If 811 marked the public lines but nobody marked the water service to your building, the electric feed to a parking lot light, or the sewer lateral behind your store, you need a private utility locator. 811 sends out the utility companies, and each utility marks only the lines it owns, usually up to the meter or the property line. Everything on your side of the meter belongs to the property owner, and no one marks it unless you hire someone to.
When you call 811 (PA 811 in Pennsylvania, Miss Utility in Delaware, Maryland and DC, NJ One Call in New Jersey), the call center notifies the member utilities with lines in your dig area. Each member sends a locator to mark its own facilities. Those utilities aren't responsible for lines they don't own, so the service lines, branch lines and site utilities past the meter are left unmarked.
Call a private utility locating company. A private locator comes to the site, sweeps the area with electromagnetic (EM) locators and ground penetrating radar (GPR), and marks what it finds with paint and flags in the standard APWA colors. Good firms also tell you what they couldn't find and why, and can map the lines for your drawings.
Metallic lines and lines with tracer wire are found most reliably with EM equipment. Plastic water and gas lines, clay sewer and abandoned lines rely more on GPR, sewer cameras with sondes, or rodding. GPR depth varies with the soil, and wet clay limits it. When a line has to be confirmed before digging near it, the next step is vacuum excavation to expose it. Read more about what GPR and EM can miss.
Trinity Subsurface marks private utilities for contractors, facility owners and engineers across the Mid-Atlantic, with a field sketch within 24 hours. Schedule a crew or call (302) 407-3697.
