Digging into unknown ground is one of the few activities that can shut a project down in seconds. A service strike brings real harm to people and serious disruption to programme and reputation. The cure is rarely clever kit; it’s disciplined planning, staged verification and permits that mean something on the ground. A permit-to-dig is not a form to file. It is a live control that sequences information gathering, detection, proving, supervised breaking of ground and change control.
TL;DR
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– Treat permits-to-dig as a live process, not paperwork; stop-start controls must match site reality.
– Prove before you dig: search, scan, mark, and trial-hole until you know what is there.
– Keep competence on the end of the shovel: trained locator, named supervisor, and a clear stop-work trigger.
– Lock in change control: any shift of line, level, method or plant means the permit is re-checked and re-briefed.
A staged permit-to-dig playbook for UK groundworks
# Stage 1: Build the picture before chalk hits the ground
/> Start with utility searches from all likely asset owners, including private networks where applicable. Align those results with design intent, traffic management, and temporary works needs so the dig method is compatible with support and access. Challenge unclear, old or conflicting plans early; do not timetable the excavator until your information is usable. Record what’s still unknown and plan how you’ll close those gaps before authorising breaking ground.
# Stage 2: Detect and mark up with the people who will dig
/> On arrival, your trained locator carries out a full scan using suitable detection equipment, following a methodical grid. Walk the line with the supervisor, plant operator and banksman, and mark out services clearly on the ground with colours and notes everyone understands. Photograph and annotate the mark-up, and keep it legible as works progress; re-mark as needed after rain, traffic or spoil movement. If a service can’t be traced or its route is ambiguous, treat that zone as suspect and escalate before any excavation.
# Stage 3: Prove it with trial holes and vacuum excavation
/> “Prove before you dig” means confirming line, depth and type by controlled hand-digging or vacuum excavation where suitable. Cut neat trial holes at key crossing points and changes in direction and record what you find with measurements and photos. Do not rely on depth assumptions; nearby level changes, previous works or unrecorded alterations can shift services. If what you expose differs from your plans or mark-up, stop, update the permit and brief the team again.
# Stage 4: Dig under supervision with defined exclusion and support
/> When you move beyond proving, keep the excavation controlled: the supervisor stays present, the banksman focuses on the bucket, and only one item of plant enters the workface unless planned otherwise. Maintain physical barriers or spotters to keep pedestrians and other trades out of the dig zone, and keep spoil heaps back to protect markings and edges. Where trenches need support or crossings, integrate temporary works requirements into your method and permit conditions. Choice of plant and attachments must reflect proximity to services; smaller buckets, guarded teeth and reduced slew racks can be the difference between near-miss and strike.
# Stage 5: Manage change and handovers like a live system
/> Permits lapse if the scope, line, level, plant, personnel or weather changes beyond agreed tolerances. Build clear stop-start rules into the permit: unexpected service, failed scan, poor visibility, or loss of supervision equals tools down. Shift briefings and handovers must include the latest mark-ups, photos and any hold points. Close out permits with as-built notes that will help future phases and reduce the chance of repeat ground-breaks in the same location.
Scenario: civils crew, new service corridor, pressure rising
/> A civils gang on a distribution park is installing a drainage run between two live units. Utility plans show medium-pressure gas and fibre in the verge, but the programme has slipped and the client wants the road open by Monday. Morning scan and mark-up find the gas, but the fibre trace is patchy near a gate. The supervisor pauses machine excavation and brings in vacuum excavation for a trial hole at the crossing. They expose a second unrecorded telecoms duct sitting shallower than expected, right on the original trench line. The permit is amended, the line shifts 600 mm, and the TWC confirms the new trench support still works. The change chews up a few hours, but the strike that didn’t happen saves days.
Permit-to-dig quick checks on the ground
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– Up-to-date utility search results are on hand and understood by the digging team.
– A competent locator has scanned, marked, photographed and briefed the service routes.
– Trial holes at crossings and suspected changes of direction are completed and recorded.
– Supervisor presence is defined; if they leave, the dig stops until cover is in place.
– Exclusion zones, barriers and banksman roles are clear to nearby trades and drivers.
– Method and plant match proximity to services; vacuum excavation considered where beneficial.
– A stop-work trigger and escalation contact are written on the permit and repeated in the briefing.
Common mistakes with service avoidance
# Treating the permit as a green light for the whole area
/> Permits should define a specific footprint and depth range. Broad, open-ended permits invite uncontrolled digging and drift in supervision.
# Scanning once and assuming it still holds
/> Site conditions, kit interference and ground changes can undermine a morning scan. Re-scan when you shift line, enlarge the excavation or start a new shift.
# Hand-digging without a method
/> Hand tools can still damage shallow fibre or plastic gas if used aggressively. Set a controlled approach with small lifts, insulation where appropriate, and clear visibility of the service.
# Letting mark-ups fade under mud and spoil
/> If the paint disappears, so does the shared understanding. Maintain markings, set up boards or stakes, and keep spoil and plant off the evidence you rely on.
Operational momentum
# Over the next week: close the gaps in digging controls
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– Walk your live permits and confirm they still match the works as they are actually being done.
– Arrange a competence refresh for locator users and check calibration and batteries.
– Set a standard for photo records of mark-ups and trial holes and store them accessibly.
– Agree with the TWC how trench support requirements are referenced in permits.
– Test your stop-work and escalation route with a short tabletop exercise at the morning briefing.
Bottom line: prevent strikes with disciplined permits
/> Avoiding service strikes is mostly about sequencing and behaviours. Information, detection, proving, controlled excavation and change control are simple stages, but they only work when the permit-to-dig pins them together and the supervisor owns the stop-start authority. Keep the form short and the controls visible, and make sure the team know exactly what will halt the dig and who can restart it.
Service strikes are drawing sharper attention across UK projects, and clients are asking harder questions about competence and assurance. Three questions for your next briefing: What is still unknown beneath our feet? Who has the authority to stop, and will they use it? How are we proving the ground, not just scanning it?
FAQ
# What’s the difference between a permit-to-dig and the RAMS for the excavation?
/> RAMS set the planned method and risks; the permit-to-dig authorises breaking ground at a specific place and time once preconditions are met. The permit checks live details like scans, mark-ups, trial holes, supervision and exclusion zones. Treat the permit as a gate that only opens when the RAMS controls are proven on site.
# When should vacuum excavation be used instead of hand-digging?
/> Use vacuum excavation when you need to expose services safely with less chance of contact damage, especially in congested or shallow service corridors. It can be faster and cleaner than hand tools in the right soils, but it still needs scanning, mark-up and competent operation. Choose it deliberately in your permit and briefing, not ad hoc at the machine.
# How often should we re-scan during a dig?
/> Re-scan whenever the line or footprint shifts, a new shift starts, plant type changes, or conditions may affect detection, such as heavy rain or adjacent electrical kit. If detection is unreliable or conflicting, escalate and treat the area as suspect until proved with trial holes. Don’t rely on a morning scan for an afternoon dig that has drifted.
# How do permits link with temporary works for trench support?
/> The permit should reference any temporary works requirements that affect how and where you dig, such as support systems, spans and loading limits. Agree with the TWC how hold points are managed, for example waiting for inspection before deepening. If the line or depth changes, re-check that the support design still applies before you restart.
# What’s the right escalation when we hit an uncharted service?
/> Stop works, make the area safe, and keep people and plant away from the service. Notify the supervisor and permit controller immediately and contact the relevant asset owner via agreed numbers. Do not attempt to move, repair or clamp anything; update the permit, RAMS and mark-ups before considering a restart.
