vvEPA
United States
Environmental Protection
Agency
Office of Research and
Development
Washington, DC 2046O
EPA/625/R-98/001
August 1998
National Conference on
Management and Treatment of
Contaminated Sediments
Proceedings
Cincinnati, OH
May 13-14, 1997
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EPA/625/R-98/001
August"! 998
National Conference on Management and
Treatment of Contaminated Sediments
Proceedings
Cincinnati, OH
May 13-14, 1997
Technology Transfer and Support Division
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH
Printed on Recycled Paper
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Notice
Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
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Foreword
The U.S. Environmental Protection Agency is charged by Congress with protecting the
nation's land, air, and water resources. Under a mandate of national environmental laws, the
Agency strives to formulate and implement actions leading to a compatible balance between
human activities and the ability of natural systems to support and nurture life. To meet this
mandate, EPA's research program is providing data and technical support for solving environmen-
tal problems today and building a science knowledge base necessary to manage our ecological
resources wisely, understand how pollutants affect our health, and prevent or reduce environmen-
tal risks in the future.
The National Risk Management Research Laboratory is the Agency's center for investiga-
tion of technological and management approaches for reducing risks from threats to human health
and the environment. The focus of the laboratory's research program is on methods for the
prevention and control of pollution to air, land, water and subsurface resources; protection of water
quality in public water systems; remediation of contaminated sites and ground water; and
prevention and control of indoor air pollution. The goal of this research effort is to catalyze
development and implementation of innovative, cost-effective environmental technologies; develop
scientific and engineering information needed by EPA to support regulatory and policy decisions;
and provide technical support and information transfer to ensure effective implementation of
environmental regulations and strategies.
This publication has been produced as part of the laboratory's strategic long-term research
plan. It is published and made available by EPA's Office of Research and Development to assist
the user community and to link researchers with their clients.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
in
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Contents
EPA's National Sediment Quality Survey: A Report to Congress on the
Incidence and Severity of Sediment Contamination in Surface Waters of the U.S.
Thomas M. Armitage and F. James Keating
Office of Science and Technology
U.S. Environmental Protection Agency
Washington, D.C.
2.
3.
EPA Role in Managing Contaminated Sediment
Thomas M. Armitage and Jane Marshall Farris
Office of Science and Technology
U.S. Environmental Protection Agency
Washington, D.C.
Strategies and Technologies For Cleaning Up Contaminated Sediments
in the Nation's Waterways: A Study by the National Research Council
Spyros P. Pavlou
Member, NRG Marine Board Committee on Contaminated Marine Sediments,
1993-1996
Technical Director of Environmental Risk Economics, URS Greiner Inc.,
Seattle, WA
Louis J. Thibodeaux
Member, NRC Marine Board Committee on Contaminated Marine Sediments,
1993-1996
Emeritus Director, Hazardous Substance Research Center (South/Southeast),
USEPA and Jesse Cpates Professor of Chemical Engineering,
Louisiana State University, Baton Rouge, LA
12
4.
5.
6.
Solving Great Lakes Contaminated Sediment Problems
Marc Tuchman and Callie Bolattino
U.S. Environmental Protection Agency
Great Lakes National Program Office
Chicago, IL
Jan Miller
U.S. Army Corps of Engineers
North Central Division
Chicago, IL
Perspective on Remediation and Natural Recovery of Contaminated Sediments.
Dolloff F. Bishop
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH
Natural Recovery of Contaminated Sediments—Examples from Puget Sound ....
Todd M. Thornburg and Steve Garbaciak
Hart Crowser, Inc.
18
27
37
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Contents (continued)
7. In-Situ Capping of Contaminated Sediment: Overview and Case Studies 44
Michael R. Palermo
Research Civil Engineer, U.S. Army Engineer Waterways Experiment Station,
Vicksburg, MS
8. Observations Regarding Brownfields and Sediment Disposal at Indiana Harbor 52
David M. Petrovski, Environmental Scientist
U.S. Environmental Protection Agency
Region 5, Chicago, IL
Richard L. Nagle, Attorney
U.S. Environmental Protection Agency
Region 5, Chicago, IL
Jan Miller, Environmental Engineer
USAGE, Great Lakes and Ohio River Division
Chicago, IL
Gregory N. Richardson, Principal
G.N. Richardson & Associates
Raleigh, NC
9. Environmental Dredging and Disposal: Overview and Case Studies 65
Michael R. Palermo, Research Civil Engineer
U.S. Army Engineer Waterways Experiment Station (WES)
Vicksburg, MS
Norman R. Francingues, Chief,
Environmental Engineering Division, WES
Danny E. Averett, Chief,
Environmental Restoration Branch, WES
10. Integrated Sediment Decontamination for the New York/New Jersey Harbor
E. A. Stern
U.S. Environmental Protection Agency, Region 2, New York, NY
K. R. Donato
U.S. Army Corps of Engineers, New York District, New York, NY
N. L. Clesceri
Rensselaer Polytechnic Institute, Troy, NY
K. W. Jones
U.S. Department of Energy, Brookhaven National Laboratory, Upton, NY
11. The Fully Integrated Environmental Location Decision Support (FIELDS) System:
An Approach to Identify, Assess and Remediate Contaminated Sediment
Matthew H. Williams, George D. Graettinger, Howard Zar,
Dr. Yichun Xie and Brian S. Cooper
12. Remediation Strategies and Options for Contaminated Sediment
Carol Ancheta
Scientific Project Officer
Environment Canada
Remediation Technologies Program
Downsview, Ontario, Canada
13. The Automated Dredging and Disposal Alternatives Modeling System (ADDAMS):
Summary and Availability
Paul R. Schroeder
Research Civil Engineer
U.S. Army Engineer Waterways Experiment Station (WES)
Vicksburg, MS
Michael R. Palermo
Research Civil Engineer WES
71
82
85
,90
VI
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Contents (continued)
14. Overview of Ongoing Research and Development
Dennis L. Timberlake
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
Cincinnati, OH
15. Corps of Engineers Research Programs on Contaminated Sediments.
Norman R. Francingues
Chief, Environmental Engineering Division (EED)
U.S. Army Engineer Waterways Experiment Station (WES)
Vicksburg, Mississippi
Michael R. Palermo
Research Civil Engineer, EED, WES
Daniel E. Averett
Chief, Environmental Restoration Branch WES.
Robert M. Engler
Senior Research Scientist WES
16. Potential for Phytoremediation of Contaminated Sediments.
Steven A. Rock
Environmental Engineer
Land Remediation and Pollution ControlDivision
National Risk Management Research Laboratory
United States Environmental Protection Agency
Cincinnati, OH
,94
97
101
17. Treatment of Metal-Bearing Solids: Using a Buffered Phosphate Stabilization System... 106
Thomas Stolzenburg, Senior Applied Chemist
RMT, Incorporated
Madison, Wl ,
18. Treatment of Dredged Harbor Sediments by Thermal Desorption'
Mary Hall, Ed Alperin and Stuart Shealy, IT Corporation
Keith Jones, Brookhaven National Laboratory
19. Solvent Extraction Process Development to Decontaminate Sediments.
Philip DiGasbarro
Metcalf & Eddy, Inc., Branchburg, NJ
John Henningson, P.E.
Formerly of Metcalf & Eddy, Inc.
Georges Pottecher
Anjou Recherche/GRS, Paris, France
John J. Cardoni, P.E.
Metcalf & Eddy, Inc., Branchburg, NJ
20. Containment Research for Contaminated Sediment and Contaminated
Dredged Material Management—A Review
Louis J. Thibodeaux, Danny D. Reible, and Killait T. Valsaraj
Hazardous Substance Research Center/S & SW
College of Engineering, Louisiana State University
Baton Rouge, LA
112
119
131
VII
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Contents (continued)
21. Summary of Conference on Management and Treatment of Contaminated Sediments.. 138
Panel Participants:
Norman Francingues
U.S. Army Corps of Engineers (U.S. COE)
Vicksburg, MS
Emily Green
Sierra Club
Madison, Wl
Michael Palermo
U.S. COE
Vicksburg, MS
Louis Thibodeaux
Louisiana State University
Baton Rouge, LA
Dennis Timberlake
National Risk Management Research Laboratory (NRMRL)
U.S. EPA
Cincinnati, OH
22. Exhibitor List 143
viii
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Acknowledgments
The success of the conference and this document is due largely to the efforts of, many individuals.
Gratitude goes to each person who was involved.
Presenters and Exhibitors
A special thanks goes to the authors of the papers and demonstrations that were presented at the
conference. Their efforts in preparing papers made this document possible and led to the overall
success of the conference. The participation of the exhibitors whose displays added to the
conference is also appreciated.
Special Thanks
The contributions of the following individuals in the development of the conference are especially
appreciated.
Thomas Armitage, Ph.D., EPA, Office of Water, Washington, D.C.
Edwin Earth, Jr., EPA, Office of Research and Development, Cincinnati. OH
Bonnie Eleder, EPA, Region 5, Chicago, IL
Norman Francinques, USACOE, Waterways Experiment Station, Vicksburg, MS
Dennis Timberlake, EPA, Office of Research and Development, Cincinnati, OH
/
Marc Tuchman, Ph.D., Great Lakes National Program Office, EPA, Chicago, IL
Joseph Zelibor, Ph.D., National Research Council, Washington, D.C.
Technical Direction and Coordination
Joan Colson, EPA, ORD, NRMRL, Cincinnati, OH, provided technical direction throughout the
development of the conference and the preparation of the conference proceedings. Eastern
Research Group, Inc. of Lexington, MA, handled conference logistics and provided support for
many aspects of the conference.
Editorial Review and Document Production
Jean Dye and Carol Legg of EPA's Office of Research and Development, Cincinnati* OH, guided
the compilation and editing of this publication. John McCready provided graphics support.
IX
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Introduction
The National Conference on Management and Treatment of Contaminated Sediment was held in
Cincinnati, OH, May 13 to 14, '1997. This technology transfer meeting was held for 213 profession-
als from various EPA divisions and other organizations, including Environment Canada, the U.S.
Army Corps of Engineers, the National Research Council, academia, and the private sector, to
disseminate information on how to manage and treat contaminated sediments. During the
conference, 24 speakers presented various treatment options available for high- and low-end
contaminated sites; future research needs, questions, and comments were addressed during an
interactive panel discussion; and private vendors who have experience in the treatment of
contaminated sediments were available for information at 23 vendor booths.'
Contaminated sediments is growing as an area of environmental concern, particularly when
assessing ecological and public health risks. Costs for treatment and removal of typically high-
volume, low-contaminant concentrations; inadequate measuring techniques for predicting the
effectiveness of cleanup strategies; and lack of comprehensive performance data for various
emerging technologies pose technological challenges for controlling and remediating sediment
contamination. While investigations have been conducted to assess the ecological effects of
contaminated sediments, and to establish general sediment quality criteria used for the basis of
some policy decisions, research is ongoing. This conference provided information on the status of
treatment technologies and the results from various research programs in the following areas:
Nature and extent of contaminated sediments
• Sigaificance of biological and chemical effects of the sediment contamination problem
Sediment quality criteria
Management of sediments, including dredging and containment
• Various In situ and ex situ sediment contamination treatment options
Current research case studies conducted by public, academic and private sectors
Panel discussion to identify future research needs
The purpose of this proceedings document is to present papers from the conference and provide
information to interested individuals unable to attend. This document will be useful to individuals
who are currently looking for information and techniques to treat contaminated sediments in rivers,
harbors, lakes, and/or Superfund sites because of the associated ecological and/or public health
risks or for navigational purposes. These individuals include environmental regulatory personnel at
the federal, state, and local level; university professors, researchers, and students; and private
sector personnel, including industry representatives and environmental consultants. The goal of
sharing this information with a broader audience is to help educate others about the various
technological advances that have been made in sediment contamination research; to present an
overview of the control and treatment options available; and to highlight the future research needs
for treating and managing contaminated sediments.
