Hand-towed GPR survey and truck-towed survey
Geophysical Surveys
Conducted Worldwide by GeoModel, Inc.
Geophysical Surveys
Geophysical surveys are non-destructive methods for investigating the subsurface soil, rock, and groundwater, without digging, probing, or drilling. Geophysical surveys can be used to locate many types of buried objects. Underground storage tanks (USTs), buried drums, underground utilities, subsurface foundations, rebar in concrete, or other buried objects can be located using geophysical surveys. Soil or ground water contamination, sinkholes, and other subsidence features can also be investigated using surface and downhole geophysical surveys.
GeoModel, Inc. provides the following geophysical surveys to government agencies, private industry, commercial businesses, environmental and engineering consultants, and the general public, worldwide:
Surface Geophysical Surveys - Ground Penetrating Radar
Ground penetrating radar (GPR) is a surface geophysical survey method that creates an underground image of the subsurface. Ground penetrating radar is a fast, inexpensive technique that can locate buried objects, utilities, underground storage tanks (USTs), buried drums, grave sites, sinkholes, and other subsurface features or objects on sites used for agriculture, commercial or industrial businesses, residential developments, recreational facilities, or government installations.
Ground penetrating radar can see through concrete and rebar to locate underground storage tanks or buried pipes. Ground penetrating radar data collection is now computerized, and the GPR profiles can be printed out in color.
State-of-the-art ground penetrating radar equipment is compact and portable, and can be taken anywhere in the world to rapidly locate or define objects or features underground or behind structures.
A GPR survey can be conducted over the entire area of site characterization or only in those areas where a previous EM survey showed anomalous conditions. The GPR survey shows cross sectional information in pictorial form. The pictures and image below show how a GPR survey is conducted and the results that can be obtained.
Hand-towed GPR survey and truck-towed survey
(Click on GPR images to enlarge)
For more information about the geophysical survey method of ground penetrating radar Click Here
Surface Geophysical Surveys - Electromagnetic Conductivity
Another type of geophysical survey is an electromagnetic conductivity (EM) or terrain conductivity survey. An EM survey can be conducted very quickly and a map showing high or low conductivity areas (possible contamination) and areas of buried metal are quickly determined. The pictures and map below show how an EM survey is conducted and the results that are obtained.
Various EM instruments used by GeoModel, Inc. are shown above.
GeoModel, Inc. uses the new EM metal detector which is twice as accurate as the standard EM metal detector.
EM Survey
Extent of plume
For more information about the geophysical survey method of electromagnetic conductivity Click Here
Surface Geophysical Surveys - Surface Resistivity
Surface resistivity is another non-destructive geophysical survey method used to investigate subsurface conditions. Surface resistivity can produce a very detailed image of the subsurface to substantial depths even in clayey soils. The picture and image below show the resistivity equipment and the results that can be obtained.
Application of the surface resistivity method requires that an electrical current be injected into the ground by surface electrodes. The resulting potential field (voltage) is measured at the surface by a voltmeter between electrodes.
The apparent resistivity of the subsurface materials can be calculated by knowing the electrode spacing, geometry of the electrode positions, applied current, and measured voltage. The apparent resistivity values are entered into a computer program that calculates the geoelectric sections or columns for each sounding location, as shown in the images below. Surface resistivity measurements are reported in units of ohm-meters or ohm-feet.
The depth of the resistivity measurement is related to the spacings of the electrodes and may vary depending on the subsurface conditions. The surface resistivity unit has a self-contained transmitter, capable of obtaining data to about 50 to 100 meters (160 to 300 feet), using self-contained, rechargeable batteries.
For more information about the geophysical survey method of surface resistivity Click Here
Company Background
GeoModel, Inc. was established in 1991 to provide Geophysical Surveys and Geophysical Consulting services. GeoModel, Inc. has conducted geophysical surveys throughout the United States and the world. GeoModel, Inc. geophysical consultants have advanced degrees in the geological sciences, and have over 50 years of combined experience in conducting and supervising surface and downhole geophysical surveys.
GeoModel, Inc. conducts surveys in every state.
Contact us to check the availability of a crew in your state.
Click on your state below:
Click here for worldwide surveys
e-mail: geomodel@geomodel.com
[Back to Top of Page]