A permit to dig is not a form that lets you start the mini digger; it’s a structured process that forces the team to confirm where services are, choose the right method, set hold points, and stop if anything doesn’t line up. Most service strikes happen because people rush, rely on out-of-date plans, or treat scanning as a tick-box. A good permit ties together records, competent scanning, visible mark-up, controlled breaking ground, and supervision through to backfill.
TL;DR
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– Treat the permit as a live control with hold points, not a one-off signature.
– Combine utility plans, competent scanning, visible mark-up, and hand-dug trial holes.
– Set clear stop rules for unknowns, strong signals, or when the plan and the ground don’t match.
– Keep supervision tight at the start of each dig, and refresh controls when locations, depth, or method change.
Controls playbook for avoiding service strikes
/> Getting digging right is about sequencing, not luck. The following staged approach joins planning, supervision and method so the permit to dig actually prevents strikes rather than decorating clipboards.
# Stage 1: Gather the utility intelligence before methods are set
/> Start with current statutory plans and any client or as-built records for the plot and surrounding area. Walk the route with someone who knows the site history; spot street furniture, ducts, cabinets and previous openings that hint at live services. Decide early if you need specialist surveys (for example, GPR) and allow them into programme, rather than hoping a last-minute scan will save time.
# Stage 2: Scan, trace and mark with tolerances in mind
/> Use competent people with maintained cable avoidance tools and signal generators. Scan the whole dig area and a buffer around it, in multiple orientations, and repeat after moves of plant or barriers. Mark detected lines on the ground in a clear, consistent colour code, add direction arrows, and record with dated photos; treat marks as guidance with tolerances, not exact positions.
# Stage 3: Choose safe methods and build hold points into the permit
/> Base the method on what you actually found: hand-digging around detected lines, vacuum excavation where feasible, and mechanical digging only outside agreed no-go zones. Include trial holes to confirm depth and location before bulk excavation. Write the hold points into the permit: “no machine dig within x of marked gas main”, “pause after first 300 mm to verify layers”, and “stop if service is not where expected”.
# Stage 4: Control the first break of ground and keep supervision close
/> Brief the gang properly: show the plans, walk the markings, and agree the stop rules. Set short initial runs under close supervision; do not let the dig sprint away from the plan on day one. Keep plant-pedestrian separation tight, use a banksman who knows the service layout, and make sure hand tools are insulated where needed; PPE is the last line, not the plan.
# Stage 5: Respond to change, unknowns and finds without guesswork
/> If you hit hard spots, unusual layers, or get a strong instrument signal where none was expected, stop and escalate. Treat any uncharted service or duct as live until proven otherwise; secure the area, inform the permit issuer, and involve a competent surveyor or utility owner where required. Do not expose a service and then continue digging without reassessing your method and re-briefing.
# Stage 6: Close out properly and leave records better than you found them
/> When the dig is complete or paused, protect exposed services from damage, collapse or vehicle loading. Update red-line drawings, keep the photos, and note any discrepancies so the next team is not guessing. Close the permit formally; if the work restarts later, issue a fresh permit after a new scan and briefing.
Site scenario: drainage tie-in under programme pressure
/> A civils team on a school build needed to tie into an existing manhole along a footpath beside a live road. Plans showed electrical and telecoms nearby; the supervisor arranged a morning scan that picked up one telecom and a weak electrical trace. The permit called for hand-digging the first metre, but the gang switched to a whacker and then a small breaker once they hit compacted Type 1. At 350 mm, the breaker clipped a shallow telecom duct that was running offset to the plan. Work stopped, the service owner was called, and a costly repair and lane closure followed. The root causes were rushed method change, thin supervision in the first hour, and overconfidence in the plan. On the restart, the team extended the scan, vacuum excavated trial holes to confirm depths, repainted the mark-up, and the permit included a hold point after each 300 mm layer. The tie-in completed without further drama, but the lost day could have been avoided.
Supervisor’s quick checklist before breaking ground
/> Before anyone lifts a spade or bucket, have a short walk-round with this list in your hand. It is about controls you can see and actions you can lead.
– Utility plans on hand, date-checked, and the dig area walked with someone competent.
– Fresh scan completed, lines marked clearly on the ground and photographed with dates.
– Method reflects the findings: trial holes planned; hand-dig or vacuum where required.
– Permit issued for the exact footprint, with hold points, expiry time, and named supervisor.
– Briefing done at the hole: everyone sees the marks, stop rules, and exclusion boundaries.
– Contingency agreed: who to call, what to barricade, and how to secure an exposed service.
Common mistakes on permits and service avoidance
/> Even capable teams fall into predictable traps. These four are behind a lot of near misses.
# Treating the permit as an admin step
/> Signing the permit in the office, then leaving the gang to interpret it at the trench, removes the control. The permit should live at the workface, backed by a face-to-face briefing.
# Over-reliance on old drawings
/> Utility plans age fast and often show indicative routes. Without a fresh scan and trial hole, you are guessing.
# Letting methods drift under pressure
/> Hand-dig specified; breaker used because the fill is tough. Any method change near services demands a pause, a rethink and a re-brief.
# Weak first-hour supervision
/> Most mistakes happen in the first stretch. If the supervisor isn’t present at start-up, shortcuts creep in and the plan gets ignored.
Bottom line
/> Permits to dig prevent strikes when they force planning, competent scanning, visible mark-up, conservative methods and disciplined stop rules. If any part is missing, you are relying on luck around live services.
# First 10 shifts: service avoidance actions to land now
/> Make these moves quickly on live projects to lift your strike prevention without derailing programme. They are small, practical and visible.
– Map the first week’s dig locations and set up early scans so permits are issued with time to brief.
– Ring-fence high-risk zones with clear no-machine boundaries and signage on barriers.
– Rotate experienced supervisors onto first-hour coverage at each new dig, then taper as controls bed in.
– Brief plant ops and groundworkers together at the hole, using photos of the mark-up and actual tools.
– Stage trial holes as mini-tasks with hold points, so depth checks are documented before bulk excavation.
Service avoidance is not complicated; it is disciplined. The sites that keep it tight treat the permit as a live control, not a comfort blanket.
FAQ
# What should a permit to dig actually include?
/> It should define the exact area, the services expected, the scan and mark-up completed, and the agreed method with hold points. It must name who is supervising, the permit validity, and the stop rules if something unexpected is found. Keep it at the workface and refresh it if the footprint or method changes.
# How often should scanning be repeated during an excavation?
/> Repeat scanning after barriers move, plant is repositioned, or when the dig extends beyond the original footprint. It’s also good practice to re-scan at the start of each shift and after any heavy rain or backfill that may affect readings. Treat scanning as ongoing verification, not a one-off.
# When is vacuum excavation worth bringing in?
/> It is useful where services are shallow, congested, or poorly recorded, and hand-digging would be slow or risky. If the programme can accommodate it, vacuum excavation reduces the chance of damage when exposing or crossing known lines. The decision should be based on the scan findings, the ground, and the proximity of critical utilities.
# How do we manage interfaces with other trades around an open dig?
/> Set and maintain physical barriers, clear access points, and signage to prevent casual crossing of the excavation zone. Coordinate timings so deliveries and pedestrian routes don’t push people through the work area. Include neighbouring supervisors in briefings about exposed services and no-go zones.
# What are clear triggers to stop work and escalate?
/> Stop if the scan gives a strong signal where none was expected, if a service is not where the plan suggests, or if you encounter unknown ducts, tiles or marker tapes. Also pause if the method has to change (for example, from hand-dig to mechanical) or if supervision is not present as planned. Secure the area, inform the permit issuer, and agree a revised approach before restarting.
