EXECUTIVE SUMMARY 



Dredging of the New Haven Harbor Channel and five private marine terminals 

 occurred between October 1993 and February 1994. These projects involved removal of an 

 estimated barge volume of 500,000 m 3 of unacceptably contaminated dredged material 

 (UDM) from the inner portion of the federal channel and about 90,000 m 3 from the five 

 private terminals. The UDM was approved for open water disposal and sediment capping at 

 the Central Long Island Sound Disposal Site (CLIS). A total barge volume of 569,000 m 3 

 (506,000 m 3 federal and 63,000 m 3 private) of cap dredged material (CDM) was used to 

 establish a sediment cap over the UDM deposit. 



A taut- wired, moored Disposal Area Monitoring System (DAMOS) disposal buoy 

 "NHAV" was deployed in the center of a basin-like feature created by a ring of seven 

 historic disposal mounds. The ring of mounds, which required ten years to construct, would 

 serve as a lateral containment measure, limiting the spread of the initial UDM deposit and 

 facilitating efficient capping operations. Deposition of UDM from the federal project was 

 completed at the NHAV buoy, while the privately dredged UDM was disposed at a point to 

 the southwest of the buoy. Capping material was placed at various points surrounding the 

 NHAV buoy to ensure sufficient coverage of the UDM mound. The end result of disposal 

 activity at CLIS was the development of a flat, stable, confined aquatic disposal (CAD) 

 mound. 



The decision to cap the material was based on the results of the Ampelisca bioassay 

 test using the sediments sampled from the federal channel project. Biological testing of the 

 private marine terminal projects was not pursued due to a cooperative plan for capping both 

 the federal and private projects, providing a cost-efficient method of disposal. 



Science Applications International Corporation (SAIC) completed five precision 

 bathymetric surveys (baseline, interim disposal, precap, interim cap, and postcap), two 

 Remote Monitoring of the Seafloor (REMOTS®) surveys, and three geotechnical coring 

 surveys of the NHAV 93 mound. The strategic repetition of survey activity over the NHAV 

 93 mound has given SAIC and NED an excellent perspective on CAD mound development 

 and insight toward the disposal and oceanographic processes that affect the bottom feature. 

 The bathymetric data provided "snapshots" of the developing mounds, allowing time-series 

 comparisons of the various stages of CAD mound construction. The REMOTS® photographs 

 were used to determine the relative shear strength of the containment ring as well as the areal 

 extent of the UDM deposit. Geotechnical cores and grab samples were used to define the 

 physical characteristics, document the bulk density, and estimate the consolidation of the 

 NHAV 93 mound. 



