I'm pretty sure if you call your utilities they'll come out and mark all your lines so you know where they are. They put little colored flags in the ground. I ran into a pipe when I was putting in a raised bed last year. Turns out it was an old drainage pipe that wasn't in use anymore. It was cast iron so I just broke it with a hammer & got rid of it. It beat having to find another spot for the bed when I'd already dug most of it already!
