Underground Utilities

Issues

Striking buried utilities can cause electrocution, asphyxiation, gas fires, or explosions. Even severing fiber-optic, telecom, or water lines carries significant liability risk if due diligence is not followed.

In 2024, there were 196,977 reports of damage to buried power, water, fiber, natural gas, and other utility lines in the U.S. and Canada. Utility work accounts for a large share of these incidents, with water/sewer and telecom/cable work consistently ranking among the top contributors. Unlike overhead systems, these utilities are hidden, which demands precise planning, coordination, and execution to prevent damage, ensure safety, and maintain service reliability.

Underground utility strikes are both hazardous and costly. Nearly all such incidents incur significant expenses, and those involving gas or electric lines can pose severe risks to everyone nearby. The Common Ground Alliance (CGA) reports that over the past 20 years, utility strikes have caused $1.7 billion in property damage, 1,906 injuries, and 421 fatalities.

Examples: Sewer • Oil • Gas • Water • Electric • Communications • Steam

Issue Hazards

Electrocution from hitting buried power or telecom lines.
Explosions or fires from gas or oil line strikes.
Asphyxiation from toxic gases (e.g., sewer gas) in confined spaces.
Flooding from severed water or sewer lines.
Service outages affecting communities and operations.
Equipment damage and costly repairs.

Sources of Hazards

Failure to request utility locates (31% of incidents).
Insufficient excavation practices (23%).
Inaccurate utility markings (17%).
Failure to maintain clearance (11%).
Outdated or incorrect facility records/maps (9%).
Working from outdated prints or assuming markings still apply after changes.
Using mechanical equipment in hand-dig zones.
Digging before utilities are marked and verified.

Example Incidents: The Facts

In December 2025, a contractor was injured after a utility strike led to a series of three explosions at a road construction site in Quincy, Massachusetts. The incident occurred during sewer and water work, with a suspected underground electrical line strike causing the accident.

Regulations

OSHA Standard Subpart P 1926.651(b)(1)
The estimated location of utility installations, such as sewer, telephone, fuel, electric, water lines, or any other underground installations that reasonably may be expected to be encountered during excavation work, shall be determined prior to opening an excavation.

OSHA Standard Subpart P 1926.651(b)(2)
Utility companies or owners shall be contacted within established or customary local response times, advised of the proposed work, and asked to establish the location of the underground utility installations prior to the start of actual excavation. When utility companies or owners cannot respond to a request to locate underground utility installations within 24 hours (unless a longer period is required by state or local law), or cannot establish the exact location of these installations, the employer may proceed, provided the employer does so with caution and provided detection equipment or other acceptable means to locate utility installations are used.

OSHA Standard Subpart P 1926.651(b)(3)
When excavation operations approach the estimated location of underground installations, the exact location of the installations shall be determined by safe and acceptable means.

OSHA Standard Subpart P 1926.651(b)(3)
While the excavation is open, underground installations shall be protected, supported, or removed as necessary to safeguard employees.

What You Need to Know

Call 811 if in a public area.
Call the property owner if the excavation area is on private land.
Have all lines properly marked two to three days prior to digging, even at home.
Never proceed on a hunch or assumed locations.
Do not dig with machinery or pointed tools within the “tolerance zone” around marked utilities. The “tolerance zone” is a minimum of the facility plus 18 inches on either side of the outside edge of the underground facility on a horizontal plane.
Use soft digging techniques, such as hand digging with blunt-edged tools or vacuum excavation.
Dig test holes periodically to assure the tolerance zone.
When working in a facility or on private property that has many lines installed by a private company, the lines most likely will not be part of the 811 system.
Use ground-penetrating radar, private locators, as-built drawings, and individuals with experience at the facility to locate potential lines before excavating.
Document a proactive, well-thought-out excavation approach prior to digging.
Pre-establish procedures to be in place when issues arise during excavation or a utility line is damaged.
The top three damage root causes are: (45%) insufficient excavation practices, (31%) proper notification not made, and (18%) insufficient locating practices.

Important Do’s Before and When Digging

Do contact 811 or your local One-Call center at least 2–3 working days before digging.
Do review and verify utility maps, flags, and paint marks with the crew.
Do conduct a site walk-through to identify hazards.
Do use ground-penetrating radar or other locating technology for complex sites.
Do mark excavation limits clearly for operators.
Do hand dig within the tolerance zone (typically 18–24 inches on either side of marked lines).
Do use vacuum excavation or other non-destructive methods when appropriate.
Do continuously verify utility locations as work progresses.

Important Don’ts Before and When Digging

Don’t assume the depth or exact location of utilities.
Don’t ignore OSHA 29 CFR 1926.651 for excavation safety.
Don’t ignore state One-Call laws and damage prevention regulations.
Don’t assume utility maps are accurate.
Don’t use heavy equipment too close to marked lines.
Don’t use damaged equipment. Immediately remove from service any platform sections, ropes, or hoists showing signs of structural damage, chemical corrosion, or wear and tear.
Don’t rush or dig too deep without verification.
Don’t bypass permits.
Don’t ignore emergency procedures.
Don’t work without proper training or certification.
Don’t use sharp or aggressive tools near lines.

Job Types include:	Services
After-Hours Response	Carpentry
Preventative Maintenance	General Repair and Maintenance
Office Fitouts	Due Diligence Surveys
ADA Upgrades	Interior Protection During Roof Replacement
Medical/Healthcare Facilities	Building Conditions Study
Multifamily Housing	Property Management
Senior Living Facilities	Preventative Building Maintenance
Educational Facilities	Installations
	Service Repairs