The Pacific Gas and Electric Co. (PG&E) San Bruno pipeline rupture last year was caused by none of the usual suspects when it comes to high-pressure natural gas transmission pipeline failures, the National Transportation Safety Board (NTSB) made clear in its final report adopted by the five-member panel in Washington, DC, Tuesday (see Daily GPI, Aug. 31).

The rupture, explosion and ensuring fire that killed eight people and devastated a residential neighborhood about 10 miles south of San Francisco was not caused by corrosion or damage from a third-party contractor — the two most common causes. And in the earthquake-prone California suburban Bay Area region, ground movement played no part either, NTSB investigators told the five board members.

“Multiple, recurring deficiencies over many years indicate a systemic problem at PG&E,” NTSB Chairperson Deborah Hersman said.

In listing more than four dozen findings and recommendations in the year-long investigation, an NTSB investigator told Hersman and her colleagues that “seismic activity was not a factor, nor was corrosion, direct third-party damage, or drug use at the [PG&E] Milpitas [pipeline control] terminal.” Allegations and suspicions had surrounded 2008 city sewer installation work near the site of the San Bruno pipe blast, but that was thoroughly studied and rejected, according to the NTSB report.

Instead, the federal report concluded:

“…the rupture of Line 132 was caused by a fracture that originated in the partially welded longitudinal seam of one of six short pipe sections, which are known in the industry as ‘pups.’ The fabrication of five of the pups in 1956 would not have met generally accepted industry quality control and welding standards then in effect, indicating that those standards were either overlooked or ignored.

“The weld defect in the failed pup would have been visible when it was installed. [Separately,] an investigation also determined that a sewer line installation in 2008 near the rupture did not damage the defective pipe.”

The ongoing historic description tied to the cause of the Sept. 9, 2010 tragedy becomes bleaker for the operating utility, PG&E, because at every turn evidence or lack of sufficient record keeping point to the utility’s “organizational failure” over decades, according to the NTSB report.

Aside from a pipeline integrity maintenance program creating a tragedy that NTSB concluded was preventable, the federal investigator found PG&E’s response to the emergency also woefully inadequate. While praising local first responders from the San Bruno police and fire department for being on the scene within minutes of the rupture, NTSB said the utility took 95 minutes to stop the gas flow.

“PG&E lacks a detailed and comprehensive procedure for responding to large-scale emergencies such as a transmission pipeline break,” the NTSB report said.

Instead of ensuring safety in the pipeline system, PG&E’s pipeline integrity management program was “deficient and ineffective,” according to NTSB, because of at least five factors:

Most damning of all, and Hersman repeated it several times during nearly six-hour NTSB board meeting, PG&E failed to learn from two earlier NTSB-investigated pipeline incidents — the 1981 San Francisco rupture and the recent 2008 distribution pipeline break in the Sacramento suburb of Rancho Cordova.

“Several deficiencies revealed by the NTSB investigation [of Rancho Cordova] — such as PG&E’s poor quality control during the pipe installation and inadequate emergency response — were factors in the 2008 explosion. The 2008 accident involved the inappropriate installation of a pipe that was not intended for operational use and did not meet applicable pipe specifications. PG&E’s response to that event was inadequate.”

In addition, in the San Bruno report NTSB concludes also that the California Public Utilities Commission failed in its role as the state pipeline safety regulatory by not detecting PG&E’s pipeline integrity management inadequacy. Similarly, the federal report said the federal Pipeline and Hazardous Materials Safety Administration pipeline integrity program protocols need to be improved.

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