for the disposal of dredged material. A new disposal point was 
chosen (designated NL-85) approximately 500 meters east of the 
center of the New London Disposal Site. This location was 
characterized by a fairly flat area at the center covered with 
amphipod tube mats and shell hash. Immediately north were mounds 
from previous disposal activities. It was predicted that disposal 
at this new location would result in the containment of the dredged 
material in this localized area. Coarse material was found in the 
northwest quadrant of the NLON-85 survey area, probably indicating 
the presence of dredged material from disposal operations at the 
existing mounds (NL-RELIC and/or NL-III). 
The survey conducted in January 1986 at the NL-85 
disposal mound (post-disposal) included precision bathymetry and 
REMOTS® sediment profiling. Results of the analysis of the 
bathymetric data indicated that significant changes in depth (>10 
cm) occurred as far as 350 meters from the center of the mound 
(created since the November 1985 survey). Dredged material was 
seen in the REMOTS® photographs as far as 500 meters from the mound 
center in layers less than 10 cm thick. These thin layers extended 
slightly beyond the eastern boundary of the disposal site (Figure 
3-31). The mound had a maximum thickness of approximately 2 meters 
and a volume of about 194,000 m?, based on the comparison of the 
November 1985 and January 1986 bathymetric surveys. Recolonization 
of Stage III infauna by lateral or vertical migration was evident 
on the fringes of the mound. 
The results of the survey conducted around the NL-85 
disposal mound in July 1986 indicated a small reduction in volume 
of dredged material when compared to the January 1986 survey. The 
minimum depth at the NL-85 mound increased by up to 20 cm. This 
deepening could have been the result of erosion, compaction, 
consolidation, subsidence, or a combination of these processes. 
Examination of REMOTS® photographs from the NL-85 mound in July 
1986 did not detect any large scale erosional features (e.g., shell 
lag deposits, truncated RPD's, or mud clasts) that could account 
for this reduction in volume. The topography at the NL-III mound 
(also included in the NLON-85 survey area) did not change between 
the January and July surveys as verified by almost perfect 
alignment of similar depth contours. This was also true for other 
topographic features in the survey area, indicating good agreement 
of the two surveys compared to calculate the change in volume. The 
quasi-fluid nature of a portion of the newly deposited dredged 
material makes it more vulnerable to erosional processes than 
previously deposited material. However, because no evidence of 
erosion was detected in the REMOTS® photographs, the most 
parsimonious explanation for the slight depth increase is 
consolidation. The July 1986 REMOTS® results also indicated that 
very thin layers of dredged material occurred in a very small area 
beyond the eastern disposal site boundary (Figure 3-38). 
33 
