B-109 leak assessment began July 2020
When monitoring data indicates that a tank might be leaking, Energy is obligated to begin a formal leak assessment process and notify us. Energy notified us in July 2020 it was beginning a leak assessment for Tank B-109. It’s a complex process that can take more than a year to complete. We monitor the process and await the results to review what Energy’s experts find.
Notified of B-109 leak in April 2021
Since Energy’s assessment concluded tank B-109 is leaking, Energy was required by law to notify us that dangerous waste is leaking into the environment. Energy notified us of the leak in April 2021.
Tank B-109 has now joined tank T-111 as a known, actively leaking underground tank.
Proposed response to the B-109 leak by Energy
Energy must first take actions to stop a tank leak and clean up the contamination. If Energy does not take timely and appropriate action to stop it, we can and will take enforcement actions as necessary.
Energy proposed a few minor actions in April 2021 that would mitigate some risk but not stop the B-109 leak. For example, they proposed installing a barrier over the B tank farm to slow down the movement of contamination to the groundwater.
Regulatory authority to protect the environment
We take leaks seriously and are committed to a solution that protects the public and the environment. The Tri-Party Agreement sets forth the process we and Energy must go through when a tank is determined to be actively leaking.
First, our agency and Energy must attempt to reach unanimous agreement about steps in responding to a leak. If unanimous agreement is not reached, Ecology has the regulatory authority to issue an Administrative Order that specifies the actions Energy must take to stop the tank leak and the schedule on which those actions must happen.
We are currently engaged in this Tri-Party Agreement process with Energy to stop the leaks from tanks B-109 and T-111. If both agencies do not come to an agreement, we will use our authority to mandate specific actions Energy must take to address the leaks.
No immediate threat
Based on the information we have right now, the leaks in tanks B-109 and T-111 pose no immediate increased risk to workers or the public, but the ongoing releases of waste do pile on to the long-term environmental threat at Hanford.
Detecting a leak is difficult
At Hanford, determining if a tank is actively leaking is a complex process.
The 149 single-shell tanks at Hanford had the majority of their liquids removed in the mid-1980s through the early 2000s as part of Hanford’s interim stabilization program. The liquid waste was moved to the site’s 28 double-shell tanks.
Any remaining liquid in the single-shell tanks was mostly within the sludge waste. The sludge has a similar consistency to pudding. Over time, some liquid has seeped out of the sludge and saltcake. Rainwater and snowmelt can also leak into the tank, adding to the liquid that could then leak from a tank.
Energy uses a variety of data sources to determine if a tank is actively leaking waste into the environment, including:
• A device called an ENRAF – a weight on a cable measuring the height of the waste in a tank.
• Liquid Observation Wells
• Liquid level measurements under the surface of the solid waste
• Drywell monitoring
Information from all of these sources is used to determine if a leak is actually occurring, or if there is some other explanation for a change in tank waste levels. For example, decreases in waste levels could be a result of gas releases from the waste, or because one of the monitoring instruments malfunctions.
In addition, the surface of the waste in a tank can consist of many valleys and hills. These might change as waste shifts underneath the devices responsible for measuring the height of waste. Energy’s experts evaluate these and other potential causes during the leak assessment process to determine whether the drop in liquid levels is a result of an active leak or something else.
Energy announced Tank B-109 as actively leaking April 29, 2021, following the formal leak assessment process that began in July 2020.
Workers constructed Tank B-109 between 1943 and 1944. The tank received reprocessing wastes until 1976. Most of the tank's drainable liquid wastes were retrieved in 1985 as part of Hanford's interim stabilization program, and moved to double-shell tanks.
Today the tank holds about 123,000 gallons of residual waste, with roughly 15,000 gallons of drainable liquids. An estimated 3.5 gallons are leaking per day.
At the time of the April 2021 leak announcement, roughly 3,100 gallons had already leaked into the soil. That number might be more than 3,640 now.
Single-shell tank T-111, which has been declared leaking several times over the years, was most recently declared leaking in 2013. Energy’s preferred response action was to install an active ventilation system, which operated from July 2015 to April 2019. In 2019, officials determined there was a direct connection to Tank T-112, causing inadvertent evaporation of some of the liquids from that tank.
Energy halted active ventilation of T-111 because the existing air permit didn't authorize the ventilation of Tank T-112. Now, however, ongoing liquid level decreases in Tank T-111 are at least as large as before and during the active ventilation.
Tank T-111 entered service in 1945 as part of Hanford's T-Farm. Like B-109, it was used to store the site's highly radioactive and chemically hazardous reprocessing waste generated from decades of plutonium production.
This tank was suspected of leaking as far back as 1974. Between 1974 and 1976, workers transferred 63,000 gallons of waste to other tanks as part of a tank stabilization effort. In 1995, T-111 also underwent interim stabilization.
In 2013, Energy evaluated the liquid level data trends for all of the single-shell tanks and found T-111 had one of the highest decrease rates. At the time, then Energy Secretary Steven Chu notified Gov. Inslee of the presumed leak.