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dredged material. The surface layers of this material, as discussed above, should have 

 characteristics much more similar to the ambient sediment (i.e., abundant shelf and 

 planktonic microorganism species), and so therefore would prove to be less of a 

 complication. 



The disposal plan used for the demonstration project was to use the suitable material 

 from the outer reaches of an estuary to cap the sediments from the iimer reach. Using this 

 plan for other projects will result in material from the transitional area that also must be 

 dredged. For a project with larger volumes, the core sampling scheme can be concentrated 

 in narrow ranges of the core that represent the transition from pseudo-UDM to CDM, so 

 that sampling of the middle reach material (presumably at the top of the mound) would be 

 minimized. In addition, if the project volumes are large enough, perhaps the material 

 dredged from transitional reaches, if suitable, could be placed at an alternate disposal 

 location. 



7.3 Sediment Tracer Technique 



Several recommendations were derived from the sediment tracer and statistical 

 analyses: 



• Limit the tracer analysis to the individual components that have the narrowest 

 range in the dredging area in order to decrease the level of effort required to 

 analyze the samples, as well as increase the statistical reliability of sample 

 identification. In hindsight, this analysis could be conducted on the Royal River 

 project data, but for purposes of the demonstration project, a thorough analysis 

 of all components was necessary for evaluation of the tracer technique. 



• For fumre projects, efforts should focus on the microfossil analysis. Mineralogy 

 observations should serve as a supplemental tool. The optimum tracer will be, 

 however, site-specific. 



• For a sufficiently large volume project, focus the sample and statistical analyses 

 on sediment sampled from above and below the ambient/UDM and UDM/CDM 

 boundaries. These boundaries can be preliminarily identified using abundances 

 of shelf and freshwater species, then a detailed analysis of samples near the 

 boundary can be conducted. 



• Sample the ambient material and conduct a tracer analysis prior to initiation of 

 the dredging project. 



• Avoid areas with historical dredged material. If this is impossible and historical 

 dredged material is present in the selected disposal area, sample and analyze the 



The Portland Disposal Site Capping Demonstration Project, 1995-1997 



