Utah law requires utility owners to mark only the lines that they own and maintain. This usually means up to the meter. Underground lines that extend beyond the meter or that are not connected to a meter are typically not installed or owned by a utility company and therefore may not be marked. These include water and sewer laterals, power to a detached garage or lamppost, sprinkler/irrigation systems, lines connected to a propane tank or septic system, etc.
Almost every job site will include some type of privately-owned underground pipe or cable. The excavator should inspect the property carefully and ask the property owner about private underground lines before digging. The excavator should consider hiring a private locator to mark private lines that could be in conflict with the excavation project. Areas where private lines are especially common include apartment complexes, mobile home parks, gated subdivisions, cabin communities, schools and universities, hospital complexes, industrial areas, government facilities and military installations. Find additional info under FAQ #6: https://www.bluestakes.org/faqs/