Underground Utilities
Underground Utility Safety & Call-Before-You-Dig
Utility locating, 811 practices, and the OSHA requirements that make locating a legal obligation, not just a good idea.
811 / Call-Before-You-Dig
Calling 811 (or a local one-call utility locate service) before digging is a nationwide practice that notifies utility owners to mark buried lines before excavation begins. It's required in every state, typically several business days before work starts. It is a separate obligation from OSHA's excavation safety requirements around soil classification, protective systems, and daily inspections - both are required; one doesn't substitute for the other.
Utility Types & Their Hazards
Electric
Contact or arc-flash risk from energized lines; requires de-energization or safe clearance distances before digging nearby.
Gas
Strike risk creates fire/explosion hazard and can release hazardous atmospheres into the excavation.
Water
Strikes can flood the excavation rapidly, destabilizing soil and creating engulfment/drowning risk.
Sewer
Strikes create hazardous atmosphere exposure (H2S, methane) and contamination risk.
Telecom
Lower direct injury risk but strikes cause costly outages and site disruption.
Fuel Lines
Fire/explosion risk similar to gas; requires the same locate-and-clear-distance discipline.
Employer Coordination Duties
Employers are responsible for coordinating utility locate requests with the timeline of the actual dig, confirming markings are current before work begins, using safe excavation practices (hand digging or vacuum excavation) within utility tolerance zones, and re-verifying locates if work is delayed past the marking's validity window.
OSHA 1926.651(b) Requirements
OSHA 1926.651(b) requires employers to determine the estimated location of utility installations before opening an excavation, contact utility companies or owners to establish exact locations, and (when excavation approaches the estimated location) determine the exact location by safe means, such as hand digging, while the excavation is open.
Stop-Work Authority
Any worker who strikes, exposes, or suspects an undocumented utility line should stop work immediately and notify the Competent Person, regardless of role or seniority. Continuing to dig near a suspected strike - especially gas, electric, or fuel lines - is one of the most dangerous decisions on an excavation site.
This topic is covered at the awareness level in Excavation, Trenching & Shoring Safety Training and at the program-oversight level in Competent Person Training.