PG&E’s control center logs reveal growing chaos on night of San Bruno blast 

At 6:26 p.m. on Sept. 9, one of the operators manning PG&E’s lines in the San Francisco natural-gas control room looked at the clock and wondered why it was moving so slowly.

It had been a long day — major problems had cropped up when engineers tried to fix a broken piece of equipment in Milpitas, and it was taking serious time and attention to resolve. A colleague called up and the pair talked about the approaching quitting time, which apparently couldn’t arrive quick enough.

“Half an hour. Jesus,” said the operator.

“Look at it this way — you won’t get in the bad traffic,” his colleague said.

“Yeah, I guess,” the operator said.

Needless to say, traffic would be the least of the operator’s problems that night, a fact that became eminently clear less than 90 seconds later, when a call came in from a PG&E dispatch center in Concord.

 “Quick question,” the dispatcher said. “You guys lose any pressure or anything out in San Bruno? I’m getting a couple of calls right now that they’re saying there’s a flame I guess that’s shot up in the air.”

“In San Bruno?” the operator said. “We have not received any calls yet.”

Unbeknownst to PG&E’s control-room operators in San Francisco, a pipeline they were in charge of overseeing in the Peninsula suburb had ruptured about 15 minutes earlier and a whole neighborhood was now engulfed in gas-fed flames.

Those early moments after the San Bruno blast are among many captured in hundreds of pages of transcribed calls and interviews released at the start of the three-day federal hearing about the disaster in San Bruno on Tuesday.

Many of the documents peered into the history of the pipeline’s engineering, and others cataloged the response to the disaster that would come over the next five months.

But the 400-page transcript of PG&E’s gas control center captures the drama of the night itself, as first responders and PG&E staff struggled to respond to the terror that unfolded.

In the moments after that first call from the Concord dispatcher, the response is one of increasing adrenaline:

“Line break in San Bruno. Line break in San Bruno. Check it out,” an unidentified caller says at 6:29.

The operator curses, then pulls up a screen allowing him to check the pipeline pressure in the area, which normally stagnates around 360 pounds of pressure, but now looks like it is attached to a roller coaster.

“Just watching the pressure just plummet like a rock,” the operator says. “So Line 132 pressure was up at 396 and now it’s down to 56 pounds.”

Over the next few minutes, he and other operators make a flurry of calls to find someone who can respond to the scene, mostly reaching voice mails or automated phone services.

Gas control operator Michael Valenti leaves an oddly prescient message for another natural-gas supervisor, speculating that the problems from earlier in the day at the Milpitas station may have sent a pressure spike through the system, busting a pipe at a weak seam — a scenario fully fleshed out five months later at Tuesday’s hearing.

“Listen, we’ve got pressure dropping like a rock here at Martin Station,” he said. “We did have some issues going on with the clearance right now in Milpitas where the lines are being overpressured. ... It’s possible that, I don’t know, maybe a seam broke somewhere .”


Fatal chain reaction

As part of San Bruno erupted in flames, PG&E officials were unaware of the issue, according to a timeline provided in documents released Tuesday. The timeline also highlights the length of time it took before the gas line could be shut down, ending the inferno that destroyed 38 homes and killed eight people.

  • 2:46 p.m. Gas control technician reports that a team will be working on broken equipment in Milpitas — work that leads in the coming hours to pressure swings in the pipes, power problems and communication failures.
  • 4:20 p.m. Pressure in the pipes drops extremely low, but returns to normal 12 minutes later.
  • 5:23 p.m. Pressure in the pipes soars, and stays extremely high over the next 48 minutes.
  • 6:11 p.m. Pipeline 132 ruptures, spewing flames 200 feet in the air and starting a fire that will kill eight people, injure dozens more and damage or destroy 100 homes.
  • 6:12 p.m. First San Bruno Police Department unit arrives on scene.
  • 6:17 p.m. First San Bruno Fire Department unit arrives on scene.
  • 6:18 p.m. PG&E’s Concord dispatch center is notified by an off-duty employee about a huge fire in San Bruno. Dispatch begins calling supervisors and on-duty employees asking for a response.
  • 6:27 p.m. PG&E’s Gas Control Center in San Francisco, which has charge of the line, first learns that there might be a problem.
  • 6:31 p.m. The Gas Control Center speculates the line might have been involved in the incident.
  • 6:40 p.m. An on-call PG&E supervisor contacts a mechanic to try to shut off the gas.
  • 6:54 p.m. Concord dispatch tells a PG&E supervisor that it has been told “a plane has crashed into a gas station and took out some houses in San Bruno” and says it has been requested to turn off gas and electricity to the area.
  • 7:20 p.m. Mechanic crew arrives at a valve location.
  • 7:29 p.m. Gas control remotely closes some of the valves north of the pipeline. 
  • 7:30 p.m. Supervisor and mechanic crew close a valve south of the pipeline.
  • 7:42 p.m. Flames diminish.

Source: NTSB

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Katie Worth

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