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New Marin Subdivision Gets MTBE Warning
Sales brisk despite disclosure

Jim Doyle, Chronicle Staff Writer 	 	Sunday, February 25, 2001  
  
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Developers of a Marin subdivision are offering upscale homes to prospective buyers with a surprising catch: Don't plant any fruit trees here. 
And contractors would be well-advised to wear haz-mat boots and coveralls when digging a hole in the backyard for a pool. 
In the groundwater beneath the partially completed Hamilton Meadows sits a toxic plume of MTBE, a suspected carcinogen that does not break down easily in the environment. First detected five years ago, the plume migrated to the site from a Navy gas station's leaking underground storage tanks. 
Developers of the subdivision -- which will include 235 spacious, executive- style homes being offered for sale at prices of $579,000 to $640,000 -- insist that the land is safe for families. 
And contamination of groundwater at the Novato development, located at the site of the decommissioned Hamilton Field, has apparently not discouraged home buyers. 
"Sales have been phenomenal," said Thom Gamble, executive vice president of Shea Homes, based in Livermore and one of the nation's largest home builders. Nearly all of the first 80 homes in the subdivision have been sold. 
Others see cause for alarm. 
"It's really outrageous that the state government and the military would allow the construction of homes in an area that has been contaminated," said Russell Long, director of Blue Water Network, a San Francisco organization that has lobbied against MTBE. 
The additive MTBE, which stands for methyl tertiary butyl ether, makes gasoline burn more cleanly but has been blamed for contaminating groundwater throughout California. 
Because of its solubility, mobility and persistence, MTBE can travel swiftly through the ground to deep underground aquifers. In recent years, the long-lasting, foul-smelling toxic chemical has become one of the nation's most notorious water pollutants. 
Gamble said this is the first time in Northern California that his large company has disclosed to buyers an MTBE contamination, but he expects such disclosures to become increasingly common. The notice to buyers was required by a state water agency. 
"I personally feel that MTBE is one of our environmental nightmares," said Gamble, whose company bought the acreage at Hamilton Field despite its toxicity problems. "It's going to be prevalent in a lot of places. . . . As you come back into the urban areas (to build), a large portion of those properties will have some sort of contamination, either in the groundwater or the soil." 
The Navy has found MTBE at various concentrations in the subdivision. The samples from some sites show negligible levels, but one test -- of a sample taken within a few hundred feet of new home sites -- found the chemical at 12, 000 parts per billion (ppb) in the groundwater. The state's drinking water standard for the chemical, which smells like turpentine, is 35 ppb. 
Navy consultants say that there are little or no MTBE vapors in depths of less than four feet at the homesites and that chemical levels have been reduced to the point where they do not pose unacceptable health risks. 
The Navy believes all the proper measures have been taken. "Our primary concern always is the health and safety of the public and the environment," said Navy spokesman Lee Saunders. 
Shea Homes sales brochures for the new Sunny Cove and Newport neighborhoods contain no mention of toxics. But when purchasing a home, buyers are advised in writing of the potential health risks. 
Property owners in two-thirds of the lots must sign a disclosure statement that warns them not only of the MTBE plume but also of cancer-causing benzene contamination from the gas station and high levels of methane gas and other toxics at a nearby landfill. 

RISK TO RESIDENTS

The disclosure informs buyers that "there may be a risk to construction workers from potential exposure to soil and groundwater and to residents who ingest fruits and vegetables grown in areas situated above the MTBE plume." 
It also advises them not to plant deep-rooted fruit trees. 
"The root systems of the fruit trees might extend to the depths where MTBE is present in a significant concentration," it states. "In this case, MTBE . . . could be ingested if the fruit is eaten. This exposure could pose some additional health risks . . . ." 
Home buyers must sign a covenant that prohibits them from digging wells and trenches. They must also promise to notify subsequent property owners "that hazardous materials are located on or beneath the property." 
The U.S. government, which is liable for the MTBE spill, reserves the right to re-enter the property to monitor and clean up hazardous wastes. 
This doesn't seem to have alarmed home buyers. 
"I'm not really interested in planting fruit trees," said Caroline Callahan, 
a new homeowner. "But I am a little surprised that they didn't clean it up first before developing it." 
Callahan also said she doesn't fret over MTBE, in part because she chose a lot on a slightly elevated slope several hundred feet from the plume. 
Ken Rudo, toxicologist for the state of North Carolina, which has suffered a slew of MTBE-related problems, agrees. "As long as they're not drinking it or bathing in it, I don't think it poses a health risk," he said. 
Nonetheless, the California Regional Water Quality Control Board crafted the disclosure and covenant to deter home buyers from coming into contact with the polluted groundwater. Long of Blue Water Network said such a warning isn't enough. 
"At some point, homeowners will grow trees, drill the soil or find other ways of becoming exposed to this pollution," he said. "The state's policy should be to protect public health, not increase public risk. The military should take responsibility for cleaning up this site." 
When the Air Force vacated Hamilton Field in 1975, the area was divided among the Army, Navy and Coast Guard. 
In 1996, the Navy discovered the MTBE plume in a low-lying area where the ground becomes saturated with rainwater during winter storms. 
Engineers concluded that the source was leaking underground fuel storage tanks at the Navy Exchange service station, which was about a quarter-mile from the subdivision and had closed four years before. 

