Grove Gulch is one of several gulches in Butte that may have been used to dispose of milling and mineral processing wastes, allowing that material to flow down the drainage and into Blacktail Creek. The proposed remedy would include construction of a sedimentation bay and vegetated swale to reduce the amount of contaminated sediment and metals that reach Blacktail Creek and thereby improve the quality of water in the creek. The proposed remedial construction activities would be performed by Atlantic Richfield Company and would include:
Excavation and Disposal – Any tailings, wastes, or contaminated soils found beneath the footprint of the sedimentation bay and vegetated swale would be excavated and hauled to a repository. Some excavated materials, including clean topsoil, may be reused to complete reconstruction of the site.
Sedimentation Bay and Vegetated Swale – A sedimentation bay and vegetated swale would be installed parallel to Lexington Avenue, just south of I-15/90, and capture stormwater from the Grove Gulch drainage. Maintenance of the bay would include removal of captured sediments and disposal of the sediments at a repository.
Final Condition – All areas disturbed during construction activities would be regraded and vegetated. For maintenance purposes, an access road and turnaround area may be constructed.
Mining waste, tailings, and contaminated soils that may be found would be removed and taken to an approved repository outside of the Silver Bow Creek and Blacktail Creek corridors.
Municipal waste, household waste, timbers, and other construction debris not suitable for re-use, if found, would be disposed of at an appropriately permitted facility.
The stormwater sedimentation bay would be sized to capture the 6-month, 24-hour Type I Soil Conservation Service (SCS) design storm.
Additional storage volume would be provided for management of accumulated sediments.