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EPA's National Sediment Quality Survey: A Report to Congress on the
Incidence and Severity of Sediment Contamination in Surface Waters of
the U.S.
Thomas M. Armitage and F. James Keating
Office of Science and Technology
U.S. Environmental Protection Agency
Washington, D.C.
The U.S. Environmental Protection Agency (EPA) has
completed work on a Report to Congress entitled, 'The
Incidence and Severity of Sediment Contamination in
Surface Waters of the United States." (U.S. EPA, 1997[a],
1997[b], 1997[c])The report describes the accumulation
of chemical contaminants in river, lake, ocean, and
estuary bottoms, and the probability of associated ad-
verse effects on human and environmental health. The
EPA has prepared this report in response to require-
ments set forth in the Water Resources Development
Act (WRDA) of 1992, which directed EPA, in consulta-
tion with the National Oceanic and Atmospheric Admin-
istration (NOAA) and the U.S. Army Corps of Engineers
(USAGE), to conduct a comprehensive national survey
of data regarding the quality of aquatic sediments in the
U.S. The Act required EPA to compile all existing infor-
mation on the quantity, chemical and physical composi-
tion, and geographic location of pollutants in aquatic
sediment, including the probable source of such pollut-
ants and identification of those sediments which are
contaminated. The Act further required EPA to report to
the Congress the findings, conclusions, and recommen-
dations of such survey, including recommendations for
actions necessary to prevent contamination of aquatic
sediments and to control sources of contamination. In
addition, the Act required EPA to establish a compre-
hensive and continuing program to assess aquatic sedi-
ment quality. As part of this continuing program, EPA
must submit a national sediment quality report to Con-
gress every two years.
Role of Sediments in Watershed Health
Sediment provides habitat for many aquatic organisms
and functions as an important component of aquatic
ecosystems. Sediment also serves as a major reposi-
tory for persistent and toxic chemical pollutants released
into the environment. In the aquatic environment, chemi-
cal waste products of anthropogenic origin that do not
easily degrade can eventually accumulate in sediment.
Sediment has been described as the ultimate sink for
pollutants (Salomons et al., 1987).
Contaminated sediments can affect aquatic organisms
in a number of ways. Areas with high sediment contami-
nant levels can be devoid of sensitive species and, in
some cases, all species. For example, benthic amphi-
pods were absent from contaminated waterways in Com-
mencement Bay, WA (Swartz et al, 1982). In Rhode
Island, the number of species of benthic molluscs was
reduced near an outfall where raw electroplating wastes
and other wastes containing high levels of toxic metals
were discharged into Narragansett Bay (Eisler, 1995). In
California, pollution-tolerant oligochaete worms domi-
nate the sediment in the lower portion of Coyote Creek,
which receives urban runoff from San Jose (Pitt, 1995).
Sediment contamination can also adversely affect the
health of organisms and provide a source of contami-
nants to the aquatic food chain (Lyman et al., 1987). Fin
rot and a variety of tumors have been found in fish living
near sediments contaminated by polycyclic aromatic
hydrocarbons (PAHs) (Van Veld et al., 1990). Liver
tumors and skin lesions have occurred in brown bull-
heads in an area of the Black River in Ohio contami-
nated by PAHs from a coke plant (Baumann et al.,
1987). Examples of risks to fish-eating birds and mam-
mals posed by sediment contaminants include repro-
ductive problems in Forster's terns on Lake Michigan
(Kubiak et al., 1989) and in mink which were fed Great
Lakes fish (Auerlich et al., 1973). Bioaccumulative toxic
contaminants in sediment have also been linked to
human health problems such as birth defects, cancer,
neurological disorders, reduced IQ, heart disease, and
kidney ailments. Most sediment-related human expo-
sure to contaminants is through indirect routes that
involve the transfer of pollutants up the food chain.
Consumption of contaminated fish is a major human
exposure pathway for sediment contaminants. Many
surface waters in the U.S. have fish consumption advi-
sories or fishing bans in place because of the high
concentrations of PCBs, mercury, dioxin, kepone, and
other contaminants found in sediment. In 1996, over
2,000 water bodies in the U.S. had fish consumption
advisories in place. The observed effects of sediment
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contaminants upon human health and the environment
demonstrate that sediment cleanup is central to effec-
tive ecosystem management, and that impaired aquatic
ecosystems cannot be restored without cleaning up
toxic sediment.
Sources of Sediment Contamination
Sediment contaminants enter aquatic ecosystems from
many different sources. Municipal and industrial point
source discharges are potential sources of sediment
contaminants. Municipal point sources of sediment con-
taminants include sewage treatment plants and over-
flows from combined sewers. Industrial point sources
include manufacturing plants and power-generating op-
erations. Atmospheric deposition of contaminants such
as mercury, polychlorinated biphenyls (PCBs) and pesti-
cides can also contribute to sediment contamination.
EPA estimates that 76 to 89% of PCB loadings to Lake
Superior have come from air pollution (EPA, 1994).
Urban stormwater and nonpoint source runoff from agri-
cultural fields, landfills, toxic waste disposal sites, and
Inactive and abandoned mining sites can also contribute
to sediment contamination.
EPA's Report to Congress
Recognizing that sediment contamination poses signifi-
cant human health and ecological risks, Congress di-
rected EPA to develop a national inventory of
contaminated sediment sites (WRDA, 1992). In response
to the WRDA mandate, EPA developed the National
Sediment Inventory (NSI), and conducted a screening
level assessment identifying the most severely contami-
nated sites for additional study, source control and
remediation. WRDA, 1992 defined contaminated sedi-
ment as, "sediment containing chemical substances in
excess of appropriate geochemicai, toxicological, or sedi-
ment quality criteria or measures; or otherwise consid-
ered to pose a threat to human health or the environment."
The NSI is a compilation of existing sediment quality
data; protocols used to evaluate the data; and various
reports and analyses presenting the findings, conclu-
sions, and recommendations for action. EPA has pro-
duced the first report to Congress in four volumes:
Volume 1: National Sediment Quality Survey—screen-
ing analysis to estimate the probability of adverse hu-
man or ecological effects based on a weight of evidence
evaluation; Volume 2: Data Summary for Areas of Prob-
able Concern—sampling station location maps and
chemical and biological summary data for watersheds
where sediment contamination may be associated with
adverse effects on human health or the environment;
Volume 3: Sediment Contaminant Point Source Inven-
tory—screening analysis to identify probable point source
contributors of sediment pollutants; and Volume 4: Sedi-
ment Contaminant Nonpoint Source Inventory—screen-
ing analysis to identify probable nonpoint source
contributors of sediment pollutants. (This volume is in
preparation for subsequent biennial reports.)
Description of the NSI Database
The NSI is the largest set of sediment chemistry and
related biological data ever compiled by EPA. It includes
approximately two million records for more than 21,000
monitoring stations across the U.S. To efficiently collect
usable information for inclusion in the NSI, EPA sought
data that were available in electronic format, repre-
sented broad geographic coverage, and represented
specific sampling locations identified by latitude and
longitude coordinates. The minimum requirements for
inclusion of data sets in the NSI were locational informa-
tion, sampling date, latitude and longitude coordinates,
and measured units. The NSI includes data from the
following storage systems and monitoring programs:
Selected data from the EPA Storage and Retrieval
System (STORET), the National Oceanic and Atmo-
spheric Administration Coastal Sediment Inventory
(COSED), EPA Ocean Data Evaluation System (ODES),
EPA Region 4 Sediment Quality Inventory, the Gulf of
Mexico Program Contaminated Sediment Inventory, EPA
Region 10/U.S. Army Corps of Engineers Seattle District
Sediment Inventory, EPA Region 9 Dredged Material
Tracking System (DMATS), EPA Great Lakes Sediment
Inventory, EPA's Environmental Monitoring and Assess-
ment Program (EMAP), and the U.S. Geological Survey
(Massachusetts Bay) Data. In addition to sediment chem-
istry data, the NSI includes fish tissue residue data,
sediment toxicity bioassay data, benthic abundance data,
histopathology data, and fish abundance data. The sedi-
ment chemistry, fish tissue residue, and toxicity data
were evaluated to develop the NSI report to Congress.
Data collected during the period from 1980 though 1993
were used in the NSI evaluation, but older data are also
maintained in the database. Figure 1 illustrates the kinds
of data evaluated to develop a screening level assess-
ment of NSI sampling stations.
Data Evaluation Approach
The approach used to evaluate the NSI data focuses on
risks to benthic organisms exposed directly to contami-
nated sediments, and risks to human consumers of
organisms exposed to sediment contaminants. EPA
evaluated sediment chemistry data, chemical residue
levels in edible tissue of aquatic organisms, and sedi-
ment toxicity data taken at the same sampling stations.
The following measurement parameters and techniques
were used to evaluate the probability of adverse effects.
To evaluate potential impacts of sediment contaminants
on aquatic organisms, three assessments were con-
ducted. 1) Sediment chemistry measurements were com-
pared to sediment chemistry screening values. These
values included EPA proposed sediment quality criteria
(SQCs) (USEPA, 1992, 1993), EPA sediment quality
advisory levels (SQALs) (EPA, 1992, 1993), sediment
effects range-median (ERM) and effects range-low (ERL)
values (Long et al., 1995), probable effects levels (PELs)
and threshold effects levels (TELs) (Florida Department
of Environmental Protection (FDEP, 1994), and appar-
ent effects thresholds for selected organics and metals
(Barrick et al., 1988). 2) The molar concentration of acid
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National Monitoring Data 198B-1993
Sediment Chemistry
Measures
Fish Tisue
Residue
Leuels
Hcute
ToHicity Tests
Peer Reuieujed Screening Leuel flssessment of
Potential Threat to Human Health or the Enuironment
Classification of Sampling Stations
Classification of Watersheds
Figure 1. National sediment inventory data.
volatile sulfides ([AVS]) in sediment was compared to
the molar concentration of simultaneously extracted
metals ([SEM]) in sediment. 3) Available sediment toxic-
ity test data were used to evaluate potential effects to
aquatic life. To evaluate the potential effects of sediment
contaminants on human health, two assessments were
conducted. 1) The theoretical bioaccumulation potential
(EPA, and U.S. Army Corps of Engineers, 1998) of
measured sediment contaminants was compared to EPA
cancer and noncancer risk levels (EPA, 1989,1994) and
Food and Drug Administration tolerance, action, or guid-
ance values (Department of Health and Human Ser-
vices, 1994; 40CFR 180.213a and 180.142). 2) Fish
tissue contaminant levels were compared to EPA can-
cer and noncancer risk levels and FDA tolerance, ac-
tion, or guidance values.
