5.19 Excavation Tolerance Zone


Practice Statement:

The excavator observes a tolerance zone that is comprised of the width of the facility plus 18 in. on either side of the outside edge of the underground facility on a horizontal plane. This practice is not intended to preempt any existing state/provincial requirements that currently specify a tolerance zone of more than 18 in.

Practice Description:

(See Practice Statement 5–20.)


  • Existing state laws, including New Mexico, Pennsylvania, South Dakota, and others
  • Telecommunications Industry Association and Electronic Industry Association (TIA/EIA), “Standard for Physical Location and Protection of Below-Ground Fiber Optic Cable Plant” (ANSI/TIA/EIA-590-A-1996)
  • American Public Works Association (APWA), “Guidelines for Uniform Temporary Marking of Underground Facilities”


One Call Center One Call Center

Facility Owner Facility Owner

Excavator Excavator

Locator Locator

Project Owner Project Owner

Designer Designer