The Sunnyvale Sun

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Polluted site in Cupertino could impact local water

EPA says Superfund site cleanup is ongoing, will take many years

By HUGH BIGGAR

Authorities say remedies for cleaning up contaminated groundwater and soil at a 15-acre toxic waste site on the border of Sunnyvale and Cupertino are working.

The city of Cupertino is in the process of redeveloping that neighborhood known as North Vallco, and Apple Computer is planning to build a second campus there. With those projects in development, authorities say two decades of cleanup at the sites at 10900 N. Tantau Ave. and 19000 Homestead Road are slowly paying off.

"That's my understanding," said Roger Papler, a geologist with the San Francisco Bay Region Water Quality Control Board, which is overseeing cleanup work at the Superfund site. Papler said the complete cleanup process, though, could last 50 to 300 years, in part because of the nature of the subsoil, which causes contaminants to adhere to it.

After a five-year review completed in September 2005--the third such review--the water board issued a report stating, "After almost 20 years of groundwater

extraction, the amount of [volatile organic chemicals] being removed has declined considerably and concentrations in the groundwater have declined to safer levels."

Off-site, the groundwater plume has migrated across Homestead Road to Sunnyvale, roughly along Teal Drive and Kensington Avenue. The water board's report says the area is meeting cleanup goals stating,, "The cleanup actions are functioning as designed and achieving positive results by maintaining hydraulic control of [water migration] and reducing VOC concentrations in ground water."

Due to previously unsafe levels of potentially cancer-causing toxins in the soil and groundwater, the federal Environmental Protection Agency designated the locations as a Superfund site in 1982. Superfund sites are those that are national priorities for cleanup due to risks posed to human health and the environment.

Since then, Siemens, Intersil and the Water Quality Control board have scoured the area to remove contaminants used by the former owners in manufacturing semiconductors. That work has included removing, vaporizing and treating soil and pumping out contaminated groundwater. The companies also removed underground storage tanks and have ceased operations at those sites.

Some of those toxins leaked or spilled into the soil and groundwater from underground storage tanks. The spills migrated offsite to the north and also affected local waterways such as Calabazas Creek and drinking water supplies of Santa Clara, Sunnyvale and Cupertino. According to the EPA, the groundwater has since been cleaned up equal to currently accepted drinking water standards.

The leaked or spilled chemicals included highly toxic degreasing agents and solvents such as chemical trichloroethylene, or TCE. On its website, the EPA says TCE, a volatile organic compound, can cause many forms of cancer and adverse health effects such as developmental, liver and kidney toxicity.

The board plans to continue monitoring the site until all cleanup goals are achieved. The next scheduled review is for 2010.

The Silicon Valley Toxics Coalition, a local watchdog group, said it had not been following the Cupertino Superfund site closely enough to comment.