EXECUTIVE SUMMARY (continued) 



The CLIS 94 mound, developed during the 1994-95 disposal season, is also an example of 

 a capped mound. Approximately 129,000 m^ of UDM and 161,000 m' of CDM were 

 placed at the CDA 94 buoy to form an irregular-shaped, moderate-sized disposal mound 

 630 m northeast of the NHAV 93 mound apex. Field operations over this bottom feature 

 were conducted to observe changes in bathymetry due to consolidation, as well as to 

 confirm the continued stability of the benthic infaunal community. 



Depth difference calculations indicated the presence of several pockets of 

 consolidation over the surface of the CLIS 94 mound. A 0.25 m to 0.5 m decrease in 

 mound height was discovered at the mound apex, while smaller cells of consolidation were 

 detected over the broader southern region of the mound. The five REMOTS® stations 

 occupied over the center of CLIS 94 displayed some improvement relative to the conditions 

 found during the September 1995 survey. A healthy Stage I on III benthic assemblage and 

 deeper RPD depths over the center of CLIS 94 indicate higher dissolved oxygen (DO) 

 concentrations and continued benthic recovery. 



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. 



SAIC has conducted a total of eight bathymetric and five REMOTS® sediment- 

 profile photography surveys over the NHAV 93 mound since September 1993. This latest 

 field effort adds to the comprehensive time-series data set that currently exists for the 

 2.56 km^ area of CLIS seafloor. At 2.5 years after the completion of capping operations, 

 the July 1996 survey has shown 0.25 m to 0.75 m of consolidation over the majority of the 

 mound with little change in size or shape. The results of the REMOTS® sediment-profile 

 photography survey indicate the benthic community is continuing to recover as expected. 



The MQR mound is a historic bottom feature formed along the southern boundary 

 of CLIS. This capped sediment mound is actually composed of alternating layers of UDM 

 and CDM deposited during the 1981-82, 1982-83, and 1993-94 disposal seasons. 

 Approximately 65,000 m^ of additional CDM was deposited over the MQR mound during 

 the 1993-94 disposal season in response to anomalous REMOTS® sediment-profile 



