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Geochemistry and geohydrology of the West Decker and Big Sky coal-mining areas, southeastern Montana

Water-Resources Investigations Report 83-4225

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Abstract

In the West Decker Mine area, water levels west of the mine at post-mining equilibrium may be almost 12 feet higher than pre-mining levels. Dissolved-solids concentration in water from coal aquifers is about 1,400 milligrams per liter and from mine spoils is about 2,500 milligrams per liter. About 13 years will be required for ground water moving at an average velocity of 2 feet per day to flow from the spoils to the Tongue River Reservoir. The increase in dissolved-solids load to the reservoir due to mining will be less than 1 percent. In the Big Sky Mine area, water levels at post-mining equilibrium will closely resemble pre-mining levels. Dissolved-solids concentration in water from coal aquifers is about 2,700 milligrams per liter and from spoils is about 3,700 milligrams per liter. About 36 to 60 years will be required for ground water moving at an average velocity of 1.2 feet per day to flow from the spoils to Rosebud Creek. The average annual increase in dissolved-solids load to the creek due to mining will be about 2 percent, although a greater increase probably will occur during summer months when flow in the creek is low. (USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Geochemistry and geohydrology of the West Decker and Big Sky coal-mining areas, southeastern Montana
Series title:
Water-Resources Investigations Report
Series number:
83-4225
Edition:
-
Year Published:
1984
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
vi, 109 p. :ill., maps ;28 cm.