As a result of past military training and weapons-testing activities, an estimated 6 million hectares (approximately 15 million acres) of U.S. land is potentially contaminated with unexploded ordnance (UXO) and/or weapons testing- and training-related artifacts. Using current technologies, the costs associated with detection, identification, and mapping of this contamination has been estimated to be in the tens of billions of dollars. Current surface-based technologies are generally labor-intensive, slow, and expensive. The Oak Ridge Airborne Geophysical System time-domain electromagnetic (ORAGS-TEM) system is a boom-mounted EM induction system designed for mounting on rigid Kevlar and carbon fiber booms attached to the underside of a Bell 206L Long Ranger helicopter. Rigid booms allow the helicopter to fly closer to the ground, increasing system resolution and permitting precise control of receiver positions, thus allowing more accurate determination of UXO locations. The airborne system is based on a single transmitter coil and two receiver coils mounted on a rigid 12m x 3m rectangular boom structure. Ancillary equipment includes a laser altimeter and a real-time differentially corrected global positioning system (GPS) for navigation and data positioning. This configuration enables operation at a nominal flight altitude of 1 to 3 meters above ground level (AGL). The survey methodology used for this report consisted of parallel lines traversing the areas of interest so that data were collected for each flight line at nominal data spacing. The survey process concludes with data processing, analysis, interpretation, and mapping using commercial software to generate digital images depicting locations and magnitudes of anomalies that may represent UXO.
