Toxic chemicals from an old Navy air station at the Monterey Peninsula Airport have been contained and cleanup efforts are proving successful, federal officials told residents of the Casanova Oak Knoll neighborhood Thursday.
Treatment systems have processed close to 46 million gallons of water, reducing levels of trichloroethene (TCE) by about 65 percent and levels of other industrial lubricants by 83 percent, said officials from the Army Corps of Engineers.
Residents, whose grassroots efforts forced the cleanup in 2003, were told 25 pounds of TCE had been removed from the groundwater beneath the airport and their neighborhood. Gerry Vincent, program manager for the Army Corps, said the cleanup process is preventing remaining contamination from spreading.
Groundwater in the Oak Knoll neighborhood, which is contaminated with TCE, is extracted from the ground, run through a carbon filtration system, treated with hydrogen peroxide and reinjected into the basin.
Separate plumes of TCE and petroleum contamination under the airport are being treated through "co-metabolism." Water from the plumes is combined and the incompatible compounds essentially eat each other, Vincent said. The water is further treated and reinjected at the airport's lower property line, creating a "hydraulic curtain" that prevents a downward flow of contamination.
"This is a one-of-a-kind process, that we know of, in California," Vincent said. "It's been very successful."
He estimated cleanup of the neighborhood plume could be completed in three to five years, while it could take 10 to 13 years to finish the cleanup of the more heavily contaminated airport plumes.
Richard Rucello, president of the Casanova Oak Knoll Neighborhood Association, said he and other residents are pleased with the progress of the cleanup and feel confident the contamination poses no threat to them.
"You name it, we did it," he said. "We made a list of separate concerns and the Army Corps went through and tested. There's no pathway to humans in the plume that is under our neighborhood. You've got to drink it or breathe it and all of our drinking water comes from (California American Water).
"When we started in July 2000, there was no standing room in the community center," Rucello said. "Now, very few people show up for the meetings."
The contamination is the remnant of aircraft-maintenance operations at the former Naval Auxiliary Air Station that was on the airport property from 1942 to 1983. When the station was declared a "formerly used defense site" in 1990, the Army Corps was put in charge of identifying potential environmental impacts.
In 1998, the corps uncovered a plume of TCE beneath the airport, but failed to notify authorities. Residents learned of the contamination in 2000, when the discovery was reported in The Herald.
The corps eventually identified TCE beneath the airport and the Casanova Oak Knoll neighborhoods, as well as a plume of petroleum products beneath the airport.
While authorities said there was no threat to the homes from soil or gas contamination, and none of the area's groundwater was used for drinking, the groundwater far exceeded the federal drinking water standards of 5 parts per billion of TCE.
Tests showed the water under the Oak Knoll neighborhood, home to 1,850 residents, contained 220 parts per billion of TCE. Levels under the airport were as high as 3,400 parts per billion.
After a three-year fight by Oak Knoll residents, the Army Corps agreed to decontaminate the groundwater in 2003. Since that time, residents were told Thursday, levels of TCE beneath the airport have dropped 64 percent, while the benzene levels of the petroleum plume there have dropped 83 percent.
Under the Casanova Oak Knoll Community Center, where a meeting was held Thursday night, TCE levels have dropped by 65 percent to 70 percent.
Benzene is a known carcinogen. TCE, known to cause cancer in animals, is also a suspected human carcinogen.
Copyright 2005 Associated Press