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4.0 DISCUSSION 



The first two major objectives of the 1997-98 survey at WLIS were to document 

 the changes in bottom topography of the disposal site relative to July 1996, and assess the 

 benthic recolonization status of the new I mound and the 1996 H mound relative to two 

 reference areas, SOUTH and SW-REF (Section 4.1). The I and H mounds were surveyed 

 in both September 1997 and March 1998 to evaluate the response of the benthic 

 community, and observe changes in seasonal conditions. 



The third major objective was to identify a new potential reference area near WLIS 

 to replace 2000W (Section 4.2). The sediments at the new proposed reference area, SE- 

 REF, were characterized through a REMOTS® survey and grab sampling. Although a few 

 images from the side-scan and REMOTS® surveys suggested possible historic dredged 

 material within SE-REF boundaries, the overall side-scan and REMOTS® survey data and 

 geochemical analysis of grab samples indicated ambient sediments with acceptable, low 

 concentrations of contaminants of concern for a reference area. 



4.1 Dredged Material Monitoring at Mounds H and I 



4.1.1 Development of Contanunant Cells 



The I mound was formed during the most recent disposal activities at WLIS, over 

 the disposal location between the D and G mounds. This disposal location was selected to 

 add to a ring of disposal mounds forming a containment berm. These berms can create 

 basins for minimizing the spread of disposed sediments to optimize capping or isolation of 

 dredged sediments and maximizing volume capacity (Figure 4-1). 



To continue the formation of containment berms, dredged material may be placed to 

 the south of the G mound (1), between E and H mounds (2), and between C and E mounds 

 (3) in the future. Figure 4-1 shows a three-dimensional view of the mounds and 

 containment basins. A very large. basin area could be created with the additional placement 

 of disposal mounds to the west of the survey area at locations 4,5, and 6. The 1996 

 survey report also suggests another containment possibility in the depression just east of the 

 F mound. The containment berm would include the namral ridge of the Long Island Sound 

 moraine margin and the H and F mounds plus two disposal mounds between the H mound 

 and the naturally occurring ridge to the south (Morris 1998). 



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



