1 . INTRODUCTION 



The Cornfield Shoals Disposal Site is located 

 approximately 3 . 3 nm southeast of Cornfield Point in Old Saybrook, 

 Connecticut. It occupies a 1 nm square area centered around 

 41°12.68N, 72°21.52W and has water depths in the range of 4 9 to 57 

 meters. Cornfield Shoals is presently the only site in New England 

 managed as a dispersive site; the disposal site has a relatively 

 smooth, sandy bottom with a shallow depression oriented in an east- 

 west direction. The near-bottom energy regime is the highest of 

 all DAMOS sites and this is reflected in the texture of the bottom 

 sediments (primarily sand and gravel) . Some overconsolidated clay 

 and clay nodules from glacial lake deposits have been found in the 

 site, providing further geological evidence of scouring. The major 

 currents at this site are the result of an east-west tidal 

 component and the outflow of the Connecticut River; seasonal river 

 effects can be quite pronounced due to spring runoff and snow melt. 

 Although recent current meter data are not available for this site, 

 near-bottom current data obtained in 1978 (NUSC, 1979) indicate 

 that average peak tidal velocities are on the order of 30 cm/sec 

 in a northwest-southeast direction. The relatively high energy 

 regime at Cornfield Shoals is equally composed of the tidal and 

 residual (river flow) components in contrast, for example, to the 

 New London Disposal Site that has similar tidal current velocities 

 but a smaller residual component, resulting in a reduced overall 

 energy regime. 



As with the other Long Island Sound disposal sites, the 

 incidence of storm-driven wave currents is reduced due to the 

 restricted fetch available at the site; only the most severe 

 northeast storms have any potential for effect. There is little 

 concern about storms and potential effects on sediment transport. 



Because Cornfield Shoals is a dispersive disposal site, 

 its use has been limited to the deposition of relatively 

 uncontaminated dredged material from the Connecticut River and 

 surrounding area. The average annual volume of dredged material 

 deposited at Cornfield Shoals is approximately 55,000 m^, however 

 the actual amount can vary widely from year to year. Previous 

 monitoring surveys have included study of the near-bottom currents 

 and precision bathymetric surveys in 1978 and 1979 (NUSC, 1979) . 

 The high current conditions at this site make diving operations 

 impossible, and deploinnent of other types of oceanographic sampling 

 gear is equally difficult. 



A precision bathymetric survey was conducted at the^ 

 Cornfield Shoals Disposal Site on 31 July 1987 to determine if any 

 bathymetric changes have occurred relative to prior surveys. It 

 was expected that no accumulation of dredged material would be 

 detected at the site even though approximately 360,000 m^ of 

 material has been deposited between 1979 and 1987. For the period 



