Portland Office
333 SW Fifth Avenue, Suite 608
Portland, Oregon 97204
Tel: (503) 248-5600, Fax: (503) 248-5577
Technical Memorandum
_______________________________________________________________________
To:
Kevin Parrett, Project Manager (DEQ) – Former McCormick and Baxter Creosoting
Company, Portland, Oregon
Date:
December 1, 2006
From:
George Lukert, Task Manager (E & E)
Heidi Blischke, Hydrogeologist (GSI)
Subject:
Organoclay Cap Performance Evaluation – Field Study Report.
________________________________________________________________________
1.0 INTRODUCTION
Ecology & Environment Inc. (E & E) under contract with the Oregon Department of
Environmental Quality (DEQ) (Task Order No. 71-03-28) and Groundwater Solutions,
Inc. (GSI) under contract with DEQ (Contract No. 035-07) have prepared this report
presenting results of the field study performed as part of the Organoclay Cap Performance
Evaluation conducted at the McCormick and Baxter Creosoting Company in Portland,
Oregon. This document describes the objectives and scope of work for organoclay (OC)
coring activities and provides a description of the methodology and findings. The OC
field study was conducted between October 2 and October 5, 2006 and was a joint effort
between DEQ, E & E, GSI, and personnel from the University of Texas (UT). Assistance
also was provided by personnel from Portland State University (PSU). A laboratory
study of the OC field samples will be performed by the UT research team and the results
presented in a separate report.
1.1
Objectives
The objectives of the OC cap performance evaluation include:

Evaluate the effectiveness of the granular organoclay cap placed in 2004 to
contain mobile NAPL (i.e., creosote) discharging prior to cap placement from
two seep areas located in Willamette Cove and the Tank Farm Area (TFA);
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
Measure the thickness of the granular organoclay cores to confirm that design
objectives were achieved during construction; and
Evaluate the effectiveness of the organoclay reactive core mats (organoclay mats)
placed in 2005 to contain releases of NAPL sheens coinciding with subaqueous
gas generation (ebullition) from these areas following construction of the
sediment cap in 2004.

It is believed that ebullition induced sheen releases result from disturbance of residual
NAPL rather than a driving head of mobile NAPL as occurred in the NAPL seeps capped
with granular organoclay. A more detailed discussion of NAPL migration mechanisms is
provided in the Conceptual Site Model Report (GSI, February 2007) and a description of
ebullition at the site is provided below.
1.2
Scope of Work
The OC Cap Performance Evaluation will be performed in two phases. The first phase
consists of the field study while the second phase consists of the laboratory study.
The scope of work for the organoclay field study included:






collection of sediment cap cores in areas where granular organoclay was placed,
logging of sediment cores for organoclay thickness and contamination,
abandonment of core holes with granular organoclay and organoclay mats,
restoration of core hole areas with capping material as was present prior to
advancing cores,
removal and replacement of the organoclay test mats, and
placement of additional organoclay mats.
Field activities were conducted between October 2 and October 5, 2006. Clearwater
Environmental, under subcontract to E&E, provided assistance to E & E during collection
of sediment cap cores and operated heavy equipment for the removal of the organoclay
test mat.
The scope of work for the organoclay laboratory study includes:
 Analytical testing of the organoclay within the mat to determine the amount of
creosote sorbed.
 Analytical testing of the granular organoclay from the cores to determine the
amount of creosote sorbed and the additional amount of creosote that the granular
organoclay can sorb.
 Conducting a crush test on the granular organoclay cores to determine whether the
strength of the organoclay has changed since cap emplacement in 2004.
 Analytical testing to determine whether nitrogen is released from organoclay as it
weathers.
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 Measuring the moisture content of the organoclay to verify the field observation
that the granular organoclay in Willamette Cove was only slightly moist while the
organoclay placed in the TFA was wet and determine whether there is a
relationship between moisture content and permeability of the organoclay.
 Measuring the permeability of the organoclay to determine whether groundwater
can pass through the organoclay capped portions of the sediment cap and whether
NAPL can migrate into the organoclay portion of the sediment cap.
The organoclay laboratory study conducted on the cores will build upon the earlier batch
and column studies conducted using organoclay and McCormick& Baxter creosote and
sediment samples (Reible, 2005).
Samples of sediment underlying the granular organoclay, granular organoclay, whole
cores, and porewater samples were also provided to or collected by Kiara Smith and Dr.
