Pacific Gas & Electric will conduct comprehensive tests of Turlock’s aging natural gas pipelines in the coming months, in efforts to ensure the pipeline does not fail as in the 2010 San Bruno pipeline explosion which killed eight people.
The hydrostatic testing will not interrupt the flow of natural gas to households or customers, PG&E said. The work is only expected to cause minor traffic congestion where PG&E excavates small areas to access the pipelines.
The hydrostatic testing will see the pipeline segments removed from service, vented of all natural gas, mechanically cleaned, sealed on both ends, and completely filled with water. The water will then be pressurized much higher than normal operating pressure, and monitored for eight hours to detect leaks.
Should the test be successful, the pipeline will be emptied, dried, and placed back into service. If problems are found, the pipeline is replaced.
According to Richard Dye, with PG&E Government Relations, only two “pinhole” leaks were found in 160 miles of tested pipeline last year. One of those, in Bakersfield, was a 4-foot-long rupture in a pipe seam, which blew a “sizable crater” in a farmer’s field, according to a San Francisco Chronicle report.
Though Turlock’s pipelines date back to the 1960s, PG&E officials said they have seen no indication of a problem with local pipelines.
“We anticipate to find the pipes in great condition,” Dye said. “If it's not, we'll fix it.”
Turlockers may smell natural gas when the pipeline is vented, which should quickly dissipate, and may also hear a loud bang, like a gunshot.
The work to test Turlock’s pipes will be conducted in two phases.
The first will test a segment along North Golden State Boulevard, from near Highway 99 to Fulkerth Road. The segment then proceeds south on Soderquist Road to Canal Drive.
PG&E said initial work to excavate pipe endpoints will begin July 5, with venting planned for July 17, testing on July 26, and the pipeline returned to service Aug. 3.
The work is not expected to interfere with the nearby Stanislaus County Fair, running from July 13 to July 22. PG&E spokesperson Nicole Liebelt said the utility expects no traffic impacts to the fair, and noted testing will not begin until the fair is over.
“We’ve taken into account that obviously the fair is something that is very important to the community,” Liebelt said.
The second segment follows Geer Road from Fullerton Drive in the north to Syracuse Avenue in the south.
PG&E expects construction to begin in mid-August, with testing in mid-September and the pipeline returning to service by the end of September.
Before conducting the tests, PG&E expects to send letters to residents and businesses near the pipelines, notifying them of the pending testing. Open house meetings will also be held to discuss the upcoming work.
Once testing is complete, a second set of letters will be sent out to notify residents and businesses of the results.