The Site is located in west-central Montana just south of the town of East Helena, in Lewis and Clark County. Lead and zinc smelting activities began at this location in 1888 and continued until April 2001. In September of 1984, the U. S. Environmental Protection Agency (EPA) added the Site to its National Priorities List of uncontrolled hazardous waste sites. American Smelting and Refining Company (ASARCO) operated the smelter to produce lead bullion and zinc oxide. Byproducts of the operation included sulfuric acid, matte (iron, copper, and lead oxides), and speiss (copper arsenides and antimodes). Prior to the 1970s, non-contact cooling water was continuously discharged into Prickly Pear Creek at a rate of over 2 million gallons per day. Effluent from washing of the speiss, as well as other process water, was also released into Prickly Pear Creek. In 1975, ASARCO ceased discharging effluent into Prickly Pear Creek (Montana Department of Health and Environmental Sciences, 1981). Aerial emissions from the smelting activities caused widespread contamination of the Helena Valley. Hazardous substances released at and from the site include arsenic, cadmium, copper, mercury, lead, selenium, and zinc. These contaminants have been identified as hazardous substances (40 CFR Part 302; Table 302.4; ) and are included in the definition of hazardous substances under § 9601 (14).
EPA’s Remedial Investigation for the Site found soil lead concentrations exceeding concentrations known to be toxic to natural resources, including migratory birds. The Supplemental Ecological Risk Assessment for the Site states that soil lead concentrations exceeding 650 mg/kg may adversely impact passerine insectivores (EPA, 2005). Cadmium and copper concentrations in site soils also exceeded the Ecological Soil Screening Levels. Based on these sampling results, the U.S. Fish and Wildlife Service (Service), through the Natural Resource Damage Assessment and Restoration (NRDAR) process, determined that 427 acres of land in and around the Site had lead concentrations high enough to injure migratory birds relying on those impacted grasslands (which include the East Fields, Dartman Fields and Lamping fields).
The United States, on behalf of the Department of Interior (DOI), settled potential claims for NRDAR at the Site with ASARCO. The East Helena NRDAR settlement was part of the 2009 ASARCO bankruptcy settlement, and ASARCO paid $706,000 to resolve its potential NRDAR liability to DOI at the Site. The Service released a draft Restoration Plan and Environmental Assessment (RP/EA) for public review on August 22, 2019 that proposed restoration alternatives funded by the 2009 settlement designed to restore grassland and riparian habitats with an intact composition, structure, and functionality capable of supporting migratory bird species. Specifically, the selected restoration alternative includes reshaping and revegetating an 80-acre parcel located along Prickly Pear Creek in East Helena, Lewis and Clark County, Montana. This project would occur after the completion of clean-up activities, which would consist of contaminated soil removal, mixing, and grading. The selected restoration project will enhance wetland, and create and enhance floodplain, and grassland habitats suitable for a variety of migratory bird species. It will expand floodplain near Prickly Pear Creek to increase the area of ephemeral wetlands and to provide a greater diversity of habitat than currently exists for migratory bird use.
The public comment period closed on September 22, 2019, and the Service updated the draft RP/EA to address the comments received. The Service finalized the RP/EA during January 2020 and will develop a monitoring plan to evaluate the long-term impacts of the planned restoration actions. Restoration activities are planned to begin during the Fall 2020.