Characterization of an Acid Mine Drainage Site in Southern Illinois

Two seams at the Tab-Simco abandoned underground coal mine site in southern Illinois were mined intermittently from the 1890’s until 1955, and later surface mined. The stripping operations resulted in several break-ins into the old underground works which were later buried by mine spoil. The resulting mine pool in the lower of the two seams has been producing an average of ~150 m per day of acid mine drainage (AMD) for the past few decades. After exiting through the breakins, the contaminated water flows along discrete pathways through the base of the spoil and emerges as 5 perennial seeps. The AMD has contaminated a nearby stream and has produced a 4 ha “kill zone” within its otherwise forested floodplain. AM production at this site is a result of the interplay among (1) site geology, (2) mine geometry and location, and (3) climate. Limited hydrologic and geochemical data gathered over a 9-month period in 1997 and 1998 suggest that AMD production is strongly influenced by seasonal mine pool elevation changes. These elevation changes may govern the cycles of formation and release of acid sulfate salts (stored acidity) within the underground mine works. Additional