PG&E Memo Says Valves That Could Automatically Shut Off Gas In Emergencies Were of "Little" Value
WASHINGTON (AP) -- Officials for a California gas company involved in a deadly pipeline accident last September acknowledged Tuesday that four years before the accident they rejected installing valves that could have automatically shut off or remotely controlled the flow of gas.
Pacific Gas and Electric Company employees were questioned at a National Transportation Safety Board hearing about a company 2006 memo that said installing the valves would have "little or no effect on increasing human safety or protecting properties."
Gas engineer Chih-hung Lee, author of the memo, said he considered only industry studies, not government studies, in reaching his conclusions. Industry studies, he said, found that most of the damage in gas pipeline accidents occurs in the first 30 seconds after the accident.
However, when the pipeline ruptured on Sept. 9 underneath a suburban San Francisco subdivision, gas continued to feed a pillar of fire for an hour and a half before workers could manually shut off the flow. Eight people were killed, many more injured and dozens of homes destroyed.
Investigators pointed to a 1999 Department of Transportation study that warned that there is a significant safety risk as long as gas was being supplied to the rupture site and operators lacked the ability to quickly close manual valves.
"Any fire would have greater intensity and would have greater potential for damaging surrounding infrastructure if it is constantly replenished with gas," the government study said. "The degree of disruption in heavily populated and commercial areas would be in direct proportion to the duration of the fire."
Coroner's reports indicate at least five of the people killed in San Bruno were trying to flee when they died.
PG&E officials acknowledged that after the memo they made no effort to further explore the valves. They said that since the accident, the company has begun a pilot project to install a dozen of the valves this year and study their effectiveness.
The safety board has been recommending the devices to industry and regulators for decades for gas distribution lines, which are larger than the transmission line that ruptured in San Bruno.
About 12 minutes after the San Bruno explosion, PG&E's dispatch center sent an off-duty employee to investigate the reported explosion, but he wasn't qualified to operate the manual valves needed to shut off gas feeding a huge fire that consumed homes, the safety board's lead pipeline investigator, Ravi Chhatre, said.
It took 30 minutes after the rupture for the company to dispatch a crew capable of isolating the pipeline and 90 minutes before all gas was stopped, he said.
(Copyright 2011 by The Associated Press. All Rights Reserved.)
