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Peabody Releases Latest Black Mesa Aquifer Study; Confirms Prior Studies Showing No Significant Harm
ST. LOUIS, Mo., March 22 — Peabody Group today released the latest study performed to analyze water flow in the D- and N-Aquifer systems in northeastern Arizona. The study confirms previous findings that long-term water use will not pose any permanent or significant impacts to the aquifer or other water users.
 
The two-year, $2 million study reaffirms 30 years of research and concludes that using aquifer water to convey coal from the Black Mesa Mine to a Nevada power plant will not significantly affect the integrity of the 7,500 square-mile aquifer or surrounding community water supplies. It also concludes that the potential impacts to springs and streams are too small to be measured and that the aquifer system will significantly recover when the pumping ends.
 
Using more sophisticated computer hardware and software for analyses and incorporating an additional 10 years of data, the investigation represents the 11th major public or private study initiated since 1970 and counters claims by some activist groups that use of the aquifer is causing permanent harm. The study was performed jointly by two leading hydrologic firms and reviewed by an independent expert.
 
Within the Black Mesa basin, the Navajo Aquifer spans an area the size of Delaware and holds more than 400 million acre-feet of water. Comprised of porous sandstone, the aquifer provides storage and serves as a transmitter, allowing water to flow through it toward springs, streams and wells. The aquifer system is replenished naturally through the hydrologic cycle; recharge occurs throughout the basin.
 
The 3-D study incorporates the most accurate tool available to simulate the dynamics and interconnections between the D- and N-Aquifer systems. For the first time, researchers created a 3-D model that independently characterizes the Dakota, Morrison and Entrada formations within the D-Aquifer; the Carmel formation, which separates the two aquifers; and the Navajo, Kayenta and Wingate formations of the N-Aquifer.
 
The science continues to show that mining will use less than one-tenth of 1 percent of the total volume of water stored in the aquifer during the life of the operations, which equates to displacing less than half of a beverage can from a 55 gallon drum.
 
"We used the most extensive data available and developed the best modeling tool yet. The results confirm that the fraction of water used is insignificant when you put the aquifer's vast size into perspective," said Fredrick D. Palmer, executive vice president for legal and external affairs. "The pipeline system continues to be the most environmentally sound way to convey coal to the Mohave power plant." Peabody has committed to participate in discussions regarding alternative water sources to benefit the tribes, as part of the Lower Colorado River Adjudication process.
 
For 30 years, the Black Mesa and Kayenta surface mines have helped provide low-cost electricity to fuel the economic growth of the Southwest in major cities including Los Angeles, Las Vegas and Phoenix. Mining also has encouraged tremendous economic progress in Hopi and Navajo reservation communities by injecting $2 million weekly in direct economic benefits or more than $1.8 billion since mining began. Peabody is one of the largest private employers on American Indian lands, providing nearly 700 jobs at its two surface mines.
 
Each year, Peabody purchases about 3,800 acre-feet of aquifer water from the Hopi Tribe and the Navajo Nation for approximately $3.5 million. Eight deep wells tap into the sandstone and supply water used at the mining complex as well as potable water used by 200 local residents.
 
Peabody Group is the world's largest private-sector coal company. Its coal products fuel 9.5 percent of all U.S. electricity generation and 2.5 percent of worldwide electricity generation.
 
 

Navajo Aquifer Water Studies

In the past 30 years, government and private experts have performed 11 major studies to characterize the Navajo Aquifer and examine the impacts of industrial and municipal water use. These studies confirm that long-term water use will not pose any significant or permanent impacts to the aquifer or other water users and that the aquifer will significantly recover when the pumping ends. Following is a list of major studies.

1999  

A Three-Dimensional Numeric Model of the N and D Aquifers
HIS-GeoTrans, Inc.
Westminster, Colorado
Waterstone Inc.
Boulder, Colorado

1997  

The Responses of the N Aquifer to Paleoclimatic Changes During Late Pleistocene and Holocene, Northeastern Arizona
HIS GeoTrans, Inc.
Boulder, Colorado

1993  

Navajo Aquifer Water Study Database Documentation
Prepared for the Hopi Tribe, the Navajo Nation and Peabody Western
S.S. Papadopulos & Associates Inc.
Bethesda, Maryland

1993   Investigation of the N- and D-Aquifer Geochemistry and Flow Characteristics using Major Ion and Isotopic Chemistry, Petrography, Rock Stress Analyses and Dendrochronology in the Black Mesa Area; Arizona
Prepared for Peabody Western
GeoTrans, Inc.
Boulder, Colorado
1991   Water Use Study for Arizona
Prepared for Peabody Western
GeoTrans, Inc.
Boulder, Colorado
1990   Final Environmental Impact Statement Proposed Permit Application, Black Mesa-Kayenta Mine, Navajo and Hopi Indian Reservations, Arizona
U.S. Department of the Interior
Office of Surface Mining Reclamation and Enforcement
1989   Cumulative Hydrologic Impact Assessment for the Black Mesa-Kayenta Mines
U.S. Department of the Interior Office of Surface Mining Reclamation and Enforcement
1988  

Simulation of Five Ground Water Withdrawal Projections for the Black Mesa Area, Navajo and Hopi Indian Reservations, Arizona
Water Resources Investigations Report, 88-4000, 51 p.
J.G. Brown and J.H. Eychaner
U.S. Geological Survey

1987   A Two-Dimenstional, Finite Difference Flow Model Simulating the Effects of Withdrawals to the N Aquifer, Black Mesa Arizona
GeoTrans, Inc.
Boulder Colorado
1983   Geohydrology and the Effects of Water Use in the Black Mesa Area, Navajo and Hopi Indian Reservations, Arizona
Water Supply Paper 2201, 26 p.
Eychaner, J.H.
U.S. Geological Survey
1972   Environmental Impact Statement
Permit Application, Black Mesa-Kayenta Mine, Navajo and Hopi Indian Reservations, Arizona
U.S. Department of the Interior
Office of Surface Mining Reclamation and Enforcement
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CONTACT:
Beth Sutton928-677-3201bsutton@peabodyenergy.com
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