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Cumulative potential hydrologic impacts of surface coal mining in the eastern Powder River structural basin, northeastern Wyoming

Water-Resources Investigations Report 88-4046

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Abstract

There are 16 existing and six proposed surface coal mines in the eastern Powder River structural basin of northeastern Wyoming. Coal mining companies predict water level declines of 5 ft or more in the Wasatch aquifer to extend form about 1,000 to about 2,000 ft beyond the mine pits. The predicted 5 ft water level decline in the Wyodak coal aquifer generally extends 4-8 mi beyond the lease areas. About 3,000 wells are in the area of potential cumulative water level declines resulting from all anticipated mining. Of these 3,000 wells, about 1,200 are outside the areas of anticipated mining: about 1,000 wells supply water for domestic or livestock uses, and about 200 wells supply water for municipal, industrial, irrigation, and miscellaneous uses. The 1,800 remaining wells are used by coal mining companies. Future surface coal mining probably will result in postmining groundwater of similar quality to that currently present in the study area. By use of geochemical modeling techniques, the results of a hypothetical reaction path exercise indicate the potential for marked improvements in postmining water quality because of chemical reactions as postmining groundwater with a large dissolved solids concentration (3,540 mg/L) moves into a coal aquifer with relatively small dissolved solids concentrations (910 mg/L). Results of the modeling exercise also indicate geochemical conditions that are most ideal for large decreases in dissolved solids concentrations in coal aquifers receiving recharge from a spoil aquifer. (Lantz-PTT)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Cumulative potential hydrologic impacts of surface coal mining in the eastern Powder River structural basin, northeastern Wyoming
Series title:
Water-Resources Investigations Report
Series number:
88-4046
Edition:
-
Year Published:
1988
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
x, 201 p. :ill., maps ;28 cm.