40 



This smaller survey consisted of 10 survey lanes measuring 1000 m in length and spaced 

 100 m apart. Side-scan images of the seafloor within the small 1000 x 1000 m survey 

 identified areas with no apparent dredged material. However, these areas were in 

 relatively shallow water (< 18 m) which may not be representative of the ecological 

 conditions at WLIS. Side-scan operations were continued in the 1500 x 4000 m survey 

 area in water depths greater than 18 m. Although detection of dredged material was 

 common at depths below 18 m, a potential reference area was identified at 40°58.301 'N, 

 73°27.722'W (NAD 27), with a mean water depth of 19.5 m (Figure 2-5). The center of 

 the new reference area was designated as SE-REF CTR. 



The results of the high-resolution side-scan sonar survey over the identified reference 

 area showed an area that appeared relatively free of dredged material (Figure 3-9). Lobster 

 pots and trawl lines marked the seafloor. A dredged material mound was detected to the 

 northwest, outside of the 300-m radius of the reference area center. Some weathered historic 

 dredged material may be present in the southwest section of the new reference area. In the 

 larger 1500 x 4000 m survey area, we did detect dredged material deposits to the north and 

 east of this region outside of SE-REF, which are shown in Figure 3-10 for comparison. 



3.5.2 REMOTS® Sediment-Profile Photography 



REMOTS® replicates were representative of target locations in the 300 m radius of 

 the potential reference area (Figure 3-11). The figure also shows the 25-station REMOTS® 

 grid relative to ten grab samples taken randomly over SE-REF. 



3.5.2.1 Sediment Grain Size and Stratigraphy 



Fine-grained silt predominantly characterized the ambient sediments. The 

 photographs showed an oxidized, brown layer with some small shell fragments over black 

 or grey-black mud. Figure 3-12 shows the variation in sample replicates from SE-REF. 

 Replicate lOONW D, with a deep RDF and high OSI value, is representative of many 

 replicates at SE-REF. lOONW D is within the normal grey-scale for REMOTS® replicates, 

 whereas 200SW C contains sediments that are darker in appearance than typical for 

 DAMOS reference areas. Redox rebounds were observed in ten replicates. 



The physical REMOTS® parameters were comparable to reference areas SOUTH 

 and SW-REF. The grain size was primarily silt and clay, > 4 phi. The mean camera 

 penetration for each station ranged from 7.79 to 15.67 cm, with an overall average of 

 12.91 cm. In September, penetration depth was shallower at SOUTH and SW-REF, with 

 average mean depths of 9.43 and 6.24 respectively. The mean boundary range averaged 

 1.52 cm, varying between 0.65 and 4.80 cm. The boundary range was slightly greater 



Monitoring Cruise at the WLIS Disposal Site, September 1997 and March 1998 



