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Safety Measures for Working around Underground Utilities

By Robert Pieters, Contributor

Dealing with underground utilities demands extra precautions, vigilance, and communication.

Each year, approximately 700,000 underground utility lines are struck during excavation work. This poses a dangerous risk to worker safety and often results in costly repairs that significantly impact project budgets.[1]

This is why it’s crucial to identify these potential hazards when starting new construction or remodeling an existing facility. Contractors must be prepared with comprehensive safety plans for working around underground utilities from trench safety to working in tight spaces. Dealing with underground utilities demands extra precautions, vigilance, and communication.

Here are four important ways that construction teams, especially excavators responsible for digging and demolition, can stay safe when managing utilities.

Take Time to Preplan & Prescan

Before the shovel hits the ground, it’s crucial for the team to plan for known and unknown utility hazards that may be present. Gas and electrical lines can often be identified in blueprints, but occasionally when a blueprint has not been updated, a hazard like underground power lines may not be identified.

When working at a private property, contractors should immediately contact a private locating company to help identify lines. For public projects, the 811 “Call Before You Dig” resource is a toll-free nationwide number and should always be called at least three working days before starting any type of digging project. Ensure that you are aware of upcoming projects and digging locations well before a project commences. Construction crews also need to immediately report any incidents or service outages due to a utility strike.

Construction teams can also use technologies like ground-penetrating radar scans (GPRS) to scan through concrete slabs above and beyond regular utility locators. Using the latest technologies to scan flooring is always best practice prior to beginning site removal.

Ensuring that owners and teams are communicating regularly during planning plays a key role in preventing potential issues with utility lines. In addition to weekly safety awareness talks where designs are reviewed and challenges are discussed, hosting regular training sessions can significantly reduce near-misses or incidents.

Pre-planning can help you avoid costly mistakes before they occur. One utility strike can mean expensive repairs and insurance will not typically cover that loss. The utility can also charge fines when it cannot service its customers.[2]

Each year, approximately 700,000 underground utility lines are struck during excavation work.

Above and Below Ground Mapping

As part of planning, take extra steps to go beyond the blueprints and scans with a comprehensive mapping of your location. Walk around the construction site to look for manholes or access points that might indicate underground lines utility markers.

To create an accurate underground map of the utility lines that may be on the property, a method called potholing or daylighting is an option. Potholing can be conducted either by hydro-excavation or air excavation which uses pressurized water or air streams to break through soil or clay. This creates deep test holds that will reveal the elevation and position of subsurface utility lines on the site.[3]

Check excavation permits and make sure everything is identified before work starts.

Understand Your Tolerance Zone

When you plan your excavation area, mark it clearly using white paint or flags to identify digging locations.  As you do this, it’s essential to define your tolerance zone – the horizontal distance that extends from the outer edge of an underground line or pipe. This zone varies state by state, ranging from 18 to 30 inches on either side of the line or pipe.

Locating underground utilities is an inexact science as many are not laying underground lines in nice straight lines. The tolerance zone warns construction workers to proceed with caution and use best practices when working in the area. These include:

  • Dig wisely: Use excavation techniques such as hand digging, soft digging or potholing; loosen dirt with a blunted shovel using a gentle prying vs. stabbing motion.[4]
  • Treat every line like it’s live: Don’t assume every line is properly marked and color-coded.
  • Never dig up to the tolerance zone: Even when the line is exposed, dig with caution and stay outside those borders.
  • Reassess and relocate: If something unidentifiable is located or a utility is spotted where it shouldn’t be, stop work immediately.

Develop an Emergency Action Plan

Did you know that 7% of utility line strikes are from inaccurately marked lines?[5] Despite preventative measures, mistakes can happen. Because clear thinking doesn’t always occur during stressful situations, it’s beneficial to prepare an emergency action plan (EAP) to ensure proper steps are taken if an underground utility strike results in a crisis.  An EAP should include:

  • Process for reporting an emergency including emergency contact numbers and a hierarchy of calls
  • Procedures for evacuation including marked exit routes for the location
  • Protocol on what to do if a line is damaged
  • Guidelines to be followed by employees who may perform rescue or medical duties on-site
  • Rally points and how to account for employees

The Occupational Safety and Health Administration (OSHA) provides additional EAP resources that can help you craft an effective EAP for your job site.[6]

Teams who invest time to pre-plan, communicate effectively, and prepare for potential emergencies will ultimately build a safer environment for workers, preventing injuries and costly errors.

Robert Pieters is a Safety Manager, Riley Construction (







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