Story updated at 7:39 p.m. April 15.
The National Transportation Safety Board released a new set of documents Thursday revealing more information as part of its ongoing investigation into the Sept. 9 gas explosion and fire.
Included in the documents are 13 interviews with PG&E employees totaling more than 500 pages that reveal new details about how the utility responded to the explosion and how Line 132, the pipeline that ruptured in the Crestmoor neighborhood, was being monitored and maintained before the disaster.
A new photo taken by the on the night of the fire was also released.
The records are among thousands that the NTSB has been making public since it held a , on the explosion in March.
Among the findings were documents that showed sections of Line 132 were built with scrap metal and welded together with other sections of transmission pipe manufactured in the field when the line was installed in 1956.
In a , the NTSB said it found a number of defective welds on the section of pipe that exploded—a pipe that PG&E originally reported as seamless and investigators later found to have been welded together with a number of longitudinal seams.
When asked to provide more details about why the pipe was manufactured using longitudinal seam welds, a PG&E official told investigators during the hearing that it was still unclear from records how the pipeline was built.
Problems with power supply before gas pressure changed
Among the documents released were interviews with a crew who had been working in the Milpitas terminal on the day of the explosion.
Crew leader Peter Beck, gas control technician Oscar Martinez, apprentice Eduardo De La Torre and contractor John Groppetti had been working all day on replacing an uninterruptible power supply, or UPS, at the terminal. A UPS is a backup system designed to keep electricity constant in the event of an emergency, and the crew members were working on replacing the system because it had failed six months earlier.
About 4:30 p.m., the crew ran into a problem with the system when they lost power.
Martinez and Beck switched off the power supply system in the control room.
The men then methodically went through various steps, restored power, and “everything came back up and running, as planned. So that was pretty much it,” Martinez said.
The crew was getting ready to end their day when at 5:23 p.m., Groppetti, who had been talking to his wife on the phone, noticed Martinez begin to panic.
“Oh shit,” Martinez said.
“What’s wrong?” Groppetti asked.
“I…walked into the controller room and about that time I saw that we lost all data on all of the controllers,” Martinez told investigators, meaning the monitors that allowed workers to gauge pipeline conditions had gone dark.
Martinez also noticed the voltage on one of the circuits dropped from 24 volts to about 5 or 7 volts.
That’s when the electrical system malfunctioned, causing the gas pressure on Line 132 at the Daly City Martin Station, which is downstream from where the rupture occurred, to spike past its maximum operating pressure of 375 pounds, eventually reaching 390 pounds.
At 6:08 p.m., the gas pressure dropped to 386 pounds, then to 361.4 pounds and then significantly dropped again to 289.9 pounds moments before the pipeline exploded in the Crestmoor neighborhood.
Groppetti said the crew spent two and half hours trying to restore the power supply. All the while, unknowingly to the crew, a fireball 39 miles away was raging through the Crestmoor neighborhood.
“The last word I got was all of the work on the UPS system was put on hold. We weren’t going to do anything until we were given the go-ahead,” he told investigators. “And then it was just a series of meetings with lawyers and PG&E, and we’re trying—we’re trying to figure out exactly what happened, which is very hard.”
The crew was told to go home about 4:30 a.m. the next morning. All the men were asked to take drug tests.
During its investigation, the NTSB has been looking into the to determine whether the malfunction could have played a role in the explosion.
No conclusions have been reached yet, and experts have said the pressure spike in the pipeline probably had no effect on the explosion.
'I knew that that was something'
In another interview with investigators, an off-duty PG&E gas mechanic described how he had an almost sixth sense for the explosion when he saw the fireball unfold on his TV screen just as he was getting ready to sit down and eat and watch the football game.
The PG&E mechanic, Michael Hickey, had no sense of anything being out of the ordinary until a news bulletin came on announcing a plane crash.
Hickey went outside. To the south, he saw a large plume of smoke, but no outline of a plane. He knew a transmission line ran through the area. He went to his car, got his company cell phone and called gas dispatch. Sounding “kind of nervous,” Hickey said, the dispatcher said he didn’t know.
“So I went back in the house again,” he told investigators on Sept. 17. “In my heart, I knew that that was something, not a plane crash.”
It was a three and a half mile drive from Hickey’s South San Francisco home to the Colma PG&E yard. On his way there he got a call from mechanic Ed Sickinger. Hickey told Sickinger to meet him there. He got another call, from the on-call supervisor asking him to come in, but he was already on his way.
It was about 6:40 p.m. when he started calling other mechanics: first Brian Olivolo, then Brad Schubach. When the dispatcher said he had no phone number for a third mechanic, Craig Fazackerley, “I started to use some foul language on him,” Hickey said. “I mean, I was pretty unhappy at that point.”
He turned on the television in the break room. When the helicopter panned out, “it was quite clear what it was,” he said. “Two transmission lines had crossed there, the 109 and the 132. The 109 proceeds east, down San Bruno Avenue. The 132 cuts south and goes right that that, or it cuts south and goes down Glenview in San Bruno.”
He called supervisor Steve Poulo and told him he knew where the critical valve was—San Andreas Lake—and was going to shut it off. Mechanics began pouring into the yard as he and Sickinger headed out, encountering heavy traffic. About a 10-minute drive, “it might have been 15 to get there,” Hickey says. “I was fighting through looky-lous.”
He used a valve key—a wrench—to shut it down. It took about 57 turns.
“I could feel a little fight,” he said. “It was fighting to stay open.” He took another key and cinched it tight. He put a PG&E cone at the site and headed to Bill Healy Station on Crestwood Drive near Rollingwood Drive. All the valves are clearly marked there, he said. It was 7:43 p.m. when he opened a three-lock gate and located the main line valve.
“You were able to open the gate?” asked investigator Richard Downs.
“If I didn’t, I had a truck. You know what I mean?” Hickey said. “It’s going down and it’s going quick.”
It took 100 turns of the wheel to close this valve. Then the men closed a second valve. Then they back-tracked to Sneath Lane and a regulator station, and still another valve. Then it was on to the command post, where he checked a chart to make sure that there was no flow in the lines.
“It was dead zero,” Hickey said.
Pipeline records weren't checked
Other information from the transcripts included an account from Gene Muse, PG&E’s integrity management program engineer, who explained how the utility had determined that Line 132 was a seamless pipe. Muse said PG&E’s pipeline mapping record from 1956, when the gas transmission line was installed, labeled the pipe as being seamless. When a team went in 1998 to manually transfer their pipeline records over to a new electronic mapping system, they assumed the information from the records was true.
"The sole object was to take our pipeline survey sheets that we used from 1956 to the present, and whatever information was on there, we assumed was accurate and precise," Muse said.
"Was there any analysis performed on any of that data in the process?" asked Peter Katchmar of the Pipeline and Hazardous Materials Safety Administration.
"No," Muse replied.