City of San Bruno Disputes Panel’s Report Blaming Pipe Bursting

August 2011, Vol. 66 No. 8

San Bruno attorneys added that the panel incorrectly blamed the sewer project without even interviewing the sewer contractors, reviewing the project specifications or talking to San Bruno engineers who signed off on the work.

Instead, the state-chartered panel relied on a gas industry group's report, the Interstate Natural Gas Association of America (INGAA), that incorrectly described the scope of the sewer project, plus the findings of a consultant who did not know all the facts, the city claims.

In May, INGAA, whom PG&E joined after the San Bruno blast, suggested pipe bursting as the likely cause. However, the industry group dismissed vibrations from the sewer pipe bursting as being a factor in weakening the PG&E line. Instead, it said forces exerted by a winch used to operate the sewer equipment - and a pulley braced against a pit wall near the gas pipe - had pushed against the PG&E line and bent it out of a round.

A Texas pipeline integrity expert and consultant, Royce Don Deaver, challenged that finding. He said he had modeled the actions of the winch and pulley against the wall and that the actual forces had been negligible, amounting to no more than the load of a 250-pound person standing on one foot.

When queried by local media, the blue-ribbon panel did not defend its original finding. Instead, it alluded to failures by both PG&E and regulators to ensure safety.

Testimony omitted
Further, the city of San Bruno claims that if the state panel had interviewed the sewer project's contractor, D'Arcy and Harty Construction of San Francisco, it would have learned that the company took standard steps to ensure that workers would not damage the PG&E line.

PG&E, which has issued a public apology for the natural gas explosion in San Bruno, said in an initial court filing in early July that it should not have to make payouts to victims who have sued the company because the blast was caused by third-party damage to a "state of the art" pipeline.
The company also indicated it would seek to assign some of the blame for the losses from the explosion to residents themselves.

PG&E quickly back-pedaled within a week of that filing and assured victims of the San Bruno natural gas pipeline explosion that it did not intend to argue in court that they were to blame for losses they suffered in the disaster.