Comparison of Survey Results from EM-61 and Beep Mat for UXO in Basaltic Terrain
Les P. Beard*, Jacob Sheehan*, William E. Doll, Battelle-Oak Ridge, Oak Ridge, Tennessee, U.S.A.;
Pierre Gaucher, Regis Desbiens, Instrumentation GDD, Quebec City;
Wayne Mandell, U.S. Army Environmental Center, Aberdeen, Maryland
Paper – [pdf] UXO_SAGEEP_BeepMat_LPB_2007
Site S-12 is one of several World War II era bombing targets found on the Pueblos of Laguna and Isleta in New Mexico. Magnetometry results from a low-altitude helicopter magnetometry survey at S-12 were inconclusive as to the extent and density of the ordnance debris field because underlying basalt flows created such a strong background signal. Subsequently, a team from Battelle and GDD Inc. carried out ground geophysical surveys to test the effectiveness of a geophysical instrument called Beep Mat. Beep Mat is mounted in a rugged sled and is designed to be towed over the ground or through snow. Originally developed for Canadian mineral prospecting, it has ability to distinguish
between conductive and non-conductive materials and between magnetic and non-magnetic materials. It is therefore a potentially useful instrument for UXO detection and discrimination. At Site S-12, a 100m x 50m grid was established in an area thought to be on the periphery of the bombing target. Geophysical data using EM-61, and Beep Mat were collected over the grid at one meter line spacing. Both the EM- 61 and the Beep Mat data produced similar maps showing locations of scrap and UXO, but Beep Mat anomaly peaks were randomly offset about 2m from EM-61 anomaly peaks.