The U.S. Army Corps of Engineers announced Thursday that it completed a five-year clean up of Kodiak’s Drury Gulch, a polychlorinated biphenyl (PCB) contaminated site near the Coast Guard Base used as a dumping ground during World War II.

Project manager Charley Peyton said most of the PCBs came from buried electrical equipment.

“The containers themselves were broken open or literally dumped out in the ground,” Peyton said. “Unfortunately, it was a common disposal practice back then.”

Some wrecked aircraft engines also contributed a smaller quantity of PCBs.

According to the Environmental Protection Agency, PCBs are a group of chemicals containing 209 individual compounds. They were widely used in electronics as insulation until the 1970s, when they were banned in the U.S. due to studies that found them harmful to human and environmental health.

The EPA classifies PCBs as a persistent organic pollutant and a probable human carcinogen. They also are linked to other adverse health effects, including low birth weight, thyroid disease and multiple cognitive disorders.

Peyton said locating the PCB-tainted soil was a challenge because there was more debris than initially expected and it was widely scattered.

“From the surface, it didn’t look that bad,” Peyton said. “It wasn’t until we excavated that we realized how extensive (the dumping) had been and how much debris there was. The hardest part was locating all the PCBs without literally digging the entire gulch up.”

To find PCB contamination, Peyton’s team created a grid across the six-acre site. Soil samples were collected from each section and sent to a lab, where PCB presence was measured in milligrams per kilograms of soil. The testing was extensive.

“There were tens of thousands of samples that had to be collected,” Peyton said. “Because they had buried over a lot of different debris that wasn’t exactly organized, you ended up chasing a lot of different paths.”

PCB contamination is not visible to the eye, though Peyton said on rare occasions it can be detected through odor.

Ultimately, 19,000 tons of PCB contaminated soil was removed from Drury Gulch.

The engineers also removed 450 tons of trichloroethylene (TCE)-contaminated soil. TCE is an industrial metal degreaser linked to nervous system damage and cancer.

The containerized soils were transported to the Columbia Ridge landfill in Arlington, Ore., for final disposal. The Drury Gulch site was covered with several feet of fresh soil.

A ditch leading through Drury Gulch to the Buskin River also was diverted to minimize drainage through the site. Peyton said contaminated water was not an issue because workers tested around the ditch and found PCB levels below the legal clean-up limit for inhabited areas of 10 parts per million.

“PCBs have not been washing out, even while we were working,” Peyton said.

According to the EPA, the safe PCB limit for drinking water is 0.5 parts per billion. PCBs are not generally soluble in water, but can be highly concentrated in fish tissue. It is unsafe to eat fish from several areas of the U.S., including parts of the Hudson River, due to PCB contamination.

The Army Corps of Engineers will monitor the site for five years. Peyton said workers will check the soil cover for erosion and will continue to test drainage water.

After five years, the Coast Guard will be responsible for monitoring Drury Gulch.

“The site can easily be maintained and monitored by the Coast Guard,” Peyton said.

Mirror writer Elizabeth Caldwell can be reached via e-mail at ecaldwell@kodiakdailymirror.com.