Four months after the U.S. Environmental Protection Agency stepped in to oversee a contaminated triple site in north Sunnyvale, it is now asking if it may step into your home.

The EPA is requesting permission from certain residents in the Duane and San Miguel neighborhood to collect indoor air samples this winter.

The EPA must get permission from homeowners and renters to perform the free of charge air sampling as part of a study that will look at the potential for vapor intrusion–a process in which vapors from groundwater contamination may migrate into the indoor air.

A community meeting was held Dec. 10 in the multipurpose room of San Miguel Elementary–one of four schools located within the contaminated area–to provide residents with more information about the sampling study.

Known as the “Triple Site,” the contaminated area in north Sunnyvale includes three contaminated groundwater sites at the Advanced Micro Devices location at 901 and 902 Thompson Place, the Philips (formerly Signetics) site at 811 E. Arques Ave. and 444 N. Wolfe Road, and the TRW Microwave Superfund Site.

Volatile organic compounds (VOCs) were discovered in 1981 from leaking underground acid neutralization tanks on the former AMD property. Initial investigation at the Philips site began in February 1982 with the detection of a leak in an underground waste solvent storage tank.

The companies have been working to contain and clean up the contaminants, but this past year the EPA strengthened its protective levels for Trichloroethene (TCE). While TCE is found in the groundwater, it does not affect the drinking supply. As a precaution, the EPA would like to test to see if there is a buildup of TCE in the area.

TCE is a type of volatile organic chemical, which can move as vapors from groundwater through soil. If levels are high enough and prolonged enough, it may create a health risk, such as organ problems in babies whose mothers were exposed during the first trimester of pregnancy.

“It sounds scary; it”s a scary chemical, but something could be done about it,” Lenny Siegel, executive director of the Center for Public Environmental Oversight, said during the outreach meeting. “And the first thing to do is to open up your home to the people who are here to work.”

There are more than 100 residences and at least four schools within the 100-acre area that spans from E. Arques Avenue to Lakehaven Drive.

It is one of five federal Superfund sites in Sunnyvale.

The EPA reported indoor air sampling has been conducted every year at the Montessori school buildings on Duane Avenue, and results continue to meet EPA requirements.

However, with the agency recently strengthening its protective levels for TCE, concentrations of the contaminant in the shallow groundwater in the area are slightly elevated above the acceptable level of 5 micrograms per liter.

The EPA is requesting to place a sampling device in homes and buildings for a 24-hour to two-week period. It would then notify each home of the results, and if they do exceed EPA”s health-based screening levels, the EPA will present options to each resident as how to proceed.

“We would first need to find where is it coming from in your home; it may be coming from the ground or you might already have it in home, which is possible,” said Melanie Morash, EPA project manager.

TCE can be found in household products such as old spray bottles of degreaser or even nail polish remover.

If the source is coming from under the home, however, the first step would be to ventilate the home, Morash added.

“We would open the windows and doors to make sure fresh air is coming in,” Morash said. “A system can be also installed at no charge, but that would ultimately be up to the homeowner. The goal is to break the vapor barrier.”

For more information about indoor air sampling, visit epa.gov/region9//triplesite or contact Melanie Morash at 415.972.3050 or morash.melanie@epa.gov.