The sediment chemistry screening values used in this
analysis were contaminant concentration reference val-
ues above which potential threats to aquatic life may
occur. Independent analyses of matching chemistry and
bioassay data reveal that sediments are frequently non-
toxic when chemical concentrations are lower than ERL7
ERMs and TEL/PELs. Sediments are frequently toxic
when chemical concentrations exceed these values (Fig-
ure 2). The sediment chemistry screening values used
in the NSI analysis include both theoretically and empiri-
cally derived values. The theoretically derived screening
values (e.g., SQC, SQAL, [SEM]-[AVS]) rely on the
physical/chemical properties of sediment and chemicals
to predict the level of contamination that would not
cause an adverse effect on aquatic life under equilibrium
conditions. The empirically derived, or correlative screen-
ing values (e.g., ERM/ERL, PEL/TEL, AET) rely on
paired field and laboratory data to relate incidence of
observed biological effects to the dry-weight sediment
concentration of a.specific chemical. Correlative screen-
ing values can relate measured concentrations of con-
taminants to a probability of association with adverse
effects, but do not establish a cause and effect for a
specific chemical. Sediment toxicity bioassays were also
used in the NSI analysis to evaluate sediment sampling
stations.
Theoretical bioaccumulation potential (TBP) and tissue
residue data may be indicative of exposure to contami-
nated sediments, and were used in the NSI analysis to
evaluate the potential human health effects of sediment
contaminants. TBP is an estimate of contaminant con-
centration at equilibrium in tissue derived from the sedi-
ment concentration of that contaminant. This calculation
is based on median biota sediment accumulation factors
(BSAFs) for various classes of chemicals. EPA fish
tissue risk levels to which TBP and fish tissue residue
measurements were compared represent tissue con-
centrations of contaminants that should protect consum-
ers from adverse health effects over a lifetime of
exposure.
Incidence of Sediment Contamination
Sediment sampling stations in the NSI were classified
according to probability of adverse effects. Tier 1 sta-
tions are those with sediment contamination associated
with a higher probability of adverse effects. Tier 2 sta-
tions are those associated with a lower to intermediate
probability of adverse effects, and Tier 3 stations are
those with no indication of adverse effects. Figure 3
presents the methodology used to classify sampling
stations in these three tiers. Upper thresholds in Figure
3 include SQCs, ERMs, PELs, and AET (high values).
Lower thresholds include ERLs, TELs, AET (low val-
ues), and SQALs. Human health risk levels include FDA
action levels and EPA risk levels. The distribution of
more than 21,000 sampling stations into these tiers is
illustrated in Figure 4. Of the sampling stations evalu-
ated, 5,521 (26%) were classified as Tier 1, 10,401
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Chemical
Concen-
trations
All 1 or more
ERL
>1 or more
ERM
AII1 or more
TEL
>1 or more
PEL
Amphipod Survival Tests
% not toxic % siqnif. toxic
64
59
45
61
62
49
23
22
13
29
21
13
% highly toxic
12
19
42
10
17
38
More
% not toxic
67
20
13
90
22
14
Sensitive
% signif.
5
15
7
5
19
8
Bioassays
toxic % highly toxic
28
64
80
5
59
78
Rgura 2. Predicting toxfcity with correlative aquatic life screening values. (Long et al., in press)
(49%) were classified as Tier 2, and 5,174 (25%) were in
Tier 3.
Stations were located in 6,744 individual river reaches
(or water body segments) across the contiguous U.S., or
approximately 11% of all river reaches in the country
(based on EPA's River Reach File 1). A river reach can
be part of a coastal shoreline, a lake, or a length of
stream between two major tributaries ranging from ap-
proximately 1 to 10 miles long. Most of the NSI data
were obtained from monitoring programs targeted at
areas of known or suspected contamination. Analysis of
the NSI data indicates that 3.8% of all river reaches in
the contiguous U.S. have at least one station identified
as Tier 1, while 4.5% of reaches have at least one
station identified as Tier 2 (but none as Tier 1), and all of
the sampling stations were identified as Tier 3 in 2.4% of
reaches. Studies conducted by EPA as part of the
Environmental Monitoring and Assessment (EMAP) Pro-
gram suggest that approximately 10% (by area) of the
near coastal water sediments in the Virginian and Loui-
sianan Provinces are sufficiently contaminated to cause
acute toxicity to amphipods (Richard Swartz, Personal
Communication, December 27, 1996). Analysis of the
NSI data indicates that the areal extent of sediment
associated with acute toxicity to amphipods is likely to
range from 6-12% nationally.
Data related to more than 230 different chemicals or
chemical groups were included in the NSI evaluation.
Approximately 40% of the chemicals or chemical groups
were found to occur at levels resulting in classification of
sampling stations as Tier 1 or Tier 2. Figure 5 displays
the sediment contaminants most frequently associated
with potential adverse effects. The contaminants most
frequently occurring at levels in fish or sediment associ-
ated with a higher probability of adverse effects were
PCBs and mercury. Pesticides, most notably DDT and
metabolites and polynuclear aromatic hydrocarbons
(PAHs) were also frequently associated with a higher
probability of adverse effects
Areas of Probable Concern
Areas of probable concern for sediment contamination
(APCs) were identified in the evaluation of NSI data.
APCs are watersheds that include at least ten Tier 1
sampling stations and in which at least 75% of all
sampling stations were classified as either Tier 1 or Tier
2. The NSI data evaluation identified 96 watersheds
Sediment Chemistry Aquatic Sediment Chemistry Tissue Residue Human
Life Human Health Health
Toxicity Tests Aquatic Life
Exceeds 2 upper thresholds*
Tier 1 (or SQC) TBP exceeds risk levels
Exceeds risk levels
[SEMJ-[AVS]>5
and"
2 or more tests (different species)
demonstrate significant mortality
Tier 2 Exceeds 1 lower threshold TBP exceeds risk levels TBP exceeds risk levels
tSEM]-[AVS]>0
At least 1 test demonstrates
significant mortality
Tier 3
None of above conditions met
Except for AVS metals (Cu, Cd, Pb, Ni, Zn)
' Except for PCBs and Dioxins (tissue residue data alone can place site in Tier 1)
Figure 3. Sampie station classification methodology.
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Tier 1: Sampling stations with sediment contamina-
tion associated with a higher probability of adverse
effects
Tier 2: Sampling stations with sediment contamina-
tion associated with a lower to intermediate prob-
ability of adverse effects
Tier 3: No indication of adverse effects (data may be
very limited or quite extensive)
iz.uuu —
10,000 —
8000 —
6000 —
4000 —
2000 -
n —
—
jljijijij
111
|:|
||!
jj:
Figure 4. Classification of NSI sampling stations.
throughout the U.S. as APCs (Figure 6). An ARC desig-
nation could result from extensive sampling throughout
a watershed, or from intensive sampling at a single
contaminated location or a few contaminated locations.
A list of these watersheds, identified by U.S. Geological
Survey cataloging unit and name, is available in EPA's
NSI database. EPA has completed an analysis to iden-
tify, within each of the 96 APC watersheds, the average
percent of stations that are contaminated by various
classes of chemicals. This analysis indicates that at the
Tier 1 level of contamination, PCBs are the dominant
chemical class. At the combined Tier 1 and Tier 2 level
of contamination, metals are the dominant chemical
class of contaminant, followed by PCBs and pesticides,
mercury, PAHs, and other organics. The relative, impor-
tance of these classes of chemicals reflects both the
occurrence of those contaminants in APCs as well as
the evaluation methodology used for the analysis.
Percent of stations indicating a probability of adverse effects
Tierl
Tierl
and 2
PCBs
Mercury
58
20
34
27
Pesticides
PAHs
Metals
Number of Stations
1-15
3-8
14-21
7-13
0-5 7-45
5,521 15,922
Conclusions
Evaluation of the NSI data strongly suggests that sedi-
ment contamination may be significant enough to pose
risks to aquatic life and human health at some locations
in the U.S., particularly within the Areas of Probable
Concern. EPA's evaluation of the NSI data was the most
geographically extensive investigation of sediment con-
tamination ever performed in the U.S. The evaluation
was based on procedures to address the probability of
adverse effects to aquatic life and human health. Based
on the evaluation, sediment contamination exists at
levels indicating a probability of adverse effects in all
regions and states within the U.S. The water bodies
affected include streams, lakes, harbors, nearshore ar-
eas, and oceans. At the most severely contaminated
sites identified in the NSI, PCBs, mercury, organochlo-
rine pesticides, and PAHs are the most frequent chemi-
cal indicators of sediment contamination. The NSI
evaluation methodology was designed to provide a
screening-level assessment of sediment quality. There-
fore, further evaluation may be required to confirm that
sediment contamination poses risks to aquatic life or
human health for any given sampling station or water-
shed. Although Areas of Probable Concern were se-
lected by means of a screening exercise, they represent
the highest priority areas for further ecotoxicological
assessments, risk analyses, temporal and spatial trend
assessment, contaminant source evaluation, and man-
agement action.
Figure 5. Chemical indicators of probable effects.
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Figure 6. Areas (watersheds) of probable concern for sediment contamination.
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References
1. Aurlich, R. J., R.K. Ringer, and S. Iwamoto. 1973.
Reproductive failure and mortality in mink fed on
Great Lakes fish. Journal of Reproductive Fertility
Suppl. 19:365.
2. Barrick, R., S. Becker, L. Brown, H. Heller, and R.
Pastorok. 1988. Sediment Quality Impairment:
1988 Update and Evaluation ofPuget Sound AET.
Volume 1. Prepared for the Puget Sound Estuary
Program, Office of Puget Sound.
3. Baumann, P.C., W D, Smith, and W.K. Parland.
1987. Tumor frequencies and contaminant con-
centrations in brown bullheads from an industrial-
ized river and a recreational lake. Transactions of
the American Fisheries Society 18:706-727.
4. Eisler, R. 1995. Elecroplating wastes in marine
environments. A case history of Quonset Point,
Rhode Island. In: Handbook of ecotoxicology, ed.
DJ. Hoffmann, B.A. Rattner, G.A. Burton, Jr., and
J. Cairns, Jr., pp 609-630. Lewis Publishers, Boca
Raton, Florida.
5. Florida Department of Environmental Protection.
1994. Approach to the assessment of sediment
quality in Florida coastal waters, Vol 1. Develop-
ment and evaluation of sediment quality assess-
ment guidelines. Prepared for Florida Department
of Environmental Protection, Office of Water Policy,
Tallahassee, Florida, by MacDonald Environmen-
tal Sciences, Ltd., Ladysmith, British Columbia.
6. Kubiak, T.J., H.L. Harris, L.M. Smith, T.R.
Schwartz, D.L Stalling, J.A. Trick, L. Sileo, D.E.
Docherty, andT.C. Erdrrian. 1989. Microcontami-
nants and reproductive impairment of Forster's
tern on Green Bay, Lake Michigan, 1983. Ar-
chives of Environmental Contamination and Toxi-
cology 18:706-727.
7. Long, E.R., D.D. MacDonald, S.L Smith, and F.D.
Calder. 1995. Incidence of adverse biological ef-
fects within ranges of chemical concentrations in
marine and estuarine sediments. Environmental
Management 19(1 ):81 -97.
8. Long, E.R., LJ. Field, and D.D. MacDonald. Pre-
dicting toxicity in marine sediments with numerical
sediment guidelines. Submitted to Env. Toxicol.
Chem.
9. Lyman, W.J., A.E. Glazer, J.H. Ong, and S.F.
Coons. 1987. An Overview of Sediment Quality in
the United States. Prepared for U.S. Environmen-
tal Protection Agency, Office of Water Regulations
and Standards, Washington, D.C.
10. Pitt, R.E. 1995. Effects of urban runoff on aquatic
biota. In: Handbook of Ecotoxicology, ed. D.J.
Hoffmann, B.A. Rattner, G.A. Burton, Jr., and J.
Cairns, Jr., pp 609-630. Lewis Publishers, Boca
Raton, Florida.
11. Salomons, W., N,M. De Rooji, H. Kerdijk, and J.
Bril. 1987. Sediment as a source for contami-
nants? Hydrobiologia 149:13-30.
