Electromagnetic detection, ground-penetrating radar and concrete scanning — finding the private utilities the provincial one-call system will never mark for you.
Nova Scotia One Call notifies member utilities so they can locate their own infrastructure. It does not cover privately owned services — the feed to an outbuilding, site lighting, irrigation, fuel lines, private water and sewer, or the conduit somebody trenched in years ago and never recorded anywhere.
Those are the lines that get struck. Private locating is the gap between holding a one-call ticket and actually knowing what runs under your excavation, and against the cost of a strike — the repair, the downtime, the report, and the very real possibility of injuring someone — it is the cheapest risk reduction available on any dig.
EM and GPR find different things in different ground. Bringing only one is how non-metallic pipe gets missed. We run both and tell you plainly which one carried the result.
Paint washes off in the first rain. Every locate can be surveyed to project coordinates and delivered as a drawing, so the information survives the weather and the next contractor.
Every locate states which method carried the result and what the ground allowed. Where a target can't be confirmed we say so plainly, rather than handing you a clear site that isn't.
No single method finds everything. What works on a steel main tells you nothing about a plastic water service, so the honest approach is to bring several and be explicit about which one produced the result.
The workhorse. A transmitter applies a signal to a conductive target — directly, by clamp, or induced from the surface — and a receiver traces it. Fast and reliable on metallic pipe, cable and tracer wire. Congested corridors, poor grounding and nearby metal all degrade the result, and we tell you when conditions were working against us rather than reporting a clean sweep.
Sends a radar pulse into the ground and reads what bounces back, so it finds non-conductive targets EM cannot — plastic pipe, ducting, vaults, tanks and voids. Performance is entirely ground-dependent: dry sand and gravel read well, wet clay and high-conductivity soils attenuate the signal badly. We report the depth the ground actually allowed.
Where a non-metallic line is accessible — a sewer lateral, a duct, a conduit — a sonde is pushed through it and traced from the surface. This is often the only way to establish the true route of a plastic service rather than inferring it from where it should be.
GPR against slabs and structures to locate rebar, post-tension cable and embedded conduit before coring, cutting or anchoring. Considerably cheaper than cutting a tendon, and quick enough that it rarely holds up the work.
Honest limits stated up front, because a locate presented as more certain than it is causes exactly the incident it was meant to prevent.
| EM horizontal accuracy | Typically within ±15–30 cm of true horizontal position under favourable conditions on a well-coupled, conductive target. Congested corridors, poor grounding and adjacent metal all degrade this. |
|---|---|
| Depth estimation | EM depth readings are estimates derived from signal geometry, not measurements. Treat them as indicative. Where depth genuinely matters, it is confirmed by exposure. |
| GPR performance | Highly ground-dependent. Dry sand and gravel give good penetration; wet clay and high-conductivity soils attenuate the signal badly and can limit useful depth considerably. We tell you what the ground allowed rather than what the brochure claims. |
| Non-metallic services | Plastic water and sewer, fibre and unmarked conduit carry no signal for EM. These need GPR, a traceable sonde where the line is accessible, or exposure. |
| Field marking | Colour-coded to standard utility marking conventions, with line, depth estimate and service type marked at the surface. |
| Confidence stated per utility | Each located service is reported with the method that found it and the confidence achieved, rather than a single blanket claim across the whole site. Anything suspected but unconfirmed is marked as such. |
It's necessary and it's free, so always place the ticket. But it only reaches member utilities locating their own assets — everything privately owned on your site is outside it. On any developed property, most of what's actually in the ground is private, and that's precisely what gets hit.
Under good conditions on a conductive target, EM will typically put you within ±15–30 cm horizontally. Depth is an estimate, not a measurement. Anyone quoting you centimetre certainty from a locate alone is overselling — the only way to know a position exactly is to expose the line, and we will tell you when a job warrants that.
Not with EM, which needs a conductive path. We use GPR, or trace a sonde through the line where it's accessible, or expose it. Non-metallic services are the single most common cause of a “cleared” area still containing a live line, so we flag them explicitly rather than reporting an absence of signal as an absence of pipe.
Depends on what the information is carrying. A few post holes on a known site needs a targeted locate. A full site sweep before excavation, or mapping ahead of a design, is a bigger scope and worth it where a strike would stop the project. We'll scope it to the risk rather than selling the largest version by reflex.
A few days for routine private locates in the Halifax region. Full site sweeps with mapped deliverables need longer, because there's drawing production behind the field work — tell us the excavation date at scoping and we'll work back from it.
