Investigators probe San Bruno explosion

November 2010, Vol. 65 No. 11

Investigators, including the National Transportation Safety Board, are looking at whether repair work on a sewer pipeline close to a gas transmission line was responsible for a deadly explosion that shook a San Bruno, CA, neighborhood on Sept. 9, killing four people and injuring several others.

It also severely destroyed 56 homes, prompting the Obama administration to propose intensified pipeline safety oversight. According to the Los Angeles Times, the sewer work in 2008 had possibly been repaired in an unsafe fashion that potentially caused damage to pipelines in the area.

In 2008, the city of San Bruno replaced a sewer line near the gas transmission line that exploded on Sept. 9 in one of the nations’ deadliest pipeline failures in nearly a generation. When the sewer line was replaced, pipe bursting technology was used to increase the size of the pipe from a 6-inch to a 10-inch diameter. Pacific Gas and Electric, the company that owns the pipeline that exploded, says it inspected the pipeline before and after the sewer work was completed.

The National Transportation Safety Board is not confirming that sewer work could have increased the risk of an explosion, but the agency is also looking at this critical angle as it continues its investigation.