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2.0 METHODS 



2.1 Survey Areas 



In order to fulfill the objectives of the 1995 CLIS monitoring survey, two 

 bathymetric survey areas were defined over the CLIS 94 and NHAV 93 disposal mounds. 

 The survey over the CLIS 94 mound was 1000 m x 1000 m, centered on the first position 

 of the 1994 CDA buoy (41°09.343' N, 72°53.099' W). A total of 41 survey lanes at 25 m 

 lane spacing were required to delineate the topography of the new CLIS 94 mound (Figure 

 2-1). The second, larger survey was conducted over a 1600 m x 1600 m area, and 

 centered at 41°09.125' N, 72°53.413' W (Figure 2-1). The layout of this survey was 

 identical to the surveys run over the NHAV 93 mound in the 1993 and 1994 disposal 

 seasons, requiring 65 survey lanes to map the changes in the now historic NHAV 93 

 mound. Detailed bathymetric charts were generated for both areas to quantify mound 

 height, lateral distribution of dredged material, and position relative to other disposal 

 mounds. 



2.2 Bathymetry and Navigation 



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

 the precision navigation and data collection required for all SAIC field operations. This 

 system utilizes a Hewlett-Packard 9920® series computer to provide real-time navigation, 

 as well as collect position, depth, and time data for later analysis. A Del Norte 

 Trisponder® System provided ppsitioning to an accuracy of +3 m. Shore stations were 

 established along the Connecticut coast at the known benchmarks of Stratford Point 

 (41°09.112' N, 72°06.227' W) and Lighthouse Point (41°14.931' N, 72°54.255' W) 

 (Figure 1-1). A detailed description of the navigation system and its operation can be 

 found in the DAMOS Navigation and Bathymetry Reference Report (Murray and Selvitelli 

 1996). 



An ODOM DF3200 Echotrac® Survey Fathometer with a narrow beam, 208 kHz 

 transducer measured individual depths to a resolution of 3.0 cm (0.1 ft) as described in 

 DAMOS Contribution No. 48 (SAIC 1985). Depth values transmitted to INDAS were 

 adjusted for transducer depth. The acoustic returns of the fathometer can reliably detect 

 changes in depth of 20 cm or greater due to the accumulation of errors introduced by the 

 positioning system, tidal corrections, changes in sound velocity through the water column, 

 the slope of the bottom, and vertical motion of the survey vessel. 



The expanding resources of the Internet have allowed SAIC to access the National 



Oceanographic and Atmo spheric Administration (NOAA), Ocean and Lake Levels 



Monitoring Cruise at the Central Long Island Sound Disposal Site, September 1995 



