border of the CLIS Disposal Area. It is possible that hypoxic 

 conditions previously documented in Long Island Sound by SAIC have 

 adversely affected the benthic ecosystem at these mounds. 



The MQR disposal mound continued to have one of the 

 slowest rates of benthic ecosystem recovery among the mounds at 

 CLIS, possibly the result of chemical contamination combined with 

 hypoxic effects. After a period of 13 years, the sand cap at NH- 

 74 was no longer apparent as a discrete sedimentary layer in the 

 upper 10-15 cm of sediment. At the FVP mound, there was a 

 deepening of RPD depths and a notable increase in the number of 

 Stage III organisms relative to the post-Hurricane Gloria REMOTS® 

 survey of November 1985. 



In order to maintain the statistical integrity of the 

 REMOTS® data base for the CLIS disposal site, it is recommended 

 that all future REMOTS® monitoring be based an analysis of a 

 minimum of three station replicates. Furthermore, in light of 

 evidence which suggests that seasonal hypoxia in Long Island Sound 

 may be affecting benthic conditions at the CLIS disposal site, it 

 appears imperative to add near-bottom dissolved oxygen measurements 

 to all future REMOTS® measurements and to perform hydrographic 

 profiling (CTD/DO profiles) of the water column. 



None of the sediment chemistry results exceeded NERBC 

 •Moderate 1 upper limits except for Hg in the Norwalk Center sample, 

 which was at 'High* levels. Notably, the mounds that have been 

 capped (CS-1, CS-2 , STNH-S and STNH-N) almost all showed relatively 

 low (i.e., 'Low') contaminant concentrations. The levels of most 

 of the parameters measured were either not different or 

 significantly lower than reference levels. This was true for both 

 the Top and Bottom core sections. The same was also true for the 

 additional stations sampled around the STNH-N disposal mound. This 

 suggests that the caps have been effective in isolating or at least 

 "diluting" contaminants which might have been elevated in the 

 capped dredged material. At the STNH-N mound, there was no 

 evidence to suggest that transport of contaminants from the mound 

 center to outlying stations had occurred. Also, only minor 

 differences were noted between the concentrations measured at the 

 STNH-N stations in 1986 and the results from samples collected in 

 1984 and 1982. 



Sediment contamination levels for several parameters were 

 significantly elevated compared to reference levels at the FVP, 

 MQR, CLIS-86, NH-74 and Norwalk disposal mounds. This reflects 

 the fact that contaminants were elevated in the dredged material 

 deposited at these mounds. At the new CLIS-86 mound, the 

 concentrations of several metals and PCBs were higher in 1986 

 compared to 1985, reflecting the ongoing disposal at this mound 

 involving sediment from a number of different sources. The FVP 

 mound showed elevated concentrations for most parameters in the 

 Bottom (2-10cm) sediment core sections. However, the Top sections 



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