Accessing Abandoned Mine Drainage sites for possible construction of treatment systems involves analyzing four basic criteria: water chemistry, flow rate, available land, and financial/in-kind resources. Treatment methods to address AMD focus on neutralizing, isolating, stabilizing and/or removing problem pollutants through various chemical, physical, and biological processes. There are two basic types of treatment systems. Active treatment involves that addition of alkaline chemicals such as lime, soda ash, or ammonia, with the contaminated drainage to decrease its acidity and speed up the removal of metals. Passive systems clean contaminants from mine drainage by exposing it to air, limestone, cattails, and other vegetation that form carefully designed components of ponds, neutralizing ditches, buried channels, and wetlands.

Cover title. Prepared by Tetra Tech, Inc. under EPA contract #EPA-903-K-97-003. Includes bibliographical references. "EPA-903-K-97-003." "September 1997."