Andrew Wheeler, acting head of the U.S. Environmental Protection Agency, on Monday signed a record of decision laying out the final cleanup plan for the 100 D and H Areas along the horn of the Columbia River at the Hanford Site in Washington state.
Cleanup began under interim decisions in the mid-1990s on 7.8 square miles of Department of Energy land near the D and DR reactors and the H Reactor, with the Washington state Department of Ecology acting as lead regulator. The EPA and DOE issued the record of decision, with “concurrence” from the state agency.
“This record of decision ensures the final remaining waste sites in the 100 D and H area(s) will be addressed thoroughly and quickly,” Wheeler said.
To date, DOE has spent $374 million on remediation of this section of Hanford, with an estimated $200 million of work remaining, primarily for continuing groundwater cleanup. “This land and groundwater cleanup is an important ‘puzzle piece’ in the larger Hanford project,” said Chris Hladick, EPA Region 10 administrator, in a press release. “Since these areas are virtually on the banks of the Columbia River, this work to further reduce toxic and radiological threats to the river is particularly important.”
Remaining work includes cleaning up five of 104 waste sites near the reactors, with most of those locations awaiting final confirmation that completed efforts meet cleanup targets. Remaining waste sites are small, such as some contamination left by wasps on power poles, and are anticipated to be cleaned up within two years. Dozens of buildings have already been torn down and the three reactors cocooned, or placed in interim storage, to allow further radioactive decay before demolition.
Groundwater treatment will continue, with a planned upgrade to the two pump-and-treat systems now being used to remove hexavalent chromium from groundwater. The chemical was added to cooling water in the reactors to inhibit corrosion. Plans call for expanding the number of wells used to extract contaminated groundwater or inject cleaned water back into the ground from 118 to about 170. The additional wells will allow the chromium cleanup to be completed in about 12 years, according to the record of decision.
The record of decision calls for natural attenuation of some remaining strontium-90 contamination in the area. The contamination will be allowed to radioactively decay until drinking water standards are met within 44 years.
Watchdog group Hanford Challenge said after the decision was signed that allowing natural attenuation of strontium, a potential carcinogen, was concerning. The local Hanford Advisory Board asked DOE and its regulators in 2016 to consider a more aggressive approach for strontium remediation.
However, the board at the time praised work that already was done, including the “big digs” at the D Area where chromium had been spilled to reduce the amount that was reaching groundwater. In three places near the D and DR reactors, workers dug down to 85 feet or more to reach groundwater, using engineering developed for open pit mining. Two of the digs eventually combined into one excavation that stretched over an area of about 7.5 football fields.
“It’s a good cleanup plan,” said Rod Lobos, the EPA project manager for the 100 D and H Areas. “It’s clean enough for all potential future uses.” The approach meets residential cleanup standards, he said, although there are no plans for residential use of that area. The DOE Hanford Comprehensive Land-Use Plan calls for the land in the 100 D and H areas to be preserved in a natural state.
Anne Marie White, assistant energy secretary for environmental management, pointed out that the federal government, Washington state, tribes in the region, and other stakeholders made protecting the Columbia River a priority when cleanup began, which helped shaped the record of decision. “The Department of Energy’s Environmental Management program has a completion mindset and is focused on achieving end states, and the substantial progress made at the 100 D and H areas is a shining example of that,” she said in the release.
This is the second record of decision for a Hanford reactor area, with the prior document signed in 2014 for land around the F Reactor.