Could San Bruno happen here?

Last Thursday,  with more possible victims still being identified. Many of the San Bruno residents never even knew Pacific Gas & Electric had a 30-inch-diameter natural gas transmission line running under their homes until this devastating accident.

Do we have similar lines running through Mill Valley? Could an explosion and fire happen here? Unfortunately, very little information is publicly available.

According to maps from the National Pipeline Mapping System, gas transmission lines run down Highway 101 in Marin, coming in off the freeway to run through downtown San Rafael. They do not go through Mill Valley.

The National Pipeline Mapping System was taken off-line following Sept. 11, 2001, but made available again in 2006. PG&E, however, will neither confirm nor deny the location of gas lines, because of safety and security concerns.

"Many of them were there before communities," said PG&E spokesperson Katie Romans. "It's not unusual for homes to be built in an area after a pipeline was installed."

PG&E has 51 miles of gas transmission lines in Marin, Romans said. The largest of those pipes is only 20 inches in diameter, compared to larger pipes in San Bruno, she said.

However, there is concern that PG&E has increased the pressure within existing lines to accommodate increased demand instead of outting in new gas lines.

"To get gas where it needs to go, you can either add a new line or crank up the pressure. What companies have been doing nationwide is cranking up the pressure, buying new pumps to provide that additional pressure and off we go," said Bob Rackleff, board president of the Pipeline Safety Trust.

Exact information about the age and pressurization of pipes in Marin isn't currently available, said Romans.

PG&E also referenced a list of the highest-risk 100 segments of its pipe in its filings to the California Public Utility Commission last year. However, the commission says it does not have the full list and PG&E has said it will not be releasing the full list.

Although a similar natural gas explosion isn't likely in Mill Valley, the likelihood of a large fire or disaster remains high, local fire officials said. With its hilly terrain of canyon homes connected by a network of thin, winding roads on the steep slopes of Mount Tamalpais, Mill Valley and its surrounding unincorporated neighborhoods are ripe for the same type of devastating wildland fire that destroyed 3,000 homes and killed 25 people in the 1991 Oakland hills blaze, according to Katherine Randolph, who teaches a regular fire safety class in Mill Valley.

Residents should be prepared for emergencies with basic emergency skills, an evacuation plan for their home, and a meet-up point for their family in a disaster situation. Residents should also have basic supplies – such as water, some food, and basic aid -- for a situation in which emergency responders aren't able to respond immediately. And residents are advised to know where and how to turn off their gas should there be a leak. Even if you don't live near the large transmission gas lines, virtually every house has smaller distribution gas lines. If you smell gas, you should leave the premises and call the police and report it to PG&E.

Emergency Preparedness classes are offered frequently in Mill Valley - check out the latest schedule here.