An underground service locator investigates a work area so a crew has better information about what is beneath it before excavation, trenching, boring or drilling starts. On a VACIT job that means working through the records and plans that already exist, tracing services on site with electromagnetic equipment, and bringing in ground penetrating radar where the records and the tracing leave gaps. What the results need to show is confirmed with you when the job is scoped.
Each method has limits. Electromagnetic locating needs a service that will carry a signal. Radar depends on the ground, the equipment and what is being looked for. Records vary between asset owners. Where an asset is critical, careful excavation can expose it so it can be seen at that point. That confirms the asset exposed, not everything else in the ground, and it sits alongside your site's safe work controls rather than replacing them.