The hydrologic effects of surface coal mining in unlimited areas is difficult to predict, partly because of a lack of adequate data collected before and after mining and reclamation. In order to help provide data to assess the effects of surface mining on the hydrology of small basins in the coal fields of the eastern United States, the U.S. Bureau of Mines sponsored a comprehensive hydrologic study at three sites in the Ohio part of the Eastern Coal Province. These sites are within the unqlaciated part of the Allegheny Plateau, and are representative of similar coal-producing areas in Kentucky, West Virginia, and Pennsylvania. The U.S. Geological Survey was responsible for the ground-water phase of the study.
The aquifer system at each watershed consisted of two localized perched aquifers (top and middle) above a deeper, more regional aquifer. The premining top aquifer was destroyed by mining in each case, and was replaced by spoils during reclamation.
The spoils formed new top aquifers that were slowly becoming resaturated at the end of the study period. Water levels in the aquifers were about the same after reclamation as before mining, although levels rose in a few places. It appears that the underclay at the base of the new top aquifers at all three sites prevents significant downward leakage from the top aquifers to lower except in places where the layer may have been damaged during mining.
Water in the top aquifers is a calcium sulfate type, whereas calcium bicarbonate type water predominated before mining. The median specific conductance of water in the new top aquifers was about 5 times greater than that of the original top aquifers in two of the watersheds, and 1 1/2 times the level of the original top aquifers in the third. Concentrations of dissolved sulfate, iron, and manganese in the top aquifers before mining generally did not exceed U.S. and Ohio Environmental Protection Agency drinking-water limits, but generally exceeded these limits after reclamation. Water-quality changes in the middle aquifers were minor by comparison. Water levels and water quality in the deeper, regional aquifers were unaffected by mining.
Additional publication details
USGS Numbered Series
Effects of surface coal mining and reclamation on ground water in small watersheds in the Allegheny Plateau, Ohio