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Deep Trouble

percolation ponds
Christopher Gardner

Still Waters: In the percolation ponds along Los Gatos Creek, runoff from the Santa Cruz Mountains seeps into underground reservoirs used for drinking water.

The valley's water supply comes from an aquifer that has been contaminated by hundreds of chemical spills. While the water district contends that none of these toxins are getting into tap water, others are less confident.

By Christopher Weir

Geological good fortune has, over the years, provided fairly good protection for the Santa Clara Valley's water supply. "There's a layer of clay, about 50 feet thick, that separates the shallow ground water from the deep aquifer," says Wilfried Bruhns, resources control engineer with the regional water board. "And it's the deep aquifer that's used as a supply."

Nevertheless, the buffer is not impermeable.

"There are a lot of abandoned wells that nobody knows about, that were never recorded," says Mike Di Marco, spokesman for the district. These deep wells, which once fed farms and orchards, can act as fast pathways for contaminants to seep from the ground-water zone into the aquifer below.

More than 400 such wells were sealed during a district program that ended in 1991. But Di Marco says the district continues to search for potentially troublesome wells.

On the fringes of the valley, the clay barrier recedes, yielding more direct access between surface and aquifer.

"That's why they had such a problem at Fairchild," Bruhns says. He is talking about Silicon Valley's moment of environmental reckoning, which descended with brute force 16 years ago when South San Jose's Fairchild Camera and Instrument Company determined that 60,000 gallons of solvent-tainted water had slowly leached from an underground waste-storage tank and contaminated a public well.

The county's squeaky-clean high-tech image was subsequently soiled by a methodical discovery process that eventually implicated some of the valley's biggest corporate names and put 29 locations in the valley on the federal Superfund list alongside the nation's most toxic sites.

While the Fairchild incident has been largely forgotten, the water-consuming public has not fully regained confidence in the public water supply.

"I understand that there's still a lot of concern on the part of people who believe that water should be 100 percent pure," says Scott Yoo, vice president of water quality for San Jose Water Company, the county's largest water retailer. "But in terms of the amount of risk associated with water from any large public water system that meets drinking water standards, I think it's absolutely safe."

Ted Smith, executive director of the Silicon Valley Toxics Coalition, says he doesn't believe that to be the case.

"They [water company officials] want to be able to tell people that it's OK and that things are under control," Smith says. "I wish that were the case, but it's not."

In the five years following the Fairchild disclosure, the Santa Clara Valley was found to be riddled with similar site contaminations, although most were confined to a shallow ground-water zone not tapped for municipal drinking water. In addition to the 29 entries on the Superfund list--the highest number for any county in the nation--more than 200 other sites have also been identified with soil and ground-water contamination.

Storage tank reforms, enhanced regulatory oversight and expanded testing procedures have since drastically reduced the leaching of toxic solvents into the environment and improved the protocols for contaminant detection. But the degree to which the problem has been addressed remains a matter of intense debate.

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Metro reporters dip into the waters of the bay, the underground aquifer and the tapwater of Silicon Valley to reveal what's real and what's imagined in the local H2O.

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Depth Charge

GOVERNED BY the San Francisco Bay Regional Water Quality Control Board and administered by the Santa Clara Valley Water District, most of the county's drinking water supply is pumped from the deep aquifer, while the Hetch Hetchy reservoir supplies the northernmost area of the county.

A vast network of reservoirs, ground-water recharge ponds and water treatment plants integrate and distribute the water sources. Thirteen water retailers purchase water from the district and/or pump ground water under permit from the California Department of Health Services.

In areas of heavy contamination, the mass of escaped toxic materials is prone to diffusion over time. Depending on the particular chemicals and the geological environment to which they are confined, leaked solvents have formed contaminated underground plumes that disperse at varying rates. That means they invade neighborhoods far from the spills.

"A lot of these solvent leaks have spread many miles underground," Smith says. The IBM plume in South San Jose extends more than three miles and has forced the closing of 17 public wells.

Often, the task of tracing deep-aquifer pollutants backward to a particular site is tricky, if not impossible. Consequently, all of the federal Superfund sites are watched closely so officials can follow the toxic plumes. The district's Wellhead Protection and Groundwater Monitoring programs also monitor affected areas.

According to Yoo, this diligence has paid off. "We have in California some of the most stringent drinking water standards in the nation and the world," he says.

Di Marco echoes Woo and says objective analysis supports his contention that the water is safe. "Public agencies don't rely on themselves to set these evaluations," he says, "they rely on good science."

Smith, however, maintains that "significant scientific uncertainties" jeopardize the notion of conservative standards. "Hardly any of these chemicals have been tested for all major health outcomes," he says, noting that standards are based primarily on carcinogenic factors, not neurotoxicity, hormone disruption or immune system impacts.

