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between the upper and middle zones of the Royal River where the pseudo-UDM and CDM
met, were selected from archived cores and were processed at the SAIC Environmental
Testing Center (Figures 2-5 and 2-10). All cores consisted of black silty clay, but had an
oxidized (gray) exterior. Because of the paucity of microfossils in many of the sediment
samples from the upper reach of the Royal River during the original analysis, one of the
additional cores (RR-3) was split into two sections to evaluate the effect of the
preservative. For this discussion, the sample preserved in formalin is referred to as RR-
3F, and the sample preserved in methanol is referred to as RR-3M.

Mineralogy. The coarse fraction from the top of the cores contained plant parts,
wood chips, and shell fragments. Large bivalve moUusca fragments and an intact
gastropod were found in Core RR-6. The fine fraction of the cores contained many of the
trace components seen previously in the Royal River (Table 4-2; Figure 4-30). Samples
RR-3M and RR-3F were identical in terms of mineralogical analysis, and so the data are
shown only once on Figure 4-30. Quartz was predominant in all samples with micas
common. Black porous material and plant fragments were common at RR-6 and RR-3,
and very abundant in RR-5. Dark minerals, flyash, insect parts, and planktonic diatoms
were rare. One textured ostracod was found in RR-6. The samples collected from the
additional cores were similar in mineralogical composition to surrounding Cores RR-8,
RR-15, and RR-26 and represent a combination of the upper and middle region means.
Fibrous minerals and bryozoan fragments, indicators of the outer river region, were absent
in all cores. Rare shell fragments in the additional cores were more typical of the upper
and middle regions than their more common occurrence in the outer region.

Microfossils. The total number of individual microfossils was higher in the
additional cores despite having been stored for over 18 months. Calcareous species
(mudflat and shelf calcareous foraminifera, ostracods), however, were reduced in
abundance relative to the original Royal River core analyses. This may be due to
dissolution of the calcareous specimens (agglutinated species consist primarily of silica).
Only Core RR-6 had a significant number of both mudflat and shelf species, which
potentially were protected from dissolution by the high concentration of calcium carbonate
of large calcareous bivalve fragments embedded in the core. The data from the additional
cores, therefore, probably do not represent the acmal calcareous foraminifera or ostracod
populations at these sites.



The Portland Disposal Site Capping Demonstration Project, 1995-1997



108



Royal River Mineralogy for Additional Cores



Coarse/ -( 5
Abundant



0.5 -





i




rrlr|tr|-



RR-6



RR-5



RR-3



H Grain size

■ Black porous material
DDark minerals
DFIyash

■ Fibrous minerals
DRock fragments
E3 Insect parts

D Plant fragments
9 Benthic Diatoms

■ Planktonic Diatoms
D Textured Ostracods
[l Smooth Ostracods

■ Pellets

■ Shell fragments

11 Gastropod fragments

■ Bryozoan fragments



Royal River Samples Mineralogy Means



Fine/
Rare




No. Of
Samples



UPPEK
3



MIDDLE OUTER

5 3



D Grain size

■ Black porous material
nDari< minerals
DFIyash

■ Fibrous minerals
El Rock fragments
mnsect parts

D Plant fragments

■ Benthic Diatoms

■ Planktonic Diatoms
D Textured Ostracods
13 Smooth Ostracods

■ Pellets

■ Shell fragments

H Gastropod fragments
II Bryozoan fragments



Figure 4-30. Histograms of abundance (rare, common, abundant) and grain size (fine,

medium, coarse) for the mineralogical components of (A) the three additional
Royal River cores, in comparison with the (B) mean mineralogical
composition for the baseline Royal River cores

The Portland Disposal Site Capping Demonstration Project, 1995-1997



109^

In the additional Royal River cores, thecamoebians varied from 7% to 17% in the
samples (Figure 4-31 A). In composition, the microfossils in the cores were comparable to
RR-26 located in the upper middle reach, with the exception of mudflat calcareous
specimens. The percentage of thecamoebians in the additional cores was close to that in
RR-26 and increased with the proximity of the core location to the upper river region.

