Environmental assessment of remedial action at the Riverton uranium mill tailings site, Riverton, Wyoming. Volume I: Text

This document assesses and compares the environmental impacts of various alternatives for remedial action at the Riverton uranium mill tailings site located 2 miles southwest of Riverton, Wyoming. The site covers 173 acres and contains 70 acres of tailings and several of the original mill structures. The Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA), Public Law 95-604, authorizes the US Department of Energy to clean up the site to reduce the potential health impacts associated with the residual radioactive materials remaining at the site and at associated properties off the site. The US Environmental Protection Agency promulgated standards for the remedial actions. Remedial actions must be performed in accordance with these standards and with the concurrence of the Nuclear Regulatory Commission. The preferred alternative is to stabilize the tailings at their present location by consolidating the tailings and associated contaminated soils into a recontoured pile. A radon barrier of compacted earth would be constructed over the pile, and various erosion control measures would be taken to assure the long-term stability of the pile. An underground bentonite slurry wall would be constructed around the perimeter of the stabilized pile to minimize additional groundwater contamination. Another alternative which would involve moving the tailings to a new location is also assessed in this document. This alternative would generally involve greater short-term impacts and costs but would result in stabilization of the tailings at a more remote location. The no action alternative is also assessed in this document. 105 refs., 24 figs., 16 tabs