2.0 METHODS 



The August 1992 CSDS survey team used bathymetry, REMOTS® sediment-profile 

 photography, and a 24 kHz acoustic survey to determine the stability of the disposal mounds 

 and investigate any further sediment transport at the disposal site. The bathymetric and 

 REMOTS® sediment-profile surveys have been used in numerous studies to monitor benthic 

 conditions (Parker and Revelas 1989, Germano et al. 1994). The 24 kHz acoustic survey has 

 been used at other disposal sites to determine both surface (Wiley 1993) and subsurface 

 sediment densities (SAIC 1991). Together these technologies should provide an accurate 

 assessment of the sedimentology at the site. 



2.1 Bathymetry 



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 later analysis, and to 

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

 accuracy of ±3 m. Shore stations we*e established in Connecticut at known benchmarks at 

 Cornfield Point (41°15.79' N, 72°23.04' W) and Lynde Point Light (41°16.29' N, 

 72°20.59' W) in Old Saybrook, Connecticut. DAMOS Contribution No. 60 (Parker and 

 Revelas 1989) contains a detailed description of INDAS and its operation. 



An ODOM DF3200 Echotrac® Survey Recorder with a narrow-beam 208 kHz 

 transducer recorded depth to a resolution of 3.0 cm (0.1 ft) as described in DAMOS 

 Contribution No. 48 (SAIC 1985). Depth values transmitted to the computer were adjusted 

 for speed of sound and transducer depth. Before starting the bathymetry survey, a SeaBird 

 Instruments, Inc. SEACAT SBE 19-01 conductivity-temperature-depth profiler (CTD) was 

 used to calculate a sound velocity profile. During analysis, all depth values were converted 

 to Mean Low Water (MLW) after compensating for vessel draft and tidal fluctuations that 

 occurred while surveying. Position and depth data were also checked to identify and 

 eliminate any outlying values before producing an accurate contour plot. Analysis of the 

 bathymetric data was conducted using the Hydrographic Data Analysis System (HDAS). 



The August 5, 1992 bathymetric survey at CSDS was set up over the same grid used 

 in the 1991 and May 1992 surveys (Wiley 1994). The 1200 x 1200 m survey consisted of 

 49 lanes oriented east and west with 25 m lane spacing. 



2.2 REMOTS® 



A REMOTS® survey was conducted at CSDS on August 6, 1992 to define the limits 

 of dredged material distribution. In May 1992, a 45-station orthogonal REMOTS® grid had 

 been surveyed to define the dredged material boundary (Figure 2-1). In August 1992, 



Monitoring Cruise at the Cornfield Shoals Disposal Site, August 1992 



