While a California congresswoman from the San Bruno, CA, area was proposing legislation addressing safety and transparency for natural gas transmission pipelines, U.S. senators representing the state last Tuesday speculated that the natural gas pipeline explosion last month would have been far less of a disaster if the Pacific Gas and Electric (PG&E) line had automatic shutoff valves.

Meanwhile, in California the scenarios and suspicion grew in terms of whether the pipeline failure was due to internal or external causes and whether PG&E’s ongoing safety, operations and maintenance programs were thorough enough. In short, the conjecture has continued on both coasts.

On Friday the San Jose Mercury-News reported that academic experts suggested that a failed weld may have been the main cause for the 30-inch diameter steel pipeline’s failure. The newspaper further quoted local government officials as complaining that PG&E was holding back information it had promised on the network of four high-pressure transmission pipelines that run through the peninsula region between San Jose and San Francisco.

In response, a PG&E spokesperson said the utility met last month with San Jose officials in what he called a “productive meeting,” and the utility plans to meet with them again this week (Oct. 4-8). “We plan to continue meeting with every local government that wants information on our pipelines and their safety procedures,” he said, noting that the utility is not refusing to provide any data, including the location of valves on the pipelines.

Experts from nearby Stanford University were asked by the Mercury-News to examine photographs of the pipeline segments that are being analyzed by the National Transportation Safety Board (NTSB). The experts concluded that the failure may have started along a weld. Separately, the newspaper reported Friday that San Jose Mayor Chuck Reed said he was not satisfied with PG&E after the utility allegedly refused to give local fire officials the locations of the shutoff valves on the transmission pipelines running through the area.

The PG&E spokesperson told NGI the utility could not comment on the possible causes of the explosion because of the NTSB investigation.

In Washington, DC, speculation centered on the shutoff capability on the pipeline segment that failed. If there had been automatic or remotely controlled valves to shut off the gas flowing through the pipeline in San Bruno, “we wouldn’t be here,” said Sen. Barbara Boxer (D-CA) at a Senate Commerce subcommittee hearing on pipeline safety.

On Sept. 9 the inferno burned for one hour and 29 minutes before gas to the 30-inch diameter pipeline could be turned off at two different locations, Sen. Dianne Feinstein (D-CA) told the subcommittee (see NGI, Sept. 13). To turn off the two valves — one located a mile away from the explosion and the other 1.5 miles away — she said a worker had to drive through rush hour traffic, use a key to get into the area where one valve was and attach a handle to the valve to crank it.

As a result, it took more than five hours to turn off all the distribution lines to the homes that were on fire, Feinstein said.

“There’s no question that turning them off sooner would have resulted in less damage,” said Christopher A. Hart, NTSB vice chairman. The target date for completion of the agency’s final report on the accident is 12 months.

Paul Clanon, executive director of the California Public Utilities Commission (CPUC), said the CPUC’s focus was on automatic shutoff valves, and it hoped to be “ahead of the curve” with the rest of the country on this.

Also contributing to the disaster was the age of the pipeline (more than 60 years) and the fact that it ran through a residential neighborhood, which did not exist when the pipeline was first built. The PG&E pipeline was also operating at more than 300 psi, Feinstein said.

Feinstein, who toured the damage area following the explosion, said it “resembled a war zone…it was like a bomb had struck.” The explosion killed eight people, injured 52 people and destroyed 37 homes, according to subcommittee Chairman Frank Lautenberg (D-NJ).

“We recognize that the accident has shaken customers’ confidence in the safety and integrity of our system, both in the areas surrounding San Bruno and across PG&E’s service areas. We take these concerns very seriously and have taken steps to help restore that confidence,” said PG&E President Christopher Johns.

“First we reinspected the three major pipelines that serve the San Francisco Peninsula. We also reduced the operating pressure of the transmission lines serving the area by 20%,” and “we are conducting aerial inspections of our entire natural gas system.” Moreover, “we have begun the ground leak survey of the entire gas transmission system beginning with the high-consequence areas,” he said.

Public speculation has shifted to looking inside the pipe for the possibility of corrosion-causing microbes that can go undetected within older gas pipelines. In addition, news reports of PG&E’s leak history caused the utility to issue a statement defending the thoroughness of its transmission pipeline maintenance and safety checks.

“On ‘high-consequence area’ pipelines [in populated and environmentally sensitive sectors] we report everything — from a pinhole[-sized] leak to a third-party dig into the pipeline,” a PG&E spokesperson said. “We continue to work with the [federal] PHMSA [Pipeline and Hazardous Materials Safety Administration] to determine how our self-imposed strict reporting can be improved.”

The San Francisco-based combination utility was responding to a report in the Sept. 27 Los Angeles Times that cited PG&E for having the highest rate of leaks reported to PHMSA per 1,000 miles of pipelines in high-consequence areas during 2004 through 2009 (6.16 leaks average each year and 38 in total), compared to Sempra Energy’s Southern California Gas Co. (SoCalGas), which averaged 2.22 leaks and 22 in total during the same period.

For the period, the numbers published showed data for Florida Gas Transmission Co., Energy Transfer Co., Williams Gas Pipeline (Transcontinental Gas Pipe Line), Texas Eastern (Spectra Energy Corp.) and Natural Gas Pipeline Co. of America (Kinder Morgan), which collectively only reported seven leaks over the same period. PG&E and SoCalGas were shown to have 2,341 miles of transmission pipelines in high-consequence areas; each of the other pipeline operators listed has smaller amounts of pipe in these similar areas individually, but collectively they have more than 3,000 miles of pipeline in such areas.

PG&E said the Times report looked at “less than one-third” of the pipeline miles traversing the sensitive areas, and to be more accurate it should compare leak records from all of the pipelines in such areas, the utility spokesperson said.

Regarding the corrosion speculation that surfaced last Friday, PG&E spokespeople verified the possibility that could be a cause but would not speak to the segment of pipe that failed in San Bruno.

According to the San Francisco Chronicle, PG&E more than a year ago had told state regulators about its concern regarding internal corrosion developing in its 46-mile transmission pipeline between Milpitas, CA and San Francisco, which included the segment in San Bruno that failed on Line 132. However, the combination utility would not confirm that for NGI.

A major interstate natural gas transmission pipeline that failed 10 years ago in New Mexico was more than 50 years old and the same 30-inch-diameter size when it ruptured, killing 12 people. Subsequently MIC was identified as a possible cause. The microbes lay dormant and cannot be easily detected externally until the small bacteria begin eating away the metal.

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