EPA zeros in on sewer line polluters

In the investigation of the toxics found under homes on Evandale Avenue in 2012, the Environmental Protection Agency has narrowed the list of suspected polluters to three companies that had manufacturing plants in early 1960s Mountain View.

The EPA announced last week that it suspects Silicon Valley pioneer Fairchild Semiconductor, along with Raytheon and Union Carbide, for the “hot spots” of toxic trichloroethylene (TCE) that sat in the the groundwater and soil for decades along Leong Drive and Evandale Avenue.

The agency says the soil and groundwater contamination leaked out of sewer lines after it was dumped or leaked into the sewer by the companies. It caused at least two homes to have elevated levels of carcinogenic vapors inside that had risen from the ground (drinking water was not contaminated).

“EPA knows TCE was released and we know the companies that would have discharged TCE in this time frame,” said EPA project manager Alana Lee as she presented the investigation results to the Moffett Field Restoration Advisory Board on Feb. 12. “We’ve identified three MEW (Superfund site) parties: Fairchild Semiconductor, Raytheon and Union Carbide.”

The TCE leaked through the city’s clay sewer pipe, Lee said.

“The concentrations we are finding are very high, such that it was very likely that when it was discharged to the sewer, there were joints and sags in these lines that TCE would have infiltrated,” she said. TCE would have “sat in the clay pipe and would have leaked out.”

Key to the investigation were city records that showed the direction sewer lines flowed in the early 1960s.

“What was puzzling the EPA for a while, was looking at the current sewer flow,” Lee said.

Today, the only sewage that flows down Evandale Avenue is from homes on Evandale Avenue. That wasn’t the case in the early 1960s, the EPA soon found.

“The city of Mountain View has provided us with a tremendous amount of information about the history of the sewer lines in the area,” Lee said.

Fairchild, Raytheon and Union Carbide were the only companies using heavy amounts of TCE, an industrialist solvent, in the area between 1961 and 1966, when the Evandale sewer line also carried wastewater from the industrial area where the companies operated. That area is now known as the MEW Superfund site in the area of Middlefield, Ellis, and Whisman roads.

The EPA doesn’t suspect companies that operated in the area only after 1966 of being involved in the contamination. That’s because after 1966, sewage from plants in the MEW was carried along a new sewer main that ran along Fairchild Drive, as it does today.

Among the records the EPA found was documentation that TCE had reached the city’s sewer plant.

“In 1960 the city identified that TCE had reached this treatment plant, because TCE was killing the bugs (natural bacteria) at the treatment plant,” Lee said.

The main danger of the contamination is that vapors rise from the ground and get trapped indoors. Since discovering the hot spots, EPA has sampled the air of over 90 homes, at the request of owners and tenants. The two that were found with TCE vapors above the limit had special ventilation systems installed similar to those used for radon.

“EPA’s immediate priority was making sure residents were protected,” Lee said.

Homeowners on Leong Drive, across the street from a hot spot in a hotel parking lot, have refused to have their homes tested, Lee said.

“EPA would like to sample more on Leong Drive,” she said. “When we offered sampling, they (the residents) didn’t want to have their homes sampled.”

The EPA reports that exposure to TCE vapors can cause birth defects over a period of weeks, and cancer and a host of other health problems from longer-term exposures.

The investigation confirmed the suspicion that the sewer lines had carried the TCE to the hot spots, as the contamination was at the same depth as the sewer lines. Lenny Siegel and Peter Strauss of the Center for Public Environmental Oversight had raised that possibility shortly after the hot spots were discovered,

“I’m impressed,” Siegel said after Lee presented the findings. “That’s a pretty good forensic job you seem to have done.”

Lee called the investigation “well over 10 years in the making.”

Representatives of Raytheon, Fairchild and Union Carbide could not be reached for comment by press time.