The valley's most abundant poisons are volatile organic compounds --TCA, TCE, DCE, Freon 113--all of which are subject to federally mandated "maximum contaminant levels" (MCLs) in drinking water. In addition, more stringent "action levels"--unenforceable guidelines--suggest when contaminants are reaching unsafe levels.

"The MCLs are not set at a safe level," Smith argues. "They're set at what they call the 'acceptable risk' level, which means that they are going to potentially harm some people.

The people who will be impacted, Smith says, are the ones who can least afford the damage.

"They don't set these levels based on the most vulnerable parts of the population--babies, the elderly, those with damaged immune systems--but rather on the average population. The impact of low levels of those chemicals on these people is going to be a lot more significant than it is on a 35-year-old healthy adult."

Smith says regulators are promoting a "Don't worry, be happy" approach rather than saying, "Here's the information we have, this is what we think it means, but there's a lot of uncertainty that you need to be aware of, and here's what the parameters are of the uncertainty."

Yoo, however, says that in addition to complying with the federal Safe Drinking Water Act and state laws, San Jose Water Company maintains excellent communication with its customers. "All of the water retailers and public water suppliers are obligated to report annually to their customers on the levels of contaminants in the drinking water."

The origins of such state-mandated annual reports, Yoo says, can largely be traced to the voluntary communications efforts forged by local water retailers in the 1980s.

"There was a lot of misinformation out there," he says. "There were news stories about shallow ground water and soil contamination, and people were drawing conclusions that it meant the drinking water was contaminated. That's when we decided to provide annual water quality reports."

"Do we tell people when we find one or two parts per billion of a chemical, even though it may be well below the action level or drinking water standard? The answer is absolutely yes. People have a right to that information."

water tower
Water Marks: In the valley's agricultural past, wells and water towers, such as this one that remains in Campbell, were used to irrigate crops. After the advent of the high-tech industry, these old wells carried toxic chemicals from shallow groundwater levels to deep drinking-water sources below.

Photo by Christopher Gardner



New Crud on the Block

MEANWHILE, new threats to the valley's ground water are emerging, most notably the fuel additive MTBE. While MTBE has been available as an octane booster for more than 20 years, its clean-burning properties became integral to regional air quality compliance under the federal Clean Air Act of 1992. Last year, the state stipulated that all gasoline sold in California must be reformulated, and the chemical agent of choice was MTBE.

According to Di Marco, MTBE now composes 11 percent of the local gasoline supply. Yet despite approval from the U.S. Environmental Protection Agency and certification by the National Academy of Sciences, MTBE's impacts on the environment and public health are not fully understood.

"We've embarked on a really aggressive campaign to monitor and look for MTBE," Di Marco says. While the compound has been detected at more than 250 leaking underground fuel storage sites, he says, "No drinking water sources have been contaminated."

Such contamination may be just a matter of time, however. Unlike many solvents, MTBE dissolves easily and moves efficiently through soils, evading natural filtration processes. Current treatment technology cannot remove MTBE from drinking water.

In Santa Monica, the discovery of MTBE concentrations far above the threshold of concern shut down more than half of the city's ground-water supply last June.

Despite reforms such as double -walled storage tanks and leak alarms, Di Marco says, "There are still problems with piping or with delivery trucks overfilling tanks. Our program is focusing on those problems."

Di Marco says that while there are no harmful levels yet established for MTBE, the chemical is listed as a possible carcinogen. "We're really racing the scientific data to try to protect the ground water," he says.

Smith suggests that uncertainties regarding MTBE illuminate a broader lack of understanding about many potentially harmful chemicals found in the local environment. Among those, he cites a body of pollutants known as glycol ethers.

"It's a concern that's been unaddressed," he says. "Like MTBE, glycol ethers are undetectable through normal testing protocols. Like MTBE, they are extremely toxic. I'm concerned that they're out there in the drinking water, that people are ingesting them, and at God knows what levels."

Nevertheless, county water managers rate high marks in regulatory circles. "My sense is that they've taken steps earlier than a lot of people have to assess their situation in regard to water quality and identify where problems exist," says Michael Perrone of the state Water Resources Control Board. "They've been pretty active and forward-thinking. We've got a lot of people in the Central Valley walking around with their eyes closed on these problems."

Smith, however, contends that there's still some eye-opening to be done on the local front. Citing several large companies' reluctance to adopt "closed loop" manufacturing procedures that would halt all toxic discharges into the environment, he says, "Maybe they need to redefine what 'cost effective' means when it comes to the environment. Maybe people need to remind them that continuing to dump their waste products into the environment is really short-sighted and that it's an assault on nature and public health."

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From the Sept. 11-17, 1997 issue of Metro.

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