Starting in May, Pacific Gas and Electric Co. plans to begin pressure-testing 150 miles of natural gas pipelines that have similar characteristics to last year.
In Mountain View, the company will conduct water pressure, or "hydrostatic," tests to 1.45 miles of pipeline 132a to determine the reliability of the segments, particularly because the pipeline is beneath densely populated or "high consequence areas," PG&E spokesman Joe Molica said. Pipeline 132a runs through the Rex Manor neighborhood.
"We want to reassure folks that our pipeline system is monitored 24 hours a day and we have strong safety procedures in place," Molica said. "This is yet another step we are taking to enhance our pipeline system."
PG&E prioritized the pipelines to be tested based on 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 require pressure testing in 1962.
The characteristics of Line 132a that it shares with Line 132, Molica explained, include either that the utility has been unable to find pressure test records for it, or the pipes are pre-1962 that measure 24-to 36-inch double submerged arc-welded pipe or pre-1974 seamless pipe greater than 24 inches in diameter.
Hydrostatic pressure testing involves filling a section of pipe with water, pressurizing it to a higher level, from 50 percent with natural gas pressure to 80 percent with hydrostatic pressure, and then monitoring it for eight hours, Molica explained.
If the test is successful and the pipe is determined to be sound, the section is emptied, dried and put back into service. If the test is not successful, the pipe would be replaced with a newer pipe built to withstand the pressure.
To explain this and answer any questions, PG&E will hold meetings in Mountain View for residents on Monday and Tuesday, April 25 and 26, from 5:30-8:30 p.m. both nights, at , 1701 Rock St. Spanish interpretation will be available.
The dates and times of the meetings will also be announced in a letter PG&E is sending to residents this week.
Though the process requires sections of pipeline to be taken out of service for possibly two weeks, there will be no interruption in service, because the utility will use alternate pipelines, according to Molica.
PG&E will also conduct an engineering analysis of pipelines that run through high-consequence areas, which could include taking X-rays of welds and seams and inspecting the interiors of pipes with robotic cameras.
"There will be some noise, especially when we empty out the gas, and it might smell like gas, but we hope to minimize the inconvenience to neighbors," said Molica.
For more information, contact PG&E at 888-743-7431, or, in Spanish, 800-660-6789. For a video of what the testing entails, click here.
—Additional reported by Bay City News Service
Editor's Note: On Monday, Apr. 25, removed the reference to the Stierlin Estates neighborhood. Pipeline 132a does not cross beneath this community.