Utility crews replaced five miles of aging gas pipes under a Northern California neighborhood less than two decades ago, but stopped just short of a segment that ruptured and exploded last year, according to documents released this week in a federal investigation into the deadly blast.
Records showed that Pacific Gas & Electric Co. had replaced the pipes in San Bruno for seismic safety concerns in 1994. The new, stronger steel pipes, however, ended about 300 yards from the epicenter of September's explosion, which killed eight people and destroyed dozens of homes.
PG&E spokesman Joe Molica confirmed to the San Jose Mercury News that the earthquake safety upgrades were done, but said the segment that ultimately ruptured was not on the list for the project, which focused only on seismic risk.
An earthquake on the San Andreas Fault, which runs near the neighborhood, could cause a displacement of up to 10 feet, PG&E officials wrote in the documents.
Molica said officials were still working to determine why the work didn't replace all the pipes in the area.
"I'm sorry I don't have more," Molica told the newspaper. "We are in the middle of doing a comprehensive records review. This is a massive undertaking."
The National Transportation Safety Board released the documents, among others, to coincide with the three-day public hearing in Washington that concluded Thursday. During the hearing, PG&E executives, local officials and experts testified about the decisions that led up to the rupture, which occurred after a sudden pressure spike stressed the aging pipeline segment.
Federal officials later found more than 150 welding defects in the pipe, which was installed in 1956.
The newer pipe placed near the blast epicenter was made of a thicker steel, and PG&E touted in a 1993 notice to customers that the replacements "should last for another 80 to 100 years."
"Oh my God. It's stunning. It's really amazing," Bill Magoolaghan, whose house was damaged in the blast, told the Mercury News. "But for another block of digging, and we wouldn't have lost eight neighbors."
Information from: San Jose Mercury News, http://www.sjmercury.com