Photo courtesy of the Damage Prevention Professional Library
We’ve covered a wide range of technologies capable of tracking, marking and locating subsurface utilities over the past few months.
One such system we’ve only briefly touched on is Ground Penetrating Radar (GPR). A technology decades old, it has remained largely the same as it did many years ago.
While its convenience as a non-invasive and relatively inexpensive method of locating a number of underground objects has made it a helpful tool for some, its drawbacks has allowed other technologies such as Radio Frequency Identification (RFID) to surge forward into the future.
What is GPR?
Using a series of radar pulses, which are converted into visible images, GPR equipment is able to map out a user-defined portion of land, giving operators a two or three-dimensional glimpse of what lies beneath the surface.
Similar to systems used by seismologists to monitor underground acoustic signals, GPR uses electromagnetic radiation to detect where signals are reflected underground. In addition to physical objects, it can also detect voids and gaps that exist beneath the surface.
Although mainly used by scientists to study bedrock patterns, soil content, groundwater, and ice shifts, it has also been utilized by the utility industry to locate buried assets. It is one among a handful of technologies capable of providing technicians with a visual layout of an underground area without the need for costly excavation.
GPR’s 3-D imaging capabilities make it possible to locate and identify pipes, power lines, sewage assets and water mains among other utility elements.
The Drawbacks of GPR
Although its multi-dimensional imaging capabilities have made it a useful tool for some utility agencies, it has a number of significant drawbacks that can render the technology useless if particular conditions aren’t met.
The most prominent limitation of GPR is its inability to operate in high-conductivity environments such as soils rich in clay or salt content. In addition, the relatively complex imagery produced by such systems often requires trained and experienced technicians to interpret accurately.
Moist soils also dissipate the electromagnetic signals quickly, making it difficult to locate deeper assets.
Finally, in order to "read" a GPR response, one needs special training. If you don't believe me, just look at the screenshot of a GPR response below.
Taken with permission from digsmartofmaine.com.
RFID As An Alternative
In light of these disadvantages, many utility agencies are exploring alternative systems capable of overcoming the drawbacks of GPR technology.
One such system is Radio Frequency Identification. A comparatively new way of locating subsurface utilities, RFID goes far beyond simple imaging to encompass both mapping and tracking capabilities.
Instead of using pulses of electromagnetic radiation, RFID systems combine precise magnetic location tools to create a system of tagging and marking which can provide on-site technicians with a wide range of information about any particular asset given that its tagged with a corresponding RFID marker.
When an asset is initially buried or serviced, a marker tag is buried directly above it. This tag can hold geographical information as well as other data useful to operators attempting to locate and identify it. This information can then be used to create digital maps using third party software.
Unlike GPR, RFID is effective in a wide variety of geological conditions and can easily be used by workers on-site. Comparatively, this system also provides a much more accurate way to locate and identify particular assets.
To learn more about the InfraMarker, Berntsen’s all-in-one underground RFID marking system, visit the InfraMarker product page or request a catalog.