Ground-penetrating radar (GPR) finds things an electromagnetic locator can’t, such as plastic water lines and unknown services. It also produces the reports clients find hardest to read: a stack of radar screenshots, a few circles on a sketch, and depths with no explanation of where they came from. A good GPR report turns the scan into something an engineer or an excavator operator can use.
This template draws on published guidance from the United States Environmental Protection Agency (EPA) and Federal Highway Administration (FHWA), and on the Before You Dig Australia (BYDA) Best Practice Guide. Adapt it to your equipment and each client’s specification.
What the radar is actually telling you
GPR sends short radio pulses into the ground. Where the pulse meets a change in the ground’s electrical properties, such as a pipe, a cable or the edge of a trench, part of the energy reflects back. The receiver records how strong the reflection is and how long it took. Shown as a cross-section, a pipe crossed at an angle usually appears as a hyperbola, an upside-down U, with the pipe at its peak.
Three things follow, and each belongs in the report:
- Depth is an estimate. GPR measures time, not distance. Depth comes from that time and an estimated speed of the pulse through the ground, which the EPA notes is often set from a reflector at a known depth. If you calibrated on an exposed pipe or a pothole, say so. If you used a default value, say that too.
- Ground conditions decide the depth you can see. The EPA says the signal loss is mainly controlled by how electrically conductive the ground is, and that ideal conditions are rare because of conductive groundwater and clay. Wet, clayey or salty ground can cut the useful depth sharply.
- Not every reflection is a service. The EPA notes that part of the signal travels through the air and can reflect off objects on the surface, showing up as false targets. Rocks, roots, rubble and old trench lines reflect too.
The FHWA adds that whether a pipe is detected depends on its depth, size and condition, the backfill around it and the surface above it. GPR can detect metallic and non-metallic pipes, but it isn’t guaranteed to detect either.
The template
1. Job and site - Client, site address, purchase order (PO) number, your job number, the date, and the operator’s name. - The BYDA enquiry reference, if the scan is part of a locate.
2. Purpose and scope - What the scan was for: a clearance for a bore, a footing or a trench, or mapping a corridor. - The area scanned, on a sketch or aerial image, and anything left out.
3. Equipment - The system and antenna used, and when it was last checked.
4. Survey layout - Direction and spacing of the scan lines. The FHWA suggests running lines across the expected direction of a service. - How the lines are tied to fixed features on site.
5. Depth calibration - How the speed of the pulse was set: a known-depth target, a pothole, or an assumed value.
6. Site conditions - Surface type, ground conditions, and recent rain. - Areas you couldn’t scan.
7. Targets For each target: - A number, the lines it appears on, and its likely type. - Estimated depth, with the calibration it relies on. - Whether an electromagnetic locator or a plan confirms it. - The quality level you are reporting, and why. - Photo or screenshot references.
8. Limitations - Depth reach on this site, false-target risk, and services the method may have missed.
9. Drawings and sign-off - A site drawing with every target, its depth and offsets to fixed features. - Operator sign-off and your standard disclaimer.
An example target entry
An illustration of the format, not real data:
- Target 4: a non-metallic pipe, likely water, unconfirmed.
- Seen on: lines 6 to 11, as a clear hyperbola.
- Estimated depth: 0.6 m, using a speed set at the exposed water main in pothole 1.
- Electromagnetic locator: no signal; no tracer wire found.
- Reported as: detected by radar; depth not verified by exposure.
- Photos: P12, P13.
Quality levels and radar
Whether a radar detection can be reported at Quality Level B depends on meeting the requirements for that level in Australian Standard AS 5488 and the client’s specification. Check the current edition rather than assuming. A target that was then potholed and exposed can be reported at Quality Level A at that point. Our article on quality levels explained covers the differences.
How OpsChase builds the report
In OpsChase’s utility locating software, the operator records each target on their phone: type, method, depth, quality level, notes, geotagged photos and screenshots of the radar display, plus a site sketch. OpsChase doesn’t process radar data. It turns what the operator records into a branded report grouped by quality level, with methods and limitations set out the same way every time, and the invoice comes from the same job.
Where to start
Take your last radar report and check it has a depth calibration line and a limitations section. If not, add both first. Then compare it with our locating report template, see pricing, or book a demo.