GPR / Radar
Investigates subsurface reflections and can help detect metallic and non-metallic buried features. Ground conditions, depth and target size influence the results.
GPR & EM
Investigate before
you excavate.
Our utility locating combines available records, electromagnetic tracing and ground penetrating radar where practical. We assess the evidence together and communicate the findings for your project.
COMPLEMENTARY METHODS
Plans. Measurements.
Field observations.
GPR investigates metallic and non-metallic features. EM traces conductive services. Neither method finds every target; access, conditions and the asset itself influence the result.
Common applications include foundations, crossings, drainage, service trenches, directional drilling and work around existing infrastructure.
Request a locateTwo methods. A clearer investigation.
EM / Electromagnetic
Traces a signal along conductive services or tracer wires. We compare the trace with available records, GPR findings and observations on site.
Our investigation process
- 01
Review records
We obtain and review available plans from Before You Dig New Zealand and relevant asset owners. Records provide a starting point and may omit private or recently installed services.
- 02
Locate & compare
EM and GPR findings are assessed together.
- 03
Mark & report
Site markings and reporting communicate the findings.
GPR questions
Where do you provide GPR utility locating?
Hall Surveying provides ground penetrating radar and electromagnetic utility locating across Auckland, including the North Shore, West Auckland, East Auckland and South Auckland. Send us your site address to discuss access and survey scope.
What underground services can GPR detect?
Ground penetrating radar can assist in investigating metallic and non-metallic buried features, including water pipes, stormwater and wastewater infrastructure, electrical conduits, telecommunications ducts, gas services and unknown services. Detection depends on ground conditions, target size and depth; we compare GPR findings with electromagnetic locating and available plans wherever practical.
How does GPR work?
Radio waves identify changes below the surface. Interpreting those reflections helps investigate buried services and other features.
Can you locate plastic pipes?
GPR may detect non-metallic pipes that cannot be traced electromagnetically. Success depends on the ground, pipe size and depth.
Why combine GPR and EM?
EM can trace conductive services or tracer wires. GPR adds information about other targets. Comparing both with utility plans improves the investigation.
What limits the results?
Clay, wet or conductive ground, reinforced surfaces, depth and congestion can reduce penetration or make interpretation difficult.
Are services marked on site?
Located routes are marked using recognised utility colours, with findings recorded in the project report.
Do you provide a report?
Yes. Reporting can include annotated photographs, plans, observations, estimated depths, confidence and recommendations.
How long does a locate take?
We scope the time around site size, access, complexity and the required deliverables.
Do I still need utility plans?
Yes. Plans are a starting point and are compared with field results; private or recent services may be missing from records.
Can you confirm a pipe’s size or material?
Size and material information may come from available asset plans. A detected signal alone does not confirm either, and an unknown detected service may remain unidentified. The report explains the available evidence.
What does an estimated depth mean?
Depth information depends on the method and site conditions. Refer to the report and survey plan for the recorded depth reference and limitations; discuss any critical excavation decisions with the relevant project professionals.
Can weather affect the survey?
Heavy rain and saturated ground can reduce radar penetration and clarity. We assess conditions and discuss access or rescheduling where required.
How deep can GPR detect services?
There is no guaranteed detection depth. Ground conductivity, moisture, target size, depth and surface conditions determine what can be interpreted. We report the limitations of the investigation.
Can you investigate gas services?
We can investigate gas routes using available asset plans, GPR and EM where the service or tracer wire can be traced. A reflection alone does not identify an unknown pipe as gas.
Can I book surveying with the locate?
Yes. Tell us if your team needs the located routes recorded in a survey plan or DWG, or wants topographical detail and aerial capture included in the brief.
Detection is an investigation, not a guarantee that every service is identified. Use findings with appropriate safe excavation practices.
Before the site visit
Share the work area
Send the site address and mark the proposed excavation or investigation area on a plan or photo. Explain the work planned and required timing.
Provide available records
Include utility plans and relevant site drawings. Let us know about private services, previous alterations and anything observed on site.
Arrange access
Tell us about gates, parked vehicles, surface obstructions and site activity. Discuss access to relevant utility connection points and known hazards.
PLAN YOUR NEXT STEP
Your project.
The right survey.
Subdividing, building or investigating your site? Send us the address and a short brief. We’ll help you identify the survey work you need.
Silverdale based. Working across Auckland.