Service strikes are not “bad luck”; they’re predictable when groundwork starts without a disciplined permit to dig process. Hitting buried electric, gas, fibre or water costs time, reputation and sometimes lives. The permit is the control that links planning, detection, supervision and change management. Used properly, it slows the job just enough to keep people and infrastructure safe, while allowing the programme to move with confidence.
TL;DR
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– Treat the permit to dig as a live control: define scope, mark the ground, brief the team, and set hold points.
– Combine records, survey, and proof excavation; do not rely on any single source of truth.
– Keep line marking visible and current; re-scan and re-brief whenever the dig shifts or deepens.
– Supervise the first bucket, enforce hand-dig zones, and manage plant/pedestrian separation.
– Close out with as-builts and updates so the next phase starts informed, not blind.
Making the permit to dig work on the ground
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Stage 1: Fix the scope and freeze the zone
Be precise about where, how deep and how wide the excavation will be, and for how long the permit covers it. Define the work area with barriers and signage, including plant routes and exclusion zones. If the dig footprint changes, the permit should pause and be reissued. This stops the “one permit for half the site” mindset and keeps control tight.
# Stage 2: Records search and surface reconnaissance
/> Collect utility plans early and validate them with a walkover. Look for inspection covers, street furniture, meter boxes, cabinets, repairs patches, historic trenches and obvious service corridors. Mark suspected routes on a working drawing and note uncertainty. Brief the team that records are indicative, not exact.
# Stage 3: Locate, don’t just detect
/> Use appropriate survey methods such as cable avoidance tools and ground-penetrating radar where beneficial, with a competent operator. Transfer findings to a clear site mark-up with colours and notes: known, likely, and unknown routes. Show depth estimates as ranges, not absolutes. Photograph mark-ups and add them to the permit pack.
# Stage 4: Prove by hand and protect what you find
/> Cut trial holes by hand or vacuum excavation to confirm the presence, depth and alignment of utilities before plant digs. Maintain safe distances around verified services; install temporary protection or matting where plant must pass. Any discrepancies between survey and reality trigger a stop and re-brief. Record exposed services with photos and update the sketch.
# Stage 5: Control the live dig
/> Set hold points for the first bucket in each area and for step changes in depth. The supervisor should be present, with the permit and mark-ups in hand. Enforce plant/pedestrian separation and ban metal tools over suspected live electric routes. Keep line marking fresh and visible as spoil, rain and trafficking can erase it quickly.
# Stage 6: Close out and update the picture
/> On completion or at the end of each shift, close the permit, remove redundant markings, and return barriers to a safe state. Update the site service plan with anything found or proven absent. Share lessons at the next morning brief so the next gang or subcontractor doesn’t repeat the learning curve.
A real site scenario: road crossing on a housing scheme
/> A civils gang is tasked to trench across a narrow estate road to install a drainage connection before handover. The programme is tight, and deliveries for plot fit-out are queuing. The permit to dig identifies probable low-voltage and telecoms routes from records and a recent survey; the supervisor sets a hold point for the first metre and bans toothed buckets near the footpath edge. Hand-dug trial holes expose a shallow telecom duct that was 300 mm offset from the plan and running diagonally. The route is protected with boards, and the trench is adjusted to avoid it. The supervisor keeps plant away from the exposed duct with barriers, and the dig proceeds in sections to maintain access. Backfill includes a warning mesh, and the updated route is added to the as-built for the client.
Permit to dig — supervisor walk-round prompts
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– Confirm the dig footprint matches the permit drawing and the ground markings are visible and current.
– Check survey evidence is in the pack, with competence of the person who scanned recorded.
– Verify hold points are stated (first bucket, depth changes, approaching marked routes) and that the team understands them.
– Ensure hand-dig zones and tool choices are clear, with insulated tools available and used where specified.
– Inspect barriers and routes to keep pedestrians and plant apart, including a spotter if required.
– Look for changes since scanning (new street furniture, spoil covering marks, re-routing of temporary services) and decide if a re-scan is needed.
– Confirm how findings will be recorded: photos, sketches, and who updates the shared service plan.
Common mistakes that cause strikes
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Treating the permit as a tick-box
Issuing it once then filing it away. A permit only works if it is read on the ground, referenced during the dig, and paused when things change.
# Over-trusting drawings
/> Assuming utility plans give exact positions or depths. They don’t; they are a starting clue, not a guarantee.
# Skipping proof excavation
/> Jumping straight to plant because the CAT beeped “clear” in a small sample. Trial holes save time by removing surprises.
# Failing to control interfaces
/> Allowing deliveries or other trades to push through the dig zone. Interaction pressure is when shortcuts happen and marks get erased.
Keeping the momentum through the programme
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Over the next 7 days: tighten service controls at transitions
Align the permit dates with the programme so permits expire before a phase shift, forcing a fresh look. Ring-fence time in daily briefings for service updates, including what was found yesterday. Bring in vacuum excavation for congested areas instead of wrestling with hand-dig delays. Stage your crossing works so access is maintained without running plant over suspected corridors. Record every exposed service with photos against fixed references so the next crew isn’t guessing.
Bottom line
/> A permit to dig is simply a structured pause that replaces assumptions with evidence. If supervisors insist on locate–prove–control before plant turns a track, service strikes become rare, not routine.
FAQ
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When do I actually need a permit to dig?
Use a permit whenever there’s a risk of hitting buried services or destabilising nearby structures. That includes trenching, posts, kerbs, trial pits, and even shallow landscaping where services might be present. If you’re unsure, treat it as needed and scale the controls to the risk.
# How often should I re-scan or refresh line marking?
/> Re-scan when the dig shifts laterally, goes deeper, or after anything that could alter readings, like heavy rainfall or new temporary services. Refresh markings at least daily in busy areas, and immediately if spoil, traffic or weather has obscured them. If you can’t see it clearly, you can’t safely rely on it.
# Who signs the permit, and who holds it on site?
/> A competent person should prepare and authorise the permit, typically the principal contractor’s supervisor or H&S lead for that area. The working copy should be with the supervisor controlling the dig, available at the point of work for reference. Everyone in the gang should have been briefed on its content before starting.
# What if records are missing or contradictory?
/> Treat uncertainty as a higher risk and increase controls: wider hand-dig zones, more extensive survey, and staged excavation with tighter hold points. Speak to the client and utility owners early to fill gaps, but do not wait passively if the programme is moving. Your permit should document the uncertainty and the additional precautions in place.
# What happens if we find an unrecorded service mid-dig?
/> Stop, make the area safe, and protect the service from damage or movement. Update the permit, re-brief the team, and adjust the method—this may mean changing the route, switching to vacuum excavation, or putting in temporary protection. Record the find with photos and communicate it to the wider site so others don’t repeat the near miss.
