Water cleanup good, but not foolproof
The $40 million project will use electrodes to evaporate contaminated water beneath a gaseous diffusion plant building.
Wednesday, August 10, 2005
Although the goal of a $40 million project is to clean up the groundwater beneath a Paducah Gaseous Diffusion Plant building to within safe drinking water standards, the Department of Energy is making no promises.
"You can't guarantee treating every nook and cranny," said Bill Murphie, DOE site manager for the plant, which has an estimated 10 billion gallons of groundwater below it.
About 1 billion gallons of groundwater containing about 1,800 gallons of the degreaser trichloroethylene (TCE) have been removed by pumping and treating over the past several years. But that has not attacked the key source the C-400 building in the center of the 750-acre plant where TCE was used for decades to clean machinery used to enrich uranium for use in nuclear fuel.
Murphie joined state and federal environmental regulators Tuesday in signing a "record of decision" to bury electrodes deep in the ground beneath the building. The electrodes will evaporate the degreaser, and the vapor will be pumped to the surface and trapped in carbon filters.
Construction will begin by November 2006, with the system operational the following year. Murphie said the system probably will operate for two or three years, long enough for most of the chemical to be removed and the electrodes to reach the end of their cost-effectiveness.
Two years ago, 22,000 pounds of the solvent were removed by test electrodes that proved more than 98 percent effective, Murphie said.
Historic leaks and spills of TCE and some former workers say the intentional dumping years ago of the chemical down a drain in C-400 have left nearly 180,000 gallons of TCE beneath the building. Some groundwater concentrations are more than 20,000 times greater than the drinking water standard of five parts per billion, equal to five drops of ink in a canal lock full of water.
Because the cleaned machinery contained radiation, the groundwater also is polluted with Technetium-99, brought into the plant decades ago in uranium recycled from nuclear fuel. Tc-99 is not as prevalent in the aquifer as TCE, but it can't be removed using the electrodes, regulatory officials say.
"We'll deal with that (other contamination) as the project moves along," said Bruce Scott, director of the Kentucky Division of Waste Management.
A system to remove other contamination will be devised after the electrode project ends, Murphie said. "This action is a focused action."
Although the electrode system isn't foolproof, members of the plant's citizens advisory board generally agree it is the best known cleanup method, board member Jim Smart said.
"That's where the rubber meets the road," he said. "If they go after the mother lode, maybe they can get the plant cleaned up."