Starting in May, Pacific Gas & Electric plans to begin pressure-testing 150 miles of natural gas pipelines that have similar characteristics to the line that exploded in San Bruno last year.
The company will conduct water pressure, or "hydrostatic," testing to determine the reliability of numerous pipeline segments throughout its service area, mostly those beneath densely populated or "high consequence areas," PG&E spokesman Joe Molica said.
"A portion of that is going to be in the Bay Area," Molica said.
The first pressure tests will take place in Antioch and Mountain View, and PG&E prioritized the pipelines to be tested based on their similarities to Line 132, which exploded when it ruptured on Sept. 9, 2010, killing eight people.
Molica said Line 132 was installed before the state began requiring pressure testing in 1962, it was between 24 and 36 inches in diameter, and there were incomplete records regarding pressure tests.
Hydrostatic pressure testing involves filling a section of pipe with water, pressurizing it to a higher level than it would operate with natural gas, then monitoring it for eight hours, Molica said.
If the test is successful and the pipe is determined to be sound, the section is emptied, dried and put back into service.
PG&E will be holding open house meetings for Mountain View and Antioch residents regarding hydrostatic testing in their neighborhoods. The dates and times of the meetings will be announced in a letter PG&E is sending to residents this week.
The process does require sections of pipeline to be taken out of service for several days, Molica said, though the utility will avert interrupting service to homes and businesses by using alternate pipelines.
PG&E will also be conducting an engineering analysis of pipelines running through high consequence areas, which could include taking X-rays of welds and seams and inspecting the interiors of pipes with robotic cameras.