San Bruno blast: PG&E repair job turned frantic
Friday, April 15, 2011
(04-14) 18:53 PDT MILPITAS -- The events leading up to last year's deadly natural-gas explosion in San Bruno may have been set in motion when a repair crew "jostled" an electrical wire at Pacific Gas and Electric Co.'s Milpitas terminal, causing a power breakdown and a pressure surge on the utility's Peninsula pipelines, crew members told federal and state investigators.
Four members of the crew - a private contractor, two PG&E technicians and a gas apprentice - working at the normally unmanned outpost the day of the disaster provided a detailed account of a seemingly routine repair job that suddenly turned frantic.
The National Transportation Safety Board, which is investigating the cause of the Sept. 9 explosion that killed eight people and destroyed 38 homes, released transcripts Thursday of interviews with the workers that were conducted one week after the blast.
The men were replacing a power supply that had failed six months earlier at the Milpitas terminal, a major intersection for the Bay Area's gas transmission system, when something went wrong, said John Groppetti, a contract technician working with PG&E. The trouble started at about 4:20 p.m., less than two hours before the San Bruno explosion.
An ominous 'beep'
Sorting through a tangled, makeshift backup system that had been put in place after the earlier power-supply failure, Groppetti recalled spotting an apparently unused circuit breaker. He turned it off, as he had other breakers that day.
When this breaker was shut off, however, there was a "beep" - "a warning, an alarm," said Peter Beck, a PG&E crew leader.
"We had triggered something that was unexpected," Beck told investigators.
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