A carcinogen used in dry cleaning and household cleaners has
turned up in two Gilroy wells, but city leaders say its levels are
harmless and do not justify clean-up costs.
Gilroy – A carcinogen used in dry cleaning and household cleaners has turned up in two Gilroy wells, but city leaders say its levels are harmless and do not justify clean-up costs.
Trace amounts of tetrachloroethylene, a liquid found to cause liver damage with long-term exposure, were measured below levels that would force closure of the wells but in high enough quantities to trigger public notification requirements set by the California Department of Health Services.
The two wells with detectable amounts of the chemical, commonly known as PCE, are located near Nob Hill and close to downtown. Water from those wells blends with six others scattered across the city before reaching faucets in homes and businesses across Gilroy.
Though drinking water remains safe, city officials say the toxin’s presence still exceeds the public health goal set by the California Environmental Protection Agency.
“If you can detect it, you have to report it,” said City Administrator Jay Baksa.
The public health goal is a basic standard that translates to the lowest level of detectable contamination and marks the beginning of known health risks, according to a mandatory report presented to the city council by Dan Aldridge, Gilroy’s water services supervisor.
Dan Aldridge, Gilroy’s water services supervisor, was unavailable for comment Wednesday, but his report concludes that any health risks from the contaminated water are negligible.
Carla Ruigh, Gilroy’s operations services manager, works with Aldridge and said the source of contamination for the wells, located at Monterey Street and IOOF Avenue, and First and Princevalle streets, remains a mystery. Previous national research has fingered dry cleaning operations, she said, adding only that “we don’t know what caused it here.”
State regulators have set the maximum contamination level for PCE at 5 parts per billion, roughly equivalent to a teaspoon of water in an Olympic-sized swimming pool. The highest level of PCE detected in either of the wells in the last three years was 2.9 ppb, measured in September 2005. Since 2004, contaminant levels have fluctuated, with an average of .16 ppb. That figure is more than double the public health goal of .06 ppb.
“It is pretty sporadic as far as I understand it,” said Ruigh, referring to pollution levels since 2004. “There is no pattern and no indication that levels are going up.”
Out of more than 500 wells in Santa Clara County, the two in Gilroy are the only ones with detectable levels of PCE, according to Tom Mohr, a hydrogeologist with the Santa Clara Valley Water District and manager of perchlorate clean-up in Morgan Hill.
Former road flare manufacturer Olin Corporation has been under state orders since 2003 to supply bottled drinking water to hundreds of residents in Morgan Hill and San Martin as a result of perchlorate contamination stretching from its former plant off Tennant Avenue.
“Perchlorate can cause problems with the thyroid in a short period of time,” Mohr said, “whereas the solvent that Gilroy is talking about is called a chronic contaminant, in that it takes a very long time to cause any problems.”
Mohr attributed the lack of PCE contamination elsewhere in the county to tough enforcement during the past 20 years. The crack-down on regulation of PCE and similar industrial solvents began in the ’80s, after a number of spills by electronics manufacturers in Silicon Valley.
When a local government like Gilroy falls short of the public health goal on PCE or other substances found in the groundwater, the City Council must hold a public hearing, which it did briefly last Monday before deciding that the estimated $1.8 million it would cost to bring the toxin in step with the public health goals is better spent on further monitoring.
