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/A newsletter about soil, sediment, and ground-water characterization and remediation technologies
Issue 18
This issue of Technology News and Trends highlights innovative approaches for
addressing issues arising at sites with contaminated sediment. An estimated 12-25%
of all National Priorities List sites contain contaminated sediment due to inadequate
treatment and inappropriate discharge of industrial and municipal wastewaters in the
past. Particular problems are posed by heavy metals and hydrophobic organic
chemicals that have settled in bottom sediment.
May 2005
Changes in River Sediment Conditions Attributed to
Ice Jam-Related Scouring
Alcoa, Inc. began a pilot study in 2001 to
evaluate subaqueous capping as a potential
remedial alternative for addressing
polychlorinated biphenyls (PCBs) in sediment
and biota of the lower seven miles of the
Grasse River near Massena, NY. The pilot
study examined various cap materials and
application techniques in a 7-acre study area.
[For more information, see the September
2002 issue of Technology News and
Trends} Data collected over the following
year demonstrated that the cap had remained
intact and relatively unchanged and was
functioning as designed.
Spring 2003 monitoring results, however,
indicated a loss of cap material and underlying
sediment in the study area. Investigations
found that these changes were caused by a
severe ice jam that formed directly over the
cap. The occurence of ice jams severe
enough to scour sediment was not known
prior to this. As a result, the cap was not
designed to withstand forces associated with
ice jam-related scour.
A review of recent climatic events revealed
that severe winter conditions in 2002-2003
had created a thick ice cover over much of
the river. Warmer temperatures the following
spring created heavy runoff and higher flows
that coupled with a weakening ice cover in
the Upper Grasse River to transport a large
volume of floating ice pieces downstream.
Floating ice encountering the (still intact) ice
cover proximate to the study area caused
accumulation of a thick ice jam extending
approximately four feet above the water
surface and through most of the water
column.
Modeling indicated that scour of the cap
material, underlying sediment, and sediment
outside the study area was caused by the
turbulence and high velocity of water flow
below the ice. The turbulence and high water
velocity resulted from an increase in water
stage upstream of the ice jam, a reduced
cross section below the jam, and the
roughness of the icejam. Sonar imagery and
underwater videography supported the
finding that scour resulted from hydraulic
forces below the toe of the ice jam rather
than physical contact between the ice and
sediment.
The extent and magnitude of sediment
disturbance caused by the ice sour event
was characterized by examining changes in
sediment elevation and type relative to pre-
ice jam conditions (Figure 1). Comparisons
indicated that scour ranged in depth from
0.4 to 5.0 feet and occurred in about 15% of
the river bottom in the uppermost 1.8 miles
of the Lower Grasse River. The greatest
scour depth was observed in "pilot cell #4"
of the study area, which contained a 24-inch
[continued on page 2]
Contents
Changes in River
Sediment Conditions
Attributed to Ice Jam-
Related Scouring page 1
New Tools Improve
Assessment of
Contaminated Ground
Water and Surface
Water Interaction page 3
Capping Techniques
Affect Contaminant
Resuspension page 4
Increased Federal
Funding Expedites
Great Lakes Sediment
Cleanup page 5
SedWeb Resources
The Hazardous Substance
Research Centers/South &
Southwest (HSRC/S&SW)
sponsor SedWebSM (http://
www.sediments.org), an online
forum for exchanging new
information and ideas on
contaminated sediments
management and research.
SedWeb participants are
invited to contribute articles to
an online library, post items on
a bulletin board, subscribe to
monthly news advisories, or
use more than 150 links to
additional online resources.
Recycled/Recyclable
Printed with Soy/Canola Ink on paper that
contains at least 50% recycled fiber
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Figure 1. Analysis of the Grasse River
system following ice jam scour revealed
high correlation between scour depth
and material deposition.
[continued from page 1]
thick sand/topsoil cap covering
approximately 1.2 acres.
The greatest accumulation of material
deposition also occurred in pilot cell #4,
where a 4.6-foot increase in sediment
elevation was noted. Bathymetric
comparisons showed an overall net
increase of sediment deposits (in addition
to sediments scoured from upstream
areas), which indicated that more solids
are entering the river system from
upstream sources and depositing into the
Lower Grasse River than previously
believed.
