A Field Evaluation Of Airborne Techniques For Detection Of Unexploded Ordnance

United States Defense Department estimates indicate that as many as 11 million acres of<br>government land in the U. S. may contain unexploded ordnance (UXO), with the cost of<br>identifying and disposing of this material estimated at nearly $500 billion. The size and<br>character of the ordnance, types of interference, vegetation, geology, and topography<br>vary from site to site. Because of size or composition, some ordnance is difficult to<br>detect with any geophysical method, even under favorable soil and cultural interference<br>conditions. For some sites, airborne methods may provide the most time and cost<br>effective means for detection of UXO. Airborne methods offer lower risk to field crews<br>from proximity to unstable ordnance, and less disturbance of sites that may be<br>environmentally sensitive.<br>Data were acquired over a test site at Edwards AFB, CA using airborne magnetic,<br>electromagnetic, multispectral and thermal sensors. Survey areas included sites where<br>trenches might occur, and a test site in which we placed deactivated ordnance, ranging in<br>size from small “bomblets” to large bombs. Magnetic data were then acquired with the<br>Aerodat HM-3 system, which consists of three cesium magnetometers within booms<br>extending to the front and sides of the helicopter, and mounted such that the helicopter<br>can be flown within 3m of the surface. Electromagnetic data were acquired with an<br>Aerodat 5 frequency coplanar induction system, deployed as a sling load from a<br>helicopter, with a sensor altitude of 15m. Surface data, acquired at selected sites,<br>provide a comparison with airborne data. Multispectral and thermal data were acquired<br>with a Daedelus AADS 1268 system. Preliminary analysis of the test data demonstrate the<br>value of airborne systems for UXO detection and provide insight into improvements that<br>might make the systems even more effective.