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. Mississippian-aged limestone layers act to buffer the hazardous AMD thus reducing the risk. Five such units were analyzed over a range of four aggregate sizes (Very Fine Gravel, Fine Gravel, Coarse Gravel, and Very Coarse Gravel). As the mean aggregate size decreases, the buffering potential increases. The natural stratigraphy aids in neutralizing the AMD, but natural ground-water flow rates may limit this effect. Neutralization is also hampered by a finite reduction in buffering potential due to repeat exposure. Also, limestone aggregate may be utilized as a control measure for AMD produced in surficial settings such as spoil piles and tailings ponds.