Federal investigators Monday finished their initial investigation of
the site of Thursday’s gas-pipe explosion in San Bruno and are now
focusing on reviewing documents and interviewing witnesses, a spokesman
The National Transportation Safety Board finished examining
pipes that were laid under the gas line that exploded and concluded
they did not contribute to the blast, board vice chairman Christopher
It was initially unclear whether the excavation and installation of those pipes damaged the gas line, he said.
Investigators have now turned the ditch over to the city of San Bruno and PG&E so infrastructure can be restored, Hart said.
Transportation safety board investigators are now looking at
documents from PG&E, visiting control and monitoring sites, and
examining valves that have been preserved for evidence, Hart said.
The transportation safety board is also looking at seismic
records to see if any activity has occurred recently that could have
affected the pipes, Hart said.
The agency has also begun to receive results of toxicology tests
conducted on PG&E employees. So far the workers have tested
negative for drugs and alcohol, Hart said.
“We’ll be interviewing witnesses, including people from PG&E, over the next few days,” he said.