isolate deposits of unacceptably contaminated dredged material (UDM) from the 

 environment (Fredette 1994). As a result of the operational success of the 1979 capping 

 project, many additional capped mounds have been formed at CLIS (SAIC 1995). 



From 1977 through 1983 the site management strategy at CLIS entailed the 

 formation of many independent mounds over the given area of the disposal site. Each 

 mound was monitored individually, assessing mound stability, cap thickness, benthic 

 recolonization status, etc. Although this practice was highly successful, the overall 

 capacity of the disposal site was compromised due to the unusable area between the 

 discrete sediment mounds (Morris et al. 1996). 



In 1983, a new management strategy was instituted at CLIS. Utilizing the ten-year 

 dredging cycle that exists in the central Long Island Sound region, NED managed the 

 deposition of small to moderate volumes of dredged material at CLIS to form a disposal 

 mound ring. Upon completion in 1992, this network of disposal mounds formed an 

 artificial containment cell that was capable of accepting a large volume of UDM, limiting 

 the lateral spread of the deposit, and facilitating efficient capping operations. 



The containment ring was employed during the 1993/94 disposal season as part of 

 the New Haven Harbor Capping Project. In September 1993, the NHAV buoy was placed 

 in the center of seven historic disposal mounds (41°09.122' N, 72°53.453' W) designating 

 the disposal point for approximately 590,226 m 3 of UDM dredged from the inner New 

 Haven Harbor (Figure 1-3). The UDM deposit was then capped to a thickness of 0.5 m to 

 1.0 m with an estimated barge volume of 569,287 m 3 of outer New Haven Harbor CDM, 

 forming the New Haven 1993 (NHAV 93) mound. Upon completion of disposal and 

 capping operations in March 1994, the NHAV 93 mound displayed a height of 2.5 m and 

 an overall diameter of 800 m (Figure 1-4; Morris et al. 1996). 



Due to the utilization of an artificial containment structure, the NHAV 93 mound is 

 considered a confined aquatic disposal (CAD) mound. The use of the disposal mound ring 

 significantly reduced the outward migration of the UDM mound apron relative to an 

 uncontained UDM deposit. As a result, cap material distribution was concentrated over a 

 smaller area, decreasing the total volume of CDM required to cap the inner New Haven 

 Harbor sediments (Morris et al. 1996). The completed CAD mound was found to be 

 broad, stable, adequately capped, and exhibiting a CDM to UDM ratio of 0.96:1.0 (Morris 

 and Tufts 1997). In the past, CDM to UDM ratios varied from 2:1 to 6:1 when initiating 

 a capping operation on a flat or gently sloping area of seafloor. The NHAV 93 mound 

 represents the first capped mound composed of a smaller volume of CDM than the initial 

 UDM deposit. 



Monitoring Cruise at the Central Long Island Sound Disposal Site, September 1995 



