57 



6.4 CORNFIELD SHOALS DISPOSAL SITE 



6.4.1 Summary of CSDS 



The Cornfield Shoals Disposal Site (CSDS) is located 3.3 nmi southeast of Cornfield 

 Point, Old Saybrook, Connecticut and has been under study by NED since 1978. CSDS 

 occupies an area of 1 nmi 2 centered at 41° 12.680' N, 72°21.520' W (Figure 6-28). Water 

 depths at this site range from 49 m in the northeast corner to 58 m in the south central 

 portion. The predominant topographic features are a smooth, sandy bottom and bedforms 

 oriented in an east- west direction (Figure 6-29). The energy regime at CSDS is the highest 

 of all the DAMOS disposal sites. The major currents in this area are the result of an east- 

 west tidal flow and runoff from the Connecticut River; seasonal river effects can be quite 

 pronounced due to spring runoff and snow melt. Tidal flow is in a northwest-southeast 

 direction with an average maximum of 32 cm-s" 1 . During spring runoff, peak tidal flow can 

 reach 44 cm-s' 1 . Nontidal current flows to the southwest with a mean peak of 10 cm-s" 1 

 (SAIC 1988a). 



Relatively little is known about the potential value of this area as a resource for sport 

 and commercial fisheries. At present there are small "day boats" which trawl in the 

 shallower waters adjacent to this site. Lobster and whelk are commercially fished shoreward 

 of Long Sand Shoal on a seasonal basis as the "run" occurs. Some lobsters are caught in the 

 central depressions and in the sand- wave area to the south of the disposal site. Because there 

 is no shelter and little food on the sand, it can be assumed that the lobsters are moving 

 through this area and are not resident (SAIC 1988a). 



In 1978 and 1979, studies were conducted at CSDS to assess near-bottom currents and 

 turbidity conditions, sediment chemistry, and bathymetry (NUSC 1979). There have been 

 two monitoring cruises at CSDS since 1984. A bathymetric survey was conducted in July 

 1987 to determine if there had been any significant changes in bottom topography since 1979 

 (SAIC 1988d). A combined bathymetric and REMOTS® sediment-profile survey in July 

 1990 identified the location and areal extent of dredged material at CSDS (Germano et al. 

 1994). 



There was no disposal buoy at CSDS from 1987 to 1990. This management action 

 was implemented because the dispersive nature of CSDS indicated that a discrete disposal 

 mound would be unstable. When dredged material is deposited at CSDS, tidal action 

 disperses it throughout the site to form a thin layer of material undetectable by bathymetry. 

 As a result, the amount of accumulated dredged material at CSDS has been limited. 



Disposal volumes at CSDS have varied greatly over the past few years, with an 

 average annual amount of approximately 29,000 m 3 (Figure 6-30). Bathymetric surveys have 

 indicated there has been no significant change in topography since the baseline survey. In 



DAMOS Summary Report, 1985-1990 



