There are over 1,000 Department of Defense (DoD) sites in the U.S. that require remediation for unexploded ordnance (UXO). The ESTCP-funded Multi-Sensor Towed Array Detection System (MTADS) has demonstrated that UXO detection rates approaching 100% can be achieved using towed sensor arrays. The U.S. Army Corps of Engineers, however, has estimated that more than 50% of the area at these sites is not amenable to survey using vehicular towed systems. In order to efficiently and economically survey all DoD areas, a portable detection and mapping system with the target detection capabilities of MTADS is required.
The three essential components of the MTADS system are sensitive, low-noise sensors; precise sensor location ability; and a state-of-the-art data analysis system. Incorporating these features, the Naval Research Laboratory developed an MTADS man-portable magnetometer system (MMS) and a man-portable electromagnetic system (EMMS). Each platform was implemented with both GPS and acoustic navigation systems to allow surveying in areas without sky view. The system hardware designs allowed the man-portable survey data to be incorporated with vehicular survey data. The data analysis system was adapted to seamlessly merge data from the vehicular platforms and the man-portable sensors.
Three demonstrations were conducted using these technologies. At the L-Range in Blossom Point, Maryland, survey results demonstrated that the MMS can provide equivalent field performance to the vehicular system and the EMMS equipment was less sensitive than the vehicular system. Upgrades and modifications were made to the systems prior to the subsequent demonstrations.
At Jefferson Proving Grounds (JPG-V) in Madison, Indiana, the MMS and the EMMS demonstrated the capability to suppress high magnetic background from geologic sources and to provide high-quality geo-referenced data. In terms of production rates and total costs, the EMMS was the best performer among the advanced technology demonstrators. It achieved an average of 1 hectare per 6.56 hours, requiring a field survey crew ranging from one to four persons. Including assessed penalties, total costs ranged from 11.4 to 27.1% lower than the other demonstrators.
During the fall of 2001, ESTCP sponsored a demonstration of hand-held and man-portable electromagnetic induction (EMI) systems on prepared sites on the island of Kaho'olawe, Hawaii. Demonstrations of the MMS and EMMS concluded that about 50% of the UXO targets were realistically detectable. Sensor noise, metallic clutter noise, and geological interferences made both the smallest shallow targets and the deeply-buried bombs and projectiles undetectable.
Assuming deployments similar to those at JPG-V, the MTADS deployment costs are about $10K per day, on site. In open areas using GPS navigation, production rates of the MMS and EMMS system are about 1.5 hectares per day. The MMS can be used with lower labor costs because it is less labor intensive to operate. Production rates would likely decrease and costs increase by a factor of 2-4 in difficult terrain or in a wooded environment.
Deployment of this system will allow the collection and analysis of high-quality magnetometer data at all DoD ranges regardless of terrain or tree cover. The integrated system will incorporate standardized operating procedures and, most importantly, quantifiable probabilities of detection. This will allow the project manager to use statistical Quality Control methods on an entire survey, while using the towed-array platforms and the new portable adjunct.