: If EM is ineffective (e.g., for non-conductive plastic pipes), locators may use Ground Penetrating Radar (GPR) or Acoustic Locating .
: Active locating uses a transmitter to follow a specific route, while passive locating detects existing fields from live power lines. 3. Documentation and Marking locating
: Before the locator arrives, the excavator should "white line" or pre-mark the planned work area with white paint or flags. This helps locators focus on the exact site, speeding up the process. : If EM is ineffective (e
: You must contact your local 811 center (the "call before you dig" service). In many states, locators are required to arrive on-site within 48 hours of the request. 2. The Locating Process Locators use specialized equipment to find buried lines: : If EM is ineffective (e.g.