2.0 METHODS 



2.1 Buoy Deployment 



Marker buoys were deployed at the CCDS and Springhill Beach Sites to serve 

 as navigational aids for disposal operations. Two small "lollipop" buoys were 

 deployed at the Springhill Beach Site at a depth of 4.5 m MLW. The buoys were 

 located at 41° 45.439'N, 70° 26.913'W and 41° 45.281'N, 70° 26.225'W along an axis 

 running roughly parallel to the beach. 



One marker buoy, "CCD", was deployed within CCDS at 41° 49.007'N and 70° 

 25.426'W (Figure 2-1). This location is approximately 600 meters west of the center 

 of the CCDS in approximately 23 m of water. 



22 Bathymetry and Navigation 



The precision navigation required for all field operations was provided by the 

 SAIC Integrated Navigation and Data Acquisition System (INDAS). This system uses 

 a Hewlett-Packard 9920 series computer to collect position, depth, and time data for 

 subsequent analysis as well as providing real-time navigation. Positions were 

 determined to an accuracy of ± 3 meters from ranges provided by a Del Norte 

 Trisponder® System. For the present survey, shore stations were established at 

 known benchmarks at Telegraph Hill, Sandwich, and Indian Hill, Plymouth. A 

 detailed description of the navigation system and its operation can be found in the 

 DAMOS QA/QC Plan (SAIC, 1990d). 



The depth was determined to a resolution of 3.0 cm (0.1 feet) using an Odom 

 DF3200 Echotrac® Survey Recorder with a narrow-beam 208 kHz transducer. The 

 speed of sound was determined from the water temperature and salinity data 

 measured by an Applied Microsystems CTD probe. During analysis, raw 

 bathymetric data were adjusted for speed of sound and for changes in tidal height 

 during the survey. A detailed discussion of the bathymetric analysis technique is 

 also given in DAMOS QA/QC Plan (SAIC, 1990d). 



The predisposal bathymetric survey, conducted at the "CCD" buoy on 22 

 March 1990, encompassed a 1200 x 1200 m grid with 25 m lane spacing, centered at 

 coordinates 41° 49.000'N and 70° 25.430'W (Figure 2-1). The postdisposal CCDS 

 survey, conducted on 24 April 1990, was extended an additional 300 meters to the 

 east of the predisposal grid encompassing a 1200 x 1500 m grid with 25 m lane 

 spacing (Figure 2-2). 



The Springhill Beach predisposal bathymetric survey conducted on 23 March 

 1990 consisted of a 2000 x 1000 m grid with 25 m lane spacing (Figure 2-3). Survey 

 lanes were oriented at a bearing of 288° true, running parallel to the axis defined by 

 the two marker buoys deployed at the site. This same grid was used for the 



Monitoring Cruise at the Cape Cod Canal Disposal Site and Springhill Beach Site 



