Spill Cleanup Continues : Corrosion Caused Leak in Pipeline, Mobil Says
A rupture in a relatively new underground pipeline that leaked thousands of gallons of crude oil onto Encino streets and into the Los Angeles River was caused by exterior corrosion, Mobil Oil Co. reported Wednesday.
The oil leaked through a 4-inch rupture in a Mobil pipeline Saturday and seeped to the surface at Ventura Boulevard and Woodley Avenue in Encino. About 90,000 gallons of oil flowed along neighboring streets and about 8,000 gallons went down a storm drain into the river, according to Mobil.
Cleanup of the spill continued Wednesday in Encino and along the river as far as Long Beach. Meantime, engineers from Mobil and the state fire marshal’s office examined the 15-foot section of the pipe containing the rupture to determine how it happened.
“We have determined that the cause was isolated corrosion,” said Mobil spokesman James A. Carbonetti. “It was only in one part of the pipe.”
Carbonetti said the corrosion came from outside the pipe. “It is probably due to interference from other pipes in the ground,” he said.
Carbonetti explained that the 12-inch-wide pipeline is located directly on top of a 30-inch-wide water main. Next to those two pipes is a smaller pipe containing an electrical trunk line. He noted that the oil that is pumped through the Mobil pipe is hot and that the combination of heat, electrical current, ground moisture and the metal of the pipes may have caused electrolysis, which could have weakened the oil pipeline, leading to the rupture.
The pipeline safety engineer investigating the oil spill for the state fire marshal’s office could not be reached for comment on Mobil’s determination Wednesday.
Ken Miyoshi, assistant chief engineer of the Department of Water and Power, said most underground pipelines, including the city’s utilities, are equipped with protection systems that prevent electrolysis from occurring. Carbonetti said the Mobil line had such a system, called “cathodic protection,” but it was unclear why it did not prevent the rupture Saturday.
Replaced in ’76
The county Health Department hazardous materials unit has estimated 70,000 to 90,000 gallons of crude oil were spilled in the pipe break. Carbonetti said the break came in a section that had been replaced in 1976 during routine maintenance of the 180-mile pipeline that runs from Bakersfield to a Mobil refinery in Torrance.
“That’s a relatively new pipe,” Carbonetti said of the section that ruptured.
A rupture of the Mobil pipeline in Granada Hills in April, 1986, resulted in a spill of an estimated 29,000 gallons of crude oil and was also attributed to corrosion. A small leak in the pipeline July 22 in Valencia resulted in a 200- to 300-gallon oil spill that resulted in a brief evacuation of a shopping center, authorities said.
The Encino pipeline is back in operation, but Carbonetti said Mobil will conduct a pressure test on the line during the next two weeks to determine if there are other weak points or problems.
Robert Gorham, of the state fire marshal’s office, said the test consists of emptying the oil out of a section of the pipeline between two pumping stations and filling the line with water to a pressure 25% more than its maximum allowable pressure. He said the high-pressure test reveals small leaks or stress points.
The state requires all underground pipelines to undergo high-pressure testing every five years, but Mobil conducts the test on its line every two years, Gorham said. He said the test was conducted in 1986, and there were no problems detected in the section that ruptured Saturday.
Also on Wednesday, City Councilman Marvin Braude requested that the city’s Department of Transportation investigate the oil spill. Braude’s request was referred to the City Council’s Transportation and Traffic Committee for consideration. He also asked for recommendations on ways of avoiding future spills from the approximately 2,500 miles of underground pipelines in the Los Angeles area.
“People had thick, gooey oil running in their driveways,” Braude said, referring to Saturday’s spill. “The L.A. River filled with oil running all the way to Elysian Park. Even today they’re cleaning up in Elysian Park from a spill in Encino.”
Carbonetti said cleanup efforts, which have cost Mobil more than $1 million so far, were continuing on the river, where about half of the oil spill has been vacuumed off. The oil is being collected at eight points on the river by floating booms that cross it and dam the oil, which floats on the water’s surface.
Carbonetti said about 36 ducks and other waterfowl that got oil on their feathers after landing in the river have been caught and are being cared for and cleaned at a city animal shelter by a company hired by Mobil.
Authorities said as many as 200 birds may be affected by the oil spill. They said there is a 60% survival rate for birds that are captured and cleaned. Already some have died, Carbonetti noted.
“We’ve lost maybe half a dozen,” he said.