Service strikes are still among the most predictable – and preventable – incidents on UK sites. A permit to dig only works when it ties design intent, utility information, ground verification and day-to-day supervision into one live control. That means accurate plans, competent scanning, clear mark-up, defined hand-dig zones, and a supervisor who can stop work when the picture changes. The paperwork is the receipt; the real control is what people do with spades, locators and excavators at the edge of a trench.
TL;DR
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– Stop assuming records are right; verify on the ground, mark it up and brief it.
– Make the permit a shift-by-shift control with hold points and stop-work triggers.
– Use the right tools: competent locator use, hand-dig or vacuum where needed, and keep plant back until proven clear.
– Supervise the dig, protect exposed services, and update the permit the moment anything changes.
The controls playbook for avoiding service strikes
# Stage 1: Plan the dig before any bucket moves
/> Start with what you can control on paper: the route, depth, plant choice and whether you can avoid breaking ground at all. Pull in up‑to‑date utility records early and insist on clarity around previous works and temporary supplies. Build in temporary works needs (support, edge protection, crossings) so the method doesn’t drift mid‑shift. Agree who owns the permit, who supervises the excavation, and who can call a halt. If the programme is tight, protect time for scanning and trial holes rather than trying to claw it back later.
# Stage 2: Locate and verify buried services properly
/> Combine drawings, a competent cable/pipe locator survey and local knowledge from the client or building manager. Use the locator with the correct modes and frequencies, and prove it on a known service before relying on it. Where the ground is crowded or depths are uncertain, bring in more capable detection methods rather than guessing. Mark findings cleanly on the ground – paint, flags, stakes or tagging – and translate that to a simple sketch for the team. Treat depths on records as unreliable; assume shallow until proved otherwise.
# Stage 3: Mark, brief and issue the permit with clear hold points
/> The permit should attach the latest plans, a photo of the mark‑up, and a simple drawing showing hand‑dig zones and no‑go areas. State what can and cannot be used (e.g. no mechanical digging within the agreed proximity to a suspected service). Set hold points at crossings and interfaces, with the named supervisor present before proceeding. Make validity time‑bound – typically a shift – and cancel it if weather, access, plant, or information changes. Brief every person putting a tool in the ground; signatures aren’t the control, understanding is.
# Stage 4: Trial holes and expose by safe methods
/> Trial holes prove the location and depth of services before the main excavation. Hand digging means controlled, shallow, and with the right insulated tools – not ramming down with a spade. Vacuum excavation is a good option in congested areas or where power is suspected. Once a service is exposed, support it, leave it visible, and protect it from plant and spoil. Photograph, tag, and update the permit sketch so the next shift isn’t guessing.
# Stage 5: Supervise the dig and keep controls live
/> A competent supervisor should be at the point of work during critical stages and reachable at all times. Keep plant and people separated with barriers and banksmen; manage spoil so it doesn’t bury markers or load trench edges. If the ground conditions vary from expectation or new services appear, stop, reassess the mark‑up, and re‑brief. Keep lighting adequate and the work area tidy so markings and exposed services stay visible. Record as‑built information progressively – don’t wait until backfill to try and remember where everything went.
# Stage 6: Manage changes, overnight makesafe and reinstatement
/> If the method shifts – different plant, route, depth, or an extra crossing – suspend the permit and re‑issue with a fresh brief. At day’s end, secure open excavations, protect exposed services from vehicles and weather, and make traffic routes safe. Hand over to the next shift with photos and a clear statement of what’s been proven and what remains uncertain. On completion, update the red‑line drawings and return them to the site information board so future works aren’t starting blind.
Scenario: a road crossing on a live housing scheme
/> A civils gang had a weekend window to install a comms duct across a new estate road before plot scaffolds went up. Drawings showed a gas main on one side and street lighting ducting on the other, with nothing in the crossing line. The locator picked up a weak signal where the crossing was planned, but the operator wasn’t convinced whether it was bleed‑through from the lighting run. The supervisor held the excavator and brought in vacuum excavation for a trial hole at the crossing line. They uncovered a shallow, uncharted lighting cable running diagonally across the carriageway, likely from a temporary feed early in the build. The route was re‑planned by a metre, the permit re‑issued, and the crossing completed safely that afternoon. Without the hold point and the willingness to pause, the first bucket would have gone straight through it.
