Detection Services

Underground Detection Services

A variety of detection methods and equipment can be applied to locate, identify and map underground features.

  • Detection of pipes
  • Detection of cables
  • Clearance of monitoring well and borehole locations prior to drilling
  • Clearing trenching positions for various construction applications
  • Service Detection and Surveying for design purposes
  • Marking identifies services out with spray paint on the surface or with painted stakes
  • Brief detection report with photos of identified services
  • Survey drawing in CAD formats
  • Other services

How do we do this:

We can provide detection services throughout Southern Africa for projects ranging from small construction or building sites through to large linear developments such as roads, power or pipelines.

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Cable Avoidance Tools (CAT)

The first part of the investigation involves the use of a Cable Avoidance Tool (CAT) instrument. The primary objective is the identification and marking of electrical cables on the site. This step is executed by traversing the survey area in a grid pattern. Live cables are discerned by referring to the CAT instrument’s display screen and a generated tone. Notably, the CAT instrument picks up detected services at a 90° angle, providing an indication of the alignment of the identified services.

Signal Generators

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Signal generators are essential tools in subsurface utility investigations. These devices emit signals along underground lines, aiding in the precise identification and tracing of buried cables and pipes. Working in tandem with other locating tools, signal generators enhance accuracy by inducing detectable signals on non-metallic or poorly conductive utilities. This efficient process ensures precise mapping and avoidance during construction or excavation, contributing to the overall effectiveness of subsurface infrastructure assessments.

Ground Penetrating Radar (GPR)

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The final phase of the investigation entails subsurface screening using ground-penetrating radar (GPR). This specialized investigation is crucial for identifying subsurface infrastructure that may go undetected by the CAT tool. Such infrastructure includes materials like fibre cement, PVC, or concrete structures. The GPR serves as a complementary tool, enhancing the overall effectiveness of the investigation by capturing details that may be overlooked by other methods.

Underground Detection Equipment Limitations

  • Ground penetrating radar does has limited penetration through very dense compacted material, saturated soil or soils covered in reinforced concrete
  • Where the dielectric value of the surrounding soil and the service you are looking for are close to each other, a very weak or no reflection will be visible
  • The GPR unit has to be in contact with the soil surface and irregular surfaces cannot be scanned
  • Outside interference from high voltage underground or overhead lines
  • Detected underground services cannot always be service-specifically identified unless they are visible at a termination point, manhole or according to existing information
  • In areas where underground services are densely concentrated in sub-metre areas, services will be indicated as a band of services. Equipment used in the proposed survey can’t distinguish between individual services in such areas if ground conditions do not allow it
  • Services buried on top of each other can often not be distinguished using electrical or radar detection methodologies
  • Depth of detected services can be supplied by the avoidance tool if a good signal connection can be made or by GPR within a 10% accuracy
  • Dense clay formations, high water tables, rubble used as backfill, excessive steel reinforcement in concrete or even load shedding can influence the accuracy of the equipment used and the outcome of the survey
  • Whilst employing appropriate equipment, processes and best endeavors at all times, no guarantee can be made that any particular element of buried infrastructure will be properly detected or parameterized by the proposed survey due to the large number of variables encountered on different sites. For critical applications it is always recommended that a survey be followed by careful hand excavation and air knife probing