12 



collected for potential future analysis of grain size. The other half was photographed and 

 archived in a refrigerated coring facility for potential future evaluation. 



2.3 Acoustic Survey Operations 



Survey operations were conducted aboard the survey vessel Cyprinodon (CR 

 Environmental) on 10 October 1997. Those involved in the survey included SAIC, the 10, 

 one MIT student, and two pilots from CR Environmental. The PINSS navigation system 

 was used for all navigation. Survey lanes were designed using the estimated locations for 

 the four comers of the cell (ENSR 1997a). Survey lanes for bathymetry (Section 2.3.1) 

 and subbottom (Section 2.3.2) were planned using the PINSS survey planning module to 

 cover the area of the cell and one survey lane outside in all four directions. PINSS 

 computed towfish position for the subbottom and side-scan sonar fish using a cable layback 

 calculation and provided this position to the data collection system. Side-scan sonar 

 operations were conducted following the bathymetry and subbottom surveys on the same 

 day (Section 2.3.3). 



2.3.1 Bathymetric Data Collection and Analysis 



Depth soundings were collected with an Odom DF3200 Echotrac® survey 

 echosounder using a 208 kHz transducer with a 3° beam angle. The Odom simultaneously 

 displayed water depth data on a chart recorder and transferred the digital sounding data to 

 the PINSS. The echosounder collected 6-8 soundings per second and transmitted an 

 average value to the PINSS at a rate of one sounding per second. Depth soundings were 

 collected along pre-configured survey lanes with 15 meter spacing in both E-W (14 lanes) 

 and N-S (8 lanes) orientations. 



A Seabird Electronics, Inc. Model SBE 19-01 conductivity-temperature-depth 

 (CTD) profiler was used to acquire a vertical profile of sound velocity in the water column 

 during the day. These data were used to correct the bathymetry data for speed of sound 

 during post-processing. 



Using SAIC's Hydrographic Data Analysis System (HDAS), bathymetric soundings 

 were edited for outliers and corrected for sound velocity, transducer draft, and tidal 

 variation. Tidal data from the Boston Harbor tide station (station #8443970 located near 

 the Northern Avenue bridge) were obtained from the NOAA Ocean and Lakes Levels 

 Division (OLLD) web-server (http://www.olld.nos.noaa.gov). Following the application 

 of all correctors, the depth soundings were spatially averaged to produce a grid of cells. 

 The gridded bathymetric data were used to produce the various topographic maps included 

 in this report. 



All graphics have been plotted in NAD83 latimde/longimde coordinates. Depth 

 values are relative to Mean Low Water (MLW) in order to compare with data provided by 



MONITORING RESULTS FROM THE FIRST BHNIP CONFINED AQUATIC DISPOSAL CELL 



