Author

Tim Grabiel

Natural Resources Defense Council

Project Director

David Beckman

Natural Resources Defense Council

NRDC

THE EARTH’S BEST DEFENSE
Controversy Comes to a Head with Peabody’s New Request

for Increased Navajo Aquifer Access 14

Recommendations for Preserving the Navajo Aquifer 16

Appendices 19

Technical Report: Update ofthe CHIA Criteria Evaluation for

Peabody Western Coal Company Groundwater Withdrawals

from the NAqi.tifer, Black Mesa, Arizona 19

Selected References 32

Technical Review of “A Three-Dimensional Flow Model of the

D and N Aquifers” Prepared by HIS Geotrans and Waterstone,

for the Peabody Western Coal Company, September 1999 33

Endnotes 39

Natural Resources Defense Council 2
For more than 40 years, billions of gallons of groundwater have been pumped out of the Four Corners region of Arizona by Peabody Western Coal Company before being mixed with pulverized coal to create a thick,

black substance called slurry and piped more than 270 miles to a coal-fired

power plant in Laughlin, Nevada. Mining of this potable, pristine groundwater—

which serves as the primary source of drinking water for the area’s Hopi and

Navajo residents—has been connected to a variety of groundwater-related

problems. Peabody’s operations have had a range of environmental, cultural,

and religious impacts on the region’s tribal communities that make their

home in the Black Mesa plateau, and now Peabody is seeking to further erode

protections for this vital water source.

The Navajo aquifer, known as the N-aquifer, is an underground water-bearing formation that provides the

sole source of potable drinking water to many Hopi and Navajo on Black Mesa. Insulated by a barrier ofmudstone and sandstone, it naturally satisfies Environmental Protection Agency (EPA) standards for drinking water—unlike the region’s other aquifers, whose contents are brackish or otherwise contaminated. The springs

it feeds along its southern front are sacred to the Hopi people and essential to their religious practice.

In 2000, the Natural Resources Defense Council (NRDC) released a technical report entitled Drawdown:

Groundwater Mining on Black Mesa (“Drawdown”), which assessed the conflict between the coal company

using the Navajo aquifer for coal slurry operations and the people of the Black Mesa who rely on the aquifer

for clean water. The 2000 report evaluated the data on groundwater depletion and made recommendations

about what role the federal government should play in resolving the controversy. Six years later, Drawdown:

An Update uses new data to update the hydrogeological evaluation of the impacts of Peabody’s massive water

withdrawals on the health of the Navajo aquifer.

This 2006 update finds that not only are there signs of material damage to the aquifer, but that some of

the government’s failure to adequately monitor the damage can be attributed to a flawed modeling system

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easure of structural

Structural head of 100 feet above stability, remains within 100 feet of the top of the aquifer in

stability top of N-aquifer at any two monitored wells and has periodically dropped below the

point to preserve confined top elevation of the Navajo aquifer itself, indicating material

state of aquifer.” damage.

Criterion 2: “A value of leakage from Yes. Leakage is not adequately assessed. Although the

Water quality D-aquifer not to exceed 10 data needed for direct measurements are lacking, analysis

percent from mine-related of related data reveals increasing trends in chemical

withdrawals.” concentrations in some areas of the Navajo aquifer,

threatening water quality and potentially causing material

damage.

Criterion 3: “A discharge reduction Yes. Decline in discharge of 10 percent or more was

Discharge to of 10 percent or more indicated in three of four recently monitored springs and,

springs caused by mine-related if the model were updated and forced to calibrate, the

withdrawals based on conclusion that no material damage has occurred would not

results of N-aquifer be supported.

simulation.”

Criterion 4: “A discharge reduction Yes. Material damage is indicated by a decline in discharge

Discharge to of 10 percent or more of 10 percent or more. Three of four continuously monitored

washes caused by mining.” wash gauging stations show decline of at least 50%, clearly

indicating material damage; however, simulated modeling

results do not calibrate with monitoring data.

The new data show that Peabody’s mining practice of drawing down the aquifer—sapping the water

pressure that has taken many centuries to build—has already caused the aquifer material harm according to

some of the U.S. government’s own criteria. Now, a permit request from Peabody seeks to potentially increase

water withdrawals from the Navajo aquifer and loosen protections for this water source—despite signs of damage and continuing decline indicated by the physical monitoring data.

NRDC recommends a number of steps that must be taken to protect this critical water source:

• Peabody should permanently cease groundwater pumping from the N-aquifer, and the Office of Surface

Mining Redamation and Enforcement must deny Peabody’s request for increased access to these waters.

• The Department of the Interior should improve its monitoring of the N-aquifer and should ensure

that the Hopi tribe and Navajo Nation have a viable, long-term source ofwater.

• With tribal consent, the Environmental Protection Agency should designate the N-aquifer a “sole

source aquifer” that is granted government protection.

• Tribal sovereignty must be respected, and federal and tribal governments should work cooperatively to

manage aquifer resources.

Full text of the original 2000 technical report can be accessed online at www.nrdc.org.

Natural Resources Defense Council
Aquifers are like sponges, holding their groundwater in sediment or in tiny pores, fissures, and fractures of rock such as sandstone and limestone. Water trickles through these spaces, pulled from high pressure areas

to areas of lower pressure, but compared with surface water its flow is

imperceptible: it moves just

a few inches or feet in the course of

a year. Beneath

Black Mesa, water first flows south from the exposed Shonto plateau, then

divides. Over the last few decades, however, Black Mesa and its springs have

turned increasingly dry. The physical impacts to the Navajo aquifer have become

even more pronounced since the release of the original Drawdown report.

In 2000, NRDC examined the Office of Surface Mining Reclamation and Enforcement’s (OSMRE)

own standards for assessing material damage to the N-aquifer’s structural stability; its water quality, and its discharge to both springs and washes. Drawdown: Groundwater Mining on Black Mesa concluded that

under the government’s adopted criteria, material damage had clearly occurred to the N-Aquifer in at least

one respect. Drawdown further concluded that physical monitoring data belied many of the Department of Interior’s conclusions of no material damage, determinations which were often at odds with physical monitoring results. In fact, the government’s results stemmed almost exclusively from the results of incomplete and inappropriately used models of the N-aquifer.

For Drawdown: An Update, NRDC undertook a thorough review of the most recent monitoring data and, additionally, commissioned LFR Levine-Fricke (LFR) to update its technical review of the Cumulative

Hydrologic Impact Assessment (CHIA) criteria in light of the latest monitoring data (appended to this publication). This section revisits OSMRE’s material damage criteria with the most current physical monitoring data and expert review available. The results are discouraging:

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ge has already occurred.

Cumulative Hydrologic Impact Assessment Criteria Results Indicate Further Damage

In 1989, the Department of the Interior established Cumulative Hydrologic Impact Assessment criteria to

assess the material damage to the N-aquifer caused by Peabody pumping. Material damage was described as “any long-term or permanent change in the available quantity or quality of a water source that will preclude its use or reduce its utility to an existing water user.” 1

In 2000, after reviewing the data from the U.S. Geological Survey (a sister agency of OSMRE’s within the Department of the Interior) and Peabody’s own reports, NRDC concluded that based on the government’s own criteria, material damage had occurred. Six years later, the most recent data shows that the N-aquifer shows signs of continuing decline. 23Water withdrawals on Black Mesa clearly violated at least one criterion for establishing material damage, with other criteria strongly indicating material damage was occurring. These findings are particularly important due to the possibility of renewed water withdrawals at increased levels over the next 20 years, as discussed in the following section.

CHIA Criterion One: Structural StabilityCriterion: Maintain potentiometric head (the height to which confined liquid will rise when tapped by a well) of 100 feet above the top of N-aquifer at any point to preserve confined state of aquifer.

2000 Findings: OSMRE established material damage criterion to protect the structural stability of the N-aquifer. Peabody was to “{mjaintain potentiometric head 100 feet above top of N-aquifer to any point to preserve confined aquifer state.” 4In 2000, NRDC reported that six of the fifteen wells (Rough Rock, 1OT-258, bR-i 11, Sweetwater Mesa, BM3, and Kayenta West) dipped below the 100-foot potentiometric threshold. Even if the first four sites are discounted for their proximity to the aquifer’s unconfined portion, that still leaves two (Kayenta West and BM3) whose head fall within the signal 100 feet. As such, according to CHIA Criterion One, material damage continues to be indicated.

2006 Findings: Since 2000, water levels at most of the monitoring wells have continued to decline, supporting the findings of material damage made in Drawdown. 5In addition, the latest monitoring data indicates that water levels in Kayenta West and BM3 have dipped below the top of the N-aquifer, potentially compromising the confined state of the aquifer. If, as OSMRE indicated, maintaining a potentiometric head 100 feet above the top of the N-aquifer is intended to provide a protective barrier in order to preserve the confined state of aquifer, then these continuing declines raise two serious concerns: 6

• First, water levels at Kayenta West and BM3 have dipped far below the 100-foot criterion, which constitutes a violation of the CHIA requirements and an indication of material damage under OSMRE’s adopted safety standards.

• Second, because water levels at Kayenta West and BM3 have dipped below the top of the N-aquifer itself and, therefore, have potentially compromised the confined state of the aquifer in those areas, the violation of CHIA Criterion One is especially serious.

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ect measurements is lacking, monitors have sought to indirectly gauge the magnitude of leakage from the D-aquifer by the amount of inorganic compounds, or total dissolved solids (TDS), in N-aquifer water. The USGS identified increased chloride and

sulfate concentrations as important indicators ofincreased D-aquifer leakage. 7Drawdown conduded that data

from the previous 10 years had resulted in dramatic localized increases at certain wells that were discounted by OSMRE for sampling error, mislabeling, failure ofindividual well seals, or changes in pumping methods.

2006 Findings: The latest physical monitoring data indicates that the trend of increased chemical

concentrations has continued. The last 15 years have seen some dramatic localized increases, such as a spike in sulfate concentrations in a Chilchinbito well and a climb in TDS in a well at Forest Lake. Data collected at

various monitoring springs that discharge from the N-aquifer also show a marked increase in chloride. 9Recent

monitoring data provide evidence ofincreasing trends in inorganic constituents in the N-aquifer, including chloride and total dissolved solids, particularly in the southeast portion of near Rough Rock, Pinon, and Keams Canyon.’ 0Despite these trends and localized increases, OSMRE continues to conclude that material

damage has not occurredJ’

The sources of induced leakage have not been inadequately assessed. Leakage can occur for a number ofreasons: a shift in the vertical gradients between the D- and N-aquifers from pre-development to post- development times, a shift in the horizontal gradient in the N-aquifer, or a combination of both.’ 2With respect

to the vertical gradient, OSMRE makes no attempt to estimate induced leakage through water-level monitoring ofthe D- and N-aquifers and changes in their vertical gradients.’ 3With respect to the horizontal gradient, historic horizontal gradient in the N-aquifer was toward the south. However, it appears that horizontal gradient has reversed as a result of Peabody’s pumping regime—leakage now appears to be providing a source ofstorage (or recharge) to offset those pumping stresses.’ 4OSMRE has failed to adequately assess this shift in horizontal gradient.’ 5In short, OSMRE has failed to provide quantitative estimates of either the vertical gradient between the D-aquifer and the N-aquifer from pre-stress to post-stress periods or the horizontal flux or vertical induced

leakage based on observed changes in the horizontal gradient in the N-aquifer.

The CHIA criteria do not address the potential for man-made conduits that may effect water quality in the N-aquifer. In particular, wells in the Peabody well field are perforated or screened across multiple aquifers

Because water

and, as

quality

such, when

in overlaying

the wells

aquifers

are not

is

pumping,

worse than

a direct

in the

vertical conduit exists between the aquifers.’ 6

lower-lying N-aquifer, contamination conveyed through inactive wells is a possibility.’ 7Ifthe wells are not pumped for a significant period of time,

water that is “injected” into the N-aquifer from overlying aquifers under non-pumping conditions could

significantly impact water quality in the N-aquifer.’ 8Peabody’s massive water withdrawals coupled with its use of perforated well casings have created a situation in which damage to water quality may be occurring whether Peabody is pumping or not.

CHIA Criterion Three: Discharge to Springs

Criterion:

A discharge to springs reduction of 10 percent or more caused by mine-related withdrawals based

on results of N-aquifer simulation.

2000 Findings: OSMRE designed its third criterion to assess damage to the springs, finding that damage

was indicated if discharge fell by 10 percent or more as a result of Peabody’s withdrawals. Unfortunately, as

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2006 Findings: It remains unclear how a conclusion can be made that no material damage is evident based

on simulated modeling results under both the USGS model (1994) and Peabody model (1999) while physical monitoring data suggest otherwise. 2’The USGS’S most recent published monitoring data from four springs that discharge from the N-aquifer (Pasture Canyon, Moenkopi School, Burro, and an unnamed spring near Dennehotso) clearly shows an overall reduction in spring discharge for the three springs on the southwest side ofthe mesa (Pasture Canyon, Moenkopi School, and Burro). Discharge from the unnamed spring near Dennehotso has fluctuated over time, implying that some unknown change(s) may have occurred (e.g., new monitoring location, nearby construction), but the two lowest measured discharges over the last decade occurred within the last three years. 22 Looking at the annual data from Pasture Canyon, Moenkopi School, and Burro springs, physical monitoring data shows reductions that far exceed the 10 percent threshold: 24

percent percent at Moenkopi, 19 percent at Pasture Canyon, and 50 percent at Burro. 23 Moreover, if other historic spring discharge data were considered, observed discharge reductions would be much greater (70percent at Moenkopi and 85 percent at Pasture Canyon). 24All considered, if models used to support claims of

no material damage were updated and forced to calibrate to the physical data that has been collected, material damage would likely be indicated. OSMRE’s analysis of this criterion is severely limited by its reliance on

computer modeling, but if physical monitoring data were given precedence over modeling, material damage would be evident.