Marsh foraminifera were predominant in all samples, however, many of them had
poorly preserved shells. Mudflat calcareous foraminifera were absent in RR-3F and RR-
3M, and composed only a small percentage of RR-5 and RR-6. Shelf calcareous
foraminifera were found in RR-6, and shelf agglutinated foraminifera varied from 0.6% to
4% in the four cores. One of the shelf agglutinated specimens in RR-6, Martinotiella
communis, was not seen in any of the prior samples from the Royal River or at the PDS.
The small percentage of shelf agglutinated foraminifera was greater than previously seen in
the Royal River cores in which only one had been observed in RR-26. The shelf
calcareous foraminifera also had a greater abundance in RR-6 than seen before at RR-18 in
the middle region.

Comparison of formalin and methanol solutions in samples from RR-3 was limited
to the preservation of non-calcareous species due to the apparent dissolution of the
calcareous fraction. Almost double the number of thecamoebians and a few more shelf
agglutinated specimens were counted in the RR-3M (methanol) samples dian found in the
RR-3F (formalin) samples (Figure 4-31B). The microfossil content in the three additional
cores had a greater density than in the Royal River cores processed in 1995, which had
been preserved in methanol, possibly reflecting the difference in preservation solution
used. However, because the formalin and methanol preserved solutions were similar in the
numbers per tray, the greater density probably was representative of a larger
microorganism community in this transition area between the upper and middle regions.

The additional Royal River cores were classified with respect to the actual dredging
plan as follows: RR-6, pseudo-UDM (phase 1); RR-5, pseudo-UDM (phase 2) near the
border with CDM; and RR-3, CDM (Figure 2-10). The cores did not have distinct enough
characteristics to classify them as separate regions, therefore, the later portion dredged for
CDM shared some characteristics with the pseudo-UDM.

The microfossil abundance and total number (the density was not calculated for the
additional cores) of the additional cores were comparable to the PDS grab and core
samples. Although the mudflat calcareous specimens were reduced in the additional cores,
the pseudo-UDM grab and core sample means were more consistent with Cores RR-6 and
RR-5 than those previously described for the upper region. The additional cores provided
evidence that some of the shelf species in the CDM, pseudo-UDM core, and pseudo-UDM
grab samples were probably derived from the areas surrounding Cores RR-3, RR-5, and
RR-6 in the Royal River.

The Portland Disposal Site Capping Demonstration Project, 1995-1997



no





Royal River - Relative Abundance




a>

C 80%




:■?'*:;:




'■'0<.




















n Freshwater the.


































DMarsh Ag.




§ 60% -




















DMudtiat Ca.




£i
<




















13 Shelf Ag.




<u 40% -
>

IS

oS 20% -




















■ Shelf Ca.












Di






























RR-6 RR-5 RR-3F RR-3M






Core Locations


A





B



No. of
Trays

ISO-
i2l60



-100

o

w 80

d)

Si 60
E
3 40

20





Royal River Numbers of Individuals Counted

3 4 4 4



ID Freshwater the.
DMarsh Ag.
DMudflat Ca.
B Shelf Ag.
■ Shelf ca.



RR-6



RR-5 RR<3F

Core Locations



Figure 4-31. Histograms of relative abundance of microfossils and the numbers of

individuals counted for the given number of trays analyzed for additional
Royal River cores. Core RR-3 had similar abundances of microfossils
preserved in formalin (F) and methanol (M)

The Portland Disposal Site Capping Demonstration Project, 1995-1997



111_

4.7 Multivariate Statistical Analysis of Fine Fraction Results

Multivariate statistics were used to evaluate whether there were statistically
significant differences between the three layers (CDM, UDM, and AMB) classified from
the postcap cores. As described in Section 3.10, several statistical methods were used,
with the primary difference dependent on how the data were prepared. For clustering and
MDS results (Section 4.7.1), the samples were analyzed prior to the layer classifications.
Two statistical tests were conducted on the sample groups using the classifications derived
after visual and microfossil results were compiled: an analysis of similarities test (Section
4.7.2), and an evaluation of discriminant statistics (Section 4.7.3). The analysis of
similarities tested the null hypothesis that there was no difference between the UDM and
CDM layers from the postcap cores. The discriminant statistics were then utilized to
visually show the strength of the layer differences using both microfossil and mineralogical
results.

