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to or from other regions. Because thecamoebians and mudflat/ marsh foraminifera are all 

 benthic species that live on or in the substrate, transportation of the microfossils was likely 

 limited. The state of naturally preserved foraminiferal tests and ostracods suggested that 

 many individuals were collected near their habitat range. 



Because no single tracer was found that was both 1) unique to the upper or outer 

 reach of the Royal River, and 2) common throughout all of the cores collected in that 

 particular reach, the method of combining data from several parameters to characterize 

 each river zone was found to be the most practical. In this way, a particular sample was 

 classified based on statistical groupings of a variety of parameters. 



5.2.2 Statistical Strength of Tracer Grouping Method 



The statistical methods used to group the samples collected over the Royal River 

 Survey Area at PDS bore out the conclusion that the CDM and pseudo-UDM had 

 overlapping characteristics, primarily due to the ranges of the tracers within the Royal 

 River. In this section, a summary of the statistical conclusions are provided, then a 

 discussion of the discrepancies that were brought out after the statistical analysis. These 

 statistical discrepancies were found to be primarily related to the dredging and disposal 

 operations. 



All of the statistical tests that were conducted on the grab and core samples 

 collected at the Royal River Project Area indicated that the ambient samples were most 

 similar to each other, while there was overlap between the pseudo-UDM and CDM 

 samples. The micro fossil dendrogram indicated that the ambient samples shared 

 approximately 22% similarities with the dredged material samples. The CDM grouping 

 was more distinct than the UDM. In general, statistical analyses showed that tracers can 

 be used to identify disposed dredged material layers removed from different regions of an 

 esmary. However, they are more difficult to distinguish if the material was dredged from 

 nearby regions (i.e., upper and middle) as opposed to separate regions (upper and outer). 

 Also, the tracers were not found to be equally effective in distinguishing material origin. 

 Overall, the biological indicators were statistically more robust than the mineralogical 

 indicators. 



Another major result, replicated by the ordination and discriminant statistical 

 methods, was that four of the pseudo-UDM samples that were most similar to the CDM 

 samples were located at the top of the pseudo-UDM interval in the cores. Because of the 

 phased dredging, the last of the cap material was dredged from the same area as the 

 material from pseudo-UDM Phase 2 (Figure 5-3). The overlap of the CDM and pseudo- 

 UDM groupings, therefore, was consistent with the disposal operations data. In addition, 

 all of the core and grab samples had a lower relative abundance of freshwater 

 thecamoebians and diatoms than the upper region of the Royal River. Thecamoebians and 



The Portland Disposal Site Capping Demonstration Project, 1995-1997 



