GEOPHYSICAL SURVEYING
GEO utilizes Electromagnetic Conductivity (EM) and Ground Penetrating Radar (GPR) methods to conduct geophysical surveying. EM responds to variations in the conductivity of the subsurface, and is a rapid and accurate technique. The EM methodology is good for locating buried metallic objects, landfills, shallow contaminated groundwater, and clay units. GPR can be utilized to locate a wide variety of subsurface features at various resolutions and depths, including rebar in concrete, underground storage tanks, sinkholes, depth to bedrock, and unmarked graves
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Potential uses of geophysical surveying include the following:
- Construction site planning
- Inspection of infrastructure (roads, levees, dams)
- Locating subsurface utility lines
- Locating unmarked graves in cemeteries
- Identifying buried debris or underground structures (storage tanks or buildings)
- Subsurface characterization and supplementation of borehole logging
- Non-aqueous phase liquid contaminant delineation and mapping
- Identifying natural resources
In response to an urgent call at a construction site, GEO teamed with Battelle Memorial Institute to identify buried debris (immediately under the proposed building footprint to a depth of 20 feet) as being three times larger than anticipated. With this information, the client was able to modify the construction plans prior to pouring building foundations, which saved the client millions of dollars.
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GEO again teamed with Battelle Memorial Institute to conduct an airborne geophysical investigation of a levee system. The objective of this project was two-fold: 1) to demonstrate the capabilities and usefulness of a newly-configured helicopter-mounted geophysical survey system that is far more agile than the traditional “towed-bird” configuration, collecting over 225 readings per second; and 2) to obtain subsurface lithology data (specifically soil thickness and type), as well as map paleochannels, seepage zones, and hidden levee weaknesses that should enable the client to identify areas in greatest need of further investigation or remediation. |