Coal Diver Everything you wanted to know about coal, but were afraid to ask.

This is a text-only version of the document "Black Mesa - Permit Revision Application - Ch18 and up - 2004". To see the original version of the document click here.
CHAPTER lE INDEX

Page

Introduction Ground Water Interruption of Ground-Water Flow and Drawdown Removal of Local Wells and Sprlngs Containment of Pit Inflow Pumpage Impact of Replaced Spoil Material on Ground-Water Flow and Recharge Capacity Impact of Replaced Spoil on Ground-Water Quality Interception of Wepo Recharge to the Alluvial Aquifer by Pits Interception of Channel Runoff Recharge to Alluvial Aquifers by Dams and Sediment Ponds Truncation of Portions of the Alluvial Aquifers by Dams Effects of Altered Wepo Aquifer Water Quality on Alluvial Aquifer Water Quality Mining Interruption of Spring Flow Impact of Peabody Wellfield Pumpage on Regional Water Levels and Stream and Spring Flows Effects of Induced Leakage of Poorer Quality Water From the Overlying D-aquifer System on N-aquifer Water Quality Impacts of Wash Plant Refuse Disposal on Ground Water Flow and Quality Surface Water Effects of Dams, Sediment Ponds and Permanent Internal Impoundments on Runoff and Channel Characteristics Effects of Dams, Sediment Ponds and Permanent Internal Impoundments on Downstream Users Effects of Dams, Sediment Ponds and Permanent Internal Impoundments on Stream-Water Quality Effects of Stream Channel Divisions on Channel Characteristics and Runoff Water Quality Effects of Culverts at Road Crossings on Stream Runoff and Water Quality Removal of Pre-existing Surface Water Structures

1

1

1
30

30

86

89 91

Revised 11/21/03

INDEX (Cont. )

Effects of Runoff From Reclaimed Areas on the Quantlty and Quallty of Streamflow The Impact of the Reclamation Plan on the Stablll~yof Reclamed Areas Summary Literature Clted

LIST OF FIGURES
A

Paqe

Figure 1

Maximum Water-Level Drawdowns in the Wepo and Alluvla! Aquifers as a Result of Combined Pit Inflow Pumpage And Locations of Private Wells and Springs in Relation to the Drawdown (23) Map

Figure la

Projected 5-, 20-, and 40-foot drawdown contours for N99 at 2013

Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16

Current and Former Model Boundaries Generalized Schematic of the Hydrologic Cycle on Black Mesa Measured vs. Simulated Water Levels Through 1996 - BM-1 Measured vs. Simulated Water Levels Through 1996 - BM-2 Measured vs. Simulated Water Levels Through 1996 Measured vs. Simulated Water Levels Through 1996
-

BM-3 EM-4

Measured vs. Simulated Water Levels Through 1996 - BM-5 Measured vs. Simulated Water Levels Through 1996
-

EM-6

Measured vs. Simulated Water Levels Through 2000 - BM-l Measured vs. Simulated Water Levels Through 2000 - BM-2 Measured vs. Simulated Water Levels Through 2000 Measured vs. Simulated Water Levels Through 2000 Measured vs. Simulated Water Levels Through 2000 Measured vs. Simulated Water Levels Through 2000
-

BY-3

EM-4 BM-5 BM-6

Simulated Drawdown in the N Aquifer, Scenario J and K in 2002 (50 ft interval)

Figure 17

Simulated Drawdown in the N Aquifer, Scenario J and K in 2007 (50 ft interval)

Figure 18

Simulated Drawdown in the M Aquifer, Scenario J in 2028 (20 ft interval)

75

Figure 19

Simulated Drawdown in the M Aquifer, Scenario K in 2028 (20 ft interval)
76

Revised 12/21/03

LIST OF FIGURES (Cont.)

Figure 20

Channel Cross Section for Moenkopi Wash on Leasehold Used for Flow Loss Computations Down to the Town of Moenkopi 101 114

Figure 21 Figure 22

Climate and Sedlment Yield Comparison of Suspended Sediment Rating Curve at Site 16 with SEDIMOT I1 Sediment Load Predictions

118

LIST OF TABLES
Page

Table Table Table Table Table Table Table

1 2
3

Pit Inflows by Year for N-10 Pit Inflows by Year for N-11 Pit Inflows by Year for J-1/N-6 Pit Inflows by Year for N-14 Pit Inflows by Year for J-16 Pit Inflows by Year for J-19/J-20 Pit Inflows by Year for J-21 Estimated Annual Inflow for Pit N-99 and Length of Time the Base of Pit is below the Pre-mining Water Table

2
3 4

4

7 9 10 13

5
6
7

Table 7a

Table

8

Projected Pit Inflow Drawdowns at Well Locations Versus Measured Water Level Ranges at Alluvial and Wepo Monitoring Wells and Static Water Levels At Local Wells

Table

9

Sediment Ponds and Dams to be Used to Contain Pit Pumpage

Table

10

Summary of Acid and Neutralization Potential for Cores in Mining Areas Projected to Intercept the Wepo Aquifer

Table

11

Summary of Dissolved and Total Trace Metal Concentrations in Portions of the Wepo and Alluvial Aquifers Below Mining Black Mesa Leasehold (1986-2002)

Table

12

Downgradient Wepo and Alluvial Well Chemistry vs Livestock Standards

Table

13

Chemical Parameters and Concentrations at Spring 97 Which Exceed Livestock Drinking Water Limits

Table

14

Simulated Peabody Pumping Rates for Two Predictive Scenarios

LIST OF TABLES (Cont. )

Page

Table

15

Effects of PWCC Pumping on Water Levels in Selected Wells, end of 2002 71

Table

16

Effects of PWCC Pumping on Water Levels in Selected Wells, end of 2007 74

Table

17

Effects of PWCC Pumping on Water Levels In Selected Wells, Scenario J 77

Table

18

Effects of PWCC Pumping on Water Levels in Selected Wells, Scenario K 79

Table

19

Simulated Reductions in Discharge (acre feet per year) to Streams, Scenarios J and K, 2007 80

Table

20

Simulated Reductions in Discharge (acre feet per year) to Streams, Scenario J, 2029 and 2039 82

Table

21

Simulated Reductions in Discharge (acre feet per year) to Streams, Scenario K, 2029 and 2039 83

Table

22

Average Concentrations of Major Ions from D and N Aquifer Wells On or Near the PWCC Leasehold, and Calculated Contribution From the D Aquifer Based on Chloride Concentrations

Table

23

Maximum Predicted Sulfate Concentrations (mg/l) Resulting From PWCC Pumping, 1956-2039

Table

24

Measured Annual Runoff at PWCC's Continuous Flow Monitoring Sites and at the USGS Streamflow-Gaging Station 09401260, Moenkopi Wash at Moenkopi, Arizona

Table Table

25 26a

Drainage Areas and Estimates of Annual Runoff Summary of Impounded Surface Runoff in MSHA Dams and Sediment Ponds by Year (Acre-feet)

Table

26b

Discharge Hydrograph Output from SEDIMOT I1 Run for 644 Acre Foot Flow Volume on Moenkopi Wash

Table

26c

Channel Bed Infiltration Loss for Each Hour of Flow over the Channel Bed Area Between the Leasehold and the Town of Moenkopi

Revised 11/21/03

LIST OF TABLES (Cont.

Page

Table

27

Mean Concentrations of Selected Chemical Parameters Measured in Permanent Internal Impoundments on Reclaimed Areas on Black Mesa (1986-2002)

Table

28

Mean Concentrations of Selected Chemical Parameters Measured at Stream Station Sites on Black Mesa (1986-2002)

Table

29

Exceedences of Livestock Drinking Water Limits at Permanent Internal Impoundments (1986-2002)

Table

30

Exceedences of Livestock Drinking Water Limits at Stream Monitoring Sites - Rainfall Runoff (1985-2002)

Table

31

Summary of Probable Hydrologic Consequences of the Life-of-Mine Mining Plan Black Mesa and Kayenta Mines

LIST OF ATTACHMENTS

Attachment 1 Attachment 2 Attachment 3

Values Used in Calculating Pit Inflow Documentation of Program MINE 1-2 "Wash-Plant Refuse Disposal Hydrologic Impact Evaluation Report, Black Mesa Mine Complex, Kayenta, Arizona"

Revised 11/21/03

CHAPTER 18

PROBABLE HYDROLOGIC COI.1SEQUENCES

Introduction

This chapter contains a discussion of the probable hydrologic consequences of the life-ofmine mining plan upon the quality and quantity of surface and ground water for the proposed permit and adjacent areas. is determined. The significance of each impact or potential impact

The determination of significance has been made considering the Impact of (1) the quality of the human environment; (2)

any probable hydrologic consequence on:

any critical habitats or important plant species; or (3) any threatened and endangered wildlife species within the proposed life-of-mine permit and adjacent areas.

Ground Water

Interruption of Ground-Water Flow and Drawdown.

A comparison of five year average Wepo

water level contours and isopach maps which show pit bottom contour elevations for all areas to be mined, along with review of historic and recent records, indicates that portions of the J-1/N-6, N-2, N-7, N-10, N-11, J-16, 5-13/20 and J-21 pits have already or will intercept the upper part of the Wepo aquifer for some period during the life of the mining areas. Review of Wepo water level contours developed from recent data (1995-2000)

and actual field observations during mining indicates that pits in the J-7, 5-23, and M-14 mining areas will not intercept the Wepo aquifer. Flow in the portions of the Wepo

aquifer truncated by overburden and coal removal will be intercepted since the groundwater gradient will rapidly orient itself in the direction of the sinks (pits). Previously developed estimates of Wepo ground-water inflow to the above identified pits are presented in Tables 1 through 7, respectively. These estimates were prepared assuming (1) the interception (2) the drainage of

that the total inflow would be derived from two principal sources: of pre-mining flow rates under a natural hydraulic gradient; and

ground water from storage in the aquifers.

It is assumed that the major portion of the

Wepo ground-water inflow would be derived from lateral flow along bedding planes and fractures. Upward leakage from underlying aquifers was assumed to be negligible.

Two different techniques have been used to estimate the rates of groundwater 1nt:ow

Into

the pits, depending on the technology available at the time the estimates were developed. Approach A was used for pits J-1/N-6, N-10, N-11, N-14, and J-16. This approach,

C

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I r a

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N . N

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.

m m (

.

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.

n m .

.

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.

-

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.

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N N

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described in more detail below, sums flow rates calculated from equations for steady flow under a hydraulic gradient, and transient, confined flow toward a linear drain

(representing the sides of an approximately linear cut) and toward a well (representing the ends of the cut). The second approach (Approach B) was developed later, and applied

to J-16, J-19/5-20, and J-21 in previous versions of this chapter, and to N-99 in the current version. This approach can be used to calculate inflow under unconfined and/or

confined conditions.

Approach A

-

Aquifer and pit characteristics and the definitions of terms used in pit Pre-mining flow calculations are based

inflow calculations may be found in Attachment 1. on the following form of Darcy's law: Q
=

TIL

Where :
Q
=

Quantity of water flowing through the aquifer at the proposed highwall locations In gal. /day.

T I L

= = =

Transmissivity of the exposed aquifer in gal./day/ft. Natural hydraulic gradient in ft./ft. Length of aquifer exposed in the highwall normal to the natural hydraulic gradient in ft.

Aquifer testing at Wepo monitoring wells indicates that water in the Wepo aquifer is under some confining pressure. and act as aquitards. Some of the coal seams have very low hydraulic conductivities Water in the alluvium is believed to be in both unconfined and Those units in the Wepo aquifer

confined conditions depending on depth and location.

believed to transmit water are most of the coal seams and sandstone units below the prevailing water level. Alluvial ground water is assumed to flow from the entire

saturated thickness of the alluvium.

In Approach A, the removal of ground water from aquifer storage was calculated using two equations; one to compute the radial component of inflow to the ends of a plt and the other to compute the linear component of inflow to the longitudinal sectlons of the plt. Radial inflow to each end of the pit was calculated using the following constant drawdownvariable discharge equation (Jacob and Lohman 1952 and Lohman 1972, pp. 23-24).

Where :

Q
T

=
=

Radial discharge into one end of the pit in ft3/day Transmissivity of the exposed aquifer in ft2/day Storage coefficient Drawdown in the aquifer at the pit face in ft.
=

S =

s
r,

=

Radius of the pit opening in ft.; equal to k the width of the initial box cut
=

G(a)

The G function of

CY

(see Lohman, 1972, p . 23)

t

=

Time since discharge began in days

The linear portion of inflow from aquifer storage was calculated

using

the constant

drawdown-variable discharge drain equation derived by Stallman (Lohman, 1972, pp. 41-43):

Where:

q

=

Discharge from an aquifer to both sides of a drain per unit length of drain in ft2/day Storage coefficient

S =

s = Drawdown in water level at drain in ft.

T
t

= =

Transmissivity of exposed aquifer in ft2/day Time since drain began discharging in days

With confined aquifer conditions, lowering of the water level occurs with the lowering of hydrostatic head. The release of water from aquifer storage under confined conchtions is

small per unit area, because it is only a function of the secondary effects of water expansion and aquifer compaction. After some length of exposure, the hydrostatic head may Further declines in the water

decline far enough that the aquifer becomes unconfined. level would then be accompanied by

significantly greater quantities of ground water

discharge per unit area.

It is assumed that during the life of the pits, ground water

flow in the affected portions of the Wepo aquifer will remain under confined conditions or that the unconfined area would only extend a short distance from the pit.

The equation for radial inflow assumes that a constant concentric head surrounds each end of the pit. The actual situation representing radlal flow to the ends of :he
p l t can be

described as an arc of a circle whose center coincides with the center of the pit.

If "r"

is the arc of the circle intersected by the pit ends, then:

should approximate the actual radial discharge into the ends of the pit

The variables used in the above-mentioned equations were determined as follows: 1. Transmissivity and storage coefficients were determined from aquifer tests and

the thickness of the portion of the aquifer being intercepted. 2. Gradients were determined from water level contours of the Wepo aquifer (Drawing

No. 85610). 3. Drawdowns at the pit face ranged frorn 3 . 9 to 13.4 ft./day using the calculation

technique derived by McWhorter (1982, p. 28).

4.

Pit lengths, lengths below water level and the number of days wne~n cjrnuila wacer

discharges into the pit were determined by overlaying pit bottom isopachs, annual pit disturbance maps, and Wepo water level contour maps. To date, no mining pits have directly intercepted the alluvial aquifer. occur, the previously described pit discharge equations require Should this ever the following

modifications.

Ground water through flow in the alluvial aquifer will be calculated frorn:

Q

=

PIA

Where : Q
=

Quantity of water flowing through the aquifer into the ends of the pit in gal./day Permeability of the exposed aquifer in gal./day/ft2 Natural hydraulic gradient in ft./ft. Average cross sectional aquifer area through which the flow occurs in f' c

P I A

=
=

=

Ground-water contribution from storage was calculated using the linear and radial flow equations with the following modifications:

Where :
s o = Observed change in water level in the mine pit

b

=

Saturated thickness of the exposed aquifer prior to pit development and dewatering

17

Revised 10/15/99

A possible additional source of ground-water inflow is induced recharge from the alluvial
aquifer where the water level in the alluvial aquifer is at a higher elevation than the pit bottom. Trial computations were performed using the average flow veloclty equation

described by Lohman (1972, pp. 10-11):

Where :

v
K

= =

Average flow velocity in the aquifer in ft./day Hydraulic conductivity of the permeable unlts in the segment of th.2 Nepo Formation the induced recharge would have to flow through before reaching the pit in

that

ft./day.

AhlAI

=

Ground water gradient between a chosen elevation in the aquifer at the highwall

and the recharge boundary in ft./ft.

8

=

Porosity of the permeable units of the Wepo aquifer.

Pit inflow estimates were

determined

for that portion

of

the

total p ~ tlength and Calculations

associated time intervals that each pit was assumed to be below water level.

for each component of inflow were based on the sum of daily values, which Incorporated a continually increasing pit length. Each component of inflow from the Wepo aquifer as well

as the totals of all inflow components for each year are presented in Tables 1 through 4.

Trial computations suggest that the hydraulic conductivity of the Wepo Formation is so low that induced recharge cannot reach the pit before one or two rows of spoil have been placed back in thus precluding the induced recharge from ever reaching the actlve pit.

Approach B - This approach

G J ~ S developed

to be able to calculate inflow rates under

confined or unconfined conditions.

If the confined option is selected, it is assumed that The

conditions are initially confined, but can become unconfined as water levels decline.

flow equations for confined and unconfined conditions are solved by numerical integration. The algorithm uses information on the rate of pit advance to calculate the daily inflow, and reports the inflow on an annual basis. However, it does not consider the effects of

antecedent dewatering, and therefore tends to conservatively overestimate the 1nfloi.i rate. This approach is described in detail in Appendix 2. This method was used to predict

inflow rates for J-16, J-19/J-20, and J-21 (Tables 5 through 7).

Revised 11/21/03

The following procedures were used and assumptions made in estimating inflow to the N99 pit for calendar years 2005-2013:

Wepo wells in the area surrounding the N99 pit were selected, and recent water level data were evaluated to determine brhether water table elevations had changed significantly from those used in the calculation of the 1985 water-table map. The

Wepo wells evaluated include: 38, 39, 40, 41, 42, 43, 44, 49, 52, 53, 54, 159, 178. Data available through May of 2003 were used in this evaluation.

Although there were obvious trends in the data for the majority of the 13 wells, the most recent data point was used in this evaluation, since this should be most

representative of the water table at start of mining in N99.

These data were compared As a result of these Map, has been

to the 1985 water table map, and revisions made as necessary. comparisons, Drawing No. 85611, 2003 Wepo Water Level

Contour

constructed (see Volume 23, PAP) .

The May 2003 water-table map was then compared with the anticipated elevations for the bottom of the N99 pit, and a 'difference' contour map was constructed that The

identified those areas where the 2003 water table was above the bottom of N99.

difference map indicates that the water table will be above base of pit along the majority of the eastern boundary, and in the northwestern sectlon of N99 ( l n the area between pits N11 and N6). for Calendar Years The difference map was then overlaid on the projected cuts which indicated that only those cuts in the Cuts to

(CY) 2005-2013,

northwestern section of the pit will encounter water within this time perlod.

be completed in CY2005-2007 are all located within the southwestern section of N99, and will therefore encounter minimal water. In Calendar Years 2008-2013, cuts will be

made both within the southwestern section of N99, and in the northwestern section where water inflow to the cuts is expected.

The analytical code Minel-2-3 was used to estimate the amount of flux entering the cuts in the northwestern section af N99 for CY2008-2013. [Minel-2-3 is a modification

of Minel-2 allowing pit geometry information to be input yearly, rather than using a single set of values for the entire mining period.] selected values used as input to the code include: o The Wepo was simulated as confined, based on the lithology of the General parameters, and the

formation, and the low values of storage coefficient determined from aquifer tests.

Revised 11/21/03

o

The

hydraulic

conductivity

was

set

to

0.03432

ft/day,

which

is

the

geometric mean of the 24 hydraulic conductivity values for Wepo wells listed in Table 32 (Chapter 15, Hydrologic Description, PAP). conductivity value was not used, since this weighted The arithmetic average the calculated value

towards the fewer, significantly higher values of conductivity, and would have overestimated this parameter. o The regional hydraulic Gradient (0.011) was estimated from the May 2003

water-table map. o A conservative value for the storage coefficient (1x10-" was estimated Use of a lower value

from the larger of the two values presented in Table 32. would result in lower values of inflow.

The remaining parameters are specific to the cuts within each calendar year, and include: saturated area; average width of cut; average saturated thickness, days open, and whether this was the first cut in the pit both sides of the initial cut only). (inflow is assumed through

There are two components that contribute to inflow into the cuts: flux controlled by the regional hydraulic gradient water in storage (termed
Qdrainage

(termed

Qnatural

in the code), and flux from

in the code).

The code assumes that the regional

hydraulic gradient, and therefore the regional flux component, is perpendicular to the long axis of each cut. This assumption is generally valid for the southern

two-thirds of the cuts located within the northwestern section of M99; however, the gradient is not perpendicular in the northern one-third of the cuts. In this area, groundwater discharge into the cuts will be less than if the gradient was perpendicular, and a correction factor must be applied to decrease the inflow appropriately dividing line (this is done outside of the code). was identified between these two Therefore, an approximate areas, separating Area A

representing the northern one-third of the cuts, from Area B representing the southern two-thirds of the cuts, and the area, saturated thickness, and days open parameters were calculated separately for the sections of the cuts located within areas A and B. The correction used to calculate the regional component of inflow

to the cuts in Area A is:

Corrected

Q n a t u r a= Q n a t u r a ( * l l [width

of cut]*sin(alpha) + [length of cut]*cos (alpha)

Alpha is the angle between a line perpendicular to the length of the cut, and the regional hydraulic gradient. The first component within the parentheses

20

Revlsed 11/21/03

represents flux across the end of the cut, and the second component represents flux across the length of the cut. Maximum inflow to the cuts occurs when the

regional hydraulic gradient is perpendicular to the length of the cut (angle alpha is 0 degrees in the above equation), and minimum inflow occurs when the gradient is parallel to the length of the cut (angle alpha is 90 degrees flux across the end of the cut only).
-

this results in

The regional hydraulic gradient is approximately parallel to the cuts in CY10-13, indicating that the regional flux component is minimal and is simulated as

occurring across the end of the cuts only. north of the dividing line.

The cut within CY08 does not extend

For the cuts in CY09, an angle of 45 degrees was used

to calculate the regional flux component.

Total

lengths year

for all cuts within were measured and

the northeastern summed in

section of N99 and total

for each were

calendar

ArcView,

areas

calculated.

These were used to calculate average widths for each of the cuts as

input to Minel-2-3.

Output from Minel-2-3 includes values for and B.

Qnatural,

Qdrainags,

and Q t c t e l for Areas A

For each of the cuts in Area A, a corrected

Qnatural

value was calculated using
Qtotal

the equation above, this value was added to Q,i,i , C The corrected corresponding
Qtotal Qtotal

and a corrected

determined. the

values were

summed for each calendar year, and added to

values for that calendar year from Area B to derlve a total flux

per calendar year.

Results for N-99 are presented in Table 7a.

[This nomenclature was adopted to avoid The predicted inflow

changes in table number throughout the remainder of this Chapter.]

varies from year to year because of changes in the length of the pits beneath the water table, and the estimated depth below the water table. In addition, drainage from two

directions is assumed for the first year (2008), but from only one side in later years. The maximum estimated rate, which occurs in 2008, is approximately 10 gallons per minute (gpm); the lowest rate is predicted to be approximately 2.5 gpm, in 2010.

Revised 11/21/03

Table 7a.

Estimated annual inflow for pit N-99 and length of time the base of the pit is

below the pre-mining water table

In£l o w

Total

No.

c

For all pits except N99, drawdowns in the Wepo and alluvial aquifers in the vicinity of the wet pits were theoretically projected and calculated for radial distances out to 5 feet of drawdown (see Figure 1 ) using the Theis equation and the greatest volumes of Though ground water was projected to be

annual pit inflow (see Tables 1 through 7).

intercepted by the N14 pits, this never occurred and Figure 1 has been modified to reflect this. The Theis drawdown analyses assumed horizontally contiguous aquifer units which is The permeable units

not the case, particularly in the J19/20 and J21/23 mining areas.

within the Wepo formation which will be disturbed by mining are perched aquifers in some locations (near Wepo wells 62R and 65), pinch out and/or are vertically displaced owing to some minor structure within the Peabody leasehold. Thus the actual extent of the drawdown
A 5-foot drawdown cutoff

will likely be considerably less than that shown on Figure 1.

was selected because natural water level fluctuations measured in the Wepo and alluvlal monitoring wells on the PWCC leasehold are of that magnitude.

Projected water-level changes predicted to occur because of dewatering of all the existing pits (excluding N99) are compared to historical variability in nearby monitoring wells in Table 8. Included on Table 8 are projected drawdown and historic completion and water

level information for the two local wells (4K-389 and 8T-506) which are at least partially completed contours. in the Wepo aquifer and are located within the projected 5-foot drawdown

Table 8 also includes a column with comparisons of projected drawdowns and

actual measured water levels in alluvial and Wepo monitoring wells and a column with percent of available well bore water height loss for the two local wells as a result of theoretical pit pumpage drawdowns.

Revised 11/21/03

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Maximum water levels at only two of the twelve Wepo monitoring wells within or at the 5foot theoretical pit inflow drawdown contours are greater than background or historic maximum water levels. At WEP062R, maximum water levels are 68 feet deeper than background This deepening exceeds the theoretical
maximum

maximum water levels for WEP062.

projected

drawdown for WEP062 and 62R by 3 feet. perched zones.

WEP062 appears to have been open to one or more

These perched zones are usually of limited aerial extent and can exhibit

large well bore water level changes which are not indicative of true aquifer water level changes. At WEP063R, current maximum water levels are 26 feet deeper than background or

earlier maximum water levels but are still less than the theoretical projected maximum drawdown for this well which is 38 feet.

Maximum water levels at 5 of the 21 alluvial wells within or at the 5-foot theoretical pit inflow drawdown contours are greater than background or historic maximum water levels measured at these wells. They exceed the earlier maximum levels by only 0.2 to 1.6 feet

and all drawdowns are less than the theoretical maximum projected drawdowns.

Based on the theoretical pit inflow drawdown contours, local well 4K-389 is projected to have its water level deepened by 8 feet or 13 percent of its total available water height of 61 feet. Local well 82-506 is projected to have its water level deepened by 14 feet or From the historic and current

2.7 percent of its available water height of 518 feet.

water levels at Wepo and alluvial monitoring wells in the vicinity of the two local wells, it appears likely that the projected water level declines at the two local wells will be less than that theoretically calculated. pit inflows will not be significant. The likely drawdown at the two local wells from

Estimates of drawdown caused by dewatering of N-99 were developed using the analyticalelement simulation program TWODAN, version 5.0. This program solves the groundwater flow Time-varying

equations in two dimensions based on spatial and temporal superposition. withdrawals can be simulated using wells.

The estimated annual pit inflows were tabulated

for N-99, and the average inflow rate was calculated.

The inflow into the pits was simulated by using ten wells for the submerged part of the pit based on the mining plan through 2013. These wells were distributed around the The discharge rate for each well was

perimeter of the pit and in the interior of the pit.

one-tenth of the average inflow rate, resulting in an approximately even distribution of inflow over the pit.

The geometric mean of the hydraulic conductivities determined from aquifer tests of Wepo monitoring wells (Table 32, Chapter 15, Hydrologic Description, PAP), 0.03432 ft/d was

used for the hydraulic conductivity of the Wepo, along with a specific storage value of 0.000001/ft. The Wepo was assumed to be 150 feet thick, even though it is over 300 feet This value

thick in the vicinity of these pits, because of the limited depth of the pits.

was chosen to approximate the effect of partial penetration of the pits into the saturated Wepo, and to subtract the thickness of the Wepo above the water table.

Figure la shows the simulated locations of the 5- and 20-foot drawdown contours at the end of 2013, when mining of N-99 below the water table and south of the beltline 1s scheduled for completion. Because the approach used to estimate the inflow rates does not take into

consideration the decline in water levels caused by inflow into the pit in previous years, it will tend to over-estimate the inflow rate in the later years. In addition, the

predicted inflow rates have tended to be considerably higher than observed during mining. For example, Western Water
&

Land (Water Waste and Land, 2003) noted

The total [annual] inflows for pit J-1/N-6 were projected to range from approximately 50,000 gallons in 1972 to 3,182,179 gallons In 2003. As

mining has progressed over the last several decades, it has generally been observed that pit inflows were overestimated, and in some cases no inflow has occurred at all. For example, initial mining of the southern portion

of the N-6 Pit saw enough inflow to require pumping, but subsequent mining of this pit to the north has not resulted in any observed pit inflows.

The projected drawdown that is projected (though not expected1 to occur 1s limited to a relatively small area. Drawdown in the N-99 pit is projected to be greater than 20 feet.

Based on the predicted inflow rates, the drawdown beneath Coal Mine Wash will be between 5 and 20 feet. This projection raises a question of whether discharge rates into Coal Mine The Wepo is believed to be the source of discharge

Wash from the Wepo will be affected.

into the wash downstream from where Coal Mine Wash passes beneath the overland conveyor. Peabody does not believe that there will be significant impacts on this discharge for several reasons. First, observations of pit discharge suggest that the technique

overestimates the inflow rate, as noted above. noticeable

Second, the mining of N-6 has not caused a into Coal Mine Wash. Although the

impact on the locations of discharge

baseflow of Coal Mine Wash is not measured, a reduction in discharge caused by declining water levels beneath the wash would be also manifested by downstream movement of the location of the uppermost area of discharge. of mining. This has not been observed over many years

Third, the water levels in Wepo 40, a well close to both N-6 and Coal Mine

Wash, appear to be affected more by changes in local recharge than by dewatering. 28 K e v ~ s e d lli21i03

29

Revised 1 1 / 2 1 / 0 3

In summary, Wepo water is expected to enter M99 (and other) pits.

Based on operational

experience, the inflow rates have generally been lower than predicted by the techniques described here. Similarly, the simulated drawdowns caused by dewatering are probably Monitoring wells in the immediate vicinity of pits

higher than will be encountered.

exhibit declines in water levels, but the drawdowns in other areas are likely to be low. Thus, inflow in the N99 pit is likely to be less than indicated in Table 7a, and the drawdowns are similarly to be less than portrayed in Figure la.

Removal of Local Wells and Springs.

One local well (4T-4043, completed In the Toreva

aquifer, is located within the proposed life-of-mine mining plan area. In addition,another local well (4T-403), completed in the Toreva aquifer, was removed in advance of the mining operation in the 5-7 mining area. mining at N-14. One local spring (Site #97) was removed i n advance of

The impacts have been mitigated during mining by providing alternative The two wells will be replaced with

water sources (N-aquifer public water standpipes).

ones of comparable quality and yield following the completion of mining and reclamation in the respective mining areas. impoundment (see Chapter 19) . The spring will be mitigated by retention of a permanent

Containment of Pit Inflow Pumpage.

It is sometimes necessary to pump ground water which

seeps into pits to allow work to continue and to prevent slumping of spoil piles resulting from saturation near the bottom of the pit. Several sediment ponds and large dams (see

Table 9) exist or will exist around the pits to contain all pit pumpage as well as storm water runoff and sediment from the disturbed areas up-watershed from the ponds. Referring

to Tables 1 through 7a, it can be seen that the maximum pit pumpage in any one year will be 19 to 37 acre-feet and will occur in the J-19/20 pit. Typical quantities of pit The larger dams are Reed Valley

pumpage will be on the order of 2 or less acre-feet per year.

designed to contain this additional volume of water with adequate freeboard.

Dam has been designed to impound 475 acre-feet of water and J-7JR dam will hold an estimated 700 acre-feet of water. runoff The capacity of smaller sediment ponds to contain storm

will be maintained by pumpage from the ponds. The current NPDES Permit (Chapter

16, Attachment 3) allows for pond dewatering or pond to pond pumpage.

Impact of Replaced Spoil Material on Ground-Water Flow and Recharge Capacity. open only until the coal has been removed.

Pits remain

Following the short-term impacts on the

ground-water system associated with open pits, a longer term impact is experienced due to the placement of spoil material in the mined-out pits. spoil material can occur depending on how it is placed. A wide range in permeabilities for

Revised 11/21/03

TABLE 9 Sediment Ponds and Dams to be Used to Contain Pit Pumpage

Mining Area

Sediment Ponds and Dams Containing Pit Pumpage

N10-G Series Ponds N11-A Series Ponds N13-D, -E, -F and -G Dams N11-H, - I , and - 3 Ponds Wlld Ram Valley Dain Reed Valley and JlS-A Dams Reed Valley and J7-Jr. Dams Reed Valley and J21 Dams

Revised 11/21/03

Rahn (1976) reported that spoil material replaced using a dragline in one instance and a scraper in another, yielded hydraulic conductivities of 35.3 ft./day and 0.4 ft./day, respectively. Van Voast and Hedges (1975) concluded that greater porosities and hydraulic

conductivities will result from volume changes (approximately one-fourth greater! between the spoil material in its original compacted, stratified state, and in i ~ s rzarranged state following replacement, regardless of the method of replacement used.

Spoil material will be regraded by dozers and scrapers and final contouring will be accomplished with dozers. Based on the conclusions of the above studies, the spoil it did in its original

material should have higher porosities and permeabilities than state.

The topsoil surface will be disked as part of the reclamation activity; this

procedure should further enhance the rainfall and overland flow infiltration rates.

However, regardless of the infiltration rates of regraded spoil, infiltration l n reclaimed areas will provide little or no recharge to the Wepo aquifer. The distance from the

reshaped land surface to the saturated portions of the Wepo aquifer and the limited annual precipitation preclude rainfall and snowmelt recharge other than in burn and clinker or highly fractured areas. coal fields. These areas are found adjacent to rather than in the reclaimed

The time necessary for the replaced spoil material to become resaturated and for flow patterns to be reestablished will depend on the porosity and permeability of the replaced spoil material. Recharge of previously saturated areas may take from a few years to 100 There are

years; but, the impact will be of little significance to the local well users.

no local wells completed in the Wepo aquifer in the areas to be mined and local wells which do exist in the vicinity will not be significantly impacted (See Table 8 and Figure 1). The only exceptions to this are the two Toreva wells (4T-403 and 4T-404) which are

discussed in the previous section "Removal of Local Wells". The maximum drawdowns will be at specific points within individual pits in a particular year and are estimated to range from 14 feet to 115 feet with the greatest drawdown in the J-16 and J-13 pits. Following

the resaturation period, ground-water levels will recover to near premining levels.

Impact of Replaced Spoil on Ground-Water Quality.

The replacement of spoil material in

the areas of the pits where portions of the Wepo aquifer and in one case, the alluvial aquifer, are to be removed will have a long-term, localized impact on the ground-water quality in these areas. Two types of chemical reactions will probably occur as the spoil
-

resaturates resulting in a change in the local ground-water quality oxidation and reduction of sulfides and organic sulfur. 32

dissolution and

Revised 11/21/03

The

first

chemical

reaction

will

be

an

increase

in the major

ions as

a

result

of

dissolution of readily soluble materials in the spoil.

Varlous leachlng processes accing from ::ne permeable In i in contrast, a

over geologic time remove most of the readrly soluble constituents unsaturated considerable and saturated of units soluble in the undisturbed may overburden. remain

quantity

constituents

still

the

relatively

impermeable strata, such as the finer grained clay, siltstones and shales.

Fracturing and

mixing of materials during pit excavation and reclamation exposes many new chemically reactive surfaces and mineral constituents that may readily release ions to the ground water during resaturation.

Studies performed by Van Voast et al. (1978) and McWhorter et al. (1979) in western mine spoils suggest that increases in TDS from 50 to 130 percent could be expected in the disturbed portions of the Wepo aquifer following resaturation of the spoil material.

Based on the Wepo aquifer water quality types, the more soluble salts (principal ions) that would account for these increases in TDS are Ca, Mg, Na, SO4 and HC03.

On a related matter, Montana Department of State Lands personnel have notlced in their review of mine overburden data that materials with high salinity are qenerally quite shallow (less than 15 meters). Normal dragline operation would generally place some of This mining practice could

the near surface overburden in the lower portions of the pit.

cause the placement of some of the more saline materials in the resaturated zone and result in a greater degree of ground-water degradation.
A review of overburden core data

for portions of the pits that will intercept the Wepo aquifer (N-6, N-10, N-11, N-14, N99, J-16, J-19/20 and J-21) indicates that there are no significantly high conductivity zones in the overburden material. Therefore, significant salinity increases are not expected in

resaturated graded spoil on the Black Mesa leasehold.

The second principal chemical reaction that occurs in spoil material and could affect ground-water quality is the oxidation and reduction of sulfides and organic sulfur. the west, waters which contact spoil are rarely acidlc. In

Acid zones will probably form In

the spoil; however, sufficient carbonate materials and alkaline salts are available to neutralize acid production resulting from the oxidation of sulfides.

Cores

from within or immediately

adjacent

to the wet portions

of the pits have been The overall

analyzed to determine the acid potential of the overburden (see Appendix E).

acid-forming potential of core material involves a comparison of the acld potential and the neutralization potential expressed in terms of tons of CaC03 required per 1000 tons of material for neutralization (acid potential) and tons of CaC03 excess per 1000 tons of 33 Revised 11/21/03

material

(neutralization potential).

Table 10 is a summary of:

(1) the percent of the

total core that is comprised of material ~11th acid potential; (2) the mean weighted acid potential; and (3) the mean weighted neutralization potential. Cores from within or

adjacent to wet pits, and new cores (2003) drilled in the J2, J4, JG, 39, J14, 515, 323, N9, N12, and N99 coal resource areas are also included. Only 1 core; Core U30356EO ln the

N-9 mining area had a higher mean weighted acid potential. excess (CaC031 neutralization potential.

P.11 other cores ;ndlcate

The neutralization of the acid produced from the

oxidation of sulfides and sulfates does have an adverse water quality related side effect. In the process of the carbonate minerals reacting to achieve neutralization, there is increased dissolution of alkaline salts and consequently elevated TDS levels.

Considerable controversy surrounds the potential activity of the different forms of sulfur and the significance of organic sulfur. In western mine settings as much as 70.A of the According to Doilhopf (1984),

total sulfur analyzed has been found to be organic sulfur.

organic sulfur when oxidized produces approximately one-third less acid than the sulfide forms of sulfur in a low
(

<4)

pH environment.

A comparison of total sulfur versus

pyritic sulfur in cores taken on Black Mesa suggests that organic sulfur is approximately 20 percent of the total sulfur. In this comparison it was assumed that only the above two Whether it is pyritic or organic sulfur, not Considerable research remains to be dons

forms comprised the total amount of sulfur.

all the forms of either will react to form acid. in this area.

Oxidation of sulfides primarily occurs above the water table in the zone of water level fluctuations or in zones of significant infiltration of precipitation. As was explained

previously, significant recharge will not occur to the aquifer through the spoil material, so the potential of this as a mechanism for additional leachate movement and acid

production on the leasehold is minimal. range from 2 to 3 feet or less.

Also, the typical Wepo water level fluctuations

This does not constitute a significant zone in which

alternate weathering and leaching of ions could occur.

Below the water table, less oxygen may he available than in the overlying unsaturated vadose zone resulting in less sulfide oxidation-reduction increases in salinity or acidity of the water. Pionke and Rogowski (1979) state that water has an ovygen diffusion

coefficient four magnitudes less than for sulfides in air.

The opportunity exists during

the mining process to minimize the oxidation of pyrites and the productlol? of sulfates by burying localized pyritic zones in the postmining saturated zone. Sulfide reduction may

be the dominant process occurring below the water table if substantial popuiatlons of sulfate reducing bacteria are present. No information exists regarding the posslblllty of

the presence of these bacteria on the leasehold. 34

TABLE 10 Summary o f A c i d a n d N e u t r a l i z a t i o n P o t e n t i a l f o r C o r e s i n M i n i n g A r e a s P r o j e c t e d t o I n t e r c e p t t h e Wepo A q u i f e r

Overburden C o r e No

% of C o r e With Negative P o t e n t i a l

Mean Weighted Acid P o t e n t i a l (Tons CaCO; Needed for Neutrality per 1000 Tons M a t e r i a l )

E!ea!l Welghteci Meutrall:atio!l Pot~nrlai ( T o n s C:aCO, E:,.cess u e r 1000 Tons M a t e r i a l )

J 2 Mining Area 30362E0 J 4 Mininq A r e a 30359E0 J 6 Mining Area 3036630 J 9 Mining Area 30364E0 514 M i n i n g A r e a 30360E0 J15 Mining Area 30363E0 N6 M i n i n g Area 21104C 23163C 23164C 23165C 23166C 24093C 24094C 24095C 24096C 24097C 24098C 24099C 24400C 24401C 24402C J 1 6 Mining A r e a 23146C

J19 Mining Area 24406C 24407C 24408C 24418C J 2 1 Mining A r e a 24403C 24404C 24405C J 2 3 Mininq A r e a 30365E0 N9 M i n i n g A r e a 30355E0

TABLE 10 (Continued) Summary of Acid and Neutralization Potential for Cores in Mining Areas Projected to Intercept the Wepo Aquifer
% of Core With Negative Potential

Overburden Core No.

Mean Weighted Acid Potential (Tons CaCO; Needed for Neutrality per 1000 Tons Material)

Mean Weighted Neutralization Potential (Tons CaCO? Excess per 1000 Tons Material)

N10 Mining Area 21099C 21100C 21101C 30354EO N11 Mining Area 26272C

N12 Mining Area 30370EO N14 Mining Area 26269C 26271C N99 Mining Area 30351E0 30352EO 30353EO 30368EO 30369EO 30381EO

Revised 11/21/03

A final concern associated with the oxidation and reduction of sulfides and sulfates is the mobilization of trace metals in the ground-water system. compared column leach extracts with spoil water quality. Dollhopf et al. 11979, 1981)

They found that the statistical

means and ranges for the comparisons between column leachates and water from spoil wells often differed by as much as a factor of ten. were comparable to well water Though they did state that column leachates to a degree, they allowed that these

concentrations

correlations would have to be made at many mines with contrasting chemical conditions in order to verify the usefulness of this method for judging which overburden materials would be most suitable for aquifer reestablishment.

Evaluation of cores taken in the N-11, N-14, J-16, J-19/20 and 5-21 mlning areas for B, As, Se, Mo, Hg, Cu, Cd, Cr and Zn indicates chat there are not hlgh co:;csntraclons of any of these chemical constituents in the overburden material. During the oxidation and

reduction stages of the sulfide zones in the saturated portions of the pits, trace metals will be alternately taken into solution as the pH drops and precipitated out as the acid is neutralized and additional alkali salts go into solution. Total recoverable metal

analyses performed on Wepo and alluvial ground-water samples collected at below-mining monitors also support the core chemistry. Wepo and alluvial ground-water trace metal

analyses presented in the annual "Hydrological Data Reports" and summarized in Table 11 indicate that both the dissolved and total recoverable concentrations of trace

constituents at monitoring sites downgradient of wet pits are typically well below the livestock drinking water limits.

The

above

discussion

has

addressed

the

sources

of

potential

ground-water

quality

degradation.

In order to assess the significance of this potential

degradation, the Table 12

historic and potential uses of the Wepo and alluvial ground water is considered.

is a summary of the principal constituents in both aquifers that render the water sources unsuitable for livestock drinking water. either at or in the immediate vicinity Wepo and or alluvial aquifer. sources. Those monitoring sites chosen for Table 12 are (downgradlent) of a pit that will intersect the

Livestock drinklng water limits were taken from three

Tribal water quality standards (NNEPA, 1999; Hopi, 1998) were principally used

and other livestock standards ( F , N03, NO?, and TDS) recommended by the National Academy of Science (NAS, 1974) and the Environmental Protection Agency (1995) were also included. All chemical parameter values listed are on water quality sampling at each site from 1986 through 2002.

The principal constituent rendering Wepo aquifer water unsuitable for use as livestock drinking water is fluoride. The N03, Se and TDS standards were also exceeded at one srte

(WEP046). Fluoride levels above 2 mg/l have been shown to cause mottling of teeth and 37
Revised 11/21/03

Table 1 1. Summary of Dissolved and Total Recoverable Trace Metal Concentrations in Portions of the Wepo and Alluvial Aquifers Below Mining Black Mesa Leasehold (1986 - 2002)
Wepo Aquifer

Chemical Constituent Arsenic (D) Arsenic (TR) Boron (D) Cadmium (D) Cadmium (TR) Chromium (D) Chromium (TR) Copper (D)* Copper (TR) Lead (D)* Lead (TR) Mercury (D)* Mercury (TR) Molybdenum (D) Molybdenum (TR) Selenium (D)* Selenium (TR) Zinc (D) Zinc (TR)

Range of Minimum Values (mv/l)

Range of Mean Values (mg/l)

Range of Maximum Values (mg/1)

Livestock Standards (mglll

Alluvial Aquifer

Chemical Constituent Arsenic (D) Arsenic (TR) Boron (D) Cadmium (D)* Cadmium (TR) Chromium (D)* Chromium (TR) Copper (D)* Copper (TR) Lead (D)* Lead (TR) Mercury (D)* Mercury (TR)* Molybdenum (D) Molybdenum (TR) Selenium (D) Selenium (TR) Zinc (D) Zinc (TR)

Range of Minimum Values (mv/l)

Range of Mean Values (mall)

Range of Maximum Values (mall)

Livestock Standards (mg/ll

* Range adjusted to exclude suspected outliers. Criteria used for identifying suspected outliers include measurable dissolved concentrations yet the pH is alkaline; dissolved concentrations higher than total recoverable concentrations; and one or two abnormally high dissolved values mixed with 40 below detection limit values.
38

Revised 1 112 1/03

Table 12

Downgradient Wepo and Alluvial Well Chemistry vs Livestock Standards

Analyte
. .

- - .- . . . . . . -. . . . . . . . . . . . . . . . . . . . -

Standard

1 0 0 7 ALW180 ALWlBl ALW182 ALW19 ALW193 ALUV197 ALUV2 9 none none ALW169 ALUV19 9 WEP0178 WEP040 WEPO.12 WEPO44 WEP04 5 WEP04 6 WEP055 WEP056 1/0/0/36 25/5/0/37 1/0/0/22 20/0/0/22 13/0/0/22 20/0/0/21 20/0/0/20 2/0/0/20 18/0/0/19 1/0/0/20 20 ALUV16 9 ALUV170 ALUV18 0 ALUV18 1 ALUV182 ALUV19 ALUV19: ALUV197 ALUV190 ALUV2 7R ALUV2 9 ALUV3 3 R ALUVBOR ALUV82 HLW83 ALUV8 8 ALUV8 9R 0/0/10/36 0/1/17/39 0/0/18/37 0/0/18/36 0/0/16/37 0/0/11/52 0/0/16/38 0/0/17/38 0/0/17/37 0/0/16/50 0/0/6/36 1/0/13/47 0/0/2/51 1/0/17/46 0/0/21/55 1/0/16/51 0/0/15/49 0/0/1/37 0/0/1/36 0/0/1/37 0/0/1/53 0/0/1/38 0/0/2/38 0/0/1/37 none none ALW199 1/0/0/37

-

NO. Sites ----Sites

--

Frequency

Exceedence Date Range

Exceedence Value Range

Exceedence Median

Aluminum, Dissolved Arsenlc, Dissolved Boron, Dissolved Cadmium. Dissolved 0.0000 50.0000 0.0000 5000.0000 0.0000

0.0000 5.0000 200.0000

-

Chromium, Dissolved Copper, Dissolved 0.0000 0.0000 2.0000 10 500.0000 Fluoride 0

0.0000

1000.0000 0

Lead. Dlssolvfd

0.0000 -

100 .OOOO

Table 12 (cont.) Downgradient Wepo and Alluvial Well Chemistry vs Livestock Standards

Analyte
. . . . . . . .

Standard

- - .....
. . . .

No. Sites Sites ----Frequency

---------

Exceedence Date Range
------....

Exceedence Value Range

Exceedence Median

Lead, Dissolved

0.0000 -

100.0000

Nitrate Nitrogen-N 100.0000 10.0000 0 none 9.0000 50.0000 6999.0000 Nitrite Nitrogen-N Ph At 25 Deg. Cent. Selenium, Dissolved Solids, Dissolved 0.0000 0.0000 6.5000 0.0000

0.0000 -

-

0

Tocal Recoverable Hg 10.0000 Vanadluin, Dlssolj.ed 100.0000 0.0000

0.0000

none

25.0000

Zlnc, Dissolved

0.0000

uncensored/between MDL&PQL/censored/no. samples, i B )

=

Between NDL&PQL range,

(c!

=

Censored range

Revised 11/21/03

skeletal

damage

in

dogs,

sheep

and

cattle.

Elevated

NO3

levels

can

lead

to

methemoglobinemia and impaired liver function, whereas elevated Se can cause white muscle disease in livestock. Principal constituents in the alluvial aquifer that preclude

livestock use are F, pH, TDS and Pb.

Consumption of lead in concentrations above 0.1 mg/l

by animals can result in deleterious affects on the central nervous system and to the animal's principal organs, as heavy metals animals. tend to concentrate in these parts of the

Livestock ingestion of water with high TDS concentrations iabove 7000 nig/l) can Those

cause diarrhea, rundown ragged appearances, weakening and eventually even death.

portions of the Wepo and alluvial aquifers potentially affected by pit interception of the Wepo aquifer do not appear to be significantly affected as eight of the twelve Wepo wells and three of the

22 alluvial wells have

always had unsuitable

livestock

water

use

potential owing to fluoride.

Also, six of the 22 alluvial wells and one of the twelve

Wepo wells have always had high TDS levels.

In summary, increases in concentrations of Ca, Mg, Na,

SOq

and HCClj

and TDS wlil occur zone. The

regardless of the nature of the spoil material placed

In the saturated

potential for acid formation and acid and trace metal migration is minimal, because of the overall buffering capacity of the overburden material. There will be some amount of

additional TDS increases as a result of the neutralization of acid forming material placed in the saturated zones. Acid formation will occur primarily in response to oxidation of Reduction of sulfates and the

sulfides in advance of the wetting front during spoil resaturation. will primarily occur following resaturation. Based on

climatic conditions

transmissivities of the material, resaturation and reestablishment of preinining ground water flow gradients could take 10 years or more. aquifer should be limited to the immediate The magnitude of the impact to either pit areas, because gradients and

transmissivities are very low.

The overall significance of this impact is minor. Wepo aquifer within the leasehold.

There are no present water users of the
(4K-389 and 1T-405) In the

In fact, only two wells

region are reported to be completed only in the Wepo aquifer inspection of the lithologic log for one of the wells

(see Chapter

17).

An

suggests

at

~t

is actually

completed in the upper member of the Toreva (155 feet of sandstone at the bottom of the well). No log could be found for the other well. Local wells are not completed in the

Wepo aquifer for two reasons; (1) the yields are too low, and ( 2 ) the quality of the water is may be unsuitable for domestic or livestock purposes

Interception of Wepo Recharqe to the Alluvlal Aquifer by Pits.

Based on Drawing No.

85610, Wepo Water Level Contour Map, ground-water flow is from the Wepo aqulfer to the

41

Revised 11/21/03

alluvial aquifer system.

Pit interception of portions of the Wepo aquifer in the P!-10, N-

11, N-6, J-16, 5-19/20 and J-21 pits can potentially cause local decline in the alluvial aquifer system. Distance drawdown projections for the combined pit pumpage (Figure 1

and Table 8) suggest portions of the alluvial aquifer system

(Reed Valley, Red Peak

Valley, Upper Moenkopi and Dinnebito alluvial aquifers) could potentially be affected to the extent that drawdowns exceed natural water level fluctuations.

It is difficult to predict the magnitude of the drawdowns as the alluvial aquifers have a large range of transmissivities and storage coefficients. Comparing this situation to the

N-7/8 pit pumpage effects on the Yellow Water Canyon alluvial aquifer (Alluvial Well 74 and 7 5 1 , it is estimated that drawdowns in the alluvial aquifer near the N-14, J-16 and J19/20 pit areas could range from 8 to 20 feet during the period of maximum combined pit interception (1980 to 1983). Also, drawing on what was experienced at the
111

1.1-7;'s

pt ',

the

alluvial aquifer drawdowns should be quite local~zedand limited mile downgradient).

?:.:rent iless than one

These impacts should be partially offset by recharge to tihe aqcifers The significance

from water impounded in Reed Valley, N-14D, N-14E, N-14F and J-16A dams.

of this impact is minimal because of the limited portions of the alluvial a q ~ ~ i f e system r affected and the absence of local use of the alluvial aquifer. As with the Wepo aquifer,

the alluvial aquifer is low yielding throughout most of the leasehold and the quality is not suitable for domestic purposes and is marginal to unsuitable for livestock use.

Therefore, water from the alluvium does not support the pre- or postming land use nor does it support any critical habitats or plant species (see Chapters 9 and 10).

Interception of Channel Runoff Recharge to Alluvial Aquifers by Dams and Sediment Ponds. Dams, sediment ponds and internal permanent impoundments will intercept the runoff from about 29 and 12 percent, respectively, of the Moenkopi and Dinnebito b~atersheds to the down drainaqe

lease boundaries.

These structures will remove some potential channel

bottom transmission loss recharge to the alluvial aquifers downstream from the structures. Downstream aquifer recharge impacts associated wlth the dams shoulcl be offset by impounded water recharge to the alluvial aquifer. The alluvial aqulfer wacer the

level

monitoring program indicates that the impact of the structures on alluvial water levels is insignificant. There is no evidence suggesting gradual water level declines in the

alluvial aquifer system over time (see Chapter 15).

Truncation of Portions of the Alluvial Aquifers by Dams.

Eight large dams have been

constructed such that the embankments cut through the entire thickness of alluvium to bedrock. The embankments are designed and constructed to be impervious. These structures A review of the

impact the alluvial aquifer system by disrupting the ground-water flow.

five-year alluvial

ground-water

level

hydrographs

(Chapter 151

indicates

that

these

impacts are of no significance probably ol.~incjto the following reasons.

All dams, !.~ith

the exception of J-7 Dam are on small tributaries, which only contribute minimal amounts of water to the alluvial ground-water system. Seepage occurs around J-7 Dam along

sandstone bedding planes. the channel reaches.

The Wepo aquifer discharges to the alluvial aquifer all along

Any localized ground-water floi.~ disruptions would be offset within

short distances below the dams.

Effects of Altered Wepo Aquifer Water Quality on Alluvial Aquifer Water Quality.

The

effects of higher TDS water from resaturated spoil in the Wepo aquifer recharging the alluvial aquifer are expected to be minimal. The pits will require anywhere from several

years to 100 years to resaturate and reestablish ground-water flow gradients because of limited precipitation recharge and very low Wepo ground-water flow rates. These same low

transmissivities will continue to limit the Wepo feed and contaminant transport Into the alluvial aquifer. In contrast, responses to snowmelt and rainfall runoff recharge are
The potentla1 for

rapid and greater than Wepo feed during three seasons of the year.

rapid dilution of elevated TDS inputs from the Wepo would be quite high during these significant recharge periods.

The significance will be minimal because, the alluvial aquifer water within the leasehold is unsuitable for domestic purposes and marginal to unsuitable for livestock drinking water. Water from the alluvial aquifer is not essential to support the postminlng land

use or critical habitats or plant species.

Mininq Interruption of Spring Flow.

To date, only eight natural and one artificial spring

of any significance (more than just a damp spot along the side of a channel) have been identified and monitored within and immediately adjacent to the leasehold.
Of these, one

spring (Monitoring Site fig71 at the northwest edge of N-14 has beein removed by mining activities (N-14 channel realignment). Reference to the statistical water quality summary

for springs in Chapter 15, Hydrologic Description, ~ndlcatesthat the '.later quality of the spring was unsuitable for livestock use. Those parameters and parameter concentrations Peabody has provided

above the livestock drinking water limits are presented in Table 13. two alternate water supplies for this spring:

(1) b~ater impounded in the M14-D dam; and

(2) two public water outlets on the leasehold.

The alternate water supplied is greater in The water supplied at the public No other springs are expected

quantity and better in quality than the spring water.

water outlets meets domestic drinking water requirements. to be impacted by the proposed mining.

Revised 11/21/03

TABLE 13

Chemical Parameters and Concentrations at Spring 97 Which Exceed Livestock Drinking Water Limits

Wean Parameter Concentration (mg/l)

Recommended Livestock ~imits' (rng/l)

Fluoride Lead Total Dissolved Solids

(1) Limits are based on Navajo Nation Science (1974), and USEPA (1996).

(1999), Hopi Tribe

(1998), National Academy of

(2) One of four TDS values was greater thar. 6999 mg/l.

Revised 11/21/03

Impact of Peabody Wellfield Pumpaqe on Reqional Water Levels and Stream and Sprlny Flows. Peabody operates a wellfield consisting of eight wells completed in the D aquifer and N aquifer (Navajo Sandstone, Kayenta Sandstone, and Wingate Sandstone) to provide water for the coal slurry pipeline serving the Mohave Generating Station and for other operational uses. Pumpage was initiated in 1969 and has averaged about 3,900 acre-feet per year

(1969-2000).

The pumping of water from the N aquifer by Peabody since 1969 has produced one of the longest term pumping tests ever. Water-level changes have been measured in wells at The rates of The result

considerable distances and in several directions from the PWCC wellfield.

pumping at the well field have been measured throughout the period of pumping.

is a data set which, if properly evaluated, provides considerable information about the aquifer, and about provide the response of the aquifer to pumping. to estimate the effects of These measurements future wacer use. also It 1s

information with which

important to use appropriate tools to interpret this lnformatiou.

Tl?e analyrlcal models,

such as the Theis, Cooper-Jacob, Hantush, or other solutions of the flow equations, while appropriate for short-term tests, are commonly not suitable for longer tests because many of their simplifications affect long-term results. reasonably short distances, and boundaries can Material properties can vary over responses to pumping.

affect aquifer

Therefore, numerical models are better tools with which to properly interpret these longterm pumping tests, and to predict the effects of future pumping. In short, monitoring

the effects of past water use provides information with which to predict future effects. This approach was first applied in the Black Mesa area In 1985 and 1987 by the USGS, through the development of a ground water flow model of the N aqulfer beneath and

surrounding the Black Mesa basin, and use of the calibrated model to predlct the effects of future pumping. of a more In 1998, consultants for Peabody started development and callbration three-dimensional model of the aquifer and incorporating more

realistic,

recently collected information; this improved model is used to predict the effects of N aquifer water use by Peabody.

The following analysis of the effects of Peabody's pumping of the N Ayulfer 1s based on data measured before and during the period of pumping, and on models based on these data. It considers the effect of pumping on drawdown at existing locations of groundwater use, groundwater discharge at springs and to streams, the structural integrity of the N

aquifer, and water quality of the N aquifer that might be affected by increased leakance of water through the overlying Carmel.

Numerical Modeling.

Several numerical models have been developed to estimate the impacts 45 1':evlsed 11/21/03

of pumping by Peabody and the tribal communities on the M Pquifer, beginning (Eychaner, 1983). Most recently, Peabody has dl;-loped a model that

in 1983 the

i!ncludes

overlying D Aquifer (PWCC, 1999). a much lesser extent than the
M

The D Aquiter is also user1 as a water r e s o u r c e ,

but to for

Aquifer.

These models are the besc ?,3oli '1va;lable

determining the individual contribution of each pumping stress on the observed or measured effects (i.e., water levels and stream flows). The models are not of sufficient

resolution to simulate flow at individual springs, but can be used to make intelligent observations of regional spring flow. Each model includes:

Development of a basic description of the real system, including geologic controls on material properties (i.e., geometry of the rock layers, deformation of the rocks,

etc.), areas and amounts of recharge and discharge, and distribution of water levels. Formulation of a mathematical description of the system to be modeled. This

formulation is based on

o

Darcy's Law

-

a mathematical expression that relates the rate of groundwater flow

to observable differences in water levels. o Mass balance
-

a

mathematical

expression that

of

conservatlo!)

of

mass.

For

a

groundb~ater-flow system, this means

flow i~nto the s:/stem

:z?shari]e)

!nust

equal flow out of the system (pumping or discharge to streams or sprlncjs) plus the change in the amount of water held or released change. o Boundary conditions
-

from storage as water

levels

mathematical statements of various conditions that exist on These require knowledge of the geometry of

the boundaries of the modeled system.

the rock formations and the processes and locations through which water enters and exits the system. o Initial conditions - description of the water levels everywhere in the system at the beginning of the model.ed time period. Development of a set of numerical values for all parameters appearing in the

mathematical formulation.

These include hydraulic conductivity, specific storage, and

specific yield, all of which may be spatially variable.

Application of a numerical algorithm that "solves" the mathematical different applied stresses. The algorithm calculates the

formulation for and temporal

spatla1

distribution of water levels and groundwater flow rates that satlsfy the mathematical model for different pumping rates, recharge rates, etc.

Each model is put through a calibration process whereby model parameters are adjusted by

46

P.evised 11/21/03

either manual or automated methods until simulated results reasonably match measurements. This usually means matching output. historic water-level measurements at wells against model

The model parameters adjusted towards calibration are typically flow and storage They are adjusted within ranges reported in the Boundary conditions such as recharge

properties of the geologic material.

scientific literature for the specific rock type.

may also be adjusted if calibration can not be achieved with the independently derlved estimates. Calibration The geometry of the flow system is typically held fixed during this process. can be performed for non-pumping (steady state) and pumplng (transient)

conditions whereby a single set of flow properties is derived to match water levels representing both conditions.

Each of the groundwater models developed for the Black Mesa area was based on the USGS's finite-difference computer codes, covered most or all of the Black Mesa Basin, included all known pumping stresses and was calibrated under non-pumplng and pumping coiici~tions using the USGS's six monitoring wells as key callbratlon targets.

The first model developed was by Eychaner of the USGS in 1983 using the computer code written by Trescott and others (1976) which simulates flow in one or two dimensions. The

N Aquifer was simulated as a single flow unit (using one model layer) in two-dimensional

space and the transient calibration period was from 1965 through 1977.

Soon thereafter,

the USGS (Brown and Eychaner, 1988) updated this model using a refined grid spacing and the USGS modeling code MODFLOW (McDonald and Harbaugh, 1988). After calibration, this Concurrently, an

model was used to predict the effects of puinpage on the flow system. independent modeling effort was begun by Peabody.

Both groups chose to simulate the floi,~ This was

system in two dimensions and to represent the N Aquifer as one flow unit.

reasonable given the N Aquifer's large regional-scale, relatively uniform and continuous nature, and its predominantly horizontal groundwater flow. The USGS (Brown and Eychaner,

1988) kept their same model boundaries while Peabody's version (GeoTrans, 1987) extended the boundaries to cover more of Black Mesa basin (Figure 21, particularly to the

southeast.

This difference in extent reflects the fact that the UsGS oniy ~ n c l u d e s the

Navajo Sandstone in the southwestern part of the model, bihile the Peabocly model also includes the Kayenta and Wingate. The USGS extended their calibration period from 1965 1985. The The

through 1984, whereas the Peabody model was calibrated from 1956 through

earlier time period (pre-1965) was chosen to simulate community pumping at Kayenta.

Peabody model also increased the number of transient calibration-target locations from six to nine. Although the two models were developed independently and differed from each

other in details, their results were similar.

48

R e v i s e d 11/21/03

In 1993, under

the auspices of Tribe,

the coal

leases and authorized Peabody

by

the Secretary of study by S. S.

Interior, the Hopi Papadopulos
h

the Navajo Nation, and

funded a

Associates, Inc. (SSPA) that reviewed the USGS model

(Brown and Eychaner,

1988) for appropriateness, application, calibration, and resulcs.

They concluded that:

"A mathematical model, such as the one constructed b y the USGS, is the only method available for separately determlnlnq lmpacts of Peabody' s

pumping on groundwater conditions in the N-Aqulfer.

This method ilhsures

consistency among the different facets of the hydrogeologic sysLem such as recharge, discharge, ground-water levels, pumping, aquifer properties and aquifer extent. Consequently, the method used in the USGS studies is a

standard method and is clearly appropriate for the purpose of evaluating impacts due to pumping by Peabody."

They

further concluded that

application of the modeling method

was

appropriate, the

calibration was reasonable, and that Peabody's impacts on surface-water features (such as streams and springs) was minimal because water was predominantly storage. Aquifer coming from aquifer

An important contribution of SSPP. (1993) towards the understanding of the N system was the development of a database for the M aquifer thac was more

comprehensive than the one used by Brown and Eychaner (1988).

Following the completion of the SSPA report and because of the concern expressed by some of the participants in the co-operative scudy, the Secretary of Interlor requescea that the USGS conduct a fresh review of the Brown and Eychaner report. The revlewer from the tlhe water budget

USGS believed that Brown and Eychaner did not sufficiently document estimates, and that the model was less credible as a result.

To evaluate this concern,

Peabody initiated a modeling study in which the sensitivity of m o d e l ~ n gpredictions to the estimated recharge rate was tested (Peabody, 1994). and Peabody models. First, this study compared the USGS

Second, it documented the conversion of both the USGS and Peabody (Hill, 1991). The converted

models to an automated calibration modeling code, MODFLOWP

USGS model was then successfully re-calibrated for pre-pumping conditions using recharge values that were 0.5, 0.75, 1.5, and 2.0 times the base recharge value used by Brown and Eychaner (1988) of 13,380 ac-ft/yr. The best agreement with water-level data occurred Pumping si~nulations were then performed, and results the model to both pre-pumplng and pumping

with the base-case recharge value. indicated the importance of

calibrating

conditions.

MODFLOWP did not have this capability.

Similar tests were performed with the

Peabody model (1987), with similar results.

In 1999, Peabody substantially revised the modeling of the flow system by developing a three-dimensional representation of the N and D .Aquifers, separated by the intervening low-permeability including Carmel Formation on (Figure 3). the model The revised three-dimensional model, model, geology,

detailed

discussions

database,

conceptual

hydrogeology, numerical modeling, and future pumping effects, are presented in the report entitled "A Three-Dimensional Flow Model of the D and N Aquifers, Black Mesa Basin, Arizona" (PWCC, 1999). are explicitly included by Each of the seven rock units that comprise the D and ;I 3.clulfers in this 7-layer model. depositional Lvloreover, the within chanijfs the
111

macerial are

properties

caused

different

environments

rock

unlts

incorporated, allowing their properties to be explicitly adjusted individually durlng the model-calibration process. In previous models, the model parameters represented a lumped The calibration period was

average for the properties of several different formations.

extended from 1956 through 1996 and the number of wells providing informarion on changes in water levels caused by pumping increased from nine to 47. This work was based on a

database that included and went beyond the one complled by SSPA (19931, in part, b ? ~adding information for the Carmel Formation and the D Aquifer, and including eleven additional years of pumping stresses, water-level measurements, and spring and streamflow

measurements.

When the 3D model was developed, it was calibrated to both non-pumping pumping

(pre-1956) and

(1956 through 1996) conditions. Temporal changes in measured water levels were The calibration process relied more

compared with changes in the simulated water levels.

on data from wells BM-1, -2, -3, -4, -5 and -6 than from other wells, becaiise (1) these wells were specifically chosen for monitoring the effects of pumping
at

the Peabody

leasehold, (2) the higher quality and greater quantity of data from the BM-series, and ( 3 ) because detailed information on pumping of community wells was not available. The

calibrated model provides good agreement with the measured changes in water levels for the BM-series wells.

An automated calibration process that used both pre-pumping and purnplng datasets was used. This facilitated the development of multiple calibrated models, each one calibrated to different estimates of recharge or other model parameters. In 1997, Lopes and Hoffman11 Their estimated Using

(1997) used geochemical data to estimate the recharge rate near Shonto.

rate was approximately one-half that proposed by Brown and Eychaner for this area.

a larger geochemical data set and a numerical transport model, Zhu and others (1998) and Zhu (2000) showed that the geochemical data are consistent with the higher, earlier

estimates of recharge rates based on hydrologic data. rates remain.

Still, uncertainty in recharge
twice,

To address this uncertainty, the model was calibrated
50

rlrst using a

f e , s c 11/21/03 ?:iel

51

Revised 1 1 / 2 1 / 0 3

recharge value similar to Brown and Eychaner's and again, using a .:slue siinilar to Lopes and Hoffmann's. In addition, two different approaches (full ET and loid
ET)

to slsnulatlng
These are

discharge in non-wash settings were used, resulting in four calibrated models.

termed FR/FET (full recharge and full ET), HR/FST (half recharge and full ET), FR/LET (full recharge and low ET), and HR/LET (half recharge, low ET) . The use of different

recharge estimates and different non-wash discharge approaches in the four calibrated models explicitly answers questions about the sensitivity of the models' predictions to uncertainty in these items. All four calibrated models matched measurements of drawdown

better than the USGS's 2D model at all but one (BM-1) of the six USGS's monitoring wells (Figures 4 through 9). Each of the four models is shown on each figure. the change in water levels, measured fro~n the last measurement. Tne figures show

The plots portray

drawdown in the usual way, such that lowering of \.later levels (increase in drawdown) is shown as the point moving toward the bottom of the plot with increasing time. definition of zero change that differs. It is the

By definition, the change 1s zero for rhe last Thus, for the purpose of

measurement, and for the last corresponding simulated value.

determining whether the model is providing good agreement with the meascreci changes i! s water levels, it is important to evaluate the trends for early times.

These four models were used to estimate impacts of Peabody and tribal pumping on the D and

N Aquifers.

Unless otherwise indicated, the term "base-case model" refers to Peabody's

FR/FET 3D model of the D and N aquifers using a recharge rate similar to that used by Eychaner (1983) and Brown and Eychaner (1988), and using MODFLOW's ET package to simulate discharge in the non-wash settings.

The 3D model was developed to improve the confidence in predictions of future effects of Peabody's pumping. The fact that the new model matched water-level ~nformatlon better

than older models, while reassuring, does not necessarily mean that the predictions will be accurate. Earlier models produced reasonably good agreement with water-level change

information available at the time of their calibration, but the agreement of measured and simulated water-level changes degraded with increasing time.

Calibration

of

the

3D model

benefited

from

the

collection

of

appro:.:imately ele%?en These data provided

additional years of data since development of the earlier ?D models.

additional, indirect information about the groundwater system through a model-development process. Groundwater models are widely acknowledged to be "non-unique". Different models

(boundary conditions, geometries, material properties, solution techniques) can produce equally good agreement with available information. results when used to make predictions. However, they may yield different

Thus, an important aspect of using models to guide
52

Re\-ised 11/21/03

Drawdown (ft)

Revised 11/21/03

Revised 1 1 / 2 1 / 0 3

Drawdown (ft)

Revised 11/21/03

Revised 11/21/03

Drawdown (ft)
--L 2

0

0

l o 0

W

P

u l

0

0

0

cn
0

-4

a 3

( D

0

0

0

Revised 11/21/03

Revised 11/21/03

resource management decisions is to evaluate whether the model results agree with data not used to calibrate the model, such as newly collected water-level data. is good, confidence in the model's predictive ability is increased. agreement is poor, the need for additional calibration work is indicated.

If the agreement
Howe.'er, if the

The accuracy of the 3D model to simulate water-level changes beyond the calibration period was tested using data collected by several organizations from 1996 through 2000. Water-

level data from the BM-series b~ellswere obtained from the U.S. Geological Survey (Thomas, B., USGS, written communication, 2001) through the end of 2000. updated. Pumping rates were also

Monthly pumpage data from each of the PWCC production wells v~ere used in the For community pumping, information was obtained from the USGS, t~ho compiles These pumping data were added to the pumping data

simulations.

information provided by BIA and NTUA. set.

Simulations were performed using four different models, as described in Peabody (1999). These four models, each individually calibrated, use two different recharge rates and two different upland (non-stream) discharge values simulated using different maximum ET rates. For the model validation tests, only the pumping rates for the period 1997 through 2000 were updated; no other changes were made.

Figures 10 through 15 provide comparisons of measured and simulated water-level changes through 2000, based on the updated pumping information, for the BM-series wells. At BM1,

the agreements of the two models using the full recharge values are better than for the two models using haYf the full recharge values. suggests a lowering of water levels. The trend of the recent measurements

Whether this is due to pumping, changes in the Earlier measurements do not The four models slmulate

instrumentation, recent climate, or other cause is not clear. suggest drawdown effects, but do indicate some variability.

drawdown effects at BM1 and are chus likely to overpredict water level changes In the future.

The four models have similar responses at Bi.12.

The simulated total change agrees well

with the measured total change, but the predicted change occurs earlier than the measured change. The rate of measured change had decreased after 1398, so that the simulated rate Stated differently, the agreement of the model

is very similar to the measured rate.

appears to have improved slightly after 1997 or 1998.

Comparison of simulated with measured values is more difficult at ~r.13 becaiise of the impacts of variable, local pumping and the resultant !iigh variability of water levels in
59

Kevised 11/21/03

U

a ,
(I)

P 3
() I

0
a ,
V)

m m

m a , 2

a.

Revised 1 1 / 2 1 / 0 3

Drawdown (ft)
2

0

I U
0

W

0

P
0

rn
0

0

m

-4 0

CO

0

CO

0

R e v i s e d 11/21/03

Revised 1 1 / 2 1 / 0 3

Drawdown (fi)

b

2.J

t L

2

0

2

N

W

Revised 11/21/03

-0

ttl s
ffl

s

m

Revised 11/21/03

Drawdown (ft)

Revised 11/21/03

BM3.

The four models track the measured changes appro:le,c model may be predicting greater drawdown from 1996 through 2000 than has occurred. another well where little change has occurred. approximately 1 m occurred after 1998.

BM3 is

A recent decline in water levels of
Continued

As with BM1, the cause is unknown.

monitoring should determine whether this will be a long-term trend, or a short-term change that might be reversed.

Data collected at BM5 between 1936 and 2000 are tracked very well by the four models, although the agreement of the full recharge, low ET model is not qulte as good as the other three. The models also agree well with the prel~ious years.

Agreement

at BM6 also continues to be excellent.

The

full recharge, low ET model,

although providing a good fit to the measured changes, simulates about 20; less change than the measured change, and less than the other three models. The rate of change

calculated by the other three models agrees very wel. with the meassred rate of chalnge. The base case model (full recharge, full ET) prooicies the best overail f l c , reflsctlng the greater effort in its calibration. Its agreement with the measured chanyes irom 1996

through 2000 (and earlier) suggests that its predictions of the changes ln water levels within the area circumscribed by the BM wells will be reliable for many years. Two of the

other three models also produce excellent agreement, and would be expected to also provide reliable predictions. but still acceptable. The fit of the fourth (full recharge, low ET) is not quite as good,

The four models match the observed water-level changes at the s:: BM monitoring r.ielis i. quite well. Extension of the model from 2D to
3D, coupled

wltn

incorporation

of

additional information, produced a pumping on the groundwater system.

framework

for evaluating

the effecrs

of

Peabody's

The framework was used to calibrate four different

models using reasonable estimates of the recharge rate and the magnitude of discharge in non-wash environments. All four of these models provide significant improvement over

previous 2D models in the quality of agreement between simulated and observed changes in water levels due The to Peabody's pumping. The predictive abillty of the models was

evaluated.

four models had been calibrated using water

level and pumplng data

collected through 1996.

In this evaluation, the water level and pumping data were updated The

through 2000, and the four models rerun without changing any other model input.

results indicated that recalibration is not warranted at this time, and are an indication of the ability of the model to accurately predict the effects of pumping by Peabody within the groundwater basin. As with all models used to guide decisions, the model should be

periodically evaluated as more data are collected, and updates made when appropriate.
66
p-..

..c~ised11/21/03

The base-case model is used in the predictive simulations presented beloh!. four models used longer pumping periods cnan s-jalcated in this PHZ

?-?sting of the

(Sceiiarro 3 ,

PWCC,

19931, and indicated that all four models produce similar results. The precllcted

C ~ ~ ~ W ~ O G J ~ S

are similar (because each model is calibrated to the same water-level and cirawdorii? dara), though not identical. also quite similar. Similarly, the predicted impacts on the discharge to streams are

Obviously, for the half-recharge cases, the slmuiared iiiscnal-ge lnto

the streams is less than for the full-recharge cases, and therefore rhe effect, expressed on a percentage basis, is slightly higher for the half-recharge cases. Because the

effects of PWCC pumping on stream discharge are predicted to be low in Scenario A for all four cases, and because the pumping plan evaluated in the PHC envisions a decrease in both pumping rates and time, only the base-case model is evaluated below. The effects of Peabody's withdrawals from the
M

aquifer have

been

simulated

using

conservative estimates of the annual pumping rate under two mining-plan scenarios (Table 14) . 2000. Peabody's annual ground water withdrawals averaged 4,176 af / y from 1996 through

Therefore, the selection of 4,400 a f / y 1s considered a censer;-ati,;e ).et reallstlc

amoiint of water withdrawal to support the current coal production races through 2007 for simulation purposes. While PWCC has not and does not relinquish or restrict any right it

has or may have to continue to utilize water from the N aquifer in accordance with the terms of its tribal lease agreements, two long-term pu~npiny
scenarios

were

simulated

(Table 14), evaluating the effect of N aquifer pumping assuming alternate Tribal source is available starting in 2005. be from a source other than the N aquifer.

that water

from an

The alternate tribal source will

In Scenario J, the alternate source provides

water for operation of both the Kayenta and Black Mesa mines through 2025, and reclamation activities at both mines through 2028. provide water in the event that water The M-Aquifer wellfield would be maintained to was unavailable from the alternate wellfield.

Maintenance of the N-aquifer wellfield is assumed to involve limited monthly pumping of each of the wells when not in regular use. af/y. For Scenario J, the maintenance pumping is 444

From 2029 through 2039, Scenario J assumes that the N-Aquifer wellfleld is used to

solely supply water to the local residents.

Scenario K is very similar to Scenario J. supply the needs of the Kayenta Mine Maintenance pumping of NP.V3, N A V 5 ,
1.lF.V6,

However, the N-Aqulfer wellflelii 1s a , j i e ::und
IJA.J4,

to

(928 af/yi, using l(lAV2,

NAV7,

and NAVS). Otherldlse

and NP.VH 1s assume ro total 217 aL./:;.

the pumping schedule is the same as Scenario J.

In both of these scenarios, it is assumed that the M Aquifer wellfield would be used to replace water from the alternate source during periods when the alternate source is not

Table 14 Simulated Peabody Pumping Rates for T ~ . i oPreclictl'.re Si.e!-!arlo-,

Scenario

Peabody M Aquifer Pumping Distribution

-997-2003 !004-2007 !008-2025

- Actual (2003 estimated) - 4400 af/y - well maintenance (444 af/y, reduced every 3 years based

In 6 month or 1 month supplemental pumping), public supply %f/y), and 6-month (2462 af/y) or 1-month 409 af/y) periods supplemental pumping to replace alternate Tribal production (alternating on a three-year cycle)
2026-2028 2029-2039 1997-2003 2004-2007 2008-2025
-

430 af/y reclamation and 75 af/y public supply

- 100 af/y public supply - Actual (2003 estimated)
-

4400 af/y Kayenta mine supply (925 af/y), well rnalntenanc.; 1211

af/y, reduced evegy 3 years base on 6 month or 1 month supplemental pumping), public supply (61 af/y) and 6-month and 1-month periods of supplemental pumping to replace alternate Tribal production (alternating on a three-year cycle)
2026-2028

- 430 af/y reclamation and 75 af/y public supply

Revised 11/21/03

available

for either 1 month

or

6 months,

every three years.

The first period

of

replacement pumping is assumed to be for 1 month in 2010. be 6 months long in 2013, three years later.

The second period 1s assumed to

This alterna~ing pattern of periodic usage
ti

of the N aquifer to replace the alternate source, either using all eight

Aquifer

ells

in Scenario J, or only 4 N Aquifer wells in Scenarlo K, is continued through 202:. The community pumping is assumed to increase at- a rate of 2.7'. per year, as desc1-:b;.d Chapter 6 of the 3D modeling report (PWCC, 1999) for the future pumping. in

Impacts of Drawdown at Community Pumping Centers.

Pumping of water from the N aquifer Drawdorin is

causes lowering of water levels or confined pressures within the aquifer.

necessary in order for water to be withdrawn from the aquifer by wells and occurs due to pumping at the Peabody well fi.eld, as well as at the communities. Howev?r, e:-:cessive

drawdown may cause wells to become unusable (e.g., if the water level during pumping of the well is lowered to the pump intake, and the pump cannot be lowered). increases pumping costs. The USGS has been monitoring water Dra1wdown also

levels in communities

throughout the basin for several years, and has estimated the drawdobln caused by pumping of water from the N aquifer.

Figure 16 shows the simulated drawdown through 2002 for the top part of the PI aquifer, using the base-case 3D model. Drawdown resulting from Peabody's pumplng
1s

cjreacest

beneath the leasehold, and is very small within the unconfined area.

The cransltion from

confined to unconfined conditions greatly llrnits draWd0~in because of the inuih qreater storage coefficient under unconfined conditions. Drawdown caused by purnplng at the

communities is also apparent.

Community drawdown is most apparent at Shor:t-o and Tuba

City, where drawdown due to Peabody pumping is essentially non-existent, but occurs at other communities as well. The model-estimated drawdown caused by pumping at the end of These wells were chosen because of their use by tiie USGS The percenLage of drawdown attributable to Peabody base-case
3D

2002 is presented in Table 15.

in the annual monitoring reports. pumping was calculated from the

modeling

results,

based

on

pumping

simulations with and without Peabody pumping. uppermost open interval were obtained

Data on the depth of the N aqulfer or reports. The drawdown

from USGS monitoring

attributable to Peabody is subtracted from this depth to estimate the available water column remaining after incorporating the effect of Peabody's pumping. This thickness

represents the drawdown available before the water level would be lob~ered to the top of the N aquifer or the top of the production interval in the well, if only Peabody had been pumping from the aquifer.

The greatest effects on water levels in 2002 are for Foresc Lai:e, Chllchlr!:i~~rc,,i'ci-i:,,;
69

?.evlsed 11/21/03

70

Revised 11/21/03

Table 15 Effects of PWCC pumping on water levels in selected wells, end of 2002

Community

we"

Depth to N Remaining PWCC Simulated PWCC or TOP Of Initial Drawdown Allocation Allocation Water Open DTW (ft) (") (ft) (%) Interval column (it) 405 1096 227 292.5 220 743.6 432 170 88 200 119 33 81 120 100 3 73% 92% 27% 23% 25% 55% 86% 47% 64 184 32 7 20 67 86 2 1136 1870 700 900 880 1870 1442 210 667 590 44 1 600 640 1060 924 38

PM3 Chilchinibito Forest Lake NTUA 1 4T-523 8T-54 1 Kayenta West PM2 Keams Canyon PMI Kykotsmovi PM6 Pinon PM2 Rocky Ridge 1OR-I 11 Rough Rock

Revised 11/21/03

Ridge and Pinon, where the estimated drawdown attributable to Peabody ranges from 64 to 184 feet. less. Elsewhere, the drawdown resulting from Peabody use of the water 1s 35 feet or

At all locations except Rough Rock, more than 440 feet of water remains above the Pumping of the well itself will cause is not available, and it is Thus these calculations

top of the aquifer as of the end of 2002. additional drawdown.

Information on this local drawdown

assumed that the local drawdown is a few hundred feet or less.

indicate that Peabody's pumping, as of 2002, will not cause sufficient drawdown to reduce the production of the aquifer by dewatering. For Rough Rock (well 10R-lll), the water

column above the top of the aquifer was only 40 feet thick before any pumping, and Peabody's pumping reduces it by approximately 2 feet. Note that this well is east of the

community of Rough Rock, where both PWCC and community-based drawdown is greater. At this location it is likely that the pump is already set below the top of the N aquifer, similar to wells in the unconfined area.

Figure 17 portrays the predicted drawdown in the N Aquifer at the end of 2007, due to PWCC and non-PWCC pumping. At this time Scenarios J and K are identical. Comparison of

Figures 16 and 17 indicate that the majority of the drawdown due to Peabody's pumping has already occurred. The primary change from the 2002 results is at the leasehold, where Near the periphery of the drawdown cone, drawdown has increased

drawdown has increased. only slightly.

Table 16 provides the estimated drawdowns due to PWCC pumping at the end of 2007.

This

represents the anticipated end of pumping from the M aquifer to supply the combined water needs of both mines and the coal-slurry pipeline. The drawdowns have increased slightly

over those at the end of 2002, but the utility of the N aquifer has not been diminished.

Figures 18 and 19 show the drawdown predicted in 2028 for Scenarios J and K.

Note that

there is significant recovery of water levels near the leasehold, as a result of the reduction in pumping rates that started in 2008. Drawdown caused by the communities Recover:; is greater

increases because of the projected increase in community water use.

for Scenario J; Scenario K assumes that the water needs at the Kayenta mlne wlll still be met by pumping of the N Aquifer.

Table 17a and 17b presents information on the predicted drawdown at the end of 2028 and 2039, respectively, due to all pumping, and Peabody's pumping (Scenario J). PWCC's pumping is assumed to stop at the end of 2028, except for a continuing of 100 af/y to local residents. In most areas, there is predicted to be significant recovery of water levels, Drawdown caused Revised 11/21/03

caused by the reduction of PWCC's pumping simulated as beginning in 2008.

72

R e v i s e d 11/21/03

Table 16 Effects of PWCC pumping on water levels in selected wells, end of 2007

Community

Depth to N Remaining Simulated PWCC PWCC Initial or Top of Excess Drawdown Allocation Allocation DTW (ft) Open Water (%) (ft) (ft) Interval Column (ft)

Revised 11/21/03

Revised 1 1 / 2 1 / 0 3

76

Revised 11/21/03

Table 17 E f f e c t s o f PWCC pumping on w a t e r l e v e l s i n s e l e c t e d w e l l s , S c e n a r i o J

Community

We"

Simulated PWCC PWCC Initial Drawdown Allocation Allocation DTW (ft) (Yo) (ft) (ft)

Depth to N Remaining or Top of Excess Open Water Interval Column (ft)

Chilchinibito PM3 Forest Lake NTUA 1 471-523 Kayenta West 8T-541 PM2 Keams Canyon PMI Kykotsmovi Pinon PM6 Rocky Ridge PM2 IOR-Ill Rough Rock
a. End o f 2028

405 1096 227 292.5 220 743.6 432 170

85 140 169 59 152 155 111 6

47% 76% 13% 20% 20% / 4 1OO 70% 37%

40 106 22 12 31 64 78 2

1136 1870 700 900 880 1870 1442 210

69 1 668 451 596 629 1062 932 38

Community

We"

Depth to N Remaining Simulated PWCC PWCC Initial or Top of Excess Drawdown Allocation Allocation DTW (ft) Open Water (ft) (Yo) (") Interval Column (ft)

Chilchinibito PM3 Forest Lake NTUA 1 4T-523 871-541 Kayenta West PM2 Keams Canyon Kykotsmovi PMI Pinon PM6 PM2 Rocky Ridge 110~-111 l~ough Rock

1

405 1096 227 292.5 220 743.6 432 1701

87 113 197 74 191 174 104 7 1

31% 60% 9% 17% 14O/0 28% 56% 28%1

27 68 18 13 26 49 59 2 1

1136 1870 700 900 880 1870 1442 21 0 1

70~ 70C 45: 59: 631 107; 95' 3t

b.

