(43°30.131'N, 70°22.978'W) and at the Stage Island Monument 

 (43°27.403 'N, 70°21. 101 *W) . These stations were selected based on 

 the availability of accurate horizontal control points. 



Individual depth measurements were determined to a 

 resolution of 10 cm using an Odom Echotrac® model DF32 00 survey- 

 fathometer equipped with a 208 kHz transducer, as described in 

 DAMOS Contribution #48 (SAIC, 1985) . An averaged speed of sound in 

 seawater was calculated from two profiles of temperature and 

 salinity. These were obtained with an Applied Microsystems STD-12 

 at the start and finish of the survey. 



The bathymetric survey covered an 800 X 800 m area 

 centered at 43°28.500'N and 70° 19. 300' W, on the former coordinates 

 of the disposal buoy (Figure 2-1) . A total of 33 lanes spaced 25 

 m apart were surveyed in the east-west direction. During analysis 

 the raw depth data were standardized to Mean Low Water by 

 correcting for the ship's draft, speed of sound in seawater, and 

 changes in tidal height during the survey. A more detailed 

 description of the bathymetric analysis procedure is provided in 

 SAIC (1989), and QA/QC procedures are reviewed in SAIC (in prep.). 



2.2 REMOTS® Sediment-Profile Photography 



REMOTS® photography was used to detect and map the 

 distribution of thin (1-20 cm) dredged material layers. This 

 capability complemented the precision bathymetric survey, which was 

 able to resolve changes greater than 10 cm in depths found at this 

 site. A detailed description of REMOTS® image acquisition, 

 analysis and interpretative rationale is given in SAIC (1989) . 



The REMOTS® survey grid was centered on the same 

 coordinates as the bathymetric survey (43°28.500 'N, 070°19. 300 'W) . 

 The sampling grid consisted of 25 stations spaced at 100 m 

 intervals over a 400 X 400 m area. Twelve additional stations were 

 established at 33 m and 66 m north, south, east and west of center, 

 and at 66 m northwest, northeast, southwest, and southeast of 

 center. REMOTS® stations were named based on distance and 

 direction from the center (station CTR) of the survey grid (Figure 

 2-3) . At each of the 37 stations an attempt was made to acquire 3 

 replicate sediment-profile photographs. 



In addition to the main sampling grid, 3 reference areas 

 (REF-1, REF-2, and REF-3) were sampled. Each reference area 

 consisted of a cross-shaped pattern of 9 stations at 100 m, 200 m, 

 and 300 m north, south, east and west of a central station (Figure 

 2-3) . Reference stations were positioned approximately 1000 m from 

 the disposal site center at the following coordinates: 43°28.198*N, 

 070°18.685'W for REF-1; 43°28.720'N, 070°19.978'W for REF-2; and 

 43°29.032'N, 070°19.429'W for REF-3. These stations were selected 

 based on similarity in water depth (20 to 30 m) , proximity to the 



