Survey & Soil Investigation

Underground Utility Survey

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Underground Utility Survey

Capital Surveys uses the latest techniques for identifying the underground utility obstruction. We have qualified Geophysicist & Surveyors with vast experience in this field. The techniques used to determine the subsurface utility is Ground Penetrating Radar Method & Radio Detector Method.

GPR uses high frequency electromagnetic waves to acquire subsurface information. Energy is radiated downward into the ground from a transmitter and is reflected back to a receiving antenna. The reflected signals are recorded and produce a continuous cross sectional or profile of shallow subsurface conditions. Reflections of the radar wave occur where there is a change in the dielectric constant or electrical conductivity between two materials. Changes in conductivity and in dielectric properties are associated with natural hydrogeologic conditions such as bedding, cementation, moisture, clay content, voids and fractures. Large changes in dielectric properties often exist between geologic materials and man-made structures such as buried utilities or tanks.

The Radio Detection instruments are used to point the subsurface utility accurately. For the most reliable determination of position, the optimum method is to clamp the Frequency Unit on to an exposed pipe or cable whereby signals then transmitted along the utility and can be detected by receiving unit. A maximum signal is returned when the instrument is located directly over the conductor and this position or series of positions can then be marked on the ground. These positions can then be rapidly coordinated using either tachometric observations (total station) or kinematic observations (GPS) and the data recorded and downloaded for computation and production of drawing files.