End o f 2039

Revised 11/21/03

by pumping in the indicated community wells w111 further reduce the water column thickness while the local pumping is occurring. For nearl:; ail of these biells, the renalnlng :,!aLer column is hundreds of feet thick, indicating that the M aqulfer wlll he able to continue to supply water at previous rates. Rock. The sole exception is possibly well 10P-111 near Rough

As previously discussed, this well only had a water column of 40 feet above the top Peabody's predicted reduction is approximately 2 feet, but If the drawdown

of the aquifer before pumping.

local pumping from the well would be expected to have a greater impact. due to pumping

from 10R-111 is more than 38 feet, dewatering of the aquifer in the Here, the N aquifer is approximately 600 ft thick, so occurs, will have only a minor impact on aquifer

vicinity of the well may occur. that local dewatering, if it

productivity.

The differences between Scenarios J and K are minor (Figures 18 and 19, and Tables 17 and 18). In Scenario K, there will also be recovery in nearly all areas between 2029 and 2039 In areas near the leasehold, recovery of water levels is predicted In areas where there has been limited PWCCto increase at a slow rate as the system

(Tables 18a and 18b).

to continue to occur at a moderate pace.

induced drawdown, equilibrates.

drawdown will

continue

Impacts on stream baseflow and spring discharge rates.

Because of the l l m i ~ e d drawdown

due to Peabody in unconfined areas and concentrated nature of discharge areas, the effects of Peabody's pumping on stream baseflow and spring discharge rates are expected to be small. Two-dimensional simulations previously performed by the USGS (Eychaner, 1983;

Brown and Eychaner, 1988) and by GeoTrans expectation.

(1987) provided results consistent with this

Table 19 presents the predicted effects of 2007.

pumping

on discharge i.iito streams at the end of

Thls and following tables were constructed by performing s~rn~ilatlons .: w!ilch there 1 1

is both PWCC and non-PWCC pumping, and tabulating the results (columns labeled ".411"). The simulations were repeated, but with Peabody's pumping removed. effect of Peabody's use of N-Aquifer water. The column labeled The difference is the
"'h

Total PWCC" is the

percentage reduction of the pre-pumping streamflow caused by Peabody's pumping from the beginning of Peabody's pumping in 1965 through the end of the year indicated ln the table, 2007.

For example, the simulated pre-pumping discharge lnto Moenkopi Wash was 4305.1 acre-feet per year (af/y). At the end of 2007, the simulated discharge is predicted to be reduced

Revised 11/21/03

Table 18 E f f e c t s of PWCC pumping o n b!ater lex.:els In s e l e c t e d lwells, S c s n a r l c ~K

Community
PM3 Chilchinibito Forest Lake NTUA 1 4T-523 8T-54 1 Kayenta West PM2 Keams Canyon PM 1 Kykotsmovi Pinon PM6 PM2 Rocky Ridge 1OR-I 11 Rough Rock
a.
End of 2 0 2 8

Simulated PWCC PWCC Initial Drawdown Allocation Allocation DTW (ft) (ft) (ft)
405 1096 227 292.5 220 743.6 432 170 94 158 171 59 153 161 119 6 52% 78% 14% 21 % 21 % 44% 72% 39% 48 124 24 12 33 71 86 2

Depth to N Remaining or Top of Excess Open Water Interval Column (ft)
1136 1870 700 900 880 1870 1442 210 683 650 449 595 627 1056 924 38

Community

Depth to N Remaining Simulated PWCC PWCC Initial or Top of Excess Drawdown Allocation Allocation DTW (ft) Open Water (ft) (Yo) Interval Column (ft)
91 122 198 75 193 180 111 7 1 34% '0 631 1O0/0 18% 15% 31 % 59% 30%1 31 76 20 14 29 55 66 2 1 1136 1870 700 900 880 1870 1442 21 70C 69E 452 594 631 1071 94L 3f

Chilchinibito PM3 405 Forest Lake NTUA 1 4T-523 1096 8T-541 Kayenta West 227 PM2 Keams Canyon 292.5 PM1 Kykotsmovi 220 Pinon PM6 743.6 PM2 Rocky Ridge 432 ~ R O U ~ ~ ROC^ IIOR-11 I ] 1701
b.
End of 2 0 3 9

01

Table 19 Simulated reductions in discharge (acre feet per year) to streams, Scenarios J and K,

1955

2007

Change due to Pumping

O O /

1

Revised 11/21/03

by 23.4 af/y, of which 2.6 af/y is caused by non-PWCC pumping, anci 20.8 af/y by FWCC pumping. The percentage reduction due to Peabody's pumping is estlmatecl to be 0.481. The

percentage reductions for all discharge areas are estmated to range from 0.0 to nearly 0.55.

The predicted effects on streams for Scenario J pumping in 2029 and 2039 are p r o ~ d e din Table 20a and 20b, respectively. The largest change from 2007 is the lncrease In effect This predicted decrease would not be (Table 21a and Table 21b), and the The magnitudes of these

at Cow Springs (1.15% in 2029, and 1.46% in 2039. measurable. The pumping is greater in Scenario K

effects on streamflow are slightly greater than in Scenario J.

predicted reductions in discharge are also too small to be measurable.

In

contrast

with

the

regionally

significant

discharge

areas,

the

models

dld

not

specifically evaluate the effect of pumping on individual sprlngs In non-wasi? settlngs (1) because of the difficulty of accurately on grid simula~ing these spaclng, and Impacts ,:,oi-is;cier~i?gr_hs of the limited of the

topographic

relief and constraints

(2) because

drawdown in unconfined areas caused by distant pumping.

The locations of man:;

smaller springs are determined by the geometric relationships between beds of different hydraulic properties, and by locations of fracture zones. Many of the smaller sprlngs

discharge from formations, such as those in the D aquifer, that contain low hydraulic conductivity beds. These lower conductivity beds, which are responsible for the

occurrence of the springs, will tend to isolate the springs from the effects of pumping of the N aquifer.

Further, the discharge rates of these springs are likely to be more sensitive to changes i n local recharge than to drawdown caused by distant pumping. These springs are typically located near recharge areas, and temporal changes in their discharge short-term changes in local recharge rates would be expected. rates caused by

Observations of springs

discharging from the Wepo formation on the leasehold confirm the temporal varlahllity of these smaller springs. document Tree-ring studies performed throughout the southwestern U . S.
i.>ee, for ?:-;ample,

the variability of precipitation on the scale of decades

Stahle and others, 2000).

Even if good spring flow data were available, thls variability Because of the character of these springs are expected to be

would make calibration to these data difficult. and of the groundwater

system, the effects of Peabody's pumping

undetectable, and very small regardless.

Measurement of pumping effects on these springs

will be difficult because of the expected small magnitude of these effects, seasonal changes of precipitation and evapotranspiration rates, and longer term changes in local precipitation rates.

Table 20 Simulated reductions in discharge (acre feet per year) to streams, Scenario J , 2029 and 2039

1955
Pumping Chinle Wash Laguna Creek Pasture Canyon Moenkopi Wash Dinebito Wash Oraibi Wash Polacca Wash Jaidito Wash Cow Springs
b.
2039

2039
All Non-PWCC

Change due to Pumping All Non-PWCC PWCC All

%

None

PWCC

498.9 2535.7 426.8 4305.1 515.6 458.1 440.6 2027.4 2178.0

498.7 2330.9 290.4 4272.0 513.5 449.6 417.2 1986.5 2140.8

498.7 0.2 2341.8 204.8 290.4 136.3 4296.6 33.1 514.5 2.1 451.3 8.5 418.6 23.4 1997.9 40.9 2172.5 37.2

0.2 193.9 136.3 8.5 1. I 6.9 22.0 29.5 5.5

0.0 10.9 0.0 24.7 1.O 1.6 1.4 11.5 31.7

0.04 8.08 31.94 0.77 0.41 1.86 5.31 2.02 1.71

0.00 0.43 0.00 0.57 0.20 0.36 0.32 0.57 1.46

Table 21 Simulated reductions in discharge (acre feet per year) to streams, S c l n a r l o I', Z O 2 C I and 2039.

1955 Pumping Chinle Wash Laguna Creek Pasture Canyon Moenkopi Wash Dinebito Wash Oraibi Wash Polacca Wash Jaidito Wash Cow Springs
b.
2039

2039 All 498.7 2329.7 290.4 4265.5 513.4 449.5 417.0 1985.3 2137.8 Non-PWCC 498.7 2341.8 290.4 4296.6 514.5 451.3 418.6 1997.9 2172.5

Change due to Pumping All 0.2 206.0 136.3 39.6 2.2 8.6 23.6 42.1 40.1 Non-PWCC 0.2 193.9 136.3 8.5 1. I 6.9 22.0 29.5 5.5 PWCC 0.0 12.1 0.0 31 . I 1. I 1.8 1.6 12.6 34.6 All

YO
PWCC 0.00 0.48 0.00 0.72 0.22 0.38 0.36 0.62 1.59

None 498.9 2535.7 426.8 4305.1 515.6 458.1 440.6 2027.4 2178.0

0.04 8.1 2 31.94 0.92 0.43 1.88 5.35 2.08 1.84

In

summary,

groundwater

models

are

the

best

tools

available

for

evaluating

the

contributions of different pumping stresses on the observed or measured effects water levels and stream flows).

(i.e.,

Models of the N Aquifer flow system have been developed

by both the USGS and by Peabody since the 1980's, with each successive effort improving on the previous. As additional data have been collected and improved computational tools

made available, the models have incorporated more knowledge of the groundwater system. The models have varied in detail; however, they were each based on che data available at the time of the model's development and incorporate the major components of the N Aquifer flow system. Further, each model has been subjected to a calibration process whereby the Peabody's 3D recharge rate.

ability of the model to simulate historical measurements is demonstrated. model has been used to evaluate the effects of uncertainty in the

Importantly, the several models are consistent with respect to their predictions of the impacts from pumping on the N Aquifer flow system. They predict that water levels in the

confined part of the N aquifer will be reduced by pumplnq but that they will remain well above the top of the N aquifer. The effect of Peabody's puniplng on discharqe to streams

has been and will continue to be minimal.

Effect on the Structural Integrity of the N Aquifer.

Lowering of water levels by pumping

has allowed compaction of unconsolidated sediments in areas of the western U.S. (e.g., Las Vegas valley, Nevada; Antelope Valley, California; San Joquin Valley, California). U.S. Geological Survey (Galloway and others, 1999) recently published a The

Circular

documenting examples of aquifer compaction and related land subsidence associated with reduction of water pressures, oxidation of organic deposits, and formation of sinkholes in carbonate terranes. It states (p. 8-9):

REVERSIBLE DEFORMATION OCCURS IN ALL AQUIFER SYSTEMS The relation between changes in ground-water levels and compression of the aquifer system is based on the principle of effective stress first proposed by Karl Terzaghi (Terzaghi, 1925). By this principle, when the support

provided by fluid pressure is reduced, such as when ground-water levels are lowered, support previously provided by the pore-fluid pressure is

transferred to the skeleton of the aquifer system, which compresses to a degree. Conversely, when the pore-fluid pressure is increased, such as

when ground water recharges the aquifer system, support previously provided by the skeleton is transferred to the fluid and the skeleton expands.

In

this way, the skeleton alternately undergoes compression and expansion as the pore-fluid pressure fluctuates with aquifer-system discharge
previous

and

recharge.

When the load on the skeleto:? reinains less tila:? any 84

R e v ~ s e d 11:21/03

maximum load, the fluctuations create onlj, a sinall elastic de?for1r:zti3!1 ! f c the aquifer system and sirtall displacement of land surface. [Emphasis added] This fully recoverable deformation occurs in all aquifer systems, cor~nonly resulting in seasonal, reversible displacements in land surface of up t.o 1 inch or more in response to the seasonal changes in ground-water piiinpacjre.

The USGS circular was primarily addressing basln fill materials of relat-ively young age. The rocks of the N aquifer are more than 135 million years old, have been buried to sufficient depth to cause pressure welding of the quartz grains, and exhumed. Thus, it is

unlikely that production of water from the N aquifer will cause the load on the skeleton to exceed the previous maximum load or produce sufficient compaction to be of concern.

To provide information with which to calculate the amounts of compaction that might occur, rock mechanics studies were performed the Navajo Sandstone beneath the (GeoTrans, 1993; Peabody, 1993). Because cores of $ample5 were

Peabody

leasehold were not avallablt,

collected from outcrop areas.

These samples had been subjected to near-surface weathering

processes that would remove calcite cement, and thus the testing results are belleved to overestimate pressure the effect of drawdown on the material properties. Reduction of water

(by pumping, for example) removes some of the support that helps maintain the The laboratory

thickness of the aquifer, and thus allows the rock or aquifer to compact.

tests were designed to measure this compaction process and its effect on the porosity and i hydraulic conductivity of the rock samples. These were performed by placing the samples

in a test cell in which the pressure was increased to simulate the pressures at the depth of the aquifer in the deepest parts of the basin. The resulting changes in the samples'

porosities and their hydraulic conductivity were measured.

Five

samples

were

placed

under

effective

stresses

of

up

to

2,000

psi,

which

is

approximately equivalent to a depth of burial of 3,000 feet and a depth to water of 600 feet. basin. effective This is greater than the actual stress conditions near the deepest part of the Measurements stress was of the reduction in poroslty of these outzrop increased (water pressure decreased)
1

sainpies as
:

che thr

(-:lac

compressibility of the sandstone is about 4:xl0~"/psi,which is higher than expected for many, un-weathered sandstones. samples. This value is consistent with the weathered nature of the

The data also indicate that the samples had prevxously been subjected to higher

pressures than in the outcrop setting, consistent with the geologic history of the area and microscopic observations that the sand grains had been pressure welded. Derivation of

compressibility from specific storage measurements for the aquifer (based on model-based interpretations of the observed drawdown caused by Peabody's use of the aquifer) yield 85 Kevlsed 11/21/02

numbers approximately one-tenth of the laboratory compressibility measurements.

This

observation suggests that the compressibility of the weathered rock is approximately 10 times that of the un-weathered rock. Thus, the laboratory compressiblliiy measurements

should not be used to characterize the specific storage sf the aquifer, but they do provide insight into the maximum changes ln the poroslt;. and 1n:diaulii water levels change as a result of pumping. c~~?dact~,~.lty as

Calculations based on these laboratory compressibility measurements indicate that there could be as much as 1.5 feet reduction in the thickness of the aquifer by 2007. approximately a 0.12 percent decrease in thickness. more representative of un-weathered sandstone, This is

Using compressibility values that are the decrease in thickness would be

approximately one order of magnitude smaller, or 0.15 feet.

The reduction in hydraulic on the

conductivity as a result of the drawdown-induced compaction was also measured samples.

These measurements indicate that the reduction would be approximately 55 in the If un-weathered samples had been

immediate vicinity of the Peabody water-supply wells.

tested, the measured reduction would have been considerably less.

Peabody has run video logs in its water-supply wells to evaluate the condition of well screens and the amount of scale that might clog the screen openings. If compaction of the

N aquifer sufficient to cause concern were occurring, buckllng of the screens would be expected. drawdown observed. at Many of the wells were logged in the early l58iifs, afcer c k ? the wells had occurred; no damage attributable to iila~srlcy of has been

compaction

The most recent video log was run in June, 2001 in NAV 8 , and no evidence of If compaction is not significant at these wells where

compaction effects was found.

drawdown and overburden stress are greatest, then compaction in other areas of the aquifer will also be negligible.

In summary, the data indicate that there is no risk of damage to the structural integrity of the aquifer resulting from projected drawdown. Similarly, compactio~n has been and will

be insignificant, and any compaction is expected to be recoverable.

Effects of Induced Leakage of Poorer Quality Water from the Overlyinq D-Aquifer System on N-Aquifer Water Quality. In the vicinity of the leasehold, water levels in the are 100 to 250 feet higher than in the N aquifer. movement of water from the D to the N aquifer.
D

aquifer

Thus, there is natural do'..~nward

The large difference In water levels

suggests that hydraulic conductivity of the Carmel is low, and therefore thar tine rate of movement is slow. Drawdown in the N aquifer caused by pumping of water frcm the ? I aqulfer

will increase the rate of water movement in proportion to the increase in water level
86

Revised 11/21/03

change.

Thus, several hundred feet of clrawclo~wn in the

l.!

aquif-r could Increase the

leakage rate several fold. prior to any pumping.

Whether this is important depends on the magnitude of leakage

If the pre-pumping leakage rate were very small, increasing it

several fold would still produce a small leakage rate.

The most direct means to evaluate the impact on N aquifer water chemistry is to evaluate water-chemistry data. Water samples have been collected from well 4T-402,
CI

wlndmill

which is completed in the D aquifer near the center of the leasehold. well has a high TDS, with concentrations of major ions as shovjn l n

Water from thls Table 22. The

chemistry of this water is distinct from that of the N aquifer.

Wells in the Peabody

wellfield have been routinely sampled since approximately 1981; results have been provided to OSM in annual monitoring reports. data of uncertain quality. Until the mid 19801s, laboratory problems produced

These problems have since been resolved, and the analytical no clear temporal

results over the last fifteen years show only occasional "noise" and trends.

Four of the wells (NAV 4 , NAV 5, NAV 7, and NAV 8) in the wellfield are completecl I n both the N and D aquifers. Based on the chemical data, the contribution to the wells pumpage Table 22 presents average concentrations of major ions for D The percentage of water derived

from the D aquifer is small.

aquifer well 4T-402 and the Peabody production wells.

from the D aquifer is also presented, based on the mixing equation for chloride:

X Cl~a,+ (1-X) Clbia?

=

Clsalnple and Cl .,,,;.,,
!+

,,,, ,,,,, where X is the proportion of water from the D aquifer, Clri 2lcc

are the

chloride concentrations in the D aquifer, M aqulfer, and the water sampl?, respectively. Even in the wells that are partially completecl in the D aquifer, the chloride-based valiies are less than 2% contribution pumping. from the D aquifer, even after more than 30 years of is

The chloride data indicate that the percent of D aquifer-derived water

approximately 0.2% or less. suggests that these

The lack of a significant trend of increasing concentrations are largely determined by pre-pumping
N

concentrations

aquifer

chemistry.

The sulfate values suggest a greater contribution from the D aquifer, but may

be affected by gypsum particles deposited with the quartz and other mlneral grains.

Using the base-case 3D model, a prediction was made of the Increase In 1eak:ance from rhe D to the N aquifer, assuming that pumping would occur as described in Scenarios J and K. The program ZONEBDGT (Harbaugh, 1990) was used to calculate the flow blithin the N aquifer within a small block encompassing the Peabody wellfield. These calculations indicate that

the leakage from the D to the N aquifer wlthln this block would increase by a factor of 1.8 between the pre-pumping period and 2007 (this factor will decrease ln later years as N
8 -?

P.tl~ii.sed11/21/03

Table 22 Average Concentrations of Major Ions from D and M Aquifer Wells on or near t.he PWCC Leasehold, and Calculated Contribution from the D Aquifer Based on C i l l o r l d e Conzencrarmcs

Well

Ca (mg/l)

Na (mg/l)

Alkalinity as CaC03

NAV 2 NAV 3 NAV 4 NAV 5 NAV 6 NAV 7 NAV 8 NAV 9

9.5 4.5 5.2

28.5 37.8 44.2 61.1 38.5 48.8 69.2

80.3 82.8 86.5 107.6 83.6 86.8 96.8 71.5

3.1
3.9 4.0 25.1 4.1

33.5

Aquifer pumping is reduced).

They also indlcate that lateral f.!i !o.
;I

into the block from
?'k:i:,,

surrounding N aquifer rocks would increase by

factor of ilkout 20.

~i-:e i.ihsml~try

of the water pumped from the wellfield would primarily be determined from chemistry of the water in the N aquifer in areas surrounding the wellfield. aquifer water in the N aquifer water (Table 22), even if The small component of D assumed to be entirely

representative of pre-pumping conditions in the N aquifer, indicates that the effect of pumping on the water quality is insignificant. This results because of (1) the limited

leakage rate under non-pumping conditions (evidenced by the present water chemistry), (2) the limited increase in leakage rate (factor of 1.81, and (3) the flow dynamics produced by pumping water primarily from the N aquifer.

Based on ZONEBDGT calculations, and mixing equations, the change in sulfate concentrations in several different areas within the N aquifer basin was calculated. The results for

Scenarios J and K are shown in Table 23a and 23b, respectively, and reflect the cumulative effect of pumping by PWCC between 1956 and 2038. Because of the small amount of leakage

through the Carmel under natural conditions (indicated by the low TDS levels in the 1.1 aquifer after leakage from the D aquifer for thousands of years), the incrsase in leakage due to pumping is predicted to cause very mlnor changes In the chemistry of the N Aquifer water. Where natural leakage is believed to be higher (in the eastern part of the basin)

based on water chemistry data), nearly 75 years of pumping is predicted to cause an increase in sulfate concentrations of about 12. predicted to be less than 0.1 percent. In all other areas, the increase is

Impact of Wash Plant Refuse Disposal on Ground Water Flow and Quality. Mine plans to construct and operate a coal wash plant facility. used to refine the separation of coal and mine waste materials.

The Black Mesa

This wash plant will be It 1s estimated that the

coal washing facility will produce approximately 1.38 million tons of refuse per year, comprised of a mixture of coarse (plus 100-mesh) and flne (minus 100-mesh) materials. The

location and configuration of the wash plant can be found on Drawing No. 85380, Sheet lA, Black Mesa Mine Facilities, in Volume 22 of the PAP.

Attachment

3 to

this

PHC contains

the

report

entltled

"Wash

Plant

Refuse

Disposal

Hydrologic Impact Evaluation Report" (Water Waste and Land, 2003).

This report provides a result from

thorough analysis of the potential impacts to the hydrologic balance that m) a' disposal of wash plant refuse in two coal resource areas.

The report concludes t h a ~the

disposal of wash plant refuse for a short 3-year period in the final M6 pit, followed by long-term disposal of wash plant refuse in the 323 pit will result in negligible and likely unmeasurable impacts to the hydrologic balance.

Table 23 Maximum predicted sulfate concentrations (mg/L) resulting from PWCC pumping, 1956-2039
Final Concentration (w n) Navajo sandstone
100 50 100 30 5 10 10 30 20 45 50 35 140 70 100.045 50.51 1 100.091 30.060 5.003 10.006 10.011 30.000 20.017 45.034 50.001 35.01 2 140.002 70.006 0.0448% 1.0229% 0.0914% 0.2006% 0.0601 % 0.0578% 0.1149% 0.0001% 0.0869% 0.0746% 0.0029% 0.0347% 0.0014% 0.0086%

Subarea

Initial Concentration (rnglL)

Change

1
Northeast East Hopi Buttes Forest Lake Kitsillie Pinon Rocky Ridge Preston Mesa Leasehold Pinon to Kitsillie Surrounding leasehold Red Lake to Tuba City Hotevilla to Kabito Pinon to Rocky Ridge

D Aquifer 250 850 360 1000 75 200 250 400 400 1000 100 400 200 210

Navajo sandstone

a. Scenario J

Subarea

/

Initial Concentration (rng1L)
D Aquifer

/
100 50 100 30 5 10 10 30 20 45 50 35 140 70

Final Concentration Navajo sandstone
100.047 50.524

1

Change

I
Northeast East Hopi Buttes Forest Lake Kitsillie Pinon Rocky Ridge Preston Mesa Leasehold Pinon to Kitsillie Surrounding leasehold Red Lake to Tuba City Hotevilla to Kabito Pinon to Rocky Ridge

Navajo sandstone
250 850 360 1000 75 200 250 400 400 1000 100 400 200 21 0

0.0468% 1.04727 0.09337 0.21399 0.06309 0.06004 0.11974 0.00014 0.09374 0.07835 0.0031'? 0.03655 0.00155 0.00905

100.093 30.064 5.003 10.006 10.012 30.000 20.019 45.035 50.002 35.013 140.002 70.006

b. Scenario K

Revised 1 1 / 2 1 / 0 3

Surface Water

Effects of Dams, Sediment Ponds and Permanent Internal Im~oundmentson P\unoff and Channel Characteristics. Ten major dams have or will be constructed on principal tributaries Portions of the

confluent to Moenkopi Wash during the life of the mining operation. drainages above as well as below the dams b~ill be affected.

The reach immediately above a

dam will gradually aggrade headward as more and more water is impounded until a pool level is reached that is in equilibrium with water gains and losses. Channel reaches below the

dams will become incised by smaller active meandering channels whose widths are a function of drastically reduced runoff potential, channel gradients and sediment load particle size ranges. Vegetation will begin encroaching on the edges of the new acrrive channels as

there will be insufficient runoff to remove it.

The effects of sediment ponds and permanent internal impoundments on runoff and channel characteristics will be minimal on an individual basis, but comparable to the effects of dams when considered in total. It is estima~ed that more than 320 sediment ponds and

several permanent internal impoundments have been or will be constructed during the life of the mining operation. The internal impoundments are typically small, excepting PIIs

like N2-RA, N7-D and the one impoundment proposed for the J-19 coal resource area, and most have been built on pre-law lands. for dams. Channel effects will be similar to those described

Since most of the sediment ponds are on very small side tributaries, there will Because of the number of ponds and (active channel narrowing and

not be any up-drainage impacts of any significance. their wide range of locations,

the downstream effects

vegetative encroachment) will be manifested over longer channel distances.

In addition to the permanent internal impoundments, 31 sediment control structures (see Chapter 6, Table 9) are proposed for consideration as permanent ~mpoundments that will remain as permanent features of the postmining landscape. The total clralnaye area that

these 31 permanent impoundments will encompass amounts to only 0.5 percent a n d 2.0 percent respectively of the entire Dinnebito and Moenkopi watersheds idown to each confluence with the Little Colorado River).

The impacts of the sediment ponds and dams will be of little significance as there are no local users of water for flood irrigation (see Alluvial Valley Ploor section of Chapter 17). Following removal of the dams and sediment ponds, there will be certaln short-term Sediment loads will

impacts to the channel reaches immediately below these structures.

temporarily increase as the active channel widens in response to the increased runoff potential. The increased channel bank vegetation should provide some stability during

Revised 11/21/03

this active channel readjustment period.

The potential for flood flov~s nvertoppinq the ahox'e

channels will be negligible as the typical channel banks are 15 to 20 plus feet h g :h the active channel.

The frequency of the larger runoff events will dictate how fast the

channels reestablish themselves in quasi-equilibrium with the environmental conditions.

Effects of Dams, Sediment Ponds and Permanent Internal Impoundments on Downstrean1 Users. As of January 2002, the total Dinnebito and Moenkopi b~atershed areas to the leasehold boundary draining to PWCC dams, ponds and impoundments are 4.08 and 63.01 square miles, respectively. There are numerous large, significant tributaries to both washes between Comparing the above impounded drainage areas

the leasehold and the Little Colorado River.

to the total drainage areas for both washes (2,605.3 and 812.8 square miles, respectively) suggests that this loss of runoff is of little significance at the points where the runoff water has any potential for being used for flood irrigation. As of January 2002, the

impounded drainage areas on the leasehold amounted to only 0.5 percent and 2.42 percent of the total Dinnebito and Moenkopi watersheds, respectively.

Busby

(1966) developed estimates of average annual runoff in the counterminous United Based on these average annual estimates, runoff

States, including Northeastern Arizona.

was calculated for the total watershed areas of both Dinnebito and Moenkopi washes to their respective confluences with the Little Colorado River. Average annual runoff for

each basin was determined by summing the calculated runoff for partial areas defined as the b~atershed area lying between transect the basin. each pair of average annual runoff isopleths that

The average annual runoff isopleths shown for the Black Mesa region Therefore, the lower portions of

on the Hydrologic Investigation Atlas HA-212 were used.

each basin were assigned an average annual runoff value of 0.1 inches, and the upper portions of each basin, including those portions in which PWCC's leasehold are situated, were assigned much higher average annual runoff numbers (1.25 to 1.75 inches) . Based on

Busby's empirical estimates, the average annual runoff for the entire Dinnebito basin was calculated to be 17,242 acre-feet, and 57,022 acre-feet of average annual runoff for the entire Moenkopi basin was determined.

Table 24 presents combined annual runoff measured from 1987 through 2002 at contin~ious flow monitoring sites SW155, SW25, and SW26, as well as annual r~uioff measured for the same period at the USGS Streamflow-gaging station (09401260) located on Moenkopi Wash at Moenkopi, Arizona. The runoff values are presented as acre-feet and inches of runoff.

The inches of runoff for the PWCC sites were calculated by dividing the total runoff in acre-feet by the combined drainage area (in acres) above all three monitoring sites that was not controlled by PWCC dams, ponds and impoundments for each year shown (e.g., 190.25

Table 24 Measured Annual Runoff at PWCC's Continuous Flow Monitoring Sites and at thn USGS Streamflow-Gaging Station 09401260, Moenkopi wash at Moenkopi, .A~l:ona

PWCC ~ltes' Total

USGS Statlon UY201260 Adjusted Total ~unoff.' (acre-ftj

Calendar Year

Total Runoff (acre-ft)

~ u n o f3 f (in.) 0.31 0.32 0.14 0.18 0.03 0.18 0.04 0.01 0.11 0.01 0.28 0.05 0.16 0.02 0.08 0.09 Avg. 0.13

Total Runoff (acre-ft)

~ u n o f5 f (in.) 0.11 0.10 0.03 0.08 0.01 0.04 0.08 0.005 0.02 0.01 0.09 0.01 0.15 0.03 0.17 0.10 Avg. 0.06

1 - Combined Measured Annual Runoff from Sites SW155, SW25, and SW26 (PWCC Annual Hydrology Reports, 1987

- 2002)
2
-

USGS records (NWISWeb, 2003)

3 - Based on the combined drainage area for all three sites (253.27 square miles) less total PWCCimpounded area during each calendar year 4 - Runoff numbers adjusted to remove groundwater baseflow component and reflect only snowmelt and rainfall runoff 5 - Based on the total drainage area for USGS Station 09401260 (1629 square miles) less total PWCCimpounded area during each calendar year
93 R ~ e v l s r d 11/21/03

square miles in 2000) and multiplied by 12.

Similarly, the inches of runoff for the USGS

Moenkopi gage was calculated by first subtracting baseflow contributions troin gl-ound ilater discharge from each year's total measured runoff, then dividing the adjusted total runoff (acre-feet) by the total drainage area (in acres) above the gage that was not con~roll=.d by PWCC impoundments (e.g., 1565.99 square miles in 2000). The inches of runoff presented

for both locations represent runoff generated from precipitation events.

For the sixteen-year period presented in Table 24, the upper sites (SW155, SW25, and SW26) averaged 0.13 inches of runoff, and the USGS gage at Moenkopi averaged 0.06 inches of runoff. The average annual runoff in inches determined from the 16-year record at the (0.06 inches) was used to estimate the average annual runoff (in

USGS gage at Moenkopi

acre feet) for the entire watersheds of both the Dinnebito and Moenkopi basins, and are presented on Table 25. Comparing these values (Table 25) with the average annual runoff

estimated for both basins using Busby's estimates (17,242 acre-feet for Dlnneblto; 57,022 acre-feet for Moenkopi), it is obvious that Busby's empirical estimates of average anlnual runoff for the Black Mesa region are extremely hlgh and unrealistic compared t : annual runoff calculations that are based on local stream flow measurements. average

Table

25 also presents

drainage

areas

and

average annual

runoff

estimates

for the

watershed areas draining PWCC dams, ponds and impoundments (unpounded areas) ~ ~ i t h iboth n Dinnebito and Moenkopi washes as of November 2003 and for the proposed life of mining. Impounded areas are based on summing designed drainage areas for the existing impoundments (November 2003) and those proposed for the life of mining (see Drawing 85406, Volume 22). Table 25 shows the November 2003 impounded area is 0.5 percent a~nd 2.4 percent

respectively of the total drainage areas for the Dinnebito and Moenkopi basins, and for the life of mining, the total impounded area increases slightly to 0.8 percent and 2.8 percent respectively of the total Dinnebito and Moenkopi drainage areas.

The 16-year average measured runoff at the three PWCC sites (0.13 inches, Table 21) was used to estimate average annual runoff for the November 2003 and life of minlng ~rnpounded areas. The estimates of average annual runoff for the November 2003 ~mpounded area on the

leasehold is 1.1 and 5.2 percent respectively of the average annual runoff calculated for the entire Dinnebito and Moenkopi basins. Table 25 shows average annual rulnoff for the

life of mining impounded area on the leasehold will increase slightly to 1.7 percent and 6.1 percent respectively of the average annual runoff calculated for the entire Dinnebito and Moenkopi basins. Additional impounding area for the life of mining will include

construction of several temporary sediment structures proposed for the 323, J19 West, and

Tabls 2 5 Drainage Areas and Estimatss of Annual Runoff

Moenkopi Wash Basin Total Area (i) m'

Dinnebito Wash Basin Total Area (mi')

Runoff (ac-ft)

Runoff (ac-ft)

Totals without PWCC Ponds

PWCC Dams, Ponds, and PII's
-

November 2003

62.84

PWCC Dams, Ponds, and PII1s - Life of Mine3'\3.51

Post-mining Permanent 1rnpoundments5

1

-

Based on 16-year average annual runoff measured at USGS Station 09401260. Maximum PWCC-impounded area within Moenkopi Wash Basin occurs in 2020. Maximum PWCC-impounded area within Dinnebito Mash Basin begins in 2020.

2 - Based on 16-year average annual runoff measured at PWCC gages SW155, SW25, and SW26.

3 4

-

5 - See Table 9, Chapter 6, Facilities.

Revised 11/21/03

N99 mining areas, and three proposed permanent impoundments in the 513, 221, an !d reclaimed landscapes (see Chapter 6, Facilities).

k110

Table 25 also presents the total impounded area of permanent ~mpoundmsnes proposed to remain in the post-mining landscape in both the Dinnebito and Moenkopi basins (see Chapter 6, Facilities, and Chapter 14, Land Use). areas, PWCC's proposed permanent Following final reclamation of all mining will comprise 0.47 and

impoundments

2.21 percent

respectively of the total Dinnebito and Moenkopi drainage areas.

Using the annual average

runoff of 0.13 inches determined from 16 years of stream flow measurements collected at the three PWCC gages, the permanent impoundments could impound about 1.0 and 1 . 8 percent of the average annual runoff at the lower ends of the Dinnebito and PIoenkopi basins, respectively.

Based on percentages of impounded drainage areas presented in Table 24 for the November 2003, life of mining, and permanent impoundments with the total basin areas of Dinnebito and Moenkopi washes, loss of runoff in each basin is of little significance at downstream points where runoff water has any potential for being used. An alluvial farm plot and

phreatophyte survey performed by Intermountailn Soils, Inc. ~n J L I I ? ~ , 1985 cloruminted that there is no evidence that flood irrigation was ever practiced in the past or that it is presently being practiced along the major washes and tributaries !.i~thln the leasehold. All agricultural plots inspected were located on high terraces and were planted with shallow rooting cultivars, which are solely reliant on rainfall infiltration. Inspection

of regional reservation land use maps indicates that flood irrigation is not practiced below the leasehold along lower Dinnebito and Moenkopi Washes other than some 70 miles below the leasehold at the town of Moenkopi. PWCC is not aware of any other diversions

immediately downstream of, or further downstream for approximately 70 miles in either Dinnebito or Moenkopi Washes. Runoff from precipitation events in both washes typically

occurs as flash floods, with rapidly rising water levels, hlgh velocltles, ancl very higln concentrations of suspended solids. The channel beds and banks of both channels are

subject to significant changes in width and depth as a result of runoff events, ofcen changing appreciably during each event, which can create significant problems regarding the construction and maintenance of water diversion structures.

Comparisons of average annual runoff estimates lndlcate the impouudscl areas for the life of mining have the potential to, on average, reduce average annual runoff I:? rhe I)l!?!?eblto basin by no more than 1.7 percent, and in the Moenkopi basin by no more than 6.1 percent.

Revised 11./21/03

Total runoff in the basins is greater than estimated in Table 25 because of depression storage, channel transmission losses and evapoeranspiration. Channel trarismisslo~?losses

along the sand-bed channel bottoms wlthin the leasehold have been estlnaied to be yulte high, potentially resulting in more than a 50 percent reduction of flow volumes durlng runoff events that occur along the major channels within the leasehold (see Chapter 15, Hydrologic Description).

Review of historical daily records from both the three upper PWCC sites

(PWCC Annual

Hydrology Reports, 1997 through 2002, see Preface to Chapter 15, Hydrologic Description) and the USGS Moenkopi gage (NWISWeb, 2002) indicate significant loss of runoff from the upper basin area can occur. From August 7 through August 8, 1987, 1,328.7 acre-feet of One large event was measured at SW155 on

runoff was measured at the three PWCC gages.

August 8, featuring a peak discharge of 10,100 cfs and a total runoff volume of 638.7 acre-feet. Total runoff volume measured at the USGS gage from August 8 through 9, 1987

was 668.7 acre-feet, suggesting almost 50 percent of the total runoff (1,328.7 acre-feet) from the three upper sites was lost downstream if these were the sole source of runoff recorded at Moenkopi . On August 16, 1989, summer thunderstorms generated moderate-sized

flash floods at all three gages at about 1600 hours, resulting in a total runoff volume of 524.8 acre-feet. prior. No runoff had occurred at any of the three sites for at least 6 days

Runoff at the USGS Moenkopi gage was only 1.3 acre-feet on the same day, and only The record comparison indicates about 77

117 acre-feet was measured on August 17, 1998.

percent of the 524.8 acre-feet of runoff generated from this portion of the basin was lost. On July 27, 1998, a flash flood passed by SW25 at a peak flow of 1,650 cfs This one event was more than 37 The USGS gage

resulting in a total runoff volume of 206.7 acre-feet.

percent of the total runoff measured at the three PWCC gages in 1998.

measured only 14 acre-feet of runoff from July 27 through 29, 1998, indicating a loss of more than 93 percent of the 206.7 acre-feet. It is likely the 14 acre-feet measured at

the USGS gage was comprised of return flow from bank storage from the upstream, 70-mile channel reach, and that the entire volume of the 200-plus acre-feet runoff event from the upper basin was lost in the channel. It should be pointed out that these comparisons This is an

assume no additional inflows to Moenkopi Wash below the leasehold occurred.

unlikely assumption considering that the entire basin above the USGS gage is large, and summer thunderstorms in the region often move great distances bihile rnaintalning high

rainfall amounts and intensities, even though the areal extent of ~ndividual storm cells may be relatively small.

Table 24 indicates actual runoff is highly variable from year to year in both the upper and lower portions of the Moenkopi basin. Runoff variability 1s closely related to the

highly variable

climatic differences typical

in

this seml-arid e!irlroiiment,
oi.i:l!L.

a n l the ic
'!,:m

limited areal extent and varying intensities of the storms that do

i95-J

through 2002, measured annual runoff at the three PbJCC gages has ranged from 124.1 acrefeet in 1994 to a high of 3,787.7 acre-feet in 1988. For the same 14-year period,

measured runoff at the USGS Moenkopi gage was also lowest in 1994, but the h i g h e s ~annual runoff was 13,974 acre-feet in 2001. Total measured runoff at the three PWCC gages in

1988 was greatly influenced by one extremely large runoff event measured at SW25 on August 26, 1988. The peak discharge was estimated at 25,000 cfs for a total runoff volume of This one event accounted for more than 50 percent of the total runoff The total runoff measured at the three PWCC

1,836 acre-feet.

measured at the three PWCC gages in 1988.

gages from August 25 through August 27, 1988 was 2,624.5 acre-feet, about 69 percent of the annual total measured in 1988. For the same period, the USGS gage measured 2,945.5

acre-feet, indicating that this extreme event fell on other portions of the Moenkopi basin and contributed additional runoff to the gage some 70 miles downstream.

By contrast, the total runoff measured at the USGS Moenkopi gage in 1388 was only the fifth highest of the sixteen years presented for this gage (see Table 24). Combined total measured runoff at the three PWCC gages as a percentage of the USGS L4oenkopl gage ranged widely from 5.7 percent in 2001 to 90.0 percent in 1998, illustrating the considerable variability in runoff within the basin. In fact, total measured runoff from the upper

part of the basin (PWCC gages) in 2001 was only 5.7 percent of the highest annual measured runoff at the USGS Moenkopi gage (13,974 acre-feet).

Review of the measured daily records at both the three PWCC gages and USGS Moenkopi gage and the annual measured runoff shown in Table 24 suggests that 1) considerable amounts of runoff generated in the upper basin can be lost before reaching downstream locations, ranging from 50 percent of runoff events in excess of 1,000 acre-feet upwards to 100 percent for smaller events (200 acre-feet); 2) areal and temporal variability of runoff within both Dinnebito and Moenkopi basins is high; 3) channel transmission losses can significantly reduce annual runoff contributed from the upper portions of both basins; and 4) the impact of PWCC impounded areas in the upper part of both the Dinnebito and Moenkopi basins is minimal.

Peabody has monitored

annual water

levels and volumes

in

the MSIIA

srzs

ciams

since

construction, beginning with J7-DAM in August 1978.

Estimates of water volumes in all

ponds based on quarterly and monthly inspections were compiled for the years 1989, 1990,

Revised 11/21/03

and 1996 through 2002.

Table 26a is a compilation of the results of the al-~o-ie-referenced The values listed i~?each column ar? the : o u n s !lre

monitoring and water volume estimates.

of water in acre-feet measured or estimated in the ponds and MSHA dams f o ~ each year or period presented.

Table 26a shows a 699 acre-foot increase in the amount of water impounded from 1996 to 1997, and a 465 acre-foot increase from 1998 to 1999. Assuming the increases shown for

these two periods represent only surface water runoff, dividing both amounts by the total impounded area present during each period yields values of annual runoff in inches of 0.20 for 1997 and 0.13 for 1999. These values compare reasonably well with the inches of The 1999 annual

runoff measured at the three PWCC gages in 1997 i0.28) and 1999 (0.161 .

runoff measured at the PWCC gages was only 12.6 percent of the 1999 annual runoff measured some 70 miles downstream at the USGS Moenkopi gage. Considering the variability in

measured annual runoff from year to year at the upper portion of the Moenkopi basin at PWCC's leasehold compared to measurements made further downstream at ~ h e USGS gage at Moenkopi, impounded runoff in PWCC's dams, ponds and impoundments appear to have had a minimal effect on downstream runoff.

Based on the pond and dam monitoring information presented in Table 2Ga, che following analysis was performed to further assess the potential impact of the dams and ponds on flow volumes at the town of Moenkopi. The analysis considers whether the amount of water

captured by the impoundments in a year would reach the town of Moenkopi if the total amount was due to a single, large storm at the leasehold. Further review of Table 26a

indicates that one of the years with significant increases in water impounded from the previous year was 1983-1984. Five hundred elghty-seven acre-feet of additional water was

impounded from overland runoff, Navajo well pumpage and pit pumpage. The latter two water sources were not considered to be a significant part of the total and were t h u s ~gnored. In Table 26a, 60 new acre-feet of water was assumed to be impounded by all the non-MSHA sized sediment ponds combined for each of the years 1978 through 1986. This GO acre-feet

added to the 1983-1984 increase in water impounded by MSHA structures ylelds a total of 647 acre feet of new water for that year.

The analysis approach employed moving a flow volume equal to 644 acre feet down a 70 mile length of Moenkopi Wash in a channel with a constant 80 foot flat bottom width (based
011 a

cross section of Moenkopi Wash that is being measured and monitored i~lthin the leasehold for indirect flow calculations) as shown in Figure 20. banks Although flow loss to the channel the only one

is significant, infiltration loss through the channel bottom was

considered.

An hourly loss rate of 1 inch per hour was used and is the lowest loss rate

TABLE 26a

Summary of Maximum Impounded Surface Runoff in MSHA Dams and Sediment Ponds by Year (Acre-feet) All Other Year J2-A J-7 J7-JR J16-A J16-L N14-D N14-E N14-F N14-G M14-H ponds' Total

*
** ***

Pond under construction Negligible amount of water impounded Pond drained for repair Assumed 60 additional acre-feet impounded each year beti~~een 8/81 and 8/86

Revised

10/15/99

determined

from particle

size analyses

of

bed

material

from the prlnc~pal channels

transgressing the leasehold (see Table 12, Chapter 15).

A storm runoff flow with a total flow volume of approximately 644 acre feet was computed using SEDIMOT I1 for a portion of Moenkopi Wash within the leasehold. Trial and error 2 4 -

hour precipitation inputs were tried until a total flow volume as close to 647 acre feet as possible was achieved. The duration of this flow hydrograph (18.4 hours, refer to

Table 26b) was used to determine the minimum amount of time that an infiltration loss of 1 inch per hour would occur over each square foot of the channel bottom between I~loenkopi Wash on the leasehold and Moenkopi Wash at the town of Moenkopi (a distance o at least 70 : miles). Table 26c shows the infiltration loss in acre feet 114.5) for each mile that a At a rate of 14.5

flow with an 18.4 hour duration moves towards the town of Moenkopi.

acre feet per mile, the entire 644 acre foot flow generated on the leasehold would be lost to channel bed infiltration before the flow had moved 45 of the 70 miles towards the town of Moenkopi.

TABLE 26c

Channel Bed Infiltration Loss for Each Hour of Flow Over the Channel Bed Area Between the Leasehold and the Town of Moenkopi

Channel Bottom Area for Each Lineal Foot in Acres Infiltration Rate in feet/hour

Acre Feet of Flow Loss for Each Mile of Flow with an 18.4 Hour Duration

The above analysis was performed using very conservative numbers.

Average channel bottom

widths from the leasehold to the town of Moenkopi are considerably larger than 80 feet and would account for larger infiltration losses per mile than were used. Channel bed

infiltration rates are considerably higher than the 1 inch per hour rate that [was used. This rate is probably more indicative of saturated Elobi infiltration rates. The flow

duration would increase as the flow hydrograph peak lowers and the flow rate slows In the downstream direction. The 18.4 hours is the shortest time span during which flow losses Finally the total flow volume used (644 Individual storm

over each square foot of the channel would occur.

acre feet) is extreme and is an accumulation of runoff from many storms.

volume totals lost due to the impoundments would be considerably smaller and totally lost

TABLE 26b
Discharge Hydrograph Output From SEDIMOT I1 Run for 644 Acre Foot Flow Volume on Moenkopi Wash

Time (hrs)

Discharge (cfs)

Time (hrs)

Discharge (cfs)

Time (hrs)

Discharge (cfs)

Time (hrs)

Discharge (cfs)

Time (hrs)

Discharge (cfs)

TABLE 26h (Cant.)

Discharge Hydrograph Output From SEDIMOT I1 Run for 644 Acre Foot Flow Volume on Moenkopi Wash

Time (hrs)

Discharge (cfs)

Time ihrs)

Discharge (cfs)

as

channel

bed

infiltration

in

shorter

distances

from the

leasehold.

Considering

watershed areas, estimates of annual runoff, comparisons of daily stream flow measurements and measured annual runoff, and runoff volumes impounded, the sedimeint ponds and dams on the leasehold do not have any measurable impact on surface water use at the town of Moenkopi.

Effects Quality.

of

Dams, Sediment Ponds The effects of pond

and and

Permanent dam

Internal Impoundments on on stream-water

Stream-Water wlll be

discharges

quality

negligible, because all sediment ponds and dams are designed to contain the 10-year, 24hour runoff volumes plus sediment. Pond and dam discharges resulting from storm runoff In the event of their occurrence, PWCC will

have and should continue to be infrequent.

make all efforts to comply with the effluent limits and monitoring requirements of the NPDES permit (No. AZ0022179, Attachment 3, Chapter 16, Hydrologic Monitoring Program). removed from sediment ponds is conducted is described in the section in a manner entitled that

The disposal of sediment protects stream water

quality

and

"Design

Methodology" of Chapter 6, Facilities.

The NPDES Permit allows pond dewatering as a means of providing sufficient decencion time and storage to help ensure discharge effluent limits are met and there are no slqnificant water quality impacts to the streams. Pond to pond pumping is also perlodlcally employed.

Seepage from dam embankments or around the sldes of embankments is also 121-esently being monitored in accordance with the NPDES Permit to document this form of pond discharge poses no significant threat to the receiving stream water quality.

Runoff discharges from the permanent internal impoundments are extremely unlikely. they occur, impacts to the stream-water quality will be negligible. average concentrations

Should

Table 27 shows

for select chemical constituents measured in permanent internal Almost all the impoundments selected contain surface

impoundments from 1986 through 2002.

water runoff and have no appreciable ground-water contribution from resaturated spoil, with the exception of Pond N2-RA. chemical constituents measured Table 28 shows average concentrations for the same

in stream flows generated by rainfall runoff at stream Excepting pond N2-RA, c~ater quality documented in
11 1

monitoring sites for the same period.

the permanent internal impoundments is similar to slightly lower compared to stream flows.

range and magnitude

ffl
(D

r. rt

Annual Hydrology Reports

(AIIR's) present

comparisons

of recent and historical pond and

stream water quality data with recommended numeric limits for livestock drlinking Iwater and other uses. Sources of the livestock drinking water limits used (1999), Hopi Tribe
111

the AHP,'s include

(among others) the Navajo EPA (1974), and the USEPA (1995). Revision package, Monitoring 2001) .

(1998), National Academy of Science

In the March 5, 2001 Hydrologic Monitoring Program Permit the document entitled

PWCC attached

"Justification of Monitor

and

Frequency Reductions at the Black Mesa and Kayenta Mines, Arizona"

(PWCC,

The document presents a thorough evaluation of summary statistics, water types,

trend analyses, and comparisons of historical stream water quality with livestock and other use limits. Based on the livestock limit comparisons presented in the document that

used total recoverable metal analyses, all stream flow generated by storm runoff is not suitable for livestock drinking water. The document also mentions, if onl:~ dissolved

analyses are used for comparison purposes, most of che scream water quallily 1s siiitable for livestock drinking.

The Navajo Nation's water limits using

water quality standards dissolved metal

(NNEPA, 1999) establish livestock drinking with the exception of mercury (total

analyses,

recoverable).

Using these standards, in addition to other tribal standards (Hopi, 1998)

and limits recommended by the National Academy of Science for nitrate, nitrite and TDS (NAS, 1974), and by the USEPA for fluoride (USEPA, 19951, comparisons were made between permanent internal impoundment and stream flow water quality collected from 1986 through 2002. Table 29 lists the comparison results for the permanent internal impoundments, and Table 29 shows

Table 30 shows the comparison results for the stream monitoring sites.

that, excepting the high pH values measured in PI1 N1-RA and the high TDS values at pond N2-RA, the permanent impoundment water quality is suitable for use as livestock drinking water. Table 30 also indicates most of the stream flow generated by rainfall runoff is

suitable for livestock drinking water, excepting very infrequent measurements of a select few parameters at Sites 16, 18, 25, 26, 34, 37 and 50. The high pH values cioc~imented in

Pond N1-RA would likely be reduced by contacr: wlch soil and channel bed matel-lals ~f a discharge occurs. An unlikely discharge from either Pond N - R A or M2-PA would he diluted Due to the simllarlt:; in water stream flows, discharges from

when mixing with the larger volumes of stream flow runoff. quality between permanent internal impoundments and

permanent internal impoundments would not significantly affect stream-water quality, and would not change the potential stream water use.

Effects of Stream Channel Diversions on Channel Characteristics and Runoff Water Quality. Six channel diversions affecting approximately 6.0 miles of channel in trlbutarles to

w

t-'

.

o

0 o
.

r

, 0 o

.

N

.

o o

in

.

0 o f f o o

r

Cn

.

.

l o

0 N o o o f

' w

.

.

.f

l

" i ~

a

mu)

. .
P

w w w w

. . . .
P N 0 0 O N 0 0 P O 0 0

0 0 0 0 0 0

"

P N 0 0

Woenkopi Wash have or will be constructed during the life of the mining operations.

The

effects of channel diversions on channel characterisrics and stability will be minor for the following reasons. All diversion channels will be at least as wide as the existing

channel, which should eliminate the potential for flow constrictions and excessive lateral erosion. comparable All diversion channel slopes will approximate original channel slopes so that flow velocity ranges will be maintained. Energy dissipators will be

constructed at the entrance and exit points of each diversion to provide an additional control on flow velocities and erosion potential at these points. The only anticipated

channel effects from the diversions would be the channel's natural tendency to reestablish meanders. This will cause some minor erosion on alternating sides of the diversion where The stability of the channel diversions

the meandering thalweg intersects side slopes.

will be no less than the stability of the natural channels.

The diversion channel construction activity and the natural meandering cendency of the active channel thalweg will expose fresh alluvial surfaces to weathering This will result in additional amounts of sediment and dissolved and erosion. being

chemicals

contributed to the streamflows.

Several years of monitoring downstream from the Coal Mine

Wash and Yazzie Wash channel changes indicates that natural background levels of sediment are so high that these minor additions are negligible (Chapter 15). loads have been historically quite variable. Stream water Dissolved chemical to be

chemistry appears

significantly affected by the portion of the watershed the flow originates in and the magnitude capacity of the sediment load being and transported by the flow. The cation exchange It is as they

of the sediment is high,

this does affect the flow chemistry.

concluded that the water chemistry effects of channel diversions are minimal cannot be distinguished from natural fluctuations.

Effects of Culverts at Road Crossings on Stream Runoff and Water Quality.

The effects of

culverts on stream runoff and water quality will be minimal for the followli-ig L-easons. All culverts or combinations of culverts are designed to pass the 10-year 6-lhour flow wlth at least 1 foot of freeboard. riprapped velocities periodically energy are dissipators between four If culvert e:,:it velocities e:.reas on

the Quantity in vihich

and

Qualltji_-gf is

Streamflow. lands

Considering disturbed by

natural and

physiographic criteria

region by

Peabody

reclaiming

mining,

imposed

regulatory

authorities

for

evaluating

reclamation efforts with

regard to bond

release, probable hydrologic consequences of Bond release

runoff from post-law reclaimed areas is addressed in the following sections.

criteria include the successful establishment of vegetative cover, topsoil stabilization, and the effects of runoff from reclaimed areas on the quantity and quality of waters in the receiving streams. Runoff from reclaimed areas will flow into receiving streams

following the removal of sediment structures at the time of bond release.

Reclamation efforts undertaken by Peabody in post-law coal resource areas on the leasehold occur in a physiographic region typified by a mild mean annual temperature 1 4 8 F ) and a low mean annual precipitation recording rain gauges. (10 inches). Including the Mean annual precipitation is based on nonheated contributions from snow, the mean effective

precipitation on the leasehold is about twelve inches. region include highly eroded landscapes of moderate

Typical basin morphologies in the to high relief, wlth entrenched

sandbed channels and headward-cutting arroyos.

In this arid climate, intense summer thunderstorms produce flash-flooding in ephemeral channels resulting in high concentrations of sediment loads (lo5 mg/l). The highly

erodible natural soils provide a significant contribution to the sediment yields produced in this climate. The limited vegetative cover in this region due to climatic and grazing

conditions contributes to the flashy response of ephemeral channels from intense storms. Figure 21.a. shows a relationship among effective annual precipitation (EAP), climate and annual sediment yield (Langbein and Schumm 1358). Considering this cllagram, EAP and Flgiire 21 . b . shows

climate on Black Mesa correlate to the highest annual sediment ylelds.

the same relationship as Figure 21.a., including the effect of mean annual temperature (MAT) (Schumm 1977). M . on Black Mesa, in combination ~11th PT EAP and climate, correlate to extreme annual sediment yields. leasehold, incorporating Estimates of annual sediment yields into the USLE, (tons/mi2) on the between 1,665

site-specific parameters

range

tons/mi2 and 14,477 tons/mi2.

These estimates were made taking into account the factors

that affect erosion in the region, including the typical sparse cover and hlghly erociable soils (see Annual Sediment Yield Estimates, Chapter 15).

Reclaimed areas created by Peabody on Black Mesa will have topography characterized by long slopes no greater than 3:l (h:v). Topsoil material used to cover regraded spoil 113 Revised 10/15/99

EFFECTIVE ANNUAL PRECIPITATION, in
I.brImion o f sediment yield w f h cll'mols (from Longbein and Schurnm, /958).
In

the United S:ofes

M E A N ANNUAL PRECIPITATION,

in

eff8cl of mean annual temperalum (OF) on t h e sodiment y d d - climofe relationship (after Schumm, 1979, p. 44).

FIGURE ' 2 1

Climofe and Sediment Yield

R e v i s e d 12/01/88

material will be spread to a minimum depth of ti,~elveinches. compacted to some degree during regrading, as ~t

Spoll matsrial swill be

contains higher i-l;~:, <-.,nti.l:r.: than due to

topsoil material.

The only suitable topsoil ma~erlalsavailable are hlgnly erosl.:?

their overall fine-sandy texture and lack of organic material, and are typlsal of those forming regionally under arid conditions. The " R " value assigned to topsoil material used .43 (Chapter 8 1 , which

for reclaimed areas by Intermountain Soils, Inc. personnel is confirms the high erosion potential of the topsoil.

Topsoiled reclaimed areas will feature vegetation established sufficiently to support the stabilization of topsoil material and the postmining land use of livestock grazing.

Vegetative ground cover in the reclaimed areas will be similar to the native vegetation. For a discussion of vegetative ground cover and success standards for cover see Chapters 23 and 26, Permit AZ-0001D.

Discharge.

The effects of runoff from reclaimed areas on the quantity and quality of Receiving streams on Black Mesa (Moenkopi, Flat and Red Peak Washes) commonl:; yleld

waters in receiving streams will be minimal. Coal Mine, Yellow Water, Dinnebito, Yucca

discharges characterized by hydrographs wlth sharp peaks, short tlme to peaks, and short durations. These hydrograph characteristics become somewhat dampened downstream, as

channel slopes lessen and cross section geometries increase.

Runoff from reclaimed areas should largely occur as overland flow, typified by hydrographs of gentle peaks and longer durations. With the controlled topography in reclaimed areas

(slopes less than 3:l) and the modified drainage system, runoff times of concentration will be longer, resulting in reduced flow peaks and longer hydrograph durations typical hydrographs of runoff from natural undisturbed basins on Black Plesa. than

External

drainages will be established as part of the final reclamation, along with networks.

Runoff volumes and discharges from reclaimed areas should result in localized decreases in runoff to receiving streams. receiving streams for Reclaimed coal resource areas will contribute less runoff to storms than those same areas did prior to minlng.

similar

Computations using SEDIMOT I1 to predict runoff and sedimelnt differences from areis ln the Coal Mine Wash drainage before mining and follobring reclamation shoi.l reciuc'iloiis in peak discharges and runoff volumes for an ldentlcal storm input (see Coal Mil15 i l s Pce- and jah Postmining Sediment Yield Estimates, Chapter 15, PAP). In watersheds wlth large portions

of mined and reclaimed areas, magnitudes of the predicted decreases in peak flows range

between 2 and 24 percent. percent.

Reductions in predicted runoff volumes range between 5 and 21

Topography, soils and vegetation modeled in the Coal Mine Wash drainage are typical of final reclamation that will be established in all mined coal resource areas on the Black Mesa leasehold. Based on SEDIMOT I1 predictions, watersheds established in reclaimed coal

resource areas will typically yield reduced peak flows and runoff volumes compared to runoff from the areas before mining activities commenced. The impact of these reductions SEDIMOT I1 predictions under

in runoff from reclaimed areas to receiving streams will be local. of peak discharge and runoff volume

from the entire Coal Mine Wash watershed

postmining conditions at Site 18 (includes junctions I-XIV) were only slightly less than the runoff generated under premining conditions. Predicted peak discharge and runoff
Considering the order

volumes were reduced by only 2 percent and 3 percent respectively.

of magnitude of flows for which predicted runoff parameters were deternuned by SEDIMOT I1 up to junction XIV (lo3), these reductions are not slgniflcant. Also, juncLlon ?:IV was

established only a short distance downstream from these largely reclaimed watersheds in which runoff reductions were estimated at more than 20 percent.

The prediction results for modeling Coal Mine Wash drainage under pre- and postmining conditions suggest that, for a 24-hour duration storm of uniform distribution over the entire watershed, runoff reductions from reclaimed areas will be local and will result in insignificant reductions of runoff in the main channels. As runoff in the main channel

systems progresses downstream, encountering additional lateral inflow from undisturbed basins, localized runoff reductions will become less pronounced and unmeasurable.

Generally, an increase in total drainage area is accompanied by an increase in watershed discharge. Reclaimed areas on Black Mesa that will drain into the Moenkopi watershed

comprise only two percent of the total Moenkopi watershed above its confluence with the Little Colorado River. Slight reductions in runoff from reclaimed areas will not affect

the overall runoff from this watershed area; however, runoff from the large :Iralnaije areas above the village purposes. of Moenkopi near Tuba Clty has been utillied

for f l o o r i lirlgatlo!~

Reductions in runoff discharge in Moenkopi Wash from reclaimed areas on the

leasehold will not be detected some 70 miles downstream in the vicinity of Moenkopi.

Revised 12/01/83

Busby (1966) mentions that approximately 50 percent of the runoff produced in tributaries of the Little Colorado River is lost in transmission before reaching this major channel. Channel transmission and evapotranspiration losses of this magnitude would completely mask any runoff reductions from the small, reclaimed areas on the leasehold to recelvlng streams.

Sediment.

Sediment concentrations measured in receiving streams as part of monitoring (see Peabody Sediment

efforts by Peabody personnel commonly range from lo4 to lo5 mg/l Monitoring, Chapter 15).

Sediment yields (tons/day) have been determined on a storm basis

from measured discharges and sediment concentrations made at automated stream station sites on the leasehold. Measured sediment yields range from lo2 to lo3 tons per day for

low discharges, and up to lo5 tons per day in higher discharges (Automated Site Sediment Yield Analyses, Chapter 15, PAP).

Channel

contributions

to

measured

sediment

yields

were

estimated

uslng

SEDIMOT

I1

computations (see Coal Mine Wash Pre- and Postmining Sediment Yield Estimates, Chapter 15, PAP). Using a range of storms, peak discharge and sediment concentrations were predicted These

for the entire Coal Mine Wash drainage above the location of Stream Station 16.

predicted values were converted to tons per day and plotted on the sediment rating curve developed from data collected at Site 16 (Figure 22).
Regression

llnes definlng the

relationships among the measured and predicted values were determined and are labeled on Figure 22. Comparisons of the regression lines at various discharges suggest that

sediment contributions from the channel sides and bed to the main channel sediment load could be as high as 45 percent at discharges in the range of 3,000 cfs. It can be

concluded that the main channels of the principal drainages that disect the Black Mesa leasehold could contribute up to 45 percent of the total sedlment load discharge during large flow events.

Due to the likelihood of intense summer thunderstorms

occurring

on reclaimed areas, and

the highly erosive nature of topsoil material, sediment concentrations of runoff from reclaimed areas purposes of could approach concentrations premining conditions comparable to
receiving

streams.

For

comparing

(undisturbed) with

postmining

conditions

(reclaimed coal resource areas), sedimentation estimates in runoff from Coal Mlne Wash have been made using SEDIMOT I1 (see Coal Mine Wash Pre- and Postmlning Secllinent Yield Estimates, Chapter 15, PAP). The drainage area above the locatlon at which these

estimates were made comprised almost 43 square miles.

Sediment yield calculations were

4

m m

h

C

>',

.

i.

ni

..
1,000

.

.
100 10
118

10,000

Stream Discharqe ( c f s )

R e v i s e d 12/01/88

made assuming that the outlet of this drainage area 1s locatecl aiso1;i o:'r< ! . l ::e from the M-1 reclaimed area at Stream Statloln 1s. sediment concentrations
(1 to 23 percent) and

ti:-1..

!:rr-r~ea!r!

Results lCt!apcer if;, ihjw cleireased
( 1 to
3-1

sediment yields

percent) in

streamflow due to discharge from modeled watersheds vlthin the Coal Mine Wash watershed largely comprised of reclaimed areas.

Again, reclaimed topography, soils and vegetation modeled in the Coal Mine Wash drainage are typical of final reclamation to be established in all mined coal resource areas. Watersheds established in reclaimed coal resource areas will typically yield reduced peak sediment concentrations and sediment yields compared to premining conditions. The effect

of decreased sediment concentrations and yields in receiving stream runoff resulting from reclaimed area runoff will be local. Generally, as discharges increase in receiving

streams, reduced sediment contributions from watersheds largely composed of reclaimed areas become less pronounced. Model predictions for the entire Coal Mine Wash watershed

at Site 18 show a reduction in sediment yield (5 percent) and a 1 percent increase in peak sediment concentration for postmining
conditions.

The

order

of

magnitude

for boch In these

predicted parameters is lo5, which diminishes the significance of the d;ff?rence parameters between premining and postmining conditions.

As

flow

in

receiving

streams

proceeds

downstream,

lateral

inflow

from

undisturbed

watersheds will contribute to sediment loads in the main channels.

These additional

contributions will tend to mask the localized decreases in sediment loads resulting from watersheds comprised mainly of reclaimed areas. Finally, sediment yield contributions

from channel beds and sides may be as high as 40 percent, which will offset the predicted reductions in sediment loads from reclaimed areas. loads are predicted to completely mask the Channel contributions to sediment effects of reclaimed area

localized

contributions in the downstream direction.

Plater Quality.

Receiving stream-water quality has been inonitored since 1381 at Stream Permanent

station sites on the leasehold (see Stream Water Quality Section, Chapter 15). internal impoundments
( P I I ) established

in both pre-law and post-law reclslrnect areas ol i for water quallty. Prevlous:l). ii?troitu~ed

Peabody's leasehold have also been

sampled

tables 27 and 28 are summaries of sample means for selected inajoz rhernlcai pa!:arneters. Table 27 presents mean parameter values measured in PII's from 1996 chrough 2J00 that were constructed in both pre-law and post-law areas, and Table 28 presents mean parameter values measured at stream station sites for the same period. 119 P,t.~,~~sed 11/21/03

Generally, PII's created in pre-law areas have water quality similar to post-law areas. Runoff flowing into PII's in pre-law areas occurs on regraded spoil material. Although

post-law areas were topsoiled, comparisons using mean parameter values from post-law and pre-law PII's indicate no significant differences in the quality of water flowing over spoil material versus topsoil material.

Mean chemical parameter values from PII's are similar to but slightly lower in range and magnitude compared with stream flows, with the exception of PII's MI-RA and N2-RA. Mean

pH measured in PII's range between 7.5 and 8.6 (except PI1 N1-RA), while stream pH values range similarly between 8.0 and 8.3. amount of high-TDS water Excepting PI1 142-RA, which receives a significant spoil in addition to runoff from reclaimed

from resaturated

areas, mean TDS in PII's (133 to 939 mg/l) range lower than rainfall runoff measured in receiving streams (231 to 1489 mg/l). Although the mean values presented in Tables 27 and

28 indicate variability among PII's and stream flows, generally, TDS, sulfate, caiclum, magnesium, sodium, and chloride are slightly lower in PII's compared with stream flows.

Tables 29 and 30 (previously discussed) indicate that water quality in most PII's and streams fall within the livestock drinking water limits (based largely on dissolved (MNEPA, 1999; Hopi, 19981,

analyses of trace metals)

recommended by Tribal agencies

National Academy of Science (1974) and the USEPA (1995). Limited exceptions include high pH values in PI1 N1-RA, high TDS values in PI1 N2-RA, and infrequent exceedences of a limited number of the livestock drinking water limits at several stream sites.

Runoff water quality from reclaimed areas (including pre-law areas not topsoiled) will not significantly alter receiving stream water quality, nor change the potenti-a1 use of biith the

receiving stream flows.

Mixing of any infrequent pond discharge from "1's

larger volumes of stream flow runoff will provide a slight diluting effect, rendering any potential impact on receiving stream
water

quality insignl.ficant.

The Impact of the Reclamation Plan on the Stability of Reclaimed Areas.

Reclainatlon of Common

coal resource areas on PCC's Black Mesa leasehold occurs in a seml-arid climate.

products of this climatic regime include flash floods in ephemeral channels resulting from very intense summer thunderstorms. Drainages exhibit high degrees of drainage densities,

severly eroded landscapes of moderate to high relief, entrenched sandbed channels and the continual evolution of rills and gullies in the upslope portions of drainage basins.

No physical measurement guidelines have been found chat provide ciistinctior!~between rills and gullies. Generally, gullies are classified a-, large rllls.
~:IL:F!!-:~LL~L,:!!:I<>I?

:,f

the

processes that form rills and gullies has not !ylelcIsd conclusive results. been classified as continuous or discontinuous (Leopold and Miller, 1956).

G u l l ~ e s have Continuous

gullies begin their downstream course with many small rills, while discontinuous gullies start with an abrupt head cut (Heede, 1975). Most rills and gullies that form naturally

on Black Mesa are continuous, as abrupt head cuts in these systems are not commonplace, occurring only where lithologic controls predominate.

Several key factors contribute to the formation of rills and gullies in the semi-arid southwest. Intense thunderstorms commonly generate large raindrops thar Impact soil The raindrop impacts detach soil particles, The k i n e ~ i cenergy imparted by very intense The

surfaces with high degrees of kinetic energy. which are then entrained by overland flow.

rainfall tends to seal some soil surfaces rapidly, concentrating overland runoff.

disruption of the soil surface and concentration of overland flow during a storm event creates an opportunity for the establishment of small rills.

Another

major

influence

is

the

vegetative

canop:;

covering

th3

soil

s::rface.

The

vegetative canopy intercepts a portion of the total rainfall volume reducing the potential for rapid runoff. The vegetative cover tends to reduce the energy of the raindrop

impacts, thereby lessening the degree to which the soil surface is impacted and the quantity of detached soil particles.

The tendency of a soil to erode occurs.

(detachment, also affects the degree to which rilling

Sandy textured soils have a higher susceptibility for detach~nent than soils high The presence of organic matter tends to provlcle soil cohesiveness, Topsoil material present on the leasehold

in clay content.

reducing the possibility of soil detachment.

tends to have a sandy texture and be low in organic matter and clay content.

Morphologic factors such as slope steepness, length, shape and drainage density affect the rilling process. The tractive force, a measure of detachmenr potential of flow, increases Runoff increases ~ic!! dlstance ?is the length

With slope steepness (Meyer, Foster and Romkens, 1975).

from the tops of slopes, as the contributing drainage area above increases. of slopes increase so does the potential for rlll and gully cievelopmelnt.

'The shape of an

irregular slope will affect the development of rills depending on the interrelationships

121

Revised 12/01/88

of slopes and

slope lengths.

Natural basins will establish

dralinaye !ietwo!-l:s of a

sufficient density to carry excess runoff to the Sasln outlet.

Although ~ 1 1 1 sai?d gullies

are small in comparison to main channels, they are an lntegral parc of a basin's dralnage netv~ork.

Many

theories

and

concepts have

been

developed

in the

literature

that

explain

the

development of rills in gullies in semi-arid environments.

Schumm and Hadley

(1957)

proposed a model of semi-arid erosion in which channels (including rills and gullies) adjust, by either aggrading or downcutting, to variations in sediment loads and discharge. Bergstrom and Schumm (1981) discuss a model based on the eplsodlc behavls!: of a iiralnag? basin, in which distinct zones of a '..iatershed ad-tiist channel i_.inarac:ei'li-~ : to episodic changes in f1oi.i and sediment b l l tlme. iti
I!: :

-=~.ui~i;se

The coi?cept of :?c!~lii!~~i~im 1s

discussed at length by Schumm (1977), and involves the complex process-response concept of a fluvial system.

Regardless of whether the drainage systems on Black Mesa are in quasi-equilibrium, or whether their development over time may be explained by a model, several factors

influencing the development of rills and gullies in these drainages and in reclalrned areas remain constant. Intense summer thunderstorms occurring on Black Mesa generace highP-lso, the vegetation canopy

energy raindrops that result in considerable soil detachment.

cover to be successfully established in coal resource areas will be similar to canopy covers found in the natural surrounding landscape. Topsoil material used as plant-growth

media in reclaimed areas has the same erosive texture as soils found in the surrounding highly eroded landscape. Natural drainages on Black Mesa exhibit a high degree of Regardless

density, naturally forming rills and entrenched guLlies In the upland areas.

of the extent of vegetal cover or the flatness of the regraded slopes, rills are qoing to
- form in the reclaimed areas as the baslns adlust clrainacje to i:on.;ey e . , e s i.ii:i>rr. Saixner .::i

thunderstorms

are

intense

and

localized

resulting

in

overland

flobi

that

rapidly

concentrates and scours in relatively short distances.

Peabody has developed a plan for insuring the stability of reclaimed areas (see Chapter
26).

The key to the plan is to control those components of the surface runoff process to for erosion is greatly minimized. By cointrolling the

the extent that the potential

erosive nature of the surface runoff the degree of rilling and gullying will be minimized such that sufficient landform stability can be achieved and a successful .'egetative can be developed that will promote the postmining wildlife habitat.
122

cover

land use of livestock grazing and

Revlsed 12/31/88

An important component of the plan (see Chapter 26) is to construct gradlent terraces with slight positive drainage (no greater than 2 percenc) on reclaimed slopes ( q z s a c e ~than 10 percent) that have high potentials for ezcesslve erosion and uncontrolled drainage

development (rills and gullies). upslope area contributions

These terraces will break up slope lengths, llmlting the flow. Distances over which tractive forces

to overland

increase will be controlled, which will limit the scouring action of concentrated runoff in the downstream direction. By establishing limited drainage areas between the contour

terraces, the size and density of rills that occur will be minimized.

Primary surface manipulations include:

1) deep ripping on all slopes

;

and 2) contour

furrowing using an offset disk unit that will promote inflltratlon and recl~~ce e:ccess runoff. The retopsoiled areas, including contour terraces, will be mulc!??cl l!c a cover bih

crop or anchored straw or hay mulch, and then revegetated w ~ t hthe permanent seed mlxes (see Chapter 26). Revegetation and mulching will promote soil cohesiveness as vegetation

becomes established, providing further resistance to rilling.

In addition to the creation of gradient terraces and the surface treatments, a network of downdrains and main channels will be constructed. Downdrains wlll be established at

specific intervals across the slopes for connecting the contour terraces to the main channel. Downdrains will enhance the stability and integrity of the contour terraces, as

they will convey runoff from the inter-terrace areas to the main channel without promoting failure of the terraces. An important feature of the plan is the sizing and lengths of Terrace embankment heights and lengths will be to increase the

the terraces between the downdrains.

maximized to insure the containment of concentrated overland runoff and time of concentration of flow to the downdrains, respectively.

Thls should greatly

reduce the potential for extreme downcutting in the downdrains.

The downdrain replaced. feet

systems will be

constructed

ii r

some

linstarices after

';~pi(jll i:a5

beein

Under these circumstances, topsoil will be removed at a minimum wldth of 45 topsoil loss. Ripping and disking will be implemented across the

to prevent

downdrain system creating a surface roughness perpendicular to flow. some resistance to scour in the downdrain. contain a significant percentage of rock

This will provide

In addition, the non-topsoiled drains will fragments further increasing the surface

roughness.

The main channels will be engineered to convey the appropriate discharge contributed by

123

Revised 12/01/88

the watershed areas drained.

The main channels will range in width from approximately 45
The main

to 135 feet which includes a fifteen foot apron on each side of the channel. channels and aprons will not be topsoiled to prevent topsoil loss.

Application of the

seed mixes will be used to revegetate and further stabilize the non-topsoiled areas.

The establishment of the drainage network outlined above will increase the overall time of concentration of flows and reduce peak flows from the reclaimed area baslns. Flow in

velocities will be controlled, as surface manipulations, including those performed downdrains and the main channels, provide roughness and resistance to scour.

Thus,

drainage development in reclaimed areas will be planned and controllecl, the number and size of rills.

hereby rnlnlrnizing

Landform stability and vegetative develop men^ supportive of

the post-mining land use can be achieved, because the reclaimed area drainage development will have been controlled and reasonably stabilized rather than in a state of quasiequilibrium between storms of large return periods as in the natural drainage system.

Summary

This

chapter

has

presented

a discussion

of

probable

hydrologic

consequences

of

the

proposed life-of-mine mining plan.

Table 30 summarizes the discussion by listing the As can be seen,

probable hydrologic consequences and the results of the analysis of each.

all the probable impacts have been determined to have either no impact or no short or long term significant impacts.

Revised 12/01/8E

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Literature Cited

Bergstrom,

F.W.

and

Schumm,

S.A.

"Episodic

Behavior

in

Badlands."

Iinternational

Association of Hydroloqical Science, Pub. 132, (1981): p. 478-489.

Botz, M.K. and Pedersen, D.

"Summary of Water Quality Criteria".

Water Quality Bureau, 1976.

Montana Department of Health and Environmental Sciences.

Helena, Montana.

Brown, J. G., and J. H. Eychaner, 1988. Simulation of Five Ground-Water Withdrawal Projections for the Black Mesa Area, Navajo and Hopi Indian Reservations, Arizona. U. S Geological Survey Water-Resources Investigations 88-4000, 51 p.

Busby, M.W. Atlas.

"Annual Runoff in the Conterminous United States." 1966.

USGS Hydroloqic Inventory

HA-212.

Dollhopf, D.J.; Goering, J.D.; Levine, C.J.; Bauman, B.J.; Hedberg, D . W . ; "Selective Placement of Strip Mlne Overburclen ln Mo:?tana, Report: July 1976 to June 1981. Contract No. H0262032.
' 1

a n 3 R.L. Hodder.
P~~,JLI;."

Sawi:ary

Fl!ial
Sta.

Montana Ayric. Ei:p.

June, 1981.

Dollhopf, D.J.; Goering, J.D.; Levine, C.J.; Bauman, B.J.; and R.L. Hodder.

"Selective Interim

Placement of Coal Strip Mine Overburden in Montana, IV Hydrogeologic Studies." Report: 1979. July 1978 to June 1979. Contract No. H0262032.

Montana Agric. Exp. Sta.

Dollhopf, D.J. and Russell, L.J. Plains."

"Assessment of Acid Producing Materials in the Northern

Third Biennial Symposium on Surface Coal Mine Reclamation on The Great Plains. 1984.

Billings, Montana. pp. 201-208.

Eychaner, J.H.

"Geohydrology and Effects of Water Use in the Black Mesa Area, Navajo and U.S. Geoloqical Survey Water Supply Paper '201. p.

Hopi Indian Reservations, Arizona." (1983): 26.

Galloway, Devin, Jones, D.R., and Ingebritsen, S.E., 1999, Land subsidence in the United States: U.S. Geological Survey Circular 1182. 133 Revised 11/21/03

GeoTrans, Inc.,

1987. A Two-Dimensional,

Finite-Difference

Flow Model

:Slm~~latlng the

Effects of Withdrawals to the N Aquifer, Black Mesa Area, Arizona. Prepared for Peabody Coal Company.

GeoTrans,

Inc.,

1993.

Investigation

of

the

M-

and

D-Aquifer

Geochemistry

and

Flow

Characteristics using Major Ion and Isotopic Chemistry, Petrography, Rock Stress G.nalyses and Dendrochronology in the Black Mesa Area, Arizona. Prepared for Peabody Coal Company, June 1993.

GeoTrans, Inc., 1994. An Assessment of the Suitability of the U. S.G.S. W-Aquifer Model for Predicting the Effects of Peabody Western Coal Company's Pumpage, and other Related Studies.

Harbaugh, A.W., 1990, A computer program for calculating subregional water budgets using results from the U.S. Geological Survey modular three-dimensional ground-water flow model: U.S. Geological Survey Open-File Report 90-392, 16 p.

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"Stages of Development of Gullies in the West."

In Present and Prospective

Technology for Predicting Sediment Yields and Sources, ARS-S-40, June 1975:

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Hill, M. C.,1991. A Computer Program (MODFLOWP) for Estimating Parameters of Transient, Three-Dimensional Ground-Water Flow Model Using Nonlinear Regression. U.S. Geological

Survey Open-File Report 91-484, 358 p.

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"Draft Hopi Water Quality Standards", 1998, 40 pp.

Jacob, C.E. and Lohman, S.W. Extensive Aquifer."

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American Geophys. Union Trans.

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"Ephemeral Streams-Hydraulic Factors and Their Relation (1956): 37.

U.S. Geological Survev Professional Paper 282-A.

Littin, G. R., and S. A. Monroe, 1995. Results of Ground-water, Surface-brater, and Waterquality Monitoring, Black Mesa Area, Northeastern Arizona1992-93. U. S. Geological

Survey Water-Resources Investigations Report 95-4156, 37 p.

Littin, G. R., and Monroe, S. A , , 1997, Ground-water, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona B 1996. U. S. Geological Survey Open-File Report 97-566.

Lohman, S.W. (1972): 70.

"Ground-Water Hydraulics."

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Lopes, T. J., and J. P. Hoffman, 1997. Geochemical Analyses of Ground-Watel- Ages, Recharge Rates, and Hydraulic Conductivity of the N Aquifer, Black Mesa Area, Arizona.
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McDonald, M.G., and Harbaugh, A.W., 1988. A modular three-dimensional finite-difference ground-water flow model: U.S. Geological Survey Techniques of Water Resources

Investigations, book 6, chapter Al, 586 pp.

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"Water Quality Criteria."

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State Water Resources Control Board Publication NO. 3-A.

McWhorter, D.B. Surface Mining."

"Procedures for Predictive Analysis of Selected Hydroloq~c Impacts of E.P.A. Cincinnati, Ohio. (19823: 28.

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in Present and Prospective Technoloqv for Predictinq Sediment Yields and ARS-S-40,

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Water Oualit:~ Criteria,

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Trescott, P. C., G. F. Pinder and S. P. Larson, 1976. Finite-Difference Model for Aquifer Simulation in Two Dimensions with Results of Numerical Experiments. U.S. Geological Survey Techniques of Water-Resources Investigations, Book 7, Chapter C1, 116 p.

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Van Voast, W.A. and Hedges, R.B.

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"Wash

Plant

Refuse

Dlsposal

Hydrologic

Impact

Evaluation Report".

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as in,

Northeastern

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to

Paleoclimatic

Changes

During

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Late

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Revised 11/21/03

Attachment 3

FINAL WASH-PLANT REFUSE DISPOSAL HYDROLOGIC IMPACT EVALUATION REPORT
Black Mesa Mine Complex Kayenta, Arizona

Prepared for:
Peabody Western Coal Company

December 18,2003

II

II

- 743

Horizon Court, Suite 330 Grand Junction, Colorado 81506
(970) 242-0170

CONTENTS

EXECUTIVE SUMMARY.............................................................................................................. ES- I INTRODUCTION.................................................................................................................. . 1 1 1.1 Background .............................................................................................................. 1 - 1

HYDROGEOLOGIC SETTING ..........................................................................................2-1 2.1 2.2 Geology ....................................................................................................................... 2-1

Hydrogeology ............................................................................................................. -2-2

REFUSE DISPOSAL SITE EVALUATION ........................................................................ 3-1 3.1 3.2 3.3 3.4 3.5 Potential Refuse Disposal Sites .................................................................................... 3-1 Evaluation Criteria .......................................................................................................3-1 Evaluation Process .......................................................................................................3.2 Site Visit ...................................................................................................................... 3-3
. .

