Nearly 100 years of copper smelter operations and emissions at the Anaconda Smelter Superfund site left approximately 10,000 acres barren or sparsely vegetated, leaving dust problems and transport of contaminants of concern (COCs) to surface water and groundwater receptors. Early on in the planning process, it was recognized that whole-scale removal of the COCs (arsenic, copper, lead, zinc, and cadmium) was impracticable and infeasible. In situ treatment of soils and wastes, using alkaline amendments to raise pH and immobilize metals, was developed to re-establish vegetation. Methods to assess ecological dysfunction and assign remedial actions, treatability studies and demonstration plots were all developed in the 1980s and 1990s, resulting in remedial actions beginning in the late 1990s. As work is completed, more information was gained from the results. While much of the revegetation work was successful, other areas were not, particularly in those areas close to the former smelters where COC concentrations in soil were much higher.
EPA identified phytotoxicity concerns in certain areas during the 2010 Five Year Review. EPA and the responsible party collaboratively conducted a study evaluating plant growth in remediated areas while looking at several factors such as COC levels in soil. This evaluation led to development of a total metal index for soil based on the probable success of reclamation grass species. Using this information, EPA and the responsible party revised the existing vegetation management plan for the site to allow for voluntary remediation to achieve higher levels of cleanup to allow unrestrictive land use (e.g., with no long-term O&M requirements). This represents a win-win for the landowner, the responsible party, and the regulatory agencies.
This webinar will review the results of over 20 years of remedial activities at the Anaconda Smelter site, and how the knowledge gained from this work has been used to develop better cleanup that satisfies all party involved.