4.7.1 Clustering and Multi-Dimensional Scaling Results

The fine fraction mineralogy and microfossil results were analyzed to determine the
statistical similarity (cluster) and dissimilarity (MDS ordination) between samples, and to
quantitatively evaluate the strength of any resultant clustering among the samples. More
detailed information on the statistical methods is available in Section 3.10. The results are
provided in a variety of graphical formats in the figures below. In order to better interpret
the information, we first briefly describe the statistical output, and how it is presented.

The first analysis that we conducted, using the PRIMER clustering program (Bray-
Curtis similarity index), independently determined the similarities between sample data
points based on multiple variables, and then grouped them accordingly to generate a
similarity matrix. The matrix of samples was created with the similarities linked, with the
links shown in a hierarchy and displayed on a dendrogram. The dendrograms provided
below display the agglomerate clustering based on similarity. The higher the level of
groupings on the dendrogram, the more similar those groups of samples were, relative to
the mineralogy composition or the microfossil community structure.

The second test, a non-metric multi-dimensional scaling (MDS), provided an
ordination, or map, of samples showing the inter-relationships between samples on a
continuous scale. The ordination plots shown in the results below were constructed by an
iterative procedure, which successively refined the positions of the samples to reflect the
similarity relations between individual samples. The MDS method was used to produce a
two-dimensional representation of the data from a three-dimensional dataset as shown in
the ordination plot, and calculated a value called "stress" which provided an indication of
the fit of the data in two-dimensional (2D) space. Stress values of up to 0. 1 correspond to
good to excellent 2D representation, values of up to 0.2 indicate the results are useful but

The Portland Disposal Site Capping Demonstration Project, 1995-1997



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



113



Table 4-9



Sample Identification for Statistical Analyses


Sample No.


Core


Depth (cm)


Core Layer


1


A -9


6-10


CDM


2


A -9


16-20


CDM


3


A -9


30-34


CDM


4


A-9


39-43


UDM


5


A-9


48-52


UDM


6


A-9


53-57


UDM


7


B-1


3-7


CDM


8


B-1


10-14


CDM


9


B-1


18-22


UDM


10


B-1


24-31


UDM


11


C-1


0-4


CDM


12


C-1


7-11


UDM


13


C-1


15-19


UDM


14


C-1


26-30


AMB




C-1


40-44


AMB


16


D-2


2-6


CDM


17


D-2


8-12


CDM


18


D-2


19-23


UDM


19


D-2


25-29


UDM


20


D-2


34-37


UDM


21


E-6


2-6


CDM


22


E-6


8-12


CDM


23


E-6


18-22


CDM


24


E-6


30-34


CDM


25


E-6


40-44


UDM


26


E-6


45-49


UDM


27


E-6


50-54


UDM


28


E-6


55-60


UDM


29


E-6


65-69


UDM


30


G-2


4-8


CDM


31


G-2


10-13


UDM


32


G-2


24-28


UDM


33


G-2


32-36


AMB


34


G-2


52-56


AMB


35


I-l


0-4


CDM


36


I-l


8-12


CDM


37


I-l


15-19


CDM


38


I-l


22-26


UDM


39


I-l


27-28


UDM


40


I-l


40-44


UDM



The Portland Disposal Site Capping Demonstration Project, 1995-1997



114



A.




50. 60. 70. SO.

Bray-Curtis Index, %



B.



