Service strikes are still a weekly reality on UK projects, from small refurb footings to major civils. A permit to dig is not a form to file; it’s a decision gate that controls who digs, where, with what, and under what limits. Done well, it forces a pause to verify buried services, set exclusion zones, and define stop-work triggers when conditions change. Done badly, it becomes a paper shield for rushed excavations, unclear service markings, and plant creeping into red zones.
TL;DR
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– Treat the permit as a live control with hold points, not a one-off signature.
– Combine up-to-date utility plans, competent detection, and trial holes before any machine breaks ground.
– Mark, photograph and brief the dig envelope; control plant movement with a banksman and barriers.
– Stop and re-validate the permit if ground conditions, layouts or the scope change.
– Record discoveries and hand back a clean, updated map for the next crew.
Staged controls to keep spades and buckets away from live services
# Stage 1: Map it properly before anyone digs
/> Gather all available utility records for the work area and immediate surrounds. Don’t assume a single drawing is complete: collate statutory plans, previous as-builts, and any site logs. Note no-dig corridors like HV cables, gas mains, fibre trunks and site-wide temporary supplies. Plot proposed excavation lines against this picture and define early design changes if routes clash with critical services.
# Stage 2: Verify the ground with competent detection
/> Use a calibrated cable avoidance tool with a signal generator to sweep the dig area and adjacent margins. Where the ground is congested, consider ground penetrating radar or a specialist survey. Mark service lines and uncertainty zones clearly on the ground and on a sketch. Record who scanned, when, and what confidence you have in the markings. If you cannot achieve confidence, escalate and redesign before digging.
# Stage 3: Prove services by trial holes, not guesswork
/> Expose expected services with hand-digging or vacuum excavation to confirm depth, location and orientation. Use insulated tools near suspected cables and manage spoil so it doesn’t load fragile assets. Photograph each exposure, tag it with a reference, and update the site plan. Only proceed with machine digging once you’ve proved the route is clear within the defined tolerance.
# Stage 4: Define the dig envelope and isolate interfaces
/> Set the boundaries of the dig in paint and pin-and-tape barriers; include offset distances from known services. Establish a plant/pedestrian interface plan with a trained banksman, and if necessary fit slew restrictors or use smaller plant. Agree traffic routes and no-go arcs. Clarify temporary works requirements for edge protection and shoring so the excavation remains stable while protecting services that enter or cross the area.
# Stage 5: Control the excavation in real time
/> Brief the team on the permit conditions at the start of each shift: where you can dig, depths, tool choices, and stop-work triggers. Keep the permit displayed at the workface. Maintain separation from services using spotters, and re-scan edges if the excavation extends. If markings are lost, the ground fills with water, or unexpected ducts appear, stop, make it safe, and call the supervisor. PPE is the last line; the main defence is not hitting anything live in the first place.
# Stage 6: Close, record, and reset when things change
/> On completion or at a change in scope, backfill and protect exposed services appropriately, remove temporary barriers, and tidy the area. Update the service map with what you actually found, however mundane. Hand over the record to the site manager so the next package doesn’t repeat the same uncertainty. Expire the permit when the conditions no longer match the work; don’t let expired permits drift into the next task.
Where digs go wrong
# Thinking a utility plan equals clearance
/> Drawings are often incomplete or out of date. Without ground verification, you’re relying on hope rather than a control.
# Scanning once then trusting it all week
/> Markers vanish under rain, spoil and traffic. A quick re-scan and remarking at the start of each shift keeps reality aligned with the plan.
# Letting plant creep into the no-dig zone
/> Under programme pressure, slews widen and buckets track closer “just for one pass”. Barriers, banksmen and slew limits exist to stop that drift.
# Relying on PPE and luck near live services
/> Insulated gloves and boots won’t save an operator from a serious cable strike. The only reliable control is avoiding contact altogether.
Scenario: unmarked services on a housing spine road
/> A groundworks gang is cutting new drainage along a plot-to-plot spine road on a housing site. The permit shows a low-voltage cable and a water main offset to the footpath; plans are six months old. The supervisor scans the route and picks up a second signal that doesn’t fit the drawing. Under pressure to open the trench before a concrete pour, the excavator starts, working “carefully”. The bucket exposes a shallow telecom duct, unmarked and brittle, and clips it. Broadband to 40 occupied homes drops, the client gets calls, and the road closure overruns into the school run. The crew has to stop, hand dig, and wait for the utility to attend, losing two days and goodwill.
Checklist
# Before the next bucket goes in
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– Collate current service plans for the exact dig strip and 3–5 metres either side; carry paper and digital copies to the workface.
– Walk the line with a competent operator using a CAT and Genny; mark, photograph and date-stamp all finds and no-dig areas.
– Prove critical crossings with hand or vacuum trial holes; record depths and orientations before machine work.
– Nominate a single supervisor and a banksman; set barriers, slew limits, plant routes and pedestrian exclusion zones.
– Brief the crew on the permit boundaries, tool choices, edge protection and stop-work triggers; display the permit at the dig.
– Keep spoil, materials and plant off known service corridors; maintain clear access for emergency isolation if required.
– If anything doesn’t match the plan, stop, make safe, and re-issue the permit after fresh scanning and updated markings.
Bottom line
/> The permit-to-dig system works when it turns uncertainty into defined boundaries, with competent verification and the authority to stop. Most strikes are not freak events; they are the end of a chain of small compromises that a good permit process is designed to prevent.
Expect closer scrutiny from clients and utility owners on how you prove clearance, not just how you fill in forms. Three questions for your next briefing: What did we verify today? Where are our hold points? Who can halt the dig when reality shifts?
FAQ
# When do I actually need a permit for digging?
/> Use a permit for any ground penetration that could contact buried services, from fence posts to deep excavations. Even soft landscaping can hide shallow comms or private feeds; the permit scales the controls to the risk. If in doubt, treat it as permit-required and justify any simplifications in writing.
# How often should we re-scan and re-mark the area?
/> Re-scan at the start of each shift, after breaks in work, and whenever the dig extends or markings are lost. Weather, spoil and traffic quickly erase lines, and nearby services can run unpredictably across your route. Regular revalidation keeps the crew aligned to the ground truth.
# What if the plans are missing, old or contradictory?
/> Escalate early and build your controls around verification rather than drawings. Bring in competent detection, open trial holes at likely crossings, and consider redesigning routes or using vacuum excavation. Do not let programme pressure convert uncertainty into risk taken by the operator.
# Who signs off the permit and who controls the dig?
/> A competent supervisor with authority over the work should issue and own the permit. The excavator operator and banksman enforce the conditions on the ground, but the supervisor sets hold points, briefs the team, and stops work if conditions change. Keep the permit at the workface so everyone knows the limits.
# What should we do if we uncover an unknown service mid-dig?
/> Stop, secure the area and prevent further disturbance; do not probe blindly. Inform the site manager, mark and photograph the find, and contact the likely asset owner for identification and advice. Hold the dig under the permit until you’ve verified what it is and updated the controls.
