The operator of a Bay Area gas pipeline that exploded in a lethal firestorm earlier this month has reported leaks on similar lines in populated areas at a rate more than six times that of other large pipeline systems across the country, according to a Times analysis.
Pacific Gas & Electric Co. has reported 38 leaks since 2004 along about 1,000 miles of line it controls near population centers or environmentally sensitive resources, federal records show.
The utility's leak rate was 6.2 annually per 1,000 miles of transmission pipes serving "high consequence" areas — more than six times the average leak rate for the nation's six other large operators.
Federal regulators have stressed that the number of transmission line leaks reported nationally in populated areas has declined more than 30% in recent years. But PG&E reports show an opposite trend, with average yearly leaks climbing some 40%, from 4.7 to 6.7.
The state's other large operator, Southern California Gas Co., reported leaks at a rate of 2.3 per 1,000 miles. Large operators are those with at least 500 miles of "high-consequence" pipelines.
In a written response to The Times, PG&E executives questioned the comparability of federal data because other utilities may differ in their surveying techniques and interpretation of reporting requirements. The utility also attributed its recent leak rates to a more rigorous reporting standard it adopted last year after consultations with federal regulators.
Michael Peevey, president of the California Public Utilities Commission, said this week that experts at the agency would review The Times' findings.
"Assuming the numbers are a reasonable representation of the situation, obviously I and this commission would find them deeply disturbing," he said. "They may indicate a more systemic problem at PG&E."
Peevey said he was particularly surprised that The Times found PG&E was reporting nearly three times as many leaks as the state's other big natural gas supplier, SoCal Gas.
Determining the cause of the blast in San Bruno, just south of San Francisco, is expected to take months as experts pore over records and conduct sophisticated forensic examinations of the ruptured pipe, including a large section blown out of the ground in the explosion. Seven people died and more than 50 homes burned down or were heavily damaged. Preliminary estimates of losses from the fires have been set at $65 million.
On Wednesday, U.S. Sens. Dianne Feinstein and Barbara Boxer introduced sweeping legislation to strengthen oversight of natural gas pipelines and establish penalties for violating federal regulations. The San Bruno blast has also raised questions about PG&E's operations and triggered debate over an array of broader issues, including the wisdom of allowing homes to be built close to potentially hazardous pipelines.
The leading causes of leaks reported by PG&E and other utilities with transmission pipelines in high-consequence areas have been equipment problems and corrosion, records show. Pipeline valves have been the most frequent equipment problem since 2004, PG&E said.
None of the leaks reported by PG&E came close in severity — or scale of losses — to the Sept. 10 San Bruno blast, one of the worst U.S. pipeline disasters in at least two decades.
The performance data analyzed by The Times was gathered by the federal Pipeline and Hazardous Materials Safety Administration to allow the public to assess the safety progress of specific pipeline systems. Inspection and public reporting regulations increased after a 2000 explosion of a 30-inch pipeline in New Mexico — the same size line that ruptured in San Bruno. The blast in Carlsbad N.M., killed 12 people.
A detailed analysis of leak reports is crucial to pipeline safety and risk management programs, said Brigham McCown, former head of the federal agency.
"Higher-than-average incidents may be indicative of a lax safety culture," he said. "Incidents exceeding similar operators in the same area should always raise concerns, especially when those incidents are caused by an operator as opposed to third parties."
Federal pipeline safety regulators say they do not compare or rank the performance of individual operators. A spokesman said regulators do monitor national trends and focus additional inspection oversight on systems with incident records outside the norm. In California, most of the pipeline inspection work falls to the state's utility commission.
PG&E's maintenance practices and leak management efforts are expected to be scrutinized by the National Transportation Safety Board, which is leading the probe into the cause of the San Bruno explosion.
"They will pull apart and look at every aspect of operations," said Kitty Higgins, a former NTSB board member. "To the extent there is a pattern, it's an issue of what was done once there was a problem and what kind of follow-up action there was."