There's more than vicarious horror and interest in the San Bruno disaster here in San Diego. Our local utility, SDG&E, has 850-000 natural gas customers and more than a few are wondering, could the same thing happen here?
“In every community with natural gas service, there's a big transmission line that acts like an artery, and small distribution lines to homes and businesses that act like capillaries,” said SDG&E spokesman Art Larson.
SDG&E says it's extremely proactive in diagnosing and treating potential problems.
"We are subject to significant and rigorous federal and state regulations concerning the safety of these pipelines. Also, we've got a rigorous procedure in place to patrol these pipelines on a regular basis," Larson said.
SDG&E has about 250 miles of transmission pipelines, which range upwards from a foot to 3 feet in diameter and are monitored around the clock. 8,300 miles of distribution pipelines are going to natural gas customers.
We've been seeing messages from residents on social media sites, wondering how close they live to a transmission line. The company won't disclose the layout of that grid, on grounds of "national and local security."
It's not clear to what extent details of PG&E's grid may come to light through investigations and court action.
Meantime, an attorney who's handled natural gas disaster litigation has this observation about the line that ruptured in San Bruno.
"It's rumored to be as old as 50 years old and they're steel lines. They can be under significant pressure, and through corrosion, they can fail," said Robert Buccola.
SDG&E does install signs marking the nearby presence -- but not exact locations -- of major transmission lines where they would cross under streets, highways or rails.
Officials say so-called "third party" contractors, digging without prior clearance, are the most common cause of pipeline ruptures.