Hap Pritchard from PSU for their ongoing research on polycyclic aromatic hydrocarbon
(PAH) biodegradation occurring at within and/or beneath the sediment cap. The PSU
research builds on an earlier study performed by a joint PSU and Oregon State University
(OSU) group of Integrative Graduate Education and Research Traineeship (IGERT)
students (IGERT, 2006). The IGERT study investigated anaerobic degradation of PAHs
occurring under and/or within the sediment cap. Sediment, sub-armoring sediment cap
pore water, sediment pore water and surface water samples were collected from 3 sites
from areas within the cap footprint: Site 1 in TFA, Site 2 in FWDA, and Site 3 in
Willamette Cove. PAHs were only present in the samples from Willamette Cove (Site 3);
however, evidence of anaerobic degradation was observed at 2 of the sites (Willamette
Cove and the FWDA) including negative oxidation-reduction potential, methane and
CO2 production, and anaerobic degradation breakdown products of naphthalene.
Additional research into the potential biodegradation of site contaminants in groundwater
using push-pull technology is being conducted by OSU (OSU, 2006).
2.0 BACKGROUND
The former McCormick and Baxter Creosoting Company is located in Portland, Oregon,
on the Willamette River at approximately River Mile 7. The Site encompasses
approximately 41 acres of land and an additional 23 acres of contaminated river
sediments.
As part of the remedial action at the site, several remedial measures were implemented to
prevent creosote contamination from continuing to discharge to the river. These remedial
measures included installation of an upland barrier wall, sediment cap with organoclay in
creosote seep areas, and upland impermeable / soil cap. In addition, soil hot spots were
removed and creosote oil continues to be recovered from wells. The sediment cap was
installed between June and October 2004 and included the placement of a two foot thick
sand cap overlain by protective armoring (cobble rock, Articulated Concrete Block
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[ACB] or rip rap). In areas of ACB armoring, a 4-inch layer of gravel overlain by a
geotextile fabric was placed beneath the ACB.
During sediment cap construction at the Willamette Cove and Tank Farm Area (TFA)
creosote seep areas, a one foot thick layer of granular organoclay was placed directly over
the contaminated sediments prior to emplacing the sand (1-foot thick) and armoring.
Organoclay is bentonite or hectorite clay that has been modified to be hydrophobic and to
have an affinity for non-soluble organics manufactured by Aqua Technologies Inc.
Because it has an affinity for petroleum products, organoclay was placed as an absorbent
for NAPL primarily comprised of creosote. The granular organoclay was emplaced in 2
areas where known mobile creosote seeps are located. These seeps are thought to
represent creosote migrating through continuous mobile creosote pathways from the
upland portion of the site outside of the barrier wall.
Organoclay mats were placed in late summer of 2005 in areas where ebullition, in
conjunction with tidal pumping, created minute pathways for otherwise non-mobile
(residual) creosote, either as a sheen associated with the gas bubbles or globules of
creosote migrating through the pathway created by the bubbling:



In a 300- by 100-foot area along the shoreline southeast of the granular
organoclay area within the TFA,
In an area 100- by 60-feet beneath the Burlington Northern Railroad bridge, and
As a small test patch (10- by 15-feet) of the mat (“organoclay test mats”)
covering an individual bubble pathway where creosote sheen was observed
downstream of the TFA. The organoclay test mats were secured with a section
of chain link fence and then covered by sand and rock armoring.
The location of organoclay mat areas along with other site features are shown in Figure 1.
Figure 2 shows the conceptual model of the ebullition at the site. Methane and carbon
dioxide are produced through anaerobic degradation of organic matter (naturallyoccurring organic matter, wood debris, or constituents associated with creosote). The gas
accumulates dissolved in pore water and in bubbles. The bubbles consolidate, and upon a
decrease in pressure such as during low River stage of less than 8 feet NAVD88,
ebullition of the gas bubbles occurs. In areas where the gas bubbles pass through residual
creosote, the bubbles become creosote-coated and produce an oil sheen burst at the water
surface. In one circumstance, the bubble pathway produced by the ebullition crossed the
tidal range of the River. Surrounding the bubble pathway, sheen was observed in the
sand above the water table. As the water rose with the tide, a creosote globule was
observed emanating from the bubble pathway along with the rising water. Attachment 2
shows photographs of the ebullition including sheen and creosote globule migration. As
described above, these areas have been capped with organoclay mats.
