1.0 INTRODUCTION 



Subaqueous capping of dredged material disposal mounds with clean, natural 

 sediment was introduced to the Central Long Island Sound Disposal Site (CLIS) in 1979 

 with the formation of the Stamford-New Haven mounds (STNH-N and STNH-S; SAIC 

 1995). During the following 15 years, monitoring and research activities within the 

 Disposal Area Monitoring System (DAMOS) Program regarding the open water disposal 

 of dredged material have evolved, resulting in significant progress in pre-project planning 

 and the development of long-term management strategies. 



A capped sediment mound consists of an initial deposit of unacceptably 

 contaminated dredged material (UDM) that has been completely overlain by 

 uncontaminated, capping dredged material (CDM), isolating the contaminants from the 

 marine environment (Fredette 1994). Several capped mounds currently exist at CLIS, 

 seven of which (Stamford-New Haven North [STNH-N], Stamford- New Haven South 

 [STNH-S], Norwalk, Mill Quinnipiac River [MQR], Cap Site 1 [CS-1], Cap Site 2 [CS-2], 

 CLIS 86, 87, 88, Cap Site 90-1 [CS 90-1]) originated as small, independent bottom 

 feamres to simplify long-term physical, chemical, and biological monitoring operations. 

 The ratios of CDM volume to UDM volume for these historic capped mounds ranged from 

 2:1 to 11:1, contingent upon the effectiveness of disposal control and the lateral spread of 

 the initial UDM mound, and the UDM volume (SAIC 1995). 



The latest capped mound. New Haven 1993 (NHAV 93), was developed as a 

 subaqueous confined aquatic disposal (CAD) mound. A CAD mound is a capped dredged 

 material deposit developed in conjunction with artificial or natural containment measures, 

 limiting the lateral spread of the UDM apron and facilitating efficient capping operations 

 (Morris et al. 1996). The successful construction of the NHAV 93 mound represents the 

 culmination of ten years of management of CLIS by the US Army Corps of Engineers, 

 New England Division (NED). 



The Central Long Island Sound Disposal Site encompasses a 6.86 km^ area (2 rmii^) 

 and is centered at 41°08.950' N latimde and 72°52.850' W longimde. It is located 

 approximately 10.39 km (5.6 nmi) south of South End Point, East Haven, Connecticut 

 (Figure 1-1). The effects of dredged material deposition at CLIS have been monitored 

 since 1977 as part of the DAMOS Program for NED (NUSC 1979). Historically, CLIS 

 has been one of the most active disposal sites in the New England region, accepting 

 sediments dredged from New Haven, Bridgeport, Stamford, and Norwalk Harbors, as well 

 as the adjacent coastal areas. 



Monitoring Cruise at the Central Long Island Sound Disposal Site, July 1994 



