LOS ANGELES — In a scathing critique, federal investigators on Tuesday blamed a series of failures by Pacific Gas & Electric Co. as well as weak government oversight for causing a gas pipeline explosion last September that killed eight people and destroyed 38 homes in San Bruno, Calif.
The National Transportation Safety Board concluded that poor pipeline welds went undetected because of a lack of inspections by the utility and inadequate monitoring by state and federal regulators. The utility also lacked a workable emergency response that could have helped prevent the devastation, the board said.
"This represents a failure of the entire system — a system of checks and balances that should have prevented this disaster," said Robert Sumwalt, an NSTB board member.
Officials said the explosion was triggered by an electrical problem at a control center that caused the valves that regulate pipeline pressure to open, allowing more gas into the line. As the pressure built up, inadequate welds in a section of pipe ruptured, allowing 47 million cubic feet of gas to escape in a huge pillar of fire
The board said the substandard welds and other problems dated to the 1956 installation of the gas transmission line beneath San Bruno. It warned that there was no certainty that the problems don't exist elsewhere.
PG&E president Chris Johns said the company has spent the past year making fundamental changes to its operations and management that will "put the safety of the public, our customers and our employees first."
Information from the Associated Press was used in this report.