A detailed discussion of sediment cap construction activities is provided in the documents
titled Remedial Action Construction Summary Report Sediment Cap (June 2004 through
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November 2004) and Remedial Action Construction Summary Report Sediment Cap
Completion (August 2005 through October 2005), both issued by E & E in May 2006.
3.0 SAMPLING ACTIVITIES
Photographs of the coring activities, core hole abandonment, open cores, organoclay mat
removal, ebullition, and granular organoclay emplacement are provided in Attachment 1.
3.1
Sediment Coring
Sediment cap cores were collected from areas capped with granular organoclay in the
Willamette Cove and Tank Farm Area (TFA). A total of 16 cores were collected from 12
locations in Willamette Cove (Figure 2), and 11 cores were collected from 3 locations in
the TFA (Figure 3). Each sampling location was chosen in order to collect cores
containing a representative sample of the underlying sand cap, granular organoclay, and
native sediments. Coring locations were selected based on several criteria including: a
grid system to provide an even distribution of samples across the capped seep areas and to
measure the actual placed thickness of organoclay; targeted locations based on previous
borings known to contain NAPL; and in the TFA, a transect of cores designed to intersect
previously identified seeps.
In Willamette Cove, ACB blocks were removed from predetermined sampling locations
and replaced with marked individual blocks. Prior to coring, the underlying geotextile
was cut open, and approximately 4-inches of gravel and in some cases up to 6 inches of
sand were removed by hand. A total of 16 cores were collected from 12 locations in
Willamette Cove. Willamette Cove coring locations are shown in Figure 3.
In the TFA, rock armoring was removed using an excavator. Because the rock armoring
thickness in the TFA area was greater than 2 feet (up to about 5 feet of rock in some
areas), it was difficult to excavate and created the risk of compromising the sediment cap
if the excavation were to penetrate the organoclay layer. The excavation took place
primarily beneath the water (as shown in the photos in Attachment 1) and thus, it was
difficult to determine the base of the armoring. Therefore, the rock armoring was cleared
from 3 areas within the TFA instead of the 21 locations scoped in the workplan. TFA
coring locations are shown in Figure 4.
Sediment cap cores were collected using 2-inch diameter Polyvinyl Chloride (PVC) pipe,
saw-cut on one end to provide a pointed cutting tip. Each core was driven approximately
4- to 5-feet below the top of the sand cap. In the TFA, cores were driven as deep as 6-feet
below the top of the sand cap.
PVC cores were driven using a metal slide hammer. Once the desired depth was reached,
two measurements were made from the top of the PVC. The first measurement was to
the top of the sand cap, and inside the pipe to the top of the sample material in the core.
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The difference between these two measurements represents the amount of compaction
during coring. The amount of core material could also be calculated to help determine
how much deeper to drive the core. The compaction appeared to be occurring in the soft
sediment beneath the sediment cap material. Next, the void space within the upper
portion of the PVC pipe was filled with water and capped to create suction within the
sampler, so that the sediment core is not lost out the bottom of the sampler during
retrieval.
Cores were retrieved using a lifting strap and a high lift jack, and the bottom end was
either capped or duct taped. Each core location was recorded using a hand held GPS, and
each core was labeled with the boring identification, depth measurements, and top and
bottom. Each core hole was backfilled with granular organoclay and capped with a piece
of organoclay blanket material followed by re-placement of an ACB block. At coring
locations below water in the TFA, granular organoclay was poured into the open core
hole and a section of organoclay blanket was used to cover the location, followed by rock
armoring.
Once a core was retrieved and the bottom end was capped or duct taped, it was
transported to the site shop building to be opened and logged. Each core was opened by
drilling a drain hole in the PVC just above the top of the sediment to remove the water.
Water was contained in a 55-gallon drum for appropriate disposal. The core was then
laid flat and the pipe was cut length wise, removing approximately 1/3 of the pipe using a
hand held circular saw, thereby exposing the entire sample core. Cores were logged for
sediment description including thickness of organoclay, and presence of NAPL. Whole
intact cores and sectioned off-cores from locations SD2304 and B3 in Willamette Cove
and D-3 and G-3 in the TFA were shipped to the UT for further analysis. The following
cores were provided to PSU for PAH biodegradation research: Willamette Cove B-4, D5, and B3 and from the TFA B1a, D3, and G3. Kiara Smith with Portland State
University also collected a gas sample from a TFA bubble path, and pore water samples
co-located with the following cores: Willamette Cove D-5 and TFA B-1, D-3 and G-3.
