[en] The 100, 200, 300 and 1100 Areas of the Hanford Site were placed on the U. S. Environmental Protection Agency's National Priorities List in November 1989 under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). Located in the 200 Area is the deactivated 233-S Plutonium Concentration Facility (used in the REDOX process). The facility has undergone severe degradation due to exposure to extreme weather conditions. An expedited response is proposed to ensure protection of human health and the environment. The Department of Energy, Richland Operations Office (RL) in cooperation with the Washington State Department of Ecology, has prepared this Engineering Evaluation/Cost Analysis pursuant to CERCLA. Based on the evaluation, RL has determined that hazardous substances in the 233-S Facility may present a potential threat to human health or the environment, and that an expedited removal action is warranted for decommissioning of the facility