MOSES LAKE - The U.S. Environmental Protection Agency (EPA) began a long term project this month to clean up a heavily contaminated area, or "superfund" site, north of Moses Lake.

The Moses Lake Wellfield Contamination Superfund Site includes contaminated groundwater and soil areas on the old Larson Air Force Base, Grant County Airport and south of the airport, according to Suzanne Skadowski, community involvement coordinator with the EPA.

The area was identified for critical, long-term cleanup in 1988 when the state found an industrial solvent called trichloroethylene (TCE) in three municipal wells in the area. TCE was reportedly used to strip paint from airplanes, wash airplane parts and clean missile parts during the 1950s and 1960s.

Most residents in the area now get their water from the city's municipal system, which is regularly monitored to assure safe drinking water standards, although, according to the EPA, five homes in the area do use well filters to remove TCE from their drinking water.

The superfund cleanup project is expected to take several years and aims to treat the area's groundwater to provide another drinking water source.

"TCE is not too hard to get out of the water," said EPA Superfund Project Manager Rod Lobos. "The biggest thing is getting a system designed to get it out of the ground and then, once it's up, we can treat it pretty easily."

Lobos said agency contractors are now drilling new monitoring wells and, over the course of the summer, will test and design a groundwater treatment system to remove TCE from two large groundwater plumes stretching south from the Larson area.

It's still unknown exactly how large or deep the plumes are, he said, which is another reason for the wells.

"To put the system in exactly the right place, we need to drill these wells to see where (the plume) is at and align the system where we can get the best understanding of how much contamination is in the groundwater," he said. "Our experts along with contracted hydrogeologists look at what the plumes look like and get an educated idea of where we should drill next."

Phase one of the project targets the south plume, which is closer to homes with private wells, and phase two will switch the focus to a larger plume to the west, Lobos said.

This summer and next year will be given over to groundwater monitoring and development of the treatment system. By 2014 the EPA plans to install extraction wells and start the treatment system, which will stay in place until the water meets EPA's safety standards.

"Once the whole process is done this will be usable as drinking water," Lobos said.

The agency is also beginning a long-term soil cleanup of 12 former dumping sites on and around the former Larson Air Force Base.

The EPA will clean up two of the sites first since they are contaminated with TCE, petroleum, toxic metals and other hazardous chemicals, Skadowski said, adding one of the dump sites is the likely source of the southern groundwater TCE plume.

The Moses Lake Wellfield Superfund site has been on the EPA's national priorities list for 20 years, during which time the agency and the Army Corps of Engineers have been monitoring private wells for contamination.

Four years ago, the EPA issued the final cleanup plan and, in 2010, signed a settlement with Boeing, Lockheed Martin and the City of Moses Lake to have them pay a combined $3.25 million toward the project, with the federal government agreeing to pay $55 million.

According to a 2011 Columbia Basin Herald article, the city was required to pay $750,000 toward the cleanup because its Larson wastewater treatment facility was viewed as a potential pollutant. The city's insurance company paid the amount but, at the same time, the city received $3 million in damages through the settlement, the article stated.