20 



attributed to the length of the tow-wire, the distance between the disposal barge and the 

 LORAN-C receiver antenna, and the direction of approach. 



3.1.2 REMOTS® Sediment-Proffle Photography 



REMOTS® sediment-profile photography was used to document benthic 

 recolonization as well as track the thin layers of dredged material and assess the overall 

 impact of dredged material deposition over the surface of the CLIS 95 mound. Complete 

 REMOTS® results for the new disposal mound are available in Appendix B. 



3.1.2.1 Sediment Gram Size and Stratigraphy 



Fresh dredged material was detected and measured at every REMOTS® station over 

 the CLIS 95 mound. The thickness of dredged material was determined to be greater than 

 camera penetration in every replicate photograph analyzed. Redox rebound intervals, areas 

 showing evidence of intermittent or seasonal oxidation below the oxidized surface layer, 

 were noted at Stations CTR, lOOE, 200S, 200W, BOOS, 300E, and 300W. The presence of 

 redox rebound intervals within a new sediment deposit suggests a recent, gradual reduction 

 in bottom water dissolved oxygen (DO) concentration as part of seasonal events in the 

 region. 



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

 reported as mostly >4 phi, indicating silts and clays in the surface layers. A fine sand 

 component (4 to 3 phi) was evident in five replicates that were scattered over the survey 

 grid. The replicate-averaged mean camera penetration ranging from 11.46 cm at lOOW to 

 18.44 cm at lOON correlated well with boundary roughness values (Appendix A, Table 3- 

 1). The lower mean camera penetration depths were generally associated with the higher 

 boundary roughness or surface dismrbance measurements. Boundary roughness ranged 

 from 0.38 cm at lOON to 1.98 cm at CTR, with the primary cause for surface roughness 

 being physical dismrbance mainly due to the recent CDM deposition. 



3.1.2.2 Benthic Community Assessment 



Three parameters were used to assess the benthic recolonization rate and overall 

 health of the project mounds relative to the CLIS reference areas. The apparent Redox 

 Potential Discontinuity (RPD) depth, infaunal successional stams, and the Organism- 

 Sediment Index (OSI) were mapped on station location plots to outline the biological 

 conditions at each station. 



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



