EXECUTIVE SUMMARY (continued) 



same location during the 1991-92, 1992-93, and 1993-94 disposal seasons. A total of 

 80,300 m^ of dredged material was deposited at the buoy from September 1991 through 

 May of 1994. A bathymetric survey conducted in July 1992, after the deposition of 

 38,700 m^ of sediment, determined the F mound to be 1.9 m high and approximately 

 200 m wide. 



Over the next two disposal seasons, approximately 41,600 m^ of material was added 

 to the existing F mound. The July 1996 survey found that two years of disposal activity 

 produced a 2.0 m increase in mound height and shifted the apex of the mound 

 approximately 30 m to the south. The final product of three years of dredged material 

 deposition was a sediment mound with a height of 3.0 m at the apex and an overall width 

 of approximately 250 m. Limited REMOTS® sediment-profile data collected over WLIS F 

 found a healthy benthic environment with deep RPD depths and Stage I and Stage III 

 organisms. 



The WLIS D mound was developed during the 1989-90 disposal season by the 

 deposition of approximately 185,000 m^ of material generated by seven small dredging 

 projects in New York and Connecticut waters. An initial benthic community assessment 

 documented signs of rapid recovery over the new mound. However, armual monitoring 

 efforts with REMOTS® sediment-profile photography in 1991, 1992, and 1993 detected 

 anomalous conditions over the southern flank of the WLIS D mound. Two stations, 

 D200S and D300S, were occupied during the July 1996 survey at WLIS to verify 

 improvement in benthic conditions. 



Station D300S displayed dramatic improvement with a median Organism-Sediment 

 Index (OSI) value of 8.0, attributable to deep RPDs and presence of Stage III individuals. 

 Two of the three replicate photographs collected at D200S determined that a localized 

 problem still exists within the surface sediments. However, this problem could be resolved 

 by developing a new disposal mound southwest of the WLIS G mound center. The new 

 material would cover the southern flank of the D mound and isolate this apparently small 

 patch of problematic surface sediments. 



Although determined to be feasible, subaqueous capping operations have not 

 occurred at WLIS due to concerns about impact on a thriving lobster fishery. However, 

 efficient and controlled disposal of large volumes of dredged material could easily be 

 facilitated within the disposal site. The strongly sloping terminal moraine margin present 

 in the southern region of the disposal site could be utilized as a namral ridge for the 

 development of lateral containment cells. By strategically constructing sediment mounds in 

 a semi-circular pattern north of the terminal moraine, large volumes of dredged material 

 could be confined, minimizing the development of a wide, thin apron and maximizing the 

 capacity of WLIS. 