Data Compilation and Findings .................................................................................... 3-3 3.5.1 Depth to Groundwater .....................................................................................3-4 3.5.2 Potential for Resaturation of Spoils................................................................3-5 3-5 3.5.2.1 Pit Infiows ....................................................................................... 3.5.2.2 Well and Borehole Logs ...................................................................3-5 3.5.2.3 Wepo Well Water Levels .................................................................3-6 3.5.2.4 Hydraulic Testing Data ..................................... ,.............................3-7 . 3.5.3 Background Geochemistry ...............................................................................3-7 3.5.4 Disposal Area Storage ...................................................................................... 3-8 Sitespecific Interpretation...........................................................................................3-9 : ..................3-10 3.6.1 5-23 Mine Area ........................................................................... 3.6.2 N-6 and J-7 Mine Areas ................................................................................ 3-11 3.6.3 5-3 Mine Area ............................................................................................... 3-12

3.6

HYDROLOGIC IMPACT ANALYSIS ............................ ................................................... 4-1 4.1 Summary of Regulations ............................................................................................... 4-1
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Contents

4.2

Refuse Disposal Conceptual Model .............................................................................. 4-1 4.2.1 N-6 Pit ............................................................................................................ 4-2 4.2.2 J-23 Pit ........................................................................................................... 4-3 Technical Approach ....................................................................................................-4-3 4.3.1 Water Quality ................................................................................................. -4-4 4.3.1.1 Data Collection, Compilation. and Reduction ................................... 4-4 4.3.1.2 Analysis and Interpretation............................................................... 4-5 4-8 4.3.2 Refuse Leachate Fate ....................................................................................... 4.3.2.1 Refuse Transient Drainage .............................................................. -4-9 4.3.2.2 N-6 Pit Saturated Flow and Transport Analysis .............................. 4-12 4.3.2.3 5-23 Pit Numerical Flow and Transport Analysis ............................4-16

4.3

5.0

SUMMARY AND CONCLUSIONS......................................................................................5-1
5.1 5.2 5.3 5-1 Refuse Disposal Site Evaluation and Selection.............................................................. Probable Hydrologic Impact Assessment ....................................................................... 5-2 Conclusion................................................................................................................... 5-4

6.0

REFERENCES....................................................................................................................... 6-1

FIGURES

Black Mesa Mine Complex Location Map. Transmissivity versus Elevation for Wepo Aquifer Wells. N-6 Pit Boundary With Bottom of Coal Topography and Wepo Aquifer Potentiometric Surface. Schematic Cross-Section of N-6 Pit with Wash-Plant Refuse Disposal. J-23 Mine Area with Bottom of Coal Topography and Wepo Aquifer Potentiometric Surface. HYDRUS2D SimuIation Results: Pressure head at time = 600. 000 days for N-6 Pit refuse transient drainage. N-6 Pit Refuse Transient Drainage. HYDRUS2D Simulation Results: Pressure head at time = 600. 000 days for J-23 Pit refuse transient drainage. 5-23 Pit Refuse Transient Drainage. HYDRUS2D Simulation Result: Infiltration of Refuse Leachate in the Wepo Formation showing pressure head distribution.
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Contents

4.9

HYDRUS2D Simulation Result: Infiltration of Refuse Leachate in the Wepo Formation showing solute concentration.

TABLES

Data Types Available and Evaluated for Potential Refuse Disposal Site Assessment. Wepo Aquifer Hydraulic Testing Results. Comparison of Summary Statistics for Metals Concentrations in Groundwater Samples Collected from Site-Wide and Local-Area Wells. Comparison of Summary Statistics for Inorganic Concentrations in Groundwater Samples Collected from Site-Wide and Local-Area Wells. Results of Synthetic Precipitation Leaching Procedure for Metals in Peabody Interburden Core Samples. Soil Toxicity and Acid Parameter Analytical Results for Interburden and Overburden Composite Samples from Coreholes. A Comparison of Summary Statistics for Refuse Samples (SPLP Metals) and Groundwater Samples Collected from the Site-Wide Well Network, J-23 Area, and N-6 Area. A Comparison of Summary Statistics for Inorganic Concentrations in Refuse Samples (SPLP and Paste Extraction) and Groundwater Samples Collected from the Site-Wide Well Network, J-23 Area, and N-6 Area. Solute Concentration Mixing Calculations.

APPENDICES

A
B C

Corehole and Well Borehole Summaries Wepo Well Hydrographs Calculations

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EXECUTIVE SUMMARY
Peabody Western Coal Company (PWCC), retained Western Water & Land, Inc. (WWL) to assist in the process of preparing a comprehensive revision to the Mining and Reclamation Plan for the Black Mesa and Kayenta Mines (Black Mesa Mine Complex - BMMC). This revision includes the construction and operation of a coal wash plant facility at the Black Mesa Mine. The coal-washing facility will be used to refine the separation of coal and mine waste materials. It is estimated that the coal-washing facility will produce approximately 1.38 million tons per year of mine waste (refuse) materials. Preliminary wash plant design forecasts a mixture of coarse (plus 100-mesh) and fine (minus 100-mesh) materials will be produced as refuse. Total annual refuse should be approximately 1.38 million tons per year, made up of about 0.62 million tons of coarse materials with a 7.0 percent surface moisture, and about 0.76 million tons of fine materials with a 40 percent surface moisture. Western Water & Land, Inc. (WWL) was retained by PWCC to evaluate the potential hydrologic impact to wash-plant refuse disposal at the BMMC. The assessment will be incorporated into the upcoming mine-plan revision to support plans for proper disposal of the wash-plant refuse in accordance with regulations promulgated as part of the Surface Mining Control and Reclamation Act of 1977. The work included the following tasks: 1) evaluate potential refuse disposal sites, 2) recommend the most favorable site with regard to minimizing hydrologic impact, and 3) analyze the potential hydrologic impact of refuse disposal at the recommended site. This report presents the results of these tasks. WWLYs technical approach involved a detailed examination of each potential refuse disposal site within the following Coal Resource Areas (CRAs): N-6,J-3,J-7, and 5-23. The primary evaluation criteria included: Depth to groundwater Potential for re-saturation of replaced spoil
0

Background geochemistry Available refuse storage space

Data and information examined to support these criteria are shown in Table 3.1, and primarily included groundwater occurrence and behavior information, water quality data, Wepo Formation characteristics (corehole data), and potential storage volume. General information collected during a site visit was also used.
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WWL concluded that the 5-23 CRA presents the most favorable characteristics for refuse disposal that will result in minimal hydrologic impact. The 5-23 CRA will not be developed until 201 1, 2 to 3 years after the wash plant begins operation. However, the estimated bottom of the pit will be at least 150 ft above the interpreted Wepo Aquifer potentiometric surface. In addition, the interpreted potentiometric surface is relatively uniform, of low gradient and does not diverge or converge to a local discharge area (surface drainage). The 5-23 CRA is expected to have sufficient storage volume for refuse disposal, as mining operations are expected to remove 5,000,000 cubic yards of coal annually. The estimated volume of wash-plant refuse produced on an annual basis is 1,000,000 yds3. CRAs N-6 and J-7, which are active pits nearing the end of their mineable resources, were considered areas of potential greater impact because the interpreted Wepo Aquifer potentiometric surface extends upwards of 30 feet above the estimated bottom of the pits. In addition, the final footprints of the N-6 and 5-7 pits will be in close proximity (500 ft) to the major surface-water drainages of Coal Mine Wash and Yucca Flat Wash. The N-6 and J-7 pit bottom elevations would be below or near the surface elevations of these drainages, presenting another potential hydrologic impact should groundwater migrate from the pits. The 5-3 Reclaimed CRA was mined in the 1970s and 1980s and is now fully reclaimed. The 5-3 Reclaimed CRA may have a potential for hydrologic impact in the long-term as the interpreted Wepo Aquifer potentiometric surface forms a hydraulic divide along the ridge where J-3 is located. Should refuse leachate migrate to a continuous saturated zone in the Wepo Formation, groundwater flow has the potential to occur in multiple directions at relatively moderate to steep hydraulic gradients. Groundwater underlying the 5-3 area may eventually discharge into Coal Mine Wash to the west and Moenkopi Wash to the southeast. Although the 5-23 CRA was selected as the most favorable site for minimal hydrologic impact, it is anticipated the area will not be fully developed and able to receive refuse for a period of 2 to 3 years after start-up of the coal wash plant. Therefore, PWCC directed WWL to evaluate hydrologic impact of a 3 year disposal scenario at the N-6 pit and long-term disposal at the 5-23 CRA. The technical approach used to assess the potential hydrologic impact of wash-plant refuse disposal in the N-6 and 5-23 CRAs focused on the following tasks: 1. A comparison of ambient groundwater and surface water quality to the potential chemical composition of refuse leachate water

ES-2

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Executive Summay

2. A study of the fate of refuse leachate (potential quantity and migration from the refuse disposal area) The objective of the first task of comparing the water quality of ambient Wepo Aquifer and estimated refuse leachate was to evaluate the potential for refuse leachate to degrade ambient groundwater quality in the Wepo Aquifer. This work was conducted by an in-depth data compilation, reduction, and statistical analysis. The objective of the second task, the evaluation of leachate fate, was to evaluate leachate quantity and the potential migration from the disposal sites. This task was assessed by the use of analytical and numerical flow and transport models. The data generated to approximate the leachate composition of the wash-plant refuse consisted of 23 (including 2 duplicate samples) interburden samples obtained from a corehole drilling program conducted in the summer of 2003. The core samples consisted of Wepo strata composited from within mineable coal seams or thin non-coal strata immediately below the mineable seams. The samples were submitted to the analytical laboratory for Synthetic Precipitation Leaching Procedure (SPLP) analysis of metals and wet chemistry parameters. The core samples were also analyzed for total metals and soil characteristic parameters. The results of Task 1, the comparison of ambient water quality of the Wepo Aquifer with analytical data generated to approximate the leachate composition of the wash-plant refuse, indicated that leachate produced as a result of acid rain infiltrating the refuse material likely contains higher concentrations of aluminum, arsenic, barium, mercury, selenium, vanadium, and zinc than does natural groundwater in the vicinity of the J-23 and N-6 Mining Areas. It is expected that metals concentrations in groundwater induced leachate would likely be less than those reported on the basis of the SPLP analyses. On the basis of the saturated paste extraction results, nitrate and nitratelnitrate concentrations are expected to be higher in the refuse material than in natural groundwater in the vicinity of the N-6 Mining Area. Nitrate and nitratelnitrite concentrations are expected to be less in the refuse material than in natural groundwater in the vicinity of the 5-23 Mining Area. Analyte concentrations in leachate derived from the refuse material are expected to be similar or less than the concentrations in natural groundwater for the other metals listed in Table 4.1 and inorganic constituents listed in Table 4.2. The potential accumulation and migration of refuse leachate from the refuse disposal areas in the N-6 Pit and 5-23 Pit were studied through the use of the application of the unsaturated flow and transport model

HMRUS~D@,and a two-dimensional analytical saturated flow model, (TDAST~).

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HYDRUS2D was initially used to evaluate transient drainage of the refuse. The results of the transient drainage simulations showed that drainage of the refuse would take hundreds of years, and that little drainage would be realized during mining operations. In the extreme long-term, a simulation for over a time of 600 years, the generated leachate would be equivalent to approximately 5.3 ft (1.6 m) of saturated thickness in the refuse. Long-term fate of the leachate was further modeled using TDAST at the N-6 Pit and HYDRUS2D at the 5-23 Pit. In the case of the N-6 Pit, it was conservatively assumed that, in a worse-case scenario, pit inflows into the pit from the Wepo Aquifer would eventually saturate the refuse deposits placed in the pit. TDAST results indicated that only a fraction (approximately 0.07) of the leachate solutes would be present a distance 500 ft downgradient of the pit after 25 years of simulated transport. The addition of solutes in the ambient Wepo Aquifer groundwater resulted in a minor increase in overall solute concentrations. A mixing calculation shown in Calculation No.2 (Appendix C) and Table 4.5 also showed minimal change in ambient Wepo groundwater quality. The 5-23 Pit was evaluated for potential leachate migration by way of unsaturated flow into the underlying Wepo Aquifer. A one-dimensional application of HYDRUS2D was used to assess unsaturated flow into the Wepo Formation below accumulated drainage from wash-plant refuse. The results of the HYDRUS2D simulation showed that unsaturated flow and solute transport of refuse leachate in the Wepo Formation is limited to a saturation depth of 8 ft (2.4 m) (Figure 4.8). Increases in water content, i.e. the wetting front, occurred at approximately 30 f (9 m) below the refuse/Wepo contact. t Solute transport simulations (Figure 4.9) confirm this conclusion, and show that solute concentrations after 200 years of infiltration are equal to or less than 0.2 of the original leachate concentration at a depth 32.8 ft (10 m) below the refuselwepo contact. On the basis of the HYDRUS2D simulations, unsaturated flow and solute transport of the refuse leachate is extremely limited and will not approach the interpreted Wepo Aquifer potentiometric surface below the J-23 Pit within a 200-year period. It is also important to note that should refuse leachate with its full source concentration infiltrate into a continuous saturated zone of the Wepo Aquifer, the resulting concentrations of solute would be similar to the results of the TDAST simulations performed for the N-6 Pit. Saturated simulations of solute transport for the 5-23 pit would result in smaller concentrations than the N-6 Pit simulations (for the same time and distance), because the 5-23 Mine Area is characterized by a smaller hydraulic gradient.

ES4

Western Water & Land, Inc.

Executive Summay

Conclusions

The 5-23 Mine Area provides the most favorable Iocation for disposal of refuse generated by coalwashing operations to be conducted at the BMMC. The pit in the J-23 area will be located in an area where the projected potentiometric surface of the Wepo Aquifer exhibits a relatively uniform and low hydraulic gradient, the bottom of the pit will be located approximately 150 ft above the projected potentiometric surface of the Wepo Aquifer, and no primary surface water drainages are located in the immediate vicinity of the pit. The interim use (3 years) of the N-6 Pit and long-term use of the J-23 Pit for wash-plant refuse disposal will result in minimal increases in water quality analyte concentrations in the case of saturated flow in the Wepo Aquifer and minimal migration in the case of unsaturated flow. Overall, the disposal of wash-plant refhe at BMMC will have a negligible impact on water quality and quantity in the mine area.

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I.O INTRODUCTION
,

Peabody Western Coal Company (PWCC) is preparing a comprehensive revision to the Mining and Reclamation Plan for the Black Mesa and Kayenta Mines (Black Mesa Mining Complex - BMMC). This revision includes the construction and use of a coal wash plant facility at the Black Mesa Mine. The coalwashing facility will be used to refine the separation of coal and mine waste materials. It is estimated that the coal-washing facility will produce 1.38 million tons per year of mine waste (refuse) materials. Western Water & Land, Inc. (WWL) was retained by PWCC to (1) evaluate potential refuse disposal sites, (2) recommend the most favorable site with regard to minimizing hydrologic impact, and (3) analyze the potential impact of refuse disposal in the recommended site(s). This report presents the results of these tasks and is organized in the following main sections: 1.0 2.0 3.0 4.0 5.0 Introduction Hydrogeologic Setting Refuse Disposal Site Evaluation Hydrologic Impact Analysis Summary and Conclusions

I .I

Background

PWCC owns and operates the Black Mesa and Kayenta surface mines. The mines, collectively referred to as the Black Mesa Mine Complex (BMMC), are located approximately 15 miles southwest of the town of Kayenta, Arizona on approximately 101 square miles of land leased fkom the Navajo Nation and Hopi Tribe (Figure 1.1). Collectively, the mines produce approximately 12 million tons per year of coal used to generate electricity. The Black Mesa Mine began operation in 1970, and currently produces approximately 4.6 million tons of coal from two active pits. The Kayenta Mine began full production in 1973. The Kayenta Mine currently produces approximately 7.8 million tons of coal from three active pits. PWCC is preparing to file a substantial revision to the mining and reclamation plans for the mines to extend mining through calendar year 2025. The Black Mesa Mine plans to routinely clean coal using a wash plant facility in order to meet their customer's coal quality requirements. Life-of-mine plans for the Black Mesa Mine anticipate average annual coal production to be about 6.2 million tons of coal. A

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Introduction

majority of this annual coal production will be washed at the plant, and result in refuse material that will be disposed of at an appropriate site near the plant. Preliminary wash plant design forecasts a mixture of coarse (plus 100-mesh) and fine (minus 100-mesh) materials will be produced as refuse. Total annual refuse should be approximately 1.38 million tons per year, made up of about 0.62 million tons of coarse materials with a 7.0 percent surface moisture and about 0.76 million tons of fine materials with a 40 percent surface moisture.

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2.0 HYDROGEOLOGIC SETTING
The hydrogeologic setting described in this section focuses on the geology and hydrogeology of the Wepo Formation and the underlying Toreva Formation and Mancos Shale. These strata are of most interest and concern with respect to evaluating the probable hydrologic impacts of wash-plant refuse disposal. The source of information for this section originates from the Geology (Chapter 4) and Hydrologic Description (Chapter 15) sections of the Mining and Reclamation Plan (MRP) for the Black Mesa and Kayenta Mines (PWCC 1985a). For a more complete description of the main aquifer units on the Black Mesa please see this reference.

2.1

Geology

This section summarizes the hydrostratigraphy of the coal-bearing and underlying strata. The geology and hydrology of the Black Mesa Mine area is discussed in detail in Chapters 4 and 15 in the MRP (PWCC 1985a). The Black Mesa is an extensive plateau whose rim is defined by Cretaceous-age rocks of the Mesaverde Group. Coal deposits mined at the Black Mesa Complex occur within the Wepo Formation, the middle member of Mesaverde Group. The Wepo Formation is underlain by the Toreva Formation and overlain by the Yale Point Sandstone. All three formations are present only on Black Mesa. The Mesaverde Group is underlain by the Mancos Shale, also of Cretaceous age (F'WCC 1985a). Geologic formations older than the Mancos Shale are discussed in Chapter 4 of the PWCC mine permit (PWCC, 1985a). The Wepo Formation consists of a thick sequence of interbedded mudstone, siltstone, sandstone and coal. The thicker sandstone beds tend to have conglomeratic bases of chert and silicified limestone pebbles. The Wepo Formation ranges from approximately 320- to 740-feet (ft) thick on the Black Mesa and is approximately 6 4 0 4 thick in the mine area. The formation dips gently to the west. Some clinker or burn (burned coal and baked shale) areas are present in the upper part of the Wepo Formation and occur as resistant ledges, ridges, or knobs on the surface. Coal strata in the Wepo Formation occur in seven somewhat consistent horizons identified in descending order as 1) violet, 2) green, 3) blue, 4) red, 5) yellow, 6) brown, and 7) orange. The mineable coal strata vary from 3- to 8-ft thick, infrequently coalescing to 20-ft thick beds. Generally, the coal is considered to be primarily of durain and fusain composition, derived from sedges and grasses rather than decomposed swampy forests (PWCC, 1985a).

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Overburden and interburden thickness in the area of the mine pits varies from approximately 200 ft to 220 ft. The underlying Toreva Formation in the south portion of Black Mesa consists of three members: (1) the upper sandstone member; (2) the middle carbonaceous shale member; and (3) the lower sandstone member. The upper sandstone member is a poorly-sorted fine to coarse-grained sandstone. The middle carbonaceous shale member is in gradational contact with the lower sandstone member and consists of thinly-bedded carbonaceous mudstone, varicolored siltstone units with coal, and thick lenses of poorly sorted fine-to coarse-grained sandstone (PWCC, 1985). The lower sandstone member consists of fine- to medium-grained quartz sandstone. The lower part of this member may have units of thin-bedded siltstone and finegrained mudstone as it transitions to the underlying Mancos Shale (PWCC, 1985a). The subdivisions of the Toreva Formation in the north half of Black Mesa are: (1) a basal unit which consists primarily of fine- to medium-grained quartz sandstone, some coal, carbonaceous shale and thinbedded siltstone; (2) a middle shale unit consisting of firmly-cemented siltstone and a few sandstone ledges; and (3) an upper unit which consists of very coarse to medium-grained poorly sorted sandstone. Formation thicknesses range from 141 to 325 feet (PWCC, 1985a). The Mancos Shale is fissile marine shale underlying the Toreva Formation and attains thicknesses between 500 and 1,000 ft in the Black Mesa area. Descriptions of the Mancos Shale in the area of the mine indicate a formation that consists predominately of silty mudstone with some bentonite and minor beds of very fine-grained sandstone. Geologic structure in the Black Mesa region consists of northwest-trending gentle folds and faults of small displacement. In the area of the Black Mesa Mine Complex, most folds are oriented north and most faults are oriented west. There is minor evidence of faulting on the surface with the throw of the major faults not exceeding 40 ft. There is little evidence of faulting and fracture zones on the exposed cuts and highwalls of the mined pits (PWCC 1985%and Willson, 2003).

2.2

Hydrogeology

Groundwater storage, recharge, movement and quality in the Black Mesa Mine area are partially to totally controlled by facies changes and stratigraphic position (stratigraphy); anticlines, synclines, monoclines,

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Hydrogeologic Setting

basins and upwarps (structure); downcutting of drainage systems (erosional stage); and the average amount of precipitation available for recharge (PWCC 1985a). The hydrogeology of the Wepo Formation in the area of the mining operations has been studied by PWCC through research done by others, the installation and hydraulic testing of wells, and monitoring of groundwater levels and water quality and surface-water hydrology features. Mine pits have also been examined to better understand the Wepo groundwater conditions. On the basis of wells installed strictly within the Wepo "Aquifer", the aquifer is considered of limited regional aquifer capability. The Wepo Aquifer is of poor water quality and most wells do not continuously yield usable amounts of groundwater. Sulfate in the Wepo wells monitored by PWCC ranges from 2 to 4,760 milligrams per liter ( m a ) , with a mean of 853 m a . Total dissolved solids (TDS) in the same monitored wells ranges from 320 to 8,0 10 m a , with a mean of 1,833 m a . Pumping rates during hydraulic testing in the Wepo wells averaged 11.7 gallons per minute (gpm). Groundwater potential in the Wepo Formation is low. The conglomeratic zones, where saturated, should yield some water to wells. Thicknesses range from 304 ft near Yale Point to 743 ft east of Cow Springs. The formation thins to the northeast (PWCC 1985a). The Mancos Shale is generally considered impermeable and hydraulically isolates the underlying Daquifer system from the overlying "Upper Cretaceous Aquifers" in the Mesaverde Group. Groundwater yields from the Toreva Formation in both sections of Black Mesa are dependent on the degree of lensing of the sandstone units with the shale, siltstone, and mudstone units as well as the grain sizes and degree of sorting of the sand grains. In the southern portion of Black Mesa, the better water yielding units are: (I) the upper part of the lower sandstone member which contains no mudstone; (2) sections of the middle carbonaceous member, which unlike most of the member contains almost all sandstone; and (3) the upper part of the upper sandstone member, which is very coarse-grained and conglomeratic. In the northern half of Black Mesa, the best water yielding units are the upper parts of the lower and upper sandstone subdivision, where the grain size is generally coarser and percentage of silt is less (PWCC 1985a). Groundwater in the Wepo and Toreva Formations is present under both water table and artesian conditions. Artesian conditions occur in the Wepo and Toreva Formations away from their outcrops.

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Unconfined conditions prevail along the perimeter of the Mesa. Groundwater is primarily obtained from sandstone units within the formations, especially where these sandstone beds are hydraulically connected. Due to the interbedding nature of the sandstone units with siltstone and mudstone beds, depths to groundwater can be variable from place to place. In places where sandstone units are underlain by coal, siltstone, or mudstone beds, perched water tables of limited storage and hydraulic connection exist. In several areas where the contact between the Toreva Formation and the impermeable Mancos Shale is exposed, groundwater discharges in the form of springs and provides an important source of domestic water (PWCC 1985a). Groundwater movement and well yields in the Wepo and Toreva Formations are in part controlled or limited by depths of erosion along Polacca and other principal washes on Black Mesa, which could act as groundwater sinks (PWCC 1985a). Groundwater is primarily obtained from the Toreva Formation and only secondarily fiom the Wepo Formation. Well yields range from 10-15 gpm. The groundwater is of marginal to unsuitable drinking water quality. Sulfate and total dissolved solids concentrations usually exceed the recommended drinking water limits, and the range of fluoride concentrations (0.1-2.1 parts per million [ppm]) exceeds the recommended limit of 1.8 ppm for fluoride in drinking water supplies in the Black Mesa area (PWCC 1985a).. The Quaternary-age alluvial deposits can locally provide significant amounts of groundwater in the region. Along some of the larger washes, deposits more than 200 ft thick exist from which water yields of from 10 to 1,000 gpm are obtained. Along the smaller washes, alluvial thicknesses range fiom 25-80 feet, and water yields are on the order of 10 to 50 gpm. In the northern part of Black Mesa, the alluvial veneer is very thin, and the well yields are small. During times of drought, many of these wells may be
dry (PWCC 1985a).

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3.0 REFUSE DISPOSAL SITE EVALUATION
This section discusses the evaluation of potential refuse disposal sites at Black Mesa Mine including the potential site candidates, the evaluation criteria and process, data compilation and findings, and concludes with a site-specific interpretation section that recommends a preferred site disposal area.

3I .

Potential Refuse Disposal Sites

PWCC originally specified that four potential refuse disposal areas be evaluated. These sites included Coal Resource Areas (CRAs) 57, N6, 527, and 53. CRAs 57 and N6 are existing pits and are still being mined, whereas 527 and 53 have been mined and are now reclaimed areas. During the site visit (September 8,2003), WWL was asked to also evaluate CRA N-11. However, PWCC subsequently determined that CRAs N-1 1 and 5-27 should not be considered for waste disposal and that one additional CRA, 5-23, should be included in the evaluation. CRA 5-23 is a proposed pit, and it will be several years (2008) before mining reaches bottom of coal in this area.

3.2

Evaluation Criteria

PWCC and WWL developed primary criteria for evaluating the suitability of using a CRA for disposing of coal-washing refuse. These criteria focused on the physical characteristics of the mine areas suited for long-term disposal of refuse. Long-term disposal scenarios are considered of potential greater hydrologic impact due to the potentially greater volume of transient drainage produced by the refuse materials. WWL did not evaluate mine areas on the basis of administrative or economical criteria such as proximity to the proposed coal wash facility. The primary evaluation criteria included: Depth to groundwater Potential for resaturation of regraded spoil Background geochemistry Available refuse storage space In addition, WWL used two screening criteria to initially rank the potential refuse disposal areas. These criteria included proximity to surface water features and the apparent configuration of the Wepo Aquifer potentiometric surface as presented on the potentiometric surface map (Drawing No. 85610).

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Refuse Disposal Site Evaluation

3.3

Evaluation Process

The evaluation of refuse disposal sites involved a cornpilatick of information acquired from (1) a site visit to the Black Mesa Mine and (2) the review of available and relevant hydrogeologic data. The purpose of the site visit to the Black Mesa Mine was to view the potential refuse disposal sites, discuss the mining history and hydrogeologic conditions of each site, and to acquire data needed to conduct the assessment. An important part of the site visit was to observe and examine the hydrogeologic conditions at each potential refuse disposal area including mine area topography, surface hydrology (seeps, springs, and streams), pit highwall characteristics (rock composition, fracture density, and seepage faces), and other physical attributes. The review of pertinent hydrogeologic data was of primary importance in assessing the refuse disposal sites. Data considered to potentially contribute to the assessment of the refuse sites included: Piezometric and potentiometric surface maps Well, borehole, and corehole logs (lithology) Well construction diagrams Well, borehole, corehole location maps Aquifer hydraulic test data Geologic map and formation descriptions Geologic structure mapldescriptions Geophysical data Geotechnical data Mine maps of potential refuse disposal areas Bottom of coal and projected bottom of pit footprints for potential refuse disposal areas Map showing surface hydrology features, and environmental monitoring sites (streams, ponds, and springs) The information obtained on the site visit and all written, electronic, or verbally communicated information was reviewed. Some data were reduced to expedite data review and interpretation. Generally, the data were reviewed on an individual mine area basis using the established criteria. Table 3.1 presents the data provided to support evaluation of the potential disposal areas.

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Refuse Disposal Site Evaluation

3.4

Site Visit

WWL visited the Black Mesa Mine on September 8, 2003. The purpose of the visit was to visually ' inspect the potential disposal sites to receive coal-wash refuse materials. In addition, WWL interviewed and discussed with PWCC employees the availability of data required to fully evaluate the suitability of the potential refuse disposal sites. During the site visit WWL (Mr. Bruce Smith) toured the potential refuse disposal sites in CRAs J-7,J-27, 5-3, N-6, and N-1 1. CRAs J-27 and J-3 have been mined out and reclaimed. CRAs 5-7, N-6, and N-11 are actively being mined. CRA J-23 was not visited as it is not currently under development. A close inspection of the exposed Wepo Formation on the pit faces was not permissible because of mine safety protocols. Pit faces and the existing pit bottoms were observed from a distance of at least 300 ft. PWCC scientists and engineers were interviewed concerning hydrogeologic information of the Wepo Formation within the CRAs, both as observed on pit highwalls and from borehole data. In addition, inquiries were made about rock fracture density and other geologic structures including jointing, fracture zones, faults, seepage or inflows within the mine pits, and if any exposed zones of the Wepo Formation show tendencies to seep groundwater. The Mine Geologist at the BMMC stated that neither the pit exposure of the Wepo Formation or borehole lithology revealed notable zones of increased fracture density, but that the study of fracture density has not been necessary to support normal mining operations. The geologist indicated that there were fairly uniform fractures throughout the Wepo Formation and that there were no characteristic zones of seepage from the Wepo Formation in most of the CRAs being considered for potential refuse disposal. However, he further indicated that local perched groundwater zones were occasionally intercepted during drilling of boreholes. The average spacing for drilling exploration boreholes is approximately 330 ft, with a 100- to 150-ft spacing used in outcrop areas and a 660-ft spacing used for corehole drilling. The geologist said there was little water intercepted at most of the drilling locations (Willson 2003).

3.5

Data Compilation and Findings

Assessment findings relative to each of the evaluation criteria listed in Section 3.2 of this report are discussed separately below.

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Refuse Disposal Site Evaluation

3.5.1

Depth to Groundwater

In 1985, PWCC prepared a potentiometric surface map (Drawing No. 85610) using groundwater levels recorded for monitoring wells completed within the Wepo Formation and located throughout the Black Mesa Mine Complex area. In addition, a preliminary map (PWCC 2003?) of potentiometric water levels in 2003 has recently been developed by PWCC. An assessment of historic and recent water level data from the Wepo wells indicates that the general potentiometric surface configuration has not significantly changed since the initial map was prepared in 1985. Mean water-level elevations for the period of record from 1980 to the present, are generally within 5 ft above or below the elevations used to create the 1985 map, and the regional flow direction and gradients have generally remained consistent over time. However, it is possible that local groundwater flow directions and hydraulic gradients have changed near some of the pits that have been mined since the potentiometric surface map was prepared in 1985. Of the local evident changes in the potentiometric surface since 1985, the decrease in water levels in Wepo Well 53 is of particular importance for this study because of the well's proximity to CRA N-6 (N-6 Pit). The 2003 draft potentiometric surface map indicates a depressed water level in the N-6 Pit vicinity as a result of the decreased water level in Well 53. The 2003 map would suggest that the potentiometric surface may exceed the final pit bottom topography by 5 to 10 feet, whereas, the 1985 potentiometric surface may exceed the final pit bottom topography by as much as 15 to 25 feet. Assuming that the noted decreases in the Wepo potentiometric surface are mostly caused by mining operations (pit excavations), it is logical to further assume that the potentiometric surface will recover after the pit areas are reclaimed. Therefore, the 1985 potentiometric surface (Drawing 85610) and well data proximal to the potential refuse disposal sites were used to assess potential elevation of re-saturation for post-mining scenarios.
A comparison of the 1985 potentiometric surface and the anticipated bottom of pit or coal topography

indicates that southern portion of the final pit footprint for CRA N-6 and the western portion of the final footprint for CRA J-7 will lie as much as 25 ft and 45 ft below the potentiometric surface, respectively. The pit bottom for the 5-23 area will lie at least 150 feet above the potentiometric surface. The bottom of coal surface for the mined and reclaimed 5-3 area ranges fiom 20 ft below to 100 ft above the potentiometric surface. The area below the potentiometric surface in the 5-3 area is limited to a small depression in the northwest portion of the mined area. An examination of the configuration of the potentiometric surface over the Black Mesa Mine Complex indicates a surface that generally mimics surface topography on a less precise scale. Generally, all mining areas with the exception of 5-3 fall in areas of singular flow direction and gradient. Area J-3 is situated on

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a hydraulic divide, where flow lines in the Wepo Aquifer diverge to Moenkopi Wash to the east southeast and Coal Mine Wash to the west. The attitude of the Wepo Aquifer potentiometric surface in the 5-23 area is relatively flat, compared to other mine areas, with a uniform westerly hydraulic gradient of 0.008 to 0.013 Wft. The potentiometric surface also indicates that the Wepo Aquifer intercepts and discharges to certain areas of Moenkopi Wash and Coal Mine Wash.

3.5.2

Potential for Re-Saturation of Spoils

A review of pit inflow calculations and well and borehole logs was conducted to support evaluation of the

potential for re-saturation of spoil.

3.5.2.1

Pit Inflows

Chapter 18 (Probable Hydrologic Consequences) in the MRP (1985a) presents pit inflow calculations for several of the CRAs, most of which have been reclaimed or are currently being mined. As mining operations progress, similar pit inflow calculations are prepared for new CRAs. These calculations generally predict pit inflows ranging from several thousands of gallons to over 10 million gallons per year for the various pits. The total inflows for the 5-1/N-6 Pit were projected to range from approximately 50,000 gallons in 1972 to 3,182,179 gallons in 2003. As mining has progressed over the last several decades, it has generally been observed that pit inflows were overestimated, and in some cases no inflow has occurred at all. For example, initial mining of the southern portion of the N-6 Pit saw enough pit inflow to require pumping, but subsequent mining of this pit to the north has not resulted in any observed pit inflows. As another example, the 5-7 Pit has not shown any significant inflows and no seepage face is present on the highwalls or bottom of the pit (Cochran 2003).

3.5.2.2

Well and Borehole Logs

Wepo well and exploration borehole logs were examined for wells and boreholes located within or near the potential refuse disposal areas. A summary of borehole information is presented in Appendix A.

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Refuse Disposal Site Evaluation

An examination of the lithologic logs for wells constructed in the Wepo Formation do not indicate extensive zones of wet conditions or that water was seeping into the borehole during drilling operations. Personal communication with PWCC personnel at the Black Mesa Mine confirmed that during drilling, very few of the boreholes yielded water, yet when allowed to sit for a period of time, some boreholes gradually yielded water and were completed as wells. Wells were apparently screened either across the stratigraphic intervals considered most favorable for yielding groundwater or on the basis of the observed depth to water in the borehole. Multiple screened intervals were installed in some wells; however, the multiple intervals were not isolated from one another with a grout seal. Static groundwater levels within the wells are typically located well above the screened intervals, supporting the concept of confined conditions in the Wepo Aquifer (this applies to wells that been constructed with hydraulic seals above the upper-most screened interval). Of the corehole data available, four logs were available for the J-23 area, three logs were available for the 5-7 area, and 16 logs were available for the N-6 area. Some of the borehole summaries indicate isolated intervals of lost circulation, lost core, and damp or wet conditions. However, wet conditions were not reported in the corehole logs from the 5-7 and J-23 areas. As a group, the N-6 area corehole logs indicated the presence of isolated wet or damp conditions over the entire length of each corehole, typically extending from 18 ft to 228 ft.

3.5.2.3

Wepo Well Water Levels

To further evaluate the potential for re-saturation of spoils, an examination of Wepo well water levels in wells in the vicinity of the potential refuse disposal mine areas was conducted to assess the sensitivity of the Wepo Aquifer potentiometric surface to hydrologic stresses. Water level elevations for 14 Wepo wells (Wells 40, 43 through 48, 53, 58 through 61, 65, 86, and 90), were plotted over time (Appendix B). The period of record was generally from 1986 to 2003. An examination of the water level fluctuations over time did not indicate a regional trend in water levels that might support more long-term climatic influences. This observation supports the confined nature of the Wepo Aquifer. However, some wells have shown distinct increasing or decreasing trends in water level elevations. For example, Well 44 exhibited steady water levels (with the exception of seasonal fluctuations) until 1992 when water level elevations began to increase; water levels have increased a total of 10 ft to the present date. Well 43 showed relatively steady levels until 1988, after which levels dropped 5 ft by 1991, leveled off until 1993 and then increased lfl through 1997. The cause of the water

3-6

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Refuse Disposal Site Evaluation

level fluctuations in the Wepo wells is uncertain without a detailed analysis of well installation procedures and assessment of potential impacts caused by mining activities proximal to each well. PWCC (1985) stated that a primary factor influencing Wepo well water levels is pumping during sampling and hydraulic testing. Some wells are slow to recover after drawdown from pumping events. The data also suggest that mining activities (Well 53) and surface water discharge (Wells 60 and 61) may have an influence on local water levels in the Wepo Aquifer. Section 3.5.1 discusses water levels in Well 53 and the potential relationship to mining activities.

3.5.2.4

Hydraulic Testing Data

Data provided by PWCC indicated that 23 Wepo wells were tested for hydraulic parameters using pumping tests and modified slug tests. A summary of these data is presented in Table 3.2. The arithmetic average of transmissivity values for the Wepo wells is 116.6 gallons per day per foot (gpdft); the geometric mean is 36.24 gpdlft. Two pumping tests resulted in estimates of the storage coefficient with an average of 8.2 x 1 0 ~indicating confined conditions. , The hydraulic conductivity of the Wepo Aquifer has not been directly measured, and because the confining strata in the Wepo Aquifer have not been clearly delineated, estimates of the hydraulic conductivity are problematic. PWCC (1985) reports that Cooley and others (1969) measured the permeability of sandstone rock cores from the Wepo Formation, the results of which ranged from 0.0009 to 0.02 gpdlft2(0.003 Wday). Alternatively, an average hydraulic conductivity value estimated on the basis of the screened interval in the hydraulically-tested Wepo wells is 0.1 1 Wday which is similar to an estimate initially used for approximating groundwater flow for a tracer test conducted at Pond BM-A1 (WWL 2002). The data do not show strong trends with respect to other well parameters. However, a plot of the transmissivity data does suggest a weak inverse correlation with respect to depth to water or water level elevation (Figure 3.1). That is, the smaller the depth to water, the greater the transmissivity value. This relationship can be attributed to greater weathering and fracture density in the shallow portion of the formation.

3.5.3

Background Geochemistry

Ambient geochemical conditions of groundwater within the Wepo Aquifer was assessed on the basis of analytical results reported for samples collected from Wepo monitoring wells located in the vicinity of each CRA. The analytical results were obtained from the PWCC database, which contains monitoring

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results for samples collected from a network of 36 wells over a monitoring period extending from 1986 through 2002. The monitoring wells evaluated for the various mining areas are as follows:

Mine Area
Wells

5-3 ~ ~ ~ WEPO86 WEP090

0

4

5-7 WEP047 5 WEP047R WEP060

5-23 WEP065 WEP066 WEP067

N-6 WEP040 WEP043 WEP053

Background geochemistry was evaluated by computing summary statistics for the metals and inorganic concentrations reported in the PWCC database for samples collected from local-area Wepo wells in the vicinity of each mining area and for lease-wide Wepo wells. Summary statistics for metals concentrations are presented in Table 3.3, and summary statistics for inorganic concentrations are presented in Table 3.4. Examination of Table 3.3 shows that the mean concentrations of metals in groundwater are generally consistent among the four mining areas and the lease-wide well network. Of the analytes shown, the mean concentrations of magnesium and selenium are higher for the lease-wide well than for the local-area wells. The wells comprising the 5-7 well network generally exhibit the best water quality, containing lower metals concentrations and lower frequencies of detection for several of the analytes than the other local area wells. The wells comprising the 5-3 and 5-23 well networks exhibit the lowest water quality, containing higher metals concentrations for several of the analytes than the other local-area wells. Concentrations exceeding the detection limit occur most frequently in wells comprising the 5-23 well network. Table 3.4 presents summary statistics for inorganic concentrations reported in the PWCC database for the local-area and lease-wide wells. The table shows that the mean concentrations among the local-area and leasewide wells are generally consistent with only minor variations between the groups. The most notable exception is that the mean concentration of nitrate-nitrite in the lease-wide wells is higher than in the local area wells. Of the local area wells, the wells comprising the 5-3 well network contain the highest mean concentrations, while the wells comprising the 5-7 well network contain the lowest mean concentrations. The mean pH values for the lease-wide and local area wells range from 7.7 in the 5-23 wells to 8.3 in the 5-7 wells.

3.5.4

Disposal Area Storage

The estimated storage volume for each potential disposal area was provided by the PWCC engineering department at Black Mesa Mine. The estimated final pit volumes for waste storage are as follows:
3=8
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Refuse Disposal Site Evaluation

0

CRA 5-3: 3,500,000 cubic yards (existing area available for waste) CRA 5-7: 1,777,500 (pit volume) CRA N-6: 9,160,000 (pit volume) CRA 5-23: Not yet available

The final 5-23 Pit will be approximately 9500 feet long and 135 feet wide. Overburden and interburden displaced by stripping equipment each year will be approximately 16,000,000 cubic yards with approximately 2 114 cuts (sequences) per year. Annually, approximately 5,000,000 cubic yards of coal will be removed from the 5-23 Pit. During the life of mining in the 5-23 CRA, several locations near the progressing pit configuration could be used for disposing of refuse that will not interfere with the production-related operations of the pit. It will not be difficult to deposit the estimated 1,000,000 cubic yards of waste per year on the pit bottom and or between spoil peaks. However, J-23 will not be available for waste disposal for about 2-3 years after start-up of coal-washing operations and subsequent production of waste.

3.6

Site-Specific Interpretation

The information obtained and compiled during the site visit and upon review of hydrogeological data provided by PWCC indicates that the variable hydrogeology of the Wepo Aquifer complicates the task of selecting a potential refuse disposal area in the designated CRAs. Of the criteria examined, depth to groundwater and the potential for resaturation are of most importance with regard to hydrologic impact. It is apparent that, on the basis of observations at the mine, pit inflows do not always occur when mined pits penetrate below the potentiometric surface. It is postulated that the most probable causes for the lack of inflow include (1) pit bottoms did not penetrate the confining layer(s) in the Wepo Aquifer, (2) evaporation rates exceed discharge rates (Darcy flux) at the seepage face, and (3) the existence of discontinuous or variable saturation within the Wepo Aquifer (isolated perched zones). The latter point emphasizes the uncertainty associated with the interpreted potentiometric surface. Groundwater inflows would not be expected at pits that have been extended below the potentiometric surface but have not penetrated the confining strata. In addition, water levels in wells adjacent to such pits would not be impacted (e.g., show drawdown) as a result of pit operations. The presence of confining strata has been assumed to exist at the mine site but has not been explicitly delineated. The relatively thin beds of shale, sandstone, and coal and their repetitious interbedded nature complicate the delineation of a

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discrete and single confining zone in the Wepo Aquifer. On the basis of static water levels, screened intervals, and anticipated pit bottom elevations, the possibility for a confining zone exists between the top of the screened intervals in Wepo wells nearest to Pits N-6 and 5-7 and the bottom elevations of the pits. Conversely, pits that have penetrated the confining strata would be expected to yield groundwater from the base of the pit and from the portion of the highwalls that extend below the confining strata. In this case, the inflow rate would be dependent on the aquifer hydraulic properties. Strata with low hydraulic conductivity may yield groundwater so slowly that evaporation rates prevent significant accumulation of water in the pits. It is also probable that the heterogeneous nature of the Wepo Aquifer accounts for inconsistent predictions of pit inflows. Groundwater in the Wepo Aquifer probably occurs in discontinuous lenses with limited amount of storage. In such cases, flow into pits that have penetrated confining strata may occur only in local perched zones and not uniformly throughout a particular zone or horizon. Any or all of the above situations may exist within the mining areas at the Black Mesa Mining Complex. Additional site-specific studies would be needed to fully assess the mechanisms controlling groundwater flow in and around the mining areas in the Wepo Formation.

3.6.1

5-23Mine Area

The 5-23 CRA is considered the most favorable CRA for refuse disposal because (1) the projected bottom of the coal layer is at least 150 ft above the potentiometric surface of the Wepo Aquifer, (2) the potential for resaturation of the waste from groundwater inflow from the Wepo Aquifer is minimal, (3) groundwater quality in the local area is generally consistent with the lease-wide area, and (4) the area available for storage is projected to be sufficient for the refuse material. The Wepo potentiometric surface in the mine area forms a broad uniform flow area (no convergent or divergent flow lines). On the basis of the Drawing No. 856 10, the potentiometric surface across the mine area has a hydraulic gradient of 0.013. The hydraulic gradient calculated from mean water levels (95 to 594 observations per well) for Wells 65, 66, and 67, is 0.008. In addition, the mine area is not located near any large surface drainage features. Although the 5-23 CRA is a new mine area, and the hydrogeologic conditions of the pit can not be observed first hand, the available corehole data from the area do not indicate that perched groundwater conditions exist in the area. Based on the corehole log information and observations at other mined areas,

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the probability of resaturation of spoils due to seepage from perched groundwater conditions is considered to be low.

362 ..

N-6 and 5-7 Mine Areas

The N-6 and 5-7 CRAs were not considered the most suitable locations for long-term refuse disposal for similar reasons. The primary disadvantages for disposal in these areas are that final pit bottom elevations are below the interpreted potentiometric surface of the Wepo Aquifer and that both CRAs are in close proximity to surface drainages and associated alluvial aquifers. The N-6 CRA is not the preferred long-term refuse disposal site on the basis of the screening criteria because the Wepo Aquifer potentiometric surface ranges from 14 ft (north end) to 25 ft (south end) above the bottom of the final pit elevations. The minimum water level elevations in Wells 40 and 53 are 32.9 ft and 91 ft above the bottom of pit elevations for the north and south ends of the pit, respectively. In addition, the final pit has a moderately steep hydraulic gradient of 0.021 in the middle area of the pit and a hydraulic gradient of 0.038 in the northern portion of the pit. The potentiometric surface indicates that Wepo groundwater in the vicinity of the pit may ultimately discharge to Coal Mine Wash, which is located only 400 fi north of the north end of the pit. The J-7 Mine Area is similar to the N-6 Mine Area with respect to its suitability for refuse disposal. The anticipated final 5-7 Pit bottom will range from approximately 12 ft above (east end) to 45 ft below (west end) the Wepo Aquifer potentiometric surface. The minimum water level elevation in the nearest Wepo Aquifer well, Well 48 (now abandoned), is 43 feet above the lowest anticipated pit bottom. The hydraulic gradient in the area of the 5-7 Pit is 0.017 with flow to the west and southwest toward Yucca Flat Wash. The potentiometric surface shown in Drawing No. 85610 indicates a convergence of Wepo Aquifer flow lines at Yucca Flat Wash suggesting the wash provides a discharge point for the aquifer. The convergence of the flow lines becomes more significant approximately 0.5 miles downstream of the 5-7 Pit. Although the elevation of the potentiometric surface higher than the projected bottoms of the N-6 and 5-7 Pits, no significant inflows have been observed at either pit to date. There are several possible explanations for the lack of substantive evidence supporting projected pit inflows. First, while the pit bottoms extend below the potentiometric surface, the pit excavations may not have fully penetrated the confining strata, and therefore, the pits have not intercepted the saturated strata with hydraulic head

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expressed by the mapped potentiometric surface. Alternatively, the pits may have in fact penetrated some or all of the confining strata, but groundwater flows from the saturated zones so slowly that evaporation along the pit margins limits surface expressions of the flow. Thirdly, saturated intervals comprising the Wepo Aquifer can be discontinuous and the pits may be located in areas that are not hydraulically connected to localized saturated intervals. Regardless of the reason for the lack of observed seepage into the pits, the available site hydrologic data indicate that the potential exists for groundwater to flow into pits. The deepest elevation of the 5-7 Pit will be approximately 6,240 ft and the stream channel of Yucca Flat Wash, which lies 500 fi to the south, is approximately 6,300 R The relatively short distance from the alluvial aquifer in Yucca Flat Wash to the J-7 Pit increases the risk for migration of alluvial groundwater associated with the drainage to intercept the pit, and conversely, for fluids generated in the pit to migrate to the alluvial aquifer, potentially discharging along the drainage. Metals and inorganic concentrations in monitoring wells near the N-6 and 5-7 Pits are generally consistent with the overall concentrations reported for the Wepo Aquifer. However, metals concentrations in samples collected from J-7 wells are typically lower than those reported for samples from the other localarea and the lease-wide well network, implying that Wepo Aquifer water quality with respect to metals in the 5-7 CRA is slightly better than elsewhere within the lease area at the site with respect to metals. The storage volume available at each pit is likely to be sufficient for refuse disposal. The final N-6 Pit storage volume will be approximately 9,160,000 cubic yards (based on uncompacted refuse). The potential storage volume of the 5-7 Pit is 1,777,500 cubic yards. On the basis of the potentiometric surface, the potential exists for the portion of the J-7 Pit that lies west of approximately the 30,000 easting coordinate to become saturated with groundwater inflow. Therefore, the storage volume available in the portion of the pit that is expected to remain dry (east of approximately the 30,000 easting coordinate) would be less than 1,777,500 cubic yards.

363 ..

5-3Mine Area

The 5-3 CRA was mined in the 1970's and 1980's and has since been reclaimed (recontoured and revegetated). An examination of the former pit bottom with respect to the Wepo Aquifer potentiometric surface (Drawing No. 85610) indicates that the former bottom of pit ranges from 20 ft below to 125 ft

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Refuse Disposal Site Evaluation

above the potentiometric surface. However, the pit bottom area below the potentiometric surface is restricted to a relatively small depression along the north boundary of the pit. Three Wepo wells are located in the 5-3 CRA. Water levels in Wepo Wells 86 and 90, located just north of the northern former pit boundary, indicate an increase in water levels of approximately 10 and 5 ft, respectively, since the beginning of the monitoring period in 1986. Water levels in these wells have been relatively stable since 1993. The mean water level elevations for Wells 86 and 90 are 6,500 ft and 6,503 ft above mean sea level (amsl), respectively, and indicate that the distance between the bottom of pit and the potentiometric surface shown by Drawing. No. 85610 may actually be approximately 10 feet less than indicated. Wepo Well 45 is located near the center of the 5-3 reclaimed CRA. The mean water level elevation of Well 45 for the period of record (1986 to present) is 6,438.7 ft. Similar to Wells 86 and 90, Well 45 showed initial increase in water levels of approximately 4 ft and has been relatively stable since 1996. The mean water level elevation also indicates that local water levels have increased 5 to 10 ft compared to levels indicated by the potentiometric surface shown on Drawing 85610. The hydraulic gradient across the J-3 reclaimed CRA is 0.018 along the pronounced hydraulic divide that is formed by the Wepo Aquifer potentiometric surface. This divide is indicative of a potential recharge area, with diverging flow paths to the west-southwest to Coal Mine Wash and to the east-southeast to Moenkopi Wash. The distances to Coal Mine Wash and Moenkopi Wash from the hydraulic divide near the center of the reclaimed CRA are approximately 7,000 A and 8,000 ft, respectively. Distances to prominent tributaries to these washes are 3,400 ft and 4,800 ft respectively. The indicated (Drawing No. 85610) hydraulic gradient between the hydraulic divide to the north-trending tributary is 0.03. There are no corehole data readily available for the 5-3 reclaimed CRA, nor are there data that refer to pit inflow observations or the geotechnical, geochemical, or hydraulic properties of the spoil material used during reclamation to backfill the 5-3 Pit. Based on the interpreted hydrologic setting in the vicinity of the 5-3 reclaimed CRA, the potential for resaturation of the refuse material would be minimal since the base of the pit largely lies above the projected potentiometric surface of the Wepo Aquifer. However, the data indicate that the long-term potential exists for any constituents leaching from the refuse to flow along divergent flow paths and possibly discharge along primary drainage features in the area.

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Refuse Disposal Site Evaluation

Metals and inorganic concentrations reported for samples collected from Wepo wells in the vicinity of the J-3 Mine Area are generally consistent with the concentrations reported for samples collected from other local-area wells and the leasewide well network. However, the J-3 wells do tend to contain slightly higher mean concentrations of alkalinity, carbonate, bicarbonate, chloride, and fluoride in comparison to other local-area and lease-wide wells. The slightly elevated concentrations for these analytes in the J-3 wells do not impact the selection criterion regarding background geochemistry. The storage area available for refuse disposal in the 5-3 Mine Area is considered to be adequate. It is estimated that storage area available at 5-3 is approximately 3,500,000 cubic yards. Disposal of refuse at the 5-3 reclaimed CRA would occur directly on the already reclaimed surface, and would focus on the filling of existing surface depressions. The 5-3 reclaimed CRA is not recommended as a disposal area primarily due to its location on a hydraulic divide in the Wepo Aquifer as indicated in Drawing No. 85610. Although disposal of wash plant refuse would occur on the existing reclaimed surface, above the Wepo potentiometric surface, long-term potential migration of leachate from the site may involve multidirectional flow toward the primary surface-water drainages of Coal Mine Wash and Moenkopi Wash under relatively moderate to steep hydraulic gradients. In addition, disposal of refuse in the 5-3 reclaimed CRA may involve further excavation work, such as top soil removal, to prepare the surface prior to refuse disposal; and additional revegetation efforts would be required in an area that has already been successfully reclaimed.

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4.0 HYDROGEOLOGIC IMPACT ANALYSIS
In accordance with regulations promulgated in the Surface Mining Control and Reclamation Act (SMCRA) of 1977, PWCC is required to assess the probable hydrologic consequences of the mining operations. The disposal of wash-plant refuse materials presents a potential impact to the overall hydrologic balance within and adjacent to the lease area of the Black Mesa Mining Complex, and must therefore be evaluated. The evaluation of potential impacts to the hydrologic balance focuses on two primary components: (1) groundwater and surface water quantity (alterations to the existing flow conditions), and (2) groundwater and surface water quality degradation.

4.1

Summary of Regulations

Hydrologic impact assessment involves an evaluation of applicable performance standards as described in 30 Code of Federal Regulations (CFR) Part 816 as they related to protection of the hydrologic balance and disposal of coal mine waste. These regulations state that surface mining and reclamation operations are to minimize disturbance of the hydrologic balance within the permit and adjacent areas, to prevent material damage to the hydrologic balance outside the permit area, to assure protection or replacement of water rights, and to support approved post-mining land uses in accordance with conditions of the permit and regulation performance standards. Potential changes to the hydrologic balance include groundwater and surface water impacts. Applicable groundwater impacts include the potential for significant acid, toxic, or other pollutant infiltration to groundwater, and the change in potential use of groundwater. Applicable surface water impacts include the potential for significant acid, toxic, or other pollutant drainage to surface water, and the potential to affect surface water quality and flow rates.

4.2

Refuse Disposal Conceptual Model

The conceptual model of wash-plant refuse disposal at the Black Mesa Mine centers on the disposal of wash-plant refuse in a previously mined area. As discussed in Section 3.6.1, the 5-23 CRA was selected as the optimal CRA for refuse disposal that would most-likely result in minimal hydrologic impact to the hydrologic balance within the lease area. However, the 5-23 CRA is a proposed pit, and is yet to be developed. It is anticipated that wash-plant refuse will be produced for a period of 2 to 3 years before the 5-23 CRA will be available to receive the waste materials. Therefore, to accommodate wash-plant refuse disposal during the 2 to 3 year beginning period for the wash plant operations, PWCC plans to dispose of the wash plant refuse in the N-6 Pit.

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4.2.1

N-6 Pit

As discussed in Section 3.6.2, the bottom elevations of the final N-6 Pit will be as much as 25 f below t the Wepo Aquifer potentiometric surface (Drawing No. 85610). However, current observations do not indicate seepage (pit inflows) into the N-6 Pit in areas below the potentiometric surface. The fact that groundwater inflow has not been observed at the N-6 Pit suggests a hydrogeologic conceptual model that isolates this region of the Wepo Formation as unsaturated or at least not fully saturated. The unsaturated regions may exist because underlying confining strata were not penetrated during mining, or because of a number of other reasons including low hydraulic conductivity or high evaporation rates all of which are related to strata heterogeneity. The possibility of a discontinuous Wepo Aquifer has been suggested by PWCC (1 985). Alternatively, a conservative analysis will consider a worse-case scenario in which any wash-plant materials deposited in the N-6 Pit are resaturated due to pit inflows, meteoric precipitation, or transient drainage from the refuse. The post-mining configuration of the N-6 Pit is estimated to be a long, north-trending open pit with side walls sloping away from an undulating floor at the angle of repose (approximately 38'). Figure 4.1 shows a plan view of the estimated final N-6 Pit. Disposal of wash-plant refuse in the N-6 Pit will occur on the pit bottom and the spoil slopes. Figure 4.2 shows a schematic profile of the pit with refuse disposal material. In a three-year period, approximately 3,000,000 yds3 or 32% of the final N-6 Pit volume will be filled with wash-plant refuse. To minimize the amount of wash-plant refuse that is potentially resaturated, the pit filling will be confined to a restricted area of the pit. Other spoil material will be placed around the wash-plant refuse to meet final reclamation grading plans. The wash-plant refuse materials are expected to contain approximately 40% surface moisture content. Some of this moisture may be lost by evaporation or drainage during the handling process prior to disposal. As a conservative measure, it is assumed that the refuse will have 40% moisture content after placement in the disposal area. Although annual evaporation rates are high (approximately 45 inches) and annual precipitation is low (approximately 6.8 inches) at the Black Mesa Mining Complex, this conservative approach may also account for moisture gained by precipitation on the refuse materials (Cochran 2003).

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Hydrogeologic Impact Analysis

Issues of primary importance in evaluating the hydrologic impact of refuse disposal are the volume and quality of transient drainage water from the wash-plant refuse and the long-term impact to groundwater quality due to the potential re-saturation of the refuse from pit inflow groundwater.

4.2.2

J-23 Pit

The interpreted potentiometric surface of the Wepo Aquifer in the 5-23 CRA is relatively uniform, with flow to the west at a hydraulic gradient of approximately 0.013. An evaluation of this surface and the estimated bottom of coal pit topography shows that the final bottom elevations of the 5-23 CRA will be at least 150 feet above the Wepo potentiometric surface (Figure 4.3). Because of the complicated nature of groundwater in the Wepo Formation (discussed in Section 3.6), the physical location of the top of the confined aquifer or confining zone is not known. In reality groundwater in the Wepo Formation may originate from a complex combination of perched unconfined and confined zones as well as a more widespread confined aquifer at depth. Long-term disposal of refuse in the 5-23 Pit will result in several hydraulic and solute transport processes that may impact the local hydrology. These processes include (1) transient drainage of inherent water content after refuse placement, (2) potential unsaturated flow and transport (percolation) of drainage water and solutes into the underlying unsaturated Wepo Formation, and (3) saturated flow and solute transport in the Wepo Aquifer in the case that percolating drainage intercepts the Wepo Aquifer. Conceptually, the processes of transient drainage of the refuse pore water will likely occur; however, the process and impact of unsaturated flow into the Wepo Formation, and the more remote occurrence of transient drainage reaching a ubiquitous Wepo Aquifer zone appears less probable. The latter flow and transport processes seem less likely to cause impact because of the questionable nature of the Wepo Aquifer, and the apparent low hydraulic conductivity of the interbedded shales, sandstones, and coal beds of the Wepo Formation. Furthermore, if a distinct stratum or even a complex series of confining strata exist above the Wepo Aquifer, these strata are expected to impede vertical flow from above elevations.

4.3

Technical Approach

The technical approach used to assess the potential hydrologic impact of wash-plant refuse disposal in the N-6 and 5-23 Pits, focuses on the following tasks: Water Quality - Comparison of ambient water quality of groundwater to the potential chemical composition of refuse leachate water.

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Hydroloqic Impact Analysis

Refuse Leachate Fate and Transport - Evaluation of the potential quantity and migration of refuse leachate from the refuse disposal area. The first task of comparing the water quality of ambient Wepo Aquifer and estimated refuse water was conducted by an in-depth data compilation, reduction, and statistical analysis. The second task, refuse ieachate fate and transport, was evaluated by the use of analytical and numerical flow and transport models.

4.3.1

Water Quality

To address the potential chemical contamination of groundwater coming in contact with the wash-plant refuse, the assessment approach consisted of data collection, compilation and reduction, followed by an interpretation task. The interpretation task involved comparing summary statistics of two data sets: (1) the ambient ground water quality data of the Wepo Aquifer and (2) the analytical results from the surrogate overburden and interburden materials. In addition, statistical tests were performed to further evaluate the different data sets.

4.3.1.1

Data Collection, Compilation, and Reduction

The data types needed to evaluate hydrologic impact(s) included groundwater chemistry data &om the Wepo Aquifer, analytical data from Synthetic Precipitation Leaching Procedure (SPLP) testing of interburden and overburden samples, total metals and wet chemistry analytical data, soil acidity and toxicity characterization analyses, and hydraulic parameter data for the Wepo Aquifer. PWCC conducted sampling and analysis of materials representative of overburden and interburden materials and coal-wash refuse. The overburden and interburden samples were considered "run-of-mine" coal that will probably become wash-plant refuse. Samples were collected from twenty-one select exploration core holes drilled in the following un-mined coal resource areas: J-2,J-4, 5-6, J-14, J-15,J-23, N-6/N-11, N-9, and N-10. Samples were "composited" by grabbing thin sections of non-coal (shales, mudstones, etc.) found within the thicker, mineable coal seams in each core, and a thin (0.3 foot thick) section of the Wepo formation immediately below each mineable coal seam. These 21 new cores were obtained during the summer of 2003 (see Drawing No. 85613, Overburden and Impact Core Location Map in PWCC 2003). The sampling and analysis effort was conducted as follows:

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Hydrogeologic Impact Analysis

A total of 23 composite samples, including 2 duplicates, were collected for SPLP metals analysis (aluminum, arsenic, barium, boron, cadmium, calcium, chromium, copper, iron, lead, magnesium, manganese, mercury, potassium, selenium, silver, sodium, vanadium and zinc) and SPLP inorganic analysis (alkalinity, bicarbonate, carbonate, hydroxide, chloride, fluoride, conductivity, total dissolved solids, and pH). The analyses were performed using EPA Method 1312 @PA, 2003). Six selected composite samples, including 1 duplicate, were collected for total metals (aluminum, arsenic, barium, boron, cadmium, calcium, chromium, copper, iron, lead, manganese, mercury, silver, vanadium and zinc) using Method 200.7, and wet chemistry analysis (chloride, nitrate [as N], nitrate and nitrite [as N], nitrite [as N], total phosphate, and sulfate) using EPA Methods 4500C1, 4500S04, 353.3 and 365.3 (mg/L on paste extractant), and total Kjeldahl nitrogen (mglkg, Method 35 1.3). Six composite samples, including lduplicate, were collected for soil characterization analyses including pH (saturated paste), electrical conductivity, percent moisture, calcium (meqk), magnesium (meqk), sodium (meqk), sodium adsorption ratio, percent sand, silt, and clay, soil class, total percent sulfur, percent pyritic sulfur, acid potential, neutralization potential, acid-base potential, pyritic acid potential, pyritic acid-base potential, total selenium, acid-base DTPA selenium, soluble selenium, and percent calcium carbonate. Three other composite samples were analyzed for a partial list of the parameters. A 20-drum bulk sample of raw coal was collected at the mine and submitted to a pilot- scale coalwash testing facility. The wash testing was conducted to examine physical parameters associated with coal-wash process performance. Existing data and data specifically collected for the hydrologic impact assessment were compiled from electronic and hard copy media provided by PWCC. The data were input into electronic (~xcel@) spreadsheets, as necessary, to facilitate rapid data organization and reduction. A large portion of the existing information included Wepo Aquifer chemical analytical data, hydraulic testing analysis data, and water level data. In addition, existing mine maps of surface topography, the Wepo Aquifer potentiometric surface, mine areas, wells, environmental monitoring sites, bottom of coal elevations, and final pit footprints, were used throughout the assessment process.

4.3.1.2

Analysis and Interpretation

The interburden and overburden core samples were analyzed using EPA Method 1312 - SPLP (EPA 2003). The SPLP method is used to evaluate the composition of potential leachate Erom a solid waste material and is commonly used in the mining industry. The method involves the use of an extraction fluid that simulates the acidity of precipitation (rain, snow, etc.) that would fall on the waste. Precipitation is typically acidic due to air pollution impacts of heavy industrialization and coal utilization areas, In the western United States, the pH of the extraction fluid used is 5.0 (Alforque 2003). The waste to liquid

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Hydroloqic Impact Analysis

ratio is 1:20 by weight. The waste and fluid mixture is agitated for 18 2 hours and filtered with 0.6 to 0.8 pm glass filter before analysis. A mixture of sulfuric acid and nitric acid is used to prepare the extraction fluid. The analysis of sulfate and nitrate may therefore be affected. PWCC did not analyze for sulfate or nitrate in the SPLP extractant. Sulfate and nitrate were analyzed in the samples collected for soil characteristic parameters. The groundwater geochemical records for the Wepo Aquifer were obtained from the PWCC database. The database contains water-quality records for samples collected from a network of 36 wells over a monitoring period extending from 1986 through 2002. The SPLP analytical results from the core samples collected in the un-mined areas were used as surrogate analytical data for actual refuse material. The refuse samples were analyzed for SPLP metals and SPLP inorganics (Table 4. I), and paste extraction inorganics (Table 4.2). These analytical results were used to assess analyte levels in potential refuse leachate relative to ambient groundwater-quality conditions within the Wepo Aquifer. The analytes projected to be present at higher concentrations in the refuse leachate than in natural groundwater are considered more likely to contribute to potential degradation of ambient groundwater conditions. Conversely, the analytes projected to be present at lower concentrations in the refuse leachate than in natural groundwater are considered less likely to contribute to potential degradation of ambient groundwater conditions. A comparison of summary statistics for metals concentrations reported for refuse samples (SPLP) and groundwater samples collected from wells in the vicinity of CRA's 5-23 and N-6 (local-area wells) and wells comprising the lease-wide well network (lease-wide wells) is presented in Table 4.3. As shown, summary statistics were computed for the sample sets containing reported concentrations at or above the method detection limit. Of the 19 SPLP metals analyses performed on the refuse samples, the mean concentrations of seven metals exceeded the mean concentrations reported for the lease-wide and localarea samples. The seven metals with mean concentrations in the refuse samples greater than the mean concentrations in the lease-wide and local-area samples were aluminum, arsenic, barium, copper, mercury, vanadium, and zinc. For each of these metals, a Student's t-test was performed to assess the significance of the difference between the mean values. Except for copper, the test results indicate that there is a statistical difference between the mean concentrations at the 0.05 level of significance. For copper, there is no statistical difference between the mean concentrations of the refuse samples and the lease-wide samples at the 0.05 level of significance. There is a statistical difference between the mean concentrations of the refuse samples and the local-area samples at the 0.05 level of significance; however, it should be noted that the concentrations reported for these samples were at or near the method detection

+

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Hydrogeoloqic Impact Analysis

limit. Selenium was the only other analyte with a mean concentration in the refuse samples higher than the local-area wells but lower than the leasewide wells. Student's t-test results indicate that there is a statistical difference between the mean values of the refuse samples and the J-23 and N-6 samples at the 0.05 level of significance.

A comparison of summary statistics for inorganic concentrations in refuse samples (SPLP and paste
extraction) and groundwater samples collected from wells in the vicinity of CRAs 5-23 and N-6 (localarea wells) and wells comprising the leasewide well network (lease-wide wells) is presented in Table 4.4. Sulfate, nitrate, and nitratelnitrite are the only analytes with mean concentrations in the refuse samples that are higher than the mean concentrations for the site- wide andor local-area wells. The mean concentration of sulfate in the refuse sample is higher than the mean concentration in the leasewide wells and the local-area wells. T-test results for comparison of the means for sulfate indicate that there is no statistical difference between the means at the 0.05 level of significance. The mean concentrations of nitrate and nitratelnitrite in the refuse samples are higher than the mean concentration in the local-area wells at N-6 but lower than the mean concentrations in the leasewide and 5-23 wells. T-test results for comparison of the means for nitrate and nitratelnitrate indicate that there is a statistical difference between the means for both analytes at the 0.05 level of significance. The mean pH value for the refuse samples (8.6) was higher than the mean pH value for the lease-wide wells (7.9), 5-23 wells (7.7) and N-6 wells (8.0). Because the mean values of pH for the lease-wide and local-area wells are greater than 5.0 (the pH of the SPLP extraction fluid) it is expected that the metals concentrations reported for the refuse samples over-estimate the concentrations in leachate produced as a result of groundwater infiltrating the refuse material. Results of the geochemical assessment indicate that leachate produced as a result of acid rain infiltrating the refuse material likely contains higher concentrations of aluminum, arsenic, barium, mercury, selenium, vanadium, and zinc than does natural groundwater in the vicinity of the 5-23 and N-6 CRAs. In the absence of geochemical modeling, the levels anticipated in leachate produced as a result of groundwater infiltrating the refuse material cannot be accurately assessed; however, it is expected that metals concentrations in groundwater induced leachate would likely be less than those reported on the basis of the SPLP analyses. On the basis of the saturated paste extraction results, nitrate and nitratelnitrate concentrations are expected to be higher in the refuse material than in natural groundwater in the vicinity of the N-6 CRA. Similarly, nitrate and nitratelnitrite concentrations are expected to be less in the refbse material than in natural groundwater in the vicinity of the 5-23 CRA. Analyte concentrations

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Hydrologic Impact Analysis

in leachate derived from the refuse material are expected to be similar or less than the concentrations in natural groundwater for the other metals listed in Table 4.3 and inorganic constituents listed in Table 4.4.

Soil Characteristics Data

Soil characteristics data consists of soil analysis parameters that are used to access soil suitability for plant growth. The wash-plant refuse will not be used for shallow soils or substrate for revegetation efforts at the mine. The refuse will be disposed in previously mined areas and buried below the root zone with spoil and other non-toxic soils. However, a brief discussed of the soil characteristics is important for a comprehensive assessment of potential refuse composition. Soil characteristics analyses were conducted on selected interburden and overburden core samples collected in the summer of 2003. As previously noted, the interburden and overburden core samples are seen as surrogate media for the coal wash-plant refuse. Table 4.2 presents the soil characteristics results for the interburden and overburden core samples. The table also presents maximum threshold values and mine site mean values for some parameters at the mine. Table 4.2 indicates that the sodium adsorption ratio (SAR) and total selenium are slightly above the maximum threshold values in 3 and 4 of the 7 samples analyzed for these parameters, respectively. Sample 307-074-03R is a replicate sample of sample 307-074-03; the SAR values for both samples slightly exceeded the SAR threshold of 35 for samples containing between 20 and 35% clay. The 4 samples that exceeded the total selenium concentration threshold of 2.5 m a did not exceed 3.0 mg1L (sample 307-074-12 was reported at 3.050 mg/L). Because of the analytical method used, the total selenium concentrations presented in Table 4.2 are not considered representative of the selenium concentrations that would leach from the refuse materials. The SPLP results shown in Table 4.1 are considered more representative of potential leachate concentrations.

4.3.2

Refuse Leachate Fate

Conceptually, the disposal of refuse materials may result in changes in water quantity and water quality in local hydrologic systems should refuse leachate migrate to and mix with these systems. The potential migration of refuse leachate from the mine area can be segregated into 4 main components or processes:

(1) transient drainage of inherent moisture content after refuse placement, (2) saturated flow in the Wepo
Aquifer in the case that percolating drainage intercepts the Wepo Aquifer, (3) potential percolation of

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drainage water into the underlying unsaturated Wepo Formation, and (4) potential transport of solutes in the Wepo Aquifer.

4.3.2.1

Refuse Transient Drainage

The first flow process investigated was the transient drainage of water in the wash-plant refuse material. The purpose of the transient drainage analysis was to confirm that pore water within the refuse will drain by gravity and to obtain an estimate of the volume of drainage over a period of time. An evaluation of the volume of water generated by transient drainage is relevant to assessing the potential impact on local hydrologic conditions at the N-6 Pit and J-23 Pit. The volume of the refuse drainage was estimated using the H Y D R U S ~ D ~ numerical flow and transport program (IGWMC 1999). HYDRUS2D is designed for modeling variably saturated media. The HYDRUS2D simulations were configured to match the hypothetical geometry of each final pit area and assumed a conservative scenario of instantaneous deposition and a maximum refuse thickness of 70 ft (Lehn 2003). The simulation was constructed to simulate drainage and saturation of the bottom portion of the refuse material, i.e. no drainage was allowed from the bottom of the model domain but allowed to build-up and saturate the bottom of the refuse material. The model domain consisted of a twodimensional vertical section of a single material type, wash-plant refuse. All boundaries were set at noflow, as only gravity drainage and water generated were being evaluated. The initial condition moisture content for the refuse was set at 0.24 (24 %), the volumetric moisture content converted from expected mass content in Calculation No. 1 (Appendix C). HYDRUS2D requires the input of unsaturated hydraulic parameters unique to each material type being modeled for variably saturated flow and transport conditions. (HYDRUS2D input parameters are in metric units, therefore, where appropriate, discussion of the HYDRUS2D modeling will cite both English and metric units). The parameters used in the model simulations for the refuse material are as follows:

L Hydrus2D media type

-1 -7092 NA

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The parameters for the refuse material were estimated using ~osetta@, unsaturated parameter an estimation program (Schaap 2000). The program uses sieve analysis and bulk density data to estimate the unsaturated parameters (more accurate estimations would require additional laboratory analysis). The geotechnical data used for the refuse material were approximations from Hazen Research, Inc., the laboratory that conducted the pilot washing of the 20-drum sample of raw coal (Section 4.3.1.1). Hazen reported an approximate composition of the refuse of 47 % sand, 20% silt, and 33% fines (Reeves 2003).
A bulk density estimate of 1.6 grams/cubic centimeter was provided by PWCC (Cochran 2003).

N-6 Pit Refuse Drainage

Intuitively, the volume of water added to the N-6 Pit as a result of transient drainage from the refuse materials would be expected to have a negligible impact on the Wepo Aquifer as the local interpreted potentiometric surface appears depressed (2003 potentiometric surface) either as a result of mining activities or natural causes (local unsaturated conditions). Nonetheless, a HYDRUS2D simulation was conducted to confirm this hypothesis. As previously discussed, it is anticipated that the N-6 Pit will be used for refuse disposal for a period of 3 years, before the 5-23 Pit will be ready to receive the refuse. In a 3-year period, an estimated 3,000,000 yds3 will be deposited in the N-6 Pit. PWCC estimates that the maximum thickness of refuse will be 70 ft. In the case of the N-6 Pit, the final pit configuration is expected to be 5,600 ft long by 330 ft wide. Assuming a refuse deposit of maximum thickness, the 3-year refuse deposit configuration would be 70 ft high by 335 ft wide bye 3,454 ft long. This configuration will accommodate 3,000,000 yds3 of refuse material. A HYDRUS2D simulation was configured for the N-6 Pit geometry and performed to provide an estimate of the transient drainage volume from 3 years of refuse disposal. It is important to note the drainage volume outcome is expected to be sensitive to the configuration of the transient simulation domain. That is, a narrower, deeper instantaneous deposit of refuse would yield the same volume of water but would have a thicker saturated interval, and would also take longer to drain. Conversely, a shallower refuse deposit would yield relatively the same amount of water in less time. The result of the simulation showed that the volume of water that drains by gravity from the 3-year deposit of refuse material is of little consequence. The simulation indicated that gravity drainage of the deposit will not yield significant water at the bottom of the refuse for many years (Figure 4.4). In fact, the head build-up at the bottom of the refuse becomes relatively stable at 5.3 ft 11.6 meters (m)] after

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Hydrogeoloqic Impact Anatysis

approximately 560,000 days (1,534 years) of drainage (Figure 4.5). Water does not begin to build-up at the bottom of the refuse for over 100 years.

PWCC has estimated that 1,000,000 cubic yards of refuse'will be produced on an annual basis. Calculation No. 1 (Appendix C) indicates that approximately 24 % (by volume) of the refuse will be "surface" water, water held by tension to the refuse material. During actual mine operations, the refuse material will be deposited over a long time interval and in different locations.

J-23 Pit Refuse Drainaae

The 5-23 Pit will be actively mined for approximately 14 years. Transient drainage of water from the refuse will occur erratically depending on disposal location within the pit, climatic conditions, compaction, and other handling procedures of the wash-plant refuse. As mentioned in Section 3.5.4, the final pit configuration for the J-23 Pit will be approximately 9,500 fk long by 131 ft wide. The volume of the final pit configuration will hold only a few years production of wash-plant refuse. However, sufficient area will be available for refuse disposal during mining operations; refuse material will be disposed in selected areas of the pit as it advances toward the final pit configuration as space becomes available. The HYDRUS2D model for the 5-23 Pit was a vertical section 70 R (2 1 m) high and 131 ft (40 m) wide. The boundary and initial conditions were set the same as the N-6 Pit simulation. Similar to the N-6 Pit HYDRUS2D simulation, the results of the transient drainage simulation for the 5-23 Pit indicates an extraordinary amount of time is required to drain the refuse materials. Figure 4.6 shows the head build-up at the bottom of the refuse material (given an impermeable bottom boundary). The figure indicates that most of the water has drained from the refuse material within approximately 250,000 days (685 years). Calculation No. 1 (Appendix C) indicates that a volume of approximately 793,400 fk3 of water is drained from a 70 ft thick deposit of refuse in an annual production of 1,000,000 yds3in this period of time. The "drainage factor", the total volume of water drained divided by the total volume of refuse, is 3%. This drainage factor only applies to deposits 70 ft thick. The results show that only 12.2 % of the original water in the refuse material drained from the refuse and that this drainage occurred over a large period of time. Obviously, the transient drainage simulation indicates that drainage of refuse water within a time frame applicable to mine operations is not an issue. It is likely no fiee water will be

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Hydrologic impact Analysis

generated by the refuse before reclamation activities are implemented; Figure 4.7 indicates that measurable drainage will not occur for decades.

4.3.2.2

N-6 Pit Saturated Flow and Transport Analysis

Even though the transient drainage model simulations indicated very slow drainage of the refuse material in the pits, the long-term fate of the leachate solutes was thoroughly explored by evaluating the potential hydraulic pathways after gravity drainage. For the N-6 Pit, it was assumed that the worsecase scenario for leachate migration would be saturated flow and transport due to pit inflows within the Wepo (Javandel and others Formation. A two-dimensional flow and transport analytical model, TDAST@ 1987), was used to examine potential contaminant migration from the N-6 Pit. The program assumes saturated, isotropic conditions and uses the convection-dispersion equation to predict solute transport due to groundwater flow and hydraulic dispersion. The applicable hydraulic and transport input parameters include longitudinal (DL)and transverse dispersion (DT),average groundwater velocity (v), retardation factor (R), a source decay factor, and the length of the source. The average groundwater velocity (v) is equal to the hydraulic conductivity (K) times the hydraulic gradient (I) divided by the effective porosity ( ) The values of hydraulic conductivity, hydraulic G. gradient, and porosity used to calculate v were 0.1 1 Mday, 0.038 Mfi, and 0.25, respectively. The hydraulic conductivity value is the mean value of K values calculated from Wepo well transmissivity values and total screened interval (fi). The hydraulic gradient of 0.038 was measured from Drawing No. 85610 on the north end of the N-6 Pit. The value for n,was taken as a reasonable porosity for sandstones and shales as stated in Freeze and Cherry (1979). The hydrodynamic longitudinal and transverse dispersion coefficients are calculated from the equations: D ~ = D + a ~ v a n d D ~ = D + a ~ v where:

D is the effective diffusion coefficient in porous media as determined by D = wD* (w is an empirically
determined constant less than 1 and D* is the diffusion coefficient for specific ions or electrolytes), a L and
a~are the longitudinal and transverse dispersivity, respectively, and v is velocity vector. Typical effective

d i f h i o n coefficients are of the order of 1 x lo4 to 1 x loe5&d.

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Hydrogeoloqic Impact Analysis

Dispersivity values are scale and time dependent and are usually estimated by the scale of the area of study (direct determination of dispersivity on a field scale would involve a complex and expensive test method). The scale and time dependence of these parameters was ignored. The N-6 Pit analysis involves a study of transport fiom the pit to a potential alluvial aquifer in Coal Mine Wash, a distance of 500 ft. Two values for longitudinal dispersivity were selected for model simulations; one at one-tenth (50 ft) and one at one-quarter (125 ft) of the total distance being evaluated. The transverse dispersivity was assumed to be one-tenth of the longitudinal dispersivity, or 5 ft. and 12.5 ft, respectively. The retardation factor, R, is defined as: where:
pb is

the bulk density (M/L3 )

Kd is the distribution coefficient
The following conservative measures were assumed in developing the TDAST model simulations: The N-6 Pit and wash-plant refuse is saturated to an elevation equal to the Wepo Aquifer potentiometric surface and hydraulically connected to the Wepo Aquifer. Contaminants leaching from the wash-plant refuse are representative of the SPLP analysis and constant over time. No retardation due to adsorption or chemical precipitation occurs during solute transport from the pit. No source degradation was modeled. Homogeneous isotropic conditions are assumed Model results are two-dimensional and therefore flow and solute transport is assumed uniform with depth of the aquifer. In addition, it was inherently assumed that Wepo groundwater flowing through the refuse would produce the same concentrations as the SPLP analysis. SPLP analysis uses an acidic extractant (pH = 5.0) whereas the Wepo Formation groundwater has a pH of 7.9. It is likely that Wepo groundwater will not leach solutes from the refuse materials to the degree of the SPLP procedure. The input parameters chosen for the simulation of flow and transport at the N-6 Pit are shown below.

Western Water & Land, Inc.

4-13

Hydrologic Impact Analysis

I

Input Value TDAST Input Parameter Simulation Refuse 5 ( a~= 50 ft) 0.0167 Wd (0.0051 m/d) 0.84 ft2/d (0.078 m2/d) 0.084 ft'/d (0.0078 m%d) , 1.0 Simulation Refuse 6 ( aL= 125 ft) 0.0167 Wd (0.0051 m/d) 2.09 ft2/d(0.194 m2/d) 0.209 ftLld(0.0194 m2/d) 1.O

C

A v e r a m Groundwater Velocitv (v)
, \ ,

!

1

1

1

Longitudinal Dispersion (DL) Transverse Dispersion (4.) Retardation Factor CR)

1

The program input was configured to simulate a constant source of contaminant from the north end of the N-6 Pit, the end closest to the alluvial aquifer in Coal Mine Wash. The length of the source was estimated to be 500 ft, and situated perpendicular to the primary flow direction (west). The two dimensional program calculates dimensionless solute concentration for a x and y coordinate grid as specified in model input. The x direction was parallel to groundwater flow direction, and the y direction was perpendicular to the groundwater flow direction. The program assumes homogeneous, isotropic conditions and output was therefore assumed to represent estimates of uniform dispersion throughout the entire saturated aquifer thickness. The TDAST program produces a dimensionless concentration output that indicates concentration of a solute relative to the source concentration (C/C,), where C, is the initial source concentration. In the case of the dissolved metal aluminum, the original concentration is assumed to be the average result from the SPLP analysis of the surrogate interburden and overburden samples, a concentration of 2.6 m a . The program calculates the C/C, ratios for a two-dimensional coordinate X and Y for a specific time as designated in the input file. A value of 0.5 indicates that the concentration at that point and time is onehalf the value of the initial source concentration. In addition to use of the TDAST program, mixing calculations were performed to assess the impact on Wepo groundwater quality in response to the elevated concentrations reported on the basis of the SPLP and saturated paste extraction analyses performed on the refuse samples. As discussed in Section 4.3.1.2, elevated concentrations relative to Wepo groundwater was observed for aluminum, arsenic, barium, mercury, nitrate, nitratelnitrite, selenium, vanadium, and zinc. Calculation No. 2 (Appendix C) was conducted to evaluate mixing of pit inflow water in the N-6 Pit and leachate water generated by gravity drainage of the refuse material. The calculation, based on a number of assumptions, indicates that mixing of the two waters will result in almost imperceptible concentration changes in ambient Wepo groundwater. Mixing calculation results are presented in Table 4.5.

4-14

Western Water & Land, Inc.

Information on the vertical hydraulic gradients within the Wepo Formation at Black Mesa Mine is not available. However, well hydraulic data suggest a horizontal hydraulic conductivity value of approximately 0.1 1 ft/d, or 3.9 x lop5 centimeters per second ( c d s ) for the Wepo Formation (Section 3.5.2.4). Vertical hydraulic gradients are common in variably saturated strata, and a reasonable estimate of a vertical hydraulic conductivity value for the Wepo Formation is an order of magnitude smaller than horizontal hydraulic conductivity value. Vertical flow and transport to the Toreva Formation is therefore expected to be minimal (at least an order of magnitude less than indicated in the two-dimensional analytic model conducted for the evaluation of horizontal flow).

Model Results and Interpretation

Two TDAST simulations were conducted, one with a longitudinal dispersivity of 50 ft (15.2 m) and one with the longitudinal dispersivity of 125 ft (30.4 m). The results of the two simulations indicated that in a
25 year period the CIC, values for the 50 ft and 125 ft longitudinal dispersivity simulations are 0.005 and

0.066 at a distance approximately 500 ft (152 m) directly downgradient from the source. At the 25-year time, this concentration was calculated over a 1 5 0 4 (45.7 m) wide region or plume perpendicular to the flow direction. In the case of aluminum, the source concentration would conservatively be assumed to be

2.6 m a , the mean concentration from the interburdedoverburden SPLP analysis data. Therefore, the
dispersed concentration at a distance 500 ft from the source after 25 years of potential solute migration from the N-6 Pit is estimated to be 0.005 x 2.6 mg/L, or 0.013 mg/L. In the case of the 100 ft longitudinal dispersivity simulation, the concentration of aluminum at the same location and time would be 0.066 x 2.6 m a , or 0.17 m a . It is worth noting again that the conservative measures mentioned above and intrinsic to the TDAST model simulations should be considered when interpreting the model results. For example, the lack of retardation in the simulations provides a greater concentration (CIC,) result than a simulation with retardation. On the basis of the TDAST output and the conservative approach to model development, the impact to groundwater quality in the Wepo Aquifer from disposal and potential leaching of wash-plant refuse is considered minimal. Using a conservative model approach, the projected concentrations of solutes derived from the refuse material would be 7 percent of the initial concentrations at a distance of 500 ft downgradient of the pit and 25 years into the future.

Western Water & Land, Inc.

