Trial Hole and Hand Dig Procedures
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Trial Hole and Hand Dig Procedures
Trial holes are small hand-dug excavations used to visually confirm the exact position, depth, and type of buried services detected by CAT and Genny surveys. Hand digging near buried services is essential because mechanical excavation can easily damage cables and pipes. The use of hand tools such as spades, shovels, and insulated digging tools reduces the risk of striking services. Trial holes must be dug at every service crossing point and at regular intervals along detected routes.
- Dig trial holes at every point where services are detected or where service plans indicate crossings.
- Use insulated hand tools when digging within 500mm of known or suspected electrical cables.
- Dig carefully and progressively, exposing services by removing soil from alongside rather than above.
- Support trial hole sides if the excavation exceeds 1.2 metres depth or ground conditions are poor.
- Mark exposed services with the correct colour marker spray and record their position accurately.
- Do not use picks, forks, or powered tools within 500mm of any known or suspected service.
- Backfill trial holes safely when complete and reinstate the surface to prevent trip hazards.
- Record trial hole findings on the service location drawing and communicate results to the excavation team.
- Obtain a permit to dig before starting any trial hole excavation on site.
If a cable is exposed and appears damaged, stop work immediately and move everyone back. Do not touch the cable. Call the electricity network operator and your supervisor. If a gas pipe is damaged, evacuate upwind and call 0800 111 999.
- Trial holes confirm what the CAT and Genny detected and reveal services that scanning may have missed.
- Hand dig within 500mm of any known service using insulated tools and careful progressive excavation.
- Never use mechanical excavation tools, picks, or forks near buried services.
- Expose services from the side rather than digging directly down on top of them.
- Record every trial hole result and mark exposed service positions clearly on the ground.
- A permit to dig must be in place before any trial hole excavation begins on site.
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