12. Swartz, R.C., W.A. Deben, K.A. Sercu, and J.O.
Lamberson. 1982. Sediment toxicity and distribu-
tion of amphipods in Commencement Bay, Wash-
ington, U.S.A. Marine Pollution Bulletin 13:359-
364.
13. Van Veld, P.A., D.J. Westbrook, B.R. Woodin,
R.C. Hale, C.L. Smith, R.J. Huggett, and J.J.
Stegman. 1990. Induced cytochrome P-450 in
intestine and liver of spot (Leiostomus xanthurus)
from a polycyclic aromatic contaminated environ-
ment. Aquatic toxicology 17:119-132.
14. U.S. EPA. 1989. Risk Assessment Guidance for
Superfund. Volume 1. Human Health Evaluation
Manual. Interim final OSWER Directive 9285.7-
01 a. U.S. Environmental Protection Agency, Of-
fice of Solid Waste and Emergency Response,
Washington, D.C. December, 1989.
15. U.S. EPA. 1992. Sediment Classification Methods
Compendium. EPA 823-R-92-006. U.S. Environ-
mental Protection Agency, Office of Water, Wash-
ington, D.C.
16. U.S. EPA. 1993. Technical Basis for Establishing
Sediment Quality Criteria for Nonionic Organic
Contaminants for the Protection pfBenthic Organ-
isms by Using Equilibrium Partitioning. Draft. EPA
822-R-93-011. U.S. Environmental Protection
Agency. Office of Science and Technology, Health
and Ecological Criteria Division, Washington, D.C.
17. U.S. EPA. 1994. Guidance for Assessing Chemi-
cal Contamination Data for Use in Fish Advisories,
Volume II : Development of risk-based intake
limits. U.S. Environmental Protection Agency, Of-
fice of Science and Technology, Washington, D.C.
18. U.S. EPA and U.S. Army Corps of Engineers.
1998. Evaluation of Dredged Material Proposed
for Discharge in Waters of the U.S. - Testing
manual EPA-823-B-98-004. U.S. Environmental
Protection Agency, Office of Water and U.S. Army
Corps of Engineers, Washington, D.C.
19 U.S. EPA. 1997(a) The Incidence and Severity of
Sediment Contamination in Surface Waters of the
United States. Volume 1: National Sediment Qual-
ity Survey. EPA-823-R-97-006. U.S. EPA Office of
Science and Technology, Washington D.C.
-------
20. U.S. EPA. 1997(b) The Incidence and Severity of
Sediment Contamination in Surface Waters of the
United States. Volume 2: Data Summaries for
Areas of Probable Concern. EPA-823-R-97-007.
U.S. EPA Office of Science and Technology, Wash-
ington D.C.
21. U.S. EPA. 1997(c) The Incidence and Severity of
Sediment Contamination in Surface Waters of the
United States. Volume 3: National Sediment Con-
taminant Point Source Inventory. EPA-823-R-97-
008. U.S. EPA Office of Science and Technology,
Washington D.C.
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EPA Role in Managing Contaminated Sediment
Thomas M. Armitage and Jane Marshall Farris
Office of Science and Technology
U.S. Environmental Protection Agency
Washington, D.C.
More than ten federal statutes provide authority to many
EPA program offices to address the problem of contami-
nated sediment. These statutes provide authority for
activities such as regulating the use of pesticides and
toxic substances that may accumulate in sediment,
remediating in-place sediment contamination, control-
ling the industrial and municipal discharge of sediment
contaminants to water and air, and regulating the dis-
posal of dredged material. Authority for these activities
is provided to EPA under such statutes as: the National
Environmental Policy Act (NEPA), the Clean Air Act
(CAA), the Coastal Zone Management Act, the Federal
Insecticide, Fungicide, and Rodenticide Act (FIFRA), the
Marine Protection Research and Sanctuaries Act
(MPRSA), the Resource Conservation and Recovery
Act (RCRA), the Toxic Substances Control Act (TSCA),
the Clean Water Act (CWA), and the Comprehensive
Emergency Response, Compensation, and Liability Act
(CERCLA). A complete summary of EPA authorities for
addressing sediment contamination is provided in Con-
taminated Sediments - Relevant Statutes and EPA Pro-
gram Activities (U.S. EPA, 1990).
EPA program offices implement contaminated sediment
management activities or coordinate implementation
where EPA has established geographically focused pro-
grams, such as the Chesapeake Bay, the Great Lakes,
and the Gulf of Mexico. EPA program offices with sedi-
ment management responsibilities include: the Office of
Water, the Office of Pollution Prevention and Toxics, the
Office of Pesticide Programs, the Office of Emergency
and Remedial Response, and the Office of Solid Waste.
EPA's Office of Research and Development conducts
research to support sediment management activities
conducted by the program offices.
Contaminated Sediment Management
Goals
EPA's Contaminated Sediment Management Strategy
(EPA, 1998) describes actions the Agency intends to
take to a accomplish four strategic sediment manage-
ment goals: 1) prevent further sediment contamination
that may cause unacceptable ecological or human health
risks; 2) reduce the volume of contaminated sediment
that adversely affects the Nation's water bodies or their
uses, or that causes other significant effects on human
health or the environment; 3) ensure that sediment
dredging and dredged material disposal are managed in
an environmentally sound manner; 4) develop and con-
sistently apply methodologies for analyzing contami-
nated sediments.
Elements of Contaminated Sediment
Management
EPA can accomplish the Agency's strategic goals for
management of contaminated sediment by taking action
in the areas of contaminated sediment assessment,
prevention, remediation of dredged material, research,
and outreach. This paper summarizes EPA's; role in
each of these areas.
Assessment
Many different methods have been developed to assess
contaminated sediment. EPA is working to develop im-
proved assessment methods, standardize the assess-
ment methods, and ensure that all Agency program
offices use standard methods to determine whether
sediments are contaminated. The Agency has also de-
veloped chemical-specific sediment quality criteria for
the assessment of contaminated sediment. EPA has
developed standard acute sediment toxicity test meth-
ods, and the Agency is currently developing standard
chronic sediment toxicity test methods. In addition, EPA
has developed a national inventory of sites and sources
of sediment contamination. A screening level assess-
ment of data in this inventory has been completed, and
the Agency has published the National Sediment Quality
Survey, a Report to Congress on the Incidence and
Severity of Sediment Contamination in Surface Waters
of the United States, (EPA, 1997 [a] [b] [c]). EPA can
use the National Sediment Inventory data to help iden-
-------
tify sites associated with adverse effects to human health
and the environment. Through the use of consistent
sediment assessment methods and the National Sedi-
ment Inventory, EPA can focus on cleaning up the most
contaminated water bodies and ensuring that further
sediment contamination is prevented. The EPA Office of
Water can use standard sediment toxicity and
bfoaccumulation test methods for monitoring and inter-
pretation of narrative water quality standards. The EPA
Office of Pesticide Programs pesticides can use stan-
dard sediment toxicity tests when registering or reregis-
tering pesticides. The EPA Office of Pollution Prevention
and Toxics can use standard sediment toxicity tests to
assess the toxicity of industrial use chemicals. The EPA
Office of Emergency and Remedial Response can use
standard sediment toxicity and bioaccumulation test
methods to evaluate contaminated sediment sites by
incorporating these methods into remedial investigation
and feasibility studies, and the EPA Office of Solid
Waste can use biological sediment toxicity test methods
for assessing and monitoring contaminated sediment at
hazardous waste facilities. Sediment quality criteria, when
final, can be used by all EPA program offices conducting
sediment monitoring to interpret sediment chemistry
data.
Prevention
EPA's role in prevention of contaminated sediments
involves the use of authority provided under the Clean
Water Act, the Federal Insecticide Fungicide, and Ro-
denticide Act, and the Toxic Substances Control Act to
control the discharge of toxic sediment contaminants to
surface waters, and to regulate the use of pesticides and
industrial use chemicals, in order to regulate the use of
pesticides that may accumulate to toxic levels in sedi-
ment, EPA can include sediment toxicity assessment in
the review processes required to support registration,
reregistration, and special review of pesticides likely to
sorb to sediment. In addition, EPA can require sediment
toxicity assessment to support industrial uses of new
chemicals, and EPA can develop guidelines for the
design of new chemicals to reduce the bioavailability
and partitioning of toxic chemicals to sediment.
EPA's Office of Enforcement and Compliance Assur-
ance can take action to prevent sediment contamination
by negotiating, in appropriate cases of noncompliance
with permits, enforceable agreements to require sedi-
ment contaminant source recycling and source reduc-
tion activities. The Agency can also monitor the progress
of federal facilities toward emissions reduction goals.
EPA's Office of Water and other EPA program offices
can work with nongovernmental organizations and the
slates to prevent point and nonpoint sources of contami-
nants from accumulating in sediments. EPA can take
the following actions to regulate point and nonpoint
sources of sediment contaminants: 1) promulgation of
new and revised technology based effluent guidelines
for industries that discharge sediment contaminants; 2)
encouragement of states to use biological sediment test
methods and sediment quality criteria to interpret narra-
tive water quality standards of "no toxics in toxic amounts";
3) encouragement of states to develop Total Maximum
Daily Loads for impaired watersheds specifying point
and nonpoint source load reductions necessary to pro-
tect sediment quality; 4) use of discharge data to identify
point sources of sediment contaminants for potential
permit compliance tracking after evaluation using pro-
gram-specific criteria; 5) ensuring that discharges from
CERCLA and RCRA facilities subject to NPDES permits
comply with future NPDES permit requirements to pro-
tect sediment quality; and 6) use of National Sediment
Inventory data to identify watersheds where technical
assistance and grants could effectively be used to re-
duce nonpoint source loads of sediment contaminants.
Remediation
EPA has an important role in remediation of contami-
nated sediment. Under a number of statutes, EPA can to
take action directed at remediation of contaminated
sediment. Where sediments are contaminated to levels
that cause ecological harm or pose a risk to human
health, EPA may implement a range of remediation
strategies to effectively reduce the risk. In certain cir-
cumstances, the best strategy may be to implement
pollution prevention measures as well as point and
nonpoint source controls, to allow natural recovery pro-
cesses such as biodegradation, chemical degradation,
and the deposition of clean sediments to diminish the
risks associated with the sites. In other cases, active
remediation is necessary. Statutory authority enables
EPA to 1) compel responsible parties to clean up the
sites they have contaminated, 2) recover costs from
responsible parties for EPA-performed cleanups, and 3)
coordinate with natural resource trustees to seek restitu-
tion from responsible parties. EPA's Office of Water,
Office of Emergency and Remedial Response, Office of
Solid Waste, and Office of Enforcement and Compli-
ance Assurance can use National Sediment Inventory
data, and other high quality data, to help target sites for
further study that may lead to enforcement action requir-
ing contaminated sediment remediation.
Dredged Material Management
EPA and the Corps of Engineers are responsible for the
dredged material discharge permitting process under
the Marine Protection Research and Sanctuaries Act
and the Clean Water Act. The program is responsible for
implementing cost-effective, environmentally sound op-
tions for disposal and management of contaminated
dredged material.
Contaminated Sediment Research
EPA's Office of Research and Development, working
with the Agency's other program offices, conducts con-
taminated sediment research. Research is conducted to
understand the extent and severity of sediment contami-
nation, develop methods and data to assess human
health and ecological effects of sediment contaminants,
10
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develop and validate chemical-specific sediment quality
criteria, and to develop and evaluate sediment cleanup
methods.
