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3.0 METHODS 



The Portland Disposal Site Capping Demonstration Project required a wide variety 

 of remote sensors and environmental monitoring techniques to evaluate the effectiveness of 

 subaqueous capping procedures at this deep water disposal site. SAIC conducted five 

 separate field efforts for the project, with one coring survey at the Royal River, and four 

 surveys over the southeast quadrant of PDS as part of the 1996-97 capping operation. 

 Precision bathymetry, REMOTS® sediment-profile and planview photography, side-scan 

 sonar, surface sediment grab sampling, and sediment coring provided information on the 

 ambient conditions at PDS, as well as morphology and composition of the disposal mound. 



3.1 Navigation 



In an effort to provide precise comparisons between the baseline, pseudo-UDM, and 

 CDM survey datasets, all bathymetric data were collected with the use of SAIC s Portable 

 Integrated Navigation and Survey System (PINSS). The PINSS navigation software was 

 resident on a Toshiba® 3200XT personal computer (PC) capable of providing real-time 

 navigation, as well as collect position, depth, and time data for later analysis. A Del Norte 

 Trisponder® System provided positioning data referenced to the North American Damm of 

 1927 (NAD 27) to an accuracy of +3 m. Shore stations were established along the Maine 

 coast at the known benchmarks of Portland Head Light (43° 37.381 'N, 70° 12.502 'W) 

 and Cape Elizabeth Light (43° 33.959 'N, 70° 12.034 'W; Figure 1-5). A detailed 

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

 Navigation and Bathymetry Reference Report (Murray and Selvitelli 1996). 



In order to maximize the efficiency of survey operations, DGPS data in conjunction 

 with PINSS were used to position the survey vessel over the REMOTS® and sediment 

 coring stations. A Magnavox 4200D GPS receiver and a Magnavox MX50R differential 

 beacon receiver provided DGPS positioning data to PINSS referenced to the North 

 American Datum of 1983 (NAD 83) with an accuracy of ±3 m. The Coast Guard 

 differential beacon broadcasting from Brunswick, ME (316 kHz) was used for satellite 

 corrections due to its geographic position relative to PDS. The acmal positions of the 

 REMOTS® and sediment stations were later converted to NAD 27 with the U.S. Army 

 Topographic Engineering Center's CORPSCON (version 3.01) for compatibility with 

 bathymetric data. Positions for Royal River sediment cores were collected using DGPS in 

 NAD 83. 



3.2 Survey Areas 



SAIC conducted four bathymetric surveys and three REMOTS® sediment-profile 

 surveys over the 800 m x 800 m Royal River Project Area centered at 43° 33.805 'N and 



The Portland Disposal Site Capping Demonstration Project, 1995-1997 