4.1 5

Results of the TDAST simulations were used to assess the potential impact to ambient groundwater quality for the analytes reported at statistically significant higher mean concentrations in the refuse material than in ambient groundwater. A comparison of mean analyte concentrations from SPLP data, ambient groundwater, and TDAST-calculated concentration downgradient of the N-6 Pit is provided below.

125 ft, C/Co is for location of 500 ft downgradient of refuse source and 25-year simulation time using inter-burden and overburden source value. Based partially on undetected results (onehalf of detection limit). As shown above, alluvial groundwater in Coal Mine Wash near the north end of the N-6 Pit is in some cases of poorer quality than the groundwater within the Wepo Aquifer. In addition, the estimated water quality from the TDAST simulation plus the ambient concentration from the Wepo Aquifer does not greatly differ from the alluvial well data. These concentrations were summed to approximate the resulting concentrations because the TDAST simulations assume that Wepo groundwater flows through the refuse and increases its solute concentrations directly, not by mixing of two different water sources.

4.3.2.3

J-23 Pit Numerical Flow and Transport Modeling

Similar to the N-6 Pit approach, simulations subsequent to the refuse drainage analysis addressed potential long-term unsaturated flow from the 5-23 CRA into the underlying Wepo Formation. A twowas dimensional numerical unsaturated flow and transport model, H Y D R U S ~ D ~ used to more fully assess these hydrologic processes. It was initially intended to use HYDRUS2D to model a domain that included both the refuse and Wepo Formation material types and the processes of refuse transient drainage and infiltration into the underlying Wepo Formation. This proved unfeasible because of

4-16

Western Water & Land, Inc.

Hydrogeologic Impact Analysis

excessive run times associated with a finely discretized domain. A domain with a coarse grid (1.64 ft or 0.5 m) took upwards of 7 hours to run and would result in unrealistic pressure head results. Ultimately, the critical questions to address: (1) will refuse drainage leachate infiltrate into the Wepo Formation, and (2) if so, what is the resulting leachate concentration at a specified distance and time; were addressed by using a one-dimensional grid with HYDRUS2D. HYDRUS2D requires the input of unsaturated hydraulic parameters unique to each material type being modeled for variably saturated flow and transport conditions. The parameters used to model unsaturated flow in the Wepo Formation are as follows:

Input Parameter Residual water content (&) Saturated water content (0s) a (m-'/ (ft-') ) N K (mlda~) (ft/&y) s / L Hydrus2D media type

I

Wepo Formation 0.07 0.36 0.50 / 0.15 1.09 - .. 0.0048 / 0.01 57 0.5 Silty clay

J

Wepo Formation parameters were estimated from an internal library of parameters provided in HYDRUS2D. The parameters used for the Wepo Formation were labeled "silty clay", and were selected as such because of their saturated vertical hydraulic conductivity values which were similar to the estimated value for the Wepo Aquifer materials. It is anticipated that some of the refuse drainage water that has accumulated in the bottom of the mine pit will percolate into the underlying Wepo Formation. The goal of modeling unsaturated flow in the Wepo Formation was to estimate if leachate water in the pit had the potential to migrate beyond the interpreted potentiometric surface below the mine pit. The interpreted potentiometric surface in the Wepo Aquifer is at least 150 ft below the planned bottom of the 5-23 Pit. Because the potentiometric surface is interpreted to represent head from confined groundwater within the Wepo Formation, the formation may or may not be saturated below this surface. In addition, it is possible that the unconfined lenses of groundwater exist above the interpreted potentiometric surface. Therefore, the modeling approach involved a domain of unsaturated Wepo Formation from the bottom of the pit to an elevation approximately equal to the potentiometric surface (150 ft or 45.7 m). The results of the refuse transient drainage modeling (Section 4.3.2.1) showed that up to 5.3 ft (1.6 m) of head could build-

Western Water & Land, Inc.

Hydroloqic Impact Analysis

up on the pit floor at the interface of the refuse and Wepo Formation. Although HYDRUS2D modeling showed that the accumulation of transient drainage of refuse for the 5-23 Pit would take place over an excessive amount of time (Figure 4.7), the model for infiltration into the Wepo Formation was restricted to a 200-year simulation with a flux rate on the top boundary equal to 2 x ft/day (5.5 x 10' &day). This flux rate is the approximate average flux rate as predicted by HYDRUS2D for the 5-23 Pit refuse transient drainage during the time period modeled (Figure 4.7). The flux rate was applied using an "atmospheric" boundary condition in which a precipitation rate equal to the flux rate is applied. Evaporation and transpiration were set to zero. The lower boundary represented a free drainage boundary, a condition where water is allowed to drain under a unit gradient by gravity. This boundary was seen as more realistic than a saturated water table or constant head boundary at the potentiometric surface. Initial conditions in the Wepo domain were set equal to a pressure head of -328 ft (-100 m), a condition indicating highly unsaturated conditions (on the basis of corehole data and consistent with the silty clay material selected to represent the Wepo Formation). A unit concentration (value of 1) was used for source solute concentrations in the refuse leachate. The results of the HYDRUS2D simulation showed that unsaturated flow and solute transport in the Wepo Formation of refuse leachate is limited. Figure 4.8 shows that after 200 years of simulated unsaturated infiltration, the refuse leachate progresses to and saturates Wepo Formation to an approximate depth of 8 ft (2.4 m) below the refuse/Wepo contact (within Wepo Formation). For quality presentation purposes, Figure 4.8 does not show all isolines, therefore, the actual pressure head of zero is not distinctly represented. Increases in water content, i.e. the wetting front is located approximately 30 ft (9 m) below the refuse1Wepo contact. Solute transport simulations (Figure 4.9) confirm this conclusion, and show that solute concentrations after 200 years of infiltration are equal to or less than 0.2 of the original leachate concentration at a depth 32.8 ft (10 m) below the refuse/Wepo contact. On the basis of the HYDRUS2D simulations, unsaturated flow and solute transport of the refuse leachate is extremely limited and will not approach the interpreted Wepo Aquifer potentiometric surface below the 5-23 Pit within a 200-year period. It is important to note that should refuse leachate with its full source concentration infiltrate into a continuous saturated zone of the Wepo Aquifer, the resulting concentrations of solute would be similar to the results of the TDAST simulations performed for the N-6 Pit. Saturated simulations of solute transport for the 5-23 Pit would result in smaller concentrations than the N-6 Pit simulations (for the same time and distance), because the 5-23 CRA is characterized by a smaller hydraulic gradient.

4.18

Western Water & Land, Inc.

Hydrogeologic Impact Analysis

In conclusion, the evaluation of refuse leachate fate, as supported by analytical and numerical modeling tools, indicates that impact to the hydrologic balance of water quantity and quality at BMMC will be negligible and in most probably immeasurable.

Western Water & Land, lnc.

5.0 SUMMARY AND CONCLUSIONS
The objectives of this study were to (1) evaluate potential refuse disposal sites and recommend the most favorable site(s) based on specific criteria and (2) analyze the potential probable hydrologic impact of refuse disposal in the recommended site(s). The specific criteria used for evaluation and selection of a preferred site(s) included depth to groundwater, potential for resaturation of spoil, background geochemistry, and available rehse storage space. The technical approach used to assess the potential hydrologic impact of wash-plant refuse disposal at the selected site@) included comparison of ambient water quality of groundwater to the potential chemical composition of rehse leachate water and evaluation of the potential migration of refuse leachate from the refuse disposal area. Potential migration of refuse leachate was evaluated with the use of analytical and numerical flow and transport models.

5.1

Refuse Disposal Site Evaluation and Selection

The J-23 Coal Resource Area (CRA) was identified as site having the most favorable characteristics for refuse disposal with respect to hydrologic impact. The estimated bottom of the pit will be at least 150 ft above the interpreted Wepo Aquifer potentiometric surface. In addition, the interpreted potentiometric surface is relatively uniform, of low gradient and does not diverge or converge to a local discharge area (surface drainage). The 5-23 CRA is expected to have sufficient storage volume for refuse disposal as mining operations are expected to remove 5,000,000 yds3 of coal annually. The estimated volume of refuse produced on an annual basis is 1,000,000 yds3. Coal Resource Areas N-6 and J-7, which are pits nearing completion, were considered areas of potential greater impact because the interpreted Wepo Aquifer potentiometric surface extends upwards of 30 feet above the estimated bottom of the pits. In addition, the final footprints of the N-6 and 5-7 pits will be in close proximity (500 ft) to the major surfacewater drainages of Coal Mine Wash and Yucca Flat Wash. The N-6 and J-7 pit bottom elevations would be below or near the surface elevations of these drainages, presenting another potential hydrologic impact should groundwater migrate from the pits. The J-3 Reclaimed CRA was mined in the 1970s and 1980s and is now fully reclaimed. The 5-3 Reclaimed CRA may have a potential for hydrologic impact in the long-term as the interpreted Wepo Aquifer potentiometric surface forms a hydraulic divide along the ridge where J-3 is located. Should refuse leachate migrate to a continuous saturated zone in the Wepo Formation, groundwater flow has the potential to occur in multiple directions at relatively moderate to steep hydraulic gradients. Groundwater

Western Water & Land, Inc.

5.1

underlying the 5-3 area may eventually discharge to Coal Mine Wash to the west and Moenkopi Wash to the southeast. Although the J-23 CRA was selected as the most favorable site for minimal hydrologic impact, the area will not be fully developed and able to receive refuse for an anticipated period of 2 to 3 years after startup of the coal wash plant. Therefore, PWCC directed WWL to evaluate the potential hydrologic impacts of a 3-year refuse disposal scenario at the N-6 Pit and long-term refuse disposal at the 5-23 Mine Area,

5.2

Probable Hydrologic Impact Assessment

Ambient water quality for the Wepo Aquifer across the site and in the vicinity of the N-6 and 5-23 Mine Areas was compared to analytical data generated to approximate the leachate composition of the washplant refuse. Results of the geochemical assessment indicate that leachate produced as a result of acid rain infiltrating the refuse material likely contains higher concentrations of aluminum, arsenic, barium, mercury, selenium, vanadium, and zinc than does natural groundwater in the vicinity of the 5-23 and N-6 CRAs. In the absence of geochemical modeling, the levels anticipated in leachate produced as a result of groundwater infiltrating the refuse material cannot be accurately assessed; however, it is expected that metals concentrations in groundwater induced leachate would likely be less than those reported on the basis of the SPLP analyses. On the basis of the saturated paste extraction results, nitrate and nitratelnitrate concentrations are expected to be higher in the refuse material than in natural groundwater in the vicinity of the N-6 Mining Area. Similarly, nitrate and nitratelnitrite concentrations are expected to be less in the refuse material than in natural groundwater in the vicinity of the 5-23 CRA. Analyte concentrations in leachate derived from the refuse material are expected to be similar or less than the concentrations in natural groundwater for the other metals listed in Table 4.1 and inorganic constituents listed in Table 4.2. The potential accumulation and migration of refuse leachate fiom the refuse disposal areas in the N-6 Pit and J-23 Pit were studied through the use of the application of the unsaturated flow and transport model HYDRUS~D@, a two-dimensional analytical saturated flow model, (TDAST~). and HYDRUS2D was initially used to evaluate transient drainage of the refuse. The evaluation of transient drainage from the refuse was based on refuse deposit configurations that had a maximum thickness of 70

f and estimates of refuse properties as estimated fiom material produced by raw coal pilot washing t
Reeves (2003). The results of the transient drainage simulations showed that drainage of the refbse would

5-2

Western Water & Land, Inc.

Summary and Conclusions

take hundreds of years, and that little drainage would be realized during mining operations. In the extreme long-term, a simulation for a time of over 600 years, the generated leachate would be equivalent to approximately 5.3 ft of saturated thickness in the bottom layer of the refuse material. Long-term fate of the leachate was further modeled using TDAST at the N-6 Pit and HYDRUS2D at the 5-23 Pit. In the case of the N-6 Pit, it was conservatively assumed that, in a worsecase scenario, pit inflows into the pit from the Wepo Aquifer would eventually saturate the refuse deposits placed in the pit. TDAST models convection and dispersion of solutes in saturated media. Model input requires half the source length, retardation and decay factors, and the average groundwater velocity which is dependent on hydraulic conductivity. Diffusion coefficients and longitudinal and transverse dispersivity values are also required. The input used in the model included an average hydraulic conductivity of 0.11 Wday (3.8 x cmlsec) for the Wepo Aquifer derived from PWCC's hydraulic test data. Retardation was conservatively assumed to be 1, i.e. no adsorbtion. Reasonable values for diffusion and dispersivity were used. TDAST results indicated that only a fraction (approximately 0.07) of the initial solute concentrations reported in the leachate would be present a distance 500 fi downgradient of the pit after 25 years of simulated transport. When combined with solute concentrations in the Wepo Aquifer, the resulting concentrations are less than or similar to alluvial groundwater quality in Coal Mine Wash near the north end of the N-6 Pit. In addition, calculations performed to assess direct mixing of refuse leachate and Wepo groundwater in the vicinity of the pit further demonstrate that solute concentrations in the refuse material would have minimal impact on Wepo groundwater quality. The 5-23 Pit was fkther evaluated for potential leachate migration by way of unsaturated flow into the underlying Wepo Aquifer. A one-dimensional application of HYDRUS2D was used to assess unsaturated flow into the Wepo Formation below accumulated drainage from wash-plant refuse. The model for infiltration into the Wepo Formation was restricted to a 200-year simulation with a flux rate on the top boundary equal to 2 x Wday (5.5 x 10" mlday). This flux rate is the approximate average flux rate as predicted by HYDRUS2D for the 5-23 Pit refuse transient drainage during the time period modeled (Figure 4.7). A unit concentration (value of 1) was used for source solute concentrations in the refuse leachate. The results of the HYDRUS2D simulation showed that unsaturated flow and solute transport of refuse leachate in the Wepo Formation is limited to a saturation depth of 8 R (2.4 m) (Figure 4.8). Increases in water content, i.e. the wetting front is located approximately 30 ft (9 m) below the refbse/Wepo contact. Solute transport simulations (Figure 4.9) confirm this conclusion, and show that solute concentrations

Western Water & Land, Inc.

Summary and Conclusions

after 200 years of infiltration are equal to or less than 0.2 of the original leachate concentration at a depth 32.8 ft (10 m) below the refuselwepo contact. On the basis of the HYDRUS2D simulations, unsaturated flow and solute transport of the refuse leachate is extremely limited and will not approach the interpreted Wepo Aquifer potentiometric surface below the 5-23 CRA within a 200-year period. Should refuse leachate with its full source concentration infiltrate into a continuous saturated zone of the Wepo Aquifer, the resulting concentration. of solute would be similar to the results of the TDAST simulations performed for the N-6 Pit. Saturated simulations of solute transport for the 5-23 CRA would result in smaller concentrations than the N-6 Pit simulations (for the same time and distance), because the 5-23 CRA is characterized by a smaller hydraulic gradient.

5.3

Conclusions

The 5-23 CRA provides the most favorable location for disposal of refuse generated by coal-washing operations to be conducted at the BMMC. Mining in the 5-23 CRA will be conducted in an area where the projected potentiometric surface of the Wepo Aquifer exhibits a relatively uniform and low hydraulic gradient, the bottom of the pit will be located approximately 150 fi above the projected potentiometric surface of the Wepo Aquifer, and no primary surface water drainages are located in the immediate vicinity of the pit. However, mining activities in the 5-23 CRA will not be conducted for the f ~ s2t to 3 years of the wash-plant operations. Because of this, the N-6 Pit has been selected to receive refuse during this two to three year interim period. A detailed evaluation and statistical comparison of ambient groundwater quality with potential refuse leachate composition and the application of analytical and numerical flow and transport modeling software demonstrate that impact to the hydrologic balance of water quantity and quality at BMMC will be negligible and most probably immeasurable.

Western Water & Land, Inc.

6.0 REFERENCES
Alforque, M. 2003. U. S. Environmental Protection Agency, . November. Cochran, J. 2003. Personal communication. Supervisor, Environmental Affairs, Black Mesa Mine, Peabody Western Coal Company. September. 12.p@. EPA, 2003. SPLP Method 1312, SW-846 On Line:  .-

0

o

z

'S r n E E l -

() I U)

0

0

m

0

y N - 6 BOTTOM OF COAL

SECTION SEE FIGURE 2 \

MINE NORTHING COORDINATE (FEET)

II

, I/

FIGURE 4.1

FINAL N-6 PIT BOUNDARY WITH BOTTOM OF COAL TOPOGRAPHY AND W E W AQUIFER POTEMIOMETRIC SURFACE.

,000'6Z ,ZP6'8Z

,008'82

,009'8Z

,OOP'8Z

,002'82

,000'8Z

,008'LZ

,009'LZ

,OOPILZ

,8S L'LZ

-15

-10

-5

0

5
= 600,000

10

2-D Simulation with domain 70 A (21 m) high by 335 A (102 m) wide. Pressure head scale is in metRs (satmated interval is blue).

Figure 4.4. HYDRUS2D Simulation Results, Run N-6 Pit Final. N-6 Pit Refuse Material Transient Drainas Pressure head distibution at time

Days.

-15

- 10

-5

0

5

10

F 2-D Simulation d domain 70 A (21 m) hi$i by 103 A (31 m) wide. Pressure head scale is in meters (saturated mtRval m blue). l

Saturated Thickness (ft)
0
2

hl

0

P

V1

0

-100

-90

-80

-70

-60

-50

-30

-20

-10

0

1-D Simulation, Time = 73,000 days, vertical depth of 150 ft (45 m).Pressure head scale in meters (p = 0 is saturated condition). Flux is 2E-5Wd (5.5E-6 d ) . d

Figure 4.9. HYDRUS2D Simulation Resub: Run W111D5. Infiltration of Refuse Leachate in the Wepo Formation Showing Solute Concentration. 1-D Sirnukition, Time = 73,000 days, v d c a l depth of 150 A (45 m). Ui concentrationat source (top of domain). Flux is 2E-05 fVd (5.5E-06 d d ) . nt

TABLES

a

a

a

a

(dam) sampaj r a p ~ ~ - a ~ t ! p n s

I
Table 3.2. Wepo Aquifer Hydraulic Testing Results

I

Wepo Wells Arithmetic Mean Hermonlc Mean Geometric Mean
116.60 1.57 36.24 8.20E-05 219.71 194.31 208.32

-

---

0.07 0.00 0.02

0.11 0.00 0.03

1
I I

Notes: 'Well completed in Wepo and Tomva Formations I lams1 = above mean sea level ldpd = gallons per day 1 bgs = below ground surface ft = feet bmp = below monitoring point I 1

I

I

I

Table 3.3: Comparison of Summary Statistics for Metals Concentrations in Groundwater Samples Collected from Site-Wide and Local-Area Wells Nun er of Samples Concentration 2 Total Detection Limit Concentrations 2 Detection Limit ( Mean Std Dev Max

Analyte

I

I

duminum Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells menic Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells sarium Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells 3oron Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells :admiurn Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells :alcium Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

0.21 8 0.023 0.044 0.080 0.073

0.003 0.002 0.001 0.002 0.002

0. I 6 0 0.024 0.01 1 0.1 70 0.303

0.188 0.086 0.060 0.048 0.246

0.003

-----

---0.0007 109 58 7.2 111 114

I

I

Page 1 of 4

Table 3.3 (cont.): Comparison of Summary Statistics for Metals Concentration in Groundwater Samples Collected from Site-Wide and Local-Area Wells Number of Samoles Analyte
>hromium Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells :opper Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23Wepo Wells N-6 Wepo Wells ron Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells &ad Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells wlagnesium Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells vlanganese Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

Total
648 54 47 59 61

Detecion Limit

Cor entrations ; Min Max (msn) (msW
0.01 0.01 0.01 0.01 0.20 0.01

Mean

own-)
0.02 0.01

---.

----

----

0.01 0.01

0.01 0.01

648 54 47 59 61

0.01 0.01 0.01 0.01 0.01

0.36 0.01 0.01 0.01 0.01

0.03 0.01 0.01 0.01 0.01 1.a 0.6 0.01 0.5 1.a

656 56 47 59 62

0.01 0.01 0.01 0.0; 0.01

14.8 3.24 0.74 2.1 4.5

648 54 47 59 61

0.02C 0.0; O.OE 0.02C 0.0;

0.1 00 0.1 0.06 0.020 0.08

0.041 0.042 0.06 0.020 0.0%

650 56 47 59 61

0.32 0.32 0.L
1

0.;

773 240 11 206 82

61.? 24.3 2.12 445 37.5

648 54 47 59 61

OO t .O O.OO! O.OO! 0.00; O.OO!

2.88 1.24 0.17C 0.1lC 0.70C

0.1 52 0.12: 0.03: 0.054 0.1 51

Page 2 of 4

Table 3.3 (cont.): Comparison of Summary Statistics for Metals Concentration in Groundwater Samples Collected from Site-Wide and Local-Area Wells

Nun Total

Analyte

Concentrations 1 Detection Limit Max Mean Std Dev Min Detecion Limit

I

I

I

Aercury Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells 'otassium Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells jelenium Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells Silver Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells ;odium Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells /anadium Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

648 54 47 59 61

649 56 47 59 61

648 54 47 59 61

387 37 26 34 44

656 56 47 59 62

648 54 47 59 61

1

I

I

I

Page 3 of 4

Table 3.3 (cont.): Comparison of Summary Statistics for Metals Concentration in Groundwater Samples Collected from Site-Wide and Local-Area Wells

I
Analyte Number of Samples Concentration 2 Total Detecion Limit
641 53 47 59 61 200 26 9 17 16

Concentrations 2 Detection Limit Std Dev Mean Min Max (mSn) (mSn) (mSn) (mSn)
0.005 0.01 0.01 0.01 0.01 1.23 0 .07 0.02 0.25 0.20 0.04 0.02 0.01 0.03 0.04 0.1 1 0.02 0.00 0.06 0.05

Zinc Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 W e ~ o Wells

Page 4 of 4

Table 3.4: Comparison of Summary Statistics for Inorganic Concentrations in Groundwater Samples Collected from Site-Wide and Local-Area Wells

650 56 47 59 61 42 1 32 32 38 39 42 1 32 32 38 39 263 18 21 25 19 650 56 47 59 61

Analyte

NUIT er of Samples Concentration 2 Total Detection Limit

dkalinity as CaC03 (mg/L) Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells licarbonate as CaC03 (mg1L) Site-Wide Wepo Wells 5-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells :arbonate as CaC03 (mg1L) Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells {ydroxide as CaC03 (mg/L) Site-Wide Wepo Wells 5-3 Wepo Wells J-7 Wepo Wells 5-23 Wepo Wells N-6 Wepo Wells 2hloride (mg/L) Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells 5-23 Wepo Wells N-6 Wepo Wells >onductivity(ums/cm2) Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

1609 144 99 132 153

Page 1 of 3

Table 3.4 (cont.): Comparison of Summary Statistics for Inorganic Concentrations in Groundwater Samples Collected from Site-Wide and Local-Area Wells

-

Analyte

Nun er of Samples Concentration2 Total Detection Limit

horide (mg/L) Site-Wide Wepo Wells 5-3 Wepo Wells 5-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells ditrate as N (mg/L) Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells Jitrate-Nitrite as N (mg/L) Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells Jitrite as N (mg/L) Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

Concentrations > Detection Limit Min Max I Mean I Standard Value - Value Value Deviation

-

I

I

I

I

I
I

I

I
I I

I

)H (s.u.) Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells
Sulfate (mg/L) Site-Wide Wepo Wells 5-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

)

1 i
)

)

! 3 I 5 !

Page 2 of 3

Table 3.4 (cont.): Comparison of Summary Statistics for Inorganic Concentrations in Groundwater Samples Collected from Site-Wide and Local-Area Wells Number of Samples Concentration 2 Total Detection Limit 1248 119 72 1248 119 72 98 123 Concentrations > Detection Limit Min Max Mean Standard Value Value Value Deviation 320 610 566 1118 5901 8010 4648 2056 5038 44001 1833 1940 877 2310 18461 1355 1019 366 1223 14711

Analyte

I

TDS (rngiL) Site-Wide Wepo Wells J-3 Wepo Wells J-7 Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

I,",",

I

Page 3 of 3

'pesn eJe e!pew qwuU lueld megns le~uewelddns eJeqM sjeuuellr, eUsu!elp u!sw pue 'sUu!lueld le~nllno 's)el!qBtlAey 'sedols deep Uu!pnpu! sew8 uo!~ewepe~ p!oeds p symuenu! loo4 E 01 1 pue 1 ol 0 eql 1 4 Aluo pesn em euel!n EJ!l!qel!ns eseql 'L , 0 'Jew0 wee q1!m pelelsum AlqB!q we senb!uqe) OM)eseql esnrneq 3 ~ e q l~ mqlo p e e 40 Alluepuedepu! pesn eq Alle~eueB l !spmpuels pue sesApue wn!ueles elqepwlxe v d 1 a - w pus elqnlos JeleM104 elU '9 ~e 8 l ~ 'elem lew pejeqleem yoelq pue eleqs s n o m e u q w y3qq 01 AwB ylep hen 105 peuiuuelepeq Aluo l l !8 - s 'smuepu! Ile ul 'ueplnyeno eq) u! pey!juep! u w q eneq ~ - S M H slenel welqo~d m q ~ ~ ~ ~ p e seem uo!lewelw w n l y pue 'ewe uo!lewape~ 1 841 w q p e p l l w pxls 'elep BSMH Gup!xe ou s! ueql weqM luewssesse eu!lesaq ueprnqmo pue ~!os n l y J O eyns lw!flleue et# u! pepnpu! eq Aluo Il!m s!sAleue uwoq elqnlos ~ e l e f i e q l 'S 0 ~ w ~ loq .seu!lep!nB oqxew M ~ e y u! p e y ! d s se Jylns o!g~Ad N wo4 pelelmlw eq lsnw le!lue~od p!oe e q l . ( ~ 8 69jsn6ny) ~ U W S woy muepuodseuw uodn peseq sjenel iIl!l!qel!nS 'leuelew p SUOIOOOL ~ e luelen!nbe e p u o q m wnplw suot w e sl!un 'p '~ O d (O L Z SE ' II Pes!AeJ) (5861.) 3 3 ~ u! t e~nB!j urnow se d u! u qns e o~ tlws 'E ( 6 % ~ ) l c n s pue weAv w q peldepe sessep p m e q uo!twi~yu! jo euoz uolpnpw ou 01 1qB!ls 841u! e4 tsnw ~!ods ~ n ~ u ~ s euoz IOOJ J O U ! ~q l ~ senlen tfvs wnu!mw elqel!ns 'Ilen!pedsw Aep %SE~4 ~ e~ eql 'sew uo!lewepey E-r eq1 u! pels301 sel!S uo!leweloey 104 sewul ZL ol g m w s ew 50 =!IS!JW~J~KJ @!pew q w w 9 iueld m e w s ~ewewelddns) I!O~S elqel!ns s! Z-Z-zzelqel 'seeit/ uo!~~me~oetl pue WL-N 'z-N 'L-N '*NIL-r LZ-r '1-r 'E-r 841u! p e ~ msie w uo!~eue~oetl =!lsuepemq3 (e!pew JOJ qwo~9 lueld megns p~uewelddng) d s eiqel!nS,, s! 2-z-zz elqel 'eu!w mew wela 'seu!U e l u d q pus mew y3elg 'ueld uo!iewepey pue B u l u ! ~3861 'Auedwo3 1803w e l s e ~ p Apoqeed :u! 2 - p n elqel pue~-z-zz elqe1.Z I ~7 lsnr3nw OUR

Table 4.3: Comparison of Summary Statistics for Refuse Samples (SPLP-Metals) and Groundwater Samples Collected from the Site-Wide Well Network, 5-23 Area, and N-6 Area

Nun Total
23 648 59 61 23 649 59 61 23 385 34 42 23 650 59 61 23 648 59 61 23 656 59 62 23 648 59 61

her of

Analyte
4luminum Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells irsenic Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells 3arium Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells 3oron Refuse (SPLP) Site-Wide Wepo Wells 5-23 Wepo Wells N-6 Wepo Wells 2admium Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells Zalcium Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells :hromium Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

Samples Concentration r Detection Limit

Min

Concentrations > Detection Limit I Max I Mean I Std Dev

Page 1 of 3

Table 4.3 (cont): Comparison of Summary Statistics for Refuse Samples (SPLP-Metals) and Groundwater Samples Collected from the Site-Wide Well Network, 5-23 Area, and N-6 Area

Nurr Total

Analyte

Min Detection Limit

Concentrations > Detection Limit Max Mean Std Dev

I

I

I

:opper Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells .on Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells .ead Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells Aagnesium Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells Aanganese Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells Aercury Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells 'otassium Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

i :

23

648 59 6 1
23

656 59
62
23

648 59 6 1
23

650 59 61
23

648 5 9 61
23

648 59 61
23

649 59 61

Page 2 of 3

Table 4.3 (cont.): Comparison of Summary Statistics for Refuse Samples (SPLP-Metals) and Groundwater Samples Collected from the Site-Wide Well Network, 5-23 Area, and N-6 Area

23 648 59 61

Analyte

Nun er of Samples Concentration > Total Detection Limit

Min

Cor entrations Max
(mglL)

(msn)

ielenium Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells iilver Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells iodium Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells fanadium Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells Iinc Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

0.001 0.001 0.001 0.001

0.011 0.560 0.003 0.002

23 387 34 44 23 656 59 62

0.01 0.01

-

0.01 0.02

--

0.01 0 0.5 15 416 41 0.020 0.005 0.005 0.010

0.010 63.7 1570 1180 I436 0.090 0.020 0.020 0.010

23 648 59 61

23

641

-

59 61

0.05 0.005 0.01 0.01

0.41 1.23 0.25 0.2C

Page 3 of 3

Table 4.4: Comparison of Summary Statistics for Inorganic Concentrations in Refuse Samples (SPLP and Paste Extraction) and Groundwater Samples Collected from the Site-Wide Well Network, J-23 Area, andN-6 ~ r e a . ~ 3

23 650 59 61

Analyte

Nun ler of Samples Concentration > Total Detection Limit

Concentrations > Detection Limit Min Max Mean / Std Dev

I

I

Ukalinity as CaC03 (mg/L) Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells 3icarbonate as CaCO, (mg/L) Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells ;arbonate as CaC03 (mglL) Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells 4ydroxide as CaC03 (mg/L) Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells 2hloride (mglL) Refuse (SPLP) Refuse (Paste Extraction) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells 2onductivity (ums/cm2) Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells -1uoride (mg/L) Refuse (SPLP) Site-Wide Wepo Wells 5-23 Wepo Wells N-6 Wepo Wells

23 42 1 38 39

23 42 1 38 39

23 263 25 19 23 6 650 59 61

23 1609 132 153 23 654 59 62

Page 1 of 2

Table 4.4 (cont.): Comparison of Summary Statistics for Inorganic Concentrations in Refuse Samples (SPLP and Paste Extraction) andGroundwater Samples Collected from the Site-Wide Well Network, 5-23 Area, andN-6 Area

6 648 59 61

Analyte

Nun er of Samples Concentration > Total Detection Limit

mit Std Dev
(mgU

rlitrate as N (mgIL) Refuse (Paste Extraction) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells \litrate-Nitrite as N (mgIL) Refuse (Paste Extraction) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells \litrite as N (mgIL) Refuse (Paste Extraction) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells
IH (s.u.) Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

0.31 25.9 0.52 0.08

6 490 46 41 6 648 59 61

0.31 22.4 0.60 0.05 0.04 0.40 0.73 0.33 1.o 0.5 0.6 0.6

23 648 59 61

Sulfate (mg/L) Refuse (Paste Extraction) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells TDS (mg1L) Refuse (SPLP) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells rota1 Phosphate (mgIL) Refuse (Paste Extraction) Site-Wide Wepo Wells J-23 Wepo Wells N-6 Wepo Wells

6 656 59 62

897 916 1026 1032

23 I248 98 123

48 1355 1223 1471

6 NA NA NA

10.7 NA NA NA
L

Page 2 of 2

Table 4.5: Solute Concentration Mixing Calculations cpl (mglL) 0.120 0.002 0.105 0.0003 0.080 0.070 0.002 0.01 0 0.040 (Qp x Cp) + (Qr x Cr) (ft3lday * mglL)

Solute

Aluminum Arsenic Barium Mercury Nitrate NitrateINil Selenium Vanadium Zinc

' Concent

ion of pit in1 corresponds to the mean concentration for site-wide or local-area N-6 wells, which ever is lower for the specified analyte. Cp = concentration of pit inflow solute Cr = concentration of refuse solute

Where: Qp = pit inflow rate Qr = refuse inflow rate (Qp x Cp) + (Qr x Cr) = Qt x Ct Qp = Qr= Qt =
705.54 ft3/day 4.76 fi3/day 710.30 ft3/day

Wepo water pit inflow Refuse water inflow Total comb i n d flow

5-7 Coal Resource Area

Borehole Data Wepo Well 47R, the replacement well for abandoned Wells 47 and 48, is collared at 6277.7 ft, has a TD of 302 ft, and is located approximately 1,000 ft west of the abandoned wells. During drilling (April 1, 1998) groundwater was noted at 56 ft and 160 to 165 ft. The well is perforated at depths of 52 to 62 ft, 82 to 112 ft, and 122 to 220 ft. Bentonite seals are at depths of 5 to 14 ft, 14 to 29 ft, 29 to 50 ft, 114 to 120 ft. and 272 to 302 ft. Well 47R has an average depth to water level of 3 1.5 ft. Assuming that alluvium is also approximately 20 ft thick in this area (Yucca Flat Wash), Wepo groundwater is currently not discharging to the alluvial aquifer in this area. Wepo Fm wells 47 and 48 (since been replaced by 47R), were located in Yucca Flat Wash, the main surface drainage south of the 5-7 Pit. Well water levels may be influenced by surface flow and recharge from alluvium in Yucca Flat Wash. Borehole 47 lithology log shows 20 ft of alluvium (sand and gravel) "damp" gray shale from 24 to 3 1 ft, "wet" coal at 36.8 to 38.3 ft, "wet" gray shale at 38.3 to 43.5, "wet" dark shale at 54.4 t o 56.4, then interbedded gray shale with coal then interbedded sandstone and shale to 220 ft; last coal is 261.9 to 271.9. TD was 323 ft; well constructed to 220 ft. Perforations at 35-73', 83-108', 117-147', 172-220'. No discussion of fractures. Borehole 48 lithology log shows 20 ft of alluvium (sand and gravel), ."damp" gray shale from 24 to 3 1.8 ft, "wet" coal at 36.8 to 38.3 ft, "wet" gray shale at 38.3 to 43.5, "wet" dark shale at 54.4 t o 56.4, then interbedded gray shale with coal then interbedded sandstone and shale to 220 ft; last coal is 261.9 to 271.9. TD was 323 ft; well constructed to 220 ft. Perforations. At 40-75', 85-1207,125-145', 172-220'. No discussion of fractures Corehole Data Corehole 15418C: Collared at 6538.1 ft. TD is 248 ft. Corehole description shows interbedded shale and C sandstone with coal beds ranging from less than 1 ft to over 7 ft thick. No reports of lost circulation, fractured areas, or lost core. Corehole 23 154C: Collared at 6463.6 ft. TD is 200 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 17 ft thick. Burnt zones at 20.2 to 24.2,40.1 to 50.1, fractured at 50.1 to 57.4, cavity, lost core, loose and fractured 57.4 to 76.0, other lost core zones at 109.3 to 110.2, 169.3 to 170.0, 176.4 to 177, damp shale at 90- 100,170 to 176.4. No reports of lost circulation. Corehole 23 l56C: Collared at 6467.1. TD is 200 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 21.3 ft (RXX). Burnt shale zones, lost core, lost circulation at 2 to 30 ft, 36 to 42 ft, burnt, loose, lost core and fractured 42 to 44.7 ft, damp shale at 44.7 to 49.7 ft, lost core and

loose at and more burnt 49.7 to 66.4 ft, burnt 71.4 to 83 ft, damp shale at 159.4 to 163.5 ft, 173 to 180.6, 191 to 197.8 ft. Also, had lost core at 158.7, 163.5, 172, and 180.1.

N-6Coal Resource Area
0

The corehole data in the N-6 region indicate multiple wet zones and zones of lost circulation. The coreholes in proximity to the final pit footprint are 24099C, 24400C, and 24401C. The corehole logs for these boreholes indicate several wet intervals at elevations between 6,545 and 6,595. These wet zones do not correlate with the mapped potentiometric surface; they are at elevations greater than the potentiometric surface, but within the exposed pit elevation interval.

In the N-6 area, corehole logs 24099C, 24400C, and 24401C, which lie on a north-trending transect near the final pit footprint, indicate wet and damp conditions in the upper portions of the borehole. Wet conditions are more prevalent in corehole 24099C, which was located near the southern end of the final pit footprint. Corehole 21 1O K : Collared at 6726.0. TD is 245 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 12.9 ft (RXX at 120.3 ft bgs). Lost circulation at 10.0 to 10.4, 19.9 to 20,21 to 22,25 to 26,30.2 to 31, 4 1.3 to 41.7, and 82.1 to 82.6. No lost circulation below 82.6 (may imply more dense, competent rock below this depth). Wet shale zones at 19.3 to 19.9,20.0 to 20.4. Corehole 23 160C: Collared at 6807.2. TD is 220 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging fiom less than 1 ft to 10.7 ft (RXX at 127.5 ft bgs). Lost circulation at 20.5 to 20.7,23.4 to 23.8, 33.4 to 33.7,55.8 to 56, 57.4 to 58, 86.1 to 86.8,92.3 to 92.7, and 102. 9 to 103.5, 153.8 to 154, 163.8 to 164, and 203.8 to 204. Wet shale zones at 18.5 to 23.8 (with lost circ.), 55.5 to 57.4 (with lost circ.); wet coal and shale at 82.6 to 86.8 (with lost circ.), wet shale at 102.9 to 103.5 (with lost circ.), Corehole 23 161C: Collared at 6729.5. TD is 200 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 11.3 ft (RXX at 117.3 ft bgs). Lost circulation at 3 1.2 to 31.5,39 to 39.3, 145.2 to 146, 146 to 146 (loose), and 148 to 149 (and fractured). Wet shale zones at 30.8 to 3 1.5 (lost circ.), 32.7 to 33.3,38.6 to 39, 80.7 to 98.4 (sand/shale), sandstone 146 to 148 (loose); damp sandstone 149 to 150.9 (fractured), damp sandstone or shale 154 to 163 (lost core), damp shale 163 to 166.2. Lost core 162.5 to 163, 189.7 to 190. Corehole 23 162C: Collared at 6646.8. TD 200 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging fiom less than 1 ft to 11.3 ft (RXX at 8 1.4 ft bgs). Lost circulation at 22.9 to 23.1,39 to 40,49.4 to 50.2,96.9 to 97.3, and 185.9 to 186.3. Wet shale and sandstone zones at 12 to 23.1,39 to 42.

Corehole 23163C: Collared at 6637.9. TD 180 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 12.3 ft (RXX at 99.7 ft bgs). Lost circulation is not reported. Lost core at 25 to 25.2,51.7 to 52.3,58.7 to 59.9, and 8 1.9 to 83.1. No reports of wet conditions. Corehole 23 164C: Collared at 6607.2. TD 200 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 12.8 ft (RXX at 102.7 ft bgs). Lost circulation is not reported. Lost core at 22.2 to 23.2, 84.1 to 84.6. Damp shale and coal at 12.8 to 23.2, shale at 55.1 to 64.9. Wet shale and coal at 193.9 to 197.7. Corehole 23 l 6 X : Collared at 6664.7. 'I'D 200 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 11.1 ft (RXX at 114.3 ft bgs). Lost circulation is not reported. Lost core in portions of intervals at 37.1 to 38,39.6 to 40, and 199.8 to 200. Damp shale at 34.8 to 47.2, 171.9 to 182.4. No wet intervals reported. Corehole 23 166C: Collared at 6798.6. TD 260 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 7.3 ft (BXX at 110.2 ft bgs). Lost circulation is not reported. Lost core in portions of intervals at 30 to 3 1,34 to 34.5,53.1 to 53.7,71.3 to 71.8,72.6 to 73.6, and 91.1 to 91.5. Damp shale or sandstone at 12 to 30,72.6 to 73.6, 131.5, 164. 8,213.1 to 216.9,218.6 to 231.6. No wet intervals reported. Corehole 24093C: Collared at 6727.8. TD 270 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 11.7 ft (RXX at 184.3 ft bgs). Lost circulation is not reported. Lost core in portions of intervals at 2 1.8 to 22,48 to 49,57.8 to 58, and 101.8 to 102. Damp clay at 0 to 4, shale at 16.7 to 18.3,49 to 49.8, 52 to 57.8, sandstone at 141.2 to 156.6. No wet intervals reported. Corehole 24094C: Collared at 6582.9. TD 230 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging fiom less than 1 ft to 12.7 ft (RXX at 122.3 ft bgs). Lost circulation is not reported. Lost core in portions of intervals at 38.2 to 38.8, 40.8 to 41.5, 51.3 to 51.6, 88.7 to 89.6, 112.3 to 112.5, and 122 to 122.3. Damp shale at 38.2 to 47.5, sandstone at 61.7 to 81.8. No wet intervals reported. Corehole 240932: Collared at 6686.2. TD 280 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 9.3 ft (BXX at 176 ft bgs). Lost circulation is not reported. Lost core in portions of intervals at 16.6 to 17, 21.7 to 22,37.6 to38,40 to 41,45.6 to 46. Damp clay at 17 to 18.4, shale at 45.6 to 46, 154.4 to 154.8, 163.8 to 169.3, sandstone at 232.2 to 243.8. No wet intervals reported. Corehole 24096C: Collared at 6665.1. TD 290 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 11.6 ft (RXX at 200.5 ft bgs). Lost circulation is not reported. Lost core in portions of intervals at 41.7 to 42,61 to 62, 142.8 to 143.1,215.5 to 216.1,226.4 to 226.9,254 to 254.2,263.9 to 264, and 273.9 to 274.2. Damp shale at 40.5 to 41.7,52 to 53.4,56 to 61,62 to 72, sandstone at

82.2 to 92.7, shale at 94.7 to 95, wet shale at 95.6 to 96.7, damp shale at 107.2 to 115.5, damp coal, shale, sandstone, damp sandstone at 163.5 to 171.7, damp shale at 181.3 to 183.8, wet shale and coal at 183.8 to 212.1, damp shale at 212.1 to 212.8,213.7 to 214, 226 to 226.4, wet shale at 228 to 228.9. Corehole 24097C: Collared at 6649.1. TD 260 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 12.7 ft (RXX at 178 ft bgs). Lost circulation is not reported. Lost core in portions of intervals at 19.8 to 20, 34.2 to 35,44 to 45,52.8 to 53.2,70.7 to 71.3,80.9 to 81.3, and 129.9 to 130.4. Damp shale at 12 to 14.2, 16.2 to 20,30.1 to 34.2,40.3 to 44,45 to 46,46.7 to 49.5,60.6 to 62.8,71.3 to 78.1 78.6 to 80.9, sandstone and coal at 82 to 92.3, shale at 101.4 to 111.7, wet shale at 124.7 to 129.2, damp shale at 158.7 to 162, wet sandstone at 213 to 217.3, damp shaleat218.7 to233.1. Corehole 240986: Collared at 6589.1. TD 220 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 A to 11.1 ft (BXX at 107 ft bgs). Lost circulation is not reported. Lost core in portions of intervals at 16.6 to 17.6, 20.6 to 21.6,30 to 31,35 to 35.4, 50.7 to 51.7, 132.5 to 133.7, 136.5 to 137.2, 145.8 to 146, 160.1 to 160.6, 164.9 to 165.4, 173 to 173.6, and 215 to 220. Burnt sandstone at 13.6to 14.6. Damp shaleat 17.6 to20.6,21.6 to24.4,25.4 to29, dampcoal at 31 to 32, damp shale at 32 to 35.4,47.5 to 51.7, damp sandstone at 82.4 to 107, damp shale at 134.4 to 141.4, wet coal and shale at 194.8to 198.5. No wet intervals reported.
0

Corehole 24099C: Collared at 6668.7. TD 225 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 10.8 ft (BXX at 109.2 ft bgs). Lost circulation is not reported. Lost core in portions of intervals at 3 1.8 to 32,68.4 to 69.4, 78.5 to 79.5, 124.6 to 125.4, 131.6 to 133.5, 153.3 to 153.5,207.5 to 208,214 to 214.7, and 224.6 to 225. Damp shale at 38.2 to 47.5,62 to 66.2,67 to 68.4, damp coal and shale at 71.4 to 78.5, damp shale at 79.5 to 81.2, wet shale at 81.2 to 93.5, damp sandstone at 93.5 to 109.2, =shale at 120 to 121.6, damp sandstone at 121.6 to 125.4, damp shale at 133.5 to 136.5. Corehole 24400C: Collared at 6614.8. TD 200 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 10.9 ft (BXX at 61.7 ft bgs). Lost circulation is not reported. Lost core in portions of intervals at 15 to 15.3, 19.7 to 20,22.3 to 22.6,39.6 to 40, 105.9 to 107, 132.7 to 133, 148.4 to 148.7, and 198.2 to 200. Damp shale at 12 to 15, 19.7 to 20, wet shale at 20 to 22.3, damp shale at 22.6 to 30,31.2 to 32.1. Corehole 24401C: Collared at 6564.7. TD 130 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging &om less than 1 ft to 7.2 ft (RXX at 58.9 ft bgs). Lost circulation at 90.7 to 111.4. Lost core in portions of intervals at 18.5 to 19, 20.5 to 22,28.6 to 29.6,34 to 35.5,39.4 to 50, and 128.1 to 130. Burnt shale at 23.2 to 28.6,29.6 to 34, sandstone at 35.5 to 39.4. Cavity in shale at 39.4 to 50. Damp shale at 12 to 18.5, wet shale at 19 to 20.5, damp shale at 22 to 23.2,70.3 to 74.9.

Corehole 24402C: Collared at 6668.3. TD 200 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 7.9 ft (GBX at 61 ft bgs). Lost circulation is not reported. Lost core in portions of intervals at 95.8 to 96.3, 96.5 to 97, 112.7 to 113.3, 114 to 114.8, 184.1 to 185.1, and 195 to 200. Damp shale at 0 e J to 7.5, sandstone at 12 to 50.1, y coal at 113.3 to 114, damp shale at 185.1 to 200.

5-23 Coal Resource Area
Geology Corehole 30365EO: Collared at 7016.194 ft. TD 220 ft. Corehole description shows interbeded shale and sandstone with coal beds ranging from less than 1 ft to 23.9 ft (BXX at 78 ft bgs). "LC" (assume "LC" means lost core) was reported in portions of intervals at 0 to 3.8,7.3 to 13.4,20 to 21.8,41.5 to 42,50 to 50.4,74 to 74.2, 121.1 to 122. Damp and wet conditions not reported.

5-3Reclaimed Coal Resource Area
The 5-3 Mine Area is a reclaimed area that was originally mined in the 1970's and 1980's. No core hole or well bore hole data were immediately available.

APPENDIX B
Wepo Well Hydrographs

Water Level Elevation (ft amsl)

£OOZ/£1 1 1 Z O I 1IL O ZE ZOOZlS 1 1 1 100Z/~ 1IL 100ZIE1 1 1 000Zf£1 L 1 O Ol 11 O ZE 1 666 1 ' 1IL 1 2 666 LIE 1 1 1 866 LIE 1IL 866 LIE 1 1 1 L66 LIE 1/L L66 1 61 1 1 1 966 LIE 1 L 1 966 1 s1 1 1 1 S66 LIE 1 L 1 S661IE1f 1 P66 1IEllL $7661 61 1 1 1 E66LIE1IL € LIE 1 1 66 1 Z66 1IE1IL Z66 LIE 1 1 1 166LIE 1IL 1661 ' 111 1 2 066 LIE 1IL 066 1 s 1 1 1 1 686 LIE 1IL 686 1 s 1 1 1 1 886 LIE 1 L 1 886 LIE 111 L86 1 s1IL 1 L86 1 81 1 1 1 986 1 s1IL 1 986 1fE1 1 1
(u

2

CI

Water Level Elevation (ft arnsl)

Water Level Elevation (ft amsl)

Water Level Elevation (ft amsl)

Water Level Elevation (ft amsl)

Water Level Elevation (ft amsl)

Water level Elevation (ft amsl)
m
0

CD

0

0 ,

cn

Water Level Elevation (ft amsl)

Water Level Elevation (ft amsl)

APPENDIX C
Calculations

CALCULATION NO.l Calculation of volume water content In wash-plant refuse. Statement of Problem: Calculate theta, the water content by volume in the wash-plant refuse material. Assume: 1.45 % of refuse is coarse material with 7% moisture content and 55% is fine material at 40% moisture content 2. Weight of water is lglcrn3 3. Saturated porosity is 0.3881 (from Rosetta software) 4. Use relationship: 0 = w(pdp,) where: 0 is volumetric water content, w = mass or gravimetric water content, pbis bulk density of material, p is density of water (glcm3) , 0.76455 Conversion yd3/m3 Volume Refuse per year (yds3) Bulk Density Ibslft3 Bulk Density glcm3 Bulk Density glm3 Volume Refuse per year (m3) Estimated wt. of Waste (g) Estimated wt. of water (g)

Estimated vol. water (cm3)

Estimated vol. water (m3)

Coarse Material yds3 per year

Fine Material yds3 per year

Total Total volume of water (m3) (yd3) The overall moisture content by volume Is: The overall molsture content by weight is:

764,550.00

0.2326 0.2382

1

, Therefore, if given a 40 % by volume water content as 0 (100 % saturation), 24% of the waste by volume is actually saturated or 24/40 or 60% saturation.

:ALCULATION NO. 2 lixlng Calculation for N-6 Pit Wash-Plant Refuse Leachate and Wepo Aquifer Groundwater

itatement of problem: Calculate the resulting concentration of solutes in refuse leachate when instantaneously mixed with Wepo Aquifer groundwater.

3efuse Material Composition and Properties I. The composition of refuse is based on information from Hazen Research: 47% Sand, 20% Silt, 33 % Fines 2. PWCC estimates a bulk density of 1.6 gIcm3 or approximately 100 lbs/ft3 3. The program Rosetta "was used to estimate the unsaturated hydraulic properties: 3 = 0.0715%, Qs = 0.3881%, alpha =2.04, n = I .268l, Ks = 0.0622 m/d , L = 0.5 Qr is the residual water content; Qs is the volumetric saturation percent when pores are 100% saturated. Ks is the saturated hydraulic conductivity; alpha, n, L are constants. $.Instantaneousdeposition and drainage of 3-year deposit of refuse in N-6 Pit. 5. Total deposit is 3,000,000 yds3 and contains 24% water content by volume (theta) per Calculation No. 1 3. Configuration of Refuse deposit in N-6 Pi: 81,000,000.0 ft3 Refuse deposit is 70 ft high x 335 ft wide x 3454 ft long = This is equivalent to 3,000,000 yds3 or 3 years of disposal in the pit. ?it Inflow from Wepo "Aquifer" 1. Seepage face thickness is the distance from the bottom of the pit to the potentiometricsurface This is estimated to be 20 ft.

2. Pit inflow rate is: or: 3. Assume uniform flow in all areas of pit. 4. Final pit length: 5. Pit inflow rate per linear ft of pit: 5. Length of pit accepting refuse in 3 years with 70 ft thickness and 335 ft width: 7. Pit inflow along refuse deposit: Estimated time to fill pit to pot. surface in refuse deposit: [(20 ft x 3454 ft x 335 ft) x 0.38811R05.54 ft3/day
Volume of water in refuse from pit inflows: [(20 ft x3454 ft x 335 ft) x 0.38811 Refuse Transient Drainage 1. Volume of water generated by transient drainage of refuse in 3 year deposit: After 500,000 days, HYDRUS2D simulation indicated 5.3 R of saturation Therefore: (5.3 ft x 335 ft x 3454 ft) x 0.3881 2. The approximate rate (assume linear relationship)that the drainage water is generated: 2,380,053 ft31500,000 day 3.The Drainage Factor : Total volume of water drainedrrotal volume of refuse: 2,380,053.13 ft3181,000,000 ft3= 4. The percent water drained of total assumed water content:

3,182,179.00 gallonslyr (PWCC 1985) 1,165.55 ft?day 5,706.00 R 0.20 ft3/day-ft 3,454.00 ft 705.54 ft3/day 12,729.73 days 34.88 years 8,981,332.58 ft3 (Lehn 2003)

HYDRUS2D Simulation (see attached plot) 2,380,053.13 ft3 4.76 f13/day 0.03 %

CHAPTER 19

HYDROLOGIC RECLAMATION PLAN

CHAPTER 19

INDEX Page Introduction Practices Employed to Minimize the Impact of Mining on the Hydrologic System Acid and Toxic Materials Drainage Control and Water Quality Standards Restoration of Approximate Premining Ground Water Recharge Capacity Water Rlghts and Alternative Water Supplles

Monitoring Plan
Introduction Ground Water Monitoring Plan Surface Water Monitoring Plan Literature Cited

LIST OF TABLES
Page

Table 1

Recommended Numeric Water Quality Standards for Domestic, Livestock, Agricultural Irrigation, and Ephemeral Aquatic Water Uses

Table 2

Monitoring Sites and Programs Utilized to Substantiate Significance Findings of Chapter 18, Probable Hydrologic Consequences

Revised 11/21/03

CHAPTER 19

HYDROLOGIC RECLAMATION PLAN

Introduction

The hydrologic reclamation plan is presented in two parts.

The first part focuses on

specific practices that are conducted to minimize the impact of mining on the hydrologic balance within and adjacent to the leasehold. that may occur regardless of these practices. The second part addresses those impacts The emphasis of the second part is on the Where possible, reference has

monitoring of the extent and magnitude of mining impacts.

been made to those chapters that contain details regarding certain practices.

Practices Employed to Minimize the Impact of Mining on the Hydrologic System

Acid and Toxic Materials. mining pits. conducted and to

Overburden and parting materials are placed in or adjacent to

Therefore, overburden and innerburden core chemical analyses have been the results the reviewed by acid a biologist, of the geologist, soil material and to scientist determine and the

hydrologist

assess

potential

concentrations of salts and trace metals (Chapter 8).

Further, hydrologists have made a

determination as to whether shallow aquifers (Wepo or alluvial) will be intercepted by the pits to be mined (Chapter 18). made an assessment as to: Where aquifers will be intercepted, the hydrologists have

(1) the significance of the saturated regions as aquifers; (2)

the value of the ground water to the quality of the human environment; and ( 3 ) the value of the ground water to support the postmining land use of the mined area. These analyses

indicate the portions of the alluvial and Wepo aquifers within the leasehold which may be potentially affected by mining, exhibit low yields to wells and show a water quality which is predominantly unsuitable for use as domestic, irrigation or livestock water. As such,

the portions of the aquifers within the PWCC leasehold have no importance in regards to domestic water consumption and irrigation use. In terms of supporting the postmining land

use of the area as livestock drinking water, the portions of these aquifers monitored within the PWCC leasehold yield water that is marginally suitable to unsuitable. The

above statements are based upon comparisons of the water against accepted domestic, irrigation and livestock water quality criteria (Table 1, page 11). As of 2003, only 4 of the 34 sampleable alluvial monitoring wells and 9 of the 26 sampleable Wepo monitoring wells yield water that meets all of the current livestock drinking water quality criteria.

1

Revised 11/21/03

None of the monitoring wells in either aquifer yield water that meets domestic drinking water criteria. Only 5 of the 26 Wepo monitoring wells yield water quality suitable for

use as irrigation water and these five wells exhibit such low yields they cannot be considered for irrigation use. for use as irrigation water. None of the alluvial monitoring wells yield water suitable

Surface water protection is achieved through drainage control and reclamation practices. Where spoil encroaches upon significant drainages, channel diversions have been designed and will or have been constructed to divert surface water runoff and minimize the

formation of acidic or toxic drainage or increased suspended solids (Chapter 6). Further, runoff from mined areas is and will be contained by sediment ponds (Chapter 6).

Contemporaneous restabilization (Chapter 20) and reconstruction of a nontoxic plant growth medium (Chapter 22) will also protect surface water quality from potential detrimental effects of surface water drainage.

Drainage Control and Water Quality Standards.

All runoff from lands disturbed by mining

will be routed through sediment ponds designed to contain the runoff from 10-year, 24-hour storm events plus sediment unless alternative water control structures are approved by the regulatory authority. NPDES Permit No. A20022179 has been issued for the Black Mesa and This permit contains effluent

Kayenta Mines by the Environmental Protection Agency.

limits, sampling and reporting requirements (Chapter 16) designed to protect surface water quality.

Reclamation practices also serve to protect the hydrologic balance and achieve water quality standards. The Surface Stability and Drainage System Development Plan in the section of Chapter 21 addresses the reclamation procedures

Backfilling and Grading

employed to reestablish a more stable and controlled drainage system in the reclaimed areas. through The Revegetation Plan in Chapter 23 describes procedures used to minimize erosion mulching and contemporaneous revegetation. Additionally, the Minesoil

Reconstruction

Plan in Chapter 22 describes ripping and

contour discing procedures

employed to stabilize the ground surface, promote revegetation and minimize erosion. These surface treatments, in addition to the spoil sampling program to ensure that acid and toxic materials are sufficiently buried, will minimize the chemical and sediment loads contributed to streamflows from reclaimed areas.

Revised 11/21/03

A plan for evaluating the success of reclamation practices with regard to controlling drainage and chemical and sediment loads from reclaimed areas was developed and

implemented.

The plan employed a

small watershed study

(Attachment 4, Chapter 16)

consisting of runoff plots, runoff volume, sediment and water quality samplers and flumes; monitoring water quality and persistence in 15 permanent internal impoundments (PIIS) in the N1, N2, Jl/N6, J3, and J27 mining areas (Chapter 15, Permanent Impoundment Monitoring Section); and the calibration and use of a rainfall/runoff/sediment yield model which was used to compare premining values against postmining values (EASI)

(Application for

Release of Reclamation Liability N1/N2 and 527 Interim Program Indian Lands, Black Mesa and Kayenta Mines, March 1994).

More emphasis was given to runoff plot data than the small watershed flume data when determining EASI model calibration coefficients because total runoff and sediment data for each storm event were collected and measured directly. Overall, the EASI model reasonably

reproduced comparable values to the runoff and sediment yield values measured at the small watershed plots and flumes for a range of highly variable rainfall events.

The permanent internal impoundment monitoring referenced above was conducted at all or some of the 15 pond sites from 1981 to 1999. samples from the PIIs were analyzed. During this time some 296 water quality

Excepting some early (pre-1985) fluoride, lead, TDS

and sulfate values at 3 of these impoundments (112,113 and 116), only N2-RA exceeded livestock water quality criteria and only for TDS and S04. All other PI1 water quality

data was comparable to or more suitable than baseflow and stream runoff water quality measured in the principal channels on the leasehold. During this same time period

approximately 500 monthly water level measurements at 14 of the PIIs and 2-3 years of continuous water level measurements at 5 of the PIIs were collected. The water level data

showed that reclaimed watershed runoff is sufficient enough to allow an average permanent impoundment water persistence of greater than 80 percent.

The

following conclusions were

reached from the EASI model

comparisons

of pre- and

postmine watersheds.

Drainage densities for postmine conditions are about one-half of the Pre- and postmine runoff was found to be quite similar.

premine drainage densities.

Sediment yield from reclaimed hillslopes is generally two times higher than from premine hillslopes having comparable hillslope length and gradient. However, total sediment

yields predicted from reclaimed watersheds are lower than premine watershed predictions.

3

Revised 11/21/03

This is because channels, not the hillslopes, are the primary sources of sediment in both pre- and postmine conditions; channels tend to be flatter in the postmine landscape; and the greater number of depressions in the postmine landscape capture a significant amount of the sediment which could potentially be transported out of the reclaimed watersheds. The above studies and modeling indicate the reclamation practices are performing well in regards to controlling the runoff, chemical and sediment loads leaving the reclaimed watersheds.

Restoration of Approximate Premining Ground Water Recharge Capacity. and scrapers accomplish the backfilling and grading of mined areas.

Draglines, dozers This technique

results in some compaction, but is estimated by VanVoast and Hedges (1975) to increase permeability when compared to the original stratified state of the overburden material. Permeability increases are primarily attributed to increased void volumes and segregation of particle sizes. The topsoiled surface will be contour-disked which will increase the Infiltration rates, however, are likely not Distances from the land surface to the

rainfall and overland flow infiltration.

critical to the recharge of the Wepo aquifer.

saturated portions of the Wepo aquifer and the limited annual precipitation preclude significant rainfall and snowmelt recharge other than in burn and clinker or highly fractured areas. following mining. These areas are found adjacent to, rather than in the coalfields

The time period necessary for the spoil material to become resaturated and for final ground water flow patterns to be established in areas where pits have intersected portions of the Wepo aquifer depend upon the resultant porosity and permeability of the replaced spoil material. The resaturation may take from a few years to 100 years to occur, but the The maximum drawdowns will occur in

magnitude of this impact will be small (Chapter 18).

the pits themselves and are estimated to be approximately 60 feet and 45 feet for the J19/20 and 5-16 pits, respectively. Following the resaturation period, ground water levels

will recover to near premining levels.

Water Rights and Alternative Water Supplies.

The State of Arizona is proceeding with the

adjudication of water rights in the Little Colorado River Basin, which includes Black Mesa. This adjudication is still in the process of being finalized. Once the

adjudication is final, it is believed Peabody's water use will be a prescribed use based on the allotments to each Tribe. Peabody's use of water on Black Mesa for the mining

Revised 11/21/03

operations is authorized in the three mining lease agreements (Lease Nos. 14-20-0603-8580, 14-20-0603-9910 and 14-20-0450-5743) with the Tribes. The mining lease agreements clearly

state that Peabody may use that amount of water necessary for its mining operations, including the transportation by slurry pipeline of coal mined from the lease areas.

At this time, the only documented local usage of the Wepo or alluvial aquifers is in the immediate vicinity of the leasehold at three wells: 41-405; 4K-389; and 4I<-380 (Chapter 17, Pre-existing Wells and Springs). Though PWCC's Wepo and alluvial monitoring well

network suggests there is small likelihood of a Wepo or alluvial well being suitable for use as livestock drinking water, these three wells are being used for livestock water because they are also partly screened in the underlying Toreva aquifer. The completion

information for well 4K-380 states it is partially completed in the Toreva and the completion depths for wells 4K-389 and 4T-405 suggest they are also partially open to the Toreva aquifer. All three wells are located off lease (two of them are at least 2 miles Because the Toreva aquifer is of better quality than the Wepo

south of the leasehold).

aquifer, this would account for how three wells adjacent to the leasehold could be of suitable quality for livestock use when so few of the monitoring wells on the leasehold meet livestock drinking water criteria.

Theoretical pit

pumpage drawdowns in the Wepo

aquifer could potentially reduce the Potential pit pumpage drawdowns

available height of water in well 4K-389 by 25 percent.

in wells 4T-405 and 4K-380 are within the range of natural shallower aquifer water level fluctuations. The windmills located on the PWCC leasehold are completed entirely in lower

aquifers and won't be affected by pit pumpage drawdowns in the shallower Wepo aquifer.

Regardless of the potential for mining impacts to any well, PWCC has made available to all local residents in the area of the leasehold water of domestic drinking water quality at standpipes located near the N6 and N14 mining areas. Navajo aquifer and is available on a 24-hour basis. The water supplied is from the

Monitoring Plan

Introduction.

In addition to the activities designed to minimize disturbances to the

hydrologic balance discussed above, ground and surface water monitoring plans have been developed to assess the impacts to the hydrologic system identified in Chapter Probable Hydrologic Consequences. The results of the monitoring plan have and will 18,

continue to be employed to support the PHC conclusions that disturbances to the hydrologic balance will be minimal and that the potential uses of the ground and surface water systems affected by mining will not be changed.

The parameters observed at each monitoring site as well as sampling and monitoring frequencies are documented in Chapter 16, Hydrological Monitoring Program. Table 2 (page

12) shows which monitoring sites are utilized to address each of the probable hydrologic consequences discussed in Chapter 18. The following monitoring plan discussions will

address how the monitoring data or programs will be used to determine impacts to the hydrologic balance.

Ground Water Monitoring Plan.

Wepo and Alluvial Aquifer Quantity and Quality .

Not all alluvial and Wepo monitoring

wells are projected to be impacted in terms of water levels and/or water quality as a result of mining areas intercepting the Wepo aqu ifer. Only portions of the N2, N7, N10,

N99, Jl/N6, J16, J19 and J21 mining areas have been determined to intercept the Wepo aquifer. This determination is based on documented pit inflows in those areas already

mined and on comparisons of the Wepo/alluvial aquifer potentiometric surface with bottom

of pit contours for those areas remaining to be mined.

From

the

pit

inflow

calculations

presented

in

Chapter

18,

Probable

Hydrologic

Consequences, theoretical drawdowns in the Wepo and alluvial aquifers were determined for Figures 1 and la in Chapter 18. Since all wells exhibit water level fluctuations owing to

climatic changes and water quality sampling stresses, only those wells within the zone of
>5

feet

of

drawdown

on

Figure

1 are

considered

likely

to

be

affected by

mining

interception of the Wepo aquifer.

Prior to 2001 only those wells within this > 5 ft. zone

were evaluated in discussions of water level monitoring, while all other wells were considered to be background wells. In July 2001, PWCC rece~ved the first of several

approvals from OSM to modify its ground water monitoring program (OSM, 2001a; OSM, 2001b; OSM, 2002). Collectively, these approvals allowed for the removal (abandonment) of 26

alluvial, spoil and Wepo monitoring wells; idling twelve additional alluvial and Wepo monitoring wells; and for reducing frequency of monitoring at all remaining wells. Owing

to these revisions, and starting with the 2001 Reclamation Status and Monitoring Report for the Black Mesa and Kayenta Mines, a previous distinction made between potentially affected versus unaffected wells was dismissed. 6 At present every alluvial, spoil or Wepo Revlsed 11/21/03

well is considered unaffected until such time as water level drops beyond historic ranges, or persistent trends, shifts, or abrupt changes in either water levels or water chemistry become evident. Several of these wells have pre-disturbance baseline water level data In the rest of

against which future water levels can be compared for impact assessments.

the cases, current water levels can be compared against 5 to 10 year historic water level ranges. To date only Wepo wells 53, 62R, former Wepo well 62 and former alluvial wells 74

and 75 have shown clear evidence of mining induced drawdowns.

The approach to evaluating the Wepo and alluvial monitoring wells for mining-induced water quality impacts is similar to the water level approach in that the analysis is closely linked to the wet pits and the Wepo/alluvial potentiometric surface. differs is water quality impacts can only occur downgradient Where the approach of

(in the direction

decreasing potentiometric head) from the wet pits, and can only occur after the pits have been reclaimed and ground water levels have reestablished so ground water flow through the mining areas can return to what it was prior to mining. Hydraulic characteristics for

each aquifer (Chapter 15, Attachments 9 and 14) were evaluated to determine which wells downgradient from the wet pits would have potential water quality impacts. The hydraulic

conductivities measured during pumping tests in each aquifer are low with average Wepo values being lower than the average alluvial values. In order to determine minlng-induced

changes in the water chemistry at the Wepo, alluvial, and spoil monitoring wells, trend analyses will be performed for sodium, bicarbonate, sulfate, and total dissolved solids concentrations measured at these wells. Persistent trends of increasing concentrations of

two or more of these major ions will suggest that mining impacts to the water quality are occurring. Also, water type changes or shifts on trilinear diagram plots of the water

chemistry for these wells will suggest mining impacts to the water quality.

Navajo Aquifer Quality and Quantity.

Water level changes in the Navajo well bore holes on

the leasehold are of little direct use in assessing drawdown in the N-aquifer as they are significantly influenced by well efficiency and pumpage rate changes. Regional water

level monitoring of the N-aquifer by the U.S. Geological Survey (USGS) in conjunction with periodically revised flow model runs will be utilized to assess the separate impacts from Peabody and Tribal pumpage on N-aquifer water levels. will provide continuous pumpage data As input to the model runs, Peabody located on the

for the eight N-aquifer wells

leasehold.

Navajo aquifer water quality changes will be compared against five-year ranges determined

7

Revised 11/21/03

from Peabody monitoring data.

Significant increases in TDS, chloride and sulfate will The USGS

suggest higher amounts of induced recharge from the overlying D-aquifer system.

monitoring program will be relied on to measure water quality changes in regional Naquifer wells. Annual progress reports from the USGS typically compare current chemical

concentrations against average values determined over the period of sampling record. Significant increases in parameter levels over the long-term averages will be considered to suggest changes resulting from increased leakage of poorer quality D-aquifer water.

Spring Flows and Quality.

Spring flows and quality changes on the leasehold will be Significant by climatic

compared to ranges developed from the five-year baseline-monitoring database. flow or quality deviations from the five-year ranges not explainable

fluctuations will be considered suggestive of impacts from mining. and water quality will be monitored by the USGS.

Regional spring flows

Significant deviations from average

values for the period of record will be considered suggestive of impacts from Trlbal and Peabody N-aquifer pumpage.

Surface-Water Monitoring Plan.

Streamflows and Stream Water Quality.

Between 1980 and 2001, PWCC conducted extensive

monitoring of streamflow and stream water quality in each of the major washes that cross the leasehold. These monitoring data were compiled, analyzed, interpreted and used as the

basis for a hydrologic program revision document submitted to OSM entitled "Justification of Monitor and Monitoring Frequency Reductions at the Black Mesa and Kayenta Mines, Arizona" (PWCC, 2001a). OSM approved this revision to Chapter 16 in several stages, (refer to OSM

resulting in significant changes to the surface-water monitoring program (2001a, 2001b and 2002a) and PWCC (2001b) for details).

Included in this revision was the

abandonment of eight stream-monitoring stations; the idling of one additional stream station; discontinuance of channel geomorphology monitoring and; discontinuance of

sediment monitoring at all remaining stream monitoring sites. surface-water monitoring network on Black Mesa conslsts of stations that monitor for water quantity and quality.

As of July 2002, the PWCC four down-gradient stream

Since many factors influence streamflows and stream water chemistry on the leasehold, comparisons with five-year averages (as is done with well water chemistry) may not prove meaningful. Instead, trending analyses is utilized to detect changes or trends in

surface-water chemistry that may suggest mining impacts. Consistently decreasing flows or
8

Revised 11/21/03

increasing concentration levels, not

associated

with

climatic

fluctuations or

local

phreatophyte development, will be considered to suggest mining impacts. monitoring will be performed by the USGS.

Regional baseflow

Consistent reductions in baseflow at Moenkopi,

Laguna Creek and Mexican Water will be interpreted as impacts from Tribal and Peabody pumpage, excepting periods of drought.

Reclaimed Area Runoff, Water Quality and Sediment Yields.

Analyses for potential impacts

of reclaimed areas on streamflows and stream water quality have been conducted as part of the small watershed studies, the permanent impoundment studies and the EASI runoff and sediment yield modeling which has been described in the previous section on Drainage Control and Water Quality Standards. runoff plot The small watershed data and EASI model runs showed: higher on reclaimed areas; total

(hill slope) sediment yield data was

watershed runoff volumes were comparable between reclaimed and undisturbed areas; and total watershed sediment yields were higher from undisturbed areas. Monitoring of

permanent impoundments showed reclaimed area runoff for a range of watershed sizes was good (some water persistence 80 percent of the time in the internal impoundments) and

overall runoff water quality was equal to or better than baseflow and runoff in the principal channels on the leasehold.

Literature Cited

VanVoast, W.A. and R.B. Hedges.

"Hydrologic Aspects of Strip Coal Mining in Southwestern Montana Bureau of Mines

Montana - Emphasis One Year of Mining Near Decker, Montana." and Geology Bulletin 93. 1975.

Peabody Western Coal Company.

PWCC Application for Reduction in Monitoring, Chapter 16, Document submitted to

Hydrologic Monitoring Program Permit Revision, Permit AZ-0001D. OSMRE on March 5, 2001.

Enclosure to this document entitled: "Justification of Monitor 2001a

and Monitoring Frequency Reductions at the Black Mesa and Kayenta Mines, Arizona".

Peabody Western Coal Company. Permit AZ-0001D".

"Chapter 16 Phase 2 Monitoring Reduction Permit Revision, Enclosure to this

Document submitted to OSMRE on November 6, 2001.

document entitled: "Justification of Phase 2 Monitor and Monitoring Frequency Reductions at the Black Mesa and Kayenta Mines, Arizona". 2001b.

OSMRE .

"Permit

Revision

AZOOOlD/Chapter

16,

Hydrologic

Monitoring

Program/Kayenta 2001a.

Mine/OSM Project AZ0001D-1-70".

Document received by PWCC on May 4, 2001. 9

Revised 11/21/03

OSMRE .

"Permit

Revision

AZOOOlD/Chapter

16,

Hydrologic

Monitoring

Program/Kayenta 2001b.

Mine/OSM Project AZ0001D-1-70".

Document received by PWCC on July 11, 2001.

OSMRE.

"Chapter 16, Hydrologic Monitoring Program Phase 2 Monitoring Reduction/Kayenta Document received by PWCC on July 24, 2002. 2002a.

Mine/OSM Project AZ0001D-1-84".

Peabody Western Coal Company. Mesa and Kayenta Mines.

2001 Reclamation Status and Monitoring Report for the Black

Revised 11/21/03

Table 1 Recommended Numeric Water Quality Standards for Domestic, Livestock, Agricultural Irrigation, and Ephemeral Aquatic Water Uses Chemical Parameter Alkalinity, mg/l Aluminum, mg/l Arsenic, ug/l Antimony, ug/l Bicarbonate, mg/l Barium, ug/l Beryllium, ug/l Boron, ug/l Cadmium, ug/1 Calcium, mg/l Chloride, mg/l Chromium, ug/l Cobalt, ug/l Copper, ug/l Cyanide, mg/l Fluoride, mg/l Gross Alpha Iron, mg/l Lead, ug/l Magnesium, mg/l Manganese, mg/l Mercury, ug/l Molybdenum, ug/l Nickel, ug/l Nitrate, mg/l Nitrite, mg/l pH, s.u. Potassium, mg/l Radium 226, pCi/L Radium 228, pCi/L Selenium, ug/l * Selenium, ug/l * * Silica, mg/l Silver, ug/l Sodium, mg/l Sulfate, mg/l Solids, Dis., mg/l Thallium, ug/l Uranium, mg/l Vanadium, ug/l Zinc, mq/l
T Total Analyses
TR Total Recoverable Analyses mg/l Milligrams per liter ug/l Micrograms per liter s.u. Standard Units All standards are dissolved, unless indicted otherwise. These standards are taken from a variety of sources, including: Navajo Nation Env. Protection Agency, Primary Drinking Water Quality Regulations (2001) - most domestic standards and Navajo Nation Draft Surface Water Quality Standards (1999) - - most livestock, irrigation and aquatic standards Hopi Tribe, Draft Hopi Water Quality Standards (1998) - - livestock pH standard National Academy of Science, Water Quality Criteria (1974, 1980) - - numerous standards United States Env. Protection Agency, National Primary and Secondary Drinking Water Standards (2001) - - domestic F and A1 Montana Dept. Health and Env. Sciences (see Botz and Pederson. 1976) - - numerous standards Arizona Dept. of Env. Quality, Numeric Water Quality Standards (2002) - - livestock, irrigation and aquatic standards) Wyoming Dept. Env. Quality (1980) - - livestock chloride and sulfate Shaded values are secondary Domestic standards, as are the lower limits for Copper and Fluoride. Values in parentheses are levels at which adverse effects have been known to occur, according to Botz and Pederson (1976) Selenium standard in the presence of
+*
c/=

Domestic

Water Use St ldard Irrigation Livestock
170 5.0 200

Aquatic

Acute-Cd

16 1000

Acute-Cu
41T 1.5 (0.2) 100 500 10 1 OTR

Acute-Pb
(300) 1.0

2.4TR Acute-Ni

6.5-9.0 (50)

Acute-Ag
(500)

700

Acute - Zn
Revised 11/21/03

500 mg/l of sulfate.

Selenium standard in the presence of

>

500 mg/l of sulfate.

Acute metals standards are derived from complex equations utilizing lab-determined hardness values, and are not given here. Refer to "Footnotes to the Numeric Surface Water Quality Standards". Navajo Nation Draft Surface Water Quality Standards (1999).

X

X

l

X

X

X

X

X

I

I

I

I

X

X

X

X

X

X

X

X

I

I

I

I

I

l

l

1

1

1

1

1

I

I

I

I

l

X

X

l

X

X

X

X

X

X

l

X

X

X

X

X

X

X

l

X

1

1

x

1

1

1

1

1

U

N

U m

5
4

m
C

.rl 0

a m

OI
C 0

w
m

OI

a
a

5

2o w3
4
4

' -4 3 U L

= ,.-

W P C

.mu, 0

z m

a m >u m c

h u E 0m w a LJ m u
%

am N

u c
UI

0 ill

U 4 ( . ) LO

m

Y E

a tl . I a)

TABLE 2 ,&ont.)

Monitoring Sites and Programs Utilized to Substantiate Significance Findings of Chapter 18, Probable Hydrologic Consequences
A l l u v i a l Well M o n i t o r i n g S i t e s 105R 106R 108R 165 168

95 I n t e r r u p t i o n o f Ground W a t e r Flow a n d Drawdowns
-

98R

99R

lOlR

104R

169

170

172

180

-

-

-

-

Removal o f L o c a l W e l l s a n d S p r i n g s by M i n i n g C o n t a i n m e n t a n d D i s c h a r g e o f P i t I n f l o w Pumpage I m p a c t o f R e p l a c e d S p o i l M a t e r i a l on Ground Water Flow a n d Recharge C a p a c i t y
X
-

-

X

X
X X

X X X

X X X

X X
X

X X X

X
X X

X X X

X

X

X

X

I m p a c t o f R e p l a c e d S p o i l o n Ground Water Q u a l i t y
X

X X

X

X

X

X

I n t e r c e p t i o n o f Wepo R e c h a r g e t o t h e A l l u v i a l A q u i f e r T r u n c a t i o n o f A l l u v i a l A q u i f e r s b y Dams
-

X

X

X

X

X

-

X X X

E f f e c t s o f Changed Wepo A q u i f e r R e c h a r g e Water Q u a l i t y on t h e Alluvial Aquifer
X

X

X
-

X

X

X

X

X

X

X

X

M i n i n g I n t e r r u p t i o n o f S p r i n g Flow I m p a c t o f Peabody N a v a j o W e l l f i e l d Pumpage on R e g i o n a l k l a t e r L e v e l s a n d S t r e a m a n d S p r i n g Flow

-

-

+
W

E f f e c t s 3f I n d u c e d Leakage o f P o o r e r Q u a l i v ' J a t f r From t h e Overlyirt.3 D - a q u i f e r S y s t e m o n t h e N - a q u i f e r > ; a t e r Q u a l i t ; , I m p a c t zf Cams, S e d i m e n t Ponds a n d Impoundmznrs rr: F,unoff and Charloel C h a r a c t e r i s t i c s I m p a c t c f Lams, S e d i m e n t Ponds and Impoundmtn?: Users I m p a c t o f &as, Quality r;r. k : < n s t r e a m
-

-

-

-

S e d i m e n t Ponds a n d impound men^^ or, S t r e a m Water

I m p a c t c f S t r e a m C h a n n e l D i v e r s i o n s o n Zhar.i.r! C h a r s : t e r i s t i c s a n d Runcff : i a t e r Q u a l i t y

. E f f e c t s i Cul.:erts i l a t e r Qu2lit;:

a t Road C r o s s i n g s on S r r c m F%u;i?ff a n d and

-

E f f e c t s zf Run3ff From R e c l a i m e d A r e a s on t i , ? ?:~a;!- ic: Q u a l i t y cf S t r e a m f l o w

Removal c i E r e - e r : i s c i n g

S u r f a c e Water S t r t i - :

.i: c s

-

Revised 1 1 / 2 1 / 0 3

X

I

I

X

X

I

I

X

X

I

I

X

X

1

1

X

X

I

I

X

X

I

I

X

X

I

1

1

X

I

I

I

X

I

I

X

X

X

X

X

X

X

l

X

X

X

l

X

X

X

X

X

X

X

l

X

X

X

l

X

C 0
U h
.rl 4

m
C

4

m
U

-4 0

Oi
U a,

a, OI d
C

3

m

0
01 a1

w

OI

m

a3
u 4

m I :
d
U

aL

52

w

w a,
-4

2

a, .rl

01 c

4

2 0 4 3
s

3

"5
-n m m E

m m u

z
a,

U

> z 'a
>

U U

u -4 a, w
01 tT C 3

m m
a1

uu 0 c

ma: m

n

U3

a4 wul
w > 0 w
U 4

" -4 (

0
LO

>

U-l

*

u

a :

U 4

m a,

W i 'CI a)
W U

aU
H

E m

3

TABLE 2 {Cont.)
Monitoring Sites and Programs Utilized to Substantiate Significance Findings of Chapter 18, Probable Hydrologic Consequences

Wepo Well Monitoring Sites
51 52 53 54 55 56 57 58 59 60 61 62R

65

66

67

68

178

Interruption of Ground Water Flow and Drawdowns Removal of Local Wells and Springs by Mining Containment and Discharge of Pit Inflow Pumpage Impact of Replaced Spoil Material on Ground Water Flow and Recharge Capacity Impact of Replaced Spoil on Ground Water Quality Interception of Wepo Recharge to the Alluvial Aquifer Truncation of Alluvial Aquifers by Dams Effects of Changed Wepo Aquifer Recharge Water Quality on the Alluvial Aquifer Mining Interruption of Spring Flow Impact of Peabody Navajo Wellfield Purnpage on Regional Water Levels and Stream and Spring F l o ~
Cn
P

-

X
-

X

X

X

X

X

X

x

X

X

X

X

X

X

X

-

-

-

-

X X X X

X X

-

X

X

X

X

X

X

X

X

X

Effects of Induced Leakage of Poorer Qualit,; i,:ster From the Orerl;,ing D-aquifer System on the Id-aquifzr I1at=_r Qualit; Irnpizt sf Dams, Sediment Ponds and Irnpoundrnen! 5 r l Runoff and Channel Characteristics Impact of Pams, Sediment Ponds and Irnpoundmer:t% cl r Downstream Users Impact of Darns, Sediment Ponds and Irnpoundmenl.. I:; Stream Flater Quality Impact of Stream Channel Diversions on Chanr:ei Characteristics and Runoff Water Quality Effects of Culverts at Road Crossings cn Sticlzi Funcff and Water Qualit;~ Effects of Runoff From Reclaimed Areas sn ti.. .:.!ar.tl t; and ,2ualit:! cf Streamflo:~: Ths Impact sf the Fieclamation Plan c;; cite S t .:i..l it? :f Reclaimed Areas and he Reestablishment of Cr-i-.sne Systems Removal of Pro-existing Surface Water Struct'i:.r.+

Revised 11/21/03

TABLE 2 (Cont.)

Monitoring Sites and Programs Utilized to Substantiate Significance Findings of Chapter 18, Probable Hydrologic Consequences

Navajo Well Monitoring Sites
7 7
II 5

6
-

7

FI

9

Interruption of Ground Water Flow and Drawdowns Removal of Local Wells and Springs by Mining Containment and Discharge of Pit Inflow Pumpage Impact of Replaced Spoil Material on Ground Water Flow and Recharge Capacity Impact of Replaced Spoil on Ground Water Quality Interception of Wepo Recharge to the Alluvial Aquifer Truncation of Alluvial Aquifers by Dams Effects of Changed Wepo Aquifer Recharge Water Quality on the Alluvial Aquifer Mining Interruption of Spring Flow Impact of Peabody Navajo Wellfield Pumpa3e on Regional Water Levels and Stream and Spring Flow Effects of Induced Leakage of Poorer Quality Clater From the Overlying D-aquifer System on the N-aquifer Water Quality Impacts of Cams, Sediment Fonds and Irnpcun3ments on Runoff and Channel Characteristics Impact of Dams, Sediment Fonds and Imp-,undments cn Do;.;nstream Users Impact of Dams, Sedlment Ponds and Impzundmer~ts on Stream Water Quality Impact of Stream Channel Diversions or, Channel Characteristics and Runoff Water Quality Effects of Culverts at Road Crossings sn Stream Runoff and Water Quality Effects of Runoff From Reclaimed Ars2s cn the Quantit; and Quality of Str?amflox Th? Impact cf the Reclamaticn Plan cr sh? Stability of Reclaimed Areas and the Reestablishment ?f Craina-je Systems Remo7:al of Ere-ezisting Surface ?!ate: jcructures

Revised 11/21/03

TABLE 2 (Cont.)

