GeoView, Inc. performed a geophysical investigation across a 200 acre site in Polk County, Florida. It had been reported that clay slimes from former mining operations had been deposited on the site. The purpose of the investigation was to help determine the horizontal and vertical extent of the clay slimes. Due to the large size of the site and limited budget, the investigation was conducted using Frequency Domain Electromagnetics (EM).
The EM Survey was conducted by towing the EM-31 on a proprietary non-conductive sled on transects spaced 100-ft apart. The data was electronically recorded and positioning was recorded using an integrated GPS system.
Initial contour maps of the EM response clearly showed the lateral extent of the slimes. A total of 31 shallow borings were performed to calibrate and verify EM data. Based on the boring results, an algorithm was designed to calculate slime thickness based on the EM data. A site wide contour map was then able to be produced showing the thickness of the clay slimes. The results proved to be within a +/- 1 foot margin of error.