140 



• Collect cores along the cross-sections of the Seawolf Mound to assess the physical 

 and chemical composition of the sediments to verify the presence of at least 50 cm 

 of cap material. 



The thickness and lateral coverage of the capping material was confirmed with 

 sediment cores and sediment profde image surveys. Cores revealed that the cap was at least 

 50 cm thick throughout the area sampled and may have reached 2-3 meters near the center of 

 the mound. Core data indicated that the top 50-cm of material had no elevated levels of 

 chemical contaminants that would indicate the presence of contaminated UDM. None of the 

 analytical samples recovered from the cores collected in 1997 had contaminant levels 

 consistent with UDM. One core did recover material below 2 m that appeared oily, and 

 consistent with UDM. 



• Examine the benthic infaunal species diversity and relative abundance over the 

 surface of the Seawolf Mound through analysis of six sediment grab samples. 



Benthic analysis of samples collected in September 1997 indicated that the Seawolf 

 Mound was in the intermediate stages of recolonization, with abundances of organisms 

 increasing with distance from the center of the mound. Species diversity, as calculated by 

 the Shannon-Wiener index H', ranged from 2.65 to 4.10. Evenness, as calculated by the 

 Shannon-Wiener index J', ranged from 0.48 to 0.82. The low diversity value was attributed 

 to the dominant presence of the bivalve, Nucula annulata. The diversity at Station CTR was 

 relatively high considering the low abundance of individuals. The high diversity relative to 

 low species abundance is indicative of an early stage of succession (Pearson and Rosenberg 

 1978). 



The use of standard benthic parameters (species richness, abundance, OSI, diversity) 

 provided a useful comparison with reference areas and seasonal patterns. REMOTS® results 

 were consistent with benthic data, except for a difference at the Seawolf Mound center 

 station that was due to slower than expected recolonization of the Gardiner's clay. 

 Community analysis is a suitable second tier evaluation to provide additional interpretation 

 of REMOTS® results 



• Perform a detailed master bathymetric survey of the region surrounding NLDS 

 as defined by the 1982 FPEIS 



The master bathymetric survey demonstrated that the configuration of disposal 

 mounds at the NLDS has remained stable over at least the last twenty years (see above and 

 Volume I). The 1997 master bathymetric survey provides a detailed benchmark for future 

 studies of dredged material disposal and consolidation processes. 



Monitoring Cruise at the New London Disposal Site, Seawolf Mound 1995 - 1998 



