The 2015 spill occurred when the truck driver braked hard to avoid hitting a deer and sludge sloshed over the back of the shipping container. The 2016 spill resulted from a faulty seal along the bottom of the container door, company officials told the NRC. In both cases, workers at White Mesa Mill identified the spills while the truck was still parked alongside U.S. 191 and cleaned up the material, according to a report by mill owner Colorado-based Energy Fuels Resources.