Monitoring Sites and Programs Utilized to Substantiate Significance Findings of Chapter 18, Probable Hydrologic Consequences
Stream Monitoring Sites 25 26 34 155
-

15 Interruption of Ground Water Flow and Drawdowns Removal of Local Wells and Springs by Mining Containment and Discharge of Pit Inflow Pumpage
-

91

Spring Monitoring Sites 92 111 147 151

191

Local Springs

-

X

X

X

-

-

X

X

-

-

Impact of Replaced Spoil Material on Ground Water Flow and Recharge Capacity Impact of Replaced Spoil on Ground Water Quality Interception of Wepo Recharge to the Alluvial Aquifer Truncation of Alluvial Aquifers by Dams Effects of Changed Wepo Aquifer Recharge Water Quality on the Alluvial Aquifer Mining Interruption of Spring Flow
-

X

X

X

X

-

X

X

-

-

X

X

r
4

Impact of Peabody Navajo Wellfield Pumpage on Regional Water Levels and Stream and Spring Flow Effects of Induced Lealta3e of Poorer Quality Watar Frsm the Overlying Daquifer System on the N-aquifer P!ater Quality Impact of Dams, Sediment Fonds and Impoundments on R!lnoff and Channel Characteristics Impact of Dams, Sediment Pcnds and Impoundments cn Gc;,~stream Users Impact of Dams, Sediment Ponds and Impoundments on Stream Water Quality Impact of Stream Channel Diversions on Charmel Char-5-teristics and Runoff Water Quality Effects of Culverts at Road Zrossings on Stream F u : f .nf and \,laterQuality

X
X X X X
K

-

-

-

X

X X
Y

X X X

X X

-

X

-

X

-

-

<
X

X X

X
X

-

Effects of Runoff From Recliimed Areas on the Quanti !:.' and Quality of Streamflo:.i The Impact of the iieclamati?n Plan =n the Stzhilit.. ;f Recl.aimed Areas and the Reestablishment of Driinaqe 3 s s s :tm

x

<

X

-

R e v i s e d 11/21/03

Monitoring Sites and Programs Utilized to Substantiate Significance Findings of Chapter 18, Probable Hydrologic Consequences

S p o i l Well M o n i t o r i n g S i t e s 161 Future Wells I n t e r r u p t i o n o f Ground W a t e r Flow a n d Drawdowns Removal o f L o c a l W e l l s a n d S p r i n g s by M i n i n g
-

Permanent

Impoundments Permanent I n t e r n a l

Other I n t e r n a l

-

C o n t a i n m e n t a n d D i s c h a r g e o f P i t I n f l o w Pumpage I m p a c t o f R e p l a c e d S p o i l M a t e r i a l o n Ground Water Flow a n d R e c h a r g e C a p a c i t y I m p a c t o f R e p l a c e d S p o i l on Ground Water Q u a l i t y
X X

I n t e r c e p t i o n o f Wepo R e c h a r g e t o t h e M l u v i a l A q u i f e r T r u n c a t i o n o f A l l u v i a l a q u i f e r s by Dams E f f e c t s o f Changed Wepo A q u i f e r R e c h a r g e Water Q u a l i t y on t h e A l l u v i a l Aquifer Mining I n t e r r u p t i o n o f S p r i n g Flon r I m p a c t o f Peabod; Na-:ajc : : e l l f i e l d Pumpage s n R e g i o n c i X a t e r L e v e l s a n d S t r e a m a n d S p r i n F1%
03 -

-

E f f e c t s o f I n d u c e d Lsei:;?s 2 F F s o r e r Q u a l i t y i i a t s r From t h e O-:erlying D - a q u i f e r S y s t e m or, e h e $1-;quifer V!atsr Q u a l i t ; . I m p a c t o f Dams, S e d i m e n t Fznds a n d Impoundments on Runoff a n d C h a n n e l Characteristics I m p a c t o f Dams, Sedimsrit F c r i J c and Impoundments on D s i n s t r e a m U s e r s I m p a c t o f Dams, S e d i m e n t Fzr:ds a n 3 Impoundments on Scream i i a t e r Quality I m p a c t o f S t r e a m Che:l;~+l C i - : s r s i o n s R u n o f f Water Q u a l i t y E f f e c t s of Cul.rsrt5 r Qualit;'
F:s:-t
,

on C h a n n s l C h a r a z t e r i s t i z s and

:rcsir!gs
.

c n S t r e a m R u n c f f and i l a t s r

E f f e c t s o f Runoff Streamflo-,i
E':z:r.

P.s.:l -.:ass .-lrea- on t h e Q u a n t i r ; - s n d Q u a l i t y o f
-

Fll; on t h s S t a b i l i t y sf R e c l a i m e d A r e a s The I m p a c t o f t h s h r rla:n;r;cr, a n d t h e R e e s t a b l i s h ~ s n t r , i ;:,ralnage S y s t e m s

Removal o f P r e - e : : i s t i n q

S c r f a c e Water S t r u c t u r e s

X

X

Revised 11/21/03

TABLE 2 (Cont.)

Monitoring Sites and Programs Utilized to Substantiate Significance Findings of Chapter 18, Probable Hydrologic Consequences
Regional USGS NAquifer, Stream & Spring

Local Well Inventory Interruption of Ground Water Flow and Drawdowns Removal of Local Wells and Springs by Mining Containment and Discharge of Pit Inflow Pumpage Impact of Replaced Spoil Material on Ground Water Flow and Recharge Capacity Impact of Replaced Spoil on Ground Water Quality Interception of Wepo Recharge to the Alluvial Aquifer Truncation of Alluvial Aquifers by Dams Effects of Changed Wepo Aquifer Recharge Water Quality on the .>.lluvial Aquifer ilicing Interruption of Spring Floir
r

NPDES Ponds

PWCC 3-D Flow Model

Monitoring of Channel Characteristics

Small Watershed Studies

impact of Peabody Navajo wellfie13 Pumpage on Regional Water Levels 2nd Stream and Spring Flow -. - . :.i:fcts cf Induced Leakage of Fssrrr Qualit;' Water From the O : , f r i , i ; ' g -2qliiffr S;,stem on the N-aquifer :later Quality
:mpact of Dams, Sediment Ponds 3rd Impoundmen~son Runoff and Cl-:;:-.i.,?i ':t!zracteristics

,mpact of Dams, Sediment Ponds and Impcundments on Do-dnstream rJseL5
,;:c?

::T~~act Dams, Sediment Ponds an3 Impoundments on Stream water of
2r.j

r!zFact of Stream Channel Diversisns on Channel Charactoristics iur.cff Water Quality
..";siit:
. - .:-ts .. . r = .... .. . L --LS

3f Culverts at Road Crcss:nqs

3n Stream Runoff an3 ilats!?
f

. . .. _ =;ci?x

. .-

zf Runoff From Reclaimed Arfas sn tt~e Quantity and Qualib.

, ---=-. . . I:,,,.--L of the Reclamation S i r , sn th? Stabilit;. of RezliimtJ ' : . + z s 2nd tte Reestablishment A fraina2e Systems

Revised 11/21/03

CHAPTER 2 0

RECLAMATION SCHEDULE

CHAPTER 20

INDEX
Page

Introduction Timing of Reclamation Activities Projected Reclamation Schedules Abandonment of Operations

1 1 4
14

LIST OF FIGURES

page
Figure 1 Reclamation Timetable
2

LIST OF TABLES

page
Table
1

Projected Reclamation Schedule for the J-7 Coal Resource Area
5

Table

2

Projected Reclamation Schedule for the N-6 Coal Resource Area
6

Table

3

Projected Reclamation Schedule for the N-10 and
N-11 Coal Resource Areas

Table

4

Projected Reclamation Schedule for the J-19 Coal Resource Area

Table

5

Projected Reclamation Schedule for the J-21 Coal Resource Area

Table

6

Projected Reclamation Schedule for the J-23, and N-99 Coal Resource Areas

Table

7

Projected Reclamation Schedule for the 5-2, J-4, and J-6 Coal Resource Areas

Table

8

Projected Reclamation Schedule for the J-8, J-9, and J-10 Coal Resource Areas

Table

9

Projected Reclamation Schedule for the J-14, J-15, and J-28 Coal Resource Areas

Revised 11/21/03

CHAPTER 20

RECLAMATION SCHEDULE

Introduction

This

chapter

presents

a

timetable for each major for the coal

phase

of

the reclamation plan and lands under

and

projected

reclamation

schedules

resource

areas

support

facilities and structures.

Additional information regarding the timing of reclamation

activities may be found in the chapters that discuss the components of the reclamation plan. For example, seeding periods are discussed in Chapter 23, Revegetation Plan. Until

facilities such as roads and sediment ponds are approved as elements of the postmining land use plan, Peabody Western Coal Company (PWCC) must develop schedules for the reclamation of all disturbed lands.

Drawings 85210 (Mine Plan Map) and 85360 (Jurisdictional Permit and Affected Lands Map) identify the limits of disturbance as of December 16, 1977 (pre-SMCRA), interim program, and permanent program lands.

Timing of Reclamation Activities

A generalized timetable of reclamation activities is shown in Figure 1. outlines the sequence and timing of each major phase of reclamation. precisely specify the timing of each reclamation phase

The timetable

It is not possible to area for the

in each mining

following reasons:

(1) variables such as customer demand for coal, labor strikes, coal

quality, overburden characteristics and manpower and equipment availability affect the rate of progress of mining activities; and (2) variables such as manpower and equipment

availability, delays

weather conditions, the availability of materials,

laboratory analytical

and the rate of mining advance affect the progress of grading, topsoiling and The reclamation process is only as fast as the rate of

seeding in each mining area.

production - hence, spoiling of material and the amount of acres graded, topsoiled, and revegetated each year will vary depending on where and when the bottom seam of coal was mined within the pit and within the permit area. Once the spoil piles are graded, the

reclamation sequence will occur in accordance with Figure 1 and as described in Chapter 22, 23 and 26.

Revised 02/28/00

Figure 1 Reclamation Timetable

Sequence of Activities Jan Feb Mar Apr May

Month Jun
Jul

Aug

Sep

Oct

Nov

Dec

Sedimentation Pond Construction Linear Detention
&

------------------

----

Filtering Structures (Minor Disturbance Areas) Site Clearing Topsoil Salvage Blasting Overburden Removal Coal Removal Backfilling and Grading Topographic Manipulation

-----------

-----

---------------------

------------

------------

-----------

- - - - ---

Measures Used in Conjunction w/Diversions Conveyances Topsoil Redistribution,
&

Overland

----------------------

- -- - -- - - - --- -

Graded Spoil Sampling, Contour Terrace Construction Spoil or Soil Surface Mechanical Manipulation Measures

-------------

------

Seeding/Vegetation Measures --------------Mulching Key Habitat Area Planting Fencing Maintenance
&

-----------------

---------------

------------------ - - - - --

-----------

Management

Notes: -Operations performed during periods indicated.

Primary revegetation season

------ Operations performed, weather permitting. Secondary revegetation season.

2

Revised 02/28/00

Sedimentation

pond

construction,

or

construction of

linear

detention

and

filtering

structures is completed prior to any other surface disturbances.

These activities insure

sediment control and protection of the hydrologic system (Chapters 6 and 261.

Clearing of woody or other materials which could interfere with topsoil removal, or potentially contaminate topsoil is performed immediately prior to given area. topsoil removal in a

Site clearing and topsoil salvage operations (Chapter 22) are typically These activities may be conducted in other months if

conducted from March to November.

mining conditions warrant and weather conditions permit.

Following coal removal, backfilling and grading activities, as described in Chapters 21 and 26, are conducted. These activities are performed throughout the year. They include

manipulation of the landform within the confines of approximate original contour to improve the runoff characteristics of the reclaimed landscape.

During and after the completion of rough grading, the appropriate data is collected to design and construct the postmining diversions and overland water conveyance systems (main reclamation channels and downdrains). reclamation process. The designs are installed during the course of the

These procedures are detailed in the Surface Stabilization Plan

(Chapter 26), and are typically conducted from March through November.

Topsoil material redistribution, the associated graded spoil suitability determinations (Chapter 221, and the construction of contour terraces follow the same timetable as salvage operations. If ground and weather conditions permit, topsoil material

redistribution may be conducted in months other than those indicated in the reclamation timetable (Figure 1) .

Mechanical manipulation of the spoil and topsoil is conducted following the redistribution of the topsoil material. These activities primarily entail deep ripping and contour These operations

furrow disking and are described in detail in Chapters 21, 22, and 26.

are performed from March through October, or at other times when weather and surface conditions permit.

Seeding and mulching of topsoiled arees will mostly be conducted during the primary seeding season following topsoil redistribution and mechanical manipulation, weather

Revised 02/28/00

permitting.

Therefore,

the

schedule

for

these

activities

parallels

the

topsoil

redistribution and surface mechanical manipulation schedule.

Seeding and mulchlng may be

conducted during the secondary seeding season, weather and ground conditions permitting. Revegetation activities are discussed in Chapters 23 and 26.

Fence construction is performed throughout the year. inclement weather.

Construction is interrupted only by

Maintenance and management activities are conducted throughout the year. these activities is dependent upon the specific activity. of trespass livestock are conducted throughout the year.

The timing of

Fence maintenance and removal Interseeding and reseeding is
'

conducted either during the primary or secondary seeding seasons based on needed remedial work. Surface stability monitoring and remedial actions are conducted as described in

Chapter 26.

Projected Reclamation Schedules

The projected reclamation schedules for the eight coal resource areas in whlch mining and reclamation will occur during the life of operations at the Black Mesa Complex are presented in Tables 1 through 9. The projected acres disturbed, backfilled and graded,

and topsoiled and seeded for five year mine blocks, where appropriate, are included in the tables.

The projections considerations. simultaneously

of

acres graded, topsoiled, and approximately pit three

seeded are based rows are

upon

three basic rough the graded desired

First, once the

spoil become

normally to achieve

configurations

regular

postmining land configuration and grading sequences.

to effectively maintain topographic continuity between

Upon OSM approval, the number of spoils associated with irregular box haulage ramps may exceed four to facilitate

cuts, certain inside and outside curves, and grading.

Second, the point in time at which grading of specific spoils can begin is based Cycle times are dependent upon factors

upon excavation cycle times and pit configuration.

such as pit configurations, excavator performance, overburden thickness, the number and thicknesses of partings, and customer demand (see Drawing No. 85210-Mine Plan Map).

Third, once grading begins, the amount of acres graded, topsoiled, and seeded annually in a given pit approximates the acres disturbed annually; however, this will vary each year within each mine area with the pit progression and the spoil area available for

Revised 11/21/03

TABLE 1

Projected Reclamation Schedule for the J-7 Coal Resource ~ r e a '

Acres Acres Year Disturbed Acres Graded Topsoiled and Seeded

As of 01/01/2004
2004 2005

245 37 16 37 65

163 99 163 0 65

N.A. 75 252 37 65

Soil Stockpiles (2005) Ponds (2011) Black Mesa Office Complex
(2030)

198 598

198 688

198 627

Totals :

'~ccounts for topsoiled and seeded acres after 01/01/2004. See Annual Reclamation Reports for acres disturbed, graded, topsoiled and seeded prior to the above date.

Revised 11/21/03

TABLE 2

Projected Reclamation Schedule for the N-6 Coal Resource

real
Acres

Acres Year Disturbed

Acres Graded

Topsoiled and Seeded

As of 01/01/2004 2004 2005 2006 2007 2008 Scoria Pits (2030) Central Ops/Warehouse (2030) Outside Roads (2017) J-3 Airport Complex (2030) Ponds (2016) Soil Stockpiles (2010, 2016)

N.A. 179 150 50 100 166 154 133 310 21 244 45

Totals :

2267

2222

2267

'~ccounts for topsoiled and seeded acres after 01/01/2004.

See Annual Reclamation Reports

for acres disturbed, graded, topsoiled and seeded prior to the above date.

Revised 11/21/03

TABLE 3

Projected Reclamation Schedule for the N-10 and N-11 Coal Resource ~ r e a s l Acres Acres Year Disturbed Acres Graded Topsoiled and Seeded

""---p ...--

-

-----N-10 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads(Bey0nd 2010) Totals:
0 660 21 42 52 775 46 660 21
42

N.A. 660 21 42 52 775

52 821

-----N-11 Coal Resource Area----AS of 12/01/2001
12/01/2001 - 2002 2003 2004 2005 2006 2007 797 0 0 0 0 0 0 27 32 74 930 65 69 70 118 386 89 0 27 0 74 898
N.A.

76 69 70 118 386
78

Ponds (2014) Topsoil Piles (2006)
N-11 Truck Dump Fac. (2026)

27 32 74 930

Totals :

'~ccounts for topsoiled and seeded acres after 12/01/2001. See Annual Reclamation Reports for acres disturbed, graded, topsoiled, and seeded prior to the above date.

7

Revised 11/21/03

TABLE 4

Projected Reclamation Schedule for the J-19 Coal Resource

real
Acres

Acres Year Disturbed

Acres Graded

Topsoiled and Seeded

As of 12/01/2001 12/01/2001 2003 2004 2005 2006-2011 Beyond 2011 Topsoil Piles (Life of Pit) Ponds (Beyond 2011) J28 Shop and Facilities.
N8 Facilities
-

N.A. 357 105 158 134 1425 1429 118 127 273 173 100 200
--

2002

Outside Roads Conveyor

Totals:

4529

4481

4599

l~ccountsfor topsoiled and seeded acres after 12/01/2001.

See Annual Reclamation Reports

for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 01/25/02

TABLE 5

Projected Reclamation Schedule for the 5-21 Coal Resource

, real
Acres

Acres Year Disturbed

Acres Graded

Topsoiled and Seeded

AS of 12/01/2001 12/01/2001 - 2002 2003 2004 2005 2006-2011 Beyond 2011 Topsoil Piles (Life of Pit) Ponds (Beyond 2011) Scoria Pits (Beyond 2011)

N.A.
253 151
96

191 1265 1690 165 61 142

Totals :

3701

3849

4014

'~ccounts for topsoiled and seeded acres after 12/01/2001. See Annual Reclamation Reports for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 01/25/02

TABLE 6

Projected Reclamation Schedule for the 5-23 and N-99 Coal Resource ~ r e a s l

Acres Acres Year Disturbed Acres Graded Topsoiled and Seeded

----- J-23 Coal Resource Area-----

As of 01/01/2004
2006-2010

0 498 983 84 42 198 1805

0 498 983 0 42 198 1721

0 498 983 84 42 198 1805

Beyond 2010 Topsoil Piles (Life of Pit) Ponds (Life of Pit) Outside Roads (Life of Pit) Totals:

----- N-99 Coal Resource Area-----

As of 01/01/2004
2005-2010

0
767

0 767 2031 0

0 7 67 2031 112 56
0

Beyond 2010 Topsoil Piles (Life of Pit) Ponds (Life of Pit) Outside Roads (Life of Pit) Totals:

2031 112 56 0 2966

56
0 2854

2966

'~ccounts for topsoiled and seeded acres after 01/01/2004. See Annual Reclamation Reports for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 11/21/03

TABLE 7

Projected Reclamation Schedule for the J - 2 ,

J-4, J - 6 Coal Resource ~ r e a s l Acres

Acres Year
~~."v,...--~-

Acres Graded
*

Topsoiled and Seeded

Disturbed

-0 610 0 24 30 683 0 610 0 0 30 659

...------*.,

----- J-2 Coal Resource Area----As of 1 / 0 1 / 2 0 0 4 Beyond 2 0 1 0 Ponds (Beyond 2 0 1 0 ) Topsoil Piles (Beyond 2 0 1 0 ) Outside Roads (Beyond 2 0 1 0 ) Totals :
0 610 0 24 30 68 3

----- 5-4 Coal Resource Area-----

Beyond 2 0 1 0 Ponds (Beyond 2 0 1 0 ) Topsoil Piles (Beyond 2 0 1 0 ) Outside Roads(Beyond 2 0 1 0 ) Totals :

286 6
11

286 6 0 14 306

286 6 11 14 317

14 317

----- 5-6 Coal Resource Area----As of 1 / 0 1 / 2 0 0 4 Beyond 2 0 1 0 Ponds (Beyond 2 0 1 0 ) Topsoil Piles (Beyond 2 0 1 0 ) Outside Roads (Beyond 2 0 1 0 ) Totals :
0 821 17 32

0
821 17 0 41 87 9

0 821 17 32

41
911

41
911

l~ccountsfor topsoiled and seeded acres after 0 1 / 0 1 / 2 0 0 4 .

See Annual Reclamation Reports

for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 1 1 / 2 1 / 0 3

TABLE 8

Projected Reclamation Schedule for the J-8, J-9, J-10 Coal Resource ~reas' Acres Acres Year Disturbed Acres Graded Topsoiled and Seeded

----- J-8 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads(Bevond 2010) Totals : 0 269 6 11 34 320 0 269 6 0 34 309 0 269 6 11 34 320

----- J-9 Coal Resource Area-----

Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads (Beyond 2010) Totals: 11 25 314 0 25 303 11 25 314

----- J-10 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) outside Roads(Beyond 2010) Totals: 0 326 7 13 16 3 62 0 326 0 326
7

7
0 16 349

13 16 362

'~ccounts for topsoiled and seeded acres after Ol/Ol/2OO4.

See Annual Reclamation Reports

for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 11/21/03

TABLE 9

Projected Reclamation Schedule for the J-14, J-15, J-28 Coal Resource ~ r e a s l Acres Acres Year Disturbed Acres Graded Topsoiled and Seeded

----- J-14 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads (Beyond 2010) Totals:
0 755 15 30 10 810 0 755 15 0 10 780 0 755

15
30

10 810

----- 5-15 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads (Bevond 2010) Totals:
0 428 9 17 31 485 0 428
9

0 428
9

0 31 468

17 31 485

----- 5-28 Coal Resource Area-----

Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads(Beyond 2010) Totals :

674 10 27 14 725

674 10 0 14 698

674 10 27 14 725

'~ccounts for topsoiled and seeded acres after Ol/Ol/2OO4. See Annual Reclamation Reports for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 11/21/03

backfilling

and

grading.

Further, the amount of

time needed

to complete grading,

topsoiling, and seeding after mining ceases is approximately equal to the lag time between the initiation of mining and the initiation of grading. In certain circumstances, this

generalization may not apply because of the spoil material needed to achieve the designed postmining landform. For example, the backfilling and grading of box cut spoil and deep In

ramps typically requires the movement of large volumes of spoil for great distances.

conclusion, the reclamation process will proceed relative to the mining production, on an annual basis throughout the permitted area.

Abandonment of Operations

All facilities will be reclaimed unless approved as an element of the postmining land use plan. After grading, the reclaimed areas will be topsoiled or covered with suitable plant

growth medium and revegetated. Three to five years will be needed to completely reclaim all facilities and structures following the cessation of mining. Abandonment of mine

facilities will commence when the facilities are no longer required to support mining activities. The structures and equipment including foundations and sub-bases will be

removed; unless approved by the applicable regulatory authority to be reclaimed in-place. Materials having economic value will be salvaged. Materials that are not salvageable will be buried in accordance with the noncoal mine waste disposal plan as required by 30 CFR 816.89. All structure sites will be contoured to conform with the natural landform. Cut

and fill slopes which are compatible with the postmining land use and which are approved by the regulatory authority will be retained.

Revised 02/28/00

CHAPTER 20

RECLAMATION SCHEDULE

CHAPTER 20

INDEX
Page

Introduction Timing of Reclamation Activities Projected Reclamation Schedules Abandonment of Operations

LIST OF FIGURES
Page

Figure 1

Reclamation Timetable

2

LIST OF TABLES
Page

Table

1

Projected Reclamation Schedule for the 5-7 Coal Resource Area 5

Table

2

Projected Reclamation Schedule for the N-6 Coal Resource Area

Table

3

Projected Reclamation Schedule for the N-10 and N-11 Coal Resource Areas

Table

4

Projected Reclamation Schedule for the J-19 Coal Resource Area

Table

5

Projected Reclamation Schedule for the J-21 Coal Resource Area

Table

6

Projected Reclamation Schedule for the J-23, and N-99 Coal Resource Areas

Table

7

Projected Reclamation Schedule for the J-2, 5-4, and 5-6 Coal Resource Areas

Table

8

Projected Reclamation Schedule for the J-8, J-9, and J-10 Coal Resource Areas

Table

9

Projected Reclamation Schedule for the 5-14, J-15, and J-28 Coal Resource Areas

Revised 11/21/03

CHAPTER 20

RECLAMATION SCHEDULE

Introduction

This chapter presents projected

a timetable for each major phase of coal resource areas

the reclamation plan and lands under

and

reclamation schedules for the

support

facilities and structures.

Additional information regarding the timing of reclamation

activities may be found in the chapters that discuss the components of the reclamation plan. For example, seeding periods are discussed in Chapter 23, Revegetation Plan. Until

facilities such as roads and sediment ponds are approved as elements of the postmining land use plan, Peabody Western Coal Company (PWCC) must develop schedules for the reclamation of all disturbed lands.

Drawings 85210 (Mine Plan Map) and 85360 (Jurisdictional Permit and Affected Lands Map) identify the limits of disturbance as of December 16, 1977 (pre-SMCRA), interim program, and permanent program lands.

Timing of Reclamation Activities

A generalized timetable of reclamation activities is shown in Figure 1. outlines the sequence and timing of each major phase of reclamation. precisely

The timetable

It is not possible to area for the

specify the timing of each reclamation phase in each mining

following reasons:

(1) variables such as customer demand for coal, labor strikes, coal

quality, overburden characteristics and manpower and equipment availability affect the rate of progress of mining activities; and (2) variables such as manpower and equipment

availability, weather conditions, the availability of materials, laboratory analytical delays and the rate of mining advance affect the progress of grading, topsoiling and seeding in each mining area. The reclamation process is only as fast as the rate of

production - hence, spoiling of material and the amount of acres graded, topsoiled, and revegetated each year will vary depending on where and when the bottom seam of coal was mined within the pit and within the permit area. Once the spoil piles are graded, the

reclamation sequence will occur in accordance with Figure 1 and as described in Chapter 22, 23 and 26.

Revised 02/28/00

Figure 1 Reclamation Timetable

Sequence of Activities Jan Feb Mar Apr May

Month Jun Jul Aug Sep Oct Nov Dec

Sedimentation Pond Construction Linear Detention
&

------------------

----

Blasting Overburden Removal Coal Removal Backfilling and Grading Topographic Manipulation
-----------

- - - - -- -

Measures Used in Conjunction w/Diversions Conveyances Topsoil Redistribution,
&

Overland

----------------------

- - - -- - --- - - - -

Graded Spoil Sampling, Contour Terrace Construction Spoil or Soil Surface Mechanical Manipulation Measures

-------------

----------------------

Seeding/Vegetation Measures --------------Mulching Key Habitat Area Planting Fencing Maintenance
&

------------------------- -- ----

------------------

Management

Notes:

-Operations

performed during periods indicated.

Primary revegetation season.

------ Operations performed, weather permitting.

Secondary revegetation season.

2

Revised 02/28/00

Sedimentation pond

construction, or

construction of

linear

detention and

filtering

structures is completed prior to any other surface disturbances.

These activities insure

sediment control and protection of the hydrologic system (Chapters 6 and 26).

Clearing of woody or other materials which could interfere with topsoil removal, or potentially contaminate topsoil is performed immediately prior to given area. topsoil removal in a

Site clearing and topsoil salvage operations (Chapter 22) are typically These activities may be conducted in other months if

conducted from March to November.

mining conditions warrant and weather conditions permit.

Following coal removal, backfilling and grading activities, as described in Chapters 21 and 26, are conducted. These activities are performed throughout the year. They include

manipulation of the landform within the confines of approximate original contour to improve the runoff characteristics of the reclaimed landscape.

During and after the completion of rough grading, the appropriate data is collected to design and construct the postmining diversions and overland water conveyance systems (main reclamation channels and downdrains). reclamation process. The designs are installed during the course of the

These procedures are detailed in the Surface Stabilization Plan

(Chapter 26), and are typically conducted from March through November.

Topsoil material redistribution, the associated graded spoil suitability determinations (Chapter 22), and the construction of contour terraces follow the same timetable as salvage operations. If ground and weather conditions permit, topsoil material

redistribution may be conducted in months other than those indicated in the reclamation timetable (Figure 1) .

Mechanical manipulation of the spoil and topsoil is conducted following the redistribution of the topsoil material. These activities primarily entail deep ripping and contour These operations

furrow disking and are described in detail in Chapters 21, 22, and 26.

are performed from March through October, or at other times when weather and surface conditions permit.

Seeding and mulching of topsoiled areas will mostly be conducted during the primary seeding season following topsoil redistribution and mechanical manipulation, weather

Revised 02/28/00

permitting.

Therefore,

the

schedule

for

these

activities

parallels

the

topsoil

redistribution and surface mechanical manipulation schedule.

Seeding and mulching may be

conducted during the secondary seeding season, weather and ground conditions permitting. Revegetation activities are discussed in Chapters 23 and 26.

Fence construction is performed throughout the year. inclement weather.

Construction is interrupted only by

Maintenance and management activities are conducted throughout the year. these activities is dependent upon the specific activity. of trespass livestock are conducted throughout the year.

The timing of

Fence maintenance and removal Interseeding and reseeding is

conducted either during the primary or secondary seeding seasons based on needed remedial work. Surface stability monitoring and remedial actions are conducted as described in

Chapter 26.

Projected Reclamation Schedules

The projected reclamation schedules for the eight coal resource areas in whlch mining and reclamation will occur during the life of operations at the Black Mesa Complex are presented in Tables 1 through 9. The projected acres disturbed, backfilled and graded,

and topsoiled and seeded for five year mine blocks, where appropriate, are included in the tables.

The projections considerations. simultaneously

of acres graded, topsoiled, and seeded are based upon First, once the approximately three pit spoil rows are normally to achieve

three basic rough the graded desired

configurations become

regular

postmining land configuration and grading sequences.

to effectively maintain topographic continuity between

Upon OSM approval, the number of spoils associated with irregular box haulage ramps may exceed four to facilitate

cuts, certain inside and outside curves, and grading.

Second, the point in time at which grading of specific spoils can begin is based

upon excavation cycle times and pit configuration. Cycle times are dependent upon factors such as pit configurations, excavator performance, overburden thickness, the number and thicknesses of partings, and customer demand (see Drawing No. 85210-Mine Plan Map).

Third, once grading begins, the amount of acres graded, topsoiled, and seeded annually in a given pit approximates the acres disturbed annually; however, this will vary each year within each mine area with the pit progression and the spoil area available for

Revised 11/21/03

TABLE 1

Projected Reclamation Schedule for the J - 7 Coal Resource

real
Acres

Acres Year Disturbed

Acres Graded

Topsoiled and Seeded

As of 0 1 / 0 1 / 2 0 0 4
2004 2005

245 37 16 37

163 99 163 0

N.A.
75 252 37 65

Soil Stockpiles ( 2 0 0 5 ) Ponds ( 2 0 1 1 ) Black Mesa Office Complex
(2030)

65

65

198 598

198 688

198 627

Totals :

'~ccounts for topsoiled and seeded acres after 0 1 / 0 1 / 2 0 0 4 .

See Annual Reclamation Reports

for acres disturbed, graded, topsoiled and seeded prior to the above date.

Revised 1 1 / 2 1 / 0 3

TABLE 2

Projected Reclamation Schedule for the N-6 Coal Resource

real
Acres

Acres Year Disturbed

Acres Graded

Topsoiled and Seeded

As of 01/01/2004
2004 2005 2006 2007 2008

N.A.
179 150 50 100 166

Scoria Pits (2030) Central Ops/Warehouse (20301 Outside Roads (2017)
J-3 Airport Complex (2030)

154
133 310 21 244 45

Ponds (2016) Soil Stockpiles (2010, 2016)

Totals :

2267

2222

22 67

'~ccounts for topsoiled and seeded acres after 01/01/2004. See Annual Reclamation Reports for acres disturbed, graded, topsoiled and seeded prior to the above date.

Revised 11/21/03

TABLE 3

Projected Reclamation Schedule for the N-10 and N-11 Coal Resource ~ r e a s l Acres Acres Year Disturbed Acres Graded Topsoiled and Seeded

----- N-10 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads(Beyond 2010) Totals : 0 660 21
42

46 660 21
42

N.A. 660 21
42

52 775

52 821

52 775

----- N-11 Coal Resource Area-----

As of 12/01/2001

797

65

N.A.

Ponds (2014) Topsoil Piles (2006) N-11 Truck D U ~ D Fac. 12026) Totals:

27 32 74 930

27
0 74 898

27
32
74

930

'~ccounts for topsoiled and seeded acres after 12/01/2001. See Annual Reclamation Reports for acres disturbed, graded, topsoiled, and seeded prior to the above date.

7

Revised 11/21/03

TABLE 4

Projected Reclamation Schedule for the J-19 Coal Resource ~rea'

Acres Acres Year Disturbed Acres Graded Topsoiled and Seeded

AS of 12/01/2001
12/01/2001 - 2002 2003 2004 2005 2006-2011

N.A.
357 105 158 134 1425 1429 118 127 273 173 100 200

Beyond 2011 Topsoil Piles (Life of Pit) Ponds (Beyond 2011)
J28 Shop and Facilities.

N8 Facilities Outside Roads Conveyor

Totals :

4529

4481

4599

l~ccountsfor topsoiled and seeded acres after 12/01/2001. See Annual Reclamation Reports for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 01/25/02

TABLE 5

Projected Reclamation Schedule for the J-21 Coal Resource

real
Acres

Acres Year Disturbed

Acres Graded

Topsoiled and Seeded

AS of 12/01/2001 12/01/2001 - 2002 2003 2004 2005 2006-2011 Beyond 2011 Topsoil Piles (Life of Pit) Ponds (Beyond 2011) Scoria Pits (Beyond 2011)

N.A. 253 151
96

191 1265 1690 165 61 142

Totals :

3701

3849

4014

'~ccounts for topsoiled and seeded acres after 12/01/2001. See Annual Reclamation Reports for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 01/25/02

TABLE 6

Projected Reclamation Schedule for the J-23 and N-99 Coal Resource ~ r e a s l

Acres Acres Year Disturbed Acres Graded Topsoiled and Seeded

----- J-23 Coal Resource Area----As of 01/01/2004
2006-2010 0 498 983 84 42 198 1805 0 498 983 0 498 983 84 42 198 1805

Beyond 2010 Topsoil Piles (Life of Pit) Ponds (Life of Pit) Outside Roads (Life of Pit) Totals:

0
42 198 1721

----- N-99 Coal Resource Area-----

Beyond 2010 ~ o p s o i lpiles (Life of Pit) Ponds (Life of Pit) Outside Roads (Life of Pit) Totals :

2031

2031 0 56 0 2854

2031
112

112
56 0 2966

56 0 2966

'~ccounts for topsoiled and seeded acres after 01/01/2004.

See Annual Reclamation Reports

for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 11/21/03

TABLE 7

Projected Reclamation Schedule for the J-2, J-4, J-6 Coal Resource ~reas' Acres Acres Year
we -

Acres Graded

Topsoiled and Seeded
w - * e -

Disturbed

----- 5-2 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010). Topsoil Piles (Beyond 2010) Outside Roads(Beyond 2010) Totals : 0 610 0 24 30 683 0 610 0 0 30 659 0 610 0 24 30 683
-

----- J-4 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads (Beyond 2010) Totals: 0 286 6 11 14 317 0 286 6 0 14 306 0 286 6 11 14 317

----- J-6 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads(Beyond 2010) Totals : 0 821 17 32 41 911 0 821 17 0 41 879 0 821 17 32 41 911

'~ccounts for topsoiled and seeded acres after 01/01/2004.

See Annual Reclamation Reports

for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 11/21/03

TABLE 8

Projected Reclamation Schedule for the J-8, J-9, J-10 Coal Resource ~ r e a s l Acres Acres Year Disturbed Acres Graded Topsoiled and Seeded

----- J-8 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads(Bevond 2010) Totals: 0 269 6
11

0 269 6 0 34 309

0 2 69 6 11 34 320

34 320

----- J-9 Coal Resource Area-----

Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads (Beyond 2010) Totals :

272 6 11 25 314

272 6 0 25 303

272 6 11 25 314

----- J-10 Coal Resource Area-----

As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads (Beyond 2010) Totals:

0 326 7 13 16 362

0 326 7 0 16 349

0 32 6 7 13 16 362

l~ccountsfor topsoiled and seeded acres after Ol/Ol/2OO4.

See Annual Reclamation Reports

for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 11/21/03

TABLE 9

Projected Reclamation Schedule for the 5-14, J-15, 5-28 Coal Resource ~ r e a s l Acres Acres Year Disturbed Acres Graded Topsoiled and Seeded

----- 5-14 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads(Beyond 2010) Totals :
0 755 15 30 10 810 0 755 15 0 10 780 0 755 15 30 10 810

----- 5-15 Coal Resource Area-----

Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads(Bey0nd 2010) Totals :
17 31 485 0 31 468 17 31 485

----- 5-28 Coal Resource Area----As of 1/01/2004 Beyond 2010 Ponds (Beyond 2010) Topsoil Piles (Beyond 2010) Outside Roads (Beyond 2010) Totals :
0 674 10 27 14 725 0 674 10 0 14 698 0 674 10 27 14 725

'~ccounts for topsoiled and seeded acres after Ol/Ol/2OO4.

See Annual Reclamation Reports

for acres disturbed, graded, topsoiled, and seeded prior to the above date.

Revised 11/21/03

backfilling

and grading.

Further, the amount of time needed to complete grading,

topsoiling, and seeding after mining ceases is approximately equal to the lag time between the initiation of mining and the initiation of grading. In certain circumstances, this

generalization may not apply because of the spoil material needed to achieve the designed postmining landform. For example, the backfilling and grading of box cut spoil and deep In

ramps typically requires the movement of large volumes of spoil for great distances.

conclusion, the reclamation process will proceed relative to the mining production, on an annual basis throughout the permitted area.

Abandonment of Operations

All facilities will be reclaimed unless approved as an element of the postmining land use plan. After grading, the reclaimed areas will be topsoiled or covered with suitable plant

growth medium and revegetated. Three to five years will be needed to completely reclaim all facilities and structures following the cessation of mining. Abandonment of mine

facilities will commence when the facilities are no longer required to support mining activities. The structures and equipment including foundations and sub-bases will be

removed; unless approved by the applicable regulatory authority to be reclaimed in-place. Materials having economic value will be salvaged. Materials that are not salvageable will be buried in accordance with the noncoal mine waste disposal plan as required by 30 CFR 816.89. All structure sites will be contoured to conform with the natural landform. Cut

and fill slopes which are compatible with the postmining land use and which are approved by the regulatory authority will be retained.

Revised 02/28/00

CHAPTER 22

MINESOIL RECONSTRUCTION

CHAPTER 22 INDEX

Page

Introduction Plant Growth Media Requirements and Availability Soil in Stockpiles Near-Surface Overburden Projected Soil Salvage Existing Disturbance Areas Projected Disturbance Areas Plant Growth Material Summaries by Pit Area Highwall and Spoil Sampling Plan Material Salvage Plans Site Clearing Procedures Soil Removal Procedures Overburden Removal Procedures Proof of Salvage Soil Stockpiling Plans Material Redistribution Plans Graded Spoil Sampling and Analysis Plans Special Purpose Reclamation Areas Mine Support Facilities Redistribution Procedures Surface Stabilization and Erosion Control Plan Modification Nutrients and Soil Amendments Approximate Original Contour Literature Cited

Revised

11/21/03

Page

LIST OF FIGURES

Figure 1

Infiltration hazard classes adapted from Ayers and Westcott (1989). Saturated paste electrical conductivity (EC) and SAR relationships for 1989-1998 recent spoil samples from the BMMC

LIST OF TABLES

Table 1

Evaluation of Near-Surface Overburden for Suitable Soil Supplements

4

Table 2

Volumes of Suitable Overburden Available in the Mining Areas for Reclamation

8

Table 3

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine 5-2 and 5-4 Disturbance Areas

Table 4

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine J-6 and J-8 Disturbance Areas

Table 5

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine 5-7 Disturbance Area

12

Table 6

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine J-9 and J-10 Disturbance Areas

13

Table 7

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine 5-14 and 5-15 Disturbance Areas

14

Revised

11/21/03

Page

LIST OF TABLES (cont'd)

Table 8

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Kayenta Mine J-16 Disturbance Area

Table 9

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Kayenta Mine J-19 Disturbance Area

Table 10

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Kayenta Mine 5-21 Disturbance Area

Table 11

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine N-6 Disturbance Area

Table 12

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine N-9 and N-10 Disturbance Areas

Table 13

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Kayenta Mine N-11 Disturbance Area

Table 14

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Kayenta Mine N-14 Disturbance Area

Table 15

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Kayenta Mine N-99 and J-28 Disturbance Areas

Revised 11/21/03

Page

LIST OF TABLES (cont'd)

Table 16

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine J-23 Disturbance Area

1 *

Table 17

Maximum Threshold Limits for Evaluating Recently Graded Spoil at the Black Mesa Mining Complex

33

Table 18

Parameter, Procedure, and Reference List for Evaluating Postmine Soil and Spoil Samples

36

LIST OF ATTACHMENTS Attachment
22-1

Site Clearing and Advance Soil Removal Distance Restrictions

22-2

Justification for Using Suitable Overburden in Steep Slope, Key Habitat, Main Drainage Channel, and Cultural Planting Reclamation Areas

Revised 11/21/03

CHAPTER 22 MINESOIL RECONSTRUCTION Introduction

This chapter outlines Peabody Western Coal Company's (PWCC) plan for reconstructing minedland soils and spoil at Black Mesa and Kayenta mines. The plan addresses those and

reclamation activities that are conducted following the completion of backfilling grading (Chapter 21) and prior to revegetation (Chapter 23).

The objective of the plan is

to reconstruct a plant growth medium that is capable of supporting the postmining land uses. The plan objective is achieved by ensuring a minimum of four feet of suitable plant

growth material, which includes twelve inches of soil (except for 1- steep slope, cultural planting, key habitat, and main drainage channel reclamation areas where supplemental surface plant growth media or residual soils may be used in the 0 to 1 foot increment to establish certain substrate-specific species, create wildlife habitat, and provide

erosionally stable landscapes; 2- pre-permanent program facilities and reclamation areas where six inches of soil replacement were approved by Permit AZ-0001; and 3- N-11

reclamation area where 8 to 9 inches of soil are available for replacement), exists on the surface of graded lands prior to the commencement of revegetation activities. The plan

presents an account of the plant growth material requirements based upon current and projected disturbance acreages, and plant growth material availability based on stockpiled material, soil depth mapping, and near-surface overburden assessments. The plan also

describes the procedural aspects of removal, storage, and redistribution of soil materials and soil supplements, and testing of spoil material.

For the purpose of this presentation, soil material is defined as suitable topsoil and subsoil proved up in the soil resources studies (Chapter 8). defined as suitable overburden and spoil. Supplemental material is

Supplemental surface plant growth medium is

defined as suitable overburden and spoil utilized to establish the 0 to 1 foot increment of special reclamation areas including cultural plantings, key habitats, main drainage channels, and steep slopes. Supplemental surface plant growth medium includes native

soils, many of which are classified as residual with a high coarse fragment content (e.g., red rock suitable overburden material that is oxidized, fractured, and weathered

(scoria)).

Toxic- and potentially toxic-forming materials are defined as spoil which

could adversely affect plant growth or contribute to toxic levels of elements or compounds in above ground plant parts.

Revised

10/21/02

Toxic-forming and potentially toxic-forming materials were identified in the overburden assessment (Chapter 8). Because of the existence of multiple coal seams and non-uniform

parting thickness, extreme variability in the lateral and vertical extent of unsuitable overburden strata, and economic considerations, routine special handling of these

materials is not feasible.

Therefore, PWCC maintains a mined-land soil reconstruction

plan that involves handling soil material and suitable supplements rather than potentially toxic or toxic-forming materials. exhibit unsuitable characteristics The intent is to identify areas of graded spoil that and bury them with adequate amounts of the best

available suitable materials.

Over the past 15 years, PWCC has developed a site-specific soil, spoil, and overburden sampling program to accurately maintain requirements and availability. a dynamic inventory of plant growth material

This program is based upon the sampling of graded spoil to

determine how much topsoil, residual soil, supplemental material, or supplemental surface plant growth medium will be needed prior to revegetation. The suitability and approximate The suitability and is also known.

volume of available soil material (in storage and in-place) is known. estimated volumes of suitable supplements, including residual

soils

Overburden and spoil piles are occasionally sampled to further delineate the volumes and locations of supplements. This sampling program allows PWCC to track the availability of The program enables

both soil material and supplemental material on an ongoing basis.

PWCC to determine the amount of material needed prior to revegetation via the graded spoil sampling plan, and where to obtain the material.

PWCC removes and stores available soil material in sufficient quantities needed to cover all disturbances (with exception of special reclamation areas, the N-11 mining area, and interim program disturbance areas) with twelve inches of soil. After grading is completed

in a given unit of grading advance, a graded spoil sampling program is used to identify the volume of soil, soil supplements, supplemental surface plant growth medium, or

residual soil needed in the area to bury unsuitable spoils.

Soil and soil supplements (if

needed) are then salvaged and redistributed on the basis of the graded spoil sampling results. The collection of ongoing sampling data to identify both unsuitable graded

spoils and suitable soil supplements enables PWCC to maintain a dynamic inventory of available (in stockpile and in-place) and required plant growth material. These

inventories are updated and balanced no less than once annually. adequate inventory of suitable plant growth media requirements prior to revegetation.

In this manner, an reclamation

is maintained to meet

Revised

10/21/02

Plant Growth Media Requirements and Availability

This section presents an estimate of the volume of plant growth material that is required and available for reclamation. The accounts consider both the current and future

requirements and availability because the Black Mesa mining complex has been in operation for several years. Soil and supplemental material availability is considered first,

followed by the requirements.

Soil in Stockpiles.

Tables 5, 8 thru 11, and 13 presented later in this chapter, list the The storage

total estimated volume of soil material in stockpile as of January 1, 2002. volumes are sub-totaled by each active mining

area and individual stockpile in the annually. Terra-Matrix

Reclamation Status and Monitoring Report submitted to OSMRE

Montgomery Watson used cross-sectional area survey techniques in August 1997 to determine soil volumes for stockpiles. load count information. is 6,651 acre-feet. Subsequently, volume changes have been updated using scraper

The estimated volume of material in storage as of January 1, 2002

Stockpile locations are shown on the Mine Plan Map, Drawing 85210.

Near-Surface Overburden.

An assessment of the near-surface overburden is performed to

identify suitable material in each active mining area and future development areas should it be needed as soil material supplements. This assessment is performed using the

physical and chemical analysis results on the shallow and deep overburden cores drilled in each mining area (see Appendix 8 , Volume 12). Table 1 presents the results of the

assessment of near-surface overburden that meets the limits for suitable supplemental material. Suitability criteria, presented later in Table 17 of this chapter, are used for the near-surface overburden assessments. Table 2 presents the estimated volumes of The

suitable near-surface overburden available in each mining area for reclamation.

volumes represent sources of soil supplements that can be used to bury unsuitable graded spoils. The volumes were derived from the average depth data given in Table 2, and the

acreages of the mining blocks and coal resource areas in each mining area, delineated on Drawing 85210, Mine Plan Map, remaining to be excavated as of December 15, 2003.

Projected Soil Salvage.

Projected soil salvage areas and volumes for the remaining lifeIndividual soil map units (Drawings

of-mine by mine area are determined as follows.

85305A and 85305C) to be disturbed by mining activities are digitized and placed into an ArcInfo GIs database to determine the total affected area. The projected soil disturbance

3

Revised

11/21/03

TABLE 1

E v a l u a t i o n of Near-Surface Overburden f o r S u i t a b l e S o i l Supplements

Mining Area

Core Number (1)

Depth o f Suitable Material ft'2'

C r i t e r i o n Out 3 o f ~ a r q (e ' 4,

Average Clay>45% L o s t Sample L o s t Sample Average Coal Coal pH<5.5 Average Coal AEP<-5 Coal Coal SAR>2O Clay>45% ABP<-5 Clay>45% None pHi5.5 Clay>45% pH<5.5 pHi5.5

Revised

11/21/03

TABLE I (Continued)

Evaluation of Near-Surface Overburden for Suitable Soil Supplements

Mining Area

Core

umber")

Depth of Suitable Material ft")

Criterion Out of ~ a n ( 3 ' 4 )e ~

26374-C 26469-C 26483-C 26484-C 26485-C 26486-C 26487-C 26488-C 26489-C 264 95-C 264 96-C Average 2 4 405-C* 24412-C* 24413-C 24415-C* 24416-C* 24417-C* 26280-C* 26286-C 26288-C 26289-C 26377-C* 26384-C* 26385-C' 26386-C 26387-C 26388-C* 26493-C 26494-C 26497-C Average

Coal Clay>45% pHc5.5 pH(5.5 None Lost Sample pH<5.5 ABP<-5 ABP<-5 None Clay>45%

Clay>45% pH<5.5 pHi5.5 pH<5.5 Coal pH<5.5 pH<5.5 Clay>45% pH<5.5 Clay>45% pH<5.5 Clay>45% pH<5.5 Clay>45% SAR>20 Clay>45% None Clay>45% Clay>45%

Revised

11/21/03

TABLE 1 (Continued)

Evaluation of Near-Surface Overburden for Suitable Soil Supplements

Mining Area

Core

umber 'I'

Depth o f Suitable Material ft'2)

Criterion Out of ~ a n g e ' ~ ' ~ '

Coal

Average

pH<5.5 Clay>45% Coal

Average Coal pH<5.5 Coal ABP<-5 Average

Revised

11/21/03

TABLE 1 (Continued)

Evaluation of Near-Surface Overburden for Suitable Soil Supplements

Mining Area

Core ~urnber(')

Depth of Suitable Material ftc2)

Criterion Out of ~ancje'~'~)

Average

11.4 pHi5.5 pH<5.5 Coal

Average pH<5.5 pH<5.5 ABP<-5 ABK-5 pH<5.5 Coal pH<5.5 Average 47.8

(I'

For sample site location, see Drawings 85613 and 85613A, Volume 23

(2) Asterisked cores are cores where topsoil materials will be salvaged and the probable depths of salvage have been subtracted from the determination. For overburden analyses, see Appendix B, Volume 12.

(3)

(4)

Diagnostic criteria and limits for suitable material are based upon maximum

threshold limits presented in Table 17 later in this chapter.

Revised

11/21/03

TABLE 2 Volumes of Suitable Overburden Available in the Mining Areas for Reclamation
(1)

Mining Area

Mining Disturbance (Acres)

Mean Depth of Suitable Material (ft)

Volume of Suitable Material (ac-ft)

Total

13,894

26.6

370,352 The mining disturbance

(''~ean depths of suitable material are from Table 1.

area for each pit is delineated on Drawing 85210, Mine Plan Map.

Revised

11/21/03

boundaries for the life-of-mine area are determined by referencing the Jurisdictional Permit and Affected Lands Map (Drawing 85360). Projected soil volumes are determined by

multiplying each affected soil map unit area by the respective mean salvage thickness. The soil salvage thickness, shown on Drawings 853058 and 85305C, are based upon the results of the Order 1 and 2 soil survey information presented in Chapter 8. The quantity

of soil available to be salvaged in each pit area is presented in Tables 3 through 16 of this chapter. About 13,961 acre-feet of soil remain to be salvaged (projected soil About

volume) as of January 1, 2002 in the life-of-mine active mining disturbance areas.

43,947 acre-feet of soil is available for salvage in the life-of-mine development areas.

Existing Disturbance Areas.

The post-law disturbance area, as of January 1, 2002, for the

entire Black Mesa mining complex by mining area is presented later in Tables 5, 8 thru 11, 13, and 14 of this chapter. This acreage represents the current plant growth material These liability areas include the existing disturbance An additional 969

liability area for the leasehold.

area surrounding the active pits, non-permanent roads, and facilities. acres at the Black Mesa and Kayenta Mines are under sediment ponds.

This acreage is not

included in the total soil material liability area because the ponds will either be reclaimed and surface-dressed using site-specific materials or retained to compliment the postmine land use (see Chapter 23). The existing dam embankment material, upstream

alluvium, and trapped sediments (if they meet the soil suitability criteria) will be used as surface dressing to reclaim the sediment ponds. existing soil storage piles located on native ground. An additional 363 acres are under This acreage is not included in the

total liability area because the original ground surface will be re-exposed upon removal of the stockpiles. Lastly, certain proposed permanent roads (278 acres) will not receive

any soil because they will be retained for access to residences and grazing lands.

Based upon the redistribution depth requirements in Permits AZ-0002A and AZ-OOOlD, post July 1990 disturbances at the N-14 and J-16 mining areas, and all disturbances at the J-19 and 5-21 mining areas (excluding special reclamation areas) must be covered with a minimum of one foot of plant growth material. A
8- to

9-inch minimum-average replacement Based upon the redistribution

thickness of soil is proposed for the N-11 mining area.

depth requirement in Permit AZ-0001, all remaining disturbances must be covered with a minimum of 0.5 feet of material. The minimum volume of soil material required for

reclamation over the entire liability area is 4,818 acre-feet and there are 6,651 acrefeet of soil stockpiled as of January 2002 (Tables 5, 8 thru 11, 13, and 14). Thus,

sufficient soil material exists in stockpile to meet all reclamation requirements, as of

9

Revised

11/21/03

TABLE 3

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine J-2 and 3-4 Disturbance Areas (As of November 21, 2003)

5-2 Disturbance Area

Projected Disturbance Area Includes entire life-of-mine area including pits, roads, and facilities. Projected Soil Volume Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine. Supplemental Plant Growth Material Volume Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2. Mean Soil Replacement Thickness (2,391 acre-feet/903 acres) An excess of 1,488 acre-feet of soil, based on the 1.0-foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material

=

903 acres

=

2,391 acre-feet

=

14,706 acre-feet

=

2.65 feet

J-4 Disturbance Area

Projected Disturbance Area Includes entire life-of-mine area including pits, roads, and facilities. Projected Soil Volume Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine. Supplemental Plant Growth Material Volume Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2. Mean Soil Replacement Thickness (822 acre-feet/524 acres) An excess of 298 acre-feet of soil, based on the 1.0-foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material.

=

524 acres

=

822 acre-feet

=

2,310 acre-feet

10

Revised 11/21/03

TABLE 4

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine J-6 and J-8 Disturbance Areas (As of November 21, 2003)

J-6 Disturbance Area Projected Disturbance Area Includes entire life-of-mine area including pits, roads, and facilities. Projected Soil Volume Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine. Supplemental Plant Growth Material Volume Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2. Mean Soil Replacement Thickness (2,483 acre-feet/l,217 acres) An excess of 1,266 acre-feet of soil, based on the 1.0-foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material 2.04 feet 32,164 acre-feet
=
=

1,217 acres

2.483 acre-feet

=

=

J-8 Disturbance Area Projected Disturbance Area Includes entire life-of-mine area including pits, roads, and facilities. Projected Soil Volume Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine. Mean Soil Replacement Thickness (1,665 acre-feet/733 acres) An excess of 932 acre-feet of soil, based on the 1.0-foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material. 2.27 feet
= =

733 acres

1.665 acre-feet

=

Revised

11/21/03

TABLE 5 Soil Salvage Volume and Supplemental Plant Growth Material Disturbance Planning Summaries for the Black Mesa Mine 5-7 Disturbance Area (As of January 1, 2002)

Disturbance Area Near Existing Pit

=

322 acres

The disturbed area includes the advance grubbed and soil removed area, active pit, last two spoil piles, gradable area, ramps, and final graded land.
Road Disturbance Area

The soil stockpiles (37 acres) and ponds
=

(168 acres) are not included. 167 acres Includes haul roads and the 5-7/5-27 Black Mesa roads, but does not include 36 acres of permanent roads (see Drawing 85445).
Facility Disturbance Area
=

150 acres

Includes Black Mesa office, shop, and warehouse areas and coal storage areas.
Existing Soil Volume

=

502 acre-feet 104 acres

The volume stored in stockpiles as of January 1, 2002.
Projected Disturbance Area Projected Soil Volume
= =

66 acre-feet

Includes only those soil map units that will be disturbed by mining-related activities.
Supplemental Plant Growth Material Volume
=

1,050 acre-feet

Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2.
Permitted Scoria Pit Area
=

304 acres

Includes two separate areas, as shown on Drawing 85360. Disturbed lands will be reclaimed using soil or supplemental plant growth media salvaged from these areas.
Mean Soil Replacement Thickness

=

0.76* feet

(568 acre-feet/743 acres) *The minimum-average replacement thickness of soil at 5-7 will be 9 inches. Pursuant to Permit AZ-0001, soil replacement thickness on interim disturbance areas is required to be 0.5 feet or greater.
Soil Required to Reclaim Current Disturbance Area
=

320 acre-feet

((322 + 167 + 150) acres X 0.5 feet)

12

Revised

11/21/03

TABLE 6

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine J-9 and J-10 Disturbance Areas (As of November 21, 2003)

J-9 Disturbance Area

Projected Disturbance Area

=

474 acres

Includes entire life-of-mine area including pits, roads, and facilities.
Projeoted Soil Volume
=

1,539 acre-feet

Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine.
Supplemental Plant Growth Material Volume

=

10,589 acre-feet

Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2.
Mean Soil Replacement Thickness
=

3.25 feet

(1,539 acre-feet/474 acres)

An excess of 1,065 acre-feet of

soil, based on the 1.0-foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material.

J-10 Disturbance Area

Projected Disturbance Area

=

432 acres

Includes entire life-of-mine area including pits, roads, and facilities.
Projected Soil Volume
=

781 acre-feet

Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine.
Mean Soil Replacement Thickness

=

1.81 feet

(781 acre-feet/432 acres)

An excess of 349 acre-feet of soil,

based on the 1.0-foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material.

Revised

11/21/03

TABLE 7

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine 5-14 and 5-15 Disturbance Areas (As of November 21, 2003)

5-14 Disturbance Area Projected Disturbance Area Includes entire life-of-mine area including pits, roads, and facilities. Projected Soil Volume Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine. Supplemental Plant Growth Material Volume Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2. Mean Soil Replacement Thickness (1,068 acre-feet/948 acres) An excess of 120 acre-feet of soil, based on the 1.0-foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material.
=
=

=

948 acres

1,068 acre-feet

=

18,170 acre-feet

1.13 feet

5-15 Disturbance Area Projected Disturbance Area Includes entire life-of-mine area including pits, roads, and facilities. Projected Soil Volume Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine. Supplemental Plant Growth Material Volume Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2. Mean Soil Replacement Thickness (893 acre-feet/729 acres) An excess of 164 acre-feet of soil, based on the 1.0-foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material. 1.22 feet 8,602 acre-feet
=

=

729 acres

893 acre-feet

=

=

14

Revised

11/21/03

TABLE 8

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Kayenta Mine J-16 Disturbance Area (As of January 1, 2002)

Disturbance Area Near Existing Pit

=

1 acre

The disturbed area includes final graded land, but does not include 87 acres of ponds and 11 acres of soil stockpiles.
Road Disturbance ~ r e a
=

72 acres

Includes haul roads and the adjacent J-16 Kayenta roads, but does not include 18 acres of permanent roads (see Drawing 85445).
Facility Disturbance Area
=

34 acres

Includes bucket barn area.
Existing Soil Volume

=

105 acre-feet 0 acres 0 acre-feet

The volume stored in stockpiles as of January 1, 2002
Projected Disturbance Area Projected Soil Volume
=
=

No additional soil map units will be disturbed by future mining related activities.
Supplemental Plant Growth Material Volume
=

0

acre-feet

If supplemental material is required based on graded spoil analysis, it will be hauled from nearby graded land or an adjacent mine area.
Mean Soil Replacement Thickness
=

0.98* feet

(105 acre-feet/l07 acres)

* Pursuant to Permit AZ-0001, soil replacement thickness on
interim disturbance areas is required to be 0.5 feet or greater.
Soil Required to Reclaim Current Disturbance Area
=

105 acre-feet

((1

+ 72 + 34) acres X 0.98 feet)

Revised

11/21/03

TABLE 9

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Kayenta Mine J-19 Disturbance Area (Includes J-19-West) (As of January 1, 2002)
Disturbance Area Near Existing P i t
=

873 acres

The disturbed area includes the advance soil removed area, active pit, last two spoil piles, gradable area, ramps, and final graded land. The soil stockpiles (96 acres) and ponds
=

(166 acres) are not included.
Road Disturbance Area

194 acres

Includes haul roads, the J-19 Kayenta Mine roads, and 50% of the N-1, N-2, N-7, and N-8 Kayenta Mine roads, but does not include 50 acres of permanent roads (see Drawing 85445).
F a c i l i t y Disturbance Area
=

96 acres

Includes 5-20 office, shop, warehouse complex, and 50% of the N-1 and N-7/8 conveyor sections.
Existing S o i l Volume
=

1,950 acre-feet 2,330 acres 5,541 acre-feet

The volume stored in stockpiles as January 1, 2002
Projected Disturbance Area
=

Includes entire life-of-mine area.
Projected S o i l Volume
=

Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine.
Supplemental Plant Growth Material Volume
=

40,417 acre-feet

Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2.
Permitted Scoria P i t Area
=

0 acres

No scoria pits are planned outside of the projected pit disturbance area.
Mean S o i l Replacement Thickness
=

2.02 feet

(7,065 acre-feet/3,493 acres) Replacement thickness has been adjusted for 426 acre-feet of soil that will be exported to the N-14 reclamation area. A n excess of 3,572 acre-feet of soil, based on the 1-foot replacement thickness required by Permit AZOOOlD, is available for use as supplemental material.
S o i l Required t o Reclaim Current Disturbance Area
=

1,163 acre-feet

((873 + 194

+

96) acres X 1.0 feet)

16

Revised 11/21/03

TABLE 10

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Kayenta Mine 5-21 Disturbance Area (As of January 1, 2002)

Disturbance Area Near Existinq Pit

=

898 acres

The disturbed area includes the advance grubbed and soil removed area, active pit, last two spoil piles, gradable area, ramps, and final graded land.
Road Disturbance Area

The soil stockpiles (154 acres) and
=

ponds (197 acres) are not included. 294 acres Includes haul roads, the J-21 and 5-28 Kayenta Mine roads, and 50% of the N-1, N-2, N-7 and N-8 Kayenta Mine roads but does not include 76 acres of permanent roads (see Drawing 85445).
Facility Disturbance Area
=

402 acres

Includes 5-21 explosive storage, 5-28 coal handling facilities, and 50% of the N-1 and N-7/8 conveyor sections.
Existing Soil Volume

=

2,983 acre-feet 2,437 acres

The volume stored in stockpiles as of January 1, 2002
Projected Disturbance Area
=

Includes entire life-of-mine area.
Projected Soil Volume
=

7,086 acre-feet

Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine.
Supplemental Plant Growth Material Volume
=

23,988 acre-feet

Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2.
Permitted Scoria Pit Area
=

117 acres

Includes one area as shown on Drawing 85360. salvaged from this area.
Mean Soil Replacement Thickness

Disturbed lands

will be reclaimed using soil or supplemental plant growth media

=

2.50feet

(10,069 acre-feet/4,031 acres)

An excess of 6,038 acre-feet of

soil based on the 1.0 foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material.
Soil Required to Reclaim Current Disturbance Area
=

1,594 acre-feet

((898 + 294 t 402) acres X 1.0 feet)

17

Revised

11/21/03

TABLE 11

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine N-6 Disturbance Area (As of January 1, 2002)

Disturbance Area Near Existing Pit

=

874 acres

The disturbed area includes the advance grubbed and soil removed area, active pit, last two spoil piles, gradable area, ramps, and final graded land.
Road Disturbance Area

The soil stockpiles (33 acres) and ponds
=

(204 acres) are not included. 222 acres Includes haul roads and the J-3/N-6 Black Mesa roads, but does not include 48 acres of permanent roads (see Drawing 85445).
Facility Disturbance Area
=

235 acres

Includes Black Mesa Central warehouse, office, and HRC areas, truck storage, explosive storage, 5-3 airport, public coal yard, trailer park, and reclamation office.
Existing Soil Volume
=

622 acre-feet 426 acres
1,174 acre-feet

The volume stored in stockpiles as of January 1, 2002.
Projected Disturbance Area Projected Soil Volume
= =

Includes only those soil map units that will be disturbed by mining-related activities.
Supplemental Plant Growth Material Volume
=

7,711 acre-feet

Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2.
Permitted Scoria Pit Area
=

140 acres

Includes two separate areas, as shown on Drawing 85360. Disturbed lands will be reclaimed using soil or supplemental plant growth media salvaged from these areas.
Mean Soil Replacement Thickness

(1,796 acre-feet/1,757 acres) 'Pursuant to Permit AZ-0001, soil replacement thickness on interim disturbance areas is required to be 0.5 feet or greater.
Soil Required to Reclaim Current Disturbance Area
=

655 acre-feet

((874 + 222

+ 235) acres X 0.5 feet)

18

Revised

11/21/03

TABLE 12

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine N-9 and N-10 Disturbance Areas (As of November 21, 2003)

N-9 Disturbance Area

Projected Disturbance Area Includes entire life-of-mine area including pits, roads, and facilities. Projected Soil Volume Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine. Supplemental Plant Growth Material Volume Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2. Mean Soil Replacement Thickness (3,299 acre-feet/2,165 acres) An excess of 1,134 acre-feet of soil, based on the 1.0-foot replacement thickness required by Permit AZ-0001D, is available for use as supplemental material.

=

2,165 acres

=

3.299 acre-feet

=

45,277 acre-feet

=

1.52 feet

N-10 Disturbance Area
Projected Disturbance Area Includes entire life-of-mine area including pits, roads, and facilities. Projected Soil Volume Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine. Supplemental Plant Growth Material Volume Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2 . Mean Soil Replacement Thickness (1,637 acre-feet/l,613 acres) An excess of 24 acre-feet of soil, based on the 1.0-foot replacement thickness required by Permit AZ-0001D, is available for use as supplemental material. 19 Revised 11/21/03 10,363 acre-feet
= =

1,613 acres

1,637 acre-feet

=

TABLE 13

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Kayenta Mine N-11 Disturbance Area (As of January 1, 2002)

Disturbance Area Near Existing Pit

=

511 acres

The disturbed area includes the advance grubbed and soil removed area, active pit, last two spoil piles, gradable area, ramps, and final graded land.
Road Disturbance Area

The soil stockpiles (32 acres) and ponds
=

(58 acres) are not included. 58 acres Includes haul roads and the N-11 Kayenta roads, but does not include 15 acres of permanent roads (see Drawing 85445).
Facility Disturbance Area
=

158 acres

Includes N-11 coal storage area, adjacent conveyors, and CDK yard.
Existing Soil Volume
=

489 acre-feet 8 acres 94 acre-feet

The volume stored in stockpiles as of January 1, 2002
Projected Disturbance Area
=

Includes entire life-of-mine area.
Projected Soil Volume
=

Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine.
Supplemental Plant Growth Material Volume
=

1,952 acre-feet

Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2.
Permitted Scoria Pit Area
=

53 acres

Includes one area as shown on Drawing 85360. salvaged from this area.
Mean Soil Replacement Thickness

Disturbed lands

will be reclaimed using soil or supplemental plant growth media

=

0.79' feet

(583 acre-feet/735 acres) *The minimum-average replacement thickness of soil at N-11 will be 9 inches.
Soil Required to Reclaim Current Disturbance Area
=

545 acre-feet

((511

+

58

+

158) acres X 0.75 feet)

20

Revised

11/21/03

TABLE 14

S o i l S a l v a g e Volume and S u p p l e m e n t a l P l a n t Growth M a t e r i a l P l a n n i n g Summaries f o r t h e Kayenta Mine N - 1 4 Disturbance Area

(As o f J a n u a r y 1, 2002)

D i s t u r b a n c e Area Near E x i s t i n g P i t The d i s t u r b e d a r e a i n c l u d e s f i n a l g r a d e d l a n d , b u t d o e s n o t i n c l u d e 89 a c r e s o f ponds. Road D i s t u r b a n c e A r e a I n c l u d e s h a u l r o a d s and a d j a c e n t N - 1 4 F a c i l i t y Disturbance Area Includes N-14 conveyor a r e a s e x p l o s i v e s t o r a g e , l a b p a r k i n g a r e a , and a d j a c e n t Kayenta r o a d s , b u t d o e s n o t i n c l u d e 3 5 a c r e s o f p e r m a n e n t r o a d s ( s e e Drawing 8 5 4 4 5 ) .

=

49 a c r e s

=

135 a c r e s

=

242 a c r e s

E x i s t i n g S o i l Volume The volume s t o r e d i n s t o c k p i l e s a s o f J a n u a r y 1, 2002 P r o j e c t e d D i s t u r b a n c e Area P r o j e c t e d S o i l Volume No a d d i t i o n a l s o i l map u n i t s w i l l b e d i s t u r b e d by f u t u r e m i n i n g related activities. S u p p l e m e n t a l P l a n t Growth M a t e r i a l Volume I f m a t e r i a l i s r e q u i r e d b a s e d on g r a d e d s p o i l a n a l y s i s , it w i l l b e h a u l e d from n e a r b y g r a d e d l a n d o r a n a d j a c e n t mine a r e a .

=

0 acre-feet 0 acres 0 acre-feet

=
=

=

0 acre-feet

P e r m i t t e d S c o r i a P i t Area Includes t h r e e areas, a s shown on Drawing 85360. Disturbed l a n d s w i l l be reclaimed using s o i l o r supplemental p l a n t growth media s a l v a g e d from t h e s e a r e a s .

=

54 a c r e s

Mean S o i l R e p l a c e m e n t T h i c k n e s s ( 0 acre-feet/426 acres) The *The maximum p r o j e c t e d d e f i c i t o f 426 a c r e - f e e t o f s o i l w i l l b e t r a n s p o r t e d from e x i s t i n g J-19 s o i l s t o r a g e s t o c k p i l e s . a c t u a l q u a n t i t y o f s o i l t r a n s p o r t e d w i l l b e l e s s t h a n 426 a c r e f e e t s i n c e 1) many c o n v e y o r and h a u l r o a d s i d e s l o p e s h a v e a l r e a d y been t o p s o i l e d , and 2 ) p u r s u a n t t o P e r m i t AZ-0001, soil r e p l a c e m e n t t h i c k n e s s on i n t e r i m d i s t u r b a n c e a r e a s i s r e q u i r e d t o be 0 . 5 f e e t o r q r e a t e r . S o i l Required t o Reclaim Current Disturbance Area ( ( 4 9 t 135

=

0.00* f e e t

=

426 a c r e - f e e t

+

242) a c r e s X 1 . 0 f e e t

21

Revised

11/21/03

TABLE 15

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Kayenta Mine N-99 and J-28 Disturbance Areas (As of November 21, 2003)

N-99 Disturbance Area

Projected Disturbance Area

=

3,883 acres

Includes entire life-of-mine area including pits, roads, and facilities.
Projected Soil Volume
=

4,398 acre-feet

Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine.
Supplemental Plant Growth Material Volume
=

126,574 acre-feet

Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2.
Mean Soil Replacement Thickness
=

1.13 feet

(4,398 acre-feet/3,883 acres)

An excess of 515 acre-feet of

soil, based on the 1.0-foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material.

5-28 Disturbance Area

Projected Disturbance Area

=

1,438 acres

Includes entire life-of-mine area including pits, roads, and facilities.
Projected Soil Volume
=

4,183 acre-feet

Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine.
Supplemental Plant Growth Material Volume
=

2,488 acre-feet

Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2.
Mean Soil Replacement Thickness
=

2.91 feet

(4,183 acre-feet/1,438 acres)

An excess of 2,745 acre-feet of

soil, based on the 1.0-foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material.

22

Revised

11/21/03

TABLE 16

Soil Salvage Volume and Supplemental Plant Growth Material Planning Summaries for the Black Mesa Mine J-23 Disturbance Areas (As of November 21, 2003)

5-23 Disturbance Area

Projected Disturbance Area Includes entire life-of-mine area including pits, roads, and facilities. Projected Soil Volume Includes only those soil map units that will be disturbed by mining-related activities over the life-of-mine. Supplemental Plant Growth Material Volume Supplemental material available for special handling or reclamation of additional facilities based on graded spoil analyses as listed in Table 2. Mean Soil Replacement Thickness (4,827 acre-feet/2,496 acres) An excess of 2,331 acre-feet of soil, based on the 1.0-foot replacement thickness required by Permit AZ-OOOlD, is available for use as supplemental material.

=

2,496 acres

=

4,827 acre-feet

=

23,991 acre-feet

=

1.93 feet

Revised 11/21/03

January 2002, on the leasehold.

Excess soil will be used as supplemental material for

covering and burying unsuitable spoil.

Projected Disturbance Areas.

Tables 3 through 16 present projected disturbance area Approximately 22,508 acres are expected to be This total includes:

statistics for the life-of-mine Mine Plan.

disturbed and 43,947 acre feet of soil are projected to be salvaged.

(1) land to be disturbed for the first time as a result of the life-of-mine Mine Plan; (2) lands disturbed as a result of existing Mine Plans (redisturbance); and (3) pre-December 16, 1977 land disturbance that will be redisturbed.

By dividing the total volume of soil

to be salvaged by the projected disturbance area, it can be seen that 1.9 feet of soil is available for future reclamation purposes on the leasehold. When the volumes of suitable

soil supplemeAts are considered (Table 2), it can be seen that a sufficient amount of suitable plant growth media is available to reconstruct mined-land soils that meet the objectives of the minesoil reconstruction plan.

Plant Growth Material

Summaries by Pit Area.

Tables 3 through 16 present soil and

supplemental plant growth material planning summaries for each respective mining area. The tables present: (1) volume of soil material in storage; (2) the projected soil salvage areas and soil volume for the remaining areas to be disturbed; (3) existing disturbance areas, including roads and facilities, requiring soil replacement; (4) excess soil

available for use as supplemental material; (5) mean soil replacement thickness values; and (6) supplemental plant growth material volumes (from Table 2). The information given

in the tables demonstrates that adequate plant growth materials are available, and will be salvaged and replaced to achieve reconstructed minesoil productivity consistent with the postmining land uses in each disturbance area.

The soil and supplemental plant growth material planning summaries (Tables 5, 8 thru 11, 13, and 14) for the active mining areas indicate an excess of about 9,610 acre-feet of soil is available for special handling and use for supplemental material. The 5-7, N-6,

N-11, N-14, and J-16 areas have little to no available excess soil available for use as supplemental material. In contrast, the J-19 and J-21 areas have 3,500 to 6,000 acre-feet This excess soil will be used with

of soil available for use as supplemental material. supplemental suitable overburden material

(Table 2) to cover unsuitable spoil with a All facilities will be reclaimed

minimum of four feet of suitable plant growth medium.

according to the provisions of the minesoil reconstruction and revegetation plans outlined

Revised

11/21/03

in this and the succeeding chapter. Drawing 85360 (Volume 20).

The location of these facilities may be found on

The soil and supplemental plant growth material planning summaries for the future life-ofmine development areas (Tables 3, 4, 6, 7, 12, 15, and 16) indicate an excess of about 12,431 acre-feet material. of soil is available for special handling and use for supplemental

The J-4, J-10, 5-14, J-15, N-10, and N-99 areas have little to no available In contrast, the 5-2, J-6, J-8,

excess soil available for use as supplemental material.

J-9, N-9, 5-23, and 5-28 areas have 900 to 2,700 acre-feet of soil available for use as supplemental material. This excess soil will be used with supplemental suitable

overburden material (Table 2) to cover unsuitable spoil with a minimum of four feet of suitable plant growth medium.

The projected

soil replacement

volumes

and replacement

thickness

listed

in Tables 3

through 16 will vary depending upon the amount and availability of plant growth material needed to bury unsuitable graded spoils. In all cases except the existing N-11 mining

area or other interim disturbance areas, a minimum-average of twelve inches of soil will be redistributed on the reclaimed spoils unless specific substrates are being

reconstructed potential

for shrub and tree establishment, wildlife habitat, or reduced erosion

(see Steep Slope, Cultural Planting, Key Habitat, and Main Drainage Channel

discussion presented in the "Special Purpose Reclamation Areas" section of this chapter). Insufficient soil is available at N-ll to meet the minimum-average twelve-inch thickness. The minimum-average replacement thickness of soil at N-11 will be 8 to 9 inches while all interim disturbance areas will receive 0.5 feet or more of soil as required by Permit AZ0001.

It appears from Tables 5, 8 thru 11, 13, and 14 that an excess 9,610 acre-feet of soil will remain in stockpile after reclamation of all projected mining disturbances. the graded spoil sampling program is used to identify the actual However,

volumes of soil,

supplemental material, supplemental surface plant growth media, and residual soils needed to meet redistribution requirements. required plant growth !material.

A dynamic inventory is maintained of available and

Logically, as mining approaches completion in a given

area, the inventory of stockpiled soil is adjusted to ensure that little or no excess material remains in stockpile. Should excess soil remain in stockpile after mining is

completed in a given area, the excess will be redistributed on the final reclamation to achieve an approximately uniform, stable thickness consistent with the approved postmining land use, contours, and surface-water drainage systems. 25 Revised 11/21/03

The maximum uniform depth of soil that could potentially be redistributed at each mining area varies from slightly less than a foot to over two feet. PWCC intends to bury The

unsuitable spoils with a minimum of four feet of suitable plant growth material.

available soil in each mining area is not sufficient to cover the liability areas if the very conservative assumption is made that all graded spoils are unsuitable at the surface. Suitable supplements and residual soils will be used to augment the soil material.

Highwall and Spoil Sampling Plan

Considerable supplemental plant growth material has been identified ahead of the highwall in each mining area as inventoried in Tables 1 and 2. material be needed for reclamation, Should any of this overburden

it will be sampled to determine suitability for

redistribution on graded spoil prior to handling unless the quality has been established from previous sampling activity.

In-place overburden will be sampled using a core drill.

The drilling and sampling methods

and procedures will follow those used to obtain overburden impact cores or chip samples (Chapter 4). Suitability criteria and analysis procedures will be the same as those used spoils (see Material Redistribution Plan section of this chapter).

to sample graded

Dozers, trucks and front-end loaders/shovels, or scrapers will handle in-place overburden used as a source of supplemental material.

Spoil piles and rough graded spoil to be used as a source of supplemental material will also be sampled prior to moving materials. Suitable material may be used in situations

where the graded spoil to be buried is in close proximity to the suitable borrow area. Dozers, trucks and front-end loaders/shovels, or scrapers will be used to move spoil identified as suitable. Suitability criteria and analysis procedures will be the same as Records from highwall and spoil sampling will be kept

those used to sample graded spoils. on file at the mine site.

Material Salvage Plans

Site Clearing Procedures.

Prior to soil removal, dozers or other suitable equipment,

clear the area of large vegetation material consisting primarily of pinyon and juniper trees. The vegetation debris removed in the clearing process is placed at locations that Local residents utilize a majority of the

will not interfere with mining operations. woody material for firewood.

The remainder is either piled at the edges of mining areas

26

Revised

11/21/03

to provide cover and nesting habitat for wildlife, or buried during the mining operations so as not to cause a stability hazard. year. Clearing activities are conducted throughout the

Maximum clearing distances are given in Attachment 22-1.

Soil Removal Procedures. operations in each pit

Soil is removed a maximum of 1,500 feet in advance of mining (see Attachment
22-1

for justification).

Other mine support

facilities such as, but not limited to, sediment ponds, soil stockpiles, powerlines, substation sites, access roads, storage yards, environmental monitoring sites, and

deadhead routes located in the mine plan areas that may require site clearing and/or soil removal activities isolated from the main advance disturbance areas are not considered part of the specifications in Attachment 22-1. These isolated activities are permitted

and limited to Category I or I1 disturbance areas shown on the Bonding Map, Drawing No. 89800. ground However, advance soil removal distances may be less at times in each pit due to conditions, equipment availability, operating room constraints, and material

requirements.

Soil is normally removed from March to November, or in other months if

mining conditions warrant and weather conditions permit.

Once the soil investigation and site clearing are complete, the soil scientist reviews the depositional and areal extent of the soil that is to be removed with foremen and

reclamation personnel who will be supervising the soil removal operation.

The foreman and

reclamation supervisors are qualified and trained to evaluate various field observation tests, including soil color, rooting depth, sand and clay content, rock fragment content, and weathered bedrock. In areas where extensive material exists, the soil scientist,

foreman, and/or reclamation personnel observes the soil removal operation on a frequent basis to assure that material is recovered without being contaminated by extraneous soil materials. In areas with thin depositions of soil or where soil recovery may be

complicated or difficult, the soil scientist, foreman, and/or reclamation personnel may stake depths of soil to be recovered based on site-specific conditions and their

professional judgment, or continuously monitor the soil removal operation.

Once the planning, instruction, and pre-removal investigations are completed, the soil is removed by scrapers or other earthmoving equipment and redistributed or transported to a soil storage area. In final pit highwall reduction and first pit boxcut spoil areas, at

pond construction sites, along pioneering road corridors, at terrace or downdrain sites, along ramp/road final reclamation parcels, and for interfacing/blending final graded areas with topsoiled parcels, soil removed by dozers and/or graders will be pushed outside the

27

Revised

11/21/03

soil disturbance area and stored temporarily (less than one year) in furrows. furrow areas are not depicted on Drawing 85210.

These

This soil will either be respread over The

adjacent final graded slopes or will be transported to an approved stockpile site.

soil removal operation is continually checked and supervised by reclamation personnel to assure complete removal of all required soil, and to prevent contamination of that soil by any soils that would not be considered suitable.

Overburden Removal

Procedures.

Overburden that will be used as soil supplements, and

therefore has been delineated based upon sampling, is removed in much the same manner as soil. Soil supplements may be handled throughout the year. Once the planning,

instruction, and pre-removal investigations are complete, the overburden is drilled and blasted or ripped, depending on its degree of induration or lifted undisturbed if nonindurated, and moved to the redistribution site. Soil supplements are typically not

stockpiled; however, if the need arises, such stockpiles will be designated and shown on the Mine Plan Map, Drawing 85210. The removal and redistribution processes are supervised by reclamation personnel.

Suitable rough-graded spoil and spoil piles that will be used as soil supplements are moved using dozers, trucks and front-end loaders/shovels, or scrapers. The equipment to

be used is determined by the amount of material and distance the material must be moved. Spoil may be handled throughout the year.

Proof of Salvage.

Proof of salvage activities are used to document the volume of soil and

soil supplements salvaged for reclamation.

The soil survey and soil depth maps are utilized to determine areas where suitable soil exist. The results of the highwall sampling plan are used to determine areas where The salvage depths and actual yardage removed usually recorded. and The soil scientist record and/or salvage As the

suitable supplemental material exists. (based on qualified equipment load counts) are

reclamation personnel

periodically observe

occasionally

depths of cut banks and soil islands on topographic base maps or photographs.

materials are being removed, a generic photo is sometimes taken to show the profile and depth of the soil being removed. soil depth maps and sampling data. The records thus obtained are cross-referenced to the The photographic record, and the volume and location

information is prepared by or under the supervision of qualified reclamation personnel. Records are kept on file for inspection and reference at the mine site.

Revised

11/21/03

Soil Stockpiling Plans

Soil stockpile sites for each mining area are shown on Drawing 85210.

Proposed piles for

each pit area have been assigned a "pit area-XX" or "pit area-LP" designation on Drawing 85210. Identification numbers will be assigned sequentially by the field reclamation

supervisor or soil scientist as the piles are constructed.

Soil stockpile locations are selected collectively by the reclamation, operations, and engineering departments. The criteria used in the selection process are:

1.

Stockpiles must be located in areas that will not interfere with the mining operation;

2.

Stockpiles boundaries;

are placed

within

the

lease, permit, and projected disturbance

3.

Stockpiles are located as close as possible to salvage and redistribution sites; and

4.

Stockpiles are located

in

stable areas where wind

and water

erosion, and

contamination are minimized.

If it is necessary to move a stockpile without redistributing the stored materials on graded spoils, regulatory authorities are contacted for approval prior to disturbance of the stockpiles.

Soil stockpiles will at times be located on final graded spoil to:

1.

Keep the stockpiles as close as possible to the salvage and redistribution areas;

2.
3. 4.

Keep the piles out of future coal recovery areas; Prevent the piles from being relocated; and Minimize projected disturbance areas.

Revised

11/21/03

Soil stockpiles that are or will be located on final graded spoil are identified and shown on Drawing 85210. Stockpiles will be located in stable areas and the spoil will be graded The spoil at the

according to the Surface Stabilization Plan criteria in Chapter 26.

stockpile sites will be sampled for suitability using methods described in the Graded Spoil Sampling Plan section of this chapter.

Stockpile sites located on final graded spoil will be reclaimed using methods described in the Material Redistribution Plans section of this chapter. Soil will not be mixed with

spoil during reclamation because an abrupt smooth boundary occurs at the interface between these materials. The soil/spoil interface is easily identified by an abrupt color change,

texture or grain size difference, change in consistency, and/or the presence of coal, scoria, sandstone, or shale chips in the spoil medium. Sufficient soil will remain in the

stockpile during reclamation to blend the site with the surrounding soiled areas, and to adequately cover spoil as described in the Material Redistribution Plans section of this chapter.

Stockpile dimensions, slopes, and volumes vary based upon total salvage volumes, the configuration of the stockpile location site, equipment ingress and egress routes, and proximity to access roads. Within these constraints, PWCC typically constructs stockpiles Short and long axis side slopes

that are oblong in shape with a rounded cross section. are typically restricted to a maximum 4:l slope.

The long axes of the stockpiles are erosion when possible within

oriented with prevailing wind patterns to minimize wind terrain restrictions.

The profiles of the stockpiles are kept as low as possible within

the slope and volume constraints.

Pursuant to 30 CFR 816.22(c)(2)(iii), topsoil stockpiles will be protected from wind and water erosion using effective conservation practices including either or a combination of vegetation establishment, ripping or tillage to create surface roughness, mulching, berms, ditches, sediment traps, and alternate barriers such as hay bales and silt fence. Wind

and water erosion is minimized by surface roughness and/or establishing a vegetation cover on the stockpiles (Chapter 23). Stockpiles that will remain in place less than one year

will be ripped or otherwise have the surface roughened to protect the soil against wind and water erosion. Stockpiles that will remain in place for more than one year are seeded This mix is comprised of quick establishing

with the soil stockpile stabilization mix. perennial species.