Redistribution of sediments and PCBs
during the 2003 ice j am and scour did not
significantly affect average PCB
concentrations in sediment, water, and
fish, suggesting that potential PCB
exposure in the river did not change
significantly. Surface sediment PCB
concentrations in the scour area,
however, were higher and more variable
than before capping, averaging 13 ppm
instead of 8 ppm. This increase is
attributed to exposure of deeper
sediments typically containing higher
PCB concentrations. Surface sediment
PCB concentrations decreased in areas
subject to deposition, as evidenced by a
three-fold reduction immediately
downstream of the study area.
Routine monitoring indicated that the
scour event did not have an adverse
131
River Flow Direction
Area of Deposition
Area of Scour
1000
1000 Feet
impact on PCB concentrations in the water
column or on PCB mass flux. Additionally,
system-wide effects from the scour event
were not observed during analysis of native
fish tissue (with the exception of brown
bullhead in one of the monitoring areas).
Expanded testing indicated that PCB
mobilization to the river banks did not
represent an exposure pathway of concern.
A review of historic records and physical
evidence such as tree scarring indicated
that possibly six ice jam events have
occurred in the Lower Grasse River over
the past 40 years. Analysis of high-resolution
and stratigraphic cores suggested that ice
j am-related scouring occurred in the Lower
Grasse River four times over the same
period or about once each decade. Results
of this and other investigative work to date
indicate that ice jams, and resulting scour
associated with severe ice jams, are limited
to the upper 1.8 miles of the Lower Grasse
River.
A follow-on study on the Grasse River
will be conducted in 2005-2006 to
evaluate a range of technical issues,
including options for reducing potential
risks associated with future ice jam-
related scour events. Options include the
installation of an ice control structure to
control formation and breakup of jams,
and the placement of an armored cap
(containing large-grade material) to
protect against erosive forces associated
with severe jams.
Contributed by Larry McShea,
Alcoa, Inc. (724-337-5458 or
larry.mcshea@alcoa.com), Young
Chang, U.S. EPA Region 2
(212-637-4253 or
chang.young@epa.gov), and Jim
Quadrini, Quantitative
Environmental Analysis, LLC
(201-930-9890 or
jquadrini@qeallc. com)
International Networking
The North Atlantic Treaty Organization (NATO) is sponsoring a workshop on sediment assessment and remediation this
month in the Slovak Republic to exchange information between North American and European experts. To view the agenda
now, or presentations with audio clips later this summer, visit the HSRC/S&SW at http://www.hsrc.org.
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New Tools Improve Assessment of Contaminated Ground Water and Surface Water Interaction
The Space and Naval Warfare Systems
Command (SPAWAR) and Naval
Facilities Engineering Service Center
(NFESC) are working with Cornell
University to develop techniques for
assessing contaminated ground-water
discharge into coastal environments. Two
of these tools - the Trident® probe and
the UltraSeep® meter - help to identify
potential areas of ground-water
impingement into surface water and to
quantify flow rates and contaminant levels.
Recent field trials of these tools show they
provide rapid assessment of coastal
contamination migration and can lead to
selection of more effective and less costly
remedial alternatives than those selected
through conventional characterization
techniques.
The Trident probe is a flexible, multi-
sensor sampling device consisting of a
simple direct-push system equipped with
temperature, conductivity, and pore-water
sampling probes (Figure 2). Contrasts in
temperature and conductivity between
surface water and ground water are used
to determine likely areas of ground-water
impingement. The device's water
sampler allows extraction of interstitial
water from sediment at depths reaching
90 centimeters below the sediment/water
interface.
The UltraSeep meter is amodular seepage
meter featuring an ultrasonic flow meter
that provides continuous and direct
measurement of ground water (Figure 3).