CDM

# Ambient
O > 68% Similarity



©



Microfossil Data



@)





< Relative Distance b/n Samples >



Figure 4-32. (A) Dendrogram of hierarchical agglomerate clustering using Bray-Curtis
similarity index of microfossil data from PDS cores. (B) 2-D multi-
dimensional scaling ordination plot (Stress = 0. 12) calculated from ranked
similarity matrix of microfossil data. Sample nvmibers described in Table 4-9,
see text for explanation of color scheme

The Portland Disposal Site Capping Demonstration Project, 1995-1997



115



A.



B.



^



{^



70. SO.

Bray-Curtis Index, %







Mineralogy Data


A







fl)






o_






£






" /"


~x


25 ^,^ — \


c /


\ 31 36 38


^^ 34 1








•C"


\ 6


13 / /


(D






H V,


J '° ,8


/15 /^


i ^


-^ 32


Ov L^^^'^


b


39

26/











^


/O '^


I





6^ r — ^






1$


*— ^ 28


j


CDM


V


y 29


y


## UDM




\^ 27^




# Ambient




< Relative Dist




O > 68% Similarily


ance b/n .


amples >



1 5
33
34



Figure 4-33. (A) Dendrogram of hierarchical agglomerate clustering using Bray-Cvirtis
similarity index of mineralogy data from PDS cores. (B) 2-D multi-
dimensional scaling ordination plot (Stress = 0.21) calculated from ranked
similarity matrix of mineralogy data. Sample numbers described in Table 4-9,
see text for explanation of color scheme

The Portland Disposal Site Capping Demonstration Project, 1995-1997



116

As with the microfossil plots, 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. The MDS plot does show general groupings of the
samples with some overlap between the CDM and pseudo-UDM samples.

4.7.2 Analysis of Similarities

After analyzing the microfossil and mineralogical results of the core samples and
conducting clustering analysis, there was an overlap of characteristics between pseudo-
UDM and CDM. Therefore, a null hypothesis was tested to determine the statistical
significance of the difference between CDM and pseudo-UDM samples. Again, the null
hypothesis was that no differences existed between the CDM and pseudo-UDM samples.

An ANOSIM randomization test was conducted on microfossil data. ANOSIM is
based on a non-parametric test analogous to standard parametric analysis of variance
(ANOVA). For this test, the classification of the samples occurred prior to analysis and
ambient samples were not included. The test compared the difference between the CDM
and pseudo-UDM samples with the differences in the samples within each group displayed
on the MDS plot. The program calculated a global R value of 0.297. The null hypothesis,
that no differences exist between the CDM and pseudo-UDM samples, was rejected with a
significance level of p < 0.001.

4.7.3 Discriminant Statistics

Using SPSS® Professional Statistics 6.1, we performed a discriminant statistical
analysis on the mineralogy and microfossil results from the core samples. Discriminant
statistics is a multi-variable technique to measure the degree of association between groups
of data. Because the groups were pre-determined based on the visual descriptions, the
success of discriminant classification allowed an estimate of the acmal differences or
similarities between groups.

The microfossil data were grouped into five categories for this analysis: freshwater
thecamoebians, marsh foraminifera, mudflat foraminifera, shelf agglutinated foraminifera,
and shelf calcareous foraminifera. The relative abundance of the five groups of species
were calculated for individual samples. Mineralogical parameter abundances were used as
described above. Each sample was then grouped with the AMB, pseudo-UDM, or CDM
classifications based on the visual core descriptions and on microfossil analyses.

Following separation into groups, the group means, standard deviation, and
discriminant scores were calculated, and the scores were graphed according to two
canonical discriminant functions. The canonical functions represented the ordination axes
that best separated the pre-determined groups. The SPSS program then determined the
The Portland Disposal Site Capping Demonstration Project, 1995-1997



m



percentage of samples appropriately classified into the pre-determined groups.

