Integrated Methods for Marine Munitions Site Characterization: Technical Approaches and Recent Site Investigations

Abstract

Investigation and remediation of munitions and explosives of concern (MEC) at marine sites are both time consuming and expensive. MEC assessment in marine environments has additional challenges compared to terrestrial sites, including the high cost of marine operations, the general absence of surface sweeps prior to geophysical assessments, the difficulty of quick or effective site reconnaissance activities, and high levels of clutter in ports, harbors, and bays. Consequently, a high payoff exists for effective methods of feature extraction and data fusion for improved assessment in marine settings. Recent site investigations have pointed to the potential of utilizing innovative geophysical sensing and new methods that directly link MEC experts to enabling technologies. We present two case studies to highlight the benefits of combining various technologies to provide the information needed for comprehensive munitions site characterization. This approach has been successful for both time-critical response activities and longer-term remedial investigations.

Efficient Underwater Site Characterization Using a Layered and Integrated Technology Approach

“…(Schultz et al, 2011). The SSS technology is used to characterize swaths of the seafloor and determine sediment conditions.…”

“…This information is initially collected for three purposes: (1) as a list of possible targets or clusters of targets requiring evaluation, (2) for object avoidance during subsequent investigations, and (3) to attempt to quantify the density of various types of debris proud of the surface to support an assessment of the general condition of the seafloor for use in future investigation actions (Schultz et al, 2011). Acoustic surveys in large, very high clutter port environments are primarily useful as a site characterization tool and not for locating and selecting small individual targets (due to the excessive dumping of debris typical in harbor sites), although these data remain effective for individual small target selection in low debris density environments and for locating clusters of targets (e.g.…”

“…dump sites) in high debris density areas. Geo-referenced acoustic maps also serve as a geographical information system (GIS) layer used by ROV teams during targeted visual surveys (Schultz et al, 2011), and are co-registered with underwater digital geophysical mapping (DGM) data to ensure that acoustic surface anomalies selected for reacquisition possess an appropriate geophysical signature correlated to the size of the object and to the items of interest present at the site. Displaying current ROV positioning information on top of the acoustic layer also allows the ROV operator to navigate directly to a target for verification.…”

“…Boston, MA USA http://www.eegs.org Sub-bottom profiling (SBP) sonar is utilized to map sediment conditions across the site (Schultz et al, 2011). Data are useable in characterizing sediment layers and locating points of transition between layers of differing consistency.…”

“…This DGM system (Figure 4) is able to survey underwater sites down approximately 100 feet. This system is proven capable of accurately positioning anomalies to within 25 centimeters (Schultz et al, 2011). It is a towed magnetometer-based system, oftentimes superior for mapping in open environments to electromagnetic (EM) arrays.…”