In September, 1982, a damaged storage tank at Mobil Oil Co.'s Anaheim distribution terminal leaked more than 37,000 gallons of gasoline into the soil below and ultimately into the city's drinking water supply.
Today, a city well remains closed, three others are being monitored closely and Mobil Oil is processing an estimated 500,000 gallons of water daily to remove pollutants.
Water quality officials say most of an estimated 175,000 gallons lost in 44 underground leaks--ranging from gasoline to jet fuel to industrial solvents and acids--has seeped into the ground water table.
But Mobil's Atwood terminal leak is considered the most serious because it is the only case of toxic materials known to have entered drinking water supplies.
Known cases probably represent just "the tip of the iceberg" of soil and ground water contamination, said James Anderson, executive director of the state Santa Ana Regional Water Quality Control Board.
As more than 94,000 companies and individuals in California with underground storage tanks, sumps or ponds work to comply with a new state law requiring inspection and monitoring that takes effect July 1, Anderson predicted that many more problems will come to light as tank leaks are discovered.
"In the state of Maine, the (U.S.) Environmental Protection Agency did a study and found 11 million gallons of gasoline were lost in one year," Anderson said Friday. "If that is the case in Maine, I think the state of California is going to find it has a significant problem.
"In Orange County, we've been fairly lucky, but that's all I'd call it."
"All of them (leaks) are a potential threat, whether they are big leaks or small ones," said Nereus Richardson, senior engineer for the Orange County Water District, which manages the ground water supply for 1.7 million county residents. "We are concerned about all of them."
In most cases, investigators say, the pollution has come from gasoline tanks at local service stations. When tanks are underground, small leaks go undetected until they become large leaks or are discovered to be a problem elsewhere.
Leak at Car Wash
Unleaded gasoline spotted floating on the San Diego Creek on Oct. 3, 1981, was traced to an undetected leak of 41,000 gallons from gas pumps at the Woodbridge Car Wash in Irvine.
In Orange County alone, more than 172,000 gallons of gasoline have been reported lost to tank leakage, according to an April report to the tri-county water quality board. Even that figure is unreliable because no estimates were given for more than half the 34 gasoline tank leaks being investigated in the county. State authorities say there are more than 5,200 underground storage containers in the county.
Ten more Orange County facilities have been investigated by various agencies for tank leaks of acids, industrial solvents, diesel and jet fuel. Of those, only a Tustin steel-casing firm estimated the amount lost--3,000 gallons of organic paint solvents from an underground tank in November, 1983.
In many cases, massive and costly recovery efforts have been undertaken--some voluntarily, some at the insistence of regulatory authorities, officials said.
Jet Fuel Seepage in Tustin
In others, state Fish and Game inspectors, water specialists from the Orange County Environmental Management Agency and investigators from the regional board have had to battle to get even minimal cleanup under way.
Authorities said Friday that efforts to get 100,000 square feet of soil saturated with jet fuel cleaned up at the Tustin Marine Corps helicopter base have been an uphill battle since Feb. 3, 1983, when a county water specialist discovered the pollutant leaking into the adjacent Peters Canyon channel.
"The problem is that military bases are not under the regulation of the EPA or civilian authorities because they are defense facilities," said Bob Collacott, a county environmental specialist.
The source was two pits about 100 feet northwest of the channel that were used to hold jet fuel that was set afire for training purposes on the bases. Over the years, untold thousands of gallons were flushed into the channel that feeds into San Diego Creek and ultimately to the Upper Newport Bay, a state preserve for numerous wildlife species, water quality officials said.
Once alerted, base officials ceased the practice and sought advice from the U.S. Geological Survey on the extent of pollution and necessary cleanup measures. In October, 1983, the I T Corp., based in Irvine, was hired to excavate to a depth of 10 feet, according to county EMA file records on the case.
Filled Pit With Sand
At that level, the soil was still saturated with jet fuel. But base officials, after spending about $250,000 on investigations and excavation, ordered the pit filled up with sand "despite our strenuous objections," Collacott said.
"It's my understanding that they had funds to remove 10 feet of soil, and when they ran out of money, they decided to backfill those pits with sand," he said.