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Aerial view of damage caused by a massive fire in a mostly residential neighborhood in San Bruno, Calif., Friday, Sept. 10, 2010. Fire crews tried to douse the remnants of an enormous blaze and account for the residents of dozens of homes Friday after a gas line ruptured and an explosion ripped through in a neighborhood near San Francisco. (AP Photo/Jeff Chiu)
The hearing did not come with any "Law and Order-type" moment of surprise or conclusion. We still don't know why the PG&E pipeline exploded killing eight people and destroying dozens of homes.
In the end, federal investigators were only able to make a call for new solutions to improve the safety of all of the country gas pipelines. Chairwoman Deborah Hersman says the accident highlighted a pattern of recurring safety problems and said the regulations guiding the industry may require reforms.
PG&E echoed the call for safety reforms in a statement released last Thursday:
"Today’s panel of experts underscored the need for pipeline operators to have multiple inspection tools available so the method best suited to each pipeline can be applied. The discussions also reinforced the importance of developing new and better technologies to enhance safety."
The Mercury News found a new theory on a possible cause. New documents made public this week show a PG&E inspector has expressed concerns about a 2008 installation of a sewer line installed ten inches below the PG&E gas line that exploded and just 15 feet away from the actual rupture site.
The sewer line installation involved something called "pipe bursting," which involves violent shaking and, although not proven, could have weakened the welds of the PG&E line.
The Merc said they reported on the sewer work in the first days after the explosion, but it wasn't until this week that they learned it might have been more significant.