OSMRE continues to disregard actual monitoring data and historical accounts from Hopi elders that the outflow from springs sacred to the tribe has been drying up. 25 Instead, OSMRE has created a “virtual” world

that differs starkly from the reports on the ground in Black Mesa. It is not entirely clear how OSMRE could conclude that no material damage is evident based on simulated modeling results while physical monitoring data suggests otherwise. This finding of no material damage is particularly dubious since the groundwater

Using water levels to better assess water quality

A measure that should be used to supplement TDS sampling—one that was proposed by the Office of

Surface Mining in 1988, but was bumped from the CHIA’s final version—is water level. Under the proposed

criterion, the aquifer’s potentiometric head would be monitored for decline against a baseline altitude, which

represents how high its water would have climbed before Peabody’s operations began. Should its head drop

below 100 feet of this baseline—suggesting a sharp fall in water pressure and the formation of a pressure

gradient strong enough to pull lower-quality water from above—material damage would be indicated. (By

contrast, under CHIA Criterion One, potentiometric head is monitored for its proximity to the aquifer’s surface,

not to a predetermined baseline, and material damage is indicated where the head drops within 100 feet

of the aquifer itself.) If this proposed criterion were in use in 2000, there could be little question that water

quality was threatened. In the intervening years, water quality has worsened to the point where three of

the 11 monitored wells in the N-aquifer’s confined portion (Pinon, Keams Canyon, and BM6) have dropped

below the 100-foot mark and three additional wells (BM2, BM3, and BM5) are on the verge of crossing over.

Moreover, in the areas where the N-aquifer has dipped below the top of the N-aquifer, the introduction of air

can alter aquifer chemistry and result in damaging reactions such as the formation of iron and manganese

oxide precipitates. Such impacts would be irreparable.

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aquifer

s washes declined by 10 percent as a result of mine

related

groundwater pumping. As noted in 2000, evaluation of this fourth criterion, like evaluation ofthe third, relieson a “virtual” world of modeling that does not conform to physical monitoring data. Unfortunately, OSMRE based its analysis ofthis criterion on the latest USGS N-aquifer model, which had last been updated by USGS in 1994. OSMRE continues to condude that based upon that 1994 N-aquifer simulation, material damage has not occurred.

2006 Findings: Historical data do exist for flow in some area washes; however, the data are limited. According

to the USGS, continuous discharge data have been collected at four streamfiow gauging stations since the mid 1970s. 27The average annual discharge at the four gauging stations varies during the period of record. Nonetheless, according to USGS monitoring data, since 1995 the median winter flows for Moenkopi Wash, Dinnebito Wash, and Polacca Wash have generally decreased.

For the four continuously monitored washes, the median winter flows in 2003 were 0.75 ft3/sfor Laguna Creek, 0.25 ft3/sfor Dinnebito Wash, 0.10 ft3/sfor Polacca Wash, and 3.45 ft3/sfor Moenkopi Wash. By comparison, the earliest measured median winter flows for Laguna Creek (1997), Dinnebito Wash (1994),

and Polacca Wash (1995) were 1.8 ft3/s, 0.5 ft3/s, and 0.35 ft3/s, respectively. As such, flow reductions of 50

percent or more are evident since monitoring began in those three washes, which easily surmounts the 10

percent threshold identified in the CHIA criteria (see Table 2). For Moenkopi Wash, the period of record is

much longer and shows a general decline since the highest measured value in 1988, except during the last two

years where flow has increased. 28

Laguna Creek 1.8 ft3/s(1997) 0.75 ft3/s - 58%

Dinnebito Wash 0.5 ft3/s(1994) 0.25 ft3/s -50%

Polacca Wash 1.8 ft3/s(1995) 0.10 ft3/s -94%

Moenkopi Wash 3.2 ft3/s(1977) 3.45 ft3/s + 8%

The physical monitoring data clearly indicates that base flow in a majority of the monitored washes

have decreased by more than 10 percent since monitoring began. Material damage to the N-aquifer is evident; however, simulated modeling results do not calibrate with the physical monitoring data. Once again, OSMRE’s analysis of this criterion is severely limited by its reliance on computer modeling, but if physicalmonitoring data were given precedence over modeling, material damage would be evident.

As with spring discharge, to assess impacts of changes in base flow to washes this criterion depends on

simulated groundwater modeling results rather than physical monitoring data. The physical monitoring data suggests that base flow in the majority ofmonitored washes have decreased by more than 10 percent since monitoring began. As such, in accordance with the CHIA criteria, material damage to the N-aquifer is evident; however, OSMRE continues to rely on simulated modeling results that do not calibrate with the

physical monitoring data.

Wash/Creek

Table 2: Discharge to N-aquifer washes

Earliest Median Winter 2003 MedIan Winter

Flows Flows

Change in Median Flow

(percentage)

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Since mining began on Black Mesa three decades ago, more than 44 billion gallons of pristine groundwater have been pumped from the N- aquifer to feed the Peabody pipeline. As shown in the original Drawdown

report and again in this follow-up paper, data collected by the government often

contravene the government’s own conclusion that material damage has not

occurred. And yet, aided by flaws in the Interior Department’s criteria, holes

in its monitoring program, and basic deficiencies in its hydrogeologic model,

Peabody has been able to allege that the present use of water for slurry will not

adversely affect the aquifer and those who depend on it.

Drawdown noted that perhaps the principal deficiency in the government’s program is its overreliance on

modeling projections, which tend to obscure on-site evidence of material damage as described in Drawdownand this follow-up publication. For example, the third of OSMRE’s four material damage criteria, which

assesses the aquifer’s discharge to springs, depends entirely upon modeling, regardless ofwhat actual data may show. Simulations have also been used in application of criteria two and four, partly to distinguish Peabody’s impacts on water quality and washes from those ofthe tribes, although results there, too, fail to correspond with on-site trends or explain their divergence. 30Relying on the U.S. Geological Survey model, OSMRE has found that material damage to Black Mesa’s springs has not occurred, noting how simulated flows “decreased

[due to Peabody’s withdrawals] by less than 1 percent under all pumpage scenarios,” even though seven of nine monitored sites have already exhibited flow reductions well in excess of the government’s 10 percent ceiling. 3’

Flaws in the U.S. Geological Survey’s Two-Dimensional Model

Drawdown outlined a number of flaws in the U.S. Geological Survey model (“USGS Model”). Besides being misapplied, the official model was based on assumptions about recharge and other hydrogeological features that have since been called into question. Recharge is the process by which aquifers are replenished with water,

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the USGS model, and they overestimated the region’s annual precipitation, which colored the results. 33

In response to an internal critique of the USGS model, Drawdown reported that the U.S. Geological Survey took steps to revise its original estimate: recharge to the exposed Shonto region at the northern end of Black Mesa, the region believed to account for much of the N-aquifer’s recharge, has been downgraded

on the basis of detailed geochemical and isotopic measurements to between 2,500 and 3,500 acre-feet per

year, suggesting that actual recharge to the aquifer is but a fraction ofthe government’s original estimate. 34If this revised figure is correct, then Peabody’s current withdrawals from the N-aquifer most likely surpass what hydrogeologists would call the aquifer’s “safe yield,”—the difference between its annual rates of recharge and discharge. 35

Safe yield is like a surplus in an accounting book; it is the amount left after all the year’s credits (recharge) and debits (discharge) have been logged. ‘What happens to an aquifer when its safe yield is exceeded? As the hydrologist C.V. Theis wrote in 1940, “a new state of dynamic equilibrium is reached only by an increase in recharge, a decrease in discharge, or a combination ofthe two.” 36If an increase in recharge is not forthcoming,

a decrease in discharge to the washes and springs is to be expected.

Other criticisms of the USGS model have been made. The overarching issue concerning the USGS model is the fact that it is over a decade old and has not been run by USGS since 1994. LFR Levine-Fricke

reports that ifforced to update, the conclusion that no material damage has occurred would very likely not be supported. In addition, since a complete water budget (or allocation scheme) for the N-aquifer could

not be calculated from available field data, researchers relied upon estimates in their original study; though revisions were made in subsequent years, fundamentals of this water budget were not reconsidered and related

assumptions went unexplained. 37As has also been noted, conclusions regarding the levels of potential leakage from the overlying D-aquifer are likewise based on insubstantial evidence. 38

Peabody’s 1999 Three-DImensional Flow Model Is Fundamentally Flawed

In 1999, HIS Geotrans and Waterstone prepared for Peabody

A Three-Dimensional Flow Model ofthe

D

and NAquifers (“1999 Flow Model”) to develop estimates of N-aquifer water withdrawals. In 2002, at the

behest of NRDC, LFR Levine-Fricke provided a technical review of the 1999 Flow Model and accompanying documentation and its application to predicting impacts on the D- and N-aquifers (appended to this publication). This review focused on whether the new model improved the ability to assess material damage and other disturbances to the hydrologic balance relative to CHIA criteria and whether it accurately simulated

responses to Peabody pumping on such issues as groundwater elevations, aquifer discharge, induced leakage, and storage loss in the D- and N-aquifers.

The technical review concluded that the 1999 Flow Model is fundamentally flawed and fails to meet the

regulatory requirements. Major flaws include the following:

1. The 1999 Flow Model is inadequate to address all relevant consequences of mining on the hydrologic balance (and associated, existing CHIA criteria).

2. the model is otherwise flawed in important ways that destroy its utility and credibility, including its theoretic postulation of a nearly unlimited supply ofwater to replace water pumped by Peabody and mask the effects of Peabody pumping.

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y flawed in important ways that destroy its utility and credibility As documented in the attached report from expert hydrogeologists and modelers with LFR, the 1999 Flow Model has numerous inconsistencies and significant problems. Chief among them, the 1999 Flow Model artificially creates a nearly limitless supply of water residing in the D-aquifer that “replaces” water pumped from the underlying N-aquifer by the coal company for use in its operations. This element of the model fitndamentally obscures impacts and minimizes Peabody’s proportional role in those that are identified. In short, as more filly discussed in the attached LFR report, the 1999 Flow Model is inadequate to support the conclusions contained in Peabody’s permit application, nor is it capable ofsupporting a finding by OSMRE that material damage or other disturbances to the hydrologic balance will not occur as a result of Peabody operations. 42

It is instructive that an earlier 2002 permit application relying on the 1999 Flow Model contained significant caveats about the utility of the model. For example, Peabody acknowledged that the agreement between the model and observed water levels (alleged by Peabody) “does not necessarily mean that the predictions will be accurate.” 43 Peabody also noted that “[e] arlier 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.” 44

The Significant Shortcomings of Peabody’s 2005 Supplement In 2005, Peabody released a supplement to its Three-Dimensional Flow Model ofthe

D and NAqufi’rs (“the 2005 Supplement”). The purpose of the 2005 Supplement was to simulate and evaluate five additional pumping scenarios, provide results of additional sensitivity testing, and evaluate whether the models originally presented in 1999 are able to accurately simulate water level changes from 1997 through 2003 in the Black Mesa monitoring wells. At the behest of NRDC, LFR reviewed the 2005 Supplement to determine its ability to address CHIA criteria and resolve outstanding shortcomings outlined in the 1999 Flow Model (appended to this publication).

Peabody’s 2005 Supplement has three major flaws:

1. Previous concerns regarding the model and its ability to resolve specific CHIA criteria requirements remain unresolved, including a failure to resolve changes in spring discharge at the level necessary to evaluate CHIA criteria.

2. Essential statistics to support the supplement’s conclusions and facilitate peer review are not made available; rather, only declaratory statements are provided.

3. The model fails to include D-aquifer water-level data necessary to quantify leakage from the D-aquifer to the N-aquifer.Each of these issues is addressed in turn. First, the previous concerns regarding the model and its ability to resolve specific CHIA criteria requirements remain unresolved. As noted above, the 1999 Flow Model has insufficient resolution to address a critical issue: diminishment of flow at sacred and other springs in the

area. 45 As noted earlier, this critical concern is a central hydrogeologic issue, one which the 2005 Supplement fails to address (as pointed out years ago by LFR). The supplement therefore fails to provide the necessary information for OSMRE to assess impacts to individual springs. For example, LFR noted that to assess discharge reductions at Pasture Canyon spring, a 10 percent reduction in spring discharge would require

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aking available the information necessary to verify this

statement. The 2005 Supplement acknowledges this shortcoming when, comparing additional pumping data and simulated model results to the updated pumping data, the report states: “[tjhis evaluation, which is not

presented here, indicated that there were only small differences between measured and simulated drawdown

for the period 1997 through 2000” (emphasis added). The 2005 Supplement fails to conform to applicable industry standards for demonstrating model performance.

Third, neither the 1999 Flow Model nor the 2005 Supplement include water levels for the confined

portion of the D-aquifer. In fact, Peabody does not even monitor water levels in the confined portion ofthe

D-aquifer as part ofits monitoring efforts. This information is necessary to directly evaluate the change in leakage from the D-aquifer to N-aquifer under the 1999 Flow Model for CHIA Criterion Three. Moreover,

it would seem necessary to calibrate a model that incorporates the D-aquifer and is intended, in part, to

quantify leakage from the D-aquifer to the N-aquifer.

Peabody’s 1999 Flow Model continues to suffer from the same fatal flaws that were left unaddressed

in the 2005 Supplement. In fact, the 2005 Supplement raises a series of additional concerns that seriously

undermine the utility and predictive accuracy of the 1999 Flow Model and 2005 Supplement for determining material damage to the N-aquifer.

