Ground Penetrating Radar (GPR)

What It Is

Ground penetrating radar is the practice of imaging the subsurface non-destructively. A radar unit emits short pulses of high-frequency electromagnetic energy into the ground; the return signal is processed into a cross-sectional scan that shows pipes, cables, voids, and anomalies up to several metres deep.

GPR is the same family of technology used by civil engineers, archaeologists, and utilities surveyors — calibrated, in our case, for the specific job of finding water lines and the voids that develop around active leaks.

How It Works

The unit moves slowly across the surface on a wheeled trolley while the radar emits pulses several thousand times a second. Each return is recorded against the position of the trolley to build up a continuous slice of the subsurface.

Software interprets the slice in real time and the technician annotates points of interest on screen. The result is a map of every detectable line under the path the trolley has covered.

What It Detects Best

GPR is the right tool for mapping unknown pipe routes, identifying parallel utilities (water, gas, telecoms, electrical), and confirming the depth of a known line before excavation. It is especially valuable on properties where the as-built drawings are missing or unreliable — which is most properties.

It also identifies voids — the empty pockets that develop in soil around a long-running underground leak as water washes fines downstream. A void on the GPR scan is often the strongest single indicator of where to dig.

When We Use It

We deploy GPR on jobs that involve excavation downstream — pre-purchase inspections where the buyer plans to renovate, builder-engaged surveys before a rear extension, and any complex underground leak detection where pipe routing is unclear.

A GPR survey of a typical residential block takes 60–120 minutes and is logged as both a printed plan and a digital file delivered with the report.

What The Client Experiences

GPR looks like a small lawn mower being pushed slowly back and forth across the property. The unit is silent, has no impact on the surface, and produces no fumes or vibration.

When the survey is finished, you receive a marked-up plan of every detected line. Many clients find the plan more valuable than the leak detection itself — it is the document that prevents a contractor from cutting through a high-voltage cable next time someone digs in the yard.

Why It Matters

GPR turns a blind excavation into a targeted one. A documented utility map means the difference between a 30-minute pinpoint repair and a damaged service that takes the local network offline for half a day.

It is the difference between cutting one trench and cutting three. It is the difference between finishing the job at lunchtime and finishing it at sunset. It is, more than any other tool we use, the one that pays for itself the first time it prevents a strike.