The gas transmission lines and associated cross-ties, which primarily serve San Francisco and San Mateo counties, had their operating pressure reduced by 20 percent in the days after Sept. 9, 2010, when PG&E's Line 132 exploded in a residential neighborhood in San Bruno, killing eight people and destroying 38 homes.
The resulting investigation revealed that the utility had incomplete records regarding testing of some of its critical transmission lines in densely populated areas.
California Public Utilities Commission executive director Paul Clanon ordered the decrease in operating pressure until PG&E could perform pressure tests and safety inspections on all of its Peninsula pipelines, or produce accurate records that tests had already been carried out.
Since that time, PG&E has performed hydrostatic pressure tests on all lines and segments in highly populated areas for which prior pressure test results were not available, according to the CPUC.
In its ruling announced today, the CPUC said that PG&E had adequately followed the agency's recommended safety testing criteria and cleared the utility to restore normal operating pressure on three of its pipelines.
"In coming to today's decision, we are satisfied that PG&E has demonstrated that the lines in question can be safely operated at the increased maximum operating pressure," commissioner Mike Florio said in a statement.
PG&E spokesman Brian Swanson said that the utility has completed an "exhaustive" series of strength testing since April, which covered 160 miles of gas pipelines throughout its service area.
The three pipelines being restored are a 34-mile portion of a transmission line from Milpitas to San Francisco International Airport, a 1.5-mile section in Mountain View, and a 3.8-mile section in San Carlos and unincorporated San Mateo County, according to PG&E.
Complete testing and records review have not yet been completed on Line 132, which continues to operate at 20 percent below maximum allowable pressure, Swanson said.