Environmental characterization with magnetics and STOLS

The application of techniques utilizing total field magnetic anomaly measurements can contribute significantly to the environmental characterization of lands contaminated with hazardous, toxic, or radioactive wastes. By addressing the correlated problem of detection and characterization of HTRW waste containers, predominantly made of ferromagnetic materials, high-density magnetics systems can be used to characterize a wide range of buried hazardous materials. Ferromagnetic materials such as iron and steel, induce an observable secondary magnetic field which can be measured and modeled to yield estimates of location, depth, and mass of the ferromagnetic objects. As a passive geophysical technique magnetics is logistically tractable, allowing for development of systems which acquire high density data over large areas. The STOL magnetics detection system was developed for this purpose, and is outfitted with seven total field magnetometers which are integrated with a differential GPS to provide 20 Hz magnetic-field measurements positioned with nominal absolute position accuracy of 30 cm. Processing of magnetic data requires the removal of the Earth´s primary field and the interpolation onto a mesh. Image processing techniques are applied to enhance and segment the data for anomaly delineation. Isolated anomalies are modeled under the point dipole assumption to produce estimates of object position, depth, and mass