Marc,
I consider my house well sealed, and when the line ruptured 2 blocks away, it only took a few minutes, for my house to reach explosive levels, We still have a lot of contractors driving rods, and digging trenches, without mark-outs, they use every excuse, from it's just a ground rod, to it's only a 18" trench, or i know where all the utilities come in, they most likely thought, that the pipe was deeper, or in another location at the job site of todays explosion.
