1J9_ 



reference areas (Figure 3-27 and Tables 3-1 and 3-9). The recolonization status of the area 

 around the NL-91 and D/S mound complex was characterized as supporting a solid Stage 

 II population with some progression into Stage III assemblages. Apparent RPD values of 

 the NL-91 and D/S mound complex tended to be slightly lower, but comparable to those of 

 the two eastern reference areas (NE-REF and NLON-REF). 



In 1995, three years after the NL-91 and D/S mound complex was placed, the 

 benthic communities at the most recent disposal mounds were even more advanced than in 

 1992 and comparable to the reference area benthic community (which had improved). All 

 stations contained Stage II on III successional stages and RPDs had deepened (Table 3-2). 

 OSI values had improved from an average of +4.9 to +8.0. In 1997, the NL-91 and D/S 

 mound complex continued to support a healthy benthic community. The dominant 

 successional stages were Stage II or Stage II on III (Table 3-3). The median OSI values 

 ranged from +2.0 to +11, with an overall average of +8.6, slightly higher than measured 

 in 1995. After placement of additional cap material in 1998, the NL-91 and D/S mound 

 complex again supported a healthy benthic community. The dominant successional stages 

 were Stage II or Stage II on III communities (Table 3-4). 



Recolonization of the new dredged material was rapid and many of the replicate 

 photographs from these regions showed Stage III feeding voids. The station median OSI 

 values ranged from +3.0 to +11.0, with an overall average of +7.5, which was only 

 slightly lower than prior to the placement of new material (1997). 



4.3.2 Sediment Distribution and Characterization 



The evidence from sediment profile photography of the distribution of dredged 

 material released during the 1991-1992 disposal season is consistent with the placement of 

 a mixed deposit of Dow UDM and Stonington UDM and Port Niantic material near the 

 D/S buoy, and east of the D/S buoy a deposit of Dow CDM (compare Figures 3-8 and 3- 

 11). REMOTS® photographs collected in 1992 were able to provide a clear delineation of 

 the distribution of fresh dredged material, but it was difficult to clearly separate the source 

 of fresh materials. The UDM and CDM from Dow facilities were quite similar in 

 sediment texture (black silt). However the REMOTS® photographs revealed the presence 

 of a layer of sand over much of the surface of the NL-91 and D/S mound complex. 



This distinctive sand layer (1.27 cm to 7.03 cm thick) was mixed with dredged 

 shells and small pebbles. The layer is similar in texture to the Port Niantic material 

 targeted for the NDA buoy on 11 and 12 December 1991 at the end of the disposal period 

 (Figure 3-12). REMOTS® photographs collected in the vicinity of the bulk of the CDM 

 deposit detected a thin layer of biologically re-worked dredged material over fresh dredged 



Monitoring Cruise at the New London Disposal Site, 1992 - 1998 



