Tank Waste & Known Leaking Tanks
Managing 56 Million Gallons of Legacy Waste
The Hanford Site contains 177 underground storage tanks that held about 56 million gallons of radioactive and chemical waste left from plutonium production during World War II and the Cold War.
The tanks are grouped into 18 farms and divided into:
149 Single-Shell Tanks (SSTs) – Built with concrete and carbon steel, these older tanks were designed for a limited service life and are now decades beyond their original design period.
28 Double-Shell Tanks (DSTs) – Built starting in 1968, these tanks include an inner steel tank, a separate steel liner, and an outer shell for secondary containment.
Monitoring and Leak Prevention
Tank waste is carefully monitored to detect leaks and track waste levels. Measures include:
Transferring liquid waste from SSTs to DSTs
Operating the 242-A Evaporator Facility to reduce liquid volume through evaporation
Using monitoring wells to track potential groundwater contamination
Conducting periodic video inspections inside tanks
Known Leaking or Suspected Leaking Tanks
Several Hanford tanks are known or suspected to have leaked waste. Examples include:
T-111 – Leaking ~300 gallons/year (identified 2013)
B-109 – Leaking ~560 gallons/year (identified 2021)
T-101 – Suspected leak of ~200 gallons/year (as of August 2024)
AY-102 – A double-shell tank where a leak from the inner tank into the annulus was discovered in 2012. The waste did not reach the soil, and more than 725,000 gallons were removed by 2017.
Recent Agreements and Actions
In 2025, the U.S. Department of Energy, Washington State Department of Ecology, and U.S. Environmental Protection Agency finalized the Hanford Site Holistic Agreement. The agreement addresses serveral parts of the tank waste cleanup mission, including retrieving waste from 22 tanks in Hanford’s 200 West Area by 2040 and grouting the low-activity portion of that waste for offsite disposal.
The agreement also includes plans for additional tank waste storage capacity and continued evaluation of new technologies for retrieving waste from tanks.
Waste Retrieval and Tank Closure
Hanford crews have removed waste from another aging underground tank, marking continued progress in the long-term effort to retrieve waste from older single-shell tanks and move it to newer double-shell tanks for safer storage until treatment.
The work focused on single-shell Tank A-102 in Hanford’s East Area. Crews transferred about 41,000 gallons of decades-old solid waste from the tank, bringing the total number of tanks with waste retrieved to 23. The total amount of waste retrieved from those tanks is now approximately 3.4 million gallons.
Tank waste retrieval is one of the major steps needed to reduce long-term risk and prepare waste for treatment and disposal.
Long-Term Waste Plan
Hanford’s long-term tank waste cleanup mission includes multiple treatment paths. Low-activity waste treatment has begun through the Waste Treatment and Immobilization Plant (WTP), also known as the Hanford Vit Plant. The Holistic Agreement also allows for grouting the low-activity portion of some tank waste for offsite disposal, while high-level waste treatment remains part of Hanford’s longer-term cleanup mission.