The stockpiles are then mulched at a rate of 2.0 tons per acre to

provide stabilization in the interim between seeding and plant cover establishment.

30

Revised

11/21/03

Berms, ditches,

and/or sediment traps will be constructed

and maintained

around the

perimeter of the stockpile, when necessary, to minimize the loss of stockpiled material resulting from surface water runoff on the stockpile and from adjacent terrain. These

berms, ditches, sediment traps, and/or alternate barriers will be constructed or placed to retain the material at the stockpile site or to divert water away from the stockpile. Berms, ditches, and/or sediment traps will be constructed from material located near the stockpile site and may consist of soil, weathered overburden, and/or spoil. Small

temporary earthen ditches and berms or an alternate barrier such as hay bales or a geotextile fabric such as silt fence will be used. The typical ditch would be a minimum

of one foot deep w i t h asymmetrical side slopes of 1:l berms would

(H:V) and 2:l.

Small temporary

also be typified by the above ditch dimensions.

The lowest practicable

longitudinal grades will be maintained.

Locations exhibiting a low interception potential

for incoming surface water runoff are chosen for soil stockpiles.

The berms, ditches, sediment traps, and/or alternate barriers will typically only be constructed and maintained where stockpiles are located on steep slopes, where vegetation establishment is delayed, where runoff from the pile is not routed through a sediment pond, or where runoff will displace soil to a potential contamination or loss area (pit, ramp, haul roads, etc.). often not be used Berms, ditches, sediment traps, and/or alternate barriers will around the perimeter of those stockpiles where the

or maintained

vegetation cover has been adequately established or on short duration, low profile, narrow linear piles located between final graded spoil and recently topsoiled areas. This latter

type of soil stockpile is very short-term, meaning it will be respread over the final graded spoil during the next favorable seeding season. The footprint of this type of

stockpile is not static, but will progress forward in unison with the existing pit. Therefore, the exact centerpoint location may not always be depicted on the Mine Plan Map, Drawing 85210. Wind and water erosion will be minimized by the shape, location, surface Additionally, displaced soil, if any, will

roughness, and life expectancy of this pile.

be deposited either on final graded spoil or recently topsoiled areas, thereby preventing any soil loss or contamination. This type of pile will not be bermed, seeded, or mulched.

Final protection measures for soil stockpiles include fencing and sign placement.

When

necessary, soil stockpiles are fenced to limit disturbance of the stockpiled material, protect the vegetation, and prevent compaction and contamination. Identification sign(s) Mine

(see Chapter 25) are placed in a prominent location(s) around the stockpiles.

31

Revised

11/21/03

personnel are instructed that soil stockpiles are not to be disturbed or contaminated. The signs serve as continuing reminders to personnel that stockpile areas are to be preserved and not disturbed.

Material Redistribution Plans

Graded Spoil Sampling and Analysis Plans.

Following the completion of grading within

logical reclamation units and often prior to redistribution of soil and supplemental material, the graded spoil in all mining areas is sampled to identify the extent and nature of unsuitable materials. centers. The spoil is sampled using a grid pattern with 330-foot

At each sample point on the grid, spoil samples are collected to a minimum depth Representative samples are collected by or under the supervision of the

of three feet.

soil scientist at the 0 to 1 and 1 to 3 foot intervals using conventional sampling techniques. points. The qualified field sampler also inspects the surface-spoil between grid

If a significant change in the spoil characteristics is found between grid

points, additional sample sites are located accordingly.

The parameters and criteria used to evaluate spoil suitability are given in Table 17 and Figure 1. The parameters and criteria are based upon the characteristics of the

overburden found in the sampling program (Chapter 8) and spoil quality as identified by postmine soil-spoil pedon data and final graded spoil data (PCC, 1988 and PWCC, 19932003). The list represents those characteristics of the Black Mesa overburden and spoil Analyses will be performed in the Field, laboratory, and

that are likely to be deleterious to plant growth.

field, at the mining complex, or at an independent soil lab. quality control procedures are presented in Table 18.

The following special criteria are applicable for boron, selenium, and SAR evaluations. The hot-water-soluble boron (HWS-B) analysis will only be included in the analytical suite for future soil and overburden baseline assessments where there is no existing HWS-B data, spoil collected from the N10 reclamation area, and future reclamation areas where problem levels of HWS-B have been identified in the overburden. Problem levels of HWS-B shall be

defined by mixing criteria established by Dollhopf et al. (1978). HWS-B will be included on the parameter list for spoil whenever unsuitable HWS-B levels comprise more than

5 percent of the associated premine overburden section.

In all instances, HWS-B will only

Revised

11/21/03

TABLE 17

Maximum Threshold Limits for Evaluating Recently Graded Spoil at the Black Mesa Mining complex(')

Major Root Zone Parameter (Subsoil-Spoil)
0

Minor Root Zone (substratum-Spoil)

to 1 feet

1 to 3 feet

pH (sat.paste)

SAR
<20%

clay

20-35% clay >35% clay

Texture Clay
%

~ock Fragments

%(3)

>2 mm(by volume)

>3 inch (by volume)

Calcium Carbonate Equivalent % ( 3 ) Acid-based potential ( 4 ) (ABPI Boron, ppm ( 5 1

Selenium, ppm(6) Total (Set) Hot Water Soluble (Ses) AB-DTPA (See) >2.5 20.26
>0.31

33

Revised

11/21/03

TABLE 17 (Continued) Maximum Threshold Limits for Evaluating Recently Graded Spoil at the Black Mesa Mining Complex ( 1 )

Parameters and maximum threshold limits are based on OSMRE (1998) and site-specific justificati.ondocuments that PWCC submitted to OSMRE in September 1998, November 1998, January 1999, February 1999, January 2000, and August 2001.
(2)

Suitable maximum SAR values for the minor root zone substratum spoil must be in the slight to no reduction zone of the infiltration hazard classes adapted from Ayers and Westcott (1989) as shown in Figure 1. These suitability criteria are used only for the 0 to 1 and 1 to 3 foot increments of special reclamation areas including steep slopes, key habitats, cultural plantings, and main drainage channels where supplemental surface plant growth media are used. Units are tons calcium carbonate equivalent per 1000 tons of material. Suitability levels based upon correspondence from OSMRE (August 6, 1987). The acid potential must be calculated from pyritic sulfur as specified in the New Mexico guidelines. The hot water soluble boron analysis will only be included in the analytical suite for future soil and overburden baseline assessment where there is no existing HWS-B data, spoil collected from the N10 reclamation area, and future reclamation areas where problem levels of HWS-B have been identified in the overburden. In all instances, HWS-B will only be determined for very dark gray to black carbonaceous shale and black weathered coal strata. The hot water soluble and AB-DTPA extractable selenium analyses and standards will generally be used independently of each other at the BMMC because these two techniques are highly correlated with each other.

(3)

(4)

(5)

'

(6)

Revised

11/21/03

v

0

I n

0 '

Revised 031 15/02

TABLE 18

Parameter, Procedure, and Reference List for Evaluating Postmine Soil and Spoil samples(')

Parameter-Units

Procedure-Reference

Preparation of saturated paste and extract pH (determination using saturated paste) Conductivity of saturation extract in mmhos/cm at 25OC Calcium content in the saturation extract in meq/l Magnesium content in the saturation extract in meq/l. Sodium content in the saturation extract in meq/l SAR

USDA (1969), Methods 2 88.

&

3a, pp.84

&

USDA (1969), Method 21a, p. 102.

Sandoval and Power (1978), Method 1, pp. 22-24. Sandoval and Power (1978), Method 2, pp. 24-26. Same as Calcium

Same as Calcium

USDA (19691, p. 26

Particle size analysis in % sand, silt
&

Black (1965), Method 43-5,p 562-566.

clay

Textural classification Acid Potential. than 0) Sulfur fractionation

Sobek et al. (19781, Method 3.2.6, p. 60-62. 60 mesh sieve. Acid potential must be calculated from pyritic sulfur as recommended by Sobek et al. (1987), New Mexico MMD (1987) and OSMRE (1988a).

in % (determined when ABP is less

Neutralization potential in CaCO
3

Sobek et al. (1978), Method 3.2.3, p. 47-50. 60 mesh sieve.

per acre furrow slice.

36

Revised

11/21/03

TABLE 18 (Continued)

Parameter, Procedure, and Reference List for Evaluating Postmine Soil and Spoil Samples
(1)

Parameter-Units Acid base potential (ABP) in tons CaCO per acre furrow slice Visual Features (Field test)
3

Procedure-Reference

Smith et al. (1974), p. 48-49. sieve.

60 mesh

Source rock in spoil materials will be visually assessed for the presence and abundance of pyrite, sulfur, gypsum, carbonaceous material, coal fines, etc.

Calcium Carbonate Equivalent (2)

(%)

USDA (1969). Method 27a, p. 197

Rock ~ragments")

(%

by Volume)

Arbitrary grid and/or transect traverses as recommended by SCS (1971). Method 2.7, p. 2.7-1.

Selenium, ppm (Soluble or AB-DTPA extactable)

Soltanpour and Workman (1980) or Black (1965), Method 80-3, p. 1122. Also, Page (19821, Section 3-5.5.4, p. 61

Selenium, ppm (Total)

Page (1982), Method 27-5.2, p. 494-498 and Bajo (1978)

oro on'^),

ppm (Soluble)

Black (19651, Method 75.4. Method 200.7 ICP.

EPA 600,

PWCC will also adhere to the following quality assurance and quality control
program recommended by OSMRE, 1988b: The quality assurance and control program will include: A. B. C. Personnel qualifications. Detailed collection, storage, and sample preparation procedures. Laboratory procedures and modifications thereof used by the laboratory with statistical data justifying such modifications.

Revised

11/21/03

TABLE 18

(Continued)

Parameter, Procedure, and Reference List for Evaluating Postmine Soil and Spoil Samples
(1)

D.

Laboratory equipment with modes of operation, reaction times, response times, recorder speeds, etc. Quality control data will include:
a.

E.

Standard reference materials;

b. Duplicate sample results reported with data; c. Referee sample data; and d. Laboratory quality control data, including statistical variability for parameters requested, detection limits, sensitivity values, and concentration ranges of optimum detection.
(2)

Analysis completed only for the 0 to 1 and 1 to 3 foot increments of special reclamation areas including steep slopes, key habitats, cultural plantings, and main drainage channels. The hot water soluble boron analysis will only be included in the analytical suite for future soil and overburden baseline assessment where there is no existing HWS-B data, spoil collected from the N10 reclamation area, and future reclamation areas where problem levels of HWS-B have been identified in the overburden. In all instances, HWS-B will only be determined for very dark gray to black carbonaceous shale and black weathered coal strata.

(3)

Revised

11/21/03

be determined for very dark gray to black carbonaceous shale and black weathered coal strata. lithology. will HWS-B levels in overburden throughout the BMMC are closely correlated to

The hot water soluble and AB-DTPA extractable selenium analyses and standards used independently of each other at the BMMC because these two

generally be

techniques are highly correlated with each other.

Suitable maximum SAR values for the

minor root zone substratum spoil must be in the slight to no reduction zone of the infiltration hazard class adapted from Ayers and Wescott (1989) as shown in Figure 1.

The criteria in Table 17 will be used to assess suitability of the graded spoils and supplemental surface plant growth media. If one or more parameters fall within the

unsuitable range at a given grid point, additional sampling may be conducted at the midpoint between the four surrounding sample sites on the grid. The same sampling

procedures used on the grid will be followed.

Sampling will continue in this manner (one

midpoint sample surrounding the unsuitable gridded sample site) until the real extent of unsuitable material in the reclamation unit is determined. A reduced analysis list,

comprised of parameters that fall within the unsuitable range, will often be used at these phase 2 inter-sample sites that were selectively placed between 330-foot grid locations to verify spoil suitability. Unsuitable areas will be staked at the next adjacent suitable

sample site to identify the problem area and provide an adequate margin between unsuitable and suitable material.

On graded spoils that are determined to be suitable in all respects, twelve inches of soil
will be redistributed except the existing N-11 mining area, interim disturbance and

reclamation areas, and special reclamation areas requiring substrate-specific species.

A

topdressing of soil will often not be applied in special reclamation areas including key habitats, steep slopes, cultural plantings, or main drainage channels where the

supplemental surface plant growth media are determined to be suitable in all respects. This will result in

a

minimum

of

four

feet

of

suitable

plant

growth

media

for

revegetation.

The thickness of suitable material that will be redistributed on areas determined to have unsuitable spoil characteristics will be based upon the depth at which unsuitable

materials were encountered.

For example, if sampling identified a five-acre area that has

unsuitable characteristics in the 1 to 3 foot sample increment, the entire area will be covered with a minimum of three feet of suitable material.

If an area is encountered

where the depth to unsuitable material is variable and it is impractical because of size

39

Revised

11/21/03

to stake subareas for suitable material redistribution, the entire area will be covered with that quantity of suitable material required by the shallowest unsuitable interval encountered in the final graded spoil. It is not necessary to resample the redistributed

supplements to verify suitability prior to redistribution of soil materials because the material was sampled and determined to be suitable prior to salvage.

Graded

spoils that are determined

to be

unsuitable will

be covered with

soil or a (in special

combination of suitable overburden, supplemental surface plant growth media reclamation areas including drainage channels), and soil. key habitats,

steep slopes, cultural plantings, and main

The relative amounts of each kind of material that will be

used will be determined based on haulage distance, the need for rehandling or special handling, topographic position, postmine land use, substrate-specific specie requirements, and the availability of materials. In most situations, PWCC expects to use suitable In The

supplemental material for burial followed by an application of twelve inches of soil. situations where supplemental material is not available, soil will be used.

potentially available volume of s~upplementalmaterial is addressed elsewhere in this plan. In every case except the exlsting N-11 mining area, and interim disturbance/reclamation areas, a mlnimum-average of twelve inches of soil material will be used as a surface treatment unless residual soils and supplemental surface plant growth media are being utilized in key habitats, cultural plantings, and steep slopes, and a minimum total depth of
4

feet

of

suitable

material will be

will used

be to

redistributed reconstruct

for the

revegetation. subsoil when

Suitable available. An

supplemental

material

Insufficient soil is available at N-11 to meet the minimum twelve-inch average depth.

approximate average of 8 to 9 inches of soil will be redistributed in this mining area. The interim disturbance/reclamation areas will receive 0.5 feet of soil or more as

required by Permit AZ-0001.

PWCC will maintain records of the sampling results for each logical reclamation unit. Soil and topsoil supplement redistribution depth requirements will be mapped using 1" 400' aerial photography following the completion of sampling.
=

These records will be kept

on file at the mine site and will be submitted with each annual reclamation report.

Special Purpose Reclamation Areas.

PWCC uses supplemental surface plant growth media

(suitable overburden and spoil) and residual soils to establish certain substrate-specific

Revised

11/21/03

species, create wildlife habitat, and provide erosionally stable landscapes. slope, cultural planting, key habitat, and main drainage reclamation

These steep areas are

reconstructed to support the postmining land uses of rangeland grazing, wildlife habitat, and cultural plants. Suitable overburden and residual soils are used to create these

landscapes because these materials are inherently stable, have low erodibility potential, promote deep root growth and water/air movement, and reduce competition from shallowrooted herbaceous vegetation. structural landscape. diversity and These special purpose areas provide the potential for plant community diversity within the reclaimed and

increased

Justification for utilizing supplemental surface plant growth media

residual soils within steep slope, key habitat, cultural planting, and main drainage channel reclamation areas is presented in Attachment 22-2.

Soil testing and amendment applications for steep slope, key habitat, cultural planting, and main drainage channel reclamation areas will be implemented on an as-needed basis. Revegetation success monitoring and revegetation trials will be utilized within these reclamation areas as described in Chapter 23. Soil and spoil samples will be collected at

representative revegetation soil sample sites located in these special purpose reclamation areas to correlate revegetation data (including forage quality) with soil chemical and physical characteristics and materials in these areas. to verify the acceptability of using supplemental soil

The list of soil and spoil analyses will, at a minimum, include

all parameters listed in Table 17.

Mine Support Facilities. Mesa leasehold included

The existing and proposed mine support facilities for the Black steep slope reclamation areas. For temporary mine support

facilities affected land areas, due to the composition of the underlying bedrock material in excavation areas, the slope aspect, steepness of slope, or low potential for

revegetation success, etc., the reclamation and surface stabilization efforts may be hindered if existing soil and subsoil reserves are utilized (see "Steep Slope" section in Attachment 22-2). Therefore, suitable overburden or a minimum depth of six inches of non-

toxic, non-acidic rock mulch cover on the side slopes or backslopes in lieu of soil and revegetation may be utilized for temporary surface stabilization.

In addition, as an alternative, and based on suitable site conditions, the soil scientist or other competent professionals may still approve soil redistribution and revegetation in lieu of temporary revegetation and surface stabilization techniques for this type of site.

Revised

11/21/03

Once the support facility is no longer required to support mining, the facilities area will be reclaimed in accordance with the approved reclamation plan, utilizing permanent revegetation or surface stabilization techniques.

Redistribution

Procedures.

Plant growth media

are redistributed utilizing

scrapers,

dozers, front-end loaders, shovels or loaders and end-dumps, and miscellaneous support equipment; for example, road graders, water trucks, and farm tractors. Scrapers,

sometimes assisted by dozers, are used primarily to load and haul soil or supplements to the areas where redistribution is to occur. often as possible. PWCC direct hauls plant growth materials as

Soil and supplements are redistributed only on graded spoils that have been prepared for redistribution. Surface preparation of final-graded spoil is carried out to minimize the

potential for slippage of replaced soil and is performed during final backfilling and grading or after soil redistribution. The procedure is completed using surface mechanical The increased adhesion

manipulation techniques including deep ripping and chisel plowing.

created at the interface between the respective materials by these surface treatments minimizes slippage of the redistributed soil. Redistribution is performed whenever weather and soil moisture conditions permit. To the greatest extent possible, materials are

removed and replaced in a single operation.

Plant growth material is redistributed from soil storage piles, from soil material removal areas, and supplemental sources (highwalls, spoil piles, and rough-graded spoil). Uniform

redistribution of soil materials is accomplished by unloading scrapers when they are traveling at constant speed. Supplemental materials are unloaded from scrapers or end-

dumps in a similar manner to scrapers, or are dumped and graded depending upon slope conditions and the extent of the area being covered. Excessive compaction is minimized by

setting up circulation patterns for scrapers or other equipment that minimize or prevent travel over redistribution materials.

Soil will channels

not

be

replaced on certain downdrain alignments and

all main

reclamation Suitable (soil

(including the 15-foot apron on each side of the main channels). material will be utilized as a surface plant root growth

overburden

medium

supplement) for reclamation of main drainage channels.

The rationale for this approach is

to conserve that amount of soil material that would otherwise wash down the water

42

Revised

11/21/03

conveyance channels to the sediment ponds below reclaimed areas.

Also, the spoil has a If the location

high rock fragment content which will aid in armour-coating the channels.

of a downdrain is known prior to soil redistribution activities, soil will not be placed in the downdrain unless site-specific conditions indicate that portions of the downdrain would be stable. replacement, downdrain. Should the location of a downdrain or terrace be defined after soil removed in the immediate vicinity of the terrace or

the soil will be

The minimum width along the downdrain alignment that will not be soiled is This is based on a minimum estimated primary channel bottom width

approximately 45 feet.

of 15 feet with an additional 15 feet of width each side of the primary downdrain channel. In this manner, soil material loss will be minimized. Soil will be replaced on terrace

cut- and fill-slopes once construction has been completed.

Surface Stabilization and Erosion Control

Several procedures are used to minimize the potential for erosion on redistributed soil surfaces. Slope gradients are kept to a minimum within the confines of grading to

approximate original contours and topographic manipulation is practiced to reduce overland flow velocities systems, where postmine and runoff volumes. Also, the reestablishment of surface drainage These estimated drainage

necessary, are incorporated procedures

into the grading plans. in the surface

topography

are described

stability and

reestablishment plan

(Chapter 26) and shown on the annual Surface Stabilization Report

maps and on Drawing 85352.

Surface

stabilization

and

erosion

control

are

also

enhanced

by

mechanical

surface ripping,

manipulations.

Surface mechanical

manipulation

may include chisel plowing,

contour furrowing, contour ditching, slope tracking, land imprinting, pitting, or other methods of surface roughening to reduce surface runoff, increase infiltration, reduce surface erosion, and enhance the establishment of vegetative cover. contour furrowing are the primary methods to be used on the leasehold. Deep ripping and Generally, these

mechanical manipulation methods are applied after rough grading of the spoil material and soil redistribution are completed. These mechanical manipulation practices have been

developed largely for semi-arid and arid lands where water and soil conservation is critical. On mined lands in this region, several complementary treatments may be

necessary to offset scant soil moisture rainfall (nine to ten inches of

supplies resulting from average annual

(1) erratic and low (2) high

precipitation),

evapotranspiration, and (3) high runoff rates.

Equipment commonly used are modified

43

Revised

11/21/03

versions

of

rangeland,

agricultural,

and

industrial

implements

including

rippers or and

subsoilers, backhoes, scrapers, etc.

dozers, disks, harrows, rakes, tillers, drills, chiselers,

Deep ripping or chisel plowing are mechanical treatment measures used to shatter compacted layers and provide better mixing or contact at the soil-spoil interface. The purpose of

these treatments is to loosen and mix subsoil, improve root penetration and aeration, and increase infiltration and subsurface water storage. treat the top one to three feet of soil. Chisel plowing or ripping is used to

Chisel plowing does not provide as great a depth

benefit as ripping; however, because more chisel shanks are carried and the shank spacing is closer, a greater proportion of surface material is affected in the approximate one foot effective operating depth of the chisel implement. Chisel plowing is also an

effective tool for mulch incorporation and reducing annual weed growth.

Though chisel

plowing can provide positive benefits, it is felt that deep ripping will provide a greater range of effectiveness. Thus, ripping will be the primary method used, while chisel

plowing will only be used as a backup method in case of equipment breakdown or other logistical problems.

Upon completion of final grading and replacement of soil, contour ripping with multiripper shanks spaced 3 to 5 feet apart will be carried out to depths ranging from one to three feet. Ripping will typically extend through the replaced soil across the soil-spoil Replaced drainages, key habitat, cultural planting,

interface and into the upper spoil.

and steep slope reclamation areas where soil is not respread, will be included in the areas ripped. The drainages will be ripped perpendicular to their channel length,

increasing the roughness coefficient of the channel and the opportunity for additional infiltration and less runoff. Deep ripping breaks or shatters compacted layers that tend

to inhibit root development and restrict the zone from which plants can extract soil water and nutrients. Branson et al. (1966) found that ripping rangeland with large rippers that Studies conducted by

created lasting furrows increased forage production by 160 percent.

Dortignac and Hickey (1963) and Hickey and Dortignac (1964) determined that ripping on a rangeland research area in New Mexico reduced runoff by as much as 96 percent and erosion by
85 percent

the

first

year

after

treatment.

Three

years

following

the initial

treatment, runoff still was 85 percent less than the control with 31 percent less erosion. While the effects of ripping on reclaimed lands at Black Mesa may vary from the above because of site and climatic differences, the above studies indicate the potential

44

Revised

11/21/03

benefits of these practices.

The increased plant growth and vigor resulting from the

practice will also provide additional erosion and land use benefits.

The ripping operation can be expected to cause a certain amount of blending of soil and spoil. It may also expose a certain amount of coarse material at the surface. This will

not interfere with the revegetation process and will benefit the reclaimed landscape by creating additional microhabitat, increasing the potential for runoff detention storage, reducing evaporative surface areas, and reducing the kinetic energy of falling raindrops.

For schematics of ripping implements and land surface patterns,

see Chapter 26.

In

addition to standard farm subsoilers, construction equipment with large single-shank or multi-shank rippers may be used to loosen the soil.

Contour furrowing and ditching are mechanical manipulations that roughen the soil surface, creating small trenches and grooves parallel to the slope contour. Contour furrowing and

ditching are used on topsoiled areas to reduce runoff and soil erosion and enhance the establishment of vegetative cover. Of the two, contour furrowing will be the primary

method used on reclaimed lands on the Black Mesa leasehold.

Following soil or supplemental surface plant growth media replacement and ripping, the reclaimed lands will be contour furrowed using a modified offset disk. The modified disk

is a large off-set type disk with the standard front disk gang retained and the rear gang modified to include a 36-inch diameter disk spaced every 36 inches. This creates furrows The front

on the reclaimed landscape that are 9 to 14 inches deep with 36-inch spacings. unmodified disk gang aids in seedbed preparation.

Contour furrowing is a standard range improvement practice used to control runoff, reduce erosion, and retain water on slopes for increased plant growth and forage production

(Valentine 1971).

For reclai.med lands, contour furrows increase surface roughness and This reduction in runoff translates into Simons, et

provide for catchment and retention of runoff.

reduced erosion, increased infiltration, and increased plant available water. al.

(1983) stated contour furrows can increase infiltration up to 10 fold and decrease Typically, contour furrows are 8 to 12 inches deep and

runoff by as much as 84 percent.

are spaced 7 to 20 feet apart, with the furrows dammed every 4 to 20 feet (WET, Inc. 1986). Contour furrowing has been and continues to be practiced at the Black Mesa and

45

Revised

11/21/03

Kayenta Mines.

Furrows are not dammed; however, the furrow spacing of only 36 inches is Thus, the

less than half the lower interval spacing of 7 feet as described above. contributing periodically area for each furrow is relatively small. on the contour

Furrows need not be dammed Quality control

if they

are placed

(Valentine 1971).

procedures will insure that furrowing is done on the contour whenever practicable.

The discussions presented above for ripping and contour

furrowing are to provide an

indication of the immediate potential benefits of these practices when applied to the reclaimed areas. Dixon
(1975), in his discussion

of the air-interface concept

for

infiltration, showed that a micro-rough, macro-porous interface (on the surface of the landscape) will improve control of runoff, reduce flash flooding, erosion, sedimentation, and nonpoint source pollution, improve control of soil water and ground water recharge, and reduce plant water stress with resultant increased growth rates. that a rough open surface has the characteristics necessary to He further showed for a highly

allow

functional

exchange of water and air across the soil surface which

results in high

infiltration rates.

A number of authors (Scholl 1985, Schuman et al., 1987, Aldon et al.,

1980) have shown that surface manipulations, as described above, measurably benefit the establishment, development, and sustained growth of vegetation in reclaimed areas. Thus,

the development and maintenance of an effective and permanent vegetative cover is the means by which erosional and landform stability will be maintained over the long term.

Slope tracking and land imprinting are surface manipulation practices used in arid areas that form microfurrows or microbasins in the soil to reduce runoff, increase infiltration, and pond water for increased plant growth. Slope tracking and land imprinting create firm This type

seedbeds and microsites beneficial to seedling germination and establishment.

of surface manipulation roughens the surface with wedges or other geometric impression patterns that are approximately four inches deep, depending on soil compaction, soil texture, soil moisture, and weight of the implement. creates lightly swollen depressions. Slope tracking with a dozer usually

Vegetation that is present at the time of the The microbasins have been

operation is crushed and spread on the surface as a mulch.

found to perform successfully in concentrating small amounts of rainfall on arid lands though the length of time for effectiveness of the operation is reduced when operating in coarse textured soils. In addition to farm implements (cultipackers), track construction

Revised

11/21/03

equipment or sheeps foot roller equipment can also be used to form the imprint pattern. Specialized imprinting equipment such as the Dixon Land Imprinter are also available. These specialized types of imprinters are based on large drum rollers with angle iron welded to the surface to create geometric patterns. The Dixon Land Imprinter was (1975) in his air-earth

developed to provide the type of surface discussed by Dixon interface concept.

The furrows can collect up to 2 inches of rainfall and rough, rocky

terrain with slopes up to 45 percent can be treated (Larson, 1980).

Pitting, a valuable water conservation and erosion control measure in arid and semi-arid regions, is a mechanical treatment that creates small basins or pits. This 1930's era

practice is done with modified disk pitters, drum or rotary pitters, and modified listers. The most practical pitting equipment to be considered for use at Black Mesa are modified disk plows. The primary modification involves the mounting of eccentric disks, deeplyThe pits created are three to five feet

notched, or cutaway disks to create the pits.

long with a four to eight-inch depth and an eight to twelve-inch width (Valentine, 1971). The pits reduce runoff, concentrate water for increased infiltration, and provide

favorable microsites for vegetation establishment and development.

While pitting provides

positive benefits to plant establishment and development on seeded ranges, pits may only last three to five years in the semi-arid Southwest (Barnes et al., 1958), especially if coarse textured soils are encountered.

As stated earlier, the primary surface mechanical manipulations to be employed at the Black Mesa and Kayenta Mines are deep ripping and contour furrowing. be used in lieu of ripping where Chisel plowing may be used as an

conditions allow and pitting may

alternative to contour furrowing.

Land imprinting and slope tracking are to be used in

specialty situations such as rill and gully repair or areas of steep slope reclamation.

Traffic on redistributed soil surfaces will be kept to a minimum.

Revegetation treatments

such as seeding, mulching, and fertilization will be conducted on the contour to maintain furrow integrity and to reduce the potential for formation of surface imprints that could conduct downslope water flow. All slopes are mulched or cover cropped. The methods and

application rates are described in Chapter 23.

Finally, the Revegetation Plan (Chapter

23) is designed to achieve revegetation in a contemporaneous manner, using plant species with high utility for stabilizing the soil surface from erosion.

Revised

11/21/03

Plan Modification

The graded spoil sampling grid, sampling depths, and sampling methods described herein will be evaluated and modified from time to time based on the site-specific data

collected. accordance

The amount of suitable soil that with the sampling results and the

is salvaged will amounts and

also be adjusted in suitable

availability of

supplemental material.

Any changes in the plan as outlined above will be submitted to the

regulatory authority for approval prior to implementation.

Nutrients and Soil Amendments

Soil testing and amendment applications are addressed in the Fertilization section of Chapter 23. practice. PWCC does not add fertilizer amendments to reclaimed areas as normal

Special reclamation areas have received nutrient and microbial supplements.

Approximate Original Contour

None of the components of this plant growth media reconstruction plan will alter PWCC's compliance with plans for achieving approximate original contour found in Chapters 21 and 26 or as depicted on Drawing 85352 and shown on maps presented with the annual Surface Stabilization Report.

Revised

11/21/03

Literature Cited Aldon, Earl F., David G. Scholl, and Charles P. Pase. grasses on mine spoils. Vol. 1. York, N.Y.
p. 91-97.

1980.

Establishing cool season

In: Proceedings of the 1980 Watershed Management Symposium,

Irrigation and Drainage Division, American Society of Civil Engineers, New

Ayers, R.C. and D.W. Westcott.

1989.

Water Quality for Agriculture.

FA0 Irrigation and

Drainage Paper No. 29, Rev. 1. Bajo, S. 1978. Total

Rome. p. 174. the HN03/HCLOq HF digestion.

selenium determination using 50:649 1958.

Analytical Chemistry

Barnes, O.K., Darwin Anderson, and Arnold Heerwagen.

Pitting for Range Improvement USDA Prod. Res. Report No. 23.

in the Great Plains and the Southwest Desert Regions. Black, C.A. P. Branson, F.A., R.F. Miller, and I.S. McQueen. ripping on rangelands of the Western U.S. Dixon, R.M. Utah. 1975. 1966. 1965. Methods of Soil Analysis, Part 2

-

Chemical and Microbiological 1572

Properties.

American Society of Agronomy Monograph No. 9, Madison, Wisconsin.

Contour furrowing, pitting, and 19(4):182-190. In Proceedings

J. Range Mgmt.

Infiltration Control Through Soil Surface Management.

of the Irrigation and Drainage Division Symposium on Watershed Management, Logan,

August 13-15, 1975.

Dollhopf, D.J., J.D. Goering, C.J. Levine, B.J. Bauman, D.W. Hedberg, and R.L. Hodder. 1978. Selective Placement of Coal Stripmine Overburden in Montana, Spoil Mixing Montana Agricultural Experiment Station Research Report 135. 68 p. 1963. Surface Runoff and Erosion as Affected by Soil Montana Phenomena.

State University, Bozeman. Dortignac, E.J. and W.C. Hickey. Ripping.

USDA Misc. Pub. No. 970:156-165.

Hickey, W.C. and E.J. Dortignac. 1964. An Evaluation of Soil Ripping and Soil Pitting on Runoff and Erosion in the Semi-arid Southwest. Ass. Sci. Hydrol., Land Erosion. Pub. 65:22-33. Larson, J.E. 1980. Revegetation Equipment Catalog. Equipment Workshop (VREW). U.S. 198 p. 1987. Overburden and Soils Inventory and Prepared for the Vegetative Government Printing Office, Int. Union Geodesy and Geophys. Int. Soil Moisture, Comm. Precipitation, Hydrometry.

Rehabilitation and Washington, D.C.

New Mexico Mining and Minerals Division. Handling Guidelines. OSMRE. 1988a. Santa Fe. 16 p.

Soil and Overburden Analytical Methods.

Denver, Colorado.

Revised

11/21/03

OSMRE.

1988b. Quality Assurance and Quality Control Program Guidelines.

Denver,

Colorado. OSMRE. 1998. Overburden Sampling and Analytical Quality Assurance and Quality Control Western

(QA/QC) Requirements for Soils, Overburden, and Regraded Spoil Characterization and Monitoring Programs for Federal Lands in the Southwestern United States. Regional Coordinating Center, Denver, CO. Page, A.L. 1982. Methods of Soil Analysis, Part 2

-

Chemical and Microbiological

Properties, Second Edition. Wisconsin. 1159 p.

American Society of Agronomy Monograph No. 9, Madison,

Peabody Coal Company (PCC).

1988.

Vegetation, Wildlife, and Soil Resources 1986 Report Flagstaff, Arizona. Report prepared for: The

for the Black Mesa and Kayenta Mines. Colorado. Peabody Coal Company (PCC). 1992.

Office of Surface Mining Reclamation and Enforcement, Western Service Center, Denver,

1988-1991 Minesoil Reconstruction Report for the Flagstaff, Arizona. Report prepared for: The

Kayenta Mine 5-21 Coal Resource Area. Colorado. Peabody Western Coal Company (PWCC). Reports prepared for:

Office of Surface Mining Reclamation and Enforcement, Western Service Center, Denver,

1993-1999.

1992-1998 Minesoil Reconstruction and Flagstaff, Arizona.

Revegetation Activities Reports, Black Mesa and Kayenta Mines. Western Division Center, Denver, Colorado. Peabody Western Monitoring Coal Company (PWCC). and 2000-2003.

The Office of Surface Mining Reclamation and Enforcement,

1999-2002 Reclamation Status and Kayenta, Arizona. Reports

Reports, Black Mesa

Kayenta Mines.

prepared for: The Office of Surface Mining Reclamation and Enforcement, Western Division Center, Denver, Colorado. Sandoval, F.M. and J. F. Power. 1978. Laboratory Methods Recommended for Chemical USDA Handbook

Analysis of Mined-Land Spoils and Overburden in Western United States. No. 525, Washington, D.C. 31 p. Scholl, D.G. 1985.

Vegetation and soil water response to contour furrows, dozer basins, p. 217-220.

and surface additions of topsoil or power plant ash on arid coal spoils. Mining and Reclamation. Denver, Colorado. October 8-10, 1985.

In Proceedings of the Second Annual Meeting of the American Society for Surface

Schuman, G.E., F. Rauzi, and G.S. Howard. modification in mined land reclamation.

1987.

Vegetation response to soil surface

Reclamation and Revegetation Research, Vol.

6, No. 1:49-54.
Simons, Li
&

Associates, Inc.

Design of Sediment Control Measures for Small Areas in

Surface Coal Mining.

May, 1983.

Revised

11/21/03

Smith, R.M., W.E. Grube, Jr., T. Arkle, Jr., and A. Sobek. for Soil and Water Quality. Washington, D.C. Sobek, A.A., W.A. Schuller, J.R. Freeman, and R.M. Smith. Methods Applicable to Overburdens and Mine Soils. Environmental Protection Agency, Washington, D.C.

1974.

Mine Spoil Potentials

EPA-670/2-74-070. U.S. Environmental Protection Agency.

1978.

Field and Laboratory U.S.

EPA-600/2-78-054.

Sobek, A.A., L. R. Hossner, D.L. Sorenson, P.J. Sullivan, and D.F. Fransway. base potential and sulfur forms. of America, Ankeny, Iowa.

=:

1987.

Acid-

Reclaiming Mine Soils and Overburden in the Soil Conservation Society

Western United States Analytic Parameters and Procedures.
p. 233-258.

Soil Conservation Service (SCS). Procedures.

1971.

Handbook of Soil Survey Investigations Field

U.S. Government Printing Office, Washington, D.C. 1980. Use of ammonium bicarbonate-DTPA soil test to Communications in

Soltanpour, P.N. and S.M. Workman.

assess availability and toxicity of selenium to alfalfa plants. Soil Science and Plant Analysis 11:1147-1156. United States Department of Agriculture (USDA). 1951. Soil Survey Staff.

Soil Survey Manual edited by the 503 p.

Agricultural Handbook No. 18, Washington, D.C. 1969.

United States Department of Agriculture (USDA). Saline and Alkali Soils. Valentine, J.F. 1971.

Diagnosis and Improvement of

Agricultural Handbook No. 60, Washington, D.C. 160 p. Brigham Young University

Range Development and Improvements. 516 p. 1986. Joint

Press, Provo, Utah.

Water Engineering and Technology (W.E.T., Inc.). Coal Association (American Mining Congress

Sediment control goals and Phase 1 report to the National Committee on Surface Mining

alternatives at surface mines in the semi-arid west: Regulations). 127 p.

Revised

11/21/03

distribution system (Drawing 85324).

Several types of permanent water sources now or will exist on the PWCC leasehold as a result of mining activities (pre-existing and (Drawing 85324). pre-law and They include pre-existing springs, wells approved or proposed postlaw internal

replacement),

impoundments, water control structures (ponds), public water standpipes, and intermittent reaches of ephemeral channels. Chapter 14, Land Use, contains a comprehensive discussion

of these permanent water sources in the section entitled "Postmining Water Sources".

Nineteen permanent internal impoundments currently exist that are available for livestock and/or wildlife use as a part of the postmining landscape Drawing 85324). (Chapter 9, Facilities, and

Three are located in the N-2 coal resource area (N2-RA, wildlife habitat The remaining 16 are pre-law and post-law internal impoundments (J3-G and five other unnamed impoundments), J-1

only; N2-RB; and N2-RC).

located in the 5-3 coal resource area

coal resource area (Jl-RA and J1-RB), N-8 coal resource area (N8-RA), and the N-1 coal resource area (Nl-RA and six unnamed impoundments). that hold water from time to time. Additional pre-law depressions exist

However, they are not considered permanent water

sources due primarily to restricted watersheds and climatic variation.

PWCC is also proposing to build one additional internal impoundment in the J19 coal resource area (J19-RB). This structure is intended to improve postmine water source

distribution and habitat in that area of the leasehold.

PWCC also will retain 31 existing and

future sediment control

structures

(permanent

impoundments) to provide surface water bodies for livestock and wildlife in addition to those previously identified. The impoundments include nine existing MSHA structures: J7 Twenty smaller, existing

Dam, J7-Jr, J2-A, J16-L, J16-A, N-14H, N14-G, N14-F, and N14-D. sediment control structures are also included.

They include J3-D, J3-E, N5-A, N6-L, N11-

G, J7-R, TPF-D, TPF-E, N7-D, J16-G, J21-A, J21-C, J27-RA, J27-RB, J27-RC, N7-E, N10-A1, N10-D, N11-A, and N12-C. Two sediment ponds scheduled for construction during the

remaining life-of-mining activities are also proposed and include N10-G and J21-I.

These

existing and proposed ponds all meet or will be upgraded to meet the permanent pond design criteria. Their size, configuration, and upstream watersheds indicate persistent They will

water retention (see the discussion of Permanent Impoundments, Chapter 6).

also provide water of good quality for their intended uses (see Chapter 14, Land Use).

Revised 11/21/03

Two public water standpipes have been constructed by PWCC on the leasehold. located on Drawing 85324, are connected to the N-aquifer potable water

These sites, distribution

system and provide excellent water in terms of quality and quantity.

These sources of

water are available for further development as livestock and wildlife watering areas, should the Tribes desire their retention in the postmining land use plans.

Maintenance and Management

PWCC's program for the maintenance and management of revegetated areas includes, but may not be limited to, the following elements: monitoring; interseeding, reseeding and

augment planting; weed control; rodent control; fencing and fence maintenance; erosion monitoring; rill and gully repair and drainage maintenance; mowing; and grazing.

The maintenance and management activities related to interseeding, planting and weed control are based upon the performance of

reseeding, augment stands as

revegetated

determined by quantitative annual vegetation monitoring and qualitative field inspection activities. When quantitative measurements indicate that a revegetated area is not

making reasonable progress with regard to the establishment of a diverse, effective and permanent vegetation cover, the site may be lnterseeded, augment planted or tilled and reseeded as necessary to improve the stand characteristics in the area. The activity or

activities will be directed towards the specific problem or problems identified by the quantitative information or qualitative observations.

Criteria used to determine if rangeland vegetation development is occurring at a desired rate may be based on qualitative of seeded and/or areas quantitative be the evaluation of seeded to stands. if

Qualitative monitoring reseeding is necessary.

will

primary

method

determine

Qualitative evaluation of two to three year old seeded stands If quantitative evaluation is used,

has proven suitable for reseeding determinations.

seedling density information will be used to compare the number of established perennial plants/ftz in the reclaimed area to the following standard: excellent (0.75 or more); good (0.5 to 0.75); fair (0.25 to 0.5); and poor (less than 0.25) (Valentine 1971).

Seeded stands of rangeland will be evaluated by the end of the second growing season following seeding. PWCC will interseed or reseed stands that fail to meet the fair

evaluation criterion after the end of the second full growing season, or if qualitative

Revised 11/21/03

TABLE 1 Index of Maps, P l a n s and Cross S e c t i o n s Drawing Number Title Volume

Land Use Map Black Mesa L e a s e s , Right-of-Ways Permit Area Anasazi S i t e s w i t h Mining Areas H i s t o r i c S i t e s w i t h Mining Areas Anasazi S i t e s w i t h Compliance S t a t u s , Mining Areas and Excavated S i t e s J-7 Area J-19 Area J-21 Area N-6 Area
N-11

and

T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic C r o s s S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t i o n T y p i c a l Geologic Cross S e c t l o n T y p i c a l Geologic Cross S e c t i o n Mine Plan Map Order 3 and 4 S o i l Survey

Area

5-2 Area J-4 Area J-6 Area J-8 Area J - 9 Area J-10 Area J-14 Area J-15 Area J-23 Area J-28 Area N-9 Area N-10 Area N-12 Area N-99 Area 85210 85300

Revised 1 1 / 2 1 / 0 3

TABLE 1 Index of Maps, Plans and Cross Sections Drawing Number Title Order 1 and 2 Soil Survey Topsoil Salvage Map Soil Type and Topsoil Salvage Map Geobotanical Study Map Vegetation and Wildlife Habitat Map Mixed Conifer Woodland Habitat Great Horned Owl and Red-Tailed Hawk Breeding Sites Pre-Existing Livestock and Wildlife Watering Sources Postmining Livestock and Wildlife Watering Sources Drill Hole Collar Location Map Estimated Postmining Topograghic Map (1"=4001) Generic Watershed Jurisdictional Permit and Affected Lands Map Drainage Area and Facilities Map (lM=400') MSHA Dam Location Map Sediment and Water Control Structures Map (1"=20001) Siltation
&

Volume

Impoundment Structure Data

Impoundments Hazard Map J2-A Dam J-7 Dam J16-A Dam J16-A Dam J16-L Dam J16-L Dam Remedial Plan J16-L Dam As-Built KM-FW Pond N14-D Dam N14-E Dam N14-F Dam N14-G Dam N14-H Dam

Revised 11/21/03

TABLE 1 Index of Maps, Plans and Cross Sections Drawing Number Title Typical Road Sections Typical Intermittent or Perennial Stream Ancillary Road Crossing 85440 85442 85445 85450 85460 and 85460A 85462 85466 85466A 85480 85480 85480 85480 85480 85480 85480 85482A 85484 85486 85488 85490 and 85490A 85494 85495 85600 85610 85611 85613 85613A 85620 J-19 Haul Road J-19 Deadhead/Haul Road Spur Permanent Roads Map N7-D Sedimentation Structure Grading Plan J2-A Dam, J-3 Airstrip J-3 Airstrip (As-Built) J-3/N-6 Access Road Design J-3/N-6 Access As-Built Road Plans Black Mesa Mine Facilities (Sheet 1A) Kayenta N7/8 Facilities (Sheet 2A) Central Warehouse and Operations Facilities (Sheet 3A) Reclamation and J-3/N-6 Facilities (Sheets 4A, 4B, 4C Kayenta N-14 Facilities (Sheet 5A) Kayenta Mine Facilities (Sheet 6A) Kayenta Transfer 22/23 and Temporary Facilities (Sheet 7A) N-11 Truck Dump/Facilities Site Plan As-Built N-11 Haul Road Spurs J-19 Ramp 46 to 60 Deadhead Road J-19 West: South Primary Haul Road Concrete Ford of Yellow Water Canyon Wash Proposed N-11 Extension North Primary Haul Road Proposed N-11 Extension South Primary Haul Road Historical Environmental Monitoring Sites Wepo Aquifer Water Level Contours 2003 Wepo Aquifer Water Level Contours Overburden and Impact Core Location Map Overburden and Impact Core Location Map (2003 Core Data) Alluvial Aquifer Water Level Contours
&

Volume

4D)

Revised 11/21/03

TABLE 1 Index of Maps, Plans and Cross Sections Drawing Number Title Regional and Local USGS Hydrological Monitoring Sites 85635 85640 85642 85642A 85646 85700 85710R Local USGS Hydrological Monitoring Sites Periodic Wet Reaches Map Stream Buffer Zone Map At-Grade Road Crossing/Stream Buffer Zone Map J-3 Landfill Grading Plan Moenkopi SEDIMOT I1 Subwatershed Boundaries Coal Mine SEDIMOT I1 Subwatershed Boundaries Coal Mine Wash SEDIMOT I1 Postmining Watershed Boundaries 7, 8 & 9 89800 93500 94700 94720 Bonding Map Current Environmental Monitoring Sites Blast Monitoring Map Preblast Survey Site Map 23 Volume

23
23 23 23 23 23

23
23

23 23

Revised 11/21/03

APPENDIX A-1

2003 SOIL SURVEY REPORT

LIFE OF MINE COAL RESOURCE AREAS BLACK MESA MINING COMPLEX

2003 SOIL SURVEY REPORT LIFE OF MINE COAL RESOURCE AREAS

BLACK MESA MINING COMPLEX

Submitted to: Peabody Western Coal Company Black Mesa Mining Complex - P.O. BOX 650 Kayenta, Arizona 86033

Submitted by: James Nyenhuis Certified Professional Soil Scientist, ARCPACS #2753 600 Ramah Drive Fort Collins, Colorado 80525

October 2003

TABLE OF CONTENTS
Page I0 . 2.0 INTRODUCTION.................................................................................................. I

METHODS ........................................................................................................... 2 2.1 Order 2 Soil Survey ................................................................................... 2 RESULTS AND DISCUSSION ............................................................................ 4 3.1 Soil Survey Maps ...................................................................................... 4 3.2 Soil Map Unit Legend................................................................................ 4 3.3 Soil Map Unit Descriptions........................................................................ 4 3.4 Soil Series ................................................................................................. 5 3.4.1 Soil Series Names........................................................................... 5 3.4.2 Soil Series Taxonomic Classification.............................................. 5 3.4.3 Soil Series Descriptions .................................................................. 5 3.5 Soil Moisture Regime and Soil Reclassification........................................ 6 3.6 Soil Laboratory Results ............................................................................. 7 3.7 Topsoil Suitability and Salvage Depth Recommendation......................... 7

3.0

October 2003

LlST OF TABLES

Table
1

Paae
2003 Soil Survey Map Unit Legend .......................................................................... 15 Current Correlation of Soil Series on the Black Mesa Lease Area .......................... 16 Taxonomic Classification of Soil Series on the Black Mesa Lease Area ................17 2003 Life of Mine Coal Resource Areas Soil Survey - Recommended Soil Salvage Depths.................................................................................................. 18 2003 Life of Mine Coal Resource Areas Soil Survey - List of Dug Soil Holes and Soil Characteristicsfor Each Coal Resource Area (N9, NIO, N12/N99S, N99N, JUJ15, J4, J6lJ14, J8, J9, J10, J28) .........................20

2
3 4 5

LlST OF ATTACHMENTS

Attachment
1

Approval Letter from Office of Surface Mining (OSM) Regarding Proposed Soils Scope-&Work (SOW); and OSM Soil Suitability Table "Topsoil and Topsoil Substitute Suitability Criteria for the southwestern United States" Black Mesa Lease Area - Map Unit Descriptions (Intermountain Soils, Inc. 1985) NRCS Official Soil Series Descriptions Black Mesa Mine: J9 Coal Resource Area Soil Laboratory Data

2

3
4

October 2003

LIST OF MAPS

N9 Soil Type & Topsoil Salvage Map (Drawing File Name NOS-SOIL.DWG) N10 Soil Type & Topsoil Salvage Map (Drawing File Name N10SOIL.DWG) N12-N99S Soil Type & Topsoil Salvage Map (Drawing File Name Nl2-N99SS0lL.DWG) N99N Soil Type & Topsoil Salvage Map (Drawing File Name N99NSOIL.DWG) J2-J15 Soil Type & Topsoil Salvage Map (Drawing File Name J2J15SOIL.DWG) J4 Soil Type & Topsoil Salvage Map (Drawing File Name J04-SOIL.DWG) J6-J14 Soil Type & Topsoil Salvage Map (Drawing File Name J6J14S0IL.DWG) J8 Soil Type & Topsoil Salvage Map (Drawing File Name J8-SOIL.DWG) J9-J10 Soil Type & Topsoil Salvage Map (Drawing File Name J9-SOIL.DWG) J28 Soil Type & Topsoil Salvage Map (Drawing File Name J28-SOIL.DWG) J23 Corridors Soil Type & Topsoil Salvage Map (Drawing File Name J23SOIL.DWG)

October 2003

1.0 INTRODUCTION The identification and proper management of topsoil resources in the various Coal Resource Areas of the Peabody Western Coal Company (PWCC) Black Mesa Lease Area is essential for: (1) the successful reclamation of any areas that might be disturbed during project activities and (2) the achievement of the post-mining land use. The information presented in this report is designed to aid in the formulation of a practical and successful reclamation plan. A detailed Order 2 soil survey of the various Life of Mine Coal Resource Areas was completed as required by the Office of Surface Mining (OSM). Approximately 18,973 acres were included in the 2003 Black Mesa Mining Complex Soil Survey as follows: Coal Resource Area N9 Coal Resource Area NIO Coal Resource Area N12lN99S Coal Resource Area N99N Coal Resource Area J2lJ 15 Coal Resource Area J4 Coal Resource Area J6lJ14 Coal Resource Area J8 Coal Resource Area J9 Coal Resource Area J10 Coal Resource Area J28 J23 Coal Transportation Corridors 2345 acres 1794 acres 2773 acres 1645 acres 1664 acres 524 acres 2343 acres 717 acres 550 acres 592 acres 1406 acres 2620 acres

The federal Office of Surface Mining (OSM) was contacted prior to the start of soils field work to ensure all requirements were met with this study. Only small portions of N10, N12, and N99N were included in the previous PWCC Order 1 and Order 2 Black Mesa Lease Area soil survey (Intermountain Soils, Inc. 1985). All of the areas had been previously mapped to the less detailed Order 3 and Order 4 level of intensity (Intermountain Soils, Inc. 1985).

October 2003

2.0 METHODS

2.1 Order 2 Soil Survey A detailed soil survey was conducted during the summer of 2003 on approximately 15,803 acres associated with all of the various coal resource areas listed above except J9 (550 acres) and the J23 Coal Transportation Corridors (2620 acres). The J9 Coal Resource Area and the J23 Coal Transportation Corridors were mapped in the summer of 2000. These surveys have been added to the 2003 Life of Mine Coal Resource Areas Soil Survey for a grand total of approximately 18,973 acres. The soil survey used the existing Peabody Black Mesa Lease Area soils map unit legend (Intermountain Soils, Inc. 1985), except many of the previous slope classes were combined into broader slope range map units. For instance, previous map unit 1A (Dulce very channery fine sandy loam, 1 to 4 percent slopes) was combined with map unit 1B (Dulce very channery fine sandy loam, 4 to 8 percent slopes) to create map unit IAB (Dulce very channery fine sandy loam, 1 to 8 percent slopes). Based on previous discussion with OSM personnel, no soils were to be sampled for laboratory characterization unless new soils were identified and mapped that were not on the previous soils legend. Attached to this report is a copy of a letter from Mr. Jerry D. Gavette (OSM Leader, Black MesaIKayenta Mine Team) to Mr. Brian Dunfee (PWCC Environmental Engineering Manager) concurring with a previously submitted proposed soils scope-of-work letter from Mr. Dunfee to Mr. Gavette which remains on file at both PWCC and OSM. Soils description, classification, and mapping was conducted in accordance with the procedures and standards of the National Cooperative Soil Survey (Soil Survey Staff 1993 and 1999; and Schoeneberger et. al. 2002). The mapping was delineated on Peabody 1"=4001rectified orthophotoquad maps with topographic contour overlay. The photography date was September 3, 1997. The Coal Resource Areas study area boundaries are outlined on the maps as well. The soil resources of the study area were investigated by Jim Nyenhuis and Tim Overdier, both Certified Professional Soil Scientists, during the summer of 2003. Jim Nyenhuis completed the J9 Coal Resource Area and J23 Coal Transportation Corridors surveys during the summer of 2000. Based on previous discussion, the various Coal Resource Areas were mapped to the Order 2 level of intensity. The entire areas were traversed by vehicle and on foot. Soil map unit boundaries were initially delineated by exposing soil profiles using a sharpshooter and bucket auger as well as observing topographic, geomorphic, vegetation, and geologic conditions. The primary tool for soil observation was the use of a backhoe. A total number of 555 holes were dug across the study area, approximately 90 percent of which were dug by backhoe. The backhoe was able to dig to 12 feet or deeper in the very deep alluvial soils under sagebrush vegetation, and to and into the weathered bedrock contact in the very shallow and shallow residual soils dominantly under Pinyon-Juniper woodland vegetation. 2 October 2003

The current study also benefited from experience gained in 1996 during which approximately 175 backhoe pits were dug throughout the Black Mesa and Kayenta Mines and adjacent areas. Soil profiles from these pits were described, photographed, and sampled for selective laboratory characterization. The J9 Coal Resource Area and J23 Coal Transportation Corridors soil survey were previously completed in the summer of 2000. Thirty soil profiles were fully described in the J9 soil survey area, most from deep backhoe pits. Numerous soil profiles were tested with a sharpshooter and bucket auger in the J23 Coal Transportation Corridors survey area but no descriptions were recorded. No new soils were encountered on the J9 and J23 corridors study areas, and therefore no soils were sampled for baseline laboratory characterization although four samples were collected for deep salvage suitability evaluation.

October 2003

3.0 RESULTS AND DISCUSSION 3.1 Soil Survey Maps The detailed soil survey maps for the various Coal Resource Areas and J23 Coal Transportation Corridors are presented on Drawing 85305C ( I 1 sheets total). Each base map is a rectified orthophotoquad with topographic contour overlay. The map scale is 1"=4001. The soils map unit legend, all field sample sites, and recommended soil salvage depths are provided on the maps as well. The maps were digitized by PWCC from the original soil field maps which are kept in the PWCC archive. 3.2 Soil Map Unit Legend The map unit legend contained in the previous Black Mesa Lease Area soil survey (Intermountain Soils, Inc. 1985) was used for the 2003 soil survey except certain slope classes were combined. No new soils were identified, and no new map units were necessary for the current survey. The revised map unit legend is provided as Table I , 2003 Soil Survey Map Unit Legend. Based on recent taxonomic reclassification of three soils by the USDA Natural Resources Conservation Service (NRCS), the site-specific Peabody soils that were previously named Cahona, Pulpit, and Sharps had been recorrelated as part of the J9 Coal Resource Area and J23 Coal Transportation Corridors soil surveys conducted in 2000, and those changes were also used in the current 2003 soil survey. The soil that was named Cahona is renamed Blanding. An "ustic-aridic" soil moisture regime modifier has been added to the Pulpit and Sharps soil names (Pulpit, ustic-aridic; and Sharps, ustic-aridic). Because these soils are not new soils, but rather recorrelated to different soil names or soil name modifiers, they were not sampled for baseline laboratory characterization. 3.3 Soil Map Unit Descriptions Map unit descriptions are contained in the previous Black Mesa Lease Area soil survey, and can be used for the 2003 soil survey. Attachment 2 is a copy of the map unit descriptions taken from the previous survey (Intermountain Soils, Inc. 1985). The soil name "Blanding" should be substituted for "Cahona" in the map unit name for Map Units 10, IOA, ?OBI IOC, 11, I I A , I I B , I I C , G11C, X11, XIIA, XIIB, andX11C. Similarly, the soil name "Pulpit ustic-aridic" should be substituted for "Pulpit" in the map unit name for Map Unit 5. And finally, the soil name "Sharps ustic-aridic" should be substituted for "Sharps" in the map unit name for Map Units 6, 6A, 6B, and 6C.

October 2003

3.4 Soil Series

Table 2 lists the soil series currently identified and mapped on the Black Mesa Lease Area. The table also shows the soil correlation changes over time on the lease area, beginning with the 1979 Espey Huston & Associates soil survey (Espey, Huston, 8( Associates, Inc. 1980), and continuing with the 1984 Mariah Associates soil survey, the 1985 Intermountain Soils soil survey, and ending with the 2000 and 2003 Nyenhuis soil surveys of the additional areas of the Black Mesa Lease Area.

This soil list could change in the future if there are additional NRCS taxonomic andlor soil correlation changes for these soils, or if new soils are identified on newly mapped areas.
Table 5 lists all 555 soil holes that were dug and described during soil survey field activities. These holes were distributed across the 11 Coal Resource Areas as follows: N9, 2345 acres, 82 holes; N10, 1794 acres, 62 holes; N121N99S12773 acres, 70 holes; N99N, I645 acres, 52 holes; J2lJ15, 1664 acres, 61 holes; J4, 524 acres, 17 holes; J6lJ14, 2343 acres, 49 holes; J8, 717 acres, 28 holes; J9, 550 acres, 30 holes; JIO, 592 acres, 44 holes; and J28, 1406 acres, 60 holes.

Table 5 is subdivided into the 11 Coal Resource Areas. Areas N12 and N99S are combined into one area, as well as areas J2 and J15, and areas J6 and J14. Each area contains a numeric listing of all soil holes dug, as well as for each hole the soil name, soil map unit symbol, depth to rock, and any pertinent comments including whether the hole received a brief soil profile description.
.. . 3.4.2 Soil Series Taxonnmic Classlflcatlon

Table 3 provides the current taxonomic classification for the soils of the Black Mesa Lease Area. This information was obtained in September 2003 from the official NRCS web site.
. . 3.4.3 Scu1 Series Descrq&ms

Because no new soils were identified and mapped on the 2003 Soil Survey area, the collection of soil samples and additional detailed profile descriptions were not necessary. Numerous detailed soil profile descriptions for each of the soils on the Black Mesa Lease Area are contained in the previous soil survey report (Intermountain Soils, Inc. 1985). In addition, there were approximately 175 detailed profile descriptions completed from deep backhoe pits in 1996 (one half of which were on nondisturbed native areas), and an additional 30 detailed soil profile descriptions were completed during the summer of 2000 for the Black Mesa J9 Coal Resource Area.

A copy of the current NRCS official soil series descriptions for each of the soils mapped on
the 2003 soil survey area is attached to this report (Attachment 3). All of these soils are active, established soil series. Please refer to the NRCS descriptions for additional 5 October 2003

information as needed. The series descriptions included the following soils: Begay, Blanding (formerly Cahona), Bond, Cahona, D u b , Las Lucas, Oelop, Pulpit, San Mateo, Sharps, Travessilla, and Zyme. 3.5 Soil Moisture Regime and Soil Reclassification One of the issues in the previous soil survey was the determination of the proper "soil moisture regimeJ'. The original soil survey considered the lease area to be dominately "typic-aridic" (Espey, Huston & Associates, 1980). However, the NRCS considered the area to be a slightly wetter "aridic-usticJJ. In order to resolve this difference, a letter was written in early 1985 to NRCS seeking information concerning the inter-relationships among soil moisture regime, mean annual precipitation, vegetation, and soil characteristics particularly in northeast Arizona (letter to Mr. R. Kover, SCS West National Technical Center, Portland Oregon, April 22, 1985). No reply was received by late 1985, and the soil moisture regime for the lease area was subsequently changed by Intermountain Soils to "ustic-aridic" (see discussion on pages 6, 7, and 8 of the Soil Resources of the Black Mesa Lease Area, lntermountain Soils, Inc., 1985). The "ustic-aridic" soil moisture regime is midway between the drier "typic-aridic" and the wetter "aridic-ustic". Because the soil moisture regime was considered to be "ustic-aridic", all of the soil names used in the 1985 soil survey were correlated to this moisture regime. This included the Cahona, Sharps, and Pulpit soil series. All three soils were classified as "Fine-silty, mixed, mesic Ustollic Haplargids". Cahona is a very deep soil, and Sharps and Pulpit are moderately deep. In 1992 the NRCS held a "Four Comers Moisture and Temperature Meeting" in order to adopt consistent criteria for use in moisture and temperature classifications in the four state region (NRCS, 1992). Although no site-specific information was presented for the Black Mesa area, two sites in northeast Arizona were discussed. Navajo Mountain (6020 feet elevation, 9.34 inches mean annual precipitation, 49.6 degrees mean annual temperature) was considered "ustic-aridic". Teec Nos Pos (5290 feet elevation, 7.99 inches precipitation was considered "typic-aridic". Based on these two Arizona sites, and other sites in the Four Comers Area, the Black Mesa lease area would be consistent with an "ustic-aridicJJ moisture regime placement. Site-specific data also supports this conclusion. Sixteen years of precipitation data has been collected by Peabody at three sites on the Black Mesa Lease Area (sites 1, 8, and 12). The average annual precipitation between 1983 and 1998 was 8.7 inches with a general range of 8 to 10 inches. The high and low values during this time period were 3 inches (1989) and 11.6 inches (1997) (Esco Associates, 1998). As a result of these data, the conclusion reached by lntermountain Soils in 1985 for the Black Mesa Lease area appears correct, and the area should be considered "ustic-aridic".

6

October 2003

As part of the overall changes adopted at the Four Corners meeting, NRCS reclassified Cahona, Sharps, and Pulpit soils from an "ustic-aridic" to a slightly wetter "aridic-ustic" moisture regime. Cahona is now classified as a "Fine-silty, mixed, superactive mesic Calcidic Haplustalf'. Sharps and Pulpit are classified as "Fine-silty, mixed, superactive, mesic Aridic Haplustalfs". Because the Black Mesa Lease Area is in an "usti~aridic",not "aridic-ustic", moisture regime, the Cahona, Sharps, and Pulpit soil names are no longer appropriate. The Blanding soil series is similar in morphology to Cahona but is "ustic-aridic" and therefore Blanding is suitable for use on the Black Mesa Lease Area (Sasser, 2000). Neither the Sharps nor Pulpit soils currently have an "ustic-aridic" soil counterpart. Therefore, these soil names have been retained for the current survey, but an "usticaridic" has been added to the name for use in the lease area. In the future there may be new names for an "ustic-aridic" Sharps and Pulpit, but there are none at the present time. 3.6 Soil Laboratory Results The previous Black Mesa Lease Area soil survey did identify a few high salinity andlor sodicity values at depth in some of the alluvial soils adjacent to drainages. In 2000 when the J9 soil survey was conducted, it was proposed that some of the deep alluvial material be sampled in the field from deep backhoe pits, and analyzed in the laboratory to determine whether values might exceed suitability levels for electrical conductivity (EC>12) and adsorbed sodium (SAR>12 to 15 depending on soil texture). Four soil samples were collected in the J9 Coal Resource Area. One sample was collected from the 80 to 108 inch depth interval of Blanding (formerly Cahona) fine sandy loam at soil hole #J9-26. Three soil samples were collected from Begay very fine to fine sandy loam: from the 76 to 108 depth interval of soil hole #J9-18, and from the 80 to 89 depth interval of soil hole #J9-24. Attachment 4 is the Inter-Mountain Laboratories (Farrnington, New Mexico) soils data for the four samples. The following parameters were included in the laboratory analysis: pH, EC, SARI texture (sand, silt, and clay), and Acid Base Potential ABP (total sulfur %, total sulfur Vkt, neutralization potential tltk). Discussion of the soil analysis results is included in the following section. 3.7 Topsoil Suitability and Salvage Depth Recommendation A topsoil suitability evaluation and salvage depth recommendation was completed for all soils in the previous Black Mesa Lease Area soil survey (Intermountain Soils, Inc. 1985). Because no new soils were found during the current survey, the previous evaluations were considered the starting point for use in the 2003 soil survey. However, the soils and map units were reevaluated based on site-specific data.

October 2003

The major change from the previous survey is the recommendation of soil salvage of shallow residual soils under Pinyon-Juniper vegetation. Previously, all # I map units (1, IA, IB, IC, and ID), #3 map units (3A, 3BC, 3C, 3D, 3E, 3DE, and 3F), #4 map units (4B, 4C, 4D, and 4E), #7 map units (7B, 7C, 7D, and 7E), and #I6 map units (16C, 16E, and 16F) were not recommended for soil salvage based on high content of surficial rock fragments, clay content of the Zyme soil, erosion status, and shallow nature of the soils (Intermountain Soils, Inc., 1985). The previous report does state these soils (Dulce, Zyme, Travessilla, and Ustic Torriorthents) do not have any chemical properties limiting soil suitability. The concept of soil suitability has evolved since 1985. The presence of gravel (2mm to 3") and cobble (3" to 10) size rock coarse fragments, including sandstone channers and shale chips, is not considered limiting or unsuitable for coarse fragment content as high as 35 to 45 percent. The State of Utah Division of Oil, Gas, and Mining (UDOGM) has even removed coarse fragment content as a criterion in their current soil suitability table (UDOGM, 2002). The presence of 15 to even 50 percent sandstone channers and shale chips predominantly on the surface of residual soils such as D u b , Zyme, and Travessilla should not be considered unsuitable for salvage, especially when the overall volume of available soil is limiting. This range of coarse fragment content can be beneficial for erosion resistance and should not create droughty conditions in the reclaimed soil profile. Additionally, coarse fragment content often decreases in the underlying soil horizons above the weathered bedrock contact. Soil erosion itself is not limiting for salvage. It makes the actual salvage operation more difficult but does not make the remaining soil material unsuitable. Shallow soils (less than 20 inches to bedrock) are not by definition unsuitable. There is just less soil material to salvage. Soil depth as low as 6 inches can be salvaged. However, soil salvage may not be feasible in the steeper portions of certain map units that approach 40 to 50 percent slopes due to equipment limitations and operator safety concerns. In addition, the upper part (up to 1 foot in thickness) of the weathered sandstone or shale bedrock (the "paralithic" Cr horizon) in residual soils is also suitable for salvage, if needed. This weathered upper bedrock material was consistently observed in backhoe pits to have many roots and no signs of salinity andlor sodicity. The soil backhoe easily and consistently dug through this upper bedrock material. Furthermore, the current contract salvage operators at Black Mesa have coined a term for this material, "toprock", and consider it to be suitable soil or soil substitute material available for salvage if and when needed. Based on extensive backhoe pit observations, it is recommended that approximately 0.5 foot of suitable soil material be salvaged from residual soils (Dulce, Zyme, Travessilla) under Pinyon-Juniper vegetation, especially when soil resources are limited and these soils are needed for successful reclamation. Actual average depth of residual soil to the weathered sandstone or shale bedrock contact is slightly deeper, but has been rounded to the nearest 0.5 foot. Map units 3F (Ustic Torriorthents-Rock Outcrop, 50 to 80% slopes) and 7E (Zyme-Travessilla-Rock Outcrop complex, 30 to 50% slopes) continue to have no 8 October 2003

recommended salvage due to steep slopes and rock outcrop.
Table 4 is a list of recommended salvage depths for soils in the 2003 Black Mesa Lease Area (Coal Resource Areas N9, N10, N12-N99SI N99N1J2-J15, J4, J6-J14, J8, J9, JIO, J28, and J23 Coal Transportation Corridors). The list includes an overall recommended salvage depth for each map unit as well as differentiated "Topsoil" and "Subsoil" salvage depths as an additional option for some map units. Based on Peabody practice, salvage depths are listed to the nearest 0.5 feet.

The following is a discussion of recommended salvage depths for each map unit. Table 5 lists the 555 soil observations and soil characteristics from which the following data evaluation and salvage recommendationswere generated.
Map Unit IAB (Dulce very channery fine sandy loam, I to 8 percent slopes) is composed of the shallow, residual D u b soil and generally occupies sloping uplands under Pinyon-Juniper vegetation. Duke was observed in 50 backhoe pits in Map Unit IAB and averaged 9 inches to the weathered bedrock contact. Duke very channery loam ranged in depth from 5 to 18 inches. Soil inclusions (Zyme, Bond, Pulpit, Sharps, and Travessilla) were observed in another 16 backhoe pits within Map Unit IAB, and averaged 19 inches to bedrock with a soil depth range of 6 to 32 inches. Soil inclusions comprised about 24 percent of Map Unit IA. The recommended soil salvage depth for Map Unit 1A is 0.5 feet, with the concept that all soil to weathered bedrock contact is suitable and could be salvaged where deeper than 0.5 feet. Map Unit 1CD (Dulce very channery loam, 8 to 30 percent slopes) is similar to Map Unit IAB except for slope. Dulce was observed in 5 backhoe pits in Map Unit 1CD and averaged 12 inches to the weathered bedrock contact, with a depth range of 9 to 20 inches. Blanding very fine sandy loam was observed to 54 inches in one additional backhoe pit. Because only 5 Dulce backhoe pits were dug in Map Unit ICD, the average 12 inch soil depth was reduced to a conservative recommended salvage depth of 0.5 feet in order to be consistent with Dulce in Map Unit IAB. Map Unit 2B (Bond very fine sandy loam) is composed of the shallow Bond soil and generally occupies gently sloping upland areas under a sagebrush and mixed grasses vegetation. Delineations of Map Unit 2B are also mapped in gently sloping open PinyonJuniper woodland. A total of 37 backhoe pits were dug in Bond very fine sandy loam, and these averaged 14 inches to the weathered bedrock contact, with a depth range of 8 to 20 inches. Soil inclusions were observed in another 13 backhoe pits (comprising 26% of the total observation in Map Unit 2B) and these averaged 22 inches in depth with a range of 6 to 72 inches.

-

'

Bond has an overall recommended salvage depth of 1 foot, the rounded average depth to sandstone or shale bedrock. All soil parameters are suitable. The upper 0.5 feet (the surface "A" horizon and the underlying "Bt" argillic horizon) have higher organic matter content than below and could be salvaged as an upper or "topsoil" lift. The underlying 0.5 feet to the bedrock contact could be salvaged as a lower or "subsoil" lift. The previous survey also recommended a salvage depth of 1.0 feet. 9 October 2003

Map Units 3AB, 3CD, and 3DE (Zyme-Duke complex) are composed of shallow residual soils under Pinyon-Juniper vegetation. Map Unit 3AB had 15 backhoe pit observations and 1 soil inclusion and averaged 9 inches to the weathered bedrock contact with a soil depth range of 3 to 18 inches. The total recommended salvage depth is rounded to 0.5 feet.
Zyme and Dulce soils were observed in 45 backhoe pits in Map Unit 3CD and averaged 8 inches to the weathered bedrock contact with a soil depth range of 3 to 17 inches. Three additional backhoe pits had soil inclusions which averaged 17 inches to bedrock. The overall total recommended salvage depth of Map Unit 3CD is rounded to 0.5 feet. Zyme and Dulce soils were observed in 14 backhoe pits in Map Unit 3DE and averaged 8 inches to the weathered bedrock contact with a depth range of 3 to 18 inches. Two additional backhoe pits had soil inclusions that averaged I 4 inches to bedrock. The overall total recommended salvage depth of Map Unit 3DE is rounded to 0.5 feet. Topsoil salvage may not be feasible in the steeper portions of this map unit that approach 40 to 50 percent slopes due to equipment limitations and operator safety concerns.

Map Unit 3F (Ustic Toniorthents Rock Outcrop Complex) Soils in Map Unit 3F are not recommended for salvage due to the high percentage of Rock Outcrop and very steep slopes. This map unit often has bedrock ledges and cliffs. Map Units 4AB and 4CD (Zyme very channery loam) are composed of Zyme clay loam on shale influenced sideslopes and ridges scattered throughout the study area. Although Zyme was observed many times in backhoe pits in other map units, it was not inventoried in Map Units 4AB and 4CD. It is assumed that Zyme has similar characteristics in all map units in which it is a component, and therefore the overall total recommended salvage depth for Map Units 4AB and 4CD is 0.5 feet. Map Unit 5 (Pulpit, ustic-aridic, very fine sandy loam) is composed of the moderately deep Pulpit soil over hard sandstone bedrock. Pulpit is located on gently sloping uplands. Vegetation is a mix of sagebrush, mixed grasses, and scattered Pinyon-Juniper. Pulpit was observed in 27 backhoe pits and averaged -28 inches to sandstone bedrock with a depth range of 20 to 39 inches. Soil inclusions were observed in an additional 17 backhoe pits (comprising about 38% of the map unit) and averaged 45 inches to bedrock. The weighted average soil depth for Map Unit 5 is 35 inches. The total recommended salvage depth for Map Unit 5 is rounded to 3 feet. The previous survey recommended a salvage depth of 2.5 feet. The upper 1.0 feet (the surface "A" horizon and the underlying "Bt" argillic horizon) could be salvaged as an upper or "topsoil" lift. The underlying 2 feet to the bedrock contact could be salvaged as a lower or "subsoil" lift. Map Units 6AB and 6C (Sharps, ustic-aridic, very fine sandy loam) are composed of the moderately deep Sharps soil and are located on gently sloping to sloping uplands dominantly under a sagebrush and mixed grasses vegetation. Sharps was observed in Map Unit 6AB in 36 backhoe pits and averaged 29 inches to the shale contact, with a depth range of 20 to 39 inches. Soil inclusions were observed in an additional 12 pits (comprising about 25% of the map unit) and averaged 41 inches to bedrock. The weighted average soil 10 October 2003

-

'.

.~-

depth of Map Unit 6AB is 32 inches. The total recommended salvage of Map Unit 6AB is rounded to 2.5 feet. The upper 1.0 feet (the surface " A horizon and the underlying "Bt" argillic horizon) could be salvaged as an upper or "topsoil" lift. The underlying 1.5 feet to the bedrock contact could be salvaged as a lower or "subsoil" lift. The previous survey also recommended a salvage depth of 2.5 feet. Sharps very fine sandy loam in Map Unit 6C was observed in 6 backhoe pits and averaged 33.5 inches to the shale bedrock. No inclusions were observed. The total recommended -salvage depth is rounded to 2.5 feet. The previous survey also recommended a salvage depth of 2.5 feet.
Map Units 7B (Travessilla-Zyme-Dulce complex); and 7CD and 7E (Zyme - Travessilla - Rock Outcrop complex) are composed of shallow soils over sandstone and shale

bedrock. They are located on weathered upland ridges with scattered rock outcrop and have dominantly Pinyon-Juniper vegetation. Soils in Map Unit 7B were observed in 13 backhoe pits and averaged 10 inches to bedrock with a depth range of 4 to 20 inches. No inclusions were noted. Soils in Map Unit 7CD were observed in 8 backhoe pits and averaged 7 inches to bedrock with a depth range of 3 to 15 inches. The total recommended salvage depth of Map Units 7B and 7CD is rounded to 0.5 feet. Map Unit 7E is not recommended for salvage due to high amounts of Rock Outcrop and very steep slopes.
Map Units IOAB and 10C (Blanding very fine sandy loam, bedrock substratum); 11AB and 11C (Blanding very fine sandy loam); G l l B (Blanding very fine sandy loam, Blanding, bedrock gravelly substratum); and X I 1AB and X I 1C (Blanding substratum) are composed of very deep local alluvial and reworked aeolian soils on alluvial fans, flats, sideslopes, and toeslopes scattered across the study area. Blanding generally has a sagebrush and mixed grasses vegetation. Blanding was observed in a high number of backhoe pits, and the average depth to bedrock in Map Units 10AB and IOC is more than 6.5 feet with a depth range of 4.5 to 9 feet or more. The depth to very gravelly sandy loam, loamy sand, or sand and gravel texture is about 5 feet.

-

Blanding has low salinity (EC) and low sodicity (SAR) values. Although all soil parameters are technically suitable, the coarse texture below an average of 5 feet can lead to a droughty and erosion prone condition if this "sandy" material constitutes the surface layer after reclamation activities have been completed. The overall recommended salvage depth for Blanding in Map Units IOAB and 10C is 5 feet, the average depth until "sandy" material is encountered. The recommended salvage depth for a "topsoil" lift is 1 foot. The recommended salvage depth for an underlying "subsoil" lift is 4 feet. The average depth for Blanding in Map Units X I IAB, X I 1C, and G I 1B is 7.5 feet, and 10 feet for Map Units 1IAB and 11C. All of this material is suitable and constitutes the total recommended salvage depths for these map units. The upper foot of soil is recommended for a "topsoilJJ and the remaining material for the "subsoil" lift. lift
Map Units 12AB and 12C (Begay loam) are composed of the very deep alluvial Begay soil located on nearly level to strongly sloping terraces of drainages scattered throughout the study area. Total soil depth was an average of at least 9.7 feet. All soil parameters of 11 October 2003

Begay are suitable, although very gravelly loamy sand and sandy loam material can be encountered at depth in some areas. This material, when encountered, is droughty and has high erosion hazard. Overall recommended salvage depth is rounded to 9.5 feet. The upper 1.5 feet, including the surface " A horizon and the underlying "Bw" cambic horizon, could be salvaged as a "topsoil" lift. The underlying 8 feet, or the depth to the dominantly very gravelly loamy sand contact, could be salvaged as a "subsoil" lift.
Map Unit 13A (San Mateo loam) is composed of fine-loamy material on nearly level to very gently sloping stream terraces, drainageway bottomlands, and floodplains. The .5 overall recommended salvage depth is 14.5 feet. The upper I feet (including the surface "A" horizon and the underlying upper part of the "C" horizon) can be salvaged as a "topsoil" lift. The underlying 13 feet can be salvaged as a "subsoil" lift. Individual delineations of San Mateo may have high electrical conductivity (EC) andlor high sodicity (Sodium Adsorption Ratio - SAR) at depths between 8 to18 feet which could limit subsoil salvage to more shallow depths in these areas. Map Unit 14AB (Oelop very fine sandy loam) is composed of the deep Oelop soil on gently sloping valley sideslopes and bottoms. The overall salvage depth is 9.5 feet. The upper 1.5 feet (including the surface "A" horizon and the underlying "Bt" argillic horizon) can be salvaged as a "topsoil" lift. The underlying 8 feet can be salvaged as a "subsoil" lift. Map Unit 15A (Las Lucas sandy clay loam) is composed of the very deep Las Lucas soil located on terraces and drainage bottomlands throughout the study area. The overall recommended salvage depth is 11.5 feet. The upper 1.5 feet can be salvaged as a "topsoil" lift, and the underlying 10 feet as a "subsoil" lift. The previous survey recommended a maximum salvage depth of 11.6 feet. Map Units 16C, 16CE, and 16F (Soil A- Soil B extremely channery very fine sandy loams) are composed of soils on crests, summits, and sideslopes of some hills scattered across the study area. These soils formed in porcellanite (scoria) and contain a very high volume of rock fragments. These soils were previously considered unsuitable for salvage due to their very high rock fragment content. However, these soils have been selectively salvaged at Black Mesa with positive results. Fifteen soil backhoe pits were dug in Map Unit 16C and fifteen in Map Unit 16CE. Soil depth averaged 6 inches for Map Unit 16C, with a depth range of 4 to 18 inches. Soil depth for Map Unit 16CE averaged 10 inches, with a depth range of 2 to 27 inches. The total recommended salvage depth for these map units is rounded to 0.5 feet. Topsoil salvage may not be feasible in the steeper portions of Map Unit 16CE that approach 40 to 50 percent slopes due to equipment limitations and operator safety concerns. Map Unit 16F is not recommended for salvage due to very steep slopes, from 50 to 70 percent or greater.

October 2003

Map Unit DL (Disturbed Land) is composed of various delineations of previously disturbed areas. There is no soil for salvage within these disturbed areas. Map Unit P (Pond) contains various constructed ponds distributed across the study area. There is no soil for salvage within these delineations although the pond and embankment "soil materials" will be tested for suitability when the ponds are reclaimed. Map Unit RL (Reclaimed Land, no topsoil) is composed of various small delineations of previously reclaimed areas. For various reasons, these areas are not presently topsoiled and therefore have no soil available for salvage. Although no topsoil is presently available for salvage, the current 6 inch surface layer may be suitable for salvage and use as a topsoil substitute material if these areas are projected to be redisturbed. Map Unit RLT (Reclaimed Land, topsoiled) is composed of various delineations of previously reclaimed areas that were topsoiled during reclamation activities. One large area of Map Unit RLT exists on the west side of Coal Resource Area N10. This reapplied topsoil was not sampled for laboratory analysis, but it is assumed that 6 inches of suitable topsoil can be salvaged from these areas if they are projected to be redisturbed. Map Unit TS (Topsoil Stockpile) is composed of some areas where stockpiled topsoil is located. This material will be used during overall reclamation activities, but it was not studied as part of the current soil survey. Map Unit RD (Reconstructed Drainage) is composed of a few areas where drainage channels have been reconstructed across reclaimed areas, most notably Coal Resource Area NIO. Soil material is not available for salvage from these areas if they are projected to be redisturbed. Map Unit RW (Riverwash) is composed of the very coarse-textured channel bed of various drainages in the study area. These channel beds will not be disturbed, and have no topsoil for salvage.

October 2003

4.0 REFERENCES ESCO Associates, Inc. 1998. Vegetation Monitoring Report - Black Mesa-Kayenta Mines. For Peabody Western Coal Company. Espey, Huston & Associates, Inc. 1980. Soils Baseline Studies of the Black Mesa and Kayenta Mines. Peabody Coal Company. Intermountain Soils, Inc. 1985. Soil Resources of the Black Mesa Lease Area. For Peabody Coal Company. December 1985. Natural Resources Conservation Service (NRCS). 1992. Four Corners Moisture and Temperature Meeting. Cortez, Colorado. October 5-9, 1992. Nyenhuis, J. 2000. Soil Survey Report - J9 Coal Resource Area, Black Mesa Mine. Kayenta, Arizona. Revised November 20,2000. Sasser, L. 2000. Soil Survey Project Leader, Natural Resources Conservation Service. Price, Utah. Personal communication with Jim Nyenhuis. October 3, 2000. Schoeneberger, P.J., et al. 2002. Field Book for Describing and Sampling Soils. Version 2.0. U.S.D.A.-Natural Resources Conservation Sewice-National Soil Survey Center. Lincoln, Nebraska. September 2002. Soil Survey Staff. 1993. Soil Survey Manual. Agricultural Handbook No. 18. U.S.D.A.Natural Resources Conservation Service. Soil Survey Staff. 1999. Soil Taxonomy. Second Edition. Agricultural Handbook No. 436. U.S.D.A.-Natural Resources Conservation Service. UDOGM. 2002. Guidelines for Management of Topoil and Overburden. R645-301-200 Soils. Table 4, Soil and Spoil SuitabilityAJnsuitability Evaluation. State of Utah, Department of Natural Resources, Division of Oil, Gas, and Mining. Salt Lake City, Utah. January 2002.

