Service strikes are one of the fastest ways to turn routine groundworks into an emergency. Power, gas, fibre and water are rarely where the old drawing says they are, and services laid by others since the last build can be shallow, unmarked or undocumented. A permit to dig is the control that brings the whole picture together: locating, planning, authorising and supervising the excavation so that breaking ground is deliberate, not guesswork.
TL;DR
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– Never dig on plans alone; scan, mark out and trial-hole to prove what’s there.
– Treat the permit to dig as a live control with hold points and expiry, not just paperwork.
– Hand-dig within tolerance bands around marked services; bring in vac ex where risk is high.
– Supervision is active: stop on unknowns, manage change, and keep plant/pedestrian separation tight.
– Close out properly with as-built updates so the next team isn’t starting blind.
The controls playbook for breaking ground without breaking services
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Stage 1: Build the underground picture before a bucket moves
Gather current utility plans from statutory undertakers and the client’s records. If the risk profile is anything above minor, arrange utility detection using competent surveyors with appropriate techniques; expect gaps and treat results as indicative until proven. Walk the site looking for visible clues: marker posts, inspection covers, meter boxes, recent reinstatements, and third-party plant routes. Bring the temporary works coordinator into the conversation early where support to excavations will be needed.
# Stage 2: Plan the dig method to the ground conditions and services layout
/> Write a method that reflects what the survey suggests: excavation type, plant size, access, spoil management, water control, and temporary works. Define exclusion zones for plant, and a pedestrian route that avoids swing radii and bucket arcs. Where services are expected, set tolerance bands and specify hand-digging, soft digging or vacuum excavation. Pre-plan hold points: for example, stop after topsoil strip to re-scan, stop before crossing the gas corridor, and stop if ground deviates from assumptions.
# Stage 3: Permit to dig issue with mark-up and briefing
/> The permit must describe the exact area, depth, date window, attached drawings, survey outputs, and control measures. CAT and Genny scanning should be completed and recorded, with the results physically marked on the ground using a clear colour code and arrows for direction. The supervisor briefs the gang and plant operators at the workface, showing the marks on the ground, the hold points and the no-go zones. The permit is displayed at the workface or available digitally, and it expires if the scope shifts, the area extends, or the date window lapses.
# Stage 4: Break ground under supervision and prove, don’t assume
/> Start with a controlled trial hole to verify the first service location and depth. Hand-dig within the tolerance band until the service is exposed and supported; do not use mechanical means in the red zone. Keep the bucket away from marked lines; use spotters who understand the plan, not just “an extra pair of eyes”. Maintain plant/pedestrian segregation throughout, and stop works immediately on any unknown, damaged or suspect service.
# Stage 5: Manage change, weather and competing pressures
/> If the programme wobbles or a delivery squeezes space, don’t improvise a new trench line without re-checking and re-authorising; that’s a permit reset. Rain can collapse sides and shift markers; re-scan and re-brief after significant weather. If trial holes disprove the survey, pause and re-map before pushing on. Record any deviations on the permit and escalate when the risk moves outside the original RAMS.
# Stage 6: Make safe, document and close out
/> Backfill with care around live services using suitable materials and hand compaction close to the asset. Reinstate markers, photos and as-builts so future teams know what’s been found and where. Close the permit with supervisor sign-off, attach records and brief the next shift if the dig is phased. Treat any near-miss or scrape as a learning event, not an embarrassment to bury.
Site scenario: civils team chasing foul drainage near a live retail unit
/> A groundworks subcontractor is tying a new foul line into an existing manhole beside a trading retail unit. The stat plans show electric and comms in the footway, but nothing in the service strip by the car park. Programme pressure is high because the store wants the area open by Friday. The supervisor gets the permit, scans and marks electric in the footway as expected; a faint signal appears across the planned trench but is dismissed as “legacy”. Trial holes are skipped to save half a day. The excavator clips a shallow fibre duct installed during a previous shop refit, unseen on plans. The store loses payment terminals for hours and the job shuts while the network provider takes over.
Permit-to-dig issue checklist
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– Confirm utility plans are the latest available and attached; note known gaps.
– Complete and record CAT/Genny scans; mark up services and suspected routes on the ground.
– Define hold points and tolerance bands; specify hand-dig or vac ex zones.
– Brief the exact dig limits, access, exclusion zones and emergency stop procedures at the workface.
– Verify temporary works needs: edge protection, shoring, and safe access into the excavation.
– Set permit validity dates and triggers for re-authorisation (scope change, weather impact, survey conflict).
– Ensure contact details for utility owners and emergency response are visible to the team.
Common mistakes around permits to dig
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Treating the permit as a form, not a control
Tick-box permits with no workface briefing lead to blind digging. If the crew can’t point to the marks and explain the hold points, the permit isn’t live.
# Digging on plans without proving
/> Stat plans are a starting point, not the truth. Without scanning and trial holes, you’re gambling with buried assets.
# Moving the line to “get it done”
/> Shifting the trench to avoid congestion or speed up spoil movements without a re-check is a common strike pathway. Change control is non-negotiable.
# Poor supervision at the bucket
/> Spotters on their phone or not understanding the mark-up add no value. Active, informed supervision is the protection layer when assumptions fail.
Follow-through and supervision
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Over the next 7 shifts: groundworks focus points
– Map the week’s digs and pre-book scanning so no crew is waiting on a last-minute sweep.
– Walk each dig line with the operator and ganger, re-mark faded paint and re-confirm hold points every morning.
– Swap in vacuum excavation for the highest-risk crossings rather than squeezing hand-dig times.
– Stand up an escalation rule: unknowns or conflicting signals mean down tools and call the supervisor, no debate.
– Capture photos of every exposed service with tape measure and orientation arrows, then log them to the permit pack.
Bottom line
/> Permits to dig only work when they pull planning, scanning, briefings and supervision into one disciplined flow. When time pressure bites, the permit is the stop that prevents a service strike from becoming your new critical path.
FAQ
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What should be attached to a permit to dig?
Include current utility plans, survey outputs, photos of mark-up, and the specific method for the task. Add a simple sketch showing the dig limits, exclusion zones and known services. Make sure contact numbers for utility owners and site emergency leads are on it. If the work spans shifts, note the handover arrangements.
# How close to a marked service should plant be allowed?
/> Good practice is to define a tolerance band around each marked service where hand-digging or soft digging is required. The exact distance depends on confidence in the survey, ground conditions and asset criticality. The key is to brief the band at the workface and enforce it consistently. If in doubt, widen the band and slow down.
# When do we need vacuum excavation?
/> Use vac ex where the likelihood or consequence of a strike is high: congested corridors, shallow services, or unreliable records. It’s also useful for exposing multiple utilities quickly for verification. Build it into the method early rather than booking it as an emergency after a near-miss. Supervision still matters; vac ex is not a guarantee against damage.
# What’s the right response if we damage a buried service?
/> Stop all works, make the area safe and keep people away. Do not attempt a repair; contact the utility owner using the numbers on the permit and follow their instructions. Isolate plant if there’s a risk of ignition and consider evacuating nearby areas depending on the service involved. Record the incident, preserve evidence and review controls before any restart.
# How often should we re-scan and re-brief on longer digs?
/> Re-scan at planned hold points, after significant weather, and whenever the trench line or depth changes. Faded markings, new deliveries or rearranged storage can also mask hazards, so treat the daily start-up as an opportunity to refresh the mark-up. If the permit expires or the scope shifts, pause and re-authorise. Regular, short briefings near the bucket are more effective than a single long induction.
