Drainage of both active and abandoned surface and underground mines can produce a variety of groundwater pollution problems (Emrich 1969). Rainwater, particularly acid rain, overexposed surface mines, and mine tailings produce highly mineralized runoff frequently referred to as acid mine drainage. This runoff can percolate into the ground and degrade the quality of groundwater. In addition, water seepage through underground mines can leach toxic metals from exposed ores and raw materials and introduce them to groundwater (Barnes and Clarke 1964). Oxidation and leaching connected with coal mining produce high iron and sulfate concentrations and low pH in groundwater (Miller 1980).

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