Approximately 75% of buried UXO cleanup costs are expended excavating false alarm anomalies (i.e., digging on the locations of geophysical anomalies that are not caused by UXO). Although probabilities of detection at documented UXO test sites are commonly > 90%, there is little documented discrimination capability. This lack of discrimination capability leads to excessively high false alarm rates for both test site and live site surveys. Despite considerable advances in quantitative interpretation methods for discrimination, the state of practice is qualitative or empirical. The UXO thrust of the Army Engineer Research and Development Center's (ERDC) Environmental Quality Technology Program seeks to develop enhanced detection and discrimination capability for geophysical surveys to locate buried UXO. ERDC and its academic partners have developed robust forward and inverse modeling capability for survey data from total field magnetometry, time-domain electromagnetic induction, and frequency-domain electromagnetic induction methods. Enhanced discrimination capability by formal geophysical inversion is demonstrated at documented test sites and live sites. A current emphasis is the development of formal inversion procedures that utilize the information content in multiple geophysical datasets. Two approaches are considered: (1) cooperative or constrained inversion; and (2) joint inversion. Cooperative inversion is the process of using inversion parameters from one dataset to constrain the inversion of other data. In true joint inversion, the target model parameters common to the forward models for each type of data are identified and the procedure seeks to recover the model parameters from all the survey data simultaneously. High-quality datasets acquired at seeded test sites at Former Fort Ord, California, demonstrate the confidence in applying these two approaches to discrimination of UXO from non-UXO targets.
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