Portable XRF to Guide a Groundwater Source Removal Action at the Cañon City, CO, USA Uranium Mill

The Cotter Corporation began uranium ore milling in 1958 at the Canon City Uranium Mill in Canon City, Colorado, USA. Over the years, uranium (U) and molybdenum (Mo) leached from the tailings and impacted the shallow groundwater which eventually migrated off site. In 2008, the S.M. Stoller Corporation (Stoller) performed a source removal action by remediating 225,000 cubic yards (CY) of contaminated soil from the former settling pond that was a potential source of Mo and U groundwater contamination. Stoller used portable X-ray fluorescence (XRF) to provide real-time data that reduced the amount of soil required to be removed by 30%. This paper examines the process by which the sampling was designed, the statistical analysis, and the lessons learned.