Discriminant statistical analyses of both the mineralogic composition and the
microfossil assemblage classified 95 % of the core samples correctly according to the
designated layer. The graphs display three clusters of core samples which were described
by two canonical discriminant functions (Figure 4-34). The first function presents the
largest difference in the sample group based on the multi-variable composition, which
clearly separated the AMB material from the disposed dredged material. The second
function determines the next largest difference between the layers; the pseudo-UDM and
CDM were more closely associated, though distinguishable. Similar to the MDS
ordination plot, the microfossil discriminant scores showed denser clusters with greater
distances between layer means than the mineralogy. The mean values for each layer
(CDM, pseudo-UDM, ambient) was marked. The top samples of pseudo-UDM, from
cores with more than one pseudo-UDM sample, are marked on the graph and tended to be
close to the CDM cluster on both graphs.



The Portland Disposal Site Capping Demonstration Project, 1995-1997



118





Mineralogy Discriminant Scores






CDM










■ UDM


^








aAMB










X UDM top


^. ■




«M


■ Layer Means


■i







o

3

u.


X_j 1 < 1

1
A ■






-X ' ' '


-12 -10 -8 -6 -4 -2 2 4 6 i


3






X















A -2 -J








-3 -








"^






Function 1





B









Microfossils Discriminant Scores






















CDM















■ UDM
aAMB


^



■■■




Function 2


A





• Gr. Means
X UDM top







i


2


A

-10


' A ' ' ' "

-8 -6 -4 -2 (


) "" 2 4 6 (





















-2 -


X




















Function 1





Figure 4-34. Plots of (A) mineralogy and (B) niicrofossil discriminant scores showing
distinct clusters of samples according to layers in PDS cores

The Portland Disposal Site Capping Demonstration Project, 1995-1997



119

5.0 DISCUSSION

5.1 Assessment of the Footprint of the Capped Disposal Mound

The demonstrated ability to form a discrete deposit of dredged material on the
complex topography of the seafloor at the PDS was a key element to the success of the
Royal River Project. Prior to the project, the DAMOS Capping Model was used to predict
the size of the capped dredged material mound. The Capping Model is a tool to
approximate the size of a mound formed from point dumping of material in a specified
water depth. This model has proven useful in managing the deposition of dredged material
at other disposal sites with subtle relief. This model does not include a correction for
bottom topography. Therefore, the measured footprint of both the pseudo-UDM and CDM
deposits on the floor of PDS was evaluated relative to the shape of the mound as predicted
by the DAMOS Capping Model.

Based on the amount of dredged material disposed at the PDA buoy during the
Royal River Capping Experiment (39,500 m^ pseudo-UDM and 22,200 m^ CDM), the
DAMOS Capping Model predicted the formation of a conical pseudo-UDM deposit
approximately 1.2 m high, with flanks extending up to 250 m from the central point of
disposal, and a 20 cm thick cap. Although the capping volume was less than what is
generally required in an acmal capping project (>50 cm), the model was still considered
useful despite the small volumes used. These results were assessed in light of the
measured deposit of pseudo-UDM (Section 5.1.1) and cap (Section 5.1.2) material.

5.1.1 Pseudo-Unacceptably Contaminated Dredged Material (Pseudo-UDM)

Typically in a capping project, sequential bathymetric surveys are used to determine
the overall shape and height of a disposal mound > 20 cm thick (the resolution of the
bathymetric method), and sediment-profile photographs are then used to map the apron of
material of < 20 cm. In the Royal River Project, bathymetry detected accumulation of
dredged material in close proximity to the PDA buoy position following disposal of the
pseudo-UDM. The bathymetric footprint consisted of two lobes, with an overall width of
approximately 300 m (Figure 4-12). The footprint of the mound was concentrated within
the namrally occurring basin feamre detected in the southern quadrant of PDS.

Due to the complex bottom topography at PDS, however, there was a degree of
uncertainty associated with the bathymetric results due to survey artifacts from replicate
surveys over strong topographic feamres. The result is that the thickness of dredged
material may have been overestimated in areas, especially along the eastern lobe which was


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