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The conflict is heating up between the coal company seeking to exploit the Navajo aquifer and the tribal communities who rely on the aquifer as

a

potable water source. Peabody has filed

a request to extend its mining

operations in Black Mesa and, despite the evidence to the contrary, claims that

this invasive mining and accompanying water withdrawals will not damage the

aquifer. But physical monitoring data as well as firsthand accounts tell

a story of

groundwater depletion that can be traced to Peabody’s operations in Black Mesa.Mohave Generating Station Closure

Since the 1960s, the Black Mesa mine has produced coal and the N-aquifer has provided water so that the dirtiest remaining power plant in the Intermountain West, located 273 miles away in southern Nevada, could operate. 48 During this period, tens of billions of gallons of pristine water have been removed from the

N-aquifer, causing material damage to the aquifer itself and threatening Hopi livelthood and the cultural practices that rely on it. 49 In 1997, environmental groups sued the co-owners of the Mohave Generating Station (MGS) to stop its repeated Clean Air Act violations. 5°According to available information, the 1,580-

megawatt MGS plant was releasing an average of 19,000 tons of nitrogen oxide, 40,000 tons ofsulfur dioxide, and 2,000 tons offine particles a year into the air above Laughlin. 51 That plume ofsmog and soot pollution

was contributing to the haze that diminished visibility at the Grand Canyon. 52 In 1999, MGS co-owners agreed to retrofit the plant, which supplied customers in California and in other states, with state-of-the-art

pollution controls by January 1, 2006. But when the MGS co-owners failed to retrofit the power plant and were forced to shut the plant down, most of Peabody’s water withdrawals from the N-aquifer ceased indefinitely. To many tribal members, the shutdown of MGS and the cessation of mining activities at Black Mesa mine were necessary steps to preserve the N-aquifer and its springs. 54 But the threat to the tribes and to

the balance of the N-aquifer remains.

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The conclusory statements in Peabody’s latest permit application conflict with empirical data indicating that several of the criteria for material damage to the N-aquifer have already likely been exceeded. As noted in

the Drawdown report and this publication, major impacts to the N-aquifer include:

• water levels in that have dipped below the 100-foot protective barrier and, in some locations, below the

top of the N-aquifer;

• dramatic localized increases in total dissolved solids, as well as sulfate and chloride concentrations at a

number oflocations;

• diminishment offlow by more than 30 percent from seven of nine monitored N-aquifer springs, with

spring flow reduction of 50 percent or more from three of four annually monitored N-aquifer springs;

and

• substantial reductions in wash discharge of more than 50 percent in three of four monitored washes, as

indicated by physical monitoring data, in excess of material damage criteria thresholds. 57

In apparent response to the concerns of the harm to the N-aquifer that the permit application would raise, Peabody included a provisional plan to use an alternative water source: the Coconino Aquifer (or “C

aquifer”). Critically, Peabody fails to show that C-aquifer water can be withdrawn consistent with OSMRE

regulations or that it is likely to be available to the mine. 58 Under Peabody’s latest permit application, until C-aquifer water is available, if ever, Peabody requests increased access to the N-aquifer for all of its operations, including production and resultant transportation of coal and its new coal washing water requirements. 59 Essentially, under Peabody’s latest permit application, if the C-aquifer never becomes available, is substantially delayed, or if Peabody decides it is not worthwhile to pursue, business as usual would continue on Black

Mesa.

As noted earlier, Peabody’s latest permit application suffers from at least two overarching shortcomings when it comes to issues related to the N-aquifer. First, Peabody’s permit application discounts physical monitoring data, concluding that material damage is not occurring despite monitoring data indicating otherwise. Second, in addition to discounting physical monitoring data, Peabody crafted the permit

application to continue its right to withdraw as much N-aquifer water as required for mining and transport operations through the life of the permit, while only making unsubstantiated assurances that it is committed

to seeking an alternative water source, much less that it will be available. 60 These unsubstantiated assurances

come in the face of a requested increase in the amount of water that Peabody would be allowed to withdraw—

in excess of 6,000 acre-feet a year.

In short, Peabody’s permit application, as drafted, would allow Peabody to increase water withdrawals

from the N-aquifer for the next twenty years despite the serious concerns raised by physical monitoring data already evident at much lower levels of annual N-aquifer pumping.

Peabody’s latest permit application to OSMRE is still being examined and will have to undergo

environmental review under the National Environmental Policy Act of 1969—a process that will continue

throughout 2006.

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The U.S. government has an obligation to protect the Black Mesa water system from groundwater mining,

a practice that virtually no one defends

as an appropriate—let alone the best—use of

a precious resource. To

preserve the Navajo aquifer and the sacred springs and washes it feeds, NRDC

concludes the following steps must be taken to protect the health of this vital

water source.• Peabody shouldpermanently cease groundwater pumping from the N-aquifer. As reported in 2000, there is ample evidence to suggest that Peabody’s annual withdrawal of more than a billion gallons of potable N-Aquifer water (which no one defends in principle) is endangering the ability of the Hopi and the Navajo

to draw on groundwater for subsistence and other needs. Given the evidence—the substantial fall of water

levels in the aquifer; mounting evidence that its recharge rates are substantially lower than originally forecast; evidence ofwater-quality degradation in at least some parts of the aquifer; declines in outflow from its springs; Peabody’s status as principal user; potential for severe, adverse consequences should pumping continue; and the protective principles that underlie the government’s trust relationship with the tribes—it should be the policy of the Department of the Interior that Peabody cease mining the N-aquifer and refuse Peabody rights

to any continued access of the N-aquifer as posited in Peabody’s most recent permit application.

• OSMRE must deny Peabody’s life-of-mine permit application. OSMRE cannot legally authorize a life- of-mine permit for the Kayenta and Black Mesa mines based on vague assumptions and future assurances that

an alternative water source may one day be available.

• The Interior Department should renew its investigation of alternatives to the current pipeline system. The Department of the Interior should update Phases 1 and 2 and conduct Phase 3 of the three-part study on coal transport alternatives that it began in the early 1 990s. The Environmental Protection Agency identified

a few of these alternatives in reviewing Peabody’s permit application 10 years ago: replacing water-based coal slurry with a methanol-based slurry; substituting low-grade water for the pristine drinking water of the N- aquifer; using reclamation technologies to reduce the total amount ofwater needed, regardless of the source;

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ates, and NRDC

s

investigation has determined that recycling in this case may be technically feasible, once the needs of local

farmers are met. 63

• The Department ofthe Interior should adopt safe yield as its management goal. Under the standard

known as safe yield, users of an aquifer cannot take more than the aquifer’s natural surplus; i.e., the difference between what the aquifer annually acquires through recharge and what it loses through discharge to springs and washes and other natural processes. Meeting this standard means developing policies and parameters that will ensure the availability of groundwater long into the future. Other standards—such as sustained

yield, which sets a 100-year parameter for an aquifer’s sustainability—provide neither a long-term solution to groundwater overdraft nor an appropriate way to ensure the viability of peoples that have inhabited the same land for many hundreds of years. With tribal consent, the Department of the Interior should adopt safe yield

as its management goal for the N-aquifer.

I The Department ofthe Interior should improve its monitoring ofthe N-aquifer. To ensure that safe yield standards are met and that washes, springs, community wells, and other features are protected in the long run, it is essential that the current monitoring regime be overhauled. The Interior Department should improve its metering of Moenkopi and other washes, take potentiometric measurements of the D- and Naquifers for a more accurate assessment of contamination risk, and make whatever additional adjustments

are necessary to address the potential impacts that OSMRE has identified. At the same time, it should open OSMRE’s material damage criteria, which help define the parameters ofits monitoring program, to a public

process of reexamination and revision.

• The Department ofthe Interior should recalibrate its hydrogeologic model ofthe N-aquifer. Data compiled by OSMRE and a reassessment of the aquifer’s recharge rate undertaken by the U.S. Geological Survey suggest that the department’s existing model does not reflect actual conditions. The department should revise its model accordingly. Of course, making these revisions to its modeling and monitoring programs should not delay the department in taking the precautionary steps we have recommended.

• With tribal consent, the Environmental Protection Agency should designate the N-aquifer a “sole

source aquifer” pursuant to the Federal Sole Source Aquifer Protection Program. The federal Safe Drinking Water Act recognizes that sole sources of regional drinking water, whose contamination “would

create a significant hazard to public health,” require special protection to ensure their long-term viability. 64 Once an aquifer has officially been designated a sole source under the program, no federal funding can be committed to any project that may result in its contamination. With the tribes’ consent, the N-aquifer should receive this designation from the Environmental Protection Agency.

• Tribal sovereignty must be respected, and federal and tribal governments should work cooperatively

to manage aquifer resources. The federal government and the Hopi and Navajo tribes must work together

to develop a viable policy of groundwater management applicable to reservation lands and modeled on the

safe yield standard of zero net withdrawals. Fundamental to the plan should be self-governance for the tribes with respect to groundwater management, enforceable limits on withdrawals from the N-aquifer to ensure

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This report has been prepared by LFR Levine•Fricke (LFR) at the request ofthe Natural Resources Defense

Council (NRDC) for the purpose of updating our review ofpotential hydrologic impacts to the N-aquifercaused by groundwater withdrawals associated with Peabody Western Coal Company (PWCC) mining

operations in the Black Mesa area ofNortheastern, Arizona. In September 2000, LFR provided an assessment of

potential impacts to the N-aquifer based on criteria established by the U.S. Department of the Interior Office of

Surface Mining Reclamation and Enforcement (OSMRE), (LFR 2000). This report is intended to update LFR’s

findings based on more recently obtained monitoring data, including, but not limited to, the United StatesGeologic Survey (USGS) annual reports on Groundwater, Surface Water and Water Chemistry for the Black

Mesa Area, Northeastern Arizona (Truini and Thomas, 2004; Truini and Porter 2005), and the USGS report onthe Hydrogeology of the D-aquifer and Movement and Ages of Groundwater Determined from Geochemical

and Isotopic Analysis, Black Mesa Area, Northeastern Arizona (Truini and Longsworth 2003).

Executive Summary

The objectives of this report are to determine whether material damage can be identified, based upon CHIA

criteria established by OSMRE. To accomplish the objectives, LFR compared monitoring data contained in theannual USGS monitoring reports and other pertinent documents with the criteria as explained in the CHIA.

Additional resource material was also reviewed to establish historic conditions and evaluate current trends.

To evaluate the impact of groundwater withdrawals on the N-aquifer, CHIA criteria were established

to allow for comparison offuture groundwater levels and surface water flows to baseline water levels and

flows established in the CHIA. The hydrologic concerns addressed in the CHIA are primarily related to thediminution ofthe N-aquifer water resource related to potential adverse impacts on water quantity and quality

The requirement of the first CHIA criterion is to maintain a potentiometric head 100 feet above the top

of the N-aquifer at any point to preserve the confined state of the aquifer. Since the September 2000 report,

water level declines have continued to be observed in most N-aquifer monitor wells. With respect to both

the Kayenta West and BM3 wells, monitoring data show that the water levels in those wells have periodically

dropped below not only the CHIA criteria level established to protect the aquifer, but the elevation of the top

of the N-aquifer itself. This adds additional concerns regarding potential material damage to the N-aquifer.

The failure of these wells to meet the criterion is dismissed by OSMRE as being the result of municipal

pumping in the Kayenta community even though the total municipal pumping at Kayenta represents less

than 12 percent of the industrial pumping by PWCC a short distance south of Kayenta. Notwithstanding

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, approximately 4,100 acre-feet per year of recharge to the upper N-aquifer layer is derived from vertical

leakage from the overlying layer (Carmel Formation); however, no discussion was provided regarding the areal distribution of observed leakage or whether changes in vertical leakage are observed between pre-stress and post-stress model simulations. Recent model simulations for various future pumping scenarios indicate that the N-Aquifer southeast of Pinon represents a source of recharge (or storage) for pumping stresses to the north. This is the same area where vertical leakage has been documented by changes in inorganic water quality; While the CHIA criterion can not be quantitatively evaluated based on available data, indirect

evidence of material damage associated with induced leakage exists.

The remaining two CHIA criteria were established to assess whether PWCC withdrawals would result

in N-aquifer discharge reductions of 10 percent or more to springs or base flow in washes. OSMRE relies on

groundwater modeling rather than physical monitoring to assess whether material damage is occurring, and has determined that material damage has not occurred. It remains unclear how a conclusion can be made that

no material damage is evident based on simulated modeling results while physical monitoring data suggests otherwise. Both the USGS and PWCC groundwater models used to make that judgment are admittedly incapable of resolving significant changes in spring discharges at the level required by the CHIA criteria. The physical monitoring data suggests that base flow in many of the monitored springs and washes have decreased by more than 10 percent since monitoring began. If the model were updated and forced to calibrate

to the physical data that has been collected, the conclusion that no material damage has occurred would not be supported. As such, in accordance with the CHIA criteria, material damage to the N-aquifer is evident; however, simulated modeling results do not calibrate with the physical monitoring data.

Introduction

The Cumulative Hydrologic Impact Assessment (CHIA) criteria used were established by OSMR.E in April 1989 to determine whether mine-related groundwater withdrawals resulted in material damage to the N- aquifer. On March 8, 1991, as part of a legal settlement, OSMRE agreed to review Black Mesa N-aquifer monitoring data against the CHIA criteria and thereafter report their findings to the Navajo Nation, Hopi Tribe, and PWCC in annual reports.

For the September 2000 report, LFR compared Black Mesa area monitoring data against the material damage criteria established in the 1989 CHIA. Based on our evaluation, LFR reported these findings:

• Based upon groundwater modeling performed for the CHIA, OSMRE concluded that none of the

projected impacts associated with proposed mine operations exceeded the material damage criteria; therefore, OSMRE. anticipated no material damage to the hydrologic balance within the study area.

• Flaws in the CHIA criteria and dependence of the criteria on an underlying groundwater flow model

hindered evaluation. These flaws raise questions regarding OSMRE’s conclusions.

• Three of the four material damage criteria may not necessarily be protective of N-aquifer water

resources because they are either directly or indirectly dependent upon modeling results from a model

not specifically designed to evaluate those criteria. OSMRE bases its analysis of CHIA Criteria 3

and 4 on the latest USGS N-Aquifer model or makes no evaluative attempt. Since the final CHIA

was released in 1989, USGS has performed modeling simulations twice. The most recent modeling

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other CHIA criteria would likely support the conclusion that material damage has occurred. The Black

Mesa monitoring data indicate that excessive pumping of the

N aquifer has caused groundwater level

declines and spring discharge reductions exceeding guidelines established in the CHIA. Data trends

further indicate that additional material damage is imminent.

