San Bruno Explosion Focus of 1st Fed Hearing in Decade

By Published On: March 4, 2011

Safety shutoff valves could have significantly limited the damage caused during last year’s natural gas pipeline blast in San Bruno, Pacific Gas & Electric officials acknowledged during a federal hearing this week. PG&E gas system managers said that if safety valves had been installed, the utility could have isolated the gas line that caused the deadly Sept. 9, 2010 blast. The valves could have shut off the gas in 30 minutes--a third of the time it took to close them manually, according to testimony given during a March 1-3 hearing at the National Transportation Safety Board (NTSB) in Washington D.C. This week marked the first time in over a decade that the Safety Board held hearings on a single pipeline accident, according to Peter Knudsen, board spokesperson. “The Safety Board does not hold public hearings on every investigation; we simply don’t have the resources,” said Deborah Hersman, NTSB chair. “However, we do hold several public hearings each year where there is a wide and sustained interest in the accident and in this case, an opportunity for lessons to be learned by discussing the facts and circumstances of the accident in the public view.” PG&E’s testimony this week contrasted with an internal memo stating that safety shutoff valves had “little or no effect” on human safety or property protection. The 2006 memo was prepared by PG&E gas engineer Chih-hung Lee, who testified March 1. Lee was grilled by Safety Board officials who pointed to a passage stating that the duration of a gas flame has little or nothing to do with human safety or property damage, despite federal studies contradicting that conclusion. Lee noted that no federal studies were looked at when coming up with the policy; only industry references. “What would have been the time it would have taken those valves to activate, and isolate the break?” NTSB chief of pipeline and hazardous materials Bob Trainor asked Lee. Lee admitted that if remote valves had been used on the pipeline at issue, the valve would have been shut off in “probably a half hour” and not the hour-and-a-half that it took to close the two manual valves to isolate the rupture. “What we’ve done since this terrible tragedy is step back” and re-evaluate that policy, said Edward Salas, PG&E’s senior vice president of engineering and operations. “As a matter policy we have placed automatic and remote-controlled valves in our system” he said. “We do so in very specific applications,” particularly over seismic faults, he added. Subsequently, utility representatives pointed out that the nearby replacement of an underground sewer pipe in 2008, which involved shaking to break the old sewer pipe in place of retrenching, may have damaged the gas line. “We are very interested in what PG&E knew, and whether action by the Contractors State License Board is appropriate against the [sewer] contractor,” said Richard Clark, California Public Utilities Commission consumer protection and safety director. PG&E also came under criticism for spiking the pressure in the old pipeline. The San Bruno explosion and resulting fire occurred when a 30-inch natural gas pipeline ruptured. The explosion created a 76 foot long crater and a 28-foot segment of the pipe was blasted out of the ground. Eight people were killed and 38 homes were destroyed. Once the fact-finding stage is completed, Hersman said the NTSB is set to prepare a report and hold a public meeting to consider the evidence and determine the probable cause.

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