Recent disposal activity has been located to take advantage of the bottom 

 topography created by historical disposal mounds. Two management objectives have been 

 sought: creation of a "bowl" by placement of mounds in a "ring"; and constraint on the 

 spread of dredged material disposed at the site. The lateral spread of dredged material 

 disposed through the water column is strongly affected by bottom slope (Bokuniewicz et al. 

 1978). By placement of the taut-wire moored disposal buoys, disposal activity can be 

 directed to specific locations and thereby limit the horizontal spread of material by filling 

 depressions or confining material between adjacent, older mounds. Minimizing lateral 

 spreading of mounds can increase site capacity and reduce the volume of material required 

 for capping. Additionally, in order to reduce the potential effects of bottom currents and 

 storm-generated waves, sediment mounds at the NLDS are developed in a broad, flat 

 manner, maintaining a minimum water depth of 14 meters. This minimum depth also 

 allows for the safe passage of deep draft Navy vessels transiting through the disposal site 

 (NUSC 1979). Presently, there are 10 discernible mounds (NL-95 is merged with the 

 Seawolf Mound) within the boundaries of the disposal site (Figure 1-2). 



The Thames River, located in southeastern Connecticut, discharges fresh water and 

 sediment from the interior of eastern Connecticut into Long Island Sound. The mile- wide 

 basin of the lower Thames River and New London Harbor is utilized by military, 

 commercial, and recreational vessels seeking protection from the open waters of Long 

 Island Sound (Figure 1-1). Maintenance dredging of New London Harbor and adjacent 

 coastal areas, overseen by the NAE, is required to insure navigable waterways and 

 adequate dockage for deep draft vessels. Most of the material generated from dredging 

 operations is transported by barge and deposited at the New London Disposal Site (NLDS) 

 in Long Island Sound. 



Disposal of dredged material occurred within and around the NLDS area for a number 

 of years before the inception of the DAMOS Program. The formation of the NL-RELIC 

 Mound was a result of dredging and disposal of sediments from the Thames River and New 

 London Harbor prior to 1977 and during the early 1980s (NUSC 1979; SAIC et al. 1985). 

 The area surrounding the NLDS is subject to moderate to high bottom currents (maximum 

 bottom current of 55 cm-s" 1 ) relative to other containment disposal sites in Long Island Sound 

 (Waddell et al. 1999). However, the shelter provided by Fisher's Island, the southern fork of 

 Long Island and the Connecticut shoreline protect the disposal site from the effects of major 

 storm waves. This inference is supported by the fact that many historic disposal mounds have 

 remained stable in both height and shape over at least ten years, and in some cases (such as 

 NL-RELIC) twenty years or more (Figure 1-2). 



Monitoring Cruise at the New London Disposal Site, 1992 - 1998 



