Blacktail Creek and Confluence Area
- Mining waste, tailings, contaminated soils, and in-stream sediments will be disposed of at an acceptable repository, provided by Atlantic Richfield Company and approved by EPA and MDEQ, outside of the Silver Bow Creek and Blacktail Creek corridors.
- Municipal waste, household waste, timbers, and other construction debris not suitable for re-use will be disposed of at an appropriately permitted facility.
- The BTL will be modified or expanded to provide sufficient capacity to treat additional groundwater captured from the Blacktail Creek area.
Remedial Construction Activities
The area where Blacktail and Silver Bow Creeks meet today has been impacted by past activities that disposed of mining, milling, smelting, and other wastes in the creek corridor area. However, Blacktail Creek and its tributaries continue to provide a natural source of freshwater flowing from the mountains into Silver Bow Creek.
The remedy for this area will remove tailings, wastes, and contaminated soils from Blacktail Creek and the confluence area, reconstruct the creek channel, and revegetate the surrounding land. Groundwater controls will be installed to prevent contaminated groundwater from discharging to and adversely affecting surface water. The remedial construction activities will be performed in part by Atlantic Richfield Company (groundwater controls) and in part by the state of Montana through MDEQ (waste removal and stream reconstruction). The activities will include:
Atlantic Richfield Company will install an underground system to capture contaminated groundwater and prevent groundwater from discharging to and adversely affecting Blacktail and Silver Bow Creeks. This captured groundwater will be transported to the Butte Treatment Lagoons (BTL). At the BTL, metal contaminants will be removed, and clean water will be discharged to Silver Bow Creek.
Excavation & Disposal
MDEQ will excavate tailings, wastes, and contaminated soils along Blacktail Creek and near its confluence with Silver Bow Creek. All excavated wastes will be disposed of in an acceptable repository, provided by Atlantic Richfield Company and approved by EPA and MDEQ. The final depth of excavation will be determined during the design phase of the project. The proposed work in the confluence area will be considered as an integrated restoration and remedy activity.
Following excavation work, MDEQ will reconstruct Blacktail Creek and the confluence area. Blacktail Creek will be reconstructed within a riparian floodplain south of the Ulrich-Schotte Nature Trail, while Silver Bow Creek will be reconstructed near its existing alignment, north of George Street.
End Land Use
The project area will be reconstructed in a manner that enables future community use of the site. Atlantic Richfield Company, Butte-Silver Bow, EPA, and MDEQ will work with the residents of Butte to develop an end land use that is compatible with the remedy.