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Blacktail Creek and Confluence Area

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 fresh water flowing from the mountains into Silver Bow Creek.

The proposed remedy for this area would remove tailings, wastes, and contaminated soils from Blacktail Creek and the confluence area, reconstruct the creek channel, and revegetate the surrounding land. Groundwater controls would be installed to prevent contaminated groundwater from discharging to and adversely affecting surface water. The proposed remedial construction activities would 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 would include:

  1. Hydraulic Control – Atlantic Richfield Company would 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 would be transported to the Butte Treatment Lagoons (BTL). At the BTL, metal contaminants would be removed, and clean water would be discharged to Silver Bow Creek.
  2. Excavation and Disposal – MDEQ would excavate tailings, wastes, and contaminated soils along Blacktail Creek and near its confluence with Silver Bow Creek. All excavated wastes would be disposed of in an acceptable repository, provided by Atlantic Richfield Company and approved by EPA and MDEQ. The final depth of excavation would be determined during the design phase of the project. The proposed work in the confluence area would be considered as an integrated restoration and remedy activity.
  3. Stream Reconstruction – Following excavation work, MDEQ would reconstruct Blacktail Creek and the confluence area. Blacktail Creek would be reconstructed within a riparian floodplain south of the Ulrich-Schotte Nature Trail, while Silver Bow Creek would be reconstructed near its existing alignment, north of George Street.
  4. End Land Use – The project area would be reconstructed in a manner that enables future community use of the site. Atlantic Richfield Company, Butte-Silver Bow, EPA, and MDEQ would work with the residents of Butte to develop an end land use that is compatible with the proposed remedy

Site-specific Details:

  • Mining waste, tailings, contaminated soils, and in-stream sediments would 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 would be disposed of at an appropriately permitted facility.
  • The BTL may be modified or expanded to provide suffcient capacity to treat additional groundwater captured from the Blacktail Creek area.
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