Reclamation of abandoned or inactive hardrock mine sites on public and private land in the western United States often involves developing a strategy for managing acid mine drainage (AMD) discharges. At many of these mine sites, there are no viable potentially responsible parties associated with the past mining operation. Remediation of water contamination at these legacy sites has commonly included water treatment facilities. Construction, operation, and maintenance of large scale, electric-powered treatment plants, is becoming increasingly difficult due to the remote locations of many mines, funding constraints associated with perpetual treatment, and long-term ownership issues. In recent years, there has been increasing research related to the feasibility of source-control measures to mitigate the impacts from discharging AMD. Source control refers to controlling the inflow of groundwater into underground workings or open pits and/or controlling the outflow of mine drainage from the workings. Controlling inflow can involve separation of “clean” and contaminated surface water, groundwater, or mine water, or reduction of groundwater inflow by grouting to reduce what has to be treated. Source control can also involve bulkhead installation in underground adits and tunnels to re-establish pre-mining groundwater levels. Experience with source control methods is growing and much is being learned re: which mine sites are suitable for this approach; appropriate hydrologic characterization tools and post closure monitoring.
Attendees to this session will be better able to:
- Learn about alternatives to traditional ARD treatment
- Learn about the Reclamation of abandoned or inactive hardrock mine sites