Underground Utility Locating Excavation Safety

• Striking underground electric, gas, water, sewer, or communication lines
• Inaccurate or missing utility markings
• Assuming marks show exact utility location or depth
• Excavating inside tolerance zones without proper care
• Poor communication between crews, operators, and utility owners
• Continuing excavation when utilities cannot be verified

Underground utility locating is a critical step before excavation. Striking a buried utility can cause electrocution, fire, explosion, flooding, service interruption, environmental release, or serious injury.

Utility markings should be reviewed before digging begins. Crews need to understand what each color means, where marked utilities are located, and whether the planned excavation crosses or runs near those utilities.

Marks are not a guarantee of exact location or depth. Utilities may be offset, deeper, shallower, abandoned, unmarked, or installed differently than expected. Workers should treat marks as a warning, not as permission to dig aggressively.

Tolerance zones require extra care. Hand digging, vacuum excavation, potholing, or other approved methods may be needed to expose and verify utilities before mechanical excavation continues.

Operators and workers on foot should communicate clearly when working near marked utilities. The operator may not be able to see all markings from the cab, especially once spoil, equipment, traffic, or water covers the area.

Site conditions can make locating harder. Pavement, old repairs, multiple utilities, poor records, private lines, service laterals, and previous construction can all increase uncertainty.

If markings are missing, unclear, damaged, or inconsistent with field conditions, work should stop until the issue is resolved. Guessing can lead to a utility strike.

Safe excavation starts with knowing what is underground. Locating, verifying, and communicating utility hazards protects workers, the public, and critical infrastructure.

• Review utility markings before excavation.
• Do not assume markings show exact depth or location.
• Use approved methods inside tolerance zones.
• Expose and verify utilities before digging near them.
• Keep operators informed of underground utility hazards.
• Protect markings from being covered or destroyed.
• Stop work if utilities are unclear or unexpected.

• Have utilities been located and marked before digging?
• Does the excavation cross any marked utilities?
• Are tolerance zones understood by the crew and operator?
• Has the utility been exposed and verified where needed?
• What is the plan if an unmarked or unexpected utility is found?