HILL AIR FORCE BASE — Hill Air Force Base's environmental restoration team has picked up a $2.1 million tab to clean up potentially carcinogenic PCBs from soil in one area of base housing.

The team plans to ask the U.S. Air Force to reimburse Hill for the cleanup and to provide the base with a further $500,000 for follow-up operations.

In February, when Boyer Hill Military Housing tested the soil for pesticides around the homes, located on the base's west side, tests came back with polychlorinated biphenyls, or PCBs. PCBs 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.

Most of the contaminated dirt — about 3,600 tons — is gone now and replaced with clean fill, said Mark Loucks, the base's restoration-operations program manager.

What's left is a 10-foot-by-5-foot piece of land that will likely be decontaminated in early 2008, though the base's environmental team likely won't close the books on the PCB project until 2009.

The base is already in the midst of a restoration project to clean up trichloroethylene, or TCE, a degreaser used at Hill until the late 1970s.

Unfortunately, as great as TCE is at degreasing, it was 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.

This was the first PCB cleanup for the base in a residential area. Work began in September and wrapped up for 2007 when the weather turned bad, Loucks said.

At high levels, PCBs can cause a skin rash known as chloro-acne and have been shown to cause cancer in some lab animals.

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