Potholing & Daylighting

What's the difference?

The terms overlap and are often used interchangeably. Potholing usually means digging a small test hole to locate a utility and record its depth, size, and material. Daylighting usually means exposing a utility so it's visible ("in daylight") while work happens nearby, such as at a bore crossing. Both are commonly done by vacuum excavation.

Why locate marks aren't enough

MISS DIG locate marks show the approximate horizontal location of a member's facility, not its depth. That's why Michigan law defines a 48-inch caution zone on either side of the marks and requires soft excavation to expose marked facilities there before power equipment is used. For lines running parallel to the excavation, the law requires exposing them at intervals as necessary.

Where potholing is used

• Horizontal directional drilling (HDD): exposing each crossing utility so the drill path can be confirmed.
• Design / subsurface utility engineering (SUE): collecting verified depth and location data for engineering plans.
• Fiber and broadband builds: crossings along road rights-of-way.
• Road, water main, and sewer projects: conflict checks before construction.

How long it takes

One industry cost guide gives a typical range of 3–5 potholes in 4–8 hours, depending on depth, soil, pavement cutting, and travel between holes. Clay, rock, and frozen ground can slow production by 30–50%.

What affects potholing cost

• Number and depth of holes, and how far apart they are
• Pavement cutting and restoration (asphalt or concrete coring)
• Traffic control requirements
• Soil type and frost
• Disposal of slurry
• Whether survey data (depth, GPS location, photos) must be delivered

See published hydrovac price ranges →

Sources: MISS DIG Underground Facility Damage Prevention and Safety Act, 2013 PA 174 (MCL 460.721–460.733) (MCL 460.723 definitions; MCL 460.725); Hydrovac Hotline, “Hydrovac Cost: 2026 Pricing Guide”.