Utility Detection



Since beginning operations in 2007 TeaCo has regularly conducted GPR surveys in the 250MHz and 500MHz frequency ranges in order to locate utilities, ducts, and vaults for a very diverse group of professionals yielding tremendous results.
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In many instances the survey area can be characterized in a matter of hours, can be marked in real time in the field, all the while collecting a digital record of the area imaged for later scrutiny by TeaCo’s data analysts. The time saved and peace of mind for professionals utilizing this service clearly defines the value of this green technology.

Geotechnical and Engineering firms, architects, surveyors, and associated professionals often need a reliable way to non-destructively locate subsurface utilities prior to drilling, trenching, or conducting site assessments and mapping. TeaCo technicians will interact with professionals to ensure every GPR survey is tailored to our client’s specific needs. The surveys can be as simple as paint on the ground, or as complex as a 3-D grid survey, with DGPS providing the capability for permanently georeferenced subsurface maps that are readily imported into powerful programs like ArcGIS or CAD. A 3-D GPR survey provides vertical data profiles along transects without the necessity of drilling test holes. In other instances, the GPR record enables project managers the ability to strategically locate test holes in order to maximize their field efforts.

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GPR provides noninvasive/non-destructive (NDT) testing to detect and identify subsurface features such as engineered drainage systems, electrical ducts, vaults and vessels. Thus, allowing planners the ability to determine spatial relationships to other non-utility targets that may have serious consequences to their project. GPR readily responds to buried metallic utility pipes, cables, and conduits; and can detect PVC, clay and concrete pipes as well. This technology has a distinct advantage when pipes are non-metallic or not easily located with traditional EM devices. In some instances a GPR survey can find utilities that conventional Subsurface Utility Engineering (SUE) might not be able to detect, while providing complete geophysical coverage of the area surveyed. In numerous instances GPR has been demonstrated to be most useful to planners in areas where no drawings or other information exist.

In addition to GPR locating, and as a way for secondary locating, TeaCo technicians use a Radiodetection RD-8000 electromagnetic (EM) locater transmitter and receiver. This system is designed to locate and detect buried conductors, metallic pipes, and lines with tracers attached.

The RD8000 is a utility locating and mapping device that is used in the field to quickly identify buried utilities. The RD8000 has 2 prime methods in which TeaCo technicians can trace the buried signals, passive and active.

Passive frequency detection takes advantage of signals that are already present on buried metallic conductors. The RD8000 supports four types of passive frequencies: power, radio, CPS (Cathodic Protection Systems) and CATV signals as these frequencies are easily detectable without the aid of the transmitter.

Active frequencies are applied direct to the pipe or cable using a transmitter. The transmitter can apply a signal using two methods: induction and direct connection.

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In induction, a transmitter is placed on the ground over or near the survey area, and an appropriate frequency is selected for utility being sought. After setting the desired frequency, it is then induced onto the utility to be delineated in the work area.

In direct connection, our field technician will connect the transmitter directly to the pipe or cable you wish to survey. This method propagates the best signal on an individual line and employs the use of lower frequencies, which can be traced for longer distances.

Knowing the location of all buried utilities on jobsites is critical information in every aspect of civil planning regardless of application. Also, the ability to differentiate between utility targets versus project scope targets is essential for initial layout and data acquisition. Having this device at our disposal allows TeaCo to respond to clients’ needs in a timelier manner, without the procurement of additional outside services.