2.0 METHODS 



2.1 Bathymetry and Navigation 



The SAIC Integrated Navigation and Data Acquisition System (INDAS) provided the 

 precision navigation required for all field operations. This system uses a Hewlett-Packard 

 9920 series computer to collect position, depth, and time data for subsequent analysis and to 

 provide real-time navigation. A Del Norte Trisponder® system provided positioning to an 

 accuracy of ±3 meters. Shore stations were established in Connecticut at known 

 benchmarks at Greenwich Point and the Norwalk electric-generating facility. A detailed 

 description of the navigation system and its operation can be found in the DAMOS QA/QC 

 Plan (SAIC 1990a). 



An Odom DF3200 Echotrac® Survey Fathometer with a narrow-beam 208 kHz 

 transducer measured depths to a resolution of 3.0 cm (0.1 feet). Prior to the bathymetric 

 survey, the speed of sound was determined with a bar check apparatus. In addition, a Seacat 

 Model SBE 19-01 profiler obtained a sound velocity profile to verify the bar check 

 measurement. Depth values transmitted to the computer were adjusted for speed of sound 

 and transducer depth. During data analysis, correction for changes in tidal height 

 standardized the raw bathymetric data to Mean Low Water. A complete description of the 

 bathymetric analysis technique is also given m the DAMOS QA/QC Plan (SAIC 1990a). 



The previous three bathymetric surveys of the WLIS Disposal Site (November 1987, 

 July 1988, and July 1990; SAIC 1990b, 1990c, and Germano et al. 1993, respectively) 

 utilized an 800 x 800 m grid which included the WLIS "A", "B", "C", and "D" disposal 

 mounds. The June 16, 1991 bathymetric survey was extended 400 m eastward (1200 x 

 800 m) to include the recently formed WLIS "E" mound (Figure 1-2). As with the previous 

 surveys, the 1991 grid consisted of thirty-three lanes miming east and west at a 25 meter 

 lane spacing. 



2.2 REMOTS® Sediment-Profile Photography 



REMOTS® photography was used to detect the distribution of thin ( < 20 cm) 

 dredged material layers, map benthic dismrbance gradients, and monitor the progress of 

 infaunal recolonization on, and adjacent to, the WLIS "E" mound. A detailed description of 

 REMOTS® image acquisition, analysis, and interpretative rationale is given in the DAMOS 

 QA/QC Plan (SAIC 1990a). 



REMOTS® monitoring at WLIS utilized a 25-station star grid, with 100 m spacing, 

 centered at the buoy coordinates for the 1990-1991 disposal season (40°59.333' N, 

 73°28.888' W, "E" mound) and a 13-station cross-shaped grid centered at the "D" mound 

 (Figure 2-1). Triplicate photographs were taken at each station. In addition, sampling at 



Monitoring Cruise at the Western Long Island Sound Disposal Site, June 1991 



