Keyholing

Keyholing involves cutting a small circular opening, typically 12 to 18 inches in diameter, through the pavement surface and then excavating down to the utility using hydrovac or vacuum excavation methods. Specialized long-handled tools are used to perform valve operations, service connections, or repairs through the small opening.

The primary advantage of keyholing is dramatically reduced surface restoration costs. A traditional utility repair might require cutting and removing a large section of pavement, excavating with a backhoe, completing the repair, backfilling, and then repaving. Keyholing reduces the pavement cut to a small circle that can be patched quickly and at a fraction of the cost.

Keyholing is most commonly used by water and gas utilities for valve exercising, service line connections, and minor repairs. The technique has been shown to reduce total project costs by 30 to 50 percent compared to conventional open-cut methods while also reducing traffic disruption and public inconvenience.