Service strikes aren’t just costly; they hurt people, shatter programmes and leave sites tied in knots with emergency repairs and investigations. A permit to dig is the control that stitches planning, detection, supervision and change management into one process. Treated as a living control, not a form to file, it’s the difference between confident progress and a shut-down trench with a crowd of hi-vis staring at a fizzing cable.
TL;DR
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– Agree the dig zone, depth and method, then scan and mark everything before anyone touches the ground.
– Issue permits with clear hold points, competent persons named, and photos of the mark-out attached.
– Break ground under supervision using the right kit for the risk, and prove services by trial holes.
– If conditions change, stop, re-scan and re-issue. No drift, no guessing, no crossing out in biro.
The controls playbook for striking-free digs
/> A permit to dig is a staged control. Each stage builds assurance: plan, detect, brief, execute, and then hold a firm line when reality doesn’t match drawings. Treat the steps below as non-negotiable, with your supervisor owning the handovers.
# Plan the dig: desktop and utility coordination
/> Start with current utility plans, recent as-builts, and any client information from previous phases. Define the footprint, depth, plant to be used, and what the hole is for. Engage temporary works where needed for shoring and edges. Lock in the sequencing with adjacent trades so you’re not scanning over fresh spoil or working above buried nets of new ducting.
# Scan and mark: detection and setting-out
/> Use appropriate locating methods for the risks: cable avoidance tools, signal generators, and ground penetrating radar where congestion or uncertainty exists. Only competent persons do the scans; if you don’t have them, bring them in. Mark services visibly on the ground with colour codes, arrows and offsets to fixed features. Photograph the mark-up with measurements that can be understood even if paint fades or weather moves things.
# Permit issue and conditions that matter
/> Don’t issue a permit until the scan and mark-out are complete and verified. State exact limits, permitted methods (hand-dig, vacuum, restricted plant), and hold points such as “stop at 300 mm for hand trial”. Name the supervisor in charge and list the operatives briefed. Attach drawings and photos, record the date/time of the last scan, and set an expiry so it can’t drift for weeks.
# Break ground under control: trial and expose
/> At the face, stick to the agreed method. Hand-dig or vacuum around expected service lines and prove their position before bringing in any mechanical plant. Keep the CAT and plans available at the trench, and re-scan edges as you progress. Maintain exclusion zones, spoil placement, edge protection and traffic routes so the workface stays orderly, not frantic.
# Manage change and close out
/> If conditions are not as expected—unknown ducts, old slabs, abnormal depths—pause the permit, make it safe, and go back to mark-out. Do not amend permits in the trench; re-issue with revised controls following a fresh brief. When complete, sign off the permit, capture as-built locations where you’ve installed or exposed, and debrief what worked and what didn’t for the next dig.
Where permits unravel on busy UK sites
/> Paperwork doesn’t stop strikes—behaviour and discipline do. These are the trip points that turn a permit into a tick-box.
# Assuming yesterday’s scan still stands
/> Weather, plant movements and overnight works can shift references. A quick re-scan at the start of each shift is small effort compared to a hit.
# Vague boundary lines and over-reach
/> If the mark-out doesn’t show edges and offsets, the dig spreads. Be specific about limits and install physical markers if needed.
# Supervisors tied up elsewhere
/> Permits rely on active control. If the named supervisor disappears to chase deliveries, the method drifts and corners get cut.
# Changing the kit without rethinking the risk
/> Swapping to a breaker because “the ground’s hard” is high-risk without revisiting the permit. New method, new brief, or stop.
Scenario: drainage tie-in beside a live retail park
/> A civils gang is booked to make a weekend surface water connection onto a live run along the edge of a retail car park. Utilities plans show low-voltage cables and a water main nearby, but the records are old. On Friday, the supervisor arranges a scan with a competent locator; GPR picks up an unrecorded duct crossing the proposed trench. The mark-up is set with offsets to kerbs, and a permit limits the first 600 mm to hand-dig only, with a stop point at any unexpected service. Saturday morning, the gang exposes the unknown duct by trial hole and finds comms at shallow depth, just inside the dig line. The supervisor adjusts the trench line by 400 mm, re-issues the permit with new photos, and they complete the tie-in using vacuum excavation around the crossing. No hits, no surprises, and the car park reopens as planned.
Supervisor’s mini-checklist before any hole is opened
/> Before the first spade, take two minutes to make sure the basics are locked in. If any are missing, stop and fix, not “we’ll sort it as we go”.
– Latest utility information and drawings are at the workface, not in the cabin.
– Scan completed today by a competent person, with services marked and photographed.
– Permit states limits, methods, hold points and named supervisor; expiry date is visible.
– Method of breaking ground matches the permit; correct insulated tools and vac applied where specified.
– Exclusion zone, barriers and signage in place; traffic routes and spoil location agreed.
– Toolbox briefing delivered to the exact crew present; signatures captured; everyone can point to the service lines.
Bottom line on digging without strikes
/> A good permit to dig is a control loop: find, verify, brief, do, and pause when reality shifts. Keep it live, keep it owned by the supervisor at the trench, and don’t let programme squeeze out the checking steps that actually prevent hits.
# In the next week: tighten permit discipline around services
/> Walk the site and sample three active or planned digs. Ask to see scans, photos and permits at the workface, not in email. Watch the first 10 minutes of breaking ground to see if practice matches paper. Where it doesn’t, reset the standard and back supervisors to stop and re-issue without argument.
FAQ
# When should a permit to dig be used?
/> Use a permit whenever there’s a risk of striking buried services or affecting ground stability, even for small trial holes. It’s also good practice near existing foundations, slab penetrations, and in refurbishment where service routes are often unknown. If in doubt, assume a permit is needed and escalate to the site manager.
# Who is competent to carry out service detection?
/> Competence comes from training, experience and the right equipment for the ground conditions. On many projects a specialist locator is brought in, especially where records are poor or routes are congested. If your own team is scanning, make sure they can demonstrate how to use the kit correctly and interpret results conservatively.
# How often should services be re-scanned once work has started?
/> Re-scan at the start of each shift and whenever the dig line, depth or method changes. Weather, ground movement and plant can all affect readings and reference points. Treat re-scanning as a routine hold point, not an exception, particularly on longer trenches.
# What if the dig uncovers uncharted services?
/> Stop the task, make the area safe and inform the supervisor and site management immediately. Re-scan, update the mark-out, and re-issue the permit with new controls before resuming. Don’t rely on guesswork or verbal assurances; capture photos and offsets so the change is clear to everyone.
# How do permits interface with temporary works and traffic management?
/> The permit should reference any approved temporary works designs for shoring, edge protection and crossings. It should also align with traffic routes, exclusion zones and spoil management so plant and pedestrians are kept apart. Coordination with the temporary works coordinator and traffic management lead before issuing the permit avoids clashes at the trench.
