Electrical resistivity surveys frequently use a Super Sting/Swift resistivity instrument system. A dipole-dipole array with 84 programmable electrodes at an appropriate spacing for the detection of the desired target is laid out on the ground surface. Parallel traverses are conducted at an appropriate spacing.
The objective of an electrical resistivity survey is to map the subsurface distribution of electrical resistivity by means of injection of DC current in the ground and by measuring the voltage drops produced at points on the surface or in boreholes.
Electrical resistivity surveys are utilized to evaluate:
Electrical resistivity values are digitally recorded on the Sting meter and processed using specialized software to build a three-dimensional model of a site which can be used to evaluate existing void spaces, depth of conductive materials, and approximate volumes of conductive objects within the subsurface soils. Topographic elevations are used to make any needed topographic corrections to the collected resistivity data.
Electrical resistivity imaging uses an automated switching system linked to a resistivity instrument and multiple electrodes. Depth sounding involves digital computer controlled current electrodes and potential electrodes expanding out from a common midpoint. As the electrode pairs are expanded farther apart, deeper measurements of apparent resistivity are recorded. The system is capable of producing resistivity profiles over 500 feet long with a depth of evaluation of up to about 100 feet below the ground surface.
Ninyo & Moore was retained to provide technical services for a project known as Tempe Marketplace, including geophysical surveys, geotechnical soil borings, soil test pits, geotechnical laboratory testing, environmental sampling, reporting, and contractor observation including ground vibration monitoring during our geotechnical site evaluation and the contractor's...