Abstract
The Blackbird Mine Site is in the Northwest United States, in east central Idaho. This legacy mine site operated between 1948 and 1967 and although never mined by Glencore the site is currently under their ownership. Before mining, downstream Panther Creek supported healthy populations of anadromous salmon and steelhead. Lack of environmental stewardship during historic mining operations resulted in the release of metals to surface water and sediments causing the elimination of the fish populations in Panther Creek. Upon implementation of remediation actions, including source control measures, water collection and water treatment improvements, downstream water quality improved significantly. This paper reviews the adaptive management approach to move this legacy site from initial characterization into remedial design and implementation through a changing regulatory framework and evolving clean-up criteria. Site characterization and remediation included traditional approaches of time-critical and early action activities while the study advanced through remedial investigations and feasibility studies and ultimately to remedial action implementation. This approach allowed an early and significant improvement in water quality and source management as well as allowed time to understand the impact of the remediation measures and to evaluate progress and continued refinement of additional actions required to move the site towards care and maintenance. Through the remediation, project-specific actions were implemented, including the use of sub surface workings to improve storage and treatment efficiency and the implementation of in-stream stabilization to minimize mobilization of mine-impacted sediments. Performance monitoring has shown 98 to 99% reductions of metals concentrations in surface water and in-stream sediment concentrations allowing full recovery of the ecosystem in Panther Creek.