Witness says PG&E misled investigators after San Bruno blast

Pacific Gas and Electric Co. deliberately misled investigators following the September 2010 pipeline explosion in San Bruno, the lead investigator told a federal court jury in San Francisco on Wednesday.

Ravi Chhatre, who led the investigation for the National Transportation Safety Board, said PG&E gave investigators insufficient data and faulty evidence as they sought to determine what caused the explosion that killed eight people and destroyed 38 homes.

At the center of the obstruction charge is a PG&E letter that disowns an internal memo the utility had provided to investigators.

The memo described a policy of testing older lines for welding problems only if gas pressure exceeded the federal maximum by 10 percent.

Evidence of the leak was collected by PG&E just a week after the San Bruno explosion occurred, according to court documents, but was not reviewed or provided to investigators until some eight months later.

Robert Fassett, PG&E’s liaison to the NTSB investigation, was removed from his position at Chhatre’s request after the investigator discovered what had happened.

Fassett’s replacement, William Hayes, former vice president of gas maintenance and construction for the utility, signed the April 2011 letter that is the focus of the obstruction charge.

Company officials called the higher pressures “within generous safety margins” built into maximum operating pressures, according to materials they submitted during investigation.