MANHATTAN BEACH — The discovery of extremely high levels of potentially explosive hydrocarbon vapors has led city officials to ask that Chevron USA Inc. temporarily pave over a swath of beach six to eight feet wide and about 200 feet long in the El Porto section of The Strand. The paving could begin as early as Friday.
Readings taken over the weekend showed the gasoline-type vapors peaking as high as 95,000 parts per million four feet below the surface, according to Assistant Fire Chief Keith Hackamack. Gasoline-based hydrocarbons become explosive at 14,000 ppm.
Although there is no conclusive evidence yet, the vapors are believed to be emanating from the Chevron refinery just north of the El Porto section of Manhattan Beach.
Surprised at Readings
Chevron spokesman Jim Edmisson said company officials were surprised at the readings, which were taken by company-hired independent consultants, but he added that above-ground levels are still in the normal range.
"We really don't understand what's going on with this stuff," he said. "But we believe it (the vapors) has been here for some time and that it's centering around an abandoned sewer line that runs along that strip of The Strand."
Readings were found in that sewer line peaking at around 5,000 ppm, he said. Normal readings for sewer lines generally fall in the 200-300 ppm range.
Edmisson said that while the sewer levels are still below the explosive range, the soil levels are "well into" it. For that reason, he said, Chevron has agreed to pave over a strip of beach from 45th Street to about 42nd Street "as quickly as possible."
Chevron and city officials met Wednesday to discuss the findings and to work out details for paving part of the county-owned beach. Edmisson said that despite numerous state, county and local permits that must be obtained, the potential hazard posed by the vapors may lead the various agencies to grant emergency permits so that paving could begin Friday. The paved area would stretch east between the bicycle path and a beach parking lot on 45th Street.
Hackamack said that while the discovery concerns him, "I really don't believe this poses a hazard because it's so deep into the ground. But obviously, we don't want anyone poking holes in that area." Hackamack was quick to add that the paving is "a temporary thing" and would be removed as soon as the soil in that area has been cleansed. However, he conceded, that could be months away.
The discovery is just the latest in a string of incidents that have plagued Chevron since El Segundo city officials found a liquid hydrocarbon pool three to four city blocks wide seeping off the refinery into the city's manufacturing district last April. Last month, a vapor plume of undetermined size was found to be moving through the soil in that area. In recent weeks Chevron officials discovered high levels of the vapors along The Strand in the El Porto area as well.
This weekend was the first time that instruments registering higher than 10,000 ppm were used. Previously, Chevron officials had found readings that high in several shallow survey holes along The Strand and in at least one house near 41st Street.
Edmisson said that as a result of the higher readings, Chevron is also asking that it be allowed to drill an observation well that will bore to the water table, to determine whether ground water in the area contains hydrocarbons. Most ground-water pools along the coast, however, have long been contaminated by seawater intrusion, and are not used for drinking water. Edmisson said Chevron is mostly looking to obtain liquid samples of hydrocarbons, which can be analyzed in much greater detail than vapor samples.
Edmisson said Chevron representatives will meet with state health officials at the state's toxicology center in Berkeley this weekend to determine the health hazard posed by the vapors.
Meanwhile, the Regional Water Quality Control Board will hold a public hearing Monday on its plan to order all 15 of the refineries in Southern California--nine of which are in the South Bay/Harbor area--to begin extensive testing on and possibly off their sites for ground-water and soil pollution from hydrocarbons or other hazardous materials. The hearing will begin at 10 a.m. at 107 S. Broadway, Room 1138, Los Angeles.
According to Senior Water Resource Control Engineer Ray Delacourt, at least five refineries are known to be investigating groundwater problems at their facilities. Those are Chevron in El Segundo; Golden West Refinery Co. in Santa Fe Springs, and Atlantic Richfield Co., Shell Oil Co., and Texaco Inc., all in Wilmington.
The plan, which the board will vote on at the Monday meeting, came about as a result of the recent incidents at Chevron.