A pump-and-treat system that captures groundwater contamination near radioactive waste tanks inside the Hanford Site in Washington would be expanded under a joint interim record of decision announced Wednesday by state and federal agencies.
The interim decision for groundwater operable units in Hanford’s 200 East Area — 200-BP-5 and 200-PO-1 — was issued jointly by the Department of Energy, the Environmental Protection Agency (EPA) and the Washington state Department of Ecology. The three are signatories to the legally-binding tri-party agreement, the official cleanup roadmap for the former plutonium-production site.
The nearly 200-page interim record of decision (ROD) says the current pump-and-treat facility will be augmented with an ion exchange system to remove both technetium-99 (Tc-99) and uranium. Also, extraction wells will be installed to remove contaminated groundwater from the aquifer “and to reduce or prevent further plume migration.” Injection wells will be used to inject treated water back into the aquifer in the 200 West Area.
The interim ROD is drafted under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), or the Superfund law, to mitigate groundwater plumes containing radioactive technetium-99 and uranium.
The current pump-and-treat setup captures contamination near tanks in the B, BX and BY Farms., according to the press release from the Tri-Party agencies. More groundwater extraction wells will be installed in the A, AX and C Tank Farm areas.
After the groundwater is extracted, it is piped to Hanford’s existing 200 West Area Pump and Treat Facility, where contamination is removed. The interim ROD also includes controls to block people from coming into contact with the groundwater until it is treated to reduce contaminant concentrations.
Hanford is one of the most polluted sites in the world due to decades of plutonium production. The 200-BP-5 groundwater contamination is leftover from operation of the B Plant chemical separations facility, and the 200-PO-1 groundwater contamination is linked with the Plutonium-Uranium Extraction (PUREX) Plant chemical separations facility, according to the document.
In the old days, as effluents were intentionally discharged to engineered structures and unintentionally leaked from underground storage tanks, the radioactive contamination seeped into either groundwater or the soil.
A separate remedial action is planned for waste areas that overlay the plumes. The interim remedy is meant to buy time and prevent further plume migration, according to the document.
The recently posted document was signed by Sept. 28 by DOE’s Hanford manager Brian Vance, EPA administrator Michael Regan and Ecology’s nuclear waste program manager, David Bowen.
A link to the interim record of decision can be found here.