Permit-to-dig essentials: one-page briefing checklist
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– Latest utility maps, locator results and a simple sketch of ground markings are on hand and match what’s on the deck.
– Named supervisor present, with authority to stop and clear controls when crossing or nearing any suspected service.
– Locator proved on a known service before use; scanning completed for each shift and after layout changes or heavy rain.
– Ground markings are clear, weather‑proofed and explained to everyone; no‑go and hand‑dig zones agreed.
– Trial holes planned at key points; hand tools or vacuum excavation available and used as briefed.
– Emergency arrangements and escalation contacts are known; stop‑work triggers spelled out in the permit.
– Close‑out and handover steps agreed for the end of the shift, including protection of exposed services and updating red‑lines.
Common mistakes on dig permits
# Treating last month’s scan as gospel
/> Conditions change fast on live builds; temporary feeds and diversions appear with little notice. Refresh the picture whenever the site layout, weather or programme shifts.
# Drawing-only permits with no marks on the ground
/> A permit pack without paint, pins or flags where the bucket will bite is a paper exercise. Put the information at the point of work in a way that survives rain and wheels.
# Hand digging with the wrong tools or force
/> A spade driven hard is as risky as a micro‑digger in the wrong place. Use insulated hand tools and pare down lifts carefully until the service is exposed.
# No one updates the permit when the method changes
/> Swapping plant, changing depth or edging the route to “save time” can push you into an unverified zone. Suspend, rethink, and re‑brief before carrying on.
Bottom line on permits and service avoidance
/> Permits to dig aren’t clipboards to wave at an audit; they are a framework that lets supervisors control risk, crews understand limits, and plant only operate where the ground has been proven. Get the planning right, verify properly, brief clearly, and keep a live grip on change – that’s how service strikes are kept out of the accident book.
# Actions to land this week before the first bucket hits the ground
/> Walk the route with the utility plans and physically mark suspected corridors; bring the locator operator to that walk. Set explicit hold points in the permit and schedule the supervisor to be present for each. Line up vacuum excavation for congested areas rather than hoping hand digging will cope. Prepare a one‑page sketch for the briefing and take a photo of the ground markings to attach. Agree the stop‑work rule: if anything doesn’t fit the picture, all plant parks up until it does.
If site teams treat the permit as a living control rather than a form to file, the strike risk drops dramatically. The pressure will keep coming from programme and access, so the test is simple: will you pause the dig when the information isn’t good enough?
FAQ
# Who should sign and control a permit to dig?
/> A competent person with excavation and service‑avoidance knowledge should issue and control the permit, typically the principal contractor’s supervisor or site manager. They need the authority to stop works, set hold points and insist on re‑verification when conditions change. Subcontractor leads should co‑sign to confirm their crews understand and will follow the controls.
# How often should a permit be revalidated?
/> Treat permits as shift‑based unless the conditions are unchanged and have been re‑checked. Any change in layout, weather, plant, lighting or workforce should trigger a re‑brief and, if needed, cancel and re‑issue. If in doubt, pause, verify and refresh the permit before carrying on.
# What tools are acceptable for hand digging near suspected services?
/> Use insulated shovels and wooden‑handled tools, working carefully to peel away small amounts of material. Avoid picks and crowbars near likely services, and never drive tools with body weight or excessive force. Where the ground is hard or congested, consider vacuum excavation rather than forcing hand tools.
# When should more advanced locating methods be brought in?
/> If records are unclear, the locator gives inconsistent results, or the work area is known to be crowded, bring in more capable detection such as multi‑mode scanning or ground‑penetrating radar. This is especially relevant for road crossings, service clusters, or older sites with undocumented alterations. Good practice is to escalate the survey when confidence in the ground picture is low.
# What happens if an uncharted service is found mid‑excavation?
/> Stop work immediately and make the area safe, including isolating plant and keeping people clear. Expose the service carefully, protect and mark it, and update the permit, drawings and brief before resuming. Notify the client and affected parties so future works and records are corrected, and capture photos for the as‑built pack.
