The Effectiveness of Acid Rock Drainage Control Strategies at the Summitville Mine

摘要

The Summitville Mine, located in Southwestern Colorado, is an abandoned open pit and underground gold mine. During recent open pit mining, the volume of acidic metal laden water released from the site significantly increased. This was attributed to development of the mine pits, development of the waste rock piles, and increased discharges from the drainage adit. The release of acid rock drainage from the site resulted in the destruction of the aquatic ecosystem for more than twenty miles downstream. Beginning in 1993, plans were implemented to reduce the amount of acid rock drainage from the mine. The goal of these activities is to reduce the need for long term treatment to control metals released from the site. The majority of this stabilization work has been completed. The work implemented includes extensive removal of waste rock and tailings, backfilling and capping of the mine pits, and plugging of two drainage adits. In the interim, chemical treatment is being utilized to reduce metal loading. The remaining phases of site stabilization work, including reclamation of the mine site, are planned to be completed in 2000. This study discusses actions taken to reduce the amount of acid rock drainage generated and released from the Summitville Mine, the cost of these actions, and the corresponding reduction in metal loading. Copper loading is analyzed as an indicator of the effectiveness of the actions taken to control acid rock drainage. The monitoring of copper at the downstream compliance point indicates an overall seventy percent reduction in metal loads released from the site. Reclamation is predicted to reduce the loads such that little or no water treatment will be necessary to meet water quality goals.