After the detection of gasoline vapors in a residential block in West Hollywood last week, the county Health Department has ordered an increase in vacuum pumping to stop a troublesome 4-month-old underground gasoline leak on Huntley Drive.
Santa Palm Car Wash, identified by the county as a major contributor to the leak, is conducting the pumping operation and plans to build a 130-foot-long, 10-foot-deep trench in the 800 block of Huntley to recover up to 3,000 gallons of gasoline lost from its underground tank.
Anastacio Medina, chief of the Health Department's hazardous-waste program, said that the department considered--but decided against--evacuating a small number of homes Friday after measuring the vapor levels in houses on three blocks of Huntley between Santa Monica Boulevard and Sherwood Avenue.
He said that the gasoline vapors measured much less than five parts of combustible vapors per million parts of the air, safely below the 30 parts per million considered to be a health hazard.
"Certainly," Medina said, "the level of vapors is an inconvenience and some of the residents are angry about the time it is taking to solve the problem. There is, however, no health hazard. . . . We are counseling residents to be patient. We are making progress on the problem."
Hank Yacoub, supervising engineer for the area for the California Regional Water Quality Control Board, said his agency is directing the recovery operation, with the assistance of various county and state departments.
The problem was discovered in March when residents complained about gasoline vapors in their homes. About 20 residences along Huntley were evacuated briefly until it was determined that there was no health hazard.
Yacoub said that investigators concluded that vapors from gasoline, apparently leaking from underground tanks in the immediate area, were infiltrating the homes through an old sewer system in an area with an unusually high water level.
Backed Into Homes
"Because of the downward slope of the area," Yacoub said, "the water level is about six feet below the surface. The gasoline collected on top of the water and infiltrated the sewer system and the vapors backed into the homes."
Yacoub said that the water level in the area apparently rose above the sewer line in the mid-1970s, when the City of Beverly Hills stopped pumping water from several wells for use in the city's water supply.
He said that a new sewer system was installed above the water level. Two wells and a vacuum pumping system were installed on a vacant lot just north of the Southern California Rapid Transit District maintenance yard in the 8000 block of Santa Monica Boulevard to recover the underground gasoline.
Twelve business operations with underground gasoline tanks were identified as possible sources of the leaks. Most of them are gasoline stations, but they also include the RTD maintenance yard, a Sheriff's Department station and a county fire station.
Yacoub said that some leakage was found at the RTD facility and a large leak was reported by the car wash. Investigation of the other sites is continuing.
"The attorney for the car wash has conceded that his client is responsible for part, but not all, of the leakage problems in the area," Yacoub said.
The vapor problem seemed to be under control until last week when high levels of gasoline were detected in recovery wells, Yacoub said.
He said that work on the recovery trench may start next week.
"The trench should aid us in clearing up the problem," he said. "We have already recovered 500 gallons of the leaked gasoline. We are aiming to recover as much as 1,000 gallons more, although we do not know how much of the gasoline has passed through the entire sewer system."
The government agencies hoped to clear up the problem "in a matter of months," Yacoub said, but he said that similar leaks in other areas have persisted for years.
He said that although investigators have confined their efforts to cleaning up the specific area, in the future they will investigate nearby areas to determine whether there are similar underground gasoline leaks.
"The basic problem is old single-wall underground storage tanks," he said. "Eventually, they have to be replaced with double-wall tanks with a leak detection system. At least one oil company has started doing exactly that."
Yacoub said the costs of the cleanup will be covered from, among other sources, a $25,000 grant from the state Cleanup and Abatement Fund, $150,000 for the new county sewer and about $70,000 from the car wash.