Scanning a Marquee Site for Buried Services Before You Stake
A marquee puts steel into the ground at dozens of points — the stake line, the eaves, the high-load anchors. Before you fix that layout, scan it. This is how to sweep a marquee footprint for buried cables and pipes, where to concentrate, and when to stop and move the plan. It sits alongside our wider cable avoidance guide — start there for the why and the rules.
Contents
Start With Drawings and a Walk
Before the kit comes off the van, get the venue's service drawings and walk the footprint. You're looking for anything a service runs to or from — the building, supply points, lighting columns, pumps, manholes, meter boxes, external taps. Those are your clues to where cables and pipes are likely to cross the ground you're about to stake.
Treat the drawings as a guide, not gospel. Services get added, re-routed, and are rarely recorded as-built — and estate, showground and heritage venues are often the worst documented. The drawings tell you where to look hardest; the scan tells you what's actually detectable on the day.
Sweep the Stake Line and Anchor Positions
Scan where you intend to drive — the full stake line and every anchor position — plus a margin around it. The mistake is a single pass down the middle: a buried line can run diagonally across a footprint and sit silent until you cross it at the wrong angle. Work the area from each side in turn, moving the locator along the run and tracing any signal across and out of the staking area before you mark it.
Concentrate on the high-load anchor positions — main eaves points, ridge anchors, clearspan leg positions — because those are both the most likely to be reinforced with deeper or ganged stakes and the most consequential to get wrong. Scan in every mode the tool offers and use the Genny: a detector left in its passive modes will miss services that aren't radiating a signal. The CAT and Genny modes are explained here if you're new to them.
If your layout might shift — and on an uneven or constrained site it often does — scan the alternative stake positions too, so a last-minute move doesn't put a stake into ground you never checked.
Mark Up and Keep Clear
Mark every located service on the ground — spray line or pegs — and record it on your layout. Keep a wide margin between any marked service and a stake position; don't drive right up to the edge of a located line. If a service crosses a planned stake point, move the stake. The whole point of scanning before you fix the plan is that repositioning a stake on paper costs nothing, and repositioning it after you've hit something costs a great deal more.
When to Stop and Move the Plan
Some signals you won't fully resolve, and some ground you won't be confident about — old estates with unmarked supplies, areas of buried hardcore, sites where the drawings and the scan disagree. When that happens, the answer is not to drive and hope. Move the stake, hand-dig to expose and confirm, or get the utility or a competent locator involved before committing.
A scan that comes back clear is not proof the ground is empty — it means nothing was detected with the methods used. A CAT misses unloaded cables, and plastic or rubber pipes carry no signal at all unless one is applied. So where you must break ground near anything you've located or suspect, expose it safely first rather than driving blind.
Then — and Only Then — Stake
Once the ground is established as clear to drive into, the rest of good staking applies as normal: the right stake for the ground, driven vertical for holding power, to full embedment. Our guides on driving stakes with a powered breaker and staking in hard ground pick up from there, and the stake calculator will size the schedule. Cable avoidance is simply the step that comes first — before the first blow, every time.
We're bringing a CAT and Genny into the Hogan range so the crews driving our stakes can scan with kit from one supplier. If you'd like to talk cable avoidance on a specific venue, get in touch.
Email: hoganuk [at] hoganstakes.co.uk
Contact form: hoganstakes.co.uk/contact
Safety note — this is an overview, not training. Cable avoidance is safety-critical. This guide explains how to approach scanning a marquee footprint; it is not a substitute for competent, trained use of a cable locator (HSE HSG47), the venue's service information, or your own risk assessment. If you cannot establish that a position is clear, do not break ground there.
Background drawn from HSE HSG47, the MUTA 2026 Best Practice Guide, and publicly available CAT & Genny training material (Paragon, Sygma Solutions, Proper DIY). Used as reference; adapted for UK marquee-site practice.
Common Questions
How do I scan a marquee footprint for buried services?
Start with the venue's service drawings and a walk of the footprint, noting anything with a service running to it. Then sweep the ground with a CAT and Genny — work across the staking area from each side in turn, moving the locator along and tracing any signal across and out of the area. Pay particular attention to the stake line and the high-load anchor positions, not just the centre of the footprint. Mark what you find and keep clear of it.
Do I scan the whole site or just where the stakes go?
Scan where you intend to break ground and a margin around it — the stake line, the anchor positions, and any spot you might reposition into. A signal can run diagonally across a footprint, so sweeping from each side of the staking area (rather than one pass) is what catches a line you would otherwise drive across. If the layout might move, scan the alternative positions too.
What if I find a service under a planned stake position?
Don't drive there. Mark the line, keep a wide margin, and reposition the stake or the anchor. Where you cannot avoid breaking ground near a located or suspected service, expose it by hand-digging or vacuum excavation rather than driving blind — and if you cannot establish it is safe, stop and get the utility or a competent locator involved before committing.
Can I just rely on the venue's service drawings?
No. Drawings tell you what should be there, but services get added, moved, and are rarely as-built, and heritage or estate venues are often poorly documented. Use the drawings to inform the scan, then scan on the day, then still dig safely. Each step covers the gaps in the others.
Does scanning mean I can stake without digging carefully?
No. A clear scan means nothing was detected with the methods used — not that the ground is empty (a CAT misses unloaded cables and non-metallic pipes). Where you break ground near anything located or suspected, expose it safely first. Treat the scan as the thing that tells you where to be most careful.