Tank Waste & Known Leakers
Managing 56 Million Gallons of Legacy Waste
The Hanford Site contains 177 underground storage tanks holding a total of 56 million gallons of radioactive and chemical waste — byproducts of 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, designed for a 20-year lifespan but now decades beyond their intended service life.
28 Double-Shell Tanks (DSTs) – Built starting in 1968, with 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 Leakers
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 (DST) – Leak from the inner tank into the annulus discovered in 2012; waste did not reach the soil. Over 725,000 gallons removed by 2017.
Recent Agreements and Actions
In August 2022, the DOE and the Washington State Department of Ecology signed an Agreed Order to address Tanks B-109 and T-111.
The plan includes:
Evaluating enhanced salt-well pumping and an in-tank pretreatment system to stop leaks
Assessing disposal options for removed waste, including transfer to a DST or treatment facility
Third-party review of methods by Pacific Northwest National Laboratory (PNNL)
Waste Retrieval and Tank Closure
The Hanford contractor Washington River Protection Solutions (WRPS) is tasked with retrieving waste from SSTs and transferring it to DSTs.
Tank AX-101 – Currently undergoing retrieval of ~426,000 gallons
Once certified empty, AX-101 will be the 21st SST to be emptied
This will make AX Farm the second farm fully retrieved, after C Farm
Long-Term Waste Plan
The majority of Hanford’s tank waste will ultimately be solidified at the Waste Treatment and Immobilization Plant (WTP) in the 200 East Area.