JO 



However, under- or over-penetration of the camera prism into the sediment prevented 

 analysis of all three replicates at a subset of the stations. 



Towed Video Sled 



A towed video sled operated by CR Environmental, Inc. was used to conduct a 

 benthic video survey over the Morris Cove borrow pit. A high-resolution 8 mm video 

 camera, contained within a specialized pressure housing, was mounted on an aluminum tow 

 sled. The sled was lowered to the seafloor by a mechanical cable and pulled along a series of 

 predetermined transect lines by the survey vessel. Video was recorded on tape by the video 

 camera and simultaneously transferred to the survey vessel via coaxial cable. A topside 

 Super VHS video recording system recorded the images captured by the video camera and 

 provided a time stamp for correlation with navigation data. 



Three longitudinal and four transverse transects were occupied in an effort to assess 

 the distribution of dredged material in the Morris Cove borrow pit. Furthermore, the video 

 was used to characterize the composition of ambient sediment and macrofauna in the pit and 

 surrounding area (Figure 2-4). The position of the tow sled, based on cable layback, was 

 logged continuously by the HYPACK® navigation system during the survey operation. 



Bathymetric Data Collection and Processing 



In addition to displaying vessel position, HYPACK® was interfaced with an Odom 

 Hydrotrac Fathometer for the collection of depth profiles during both the side-scan sonar and 

 towed video surveys. The fathometer was equipped with a narrow beam (3°), 208 kHz 

 transducer to obtain depth soundings to a resolution of 1 cm. Approximately 10 measured 

 depth values were collected, adjusted for transducer depth (draft), and transmitted to 

 HYPACK® at a frequency of 1 Hz. The fathometer data recorded by HYPACK® were 

 averaged, merged with time and position information, and written to a series of navigation 

 log files at a frequency of 2 Hz. At the conclusion of survey, raw depth soundings were 

 plotted over the survey lines to re-create vessel track and verify data quality. 



The bathymetric data were later processed and analyzed using the HYPACK® single- 

 beam hydrographic data processing module. Raw bathymetric data files were standardized 

 to the vertical datum of Mean Lower Low Water (MLLW) using National Oceanographic 

 and Atmospheric Administration (NOAA) observed tides. Observed tidal data were obtained 

 through NOAA's Ocean and Lake Levels Division's (OLLD) National Water Level 

 Observation Network. The NOAA 6-minute tide data for 28 September 2000 were 

 downloaded from http://co-ops.nos.noaa.gov from station (8465705) in New Haven Harbor 

 and used to formulate tidal height correctors. 



Monitoring Cruise at the Morris Cove Borrow Pit 



