One of the National Transportation Safety Board officials admitted he didn't know whether there were pipelines under his house. The fire chief of San Bruno said he didn't know there was a major transmission pipeline under his city. Do you know what's under your house?
Here's a link to a pipeline mapping website where you can identify some of the pipes in your neck of the woods. It's not perfect - you can only get about half a mile of detail. But give it a try: