A permit-to-dig is the control that stops buried services turning a routine excavation into a life-changing incident. Done properly, it ties together utility searches, locating and proving services, method selection, supervision, and stop-work triggers. Done poorly, it becomes a form-filling exercise that nobody trusts, and the risks creep back in as the ground opens up and the programme squeezes.
TL;DR
/>
– Agree and mark the dig zone, then locate and prove every service before any plant breaks ground.
– Set method limits in the permit: who digs, with what kit, how close to marked services, and when to stop.
– Keep the permit live: daily briefings, re-marking, and fresh scans when the plan or ground changes.
– Tie in isolation, temporary works, traffic routes and emergency arrangements; don’t let anyone work outside the controls.
Controls playbook for avoiding buried service strikes
/>
Define the dig zone and information baseline
Start by white-lining the exact area and depth of the excavation, including plant access, spoil heaps and any temporary works footprint. Bring together utility plans from statutory undertakers, client records and recent as-builts, and clarify what’s indicative versus verified. Mark a control drawing with the intended dig area, nearby services, safe plant routes and no-go zones. If works are phased, split the permit so each phase has a clear boundary and time window. Agree the competence of the permit requestor, issuer and holder, and set a realistic validity period that suits the ground and programme.
# Locate, scan and prove before you dig
/> Use competent operatives with calibrated cable avoidance tools and, where needed, ground-penetrating radar to sweep the whole zone plus a sensible buffer. Record who scanned, when, with what equipment, and how the area was marked. Don’t rely on a sweep alone: prove positions with hand-dug trial holes or vacuum excavation to expose services. Tag and protect what you find; adjust the control drawing and permit conditions if services are closer than expected. Where isolations are agreed with asset owners, capture the consents and lock-out method in the permit pack.
# Control the method and equipment
/> Select a digging method to match the findings, not the original plan. That may mean hand-digging around markings and within an agreed distance of services, with insulated tools and constant supervision. If plant is used, specify buckets, maximum depth per pass, approach angles and a spotter’s role. Keep spoil placement, shoring and access in mind; don’t bury valve covers or draw static plant over suspected routes. Make the permit explicit on what cannot happen: no teeth-on-bucket near known services, no ripping, no augers through marked corridors.
# Manage interfaces and keep people out of harm’s way
/> Set up physical barriers and clear signage to keep non-essential people and trades away from the dig. Coordinate traffic management so deliveries and site plant don’t track across marked service runs. Brief all involved—groundworkers, plant ops, supervisors, visiting utilities—on the markings, method and stop signals. If hot works, piling, dewatering or other nearby activities could affect services, make those interfaces part of the permit conditions. Keep communications simple: radio channel, banksman hand signals, and a clear instruction to stop on any uncertainty.
# Keep the permit live as the ground changes
/> Treat the permit as dynamic. Re-brief and re-validate at the start of each shift, after weather events, or when the dig extends. Re-mark lines that get scuffed by wheels or rain. Scan again if the footprint moves, the depth increases, or unexpected materials are found. Build in escalation triggers: unknown ducting, a smell of gas, unexpected cables, or water ingress should halt works until the issuer attends. If the validity window runs out, stop, close, and reissue—don’t pencil-whip an extension.
# Record, protect and hand back clean
/> Photograph exposed services, annotate the control drawing, and secure temporary protection like trench boards or barriered standoffs. Where possible, agree as-built updates with the client or asset owner, so future phases aren’t guessing. Before closing the permit, make sure reinstatement doesn’t bury temporary markers or leave edges unguarded. Sign off only when the area is safe, barriers are right, and the records are filed.
Site scenario: drainage run meets buried surprises
/> A civils gang on a housing site is chasing a drainage connection before the weekend. The permit-to-dig was issued mid-week, based on utility plans and a CAT sweep, and white lines mark the trench route across a new access road. On Friday morning, the plant op starts peeling tarmac with a toothed bucket while the supervisor is pulled away to the gate for a delivery clash. The banksman notices the white lines are half-missing after rain and asks for a re-mark, but the op edges forward to “just square off the edge.” The bucket scrapes something orange—then the breaker trips on the substation across the road. It turns out an LV service to the show home was laid along a slightly different path than shown. No-one is hurt, but the outage, investigation and repairs cost the programme two days. On Monday, the team reissues the permit, bans toothed buckets near marked routes and switches to vacuum excavation for proving.
Supervisor walk-round checklist for permits to dig
/>
– Walk the white-lined zone end to end and confirm markings are clear, continuous and recent.
– Ask to see the scan records, instrument checks and the names of those who scanned and proved.
– Verify trial holes and exposed services match the drawings and are physically protected.
– Confirm isolation or consent paperwork is on file where agreed with asset owners.
– Inspect plant set-up: bucket type, approach route, banksman positioning and exclusion barriers.
– Look for programme pressures or nearby works that could distract or interfere with the dig.
– Agree the stop-work triggers and make sure everyone can state them back in simple terms.
Common mistakes
/>
Relying on old drawings as if they’re gospel
Utility plans are often indicative. Without scanning and proving, you’re guessing—and guesses get exposed as soon as the bucket bites.
# Letting permits lapse quietly
/> A permit that’s out of date or not re-briefed is a permit that no-one believes. Once trust goes, method drift follows.
# Treating the CAT sweep as a one-off
/> Ground changes, markings fade and footprints creep. Scanning and remarking must follow the work, not the paperwork.
# Ignoring the edges and the spoil
/> Strikes often happen at the margins—plant turning, tipping spoil, or tracking over a suspected route. Control the approaches, not just the trench.
Keeping momentum without drift
/>
First week actions on a live dig
Confirm the permit boundary with fresh white-lining after any rain or traffic. Walk the plant routes with the op and banksman and agree where to stop and how to approach live markings. Brief every shift start with the permit holder present, and change the method if the ground or findings demand it. Stage vacuum excavation or hand-digging for proving ahead of the machine, so no-one is waiting with a running engine. Escalate any unknown ducts, unmarked cables or whiff of gas immediately and treat them as show-stoppers until verified.
Bottom line
/> Permits to dig are more than a signature—they are a daily control that adapts to findings on the ground. Keep them live, keep them specific, and keep them enforced. Expect increased scrutiny around service strikes where programmes are tight and subbies are overlapping. Three questions for your next coordination meeting: Who owns the permit today, what changed since yesterday, and where are we most likely to drift outside the method?
FAQ
/>
When do I need a permit to dig?
Use a permit for any intrusive ground activity where buried services could be present, including trial holes, posts, drainage, fencing and sign bases. Even shallow works can hit services, so the trigger should be the presence of utilities risk rather than depth alone. On long runs or phased works, split permits into manageable sections so controls stay live.
# How long should a permit remain valid?
/> Set a validity window that matches the site pace and the likelihood of change—often days rather than weeks. Re-brief and re-validate at each shift start or when the footprint moves, markings fade, or weather affects visibility and stability. If the method, plant or people change, close and reissue rather than extending casually.
# Who should carry out the scanning and proving?
/> Competent operatives trained in the specific equipment should do the scanning, with instruments checked and logged. Proving should be by hand-digging or vacuum excavation under supervision, with exposed services identified, tagged and protected. Supervisors should not accept unverified plans as proof; they should see the ground opened and compare to the control drawing.
# What’s the right response if we uncover an unknown service?
/> Stop work, make the area safe and inform the permit issuer and site management. Keep people and plant clear, protect the exposure and seek identification from the asset owner if possible. Do not probe live services with metal tools or assume it’s redundant just because it looks old.
# How do we coordinate permits with other site activities?
/> Fold temporary works, traffic routes, deliveries and neighbouring tasks into the permit conditions and brief all affected parties. Set barriers and signage that keep non-essential trades out, and schedule deliveries to avoid plant crossing suspected routes. If another activity affects the dig area, pause and re-brief before restarting.
