After the Northridge earthquake turned the soil under a King Harbor Marina parking lot to car-swallowing, goopy muck, some Redondo Beach residents gazed across Harbor Drive at the Southern California Edison electrical generating plant and wondered if a bigger earthquake might cause the plant to collapse--with catastrophic results for surrounding residents and businesses.
This week a delegation of Edison representatives appeared before the city Environmental and Public Utilities Commission to provide information on earthquake risk assessment at the generating plant. The Edison representatives’ conclusion:
Nothing to worry about.
“In a worst-case scenario . . . we believe any problems would be confined to the plant itself and not pose a danger to the community,” generating station manager Jerry Berquist told the commission.
A major concern centers on “liquefaction,” the phenomenon in which loose, wet soil can suddenly turn into a jelly-like substance when subjected to the violent shaking of an earthquake. In the Jan. 17 quake, Redondo Beach, although 28 miles from the epicenter, suffered at least $2.5 million in damage at King Harbor Marina when a parking lot built on a sandy spit collapsed, and about a dozen parked cars sank six feet into a mucky chasm. The collapse was attributed to liquefaction.
Dennis Ostrom, an Edison engineer and earthquake specialist, told the commission that while the plant rests atop soil that could be subject to liquefaction, it is supported by pilings driven 30 to 50 feet into the ground, below the potential liquefaction area. By contrast, the earthquake-damaged marina area was slabs of asphalt and concrete supported only by the underlying soil.
Ostrom said before the meeting that he was not aware of any liquefaction under the plant as a result of the Jan. 17 earthquake.
“Our plants have been exposed to earthquakes in the past,” Ostrom told the commission. “They’ve been exposed to liquefaction. So far there has been no consequence of liquefaction. . . . Certainly there has been no danger to people outside the facility.”
Ostrom added that generating plants “are known for being low-risk facilities.”
But not everyone was convinced.
Commissioner Tom O’Leary, who makes no secret of his opposition to having the power plant in Redondo Beach, earthquakes or no earthquakes, said the Edison representatives were basing their assurances on faulty assumptions.
“What has happened up to now has no bearing on what could happen in the future,” O’Leary said. “We have facing us the danger of stronger earthquakes.”
Although Edison representatives said the nearest known major fault line, the Newport-Inglewood Fault, lies about 2.5 miles away, O’Leary said the Northridge earthquake showed earthquakes can occur in areas where scientists never expected them.
O’Leary and other commission members wanted to know what would happen if a huge earthquake, say an 8.0, occurred near the plant. Would natural gas or electrical fires erupt? Underground ammonia tanks burst? Power lines collapse?
Liquefaction could occur under the plant with a nearby 7.5 quake, the Edison representatives said, and there could be fires and pipe ruptures. But again, Berquist insisted, any danger would be confined to the plant site.
“The Cal Ed guys’ presentation was incomplete and unconvincing,” O’Leary said after the meeting. “All they said was, ‘As far as we can tell, everything will be all right.’ ”
“A power plant is a very dangerous industrial application,” said Redondo Beach resident John Dancy, a retired aerospace engineer who attended the meeting. “You got the feeling (from the Edison presentation) that everything is flying on automatic pilot, that they just hope and pray nothing will happen.”
O’Leary said an informal group of citizens intends to analyze the Edison presentation and may have more questions.