Handheld Sensor for UXO Discrimination:

Abstract

Abstract : As a result of past military training and weapons-testing activities, UXO is present at sites designated for Base Realignment and Closure (BRAC) and at Formerly Used Defense Sites (FUDS). Current estimates indicate that over 11 million acres of land potentially contain UXO. Using current technologies, the cost of identifying and disposing of UXO in the United States is estimated to be in the billions of dollars. Current technology has shown improvements in our ability to detect sub-surface UXO but is unable to reliably discriminate UXO from other items that pose no risk. Current remediation approaches are labor intensive, slow, and expensive. The goal of this project is to demonstrate that, with the right post-processing of the sensor output, a simple, commercially available handheld sensor (Geonics EM61-HH metal detector) can be used to discriminate between buried UXO and subsurface clutter. For several years now, with SERDP and ESTCP funding, AETC has been developing advanced processing techniques for discriminating between UXO and clutter using magnetic and electromagnetic induction (EMI) sensors. For EMI sensors, our approach [1] is based on estimating the magnetic polarizability tensor [2,3] of an unknown buried object from data collected above the ground. The eigenvalues of the magnetic polarizability tensor are determined by the size and shape of the object, and can be used effectively in discriminating between UXO and clutter. The basic idea is to collect data at a set of known positions over a target using the EM61-HH and its data recorder. After a number of targets have been interrogated in this manner, the data is downloaded to a notebook computer and fed into a program that determines the polarizability eigenvalues. A set of predetermined decision rules is then used to classify the target as either UXO or clutter. We have used this procedure successfully with precisely positioned array data and with data collected on a fixed grid.