DOE wants to try unprecedented pond cleanup at K-25 plant site

Oakridger.com, October 10, 2006
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Sunfish feeding
(AP) — The Department of Energy is considering an unusual “ecological enhancement” approach to cleaning up a contaminated pond at a uranium-enrichment plant.
The Energy Department is in the middle of a massive cleanup project at the K-25 plant site, preparing it for private use. But before the site can be turned over to new owners, the pond, which contains polychlorinated biphenyls, or PCB, must be cleaned.
The department traditionally uses what it calls the “muck-and-truck” approach — draining, dredging and filling a pond with dirt. The ecological enhancement approach will preserve the pond and rectify the aquatic habitat.
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A school of grass carp, to be weeded out
“The strategy will significantly enhance the quality of the pond by putting in new vegetation and taking out the nonnative fish,” Oak Ridge National Laboratory environmental scientist Mark Peterson told The Knoxville News Sentinel.
Peterson has been monitoring pond conditions and PCB levels since 1989 and developed the idea to preserve the pond.
His process involves removing the fish population — estimated at 100,000 — and separating native sunfish that feed on terrestrial insects and are largely uncontaminated from the nonnative fish, such as grass carp, which consume the pond’s vegetation, and largemouth bass that feed on smaller fish.
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Largemouth Bass, too contaminated to eat
After removal and separation, scientists would either completely replace the fish population or return the native uncontaminated fish. A vegetative buffer would be placed around the pond to keep geese from using the area, said Jim Kopotic, DOE’s team leader for cleanup projects at the federal site.
As ecological changes take hold, PCB-contaminated sediments will be covered, reducing potential for human health concerns, Kopotic said.
By Energy Department Cold War nuclear sites standards, the pond is not overwhelmingly polluted. The main concern is the presence of PCBs, which are a widespread plague on the environment because of their broad usage years ago in electrical transformers.
Kopotic emphasized that the pond rehabilitation is the preferred cleanup process by DOE and the Tennessee Department of Environment and Conservation, but is only a proposal at this point. It’s also the cheapest option, with an estimated cost of $4.1 million compared to $10 million to close out the pond, according to DOE.
But not everyone is convinced ecological enhancement is the best idea.
“We don’t think this is a permanent solution,” said Susan Gawarecki, executive director of the Local Oversight Committee, which studies environmental projects for local governments.
Gawarecki said removing contaminated sediments might be the best answer, after which the pond could be re-established.
A public meeting about the pond and several other smaller ones is scheduled for 6 p.m. Oct. 19 at the DOE Information Center in Oak Ridge. Information about the project is available for public viewing there.

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