REPORT DOCUMENTATION PAGE 



Form approved 

 OMB No. 0704-0188 



Public reporting concern for the collection of Information is estimated to average 1 hour per response including the time for reviewing Instructions, searching existing 

 data sources, gathering and measuring the data needed and correcting and reviewing the collection of information. Send comments regarding this burden estimate or 

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

 Observations and Records, 1216 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302 and to the Office of Management and Support, Paperwork Reduction 

 Protect (0704-0188). Washinqton, 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 



Monitoring Cruise at the Cornfield Shoals Disposal Site, August 1992 



5. FUNDING NUMBERS 



6. AUTHOR(S) 



M. Baker Wiley 



7. PERFORMING ORGANIZATION NAME(S) AND ADDRESSES) 



Science Applications International Corporation 

 221 Thrid Street 

 Newport, Rl 02840 



S. PERFORMING ORGANIZATION REPORT 

 NUMBER 



SAIC-C112 



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 106 



: 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 



After fine-grained dredged material was released at the Cornfield Shoals Disposal Site (CSDS) between October 1991 and May 

 1992, there was evidence that ambient sand was being transported over the fine-grained dredged material deposit. The presence of 

 ambient sand over fine-grained dredged material in REMOTS sediment-profile photographs, current meter studies, and transmissometer 

 and backscatter data all supported active bedload transport in a study conducted at CSDS in 1991/1992. However, the areal extent of the 

 fine-grained dredged material under the sand and the thickness of the sand over the unknown. 



The present study, conducted at the Cornfield Shoals Disposal Site in August 1992, attempted to delineate the extent of the fine 



grained dredged material under the sand and to measure the sand thickness. Part of the May 1992 REMOTS survey was repeated in 



August. All but two stations that were formerly fine-grained dredged material had been covered with sand by August. The new REMOTS 



stations in August were concentrated south of the mapped fine-grained deposit . Dredged material was detected under sand at two 



I stations south of this area, extending the dredged material boundary to the south. 



An acoustic sediment density study was conducted at CSDS to define the surface sediment density and locate the fine-grained 



1 dredged material. It was also conducted to gather the subsurface sediment density information and map the thickness of the sand over 



1 the mud. The surface density values, calculated every 50m along the survey track, did not delineate the fine-grained material that was at 



REMOTS stations G8 and G9. Subsurface densities were measured at 15 cm intervals below the sediment water interface. These 



subsurface densities did not detect any decrease in sediment density with depth, suggesting that the depth to the base of the mud was 



ess than 15cm or that the acoustic survey was unable to detect the density changes. 



The transformation from fine-grained dredged material at the center of the mound to sand over mud or sand at all but two 

 GEMOTS stations (G8 and G9) continues to support the theory that sand is being transported over the fine-grained dredged material at 

 the Cornfield Shoals Disposal Site. This is not unexpected in that the site is dispersive and material is normally transported across and 

 iltimately out of the area. 



The acoustic sediment density study was not successful in locating the fine-grained dredged material either at the center of the 

 lisposal mound or under the sand on the flanks of the deposit. The lack of success with the 24 kHz acoustic survey may have been due 

 n part to the resolution of the system, but attention to and adjustment to varying system parameters in future surveys may result in more 

 successful distinction between subbottom layers. 



I4. SUBJECT TERMS 



acoustic sediment density studies REMOTS CSDS DAMOS fine-grained dredged material 



15. NUMBER OF PAGES 

 97 



16. PRICE CODE 



1 7. SECURITY CLASSIFICATION OF REPORT 



Unclassified 



18. SECURITY CLASSIFICATION OF THIS 

 PAGE 



19. SECURITY CLASSIFICATION OF 

 ABSTRACT 



20. LIMITATION OF ABSTRACT 



