The Copper Mountain Sports and Recreation Complex in Butte is situated on top of a Superfund waste repository that serves as an engineered cap. This area is used for a practical purpose to prevent the loss of land to topsoil, gravel, clay, and planted grasses, with fences and signs prohibiting entry.
Last year, the EPA confirmed that seeps discovered on private property below the repository beneath the recreation complex contained metal contaminants.
Reports indicated that seeps from the Clark Tailings Consolidated Waste Management Area were leading to the formation of pools on private property.
Under federal Superfund law, Atlantic Richfield/BP, responsible for managing the repository, announced in late October that they were investigating the waste management area’s performance as per the Butte Priority Soils Consent Decree.
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Atlantic Richfield stated that once the investigation is complete, they will create a site model to guide future remedial designs at the Copper Mountain site.
When The Montana Standard reached out to Atlantic Richfield/BP for an update, they did not respond by the deadline.
The EPA provided a statement from spokeswoman Mackenzie Meter, stating that Atlantic Richfield is actively investigating the Copper Mountain site to assess the impact of seepage on groundwater, soils, and surface waters.
Meter added that EPA anticipates a Phase 1 Data Summary Report from Atlantic Richfield in July 2024, which will support an update to the conceptual site model. As of now, EPA does not have data from Atlantic Richfield to report on findings.
Residents of Butte-Silver Bow County are concerned about the performance of waste management areas, especially given plans to locate repositories for contaminated materials from the Silver Bow Creek Corridor. The Berkeley Pit is a potential candidate.
The Copper Mountain repository, constructed in 1998 without a liner, relies on a cover system to prevent water infiltration. This system includes topsoil, soil, gravel, and clay to redirect water away from the tailings.
Initial data from Butte-Silver Bow County and Montana Technological University strongly suggests that the seeping water from the repository is contaminated with metals.
The repository received approximately 840,000 cubic yards of tailings and metals-impacted soils from the former Colorado Smelter and Lower Area One in Butte. Additional tailings were consolidated from the Clark Mill.
Atlantic Richfield/BP estimates a similar volume of wastes will be excavated from sites in the Silver Bow Creek Corridor, prompting discussions with Butte-Silver Bow about repository locations.
Concerns have been raised by Centerville residents regarding the proximity of proposed repositories and the potential impact on the historic Dublin Gulch neighborhood. Atlantic Richfield/BP has assured that materials will not be dumped near Dublin Gulch.
Regarding the Kelley Mine Area repository, the company explained that design and maintenance of the cover system would prevent water flow to the Berkeley Pit and minimize environmental risks.
Models, studies, and analyses will guide decision-making at the Copper Mountain site, where drilling and sampling operations have been ongoing under EPA oversight.