October 2003

TABLE 1 2003 Soil Survey Map Unit Legend
Dulce very channery fine sandy loam, 1 to 8 percent slopes Dulce very channery fine sandy loam, 8 to 30 percent slopes Bond very fine sandy loam, 1 to 8 percent slopes Zyme Duke complex, 1 to 8 percent slopes Zyme Dulce complex, 8 to 30 percent slopes 3DE 1 Zyme - Duke complex, 30 to 50 percent slopes 3F I Ustic Toniorthents Rock Outcrop complex, 50 to 80 percent slopes 4AB I Zyme very channery loam, 1to 8 percent slopes 4CD I Zyme very channery loam, 8 to 30 percent slopes 5 I Pulpit very fine sandy loam, ustic-aridic, 2 to 8 percent slopes 6AB I Sharps very fine sandy loam, ustic-aridic, 1 to 8 percent slopes ( Sharps very fine sandy loam, ustic-aridic, 8 to 15 percent slopes 6C 7B I Travessilla Zyme Dulce complex, 2 to 6 percent slopes 7CD Zyme-Travessilla-RockOutcrop complex, 6 to 30 percent slopes Zyme-Travessilla-RockOutcrop complex, 30 to 50 percent slopes 7E IOAB Blanding very fine sandy loam, bedrock substratum, 1to 8 percent slopes Blanding very fine sandy loam, bedrock substratum, 8 to 15 percent slopes 10C X I IAB Blanding - Blanding, bedrock substratum, very fine sandy loams 1 to 8 percent slopes X I 1C Blanding - Blanding, bedrock substratum, very fine sandy loams, 8 to 15 percent slopes 1IAB Blanding very fine sandy loam, 1 to 8 percent slopes Blanding very fine sandy loam, 8 to 15 percent slopes 11C G I I I Blanding very fine sandy loam, gravelly substratum, 2 to 8 percent slopes B 12AB I Begay loam, 1 to 8 percent slopes 12C 1 Begay loam, 8 to 15 percent slopes 13A I San Mateo loam, 0 to 3 percent slopes to 14AB (Oelopvery fine sandy loam, I 8 percent slopes 15A I Las Lucas sandy clay loam, 2 to 6 percent slopes Soil A - Soil B, extremely channery very fine sandy loams, 4 to 15 percent slopes 16C 16CE Soil A - Soil B, extremely channery very fine sandy loams, 15 to 50 percent slopes 16F Soil A - Soil B, extremely channery very fine sandy loams, 50 to 70 percent slopes DL Disturbed Land I P 1 Pond RL Reclaimed Land, no topsoil RLT Reclaimed Land, topsoiled Topsoil Stockpile TS Reconstructed Drainage RD RW Rivetwash
I

IAB 1CD 2B 3AB 3CD

-

I

-

I

I

I

I

I

-

-

I

-

15

October 2003

TABLE 2 Current Correlation of Soil Series on the Black Mesa Lease Area

Espey Huston & Assocrates lgBo Fruitland Not mapped Clovis Not mapped Moenkopi lves Not Mapped Not Mapped Youngston Not mapped Moenkopi Not mamed Not mapped Begay Not mapped Cahona Not mapped Dulce Mikim Not mapped Pulpit San Mateo Sharps Not mapped Not mamed Not mapped

I

Intermountain So~ls Igg5 Begay Bond Cahona Chilton Duke Las Lucas Oelop Pulpit San Mateo Sharps Travessilla Zyme Soil A Soil B

I

2000 & 2003
Nyenhuis Begay Bond Blandina Not mapped Dub Las Lucas Oelop Pulpit, ustic-aridic San Mateo Sharps, ustic-aridic Travessilla Soil A Soil B

1

I

I

I

October 2003

TABLE 3 Taxonomic Classification of Soil Series of the Black Mesa Lease Area

II-p 1 1

Series
Begay Blanding Bond
-

r
-

Family

Coarse-loamy, mixed, superactive, mesic Ustic Haplocambid Fine-silty, mixed, superactive, mesic Ustic Haplargid

Chilton Duke

I Loamy, rnked, superadie, rnesic Liihic Ustic Haplargid I Loamy-skeletal, rnked, calcareous, rnesic Ustic Toniorthent
Loamy, mixed, superactive, calcareous, rnesic, shallow Ustic Toniorthent Fine-silty, mixed, active, mesic Ustic Haplocambid Fine-loamy, mixed, superactive, mesic Ustic Haplargid Fine-silty, mixed, superactive, mesic Aridic Haplustalf

Las Lucas Oelop Pulpit, ustioandic

1 I
1

San Mateo Sharps, ustioaridic Travessilla Zyme Soil A Soil B

I Fine-loamy, mixed, superactive, calcareous, mesic Ustic Toniflwent
Fine-silty, mixed, superactive, mesic Aridic Haplustalf Loamy, mixed, superactive, calcareous, mesic Lithic Ustic Toniorthent

I Clayey, smetiiic, calcareous, mesic, shallow Ustic Toniorthent

I Loamy-skeletalover fragmental, mixed, calcareous, mesic Ustic Toniorthent
Loamy-skeletal overTragmental, mixed, mesic Ustic Haplocalcid

October 2003

TABLE 4 2003 Life of Mine Coal Resource Areas Soil Survey Recommended Soil Salvage Depths

2B 3AB 3CD 3DE 3F 4AB 4CD

1

5

1OAB 1O C

I

8 to 30 percent slopes Bond very fine sandy loam, 1 to 8 percent slopes Zyme Dulce complex, 1 to 8 ~ercent sloms Zyme Dulce complex, 8 to 30 percent slopes Zyme - Dulce complex, 30 to 50 percent slopes Ustic Torriorthents - Rock Outcrop complex, 50 to 80 percent slopes Zyme very channery loam, 1to 8 wrcent slo~es Zyme very channery loam, 8 to 30 percent slopes Pulpit, ustic-aridic, very fine sandy loam, 2 to 8 percent slopes Sharps, ustioaridic, very fine sandy loam. 1to 8 mrcent slo~es Sharps, usti~aridic, very fine sandy loam. 8 to 15 wrcent s l o r ~ s Travessilla - Zyme - Dulce complex, 2 to 6 percent slopes Zyme-Travessilla-Rock Outcrop complex, 6 to 30 percent slopes Zyme-Travessilla-Rock Outcrop complex, 30 to 50 percent slopes Blanding very fine sandy loam, bedrock substratum. 1 to 8 mrcent slo~es Blanding very fine sandy loam, bedrock

1.O 0.5
I

1.OlO.O

-

0.510.0 0.510.0 0.510.0

0.5
0.5~

0.0 0.5

0.510.0

I

0.5

I

0.510.0

2.5

1.011.5

0.5 0.5 0.0 5.0

0.510.0 0.510.0 1.014.0

(

5.0

I

1.014.0

October 2003

TABLE 5
N9 COAL RESOURCE AREA, 2345 Acres

33
34

Soil A-B gravelly loam Blanding loam Pulpit fine sandy loam Dulce channery loam Pulpit very fine sandy loam

16CE X il C
5

3CD

X llC (inclusion)

SH 8" to fract. SS Sideslope of scoria hill 4 2 to weath. Major rooting depth 1 7 , photo SH 30"to weath. Profile description, photo soft SS 12" to weath. sandy SH 24" to scoria SH

I

20

October 2003

TABLE 5
N9 COAL RESOURCE AREA, 2345 Acres

( Hole# (
38
39

Soil Name surface texture Duke fine sandy loam

-

I

Map Unit ( Depth to rock

Comments Iprofile description

I

40 I41 42 43
44

I

Pulpit very fine sandy loam

1 Puloit sandv loam/loam 1 O e l o ~ fine sandv loam very
Duke channery loam Pulpit very fine sandy loam Sharps very fine sandy loam

1 5 I5 (inclusion) 3CD 5

I

5 (inclusion) 5

17" to hard, shaly SS 27" to weath. I hard SH 1 30" to fract. SS 1 7.7'+ Profile description

45 46 47 48 49 I 50 51 52 53 54

IOelop very fine sandy loam IOelop very fine sandy loam
Oelop very fine sandy loam Duke channery loam Dulce channery loam I Duke channery loam Duke channery loam Blandina sandv loamlloam IOelop very fine sandy loam IPulpit fine sandy loam

-

I

55 56 57 58 59 60 61

I IDuke channery loam
I

Blanding fine sandy loam Oelop very fine sandy loam Oeloo verv fine sandv loam 1 Duke channery loam 1 Duke channery loam Duke channery loam

162 63 64 65 66 67 68 69 70 171

1 Duke channerv loam

I

Blanding fine sandy loam

1 Dulce channerv loam
Blanding fine sandy loam Dulce channery loam

I 1 Dulce channerv loam IBond fine sandy loam 1 Blanding very fine sandy loam 1 Pulpit very fine sandy loam

Bond fine sandy loam

4" to fract. SS 38" to weath. Contains old buried 7.5YR Bt SS 28" to weath. Profile description 5 (inclusion) fract SS 1 14AB I 6'+ 1 14AB 6'+ 14AB 6'+ 5" to fract. SS 3CD 3CD 5" to fract. I I scoria 5" to scoria SS 3CD 5 to scoria SS 3CD X I IAB 6.8'+ Major rooting depth 18" 1 14AB I 6'+ 128 1 39" to SS Profile description, photos 1 (inclusion) 1 1~ A B 1 6" to fract. Photos I I Siltstone 7'+ Profile descripton 11AB lo'+ Drainage cut 14AB 14AB lo'+ Drainage cut 1 IAB 1 5" to scoria SS 1~ A B I 6" to weath. Major rooting depth goes to 14" in . scoria SH w i t h . SH, photos 1AB 6" to weath. Major rooting depth goes to 14" in SH weath. SH, photos 1 IAB I 14" to weath. SH 4.5'+ 5 Major rooting depth 16" I(inclusion) I 13CD 1 8" to fract. Siltstone 7'+ Maior rootina d e ~ t h 26" 11AB 18" to weath. 2B SH (inclusion) 14" to fract. 2B 1 Hard SS 1 IAB 1 6"to fract. SS (28 1 9" to hard SS 1x1IC I 40'+ 15 1 35" to weath. Photos

fl

I

I

October 2003

TABLE 5
N9 COAL RESOURCE AREA, 2345 Acres

I Hole# I Soil Name - surface texture 72 IDuke channery loam 73 1 Blanding very fine sandy loam
74 75 76 77
78

I

Soil A-B very channeryloam Begay sandy loam Duke channery loam Duke channerv loam Pulpit very fine sandy loam Pulpit very fine sandy loam Bond very fine sandy loam San Mateo loam San Mateo loam

Map Unit 13CD 15 (inclusion) 16CE
12AB 1AB 3CD 2B (inclusion) 2B (inclusion) 2B 13A
13A

I Depth to rock I 1 6" to fract. SS I

Comments Iprofile description

I

I

53" to weath. 1 SH 16" to weath. Weath. scoria SS & SH from 16 to 40" scoria Drainage cut 6'+ 6" to fract. SS 10" to weath. Photos sandy SH 28" to hard SS Photos

79

29" to hard SS
18" to fract. SS Photos 8'+ 8+ '

80 81 82

October 2003

TABLE 5 NIO COAL RESOURCE AREA, 1794 Acres
Hole# Soil Name surface texture Map Unit 1 3CD Dulce channery sandy loam 2 Travessilla very channery sandy loam 3CD (inclusion) 3 3CD Duke channery sandy loam 4 3CD Zyme clay loam 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 Blanding fine sandy loam Zyme clay loam Zyme clay loam Duke channery loam Sharps very fine sandy loam Las Lucas sandy clay loam Las Lucas sandy clay loam Las Lucas sandy clay loam Las Lucas sandy clay loam Las Lucas sandy clay loam Duke channery loam Dulce channery loam Zyme clay loam Duke channery loam Blanding fine sandy loam Begay sandy loam Blanding fine sandy loam Duke channerv loam Pulpit very fine sandy loam Blanding fine sandy loam Blanding fine sandy loam Bond very fine sandy loam Blanding very fine sandy loam Duke channery loam Bond very fine sandy loam Bond very fine sandy loam Bond very fine sandy loam Bond very fine sandy loam Blanding very fine sandy loam Pulpit very fine sandy loam Duke channery loam Blanding fine sandy loam Duke channery loam 1OAB 3CD 3CD 1AB 5 (inclusion) 15A 15A 15A 15A 15A 3CD 3CD 3CD 3AB 1OAB 12AB 1OC 3CD 5 1O C 1O C 2B 1OAB 28 (inclusion) 28 2B 2B 2B 3DE (inclusion) 3DE (inclusion) 3DE 5 (inclusion)

-

Depth t o rock 5" to fract. SS 4" to hard SS 7" to fract. SS 6" to weath. SH 55" to SS 4" to weath. SH 6" to weath. SH 6" to fract. SS 30" to SS 15'+ 15'+ 15'+ 15'+ 15'+ 4" to fract. SS 6" to fract. SS 3" to weath. SH 3 to fract. SS 6'+ 7'+ 6.7'+ 9" to weath. SH 30" to hard SS 57" to SS 44" to SS 13" to weath.

Comments / profile description

Drainage cut Drainage cut Drainage cut Drainage cut Drainage cut

Profile description Profile description Profile description

1 9" to fract. SS

7'+

Thin, weak scoria on soil surface

10" to fract. SS 9" to fract. SS 9" to fract. SS 16" to sandy SH 5' to SS Major rooting depth 30" 22" to sandy SH 12" to fract. SS 53" to SS

5
(inclusion)

16" to fract. SS

October 2003

TABLE 5 NIO COAL RESOURCE AREA, 1794 Acres
Hole# Soil Name surface texture 38 Duke channey loam
141 42 43 44 45 146 147 48 49

-

1 Duke channery loam
'~
I

I Pulpit very fine sandy loam

I Pulait verv fine sandv loam
u ~ b i t fine sand; loam ve& Duke channery loam

Map Unit 1CD 1CD 1CD 1CD 5 5

5
5 (inclusion) 15A I 5A 5 5 (inclusion) 3DE 3DE 2B 2B 28 (inclusion) 2B

Depth to rock Comments / profile description 20" to SS Scoria colluvium 9" to SS Scoria colluvium 16" to SS Scoria colluvium 10" to fract. SS 28" to SS 24" to soft SS 1 23" to soft SS I 1 16" to soft SH I

I Las Lucas sandv clav loam
Pulpit vety fine sandy loam Blanding fine sandy loam Zyme very channery loam Zyme very channety loam

I
1
1

1 Las Lucas sandy clay loam

15' 15' 26" to SS 7' to SS
4" to weath.

IDrainaae cut -

Drainage cut

I

Pulpit very fine sandy loam
55
56 57 58 59 60
61 I62

I
1

SH 3" to weath. SH 13" to fract. SS 12" to fract. SS 22" to fract. SS
9" to fract. SS

Duke channery loam

I
J

( Bond very fine sandy loam

I Bond verv fine sandv loam

i Bond ve& fine sand;
I

loam Bond very fine sandy loam Pulpit very fine sandy loam

2B 2B 2B

(inclusion)
3F

I Sandstone Rock Outcrop

I Sandstone Rock O u t c r o ~

1

12" to fract. SS 12" to fract. SS 24" to fract. SS 0"

1

I

October 2003

TABLE 5 N12lN99S COAL RESOURCE AREA, 2773 Acres
Hole# II Soil Name surface texture 1 I Blandinn fine sandy loam 2 Blanding fine sandy loam 3 Dulce channery loam

-

76" to weath.

Map Unit

Depth to rock

Comments I profile description Buried Btk at 6 to 7.5'

1

4 5 6 7

( Blanding fine sandy loam
)BI:lndina fine sandv loam Duke channery loam

I Oelop very fine sandy loam
16CE inclusion)
16CE (inclusion) 16CE

1

1 5" to fract. SS

8 9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Duke channery sandy loam Duke channery sandy loam Soil A-B very channery loam

I

5" to fract. SS 16" to fract. SS
4" to fract. scoria

1

1 Blanding very fine sandy loam

I

I Oelop very fine sandy loam
1 Duke channerv loam

I Duke channery loam
Duke channery sandy loam Handing very fine sandy loam Oelop very fine sandy loam
1AB 14AB inclusion)

Gravelly lense at 8 to 9' Drainage cut 5" to fract. SS Sliaht scoria influence 5" to fract. SS 6" to fract. SS Photos 63"+ to SS Profile description, photos
8.3'+

-

I

I Oelop very fine sandy loam

I Oelop very fine sandy loam

1Oelo~ channerv sandv loam

1 Blanding very fine sandy loam
1 Blandina verv fine sandv loam

I Oelop channery sandy loam

. .. .-

Lower fan-valley sideslope, very channerv loam lense at 4 to 5' Drainage cut Local alluvium from trib. drainage Drainaae cut Drainage cut

I
I
1

I Blanding very fine sandy loam

25 26 27

1I
I

Blanding channery sandy loam

XI IAB XI I AB XIIAB XIIAB

4'+ 5'+

Blanding fine sandy loam I Duke channerv loam Dulce channery loam Pulpit very fine sandy loam

XIIAB 1AB 14AB 1AB 5
5

31 32 33 34 35 36 37

(Pulpit very fine sandy loam

Drainage cut 54 '. 54" to whitish gray SH 9'+ 12" to fract. SS 4'+ Drainage cut 12" to fract. SS 3 2 to hard, fract. SS I 30" to hard, Photos

I

I

I Duke very cobbly loam
I

Duke loam Duke loam

GllB

SS 6") 12" to fract. SS 9" to fract. SS

===I P
D
October 2003

1 Soil A-B verv channerv loam
'Soil A-B v e 6 channe6 loam Soil A-B very channery loam

Scoria hilltor, Scoria hilltop Scoria sideslope, rods in upper part of scoria, photos

TABLE 5 N12lN99S COAL RESOURCE AREA, 2773 Acres
Soil Name surface texture Blanding very fine sandy loam Blanding fine sandy loam Bond channerv loam Bond loam Bond loam Bond loam Dulce channery loam Zyme channery silty clay loam Soil A-B flaggy sandy loam Soil A-B cobbly sandy loam Soil A-B cobbly loam Begay fine sandy loam Dulce fine sandy loam Blandina fine sandv loam Begay fine sandy loam Zyme clay loam Dulce channery loam Duke fine sandy loam Duke fine sandy loam Zyme clay loam Zyme clay loam Zyme channery clay loam Bond fine sandy loam Duke gravelly fine sandy loam Bond fine sandy loam Dulce fine sandy loam Duke fine sandy loam Bond fine sandy loam Zyme clay loam Reclaimed Land fract. SS 9" to weath. SH over SS Old sed, pond basin reclaimed
16C

-

Map Unit

I Depth t o rock
4' to SS 8" to SS 16" to weath. SS&SH 15" to weath.

Comments 1 profile description Small saddle between 2 knob ridges, photos Photos Weath. bedrock with roots from 16 to 25", photos Weath. bedrock with roots, photos
J

28

I

1

Photos

I
1
GIIB GllB (inclusion) 3DE

1 4" to scoria
5" to fract., hard SS 54"+ 8'+

hard scoria

I

______i
Slopewash alluvium, photo Profile description, photo Drainage cut

12" to weath. SH 16CE I 8" to weath. inclusion) scoria 5" to fract., hard SS 3AB 1 5" to fract., hard SS 3AB 5" to weath. SH 3CD 17" to weath. 3cD platy SH 5" to weath., Roots go into SH to 12" I platy SH 2B 1 17" to weath. sandy SH 2B 1 14" to weath. Weath. SH with roots 14 to 24" SH (inclusion) 2B 1 12" to fract. S2 1 7" to hard, fract. SS (inclusion) 2B 1 6" to hard.

I
1

1
1

I

I

Photos

- taken out,

October 2003

TABLE 5

N12lN99S COAL RESOURCE AREA, 2773 Acres
Hole#
68 69 70

Soil Name surface texture Las Lucas sandy clay loam Soil A-B very channery loam Dulce channery loam

-

Map Unit 15A 16CE 1AB

Depth to rock Comments 1 profile description 4'+ 3" to scoria 12" to fract. SS Photos

October 2003

N99N COAL RESOURCE AREA, 1645 Acres
Hole# I Soil Name surface texture 1 Pulpit fine sandy loam 2 Duke channery loam 3 Duke channery loam
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Duke channery loam Pulpit very fine sandy loam Pulpit venr fine sandv loam Blanding fine sandy loam Zyme clay loam Zyme clay loam Las Lucas sandy clay loam Sharps very fine sandy loam Sharps very fine sandy loam Zyme clay loam Sharps channery sandy loam Scoria Rock Outcrop Duke channery fine sandy loam Zyme clay loam Pulpit very fine sandy loam Duke channery loam Soil A-B very channery sandy loam Duke channery sandy loam Sharps very fine sandy loam Duke channery loam Las Lucas sandy clay loam Sharps very fine sandy loam Las Lucas sandy clay loam Las Lucas sandy clay loam Zyme clay loam Soil A-B extremely channery sandy loam Sharps very fine sandy loam Blanding very fine sandy loam Bond channery fine sandy loam

-

I

Map Unit I Depth to rock I Comments /profile description Profile description 39" 5 9" to fract. SS 1AB 17" to fract. SS 5 (inclusion) 14" to fract. IAB shaly SS 29" to hard, 5 fract. SS 23" to hard. 5 fract. SS 7' to hard, 5 fract. SS (inclusion) 3CD 4" to sandy SH 3CD 3" to sandy SH 6.3' Drainage cut 15A 6AB 23" to SH & soft SS 6AB 24" to soft SH 3CD 13" to soft, sandy SH 23" 6AB Residual material from scoria 16CE 2" to baked SS 16CE 6" to baked SS (inclusion) 3CD 3" to SH 1AB 27" to hard SS (inclusion) 3CD 14" to SS 16CE 27" to weath. baked bedrx 14" to weath. 14 to 4 0 very weath. SH with routs 6AB SH (inclusion) 32" to weath. 6AB SH 3CD 11" to fract. SS 7'+ 15A Drainage cut 23" to weath. 6AB
-- -

15A 1 5A 3CD 16CE 3CD (inclusion) 2B (inclusion) 2B

15' Drainage cut 20' Drainage cut 7" to weath. Roots in SH to 24" SH 11" to baked SH 11 to 24" very weath. SH, photos 24" 6' to weath. Major rooting depth to 38", photo carb.SH 19" to weath. Weath. SH 19 to 50", photo SH

October 2003

TABLE 5
N99N COAL RESOURCE AREA, I645 Acres
Hole# 33 34 35 36 37 Soil Name surface texture Bond channery fine sandy loam Bond channery fine sandy loam Soil A-B channery sandy loam Duke channery loam Zyme clay loam to clay Sharps loam Zyme clay loam Dulce channery loam Zyme clay loam Zyme clay loam Zyme clay loam Duke channery loam Duke channery sandy loam Sandstone Rock Outcrop Travessilla channery sandy loam Duke channery sandy loam Duke channery loam Duke channery loam Duke channery loam Pulpit very fine sandy loam

-

Map Unit 28 28 16CE 3DE 3DE 3CD (inclusion) 3CD 3CD 3CD 3CD 3CD 1AB
1 AB

38
39 40
41

42 43 44 45 46 47 48 49 50 51 52

7E 7E 3CD 3AB 3AB I AB 1AB (inclusion)

Depth to rock Comments /profile description 19" to weath. SH 1 4 to fract. scoria SS 12" to mixed scoria 6" to fract. SS 12" to weath. SH 24" to weath. Major rooting depth 12" SH 6 to weath. SH 11" to weath. SS 9" to weath. SH 6" to weath. SH 5" to weath. SH 10" to weath. SH 8" to weath. SS 0" 9" to SS 4" to fract. SS 10" to fract. SS 12" to fract. SS 12" to weath. SH 24" to fract. SS

October 2003

TABLE 5 52/515 COAL RESOURCE AREA, 1664 Acres
Hole#

I

Soil Name surface texture Sharps channery very fine sandy 1 loam I Zyme channery silty clay loam Duke very channery loam Duke taxajunct very gravelly loam
Duke taxajunct channery loam

-

I

Map Unit IAB (inclusion) IAB 1AB IAB

I Depth to rock I
30"

Comments /profile description Profile description, platy SH Cr 30 to
60"

-

(inclusion) Bond taxajunct loam
52-7
I

2B

7" to platy SH Profile description 9" to fract. SS Profile description 1 0 to variable Profile description, variable scoria lo"+ with SS., SH. clinker (red with scoria white ashy material) 10" to scoria Profile description, scoria substratum, with duric & open swale petrocalcic features 18" to fract. Profile description, scoria substratum SS, hard SS
,

Bond very fine sandy loam Bond flaggy very fine sandy loam Soil A Blanding channery loam Duke channery fine sandy loam Bond very fine sandy loam Duke very channery loam (inclusion) 28
IAB (inclusion) 16" to fract. rock 10"

Profile description Profile description

J2-8 52-9 52-10 52-11 J2-12 52-13

Profile description, valley swale Rock outcrop present, slopes go to 45% Profile description, Crk 9 to 2In, hard SS @ 21",backslope Profile description, Crk 12 to 29", ha^, scoria @ 29"; backslope Profile description, scoria @ 55" Profile description; open valley sideslope; ext. gravelly fine sandy loam 53 to 90" Profile description; ext. gravelly discontinous strata 45 to 70", valley lower sideslope Scoria R @ 8.3' 6.8' to gravel Profile description; gravel 6.8 to 8.6', then hard scoria, lower valley Profile description; gravelly lense @ 3 to 5', valley sideslope Profile description, terrace, common salt filaments & seams 85 to 96" (7 to
1AB (inclusion) IAB

-

Oelop fine sandy loam
J2-17 52-18 J2-19

Oelop very fine sandy loam Oelop very gravelly-channery very fine sandy loam Oelop very fine sandy loam San Mateo very fine sandy loam

J2-21 J2-22

Travessilla very channery loam Travessilla very cobbly fine sandy

7" to SS
6

-

-

J2-25 J2-26

1Zyme clay loam 1 Duke loam

3CD 1 AB

6 12"

Depth ranges from 6 to 30", gullied

I

30

October 2003

TABLE 5
J2lJ15 COAL RESOURCE AREA, I664 Acres
Soil Name surface texture Dulce very channery loam
Sharps very fine sandy loam Dulce like loam Blanding loam Begay very fine sandy loam Pulpit very fine sandy loam Soil A very channery loam

-

Map Unit

~

comments /profile description 9" to white SS Profile description, shoulder, drainage exceeds 8% to the south

x to h rock

9"
50"

IWhite SS @ 9" ICr 50 to 74", then hard rock

Soil A very channery loam

Oelop very fine sandy loam Dulce loam Bond like very fine sandy loam Travessilla fine sandy loam Sharps like very fine sandy loam Sharps like very fine sandy loam Sharps very fine sandy loam Soil A very cobbly loam 515-11 Soil A very cobbly loam 515-12 Soil B extremely channery loam

profile description, backslope-nose, very to ext gravelly loam to sandy loam @ 4 to 30", scoria @ 30", PJ vegt. 5" to Profile description, convex summit, carbonates very channery loam to sandy loam 5 to 28", ext channery loamy sand 28 to 164,then hard scoria 62" 1 Profile description, valley sideslope, olive SH 62 to 88", then ss 8" I Cr SHIcoal 21" I Profile description, open summit, sandy clay loam ~ r k - 2to 32", then 1 hard SS 4" to buff SS Profile description, convex summit 25" Profile descri~tion. summit. Crk 25 to 145", then buff SS 18" to soft SH I -. 28" to gray SH Profile description, open swale 7" to fract. Profile description, backslope, sage

4 to carbonates

I

'

-

--

-

-

-

~

FEE-

Soil A very channery loam Blandina loam Travessilla very fine sandy loam Sharps very fine.sandy loam Soil A extremely cobbly loam Blanding loam Travessilla very fine sandy loam OelopIBlanding very fine sandy loam Blanding very fine sandy loam Pulpit very fine sandy loam Pulpit very fine sandy loam
5 1AB (inclusion)

8" to fract. ( profile description, backslope, PJ & Scoria sage 7.8' to soft SH Profile description, sage 36" to soft SS I & SH 1 8 to scoria 4 5 to Cr SS & SH 8" to white SS I 60" to gray Profile description platy SH 8'+ Profile description, valley sideslope, sage, hard ss at 8.3' 34" to hard SS Profile description, open swale, sage Profile description, ridge, PJ, Crk 21 21" 1to 39, then hard SS 9" I

1CD I OAB

October 2003

TABLE 5 J21J15 COAL RESOURCE AREA, 1664 Acres
Soil Name surface texture

-

Map Unit

Depth to rock

Comments /profile description

Pulpit like very fine sandy loam Travessilla very channery fine sandy loam Blanding very fine sandy loam

IAB (inclusion)

Profile description, upland, PJ, Crk very fine sandy loam 39 to 50". then ha& SS Patches of scoria & Duke Profile description, valley dissected & gullied, loam & very fine sandy loam textures, slightly coarser sands with depth Alluvial fan, stratified very fine sandy loam, fine sandy loam, and loam Gullied

Begay gravelly very fine sandy loam Sharps very channery fine sandy loam Soil A

October 2003

TABLE 5 54 COAL RESOURCE AREA, 524 Acres
Hole# I Soil Name surface texture 1 Blanding very fine sandy loam
I

-

I

Map Unit

I Depth to rock I
51"
7"

Comments Iprofile description

2

Soil B very channery loam Sharps very fine sandy loam Sharps very fine sandy loam Blanding loam, very fine sandy clay loam Bond very fine sandy loam Begay fine sandy loam Sharps very fine sandy loam Blanding very fine sandy loam -

3 4 5

6
7 8 9 10
I I 12 13 14 15 16 17

I I Blanding very fine sandy loam

5 (inclusion) 1AB (inclusion) 6AB 6AB 6AB (inclusion) 2B 12C 6AB X I IAB 11AB 6AB 5 5 1AB 3DE 3CD 1AB

Profile description; Crk 51 to 70", then white SS @ 70" Profile description

25 to 36" (30") 35 to 45" weath. SH 35" Buried argillic; white SS @ 58" 58" 17" 8'+ 39" 8.1' 11' 38" 20" 18" 8" SH and SS Cr in same pit Dissected Gray SH Cr 39 to 45", then hard SS Profile description, 97 to 120" soft SS, then hard, white SS 0 to 7' very fine sandy loam & sandy clay loam; 7 to 11' loamy fine sand SH Cr 38 to 66", then hard scoria 20 to 2 8 Cr, then hard, white SS Surface disturbed Profile description Gray, calcareous SH Cr Gray SH Cr; also inclusion of Sharps Buff SS & olive gray SH Cr

Sharps very fine sandy loam Pulpit very fine sandy loam Pulpit very fine sandy loam Duke like very channery loam Zyme channery clay loam Duke channery very fine sandy loam Duke very channery loam

6"
8" 8"

October 2003

TABLE 5
J6lJ14 COAL RESOURCE AREA, 2343 Acres
Soil Name surface texture Hole# Begay loamy fine sand J6-1
56-2 56-3 56-4 56-5 J6-6 J6-7 J6-8 J6-9 J6-10 J6-11 J6-12 J6-13 J6-14 J6-15 J6-16 56-17 J6-18 J6-19 J6-20 J6-21 56-22 J6-23 56-24 J6-25 J6-26 J6-27 J6-28 J6-29 Unnamed inclusion Sharps very fine sandy loam Travessilla very fine sandy loam Pulpit very fine sandy loam Blanding very fine sandy loam Begay very fine sandy loam Blanding very fine sandy loam Sharps very fine sandy loam Soil A Blanding very fine sandy loam Pulpit very fine sandy loam Sharps like very fine sandy loam Blanding very fine sandy loam Blanding very fine sandy loam Sharps loamy very fine sand Blanding very fine sandy loam Blanding very fine sandy loam Blanding very fine sandy loam Blanding very fine sandy loam Travessilla fine sandy loam Duke channery loam Pulpit very fine sandy loam

-

Map Unit X I IAB (inclusion) X I IAB (inclusion) 6AB
7B 5 1OAB XllC (inclusion) AB X II 6AB 16CE 1OAB 6AB (inclusion) 6AB XllC XIl C 6AB 1OAB 1OAB XllC X I IAB

78 1AB 6AB (inclusion) 3AB Zyme channery clay loam C 1O Blanding very fine sandy loam Duke very channery fine sandy loam 3DE San Mateo loam Zyme Sharps very fine sandy loam

Comments I profile description Depth to rock 10.5' to SS Profile description, backslope, wind reworked Profile description, slickspot - barren, 7.8' blowout surface 32" to gray SH Profile description, convex ridge, depth to SH varies in pit from 32 to 42" 5 to hard SS Upland dissection up to 15% slopes Profile description, bench, shadscale 26" to SS vegetation 6.3' to gray Profile description, bench, shadscale vegetation shale Profile description, bench, 6% slope 10.5'+ but sides range up to 12%, annual vegetation 49" to Cr SH 8" to strong carbonates 24" to Cr mudstone Profile description, backslope 14" 60" (5') to Cr Profile description, bench, shadscale SH, rock @ vegetation 66" 27, to Cr, rock Profile description, bench, shadscale vegetation, >18% clay Bt @ 36" Profile description, bench, shadscale 26" vegetation, platy SH & SS digs easy to 60" 9.5'+ 0 to 50" very fine sandy loam, 50 to 1O'+ 125" loamy fine sand (lee side of hilltops) 28" to Cr SH 60". variable 60" to gravelly sandy loarn/loamy sand, 86" to Cr SH, 3% slope depth Weath. scoria 70" 72-140" loamy very fine sand, loamy 12'+ fine sand, 8% slope 0 to 5 very fine sandy loam, 5 to 9' ' 9' to SS gravelly very fine sandy loam 10" Sharps inclusions on bench 14" Inclusions of Rock Outcrop and Duke 38"
6" 52" 6" 12'+ Slopes range to 15% 8% slope, eroded Inclusions of Sharps, Pulpit, and Zyme Greasewood vegetation 15-20% RO, Eroded, patches of Zyme & BlandinL

I 3A 3DE 6AB

4 "
30"

October 2003

TABLE 5 J6lJl4 COAL RESOURCE AREA, 2343 Acres Soil Name - surface texture Sharps very fine sandy loam
Blanding very fine sandy loam

I

Map Unit

Depth to rock

I6C I 6AB (inclusion)

Comments Iprofile description Inclusions of Blanding eroded

44" to gray SH Profile description, Cr SH 44 to 60" with scoria fragments 37" to Cr SH Profile description, upland 36" to white 5% slope

ss

Blanding very fine sandy loam Bond very fine sandy loam Blanding very fine sandy loam Blanding very fine sandy loam Pulpit very fine sandy loam Blanding very fine sandy loam Soil A very channery loam Duke loam Blanding very fine sandy loam Duke very fine sandy loam Sharps very fine sandy loam Duke channery loam Pulpit very fine sandy loam Soil A Scoria-SS

6AB (inclusion) 2B lllAB 1x1IAB I6~ (inclusion) 5 I(inclusion) 116~ IAB I OAB IAB 6C 3AB 5 16C 16C

45" to hard, 2% slope white SS 55" to olive. ca Profile description, 4% slope SH 13" to hard 3% slope 4% slope 6% slope, loamy fine sand 64 to 88" SS & SH observed in gully, - moderately deep 6% slope

6 6 to white SS 6" to white SS Profile description, shoulder, 4% slope 20" Sharps inclusions 60" to interbedded SS & SH 12" lnclusions of Zyme and Sharps 30+ Incised Sharps and Blanding 8" to SS Sharps inclusions 24" to hard SS 4" to hard SS Both hard SS & scoria present On

October 2003

TABLE 5
58 COAL RESOURCE AREA, 717 Acres
Hole# 1 Soil Name surface texture 1 Begay fine sandy loam 2 Sharps taxajunct very channery fine sandy loam Sharps very fine sandy loam 3 4 Sharps very fine sandy loam 5 Duke very channery fine sandy loam

-

I

Map Unit 12AB 6AB

I Depth to rock 1
7.5'+ 36" to SH

Comments Iprofile description Valley fill 2BCk @ 13 to 36" clay

T

6AB 6AB 6AB

Eroded surface, Bk 8 to 26" 26" to SH 33" to soft SS Bk 18 to 33" 15" to SH SH is soft, gray & calcareous

eroded 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Blanding very fine sandy loam Sharps very fine sandv loam Blanding very fine sandy loam Blanding very fine sandy loam Sharps taxajunct very fine sandy loam Blanding very fine sandy loam Sharps very fine sandy loam Blanding very fine sandy loam XII AB 1OAB (inclusion) 1OAB 1OAB 6AB 1OAB 6AB 6AB / (inclusion) 16AB 6C XII AB X I IAB X1IAB 1O C (inclusion) 6AB 52" to SS 22" to SS & SH 51" to fract. white SS 40" 25" 72" to SH 33" to SH 58" to SS & SH 38"toSS& SH 36"
48" ,to SH 72"+ 74" to SH 72"+

CoalISH at 40 to 60" in gully Weak argillic, coal @ 25" Well developed argillic

ISharps very fine sandy loam
Sharps very fine sandy loam Blanding very fine sandy loam Blanding very fine sandy loam Blanding taxajunct fine sandy loam Unnamed loamy fine sand Sharps very channery fine sandy loam

I

1 I

I I
Dissected (gullied), inclusions of Blanding 2' of fine sandy loam eolian on top Psamment, old substratum, C03 2440" weakly cemented Eroded, Zyme in gullies

1

36"

October 2003

TABLE 5
J9 COAL RESOURCE AREA, 550 Acres
Hole# Soil Name surface texture 1 Zyme sandy clay loam

-

I

1

I

Map Unit 7CD

Depth to rock Comments / profile description 8" to Complete profile description I somewhat I I

-.

.

12 13 14 15 16 17

Bond fine sandy loam Blanding, bedrock substratum, fine sandy loam Blanding fine sandy loam Blanding fine sandy loam Blanding fine sandy loam Sharps, ustic-aridic, fine sandy loam

2B 11AB (inclusion)
I OAB (inclusion) 11AB 11AB 6AB

20" to hard SS Complete profile description 65" to Complete profile description somewhat soft SH 72" to hard SS Complete profile description 80"+ 96"+ 26" to weath. Complete profile description Complete profile description Complete profile description

26 27 28 29
30

Blanding fine sandy loam Travessilla gravelly sandy loam Bond fine sandy loam Zyme clay loam

(inclusion) 11AB 7CD 2B 7B
~IIAB

I Blanding fine sandy loam

Complete profile description 108"+ 6" to hard SS Complete profile description 16" to hard SS Complete profile description 4" to weath. Complete profile description SH 72" 1 Complete profile description

October 2003

TABLE 5
J10 COAL RESOURCE AREA, 592 Acres
Soil Name surface texture Begay very fine sandy loam Zyme channery silty clay loam Travessilla very channery loam

-

Map Unit 12AB 3AB 7CD

I Depth to rock I Comments I profile descriptio I 5'+ 1 Fan position, 4% slope, gravel @ 60" I 10" 6" I Rock Outcrop ledges approx. 25%,
8" 4.5'
4
IL
911

,,

Duke verv channerv loam Blanding very fine sandy loam Zyme clay loam Blanding very fine sandy loam Dulce channery fine sandy loam Dulce very channery loam Pulpit very fine sandy loam Pulpit very fine sandy loam Pulpit very fine sandy loam Zyme very channery clay loam Zyme very channery loam Travessilla very channery fine sandy loam Pulpit very fine sandy loam Duke very channery very fine sandy loam Dulce very channery loam Dulce verv channerv loam Dulce very channery loam Pulpit very fine sandy loam Oelop very fine sandy loam Sharps very fine sandy loam Blanding fine sandy loam Blanding very fine sandy loam Blanding very fine sandy loam Blanding very fine sandy loam Blanding very fine sandy loam Blanding fine sandy loam Blanding very fine sandy loam Pul~it Sharps very fine sandy loam Sharps very fine sandy loam Blanding very fine sandy loam Sharas venr fine sandv loam Dulce very channery fine sandy loam

1AB XI I A B
Q P ~

Zyme inclusions Scoria influence, 6% slope C03 at 14", fine sandy loam at 40"

X I 1AB 3CD 1AB I AB (inclusion) 1AB (inclusion) 5 78 3CD 7CD 5 3CD
I

6'+
12"
6" 22"

C03 at 12", loamy fine sand at 40" Duke-Zvme-Travessilla-Rock Outcrop present PJ vegetation

24"
30" 10" 16 15" 34" Calcic at 1 2 Shoulder position, 6% slope, SS ledges present Profile description, 8% slope, PJ vegetation, SS-SH & scoria influence Profile description Eroded Zyme-Duke-Travessilla present
I

8"

3AB

1 16" to fract. I

I

White & red

I
Bedrock is mix of SS, SH, and scoria PJ vegetation

14AB

I

6'+

I loam 36 to 72"

Valley fill, loam 0 to 36", fine sandy

1O C 1CD (inclusion) X I IAB 6AB 6AB

50" 54"

bottoms Summit noseslope Backslope, eroded Old eolian loamy fine sand 5 to 8'

I

XI IAB 6AB 1AB

1

1 I

30" to soft SH 0 to 18" very fine sandy loam, 18 to 130" clav . - ~, 5' to gray SH Profile description, summit, 3% slope 20" to Cr SH Siltv clav loam C horizon at 1 2 6" sciria. ss & SH bedrock with Shar l remnants
~

1

38

October 2003

TABLE 5
JIO COAL RESOURCE AREA, 592 Acres
Hole# Soil Name surface texture 37 Blanding very fine sandy loam 38 Blanding very fine sandy loam 39 40 41 I42
43 44

-

Map Unit

X I I AB X I 1AB
1OAB

Handing very fine sandy loam Pulpit very fine sandy loam Blanding very fine sandy loam 1 Blandinn very fine sandy loam Sharps very fine sandy loam Travessilla flaggy fine sandy loam

5
I OAB I5 (inclusion) 1AB (inclusion)

I

Depth to rock Comments 1 profile description 48" to scoria Profile description, convex summit 7' to SH Profile description, backslope, soft SH from 7 to 9' 53" to hard SS 6% slope 24" to hard SS 6% slope 48" to SH SS at 70" 43 1 I
-

16" 10"

Eroded, remnant inclusion in I A B Zyme very channery loam also
oresent

76

October 2003

TABLE 5 J28 COAL RESOURCE AREA, 1406 Acres
Hole# Soil Name surface texture 1 Blanding very fine sandy loam

-

Map Unit X11AB 13A X11C X I 1AB 13A X I 1C

2

San Mateo very fine sandy loam Blanding very fine sandy loam Blanding very fine sandy loam San Mateo very fine sandy loam Blanding channery very fine sandy
I

Depth t o rock Comments Iprofile description 7.5' to SH Mollic surface, loam & very fine sandy loam to SH, B k l @ 20" 18' Profile descri~tion. terrace. verv few profile, generally loam 76" to hard SS PJ vegetation, 8% slope Profile description, valleyside, 87" I borderline mollic 15' SS rises to 7' east of knoll 86" Profile descri~tion, knoll, verv aravellv fine sandy loam 75 to 86". p j * I vegetatioh, 6% slope, dissected IS+ 12 to 15' are very gravelly 211+ Loam Bt 17' 6 to 17' alternating loamy & gravelly

3 4

5 5
7 B 9
10 11

-

I San Mateo very fine sandy loam
1 O e l o ~ fine sandv loam verv

12 13 14 15
16

13A 14AB San ~ a t e channeiloam 6 1 1~ A B I 1 (inclusion) I Oelop channery very fine sandy loam I 14AB I Unnamed gravelly very fine sandy 1 X I 1C loam Oelop very channery very fine sandy 14AB loam Oelop channery very fine sandy loam 14AB

1

17 18

19 20 21 22
23

24 25

7 to 17' alternating gravelly & loamyp 50 to 72" gravelly very fine sandy loam 10.5' to SS & Eroded valley fill SH 6% slope, very fine sandy loam, loam, ( 12'+ and clay loam textures 12'+ I San Mateo loam 11 3 ~ 2% slope, loamy, greasewood 6' Profile description, mollic surface Blanding channery very fine sandy I X I 1AB loam layer I 6 to 12' gravelly mix with loams & 13A 18'+ San Mateo loam very fine sandy loam above & below, saline filaments visible at d e ~ t h Travessilla channery fine sandy loam 7B 20" to hard, Bench, 3% slope white SS 8.6'+ X11C Profile description, valley side, 9% Unnamed fine sandy loam slope, old alluvium with relic mottles SS 16" to 103" (8.67, flagstones at 8.6' 201+ San Mateo loam 13A Loam textures with scattered 3-5" aravellv strata Mollic upper 12", 4% slope 5' to SS Blanding very fine sandy loam 1OAB 10'to SS SS exposed at depth along 13A San Mateo loam drainageway 46" to rock Profile description, 0 to 26" old Unnamed channery loam 6AB (inclusion) channery alluvium, 26 to 46" shaly C horizon, mollic surface 0 to 8" I I I 0 to 16" A, Bt; 16 to 42" Bk, 42-57" 1O'+ Blanding very fine sandy loam 1~ A B (inclusion) loamy fine sand 12'+ 13A Profile description, terrace, 2% slope, San Mateo loam all horizons stratified, variable textures, irregular OM% 14AB 12'+ Profile description, valley side, 7% Oelop fine sandy loam slope

I

I

17'+ 6'

I

I

1

October 2003

TABLE 5
J28 COAL RESOURCE AREA, 1406 Acres
Soil Name -surface texture Oelop fine sandy loam Map Unit 14AB Depth t o rock Comments 1 profile description 1O'+ Fine sandy loamlsandy clay loam A,Bt; substratum to 10' sandy clay loam, very fine sandy loam, silty clay loam, and loam 19" to buff- Profile description, has an argillic, white SS loses argillic near Rock Outcrop's 10" to SS Channers easily crushable 6'+ 9.5'+ Profile description, 5% slope, gravelly alluvium, Chilton like 7% slope, textures include very fine sandy loam and loam Eroded
-

Travessilla like very channery fine sandy loam Duke-Travessilla very channery fine sandy loam Unnamed gravelly fine sandy loam Blanding very fine sandy loam

7B

78
X I 1C (inclusion) XI IAB

14AB Blanding channery very fine sandy loam (inclusion) Sharps channery very fineandy - I6AB loam Oelop channery very fine sandy loam 14AB 7E Zyme very channery clay loam 3CD Duke very channery loam Duke channew loam 1AB Blanding channery very fine sandy loam Sharps channery very fine sandy loam Dulce very channery loam Zyme very channery clay loam Zyme channery clay loam Dulce channery loam X I 1C 6AB 1AB 3AB 3DE 3AB

55"to SH

1

3 0 % ~ 1~ -

1

10' to SH Eroded, variable textures 6" 35% slope with SS fragments 6" to fract. SS 10" to soft. fract. ss Dissected, gravelly alluvium @ 8.5' 8.5' 21" to SH Eroded & shaly

5" to fract. SS 8" to SH Duke over fract. SS also present 6" to fract. SS 40% slopes, smoother slopes 8" Zyme-Travessilla-Duke 4 to 12" to
rock .

XllC Blanding very fine sandy loam Oelop channery very fine sandy loam 3AB (inclusion) Bond channery very fine sandy loam 5 (inclusion) Oelop channery loam 14AB Zyme channery clay loam 3CD Blanding very fine sandy loam XllC Oelop very channery very fine sandy 14AB loam Zyme channery clay loam 7B Oelop very channery very fine sandy 14AB loam Oelop channery very fine sandy loam 6AB (inclusion'l Dulce channery loam Duke very channery fine sandy loam 3DE Zyme very channery loam 7B Soil A extremely channery to 16CE extremely cobbly loam

9'+ 11'+ 12" to SS

Dissected valley remnant Dissected inclusion in 3AB

I ' to soft SS Eroded, range overgrazed I 8" 6'+ Dissected, PJ vegetation 10.5'+ Eroded, 5-10% gravels throughout

7"

Dulce-Zyme-Travessilla, higher OM%, more clav than t v ~ i c a l Higher OM%, remnant in 6AB Higher OM% & some argillic inclusion Unit is 3 to 16" to rock

7'+
5'+
6"

i~

9" 6" to rock

3"

45% slope

October 2003

TABLE 5
J28 COAL RESOURCE AREA, 1406 Acres
Hole#
57 58
I

I Bond very fine sandy loam

I

Soil Name surface texture

1 IAB 1 12" to hard SS 13% slope I I (inclusion) I 1 ~ravessilla channery very fine sandy (1AB 1 18"toSS 1
I I Sharps very fine sandy loam
loam Pulpit very fine sandy loam (inclusion) 6AB 1 (inclusion) ( 6AB

-

I
I

Map Unit

1I Depth to rock 1 Comments 1 profile descriptio,

1

59
60

I 1

40" to SS
36" to SH

I

October 2003

ATTACHMENT I Approval Letter from Office of Surface Mining (OSM) Regarding Proposed Soils Scope-of-Work (SOW); and OSM Soil SuitabilityTable "Topsoil and Topsoil Substitute Suitability Criteria for the Southwestern United States"

United States Department of the Interior
OFFICE OF SURFACE MINING
IN REPLY REFER TO

5&' Pj-dZI

Reclamation and Enforcement 1999 Broadway, Suite 3320 Denver, Colorado 80202-5733

6~
AzOOOl

&

June 25,2003

Mr. Brian Dunfee Environmental Engineering Manager Peabody Western Coal Company P.O. Box 650 Navajo Route 41 Kayenta, Arizona 86033

RE: Baseline Wildlife, Soils and Overburden Studies-Black Mesa
Complex

Dear Mr. Dunfee: The Office of Surface Mining (OSM) is in receipt of Peabody Western Coal Company's (PWCC) letters dated June 3,2003 and June 19,2003. The letters described PWCCJs proposals for gathering baseline data regarding wildlife, soils and overburden in un-mined coal resource areas. This data will be used for future mine planning and permitting activities. We have discussed PWCC's approach to gathering this data during phone conversations and you have received, via email, OSM's Guidance for soil and overburden sampling. PWCC's previous sampling (122 deep cores) and the continuing regraded spoil sampling program, in the existing mining areas, has resulted in excess of 6,000 samples and analyses. The current proposal for soil and overburden sampling is less intense than is recommended in the OSM Guidance. However, based on the above information, OSM is confident that the proposed sampling schemes will provide the needed information as to soil and overburden quality. In addition, PWCC has committed to doing additional overburden sampling if the results of the initial sampling indicates there are unexpected changes in overburden quality from mined areas or areas currently being mined. PWCC has continued to monitor, on an annual basis, several threatened and endangered (T&E)wildlife species and species of special interest and has conducted wildlife studies on an ongoing basis within the leasehold. Therefore, focusing on T&E species and species of special interest and.theircritical habitat should be satisfactory baseline for future mine planning andc'penitting activities.

'2

. , /',/'

Therefore, based upon PWCC's description of proposed baseline studies for wildlife, soils and overburden OSM concurs with the proposals referenced in the above cited letters.

By copy of this letter, OSMNVRCC requests PWCC, other OSM offices, and other agencies to file the attached material appropriately.
If you have questions or concerns please contact me at 303-844-1400 x1496. Sincerely;

(derry D.davette, Leader Black MesaIKayenta Mine Team

J

cclwith enc: AFO BIA-Navajo Regional Office BIA-Western Regional Office BLM-Phoenix Forest Lake Chapter House Hopi Office of Realty Services Hopi Office of Mining & Mineral Resources Navajo Minerals Department

TOPSOIL AND TOPSOIL SUBSTITUTE SUITABILITY CRITERIA* FOR THE SOUTHWESTERN UNITED STATES

Good

Unsuitable

EC mmhoslcm (1)

< 4.0

SAR (2) sl and coarser 1 and cl
40% clay
< 12.0
< 10.0 < 8.0

Texture (3)

Is, sl, I , sil, with 35% c
25-80

s, Ics, cl, sic1 with 45% c

Saturation %

Coarse Fragments (4)
< 3 inch % > 3 inch %

15 3
< .37

Erosion Factor (5) Acid-base potential Boron

+5 T CaC03 equiv.nO00T

-5 T CaC03 equiv.IIO00T

5 PPm

>5 PPm
< - 0.8 ppm
< - 0.15 ppm > 0.8 ppm > 0.15 ppm

Selenium (Total) Selenium (Extractable)

These suitability criteria may be modified on a case by case basis if sufficient data are submitted to support the modifications and the

submitted data technically represent the site specific nature of the modification.
1.

When EC is less than 2.0. then SAR's can not be >18. SAR values can be modified if adequate data is submitted to support proposed modifications. Is=loamy sand; Ics=loarny coarse sand; sl=sandy loam; I=loam; sil=silt loam; scl=sandy clay loam; s=sand; cl=clay loam; sicl=silty clay loam; cl=clay. For topsoil substitutes/supplements, percentage can be increased if it is shown that the higher percentage will increase slope stability andlor vegetation establishment. Suitabilities will be determined on a site specific basis.

2.
3 .

4.

ATTACHMENT 2 Black Mesa Lease Area Map Unit Descriptions (Intermountain Soils, Inc. 1985)

Order 1 and 2 Map Unit Descriptions

1A 1, 1B 1C ID

Dulce very channery fine sandy loam, 1 to 4 percent slopes. Dulce very channery fine sandy loam, 4 to 8 percent slopes. Dulce very channery fine sandy loam, 8 to 15 percent slopes. Dulce very channery fine sandy loam, 15 to 30 percent slopes.
The less steep phases of these map units are found on ridge crests and shoulders whereas the steeper phases are found on shoulders and sideslopes. The soils in these map units are reddish brown and have a surface layer high in rock fragments. Depth to soft or fractured sandstone bedrock is 2 to 10 inches with bedrock generally occurring at less than 6 inches. Contrasting soils which may occur in these map units include Zyme soils found on sideslopes and Bond soils found on ridge crests, soils with bedrock deeper than 20 inches found in concave areas and rock outcrop occurring as narrow escarpments. Similar soils which may occur in these map units include soils with over 35 percent rock fragments, soils that are non-calcareous throughout, and Travessilla soils. Dulce soils are marginally suitable for topsoil and are limited by the amount of rock fragments on the soil surface. The shallow depth to bedrock of these soils may resmct the amount of soil which can be salvaged. The included Bond soils have a good suitability for topsoil and should be salvaged where practicable.

2B

Bond very fine sandy loam, 1 to 8 percent slopes.
This map unit occurs on ridge crests and shoulders throughout the lease area. The Bond soils are reddish throughout and have a surface layer high in very fine sand Depth to hard sandstone bedrock is between 12 and 20 inches. Contrasting soils which may occur in these map units include Dulce soils on shoulders and Sharps soils near the delineated boundaries of this map unit. Soils similar to Bond which may occur in these map units include soils with less than 18 percent clay, soils with less very fine sand, and soils underlain by soft bedrock. Bond soils are suitable for topsoil and have an average stripping depth of 12 inches. The high very fine and fine sand content make these soils susceptible to wind and water erosion.

3A

3BC
3C

3D 3DE

3E

Zyme-Dulce complex, 2 to 8 percent slopes. Zyme-Dulce complex, 2 to 15 percent slopes. Zyme-Duke complex, 6 to 15 percent slopes. Zyme-Dulce complex, 15 to 30 percent slopes. Zyme-Duke complex, 15 to 50 percent slopes. Zyme-Dulce complex, 30 to 50 percent slopes.
The less steep phases of these map units are found on ridge crests and shoulders whereas the steeper phases are found on ridge sideslopes. Generally, Zyme soils are found on the steeper portions of the map units. Zyme soils are variable in color, depending on the color of the underlying shale bedrock. They are clayey throughout and have numerous surficial rock fragments. Dulce soils are reddish brown and also have a surface layer high in rock fragments. Both these soils in these map units are extremely eroded. Depth to soft or fractured bedrock is 2 to 10 inches with bedrock generally occurring at less than 6 inches. Contrasting soils which may occur in these map units include soils deeper than 20 inches, Bond soils, and Soils A and B. Bond soils and Soils A and B are found on ridge crests and sideslopes, and the soils deeper than 20 inches are found in concave areas. Rock outcrop occurs as narrow escarpments. Similar soils which may occur in these map units include those with over 35 percent rock fragments, soils that are non-calcareous throughout, and Travessilla soils.

.

The soils in these map units are marginally suitable for topsoil and are limited by clayey texture of the Zyme soils and high surficial rock fragment content of both soils. The shallow depth to bedrock of these soils may restrict the amount of soil which can be salvaged. The included Bond soils have a good suitability for topsoil and should be salvaged where practicable.

Ustic Torriorthents-rock outcrop complex, 50 to 80 percent slopes.
This map unit occurs on very steep sideslopes of ridges. Because of the slope steepness and the interbedded nature of the bedrock, soils are quite variable and mappd only to the subgroup level. Rock outcrop consists of areas of exposed sandstone or shale bedrock. The soils in this map unit are not considered salvageable because of the steep slopes and high amounts of rock outcrop.

Zyme very channery loam, 1 to 4 percent slopes. Zyme very channery loam, 4 to 8 percent slopes. Zyrne very channery loam, 8 to 15 percent slopes. Zyme very channery loam, 15 to 30 percent slopes.
The less steep phases of these map units are generally found on toeslopes or upper sideslopes, and the steeper phases are found on sideslopes. Zyme soils are variable in color, depending on color of the underlying shale bedrock. They are clayey throughout and have a surface high in rock fragments. Depth to shale bedrock is 2 to 10 inches with bedrock generally occurring at less than 6 inches. Contrasting soils which may occur in these map units include Dulce and Bond soils found on crests and sideslopes, and soils deeper than 20 inches occurring in concave areas. Rock outcrop, where present, occurs as narrow escarpments. Similar soils which may occur in these map units include soils that are noncalcareous throughout and soils with less clay. The soils in these map units are marginally suitable for topsoil and are limited by clayey texture and high surficial rock fragment content. The shallow depth to bedrock of these soils may restrict the amount of soil which can be salvaged. T k included Bond soils have a good suitability for topsoil and should be salvaged where practicable.

Pulpit very fine sandy loam, 2 to 8 percent slopes.
This map unit occurs on valley sideslopes, and crests and sideslopes of ridges. The soils in this map unit are reddish brown and have a surface layer high in very fine sand. Depth to hard sandstone bedrock is 20 to 40 inches. Contrasting soils which may occur in these map units include Cahona soils on sideslopes and Bond soils on crests. Soils similar to Pulpit which may occur in this map unit include soils with less than 18 percent clay and/or a sand fraction with more than 15 percent fine or coarser sand. The 517 mining areas has more of these similar soils than the other mining areas. Sharps is also a similar soil. Pulpit soils are suitable for topsoil and have an average snipping depth of 28 inches. The high very fine and fine sand content make these soils susceptible to wind and water erosion.

Sharps very fine sandy loam, 2 to 8 percent slopes. Sharps very fine sandy loam, 1 to 4 percent slopes. Sharps very fine sandy loam, 4 to 8 percent slopes. Sharps very fine sandy loam, 8 to 15 percent slopes.
The less steep phases of these map units are found on ridge crests and shoulders, and the steep phases are found on shoulders and sideslopes. The soils in these map units are reddish brown and have a surface layer high in very fine sand. Depth to soft or fractured bedrock is 20 to 40 inches. Contrasting soils which may occur in these map units include Cahona soils on sideslopes and Bond soils on crests. Similar soils which may occur in

this map unit include soils with less than 18 percent clay and/or a sand fraction with more than 15 percent fine or coarser sand. The J/7 mining areas has more of these similar soils than the other mining areas. Another similar soil is Pulpit. Sharps soils are suitable for topsoil and have an average stripping depth of 28 inches. The high very fine and fine sand content make these soils susceptible to wind and water erosion.

7B

Travessilla-Zyme-Duke complex, 2 to 6 percent.
This map unit is found primarily in the J17 mining area on ridge crests a d sideslopes. Zyme and Dulce soils are generally found on the sideslopes and the Travessilla soils on the crests. Zyme soils are variable in color, depending on the color of the underlying shale bedrock. They are clayey throughout Travessilla and Dulce soils are reddish brown and are coarse-textured. All of these soils in this map unit are very eroded. Depth to bedrock is 2 to 10 inches with bedrock generally occurring at less than 6 inches. Contrasting soils which may occur in this map unit include soils deeper than 20 inches in concave areas and Bond soils on ridge crests. Rock outcrop also is included. The soils in these map units are marginally suitable for topsoil and are limited by clayey texture of the Zyme soils and high surficial rock fragment content of each of the soils. The shallow depth to bedrock of these soils may restrict the amount of soil which can be salvaged. The included Bond soils have a good suitability for topsoil and should be salvaged where practicable.

7C 7D 7E

Zy me-Travessilla-Rock outcrop complex, 6 to 15 percent slopes.

Zyme-Travessilla-Rock outcrop complex, 15 to 30 percent slopes. Zyme-Travessilla-Rock outcrop complex, 30 to 50 percent slopes.
These map units are also found primarily in the 517 mining area. They are found on sideslopes and include significant amounts of rock outcrop. Zyme soils are found on the steeper portion of the map unit. Zyme soils are variable in color, depending on the color of the underlying shale bedrock. They are clayey throughout. Travessilla soils are reddish brown and are coarse-textured. Both these soils in these map units are very eroded. Depth to bedrock is 2 to 10 inches with bedrock generally occurring at less than 6 inches. Rock outcrop occurs as narrow escarpments. Contrasting soils which may occur in these map units include soils deeper than 20 inches found in concave areas and Bond soils found randomly throughout. Similar soils which may occur in these map units are Dulce soils. The soils in these map units are marginally suitable for topsoil and are limited by the clayey texture of the Zyme soils and the high surficial rock fragment content of both soils. The shallow depth to bedrock of these soils and the amount of rock outcrop occumng in these map units may restrict the amount of soil which can be salvaged. The included Bond soils have a good suitability for topsoil and should be salvaged where practicable.

10 10A 10B
10C

Cahona very fine sandy loam, bedrock substratum, 2 to 8 percent slopes. Cahona very fine sandy loam, bedrock substratum, 1 to 4 percent slopes. Cahona very fine sandy loam, bedrock substratum, 4 to 8 percent slopes. Cahona very fine sandy loam, bedrock substratum, 8 to 15 percent slopes.
These soils are found on valley sideslopes. The soils in these map units are reddish brown and have a surface layer high in very fine sand. Depth to bedrock is 40 to 72 inches. Contrasting soils which may occur in these map units include Cahona soils which are deeper than 72 inches on sideslopes, and Sharps soils on crests. Similar soils which may occur in these map units include soils with less than 18 percent clay and/or a sand fraction with more than 15 percent fine or coarser sand. The 517 mining areas has more of these similar soils than the other mining areas.

Cahona soils are suitable for topsoil and have an average stripping depth of 58 inches. The high very fine and fme sand content make these soils susceptible to wind and water erosion.

11 11A 11B 11C

Cahona very fine sandy loam, 1 to 6 percent slopes. Cahona very fine sandy loam, 1 to 4 percent slopes. Cahona very fine sandy loam, 4 to 8 percent slopes. Cahona very fine sandy loam, 8 to 15 percent slopes.
These soils are found on valley sideslopes. They are reddish brown and have a surface layer high in very fine sand. Depth to soft or fractured bedrock is 72 to more than 180 inches. Contrasting soils which may occur in these map units include Cahona, bedrock substratum, soils on upper sideslopes and Sharps soils on crests. Soils similar to Cahona which may occur in these map units include soils with less than 18 percent clay and/or a sand fraction with more than 15 percent fine or coarser sand. The Jl7 mining areas has more of these similar soils than the other mining areas. Oelop soils are also sirnilar. Cahona soils are suitable for topsoil and have a weighted average stripping depth of 10.0 feet. The high very fine and fme sand content make these soils susceptible to wind and water erosion.

Cahona very fine sandy loam, gravelly substratum, 8 to 15 percent slopes.
This soils occurs on valley sideslopes and alluvial fans in the area of the proposed Wild Ram Dam. It is very similar to the Cahona soil in map unit 11, but is underlain by material high in rock fragments at a depth of 24 to 40 inches. Depth to soft or fractured bedrock is 40 to more than 72 inches.Contrasting soils which may occur in this map unit include Sharps on the upper slopes and Chilton soils on the steeper sideslopes. Similar soils which may occur in these map units include those with less than 18 percent clay and/or a sand fraction with more than 15 percent fine or coarser sand. These soils are suitable for topsoil and have an average smpping depth of 2.5 feet. The high very fine and fine sand content make these soils susceptible to wind and water erosion.

XI1

Cahona-Cahona, bedrock substratum, very fine sandy loams, 2 to 10 percent slopes. X11A Cahona-Cahona, bedrock substratum, very fine sandy loams, 1to 4 percent slopes. X11B Cahona-Cahona, bedrock substratum, very fine sandy loams, 4 to 8 percent slopes. X l l C Cahona-Cahona, bedrock substratum, very fine sandy loams, 8 to 15 percent slopes.
These soils are found on valley sideslopes. The soils in these map units are reddish brown and have a surface layer high in very fine sand. Depth to soft or fractured bedrock is 40 to more than 72 inches. Contrasting soils which may occur in these map units include Sharps soils on crests. Similar soils which may occur in these map units include those with less than 18 percent clay and/or a sand fraction with more than 15 percent fine or coarser sand. The Jl7 mining areas has more of these similar soils than the other mining areas. Oelop soils are also similar. These soils are suitable for topsoil and have an average stripping depth of 7.6 feet. The high very fine and fine sand content make these soils susceptible to wind and water erosion.

12 12A 12B 12C

Begay loam, 2 to 10 percent slopes. Begay loam, 1 to 4 percent slopes. Begay loam, 4 to 8 percent slopes. Begay loam, 8 to 15 percent slopes.
These map units are found on valley-filling sideslopes. These soils are reddish to reddish brown and are coarse-textured. Contrasting inclusions whichmay occur in these map units are soils with bedrock between 40 and 72 inches, primarily in the JI7 area. Similar soils which may occur in these map units include soils with over 18 percent clay and soils lacking a structural B horizon. Begay soils are suitable for topsoil and have an average stripping depth of 9.8 feet. The high very fine and fine sand content make these soils susceptible to wind and water erosion.

13, 13A San Mateo loam, 0 to 3 percent slopes.
This map unit is found on stream terraces and remnant floodplains. The soils in this unit are very deep and are brownish in color. There are no contrasting soils included in the mapping. Soils similar to San Mateo which may occur in this map unit are theelas Lucas and Oelop soils and soils with a sand fraction of less than 15 percent fine or coarser sand. San Mateo soils are suitable for topsoil and have an average stripping depth of 14.7 feet. These soils are affected by salinity andlor sodicity at varying depths. Most of these soils which are saline or sodic are in or near Reed Valley. Depth to high salt or sodium levels ranged from 8 to more than 18 feet.

14A 14B

Oelop very fine sandy loam, 1 to 4 percent slopes. Oelop very fine sandy loam, 4 to 8 percent slopes.
These map units are found on valley sideslopes and bottoms. These soils are brown and are high in very fine and fine sand. These map units tend to occupy relatively small areas but they occur commonly throughout the Black Mesa lease area. No inclusions of contrasting soils were observed within these map units. Soils similar to Oelop found in the study area are the Las Lucas and Cahona soils and soils with a sand fraction of less than 15 percent fine or coarser sand. Oelop soils are suitable for topsoil and have an average smpping depth of 9.8 feet. These soils are affected by salinity andtor sodicity at varying depths. Most of these soils which are saline or sodic are in or near Reed Valley. Depth to unsuitably high levels ranged from 20 to more than 120 inches. The high very fine and fine sand content make these soils susceptible to wind and water erosion.

15, 15A Las Lucas sandy clay loam, 2 to 6 percent slopes.
This map unit is found on lower valley sideslopes. The soils in this unit are very deep and are brownish in color. No inclusions of contrasting soils were observed within this map unit. Similar soils which may occur in this map unit include the Cahona, San Mateo and Oelop soils. Other similar soils included are those with a sand fraction with more than 15 percent fine or coarser sand and those lacking a structural B horizon. Las Lucas soils are suitable for topsoil and have an average stripping depth of 11.6 feet. These soils are affected by salinity and/or sodicity at varying depths. Most of these soils which are saline or sodic are in or near Reed Valley. Depth to unsuitably high levels ranged from 31 to more than 120 inches. The high very fine and fine sand content make these soils susceptible to wind and water erosion.

16C 16E 16F

Soil A-Soil B extremely channery very fine sandy loams, 4 to 15 percent slopes. Soil A-Soil B extremely channery very fine sandy loams, 15 to 50 percent slopes. Soil A-Soil B extremely channery very fine sandy loarns, 50 to 70 percent slopes.
These map units are found on the crests of hills throughout the lease. The soils in these map units forrhed in porcellanite, and as a result, contain a very high volume of rock fragments. Other surface textures found in this map unit are very channery, very cobbly or extremely cobbly very fine to fine sandy loarns. Since these soils are unsuitable for topsoil because of high rock fragment content, they were not sampled or described.

17C--Chilton very gravelly fine sandy loam, 6 to 15percent slopes. This map unit occurs only at the proposed Wild Ram Dam site and is very limited in

areal extent. It occurs on the sideslopes of the alluvial fans in this area. The soil in this map unit were not sampled or described. Based on field observations, this soil has a gravelly fine sandy loam surface layer and a very gravelly sandy loam substratum layers. Because of high rock fragment content in all but the surface layers, these soils are suitable for topsoil down to six inches.

Riverwash.
The riverwash map unit was mapped along the channel of some of the drainages in the permit area Most of the areas are very narrow. These soils are affected by salinity andlor sodicity and are not suitable for topsoil.

Disturbed land.
This map unit consists of land disturbed by activities associated with mining. It is similar to map unit 34 in the Order 3 survey.

Reclaimed land.
This map unit is composed of areas that have been disturbed by mining and subsequently reclaimed. It is similar to map unit 35 in the Order 3 survey.

Topsoil Stockpile.
This map unit consists of stockpiled soil material to be used in reclamation.

ATTACHMENT 3 NRCS Offkial Soil Series Descriptions Begay Blanding Bond Cahona Duke Las Lucas Oelop Pulpit San Mateo Sharps Travessilla Zyme

Official Series Description BEGAY Series

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Page 1 of 4

LOCATION BEGAY

Established Series Rev. RLMIGWLllUB 1012002

BEGAY SERIES
The Begay series consists of very deep, well drained, moderately rapidly permeable soils that formed in eolian deposits and alluvium, derived mainly from sandstone. Begay soils are on structural benches, broad mesas, fan remnants and have slopes of 0 to 30 percent. The average annual precipitation is about 12 inches, and the mean annual temperature is about 48 degrees F. TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Ustic Haplocambids TYPICAL PEDON: Begay loamy fine sand, rangeland. (Colors are for air-dry soil unless otherwise noted.) A--0 to 3 inches; yellowish red (5YR 516) loamy fine sand, yellowish red (5YR 416) moist; single grained; loose; very slightly effervescent, carbonates are disseminated; moderately alkaline (pH 7.9); clear smooth boundary. (2 to 5 inches thick) Bw--3 to 16 inches; yellowish red (5YR 516) very fine sandy loam, yellowish red (5YR 416) moist; weak medium subangular blocky structure; soft, fkiable; common fine roots; few fine pores; slightly alkaline (pH 7.8); clear wavy boundary. (1 1 to 17 inches thick) Bkl--16 to 28 inches; yellowish red (5YR 516) very fine sandy loam, yellowish red (5YR416) moist; weak medium subangular blocky structure; slightly hard, fm;few fine roots; common fine pores; very slightly effervescent, carbonates are disseminated; moderately alkaline (pH 7.9); gradual wavy boundary. (1 0 to 14 inches thick) Bk2--28 to 42 inches; yellowish red (5YR 516) very fine sandy loam, yellowish red (5YR 416) moist; weak medium subangular blocky structure; slightly hard, firm,strongly effervescent, moderately alkaline (pH 8.0); gradual wavy boundary. (12 to 16 inches thick)
p.

C--42 to 60 inches; yellowish red (5YR 518) very fine sandy loam, yellowish red (5YR 518 or 416) moist; massive; soft, very friable; few fine pores; very slightly effervescent, carbonates are disseminated; moderately alkaline (pH 8.1).

TYPE LOCATION: San Juan County, Utah; 7 miles east and 5 miles north of Navajo Mountain School; SW 114, SE 114 sec. 31, T. 42 S., R. 17E.

RANGE IN CHARACTERISTICS:
Soil moisture: In 7 out of 10 years the soils are dry in all parts of the moisture control section for 50 to 75 percent of the time (cumulative) that the soil temperature at depth of 20 inches is above 41

Official Series Description - BEGAY Series

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degrees F. The soils are moist in some part of the moisture control section for 30 to 40 days during the summer and are dry in some part of the moisture control section for 60 to 90 consecutive days during winter and early spring and are moist in some parts between July and October. Mean mual soil temperature ranges fiom - 47 to 57 degrees F Mean summer soil temperature at a depth of 20 inches ranges fiom - 61 to 65 degrees F. Combined thickness of A and B horizons is - 35 to 50 inches. Depth to secondary carbonates accumulation ranges from 7 to 22 inches. Particle-size control section ranges from - 15 to 40 percent fine sand or coarser Rock fragments: 0 to 15 percent
A horizon

-

Hue: 2.5YR to 1OYR Value: 4 to 6 dry, 3 to 5 moist Chroma: 3 to 6 dry or moist Reaction: slightly alkaline or moderately alkaline Calcium carbonate equivalent: ranges fiom 0 to 3 percent. Bw horizon Hue: 2.5YR to 7SYR Value: 4 to 6 dry, 3 to 5 moist Chroma: 4 to 8 dry or moist Texture: ranges from very fine sandy loam, loamy very fine sand, fine sandy loam, sandy loam Reaction: slightly alkaline to strongly alkaline Calcium carbonate equivalent: ranges from 0 to 3 percent.

Bk and C horizons
Hue: 2.5YR to 7.5YR
--.

Value: 5 to 8 dry,and 4 to 8 moist

Official Series Description BEGAY Series

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Page 3 of 4

Chroma: 4 to 6 dry or moist Textures: ranges from very fine sandy loam, fine sandy loam, or sandy loam, and thin strata of gravelly fine sandy loam, or loamy fine sand, below a depth of 40 inches Reaction: ranges fiom slightly alkaline to strongly alkaline. Calcium carbonates equivalent: ranges fiom 0 to 5 percent. Koshare (NM), COMPETING SERIES: These are the Delvalle (NM), Ignacio (NM), Kitsili Oiito (NM), Parida (NM), Remmit (CO), Sandspring (T AZ), and Turnback (WY) series. Delvalle soils have a lithologic discontinuity at 27 to 60 inches and contain 55 to 70 percent sand; Fine sand or coarser content: more than S percent. O Ignacio apd Turnback soils have bedrock at depths of 20 to 40 inches. Parida soils have more than 15 percent rock fiagrnents in the particle-size control section. Remmit and Sandspring soils have hue yellower than 7.5YR. Koshare soils contain 10 to 25 percent mica content in the coarse silt to fine sand fraction. Kitsili soils are effervescence throughout the entire profile and contain less than .6 percent organic matter. Ojito soils are moderately deep to bedrock. GEOGRAPHIC SETTING: Begay soils occur on fan remnants, structural benches, broad and mesa tops at elevations of 4,700 to 7,400 feet. Slopes are 0 to 30 percent. These soils formed in deep eolian deposits and alluvium from sedimentary rocks. The climate is semiarid and the average annual precipitation ranges fiom 8 to 14 inches. The mean annual temperature is 44 to 55 degrees F. The mean summer temperature is 59 to 63 degrees F. and the freeze-free period ranges fiom 110 to 175 days. GEOGRAPHICALLY ASSOCIATED SOILS: These are Anasazi, Aneth and Soazie soils. Anasazi soils have calcic horizon and lithic contact at 20 to 40 inches. Aneth soils do not have cambic horizons but have a sandy particle size control section. Sogzie soils have calcic horizons. DRAINAGE AND PERMEABILITY: Well drained; very slow to medium runoff; moderately rapid permeability. USE AND VEGETATION: Used only as rangeland. Potential vegetation is needleandthread, big sagebrush, blue grama, Indian ricegrass. DISTRIBUTION AND EXTENT: Southeastern Utah and northwestern Colorado. Begay soils are moderately extensive. MLRA 34,35 and 48A.

m),

MLRA OF'FICE RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: San Juan County, Utah, 1976.

REMARKS:
These soils have been correlated to semidesert range sites in Utah. http://ortho.ftw.nrcs.usda.gov/cgi-bin~osd~osdname.cgi?-P

Official Series Description - BEGAY Series

Page 4 of 4

Diagnostic horizons and features recognized in this pedon are: Ochric epipedon - fkom 0 to 3 inches (A horizon). Cambic horizon - from 3 to 16 inches (Bw horizon). The Bk horizon is assumed to have too little carbonate to be a calcic horizon.

In December 1994 the classification was changed fkom Ustollic Camborthids to Ustic Haplocambids.
Classified according to Soil Taxonomy Second Edition, 1999.
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National Cooperative Soil Survey U.S.A.

Official Series Description - BLANDING Series

Page 1 of 3

LOCATION BLANDING

Established Series Rev. TBH/AJE/MJD 7/97

BLANDING SERIES
The Blanding series consists of very deep, well drained soils that formed in eolian deposits derived mainly fram sandstone. Blanding soils occur on gently sloping and rolling uplands, and have slopes of 2 to 10 percent. The average annual precipitation is about 12 inches, and the mean annual air temperature is about 50 degrees F. TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Ustic Haplargids TYPICAL PEDON: Blanding very fine sandy loam, rangeland. (Colors are for air dry soil unless otherwise stated.) A--0 to 4 inches; reddish brown (5YR 514) very fine sandy loam, reddish brown (5YR 414) moist; weak thin and medium platy structure; slightly hard, fiiable, nonsticky and nonplastic; many fine roots; moderately alkaline (pH 8.1); abrupt wavy boundary. (3 to 8 inches thick) Bt--4 to 16 inches; yellowish red (5YR 516) sandy clay loam, yellowish red (5YR 316) moist; weak coarse prismatic structure that parts to very weak medium subangular blocky, slightly hard, fkiable, slightly sticky and slightly plastic; many fine pores; slightly alkaline (pH 7.7); clear wavy boundary. (9 to 25 inches thick) Btkl-- 16 to 50 inches; reddish yellow (5YR 416) very fine sandy loam, yellowish red (5YR 416) moist; moderate medium subangular blocky structure; extremely hard, firm, slightly sticky and slightly plastic; few fme roots; few fme pores; moderately calcareous; moderately alkaline (pH 8.1); clear smooth boundary. (15 to 35 inches thick) Btk2--50 to 60 inches; reddish yellow (5YR 616) sandy clay loam, yellowish red (5YR 416) moist; i m slightly plastic; moderately moderate medium subangular blocky structure; very hard, f r , calcareous; moderately alkaline (pH 8.2). (8 to 15 inches thick)

TYPE LOCATION: San Juan County, Utah; about 6.5 miles south of Blanding; 200 feet south of trail and 0.4 miles west of Utah Highway 47; NW 114NE1/4 sec. 33, T.37S., R.22E. RANGE IN CHARACTERISTICS: The depth to carbonate accumulation ranges fiom 9 to 30 inches. Organic matter in the upper 15 inches ranges from -4to -9 percent. The mean annual soil temperature at depth of 20 inches ranges from 52 degrees to 55 degrees F., and the average summer soil temperature ranges fiom 68 degrees to 73 degrees F. In more than 7 out of 10 years, the moisture control section is dry in some parts 25 to 45 consecutive days during the summer and is dry in all parts 50 to 75 percent of the time when the soil temperature is above 41 degrees F.

Official Series Description - BLANDING Series

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The A horizon has value of 3 or 4 moist, 5 or 6 dry, and chroma of 4 through 6. It is dominantly very fine sandy loam but ranges to fine sandy loam. The A horizon is neutral to moderately alkaline. In some pedons thin BA horizons are present above the argillic horizon. The Bt horizon has value of 3 through 5 moist, 5 or 6 dry, and chroma of 4 through 6. It is dominantly sandy clay loam, but includes very fine sandy loam or loam. This horizon has 18 to 27 percent clay and less than 15 percent coarser than very fine sand. It is neutral to moderately W i n e . The Btk or Bk horizons have value of 4 or 5 moist, 5 or 6 dry, and chroma of 4 through 6. It ranges fiom very fine sandy loam to sandy clay loam. This horizon has 3 to 12 percent calcium carbonate. It is slightly or moderately alkaline. Buried horizons occur in places at depths below 40 inches. COMPETING SERIES: This is the Snapill (T) series. Snapill soils have a calcic horizon. GEOGRAPHIC SETTING: Blanding soils are on uplands and plateaus, at elevations of 5,000 to 6,500 feet in a semiarid climate. Slopes are 2 to 10 percent. These soils formed in eolian deposits derived mainly fiom sandstone. Average annual precipitation is 8 to 13 inches. The mean annual temperature is 50 degrees to 54 degrees F. The mean summer temperature is 70 degrees to 73 degrees F. The fiost-free period is 130 to 150 days. GEOGRAPHICALLY ASSOCIATED SOILS: This is the the Northdale series. Northdale soils have mollic epipedons. DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability. USE AND VEGETATION: Used mainly for rangeland. Some areas are used for irrigated or nonirrigated cropland. Vegetation is dominantly blue grama, galleta, Wyoming big sagebrush, Indian ricegrass, and snakeweed. DISTRIBUTION AND EXTENT: Southeastern Utah, western Colorado, northeastern Arizona, northwestern New Mexico. These soils are of moderate extent.

MLRA OFFICE RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: San Juan County, Utah, 1952.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone fiom 0 to 4 inches (A horizon). Argillic horizon - the zone from 4 to 16 inches (Bt horizon) Ustalfic feature - dry in all parts of the moisture control half to three-fourths of the time, and soil moisture regime is aridic bordering on ustic.

Official Series Description - BLANDING Series

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National Cooperative Soil Survey U.S.A.

Official Series Description - BOND Series

Page 1 of 3

LOCATION BOND

NM+AZ CO UT

Established Series Rev. TLPICDLILWHISAUWWJ 0412002

BOND SERIES
The Bond series consists of very shallow and shallow, well drained, moderately permeable soils that formed in alluvium, slope alluvium, and eolian deposits derived from sandstone on cuestas, mesas, hills and ridges. Slopes range from 0 to 50 percent. The mean annual precipitation is about 11 inches and mean annual temperature is about 5 1 degrees F. TAXONOMIC CLASS: Loamy, mixed, superactive, mesic Lithic Ustic Haplargids TYPICAL PEDON: Bond sandy loam - on dipslopes; northeast aspect of cuesta with 4 percent slopes - rangeland. (Colors are for dry soil unless otherwise noted.) A--0 to 3 inches; brown (7.5YR 514) sandy loam, brown (7.5YR 414) moist; weak fine granular structure; soft, very fiiable, nonsticky and nonplastic; few medium, fine and very fine roots; few very fine irregular pores; neutral; clear smooth boundary. (2 to 4 inches thick) BA--3 to 7 inches; brown (7.5YR 514) sandy loam, brown (7.5YR 414) moist; weak medium subangular blocky structure; soft, very fiiable, nonsticky and nonplastic; few very fine and fine roots; common very fine irregular pores; neutral; abrupt smooth boundary. (0 to 4 inches thick) Bt--7 to 13 inches; reddish brown (5YR 414) sandy clay loam, reddish brown (5YR 414) moist; moderate medium subangular blocky structure; hard, fiiable, sticky and slightly plastic; common moderately thick clay films on faces of peds and lining pores; common very fine and few fine roots; common very fine and fine tubular pores; neutral; abrupt smooth boundary. (5 to 12 inches thick) C--13 to 16 inches; light brown (7.5YR 614) sandy clay loam; brown (7.5YR 514) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; common very fine irregular pores; strongly effervescent; moderately alkaline; abrupt smooth boundary. (0 to 4 inches thick)

2R--16 inches; sandstone.
TYPE LOCATION: Cibola County, New Mexico; about 7 miles north of Milan; Bluewater Quadrangle; 300 feet south and 2,600 feet east of the northwest corner, sec. 8, T. 12 N., R. 10 W. RANGE IN CHARACTERISTICS: Soil Moisture: Usually dry, dry in all parts of the soil moisture control section in late spring and early summer, but moist intermittently in some part of the soil moisture control section fiom July to October.

Oficial Series Description - BOND Series

Page 2 of 3

Soil Temperature: 5 1 to 55 degrees F. Depth to lithic contact: 6 to 20 inches Rock fragments in the profile: 0 to 35 inches Clay content in the particle-size control section: 18 to 35 percent
A horizon Hue: 5YR, 7.5YR or 10YR Value: 4 to 6 dry, 3 through 5 moist Chroma: 2 to 4 Texture: loamy fine sand, sandy loam or fine sandy loam BA horizon (where present) Hue: 5YR or 7.5YR Value: 4 to 6 dry, 4 or 5 moist Chroma: 3 or 4 Texture: sandy loam, sandy clay loam or fine sandy loam

Bt horizon Hue: 5YR or 7.5YR Value: 4 or 6 dry, 3 to 6 moist Chroma: 3 to 6 Texture: sandy clay loam, loam, sandy loam or clay loam C horizon Hue: 5YR or 7.5YR Value: 5 to 8 dry, 5 or 6 moist Chroma: 4 through 6 dry and moist Fine earth fraction: sandy clay loam, loam, sandy loam or clay loam Some pedons have Btk horizons

COMPETING SERIES: These are the Barboncito, Bondman, Frontier, and Kech series. series. The Barboncito soils have cooler mean annual temperatures and receive more effective winter moisture. Bondman soils have soil temperatures ranging fiom 47 to 50 degrees F, and receive more winter moisture. Frontier and Kech soils have horizons with segregated secondary carbonates. In addition, Frontier soils have hue yellower than 7.5YR in the argillic horizon and are in LRR-G and are moist in _May and June. GEOGRAPHIC SETTING: Bond soils are on cuestas, mesas, hills, and ridges with slopes ranging from 0 to 50 percent. They formed in alluvium, slope alluvium, and eolian deposits from sandstone. Elevations are 5,600 to 7,200 feet. Typically, the average annual precipitation is 10 to 13 inches, but ranges to 15 inches in some areas; mean annual temperature is 49 to 54 degrees F. The frost-fiee period is 110 to 160 days. In Colorado, the temperature ranges as low as 43 degrees F. In Arizona elevations are as low as 4,500 feet, temperatures as high 55 degrees and frost free as long as 165 days

,

Official Series Description - BOND Series

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GEOGRAPHICALLY ASSOCIATED SOILS: These are the Apare-io, Hagerman, Penistaja and S h i l l a g e soils. Aparejo and Penistaja soils are deep. Hagerman soils have lithic contact between 20 and 40 inches. Skyvillage soils do not have argillic horizons. DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderately permeable. USE AND VEGETATION: The major use of this soil is for livestock grazing. The present vegetation is blue grama, sideoats grama, New Mexico feathergrass, Indian ricegrass, scattered oneseed juniper, and winterfat. DISTRIBUTION AND EXTENT: West-central New Mexico, Northern Arizona, southwestern Colorado and southern Utah. MLRA 36, LRR-D. The series is of moderate extent.

