REPORT DOCUMENTATION PAGE 



Form approved 

 0MB No. 0704-0188 



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. 1. AGENCY USE ONLY (LEAVE BLANK) 



2. REPORT DATE 



November 1996 



3. REPORT TYPE AND DATES COVERED 



Final report 



.TrrLE AND SUBTITLE 



An Investigation of the Dispersion of Sediments Resuspended by Dredging Operations 

 In New^ Haven Hart)or 



5. FUNDING NUIMBERS 



B. AUTH0R(S) 



W. Frank Bohlen, M.M. Howard-Strobel, David R. Cohen, Eric T. Morton 



|7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 



Science Applications International Corporation 

 221 Thrid Street 

 Newport, Rl 02840 



B. PERFORMING ORGANIZATION REPORT 

 NUMBER 



9. SPONSORiNGyMONITORlNC AGENCY NAME(S) AND ADDRESS(ES) 



US Army Corps of Engineers-New England Division 

 424 Trapelo Road 

 Waltham. MA 02254-9149 



10. SPONSORING/ MONITORING AGENCY 

 REPORT NUMBER 



DAMOS Contribution 

 Number 112 



11. SUPPLEMENTARY NOTES 



Available from DAMOS Program Manager, Regulatory Division 

 USACE-NED. 424 Trapelo Road. Waltham, MA 02254-9149 



12a. OlSTRIBUTION/AVAILABILrrY STATEMENT 



Approved for public release; distribution unlimited 



t3.ABSTRACf ~ 



12t). DISTRIBUTION CODE 



Maintenance dredging involving the removal of 840,000m3from the New Haven Harbor main navigational channel toolc place between October 1993 and 

 January 1994. Concern about the transport and fate of the resuspended sediments resulting from the dredging operations was expressed by the State of Connecticut's 

 Department of Environmental Protection PEP). The problem cantered on the shallow water areas llaniung tiie navigation channel which had been identified as winter 

 flounder spawning grounds. An agreement was reached wherein field surveys, using an acoustic echo sounder, would be conducted while the dredge was operating. 

 Additionally, a bottom-mounted instrument array, recording suspended sediment concentrations and other hydrographic parameters, vrauld be deployed near the site of 

 the flounder spawning grounds. This monitoring of the dredged sediment plume would provide a case history for future reference. 



The two major objectives of the study were 1) establish wtiat the bacicground suspended sediment concentration is before and after dredging, and 2) documeirt 

 the movement ctf the dredge plume nsialiva to fishery resource areas such as winter flounder spawning grounds. 



The result of the acoustic sunrays revealed that the dredge-induced sediment plume did protrude into the shoals area to the east and wast of the main 

 navigation channel. These excursions onto the siioals occurred only when the dredge was in the immediate vicinity. The DAISY, which was deployed on the eastern 

 edge of the winter flounder spawning area, also showed elevated suspended material concentrations attributable to the dredge operating in the upper reaches of the 

 harbor. The time series of the DAISY data shovi/ed numerous aperiodic short duration spiltes of approximately 1 00 mg-1-< . The observed concentrations were an order of 

 magnitude larger tlian the preceding bacicground concentrations. However, in the last half of the deployment, while the dredge was located well south of the DAISY site, 

 there were several long duration (1-3 days), very high concentration perturbations. During these events concentrations reached 700 mg -1-1 wrtiich could not be related to 

 dredging operations. Evidence from the meteorological data and sevrage effluent records indicate that these events are likely a result of winds and wind-generated 

 waves, alone or in combination vnth, discharges from vrastevrater treatment plant outfalls. 



Based on these findings, dredge induced sediment resuspension is a minor perturbation relative to the much longer duration, larger amplitude events 

 associated with wind, wind-vi;aves , and effluent discharges from outfalls . The effects of dredging related spikes in suspended sediment on the winter flounder spawning 

 grounds, and the regional water quality in general appear limited in duration and of relatively low amplitude. 



14. SUBJECT TERMS 



DAMOS CT Department of Enviromental Protection (DEP), acoustic surveys. The DAISY, dredging 

 plumes, sediment resuspension 



16. PRICE CODE 



16. NUMBER OF PAGES 



12 



17. SECURITY CLASSIFICATION OF REPORT 



Unclassified 



18. SECURITY CLASSIFICATION OF THIS 

 PAGE 



19. SECURITY CLASSIFICATION OF 

 ABSTRACT 



20. UMITATION OF ABSTRACT 