Core descriptions are discussed in Section 4 below.
3.2 Organoclay Mat Removal and Placement
During the October coring event, the organoclay test mat was removed, visually logged
for evidence of contamination, swaths cut out for samples, and replaced. The organoclay
test mat was installed in August 2005 in the TFA to cap NAPL sheens produced during
ebullition and for follow-up analysis. To aid in retrieval, the organoclay mat was covered
by sand and 3 chain link fence sections for ease in finding. Additional sand and rock
armoring was placed over the fence sections to protect it from wave action.
Using an excavator, overlying rock armoring and sand were removed, and the test mat
was pulled back. Two small sections of each mat, measuring approximately 2 feet and 3
feet in diameter, were cut out of the mat and shipped on ice to the UT for further analysis.
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The organoclay test mats were placed back over the same location with new sections of
organoclay mat placed where sections had been cut for analyses. The mats were reburied
with the sand and rock armoring (the fencing was disposed as solid waste).
Additional organoclay mats (15’ by 15’) were installed just west of the original test mat
location where more recent field observations had identified occasional ebullitioninduced sheens. The locations of these organoclay mats are shown in Figure 3.
4.0
SEDIMENT CAP OBSERVATIONS
The PVC cores, not retained as intact cores for analysis, were cut open as described in
Section 3 for logging and sampling purposes. They were logged primarily for the
following information:




organoclay and sand cap thickness;
field evidence of creosote in organoclay, sand cap or sediment (odor, slight
sheen, moderate sheen, heavy sheen, free oil);
nature of the organoclay (odor, color, density, moisture content, grain size,
swelling, stratification, mottling, structure, consistency);
nature of sediment beneath organoclay - primarily creosote.
The core logs are provided in Attachment 2. Photos of the cores are shown in
Attachment 1. Figures 2 and 3 show the organoclay thickness encountered at each core
location for the Willamette Cove and TFA, respectfully.
Willamette Cove Observations
The sand cap in Willamette Cove was confirmed to be approximately one foot thick.
Typically, a 4-6 inch hole was dug in the sand layer prior to driving the cores, and
therefore, less than a foot of sand was present in most cores. A strong “reducing odor”
was present at the bottom of the sand layer and into the top of the organoclay layer often
with associated holes from which it appears that gas escaped upon opening the cores.
The holes appeared to be discontinuous in nature. The sand and organoclay in this
horizon was discolored to a dark gray, suggestive of chemically reducing conditions.
Cores from the northern edge of the granular organoclay appeared to have sand cap
material beneath the organoclay. This is likely because the sand cap to the north in
Willamette Cove was placed prior to placing the Willamette Cove granular organoclay.
In some locations the sand cap material beneath the organoclay had a creosote odor;
however, there were no locations were the sand overlying the organoclay had a creosote
odor.
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The thickness of organoclay, based on the cores, is shown on Figure 2. In general, within
the central area of the granular organoclay, the organoclay thickness was approximately
12- to 15-inches; within 10 feet from the edge of the design footprint, the organoclay
thickness ranged from 7- to 10.5-inches; and at or just outside the organoclay design
footprint, organoclay thickness ranged from 1.5- to 3.5-inches. These observations
indicate that the organoclay was placed according the design criteria of a 1 foot thickness
in Willamette Cove.
The organoclay in Willamette Cove was typically very hard and only slightly moist (with
the exception of C4.5 which was soft and wet). The PVC coring tubes were difficult to
drive through the organoclay layer. It did not appear that swelling was the cause for the
hardness of the organoclay layer because the organoclay was friable and easily separated
into grains when placed in water. The individual grains were hard but brittle when
pinched. Typically, the contact with the sand cap and sediment were sharp and flat. The
organoclay had a stratified appearance based on both grain-size and color. Color ranged
from light gray to black with some areas of tan, brown and orange grains. Often the
organoclay had a mottled appearance of light and dark gray areas. With the exception of
organoclay from B-3 which had a slight odor of creosote, there was no field evidence of
creosote contamination in the organoclay.
