Daylighting

Technique

Definition

Daylighting is the practice of exposing underground utilities or structures to visible light by carefully excavating the soil above them. The term refers to literally bringing buried infrastructure "into the daylight" for visual inspection and verification.

Daylighting is often used interchangeably with potholing, though daylighting more broadly refers to any method of exposing buried utilities to the surface. Hydrovac daylighting is the preferred approach because it uses pressurized water and vacuum suction rather than mechanical digging, dramatically reducing the risk of utility damage.

The process is critical during the design and pre-construction phases of infrastructure projects. Engineers and surveyors use daylighting to confirm that utility records and locate marks are accurate before finalizing construction plans. This verification prevents costly redesigns and change orders that result from encountering unexpected subsurface conditions.

Daylighting is required by many municipalities and state DOTs before any mechanized excavation takes place near known utility corridors. The exposed utility is measured, photographed, and logged with GPS coordinates, creating a permanent record of the as-found conditions.