Objective

The objectives of this report are to determine whether material damage can be identified, based upon Black

Mesa CHIA criteria. To accomplish the objectives, LFR compared monitoring data contained in the annual

USGS monitoring reports and other pertinent documents with the criteria as explained in the CHJA.

Additional resource material was also reviewed to establish historic conditions and evaluate current trends.

The scope of this evaluation is limited to impacts of pumping on the N-aquifer groundwater resource and

does not address other pertinent criteria such as surface water quality.

Hydrogeology of the Black Mesa Area

The Black Mesa region of northeastern Arizona is located in the Plateau Uplands Hydrogeologic Province

and is characterized by high, isolated mesas and steep-walled canyons. The Black Mesa, with an area ofapproximately 5,400 square miles, is underlain by thick sequences of relatively flat-lying, well-lithified

sedimentary rocks. The mesa land surface rises steeply on the East Side to more than 3,000 feet above the

surrounding lowland, while it slopes gradually toward the lowland to the west.

A thin veneer of recent unconsolidated sediments covers the surface of the mesa with floodplain alluvial

deposits generally occurring in narrow bands along major drainage channels. The underlying sedimentary rock

sequence, Permian to Late Tertiary in age, is highly variable and consists of up to 10,000 feet of interbedded

sandstone, mudstone, siltstone, limestone, coal, and gypsum deposits (Lopes and Hoffman 1996).

Several water-bearing zones (aquifers) underlie the Black Mesa area. The primary aquifer in the Black

Mesa area is the Jurassic-age N-Aquifer, which includes the highly productive Navajo Sandstone and the

underlying Wingate Sandstone (Cooley et al. 1969). The N-aquifer is more than 1,200 feet thick in the

northwestern portion ofthe mesa and thins toward the southeast corner of the mesa. The N-aquifer isunconfined around the margins of the mesa where it is exposed and overlying sediments have been removed

by erosion. Beneath approximately 3,500 square miles of Black Mesa, however, the N-aquifer is fully saturated

and confined by sediments of the overlying D-aquifer and Carmel Formation (Lopes and Hoffman 1996).Recharge to the

N aquifer occurs primarily in the area near Shonto, north and northwest of the mesa, where

the N-aquifer is exposed at the surface (Lopes and Hoffman 1996).

The D-aquifer generally consists of isolated thin sandstone layers of the Morrison Formation and

the Cow Springs Member of the Entrada Sandstone, separated by thick sequences oflower permeability

mudstone and siltstone (Cooley et al. 1969). The thickness of the D-aquifer varies from less than 100 feetin the area northwest of the mesa to 1,300 feet in the central portions of the mesa (Lopes and Hoffman

1996). Groundwater occurs under both unconfined and confined conditions within the D-aquifer. Hydraulic

heads in the D-aquifer are as much as 600 feet higher than those of the underlying N-aquifer, resulting in a

significant potential downward gradient toward the N-aquifer. Recharge to the D-aquifer primarily occursalong the eastern slope of the mesa where the unit is exposed at higher elevations (Lopes and Hoffman 1996).

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of the mesa, the direction ofregional groundwater flow beneath the central portion of the mesa generally diverges toward the northeast and southwest (Lopes and Hoffman 1996). Groundwater from the N-aquifer discharges to Laguna Creek and Moenkopi Wash, as well as to springs along the margins of the mesa where

the N-aquifer outcrops. Water withdrawn from the

N aquifer takes many years to be replenished through the recharge area; therefore, long-term impacts on springs may result from groundwater pumping.

Precipitation in the Black Mesa area ranges from 7 inches per year to 18 inches per year near Shonto

and in the higher elevations of the mesa (Lopes and Hoffman 1996). Precipitation recharging the shallow

unconsolidated sediments and the upper D-aquifer results in shallow flow outward toward the margins of the

mesa and the occurrence ofsprings along surface drainage-ways.

Basis of Evaluation

Pursuant to the Surface Mining Control and Reclamation Act of 1977, OSMRE performed a CHIA of

PWCC’s Black Mesa/Kayenta Mine in the Black Mesa Area of Northeastern Arizona. In January 1988,

OSMRE issued a copy of their CHIA for the Black Mesa area. In April 1989, a revised CHIA for the Black

Mesa was issued. Differences between the Draft and Final CHIA were discussed in Section 5.2 of LFR’s

September, 2000 report evaluating cumulative hydrologic impacts on the

N Aquifer (LFR, 2000). The

purpose of the Black Mesa CHIA was to determine whether Peabody’s proposed extraction of approximately 4,000 acre-feet ofwater per year from the N-aquifer would cause material damage to the aquifer.

To evaluate the impact of groundwater withdrawals on the N-aquifer, CHIA criteria were established to

allow for comparison of future groundwater levels and surface water flows to baseline water levels and flows

established in the CHIA. Within the CHIA, pertinent baseline years are listed as January 1, 1980 through December 31, 1984 for surface water quantity evaluations, and 1985 for groundwater level evaluations. The

hydrologic concerns addressed in the CHIA are primarily related to the diminution of the N-aquifer water

resource related to potential adverse impacts on water quantity and quality.

Discussion

Table 1 lists the Black Mesa CHIA criteria standards that are specifically pertinent to N-aquifer groundwater

resources. The status of each of those criteria as reported in LFR’s September 2000 report and this report are included for reference. Below is a summary of Black Mesa CHIA criteria along with associated observations

from our evaluation.

Criterion 1.: MaIntain potentlometric head 1.00 feet above top of N-aquifer at any point to preserveconfined state of aquifer.

This criterion was established to protect the structural stability ofthe N-aquifer due to a reduction of

potentiometric head and water stored within the aquifer. Confined aquifers are typically dependent upon water

pressure contained within the matrix pore space to retain structural integrity; without the additional support of

pore space water pressure some aquifers can compact, causing a permanent loss ofstorage capacity and, in some

cases, surface land subsidence. Because the N-aquifer in the Black Mesa Area is comprised primarily of cemented

sandstone, the likelihood of aquifer compaction occurring is lessened. This likelihood of N-aquifer compaction is recognized on pages 5 6 of the CHIA; however, “as an added insurance” the criterion is retained.

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Water the D-aquifer not to exceed measured; analysis of analysis of related data reveals

quality 10 percent from mine- related data suggests increasing trends in inorganic

related withdrawals.” that water quality is constituents in the N-aquifer in some

threatened in some areas.

areas.

Criterion 3: “A discharge reduction Seven of nine monitored Three of four monitored springs

Discharge of 10 percent or more springs show a decline continue to show a decline in excess

to springs caused by mine-related in excess of 10 percent, of 10 percent; if the model were

withdrawals based on according to available updated and forced to calibrate, the

results of N-aquifer field data. conclusion that no material damage

simulation.” has occurred would not be supported.

Criterion 4: “A discharge reduction Moenkopi Wash shows a Three of four continuously monitored

Discharge of 10 percent or more decline of approximately wash gauging stations show decline

to washes caused by mining.” 25 percent; status of of at least 50%; material damage

other washes is difficult is evident however simulated

to ascertain, modeling results do not calibrate with

monitoring data.

Results ofthe September 2000 Assessment

In the September 2000 report, LFR located measuring point elevations for the N-aquifer wells listed in the

USGS progress reports and evaluated measured water levels based upon this criterion. Of the 15 wells listed as

existing within the confined portion of the N-aquifer in the USGS progress reports, six had a potentiometric head within 100 feet of the top of the N-aquifer. Three of those six wells (1OT-258, bR-i 11, and Sweetwater

Mesa) are located near the aquifer boundary between confined and unconfined portions of the N-aquifer and behave more like wells existing in the unconfined portion of the aquifer.

A fourth well, the Rough Rock well, is located in the unconfined portion of the N-aquifer.

Of the 11 wells monitored that were known to be installed in the confined portion of the aquifer, two (Kayenta West and BM3) were found to have a potentiometric head less than 100 feet above the top of the N-aquifer. The groundwater elevation in the Kayenta West well was reported in 1996 to be more than 11 feet

below the approximated top of the N-aquifer and in 1998 to be approximately 0.2 feet above the top of the N-aquifer. The groundwater elevation at BM3 was reported in 1996 to be within approximately 1 foot of the

top of the N-aquifer and in 1998 to be approximately 1.6 feet above the top of the N-aquifer.

OSMRE acknowledged this criterion failure at BM3 in their material damage reviews. However, since

the static water level in this well was 99 feet above the top of the

N aquifer when it was first installed (1959) OSMRE concludes that “material damage to the hydrologic balance of the N-aquifer, caused by mining, with

respect to maintaining the potentiometric head above the top of the N-aquifer, has not occurred.” Monitoring data indicate a water level decline in the BM3 well more than 93 feet since the pre-stress (or pre-mining) period.

“The criteria listed here were established by OSMRE in its Cumulative Hydrologic Impact Assessment of the Peabody Coal Company Black Mesa/ Kayenta Mine (1989), pp. 6-20 to 6-45 and 7-3 to 7-5. Assessments made in the column marked “status” are based on the analysis presented below.

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objective of having a groundwater elevation of at least 100 feet above the top ofthe N-aquifer in the confined

portion of the aquifer. The failure of this well to meet the criterion is dismissed by OSMRE as being the result

of municipal pumping in the Kayenta community OSMRE states in their 2004 Annual Hydrologic Data

Report that 516 acre-feet were withdrawn from the N-aquifer at Kayenta, accounting for 38% of all nonindustrial pumping from the confined portion of the aquifer. They don’t mention that the total municipal pumping at Kayenta represents less than 12% of the industrial pumping by PWCC a short distance south of

Kayenta. Furthermore, OSMRE does not include a discussion of the Kayenta West well in its material damagereviews because the USGS reported that the well had recently been pumped and water level measurements

were not considered representative. Nevertheless, historical monitoring data collected from the Kayenta Westwell show that this well would not meet the CHIA Criterion 1 objective, and it appears that material damage

to the hydrologic balance of the N-aquifer has occurred based upon CHIA Criterion 1.

For the BM3 well, water levels have fluctuated (both up and down) by approximately 10 feet from the

levels reported in the September 2000 report. The most recent monitoring data indicate that for the year2004, groundwater elevations are approximately 2.3 feet above the top of the N-aquifer. As such, this monitor

well continues to fail CHIA Criterion 1. Notwithstanding OSMRE’s exception for the BM3 well, it appears

that material damage to the hydrologic balance of the N-aquifer has occurred based upon CHIA Criterion 1.

With respect to both the Kayenta West and BM3 wells, monitoring data show that the water levels in

those wells have periodically dropped below not only the CHIA criteria level established to protect the aquifer,

but the elevation of the top of the N-aquifer itself. This adds additional concerns regarding potential materialdamage to the N-aquifer. The 100 foot threshold for CHIA Criterion 1 was intended as a buffer to protect the confined state of the aquifer. As the water levels drop below the confining layer, the aquifer begins to dewater

and air enters the previously saturated pore spaces. Even if water levels rebound, air can become entrained

in the pore spaces and can reduce the permeability and storage capacity of the aquifer in the area where the

overdraft occurred. In addition, the introduction of air can alter aquifer chemistry and result in damaging

reactions such as the formation of iron and manganese oxide precipitates. Such impacts may be irreparable.

Criterion 2:

A value of leakage from the D-aquifer not to exceed 10 percent from mine-related

withdrawals.

Continued stresses on the N-aquifer and associated water level declines, as observed, will increase vertical

gradients and potentially induce vertical leakage of poor quality water from the overlying D—aquifer. Thiscriterion was established to prevent degradation of N-aquifer water quality due to induced leakage of poor

quality groundwater from the overlying D-aquifer.

In order to quantify leakage from the D-aquifer to the N-aquifer, water level elevations for both aquifers

and the vertical hydraulic conductivity ofthe confining unit separating the aquifers are needed. However,

since D-aquifer water level data is not regularly monitored, other approaches must be used. Other methods

of evaluating D-aquifer leakage to the N-aquifer include inorganic water quality monitoring from the D- and

N-aquifers and groundwater flow and transport modeling.

To establish and evaluate this criterion for the CHIA, OSMRE used the USGS N-aquifer model.

Specifically, the CHIA evaluated the model’s simulation of predicted changes in the annual volume ofleakage

from the D-aquifer to the N-aquifer attributable to mine-related withdrawals. The CHIA predicted no

significant change in volume of D-aquifer leakage to the N-aquifer for the simulated period.

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multiple monitoring locations, the trends were noted to be “small” or “statistically insignificant.” OSMRE

concluded that “material damage to the hydrologic balance ofthe N-aquifer, caused by mining, with respect

to leakage from the D-aquifer to the N-aquifer, has not occurred.” OSMRE based its conclusion upon inorganic water quality analysis only; other methods of analysis were not attempted. No attempt was made to

correlate the trends of increasing TDS with the material damage criterion.

Ifleakage to the N-aquifer were estimated as proposed in the draft CHIA by evaluating the magnitude of N-aquifer water level declines and associated changes in the vertical gradient between the D-aquifer and

the N-aquifer, a conclusion of material damage to the N-aquifer water quality would be more likely. The

N-aquifer potentiometric head was more than 100 feet below the baseline altitude in at least two ofthe

monitored wells (Pinon and Keams Canyon). Additionally, data trends for at least four additional wells (BM2,

BM3, BM5, and BM6) indicate that groundwater levels would soon be more than 100 feet lower than thebaseline altitude in those wells. Ultimately, six or more of the eleven monitored wells would likely exhibit

groundwater level declines more than 100 feet before mining operations cease.

