clams and the mussel Mytilis edulis. As indicated by the results 
of the REMOTS® July 1985 survey, this region southwest of the 
disposal site appeared to be a relatively high-kinetic area 
characterized by surface shell lag layers (Figure 3-42). 
The frequency distributions of boundary roughness values 
were determined for all stations within the disposal site (NL-85, 
NL-III, NL-II, NL-I, and NL-RELIC, Figure 3-43a), for the NL-85 
mound only (Figure 3-43b), for the Reference station (Figure 3- 
43c), and for the southwest reconnaissance grid (Figure 3-43d). 
The major mode in each case was centered at 0.80 cm. There was no 
significant difference between the boundary roughness values at the 
entire disposal site and the Reference station (Mann Whitney 
U-test; p = 0.6877), or between the NL-85 disposal mound and the 
Reference station (Mann Whitney U-test: p = 0.4643). Also, there 
was no change in small-scale bottom roughness at the NL-85 mound 
since the January 1986 survey (Mann-Whitney U-test; p = 0.5357). 
The lack of change in small-scale surface topography at the NL-85 
mound indicated that the minor disposal activity since January had 
little or no impact. Overall, the highest roughness values were 
recorded in the southwest grid; this was related to the presence 
of large shell fragments at the sediment surface in this region. 
Stations in the southeast portion of the NL-85 mound had 
relatively low apparent RPD values (Figure 3-44). This area of 
shallow RPD depths overlapped both disposed materials and some 
ambient bottom stations. This affected area was generally below 
the 19 meter isobath (Figure 3-7), while the rest of the mound was 
located in shallower water. The shallow mean apparent RPD's could 
have been related to a high sediment oxygen demand or a limited 
supply of oxygen to these sediments. In the July 1985 REMOTS® 
survey of the New London Disposal Site, the southeast corner (and 
northern edge) of the site had shallow, or absent, apparent RPD 
depths which were either very shallow or equal to zero (i.e., no 
oxidized sediment layer). The southeast corner of the site was 
again observed to have anomalously shallow oxidized layers in the 
November 1985 survey. During the July 1986 survey, seven stations 
showed shallow RPD depths along the northern edge of the disposal 
site. It is unclear if these few stations represented general 
hypoxic water conditions along the northern perimeter of the site 
or if these low RPD values represented locally high sediment oxygen 
demands. Much of the southwest survey grid also was marked by 
shallow apparent RPD depths (Figure 3-45). This outlying area 
occurred at greater depths relative to the disposal site. 
The apparent RPD values from all stations in the disposal 
site (Figure 3-46a), as well as just the NL-85 mound (Figure 
3-46b) , were not significantly different from the Reference station 
values (Figure 3-46c, Mann-Whitney U-tests; p = 0.6303 and 0.6885, 
respectively). However, the NL-85 RPD values have significantly 
deepened since the January post-disposal REMOTS® survey 
(Mann-Whitney U-test; p = 0.001). This reflects the effects of 
25 
