2002 Airborne Geophysical Survey at Pueblo of Laguna Bombing Targets, New Mexico. Revision 3

Abstract : This report describes the results of a low altitude helicopter geophysical survey performed by US Army Engineering Support Center, Huntsville (USAESCH) and Oak Ridge National Laboratory (ORNL) over areas contaminated by unexploded ordnance on Pueblo of Laguna Nation lands in April/May, 2002. The purpose of the survey was to evaluate improvements to a multi-sensor magnetometry system for ordnance detection. Surveys were carried out at four areas where the Department of Defense previously had conducted bombing exercises. These areas totaled over 1640 hectares. In addition, a 0.03 hectare calibration grid was surveyed. In two of the areas, 90 m x 350 m grids were measured with the MTADS ground magnetometer system, and anomalies were excavated. No live ordnance was found. Of a total of 576 excavated items classed as UXO fragments in areas N-09 and N-10, 432 were within a 2 m radius of aerial anomaly locations, yielding an overall find ratio (number of helicopter detections/total MTADS detections) of 75%. However, many of these undetected items may have been too small for detection by helicopter systems.