CHIA Criterion

2 Update

The CHIA criteria set a 10 percent increase in induced leakage attributed to mine-related withdrawals asthe basis for determining material damage to the N-aquifer. While physically quantifying the amount of

induced leakage associated with mine-related withdrawals may not be possible, estimates could be based

on the fact that the amount of leakage induced by groundwater withdrawals would increase proportionally

to the increased vertical gradient resulting from those withdrawals [i.e., from Darcy’s Law:

Q (flux) = K (hydraulic conductivity) x I (gradient) x A (area)]. In other words, everything else being equal, an increase in

the vertical gradient by 10 percent would increase the vertical flux ofleakage by 10 percent. However, rather

than attempting to estimate induced leakage through water-level monitoring and changes in vertical gradients

or using water balance results from groundwater modeling, OSMRE looks at inorganic water quality as anindirect indicator ofinduced leakage to make the conclusion that material damage has not occurred.

Recent monitoring data provide evidence of increasing trends in inorganic constituents in the Naquifer, including chloride and total dissolved solids, particularly in the southeast portion of Black Mesa near

Rough Rock, Pinon, and Keams Canyon. Induced leakage resulting from groundwater withdrawals doesnot necessarily occur in the immediate vicinity of the pumping stresses, rather it can occur at some distance

away where resistance to vertical flow is reduced and leakage can provide a source ofrecharge to offset those

pumping stresses. As such, evidence of induced leakage from the D-aquifer to the N-aquifer in the southern

portion of Black Mesa may potentially be related to groundwater withdrawals by PWCC further to the north.

In 2003, the USGS issued a report on the Hydrogeology ofthe D-aquifer and Movement and Ages of

Groundwater Determined from Geochemical and Isotopic Analysis, Black Mesa Area, Northeastern Arizona

(Truini and Longsworth 2003). That report included a discussion on groundwater leakage from the D-aquifer

to the N-aquifer based on geochemical and isotopic data analysis and concluded that leakage has occurredfrom the D-aquifer to the N-aquifer for thousands of years, and most likely occurs in the southern part of

Black Mesa. Unfortunately, the report avoids any quantitative discussion of the change in vertical gradients

between the D- and N-aquifers from pre-development to post development times.

A separate USGS report

(Thomas 2002) states that groundwater monitoring of the N-aquifer has shown that vertical drawdowns have

increased the differences between the potentiometric surfaces of the D- and N-aquifers by greater than one

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discussion was provided regarding the areal distribution of observed leakage or whether changes in vertical

leakage is observed between pre-stress and post-stress model simulations. This would seem like a logical and

necessary evaluation to include considering the specific requirements of the CHIA criteria.

Regardless of the modeling and water-quality monitoring efforts that have been done to date, there

have been no attempts to provide quantitative estimates of either horizontal flux or vertical induced leakage

based on observed changes in the horizontal gradient in the N-aquifer or the vertical gradient between theD-aquifer and the N-aquifer from pre-stress to post-stress periods. Horizontal groundwater gradients in the

N-aquifer have changed significantly in the southern portion of Black Mesa since the introduction of PWCC

withdrawals. The most recent model simulations indicate that groundwater flow in the N-aquifer southeast

of Pinon is to the north and represents a source ofstorage (or recharge) for pumping stresses to the north.

This area is also where vertical leakage has been documented by changes in inorganic water quality. While the

CHIA criteria cannot be quantitatively evaluated based on available data, indirect evidence of material damageassociated with induced leakage exists. In short, based upon the information provided, the impact of increased

vertical gradients on the potential for increased induced leakage from the D-aquifer as a result of PWCCwithdrawals from the N-aquifer has not been adequately assessed.

In addition to concerns about induced leakage, available reports do not address the potential for man

made conduits that locally may impact water quality in the N-aquifer. In particular, wells in the PWCC

well field are screened across multiple aquifers and, as such, when the wells are not pumping a direct vertical

conduit exists between the units. Ifthe wells are not pumped for a significant period of time, water that is

“injected” into the N-aquifer from overlying aquifers under non-pumping conditions could significantly

impact water quality in the N-aquifer.

CriterIon 3:

A discharge (from N-aquifer springs) reduction of 10 percent or more, caused

by mine-related withdrawals based on results of N-aquifer simulation..

This criterion was established to protect the natural springs in the Black Mesa area. Well capture generally results

in reduced discharge from the aquifer, induced leakage to the aquifer, or some combination ofthose two.

OSMRE used the N-aquifer groundwater model to establish and evaluate this criterion for the CHIA.

They base the criterion on present and future N-aquifer simulations. Apparently, when model updates are

unavailable this criterion is based upon the most recent model results or no material damage evaluation is

attempted. Within the CHIA, only one spring area (Pasture Canyon) appears to have been evaluated. TheCHIA predicted “outflow to the springs in Pasture Canyon would not be affected by the duration of pumping

at the mine.” However, later in the same paragraph (page 6-39) OSMRE states that the simulated outflownumbers for Pasture Canyon “should be used with caution because the model does not adequately represent

important details of the local geology in this area.” They also state “reliable estimation of changes in flow ofthe Pasture Canyon springs would require detailed study and modeling of that local area.”

Results of the September 2000 AssessmentIn its annual material damage reviews, OSMRE based its analysis of this criterion on the latest USGS Naquifer model or made no evaluative attempt. Since the final CHIA was released in 1989, the USGS had

performed modeling simulations twice. The most recent modeling results were presented in the 1992-1993

USGS progress report released in 1995. Therefore, all OSMRE material damage analyses were based upon

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(Dennehotso, Hard Rocks); however, original flows at Hard Rocks were only estimated, and the magnitude

of change in flow from the spring near Dennehotso tended to imply that some unknown change(s) may

have occurred (e.g., new monitoring location, nearby construction). Some ofthe monitoring data werequestionable due to variable monitoring locations and the lack of any attempt by the USGS to correlate them.

Not only had most springs experienced a discharge reduction in excess of 30 percent, but the majority of those

appeared to have decreased by more than 50 percent (Rock Ledge, Moenkopi School, Many Farms, Whiskey,and Pasture Canyon). Hence, regardless of the monitoring data deficiencies, material damage appeared

obvious based upon actual conditions. It was unclear why the modeling simulations had not been adjusted

(calibrated) to better represent observed decreases in spring discharges.

CHIA Criterion 3 Update

The USGS report “Ground-Water, Surface-Water, and Water Chemistry Data, Black Mesa Area, Northeastern

Arizona—2003-2004” (Truini and Porter 2005) contains recent data for four springs that discharge from the

N-aquifer. Of the four springs, three are located on the southwestern side of Black Mesa (Pasture Canyon,

Moenkopi School, and Burro) and the other is on the northeastern side of Black Mesa (unnamed spring

near Dennehotso). Annual discharge data dating back to at least the early 1 990s are provided. Some historicdischarge data (pre-development) are also provided.

A graph showing trends in discharge for all four springs

is presented, although the data is plotted on a logarithmic scale making interpretation difficult.

A closer look

at the data clearly shows an overall reduction in spring discharge for the three springs on the southwest side of

the mesa. Discharge from the unnamed spring near Dennehotso has fluctuated over time making a definitiveanalysis of the overall trend more difficult; however, the two lowest measured discharges observed since annual

measurements commenced in 1992 occurred within the last three years. Using only the annual data collected

at the same location for each spring, estimates of discharge reduction since monitoring began are 24 percent

at Moenkopi, 19 percent at Pasture Canyon, and 50 percent at Burro. Considering that industrial pumping

at PWCC represents the single largest stress on the N-aquifer (roughly 75 percent of withdrawals from the

confined portion of the N-aquifer in 2003), monitoring data shows that material damage has occurred based

on the CHIA criteria (a reduction of discharge of 10 percent or more). If other historic spring discharge data

were considered, observed discharge reductions would be much greater (70 percent at Moenkopi and 85percent at Pasture Canyon).

It remains unclear how a conclusion can be made that no material damage is evident based on simulated

modeling results under both the USGS model and PWCC model while physical monitoring data suggests

otherwise. The groundwater model used to make that judgment is admittedly incapable ofresolving

significant changes in spring discharges at the level required by the CHIA criteria. Physical monitoring datacontinue to show that material damage, as defined by the CHIA criteria, is occurring. Ifthe model were

updated and forced to calibrate to the physical data that has been collected, the conclusion that no materialdamage has occurred would not be supported.

Criterion 4:

A discharge (from N-aquifer to washes) reduction of 10 percent or more,

caused by mining.

This criterion was established to prevent excessive reduction of flow in the Black Mesa area washes due to

reduction of N-aquifer discharge to the washes. When a stream is in communication with an aquifer and the

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discharges in some instances based upon model results, but never to exceed the material damage criterion.

Results ofthe September 2000 Assessment

As with Criterion 3, OSMRE based their analysis of this criterion on the latest USGS N aquifer model,

which had last been updated in 1994. OSMRE again concluded that based upon “the most recent N-aquifer

computer model simulation, material damage to the hydrologic balance of the N-aquifer, caused by mining,

with respect to N-aquifer discharge has not occurred” or that it “could not determine whether or not material

damage to the hydrologic balance of the N-Aquifer has occurred” due to a lack ofmodeling results.

Historical data do exist for flow in some area washes; however, the data are limited. For the baseline years

(1980-1984), data were only collected for the Moenkopi and Laguna Creek washes. The Dinnebito wash

had a monitoring station established in June 1993. Prior to establishing the 10 percent reduction criteria, the

CHIA noted that the Moenkopi gauge had been rated as having poor accuracy; As such, the margin of error inmeasurement of more than 15 percent exceeds the criterion range of 10 percent.

The USGS monitoring reports use low-flow data for comparing wash flows. Low-flow data are based

upon daily stream discharges for the months of November through February of a water year. Discharge data

collected during these months are considered representative of low flow because the effect ofstream loss due

to evapotranspiration (losses due to evaporation and transpiration, or the transfer ofwater to the atmosphereby vegetation) and gain from snowmelt and rainfall (which generally occurs during temperate months) is

minimized.

The Dinnebito wash had a mean daily discharge (as low-flow) of approximately 0.50 cubic feet per

second (ft 3/s), based upon 1994-1997 continuous-record data. The Dinnebito wash gauging station became

operational in June 1993. In 1998, the low-flow discharge measurements for the Dinnebito wash rangedfrom 0.32 ft3/sto 0.44 ft3/s, a reduction of at least 12 percent. The average mean daily discharge (as low-flow)for the baseline years on Moenkopi wash was reported to be about 3.2 ft3/s. From 1992 through 1998, the

average mean daily discharge (as low-flow) on Moenkopi wash was reported to be about 2.4 ft3/s. Therefore,there had been a discharge reduction of approximately 25 percent in the Moenkopi wash according to the

USGS progress reports. The Laguna Creek monitoring station had been moved to a new location sincereadings were taken for the baseline years making evaluation of that data difficult.

CHIA Criterion 4 Update

According to the USGS report “Ground-Water, Surface-Water, and Water Chemistry Data, Black Mesa Area,

Northeastern Arizona—2003-2004” (Truini and Porter 2005), continuous discharge data have been collectedat four streamfiow gauging stations since the mid-i 970s. The average annual discharge at the four gauging

stations vary considerably during the period of record and no long-term trends are apparent. Groundwater

discharge to the washes is assumed to be constant throughout the year, and the median winter flow is assumedto represent the constant annual groundwater discharge. According to the report, since 1995 the median

winter flows for Moenkopi Wash, Dinnebito Wash, and Polacca Wash have generally decreased and there is no

consistent trend in flows for Laguna Creek.

For the four continuously monitored washes, the median winter flows in 2003 were 3.45ft3/s for

Moenkopi Wash, 0.75ft3/s for Laguna Creek, 0.25 ft3/sfor Dinnebito Wash, and 0.10 ft3/sfor Polacca Wash.By comparison, the earliest measured median winter flows for Laguna Creek (1997), Dinnebito Wash (1994),

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evident; however, simulated modeling results do not calibrate with the physical monitoring data.

Summary

Ofthe four N-aquifer groundwater resource criteria identified in the Black Mesa CHIA, only one (Criterion

1) is written such that material damage can be readily determined through physical monitoring data. The

other three criteria are written such that material damage can only be determined if attributed to minerelated groundwater withdrawals through hypothetical modeling efforts. While municipal withdrawals have

grown over time, mine-related withdrawals still represent the single largest consumptive use of groundwater

at Black Mesa, accounting for about 62 percent of the total groundwater withdrawals and about 77 percentof the groundwater withdrawals from the confined portion of the N-aquifer (Truini and Porter 2005).Compounding the issue, most mine-related withdrawals are used to transport coal as slurry to Nevada. As

such, extracted groundwater is exported from the region, precluding any potential for conservation measures

that might be employed, such as treatment and re-use, if the water were used locally.

Evaluation of Criterion 3 is based solely on computer groundwater modeling simulations and Criteria 2

and 4 are directly dependent upon the modeling results. Since the modeling simulations are not performed

regularly, OSMRE. does not annually review the criteria based upon the simulation results, making it

impossible for them to ascertain whether material damage has occurred. Concluding material damage istherefore problematic based upon the final CHIA criteria irrespective of data evaluation. However, in lightof available monitoring data, it is not possible to support OSMRE’s conclusion that material damage has not

occurred, made in its annual analyses of Peabody and USGS hydrological data monitoring reports.

With respect to physical monitoring data for the N-aquifer, an evaluation of the more recently collected data

shows that the concerning trends previously observed and reported by LFR in September 2000 continue topersist. The median average annual decline in groundwater elevations in the confined portion of the NAquifer was reported to be approximately 2 feet per year since 1983. The median overall decline in water

levels in the confined portion of the aquifer from pre-stress period (1965) to 2004 is 72 feet with a maximumdecline of more than 205 feet at one location. Spring monitoring data show reductions in discharge of

between 19 percent and 50 percent in three of the four monitored springs since around 1990, and by more

than 70 percent if historical (pre-development) data are considered. Similarly, the USGS concluded that

median winter flows in washes, used to approximate base flow attributed to groundwater discharge, havebeen observed to be decreasing in excess of the CHIA criterion threshold for material damage in at least threeof four washes that have been monitored since 1995. Since a majority of groundwater withdrawals from the

N-aquifer are industrial and associated with the mine (particularly in the confined portion of the aquifer) theobserved impacts must be attributed in large part to those mine-related withdrawals and, therefore, physical

monitoring data confirms that material damage is still occurring as a result of Peabody withdrawals.