Contaminated Sediment Planning and
Outreach Processes
Outreach is also a critical component of EPA's role in
contaminated sediment management. Public understand-
ing of the ecological and human health risks associated
with sediment contamination, and of solutions to the
problem, is key to successfully managing contaminated
sediment. EPA's role in outreach is to educate key
audiences about the risks, extent, and severity of con-
taminated sediment. EPA can engage stakeholders by:
1) defining sediment management themes or messages,
2) identifying target audiences and needs, 3) developing
appropriate outreach materials, and 4) providing chan-
nels to facilitate two-way communication on sediment
management issues. EPA can communicate four con-
taminated sediment themes to target audiences. The
first theme is that sediment contamination comes from
many sources, which must be identified, and that source
control options must be evaluated according to risk
reduction potential and effectiveness. The second theme
is that sediment contamination poses threats to human
health and the environment. The risks must be identified
and effectively communicated to the public. The third
theme is that sediment contamination can be effectively
managed through assessment, prevention, and
remediation. The fourth theme is that EPA's strategy for
managing contaminated sediment will depend upon in-
teragency coordination and on building alliances with
other agencies,.industry, and the public.
References
1. U.S. Environmental Protection Agency. 1990. Con-
taminated Sediments, Relevant Statutes and EPA
Program Activities. EPA-506-6-90-003. U.S. Envi-
ronmental Protection Agency, Washington, D.C.
2. U.S. Environmental Protection Agency. 1998.
EPA's Contaminated Sediment Management Strat-
egy. EPA-823-F-98-001. U.S. Environmental Pro-
tection Agency, Washington D.C.
3. U.S. Environmental Protection Agency. 1997(a).
The Incidence and Severity of Sediment Contami-
nation in Surface Waters of the United States.
Volume 1: National Sediment Quality Survey. EPA-
823-R-97-006. U.S. EPA Office of Science and
Technology, Washington D.C.
4. U.S. Environmental Protection Agency. 1997(b).
The Incidence and Severity of Sediment Contami-
, nation in Surface Waters of the .United States.
Volume 2: Data Summaries for Areas of Probable
Concern. EPA-823-R-97-007. U.S. EPA Office of
Science and Technology, Washington D.C.
5. U.S. Environmental Protection Agency. 1997(c).
The Incidence and Severity of Sediment Contami-
nation in Surface Waters of the United States.
Volume 3: National Sediment Contaminant Point
Source Inventory. EPA-823-R-97-008. U.S. EPA
Office of Science and Technology, Washington
D.C.
11
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Strategies and Technologies For Cleaning Up
Contaminated Sediments in the Nation's Waterways: A
Study by the National Research Council
Spyros P. Pavlou
Member, NRC Marine Board Committee on Contaminated Marine Sediments, 1993-1996
Technical Director of Environmental Risk Economics, URS Greiner Inc., Seattle, WA
Louis J. Thibodeaux
Member, NRC Marine Board Committee on Contaminated Marine Sediments, 1993-1996
Emeritus Director, Hazardous Substance Research Center (South/Southeast), USEPA and Jesse Coates Professor of
Chemical Engineering, Louisiana State University, Baton Rouge, LA
Introduction
This presentation is an overview of a study performed by
the National Research Council (NRC) Marine Board
Committee on Contaminated Marine Sediments. The
fifteen-member committee included national experts from
academia, industry, and the professional services sec-
tor. The committee was established in the spring of 1993
and completed its work in the summer of 1996. The
committee's deliberations were published in a report
released by the NRC in March 1997.
The committee's activities were sponsored through the
NRC by the US Environmental Protection Agency
(USEPA), the US Army Corps of Engineers (USAGE),
the US Navy, the National Marine Fisheries Service of
the US Department of Commerce, the Maritime Admin-
istration of the US Department of Transportation, and
the US Geological Survey. The names and affiliations of
the committee members, government liaison represen-
tatives, and NRC staff are listed in Table 1.
The Challenge
Contaminated marine sediments pose a threat to eco-
systems, marine resources, and human health. Sedi-
ment contamination also interferes with shipping activities
and growth of trade resulting from delays in dredging
and/or the inability to dredge the nation's harbors due to
controversies over risks and costs of sediment manage-
ment Given that approximately 95% of total U.S. trade
passes through dredged ports, potential economic im-
pacts due to sediment contamination may be severe.
The management of contaminated sediments is a com-
plex and difficult process. The factors that contribute to
the complexity are multiple and, in combination, exacer-
bate the problem. In summary, these are:
High public expectations for protecting human
health and the environment
.Multiple stakeholder interests and priorities
Conflicting and overlapping jurisdictions of fed-
eral, state, and local regulatory authorities
Relatively low levels of contamination
Large quantities of affected sediments
Uncertainty in quantifying and managing risk
Limitations of handling and treatment technolo-
gies
All of the above factors may result in non-cost-effective
management actions with controversial outcomes and
marginal benefits.
Conceptual Framework for Contaminated
Sediment Management
The committee recognized the challenges associated
with contaminated sediment management and devel-
oped a risk-based framework for making management
decisions and for selecting remediation technologies.
This framework, presented in Figure 1, provides the
12
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Table 1.
Committee on Contaminated Marine Sediments
HENRY BOKUNIEWICZ, co-chair, State University of New York at Stony Brook
KENNETH S. KAMLET, co-chair, Linowes and Blocher
W. FRANK BOHLEN, University of Connecticut, Avery Point
J. FREDERICK GRASSLE, Rutgers University
DONALD F. HAYES, University of Nebraska
JAMES R. HUNT, University of California at Berkeley
DWAYNE G. LEE, Ralph M. Parsons Company
KENNETH E. MCCONNELL, University of Maryland
SPYROS P. PAVLOU, URS Greiner, Inc
RICHARD PEDDICORD, EA Engineering, Science, and Technology
PETER SHELLEY, Conservation Law Foundation, Inc.
RICHARD SOBEL, Clean Sites, Inc.
LOUIS J. THIBODEAUX, Louisiana State University
JAMES G. WENZEL, NAE, Marine Development Associates, Inc.
LILY Y. YOUNG, Rutgers University
Government Liaison Representatives
SABINE APITZ, U.S. Navy
CHARLES C. CALHOUN, U.S. Army Waterways Experiment Station
MILES CROOK National Marine Fisheries Service
ROBERT ENGLER, U.S. Army Waterways Experiment Station
KENNETH HOOD, U.S. Environmental Protection Agency
EVIE KALKETENIDOU, Maritime Administration
DANIEL LEUBECKER, Maritime Administration
FRANK MANHEIM, U.S. Geological Survey
JANET MORTON, U.S. Geological Survey
ANNA PALMISANO, U.S. Navy
CARL SOBREMISANA, Maritime Administration
MARK SPRENGER, U.S. Environmental Protection Agency
CRAIG VOGT, U.S. Environmental Protection Agency
LARRY ZARAGOZA, U.S. Environmental Protection Agency
Staff
JOSEPH L. ZELIBOR, Project Officer
LAURA OST, Editor
13
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basis for a systematic and consistent approach to con-
taminated sediment management, including dredging
and disposal.
It must be emphasized here that the approach appears
similar to existing decision-making frameworks devel-
oped by USEPA and USAGE. One of these decision-
making frameworks was developed by USEPA for
evaluating alternatives for remediation in Superfund
projects. The other was developed jointly by USEPA
and USAGE for evaluating alternatives for the disposal
of dredged material associated with navigation projects.
While the committee recognized the utility of these
formal decision-making approaches, this schematic rep-
resentation (Figure 1) has a different purpose. It was
developed as a generic overview of the contaminated
sediment management process to assist the committee
members in addressing the various decision compo-
nents in a logical sequence of evaluations.
Scope of the Study and Approach
The committee's charge was to: (1) assess best man-
agement practices and emerging technologies for re-
ducing adverse environmental impacts; (2) appraise
interim control measures for use at contaminated sedi-
ment sites; (3) address how information about risks,
costs, and benefits can be used and communicated to
guide decision making and; (4) assess existing knowl-
edge and identify research needs for enhancing con-
taminated sediment remediation technology.
Technical information was reviewed and assessed. Com-
mittee members interacted closely with researchers,
regulators, stakeholders, engineers and operators. Six
case studies of contaminated sediment remediation were
evaluated and one sediment remediation project site
was visited. In addition, the committee conducted work-
shops on interim controls and long-term technologies,
summarized site assessment methods, and evaluated
the application of decision tools to the contaminated
sediment management process.
The results obtained from the above tasks were then
assembled and organized under three major categories:
decision making, remediation technologies, and project
implementation. Opportunities for improvement were
identified in all categories. The discussion that follows
summarizes the committee's conclusions and recom-
mendations.
Conclusions and Recommendations
Improving Decision Making
Factors influencing decision making include regulatory
realities, stakeholder interests, site-specific characteris-
tics and data uncertainty, and availability of remediation
technologies. The committee examined all of the above
factors in making the following conclusions and recom-
mendations:
Stakeholder involvement early in the decision pro-
cess is important in heading off disagreements
and building consensus among all parties involved.
In situations where decisions are complex and
divisive, obtaining consensus among stakehold^
ers can be facilitated by using formal analytical
tools, e.g., decision analysis.
The trade-off evaluation of risks, costs and ben-
efits and the characterization of their associated
uncertainties in selecting a preferred manage-
ment alternative offer the best chance for effective
management and communication of the decision-
making process to stakeholders.
Risk analysis is an effective method for selecting
and evaluating management alternatives and
remediation technologies. More extensive use of
appropriate methods for cost-benefit analysis has
the potential to improve decision making.
The USEPA and USAGE should sponsor research
to quantify, the relationship between contaminant
availability and corresponding human health and
ecological risks. The main goal is to evaluate
projects using performance-based standards, i.e.,
risk reduction from in-place sediments, disturbed
sediments and sediments under a variety of con-
tainment, disposal and treatment scenarios. This
information is critical to the successful trade-off
evaluations of risks, costs, and benefits to make
technically defensible decisions in selecting a pre-
ferred management alternative.
The use of systems engineering can strengthen
project cost effectiveness and acceptability. In
choosing a remediation technology, systems engi-
neering can help ensure that the solution meets
all removal, containment, transport, and place-
ment requirements while satisfying environmen-
tal, social and legal demands.
Federal, state, and local agencies should work
together with appropriate private sector stake-
holders to interpret statutes, policies, and regula-
tions in a constructive manner so that negotiations
can move forward and sound solutions are not
blocked or obstructed.
The USEPA and USAGE should continue to de-
velop uniform or parallel procedures to address
human health and environmental risks associated
with freshwater, marine, and land-based disposal,
containment, or beneficial reuse of contaminated
sediments.
The USEPA and USAGE should develop and
disseminate information to stakeholders regard-
ing: the availability and applicability of decision
analytical tools; appropriate risk analysis tech-
niques to be used throughout the management
process, including the selection and evaluation of
15
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Solving Great Lakes Contaminated Sediment Problems
Marc Tuchman and Callie Bolattino
U.S. Environmental Protection Agency
Great Lakes National Program Office
Chicago, IL
Jan Miller
U.S. Army Corps of Engineers
Great Lakes and Ohio River Division
Chicago, IL
Introduction
Formed by glacial activity approximately 12,000 years
ago, the Great Lakes comprise a unique ecosystem
that, as a result of industrialization and human interven-
tion, has been degraded over time. The five lakes hold
95% of the surface freshwater found in the United States
and represent 18% of the world's supply of surface
freshwater. This wealth of freshwater reaches deep into
North America, sustaining abundant and diverse popu-
lations of plants and animals, providing a drinking water
supply to support 24 million people and yielding the
mobility to enhance technological production and trans-
portation (1).
