SAN BRUNO, Calif. — Federal investigators probing the cause of a gas pipeline explosion that killed eight people and destroyed 38 homes last September found a “litany of failures” at Pacific Gas & Electric Co., combined with weak government oversight and inadequate emergency response, led to the disaster.
The San Bruno pipeline explosion is “the story of flawed pipe, flawed inspection and flawed emergency response,” said Deborah A.P. Hersman, Chairwoman of the National Transportation Safety Board (NTSB), which led the investigation. “It was not a question of if the pipe would fail, but when,” she said.
Ms. Hersman said that federal and state regulators both placed a “blind trust” in the utility company and that the company, in turn, exploited that trust. This recipe for disaster allowed flawed pipe with poor pipeline welds to go unnoticed. Even then the disaster could have been averted had a competent emergency response plan been in place at Pacific Gas & Electric.
According to the NTSB, the problem started when an electrical glitch at a control center in Milpitas caused pipeline valves to open too far, allowing excessive amounts of gas into the subterranean pipelines. Poor seam welds gave way as pressure in the pipes continued to escalate, resulting in 47 million cubic feet of gas (enough to power 12,00o homes for a year) to erupt in a fireball.
After the explosion, it took Pacific Gas & Electric workers more than an hour and a half to shut off the gas flowing into the pipeline because, as the NTSB pointed out, the utility lacked both automatic and remotely controlled emergency shutoffs.
“This represents a failure of the entire system — a system of checks and balances that should have prevented this disaster,” said an NSTB board member Robert L. Sumwalt, adding that the seam welds may have been one technical cause of the explosion, but the disaster was really “an organizational accident.”
Photo: Flame roars from the San Bruno gas pipeline explosion in September 2010. Credit: Karl Mondon / Contra Costa Times