Uranium mine waste dump characterization in Lathrop Canyon, Canyonlands National Park, Utah

Burghardt, J; Graham, R; Mesch, M; Doolittle, R

The National Park Service (NPS), Utah’s Department of Natural Resources Abandoned Mine Reclamation Program (AMRP), and the U.S. Environmental Protection Agency (EPA) entered into a partnership to develop and implement a sampling procedure to evaluate the environmental risk of abandoned uranium mine waste rock. The NPS and AMRP have worked cooperatively since 1988 to evaluate and close hazardous openings at these sites throughout Utah, but mine waste rock piles at remote sites have often not been reclaimed for reasons such as limited funding, minimizing new impacts, and preserving historic mining fabric. The environmental risks of leaving uranium mine dumps unmitigated have not been fully assessed. EPA contributed funding and expertise to develop a sampling design to evaluate these risks. Representative sites on NPS lands were considered for this study, giving highest priority to those sites where there was evidence of contaminants being released to the environment. Criteria for site selection included size of mine waste rock piles, proximity to ephemeral desert washes, and evidence of waste rock pile erosion. Twelve abandoned uranium mines in the Lathrop Canyon area of Canyonlands National Park were selected for field analysis. Gamma and alpha radiation surveys were conducted onsite. EPA’s National Air and Radiation Laboratory in Montgomery, Alabama analyzed solid and water samples for metals and radionuclides of the uranium-238 series. Field observations and analysis of sample data indicate that the Lathrop Canyon sites, abandoned in the 1950s, have stabilized over time and currently have minimal impact on the environment and potential biological receptors. From this analysis the NPS, AMRP, and EPA conclude that it is best not to attempt removal or onsite encapsulation of the waste rock piles.