The device's water sampler collects up to
10 samples of discharge water, which are
collected in proportion to the measured
discharge rate using a low-flow peristaltic
pump equipped with a sample selector
valve and bag array. Temperature and
conductivity measurements collected by
onboard sensors are stored in an onboard
computer that also controls sampling
events. The flow meter detects a specific
discharge or recharge in the range of
approximately 1-1000 cm/day
The two tools typically are applied as an
integrated system, with Trident sensors used
first to identify potential contaminant
discharge zones. Its water sampler then
operates to determine spatial distribution and
concentrations of contaminants in the
identified discharge zones. Deployment of
UltraSeep follows in key areas to quantify
the discharge rate and concentrations.
One of the first coastal sites where the
integrated system was deployed on a full-
scale basis is Naval Air Station (NAS)
North Island Site 9, CA. Bordering San
Diego Bay, the site was a marshland that
was filled during the 1930s with dredge
material and subsequently served as a
chemical waste disposal site. Shoreline
monitoring wells and ground-water
modeling suggested that a trichloroethene
(TCE) plume was migrating toward but not
discharging into the Bay.
The Trident probe was deployed at 20 stations
located across an approximate 100- by 200-
meter area to a depth of approximately 60
cm, collecting both sensor readings and pore-
water samples at each station. Though
sampling was restricted to 4-hour, low-water
time windows, the survey was completed in
two days. A localized discharge area of
approximately 50 by 100 meters was
identified based on a temperature contrast
of 1-2 °C that corresponded with elevated
concentrations of volatile organic compounds
(VOCs) in pore water. UltraSeep
deployment then provided direct
quantification of the ground-water discharge
rates (up to approximately 30 cm/day) and
the VOC concentrations. These results were
incorporated into arefined conceptual model
and resulting remedial strategy for the site
Figure 2. Its relatively compact size
(24-inch length), stainless steel
construction, and adjustable air
hammer allow the Trident probe to
be used easily in a variety of
sediment scenarios.
that reflects a more isolated zone of
discharge into San Diego Bay.
More recently, a full-scale demonstration
of the integrated system was completed
at NAS Panama City, FL, which lies on
St. Andrew Bay along the Florida
panhandle. From the mid 1950s to the late
1970s, an area now designated "Area of
Concern 1" (AOC 1) was used for
firefighter training that generated waste
oils, fuels, paint/thinners, and bilge water.
The source area was remediated but
concern remained for surface water
discharge of a residual dichloroethene
(DCE) plume that extended to the bay
shore.
Use of Trident and UltraSeep technologies
demonstrated that DCE concentrations
in the discharge zones offshore from
AOC 1 were below detection. This
finding facilitated a determination that
monitored natural attenuation is afeasible
remedy for AOC 1, thereby providing a
potential cost savings of $1,250,000.
Full-scale deployment of these integrated
tools was conducted at several other
contaminated sediment sites including the
Anacostia River in Washington, DC, and
the Naval Construction Battalion Center
Davisville Site 7, in Rhode Island.
[continued on page 4]
Sample
Line to -
Surface
Reference
Temperature &
Conductivity
Adjustabi
Stop Plate
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[continued from page 3]
SPAWAR and the NFESC anticipate
additional deployments in Naval Station
San Diego andNAS Orlando this summer.
Contributed by D. Bart Chadwick,
Ph.D., andStacey Curtis, SPAWAR
Systems Center San Diego (619-553-
5333 or bart.chadwick@navy.mil
and 619-553-5255 or
stacey.curtis@navy.mil) and Amy
Hawkins, NFESC (805-982-4890 or
amy. hawkins@navy.mil)
Capping Techniques Affect Contaminant Resuspension
Recognizing that little information has
existed on the potential release of in-situ
contaminated sediments during and after
capping operations, the U.S. EPA's
National Risk Management Research
Laboratory (NRMRL) led an interagency
investigation of the issue at two
contaminated sediment sites over the past
two years. Contaminant releases were
measured during cap placement at two
confined aquatic disposal (CAD) cells in
Boston Harbor, MA, and on creosote-
contaminated sediments resulting from
past wood-treating opperations at the
Wyckoff/Eagle Harbor Superfund site on
Bainbridge Island, WA. The study found
consistent evidence of contaminant
resuspension during capping and identified
potential field methods for minimizing
resuspension.
