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, 1215 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 



May 1998 



3. REPORT TYPE AND DATES COVERED 



HNAL REPORT 



4. TITLE AND SUBTITLE 



A PREDICTIVE MODEL FOR SEDIMENT TRANSPORT AT THE PORTLAND DISPOSAL SITE, 

 MAINE 



6. AUTHOR(S) 



Waterways Experiment Station -Coastal and Hydraulics Laboratory 



5. FUNDING NUMBERS 



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



U.S. Army Engineer, Waterways Experiment Station -Coastal and Hydraulics Laboratory 

 3909 Halls Ferry Road 

 Vicksburg,MS 39180-6199 



8. PERFORMIGORGANIZATION 

 REPORT NUMBER 



9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 



US Army Corps of Engineers-New England District 



696 Virginia Rd 



Concord, MA 01742-2751 



10. SPONSORING/MONTTORING 

 AGENCY REPORT NUMBER 



DAMOS Contribution #122 



11. SUPPLEMENTARY NOTES 



Available from DAMOS Program Manager, Regulatory District 

 USACE-NAE, 696 Virginia Rd, Concord MA 01742-2751 



12a. DISTRIBUTION/AVAILABILITY STATEMENT 



Approved for public release; distribution unlimited 



12b. DISTRIBUTION CODE 



13. ABSTRACT 



A mmierical model, used to predict the long term fate of sediments (LTFATE), was applied to assess the potential stability of 

 sediment caps at the Portland Disposal Site, Maine. The modeling was performed by the Coastal and Hydraulics Laboratory of the U.S. 

 Army Corps of Engineers, Waterways Experiment Station for the New England District. 



The results showed that a cap of 50-100 cm thick, composed of sediments similar to those used in the model, would provide 

 protection for the capped sediments even under extreme wave conditions of 14.8 m (48 ft). Using conservative parameters, the model 

 predicted erosion from such waves might remove 1 1-22 cm of a cap. Thus, capped sediments (imder a 50-100 cm cap) are not likely to 

 be at risk of erosion and would remain within the disposal moimd. 



Depending on the characteristics of the sediments chosen as cap material, actual site losses could be significantly lower than 

 model estimates. Therefore, once a sediment is chosen for cap material, laboratory and field experiments should be performed to 

 determine the erosion potential for these sediments. In addition, further monitoring of the PDS to measure on- and off-site sediment 

 concentrations, bottom roughness, and near bottom hydrodynamics would increase model accuracy. Other factors not accoimted for in 

 this modeling effort, such as estimates of sediments transported to and possibly deposited at the PDS, would tend to further reduce the 

 estimate of actual erosion. 



Model calibration was accomplished using data provided from a field sampling array that was deployed during events with 

 waves ranging up to 5.4 m (17.7 ft) in height. Severe historical wave conditions were determined through the use of the Wave 

 Information Study (WIS) hindcast for the Atlantic Coast and the ADCIRC ocean circulation model. This included custom refmement of 

 the ADCIRC model grid in the New England region to provide more accurate predictions.. 



14. SUBJECT TERMS sediment caps, capped sediments, cap material 



15. NUMBER OF PAGE 23 



16. PRICE CODE 



17. SECURITY CLASSIFICATION OF 

 REPORT Unclassified 



18. SECURITY CLASSIFICATION 

 OF Tins PAGE 



19. SECURITY CLASSIFICATION 

 OF ABSTRACT 



20. LIMITATION OF 

 ABSTRACT 



