^0 



3.1 Recommendations for Future Studies 



It should be reiterated here that results derived from this modeling effort should 

 only be used as a guideline for quantifying erosion potential. The erosion amounts can only 

 be considered approximate without further validation from field data. Assumptions made 

 concerning sediment and site characteristics result in significant model uncertainty. A field 

 data collection effort to determine variation in erosion potential with depth of PDS 

 sediments imder high stress conditions would significantly reduce this uncertainty. In 

 addition, further analysis to determine variation in bottom roughness, variation in the 

 suspended solids plume with height above the water column, boundary condition 

 concentrations, data concerning bottom bathymetry changes during storm periods, data 

 from a large return period (significant wave height approximately 6 m) event, and locations 

 of rocky outcrops verses sediment deposits would further refine the model and reduce 

 imcertainty. Another possibility, if the data were available to support such a model, would 

 be to use a three-dimensional model to more accurately reflect the complex bottom 

 hydrodynamics and sediment transport that are inherent in a complex bottom bathymetry 

 like the PDS. This would require an order of magnitude more detailed modeling effort than 

 the LTFATE screening level model. 



A Predictive Model for Sediment Transport at the Portland Disposal Site, Maine 



