Planning to plant a tree or put up a fence? Listen up: It's crucial to know the location of any underground utility lines before you get down to the business of digging. Otherwise, you run the risk of shoveling right into a buried pipe, television hookup, or in the worst-case scenario, a power line. Such accidents occur more often than you might think. In fact, the Common Ground Alliance estimates U.S. homeowners hit in-ground utility lines as often as every three minutes. Before you break ground, protect yourself—call 811. The free government service coordinates with relevant local utilities to visit your home and mark out any line locations. That way, you know precisely where not to dig.