The Boston Harbor investigations focused
on CAD cells containing 118,500 m3 and
136,850 m3 of dredge material placed in
the Mystic River during late 1999. The
material is characterized as silty, fine-
grained sediment containing total
petroleum hydrocarbons (TPH), PCBs,
and polycyclic aromatic hydrocarbons
(PAHs) averaging 1,520 mg/kg, 220
|0g/kg, and 64,500 |Jg/kg, respectively, in
concentration.
Nine months after filling the cells, at which
point consolidation was considered
complete, sand dredged from Cape Cod
Canal was placed over the cells to form
caps. A tugboat was used to maneuver a
partially opened hopper dredge that
distributed sand over each cell to achieve a
cap thickness of 0.67-1.22 meters. This
capping method was expected to minimize
disturbance of silt material within the cells.
During cap installation, an aqueous
monitoring tool (AMT) was towed behind
a boat to collect and integrate in-situ
measurements with continuous water
collection at the rate of 12 L/min. The AMT
sensor package included components for
measuring conductivity, temperature and
depth; two turbidity sensors; and a Teflon™/
titanium pumping system for water sample
collection. The AMT was suspended 1-2
meters above the sediment surface while
the research boat maneuvered around the
capping vessel. Ten separate sampling
events were conducted over a 22-day
period. All water samples were analyzed
for PCBs, PAHs, TPH, total suspended
solids (TSS), and eight RCRA-regulated
metals.
Turbidity mapping of the water column
revealed that the highest turbidity and TSS
concentrations occurred during the first
capping run, followed by progressively
decreasing turbidity and TSS as capping
continued. This suggested that a substantial
portion of the sediment suspension
measured during the initial runs was due
to bed sediment resuspension, and that
the amount of bed sediment resuspension
decreased with each run.
A similar trend was noted in contaminant
concentrations, whereby concentrations
of contaminants of concern increased
significantly during the first capping run
but generally decreased throughout the
remainder of capping activities. For
example, analytical results indicated that
concentrations of total PAHs reached a
maximum average of 1,370 ng/L during
the first capping run but approached pre-
capping concentrations and averaged 55
ng/L after cap installation. Similarly, PCB
concentrations were below detection
prior to capping but reached 84 ng/L during
the initial run. By the end of the monitoring
study, PCB concentrations returned to a
non-detectable level.
Similar results were obtained in Eagle
Harbor, which is a shallow marine
embayment west of Seattle, WA,
containing sediment with TPH and PAH
concentrations reaching 3,060 mg/kg and
2,120 mg/kg, respectively. The U.S.
Army Corps of Engineers (ACE) initiated
partial capping in 1993 to begin controlling
migration of contaminants from the
sediment into the water column and
surrounding sediment. The final phase
[continued on page 5]
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[continued from page 4]
began in 2001, when the ACE capped the
area containing the highest contaminant
concentrations as part of an enhanced
source control effort. Capping was
performed by transporting sand to the site
in aflat-top barge maneuvered by atugboat
and washing sand overboard with a high-
pressure hose. Approximately 91,700 m3 of
clean sand was distributed to form a cap
covering 5.27 hectares.
Contaminant resuspension was studied in
a 150- by 275-meter portion of the cap
located 76-381 meters from the primary
contaminant source. During capping, the
AMT was pulled at a depth of one meter
above the sediment and immediately
behind abarge depositing the cap material
on the sediment surface. Three monitoring
runs were conducted over three
consecutive days of cap installation to
obtain a total of 90 water samples.
Elevated turbidity levels were observed at
varying distances and directions from the
capping barge, and TSS levels were
observed 200 meters from the capping area
within three hours of capping
commencement. Unlike the results at
Boston Harbor, turbidity and TSS levels
remained high during the following three
capping runs, likely due to higher rates of
TSS from the cap material itself rather than
bed sediment. Turbidity levels were found
to decrease to pre-run capping, however,
within 1-2 hours.
Consistent with the Boston Harbor results,
total PAH concentrations in water were
elevated during initial capping operations
but progressively decreased and dissipated
after capping was complete (Figure 4).
