Underground Tank Leaks in S.D. Cited
Gasoline and other potentially toxic substances have leaked from faulty underground tanks and into the soil and water supply of San Diego County at least 859 times over the past four years, statistics show.
Although most of those leaks have posed no direct environmental threat, two of them have forced health officials to advise some residents in Ocotillo Wells and Santa Ysabel to switch to bottled water because their drinking wells were found to contain gasoline and high levels of carcinogens.
A third spill from an underground tank at a Borrego Springs resort has health officials concerned that gasoline could spread to nearby wells used for the drinking water supply in that East County community.
Typical of Most of the Region
“I think San Diego is probably typical of most areas in Southern California,” said Victoria L. Gallagher, a senior hazardous-materials specialist with the county health department. “There is a significant amount of leakage from tanks.”
Preventing leaks from the underground tanks was the aim of a state law that went into effect in 1984 and requires local environmental agencies to test underground tanks for “tightness.” It requires that older tanks be retrofitted with permanent monitoring devices, and dictates that any new tanks installed underground must have double walls and double piping.
The law was inspired by an incident in San Jose in 1981, when 50,000 gallons of a highly toxic solvent leaked from the Fairchild Camera and Instrument Co. into the drinking water of thousands of residents.
But a Times survey shows that, three years after the law’s deadline, local regulators are lagging far behind in implementing what the Legislature had in mind. Only about half of an estimated 142,000 subterranean storage tanks in the state have been tested by local environmental agencies.
The result: Potential environmental hazards leaking from the tanks are going undetected.
San Diego County health officials, however, say they’ve been more conscientious than most in implementing the law. Currently, the county employs 25 people to handle permits, inspections and cleanups from the underground tanks, said Gallagher.
‘Ahead of Most Counties’
“We’re ahead of most counties--you could say all counties--in implementation of the law,” she said. “So we’re discovering a lot of leaks.”
Gallagher estimated that the health department has ordered routine tightness tests on 90% of the estimated 7,500 subterranean storage tanks in the county. Permanent monitoring devices have been installed on 5,000--or 66%--of the tanks.
Despite the aggressive campaign, or maybe because of it, Gallagher said the county has recorded 859 leaks from underground tanks.
Of those spills, 63 have been known to seep into underground water supplies considered safe enough to drink, county statistics show. In 571 of the cases, only soil has been contaminated.
“There have been only a few cases, a handful of cases, where drinking water was affected,” said Gallagher.
In the Ocotillo Wells case, cleanup has yet to begin of the gasoline that leached into private wells in the rural community about 75 miles northeast of San Diego. Discovered in 1986, the gasoline contamination put heavy concentrations of carcinogens into the water supply and prompted health officials to suggest that two families switch over to bottled water.
Traced to Mobil Station
In one of the private wells, tests showed that the concentration of benzene--a carcinogen and a component of gasoline--to be 180 parts per billion, far in excess of the 0.7 parts per billion permitted under state environmental standards.
The gasoline was traced to the nearby Burro Bend Mobil service station, on California 78, where two 1,000-gallon underground tanks failed tightness tests, said Gallagher. Although the source has been found and state water officials have ordered a cleanup, ridding the wells of gasoline will take some time, she said.
“It will be going on for a couple of years,” she said.
Santa Ysabel, 40 miles east of San Diego near Ramona, is on a state Superfund cleanup list because of the subterranean flow of fuel. Detected by residents as early as 1977, the underground plume of gasoline has contaminated wells used by a handful of homes and a private health clinic.
The source of the gasoline has been traced to the underground tanks at a local Chevron station, although other sources are possible, health officials say. There is a moratorium in the Santa Ysabel area on drilling new water wells.
The third and most recent threat to drinking water has been discovered in Borrego Springs at La Casa del Zoro resort, which is owned by the Copley Newspapers.
No Imminent Threat
Leaks from two 550-gallon underground tanks at the resort have put gasoline into the ground water, yielding concentrations of benzene in excess of the 0.7 parts per billion allowed by state standards. Two test wells drilled near the faulty tanks showed benzene at 14 and 3.9 parts per billion, according to a July report by an environmental consulting firm hired by Copley.
County health officials say they are worried the gasoline from the resort could find its way into nearby wells used by a local water agency, but they add that the threat is far from imminent. Calculations show that, at the rate it is leaching through the soil, the gasoline would take at least 11 years to reach the water supply.
Less worrisome are the 60 other leaks contaminating usable ground water. County officials say that since no one is tapping into those water supplies, and since the county has no immediate plans to use that water, there is no imminent danger to the public’s health.
While the threat of underground tanks on the environment is obvious, Gallagher said the leaks are also driving up the cost of development in San Diego.
Increasingly, developers are discovering leaking underground tanks on construction sites. Delays and cleanup costs can translate into an unpleasant surprise costing hundreds of thousands of dollars, she said.
If gasoline or other toxics have leaked from the tanks and heavily contaminated the soil, the developer may be forced to remove the dirt as a hazardous material and dump it at a landfill, at a cost of $300 a cubic yard, she said.
‘Real Expensive Real Quick’
“It can get real expensive real quick,” said Gallagher. “And it can get real confusing real quick. Sometimes you need a consultant, and sometimes a lawyer gets involved.”
Such has been the case for the Centre City Development Corp., the downtown redevelopment agency of the city of San Diego.
The redevelopment agency discovered a 470,000-gallon plume of gasoline lying under nearly 7 acres of prime downtown property.