Uncontrolled surface flow areas

REMEDIAL CONSTRUCTION ACTIVITIES

Under the remedy, most of the stormwater impacted by historic mining will be captured and will be managed in existing stormwater best management practices (BMPs) controls and by additional stormwater BMPs proposed at other locations throughout Butte, including Diggings East, Northside Tailings, Buffalo Gulch, and Grove Gulch. Under the remedy, areas remaining outside the influence of these BMP projects will be evaluated to assess the potential impact of historic mining sources in those areas on surface water quality in Silver Bow and Blacktail Creeks, and additional BMPs will be constructed in these remaining areas to improve water quality in the creeks.

Site Evaluations 

Atlantic Richfield Company will evaluate the remaining areas where stormwater is not captured in existing or proposed BMPs and may drain to Blacktail and Silver Bow Creeks to determine whether these areas have been impacted by historic mining activities and if they contribute to the degradation of surface water quality.

Remedial Action

If an area is determined to be contributing contaminants of concern and impacting Blacktail Creek or Silver Bow Creek water quality, an appropriately sized BMP will be proposed. A work plan will be developed detailing where and how the BMPs will be constructed to reduce or prevent contaminated stormwater and sediments from reaching Blacktail and Silver Bow Creeks. Following construction, each BMP will be integrated into the stormwater operation and maintenance program for BPSOU.