MANHATTAN BEACH — Citing an "extraordinary level of public hazard," from underground hydrocarbon vapors, the Los Angeles County Department of Beaches and Harbors ordered temporary barricades, warning signs and patrols for the northern El Porto area along The Strand.
The measures were taken to keep onlookers away and warn of flammable conditions while Chevron USA Inc. officials began blacktopping an eight-foot-wide portion of The Strand from 45th Street to 42nd Street where the vapors had collected, a spokesman for the beach department said.
Larry Charness, chief of planning for the department, said the barricades, which block one lane of the bike path in that area, will remain until the blacktopping was completed, probably today.
However, he added, the activities were not expected to have much impact on weekend use of the bike path.
Manhattan Beach officials had asked Chevron on Wednesday to blacktop that portion of The Strand between the bike path and a parking lot after refinery representatives discovered hydrocarbon readings of 95,000 parts per million in the area last weekend. Gasoline-based hydrocarbons become explosive at 14,000 ppm.
While the origin of the gasoline-based vapors has not been definitively traced, the El Segundo refinery, located just north of the El Porto area, is believed to be the source.
"We view blacktopping the beach as an extraordinary measure," Charness said. "We wanted to prevent any digging or disturbance of sand levels in that location while the blacktopping was taking place.
"We understand that the levels found there are extraordinarily high, and our attorneys advised us that we had to block off the area as soon as we knew of the hazard, or face great liability."
Timing of Decision
Charness said the department made the decision to block off the area about 4 p.m. Wednesday, when lifeguards cleared the area of pedestrians and bicycle traffic while setting up the barricades.
Chevron officials learned of the high vapor levels while conducting tests to determine the extent of hydrocarbon vapor migration through the soil in the El Porto and El Segundo areas.
Extensive testing was begun last month when officials learned that a vapor plume of undetermined size was migrating through the El Segundo manufacturing district from a large pool of liquid hydrocarbons under the refinery, one of eight such pools on the Chevron site.
While only very low levels of the vapor were discovered in El Segundo, Chevron officials have discovered much higher levels along the El Porto section of The Strand in Manhattan Beach, including a maximum reading of 10,000 ppm in one house in that area.
Chevron officials say they will continue testing in the area and are meeting with state toxicology experts in Berkeley this weekend.