The U.S. Naval Research Laboratory (NRL) and Science Applications International Corporation (SAIC) have participated in several programs funded by SERDP and ESTCP, whose goal has been to enhance the classification ability of the Multi-sensor Towed Array Detection System (MTADS). The Time-domain Electromagnetic MTADS (TEMTADS) 5x5 Array incorporated an advanced electromagnetic induction (EMI) sensor specifically designed for unexploded ordnance (UXO) classification.

The team further undertook efforts to transition this successful technology to smaller, man-portable (MP) and hand-held systems for deployment in more confined terrains. The MP System was constructed as a 2x2 Array of upgraded sensors based on those from the original TEMTADS, but with tri-axial receiver cubes in place of the original single, vertical receiver loops. The MP System was designed to be deployable in increasingly inaccessible areas where vehicle-towed sensor Arrays cannot be used.

The objective of this project was to validate the performance of the 5x5 Array and MP System in blind demonstrations conducted at live munitions response (MR) sites. Performance metrics include production rate as well as accuracy and variability of extracted target parameters. Based on the success of the MP System as a cued sensor, an effort was made to operate the system in a dynamic, or survey, mode at one demonstration. Operating as such allows for the collection of anomaly detection data and more excitingly, the potential for classification based on the dynamic data for a significant portion of the detected anomalies. This mode of operation could dramatically improve the efficiency and accuracy of UXO classification efforts and therefore save money during UXO remediation efforts.

Two types of advanced EMI sensors were used in this demonstration. The first is the EMI sensor developed for the 5x5 Array, consisting of a single transmitter loop coaxially located with a single vertical-axis receiver loop. The transmit (Tx) coil is wound around the outer portion of the form and is 35 cm on a side. The receive coil is wound around the inner part of the form, which is re-inserted into the outer portion, and is 25 cm on a side.

The second is the ‘TEMTADS/3D’ sensor in which the same transmitter coil is used but the receiver coil is replaced by an 8-cm, 3-component ‘cube’ receiver that was first developed by G&G Sciences under a Navy-funded project known as the Advanced Ordnance Locator (AOL). NRL has developed systems made from multiple copies of these sensors, assembled in a variety of Array configurations. Minor modifications were made to the AOL control and data acquisition infrastructure to make it compatible with this project’s deployment schemes.

The 5x5 Array was demonstrated at two sites, the former Mare Island Naval Shipyard, California (fMINSY) in 2011, and the former Spencer Artillery Range, Tennessee (fSpAR) in 2012. The MP System was demonstrated at the former Camp Beale, California in 2011, and the Central Impact Area of the Massachusetts Military Reservation and fSpAR in 2012. With the exception of a small area at fSpAR, all data collection was done in cued mode. For each site and system, 180 or more target locations were investigated per day with limited rework required. Based on Instrument Verification Strip (IVS) results, the accuracy and variability of fit locations and target parameters were well within the requirements for conducting UXO/Clutter classification. The limited data set of dynamic data collected with the MP System at fSpAR was used to ultimately detect all seed items within the area. Approximately 70% of the detected anomalies could be classified from the dynamic data alone. Using a combination of results from dynamic and cued data, 100% of the identified UXO were correctly classified and the number of necessary digs could be reduced by at least 75%.

This project demonstrated high-quality data collection with an advanced EMI sensor to support UXO/Clutter classification decisions. The introduction of a second generation of advanced sensors that focused on being practical field instruments was part of this effort. These systems are designed to be used in rugged/restrictive terrain by industrial community members, which aids in the transition of these technologies from research prototypes to use in the industrial community. The mechanics of collecting classification-grade advanced EMI cued data with these systems have been shown to be fairly routine in the research community. As part of the ESTCP Live Site demonstrations, industrial partners have been exposed to the MP System and the associated data collection and processing procedures. The success of this effort will be evaluated on an ongoing basis through the Live Site demonstrations. In the past, analysis of data from these systems has been somewhat of a specialty, requiring specific software and knowledge to proficiently conduct. The successful transition of the processing and analysis procedures for MP data to the Geosoft Oasis montaj environment provides a clear pathway forward.