The California Public Utilities Commission (CPUC) Thursday ordered Pacific Gas and Electric Co. to lower by 20% the maximum operating pressures in parts of its transmission system throughout its territory as the investigation of the fatal San Bruno pipeline blast continues.

The CPUC has picked up on part of the National Transportation Safety Board (NTSB) interim report released last Tuesday (see Daily GPI, Dec. 15) that referenced results of the tests of the Sept. 9 ruptured pipeline sections showing "longitudinal seams that were fusion-welded from both inside and outside the pipe, or just the outside of the pipe."

For pipelines with these characteristics, CPUC Executive Director Paul Clanon, in a letter sent Thursday, directed the San Francisco-based combination utility to: drop the pressure to 20% below each pipe's maximum allowed levels; assess those pipeline's integrity with one of four tests; and obtain CPUC authorization to repressure those lines. Since the San Bruno tragedy, the pressure in the three transmission pipelines operating in the areas have been kept 20% below their allowable levels.

PG&E officials told news media that two transmission pipelines in the East San Francisco Bay Area could be impacted -- one from Oakland to Fremont and the other between Fremont and Milpitas. The officials said steps were being taken to reduce pressures, but when and how inspections would be carried out was not immediately clear.

In the wake of the latest NTSB preliminary progress report, which said a root cause for the pipeline failure is still a long way from being determined, news media in the San Francisco area have reported a nearly two-year-old CPUC safety staff report that was critical of PG&E's safety maintenance programs on parts of its distribution system.

PG&E has responded that it is working closely with the CPUC to make sure everything is being done to keep the utility pipeline systems operating at maximum safety. "The bottom line is that any time we find something that could potentially pose a safety issue, we work to fix it immediately, and we don't wait for orders from the regulators to do that," the utility said.

Nationally, the Interstate Natural Gas Association of America (INGAA) responded to the latest NTSB report, commending the federal investigatory agency for its "methodical approach." INGAA said that at the same time the industry and federal, state and local officials cannot stand by idly, emphasizing the industry has to continue to address the issue of third-party damage to pipelines, which it called "the leading cause of fatalities and injuries associated with pipeline accidents."

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