EXECUTIVE SUMMARY 



Science Applications International Corporation (SAIC) conducted a monitoring survey 

 at the Central Long Island Sound (CLIS) Disposal Site from 18 to 23 June 1991 as part of 

 the DAMOS (Disposal Area Monitoring System) Program. The objectives of the June 1991 

 field operations were to map the distribution and thickness of dredged material in areas that 

 received project materials after the 1990 DAMOS survey (CLIS-90 and CS-90-1) and to 

 evaluate the status of inactive mounds: MQR, NHAV-74, CLIS-88, CLIS-89, CS-1, and 

 FVP. Surveying and monitoring techniques included precision bathymetry, REMOTS® 

 sediment-profile photography, CTD and dissolved oxygen information, and sediment grab 

 samples. 



In September 1990, the CLIS disposal buoy was deployed at41°9.212' N, 

 72°53.25' W. Barges released approximately 59,000 m 3 of dredged material at this location 

 between September 1990 and May 1991. It was predicted that a new disposal mound would 

 form at this location. During the 1989/1990 disposal season, material was released at, and 

 formed a mound at, the CS-90-1 location. During the 1990/1991 disposal season, barges 

 released 8,730 m 3 of additional dredged material at CS-90-1 to increase cap thickness. 



The precision bathymetric survey detected a small, newly formed disposal mound at 

 the CLIS-90 buoy location. The addition of 8,730 m 3 of material to the CS-90-1 was 

 detectable in the bathymetric survey as two 20 cm thick areas of accumulation. REMOTS® 

 sediment-profile photography detected the presence of dredged material at all stations within 

 the survey area. "Fresh" or recent dredged material, identified by sedimentary fabric and 

 shallow apparent RPD (Redox Potential Discontinuity) depths, was several hundred meters 

 away from the active mounds. The limit of the dredged material mound, as mapped 

 acoustically, was within a 100 m radius of the CLIS-90 buoy location. 



Benthic recolonization was determined from analysis of REMOTS® photographs 

 obtained at CLIS and at three outlying reference areas. Recolonization predictions from the 

 DAMOS tiered monitoring and management protocol were that the active mounds should be 

 in a Stage I sere while Stage III sere should colonize the inactive mounds: MQR, NHAV-74, 

 CLIS-88, CLIS-89, CS-1, and FVP. The 1991 REMOTS® data supported these predictions. 



Water column profiles of temperature, salinity, sigma-t, and dissolved oxygen were 

 determined on June 18th at the CLIS-90 buoy and three reference areas. The water column 

 at these four sampling stations was stratified with respect to both temperature and salinity. 

 Dissolved oxygen (DO) concentrations below the pycnocline were 6 to 7 ppm, 2 to 3 ppm 

 lower than near-surface values. DO values were similar between the CLIS-90 buoy location 

 and the three reference areas. 



Sediment samples collected from the CLIS reference areas contained metals in 

 similarly low concentrations as measured during previous CLIS surveys. Polyaromatic 

 hydrocarbons (PAHs) were also analyzed to provide a baseline for future sampling. PAHs 

 were measured at all three reference areas in concentrations generally within ranges present 

 in regional Long Island Sound. 



