In one of the three ongoing post-San Bruno natural gas pipeline explosion regulatory cases, Pacific Gas and Electric Co. (PG&E) fired back at one of its strongest critics: the safety staff at the California Public Utilities Commission (CPUC).

Defending the utility's gas pipeline system, PG&E utility President Christopher Johns said the company is disputing many of the findings of the CPUC's Consumer Protection and Safety Division (CPSD), although that does not mean the company is disputing its liability for the ruptured pipe and explosion that killed eight people and destroyed part of a suburban residential neighborhood almost two years ago.

"It was our pipeline that ruptured and exploded because of a defective four-foot piece of pipe that should never have been put in service," PG&E's attorneys said in the opening of the company's 209-page response to the CPSD report on the September 2010 incident, which was filed with the CPUC Tuesday. Both confidential and public versions of the PG&E document were filed, the utility said in a cover letter to the filing.

While clearly stating that the defective piece of pipe should not have been in the ground and the utility has no records concerning the installation, manufacture and testing of the bad pipe segment, PG&E said it strongly disagrees with "many of the alleged deficiencies identified in the CPSD report," and assertions in submittals by intervenors.

One of PG&E's expert witnesses in the case, Robert Caligiuri, a pipe metallurgist, concluded that the pipe segment (No. 180 on Line 132) failed because of a missing interior longitudinal weld, a ductile tear likely caused by hydro testing at about 500 psig and fatigue cracking that grew from the tear.

"We acknowledge that our pipeline failure caused the tragedy, and our pledge is to continue to do the right thing in every way possible for the victims and the city of San Bruno," Johns said. "We have worked relentlessly to make improvements throughout our company and particularly in our gas operation, and we have made measurable progress and continue to every day."

With a series of witnesses from the utility's management, PG&E is attempting to prove that most of the alleged deficiencies cited by the CPSD in its report and in various intervenor testimony "are not, in fact, deficiencies," or are what the utility thinks are much less severe than alleged. "In either event [they] do not constitute violations of state or federal law," the PG&E filing said.

The case put on by the utility, its attorneys said in opening statements, also will concede that PG&E recognizes that parts of its gas system operations were not "as good as they could have been" prior to the explosion in San Bruno, and the utility has taken seriously "its obligation to fix shortcomings and ensure that safety is maintained as a top priority."

In essence, PG&E is contending that the CPUC safety staff have gone beyond the shortcomings that the utility has acknowledged and tried to "stack on top of this unknowing mistake a large number of alleged violations of what were then voluntary standards in 1956," when the portion of pipeline that failed was part of a relocation, or rerouting project. "But most of the standards CPSD references have nothing to do with the root cause of the pipe's failure."

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