n 



the current ambient sediments (Turgeon et al. 1989). No samples had anomalous values 

 typical of dredged material deposits for any of the geochemical analyses. 



Although some survey data suggested the possibility of historic dredged material 

 within the 300 m radius of SE-REF, the evidence was rather ambiguous. Some possible 

 weathered dredged material was identified in the southwest section of SE-REF in the side- 

 scan sonograph (Figure 3-9). The mottled relief with no definite shadows typical of rocks 

 or boulders may represent disposed dredged material that has been on the seafloor for a 

 long time. This marked area could also be attributed to remaining glacial debris or 

 exposed bedrock associated with the small knoll feamre on the southern flank of the 

 reference area. If this is the case, the presence of the knoll and glacial debris may indicate 

 winnowing in the southwest section. 



REMOTS® stations 300N, 300SE, lOOS, 200S, and 200SW indicated possible 

 dredged material in a few replicates. Replicate C at 300NW was indeterminate because the 

 surface was disturbed by either a large burrow or camera penetration, or possibly both. 

 Replicate lOOS C had a mottled sediment profile which provided the most convincing 

 indication of dredged material for REMOTS® photographs (Figure 4-8). Replicates A and 

 C at 300SE and B at 300N had high boundary roughness values and dark sediments with 

 very shallow RPD depths. Replicate C at 200SW also was very sulfidic and had a thin 

 RPD layer (Figure 3-13). However, as mentioned previously, sulfidic sediments are 

 characteristic of the western Long Island Sound region. The high boundary roughness 

 values are most likely due to recent physical disturbances at the sediment-water interface 

 (i.e., trawling, dragging of lobster gear across the bottom, etc.). Abundant lobster gear in 

 the area was observed in both September and March and is visible in the side-scan survey 

 images at SE-REF. Because fishing practices, such as lobstering, that affect the bottom 

 sediments are intensive at WLIS and the surrounding regions, some uimatural disturbances 

 of the substrate are expected at all reference areas that are within close proximity to WLIS. 



In summary, the recent survey data indicated that SE-REF meets sufficient 

 reference area requirements to replace 2000W as the third reference area for WLIS. SE- 

 REF is within 1500 m of the WLIS boundary and appeared to have a moderate topographic 

 relief. The fine-grained sediments, primarily composed of fine sand, silt, and clay, were 

 similar to observations of grain size at WLIS and the previous reference areas. Due to the 

 widespread distribution of dredged material in the region, it is unlikely that a reference 

 area with a complete lack of evidence of dredged material will be found. Although the 

 side-scan and REMOTS® detected possible historic dredged material, the evidence was 

 equivocal. No methane bubbles, such as those seen in many replicates showing sulfidic 

 dredged material at 2000W, were present at SE-REF. All ten grab samples indicated 



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



