Special Issue on geophysics applied to detection and discrimination of unexploded ordnance

Unexploded ordnance (UXO) presents serious problems in Europe, Asia, as well as in the United States. Explosives and mines from World War I and World War II still turn up at European and Asian construction sites, backyard gardens, beaches, wildlife preserves and former military training grounds. The high rate of failure among munitions from 60-90 years ago is cited as one of the main reasons for such a high level of contamination. Apart from war activities, military training has resulted in many uncovered ordnance. It is especially true in the United States, where most UXO has resulted from decades of military training, exercises, and testing of weapons systems. Such UXO contamination prevents civilian land use, threatens public safety, and causes significant environmental concern. In light of this problem, there has been considerable interest shown by federal, state, and local authorities in UXO remediation at former U.S. Department of Defense sites. The ultimate goal of UXO remediation is to permit safe public use of contaminated lands. A Defense Science Board Task Force Report from 1998 lists some 1,500 sites, comprising approximately 15 million acres, that potentially contain UXO. The UXO-related activity for these sites consists of identifying the subareas that actually contain UXO, and then locating and removing the UXO, or fencing the hazardous areas off from the public. The criteria for clearance depend on the intended land end-use and residual hazard risk that is deemed acceptable. Success in detecting UXO depends on the ordnance's size, metal content, and depth of burial, as well as on the ability of geophysical systems to detect ordnance in the presence of metallic fragments from exploded UXO and other metal clutter