WASHINGTON ? A federal safety panel blamed a series of missteps by one of the nation's largest gas companies for the largest pipeline accident in a decade, a suburban San Francisco explosion that killed eight people and incinerated a neighborhood. The panel also warned there was no certainty that the problems that led to last year's accident don't exist elsewhere.
The National Transportation Safety Board wrapped up its yearlong investigation of the Sept. 9, 2010, accident in San Bruno, Calif., voting 5-0 that actions by Pacific Gas & Electric were the probable causes of the explosion. Lax regulations at the state and federal level also contributed to the accident.
"The aging pipelines, our oldest pipelines really are without a safety net," NTSB chairman Deborah Hersman said.
The board voted that substandard welds and other problems dating to the 1956 installation of a Pacific Gas & Electric Co. gas transmission line beneath San Bruno were the direct cause of the accident. The board also said the company's inadequate inspection program for pipelines, which allowed the bad welds and other weaknesses to go undetected, helped cause the accident.
Among the problems with government oversight was a lack of federal or state requirements for testing for older pipelines to detect defections, the board said.
The California Public Utilities Commission also failed to detect widespread internal problems with PG&E's safety regime, including a lack of automatic gas shut-off valves and shortcomings in the company's emergency response plan that contributed to the protracted duration of the accident, the board said.
"It was not a question of `if this pipeline would burst,'" Hersman said. "It was a question of `when.'"
The board also made a series of safety recommendations to regulators and the gas industry before adjourning. The board has made nearly 40 safety recommendations as a result of the accident over the last year.
The board concluded the accident wasn't the result of a simple mechanical failure, but was an "organizational accident."
Among PG&E's problems were a failure to learn from past accidents, the loss of key personnel after the company's 2001 bankruptcy, poor internal communications and bad morale among company employees, board members said.
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."
"We fully embrace the recommendations of the NTSB and will incorporate them into our plans," Johns said in a statement.
He also said the company's board was "deeply sorry that our pipeline was the cause" of the accident.
"We know that nothing we can say nor any action we can take will ever make up for the losses experienced by the victims of the accident and the San Bruno community," he said.
Hersman said existing rules that allow operators to make determinations and decisions about pipeline safety are "a slippery slope" that leave regulators little recourse when something goes wrong.
About half the gas transmission lines ? roughly 150,000 miles ? were built prior to 1970 and so are exempt from many federal safety requirements, NTSB officials said
"What we've seen in PG&E is hopefully the worst-case scenario," Hersman said.
The board was especially critical of PG&E's failure to provide investigators with critical records related to the source and installation of the section of the transmission line that ruptured.
Company records that were provided were also inaccurate on key points. They indicated the pipe that ran through San Bruno was seamless. But a laboratory examination later showed that the pipe was constructed with seam-welds that failed during the accident.
Also, company records showed the pipeline was of a uniform thickness in the San Bruno area. It was later found to be variable.
Such information is considered crucial to determining how much internal pressure a pipeline can be operated under, investigators said.
PG&E had set a maximum allowable pressure on the line of 400 pounds per square inch. It failed after reaching 396 pounds-per-square-inch in the hour before the explosion.
"The NTSB has been frustrated throughout the duration of this investigation by the inadequacy of PG&E's record-keeping," Hersman told reporters.
Investigators also faulted the company for understating threats to the pipeline from corrosion or manufacturing defects. The threat assessment was based on internal records that the NTSB said overstated the danger from ground movement or third-party damage caused by excavating near a pipeline.
PG&E said earlier this year that it could not find key safety records for 8 percent of its lines running through populated areas. That was after the company used documents showing historical pressure levels for many of its older pipelines, rather than pressure tests or engineering work. The utility could not turn up pressure tests for 69 percent of the transmission lines laid before 1961, including for some sections of the line that blew up in San Bruno.
Investigators identified a substandard seam weld that went only halfway through the pipe wall at the rupture point. The 30-inch circumference pipe had other substandard welds as well. Evidence indicates the pipe was composed of several short welded pieces that didn't meet any known specifications, investigators said.
PG&E has said it didn't know of the welds because its records incorrectly listed the pipe as seamless. The utility also has been unable to produce other key records regarding the pipeline.
The explosion sent a giant plume of fire into the air that continued to burn for 95 minutes before PG&E employees were able to shut off the flow of gas. In addition to the eight deaths, dozens of people were injured and 55 homes destroyed or damaged.
The pipeline lacked automatic or remotely controlled shut-off valves. If valves on the line had closed immediately after the initial explosion, the gas-fed fire probably would have gone out in under 10 minutes, according to safety experts.
Last week, federal regulators proposed forcing utilities to step up testing of older transmission lines and install more automatic shut-off valves.
San Bruno mayor Jim Ruane said Tuesday he would join with lawmakers to push measures pending before Congress to replace aging pipe, require emergency shut-off valves and bolster inspections for the nation's underground pipeline system.
"They say out of sight out of mind. It's not out of sight anymore and we're going to keep it that way," Ruane said. "They heard loud and clear today that something has to be done."
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Brown reported from Billings, Mont.
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Online:
National Transportation Safety Board: http://www.ntsb.gov
NTSB chairman's briefing on San Bruno hearing http://www.youtube.com/ntsbgov
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Follow Joan Lowy on Twitter: http://twitter.com/(hash)!/AP_Joan_Lowy
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