Potholing (Daylighting): Definition for Fiber Construction
Potholing (daylighting): digging test holes to physically expose underground utilities before fiber trenching or HDD boring, preventing utility strikes.
Potholing, also called daylighting, is the practice of digging small excavations by hand or vacuum excavation to physically expose an existing underground utility so its exact depth, location, and condition can be confirmed before fiber construction crews trench, bore, or drill nearby. It turns approximate locate marks into verified field data.
Why Potholing Matters Before Fiber Construction Begins
One-call locate marks show the approximate horizontal position of a buried utility, not its exact depth or condition. That gap is where strikes happen. Potholing closes it by physically exposing the line so crews know precisely where it sits before a bore path is drilled or a trench is cut nearby. On fiber projects, potholing is standard practice at every crossing of gas, electric, water, sewer, or existing telecom conduit. It converts a painted estimate into verified field data, which engineers then use to set safe bore depths and clearances. Skipping it is one of the most common and most expensive mistakes in underground construction, since a single utility strike can halt a project, trigger emergency repairs, and create real safety hazards for the crew and the public.
How Potholing Is Performed
Most fiber contractors pothole using vacuum excavation, either air vac or hydro vac, which removes soil with pressurized air or water and a vacuum hose instead of a shovel or blade. Vacuum excavation is the preferred method near sensitive utilities because it exposes the line without the cutting risk of mechanical digging. Hand digging is still used on smaller or shallow holes. Once the utility is exposed, the crew records its exact depth, horizontal position, and often GPS coordinates, then compares that data against the original locate marks and the design bore profile. If the utility sits somewhere other than expected, the engineering team adjusts the plan before construction proceeds, rather than finding out mid-bore.
Potholing vs. Utility Locating
Locating and potholing are two different steps in the same damage prevention process, and they are not interchangeable. A one-call locate is a non-invasive service that marks the approximate path of buried utilities using paint, flags, or stakes, based on utility owner records and ground-penetrating tools. It is required by law before excavation but it is an estimate. Potholing is the physical verification step that follows: digging down to the actual utility to confirm exact depth and position at specific points along a route, especially at planned crossings. Responsible fiber contractors treat locate marks as a starting point and pothole at every crossing before drilling or trenching through it.
Potholing (Daylighting), answered
What is Potholing (Daylighting)?
Potholing, also called daylighting, is the practice of digging small excavations by hand or vacuum excavation to physically expose an existing underground utility so its exact depth, location, and condition can be confirmed before fiber construction crews trench, bore, or drill nearby. It turns approximate locate marks into verified field data.
Is potholing the same as daylighting?
Yes. Potholing and daylighting are the same practice under two names, both common in the utility and telecom construction industry. Either term refers to digging a small exploratory hole to physically expose a buried line rather than relying on painted locate marks alone.
When does a fiber project require potholing?
Potholing is standard before horizontal directional drilling bore paths, hand or machine trenching near marked utilities, and any crossing of gas, electric, water, or other fiber lines. Engineers use the exposed depth and location to finalize the bore profile and avoid a strike.
Who performs the potholing, the locate company or the contractor?
One-call locate services mark approximate utility positions with paint and flags but do not dig. Potholing is physical excavation, typically done by the construction crew or a vacuum excavation subcontractor, to confirm what the locate marks only estimate.