Hanford plume cleanup hastened
YAKIMA – The federal government is accelerating cleanup of one plume of contaminated groundwater at the nation’s most contaminated nuclear site in an effort to better protect aquatic life in the nearby Columbia River.
The project will triple the amount of groundwater treated for hexavalent chromium, a cancer-causing agent that was used as a corrosion inhibitor in nuclear reactors, at south-central Washington’s Hanford Nuclear Reservation. The contaminant moves easily with water and is particularly dangerous to salmon in the region’s largest waterway.
“Accelerating this work emphasizes our commitment to cleanup and directly supports our goal to stop key contaminants from reaching the Columbia River,” Briant Charboneau, the U.S. Department of Energy’s project director for groundwater remediation, said in a statement Tuesday.
The federal government created Hanford in the 1940s as part of the top-secret Manhattan Project to build the atomic bomb. Plutonium production for the nation’s nuclear weapons program continued there for four decades, leaving an estimated 80 square miles of groundwater contaminated at levels exceeding state and federal drinking water standards.
The hexavalent chromium contamination near the K East Reactor resulted from discharges of reactor effluent into a long trench next to the Columbia River.
The plume stretches along 1 1/4 miles of the rivershore. Very little of the contamination closest to the river exceeds the federal drinking water standard of 100 parts per billion, while about half of it away from the river exceeds the standard, said Larry Gadbois, environmental scientist with the Environmental Protection Agency.
However, the area closest to the river exceeds the more stringent standard for fresh water aquatic life – 10 parts per billion.
New wells and additional equipment will allow the contractor hired to handle the groundwater cleanup, Fluor Hanford, to triple the amount of groundwater it can treat, from 300 gallons per minute to 900 gallons per minute.
“This isn’t just a little increase. This is a major increase, that should not only capture the plume, but pump the water hard enough that this will really help restore the aquifer,” Gadbois said.
A 2004 audit by the Energy Department’s inspector general criticized the agency’s groundwater cleanup efforts, finding the pump-and-treat systems had been largely ineffective. Those systems pump water out of the ground, use chemicals to remove the contaminants and inject it back into the ground.
However, Gadbois said the method has worked quite well for chromium. A similar plume at the 100 H Reactor is nearly cleaned up, and the plume at K East Reactor has been reduced by about one-third.
“In this case, we just needed a bigger system, because the plume is bigger,” he said. “But it’s the right remedy.”
Accelerating groundwater cleanup has been a point of discussion among the Energy Department, EPA and Washington state officials in recent months amid negotiations over the Tri-Party Agreement, the 1989 pact that governs cleanup of the site.
The document has seen numerous changes over the years, but the Energy Department has recently proposed some significant deadline changes. Among the things the state has sought in return is an acceleration of groundwater cleanup to better protect the Columbia River.