HISTORY OF PROBLEMS

The Navy's Autoport gas station was a few blocks from Hamilton Field's main gate, near a commissary and post exchange. After it closed in 1992, the Navy found high levels of benzene in the water table nearby. The Navy monitored the carcinogenic plume but did not clean it up. 
Navy contractors later identified the MTBE leak after removing the station's underground fuel tanks. They installed monitoring wells to track the contamination. 
In 1998, contractors reduced MTBE levels beneath the gas station by pumping air into the groundwater, extracting vapors and removing 23,000 pounds of gasoline. That effort was discontinued a year later because of its cost. 
Last summer, the Regional Water Quality Control Board ordered the Navy to further clean up the plume. Navy consultants are conducting more studies to propose cleanup options to the board, which will decide what level of MTBE is acceptable. 
The leaking chemical has been found in the water table within 50 feet of the North Bay Children's Center, a day-care facility with an outdoor playground. It has also been found within 100 feet of a parcel where Novato Charter School plans to build a new campus for 220 children. 
The half-mile-long MTBE plume has migrated northward in the aquifer to a landfill, and has also intersected Pacheco Creek, which flows through a wildlife preserve toward San Pablo Bay. 
The contamination has delayed the transfer of Navy land near the gas station, the site of a planned shopping center. 
Shea Homes' Gamble said the plume beneath the new subdivision is at "extremely low levels compared with what's at the gas station." 
"The plume is in the groundwater, not in the soil," Gamble said. "All the studies that have been done showed that everything is fine. I don't have a concern with the MTBE. There's full disclosure on that. Just don't pierce the groundwater." 
$1 MILLION SPENT 
Tom Macchiarella, the Navy's coordinator of the gas station cleanup, said about $1 million has been spent on engineering studies, groundwater monitoring and remedial work at the site. 
"The plume's length is generally not increasing," Macchiarella said. "We believe that it is undergoing anaerobic biodegradation" -- a natural process in which microbes break down the contaminant and render it harmless. 
Across the nation, MTBE has proven to be a vexing problem. 
In California, the chemical has leaked from underground fuel tanks and contaminated 10,000 shallow groundwater sites, including more than 1,000 in the Bay Area. It has also been found in dozens of state lakes and reservoirs. And cities have been forced to cap tainted wells. 
Less than a mile from Hamilton Meadows, a leaking gas station outside the airfield was responsible for an MTBE plume that contaminated a drinking well at a Novato trailer park. 
MTBE was first used in the late 1970s as an octane enhancer for premium- grade fuel. In 1991, the Environmental Protection Agency ordered the use of oxygenates, such as MTBE, in gasoline in areas that do not meet state and federal clean-air standards. 
In 1999, after a state-sponsored study found that there were enough serious health and environmental risks associated with the chemical, Gov. Gray Davis issued an executive order calling for a complete ban on MTBE by the end of 2002. 
Macchiarella said the Navy hopes the MTBE plume will decay naturally. But its computer models predict that, if the plume resists decay, it could migrate like a slug through the aquifer and still exist in 40 years. 
Although he maintains that the subdivision is safe for residents, Gamble is also pressing the Navy to do more. 
"They're trying to wash their hands of it," Gamble said. "They're taking the stand that there are no environmental problems if you do proper deed restrictions."
E-mail Jim Doyle at jdoyle@sfchronicle.com. F