HILL AIR FORCE BASE — Hill Air Force Base officials expect to remove up to 1,800 cubic yards of soil from an area of base housing where a potential carcinogen was found earlier this year.

The cleanup process, which involves removing 4 feet of earth, testing for contaminants and filling the hole with clean soil, is expected to be completed mid-November, said Ray Spencer, the base's construction manager for the cleanup.

Spencer is charged with overseeing the removal of polychlorinated biphenyls, or PCBs, from Area F of the base's housing. About 100 homes are in the area, though only a handful of those are directly affected.

In February, as Boyer Hill Military Housing tested the soil for pesticides around the homes, located on the base's west side, tests came back with PCBs, which are a mixture of 209 chemicals that were produced until 1977 and were used as an insulating material in transformers and other electrical equipment.

During the 1970s, in an area northwest of Area F, the base had a storage yard, and officials theorize that transformers sitting outside could have leaked PCBs. Later, when the yard was altered, some of the dirt from the area could have been used as fill when homes were built in the 1970s.

PCBs did a good job, just as did trichloroethylene, or TCE, a degreaser used at Hill until the late 1970s.

Unfortunately, as great as TCE is at degreasing, it was also found to be a probable carcinogen.

Waste TCE, which was dumped in chemical pits for decades, eventually contaminated a shallow aquifer in the seven cities surrounding the base and landed Hill Air Force Base on the U.S. Environmental Protection Agency's National Priorities List. It was declared a Superfund site in 1987.

The base is now cleaning up TCE from the shallow groundwater plumes on and off base, a cleanup job expected to take 65 years at least.

PCBs also fall under Superfund guidelines.

The PCB cleanup will involve removal of contaminated soil in areas where PCBs have been detected at levels above 1 part per million, Spencer said. The soil will be taken to Clean Harbors' Grassy Mountain facility in western Tooele County.

Barbara Fisher, spokeswoman for Hill's environmental restoration, said that of the 18 homes affected, seven homeowners have opted to temporarily relocate to other housing units or to a hotel off base. Four of the units are vacant.

Spencer said that if sampling comes back with PCB levels higher than 1 ppm, more soil will have to be removed, or, if it's deeper than 4 feet, the contractor can place a concrete cap over the contaminated soil before clean dirt is brought in.

E-mail: jdougherty@desnews.com