Evaluation Of Improved Airborne Techniques For Detection Of Uxo

Recent development of helicopter boom-mounted magnetic detection systems (Gamey and<br>Mahler, 1999) have made it possible to detect much smaller objects than could be detected with<br>conventional towed systems. Data acquired with the HM3TM system in June 1999 at the<br>Badlands Bombing Range (BBR) in South Dakota indicate sensitivity to ordnance and buried<br>metals that have a mass of less than 1Okg. This is significantly better than was observed in an<br>earlier test with the HM3TM system at Edwards Air Force Base (EAFB) in California (Doll et. al.,<br>1999). This paper presents an overview of the project and initial results.<br>Data were acquired in six areas at BBR. These included two trench areas, two bombing targets,<br>a controlled test site, and an undiscovered bombing target. The first two bombing targets had<br>previously been surveyed with the MTADS system (McDonald and Robertson, 1996). The third<br>bombing target was discovered in the course of a blind survey of a “clean” part of the range.<br>The controlled test site consisted of 24 holes in which deactivated ordnance, fragments of<br>ordnance, simulants, plumbing pipes, and known metallic objects (e.g. segments of reinforcing<br>rods and I-beams) were placed at depths ranging from 0 to lm. The smallest objects at the test<br>site were approximately 5kg.<br>The improved sensitivity at BBR is attributed to: 1) higher data sampling rates, 2) elimination of<br>a low pass filter that was used at EAFB, 3) improved techniques for removal of geologic noise,<br>4) lower instrument altitude in flatter terrain, and 5) more favorable geologic background<br>conditions. These results indicate that airborne magnetic methods are an appropriate tool for<br>detection of ordnance, and for screening or characterizing large areas of suspected<br>contamination. This is particularly true at sites where low survey altitudes are possible,<br>background geologic response is low, and expected target size is within range.