This year our Geophysical Team used low-frequency GPR (100MHz) to locate some old mining spoils in Polk county. Spoils are primarily sand and phosphate that were discarded during initial excavation. In this case, these spoils have been on these lands since initial digging in the 1940s-1960s. The material still has value to it and some developers are taking advantage of the hidden profit by locating this material at old mining sites.
The data that we found was then correlated to aerial images from 1968.
From this process, the team was able to locate buried spoil piles and determine their maximum depths. This helps our clients relate our findings to drill logs to create confidence for new excavation locations. However, the content of the buried spoils would be subjective to the location/mining practices. The information that we find is very important to the owners of these spoil pits, this way they can excavate spoil piles and chemically separate the phosphate for use in commercial products like fertilizers.