1.0 INTRODUCTION 



The Central Long Island Sound Disposal Site (CLIS) is located 5.6 nautical miles 

 south of New Haven Harbor, Connecticut. Environmental monitoring by the US Army 

 Corps of Engineers, New England Division (NED) has occurred at the site since 1972. A 

 primary objective of past investigations has been to assess the environmental impact of 

 dredged material disposal, particularly in terms of the postdisposal recovery of benthic 

 ecosystems. A secondary historical objective has been to monitor the location of dredged 

 material, the height and stability of individual dredged material mounds, and any 

 postdepositional dispersion of material. Several active and inactive disposal points or 

 mounds currently exist at CLIS. The previous monitoring survey at CLIS was conducted in 

 July 1988 (SAIC 1990a). During the 1988/89 and 1989/90 disposal seasons, approximately 

 594,800 m^ of dredged material was disposed at buoy locations CLIS-88 and CLIS-89. At 

 location CS-90-1, 28,720 m^ of material unsuitable for unconfmed open water disposal was 

 capped by 78,550 m^ of clean sediment in January 1990. The July 1990 CLIS survey 

 investigated active disposal points CLIS-88, CLIS-89, and CS-90-1 (Figure 1-1). 



Science Applications International Corporation (SAIC) conducted the field operations 

 for this report at CLIS from 18 to 23 July 1990. The field work consisted of a precision 

 bathymetric survey, a Remote Ecological Monitoring of the Seafioor (REMOTS®) sediment- 

 profile photographic survey, dissolved oxygen (DO) and conductivity, temperature, and depth 

 (CTD) profiles, and sediment sampling. The objectives of this study were 



• to delineate the extent and topography of the recently deposited dredged 

 material resulting from the past two years' disposal activities through 

 bathymetry and sediment-profile photography; 



• to measure near-bottom and near-surface dissolved oxygen concentrations and 

 vertical profiles of temperamre and salinity at selected disposal site and 

 reference stations to characterize depth gradients and assess near-bottom 

 dissolved oxygen concentrations relative to REMOTS® benthic analysis; and 



• to collect additional baseline sediment grain size and chemistry samples from 

 the reference areas. 



The 1990 monitoring scheme at CLIS investigated the following predictions: 



• Sediment disposed since July 1988 would result in the formation of mounds 

 with radii of 250-300 m at CLIS-88 and CLIS-89 buoy locations; 



Monitoring Cruise at the Central Long Island Sound Disposal Site, July 1990 