Technical Review of “A Three-dimensional Flow Model of the D- and

N-aquifers” and “A Three-dimensional Flow Model of the D- and N

aquifers Supplement 1”

LFR provided a review of the model developed by PWCC for the combined D-aquifer and N-aquifer and

determined that:

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Overall, the new model provided for recharge levels that greatly exceed the latest estimates provided by the USGS. In the PWCC model, approximately 11,000 acre-feet per year ofrecharge is applied in the unconfined portion of the N-aquifer. In addition, an estimated 5,400 acre-feet per year of recharge is derived from the river recharge boundary condition applied to the upper surface ofthe model as an initial condition (pre-pumping). The upper boundary condition represents an infinite supply ofwater, thus aquifer withdrawals will yield additional recharge from the river recharge boundary condition due to increased vertical gradients. It is estimated that more than 15,000 acre-feet per year ofrecharge could be derived from the theorized river recharge boundary condition if pumping stresses lowered groundwater elevations to the top ofthe N-aquifer. The impact ofthe river recharge boundary condition was not assessed in the sensitivity analysis. The PWCC model did not address the resolution problems that have precluded modeling as an accurate method

to assess material damages in the form ofreduced discharge from the N-aquifer. The PWCC model is unable to resolve changes in spring discharge from the N-aquifer or reduced flow in washes at the 10 percent level specified by the CHIA criteria. Actual monitoring data regarding spring discharges continue to contradict predictions based on modeling.

In July 2005, Supplement 1 ofthe Three-Dimensional Flow Model of the D- and N-aquifers was released. The purpose of the supplement was to simulate and evaluate five additional pumping scenarios, provide results of additional sensitivity testing, and evaluate whether the models originally presented in 1999 are able to accurately simulate water level changes from 1997 through 2003 in the Black Mesa monitoring wells. Based on

our review ofthe supplemental report, LFR concludes as follows:

• Previous concerns regarding the model and its ability to resolve specific CHIA criteria requirements remain unresolved.

• Calibration statistics typically provided in model validation reports (e.g., American Society for Testing and Materials [ASTM] guidance for documenting and calibrating groundwater flow model applications) are not made available, but rather qualitative statements are provided. For example, the supplement simply offers us this evaluation: “The four models match the observed water-level changes at the six BM monitoring wells quite well.” The report further states that the model was updated to include additional pumping data and simulated model results were compared to the updated pumping data. The report states, “This evaluation, which is not presented here, indicated that there were only small differences between measured and simulated drawdown for the period 1997 through 2000.” Subjective and unsupported narrative does not constitute technical support for the conclusion reached. It would be more appropriate to provide quantitative analyses of model validation that demonstrate

model performance within applicable industry standards.

• For the additional pumping scenarios, the report states that “predicted impact on discharge to streams

was almost negligible, and would not be measureable.” The question that more appropriately should be addressed is whether the model would be able to resolve changes in spring discharge at the level

necessary to evaluate the CHIA criteria. For example, to assess discharge reductions at Pasture Canyon Spring, a 10 percent reduction in spring discharge (CHIA Criterion 3) would require that the model accurately resolve changes in spring discharge of less than 5 gallons per minute or 8 acre-feet per year at

a minimum. Furthermore, if the model were accurately calibrated, it would show a reduction in spring flow of more than 19 percent at Pasture Canyon Spring since 1995 (Truini, Macy; and Porter 2005).

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would cause material damage to the aquifer, OSRME prepared a CHIA report dated April 1989 (4,000 acrefeet is typically used for estimation of mine-related groundwater withdrawals). Actual annual withdrawals

have ranged from 2,520 acre-feet to 4,740 acre-feet since mine-related withdrawals began in earnest in theearly 1 970s. The average mine-related withdrawal over that same period has been approximately 3,950 acrefeet. In the CHIA, OSMRE established specific criteria used to determine whether material damage would

occur. Based upon groundwater modeling performed for the CHIA, OSRME concluded that none ofthe

projected impacts associated with proposed mine operations exceeded the material damage criteria; therefore,

it anticipated no material damage to the hydrologic balance within the study area.

In September 2000, LFR evaluated groundwater, surface water, and water quality data from the Black

Mesa monitoring program contained in USGS Progress Reports to determine if material damage to the N aquifer could be detected or appeared imminent. Flaws in the CHIA criteria and dependence ofsome criteriaon an underlying model that was not specifically designed to evaluate those criteria made the evaluation

difficult. It was determined that while the model may reasonably predict regional N-aquifer groundwater conditions in the Black Mesa vicinity; the model does not adequately represent geologic detail to enable

conclusions regarding vertical leakage, spring discharge, and base flow in washes at the scale required by the final CHIA criteria. LFR concluded that, issues with the final CHIA aside, material damage was evident based

upon CHIA Criterion 1. Additionally, if monitoring data were given precedence over modeling predictions,

it could be determined that excessive pumping of the N aquifer has caused groundwater discharge reductions

to springs and washes that exceed the guidelines established in CHIA Criterion 3 and CHIA Criterion 4. The

most recent physical monitoring data indicates that the 2000 LFR Report conclusions are still valid.

Since LFR’s September 2000 report, physical monitoring data show excessive drawdown in many Black

Mesa area groundwater monitoring wells and continued declines in discharge to springs and washes. Based

on the latest physical monitoring data, LFR concludes that additional negative impacts resulting in material

damage have occurred and further material damage to the N-aquifer is imminent. Material damage is still indicated under CHIA Criterion 1 and, if physical monitoring data is given precedence over hypothetical

modeling results, material damage is also clearly indicated for CHIA Criteria 3 and 4. With respect to

CHIA Criterion 2, leakage is not adequately assessed but indirect evidence of material damage associated

with induced leakage exists. LFR continues to believe that the Black Mesa CHIA criteria are not necessarily protective of the N-aquifer water resources due to their dependence upon simulated computer modeling

results and disregard of actual monitoring data. Damage to the hydrologic balance of the N-aquifer may

be compounding over time due to the lack of protection provided based upon the CHIA criteria and

the disregard of actual monitoring data. Nevertheless, groundwater modeling results, rather than actual

monitoring data, remain the primary tool for assessing material damage to the N-aquifer. As such, a detailedand quantitative analysis of model performance, based on standard industry practices for model calibration

and documentation, and considering the rigorous requirements of the CHIA criteria, is needed.

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LFR Levine•Fricke. 1997. Evaluation ofImpacts ofGroundwater Pumpingfrom the NAqufèr, Black Mesa Area, Arizona. August.

LFR Levine•Fricke. 2000. Evaluation ofCumulative Hydrologic Impacts on N-Aqufr, Block Mesa, Arizona.

September.

LFR Levine•Fricke, 2002. Technical Review of “A Three-Dimensional Flow Model of the D and N Aquifers” Prepared by HIS Geotrans and Waterstone for the Peabody Western Coal Company, September 1999. April.

The Office of Surface Mining Reclamation and Enforcements. 2004. Report on its Review and Analysis of Peabody Western Coal Company’s 2003 ‘nnual Hydrological Data Report” and the U.S. Geological Survey’s “Ground-Water, Surface-Water, And Water-Chemistry Data, Black Mesa Area, Northeastern Arizona—2002-

03.” September.

The Office of Surface Mining Reclamation and Enforcements. 2005. Report on its Review and Analysis of Peabody Western Coal Company’s 2004 ‘Annual Hydrological Data Report” and the U.S. Geological Survey’s “Ground-Water, Surface-Water, And Water-Chemistry Data, Black Mesa Area, Northeastern Arizona—2003-

04.” August.

Thomas, B.E. 2002. “Ground-Water, Surface-Water, and Water-Chemistry Data, Black Mesa Area,

Northeastern Arizona-2000-2001, and Performance and Sensitivity of the 1988 USGS Numerical Model of

the N Aquifer.” U.S. Geologic Survey Water Resources Investigations Report 02-4211.

Truini, M. and S.A. Longsworth. 2003. “Hydrogeology of the D Aquifer and Movement and Ages of Ground

Water Determined from Geochemical and Isotopic Analysis, Black Mesa Area, Northeastern Arizona.” Water

Resources Investigations Report 03-4 1 89_Version 1.1.

Truini, M. and T.J. Porter. 2005. “Ground-Water, Surface-Water, and Water-Chemistry Data, Black Mesa

Area, Northeastern Arizona-2003-2004.” U.S. Geologic Survey Open File Report 2005-1080.

Natural Resources Defense Council J 32
Coal Company, September 1999

April 24, 2002 (LFR 014-10002-00)

Introduction

Three-dimensional flow models ofthe N Aquifer in the Black Mesa Basin ofArizona have been developed and used to evaluate effects from Peabody Western Coal Company (PWCC), and Navajo Nation and Hopi Tribe community pumping centers on the N Aquifer. Those modeling efforts have been applied to assess potential impacts to the N Aquifer.

The Department ofInterior has previously established Cumulative Hydraulic Impact Assessment (CHIA) criteria to assess the presence ofmaterial damage to the N Aquifer caused by PWCC pumping. The four main CHIA criteria included:

1. Maintain potentiometric head of 100 feet above the top of N Aquifer at any point to preserve confined

state of aquifer.

2. A value of leakage from the D Aquifer not to exceed 10% from mine related withdrawals.

3. A discharge to springs reduction of 10% or more caused by mine-related withdrawals based on results

of N Aquifer simulation.

4. A decline in discharge to the N Aquifer washes by 10% or more caused by mining.

Evaluation of the four CHIA criteria relies heavily or almost entirely on model simulation results. In fact,

the very terms ofsome of the criteria directly refer to a modeling analysis. Unfortunately, available models generally lack the necessary resolution and/or were not developed for the specific purpose of evaluating CHIA criteria. Thus there has been a large degree of uncertainty in conclusions derived from model predictions. In September 1999, PWCC issued a report summarizing the development of a new three-dimensional

flow model that simulated aquifer conditions and groundwater flow in both the D and N aquifers. One stated objective of this modeling effort was to help assess probable hydrologic consequences ofthe life- of-mine mining plan upon the quality and quantity ofsurface and groundwater for the proposed permit and adjacent

areas. More specifically, the model was used to estimate future impacts of PWCC and tribal pumping on the

D and N aquifers.

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comments. Major technical issues and other inconsistencies are discussed with reference to the model

documentation, where available. Overall, LFR’s comments can be condensed into the following three

statements:

i. The model, because of its nature, resolution, and data density, is not well suited to the task of assessing potential material damage or other disturbance to the hydrologic balance as it was intended to do. ii.

A surface boundary condition putting in effect an infinite amount ofwater on top of the aquifer

system is inappropriate in an arid to semi-arid climate setting. iii. The model includes both the

D and

N aquifers. The CHIA have been developed for the

N Aquifer only. By including groundwater storage of the

D Aquifer to the model, over 43% ofstored water

is added to the system. By adding storage to a system where “most of the groundwater pumped is released from storage,” the effects ofwithdrawals are effectively diluted.

Major Issues

A. Surface boundary condition

The model consists ofseven layers, the top three representing various members of the

D Aquifer. Layer four represents the thin Carmel Aquitard, and layers five through seven represent members of the

N Aquifer. Peabody states that water budgets provided in the model documentation are based on the combined

inflows and outflows of both the

D Aquifer and

N Aquifer. In the Black Mesa Area, the Mancos shale and

other unconsolidated deposits overlie the

D Aquifer. Those units are not explicitly defined in the model because they are thin and usually unsaturated (page 5-1). On page 5-12, it is stated that “Water primarily

moves into the Dakota aquifer from leakage ofwater through the Mancos shale overlying the Dakota sandstone.” This leakage is simulated in the model by a river boundary condition which, in effect, places an infinite amount of water on top of the model.

A “riverbed” conductance of 0.00026 ft/d and a thickness of

600 feet is used for the Mancos shale, and a “river stage” is assumed to be 100 feet above the top of the Mancos, or 700 ft above the top of the

D Aquifer (p. 513). This vertical conductance, albeit small, is theorized to yield a significant amount of inflow when considered over the area of the aquifer system modeled. ‘When combined with data on the aerial extent of the

D Aquifer (Surface statistics, Table 4.3-1) and evaporation (section 5.4.2, page 5-16), this simulated “river recharge” yields an estimated 5,400 acre-feet/year

or more to the combined aquifer systems, or nearly the equivalent of the documented withdrawals (Peabody mine and Indian Communities are estimated to withdraw 4,000 and 2,800 ac-ft/yr, respectively). Note that this boundary condition influx is an initial (pre-pumping) source of recharge in addition to the precipitation recharge of 11,000 ac-ft/year in the unconfined areas, discussed in the recharge boundary condition, section 4.6.9, and used extensively as a variable in calibration runs (ES-3 and page 4-36).

The river boundary condition on top of the model domain in itself contributes an inflow of equal magnitude as the groundwater withdrawals. With increasing drawdown in the underlying aquifers, the surface boundary condition, as theorized in the model, will yield more water due to increased vertical gradients. As such, the impact of the surface boundary condition is that sufficient water is always available as vertical leakage to the

D and

N aquifers to offset pumping stresses applied in the simulations. Impacts to spring discharge and baseflow in washes are minimized, the boundary between the confined and unconfined portion of the N-Aquifer is unaffected, and the confined portion of the N-Aquifer remains fully saturated. Yet, the

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(point features) as three-dimensional cells or cell blocks. For example, the lateral dimensions of one drain cell at Moenkopi School is 3,000 by 2,100 meters (9,840 by 6,890 feet) while in the actual scenario is a spring

area approximately 50 feet wide discharging anywhere between 12 to 40 gpm only. Such discrepancy in representation of a drain feature will effect the calibration that can either be aimed at water levels or discharge, but not both. This is an inherent and well-known problem ofMODFLOW and finite different models in general. The alternative would be the use of a finite element model.

