Call it a dirt barbecue: Workers heat the ground to remove contamination at CTS site

Mark Barrett | The Citizen-Times

SKYLAND – If the temperature here reaches 100 degrees sometime this summer, the air would still only be a little more than half as hot as the dirt below the surface on a patch of land off Mills Gap Road.

At the CTS hazardous waste site, workers are using massive amounts of electricity to raise the underground temperature to 190 degrees so contaminants in the soil boil off and are vacuumed up as vapor.

The work is the first time large amounts of contamination from the ground have been removed at the site, which has been the subject of neighborhood concern since at least 1999, said Jeff Wilcox, a UNC Asheville professor of environmental science.

Even though it is considered only an interim cleanup, "This is the most progress by far" in the process of removing contaminants from the property at 235 Mills Gap Road, Wilcox said.

Why is the former CTS plant contaminated?

Workers made industrial switches and resistors in a manufacturing plant there for Illinois-based CTS Corp. from 1959 until the plant closed in 1986.

Testing by the U.S. Environmental Protection Agency uncovered contamination in soil and surface water in 1990, but it wasn't until 1999, when an industrial degreaser was found in a drinking water well near the site, that a significant push for a cleanup began.

EPA has been criticized by residents and others for being slow to deal with problems at the site, which is part of the EPA's Superfund program.

"We're happy that something is being done," said Tate MacQueen, one of several neighborhood residents who have lobbied for a cleanup for years. "The question that will always remain is why didn't (the EPA) address the source sooner."

In 2016, the EPA reached a cleanup agreement with CTS; current property owner Mills Gap Road Associates; and aerospace giant Northrop Gumman, the successor to a company that operated a plant on the site in the 1950s. It requires the three companies to spend $9 million to remove 95 percent of contamination.

How is the TCE being cleaned up?

The substances to be taken out are old fuel oil and trichloroethylene, or TCE. TCE is a solvent that is suspected of causing various illnesses, including cancer.

The project involves zapping 1.2 acres with enough electricity to vaporize chemicals.

According to the EPA, workers earlier this year drilled holes 30-50 feet into the ground on and around the former location of the plant, which has been torn down. The 229 holes are 17 feet apart and each is a foot in diameter.

Then they put electrodes made of cooper sheeting into the holes, surrounded the sheeting with a mixture of graphite and steel shot — it looks like black cat litter — to help conduct electricity to the soil and ran wires from each to a power control unit.

Pipes connect the wells and a vacuum system that channels the vapor to a condenser. The vapor is then cooled, which separates it into liquid and air.

The air is routed through an incinerator and scrubber to remove TCE; the liquid is treated to remove the fuel oil, which goes to a hazardous waste dump. The leftover water goes into a regular sewer pipe. The cleaned air, sometimes with a little visible steam, goes up a chimney, and everything else is hauled off to a hazardous waste dump.

Wilcox said the technology is probably the most advanced way to get at TCE contamination. Just pumping groundwater out and treating it wouldn't work because the chemical adheres to soil particles, he said.

Workers flipped the switch to turn on the juice for this dirt barbecue in late May. It is scheduled to run until October or November.

The operation can't go any later than that because Duke Energy says its electrical grid can't handle enough electricity to meet normal wintertime demands in that area plus power the cleanup.

The process is expected to use between 8.5 million kilowatts of electricity, the EPA says. For perspective, that's just a little less than the amount of power the 1,900 or so homes in the town of Weaverville will use over the same period.

The EPA says it expects the process will remove about 10 tons of contaminants before it wraps up this fall.

But, the job won't be over then.

Surrounding area will be treated next

Next spring, workers will inject potassium permanganate into a 1.9-acre area to the north of the plant site to clean up TCE in the ground there. Potassium permanganate is commonly used in water treatment plants and as a skin disinfectant.

The EPA says it will break down the remaining TCE to render it harmless. Byproducts of that process are carbon dioxide and water, EPA spokeswoman Davina Marraccini said.

Wilcox, the UNCA professor, said he is glad to see the EPA taking action and endorses the methods being used.

"Previous actions ... have been to deal with the symptoms of the problem" rather than actually removing the source, he said. "It wasn't going to to take care of itself. There is so much material, so much TCE, below the plant it needed an active solution."

But he and MacQueen said it is important to remember that the work being done now and next spring does not address contamination in bedrock below the area being treated.

"This is not the final cleanup," Wilcox said.

Once the current work is finished, those paying for the cleanup and even the EPA may want to quit there, he said. Wilcox said he can't say yet whether more work should be required.

"There's going to be a lot of pressure to call this good enough," he said. "It may be, or it may not."

The CTS plant manufactured industrial switches and resistors for more than 20 years before closing in 1986.