WASHINGTON — Officials for a California company involved in a deadly
pipeline explosion last September acknowledged Tuesday that four years
before the accident they rejected installing safety valves that could have
automatically shut off or remotely controlled the flow of natural gas.
Pacific Gas and Electric Co. employees were questioned at a National
Transportation Safety Board hearing about a 2006 memo that said
installing the valves would have “little or no effect on increasing
human safety or protecting properties.”
Gas engineer Chih-hung Lee, author of the memo, said he considered
only industry studies, not government studies, in reaching his
conclusions. Industry studies, he said, found that most of the damage in
natural gas pipeline accidents occurs in the first 30 seconds.
However, when the pipeline ruptured on Sept. 9 under a suburban San
Francisco subdivision, gas continued to feed a pillar of fire for an
hour and a half before workers could manually shut off the flow. Eight
people were killed, many more injured and dozens of homes destroyed.
Investigators pointed to a 1999 Transportation Department study that
warned that there is a significant safety risk as long as gas was being
supplied to the rupture site and operators lacked the ability to quickly
close manual valves.
“Any fire would have greater intensity and would have greater
potential for damaging surrounding infrastructure if it is constantly
replenished with gas,” the government study said. “The degree of
disruption in heavily populated and commercial areas would be in direct
proportion to the duration of the fire.”

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