In the vertical dimension, the report states that the contact elevations of the seven hydrostratigraphic units (HSUs) is generally accurate within 100 feet in moderately sloping terrains and up to 300 feet in steeper areas (Appendix F, page F-2 and F-6). This too, precludes an accurate representation ofsprings and intersects of HSUs by streams which are critical to the natural drainage ofthe aquifer system. These shortcomings related to grid resolution have been recognized by the authors on page 1-5: “The model grid, although optimized to address flow issues [stream discharge, recharge, leakance], was not designed to evaluate impacts at individual springs or wells.” Yet, the impact on springs is acknowledged to be a significant issue of concern, and is exactly the goal of CHIA criterion #3.

C. Confined and unconfined storage

The model combines the water budget (Table 5.8-4) for the

D and

N aquifers, thereby obscuring the CHIA that have been developed for the

N Aquifer only. The combined volume of the two aquifers increases the predicted amount of groundwater in storage by 43% (Table 4.3-1). Because most of the groundwater pumped is released from storage (page ES-6), the effects ofwithdrawals on the

N Aquifer are diluted. When unconfined storage is depleted, air enters the pore space to replace the extracted groundwater. When the groundwater is confined, storage depletion results in pressure drops that extend over very large distances (in the order ofmiles) to draw replacement water from the surrounding aquifer over long periods of time (decades).

Under unconfined conditions the amount ofstorage is determined by the storage coefficient which equals the specific yield (Sy), or drainable porosity at the water table. For confined conditions the storage coefficient is expressed as specific storativity (Ss) and is described as the volume of water released per unit volume of aquifer per unit change in head. Both these coefficients, and the respective condition that the groundwater in

a HSU is exposed to, have a significant effect on the amounts ofwater recharged, stored and pumped. However, from the nine calibration steps, only one (step 6, page 5-36) adjusted the specific storage while the remaining steps controlled the hydraulic conductivity and flow rates, specifically recharge. This does not

agree with the conclusion that the hydrologic system is “only mildly” sensitive to recharge (page 8-4). In the transient model run, a large contrast exists between the values of Sy (0.1) and Ss (3.05.10-7 ft-I). These values

are assumed constant throughout the vertical layering and the lateral extent (page 5-39, and Table 5.6-1). This is puzzling, since over 50 pumping tests have been performed over the area and storage coefficient is an output from such analyses. Furthermore, a change from confined to unconfined condition results in the release of large amounts of water, albeit irreversible. Once air enters a previously confined aquifer, its recovery will not be complete because of air entrapment and possible settling. The scenario shown in Figure 5.6-3 with the

new 3-D model showing a larger confined area than the 2-D model and virtually no effect on the confinedl unconfined boundary by the year 2033 cannot be justified with the storage data used.

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improve estimates of recharge”. It does not appear that a recharge rate representative of Lopes and

Hoffman’s work was used.

• Page ES-4: It is unclear why four models had to be calibrated in order to estimate the effects of PWCC

and community pumping on the D and N aquifers. If the difference between these four models is only

in recharge and discharge rates, one calibrated model and three “what-if” scenarios would seem more

appropriate.

• Page 5-33: The standard guide to model verification (ASTM, 1994), is referenced but does not appear

in Section 9, References and Bibliography. It is also unclear from the mass balance, Table 5.8-4, howthis verification relates to stream discharges which, in Tables 6.3-7 to 6.3-9, show no effect to pumping

whatsoever.

• Page 5-38: The units used in the model are meters and days, while the report is written in, and

the figures of contours show, units of feet. Reason for this inconsistency is undear and it makes

comparisons of calculations to reported graphs difficult.

• Figures 5.6-4 and 5.5-5: An anomalous geological feature with a contrasting hydraulic conductivity

connecting wells BM- 1, BM-2 and BM-3 is shown in the three lowermost formations, but its origin is

not explained.

• Figure 6.1-1: First part of the curve, historical pumpage, is different in the presented scenarios. If based

on existing data, the six curves from 1960 to 1998 should be identical.

• Figures 6.3-14, 6.3-21, 6.3-28, and 6.3-41. Problem in the legend of the drawdown contour: the

subtraction is not that ofscenario A — E, shown in Figure 6.3-7.

Summary of the Model’s Applicability to N Aquifer Issues

LFR has reviewed previous reports and modeling applications used to assess potential impacts to the N

Aquifer from mine-related groundwater withdrawals. The most significant issues previously identified by LFR

that are relevant to the current model review include:

• Most recharge to the N Aquifer occurs in the Shonto area north of the mesa where the N Aquifer is

unconfined.

• The quantity of recharge to the N Aquifer has been overestimated in previous modeling exercises.

Many early models included as much as 13,000 ac-ft/yr of N-aquifer recharge. More recent studies

conducted by the U.S. Geological Service (USGS; Lopes and Hoffman, 1996) incorporating detailed

geochemical and isotope measurements suggest that the average rate of recharge to the N Aquifer

during the past several thousand years may be as low as 3,100 ac-ft/yr in the primary recharge areaalong the northern margin of the mesa.

• USGS studies by Brown and Eychaner (1988) estimate that only 3% of the N Aquifer water budget is

attributed to leakage from the overlying D Aquifer.

• CHIA criteria were developed by the Department of Interior, Office of Surface Mining Reclamation

and Enforcement to establish if material damage to the N Aquifer has or may occur as a result of

mine-related withdrawals. Those criteria may not be protective because many depend either directlyor indirectly on simulations using ground water models that were not specifically designed to evaluate

those criteria.

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ge boundary condition applied to the upper surface of the model as an initial condition (pre-pumping). The

upper boundary condition represents an infinite supply ofwater, thus aquifer withdrawals will yield additional recharge from the river recharge boundary condition due to increased vertical gradients. It is estimated that

more than 15,000 ac-ft/yr of recharge could be derived from the theorized river recharge boundary condition if pumping stresses lowered groundwater elevations to the top of the

N Aquifer. The impact of the river recharge boundary condition was not assessed in the sensitivity analysis.

The PWCC model does not address the resolution problems that have precluded modeling as an accurate method to assess material damages in the form of reduced discharge from the

N Aquifer. The PWCC model is unable to resolve changes in spring discharge from the

N Aquifer or reduced flow in washes at the 10% level

specified by the CHJA criteria. Actual monitoring data regarding spring discharges continue to contradict

predictions based on modeling.

It does not appear that changes incorporated in the PWCC model improve the ability to assess the CHIA criteria or to assess any similar criteria that may be developed. The

N Aquifer was the primary subject of the CHIA because, among other things, it represents a sole-source drinking water supply for the Hopi Tribe and many members of the Navajo Nation. Water quality in the

D Aquifer is generally too poor for human consumption.

Applicability of the Model to Other Groundwater Issues

PWCC used their model to assess a broader range of impacts as defined by their report on Probable

Hydrologic Consequences, Chapter 18 of Peabody’s Revised Mining Application. Previous reports in defense of PWCC groundwater withdrawals include community withdrawals when discussing potential damages to the

N Aquifer. However, the community wells are not used for calibration in the PWCC model due to “a lack

of detailed information on pumping in community wells”. Considerable information has been collected by the USGS on annual pumping and/or water use, and on water levels in wells used by the various communities and it is not apparent why simulation results were not calibrated to available community pumping center data.

The reports provided by PWCC suggest that past (45÷ years) as well as future groundwater extraction (an additional 20+ years) at the mine will only capture water from aquifer storage (rather than recharge). Water is captured from aquifer storage under transient conditions when wells are initially pumped. Equilibrium conditions are reached when the cone of influence extends to (and captures) some source of recharge. This will result in reduced discharge from the aquifer (as springs or baseflow in washes) and/or an inducement of

additional recharge as leakage from overlying units to offset the withdrawals. Ifwithdrawals exceed availablerecharge, then transient conditions persist and groundwater again is removed from aquifer storage. Under that scenario, groundwater elevations will continue to decline and dewatering ofthe aquifer can occur. PWCC

suggests that the process of reaching equilibrium with groundwater withdrawals never occurs over the 65+

years of continuous pumping from the aquifer.

In contrast to previous studies that suggest only 3% of the

N Aquifer water budget is attributed to leakage from the overlying

D Aquifer, the inclusion of the

D Aquifer and use of a river recharge boundary in the model provides far greater aquifer storage and recharge to offset mine-related withdrawals. It is not surprising that impacts to

N Aquifer discharges are minimized in the model.

Natural Resources Defense Council 37
suitable for human consumption.

• Incorporation of the D Aquifer and river recharge boundary condition, along with N Aquifer recharge in the unconfined areas, results in recharge assumptions that are substantially higher than any other known estimate and are inconsistent with recharge evaluations in both unconfined and confined

portions of the N Aquifer provided by the USGS and others.

• The inclusion of the D Aquifer and use of a river recharge boundary in the PWCC model inappropriately provides far greater aquifer storage and recharge to offset mine-related withdrawals. As

such, conclusions regarding impacts to N Aquifer cannot be substantiated.

• The model, because of its nature, resolution, and data density; is not well suited to the task of assessing potential material damage or other disturbance to the hydrologic balance as it was intended to do.

ABOUT THE AUTHORS

LFR Levine Fricke (LFR) is an environmental consulting and engineering firm headquartered in the San Francisco Bay Area with approximately 400 employees in 20 offices nationwide. LFR provides assessment, visualization, and practical solutions to engineering and environmental problems associated with resourcemanagement, infrastructure development and improvement, and hazardous waste management.

Dr. Vit Kuhnel, Ph.D., has over 15 years of experience in environmental engineering and water resource

management on projects throughout the United States, Europe, and the Middle East. His expertise in hydrogeology and geochemistry includes groundwater exploration and modeling, contaminant fate

and transport modeling, remedial systems analysis, and design and implementation of corrective actions. Dr. Kuhnel’s primary focus is on the acquisition, interpretation, trend analysis, and presentation of hydrologic data using groundwater flow and transport models ranging from simple analytical codes to sophisticated, three-dimensional, multi-phase and transient models. Dr. Kuhnel works within LFR’s Water Resources and

Quantitative Services Group which provides state-of-the-art modeling and three-dimensional visualization of

surface, unsaturated sub-surface, and groundwater flow and transport phenomenon.

Bradley Cross, R.G., is a Principal Hydrogeologist and the Manager of Operations for the Southwest Region at LFR. Mr. Cross has 15 years of experience in groundwater resource evaluation and resource

damage assessment, hazardous waste investigation, soil and groundwater characterization and remediation, environmental assessment, and regulatory compliance. Mr. Cross is experienced in local to basin-wide characterization of groundwater flow systems, field investigative methods, data analysis, remediation, litigation support, project management, and report preparation. Specific areas of expertise include hydrogeology, stratigraphy, sedimentology; and geochemistry including organic and inorganic transport and fate analysis.

Natural Resources Defense Council 38
reports published between 1998-2004,

reflecting the latest available monitor

ing data; Peabody’s Annual 1-lydrological Data Reports from 2000-2004,

reflecting Peabody’s monitoring data

during the calendar year and including

summary data from previous years;

and OSMRE’s annual reviews of both

USGS and Peabody’s annual reports,

which determine if available Peabody

and USGS data indicate material dam

age has occurred as a result of Peabody’s

N-aquifer water use.

‘The following discussion of material

damage criteria is largely based on LFR

Levine-Fricke-Revon, “Evaluation of

Cumulative Hydrologic Impacts on the

N-Aquifer, Black Mesa Area, Arizona,”

September 2000 (prepared for NRI)C

and appended to the Drawdown

report); and LFR Levine-Fricke,“Report: Update of the CHIA Criteria

Evaluation for Peabody Western Coal

Company Groundwater Withdraw

als from the N-Aquifer, Black Mesa,

Arizona,” March 2006 (prepared for

NRDC and appended to this report).

Office of Surface Mining “Reclama

tion and Enforcement, Cumulative

Hydrologic Impact Assessment of the

Peabody Coal Company Black Mesa/

Kayenta Mine,” Jan. 1988, p. 5-11.

See the U.S. Geological Survey’s

“Ground-water, Surface-water, and

Water-chemistry Data, Black Mesa

Area, Northeastern Arizona—2003-

04,” Sept. 2004; and the Office of

Surface Mining Reclamation and

Enforcement, Report on Its Review

and Analysis of Peabody Western CoalCompany’s 2004 “Annual Hydrological

Data Report” and The U.S. Geological

Survey’s “Ground-water, Surface-water,

and Water-chemistry Data, Black Mesa

Area, Northeastern Arizona—2003-

04,” Aug. 2005.

Office of Surface Mining Reclama

tion and Enforcement, “Cumulative

Hydrologic Impact Assessment of the

Peabody Coal Company Black Mesa?

Kayenra Mine,” Jan. 1988, p. 5-i I.

‘The Office of Surface Mining

Reclamation and Enforcement, Report

on Its Review and Analysis of Peabody

Western Coal Company’s 2004

“Annual Hydrological Data Report”

and the U.S. Geological Survey’s

on Its Review and Analysis of Peabody

Western Coal Company’s “1996

Annual Hydrological Report—Black

Mesa and Kayenta Mines” and the U.S.

Geological Survey’s “Ground-Water,

Surface-Water, and Water-Chemistry

Data. Black Mesa Area, Northeastern

Arizona—I 996,” “Ground-Water,

Surface-Water, and Water-Chemistry

Data, Black Mesa Area. Northeastern

Arizona—1995,” “Results of Ground

water, Surface-Water, and Water”

Chemistry Monitoring, Black Mesa

Area, Northeastern Ariwna—1994,”

“Results of Ground-Water, SurfaceWater, and Water-Quality Monitor

ing, Black Mesa Area. Northeastern

Arizona—1992—93” (June 1998), pp.

