Hanford Site Fact Sheet


The mission of NCSL’s Nuclear Legislative Workgroup (NLWG) is to provide legislative members with the opportunity to learn about the cleanup of federal nuclear weapons production and research facilities, the transportation and storage of radioactive wastes, and nuclear energy issues that affect our nation and states. This fact sheet is part of this effort.


The Hanford Site in southeastern Washington, was home to the world’s first nuclear reactor and first full scale plutonium production plant used for America’s nuclear weapon program. Located along the Columbia River near the Tri-Cities of Richland, Kennewick, and Pasco, the 586 square mile site contains over 53 million gallons of chemical and radioactive waste and is now home to the world’s largest environmental cleanup operation. The U.S. Department of Energy’s Office of Environmental Management (EM) oversees cleanup activities at the Hanford Site.

State: Washington
Size: 586 square miles
Original Purpose: Plutonium Production
Estimated Cleanup Completion: 2052

Scale of the Contamination

There are three main components to the Hanford Site cleanup: (1) River Corridor, (2) Central Plateau and (3) Tank Waste. At least 1,900 waste sites have been identified, including nine plutonium production reactors near the Columbia River and 500 contaminated facilities. There are more than 20 tons of leftover plutonium material and 2,300 tons of nuclear spent fuel.  About 53 million gallons of hazardous chemical and radioactive waste exist on-site and are stored in 177 large underground tanks; 67 of these tanks may have leaked. Approximately 200 square miles of soil and groundwater beneath the site have been contaminated, creating plumes that flow towards the Columbia River.  Investigators have found that some contaminated areas are well documented, while others are not, leading to uncertainties as to the exact scale of the cleanup.

DOE’s Environmental Management Activities

The DOE EM’s mission at Hanford is to remove hazardous wastes from the site and remediate the soil and groundwater to avoid further exposure of contaminants.
Much of the cleanup will take place at treatment plants that are to be built on-site. Liquid wastes will be separated by their radioactivity and solidified by a vitrification plant at the site, also known as the Waste Treatment Plant (WTP). The construction of the WTP is a key part of the DOE Tank Waste cleanup and is scheduled to be completed by 2019 and in full operations by 2022. Contaminated buildings, soils, and buried solid waste are relocated to appropriate disposal facilities including those on-site, the Department of Energy’s Waste Isolation Pilot Plant in New Mexico and a national geologic repository.
Groundwater and soil treatments continue at the River Corridor and Central Plateau. The treatment prevents contaminated plumes from reaching the Columbia River and avoids re-contamination of the groundwater. Permeable barriers are put in place allowing water to flow through them while chemically altering the hazardous contaminants. A pump-and-treat action is being used to remove chemicals from the groundwater. The water is pumped out of the ground, treated to remove contaminants and then pumped back into the ground. Additional treatments such as the injection of micro-size iron, electro-coagulation and bio-stimulation are being researched and tested. Monitoring and regulation of the groundwater and soil will continue beyond completion of the remediation.

Timeline for Cleanup Completion

The overall site cleanup is expected to continue until 2052.  A majority of the River Corridor land segments will be completed by 2016, except for a small portion that is expected by the DOE to be completed no later than 2020. The cleanup of the Central Plateau Outer Area is expected to be completed by 2020. The DOE, US Environmental Protection Agency, and State of Washington Department of Ecology signed the Tri-Party Agreement in 1989  that set the timeline for the cleanup operations.

Additional Resources

NCSL Resources

Other Resources