Subaqueous Capping Demonstration Project at the Massachusetts Bay Disposal Site

The overall objective of the MBDS capping demonstration project was to evaluate the effectiveness of subaqueous capping as a dredged material management technique at this deep-water disposal site. A series of monitoring surveys employing precision bathymetry, side-scan sonar, sediment-profile photography, and multiple sediment collection techniques were performed over the study area to track the development of the capped mound. The comprehensive data set documented the development of a capped mound composed of two distinct layers of sediment on the MBDS seafloor. This paper will discuss the success of the demonstration project, a recommended approach for future deep-water capping projects, and the value of firm, cohesive glacio-marine clay as a capping/armoring deposit.