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 used a Hewlett-Packard 

 9920® series computer to collect position, depth, and time data for later analysis, as well as 

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

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

 Stratford Point (41°9.112' N and 73°6.227' W) and Lighthouse Point (41°14.931' N and 

 72°54.255' W). DAMOS Contribution #60 (SAIC 1989) contains a detailed description of 

 the navigation system and its operation. 



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 feet) as described in 

 DAMOS Contribution #48 (SAIC 1985). Depth values transmitted to the computer were 

 adjusted for speed of sound and transducer depth. Before starting the 1991 precision 

 bathy metric survey, a Seabird Instruments, Inc. SEACAT SBE 19-01 CTD probe was used 

 to calculate a sound velocity profile. During analysis, raw bathymetric data were 

 standardized to Mean Low Water by correcting for changes in tidal height during the survey. 

 A detailed discussion of the bathymetric analysis technique is given in DAMOS Contribution 

 #60 (SAIC 1989). 



The June 1991 bathymetric survey of the northwest corner of CLIS encompassed a 

 1200 x 1200 m grid centered at coordinates 41°9.260' N and 72°53.353' W (Figure 1-2). 

 The survey consisted of forty-nine lanes run east and west at 25 m lane spacing. 



2.2 REMOTS® Sediment-Profile Photography 



REMOTS® photography was used to detect the distribution of thin (1 to 20 cm) 

 dredged material layers, map benthic disturbance gradients, and monitor the process of 

 infaunal recolonization on, and adjacent to, the disposal mounds, and at reference areas. A 

 detailed description of REMOTS® photograph acquisition, analysis, and interpretive rationale 

 is given in DAMOS Contribution #60 (SAIC 1989). 



A REMOTS® survey was conducted at the reference areas, at the inactive mounds 

 (MQR, NHAV-74, CS-1, CLIS-89, FVP, and CLIS-88), and over the area of active disposal 

 (CLIS-90 and CS-90-1). The reference areas were 2500 m west (2500W-REF), 4500 m east 

 (4500E-REF), and 5094 m southeast (CLIS-REF) of the CLIS-87 buoy location (41°9.18' N 

 and 72°53.65' W). The REMOTS® survey at each reference area consisted of a thirteen- 

 station cross grid with stations 100 m apart. A thirteen-station cross grid was also used at 

 the inactive disposal mounds (Figure 2-1). For the area of active disposal, a thirteen-station 



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



