EXECUTIVE SUMMARY (continued) 



bathymetric surveys performed over the mound to ensure successful development, 

 comprehensive environmental monitoring surveys were performed over the Seawolf Mound 

 in 1997 and 1998. 



The August 2000 bathymetric survey showed no significant changes in the 

 topography of the Seawolf Mound relative to the survey performed in July 1998. REMOTS® 

 sediment profile photography showed the Seawolf Mound continued to be populated by a 

 benthic community consisting of advanced successional stage assemblages, with relatively 

 deep apparent aeration of the sediments comprising the surface of the mound. 



The USCGA mound is also a historic dredged material disposal mound, developed 

 within the northeast quadrant of NLDS during the 1994-95 disposal season. This mound 

 consists of 124,000 m^ of sediment sequentially removed fi"om the area surrounding the 

 Eagle Pier at the US Coast Guard Academy on the Thames River. This bottom feature was 

 considered a confined aquatic disposal (CAD) mound, as the project sediments were directed 

 to a disposal point located between the pre-existing NL-TR and NL-RELIC mounds. Based 

 on the findings of the initial survey effort in August 1995, follow-on monitoring was 

 deferred until the August 2000 field effort. 



An advanced benthic successional stage (Stage III) was noted at the majority of 

 REMOTS® stations sampled over the USCGA mound. As the USCGA material has been 

 recolonized and subject to increased aeration over time, it has become increasingly difficult 

 to distinguish it fi"om ambient sediments. 



Overall, the August 2000 REMOTS® sediment-profile imaging survey showed 

 healthy benthic conditions at USCGA, as well as the other project mounds (NL-91 and D/S, 

 and Seawolf) and the NLDS reference areas (NLON REF, NE REF, and WEST REF). The 

 RPD values were consistently deep, indicating good oxygen penetration within the surface 

 sediments. In contrast to previous surveys, little physical disturbance was observed, as many 

 images over each mound and reference area displayed intact amphipod mats and a 

 depositional layer of organic matter on top of the sediments. Amphipods appeared to be in a 

 transition fi-om inactive decaying mats to the reestablishment of active juvenile populations. 

 The average Organism-Sediment Index (OSI) values at the three mounds (NL-91 and D/S, 

 +8; Seawolf, +8; and USCGA, +9) were all greater than the average for the reference areas 

 (+7). Both the mound and reference area OSI values are indicative of healthy or undisturbed 

 benthic habitat quality at the time of the August 2000 survey. 



