An excavation permit is usually required if an excavation takes place within the boundaries of a municipality or within a specific area designated by the local government. It is also usually required for any excavation that involves removing soil or rock from the surface of the ground, or for any excavation that disrupts the surface of the ground. Additionally, an excavation permit may be required for any excavation that involves a structure, such as a retaining wall, or if the excavation will interfere with any public utility lines.