Rapid dissipation of contaminant plumes
likely resulted from the combined effects
of sedimentation and off-site plume
migration.
These results suggest that alternative
techniques for cap installation may
considerably reduce negative impacts on
water quality. Resuspension may be
30(H
250-
200-
150-
100-
Baseline
Day 1
Day 2
Day 3
Post Survey
minimized by placing cap material in
several lifts, whereby the first lift uses
minimal disturbance techniques to provide
a uniform layer of clean material and
subsequent lifts are placed more
aggressively. While some low-energy
techniques may reduce the degree to
which native sediments are disturbed,
they may slow the cap placement process
and prolong the duration of exposures due
to resuspension.
This study was conducted in cooperation
with the U.S. Army Engineer Research
and Development Center, ACE, Batelle
Memorial Institute, and EPA Regions 1
and 10. Copies of the complete report will
be available from NRMRL later this year
at http://www.epa.gov/ORD/NRMRL.
Contributed by Terry Lyons, EPA
Office of Research and
Development/NRMRL (513-569-
7589 or lyons.terry@epa.gov)
Increased Federal Funding Expedites Great Lakes Sediment Cleanup
EPA's Great Lakes National Program
Office (GLNPO) reports that
contaminated sediment is the largest major
source of contaminants in Great Lakes
rivers and harbors entering the food
chain. Although the discharge of toxic and
persistent chemicals to the Great Lakes
has decreased significantly over the past
20 years, continued high concentrations of
contaminants in bottom sediment raises
concern about potential risks to aquatic
organisms, wildlife, and humans.
To address the problem, the Great Lakes
Legacy Act of 2002 (GLLA) authorizes
[continued on page 5]
Contact Us
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Office of Superfund Remediation and
Technology Innovation
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U.S. Environmental Protection Agency
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1200PennsylvaniaAve,NW
Washington, DC 20460
Phone:703-603-7199
Fax:703-603-9135
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Solid Waste and
Emergency Response
(5102G)
EPA 542-N-05-003
May 2005
Issue No. 18
United States
Environmental Protection Agency
National Service Center for Environmental Publications
P.O. Box 42419
Cincinnati, OH 45242
Presorted Standard
Postage and Fees Paid
EPA "
Permit No. G-35
Official Business
Penalty for Private Use $300
[continued from page 4]
$270 million during fiscalyears 2004-2008
for remediation of contaminated sediment
in 31 areas of concern (AOCs) of the
Great Lakes region. Each year, $50million
is targeted for projects that monitor or
evaluate contaminated sediment,
implement a plan to remediate
contaminated sediment, orpreventfurther
or renewed sediment contamination at the
AOCs. Priority also is given to projects
employing an innovative approach that
provides greater environmental benefits
than conventional methods or equivalent
environmental benefits at a reduced cost.
The Black Lagoon on the Detroit River
in Trenton, MI, will be the first
contaminated sediment site to be cleaned
up under the GLLA. Environmental
dredging, which began in October 2004,
is in use to remove approximately 90,000
yd3 of sediment contaminated with PCBs,
oil and grease, mercury, and other heavy
metals from the bottom of the lagoon.
Over 3.3 million yd3 of contaminated
sediments were remediated in the U.S.
Great Lakes basin between 1997 and 2003
(Figure 5). The GLNPO anticipates that the
rate of sediment remediation activities will
continue to accelerate with the availability
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1997 1998 1999 2000 2001 2002 2003
Year
of GLLA funding opportunities. More
information on GLNPO's Contaminated
Sediments Program, current projects, and
links to related resources is available at
http ://www.epa.gov/glla.
Contributed by Marc Tuchman,
GLNPO (312-353-1369 or
tuchman.marc@epa.gov)
Figure 5.
Although
significant
progress is
being made in
sediment
remediation in
the Great Lakes,
millions of cubic
yards of
contaminated
sediment remain.
EPA is publishing this newsletter as a means of disseminating useful information regarding innovative and alternative treatment techniques and
technologies. The Agency does not endorse specific technology vendors.
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