Potential Effects on Ground Water of a Hypothetical Surface Coal Mine in Indiana

The possible mine will remove a gently, less than 50 feet per mile, westerly dipping Springfield coal from an area covered by glacial till and some channel sands and gravel. The area is flat, with less than 20 feet of relief in a square mile. The channel sands and gravels, the till and the bedrock are capable of yielding ground water at 5 to 75,3 to 10, and 1 to 10 gallons per minute (gpm), respectively. The ground water in the drift and the shallow bedrock is calcium-bicarbonate type, contrasting with the sodium-bicarbonate type in the deep bedrock. The surface mine will feature selective handling of overburden. The probable hydrologic consequences of the mine will be 1) a short-term, areally limited dewatering, 2) an increase in dissolved solids, 3) a change in ground water chemistry in some areas to a calcium-bicarbonate sulfate water, 4) an increase in ground water storage, and 5) a new integrated surface water system. The proposed ground water monitoring system will include seven monitoring wells in the glacial material and one in the bedrock. The primary effort in ground water monitoring to the west of the mine will be to detect changes in the quality of the ground water, whereas to the east, changes in both quality and quantity will need to be monitored intensively.