The sediment was typically sand or sand with silt with some woody debris. Cores B-1, B2, and D-3 did not penetrate through the organoclay to the sediment. C5.5 was the only
core with no field evidence of contamination noted in the sediment of the core; however,
when the core was removed from the hole, a slight sheen appeared on the water in the
core hole prior to abandonment. Cores D-4 and SD2404 had creosote odor in the
sediment portion of the cores but no sheen. Sediment from cores B-3, C-4.5 and SD2304
had a strong creosote odor and a moderate sheen. Sediment from core B-4 had odor but
no sheen near the organoclay contact with increasing odor and a heavy sheen at the base
of the core (approximately 2 feet below the organoclay/sediment contact. Black creosote
globules entered the B-4 core hole upon removing the core. The creosote rose to the top
of the water table when exposed to the open hole indicating it is light nonaqueous phase
liquid (LNAPL). However, since the contamination in the core appears to be limited to
the based of the sediment, the creosote oil is likely in a residual state when undisturbed
(i.e. doesn’t appear to be migrating upward through the sediment).
Tank Farm Area Observations
The armoring was removed from 3 areas to collect cores into the sand and organoclay
portions of the sediment cap. Armoring material ranged from 1 foot thick in the G-3
coring location to 5 feet thick in the D-3 coring location. At least a foot of sand was
overlying the armoring in the G-3 location. The sand cap thickness ranged from 12-to 32inches in the TFA. No evidence of contamination was apparent in the sand cap material.
The strong reducing odor present in the sand near the organoclay in Willamette Cove was
not present in the TFA; however, the top few inches of organoclay from G-3 were
discolored to a dark gray.
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The organoclay ranged in thickness from 7- to 12-inches in the central portion of the
organoclay design area and 1.5-inchs in B-1 located at the edge of the design. Coverage
of organoclay seems to be good; however, the thickness is somewhat less than the desired
foot in some locations.
The organoclay in B-1 and D-3 was soft and wet. D-3 had a mottled appearance with
light gray and black areas. The zones with black organoclay did not exhibit sheen or
odor. If these black grains were organoclay with sorbed creosote NAPL, one might
expect an odor and potentially an oily sheen. However, the UT lab study (Reible, 2005)
indicated that organoclay with sorbed creosote did not produce a sheen in water.
The organoclay from Core G-3 was much more stratified than other cores both from the
TFA and Willamette Cove. Grain size ranged from a fine sand size to a pebble size. A
1.5-inch layer of coarse sand to pebble-sized organoclay was present. Grains ranged in
color from orange to light gray to black. It appears to have settled in a few episodes, a
few finer layers at the bottom followed by a fining upward sequence from pebbles to fine
sand sized grains. Potentially, as pre-wetted super sacks of organoclay were placed into
the river, the wetted organoclay settled distally. Then, the organoclay from the super sack
placed in the G-3 area may have been placed on top of existing organoclay that settle
from other super sacks. However the stratification occurred, it does not appear to be a
post-emplacement phenomenon. Photographs of the organoclay placement are provided
in Attachment 1.
No obvious field evidence of contamination was noted in the organoclay from the TFA.
The contact with sand cap material and sediment were sharp. In areas where the
organoclay was discolored to a black or dark gray color, there were no other field signs of
contamination such as odor or sheen. The UT laboratory analyses will determine whether
and to what extent the organoclay has sorbed creosote or creosote constituents dissolved
in water.
Sediment encountered below the organoclay in the TFA was visually contaminated with
creosote. The cores that were logged from G-3 and D-3 showed increasing creosote
contamination with depth in the sediment from the strong odor to a heavy sheen. The
sediment was dark gray sand with silt. Sediment in the base cores D3b and D3e (not
logged) had oily sheen and a strong creosote odor. Core G-3d (also not logged) had free
creosote oil at base of core. These cores were delivered as intact cores to UT or given to
PSU for additional analysis.
After removing organoclay cores in the TFA, sheen appeared on the water in the trenched
areas. Upon core hole abandonment, the sheens dissipated and did not reappear.
Although ebullition developed upon coring, NAPL releases were not observed. It also is
noted that throughout the entire TFA area very active ebullition, primarily associated with
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low tides, occurs on a regular basis but without releases of NAPL Ebullition appears to
be most abundant outside of the organoclay footprint
Organoclay Test Mat Observations
The 10-by 15-foot organoclay mats were removed from the TFA area shown as
“organoclay test mat” on Figure 3. These two organoclay test mats were placed (double
thickness) in August 2005 over a small area of ebullition induced sheen releases. This
was the first usage of organoclay mats at the site. The mats have been in place for
approximately one year. Figure 4 illustrates the mat orientation, discolored areas, and
areas cut out for sampling. The upper mat had rust colored stains on the edge of the mat
towards the shore edge. The lower mat had rust colored stains also towards the shoreline,
although the stained areas did not match up with the lower mat rust colored stains. The
bottom mat had a large oval area in the center which was whiter than the rest of the mat.
