Potholes that Enhance Utility Damage Prevention

Hand digging test holes is accomplished with blunt tip shovels (sometimes referred to as shooters), picks and digging bars which are carefully used to find and uncover utility lines. Although the hand digging method of potholing has been used successfully for a long time, it has its limitations. The cutting edge of these tools can also damage utility lines. It does not take much force to damage a fiber-optic, telephone or electric cable, a cathodic protection on gas lines or to nick and weaken plastic water lines. Care should also be taken when electrical lines are present. In addition, potholes can only be dug about 4 ft deep before they have to be opened up enough to accommodate a worker and digging holes. More than 5 ft deep creates the need for a cave-in protective system (sloping, shoring or shielding).

Vacuum excavation, although not always feasible, is becoming the most popular and efficient method for locating utilities. Trailer- and truck-mounted vacuum excavators use air or water pressure to quickly dig small, precisely controlled potholes to uncover utilities. Both air and water excavation methods have advantages and disadvantages, which should be considered before purchasing a vacuum excavation system.
An important consideration is that vacuum excavators can dig deeper than is possible with a shovel. Controlled by an experienced operator, they can also uncover buried utilities without the risk of damage to them.

Some state jurisdictions and local communities frown on or even prohibit potholing when it means cutting through the surface of paved streets. If this is the case, it may be necessary to explain to officials the importance of potholing and what you’re trying to prevent.

After the work is complete, the potholes must be filled and compacted to ensure that patches do not sink with time. The pothole should be clean and dry before backfilling and the pavement or surface must be replaced in accordance with local standards and specifications. Make sure you know the local restrictions and requirements before potholing.

Even with potholing, utilities will not always be found where the locator placed the marks. When this happens, mismarks and unmarked utilities should be reported to the facility owner and/or the One-Call/Dig Safe center. NUCA encourages contractors to also file a DIRT (Damage Information Reporting Tool) report with the Common Ground Alliance at www.cga-dirt.com. Reporting mismarks helps the utility owner update its maps and identify locators who may need additional training. It also helps the industry address the issue of contractors being blamed for damages that are caused by mismarks and unmarked utilities.

Safety is always a consideration. Contractors must ensure that vacuum crews know and follow the necessary safety precautions. In many situations, crews will be working outside the barricaded work zone where they could be exposed to traffic. They should be instructed on how to set up a temporary work zone and provided with the cones, barricades and/or signs needed to safely redirect traffic around the potholing operation. All workers should be provided with high visibility vests or clothing to be worn at all times. In addition, safety glasses — and sometimes hearing protection — must be used. Hand digging requires non-conductive or insulated tools. Companies need to provide dielectric boots and gloves and require their employees to wear them to reduce the possibility of being shocked if an electric line is damaged.

Start your jobs off right by following this simple 10-step procedure to prevent damage to underground utilities:
Plan the job.

White-line or mark the area to be located. Meet the locator at the jobsite, if necessary.

Call the One-Call/Dig Safe center to request a mark-out and wait the required time before proceeding.

Verify that all utilities have been marked and notify the One-Call/Dig Safe center if all utilities are not marked.
Pothole to find utility lines and determine the exact location and depth.

Report mismarked facilities, inaccurate marks and unmarked utilities to the One-Call/Dig Safe center.

Respect the tolerance zone.

Support and protect exposed utilities from damage.

Report damages immediately to the facility operator and investigate the cause of any damages.

Backfill carefully and fill in potholes properly in accordance with standards and specifications.

Utility hits are dangerous and costly. They can only be prevented when companies commit to damage prevention. Contractors have a responsibility to their companies, employees and the general public to do all they can to prevent damage to underground utilities. That prevention comes from knowing exactly where utilities are located, and the best way to accomplish that is to both call before you dig and pothole before digging. Make a difference: Establish a damage prevention procedure, include potholing and dig responsibly.
The Mid-America Regional Council (MARC) has prepared a useful Potholing Practice which includes additional information that can be downloaded from its website (www.marc.org/gif/potholing.pdf). Additional information is also available from the manufacturers of vacuum excavation equipment.

George Kennedy is NUCA Vice President of Safety.