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R. E. Davis

Publications and source records attributed to R. E. Davis.

8 recordsLinked to original sources
USGS1984

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

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.

Montana↗
USGS1984

Example calculations of possible ground-water inflow to mine pits at the West Decker, East Decker, and proposed North Decker mines, southeastern Montana

Proposed plans to raise the spillway of the Tongue River Dam, Montana, 14 feet would result in an increase in the reservoir stage, which will affect the amount of ground-water inflow from the reservoir to existing and proposed surface coal mine pits near Tongue River Reservoir. Example calculations are based on flow from the reservoir to the mine pits through areas approximately perpendicular to the long axis of the reservoir. The planned increase in the stage of the reservoir will result in an increase of inflow to the mine pits in most areas. The increases will be greatest where the mine pits are near the reservoir and separated from the reservoir solely by aquifer zones of relatively large hydraulic conductivity. However, the inflow determined from the calculations is subject to a large degree of error, owing to the simplified method of calculation and the assumptions used. (USGS)

Water-Resources Investigations Report↗