3.0 RESULTS 



3.1 Bathymetry 



The bathymetry at CSDS changed very little between May 1992 (Figure 3-1) and August 

 1992 (Figure 3-2). At approximately 72°21.75' W and 41° 12. 85' N, the mound formed by the 

 disposal of fine-grained sediment from North Cove caused the contour lines to bend to the south 

 in both surveys. South of 41°12.50' N, the contours in the August survey were slightly deeper 

 and more convoluted than in May. This is the area where sand waves were recorded in the 

 fathometer trace in May (Wiley 1994). Comparing depths in the two bathy metric surveys showed 

 very little loss from May to August (Figure 3-3). Five areas of -20 cm depth difference exist, 

 each a maximum of 75 m in diameter. Up to 40 cm of material had accumulated at 16 locations 

 in the southern portion of the survey area from May to August (Figure 3-4). Each of these areas 

 was less than 100 m in diameter. 



3.2 REMOTS® 



Of the 25 REMOTS® stations surveyed at CSDS in August 1992, two were fine-grained 

 dredged material, and four were sand over mud. The remaining stations were sand (Figure 3-5). 

 The two stations with fine-grained dredged material (G8 and G9) were located closest to the 

 specified disposal point. Of the REMOTS® stations that were surveyed both in May and August 

 1992, E3, F6, F7, G5, G10, D3, F8, and E9 were sand over mud in May, but only sand was 

 visible in August (Figure 3-6). Station F9 was ambient sandy sediment in May, but in August it 

 was sand over dredged material (Figures 3-7 and 3-8). Stations G6, G8, and G9 remained 

 unchanged. Sand is very difficult for the REMOTS® camera to penetrate; as a result, REMOTS® 

 photographs taken at a sandy station usually have very low penetration and often do not show the 

 subbottom structure. Ten new stations were surveyed in August to determine if there was any 

 other fine-grained material at the site that had not been detected in May. Eight of these stations 

 detected only sand, but D6 and D7 showed sand over fine-grained dredged material. 



In addition to documenting the presence of ambient sand or fine-grained dredged material, 

 the REMOTS® sediment-profile photographs showed variations in the sand grain size between 

 stations and mapped the locations of sand waves or lag deposits. In both May and August, 

 coarser grained sand with lag deposits of pebbles or shells was found north of 41° 12.75' N, and 

 finer grained sand with bed forms was found to the south (Figure 3-8). 



Monitoring Cruise at the Cornfield Shoals Disposal Site, August 1992 



