112 



should be used with additional statistical techniques, and stress values of up to 0.3 indicate 

 that the values are almost arbitrarily located in the 2D ordination plot. 



Following the creation of the cluster dendrograms and MDS ordination plots, 

 individual samples were colored according to their original classification: AMB is red, 

 pseudo-UDM is blue, and CDM is yellow. The results of both the cluster and MDS 

 analyses are presented together in order to evaluate the overall ability to distinguish the 

 three groups of samples. 



Microfossils. Statistical analysis on the microfossil data showed that the AMB 

 samples were most similar to each other, while there was overlap between the pseudo- 

 UDM and CDM samples (Figure 4-32). The dendrogram indicated that the AMB samples 

 shared approximately 22% similarities with the dredged material samples. The ordination 

 plot was consistent with the dendrogram, showing a distinct cluster for AMB samples, and 

 less distinct clusters for CDM and UDM (Figure-4-32). The CDM and pseudo-UDM 

 samples were distinguishable, but more closely associated to each other (sharing more 

 similarities, therefore overlapping clustering on the ordination plot) than with the AMB 

 samples. The CDM samples were clustered more compactly than the pseudo-UDM 

 samples in microfossil analyses. The low stress value (0.12) of the MDS plot indicates 

 that the two-dimensional depiction was an accurate representative of statistical groupings. 



In order to further clarify the clusters on the ordination plot, the pseudo-UDM 

 samples were divided into different shades of blue according to the clustering on the 

 dendrogram. Samples that shared 68% or greater similarities were circled. All four 

 pseudo-UDM samples circled with the CDM were located at the top of the pseudo-UDM 

 interval in the cores. Samples 31 and 25 both contained a small pocket of sand that may 

 have been from the disposal of CDM (Table 4-9). Sample 10, from the lower part of the B 

 core, showed similarity to the AMB samples because it contained foraminifera found only 

 on the continental shelf and most likely contained some ambient (or historical dredged) 

 material. 



Mineralogy. The dendrogram and ordination plot of the mineralogy results (Figure 

 4-33) showed a clear distinction between the ambient and dredged material samples, as in 

 the microfossil results, but a more blurred grouping of CDM and pseudo-UDM samples. 

 The ambient samples were isolated from the rest of the samples on the dendrogram. Two 

 small groups of C^DM samples and one group of five pseudo-UDM samples shared 68 % 

 similarity in mineralogy composition (Figure 4-33). Many CDM and pseudo-UDM 

 samples were grouped together. The moderate-to-high stress level of the mineralogy 

 ordination plot (0.21) indicated that the 2D representation of the groups MDS plot was 

 useful, but should be evaluated in light of alternate statistical tests. 



The Portland Disposal Site Capping Demonstration Project, 1995-1997 



