decrease the depths at the disposal location within the detection 

 limits of the acoustic fathometer system (~10-15 cm) . 



No significant trends could be found in the sediment 

 chemistry data beyond the sampling and analytical variability. The 

 CLIS-SE results were compared to averages and ranges of selected 

 chemical concentrations for the CLIS reference station (CLIS-REF) 

 over a five year period to see if CLIS-SE chemical concentrations 

 represented values for natural bottom. The CLIS-SE data are within 

 the ranges for CLIS-REF except for oil and grease (Table 4-1) . The 

 August 1985 oil and grease results (x = 540 ppm) for CLIS-REF were 

 also higher than normal. If dredged material was present, metal 

 concentrations would be expected to be higher as well. No sediment 

 samples collected during the October field operations were 

 analyzed. 



The results of the benthic community analysis of the 

 samples collected at the stations in the CLIS-SE area were 

 generally very similar to one another as well as to CLIS-REF. Some 

 differences did exist in the abundances of some polychaetes (low 

 numbers of Cgssura, Mediomastus . Spio , and Tharvx at CLIS-REF) but 

 this was likely due to the higher water content sediment at CLIS- 

 REF. At CLIS-SE, the occurrence of the bivalves Mulinia lateralis 

 and Macoma tenta and the polychaete Mediomastus ambiseta was well 

 below the maximum levels that can be expected here, while Nephtys , 

 Nucula, and Yoldia were more abundant and occupied a deeper, more 

 physically stable habitat. The transition from the former group 

 to the latter might be interpreted as a response to a change in 

 habitat quality or disturbance level. Recent studies at the FVP 

 site by EPA/COE, however, suggest that this transition may be an 

 irregular cycle in relative abundance of these two groups and not 

 related to habitat changes. 



Analysis of REMOTS® images taken during the August survey 

 detected a range of benthic conditions from undisturbed to a 

 "stressed" condition. As in the 1984 survey, the STNH-N mound 

 exhibited high OSI values in August 1985, reflecting successful 

 recolonization by Stage III infauna. Also, patches of reduced 

 sediment, the apparent result of large-scale biological sediment 

 reworking, were evident in 82% of the STNH-N images. The STNH-S 

 images showed evidence of "stress" relative to its condition in 

 1984. RPD depths and OSI values had decreased. The western 

 portion of the STNH,-S mound continued to lack high-order 

 successional infauna. Near-surface, reduced sediment patches were 

 evident in 47% of the images. 



Images collected at CS-1 and CS-2 exhibited relatively 

 undisturbed benthic environments consisting largely of Stage III 

 infauna and well-developed RPD's. Evidence of new dredged material 

 was observed at approximately 100m north of CS-1. Biogenic 



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