3.25 Identification of Unknown Lines

One Call Center

Practice Statement:15

The one call center has a defined and documented policy for handling calls from excavators regarding the discovery of an unidentified line.

Practice Description:

To facilitate damage prevention, one call centers have an established procedure that is implemented when an excavator calls and reports an unidentified facility. The action taken could be as simple as renotifying all affected facility operators in the absence of any other specific requirement of state or local law.


  • Many one call centers process a “Dig Up” request when an unidentified line has been exposed (Texas). Others simply reissue the locate request with an appropriate remark (Maryland, Delaware). Some state laws mandate that additional specific action be taken by the facility operators upon receipt of these types of notices (Arizona, which currently requires an “unknown line policy” to be in effect via the Arizona Blue Stake One Call Center). The law requires that the one call center “establish a method of providing personnel from a facility owner qualified to safely inspect and verify that the facility is abandoned or active and a method for reimbursing the verifying facility owner for the cost incurred.”


One Call Center One Call Center

Facility Owner Facility Owner

Excavator Excavator

Locator Locator

Project Owner Project Owner

Designer Designer