Authorities said as many as four people were still missing as investigators searched for clues to the cause of a PG&E Corp. natural-gas pipeline blast that destroyed 37 homes in a San Francisco suburb.
The death toll remained at four and skeletal remains that were found at the site of the disaster yesterday were being tested to determine their origin and identity, Michelle Rippy, senior deputy coroner for San Mateo County, California, said today in a phone interview.
Some residents were being allowed to return to their homes today after the Sept. 9 pipeline rupture and fire that burned a 15-acre residential area in San Bruno.
Investigators for the National Transportation Safety Board, which is overseeing the probe into the cause of the explosion, began gathering evidence and making measurements yesterday at the site, which is about two miles (3.2 kilometers) west of San Francisco International Airport.
Federal authorities are sending a 28-foot piece of pipe that was blown about 100 feet out of the ground to Washington for further testing and analysis, NTSB Vice Chairman Christopher Hart said at a news conference today in San Bruno. That piece of pipe was made of sections welded together and officials will be looking at why it was constructed that way, Hart said at a news conference yesterday.
Investigators will also cut and analyze two 10-feet sections of pipe from the ends of the remaining line, Hart said today.
The blast left a crater in the street 167 feet (51 meters) long by 26 feet wide, Hart said.
California lawmakers pressed investigators, who said it may be 18 months before they can conclude their work, to quickly determine the cause of the incident.
“We cannot wait for answers to this,” U.S. Senator Barbara Boxer told reporters yesterday in San Bruno.
The NTSB will make recommendations if there are safety concerns that need “immediate attention” before a final report is published, Hart said today.
PG&E, based in San Francisco and California’s largest utility owner, inspected the pipeline in November and performed an annual gas-leak assessment in March, Geisha Williams, senior vice president of energy delivery of PG&E’s Pacific Gas and Electric utility said yesterday during an interview.
Williams declined to discuss the results of the two inspections.
California regulators will require PG&E to inspect its natural gas system as a result of the explosion, the California Public Utilities Commission said today in an e-mailed statement.
PG&E has not been able to confirm reports that residents made calls to the utility complaining of a gas smell in the days before the explosion, Chris Johns, president of PG&E’s Pacific Gas and Electric, said.
Federal authorities so far have not been able to document those claims, Hart said today.
The utility has searched about two-thirds of its phone records from the neighborhood from Sept. 1 through Sept. 9, Johns said. Utility crews weren’t at the site at the time of the blast, he said.
The company has $992 million in liability insurance for damages caused by fire, according to a public filing on Sept. 10.
“If it is ultimately determined that we were responsible for the cause of the incident, we will take accountability,” PG&E said in an e-mailed statement.
Financial results “could be materially adversely affected” if, after the explosion is investigated, insurance is insufficient or unavailable, PG&E said in the filing.