a shipboard portable computer for subsequent analysis. A 20 foot Privateer, owned and 

 operated by the University of Connecticut, was the boat used for all field surveys and array 

 servicing. 



3.0 RESULTS 



3.1 Field Surveys 



Of eleven field surveys attempted, nine were successful. One survey was abandoned 

 due to inclement weather, and a second survey terminated due to mechanical difficulties on 

 the dredge. The nine completed surveys, encompassing 65 transects, were conducted while 

 Great Lakes Dredge #54 was operating in the interior reaches of New Haven Harbor. Reach 

 limits, defined by Great Lakes Dredge and Dock, Co., are shown in Figure 3-1. Daily 

 volumes of dredged sediment from the various reaches are plotted in a histogram (Figure 3- 

 2). The barge used an open clamshell bucket with a capacity of 19.9 m\ The surveys 

 spanned the period from October 25 through November 18, 1993. Local weather and tidal 

 conditions observed for each survey are summarized in Table 3-1, as well as the latitude and 

 longitude of the barge location, and sampling activities. Dredge locations for all of the 

 surveys are shown in Figure 3-3. The locations were determined by encircling the barge 

 while running the GPS; if GPS was unavailable a symbol is used to denote the barge. A 

 time series of the meteorological conditions, recorded at Norwalk Harbor by Northeast 

 Utilities, during the dredging period is shown in Figure 3-4 and a summary in Figure 3-5. 

 All of the echo sounder traces recorded are presented in Appendix A; plotted casts from the 

 CTD are located in Appendix B. 



The first survey took place on October 25; the dredge was located near the United 

 Illuminating Company electric generating facility on the eastern side of the harbor (Figure 3- 

 6). Echo sounder transects were run during the end of the ebb; tidal currents were slacking. 

 The horizontal distribution of the dredge-induced sediment plume for this survey, and all 

 subsequent surveys, is displayed as a heavy line^on a transect (e.g., Figure 3-6, A) whenever 

 material was present in the vertical. The resulting traces indicate that a plume is advected 

 downstream within the confines of the channel for a distance of at least 250 meters (Figure 

 3-7). Throughout this survey the dredge was located near the United Illuminating outfall; 

 thus, it is difficult to determine whether or not all of the echo sounder record is directly 

 attributable to dredging operations (e.g., Figure 3-8). There is no indication of the plume, 

 regardless of its source, migrating cross-channel to the bounding shallows along the western 

 edge. Water samples collected near the United Illuminating outfall do show a significant 

 decrease in the ambient salinity (Table 3-2). Specifically, samples #21 and #26 are 19.9 and 

 21.6 practical salinity units (psu), as compared to an average of approximately 26.5 psu for 

 all surface water samples collected. 



Dredged Sediment Dispersion in New Haven Harbor 



