compared to shallow water surveys. However, the equipment used in 1988 and 1990 was 

 able to discriminate 20 cm changes at 90 m depth. Raw depth values were corrected to 

 Mean Low Water during analysis of the bathymetric data by adjusting for the ship draft, tidal 

 changes during the survey, and the speed of sound. The tidal changes used during SAIC 

 surveys are predicted tidal changes. Because disposal sites are located so far offshore, actual 

 tidal ranges (based on shoreline measurements) are not necessarily correct for a boat's 

 location during a survey. The correction method for normalizing to a benchmark survey also 

 corrects for tidal changes. 



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 progress of 

 infaunal recolonization on and adjacent to the disposal mound. A detailed description of 

 REMOTS® photograph acquisition, analysis, and interpretative rationale is presented in 

 DAMOS Contribution No. 60 (SAIC 1989a). 



A REMOTS® survey, performed 14, 15, and 16 August 1990, generated triplicate 

 photographs for each of the 41 disposal site stations surrounding the "MDA" buoy (Figure 2- 

 2). The objective of the survey was to map that portion of the recently deposited dredged 

 material not detectable with bathymetry. REMOTS® stations, spaced 100 m apart, extended 

 700 m to the north, 800 m to the south, 900 m to the east, and 800 m to the west of the 

 disposal site center. The 13 REMOTS® stations established at each of the three reference 

 areas allowed comparisons between ambient and on-mound conditions. These reference area 

 stations were arranged in a cross-shaped pattern similar to the disposal site sampling grid and 

 spaced 100 m apart. Photographs were taken in triplicate at each station with the exception 

 of 200S and 300S at SE-REF (due to difficulties with the camera). Disposal site and 

 reference area station locations were the same as those analyzed in January 1989. Reference 

 area locations, depths, and distances from the "MDA" buoy are summarized in Table 2-1. 



Monitoring Cruise at the Massachusetts Bay Disposal Site, August 1990 



