There may be as many as 1 million acres of potentially unexploded ordnance (UXO)-contaminated lands underwater and in wetland environments. Recovery of underwater UXO targets is several times more expensive than excavating the same targets on land. Thus, both detection and discrimination are crucial components of any underwater search technology. Commercially deployed vehicular or man-portable UXO search systems show direct applicability only for dryland operation in areas that can be routinely traversed. Development and deployment of the Airborne Multi-Sensor Towed Array Detection System (MTADS) magnetometer arrays has demonstrated that these sensors deployed 1 to 2 meters above the surface can detect and identify individual UXO targets equivalent to or larger than 105-mm projectiles. Deploying sensor arrays in the water, 1 to 2 meters above the bottom sediments, will require the use of both magnetometer and electromagnetic induction (EMI) arrays to detect all UXO targets larger than or equal to 60-mm mortars. However, several scientific and engineering challenges must be met before deployment.

The objective of this project was to develop new sensor array platforms and deployment techniques that will support integrated magnetometer/electromagnetic search technologies in a robust and versatile underwater search system to both detect and discriminate shallow-buried UXO.

Many system components developed for the Airborne MTADS could be directly adapted for the Marine MTADS platforms. These included the data acquisition and pilot guidance systems, the magnetometer sensors, the navigation control and attitude sensors, the data analysis algorithms and software Graphical User Interface, and the output graphics, interfaces, and remediation support documentation. In this project, a study was completed to define the support vessel (i.e., deployment concept) and develop engineering design plans for the vessel-sensor platform interface and the sensor array platform. Additionally, an EMI modeling study was undertaken to develop the engineering design plans for the new marine EMI array and define the high-frequency sonar system required to support the marine UXO survey system.

The project team carried out a marine engineering study of vessel parameters and sensor platform concepts and established designs for towed sensor platforms at varying widths. In addition, researchers completed EMI modeling studies and parametric measurement studies with inert ordnance and established a working design for a time-domain EMI transmitter-receiver system that they predicted could be used to detect a 60-mm mortar from a stand-off distance of 1 meter. It was concluded that both magnetometers and an EMI sensor array could be housed in the same sensor platform. Although they could not be operated simultaneously, each could be independently used without interference from the other system.

This project produced the engineering design informationnecessary to develop and deploy a fully functional marine UXO search system appropriate for the shallow-water environment. The concepts have transitioned to ESTCP project MR-200324 where investigators have built the underwater UXO search system and are conducting demonstration surveys in multiple shallow water sites. (Project Completed – 2003)