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Glossary

Potholing

What is Potholing?

Potholing is digging a small, precise test hole to expose and verify the location and depth of an underground utility, commonly performed with hydro excavation to avoid damaging the line.

Potholing (also called test-holing) creates a compact excavation over a suspected utility so the line can be visually confirmed before larger construction begins. Hydro excavation is the preferred method because pressurized water and vacuum remove soil without the risk of cutting or cracking the pipe or cable.

Potholes are used to check depth of cover, confirm horizontal position, and identify unknown or abandoned lines ahead of directional drilling, trenching, or grading. A hydrovac truck or hydrovac trailer with a dig tube and wand is the typical tool. Renters can request potholing-capable vacuum excavation equipment on Vac4Rent for free and hear back directly from rental companies.

Renting equipment for this job? Rent Hydrovac Equipment for Potholing

Guides that cover Potholing

Related terms

DaylightingHydro ExcavationUtility LocatingDig Tube / Wand

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Potholing: common questions

What is Potholing?+

Potholing is digging a small, precise test hole to expose and verify the location and depth of an underground utility, commonly performed with hydro excavation to avoid damaging the line.

How is potholing used before horizontal directional drilling?+

Before a directional bore, crews typically pothole each existing utility that the planned bore path crosses, so the drill operator knows the actual depth and position of those lines. The exposed crossing lets the bore be steered with safe clearance and lets the crew watch the drill head pass the line. Project specifications, utility owners, or state rules may require potholing at crossings, so check the job requirements before boring.

Where should potholes be placed on a utility project?+

Potholes usually go wherever the planned work crosses a marked or suspected utility, where a line changes direction, and at intervals along utilities that run parallel to the work. Crews also pothole where locate marks conflict with records or where a line's depth is unknown. The number and spacing of potholes is normally set by the project specification, the design engineer, or the utility owner, so confirm those requirements before scheduling equipment.

How are potholes backfilled and restored after the utility is verified?+

After the line's depth and position are recorded, the hole is backfilled, compacted, and the surface is restored to match the surrounding pavement, turf, or gravel. Backfill material and compaction requirements usually come from the utility owner, the right-of-way permit, or the project specification. Keyhole potholes cut through pavement often need an approved patch or core reinstatement. Confirm restoration rules with the permitting agency before digging.