REPORT DOCUMENTATION PAGE 



Form approved 

 OMB No. 0704-0188 



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 any other aspect of this collection of information including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information 

 Observations and Records, 1 21 6 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302 and to the Office of Management and Support, Paperwork Reduction 

 Project (0704-0188), Washington, D.C. 20503. 



1 . AGENCY USE ONLY (LEAVE BLANK) 



2. REPORT DATE 



January 1996 



3. REPORT TYPE AND DATES COVERED 



Final report 



4. TITLE AND SUBTITLE 



Synthesis of Monitoring Surveys at the Cornfield Shoals Disposal Site, July 1991 to 

 May 1992 



5. FUNDING NUMBERS 



6. AUTHORS) 



M. Baker Wiley 



7. PERFORMING ORGANIZATION NAMEfS) AND ADDRESSES) 



Science Applications International Corporation 

 221 Thrid Street 

 Newport, Rl 02840 



B. PERFORMING ORGANIZATION REPORT 

 NUMBER 



SAIC-C106 



9. SPONSORING/MONITORING 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 105 



11. SUPPLEMENTARY NOTES 



Available from DAMOS Program Manager, Regulatory Division 

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



12a. DISTRIBUTION/AVAILABILITY STATEMENT 



Approved for public release; distribution unlimited 



12b. DISTRIBUTION CODE 



13. ABSTRACT 



Preliminary evidence of active bed transport at the Cornfield Shoals Disposal Site (CSDS) prompted the National Marine 

 Fisheries Service and Connecticut Department of Environmental Protection to express concern about possible sediment transport 

 towards, and impact on, shellfish beds located north of the site, north of Long Sand Shoal. This preliminary study was designed to 

 determine if the field-observed transport at the disposal site is consistent with the predicted east-west transport pattern found in the 

 historical record. 



This investigation at CSDS between July 1991 and May 1992 provided strong circumstantial evidence for active bed transport. 

 This study included a series of bathymetric surveys, current meter suspended sediment data collection, and REMOTS photography of the 

 sediment-water interface. The circumstantial evidence for active bed transport included shifts in areas of sediment accumulation and 

 erosion, increased suspended sediment deposits at the sediment-water interface. In general, active bed transport appears to follow the 

 historical east-west current direction, and the extent of the transport depends on the type of material. The actual direction and magnitude 

 of active bed transport apparently depend on local topography and the nature of materials being transported. 



Sediment accumulated over a broad area near the disposal points of sand hydraulically dredged from the Connecticut River in 

 September 1991. Subsequent bathymetric surveys showed apparent movement of this material to the west. A clearly defined deposit 

 formed at the disposal point for fine-grained material mechanically dredged from North Cove, Connecticut. This deposit of fine-grained 

 dredged material apparently did not move, but was partially covered by bedload transport of adjacent coarse-grained sediments. 



The present study concluded that: 



The predominant transport direction at the site appears to be east-west . This is supported by current meter deployments and 

 observed erosion and deposition patterns. 



Sediment disposed at the side was not immediately dispersed and was defined within discrete deposits. This was observed for 

 both fine-grained and sandy sediments. 



The dispersion process appears to occur over a period of weeks to months. The dispersion rate for fine-grained materials may 

 be markedly slowed by sand armor that migrates over the more cohesive, less erosive silt-clay. 



The above findings, taken over the ten month time period, reduce concerns about far field transport of material over oyster beds 

 to the north. The dispersion of material over a time scale of years, and the effectiveness of the sand armor over the silt-clays are 

 unknown. 



14. SUBJECT TERMS 



bathymetric surveys REMOTS CSDS DAMOS 



15. NUMBER OF PAGES 



30 



16. PRICE CODE 



17. SECURITY CLASSIFICATION OF REPORT 



Unclassified 



18. SECURITY CLASSIFICATION OF THIS 

 PAGE 



19. SECURITY CLASSIFICATION OF 

 ABSTRACT 



20. LIMITATION OF ABSTRACT 



