The thing is, these mistakes (drills going through things) are more common than people think. It’s a hollow-stem augur bit, not really a very big one either–I’ve worked with those myself. And the utility clearance folks we get to work with…..Let’s just say I’m not a huge fan of witching sticks. The maps are little better. I’ve skimmed the edges of sewers (sanitary and storm water), shaved the casing off a power cable, and a bunch of other stuff. My wife once sank a drill by hitting a water line, flooding the area and turning it into quicksand. And none of this ranks as a particularly exciting day drilling.

Also, part of the problem is that the geologist on the ground has four people above him screaming to get six holes done a day, and the drillers get paid by the foot in most cases. So you frequently have about ten minutes to clear a site. Not exactly ideal.