1.4 NHAV 93 



The NHAV 93 mound was developed during the 1993-94 disposal season as part of 

 a large scale confined aquatic disposal (CAD) project. The management strategy of 

 controlling the deposition of small to moderate volumes of dredged material over a ten- 

 year period resulted in the formation of a ring of disposal mounds on the CLIS seafloor. 

 Upon completion in 1992, this network of disposal mounds formed an artificial 

 containment cell capable of accepting large volumes of UDM, limiting the lateral spread of 

 the deposit, and facilitating efficient capping operations. 



In 1993, approximately 590,000 m^ of UDM dredged from the inner New Haven 

 Harbor was deposited within the containment cell and capped to a thickness of 0.5 m to 

 1.0 m by 569,000 m^ of CDM (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. In the past, CDM to UDM ratios have varied from 2:1 to 6:1 when initiating a 

 capping operation on a flat or gently sloping area of seafloor. This highly successful 

 strategy resulted in the formation of the first capped mound composed of a smaller volume 

 of CDM than the initial UDM deposit. In addition, the completed NHAV 93 mound 

 formed a distinct, broad, and flat mound complex as the project sediments merged with the 

 seven perimeter mounds (Morris and Tufts 1997). 



The development of the CLIS 94 and CLIS 95 mounds represents the continuation 

 of this successful management strategy. By constructing networks of disposal mounds with 

 small to moderate volumes of dredged material, numerous artificial containment cells will 

 be formed, and the overall site capacity can be maximized (Morris et al. 1996). The 

 development of the CLIS 94 mound begins to close a second containment cell northeast of 

 the NHAV 93 mound complex. The formation of the CLIS 95 mound southwest of the 

 historic NHAV 74 mound initiates the formation of a third artificial containment strucmre 

 to the southeast of the NHAV 93 mound complex. 



1.5 MQR Mound 



The MQR mound is an historic, discrete, capped mound composed of alternating 

 layers of UDM and CDM deposited during the 1981-82, 1982-83, and 1993-94 disposal 

 seasons. In the spring of 1982, an estimated barge volume of 42,000 m' of UDM was 

 dredged from the Mill River and placed on a relatively flat area of CLIS seafloor. The 

 UDM deposit was quickly capped with approximately 133,200 m^ of CDM removed from 

 the Quinnipiac River. During the 1982-83 disposal season, an additional 67,000 m^ of 

 UDM from Black Rock Harbor was released over the MQR mound followed by 

 400,000 m3 of CDM originating from New Haven Harbor (SAIC 1995). 



Monitoring Cruise at the Central Long Island Sound Disposal Site, July 1996 



