Polarize your subsurface, not your client relations!
Article by Moira Poje – hydroGEOPHYSICS Geoscientist
As engineering and consulting professionals, we grapple with the challenges of designing projects across unknown subsurfaces. Geologic features, visual inspections, infrastructure, and historical documents can only give us clues to what is happening beneath our feet. Geophysical tools (such as Induced Polarization) can offer inexpensive ways to quantitatively understand large areas of the subsurface.
The Induced Polarization (IP) survey method is one of the most widely used exploration techniques in the mining industry. In recent years IP investigations have been positively applied to hydrological surveys, environmental investigations and geotechnical engineering projects.
IP is a geophysical field technique used to quantify the chargeability of the subsurface. IP data are acquired by injecting current into the ground at discretely spaced electrode locations and then received voltage is measured at additional electrode locations along the surface of the earth. Chargeable subsurface particles become polarized within onset of the transmitter signal and the polarization decays overtime after the signal is shut off. IP data can be collected concurrently with resistivity data to calculate a chargeability measurement and a resistivity measurement. The combination of the two electrical measurements allow the user to discriminate features with chargeability that would not be readily apparent with a resistivity measurement alone.
IP is well suited for problems related to landfills, organic non-aqueous phase liquid (NAPL) plumes, and lithological discrimination. Fortunately, the method has been adapted to acquire high-quality field data with existing multichannel resistivity systems, so that IP data acquisition can be inexpensive, fast, and offer data-rich targeting information. HGI has experience using IP for mineral exploration, superfund site investigation and hydrogeological characterization. With the implementation of IP surveying, another tool can be added to your site characterization toolbox.
Follow the link below for more information on IP… while you’re at it connect with us on LinkedIn and friend us on FB. If you have a project where IP could benefit you or your client, call us up! We are passionate about what we do and honest with applications and limitations of geophysical technologies. Cheers!
About the Author: Moira Poje | hydroGEOPHYSICS
Moira Poje is a Staff Geoscientist with hydroGEOPHYSICS, Inc. She works on contaminant delineation, void detection projects for mine reclamation, subsurface fluid flow mapping, and depth-to-bedrock delineation via seismic, gravity, and electrical methods.
Moira has presented at the AGU Annual Meeting, Arizona Hydrological Society Annual Meeting, CUR REU symposium, and published in EEGS’s magazine FastTIMES. Moira serves on the Board of Directors for the Environmental and Engineering Geophysical Society (EEGS). Moira holds a B.A. in Geophysics and Planetary Science from Boston University.
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