- Published on Tuesday, 17 May 2011 17:00
- Written by Jana Seshadri - Staff Writeremail@example.com
Last September’s deadly gas-pipeline explosion in San Bruno raised many questions, with Los Altos residents asking, “Could that happen in my neighborhood?”
PG&E’s pipelines deliver natural gas to residents in cities across the Bay Area. Los Altos officials are working with the utility company to prevent such a disaster from happening locally, according to Jim Gustafson, engineering services manager.
“We have approximately 10,000 gas connections,” Gustafson said. “Every house in the city has gas delivered to it.”
Although he does not have a precise Los Altos PG&E map, Gustafson said gas pipelines run along Foothill Expressway, Grant Road and El Monte Avenue, and some of the lines are old.
“We’ve requested a utility grid map from PG&E, along with pipe conditions and schedules for testing,” he said. “They’re addressing similar requests from several cities.”
In the meantime, all development projects require underground utility work, which proceeds on a site-by-site basis, he said.
The gas line running under Los Altos along El Monte is the narrower, 4- to 8-inch-wide distribution feeder main line, not the wider, 24-inch transmission line, according to Brittany Chord, PG&E spokeswoman.
Installed in 1955, the Los Altos feeder lines deliver gas to residential areas, Chord said. Some new sections were added in 1998.
Proceeding with caution
Without a utility map for guidance, city officials take extra precautions while planning and executing construction projects to avoid undue mishaps, Gustafson said.
“We’re very cautious about our projects,” he said. “We follow the Underground Service Alert (USA North) system before construction.”
The USA system generates communication between city officials and PG&E before the shovel hits the ground, according to Gustafson. After a project plan is finalized, he notifies the utility companies – including PG&E – of the project details and awaits response. The companies inspect the plan to determine the scope of work required to ensure that cables and lines have enough separation from one another, he said.
Each utility has its own set of codes and standards it must follow. In addition to their rules, Gustafson’s team diligently takes care to guarantee that utility lines are out of the city’s way.
“Every project is challenging,” Gustafson said. “The underground is busy.”
The USA system might cause delays, but safety is the city’s No. 1 priority, he added.
San Bruno aftermath
Investigations and public hearings are ongoing months in the wake of the Sept. 9 San Bruno gas-pipeline explosion, which caused an inferno powerful enough to be seen from Los Altos Hills.
The rupture of the PG&E-owned and -operated natural gas pipeline – 30 inches in diameter – killed eight people, injured many more and destroyed 37 homes and damaged 18, according to the National Transportation Safety Board.
At San Bruno town hall meetings that followed, residents and family members shared personal accounts of what happened that day.
The powerful blast occurred after a major gas line running under a San Bruno neighborhood began leaking large volumes of gas, which ignited, blew a 28-foot section of the pipe out of the ground and set ablaze a dozen homes.
According to a Dec. 14 report by onsite investigators, PG&E’s pipeline in the ruptured area was installed in 1956 and connected with welds. It was not seamless, as the utility’s records indicated. While some sections were welded from both the inside and outside of the pipe, others were welded only from the outside.
After discovering that PG&E’s records for the San Bruno explosion area were inaccurate, National Transportation Safety Board regulators issued recommendations for the utility to follow.
Federal investigators directed the California Public Utilities Commission (CPUC), which regulates PG&E’s pipeline operations, to ensure that utility representatives search the records for more accurate information on their pipelines. If the document and records search cannot be satisfactorily completed, they must identify segments that had not undergone a testing regimen, to determine a safe operating pressure, explore the use of automatic/remotely operated shut-off valves and provide oversight of any testing conducted by PG&E.
It happened one night
in Los Altos
The explosion in San Bruno brought back painful memories for Los Altos resident David Hu, who experienced a similar crisis several years ago.
A faulty PG&E gas pipeline caused an explosion that blew apart Hu’s Frontero Avenue home in 2005. Hu and his two children were sleeping but managed to escape with minor injuries. His wife was out of the country at the time.
An investigation identified a copper gas-pipeline connector as the cause of the explosion. Gas began leaking at the failed connector, which joined two steel gas pipes and returned to the home through the sewer pipe, consequently causing the explosion that destroyed three-quarters of the home. A portion of Hu’s garage roof fell, and he was pinned under a mattress covered with debris. He and his children suffered bruises, scratches and minor injuries.
“We’re still coping with that. Once in a while, images of the past haunt me,” Hu said. “We’re doing fine now, thank God. It was nothing short of a miracle. We had several angels with their arms around us.”
Hu and his family have since moved from their damaged home but remain in Los Altos. Bound by legal obligations, he is unable to reveal more information and would rather put the entire episode behind him. Dealings with PG&E after the explosion have been satisfactory, he said.
Pipeline testing begins
Last month PG&E embarked on the task of safety testing its pipelines per CPUC directive, beginning in Mountain View and Antioch.
“What we are hydrotesting now is 150 miles of transmission pipelines based on characteristics similar to those of the San Bruno pipes,” Chord said.
The testing involves pressurizing a section of pipe with water to a much higher pressure than the pipe would experience with natural gas. The test validates the safe operating pressure of the pipeline. Crews tested a 1.5-mile stretch of 24-inch pipe that runs from Shoreline Golf Links to a street behind Crittenden Middle School, part of which was installed in 1944.
“The eight-hour test ended successfully in Mountain View,” Chord said. “There was no loss in water pressure, which means no leaks were found.”
PG&E established a comprehensive survey and monitoring program for ongoing reviews of the safety of its natural gas transmission pipeline system, Chord said. The company has taken significant initial actions to improve the safety and operations of the natural gas system and the security of the communities it serves.
PG&E pipelines of a similar size and age to the San Bruno line that have not been pressure tested are continuing to operate at pressures reduced by 20 percent, Chord said. PG&E is communicating with residents within 2,000 feet of its gas transmission pipeline throughout its service area, she said.
Additional testing in other cities will follow in the coming months. Los Altos is not on PG&E’s radar for the immediate future, Chord said, adding that Los Altos’ pipelines are significantly narrower and different from those that ruptured in San Bruno.
Residents interested in additional information on PG&E pipelines should contact the company directly, as city officials do not have such data, Gustafson said.
For more information, visit www.pge.com.