I'm inclined to agree. You mean to say there is no phone or power that is U/G there also? Also, what is the problem? peds in a fenced in yard is nothing new. Tell him to call for locates and put the fence up. If he bought the property with the peds already in place, having been granted permission from the previous/original owner, then I doubt he can legally do anything about it as it would be in essence 'grandfathered' in this late in the game.
You really have all the time in the world. Make him take you to court over it. If he wilfully cuts the lines, lines that are now considered to be 'utility' lines, that is at least a state offense, and if memory serves is actually a federal offense. And of course, since he is well aware of the lines and their location, any damage would now be considered wilfull.
Get a lawyer and set precident in this case. Tax deductable as a business expense.
