Relax man, unless someone does something very stupid, its as safe as can be. The accident in walnut creek 4 years ago happened because someone was using a backhoe near the pipeline while welding was going on in a 40" sewer line. The backhoe driver was new, they did not have a inspector from the pipeline company on site, and he was using a rough hole digger not a smooth side digger.

You would be surprised just how much it takes to damage a pipeline. I am willing to bet when this gets investigated, someone hit the PG&E line and didn't report it.