31_ 



Depth difference plots with the July 1992 bathymetry display the 2.5 m high WLIS 

 G mound connected to the adjacent D and F mounds by a wide apron of material 0.25 m 

 thick (Figures 3-12 and 3-13). The 0.25 m apron surrounding the G mound extends north 

 and east to the flanks of the historic D mound. A pocket of accumulation 0.5 m thick over 

 the southern slope of the D mound may be the result of errant deposition during the 1993- 

 94 disposal season. Approximately 1,375 m^ of dredged material was released using only 

 LORAN-C TDs to guide disposal operations. However, the apparent accumulation in the 

 southeast corner of the plot corresponds to the margin of the terminal moraine and is 

 considered to be a survey artifact. 



3.2.2 REMOTS® Sediment-Profile Photography 



REMOTS® sediment-profile photography over the G mound was primarily used to 

 document benthic recolonization and track the layers of dredged material over the WLIS G 

 mound. Formed during the 1994-95 disposal season, the mound surface has been 

 undismrbed for an entire year, allowing ample time to establish a stable benthic 

 community. Complete REMOTS® results for the WLIS G mound are available in 

 Appendix C. 



3.2.2.1 Sediment Grain Size and Stratigraphy 



As with the H mound, dredged material was detected and measured at every station 

 over the WLIS G mound. Redox rebound intervals were noted in one or two replicates at 

 Stations CTR, lOOS, lOOW, 200N, and 300N over the G mound, indicating a gradual 

 reduction in available oxygen. 



Major modal grain size reported > 4 phi sediments (silts and clays) in the surface 

 and near surface layers, with a small pocket of fine sand at Station lOON (4 to 3 phi). 

 Mean camera penetration over the G mound suggested a more consolidated surface, 

 relative to the H mound. Penetration depths ranged from 10.32 cm at Station 300S to 

 17.76 cm at Station 200E, slightly shallower than the H mound (Appendix A, Table 3-2). 

 Replicate-averaged surface roughness values for the REMOTS® camera stations over the G 

 mound ranged from 0.47 cm at lOOS to 2.24 cm at lOON. As with the H mound, the 

 surface disturbances were classified as indeterminate in the majority of replicates, with 

 several replicates displaying evidence of surface roughness due to physical effects and 

 biogenic activity. 



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



