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3.0 RESULTS 



To monitor changes in the topography and benthic conditions at WLIS, we surveyed 

 the southwest quadrant of the disposal site (Figure 2-4) where all disposal activity has 

 occurred since 1982 (Section 3.1). The WLIS disposal mounds have been strategically 

 placed to form potential containment cells. The REMOTS® surveys were focused over the 

 recently deposited I mound (Section 3.2), the 1995-1996 H mound (Section 3.3), and the 

 reference areas South and SW-REF (Section 3.4). In addition to the development of 

 containment basins, the I mound was placed between the D and G mounds to cover an area 

 exhibiting low dissolved oxygen conditions and poor recolonization in the 1996 REMOTS® 

 monitoring survey (Morris 1998). 



For the new reference area investigation, using a high-resolution side-scan sonar 

 survey, we located a region identified as SE-REF that appeared to be free of historic 

 dredged material deposits. We also conducted a REMOTS® photography survey to 

 characterize the ambient material and confirm that no dredged material was in the 300-m 

 radius of the center of the reference area (Section 3.5). The ambient sediments had a high 

 sulfide content and were in many cases darker than typical reference areas. However, 

 determination of the contaminant levels in sediment grab samples revealed moderate to low 

 pollution levels similar to ambient sediment conditions of western Long Island Sound. 



3.1 WLIS Disposal Site Bathymetry 



The September 1997 800 x 800 m bathy metric survey at WLIS detected eight 

 dredged material disposal mounds on the WLIS seafloor (Figure 3-1). The I mound is a 

 result of the most recent deposition. There are a total of nine mounds in the southwest 

 quadrant, including the 1995-1996 H mound which is located to the east of the survey 

 area. Depths in the survey area ranged from 27 m to 35 m. The minimum depth occurred 

 over the southern edge of the survey area, which continues to shoal towards the south to 

 form the terminal moraine of Long Island. This namral containment wall, created by 

 glacial deposition, combined with the strategic placement of the dredged material mounds 

 has resulted in the formation of several basin areas that may serve as potential containment 

 cells for dredged material in the future. 



3.2 WLIS I Mound 



To continue the development of the dredged material containment berm and basins, 

 material was disposed between the existing D and G mounds. The buoy was positioned at 

 40° 59.203' N, 73° 29.072' W, where approximately 35,000 m^ of new dredged sediments 

 over the disposal season were placed, forming the I disposal mound. 

 Monitoring, Cruise at the WLIS Disposal Site, September 1997 and March 1998 