MLRA OF'FICE RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Zuni Mountain Area, New Mexico; McKinley County, New Mexico; 1964.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric Horizon - The zone from 0 to 3 inches (A horizon). Argillic Horizon - The zone from about 7 to 13 inches (Bt horizon). Lithic contact - the boundary with sandstone at 16 inches The type location of the Bond series was moved fiom McKinley to Cibola County in 1984 to better reflect the present concepts of the Bond series. Classified according to Soil Taxonomy Second Edition, 1999. National Cooperative Soil Survey U.S.A.

Official Series Description - CAHONA Series

Page 1 of 4

LOCATION CAHONA

Established Series Rev. DKRIJWWWWJ 0612000

CAHONA SERIES
The Cahona series consists of very deep, well drained soils that formed in eolian material derived from sandstone. Cahona soils are on hills and mesas. Slopes range from 1 to 12 percent. Mean annual precipitation is about 14 inches and the mean annual temperature is about 48 degrees F. TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Calcidic Haplustalfs TYPICAL PEDON: Cahona loam, on a south facing, 4 percent slope in rangeland at an elevation of 6,800 feet. (Colors are for dry soil unless otherwise noted.) Al--0 to 1 inch; reddish brown (5YR 414) loam, dark reddish brown (5YR 314) moist; single grain, loose, loose, nonsticky and nonplastic; slightly effervescent; slightly alkaline (pH 7.5); clear smooth boundary. (1 to 8 inches thick) A2--1 to 5 inches; reddish brown (5YR 414) loam, dark reddish brown (5YR 314) moist; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots throughout; common very fine discontinuous tubular pores; noneffervescent; slightly alkaline (pH 7.4); clear smooth boundary. (0 to 6 inches thick) Bt--5 to 15 inches; yellowish red (5YR 416) clay loam, reddish brown (5YR 414) moist; moderate medium prismatic structure parting to moderate medium angular blocky; hard, fiiable, slightly sticky and moderately plastic; common fine roots throughout; common fine discontinuous tubular pores; slightly effervescent; slightly alkaline (pH 7.8); gradual smooth boundary. (4 to 16 inches thick). Btk--15 to 25 inches; yellowish red (5YR 516) clay loam, reddish brown (5YR 414) moist; weak medium prismatic structure parting to moderate medium angular blocky; hard, fiiable, moderately sticky and moderately plastic; common fine and medium roots throughout; common fine discontinuous tubular pores; common fine irregular soft masses of carbonate; violently effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (3 to 15 inches thick). Bkl--25 to 38 inches; pinkish white (5YR 812) loam, light reddish brown (5YR 613) moist; weak coarse prismatic structure parting to moderate medium subangular blocky; hard, firm, slightly sticky and moderately plastic; common medium roots throughout; 43 percent calcium carbonate equivalent; violently effervescent; strongly alkaline (pH 8.6); clear wavy boundary. (6 to 20 inches thick). Bk2--38 to 60 inches; pinkish gray (5YR712) loam, light reddish brown (5YR 613) moist; massive; hard, firm, slightly sticky and slightly plastic; common medium roots throughout; violently effervescent; moderately alkaline (pH 8.4)

Official Series Description - CAHONA Series

Page 2 of 4

TYPE LOCATION: Dolores County, Colorado; about 5 miles northwest of Dove Creek; located about 500 feet south and 1500 feet east of the northwest corner of sec. 9, T. 41 N., R. 19 W.; Dove Creek USGS quad; lat. 37 degrees 47 minutes 12 seconds N. and long. 108 degrees 56 minutes 24 seconds W., NAD RANGE IN CHARACTERISTICS: Soil moisture regime: ustic bordering on aridic Soil temperature regime: mesic Mean annual soil temperature: 48 to 52 degrees F Mean annual summer soil temperature: 63 to 67 degrees F Particle-size control section: 18 to 35 percent clay Depth to calcic horizon: 20 to 40 inches Depth to secondary calcium carbonate: 5 to 30 inches Depth to the base of the argillic horizon: 20 to 30 inches
A horizon: Hue: 5YR or 7.5YR Value: 4 to 7 (3 to 6 moist) Chroma: 2 to 6 Texture: fine sandy loam or loam Rock fragments: 0 to 5 percent Calcium carbonate equivalent: 0 to 1 percent Reaction: neutral or slightly alkaline

Bt and Btk horizon: Value: 4 to 7 dry (3 to 5 moist) Chroma: 3 to 6 Texture: loam or clay loam Calcium carbonate equivalent: 0 to 10 percent Rock fragments: 0 to 5 percent Reaction: slightly to strongly alkaline

t

Bk horizon: Hue: 5YR to 7.5YR Calcium carbonate equivalent: 15 to 50 percent Reaction: slightly to strongly alkaline
COMPETING SERIES: This is the Plughat and Villegreen series. Plughat soils are deep. Villegreen soils are moderately deep.

Official Series Description - CAHONA Series

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GEOGRAPHIC SETTING: Parent material: eolian material derived from sandstone Landform: hills and mesas Slopes: 1 to 12 percent Elevation: 6,200 to 7,400 feet Mean annual temperature: 46 to 50 degrees F Mean annual precipitation: 13 to 16 inches Precipitation is fairly evenly distributed throughout the year with July and August being slightly wetter and June being slightly dryer. Frost-free period: 100 to 120 days GEOGRAPHICALLY ASSOCIATED SOILS: These are the Wetherill, Pulpit, and Sharps series. All these soils are on the same landscape positions as Cahona. Wetherill soils have a calcic horizon below 40 inches. Pulpit and Sharps soils have bedrock above 40 inches. DRAINAGE AND PERMEABILITY: well drained, medium to very high runoff, moderately slow or slow permeability USE AND VEGETATION: These soils are used for dryland and irrigated cropland, and for grazing. The native vegetation is scattered pinyon and juniper, big sagebrush, Indian ricegrass, muttongrass, and western wheatgrass. DISTRIBUTION AND EXTENT: Southwest Colorado and southeast Utah. LRR D, MLRA 36. This series is of moderate extent.

MLRA OFFICE RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Canyonlands Area, Utah - parts of Grand and San Juan counties Utah. August 1983. REMARKS: This OSED reclassified the Cahona series into the 13 to 16 inch precipitation zone in southwest Colorado and Utah. Change results from the Four Corners Climate Conference of 10/92. a Type location w s moved to better reflect the central concept of the Cahona series. Diagnostic horizons and features recognized in this pedon are: Ochric epipedon: The zone from 0 to 5 inches. (Al, A2 horizons) Argillic horizon: The zone from 5 to 25 inches. (Bt, Btk horizons)

Official Series Description - CAHONA Series

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Calcic horizon: The zone ftom 25 to 60 inches. (l3k1, Bk2) Particle size control section: The zone from 5 to 25 inches. (Bt, Btk) Particle size control section: The zone fiom 5 to 25 inches. (Bt, Btk) Soil Taxonomy Second Edition, 1999 National Cooperative Soil Survey U.S.A.

Official Series Description - DULCE Series

Page 1 of 3

LOCATION DULCE

Tentative Series Rev. GBIJPP 0212003

DULCE SERIES
The Duke series consists of shallow, or very shallow, well drained soil that formed in residuum from sandstone. Duke soils are on foothill slopes and ridges. Slopes range from 6 to 60 percent. Mean annual precipitation is about 14 inches, and mean annual temperature is about 49 degrees F. TAXONOMIC CLASS: Loamy, mixed, superactive, calcareous, mesic, shallow Ustic Torriorthents TYPICAL PEDON: Duke sandy loam - native range with pinyon-juniper (Colors are for dry soils unless otherwise noted). A--0 to 4 inches; brown (10YR 513) sandy loam, brown (1O Y R 413) moist; weak medium granular structure; soft, very friable; nonsticky and nonplastic; 2 percent stones; moderately alkaline (pH 8.0); clear smooth boundary. (2 to 6 inches thick) AC--4 to 9 inches; grayish brown (10YR 512) sandy loam, dark grayish brown (10YR 412) moist; very weak medium subangular blocky structure parting to weak fine granular; soft, very fiiable; nonstick nonplastic; 2 percent stones; slightly effervescent; moderately alkaline. (3 to 10 inches thick) Ck--9 to 13 inches; very pale brown (10YR 713) sandy loam, pale brown (10YR 613) moist; massive; soft, very fiiable, nonsticky and nonplastic; violently effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (2 to 5 inches thick) Cr--13 to 17 inches; soft sandstone and interbedded sandy shale that can be dug with an auger and a spade. TYPE LOCATION: La Plata County, Colorado; 700 feet south and 300 feet west of the northeast corner of Sec. 4, T. 32 N., R. 10 W. U.S.G.S. Long Mountain quad.; Lat. 37 degrees, 03 minutes, 05 seconds N., and Long. 107 degrees, 55 minutes, 49 seconds W. RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges fiom 47 to 52 degrees F. Depth to the paralithic contact is 8 to 20 inches. Bedrock is soft sandstone or sandy shale. Coarse fragments range fiom 0 to 20 percent and are typically sandstone chips ranging fiom pebble to stone size. Typically, these soils contain fiee carbonates throughout, but some pedons may be leached as much as 5 inches. Clay content of the particle-size control section ranges from 5 to 18 percent, sand fiom 50 to 80 percent, and silt fiom 5 to 45 percent. The moisture control section is dry for 15 consecutive days from May 15 to July 15 when the soil temperature at 20 inches is greater than 41 degrees F., (5 degrees C.). It is not dry in all parts of the moisture control section for at least 45 consecutive days following the summer solstice to October 20, and for at least 90 cumulative days during that period.

Official Series Description - DULCE Series

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The A horizon has hue of 1OYR or 2.5Y, value of 5 or 6,4 or 5 moist, and chroma or 2 or 3. It is slightly alkaline or moderately alkaline. The AC horizon has hue of lOYR or 2.5Y, value of 5 to 6,4 or 5 moist, and chroma of 2 or 3. Reaction is slightly alkaline or moderately alkaline. The C horizon has hue of 10YR or 2.5Y, value of 6 or 7 dry, or 6 moist, and chroma of 2 through 4. It is slightly alkaline or moderately alkaline. Fairburn (SD), COMPETING SERIES: These are the Canyon (NE), Epping (NE), Eslendo Gent (UT), Kinusta (AZ), Klondike (AZ), Picante, (CO), Redarrow (WY), Sandoval (NM), Shingle (WY), Spearfish (SD), Taluce (WY), and Tassel (NE) series. The Canyon, Eslendo, Fairburn, Gerst, Picante, Sandoval, Shingle, and Spearfish soils have more than 18 percent clay in the particle-size control section. Epping and Tassel1 soils are dry less than 15 consecutive days throughout the soil 15 and July 15, and are in a climatic setting that receives over moisture control section between half of the precipitation between April and August. Kinusta soils have particle-size control sections that are very fine sandy loam or silt loam. Klondike and Redarrow soils have hue of 5YR or redder. Taluce soils are dry in all parts of the moisture control section for at least 60 consecutive days from July 15 to October 25, and for at least 90 cumulative days during this period. GEOGRAPHIC SETTING: Dulce soils are on foothill slopes and ridges. Slope ranges from 6 to 60 percent. The soils formed in residuum from sandstone. Elevation ranges from 5,000 to 7,500 feet. Average annual precipitation ranges from 13 to 16 inches and about half comes as snow. The precipitation is distributed fairly evenly throughout the year with May and June being the driest months. Mean annual temperature ranges from 45 to 50 degrees F., and mean summer temperature ranges from 60 to 66 degrees F. P.E. Index is about 42 at the type location and ranges from 35 to 50 for the series. GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lazear, Mikim, Travessilla, and Zyne soils. Lazear and Travessilla soils are shallow, loamy soils over hard sandstone. Mikim soils are deep, loamy soils on gently sloping to sloping alluvial fans, toe slopes, and foothill valleys. Zyme soils are shallow, fme-textured soils over shale. DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately rapid permeability to bedrock. USE AND VEGETATION: Dulce soils are used primarily for rangeland and wildlife habitat. Native vegetation consists of western wheatgrass, Indian ricegrass, junegrass, sand dropseed, needleandthread grass, blue grama, Red three-awn, big sagebrush, pinyon pine, and Rocky Mountain juniper. DISTRIBUTION AND EXTENT: Dulce soils occur in southwestern Colorado and possibly adjacent parts of Utah. The series is of moderate extent.

MLRA OFFICE RESPONSIBLE: Phoenix, Arizona
SERIES PROPOSED: La Plata County Area, Colorado, 1982.

Official Series Description - DULCE Series

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REMARKS: Diagnostic features include an ochric epipedon fiom 0 to 4 inches. Particle-size control section with 5 to 18 percent clay. A paralithic contact at 13 inches, and a mesic temperature regime. Last updated by the state 3/95.
National Cooperative Soil Survey U.S.A.

Official Series Description - LAS-LUCAS Series

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LOCATION LAS LUCAS

Established Series Rev. W W J 1012002

LAS LUCAS SERIES
The Las Lucas series consists of deep, well drained, slowly permeable soils that formed fiom gray and olive shales on alluvial fans and valley fill side slopes. Mean annual precipitation is about 15 inches, and mean annual temperature is about 50 degrees F. TAXONOMIC CLASS: Fine-silty, mixed, active, mesic Ustic Haplocambids TYPICAL PEDON: Las Lucas clay loam A--0 to 8 inches; pale brown (1OYR 613) clay loam, brown (10YR 413) moist; weak medium platy structure in the upper 1 or 2 inches, moderate fine granular structure in the lower part; slightly hard, fiiable; abundant roots; weakly calcareous in upper 4 inches becoming strongly calcareous in lower part; clear boundary. 5 to 10 inches thick. Bw--8 to 15 inches; brown (10YR 513) heavy clay loam, brown (10YR 413) moist; moderate medium and coarse subangular blocky structure; hard, &able; roots are common; very strongly calcareous; clear irregular boundary. 5 to 9 inches thick. Bk-- 15 to 22 inches; yellowish brown (10YR 514) clay loam, dark yellowish brown (10YR 414) moist; weak angular and subangular blocky structure; very hard, firm; very strongly calcareous; this is a weak ca horizon with a few small calcium carbonate concretions; gradual boundary. 5 to 10 inches thick. Ck--22 to 40 inches; pale olive (5Y 613) light clay loam, light olive brown (2.5Y 513) moist; massive; hard, fiiable; strongly calcareous; this is a weak ca horizon with a few small calcium carbonate concretions and thin seams; gradual boundary. 8 to 14 inches thick. R--40 to 50 inches +; Gray and olive shales, laminated and with common salt crystals between the laminations.

TYPE LOCATION: Sandoval County, New Mexico, 20 feet NE of SW corner of section 16, T19N, R2W.
RANGE IN CHARACTERISTICS:
A horizon Hue: 1OYR and 2.5Y Chroma: 2 and 3 Value: 5 and 6 dry and 3 and 4 moist (Surface horizons having values as dark as 5 dry and 3 moist

Official Series Description - LAS-LUCAS Series

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should not exceed 4 inches in thickness) Texture: loam or clay loam Calcium carbonate: noncalcareous to weakly calcareous

B horizon Hue: 1OYR to 5Y Chroma: 3 through 4 Value: 5 to 7 dry and 3 to 5 moist Texture: clay loam Clay content: 27 to 35 percent Silt content: 20 to 60 percent Sand content: 10 to 45 percent Depth to shale bedrock: greater than 40 inches
COMPETING SERIES: There are no competing series. GEOGRAPHIC SETTING: Nearly level to sloping alluvial fans and valley filling slopes. GEOGRAPHICALLY ASSOCIATED SOILS: DRAINAGE AND PERMEABILITY: Well drained; slow permeability; runoff is rapid. USE AND VEGETATION: Western wheatgrass, alkali sacaton, blue grama and galleta. Rangeland. DISTRIBUTION AND EXTENT: Central and north central New Mexico. MLRA OFFICE RESPONSIBLE: Phoenix, Arizona SERIES ESTABLISHED: The Upper Puerco Reconn. Survey, SCS, 1937. REMARKS: Diagnostic horizons and features recognized in this pedon are: Ochric Epipedon - The zone fiom the surface to a depth of 8 inches. (A horizon) Cambic horizon - The zone fiom 8 to 15 inches. (Bw horizon) Classified according to Soil Taxonomy Second Edition, 1999. Series name after a small village in Bernalillo County, New Mexico. Soil at type location differs from typical profile for series description by having a light clay texture at 8 to 15 inches and having slightly coarser structure throughout the horizon. OSED scanned by SSQA. Last revised by state on 1/24/64. National Cooperative Soil Survey U.S.A.

Official Series Description - OELOP Series

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LOCATION OELOP

NM

Established Series Rev. JERIRJAILWH 1112000

OELOP SERIES
The Oelop series consists of very deep, well drained soils that formed in alluvium and eolian material derived fiom sandstone and shale. Oelop soils are on stream terraces, mesas, plateaus and alluvial fans. Slopes are 0 to 10 percent. The mean annual precipitation is about 11 inches, and the mean annual temperature is about 51 degrees F. TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Ustic Haplargids TYPICAL PEDON: Oelop loam--rangeland. (Colors are for dry soil unless otherwise stated.) A--0 to 3 inches; dark yellowish brown (10YR 414) loam, dark yellowish brown (10YR 314) moist; weak fine granular structure; soft, very fiiable, slightly sticky and slightly plastic; few fine and medium roots; few fine irregular pores; slightly alkaline; abrupt smooth boundary. (3 to 6 inches thick) Btl--3 to 8 inches; dark yellowish brown (10YR 414) clay loam, dark yellowish brown (IOYR 314) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and medium roots; few fine tubular pores; common moderately thick clay films on faces of peds and in pores; slightly alkaline; clear smooth boundary. (4 to 9 inches thick) Bt2--8 to 16 inches; dark yellowish brown (1OYR 414) clay loam, dark yellowish brown (10YR 314) moist; moderate medium subangular blocky structure; slightly hard, friable, sticky and plastic; few very fine and medium and common fine roots; few fine tubular pores; common moderately thick clay films on faces of peds and in pores; slightly alkaline; clear smooth boundary. (3 to 15 inches thick) Bkl--16 to 34 inches; dark yellowish brown (IOYR 414) clay loam, dark yellowish brown (10YR 314) moist; massive; slightly hard, fiiable, sticky and plastic; few very fine and fine roots; few fine irregular pores; slightly effervescent with disseminated calcium carbonate; moderately alkaline; clear smooth boundary. (3 to 26 inches thick) Bk2--34 to 44 inches; dark yellowish brown (10YR 414) loam, dark yellowish brown (10YR 314) moist; massive; slightly hard, fiiable, slightly sticky and slightly plastic; few very fine and irregular pores; strongly effervescent; calcium carbonate occurs as few fine irregular filaments; moderately alkaline; clear smooth boundary. (3 to 30 inches thick) Bk3--44 to 64 inches; dark yellowish brown (10YR 414) loam, dark yellowish brown (10YR 314) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine irregular pores; strongly effervescent; calcium carbonate occurs as few fine irregular filaments; moderately alkaline.

Official Series Description - OELOP Series

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TYPE LOCATION: Cibola County; about 4 5 miles southwest of south Garcia; 2,480 feet east and . 100 feet north of the southwest corner of Sec. 33, T. 8 N., R. 3 W. 107 degrees, 10 minutes, 00 seconds west longitude; 34 degrees, 52 minutes, 28 seconds north latitude. RANGE IN CHARACTERISTICS: Soil moisture - The soil moisture control section is typically dry in all parts during April, May and June and are moist in some part periodically July through October. It is dry in all parts 50 to 75 percent of the time that the soil temperature is above 41 degrees F. Soil temperature - 50 to 55 degrees F. Depth to the base of the argillic horizon - 1 to 30 inches. 5

8 Particle-size control section - Texture: loam, clay loam or silty clay loam. Clay content: 1 to 35 percent Sand content: 1 to 40 percent with less than 1 finer than fine sand. Rock fragments: less 5 5 than 5 percent dominantly pebbles.
A horizon - Hue: 5 Y R through 10YR.Value: 4 through 6 dry, 3 through 5 moist. Chroma: 3 or 4. Texture: loam, silt loam, fine sandy loam, or sandy loam. Bt horizon - Hue: 5YR through 10YR.Value: 4 through 6 dry, 3 through 5 moist. Chroma: 3 or 4. Lower subhorizons have fine seams of carbonate in some pedons. Bk horizon - Hue: 5YR through 10YR.Value: 4 through 7 dry, 4 through 6 moist. Chroma: 3 through 6. Texture: sandy loam, loam, sandy clay loam, clay loam or silty clay loam. Calcium carbonate equivalent: less than 15 percent. COMPETING SERIES: These are the Balon(AZ), &(UT), Bowbac(WY), B u c k l e o , Cambria (WY), C e r r i l l o s O , Clovis(NM), Cushman(WY), Decolney(T)(AZ), F&(MT), Fernando(NM), F l a c o o , Forkwood(WY), Fort Collins(CO), Gaddes(AZ), Gapbutte(T)(AZ), H a g e r m a n o , Harbord(CO), Hiland(WY), Los A l a m o s o , Maysdorf(WY), Millett(AZ), Olney(NM), Palacid 0, Penistaia(NM), Pokeman(WY), Potts(WY), Progresso(CO), Pugsley(WY), Rauzi(T)(WY), Scholle(NM), Spangler(WY), Spenlo(UT), Stoneham(CO), Sundance(CO), Tapia(NM), Threetop (WY), Toluca(MT), Tuweep(AZ), and Yenlo(C0) series. Balon, Decolney, Gaddes and Rauzi soils are noncalcareous throughout. Bam, Cerrillos, Clovis, Fernando, Hiland, Los Alamos, Millett, Scholle, Sundance, Tapia, Toluca and Tuweep soils have calcic horizons. Bowbac, Cushman, Fattig, Flaco, Gaddes, Gapbutte, Hagerman, Pokeman, Progresso, Pugsley and Spangler soils have bedrock at depths between 20 and 40 inches. Buckle, Mxsdorfand Palacid soils are deeper than 40 inches to the base of the argillic horizon. Cambria and Stoneham soils are 10 to 15 inches to the base of the Bt horizon. Forkwood, Collins, Harbord, Olney, Potts and Threetop soils are moist in some part, periodically, during April, May and June. ~enistaja Yenlo soils have more than 40 and sand. Spenlo soils are deeper than 30 inches to the base of the argillic horizon and are noncalcareous to depths of 30 inches. GEOGRAPHIC SETTING: Oelop soils are on stream terraces, mesas, plateaus and alluvial fans, with slopes of 0 to 10 percent. Elevations range from 5,900to 7,500feet. The mean annual precipitation ranges from 10 to 12 inches. The mean annual temperature is about 48 to 53 degrees F.,

Official Series Description - OELOP Series

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and the frost-free period is about 120 to 160 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Shingle, Skyvillage and competing Penistaia soils. The Shingle and Skyvillage soils are both shallow to bedrock. DRAINAGE AND PERMEABILITY: Well drained; medium runoff, moderately slow permeability. USE AND VEGETATION: These soils are used mainly for grazing. Present vegetation is sage, blue grama, galleta and Indian ricegrass. DISTRIBUTION AND EXTENT: Northwestern New Mexico. Series is moderately extensive.

MLRA OFFICE RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Cibola County, New Mexico, 1985. REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the surface to a depth of about 3 inches. (A horizon) Argillic horizon - The zone from about 3 to 16 inches. (Btl, Bt2 horizons) Ustollic feature - organic carbon content and soil moisture regime meets the requirements for "Ustollic".

In October 2000, taxonomic classification was converted to the closest match found in Soil Taxonomy, Second Edition 1999. No update was made to horizon nomenclature, competing series section, etc. Other placements may be more appropriate after a complete update.

Official Series Description - PULPIT Series

Page 1 of 4

LOCATION PULPIT

Established Series Rev. DWJWWWWJ 0612000

PULPIT SERIES
The Pulpit series consists of moderately deep, well drained soils that formed in eolian material derived £?om sandstone. Pulpit soils are on hills and mesas. Slopes range from 2 to 12 percent. Mean annual precipitation is about 14 inches and the mean annual temperature is about 48 degrees F.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aridic Haplustalfs
TYPICAL PEDON: Pulpit loam, on a southeast facing slope, in nonirrigated cropland at an elevation of 6,680 feet. (Colors are for dry soil unless otherwise noted.) Ap--0 to 7 inches; reddish brown (5YR 514) loam, dark reddish brown (5YR 314) moist; moderate medium granular structure; soft, very friable; neutral (pH 7.2); clear smooth boundary. (3 to 8 inches thick) Btl--7 to 10 inches; reddish brown (5YR 514) loam, reddish brown (5YR 414) moist; weak medium subangular blocky structure parting to moderate fine granular; slightly hard, very friable, slightly sticky and slightly plastic; few faint clay films on faces of peds and in root channels; few fine pores; slightly alkaline (pH 7.4); clear smooth boundary. (0 to 4 inches thick) Bt2--10 to 20 inches; reddish brown (5YR 514) clay loam, reddish brown (5YR 414) moist; weak medium prismatic structure parting to moderate medium subangular blocky; slightly hard, fiiable, slightly sticky and slightly plastic; common faint clay films on faces of peds and in root channels; few tubular pores; slightly alkaline (pH 7.6); clear wavy boundary. (7 to 30 inches thick) Btk--20 to 25 inches; reddish brown (5YR 514) loam, reddish brown (5YR 414) moist; weak medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few faint clay films on faces of peds and in root channels; common medium calcium carbonate threads and soft masses; strongly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary. (3 to 8 inches thick) Bkl--25 to 30 inches; reddish brown (5YR 514) loam, reddish brown (5YR 414) moist; massive; hard, fm,slightly sticky and slightly plastic; common medium calcium carbonate threads and soft masses; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary. (0 to 29 inches thick) Bk2--30 to 36 inches; pink (7.5YR 814) fine sandy loam, pink (7.5YR 714) moist; massive; slightly hard, friable; common medium calcium carbonate threads and soft masses; violently effervescent; moderately alkaline (pH 8.2); abrupt wavy boundary. (0 to 10 inches thick)

2R--36 inches; hard calcareous sandstone.

http://ortho.ftw.nrcs.usda.gov/cgi-bin/osd~osdname.cgi?-P

Official Series Description PULPIT Series

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Page 2 of 4

TYPE LOCATION: Dolores County, Colorado.; about 6 miles northwest of Dove Creek; located in the northeast quarter of sec. 24, T. 41 N., R. 20 W.; Northdale USGS quad; lat. 37 degrees 48 minutes 21 seconds N. and long. 109 degrees 01 minutes 41 seconds E., NAD RANGE IN CHARACTERISTICS: Soil moisture regime: ustic bordering on aridic Soil temperature regime: mesic Mean annual soil temperature: 49 to 53 degrees F Mean summer soil temperature: 66 to 70 degrees F Particle-size control section: 18 to 35 percent clay Depth to lithic contact: 20 to 40 inches Depth to secondary calcium carbonate: 6 to 20 inches
A horizon: Hue: 2.5YR to 7.5YR Value: 5 to 7 and (3 to 6 moist) Chroma: 2 to 4 Texture: loam, fine sandy loam, silt loam, or sandy loam Rock merits: 0 to 10 percent gravel Calcium carbonate equivalent: 0 to 1 percent Reaction: neutral or slightly alkaline

Bt horizon: Hue: 5YR to 1O R Value: 5 to 7 and 3 to 6 (moist) Chroma: 3 to 6 Texture: clay loam, silty clay loam, loam, silt loam, or sandy clay loam Rock fragments: 0 to 10 percent gravel Calcium carbonate equivalent: 0 to 5 percent Reaction: neutral to moderately alkaline Bk horizon: Hue: 5YR to 7.5YR Value: 5 to 8 (4 to 7 moist) Chroma: 2 to 4 Texture: loam, fine sandy loam, or clay loam Rock fragments: 0 to 10 percent gravel Calcium carbonate equivalent: 5 to 10 percent Reaction: slightly or moderately alkaline COMPETING SERIES: These are the Buick, Keiser, Klinedraw, Oshoto, Roubideau, Sharps,

http://ortho.ftw.nrcs.usda.gov/cgi-bin/o.cgi?-P

6118/03

Official Series Description - PULPIT Series

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Verde, Wetherill, and W > soils. Potential competitors that do not yet have CEA class assigned are the Amal, Chita, Elpedro, and Moncha series. Amal, Buick, Chita, Elpedro, Keiser, Moncha, Oshoto, Wetherill, and Wiley soils are very deep. Klinedraw and Sharps soils are moderately deep over soft sandstone or shale. Roubideau soils lack carbonates in the lower part of the solum. Verde soils have a fi-agipan-like horizon. GEOGRAPHIC SETTING: Parent material: eolian material derived from calcareous sandstone Landform: hills and mesas Slopes: 2 to 12 percent Elevation: 6,200 to 7,800 feet Mean annual air temperature: 46 to 50 degrees F Mean annual precipitation: 13 to 16 inches Precipitation is fairly evenly distributed throughout the year with July and August being slightly wetter and June being slightly dryer. Frost-free period: 100 to 120 days GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cahona, Gladel, Wetherill, and Sh - m series. All soils are found on the same landforms. Glade1 soils are shallow over hard bedrock. DRAINAGE AND PERMEABILITY: well drained, low to high runoff, moderately slow permeability USE AND VEGETATION: These soils are used for grazing and for dry or irrigated cropland. Native vegetation is predominantly sagebrush, pinyon, juniper, western wheatgrass, and Indian ricegrass. DISTRIBUTION AND EXTENT: Southwest Colorado. LRR D, MLRA 36. This series is of moderate extent.

MLRA OFFICE RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: La Plata County Area, La Plata County, Colorado. 1982. REMARKS: Reclassified due to moisture regime change resulting from Four Corners Climate Conference 10192. Diagnostic horizons and features recognized in this pedon are: Ochric epipedon: The zone &om 0 to 7 inches. (Ap)

Official Series Description - PULPIT Series

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Argillic horizon: The zone fkom 10 to 20 inches. (Bt) Lithic contact: The zone at 36 inches. (R) Particle size control section: The zone fiom 10 to 25 inches. (Bt, Btk) Soil Taxonomy Second Edition, 1999 National Cooperative Soil Survey U.S.A.

Official Series Description - SAN-MATE0 Series

Page 1 of 3

LOCATION SAN MATE0

NM

Established Series Rev. TLP/RJA/LWWSAZ/WWJ 0412002

SAN MATEO SERIES
The San Mateo series consists of very deep, well drained, moderately slowly permeable soils that formed in alluvium, fan alluvium and stream alluvium fiom mixed sources on alluvial fans on valley sides and flood plains on valley floors. Slopes are 0 to 5 percent. Average annual temperature is about 52 degrees F. Average annual precipitation is about 11 inches. TAXONOMIC CLASS: Fine-loamy, mixed, superactive, calcareous, mesic Ustic Torrifluvents TYPICAL PEDON: San Mateo loam -- rangeland. (Colors are for dry soil unless otherwise noted.) A--0 to 2 inches; light yellowish brown (2.5Y 614) loam, olive brown (2.5Y 414) moist; moderate fine granular structure; soft, friable, nonsticb and nonplastic; common fine and very fine roots; strongly effervescent; slightly alkaline; abrupt smooth boundary. (1 to 12 inches thick) C1--2 to 12 inches; light olive brown (2.5Y 514) loam, olive brown (2.5Y 4/4) moist; massive; slightly hard, friable, nonsticky and nonplastic; common fine and very fine roots; 5 percent pebbles; strongly effervescent; slightly alkaline; clear smooth boundary. C2--12 to 29 inches; light olive brown (2.5Y 516) sandy clay loam, olive brown (2.5Y 414) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common very fine and few fine roots; common very fine irregular pores; 5 percent pebbles; strongly effervescent; slightly alkaline; gradual smooth boundary. C3--29 to 70 inches; light olive brown (2.5Y 516) sandy clay loam, olive brown (2.5Y 414) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; few very fine irregular pores; 5 percent pebbles; strongly effervescent; slightly alkaline. (Combined thickness of the C horizon is greater than 40 inches.)

TYPE LOCATION: Cibola County, New Mexico, Moquino Quadrangle; about 1 mile northwest of Moquino, New Mexico, at 35 degrees, 11 minutes and 10 seconds north latitude, and 107 degrees, 18 minutes and 2 1 seconds west longitude .
RANGE IN CHARACTERISTICS:
Soil Moisture: Intermittently moist in some part of the soil moisture control section December through March and July through October. The soil is driest during May and June. Ustic aridic moisture regime. Soil Temperature: 5 1 to 57 degrees.

Official Series Description - SAN-MATE0 Series

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Reaction: slightly to strongly alkaline. Carbonates: Calcareous throughout. Salinity: EC of 1to 8 mmhos/cm Control section: weighted average - 18 to 35 percent clay and more than 15 percent fine sand or coarser.
A horizon Hue: 1OYR or 2.5YValue: 5 or 6 dry, 3 through 5 moist Chroma: 2 to 4 dry and moist When the surface mantle has colors and organic carbon content of a mollic epipedon, it lacks the thickness requirements. Chroma: 2 through 6 Texture: sandy loam, fine sandy loam, loam, sandy clay loam, silt loam, silty clay loam, and clay loam

C horizon Hue - lOYR or 2.5Y Value: 5 or 6 dry; 3 through 5, moist Chroma: 2 through 6 Texture: Stratified sandy loam, fine sandy loam, loam, sandy clay loam, silt loam, silty clay loam, and clay loam. Sodicity: SAR of 5 to 30

COMPETING SERLES: Current competitor is the Hamburn, Haverdad, Haversid, and Manikan, series. Potential competitors that do not yet have the CEA class assigned are the Barnum, Panitchen and Suwanee series. Manikan and Suwanee soils are redder than 10YR. Hamburn and Panitchen soils have gypsum accumulations. The Bamum, Haversid, and Haverdad soils are more moist in M x and June. GEOGRAPHIC SETTING: The San Mateo soils formed in alluvium, fan alluvium and stream alluvium from mixed sources on flood plains on valley floors, and alluvial fans on valley sides. Slopes are 0 to 5 percent. Elevations range fiom 5,200 to 7,800 feet. The mean annual temperature is 49 to 54 degrees F. The average annual precipitation is 9 to 13 inches. Peak precipitation occurs in July, August, September and October. The fkost-free period is 120 to 180 days. GEOGRAPHICALLY ASSOCIATED SOILS: These are the Sparank soils. Sparank soils have more than 35 percent clay in the control section. DRAINAGE AND PERMEABILITY: Well drained, low to medium runoff, and moderately slowly permeability. USE AND VEGETATION: This series is used for rangeland. The present vegetation is alkalai sacaton, western wheatgrass, blue gram, fourwing saltbush, and galleta. DISTRIBUTION AND EXTENT: Northwestern New Mexico, Arizona and Utah. MLRA 36, LRR-

Official Series Description - SAN-MATE0 Series

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D. This series is of large extent.

MLRA OFFICE RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Cibola County, New Mexico, 1956.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: the zone from 0 to 2 inches. ( A horizon) Fluventic feature - An irregular decrease in organic carbon due to stratification. Classified according to Soil Taxonomy Second Edition, 1999. National Cooperative Soil Survey U.S.A.

Official Series Description - SHARPS Series

Page 1 of 4

LOCATION SHARPS

Established Series Rev. DKRIJWWWWJ 0612000

SHARPS SERIES
The Sharps series consists of moderately deep, well drained soils that formed in eolian material derived from sandstone overlaying shale. Sharps soils are on mesas, ridges, and hills. Slopes range fiom 2 to 12 percent. Mean annual precipitation is about 14 inches and the mean annual temperature is about 48 degrees F. TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Aridic Haplustalfs TYPICAL PEDON: Sharps loam, in a cultivated field. (Colors are for dry soil unless otherwise noted.) Ap--0 to 6 inches; light reddish brown (5YR 614) loam, reddish brown (5YR 414) moist; moderate medium granular structure; slightly hard, very £iiable, slightly sticky and slightly plastic; neutral; clear smooth boundary. (4 to 8 inches thick) BA--6 to 9 inches; light reddish brown (5YR 614) loam, reddish brown (5YR 414) moist; weak medium subangular blocky structure parting to moderate medium granular; slightly hard, very friable, slightly sticky and slightly plastic; few faint clay films in root channels; slightly alkaline; clear smooth boundary. (0 to 6 inches thick) Bt--9 to 19 inches; reddish brown (5YR 514) clay loam, reddish brown (5YR 414) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable, slightly sticky and slightly plastic; common faint clay films on faces of peds and in root channels; slightly alkaline; clear wavy boundary. (4 to 32 inches thick) Bkl--19 to 25 inches; light reddish brown (5YR 614) loam, reddish brown (5YR 514) moist; weak medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few faint clay films on faces of peds and in root channels; common calcium carbonate threads and soft masses; strongly effervescent; moderately alkaline; gradual wavy boundary. (4 to 8 inches thick) Bk2--25 to 30 inches; pink (5YR 814) loam, pink (5YR 7/4) moist; massive; hard, friable, slightly sticky and slightly plastic; many soft masses of calcium carbonate; strongly effervescent; moderately alkaline; gradual wavy boundary. (0 to 28 inches thick) 2Cr--30 inches; shale and soft sandstone. TYPE LOCATION: Dolores County, Colorado; about 6 miles northwest of Dove Creek; located in the northwest quarter of sec. 18, T. 41 N., R. 19 W.; Northdale USGS quad; lat. 39 degrees 49 minutes 19 seconds N. and long. 109 degrees 00 minutes 46 seconds E., NAD27

Official Series Description - SHARPS Series

Page 2 of 4

RANGE IN CHARACTERISTICS: Soil moisture regime: ustic bordering on aridic Soil temperature regime: mesic Mean annual soil temperature: 49 to 52 degrees F Mean summer soil temperature: 58 to 64 degrees F Rock fiagments: 0 to 15 percent gravel Particle-size control section: 18 to 35 percent clay with 15 to 70 percent sand, most being very fine sand Depth to paralithic contact: 20 to 40 inches to soft shale or sandstone Depth to secondary calcium carbonate: 10 to 36 inches
A horizon: Hue: 5YR to 1OYR Value: 5 to 7 and 3 to 6 moist Chroma: 2 to 6 Texture: loam, silt loam, or fine sandy loam Rock fiagments: 0 to 20 percent gravel Calcium carbonate equivalent: 0 to 1 percent Reaction: neutral or slightly alkaline

Bt horizon: Hue: 5YR or 7.5YR Value: 5 to 7 (3 to 6 moist) Chroma: 3 to 6 Texture: loam, silty clay loam, or clay loam Rock fragments: 0 to 15 percent gravel Calcium carbonate equivalent: 5 to 10 percent Reaction: Neutral to moderately alkaline Bk horizon: Hue: 5YR to 1O Y R Value: 4 to 8 (4 to 7 moist) Chroma: 4 to 8 (moist) Texture: loam, silty clay loam, or clay loam Rock fragments: 0 to 15 percent gravel Calcium carbonate equivalent: 10 to 15 percent Reaction: moderately alkaline or strongly alkaline

COMPETING SERIES: These are the Buick, Keiser, Klinedraw, Oshoto. Pulpit, Roubideau, Verde, Wetherill, and Wiley series. Potential competitors that do not yet have CEA class assigned are the

Official Series Description - SHARPS Series

Page 3 of 4

Arnal, Chita, Elpedro, and Moncha soils. Amal, Buick, Chita, Elpedro, Keiser, Moncha, Oshoto, Wetherill, and Wiley soils are very deep. Klinedraw soils have hue of 10YR or 2.5Y. Pulpit, Roubideau, and Verde soils are moderately deep over hard sandstone. In addition, Roubideau soils lack carbonates in the lower part of the solurn, A d Verde soils have a fragipan-like horizon. GEOGRAPHIC SETTING: Parent material: eolian material derived &om sandstone and shale. Landform: mesas, ridges, and hills Slopes: 2 to 12 percent Elevation: 6,200 to 7,400 feet Mean annual temperature: 46 to 50 degrees F Mean annual precipitation: 13 to 16 inches Precipitation is fairly evenly distributed throughout the year with July and August being slightly wetter and June being slightly dryer. Frost-fiee period: 100 to 120 days GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cahona, Pulpit, and Wetherill series. All these soils are on the s.me landscape position as Sharps. Cahona soils have a calcic horizon. Wetherill soils are very deep. DRAINAGE AND PERMEABILITY: well drained, low to high runoff, moderate and moderately slow permeability USE AND VEGETATION: Sharps soils are used for grazing or as irrigated or dry cropland. Native vegetation is mainly sagebrush, cactus, pinyon, juniper, western wheatgrass, and Indian ricegrass. DISTRIBUTION AND EXTENT: Southwest Colorado and New Mexico. LRR D, MLRA 35,36 and 39. This series is of moderate extent.

MLRA OFFICE RESPONSIBLE: Phoenix, Arizona.
SERIES ESTABLISHED: Lincoln County, NM. 1981. REMARKS: Classification changed due to the change in moisture regime due to the Four Comers Climate Conference of 10192. Diagnostic horizons and features recognized in this pedon are: Ochric epipedon: The zone fiom 0 to 6 inches. (Ap) Argillic horizon: The zone fiom 9 to 19 inches. (Bt) Particle size control section: The zone fiom 9 to 19 inches. (Bt) http://ortho.ftw.nrcs.usda.gov/cgi-bin/osd/osdname.cgi?-P

Official Series Description - SHARPS Series

Page 4 of 4

Soil Taxonomy Second Edition, 1999
-.

--

---

-

- --

- --

-

-

-

-

National Cooperative Soil Survey U.S .A.

Official Series Description - TRAVESSILLA Series

Page 1 of 3

LOCATION TRAVESSILLA

Established Series Rev. VGL-AJC-RJA-ACT 05/2002

TRAVESSILLA SERIES
The Travessilla series consists of very shallow and shallow, well drained soils that formed in calcareous eolian sediments and material weathered from sandstone. These soils are on hills, cuestas, scarps, and mesas with slopes ranging from 0 to 75 percent. Mean annual precipitation is about 11 inches. The mean annual temperature is above 53 degrees F. TAXONOMIC CLASS: Loamy, mixed, superactive, calcareous, mesic Lithic Ustic Torriorthents TYPICAL PEDON: Travessilla stony sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.) A--0 to 4 inches; light brownish gray (10YR 6/2) stony sandy loam, dark grayish brown (1OYR 412) moist; weak fine granular structure; slightly hard, very fiiable, slightly sticky and slightly plastic; many fine and medium roots; common fine pores; 15 percent stones; slightly effervescent; slightly alkaline; clear smooth boundary. (2 to 6 inches thick) C--4 to 8 inches; pale brown (1OYR 613) channery loam, brown (10YR 413) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; common fine and medium roots; common fine pores; 20 percent charmers; slightly effervescent; moderately alkaline; abrupt smooth boundary. (2 to 14 inches thick) R--8 inches; hard sandstone with some fractures.

TYPE LOCATION: Union County, New Mexico; approximately 1,560 feet north and 4,200 feet west of the southeast corner, sec. 24, T. 3 1 N., R. 36 E.
RANGE IN CHARACTERISTICS:
Soil Moisture - Typically, moist intermittently fkom April 30 through October in some part of the soil moisture control section and dry in all parts periodically fiom November 1 to April 30. Soil Temperature - 50 to 58 degrees F. Depth to lithic contact: typically 4 to 10 inches but ranges to 20 inches. Particle-size Control Section: Clay Content: 5 to 18 percent. Silt Content: 5 to 50 percent. Sand Content: 40 to 90 percent with more than 25 percent fine sand or coarser. Rock fragment content: 0 to 10 percent stones, 0 to 10 percent cobbles and 0 to 25 percent pebbles

Official Series Description - TRAVESSILLA Series

Page 2 of 3

but weighted average is less than 35 percent. A and C horizons - (an AC horizon is present in some pedons) Hue: 7.5YR to 2.5Y Value: 5 to 7 dry, 3 to 5 moist Chroma: 2 to 4 Texture of the Fine Earth Fraction: sandy loam, fine sandy loam, loam or very fine sandy loam. Rock fragment content: 0 to 35 percent Reaction: slightly alkaline or moderately alkaline. COMPETING SERIES: These are the Hideout (UT), Kenzo (T UT), Lazear (CO), Redspear (WY), Rizno (UT), Rizozo (NM), Simel (UT), Skyvillage (NM), Tesihim (AZ), Travson (WY), and Zukan (UT) series. Hideout soils: have a mean annual temperature of 47 to 50 degrees F. Kenzo soils: have hue of 7.5YR or redder. Lazear soils: have more than 18 percent clay. Redspear, Rizno and Rizozo soils: have hue of 5YR or redder. Simel soils: average 27 to 35 percent clay. Skyvillage soils: are dry in all parts of the soil moisture control section periodically from & 1 to June 30. Tesihim soils: are derived from soft volcanic tuff. Travson soils: are dry in the soil moisture control section July through September. Zuchan soils: have accumulated carbonates in the form of a Bk horizon. GEOGRAPHIC SETTING: Parent material: calcareous eolian sediments and residuum weathered fiom sandstone and shale. Outcrops of sandstone with a minor amount of shale are common on steep slopes. Landform: hills, cuestas, scarps, and mesas Slopes: 0 to 75 percent. Elevation: 4,700 to 8,000 feet. Mean annual precipitation: 10 to 16 inches, but has ranged higher. Mean annual temperature: 50 to 57 degrees F. Frost-fiee period is typically 115 to 170 days. Utah has a frost-free period as low as 70 days. GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bernal, Carnero, Hagerman, Quay and Pa-iarito soils. Bernal and Hagerman soils: have an argillic horizon. Carnero soils: have bedrock at depths of 20 to 40 inches. Quay and Pajarito soils: do not have bedrock within a depth of 40 inches. Quay soils have more than 18 percent clay in the particle size control section and have a prominent zone of lime accumulation DRAINAGE AND PERMEABILITY: Well drained; runoff is high on slopes less than 1 percent and very high on slopes greater than 1 percent; moderate or moderately rapid permeability. USE AND VEGETATION: Rangeland. Juniper, pinyon, squawbush, oakbrush, blue grama, sideoats grama and snakeweed are the principal plants. DISTRIBUTION AND EXTENT: Northern New Mexico, Arizona, Colorado, Montana, western

Official Series Description - TRAVESSILLA Series

Page 3 of 3

Oklahoma, Utah and Wyoming. LRR E, G; MLRA'S 49,67,69,70,77. The series is extensive.

MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Eastern New Mexico Reconnaissance, Harding County, New Mexico, 1937.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric Epipedon - 0 to 4 inches. (A horizon). Lithic Contact - 8 inches. (R horizon). Particle-size Control Section - The zone f!rom the surface of the soil to about 8 inches: (A, C horizons). Additional data: None Taxonomic Version: Second Edition, 1999

Official Series Description - ZYME Series

Page 1 of 4

LOCATION ZYME

CO+UT+AZ

Established Series Rev. JPP/JWWDKR/SAZ/WWJ 0912001

ZYME SERIES
The Zyme series consists of shallow or very shallow, well drained soils that formed in residuum derived from shale. Zyme soils are on ridges, knobs, and hills. Slopes range fiom 3 to 80 percent. The mean annual precipitation is about 13 inches and the mean annual temperature is about 46 degrees F. TAXONOMIC CLASS: Clayey, smectitic, calcareous, mesic, shallow Ustic Torriorthents TYPICAL PEDON: Zyme clay loam, on a southeast facing, simple, 30 percent slope in pinyon and juniper woodland at an elevation of 6760 feet. (Colors are for dry soil unless otherwise noted.) When described on 7/12/79 the soil was dry fiom 0 to 10 inches. A1--0 to 1 inch; grayish brown (10YR 512) clay loam, dark grayish brown (10YR 412) moist; medium fine granular structure; loose, fiiable, sticky and plastic; violently effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (0 to 2 inches thick) A2--1 to 4 inches; grayish brown (1OYR 512) clay loam, dark grayish brown (1OYR 412) moist; i m sticky and plastic; violently effervescent; moderately alkaline (pH 8.2); massive; very hard, f r , clear smooth boundary. (2 to 5 inches thick) C--4 to 10 inches; grayish brown (10YR 512) clay loam, dark grayish brown (10YR 412) moist; massive; hard, firm, sticky and plastic; 10 percent shale chips; violently effervescent; moderately alkaline (pH 8.2); clear smooth boundary. (4 to 14 inches thick) Cr-- 10 to 14 inches; gray platy calcareous shale. TYPE LOCATION: La Plata County, Colorado; west of the cemetery on the west side of Durango; located about 2,700 feet west and 300 feet north of the southeast corner of Sec. 19, T. 35 N., R. 9 W.; Durango West USGS quad; lat. 37 degrees 16 minutes 40 seconds N. and long. 107 degrees 53 minutes 34 seconds W., NAD 27

RANGE IN CHARACTERISTICS:
Soil moisture regime: Ustic-aridic. The soil moisture control section is dry for 15 consecutive days fiom May 15 to July 15 when the soil temperature at 20 inches is greater than 41 degrees F. It is not dry in all parts of the moisture control section for at least 45 consecutive days following the summer solstice to October 20 and for at least 90 cumulative days during that period. Soil temperature regime: mesic

Official Series Description - ZYME Series

Page 2 of 4

Mean annual soil temperature: 47 to 55 degrees F Mean annual summer soil temperature: 59 to 68 degrees F Particle-size control section: 35 to 45 percent clay, 20 to 60 percent silt, 5 to 45 percent sand, 0 to 15 percent rock fragments Depth to paralithic contact: 6 to 20 inches to shale Depth to secondary calcium carbonate: 0 to 3 inches
A horizon: Hue: 5Y to lOYR Value: 4 or 6 dry, 3 to 5 moist Chroma: 2 to 6 Texture: clay loam or silty clay loam Rock fragments: 0 to 60 percent, mostly gravel and channers Calcium carbonate equivalent: 0 to 5 percent Reaction: slightly or moderately alkaline

C horizon: Hue: 5Y to 1OYR Value: 4 to 7 dry, 3 or 5 moist Chroma: 2 to 4 Texture: clay, clay loam, silty clay, or silty clay loam Rock fragments: 0 to 15 percent Calcium carbonate equivalent: 1 to 10 percent Reaction: slightly or moderately alkaline Cr horizon: shale bedrock Some pedons have accumulations of gypsum

COMPETING SERIES: These are the Cannonville, Danko, Midway, Orella, and Samday, series. Cannonville soils are dry in all parts of the moisture control section 65 to 75 percent of the time when the temperature at 20 inches is greater than 41 degrees F. Danko soils have hue redder than 10YR and more than 15 percent exchangeable sodium. Epsie soils contain 50 to 60 percent clay in the C horizon. Midway soils are dry less than 15 consecutive days in all parts of the moisture control section between 15 to July 15. Orella soils are strongly alkaline and sodic. Samday soils have consistent gypsum accumulations in the C horizon. GEOGRAPHIC SETTJNG:
Parent material: residuum derived from shale Landform: ridges, knobs, and hills Slopes: 3 to 80 percent

http://ortho.ftw.nrcs.usda.gov/cgi-bin/osd/osdname.cgi?-P

Official Series Description - ZYME Series

Page 3 of 4

Elevation: 5,000 to 8,100 feet Mean annual air temperature: 45 to 53 degrees F Mean annual precipitation: 10 to 16 inches Wettest months: except for May and June, monthly precipitation is about the same. About half the precipitation falls between April and September. Driest months: May and June receive the least precipitation. Frost-free period: 90 to 135 days

PE Index: 30 to 50 for the series
GEOGRAPHICALLY ASSOCIATED SOILS: These are Arboles, Bayfield, Bodot, and Arboles and soils.

a soils are very deep and have cambic horizons. i

Bavfield soils are very deep. Bodot soils are moderately deep to bedrock. DRAINAGE AND PERMEABILITY: Well drained, high or very high runoff, slow permeability USE AND VEGETATION: These soils are used for livestock grazing, wildlife habitat, and homesite development. Native vegetation is pinyon pine, Utah juniper, big sagebrush, Indian ricegrass, western wheatgrass, mountainmahogany, Gambel oak, serviceberry, and bitterbrush. DISTRIBUTION AND EXTENT: Western Colorado and similar areas in Arizona and Utah. LRR D, MLRA 39,35,34B. This series is of large extent.

MLRA OFFICE RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: La Plata County Area, Colorado, 1982.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone fiom 0 to 4 inches. (A1 and A2 horizons) Paralithic feature: Shale bedrock at 10 inches. Particle size control section: The zone from 0 to 10 inches. (Al, A2,C) Classified according to Soil Taxonomy Second Edition, 1999. National Cooperative Soil Survey

http://ortho.ftw.nrcs.usda.gov/cgi-binlosd~osdname.cgi?-P

Official Series Description - ZYME Series

Page 4 of 4

U.S.A.

ATTACHMENT 4 Black Mesa Mine: J9 Coal Resource Area Soil Laboratory Data

d
August 24,2000

1nter.Mountain laboratories, lnc.
2506 West Main Street. Farmingfon, NM 87401

Mr. Gary Wendt Peabody Western Coal Co. PO Box 650 Navajo Route 41 Kayenta, Arizona 86033

Dear Mr. Wendt: Enclosed are the results of the analyses performed on the soil samples received by IML on August 4,2000. The samples were from Black Mesa Mine and correspond to IML lab numbers 0300S03226 - 29. The 1999 PWCC QC Split Analytical Suite was requested for each sample.

If you have any questions or comments, please feel free to contact me at 1-800-828-1409.

Sincerely,

Eric J Jaquez Soil Lab Supervisor IML-Farmington

enclosure: analytical report

Inter*mountain Lciborcitorles, lnc.
2506 West Main Street
Farmington, New Mexico 87401

Tel. (505) 326-4737

Peabody Western Coal Company
Client Project ID: Black Mesa Mine Kayenta, AZ Date Received: 08/04/00 Lab Id Sample Id
J9-I8

Page 1 of 6

. J-19
Depths
Inch 76 108 PH
EC mmnoslcm 3.06 meq/C-13 meqR 8.7
I

IML Project #0300803226 Report Date: 08/24/00
SAR
Sand
Silt
-.

Ca

Mg
Na
13

Ca ly
4.0

Texture

0300803226

/9p

/
'80-108
42

7.3

s.u.

meqR------

"

-- -

-

81

8

11

SL

0300503229
JQ-26
#"c,/

7.1
8.34

23

32

5.6

69

11

20

SCL

Inter*mount~lnLcrboratorles, lnc.
2506 West Main Street
Farmington, New Mexico 87401

Tel. (505) 326-4737

Peabody Western Coal Company
Client Project ID: Black Mesa Mine Date Received: 08/04/00 Kayenta, AZ

Page 2 of 6

IML Project #0300S03226

J-19
Depths
Inch 76- 108
0.9
34.6 33.6

Report Date: 08/24/00

Lab Id
Sample Id

--

0300803226

J9-18

Total 8 % 0.03

Acid Base T of u r

Neutral. Potential

ABP Total Sulfur

tlKtVl(tVrcr

-

-- - -- - - - -

-- -- - - -- - --

-

.

--

--

- -

Inter*mountain laboratoiles, Inc.
2506 West Main Street
Farmington, New Mexico 87401

Tel. (505) 326-4737

Peabody Western Coal Company
Client Project ID: Black Mesa Mine Kayenta, AZ Date Received: 08104100 Lab Id Sample Id Depths
Selenium TO~I Selenium Soluble

Page 3 of 6

IML Project #0300803226

$19

Report Date: 08/24/00

Inter*mountcrin Lcrborcrtorles, lnc.
2506 West Main Street
Farmington, New Mexico 87401

Tel. (505) 326-4737

Client Project ID: Black Mesa Mine Date Received: 08/04/00 Lab Id
.- .s .,
rn mQcm- n me-q
8.34 8.41 42 42 23 23 7.1 7.1 0300S03229 59-26 0300S03229D J9-26 80-108 80-108 32 32

Peabody Western Coal Company Kayenta, At
J-19
PH EC Ca

Page 4 of 6

IML Project #0300303226
Silt
Sand

Report Date: 08/24/00
S AR Clay

Sample Id

Depths

Mg
Na

Texture

c r m q - eeq m n 6 nnm- Ir---5.6 5.6

--

O F - -

- -%'

%
69 69 11 11 20 20

-- -

SCL

SCL

APPENDIX B

INDEX

Appendix B presents the lithologic, chemical and physical descriptions of the overburden in the coal resource areas for the life-of-mine plans. The locations of the deep, shallow

and highwall cores used to characterize the overburden are shown on Drawings 85613 and 85613A.

eage
Lithologic Symbols and Descriptors 5-7 Mining Area (Deep Cores) J-16 Mining Area (Deep Cores) J-19 and J-21 Mining Areas (Deep Cores) J-19 and 5-21 Mining Areas (Shallow Cores) J-21 Mining Area (Highwall Cores) N-6 Mining Area (Deep Cores) N-10 Mining Area (Deep Cores) N-10 Mining Area (Shallow Cores)
!

1

N-11 Mining Area (Deep Cores) N-14 Mining Area (Deep Cores) J-28 Mining Area (Deep Cores) 2003 Drilling Areas (Deep Cores) Lithologic Symbols and Descriptors (2003 Drilling) 5-2 Mining Area J-4 Mining Area J-6 Mining Area J-9 Mining Area J-14 Mining Area 5-15 Mining Area
J-23 Mining Area

N-9 Mining Area N-10 Mining Area N-99 Mining Area

Revised 11/21/03

J-28 MINING AREA (DEEP CORES)

:ATION

'

DATE DRILLED SA'rUHATION % (MOISTURE) -

' 1 L8/ 61
SAR (ASH SOL.Na.
,

SUB A R E A
SOL -. C a . SOL.Mg
,

J -LU

HOLE # 23155C.
:VATION

SAMPLE - NO -

(BTU)

-.

Revise

- 8
w

d

p d

o

d

y

g ? ? l
N N N

4 g Y 9 r . 9 ? ?
N N O ~

m
~ P
.l -

N

r n N r n d r l N N . 4

~

N

d

m

O

~

519

Revised 11/21/03

-

I-U

\O (F

m z

MI ne: Xayenta Core: 23155-C Date Cored:
-

. .
Central Laboratory nTonr o f Cat03 Equivalrst p a r l o 0 0 Tons h t t r l a l * D r y Bar l s Max. Rcq From To ta l Sulfur Excess
h a

P a r t i c l e Slze lrganlc Ha t t c r 5.2
2.1

% Mol s t u r e

l a b No. /sulfur 1 2 3 0.07 4 '0.06 0.08 4.06

I
5 6 '0.06 '0.06
40-06 '0.06

1
I
,

I

t

"

7
Sand 26.7 29.0 4.5 2.1 3.9 10.2 9.1 14.3 3.5 3.8 2.2 19.5 72.4 49.5 39.7 25.5 37.2 49.5 11.2 73.2

%
Clay 29.8 32.9 39.5 12.4 34.1 43.7 54.4 42.8 38.5 38.6 8.5

1 / 3 OAR

15 BAR

30.1 34.5 35.6 21.5 37.8 42.4 48.4 47.2

16.9

14.4

z---

Aval l a b l a H2O H o l d . Capacl l y ( I / ] - I 5 BAR)

C
41.9 15.1 37.6 48.8

20.1

16.5

19.1

8.0

13.5

7

I

'0.06

19.0

18.8

26.9

15.5

26.3

22.1

-9 10 11 12 13 14 15
16

8

23.8

23.4

/ ::::
/
'0.06

I

33.3

16.4

16.9

18.5 '0.06

23.4

20.8

7.3

13.5

39.8 4.2 4.0 1.5 4.1 3.9 41.8 39.6 62.3 34.7 14.8 41.3 47.6 16.5 29 .O 35.1

21.1

18.7

43.1

26.5

16.6

41.6

23.0

18.6

21.2

8.8

12.4

--'

31.1

16.1

15.0

17

38.7

20.4

18.3

I '

4.n

Z1.C
.

'77

l

:?
i

I .

... -

.

.. .

ne:
Kayenta
Cure: 23155-c 9 a t e Cored:

Townrhl p: 3 6 ~ Range: lge S e c t l o n : 35 *Tons o f Cat03 E q u l v s l e n t par 1030 Tons n a t e r l s l h o u nt Needed for

\ rl rl

N

rl

z
P s r t l c l s Slze

2 no1 s t u r e
ft
Sand

--

Req From

Lab Yo.

NeutralI ty

6 % Excess CsCo3 . Organic Equlv. H a t t e r

%
Sllt

t
Clay

-19
20
21 22

DATE D R I L L E D

5/19/81

S U B AREA

20.8 .10.5 24.6

2.4 1.2

0 .j4

28.9

2.1

23.8

0.4

24.6

2.3

28.8

0.4

-.

12,864 Revised

15.3

1.1

'.E NO.

23329C

DRILLER DATE DRILLED

G . Hopkins

219(181
SAR (ASH

S U B AREA 5-28
SOL. N a

SATURATION % SAMPLE - NO -

.

SOL. Ca

.

SOL. M g

(MOISTURE)

Revised

-

- --

- --.. - .

Mine8 Corer
Kaymta 23329-C Data

I

S e c t i o n : 35

Townstiip~ 36N Range: 19E C o r e d : 5/19/81
c e n t r a l Laboratory

P!.itl:, IIY C0I:L COMPANY

-

-

-

Depth

'?hlcknera Ft.

NO.
,23 24 25 26
'

Lab
Sat, 8
'

Tonduc tivityPaste
1.1
72.5 63.4 35.0 41.7 57.9 69.1 1.9 2.9 1.7 3.2 3.3 2.7 2.9 59.3 37.9 70.1 32.2 36.1 68.0 37.0 3.7 4.8 5.2 5.9 2.1

-

-

Saturation Extract

3.4
8.2 8.6 6.6 6.8 8.5 9.6 11.6 8.5 30.6 23.2 43.2 20.0 4.1 8.5

NaHCO

ESP SAR - - ppm

P

3

11.2
8.4 7.6 9.8 10.8 15.3 9.0 34.6 27.1 33.4 22.0

Nl1 OACl

i

N

ppm ppm

Surface n o i l Surface s o i l Sands tone 27 sMle/Silty s$ale 28 29 30 31 32 Sandstone 33 34 35 36 Shale Sandstone Shale Coal s & l e / ~ i l t y shale Sandstone Shale

7.9

400.4

33

7.3

213.5

44

7.2

106.7

24

7.1

102.8

19

7.2

107.0

17

7.9

250.1

23

8.2

213.9

33

7.9

163.2

34

8.7

609.9

53

8.2

210.3

49

7.4

208.4

154

7.5 3.1 72.9 51.2 36.5

816.9

43

7.7

227.4

166

--

7.5 72.1 15.8 18.2

1103.2

94

-38 39 40

37

2.1 2.6 3.2 1.8 41 3.0

8.7 16.2 69.3
68.2

637.5

179

13.4 33.1 22.7 37.1 12.4 9.2

8.2

460.0 29.8 16.1 11.9

91

7.7

597.7

37 .

'

8.3

324.5

15

sGty s a n d s t o n e
\

7.0

140.2

72

--

-

-

. V O f

- -

LO, n n .. ..

r Pm ? r n m r
w o w w

r w
w

r r r r !r - r r r rm rm rw r mr wr m r 4 z X m m w w n ~ w m
m m w w m w w m w w m w w w
- 0

v

-

-,

-9

W 4

e

w

.

N

e w

N P

P

P
. e

W N W . " .WJ P ? N' PPY . NW 'O! " P P N . m N. "N! -W ? . V I

z.
r0 m

w

u

w

m

r

o

m

u

l

r

w

~

e

~

-

526

Revised 11/21/03

A

1

LED

5/25/81
. .

SUB ARTA J-28
.

DRILLER

G. Hopkins
SAR

SATUPJTION %

SOL. IJa. S O L . C a .
,

SOL.Cl9
,

11I +

(BTU)

as

1

1

,

PI{

levi sed

Revised 11/21/03

- .

Revised 11/21/03

0"

" - 3

D 0

2

n n n

N N W

n
h N
W

d

N
N

I
o

I

N
a ,

0
1) 1

y . " p
0 U ) W Q

I

p'"."!-'p
N

P . -

m
W

a

530

Revised 11/21/03

DATE DRI LLED

6/2/81
SAR
SOL.

SUi3 A R m

J-28

SATURnTION B

5.3

Revi se

4.4

1

L

A

G . Hopkins 6/2/81
SUB AREA

DATE D R I L L E D

Jr28

SAMPLE NO.,
1

SATURATION % (IrlOISTURE)

. - ... -..

-

M l rlc a Kayent. Core a 23131-C Section: 27

Township; 36N Ranyet 1 9 ~ ~ Date Cored; 6/2/01

PEABODY COAL CO!4Pk!JY

-No. .
\ Silty shale 51 1.5 2.6 3.9 8.7 * 7.2 4.9 2.3 3.5 2.6 2.8 5.8 4.4 63
'

Lab
49.9 48.5 73.2 . 51.7 36.4 69.3 75.0
,

Conduc t l v i tyv Sat, Paste t

c e n t r a l Laboratory Saturation

-ESP SAR -1.6 5.1 2.4 0.9 0.7 0.8 15.5 1.2 6.4 2.2 0.1 0.1 0.1 18.3

Nal!CO

ppm

P

3

r

NH

ppm

rt

OACI

7.8

341.4

Siltstone 52 53 54 55 Sh& 56 Coal Shale 57 58 59 60 61 62 64 65 66 67 68 Sandstone Sandatone Sandstone Sands t o n e Shale Shale Snale
W

7.5

308.5

Shale

5.5

422.3

4.4

149.1

5: 5

173.4

--

5.9

418.7

7.6 38.0 35.7 34.9 37.3 75.9 3.5 2.6 9.1 2.8 1.9 3.6 65.0 76.0 35.2 34.5 72.4 69.5 27.2 15.7 15.9 7.8 7.0 6.9 5.6 5.9 23.4 16.6 12.4 29.5 19.1 17.3 10.5 7.2 7.8 5.8 6.8 26.4 20.3 16.3

677.7

7.0

122.4

7.4

301.0

7.8

296.9

8.5

101.4

9.0

321.0

9.1

308.8

9.1

296.8

8.6

97.1

6.1

103.3

8.0

740.3

-69 -?Drv Basis 1 ' Total-N is Sum of NH,,-N * * ' " I

8.6 1.2 74.0 4.2 4.5

351.3

8.6

533.4

- Wlppm

and NOl

-

and NO -N 3
h.blppl

..

--

Townsllipr 5bN Range; 19e Date Cored1 6/2/81

i'l'l\bOfrY COAL COI.:I*AIJY

Central Laboratory
Lab Sat,
1 71.5 34.5
59.5 1.2

Ll thology

Depth Ft.

Shale

I
Thickneee

Pt.
70

NO. -

Conduc tivityo Paste
1.6 1.1

-

-

Saturation Extract
- m

ShR

I
a

ESP

N I ? ppm ppm

NIi OACa

678.3

38

71
Silty s h a h

148.3

21

72

157.8

35

C

r L A u uv I c U ~ - L' ~ ' L m r i I r r 7 - - . - Centra l Laboratory

: Kaycnta :ore: 23331-c h t c Cored: 6/2/01
-

Township: 36N Rangal 19E

Section: 27
*Tons o f Cat03 E q u l r a l e n t par

180 Tons h t e r l r r l
Max. Req From Total Sulfur

- -

Present BY Excess ca Co3 Equlv.
0'. 39

I tratlon
22.88
2.20

h o u nt leeded for leutralIty

rganlc

*

t
na t tcr
2.5
2.2

t Sand

7
Clay

1 3 BAR 1
42.6
3.0

15 BAR

1.88 1.88 1.88
\

2.27 24.76 4.08

24.4 11 .
3. 69

7.4

16.1

I

DATE D R I L L ~ D

6/.7/ 8 1
'

OLE '# 23332C
V A T 1 ON

SAMPLE NO.

DRILLER

G. Houkins
SAR

.

SUB A R M

5-28

'
..

1

SATURATION % (MOIS'rURE)

2.2

Revi sec 0.3

SATURATION
:VATIqN
t

$

-

SAMPLE NC

Revi E

MLner

Corc: 23332-C Section; 26 Central Laboratory Depth
Ft.
Ft. 73'
a

Kaycntr

I.EIILu- r
c b

..:... .. .,
.i
t...

r

Thickness NO. -.
Paste
b

Lab
Sat,
65.3 65.6 68.5 36.8 41.5 43.3 32.5 34.0 68.2 37.7 72.3 63.3
.

Zonduc tivlty.
b

- -

-

Saturation Extract

ESP 1.4 .2.3 34 .

NallC03

N H OAc.

P

ppm

N 8; ppm ppm
79 . 71 .

0.0 Cuttingr-Shale Cuttinga-Shale Cuttings-Sandstone 10.0 13.0 17.0 Sandstone Coal Shale/Si ltstone Sandstone
Coa l/Shals

211.1

11

2.5 50 . 70 . 77 78 79 80 76 75

74

7.2 4.0 3.6 52 . 2.6 18 . 14.0 10.8 6.4 38.1 73 .

302.8

13

.

240.6

12

71.7

15

7.1

78.0

12

70 .

93.1

12

69 .

47.4

13

25.9 34.8 42.0 81 82 83 50.6 60.5 66.8 72.&1 77.0
'

--

51 .

77.4

. 4

80 .

242.5

75 .

95.5

Coa 1 Shale Coa 1 Silty sandstone 86.3 91.1 9: 5 5 99.8 105.9 Coag CarQnaceous
W
\

-84

88 .

301.4

7.5

699.2

--

80.7

85 86 87 88

42.1 59.1 54.4 47.8

20.6 18.7 75 . 26.8

7.7

154.3

74 .

466.0

84 .

226.9

--

77 . 72.6 89 3.0

539.0

114.2 shale 115.2

-90

9.0 25.5 10.6

205.8 .

7.8

499.0

540

Revised 11/21/03

q ? w ~ ~ y I - U - I O N I - N m N
d N N d r l d r l

. . .
d

m mm ~ ~ r N O N N A N

. . .

l m O I
rl

w

o

m

w

G 0N' gd. nA' A

9
a
d

: 3 4 " ? ? : 5 ?
~ V r P - a o m P N N N

m N

d N

o

Y ? 9
m m w - a d 9

?
r0

v N

3 9 ? Y

n m W m N

m

"
r)

-. .
--

? r ! ? ? y P ; ? y .
~
9 n

- I - -

m

v

~

w

4

m

r l d

m

m

rm l o m v r l v

...

I N

n 9 I -

9

N m

. .
m m

m m

. ? O
m

9 N
9

W

Y U X

--

I - r n r n r ( I n V . O O O O O O

.

S S
O

N

N

S Y 1
N m

?
V

r . ? q w N m m m

n
N

r d :

,-

U : S ' U Y

0 -

e, -:

m ' m m m m m m m m m ~ m m m m

d - i r l d r ( . - I r l r l

. . . . . . . .

m

m m a m d A

. . .
m m A

m m
rl

m m w o m 4 i D . :
4 8

. . . .

.I -

?

m

"!
( 5

n

10 3 ;
r,

- .-.. c r

C

Q " rl

01 N Q

\O

uC

0
U

0 9 U kern

Z

rn-.

C e n t r a l Lsbora t o r y

I
Kaysnta 'Mine: !tot K: 23332-c ? a r e Cored: 6/7/81
i
*

Township: 3(34 Range: 1 9 ~ Sect Ion:
hTonc o f CaCo3 E q u i v a l e n t por 1000 Tons M a t e r l a l imoun t '{ceded

Hsx ,
Req From Totr l Sulfur
Neutral-

for

I ty

Excess Ca c o j Equlv.

rganlc Ya t t c r

*t

Particle

Slzc

7 Sand
3.7 22.7

1.88 1.88

0.39
3.63

0.4

46.1

I

DA'rE DR 1LLED

6/15/81

SUi3 ART&

DRILLER

G. Hopkins

-

5-28

". 1

I UUIA,,

'

HODKlnS

DATE D R I L L E D

6/15/81
SAR

SUB AREA

Jv28

-

]OLE # 23333C
XATJQN
-

do-

i

SAMPLE - NC -

SATURATION % ( -M O I S T U R E )

Revise

N
rl
CI

. . .
P M

N r n N r ) N d N M

. . . .

N r n r l r l

v.

O

r l N

545

Revised 11/21/03

.

Centra l Laboratory

.-. .- .---.--. .. . . .
..

- - --

m

\

0

rl

\ rl rl

N

rTon, o f taco3 Equivalent p a r

2
lrganlc Matter

lo30 Tons ' a t r r l a l
Amount MIX, Present Rrq From Y II t r a To ca l Sulfur tlon
Ueeded for NeutralIty 1. 88 1.88 1.88 3.67 10.60 15.15 0 :oo 21.25 17.48 1.88 1.88 4.06 4.06 1.88 1.88 L2.41 22.09 4.08 1.35 19.37 15.60 10.53 20.21 2.20 3.65 1.88 1.80 1.88 1.98 1.88 1.88 7.39 13.25 11.37 5.51 1.79 8.72

V1

-houri t
Excess C Co3 a Equlv.

Aval l a b l e

Sulfur
4.06 4.06 L0.06 10.06 10.06 C0.06 0.06 4.06 4.06 4.06 4.06

a *

' b

4
Ssnd
0.2 04 . L0.1 0.3 13.27 1.77 0.2 0.9 1.3 13 . 26 . 15.2 4.7 1.8 14.9

1 / j BAR

b

4.06
0.15 4.06 4-06 'O.0C.
;

1.88 4.70 1.88 1.88
:.R=

27.12 5.08 3.70 3.16
?. ??

25.24 0.38 1.82 1.28
'.1.94

2.6 43.2 2.1 12.8
2.4

*Mostly carbolithic

EVATION

'

SAMPLE - N -

(MOISTURE) -

(AS

VATION

.

SATURATION % SAMPLE - NC -

SOL.

Revis

549

Revised 11/21/03

0 9 6
X U W
W

2

SIL

- L 4 3
U b

e

-

g

A

. . . . . . . . . . . . . . . . . . .
m
N A A A

g

~

~

~

g

g

m m m m

m m

~ m m m m m m m m

m m m m m m

m N

I - ;

n c

.

m ~7

. r

m

w Z
n

-- ba c - m -N

VL

Cl.4

c

n u -

.- 0
" 7

0 9 b- LL

C m u I C U

U

f ~ : 3 3 : 3 3 1 1 : : : 2 : 3 1 z z z z 1 2 ~ 3
551

d

~

m

~

~

~

w

-

m

m

o

d

~

m

o

~

~

w

~

m

r

n

8

Revised 11/21/03

o - nz
6.

0

n n n

7

3

-I

. .
I -

P

0

1 - 4 0 O m V I

? ?

W

.

m n x o m n
< u m

rn

c 0o r n -

r,I-:, . . . .
P W W

m

" b
3

s

0
7 a

s

W

-n -

" 3 H

. . . .
N N

m

W

N

W

m

W

4
I

a n
n

-1

O

W

O

-

. . . .
P P N 4 W N

N O

m

a

4

0

A

\

w
Y-

m

2003 DRILLING AREAS

(DEEP CORES)

LITHOLOGIC SYMBOLS AND DESCRIPTORS
(2003 DRILLING)

COLOR CODES

LITHOLOGY CODES

BLK - black BR
-

BRN - burn BR
CO CS

brown

-

burn coal claystone

BRGR - brownish gray DGR - dark gray DGRBR - dark grayish brown DRDBR - dark reddish brown DRDGR - dark reddish gray DYBR - dark yellowish brown GR - gray GRBR - grayish brown LBRGR LGR
-

MS - mudstone

SH - shale SL - siltstone SO

-

soil

SS - sandstone

light brownish gray

OTHER CODES

light gray

GAL

-

Green Analytical Laboratory, Inc.

LRBR - light reddish brown LRDBR - light reddish brown LYBR - light yellowish brown PBR - pale brown RBR - reddish brown RD - red RDBR - reddish brown RDGR

LC - lost core

-

reddish gray

RGR - reddish gray RDY - reddish yellow VDGR

-

very dark gray

YBR - yellowish brown

Revised 11/21/03

LITHOLOGIC SYMBOLS AND DESCRIPTORS
(2003 DRILLING)

COAL SEAM CODES (See C h a p t e r 4, Figures 6 and 6 a )
BOX - BLUE 0 B1X BXX
-

BLUE 1 BLUE

EOX - ORANGE 0 E 0 1 - ORANGE 0 & 1 MERGE E 1 X - ORANGE 1

E1A - ORANGE 1 A
E2X E3X EXX
-

ORANGE 2 ORANGE 3 ORANGE

G 1 X - GREEN 1 GXX - GREEN MOX - BOTTOM R E D 0 M1X MXX NOX NIX
-

BOTTOM RED 1 BOTTOM RED BROWN 0 BROWN 1

N2X - BROWN 2 NXX
-

BROWN

ROX - RED 0 R1X RXX
-

RED 1 RED

YOA - V I O L E T 0 A YOB - V I O L E T 0 B YOC - YELLOW 0 C YOX - YELLOW 0 Y 1 A - YELLOW 1 A Y 1 B - YELLOW 1 B Y1X YNX
-

YELLOW 1 YELLOW & BROWN MERGE

YXX - YELLOW

Revised 11/21/03

HOLE NUMBER: 30362EO*
MINE AREA: 52 DATE: 7/27/03 SAMPLE DEPTH NO. INCREMENT THICKNESS N/A
- ~ c

LITHOLOGY BRN CO FOB) SL CO (YlX) SS

COLOR

COMMENTS LC: 0.0-33.5 LC: 34.0-35.3 SANDY LC: 40.2-40.5 SILTY LC: 50.0-51.0 LC: 59.3-59.8 LC: 70.0-70.7 LC: 77.5-78.0 LC: 90.0-91.0, SANDY SILTY NONMINEABLE LC: 100.0-101.8 LC: 110.0-110.2 LC: 121.8-122.0
LC: 123.0-124.3 LC: 130.0-131.2

**

1

** +
5+
w

2# 3 4

6+ 7 8
9 10 11 12# 13 14
w

0.0-33.5 33.5-38.0 38.0-40.2 40.2-43.0 43.0-47.5 47.5-53.4 53.4-59.0 59.0-68.0 68.0-77.0 77.0-79.0 79.0-83.8 83.8-88.0 88.0-92.7 92.7-97.2 97.2- 100.0 100.0- 110.0 110.0-120.0 120.0- 123.0 123.0- 130.0 130.0- 134.6 134.6- 140.6 140.6- 143.7 143.7-148.0 148.0- 150.0 150.0- 160.0 160.0-170.0

33.5 4.5 2.2 2.8 4.5 5.9 5.6 9.0 9 .O 2.0 4.8 4.2 4.7 4.5 2.8 10.0 10.0 3.0 7.0 4.6 6.0 3.1 4.3 2.0 10.0 10.0

SH
SS CO (NXX) SS, SL CO (NIX) SS, SL SH, CO SL
SH CO (EOX), SH SS SS SS SH CO (ElX) SH, CO CO (E2X) SS SH, CO SS, SL
SS

N/ A BLK GR BLK GR VDGR, DGR GR BLK GR BLK GR VDGR, BLK GR
DGR VDGR, BLK GR, LGR GR, LGR GRBR, GR VDGR BLK VDGR, BLK BLK DGR VDGR GR, DGR LGR, GR

15+

**

LC: 140.6- 142.0

16+ 17 18 19

* Core boxes

I

1 through 14, 10 foot of core per box except Box 1 that represents 40 feet.

I

I

I

I

# Designated duplicate sample, process core, send representative split to GAL.

** Mineable coal seam, process core & store, no analyses required at t h i s time.
+ The following increments were removed to perform coal washability analyses: 64.5564.62, 65,65-65.70,68.0-68.3, 79.0-79.3, 134.6-134.9, & 143.7-144.0.

Revised 11/21/03

Revised 11/21/03

CORE NO: 3036230 Mine Area: J02, Peabody Coordinates: 24138.143, -17739.33N

--------- ------ --

Depth

Thick

RTYP~
Seam

-- -

0.00 33.50 38.00 40.20 43.00 47.50 53.40 59.00 68.00 77.00 79.00 83.80 88.00 92.70
LC CO SL

33.50 4.50 2.20 2.80 4.50 5.90 5.60 9.00 9.00 2.00 4.80 4.20 4.70 4.50 2.80 10.00 10.00 3.00 7.00 4.60 6.00 3.10 4.30 2.00 10.00 10.00 YOB Y1X

co

co
SS SH SL SH CO SS SS SS SH CO SH CO SS SH SS

SS SH SS CO SS

NXX

E1X EZX

ss

CORE NO: 3036230

Mine b e a : J02, Peabody Coordinates: 24138.143, -17739.33N

Depth

----0.00 33.50 38.00 40.20 43.00 47.50 53.40 59.00 68.00 77.00 79.00 83.80 88.00 92.70 97.20 100.00 110.00 120.00 123.00 130.00 134.60 140.60 143.70 148.00 150.00 160.00 YOB 7.96 -20.90 2.42 -9.31 50.90 <0.05 0.07 10.05 0.08 0.11 0.06 0.07 0.11 33.50 4.50 2.20 2.80 4.50 5.90 5.60 9.00 9.00 2.00 4.80 4.20 4.70 4.50 2.80 10.00 10.00 3.00 7.00 4.60 6.00 3.10 4.30 2.00 10.00 10.00

Thick

----0.50 0.40 0.40 0.20 0.39 0.29 0.28 0.27

Y 1X
28.40 16.40 51.00
NXX

13.00 11.70 7.47 69.40

4.43 7.90 0.41 69.40

0.06 <0.05 <0.05 10.05

0.10 CO.05 0.06 er box.

I

I

I

I

# Designated duplicate sample, process core, send representative split to GAL.

** Mineable coal seam, process core & store, no analyses required at this time.
+ The following increments were removed to perform coal washability analyses: 32.4-

32.7, 74.9-80.2, 84.5-84.8, 157.9-158.2, 196.45-196.50, 196.75- 196.80, 202.0-202.3, 203.4-203.6, 203.8-204.0, 204.2-204.5, 248.3-248.6, 255.5-255.8, & 265.9-266.2.

Revised 11/21/03

CORE NO: 3035430

Mine Area: N10, Peabody Coordinates: 34287.153,
Sodium Absorption Ratio Sand (SARI (%I

8595.89N

------------ - - -- - - 4. 2 25.0 25.0 21.0 GXX 3.3 3.4 6.0 10.0 9.1 0.5 RXX 4.3 14 .O MXX 0.5 1.6 0.7 1.0 4.2 4.6 0.2 0.3 0.3 0.8 0.4 0.4 1.9 1.6 0.1 0.3 11.0 19.0 16.0 Y1B 17.0 0.2 0.8 1.5 1.8 NXX 0.2 0.1 0.2 1.0 6.8 0.1 EOX 0.2 E1A 0.3 E1X 0.1 E2X 0.1 8.8 0.2 16.0 0.2 17.0 0.2 0.1 0.1 0.7 4.2 0.1 16.0 7.4 8.9 11.0 12.0 9.0 9.7 0.1 0.5 0.6 0.6 18 .O 9.2 14.0 37.0 31.0 8.6 18.0 9.3 26.0 38.0 25.0 32.0 48.0 60.0 18.0 18.0 3.2 1.6 20.0 1.8 4.0 40.0 66.0 2.3 2.2 3.6 5.9 4.1 0.3 13.0 22.0 31.0 46.0 45.0 17 .O 14.0 117.0 48.0 26.0 11.0 6.5 5.3 11.0 0.00 10.00 20.00 23.50 29.70 32.40 38.20 47.70 50.00 55.60 65.30 69.40 74.90 80.00 81.40 84.50 88.10 92.50 96.50 98.80 105.70 109.00 ll9.00 121.80 126.90 135.00 145.00 155.20 157.90 161.40 171.10 181.00 189.60 192.60 204.20 206.00 216.00 226.00 236.00 241.00 244.00 248.30 253.00 255.50 259.80 265.90 269.30 10.00 10.00 3.50 6.20 2.70 5.80 9.50 2.30 5.60 9.70 4.10 5.50 5.10 1.40 3.10 3.60 4.40 4 .OO 2.30 6.90 3.30 10.00 2.80 5.10 8.10 10.00 10.20 2.70 3.50 9.70 9.90 8.60 3.00 11.60 1.80 10.00 10.00 10.00 5.00 3.00 4.30 4.70 2.50 4.30 6.10 3.40 0.70

Depth

Thick Seam

Calcium (MEQ/LI

-- -- -- -- -

Magnesium MEQ/L)

Sodium

Silt 40 41 45 27 37 44 40 42

Clay (%I (%I ---- ---- ---23 15 15 31

Sulfur Total