A gas pipeline that exploded in flames in a San Francisco neighborhood earlier this month shows damage consistent with being ruptured by third-party excavators, the National Transportation Safety Board said Wednesday.
In a preliminary report, investigators also say the Feb. 6 fire took more than two hours to extinguish, though crews from Pacific Gas & Electric were on-site 20 minutes after the fire began.
The agency will continue its investigation into whether the third-party, Kilford Engineering, was sufficiently prepared and qualified to do the excavation work.
Officials with Kilford could not be located for comment. Its business listing with the city of San Francisco did not list a phone number.
The board will also examine the response by city officials and PG&E.
Utility workers took two hours to isolate and shut off gas fueling the fire, prompting questions from some as to why it took so long. PG&E officials said crews needed to dig by hand and that they didn't want to shut off gas to more customers than necessary on what was a cold day.
The fire destroyed Hong Kong Lounge II, a popular Chinese dim sum restaurant that is a fixture on the city's "best of" lists. It also forced 100 people to evacuate and disrupted natural gas service to more than 300 customers.
There were no injuries.
The federal transportation safety agency often investigates blasts on pipelines because they transport oil and natural gas, which the board oversees.