I wouldn't go as far to say that it was due to negligence. I have to agree with Reno if you truly want to maintain peace with the customer. The problem is that the insurance deductible would probably cost as much as your repair efforts would have cost anyway. Not to mention that you don't want to have any claims against your insurance policy these days.
I'd sure question the location of that pipe, but I guess there aren't any rules that specifically say that a sewer pipe can't be there. Do you have any idea what caused the collapse of the pipe further down the line?
I say a few prayers every time I drive a ground rod too. It sure would be nice if a mandatory "safe zone" could be established for new buildings, similar to working clearance requirements for equipment. We are fairly lucky in these parts as all public utilities, to include sewer are marked by "Miss Utility", which helps to a certain extent. I'm sure that in your case, the building was under construction so who would have thought?
