The U.S. Department of Energy (DOE) developed this Supplemental Environmental Impact Statement (EIS) to assess the potential environmental impacts of completing construction and operating the Defense Waste Processing Facility (DWPF), a group of associated facilities and structures, to pretreat, immobilize, and store high-level radioactive waste at the Savannah River Site. On the basis of the analysis of impacts in the Supplemental EIS, monetary costs, and regulatory commitments, DOE decided to complete construction and startup testing, and begin operation of DWPF. The facility will be completed and operated as designed, which includes modifications to the conceptual design originally proposed and evaluated in the EIS prepared for the DWPF in 1982 (DOE/EIS–0082). DOE also will implement additional safety modifications to DWPF that will substantially reduce or eliminate potential accidental releases of radioactive material and chemicals in the unlikely event of a severe earthquake. See also DOE/EIS-0082-S2.