THE EFFECTIVENESS OF IN-SITU LIMESTONE TREATMENT OF ACID-MINE DRAINAGE

Acid mine drainage (AMD) is a common problem in southwestern Missouri and is partly responsible for many contaminated water supplies. Missis sippian-aged limestone layers act to buffer the hazardous AMD thus red ucing the risk. Five such units were analyzed over a range of four agg regate sizes (Very Fine Gravel, Fine Gravel, Coarse Gravel, and Very C oarse Gravel). As the mean aggregate size decreases, the buffering pot ential increases. The natural stratigraphy aids in neutralizing the AM D, but natural ground-water flow rates may limit this effect. Neutrali zation is also hampered by a finite reduction in buffering potential d ue to repeat exposure. Also, limestone aggregate may be utilized as a control measure for AMD produced in surficial settings such as spoil p iles and tailings ponds.