A statewide survey of Pacific Gas & Electric’s pipeline system has discovered 21 additional gas leaks than previously found, including three in South San Francisco.
The results of the inspection were released Tuesday, along with an update on PG&E’s search for documents that prove its pipeline system is safe.
PG&E had been ordered by state regulators to survey its entire pipeline system after a transmission pipeline it owned in San Bruno exploded Sept. 9 and killed eight people.
In October, PG&E released the results of the first half of the inspections, revealing that 38 leaks had been found on the thousands of miles of pipelines they had surveyed. Of those, four had been discovered on the large, high-pressure transmission lines like the one that ruptured in San Bruno.
Since then, the company found 21 more leaks – eight of which were on transmission lines. Of those, three were found “in close proximity to Line 109 in South San Francisco,” according to the report PG&E provided to the California Public Utilities Commission on Tuesday.
The leaks were repaired by tightening the cap on a pipe fitting, applying grease to a valve, and tightening the plug on another valve.
In order to find the leaks, PG&E flew small planes over all of its thousands of miles of transmission and distribution feeder mains, using methane detection technology. In some cases, they had workers actually walk the lines with methane detectors.
In addition to the accelerated leak survey, PG&E provided the Public Utilities Commission with an update on a separate mandate.
Federal inspectors have discovered the paperwork surrounding the pipeline in San Bruno had been inaccurate and incomplete, flaws that lead PG&E to operate the pipeline at much higher pressures than was safe. After these flaws were revealed, the federal government encouraged the CPUC and other regulators across the nation to insist utility companies better document the state of their underground natural gas infrastructure.
Earlier this month, the CPUC did just that, mandating that PG&E and other utilities pore through documents about their pipelines to identify other areas were records might be shoddy. Though the results of that search are not required until next month, CPUC required an update on the process by Tuesday. PG&E’s update stated they had identified 1.25 million documents about their pipelines and were scanning and indexing them on the order of tens of thousands of documents a day.