7—9; Report on Its Review of Analysis

of Peabody Western Coal Company’s

1992 “Hydrological Data Report” and

the U.S. Geological Survey’s “Results

of Ground-Water, Surface-Water and

Water-Quality Monitoring, Black Mesa

Area. Northeastern Arizona—1991—

92” (March 1994), pp. 6—8; Report

on Its Review and Analysis of Peabody

Coal Company’s 1991 “Hydrological

Data Report” and the U.S. Geological

Survey’s “Results of Ground-Water,

Surface-Water, and Water-Qual

ity Monitoring, Black Mesa Area,

Northeastern Arizona—I 990—91”

(June 1993), pp. 6—8; Review and Analysis of Peabody Coal Company’s

1990 “Hydrological Data Report” and

the U.S. Geological Survey’s “Results

of Ground-Water, Surface-Water, and

Water-Quality Monitoring, Black Mesa

Area, Northeastern Arizona—I989-

90” (December 1992), pp. 5—6.

‘The U.S. Geological Survey’s “Ground

Water, Surface-Water, and Water-Chem

isuy Data, Black Mesa Area, North

eastern Arizona—2003-04,” September

2004 p. 35-36 (Table 15).

15 LFR Levine-Fricke, “Report: Update

of the CHIA Criteria Evaluation for

Peabody Western Coal CompanyGroundwater Withdrawals from the

N-Aquifer, Black Mesa, Arizona,”

2006, p. 10.

See the Office of Surface Mining

Reclamation and Enforcement, Report

on its Review and Analysis of Peabody

Western Coal Company’s 2004

“Annual Hydrological Data Report”and the U.S. Geological Survey’s

N-Aquifer. Black Mesa, Arizona,”

2006. p. 10-11.

“LFR Levine-Fricke, “Reporc: Update

of the CHIA Criteria Evaluation for

Peabody Western Coal Company

Groundwater Withdrawals from the

N-Aquifer, Black Mesa, Arizona,”2006, p. Ii.

t4 LFR Levine-Fricke, “Report: Update

ofthe CHIA Criteria Evaluation for

Peabody Western Coal CompanyGroundwater Withdrawals from the

N-Aquifer, Black Mesa, Arizona,” 2006

p. 11.

IS LFR Levine-Fricke. “Report: Update

of the Cl-hA Criteria Evaluation for

Peabody Western Coal Company

Groundwater Withdrawals from the

N-Aquifer, Black Mesa, Arizona,”

2006, p. 11.

u Memorandum from Masud Ui Za

man, Director of Water Management

Department, to Mike Nelson, Staff

Assistant of Office of the Chairman!

Vice-Chairman, Evaluation and Analy

sis of Peabody Coal’s Groundwater

Withdrawals and Recommendations

Pertinent to Full Exercise of the Navajo

Water Code (Ocr. 4, 1984).

7 Memorandum from Masud Uz Za

man, Director of Water Management

Department, to Mike Nelson, Staff

Assistant of Office ofthe Chairman!

Vice-Chairman, Evaluation and Analy

sis of Peabody Coal’s Groundwater

Withdrawals and Recommendations

Pertinent to Full Exercise of the Navajo

Water Code (Oct. 4, 1984).

lB Memorandum from Masud Uz Za

man, Director of Water Management

Department, to Mike Nelson, Staff

Assistant of Office of the Chairman?

Vice-Chairman, Evaluation and Analy

sis of Peabody Coal’s Groundwater

Withdrawals and Recommendations

Pertinent to Full Exercise of the Navajo

Water Code (Oct. 4, 1984).

“Office of Surface Mining Reclama

tion and Enforcement, Cumulative

Hydrologic Impact Statement, pp.

5-6, 5-lI.

‘°Al monitored springs at Den

nehotso and Hard Rocks are reported

to have increased in flow, data in both

cases are questionable. The baseline

discharge of Hard Rocks Spring has

° The Office of Surfacr Mining

Reclamation and Enforcements, 2005,Report on its Review And Analysis

of Peabody Western Coal Company’s

2004 “Annual Hydrological Data Report” and the U.S. Geological Survey’s

“Ground-Water, Surface.Warer, And

Water-Chemistry Data. Black Mesa

Area, Northeastern Arizona-—-2003-

04” (August), p. 9.

See LFR Levine-Fricke, “Report: Up

date of the CHIA Criteria Evaluation

for Peabody Western Coal Company

Groundwater Withdrawals from the

N-Aquifer, Black Mesa, Arizona,” pp.

11-13.

The Office of Surface Mining

Reclamation and Enforcements, 2005

Report On Its Review And Analysis

of Peabody Western Coal Company’s

2004 “Annual Hydrological Data Re

port” and the U.S. Geological Survey’s

“Ground-Water, Surface-Water, And

Water-Chemistry Data, Black MessArea, Northeastern Arizona—2003-

04,” August, Appendix G.

t4See LFR Levine-Fricke, “Report: Up

date of the CHIA Criteria Evaluationfor Peabody Western Coal Company

Groundwater Withdrawals from the

N-Aquifer, Black Mesa, Arizona,” pp.

11-13.

See the discussion of Black Mesa

hydrogeology in “Evaluation of

Cumulative Hydrologic Impacts on

the N-Aquifer,” appended to this

report (citing Survey records); Foster

Associates, Inc., Study ofAlternarivet to

Transport CoaL p. E-9 (reporting 1993

study).

Th See CHIA Criteria Section 6.2.2.4.

t7Truini, M. andT.J. Porter, 2005,

“Ground-Water, Surface-Water, and

Water-Chemistry Data, Black Mesa

Area, Northeastern Arizona—2003-

2004.”

‘5Truini, M. andT.J. Porter, 2005,

“Ground-Water, Surface-Water, and

Water-Chemistry Data, Black Mesa

Area, Northeastern Arizona——2003-

2004”: U.S. Geologic Survey Open

File Report 2005-1080.

° The Office of Surface Mining

Reclamation and Enforcement, Report

on its Review and Analysis of Peabody

Western Coal Company’s 2003 “Annual

Natural Resources Defense Council 39
Again, see our earlier discussion of

OSMRE’s material damage criteria in“Signs of Decline,” which appears in

Chapter 1 of the Drawdown report,

and LFR Levine-Fricke “Report: Update of tlse CHIA Criteria Evaluation

for Peabody Western Coal Company

Groundwater Withdrawals from the

N-Aquifer, Black Mesa, Arizona.”

Compare Office of Surface Mining

Reclamation and Enforcement Western

Regional Coordinating Center, Reporton its Review and Analysis (2000), pp. 9—10 with Table 3 in the Drawdown

report; the Office of Surface Mining

Reclamation and Enforcements, 2005,

Report on its Review and Analysis of

Peabody Western Coal Company’s

2004 “Annual Hydrological Data Re

port”; and the U.S. Geological Survey’s

“Ground-Water, Surface-Water, and

Water-Chemistry Data, Black Mesa

Area, Northeastern Arizona—2003-

04” (2005), p. 9.

Office of Surface Mining Reclama

tion and Enforcement, Cumulative

Hydrologic Impact Assessment p. 3-36(citing the USGS model as presented

in J.H. Eyclianer, “Simulation of Five

Ground-Water Withdrawal Projections

for the Black Mesa Area, Navajo andHopi Indian Reservations, Arizona,”

1983 (USGS Water Resources Inves

tigations Report 83-4000)). The Final

Environmental Impact Statement

prepared for Peabody’s life-of-themine permit sets an even estimate of

recharge: between 13,000 and 16,000

acre-fact per year. See the Office ofSurface Mining Reclamation and

Enforcement, Proposed Permit Ap

plication FEIS, vol. 1, p. 111-4.

u See letter from William D. Nichols

to Chief ofshe Office of Groundwater

(Oct. 28, 1993), pp. 3—4. Nicholsnotes that Brown and Eychaner, who

conducted the initial studies of the Naquifer, relied on estimates of precipita

tion levels of 18 inches in the Shonto

area and less than 12 inches in most

outcrop areas. They then estimated recharge to be 3 percent of the 18 inches

near Shonto, and 1 percent of the 12

inches elsewhere. As Nichols points

out, however, a map mean annualprecipitation far 1931—1 960 published

by the State ofArizona shows that the

Followings critique by William

0. Nichols, of the USGS Water

Resources Department, researchers

Thomas J. Lopcs and John P. Hoffman

recalibrated the recharge rate for the

all-important Shonto region. See letterfrom William D. Nichols to Chief of

the Office of Groundwater (Oct. 28,

1993), pp. 2—4; Lopes and Hoffman,

“Geochemical Analyses,” p. 30.

See Lopes and Hoffman, “Geo

chemical Analyses.” p. 7; Levine

Fricke-Recon. “Evaluation of Impacts

of Groundwater Pumping,” p.7.

3C.V. ‘Iheis, “The Source of Water

Derived from Wells: Essential Factors

Controlling the Response of an Aquifer

to Development,’ Civil Engineering, 10

(1940), p. 277.

Letter from William 0. Nichols to

Chief of the Office of Groundwater

(Oct. 28, 1993), p. 3.

Letter from William D. Nichols to

Chief ofthe Office of Groundwater

(Oct. 28, 1993), P. 4.

‘2002 Mining Application, Chapter

18 p. 39 (“the models are not ofsuf

ficient resolution to simulate flow at

individual springs.. .

“Cumulative Hydrogeologic Impact

Assessment of Peabody Coal Company

Black Mesa Mine/Kayenta Mine,” 1989.

41 Drawdown p. 24.

“See Kuhnel and Cross, “A Technical

Review of’A Three-Dimensional Flow

Model of the 0 and

N Aquifers’”

prepared by HIS Geotrans and Water

stone, for the Peabody Western Coal

Company, Sept. 1999 (LFR 2002).

2002 Mining Application, Chapter

18. p. 46.

“2002 Mining Application, Chapter

18, p. 46.

“2002 Mining Application, Chapter

18, p, 39 (“the models are not ofsuf

ficient resolution to simulate flow at

individual springs.. . “).

46Truinj, M. andT.J Porter, 2005,

“Ground-Water, Surface-Water, andWater-Chemistry Data, Black Mesa

Area, Northeastern Arizona—2003-

2004,” U.S. Geologic Survey Open File

Report 2005-1080.

“U.S. Geological Survey’s “GroundWater, Surface-Water, and WaterChemistry Data, Black Mesa Area.

Northeastern Arizona—2003-04,”

Sept. 2004, p. 3.

Grand Canyon Trust, Inc. cc al. v.

Southern California Edison Co. et al.,

United States District Court, District

of Nevada Judicial District, Case No.

CV-S-98-00305-LDG (RJJ).

Miguel Bustillo, Edison to Shut

Down Polluting Coal Plant, Los Angeles

Times. Dec. 30, 2005.

Grand Canyon Trust, Inc. et al. v,

Southern California Edison Co. et al.,

United States District Court, District

of Nevada Judicial District, Case No.

CV-S-98-00305-LDG (RJJ).

Grand Canyon Trust, Inc. et al v.

Southern California Edison Co. et al..United States District Court, District

of Nevada Judicial District, Case No.CV-S-98-00305-LDG (RJJ).

‘ Daniel Kraker, The End of an Era on

the Colorado Plateau, High Country

News. Vol. 38, No, 1, Jan. 23, 2006.SS Black Mesa Mine Permanent

Program Permit and Kayenta MinePermanent Program Permit AZ-000ID

(Feb. 12, 2004) (submitted to Mr.

Jerry Gavette, OSMRE)

Peabody February 12, 2004 letter p. 3.

u NRDC comment letter to OSMRE

on April 26, 2002, citing USGS

regional monitoring reports and relying

on data published therein.

There is simply not enough evidence

in the record to support Peabody’s

assumption that an alternative watersource is available. In fact, what evi

dence does exist points to the significantpotential for C-aquifer withdrawals to

upset the local hydrological balance.OSMRE has previously found the

C-aquifer not to be a viable option.See Drawdown Chapter 1, footnote

11. This finding is further supported

by the dependence of the burgeoning

populations of the Coconino Plateau

on the C-aquifer—from Flagstaff to

Tusayan—which increasingly rely on the

C-aquifer to fulfill their water needs.

Peabody acknowledges that “[tjhe

existing Navajo aquifer welifield would

g 

t

at C

aquifer water would

be available, Peabody does not define

“emergency use.” See Peabody Feb. 12,

2004 letter, p. 4.

Black Mesa and Kayenta Life-ofMine Plan Extension (hereinafter

“2004 Plan Extension”), p. 5.

SI Phases I and II of the government’s

study appear under the tides: Foster

Associates, Inc., Errol Montgomery

& Associates, and Ryley, Carlock &

Applewhite, “Phase I Final Report:Study of Alternatives to Transport

Coal from the Black Mesa Mine

to the Mohave Power GeneratingStation,” Dec. 22, 1992 (literature

review produced by consultants tothe Interior Department): “Phase II

Final Report: Study of Alternatives to

Transport Coal from the Black MesaMine to the Mohave Power Generating

Station,” Nov. 17, 1993 (first half

of alternatives analysis produced by

consultants to the Interior Department); and Environmental Protection

Agency Region IX, “EPA Comments:

DEIS on Proposed Permit Application,Black Mesa-Kayenta Mine, Navajo and

Hopi Indian Reservations, Arizona,”Sept. 1989, pp. 2—3 (attached to letter

from Deanna M. Wiesnan, Director of

External Alfairs for EPA Region IX, to

Peter A. Rutledge, Chief of OSMRE’s

Federal Programs Division, Sept. 14,

1989). See also Bureau of Indian Af

furs, Memorandum from BIA Acting

Deputy to the Assistant Secretary ofIndian Affairs so the Office of Surface

Mining Reclamation and Enforce

ment’s Western Field Operations, Sept.

18, 1989, p. 1 (on the “Draft Environ

mental Impact Statement (DEIS) for

the Proposed Permit Application, Black

Mesa-Kayenra Mine, Navajo and HopiReservations, Arizona”).

u 42 U.S.C. 4321 et seq.

“Drawdown p.31.

“See United States Code 42(1998):

S 1424.

Natural Resources Defense Council 40