23_ 



sediment layers. However, a deep RPD and mature Stage I benthic assemblage in this 

 replicate suggest that the surface sediments are comparable to the remainder of the CLIS 

 95 mound (Figure 3-7 A). Overall, the bendiic conditions over the entire CLIS 95 mound 

 indicate a rapid recovery as demonstrated by the photographs collected over CTR (Figure 

 3-7B). 



3.2 CLIS 94 Mound 



3.2.1 Bathymetry 



The CLIS 94 mound is readily apparent in the large 4.41 km^ survey area; 

 however, in order to focus on the smaller aspects of the disposal mound, the July 1996 

 bathymetric data were narrowed to a LO km^ analysis area. The mound is approximately 

 470 m wide at the center with a minimum depth of 16.25 m at the apex (Figure 3-8). The 

 CLIS 94 mound maintained its irregular shape, being broader and less pronounced south of 

 the apex. Depth difference plots utilizing the September 1995, 1000 m x 1000 m survey 

 over the CLIS 94 mound indicate a 0.25 to 0.5 m decrease in mound height at the apex as 

 well as several pockets of consolidation to the south (Figures 3-9 and 3-10). Comparisons 

 with the July 1994 baseline bathymetry show that the bottom feature now has a maximum 

 mound height of 2.5 m (Figures 3-11 and 3-12). 



3.2.2 REMOTS® Sediment-Proffle Photography 



REMOTS® sediment-profile photography was used to document benthic 

 recolonization over the center of the disposal mound and assess the overall recovery of the 

 dredged material deposit. Complete REMOTS® results for the disposal mound are 

 available in Appendix C. 



3.2.2.1 Sedunent Gram Size and Stratigraphy 



Dredged material was detected and measured at every station over the center of the 

 CLIS 94 mound. Dredged material was greater than camera penetration in every replicate 

 photograph. Redox rebound intervals were noted at stations 100 m south and east of the 

 center, lending further support to the observations at CLIS 95 which suggest the 

 occurrence of a recent, gradual reduction in water column DO. 



Physical REMOTS® parameters showed that the major modal grain size was 

 reported as > 4 phi (silt and clay) at most stations, indicating the deposition of 

 predominantly fine-grained dredged material with no detectable coarsening of surficial 



Monitoring Cruise at the Central Long Island Sound Disposal Site, July 1996 



