: If EM is ineffective (e.g., for non-conductive plastic pipes), locators may use Ground Penetrating Radar (GPR) or Acoustic Locating .

: 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:

: This is the most common method. It involves a transmitter that sends a frequency down a conductive line and a receiver that detects the signal above ground.

In the context of construction and excavation, a is the process of identifying and marking the positions of underground utility lines—such as gas, electric, water, and telecommunications—to prevent damage during digging.