Formation personnel conducted the Remedial Investigation and Feasibility Study (RI/FS) for the Butte Priority Soils (BPS) Operable Unit of the Silver Bow Creek/Butte Area Superfund site. The BPS Operable Unit is a large, complex mining site with commingled residential and industrial areas and associated human health and ecological risk issues. The RI characterized the distribution of metal contaminants of concern in soil and over 100 residual mine waste piles and described transport of metals to alluvial groundwater and surface water.
The preferred alternative included operation and maintenance of capped mine waste accumulations, collection and treatment of groundwater, and storm water controls to reduce particulate metal loads to local streams. Removal actions conducted prior to and during the RI/FS were evaluated and found to be consistent with the preferred remedial alternative identified in the FS thereby eliminating the need to rework these previously addressed areas.
Formation personnel were continuously involved in the RI/FS efforts, which commenced in 1992 and successfully concluded in 2004. Formation continues to provide technical assistance at the BPS Operable Unit.
Formation is supporting its client in the evaluation and optimization of an alluvial groundwater capture and treatment system, which is part of remedy selected for the Butte Priority Soils Operable Unit. The groundwater extraction system supports remedial goals by capturing groundwater prior to discharge to a nearby river. Formation applies MODFLOW and MODPATH to evaluate the hydrologic effects of nearby ponds on the efficiency of the groundwater extraction system.