Description: Two mine openings were combined into one pipe to treat the discharges with an anoxic limestone drain. Unfortunately about two years after construction the system began to fail due to a significant change in water chemistry. In the fall of 2002 the existing system underwent a significant modification into a vertical flow system and has since been operating properly. In addition a 300 foot section of stream had additional limestone placed within the channel to add alkalinity to the watershed. The system includes an initial sediment basin, a vertical flow treatment pond and a final settling basin. The post treatment water quality data is reflective of the average water chemistry observed since 2003.