Wide-Area Assessment (WAA)
Wide Area Assessment is a characterization strategy using a variety of platforms to cost-effectively delineate areas where unexploded ordnance (i.e., bombs and shells, or UXO) is likely to be found on the vast munitions ranges throughout the United States. By narrowing the footprint of potential UXO locations, WAA saves times and money on conventional characterization.
Conventional detection and characterization technologies involved hand-held magnetometers operated by technicians who must slowly walk across a survey area, or using a towed array of sensors that is driven across an area. These methods can be utilized more efficiently after after high-level aircraft take high-resolution photographs to detect topographic anomalies and low-altitude helicopters (flying about three meters above the surface) delineate magnetic anomalies.
At underwater sites, high altitude aircraft are not used; rather the area is subjected to both an assessment by low-altitude helicopters and additional assessment by a marine towed arrays to detect magnetic anomalies underwater.
Limitations and Concerns
No existing technology for characterizing buried UXO achieves the 100% detection rate sought by many neighbors of military property containing UXO, though they approach that for items on or just below the surface. Wide Area Assessment is a tool that focuses on detecting areas with high concentrations of munitions, not one single target.
Data interpretation is a key to the success or failure of this technology.
Magnetic and electromagnetic detectors have diminished accuracy in highly magnetic soils. High-density magnetic clutter can make it nearly impossible to locate target areas.
Where vegetation exists or topographic anomalies exist such that aircraft or towed arrays cannot be used, handheld magnetometers must be used. Often the areas are so vast that this step does not take place.
Man-made alterations of the surface (or on the surface) may obscure detection of UXO.
Physical access to a developed site may be problematic (e.g., right of entry, fences, power lines, recreational activity).
Underwater UXO location does not have the same level of confidence. In a marine environment, the distance between the array and the targets will increase by the water depth, so only large munitions are detected at any reasonable efficiency.
The tools used in Wide Area Assessment do not replace the need for historical research.
The U.S. Department of Defense (DoD) is responsible for over 15 million acres of weapons ranges in the United States, and over 1,500 sites may require the cleanup of UXO. Wide area assessment is an advanced characterization technique.
Technology Development Status
Wide Area Assessment has been proven and is used by the DoD. The marine systems are in the pilot stage of development.
Other Resources and Demonstrations