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 data 

 accurate to ±3 m. 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 (Browning et 

 al. 1990). 



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 CTD (conductivity, temperature, and depth) profiler obtained a sound 

 velocity profile to verify the bar check measurement. Depth values transmitted to the 

 computer were adjusted for transducer depth. During data analysis, depth measurements 

 were corrected for speed of sound through water and standardized to Mean Low Water 

 (MLW) by adjusting for changes in predicted tidal height. A complete description of the 

 bathymetric analysis technique is also given in the DAMOS QA/QC Plan (Browning et al. 

 1990). 



The 1992 bathymetric survey consisted of 41 east- west lanes covering a 

 1200 x 1000 m area (Figure 2-1). The northern 33 lanes of this survey corresponded to the 

 previous 1991 bathymetry survey lanes. The buoy for the 1991-1992 disposal season ("F") 

 was within 100 m of the area covered by the 1991 survey; therefore, eight additional lanes 

 were included in the 1992 survey to ensure complete coverage of any recently deposited 

 material. 



2.2 REMOTS® Sediment-Profile Photography 



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

 recently deposited dredged material layers, map benthic disturbance gradients, and monitor 

 the progress of infaunal recolonization on, and adjacent to, the WLIS "F" mound. A 

 detailed description of REMOTS® image acquisition, analysis, and interpretative rationale is 

 given in the DAMOS QA/QC Plan (Browning et al. 1990). 



The 1992 REMOTS® survey of WLIS utilized a 25-station star grid centered at the 

 buoy coordinates (40°59.160' N and 73°28.880' W) for the 1991-1992 disposal season 



Monitoring Cruise at the Western Long Island Sound Disposal Site, July 1992 



