Classification of MEC with the ALLTEM at Camp Stanley, Texas

The ALLTEM is a multi-axis electromagnetic induction system designed for unexploded ordnance UXO applications. It uses a continuous triangle-wave excitation and provides good late-time signal-to-noise ratio SNR especially for ferrous targets. Multi-axis transmitter Tx and receiver Rx systems such as ALLTEM provide a richer data set from which to invert for the target parameters required to distinguish between clutter and UXO. Inversions of field data acquired between 2006 and 2010 over the Army's UXO Standardized Test sites at the Yuma Proving Ground YPG in Arizona and at the Aberdeen Proving Ground APG in Maryland have produced reasonable and generally repeatable results for many UXO items buried at different orientations and depths. In February-March 2011 ALLTEM data was acquired at two locations on the Camp Stanley Storage Activity CSSA just north of San Antonio, Texas. Camp Stanley is used to store munitions as well as test, fire, and overhaul munitions components. Site B-20 is an open burn/open detonation OBOD area and Site B-27 consists of narrow trenches blasted into limestone containing buried range and munitions debris and possibly MEC. The processing, analysis, and classification techniques developed at the controlled environments of YPG and APG have been applied to these two "live" sites at Camp Stanley. ALLTEM data analysis includes both classical numerical inversion of data from each anomaly and clustering of the raw data by means of a self-organizing map SOM via generalized neural network algorithms. Final classification consists of an integration of both the numerical and SOM results. ?? 2011 Society of Exploration Geophysicists.