A five-member review panel released an interim report to the California Public Utilities Commission (CPUC) Wednesday, indicating it will assess the effectiveness of Pacific Gas & Electric Co.'s (PG&E) and regulators' safety and risk management work in recent years leading up to the pipeline explosion in San Bruno, CA, last year.

The panel said in its five-page report that it is "reasonably optimistic" that it can complete its work by late May, according to Larry Vanderhoef, the investigative body's chairman and chancellor emeritus at the University of California Davis campus.

"We are mindful that the level of public interest and concern regarding the [Sept. 9] San Bruno incident and the safety of the PG&E natural gas transmission system remains high," Vanderhoef said. On Monday CPUC Executive Director Paul Clanon provided information from the combination utility on its location and maintenance of 10 major gas transmission pipelines in Northern California to state Assemblyman Jerry Hill, who represents the San Bruno area.

Within weeks of the blast, the CPUC named the independent investigative panel charged with looking at PG&E pipeline operations, but also those of other pipeline operators in the state and the oversight of the CPUC for those pipelines (see Daily GPI, Sept. 27, 2010). Other panel members besides Vanderhoef are Patrick Lavin, an executive council member for the International Brotherhood of Electrical Workers; Karl Pister, chair of the California Council on Science and Technology and a former chancellor and engineering professor in the University of California system; Paula Rosput Reynolds, CEO of PreferWest LLC and a former CEO of AGL Resources; and Jan Schori, an energy attorney and former CEO of the Sacramento Municipal Utility District.

While leaving the task of root cause analysis to the National Transportation Safety Board (NTSB), California's investigative panel is interested in the incident's "first cause," but only regarding what it reveals about the approaches to public safety and the quality of pipeline integrity management efforts by PG&E, other gas pipeline operators of intrastate lines, such as Sempra Energy's utilities and the CPUC itself.

"Our efforts are intended to examine both the scope and quality of the preventive efforts and the response capabilities of [PG&E]," the panel 's interim report said, adding that it also is looking at questions regarding "what is the role of the responsible regulators in the oversight of PG&E and its pipeline systems."

The panel report said it also now is scheduled to meet with Sempra to learn how it approaches "pipeline integrity management, risk management and regulatory oversight," although it added the caveat that it does not intend to expand the scope of its work beyond San Bruno and PG&E. To assist the investigation it has retained the Jacobs Consultancy, a unit of Pasadena, CA-based Jacobs Engineering Group Inc.; and global expert on vessels and pipeline integrity Robert Nickell.

Outside expertise on enterprise risk management and regulatory pipeline expertise are also being sought, the panel said.

PG&E's backbone transmission pipeline system has 20,000 segments, typically defined as lengths of pipe located between two valves that control flow and pressure. Segments range in size from four to 42 inches in diameter.

The pipelines typically operate at pressures between 100 and 1,040 psig (pounds per square inch gauge), the utility said. Federal limits for transmission pipelines such as the San Bruno pipeline that ruptured (Line 132) are set at 400 psi, and PG&E has used 375 psi as its operating limit. Since the San Bruno explosion, it has lowered pressures in San Bruno and other areas to 300 psi (see Daily GPI, Feb.4).

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