Years of point and nonpoint source discharges from
industrial and municipal facilities and urban and agricul-
tural runoff to the Great Lakes and its tributaries have
introduced toxic substances to the Great Lakes ecosys-
tem. The slow flushing process of replenishing water in
the lakes allows contaminants in the water column to
settle out and accumulate in bottom sediments. As a
result, sediments have become a repository for contami-
nants. Though discharges of toxic substances to the
Great Lakes have been reduced in the last 20 years,
persistent high concentrations of contaminants in the
bottom sediments of rivers and harbors have raised
considerable human concern about potential risks to
aquatic organisms, wildlife and humans. As a result,
advisories against fish consumption are in place in most
locations around the Great Lakes.
In 1987, a protocol (Annex 14) that was added to the
already existing Great Lakes Water Quality Agreement
between the United States and Canada (originally signed
in 1972) specifically recognized that there is a need to
jointly address concerns about persistent toxic contami-
nants in the Great Lakes (2). It went on to direct that the
information obtained in addressing these concerns be
used to guide development of Lakewide Management
Plans and Remedial Action Plans (RAPs) for specific
Areas of Concern (AOCs) in the Great Lakes Basin.
These 43 AOCs (Figure 1) are defined as places where
beneficial uses of water resources such as drinking,
swimming, fishing and navigation are impaired by an-
thropogenic pollution or perturbation. It has been docu-
mented by the International Joint Commission that
sediment contamination is a major cause of such impair-
ment in 42 of the 43 AOCs (3). For the 31 AOCs on the
U.S. side, all RAPs written to date have identified con-
taminated bottom sediments as a significant problem
that must be addressed to restore beneficial uses (4).
In an attempt to focus efforts on the issue of contami-
nated sediments, in the 1987 amendments to the Clean
Water Act, Congress authorized the U.S. Environmental
Protection Agency's (EPA) Great Lakes National Pro-
gram Office (GLNPO) to coordinate and conduct a 5-
year study and demonstration project relating to the
appropriate treatment of toxic pollutants in bottom sedi-
ments. Five areas were specified by Congress as requir-
ing priority consideration in conducting demonstration
projects: Ashtabula River, OH; Buffalo River, NY; Grand
Calumet River, IN; Saginaw Bay, Ml; and Sheboygan
Harbor, Wl. To fulfill the requirements of this Congres-
sional mandate, GLNPO initiated the Assessment and
Remediation of Contaminated Sediments (ARCS) Pro-
gram. ARCS was an integrated program for the develop-
ment and testing of remedial action alternatives for
contaminated sediments.
18
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Figure 1. Forty-three areas of concern where beneficial use of water resources is impaired.
A primary goal of the ARCS Program was to develop an
integrated, comprehensive approach to assessing the
extent and severity of sediment contamination, assess-
ing the risks associated with that contamination, and
selecting appropriate remedial responses. The program
developed the following objectives that .were designed
to meet this goal and the requirements of the Clean
Water Act:
Assess the nature and extent of bottom sediment
contamination at selected Great Lakes AOCs;
Demonstrate and evaluate the effectiveness of
selected remedial options, including removal, im-
mobilization, and advanced treatment technolo-
gies, as well as the "no action" alternative; and
Provide guidance on contaminated sediment prob-
lems and remedial alternatives in the AOCs and
other locations in the Great Lakes (5).
Consistent with these objectives, the ARCS Program
directed its efforts toward developing and demonstrating
sediment assessment and cleanup approaches that were
scientifically sound, and technologically and economi-
cally feasible.
In meeting the set objectives, issues such as determin-
ing the nature and extent of sediment contamination,
defining three-dimensional boundaries of sediment prob-
lems, identifying available remedial alternatives and their
likelihood of success, determining the environmental
impacts of remediation and calculating the economic
costs associated with remedial actions were addressed.
The major findings and recommendations of the ARCS
Program included:
Use of an integrated sediment assessment ap-
proach, incorporating chemical analyses, toxicity
testing and benthic community surveys, is essen-
tial to define the magnitude and extent of sedi-
ment contamination at a site.
Risk assessment and modeling activities are valu-
able techniques for evaluating the potential im-
pacts associated with contaminated sediments.
A number of treatment technologies are effective
in removing or destroying sediment contamina-
tion.
Broad public involvement and education are criti-
cal in any sediment assessment and remedy se-
19
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lection study in order to develop a common under-
standing of the problem and the environmental
and economic impacts of alternative remedial ac-
tions (5).
Though the ARCS Program was completed in August
1994, the guidance that was provided and the technical
knowledge that was gained continue to influence the
ongoing process of addressing contaminated sediments
in the U.S. AOCs.
Assessment
In response to the momentum gained from the ARCS
Program in evaluating sediment contamination in the
Great Lakes, various assessment tools have been uti-
lized and have proven to be beneficial in obtaining an
understanding of sediment contamination and dynam-
ics. A few of these tools include:
Chemical and Biological Testing
Research Vessel (R/V) Mudpuppy
Acoustical Mapping of Bottom and Subbottom
Sediments
• Sediment Resuspension Modeling
Database Management
Chemical and Biological Testing—One of the recom-
mendations from the ARCS Program that is continually
utilized to define the nature and extent of sediment
contamination at a particular site is the integrated sedi-
ment assessment approach (6, 7). This integrated ap-
proach Involves performing chemical analyses to
determine which toxic substances are present; toxicity
testing to provide information on how toxic substances
are affecting organisms; and benthic community sur-
veys to evaluate the long-term impacts that may result
from toxic contamination. Integration of these results
thus provides a clear picture of the amounts and effects
of contaminants present in the sediments.
R/V Mudpuppy—Conducting integrated sediment as-
sessments typically requires that many samples be taken
in order to adequately characterize the magnitude and
extent of contamination at a given site. One such route
for gathering the assessment samples and site informa-
tion has been through the use of the R/V Mudpuppy.
The Mudpuppy is a 32-foot flat-bottom boat specifically
designed for sediment sampling in shallow rivers and
harbors. It is equipped with a vibro-coring unit that
allows the sampling of cores up to 15 feet long. It also
has a differentially corrected global positioning system
(GPS) with submeter accuracy that allows for precise
and accurate determinations of sample locations. Once
samples are collected, they can be subsampled and
processed on board or at land-based facilities. A triple-
axle trailer allows the vessel to be transported easily
from one project location to the next.
GLNPO typically works closely with state agencies and
local communities involved in the RAP process to de-
velop sampling plans, testing protocols, and Quality
Assurance Project Plans (QAPPs) for individual projects.
Mudpuppy surveys provide data that allow the three-
dimensional mapping of these project sites. To date, the
Mudpuppy has been used to perform sediment assess-
ments at 18 Great Lakes AOCs (Figure 2). Typically,
projects implement an integrated sediment assessment
in a two-phased approach. The first phase includes a
comprehensive sampling of the entire AOC to help
pinpoint the location of "hot spots." These hot spots are
then delineated in the second phase to provide informa-
tion necessary for making remedial decisions. The over-
all goal of this effort is to generate the information
needed to make scientifically defensible remediation
decisions.
Acoustical Mapping of Bottom and Subbottom Sedi-
ments—A cost-effective and rapid means of mapping
the distribution of sediments in harbors and rivers facili-
tates the remediation decisions facing environmental
managers and forms the basis for any remediation plan.
Presently, sediment cores are collected at preselected
sites and the sediment lithography is extrapolated be-
tween core sites. Often, due to spatial variation, this
extrapolation provides inaccurate estimates of soft sedi-
ment volume and distribution which may require
remediation.
Acoustical profiling of bottom and subbottom sediments
may provide an accurate cost-effective method for map-
ping sediment distribution. The acoustical coring analy-
sis method developed by Caulfield Engineering and
applied, under contract to the U.S. Army Corps of Engi-
neers, Waterways Experiment Station, was developed
to classify sediments for dredging operations. This ap-
proach has been shown to have an accuracy of 95% in
estimating density in normal marine sediments (8). This
technology has been transferred for use in mapping
sediment distribution in harbors and rivers of the Great
Lakes. Figure 3, illustrates the acoustical profiling method.
This technology has been demonstrated on a pilot basis
in the Detroit River's Trenton Channel. The Trenton
Channel provided sites of shallow water depth (2-30
feet) and sediments exhibiting high spatial variability
and micro-gas bubble content. Survey line cross-sec-
tions were plotted from the acoustical data and illustrate
horizontal and vertical sediment distribution. Sediment
core lithography has been overlaid on the acoustical
lithography demonstrating the close agreement between
collected cores and acoustical sediment density esti-
mates (Figure 4). Acoustical data can also be used to
plot the location and volume of soft sediment deposits
which may require removal. The results of this Trenton
Channel work will be evaluated to determine its applica-
bility to other AOCs.
Sediment Resuspension Modeling—When attempt-
ing to remediate contaminated sediments it is-important
not only to know the chemical and biological composi-
20
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x R.and
L6wer Green Bay
White L.
ri / . ^Pine R.
Presque Isle Bay
Ashtabula R.
Grand Calumet R.
and Indiana
Harbor Canal
Figure 2.
Nineteen Great Lakes sites sampled with R/V Mudpuppy.
tion of the sediments, but also to understand the
resuspension/erosion properties associated with the sedi-
ments. Most contaminants are sorbed to fine-grained
sediments which are buried at depths of up to several
meters. It is critical to understand whether these buried
contaminated sediments can be exposed and eroded
during large floods and storms. Hydrodynamic models
can be utilized to quantitatively predict changes in vol-
umes, depths, and velocities of water in response to
changes in flow and water surface elevation. Addition-
ally, the models can be used to understand the
resuspension and erosion properties of sediments at
high-sheer stress during flood and storm events (9).
Under the ARCS Program, researchers at the University
of California, Santa Barbara, investigated the
resuspension properties of bottom sediments in two
Great Lakes AOCs through the use of laboratory experi-
ments, field measurements and numerical models. To
obtain data for model inputs they utilized an annular
flume, a portable resuspension device (Shaker) and
later, a Sediment Erosion at Depth Flume (Sedflume).
All of these methods enhanced the researchers ability to
approximate the resuspension properties of undisturbed
sediments as a function of sheer stress and time after
deposition. Their results highlighted the potential of these
techniques by determining distinct differences in
resuspension properties between the sediments in each
of the rivers and between muddy and sandy sediments
within a river (10).
Database Management—Another important component
of a sediment assessment program involves the clear
and concise management of all chemistry data, as well
as toxicity and benthos data. Having all the available
data for a particular area in a database can provide the
basis for short- and long-term decision making. The
combination of a database and GIS mapping capabili-
ties enhances both Agency decision making and public
education at all stages of a sediment project.
Toward Remediation
Following completion of the characterization and as-
sessment of a site, a determination must be made as to
whether remediation will be required. If so, a variety of
remedial options should be evaluated and a suitable
option ultimately selected. Historically, placement of sedi-
ments in a confined disposal facility (CDF) or landfill has
been the option of choice. Recently however, there has
been more effort placed into examining the feasibility of
using alternative treatment technologies as a method for
remediating contaminated sediments.
21
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Typical Shallow Seismic System Configuration
Calibration
Amplifiers
Layer 4
Figure 3. Typical shallow seismic system configuration.
The U.S. EPA's ARCS Program was one of the first
programs in the Great Lakes to examine the feasibility of
utilizing treatment technologies as an alternative to plac-
ing contaminated sediments in CDFs. The ARCS Pro-
gram evaluated and demonstrated in the laboratory and
field the effectiveness, feasibility and cost of numerous
remediation treatment technologies (5). A number of the
technologies tested were found to be technically fea-
sible, although they varied in their effectiveness depend-
ing on the contaminants present. All options did cost
more than traditional confined disposal.
