Papers to be signed to clean up tainted groundwater
Regulatory agencies will heat the ground near the cleaning building far below the surface and vacuum out vaporized contamination.
By Joe Walker
Tuesday, August 09, 2005
Regulatory agencies will sign a document today for a $40 million project to clean up an area of the Paducah Gaseous Diffusion Plant that is the leading cause of billions of gallons of contaminated groundwater.
The document, called a record of decision, is scheduled to be signed at 11:30 a.m. by Bill Murphie, manager of the Department of Energy's Portsmouth (Ohio)/Paducah Project Office, and Kenneth LaPierre, Federal Facilities Branch chief for the U.S. Environmental Protection Agency. The signing is planned for the DOE Site Office in front of the plant.
Also on hand will be Lloyd Cress, commissioner of the Kentucky Environmental Protection Cabinet, which has issued a letter agreeing with the decision.
The agencies have agreed to heat the ground far below the surface and vacuum out vaporized contamination for carbon-filter treatment. Construction will begin next year, with heating targeted to start in 2007.
During testing over several months in 2003, electrodes were buried 100 feet deep near the southwest corner of a cleaning building, called C-400, where the now-banned hazardous degreaser trichloroethylene (TCE) was used extensively for decades to clean uranium-enrichment machinery.
The 2003 test proved that 98 percent of the TCE could be removed, said Greg Cook, spokesman for DOE cleanup contractor Bechtel Jacobs.
"That was very, very successful, much more than we ever expected it would be," he said. "Now we're applying the same basic technology to the broader area south of the C-400 building, the area that all our measurements show is the area of highest concentration."
Cook said it will take several years to clean up the area. Testing removed some virtually pure TCE from the ground, he said.
"This is unquestionably the main source of groundwater contamination at the site," Cook said. "It's probably not the only one, but certainly is the main one."
Historic spills have left almost 180,000 gallons of TCE beneath the building, some at concentrations more than 20,000 times greater than the federal safe drinking water standard of five parts per billion. That level, at which municipal water systems must treat to remove TCE, is equivalent to five kernels of corn in a silo 45 feet high and 15 feet wide. Molasses-like globs of the hidden, heavier-than-water chemical have lodged in underground rock fissures, feeding traces of TCE into the aquifer almost indefinitely.
Cook said two pump-and-treat systems on the northeastern and northwestern plant boundaries continue to remove about 16 million gallons a month, and have cleaned up more than a billion gallons. But the systems only remove the highest concentrations of the contamination, which covers much of the area from the plant to the Ohio River.
"We've never actually seen TCE in the river at our monitoring points downstream" of the plant, Cook said, noting that if TCE actually is in the river, it is being diluted below detectable levels. "We have picked it up upstream, but that's not coming from the plant."
Used in many industries, TCE is a common groundwater contaminant with various sources, Cook said.
The chemical solvent is deemed to be the main public health risk near the plant. The Energy Department spends about $70,000 a year providing free municipal water to 120 properties around the plant that either have contaminated well water or are threatened by it. Those wells have been capped.