The board unanimously agreed the accident was caused by what chairman Deborah Hersman called “a litany of failures’’ by PG&E, one of the nation’s largest gas companies, and weak oversight by regulators.
She called the explosion the most significant pipeline accident in the past decade, because of its destructiveness and the significant safety lapses it revealed.
The report said events that led up to the accident began more than 50 years ago with the installation of substandard pipe with inferior welds.
PG&E did not discover the problem because it failed to conduct proper pressure tests or visual inspections of the pipeline. Key records relating to the pipeline’s origin are missing. Other records incorrectly describe the section of pipe that ruptured as being seamless rather than welded, which led the gas company to set a maximum gas pressure limit for the line that was too high.
Destruction caused by the accident was worsened because of PG&E’s ineptness. Long after control room operators knew the cause of the fire was the rupture of a transmission line, they neglected to relay that information to 911 operators or to emergency responders, who thought they were dealing with a plane crash.
The fire burned at least an hour longer than it would have if PG&E had installed automatic or remote-controlled shut-offs.
As a result of the accident, the board has issued 39 safety recommendations to PG&E, gas pipeline operators, and federal and state regulators. But a safety advocate who has followed the case said it is not clear whether Congress and federal regulators will embrace the more significant recommendations.
For example, the safety board has recommended installing automatic shut-off valves on existing pipelines, but legislation under consideration in Congress addresses only new lines - a far less expensive proposition, said Carl Weimer, executive director of the Pipeline Safety Trust.
“Everyone knows that going back and putting in these valves or doing these pressure tests that should have been done 40 years ago is a costly thing,’’ he said. “It would cost hundreds of millions of dollars. I think Congress is hesitant to require regulations that would cost that much money without a clear sense of how many lives would be saved.’’
