Technological approaches to groundwater treatment in remediation projects

Past activities at U.S. Department of Energy (DOE) sites associated with production of nuclear materials included multiple steps that resulted in production of waste materials. For example at the DOE Hanford Site, fuel fabrication and nuclear reactors were adjacent to the Columbia River, an important resource to protect in clean up efforts. Plutonium and uranium separations were conducted miles inland from the river. Sites along the river have uranium, chromium, nitrate, and strontium-90 groundwater plumes associated with fabrication and reactor operations. In the separations area, significant quantities of liquid wastes were produced and were discharged in multiple types of disposal units. Much of the discharged contaminants in the separations area are still in the vadose zone where waste disposal chemistry has affected transport of some of the contaminants. However, past discharges were large enough in some cases to create large carbon tetrachloride, iodine-129, technetium-99, uranium, chromium, and other contaminant groundwater plumes. Other DOE sites have large groundwater plume issues including an acidic iodine-129, uranium, and strontium-90 plume at the Savannah River Site, a chromium plume in the deep subsurface at the Los Alamos Site, and issues with mercury in groundwater and surface water at the Oak Ridge Site.