SAN FRANCISCO — Despite flawed and incomplete records for a key natural gas line, PG&E engineers raised the pressure on the pipe, which eventually blew up and leveled much of a San Bruno neighborhood, according to testimony presented Wednesday in the utility’s federal criminal trial.
“It was commonly known within the organization” at PG&E that a geographic database the utility used as a major component of its pipeline records was inaccurate and flawed, Todd Arnett, a supervising gas engineer with PG&E, testified during the trial in U.S. District Court.
The testimony also disclosed that PG&E was eager to increase the pressure on a section of natural gas pipeline known as Line 132 to a high enough level to enable the utility to establish a benchmark for the line’s maximum operating pressure.
For certain gas pipelines constructed before 1970, utility operators are required to establish the maximum pressure based on the top pressures recorded during a five-year window. That included the pipe that ruptured in San Bruno.
“We need to do whatever it takes to keep the maximum operating pressure of Line 132 at 400 pounds per square inch,” Jason Reider, a PG&E gas engineering executive, wrote in a November 2008 email to other PG&E officials.
If PG&E hadn’t been able to maintain the 400-psi benchmark, it would have had to make sure the pressure on the line never topped 373 psi — which would have reduced the utility’s delivery capacity in that area.
Line 132 normally operated at 375 psi, according to internal PG&E memos entered into evidence Wednesday.
“There are sections of Line 132 that have suspected manufacturing threats,” a PG&E executive wrote in one of the memos.
Despite the concerns circulated among PG&E engineers, pressure in the line was spiked sometime in late 2008, according to a PG&E email.
“Line 132 reached 400 psi a little bit ago,” William Manegold wrote in an email in December 2008.
Less than two years later, a section of Line 132 exploded. The September 2010 blast killed eight people and destroyed dozens of homes.
“This pressure spike was a deliberate decision by PG&E,” Connie Jackson, San Bruno’s city manager, said outside the courtroom during a break in the trial. “But it was clear that PG&E knew there was a risk associated with raising the pressure to 400 psi.”
It also appeared that PG&E largely relied on a database called the geographic information system as a primary foundation for its records on Line 132 and other gas pipelines.
“I didn’t look at any records other than a cursory review of the GIS,” Arnett testified, describing his procedure to verify the condition of pipes such as Line 132.
But that system wasn’t deemed accurate by many PG&E engineers.
“We do not trust GIS to be accurate,” an internal PG&E memo stated.
San Francisco-based PG&E faces 13 criminal counts in the case, including 12 allegations by prosecutors that it violated pipeline safety rules, and one charge that it obstructed an official investigation into the explosion.
PG&E made a series of “deliberate and illegal choices” — and subsequently covered up those decisions — actions that led to the explosion, federal prosecutors said earlier in their opening statements.
But defense attorneys countered in their opening statements that individual employees and executives at PG&E are not guilty of any criminal acts and did their “level best” to operate the system safely and efficiently.
PG&E has pleaded not guilty to all the charges. If convicted on all the counts, PG&E faces a fine of up to $562 million.
Contact George Avalos at 408-859-5167. Follow him at Twitter.com/georgeavalos.
