The U.S. Department of Energy has agreed to spend $4.5 million during the next three years to study groundwater contamination on the Oak Ridge Reservation.
The reservation includes three federal sites—East Tennessee Technology Park, Oak Ridge National Laboratory, and Y-12 National Security Complex—that have been involved in missions ranging from scientific research to uranium enrichment to nuclear weapons work. That work has sometimes included the use of hazardous substances such as mercury and technetium-99, a slow-decaying radioactive metal.
The $4.5 million in funding will help implement a new groundwater strategy developed by DOE with help from the Tennessee Department of Environment and Conservation and the U.S. Environmental Protection Agency.
The strategy, which was presented to the Oak Ridge Site Specific Advisory Board in November, will help guide future cleanup decisions, said Sue Cange, deputy manager for environmental management in DOE’s Oak Ridge Office.
Officials said there is no cause for alarm, and the off-site risks from possible groundwater contamination aren’t significant enough to compel the EPA to require the Department of Energy to act.
“No one should be alarmed,” said Daniel J. Goode, a research hydrologist for the U.S. Geological Survey. “DOE is managing the site. It’s very complex. It’s very contaminated. But they are protecting the public. There is no crisis here.”
But during a November briefing to the SSAB, Goode said there are questions about the potential migration of contaminated groundwater off the Oak Ridge Reservation through very limited, discrete waterways deep under ground.
The groundwater project team, which also included representatives from UCOR/RSI and SAIC, recommended a three-year off-site groundwater quality assessment focused on the southwest side of the Oak Ridge Reservation. Residential wells and springs could be sampled and their contents analyzed to determine if contaminants unique to the ORR are present and if there is a potential public health risk from DOE contaminants. The results could be evaluated to determine if more action is needed.
The groundwater strategy document said there have been recent sporadic, low-concentration detections of radionuclides and volatile organic compounds, or VOCs, in off-site sampling locations “downgradient” of the ORR.
The contaminants are at very low concentrations, but DOE has put in place some land-use restrictions and provided water to residents, Goode said. There are off-site monitoring wells in Melton Valley between Haw and Copper ridges, and they have detected contaminants that could have come for Oak Ridge.
“There are no known health impacts from contaminants detected off-site,” the strategy document said. “However, in order to minimize groundwater pumping that could draw DOE contaminants off-site, license agreements restricting groundwater use have been put in place for some residents in the area west of the Clinch River across from Melton Valley.”
The strategy said a number of radionuclides and VOCs have been periodically detected at low levels in monitoring wells in Melton Valley southwest of ORNL. There have also been intermittent detections of metals and VOCs in off-site wells on the west side of the Clinch River, across from the reservation, and two detections of strontium-90 and technetium-99 have been observed, the report said.
But with the exception of a low VOC detection in one well in 2010, no known DOE contaminants in off-site wells across the Clinch River from Melton Valley have exceeded safe drinking water standards, Goode said. And that one compound was not detected in subsequent samples from the same well.
Detection of the contaminants doesn’t prove migration from the Oak Ridge Reservation, but there is a consensus that off-site migration is plausible, may have occurred, and needs investigation, Goode said.
Dave Adler of DOE-ORO said VOCs are not unique to Oak Ridge—they’re used for activities ranging from agriculture to racing—but technetium-99 is. The technetium-99 was found in a DOE sampling well and only after aggressive drilling that could have drawn contaminants into the well, Adler said.
Goode said the groundwater strategy could include a revival of state-of-the-art studies at the Oak Ridge Reservation that could include academic and government experts. That type of approach seems to be under way with respect to mercury, Goode said.
He said there are many data gaps regarding groundwater contamination because there has been little investigative work since the 1990s. Since the early 1990s, DOE has focused on remediation and monitoring and less on science, even though there have been scientific advances in characterization and modeling in the past two decades, Goode said.
The project team’s strategy document included a ranking of plumes on the Oak Ridge Reservation at ETTP, ORNL, and Y-12. They were ranked by pathway, hazard, toxicity, and longevity, among other things.
The top two plumes by what is known as a pathway score are contamination from undetermined sources on the southwest side of the reservation, southwest of ORNL’s main campus and near the Clinch River, and uranium in Maynardville limestone at Y-12. The third is S-3 Deep nitrate in the Maynardville limestone in Bear Creek Valley west of Y-12.
The top ranking by what is known as a total plume score—the final results were heavily weighted with the pathway score—is a hydrofracture disposal site south of ORNL where waste was injected between 700 to 1,000 feet underground with cement. That site had the highest hazard score.
Goode said the ORSSAB could consider recommending that DOE collect, review, and archive records associated with the hydrofracture disposal site to support long-term stewardship. He said that waste will be at that spot forever.
Communications with the public could be an important part of the groundwater work, Goode said.
For some time, regulators have wanted DOE to evaluate groundwater contamination and develop possible responses. Officials said the new groundwater strategy will include the implementation of more groundwater investigation to support ongoing efforts to manage groundwater resources associated with the Oak Ridge Reservation.
“This is a great example of us trying to be more collaborative with the environmental regulators,” said Michael T. Koentop, executive officer in DOE’s Oak Ridge Office of Environmental Management.
Read the groundwater strategy document here: ORSSAB Groundwater Report.
More information will be added as it becomes available.