by: Laura Parker

(Sept. 10, 2010) -- Damaged pieces of 30-inch steel pipe pulled from the ashes may tell the tale of what happened in Crestmoor Canyon on Thursday night, when gas from a ruptured transmission pipeline fed a fire so intense it devoured 15 acres of houses in the San Francisco suburb of San Bruno, Calif., and killed four people.

What's certain is that the accident, coming on the heels of the BP disaster in the Gulf of Mexico, will once again cast a spotlight on the effectiveness of state and federal safety regulations governing the energy industry. Regulations passed by Congress in 2002 require safety inspections of gas pipelines in densely populated areas by 2012. A new agency, the Pipeline and Hazardous Materials Safety Administration, was set up in 2004 to "protect the American public and the environment by ensuring the safe and secure movement of hazardous materials," according to the agency's mission statement. There are more than 2 million miles of natural-gas pipeline in the United States.

"This is going to be a major event," said Jim Hall, who chaired National Transportation Safety Board during the Clinton administration and made pipeline safety his cause. "All of these underground pipelines are potential bombs."
The overhaul of pipeline safety laws followed a spate of fatal pipeline accidents in the late 1980s and 1990s. The NTSB pushed for new inspection regulations and replacement of aging pipelines, some of which are more than 50 years old.

Hall, who has often given speeches on pipeline safety, told AOL News in an interview that the accident in San Bruno will be the first major test of the new regulations.

"There aren't enough facts yet to draw any conclusions about this event," he said. "But it certainly presents us with an opportunity to closely examine how well the new legislation was working."

Donald Santa, president of the Interstate Natural Gas Association of America, an industry trade group based in Washington, said the programs put in place after 2002 have reduced risk. "Compared to other modes of transportation, pipelines are among the safest," he said.

In California, investigators converged in San Bruno to begin a forensic examination. A four-member team from the NTSB, which will head the probe, arrived at the scene Friday afternoon to begin collecting physical evidence and records from the pipeline's owner, Pacific Gas and Electric Co.

The federal investigators will be joined by state and local officials, including a team from the California Public Utilities Commission, which has state jurisdiction over the pipeline, though federal regulations also apply.

The "how" of the pipeline explosion may prove easier to solve than the "why." The usual culprits in pipeline breaks are construction crews or other workers who run into the pipeline while excavating for some other purpose. In some cases, the damage is not immediately apparent. If a pipeline is merely scraped, as opposed to punctured outright, years could pass before metal fatigue sets in and the pipe finally gives way.

That is what happened in Edison, N.J., in 1994 when a 36-inch gas-transmission line ruptured, causing an explosion that burned eight buildings in an apartment complex and forced the evacuation of 1,500 residents. NTSB metallurgists found a gouge in the pipe that weakened it over time. Eventually, a crack grew in the gouge until it reached "critical size," according to the NTSB report of the accident.
But from there questions can be many, and complicated. Was the pipe properly installed? What kind of soil was it buried in? Had it been dislodged from its bed? When was the neighborhood developed after the pipeline was installed? Had the pipeline been repaired? Were the repairs done properly? What kind of monitoring system tracked the flow of gas? Was a warning system triggered?

The San Bruno accident was so devastating because it involved a large transmission line, which exploded in an area where the pipeline was buried just 3 feet deep. Transmission pipelines deliver natural gas to utilities, large industrial customers and municipalities for further distribution to homes and businesses, according to the pipeline administration's website.

Investigators will want to know when the pipeline was last inspected. In California, state inspectors carry out the checks under an agreement with the federal Transportation Department.

It is unclear the travel route of the pipeline involved in Thursday's explosion, or where the gas was to be delivered. Nicole Liebelt, a PG&E spokeswoman, told AOL News that that information would not be immediately available.
In its investigation, the NTSB investigators will also examine a previous explosion involving a PG&E gas pipeline in 2008 in Rancho Cordova, Calif., that killed a homeowner, injured five people and damaged several homes. That explosion was caused by gas leaking from an unmarked and improperly sized pipe in the house that had allowed gas to leak from a mechanical coupling installed two years earlier, the safety board concluded.

Although the two incidents are vastly different, they may have one thing in common: a customer complaint called into PG&E beforehand. The way the company responded will surely draw investigators' attention.

In the 2008 incident, the company dispatched a technician five minutes after the homeowner called in to report he'd smelled gas. But the technician could not resolve the problem. After a series of delays, a leak inspector finally arrived two hours and 47 minutes after PG&E received the initial report. The safety board concluded that the long delay contributed to the cause of the accident.
In San Bruno, residents said neighbors had reported to PG&E that they smelled gas in the area. PG&E President Chris Johns said the company has not confirmed that it received any complaints. But he added that the company has no record of its crews working in the area at the time of the explosion.

Around 6:15 p.m., residents reported hearing a sound so deafening some thought at first a plane had crashed. The fireball sent flames soaring more than 60 feet into the air. In addition to the four people who died, 24 others were injured, five of them critically.

The fire was so fierce firefighters were still trying to contain the blaze Friday morning