Digging Near Buried Facilities
The flags and paint marks used to mark buried utilities show the approximate location of the actual facility. Utilities have a tolerance zone that runs 24-inches from the utility's outside edges.
Before using mechanized digging equipment in a tolerance zone, you must make sure that someone observes the dig to help the person on the equipment if something doesn't look right. Of course, the best thing to do is find the utility before digging either with hand-dug test holes or vacuum excavation.