This area also had a slight creosote odor. Two sections were cut from the each upper and
lower mat as shown in Figure 5 for University of Texas laboratory analysis of PAHs and
creosote content. No sheen was present in the sand below the mat; however, sand was
collected for analysis of PAHs from beneath the mat in an area where there was a
creosote odor.
Top Mat
Bottom Mat
Rust
Area
Rust
Area
Whiter areas
w/ creosote
smell
Willamette River
Willamette River
*Dashed areas indicate sections removed for analysis
Figure 5: Illustration of Organoclay Test Mats Removed from TFA
The mats were returned to their location over the location of the former ebullition induced
sheen releases. As described in Section 3, additional mats were placed to the southwest
of the test mat (as shown in Figure 4) over an area (formerly identified as “the tomb”)
where ebullition induced sheens were identified in July 2006. It was in this location
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where creosote globules were observed emanating from the bubble pathway during the
rising tide as the water level rose above the sediment surface. Figure 1 shows the
locations of additional organoclay mats that were placed 2005 to cap areas to remedy
ebullition induced sheen releases.
5.0 SUMMARY
Sampling verified that granular organoclay was placed according to specification in
Willamette Cove. Thickness of organoclay in the Tank Farm Area ranged from 7-12
inches within the granular organoclay design area. This is somewhat less than the 12
inches that were specified; however, only 4 cores were logged from the TFA.
In Willamette Cove, although the cores were difficult to advance through the hard
organoclay, removing the articulated concrete blocks and accessing areas to core was
straightforward. In addition, there was less concern in Willamette Cove than in the TFA
regarding compromising the integrity of the sediment cap. However, coring through the
cap in any location could potentially create and undesirable pathway through the sediment
cap. Areas that were cores will need to be observed to ensure that the core hole
abandonment was effective.
In the TFA large amounts of rock armoring covered the sand and organoclay. Even at the
lowest river stages, removal of the rock resulted in working beneath the water level of the
river. Thus, it was difficult to determine the base of the rock and we had to be very
careful not to remove the sand or dig into the organoclay layer. We were concerned over
the possibility of penetrating the organoclay layer and compromising the integrity of the
sediment cap. Therefore, only 3 locations were prepared for coring.
The organoclay in Willamette Cove was generally hard and moist while organoclay from
the TFA area was generally soft and wet. In Willamette Cove there was evidence of
biological or chemical activity at the top of the organoclay/base of the sand cap as
evidenced by a strong “reducing odor”, discoloration to a dark gray, and holes where
gases appeared escaped from upon opening the cores. There was some evidence of this
phenomenon in the TFA based on discoloration of the organoclay and sand to a dark gray
color; however, the strong “reducing odor” was not as apparent. Research that Kiara
Smith and Dr. Hap Pritchard are conducting at Portland State University may help
understand the processes occurring at this horizon in the sediment cap.
There was no clear evidence of creosote migrating into the organoclay; however, there
was a slight creosote odor in the organoclay in a few cores. The laboratory studies being
conducted by Dr. Reible and his graduate student Lisa Morelli will determine whether the
granular organoclay has sorbed creosote oil or dissolved constituents associated with
creosote.
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6.0 REFERENCES
Bice, A. M., 2006, Proposed Field Work Plan: Single Well Push-Pull Tests for
Determining in situ Naphthalene Degradation Rates at McCormick & Baxter Creosoting
Company Superfund Site Portland, Oregon. November 2006.
Ecology and Environment, 2006, Remedial Action Construction Summary Report
Sediment Cap (June 2004 through November 2004), Prepared for Oregon Department of
Environmental Quality. May 2006.
Ecology and Environment, 2006, Remedial Action Construction Summary Report
Sediment Cap Completion (August 2005 through October 2005), Prepared for Oregon
Department of Environmental Quality. May 2006.
OSU/PSU IGERT Team, 2006, Report of Findings. Prepared for the Oregon Department
of Environmental Quality. August 2006.
Reible, D., 2005, Organoclay Laboratory Study- McCormick & Baxter. Prepared for the
Oregon Department of Environmental Quality. Project 005-05. September 2005.
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