1.0 INTRODUCTION 



The New London Disposal Site (NLON) covers a one square nautical mile (nmi) area 

 and is centered at 41° 16. 100' N latitude and 72°04.600' W longitude. It is located 

 approximately 3 nmi south of Eastern Point, Groton, CT (Figure 1-1). The Disposal Area 

 Monitoring System (DAMOS) Program has monitored this disposal site since 1977. Initially, 

 monitoring was conducted in response to concerns about possible environmental impacts 

 resulting from the disposal of dredged material removed from the Thames River to 

 accommodate deep draft submarines. Subsequent surveys (with the most recent occurring 

 during June- July 1990) were initiated to monitor mound formation and stability as well as 

 benthic recolonization. Several disposal mounds currently exist at NLON as a result of past 

 and recent dredging operations from the Thames River and at other locations in the eastern 

 Long Island Sound region. 



During the 1990-1991 disposal season, 31,475 m 3 of dredged material was deposited 

 in the vicinity of the NL-TR mound at the 1990-1991 buoy location, 41° 16.428' N and 

 72°04.333' W (Figure 1-2). The NL-TR disposal mound is located in the northeast quadrant 

 of the New London disposal site at 41°16.425' N and 72°04.320' W. NL-TR was created in 

 1988 for disposal of contaminated sediment generated by dredging activities at the Thames 

 Shipyard and Repair Company. This original mound was capped with material released at 

 six different locations from 1 October 1988 to 23 January 1989. The volume of this material 

 was estimated at 59,500 m 3 based on disposal logs (SAIC 1993). The release of additional 

 cap material was recommended following a bathymetric survey of the area in February 1989 

 (SAIC 1990a). Disposal at NL-TR was resumed in March 1990, and continued through June 

 1990 (SAIC 1993). 



From 24 to 27 June 1991, SAIC conducted field operations near the NL-TR mound 

 (Figure 1-2) to provide information on the effects of the 1990-1991 disposal operations. 

 Field operations included a precision bathymetric survey, Remote Ecological Monitoring of 

 the Seafloor (REMOTS®) sediment-profile photography, sediment sampling for chemical and 

 physical analyses, and measurements of near-bottom dissolved oxygen (DO). The objectives 

 of the 1991 survey were to 



• delineate the footprint and characterize the topography of the dredged sediment 

 deposited in the vicinity of the NL-TR mound during 1990-1991 using 

 precision bathymetric and REMOTS® sediment-profile surveys. 



• assess the benthic recolonization rate at the active disposal site and monitor the 

 successional status at the inactive NL-88 mound. 



Monitoring Cruise at the New London Disposal Site, June 1991 



