After many years of watching and reporting about EPA scientists and others tracking the underground migration of the toxic chemical trichloroethylene (TCE) from leaking tanks in the vicinity of N. Whisman Road to the discovery of other "hot spots" hundreds, if not thousands of feet away, it is remarkable that even today, the extent of TCE contamination in the city's soil and groundwater remains unclear.
The latest thinking, though there is no conclusive proof yet, is that it is very likely that the mystery of how TCE managed to flow west of what was thought to be its boundaries has been solved.
It has long been known that the solvent that was spilled at the Fairchild plant on N. Whisman Road, and at other plants making computer chips, created an underground plume of contamination that appeared to be contained in an area bordered by E. Middlefield Road, Ellis Street and N. Whisman Road, and extending across Highway 101 north to connect with another large TCE plume left by the Navy at Moffett Field.
Then came the surprising discovery in 1982 that a deep well used by Joe Silva and his family for drinking water and in their farming operation was contaminated by TCE , in an area outside what was thought to be the boundary of the plume. The well on the Sherland Avenue property is about a block west of the MEW and was immediately shut down when it tested positive for high levels of TCE. But despite efforts to determine how the dangerous chemical found its way into a deep (465 feet) well, the mystery of how the chemical migrated over half a block west of what were thought to be its boundaries was never solved.
In late 2013 two more "hot spots" were found by EPA testing on Evandale Avenue, also west of the N. Whisman boundary of the MEW, and also along a sewer line. Two other significant hot spots of TCE were found even farther west, along the same sewer line, which makes it a near certainty that when early tech workers at Fairchild or other plants making computer chips poured TCE down the drain it found its way through sewer line connections, and produced vapors found by the EPA in a handful of homes in the area. More could be discovered if the Environmental Protection Agency continues to test along the sewer lines in the residential neighborhood west of Whisman Road, where small amounts of TCE have already been found along sewer lines on Easy Street and Tyrella Avenue, among others.
The latest discoveries show how little is known about this dangerous toxic chemical's presence in the city. It can seem contained in the North Whisman area and then be discovered blocks away, where in some cases, residents have lived with it in their homes for more than 40 years.
What is known is that prolonged breathing of the toxic vapors given off by underground plumes of TCE can cause birth defects, cancer and a host of other diseases, although it is nearly impossible to attribute individual cases of diseases directly to inhalation of TCE vapors in this area. And unless barriers have been installed in a home's foundation, TCE vapors from undiscovered hot spots have the potential to penetrate into living spaces, potentially exposing residents to increased health risks.
Another, more problematic hot spot, is the site of a large former military apartment complex -- Orion Park -- just outside the main gate at Moffett Field, torn down in 2009 and once home to hundreds of military families. A TCE plume in the ground water could have exposed families who lived in the apartments to toxic TCE fumes since 1968. The situation has eased somewhat since demolition of the complex, which was replaced by offices and training facilities. The Army contends that the since the area was a farm prior to 1968, cleanup of the TCE is not its responsibility.
But that conclusion was made before the recent discoveries, which strongly suggest that sewer lines are the conduits of TCE outside the MEW area. Lenny Siegel, a longtime local watchdog of toxic cleanups, told the Voice he has discovered a map showing a large sewer line located on the east side of Orion Park that had also once served Fairchild, where the TCE is said to have originated. No one knows for sure if the apartments were contaminated by the gas, but the discovery of TCE on the Orion site is certainly an indicator that some apartment-dwellers were breathing the toxic fumes for a long time.
It is remarkable that after so many years, residents and city officials are seeing strong evidence that TCE apparently migrated along sewer line corridors to sites far beyond the boundaries in the MEW. Now it is incumbent on the EPA to do more testing, using the sewer line maps to guide them, and for the city to fully cooperate in revealing the locations and flow directions of sewer lines then and now. It is difficult to imagine why no one suspected the sewer line's importance in tracking the spread of this dangerous chemical, but now it is clear that TCE can travel hundreds, if not thousands, of feet away from what was previously thought to be its definitive boundaries. And although TCE's half-life in open air is only about seven days, depending on conditions it is a stable compound underground and could last for 100 or more years.