The Hanford 200-Area spans 79 square miles about 17 miles north-northwest of Richland, Washington. It operated as a nuclear materials processing facility and left behind roughly one billion cubic yards of radioactive, mixed, and hazardous waste buried in trenches, ditches, and an on-site landfill. The site was added to the National Priorities List in 1989, and formal remedy construction began in 1995. Radioactive and mixed waste treatment and disposal operations are expected to continue at least until 2050 or beyond.
More than 70 contaminants of concern have been identified across the site. Groundwater holds carbon tetrachloride, chromium, tritium, uranium, trichloroethene, nitrate, technetium-99, iodine-129, and chloroform, among others. Soils and debris contain radioactive substances like plutonium-239/240, cesium-137, strontium-90, and americium-241, as well as chemicals like mercury and polychlorinated biphenyls (PCBs). An on-site disposal facility also has leachate containing metals, solvents, and other chemicals.
The U.S. Department of Energy (DOE) owns and operates the site and leads cleanup. The DOE, EPA, and Washington State coordinate under the Tri-Party Agreement. Major cleanup actions include operating a pump-and-treat system that has processed at least 18 billion gallons of contaminated groundwater, disposing of over 18 million tons of remediation waste at the Environmental Restoration Disposal Facility, demolishing contaminated buildings including the Plutonium Finishing Plant, and excavating buried waste. The site is divided into more than 19 source operable units (OUs) and 4 groundwater OUs covering more than 800 waste sites. Some OUs have finished major milestones, while others are still in investigation or active cleanup phases, with estimated completion dates running through at least 2027.
Current assessments indicate there are no unacceptable human exposure pathways at this time. However, contaminated groundwater migration is not yet stabilized, physical construction is not complete across the entire site, and the site does not yet meet the criteria for site-wide readiness for anticipated use. A 2024 five-year review confirmed that completed response actions match their intended design, though EPA has not determined overall protectiveness because work remains ongoing. The next five-year review is estimated between May and July 2027.
Community members can access site records at the Public Access Room in Richland, Washington, at 2440 Stevens Center Place, Room 1101. Additional information and upcoming public involvement events are available through the Hanford website. EPA's Community Involvement Coordinator can answer questions about the site and direct people to the Administrative Record.