Guidance on making remedial decisions based on the
results of these activities is provided in the ARCS
Remediation Guidance Document^ 1). Of the treatment
technologies evaluated and demonstrated by the ARCS
Program, no single technology was effective for all
contaminants. Technologies that extract contaminants
from sediments were identified as having high potential
for successful remediation. Cost savings can be achieved
by applying extractive technologies first, thus reducing
the volume of material requiring further treatment by
more expensive destructive methods.
ARCS Bench-Scale Demonstrations
The ARCS Program examined more than 250 treatment
technologies, most of which had been previously dem-
onstrated on contaminated sediments. Of these, nine
were selected for bench-scale testing and four were
selected for pilot-scale demonstration projects. The nine
technologies selected for bench-scale work were tested
in the laboratory on up to a few kilograms of sediment
collected from the priority AOCs. The selection of tech-
nologies to be used depended on matching the charac-
teristics of each technology with the specific sediment
type and contaminants present. The results of the bench-
scale testing provided preliminary feasibility data and
design data for the pilot-scale demonstrations.
ARCS Pilot-Scale Demonstrations
Pilot-scale demonstrations were conducted at the five
ARCS priority AOCs and involved the onsite field testing
of up to several thousand cubic yards of sediment.
Thermal Desorption at Buffalo River, NY—Low tem-
perature thermal desorption, which uses indirect heat to
separate organic contaminants from contaminated sedi-
ments through volatilization, was demonstrated on 12
cubic yards of sediment from the Buffalo River (12).
Organic contaminants are volatilized from the sediments
and then condensed and collected in a separate re-
sidual oil product. This technology was used in the
Buffalo River specifically to examine its effectiveness at
removal of the polycyclic aromatic hydrocarbon (PAH)
fraction, which is of particular concern at this site. This
22
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Data File: BP010000
Subfile: 2 3
Geographical Position •
BP010001
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72.965.80N
4,098,819.DOE
BP010002
5 0
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-10
CORE 17/18
(APPROXIMAT
73,035.96N
4,098,833.45E
0 5 10m
LATERAL DISTANCE SCALE
Basic Soil Description
foam/fluff
clay
silty clay to clayey silt
jsllt
silty 'sand to sandy silt
sand
hard/compact
Density
gm/cc
1.0-1.3
1.3-1.4
t.4-1.6
1.6-1.8
1.8-2.2
>2.2
::•:::•:•::
W//S
'ffiffl/
wHflm,
"w&ft'iife
\-.:-,t;\-f-f-
Ji*JlmJI*f*fm^,
Figure 4. Sediment cross section from accoustical survey ori Trenton Channel, Ml.
process removed more than 80% of the PAHs present in
the Buffalo River sediments.
Sediment Washing at Saginaw River, Ml— Sediment
washing was demonstrated at the Saginaw River AOC
on approximately 400 cubic yards of sediment (13). This
technology utilizes equipment such as hydrocyclones to
separate material into different sized particles. The sedi-
ment washing process was very effective in separating
clean sands from contaminated silts and clays, and
produced a clean sand fraction, representing about 75%
of the mass of the feed material. This clean fraction
could then be considered for beneficial reuse instead of
requiring confinement. The demonstration initiated by
ARCS was continued by the U.S. EPA's Superfund
Innovative Technology Evaluation (SITE) program to
examine different operational systems.
Solvent Extraction at Grand Calumet River, IN—The
Basic Extractive Sludge Technology (B.E.S.T.®) was
demonstrated on contaminated sediment taken from
two locations in the Grand Calumet River (14). The
B.E.S.T.® process uses the solvent triethylamine to
separate organic compounds from sediment. Organic
compounds such as polychlorinated biphenyls (PCBs)
and PAHs are of particular concern at this site. More
than 98% of the total PCBs and PAHs were removed
from the Grand Calumet River sediments using the
B.E.S.T.® process.
Thermal Desorption at Ashtabula River, OH—The
same low temperature thermal desorption technology
that was used in the Buffalo River demonstration was
also used on about 15 cubic yards of sediment in the
Ashtabula River demonstration (15). This technology
was repeated at this site to test its capabilities for
treating contaminants such as PCBs and other chlori-
nated hydrocarbons not present in significant concentra-
tions at the Buffalo River AOC. The process removed
86% of the PCBs, up to 99% of the semivolatile com-
pounds and more than 92% of the chlorinated volatile
compounds. Mercury was the only heavy metal re-
moved by the process.
Bioremediation at Sheboygan River, Wl— Bioreme-
diation was demonstrated on contaminated sediment
from this location. This demonstration was performed in
conjunction with Superfund activities at the site. U.S.
EPA developed a plan with Tecumseh Products to ma-
nipulate the sediment in a confined treatment facility
(CTF) to enhance naturally occurring biodegradation.
Manipulation consisted of adding nutrients to sediments
already containing indigenous populations of microor-
ganisms, and cycling the CTF between aerobic and
anaerobic' conditions. Results of this demonstration were
determined to be inconclusive as it appeared that there
were no differences between treatments.
23
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Current Bench-Scale Demonstrations
Building upon information gained from the ARCS pro-
gram, current projects continue to expand the knowl-
edge base of technologies to remediate contaminated
sediments.
Buffalo River Dredging Demonstration—A demon-
stration of various dredging technologies was conducted
by the U.S. Army Corps of Engineers (ACE) in collabo-
ration with the U.S. EPA GLNPO. Mechanical and hy-
draulic dredging equipment were demonstrated for
precise removal of contaminated sediments in the Buf-
falo River, with monitoring to evaluate efficiency and
resuspension (16).
Trenton Channel Treatability Study-As a followup to
work conducted under the ARCS Program some new
work is currently taking place in conjunction with the
Michigan Department of Environmental Quality on the
Trenton Channel of the Detroit River AOC. The main
sediment contaminants in the Trenton Channel include
PCBs, PAHs and mercury. Up to 12 gallons of sediment
were shipped to five different vendors to conduct bench-
scale testing. The technologies being examined include:
solvent extraction, soil washing, solidification, plasma
vitrification, and thermal desorption followed by cement
production. The treatment technologies that were cho-
sen for the Trenton Channel Study were predominantly
based on being able to achieve a cleanup standard that
would allow reuse of the sediments once "cleaned."
Possible reuses include industrial/commercial/highway
fill and augmentation of cement production. It is antici-
pated that the results from these bench-scale tests will
aid in the selection for a full-scale remedial effort on the
Trenton Channel. The study also has implications for
sediment remediation outside of the Trenton Channel,
including the Detroit River and Southeast Michigan con-
taminated sediment sites.
Remediation
Over the last few years a number of sediment cleanups
have occurred in the Great Lakes basin. All of these
have been conducted in association with enforcement
actions, either under Superfund or other authorities.
Descriptions of a number of these cleanups are included
below.
Manistique River, Ml—The Manistique River is a tribu-
tary to Lake Michigan that is both an AOC and on the
National Priorities List (NPL) for Superfund. The con-
taminant of concern is PCBs, with concentrations rang-
ing upwards of 2,500 ppm. Approximately 18,000 pounds
of PCBs are found in the sediments, with estimates of
100 pounds per year being discharged into Lake Michi-
gan. Concentrations in carp (Cyprinus carpio) average
approximately 6 ppm of PCB.
In-sttu capping had been the preferred alternative of the
Potentially Responsible Parties (PRPs), but the U.S.
EPA Region 5 preferred that the contaminated sedi-
ments be removed (dredged). In 1995-6, Region 5 con-
ducted an emergency removal of approximately 18,000
cubic yardsof contaminated sediments from a portion of
the River and placed a temporary cap on another de-
posit to prevent its erosion. Dredging was conducted
using diver assisted techniques to reduce the amount of
resuspension. Prior to commencing of dredging activi-
ties in 1995, EPA designed, built or installed:
Sheet piling and silt barriers to prevent any re-
leases of resuspended sediments;
An on-site water treatment plant to dewater
dredged sediments and treat dredge water prior to
its discharge back into the Manistique River; and,
Two 1.2-million-gallon lagoons for storage of
treated dredge water.
The dredged material was processed with a series of
screens in order to separate the fine-grained and coarse
materials. Coarse materials, predominantly wood chips,
contained the bulk of PCBs, and were transported to a
Chemical Waste Landfill in Utah. The fine-grained sedi-
ments were sent to a local landfill for disposal, at a
significantly lower cost.
After much discussion over selection of what technology
to be used for the remediation of the remainder of the
contaminated sediments, a total dredging remedy was
selected and supported by the PRP and local commu-
nity. The PRPs agreed to pay $6.4 million for EPA to
finish dredging all the river and harbor sediments. Dredg-
ing of the rest of the sediments (approximately 100,000
cubic yards) is slated to be started in the Spring of 1997.
Sheboygan River, Wl—The Sheboygan River, Wl, is
an AOC and Superfund site, located on Lake Michigan.
PCB concentrations range upwards of 4,000 ppm and
as a result the entire AOC was included on the NPL in
May 1986. In 1989 and 1990 Tecumseh Products con-
ducted a voluntary pilot study to evaluate bioremediation
and sediment armoring of PCB-contaminated sediments.
To conduct the bioremediation studies, a 14,000 square-
foot confined treatment facility (CTF) was constructed
incorporating a double liner in each of four treatment
cells and a leak detection/leachate collection system.
The four treatment cells allowed for the testing of differ-
ent environments in which to study the effectiveness of
degrading PCBs by enhanced natural biodegradation.
The CTF has a capacity for approximately 1,500 cubic
yardsof sediments.
Sediment armoring (in-situ capping) was also conducted
in the upper reaches of the river. Approximately 15,000
square feet of sediments with PCB concentrations aver-
aging 100 ppm were armored in place. After placement
of silt curtains around the sediment area to be removed,
a geotextile material was first placed over the area. The
sediment area was then armored with roadbed material
consisting of fine to coarse-grained material. A second
layer of geotextile was then placed over the roadbed
24
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material and gabions placed around the edges to per-
manently hold the fabric in place. A layer of cobbles was
placed over the geotextile and a layer of roadbed mate-
rial was spread over the gabions.
Aside from the CTF and armoring work, an additional
2,500 cubic yards of material was removed and placed
into a storage tank on PRP property. The ultimate
disposal of this material, and remedial decisions regard-
ing the remainder of contaminated sediments in the river
is still being considered.
Waukegan Harbor, IL—Waukegan Harbor is an AOC
and NPL site, located on Lake Michigan, and was one of
the first sediment remediation projects completed on the
Great Lakes. In 1988, Outboard Marine Corporation, the
U.S. EPA and the State of Illinois signed a consent
decree specifying the final terms for the removal of over
300,000 pounds of PCBs from Waukegan Harbor. The
highest concentration of PCBs were found in Slip 3 with
levels up to 17,000 ppm.
The sediments that contained PCBs over 500 ppm were
dredged and thermally treated using the Taciuk process.
The Taciuk process is a thermal treatment system that
separates PCBs from soils and sediments by vaporizing
them at high temperatures. When the vapors cooled, the
PCBs were condensed into a liquid, removed, and de-
stroyed at an off-site facility. Over 12,700 tons of mate-
rial were treated by this process and 35,000 gallons of
PCBs were extracted and taken off-site for destruction.
The Taciuk process was operated and evaluated under
EPA's Superfund Innovative Technology Evaluation
(SITE) program, which assists EPA and industry in
determining promising and innovative Superfund tech-
nologies.
