A 1989 memo, found during a search of 11 million documents, said a natural gas pipeline near San Bruno, Calif., had a history of weld failures, the San Francisco Chronicle reports.
A pipeline in the area exploded in 2010, killing eight people and destroying 38 homes. The National Transportation Safety Board found PG&E didn't know what kind of pipe was beneath San Bruno and last year said defective welds contributed to the explosion.
The newspaper reports that PG&E indicated, in the memo, that a weld seam failed and likely caused a leak in 1988 about 9 miles south of the San Bruno accident.
PG&E announced in March that it reached an agreement to pay $70 million to the city of San Bruno in restitution for recovery efforts after the deadly 2010 pipeline explosion.
A report from California regulators found that PG&E's record-keeping on its gas transmission lines was substandard.