Engineering Assessment of Inactive Uranium Mill Tailings. Canonsburg Site, Canonsburg, Pennsylvania

摘要

Ford, Bacon and Davis Utah Inc. has evaluated the Canonsburg site in order to assess the problems resulting from the existence of radioactive residues at Canonsburg, Pennsylvania. This engineering assessment has included the preparation of topographic maps, radiometric measurements sufficient to determine areas and volumes of tailings and radiation exposures of individuals and nearby populations, the investigations of site hydrology and meteorology, and the evaluation and costing of alternative remedial actions. Radon gas released from the approximately 300,000 tons of tailings and contaminated soil at the Canonsburg site constitutes the most significant environmental impact, although windblown tailings and external gamma radiation also are factors. The four alternative actions presented in this engineering assessment range from millsite and off-site decontamination with the addition of 3 m of stabilization cover material (Option I), to removal of the tailings and contaminated materials to a remote disposal site and decontamination of the Canonsburg site (Options II through IV). Cost estimates for the four options range from $23,244,000 for stabilization in-place, to $27,052,000 for disposal at a distance of about 17 mi. Three principal alternatives for the reprocessing of the Canonsburg tailings were examined: heap leaching; treatment at an existing mill; and reprocessing at a new conventional mill constructed for tailings reprocessing. As required by Public Law 95-604, under whose auspices this project is conducted, the US Department of Energy has solicited expressions of interest in reprocessng the tailings and residues at the Canonsburg site for uranium recovery. Since no such interest was demonstrated, no effort has been made to estimate the value of the residual uranium resource at the Canonsburg site. (ERA citation 07:046019)