A Metal Detector Study to Locate Inactive Small Arms Range Impact Areas

Abstract

Historical records suggested the existence of .45 caliber Thompson sub-machine gun ranges near the Fort Lewis Evergreen Range; however, the precise location of the bullet impact area was not known. The site covered 20 acres, too large to cost-effectively characterize using convention grid sampling techniques. As an alternative, a study was conducted using a hand-held metal detector to locate the bullet impact areas. The metal detector chosen, a Garrett Graphic Target Imaging™ (GTI) 2500, has an LCD screen, which provides the user information on the potential size and depth of the object causing the signal. A two-man team performed the study and bullet detection was confirmed by excavation. The metal detector proved effective at finding .45 caliber bullets. Three impact areas were successfully identified and marked using a global positioning system (GPS). The metal detecting strategy saved substantial sampling time and over $35,000.00 by decreasing the sampling area by 93 percent.