successional condition observed at STNH-N was not apparent at 

 STNH-S. This may be an artifact of the relatively small sample 

 sizes of these post-storm mound surveys. 



The post-storm Organism-Sediment Index values for STNH-S 

 (Figure 3-33) did not change significantly between August and 

 November (Mann-Whitney U-test, p = 0.5213). There was no clear 

 difference in the OSI values from on and off the disposal mound. 

 The distribution of OSI values continued to indicate a patchy and 

 relatively disturbed benthic environment. The lack of significant 

 change due to Hurricane Gloria may be related to the mound's 

 relatively "disturbed" pre-storm condition. 



3.3.3 Cap Sites One and Two (CS-1 and CS-2) 



August Survey 



These two experimental capping locations are located on 

 the western edge of the Central Long Island Sound disposal site. 

 A baseline REMOTS® survey was completed in April 1983. In May 

 1983, Black Rock harbor sediment was barged to these two locations, 

 and two disposal mounds were produced. CS-1 was capped with silt- 

 clay material, while CS-2 was covered with sand. A post-disposal 

 reconnaissance REMOTS® survey was conducted in June 198 3 to map the 

 dispersal of the dredged material and the thickness of capping 

 materials. Subsequent REMOTS® surveys were conducted in August 

 1983 and September 1984. In August 1985, these mounds were again 

 surveyed (Figures 3-34 and 3-35) . 



CS-1 stations showed a major textural mode at >4 phi 

 (silt-clay) , with a range of >4-3 phi (silt to very fine sand) at 

 all stations; the only exception was station 600N which had a major 

 mode of 4-3 phi (very fine to fine sand) . This station was 

 apparently located on the southern flank of the sand cap placed on 

 CS-2 (lOOS) . The sediment grain-size major mode and range for CS- 

 1 stations had not changed since the August 1983 survey. 



The sand cap at CS-2 initially consisted predominantly 

 of 4-3 phi material. In the last REMOTS® survey (September, 1984), 

 the sand was still apparent but it appeared to be partially covered 

 with silt-clay (>4 phi) . The burial and admixture of the sand with 

 mud was attributed both to bioturbation (bringing underlying Black 

 Rock material upward from below) and to the deposition of 

 fine-grained sediments- and detritus from the water column. This 

 survey found that these processes were continuing. A distinct 

 surface sand cap was not apparent at most stations. Many images 

 revealed a major grain-size mode of >4 phi (silt-clay) . Two 

 replicates from station 200W showed silt-clay layers 4.5 and 6.5 

 cm thick overlying the original sand cap (Figure 3-36) . This would 

 have represented a net sedimentation rate of 2 to 3 cm/yr (June 

 1983 to August 1985; a period of 26 months). This high 

 sedimentation rate may have been specific to the western side of 



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