Dear Doves,

The issue with a gas explosion in San Francisco is one I thought to comment on.  I work in this field, though in NY state.  Anyway, I've never heard of a gas main as big as 30".  The largest in my area is 14", although I'm not in a big city.  Most of the high pressure transmission mains are running through the woods and not near houses.   Some, however, do pass close to houses in a few spots.  But this is relatively rare and there should be markings from the gas co. so people know about these mains.   The gas you receive is from distribution mains in front of your houses or across the street.   Leaks on these mains happen, but they don't have anywhere the kind of pressure the transmission mains have.  It sounds like they should have detected the reported leak, shut the main down and fixed it before it blew up.  Anyway, don't let this worry you.

Joe M