For the materials between 50 and 500 ppm PCBs, Slip 3
was made into a permanent containment cell by con-
structing a cutoff wall and a slurry wall. The 290-foot
cutoff wall consisted of two steel braces placed every 30
feet along the wall and keyed 12 feet deep into the clay.
A 3-foot wide,slurry wall was built around the entire
perimeter of Slip 3. Approximately 32,000 cubic yardsof
PCB-contaminated sediment was placed into this con-
tainment cell. This work was completed in the fall of
1993.
Black River, OH—The Black River is an AOC and
tributary to Lake Erie, near Lorain, OH. The primary
contaminant of concern is PAHs, which have been
associated with a number of fish tumors and abnormali-
ties in the river. The U.S. EPA Region 5 and USX-Kobe
Steel Company signed a consent decree in 1985 result-
ing from violations of the Clean Air Act, the Clean Water
Act and the Resource Conservation and Recovery Act
(RCRA). Under the terms of the agreement, USX-Kobe
agreed to remove contaminated sediments from a por-
tion of the Black River.
Between 1988-9, USX-Kobe removed approximately
40,000 cubic yardsof contaminated sediments from the
Black River using a mechanical dredge, fitted with a
closed-bucket clamshell and silt curtains. The sediments
were placed in dumpsters for transport by truck to a
disposal site constructed on USX-Kobe property.
Grand Calumet River/Indiana Harbor Canal, IN—The
Grand Calumet River and Indiana Harbor Canal are an
AOC located at the southern end of Lake Michigan, in
northwest Indiana. This waterway has one of the largest
concentrations of steel and petrochemical industry in the
Midwest, and the sediments are among the most con-
taminated of any on the Great Lakes, having elevated
levels of PCBs, PAHs, metals, and nutrients. The U.S.
EPA Region 5 and Indiana Department of Environmen-
tal Management (IDEM) have successfully pursued a
series of enforcement actions against industries and
municipalities in northwest Indiana for violations of vari-
ous federal and state environmental laws. A significant
amount of the compensation obtained through these
actions will be directed at contaminated sediment
remediation.
The first sediment remediation action completed in this
AOC was conducted by LTV Steel in a slip adjacent to
Indiana Harbor. Approximately 100,000 cubic yardsof
contaminated sediments were removed in 1994-5. Ini-
tially, dredging was conducted using diver-assisted suc-
tion lines because of concerns for sediment resuspension
and the proximity of the steel mill's main water intake to
the dredging location. A conventional cutterhead dredge
was later used to overcome the slow pace associated
with diver assisted dredging.
Sediments were dewatered on site utilizing filter presses
and surplus wastewater treatment capability of the steel
mill. The dewatered sediments were trucked to a dis-
posal facility off site.
St. Lawrence River, NY—The Massena-GM Superfund
project removed approximately 14,000 cubic yards of
PCB-contaminated sediments from the harbor in 1996.
Because of the amount of cobbles and stone present in
the sediments, dredging was conducted using a modi-
fied backhoe which allowed for separation of the stone
from fine-grained sediments during excavation. The
dredging area was surrounded by a sheet pile wall to
prevent off-site migration of sediments during dredging.
The cobbles were washed and considered free of con-
taminants. The fine-grained materials were transported
to a disposal facility off site.
Dredging, even to a greater than planned depth, proved
unable to create a bottom surface with PCB levels below
the negotiated target (10 ppm). Consequently, the exca-
vated area was subsequently covered with a composite
cap of 6 inches of carbon/sand filler and armored with 12
inches of gravel and stone.
Some of the sediment cleanups that have been con-
ducted in the Great Lakes over the past 10 years have
been presented in this paper. Numerous others are
planned or under design. It is hoped that by continuing
25
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to remediate the contaminated sediments, many of the
beneficial uses in the Great Lakes, identified by the
GLWQA, will be restored.
For further information on sediment activities being un-
dertaken by the U.S. EPA GLNPO please visit the
following Internet site: http://www.epa.gov/glnpo/.
Acknowledgments
The authors would like to thank the following people for
assisting with the completion of this paper: John Filkins,
U.S. EPA, ORD-LLRS, Grosse lie, Ml; Brian Stage, U.S.
EPA, GLNPO, Chicago, IL; and Art Ostaszewski, Michi-
gan Department of Environmental Quality, Lansing, Ml.
References
1. Hartig, J.H., and Thomas, R.L 1988. Develop-
ment of Plans to Restore Degraded Areas in the
Great Lakes. Environmental Management Vol.12,
Number 3, pp 327-347.
2. United States and Canada. 1987. The Great Lakes
Water Quality Agreement as revised by Protocol
on November 1,1987. Windsor, Ontario, Canada.
3. Hartig, J.H., and Zarull, M.A., eds. 1992. Under
RAPs: Toward Grassroots Ecological Democracy
In the Great Lakes Basin. University of Michigan
Press. Ann Arbor, Ml.
4. U.S. EPA. 1988. U.S. Progress in Implementing
the Great Lakes Water Quality Agreement, Annex
Reports to the IJC. EPA 905/9-89/006. Chicago,
IL
5. U.S. EPA. 1994. ARCS Program Final Summary
Report. EPA 905-S-94-001. Chicago, IL.
6. U.S. EPA. 1994. ARCS Assessment Guidance
Document. EPA 905-B94-002. Chicago, IL.
7. Chapman, P.M. 1986. Sediment Quality Criteria
from the Sediment Quality Triad—An Example.
Environ. Toxicol. Chem 5: 957-964.
8. McGee, R.G., Ballard, R.F., Jr., and Caulfield,
D.D. 1995. A Technique to Assess the Character-
istics of Bottom and Subbottom Marine Sediments.
Technical Report DRP-95-3. U.S. Army Engineer
Waterways Experiment Station. Vicksburg, MS.
9. Lick, W., Yao-Jun, X., and McNeil, J. 1995.
Resuspension properties of sediments from the
Fox, Saginaw, and Buffalo Rivers. Journal of Great
Lakes Research. 21(2):257-274.
10. Cardenas, M., and Lick, W. 1996. Modeling the
transport of sediments and hydrophobic contami-
nants in the lower Saginaw River. Journal of Great
Lakes Research. 22(3):669-682.
11. U.S. EPA. 1994. ARCS Program Remediation
Guidance Document. EPA 905-B94-003. Chicago,
IL
12. U. S. EPA. 1993. ARCS Program Pilot Scale
Demonstration of Thermal Desorption for the Treat-
ment of Buffalo River Sediments. EPA 905-R93-
005. Chicago, IL.
13. U.S. EPA. 1994. ARCS Program Pilot Scale Dem-
onstration of Sediment Washing for the Treatment
of Saginaw River Sediments. EPA 905-R94-019.
Chicago, IL.
14. U.S. EPA. 1994. ARCS Program Pilot Scale Dem-
onstration of Solvent Extraction for the Treatment
of Grand Calumet River Sediments. EPA 905-
R94-003. Chicago, IL.
15. U.S. EPA. 1994. ARCS Program Pilot Scale Dem-
onstration of Thermal Desorption for the Treat-
ment of Ashtabula River Sediments. EPA 905-
R94-021.ChlL
16. Averett, D.E., B.D. Perry, E.J. Torrey, and J.A.
Miller. "1990 Review of containment and treat-
ment technologies for remediation of contami-
nated sediment in the Great Lakes." Miscella-
neous Paper EL-90-25. U.S. Army Engineer Wa-
terways Experiment Station, Vicksburg, MS.
26
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Perspective on Remediation and Natural
Recovery of Contaminated Sediments
Dolloff F. Bishop
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH
Sediments include material, particularly clays and or-
ganic matter, that control sediment cohesiveness. Co-
hesive sediments have large surface area-to-volume
ratios, a net negative charge on their surface and ex-
changeable cations (1). Thus cohesive sediments ad-
sorb both organic and inorganic contaminants strongly.
Indeed the bulk of the contaminant load in watersheds is
usually adsorbed to cohesive sediments that act as a
transporting system for contaminants (2, 3). The con-
taminants in sediments, therefore, include a wide variety
of organic compounds and metals adsorbed to the cohe-
sive material (4).
Metals in sediments cannot be destroyed but can be
transformed by bioprocesses often to less available
forms. The important organic contaminants belong to
the high molecular weight organic classes, especially
polychlorinated biphenyls (PCBs), highly chlorinated pes-
ticides, dioxin/dibenzofurans and polynuclear aromatic
hydrocarbons (PAHs) from widely used multicomponent
aroclors, pesticides, and creosotes. These organics par-
tition strongly to and persist in sediments (4, 5, 6). In
addition, less widely used chlorinated organics such as
hexachlorobenzene and trichlorobenzenes pan be im-
portant contaminants at specific sites (4, 7).
Attenuation Chemistry and Biology
Attenuation mechanisms of the contaminants in sedi-
ments include biodegradatlon, biotransformation, biotur-
bation (mixing by sediment organisms), dispersion,
dilution, adsorption, volatilization, chemical stabilization
or destruction and burial by clean sediment. With or-
ganic contaminants in sediments often highly hydropho-
bic which can significantly increase the volatility of high
molecular weight organics in wet environments, volatil-
ization as well as biodegradation can provide substantial
sediment contaminant removal (8, 9). The attenuation
mechanisms at sites are significantly affected by highly
variable flow in watersheds and by removal through
bioaccumulation in the food chain which also produces
potential human health and environmental risks (4, 6).
Quiescent sediments with substantial organic contami-
nation are anaerobic except in the upper layer (a few
cm) adjacent to the water column (10). Dissolved oxy-
gen levels of approximately 8.0 mg/L in water, slow
oxygen diffusion into sediments, and slow diffusion of
contaminants, especially in sediments with extended
contaminant contact time (aging), to bioactive sites limit
the rates of aerobic degradation or transformation pro-
cesses (11). Indeed, mass transport limitations in quies-
cent sediments reduce bioavailability of metals and
organic contaminants, but also increase persistence of
the aerobically degradable organic contaminants.
Turbulent mixing with high flows or strong tides trans-
ports and disperses highly contaminated sediments over
wide areas (4, 12). The mixing and dispersion blend
contaminated and clean sediment which may subject
the persistent contaminants in the sediment to acceler-
ate bioaccumulation. The mixing of sediments into the
water column usually produces only limited and slow
aerobic oxidation or transformation of aerobically de-
gradable or transformable contaminants because the
sediment transport, sorption and bioaccumulation pro-
cesses are usually substantially faster than the aerobic
degradation or transformation processes (13). Finally,
with dispersion and dilution by clean sediments, biodeg-
radation and/or transformation of the sediment contami-
nants may be limited because of low concentrations of
contaminant and insufficient biodiversity in the microbial
community.
Concentrations of trace metals in sediments are not
good measures of metal toxicity in watersheds because
field and laboratory studies have revealed that different
sediments exhibit different degrees of toxicity for the
same total quantities of metals (14, 15). Since most
contaminated sediments have low redox potentials, metal
27
-------
reduction processes and precipitation reactions with
suifides sequester many metals in sediments, usually as
insoluble suifides (4,16). The sequestering reduces the
environmental availability and toxic impact of metals to
beothte organisms, watershed fish, animals and humans
(17-19).
As an empirical characteristic of sediments, acid volatile
sulfide (AVS) is the sulfide liberated when a sediment is
treated with hydrochloric acid at room temperature un-
der anoxic conditions (19). Ferrous sulfide is the major
component of AVS in anoxic sediments (16). The AVS
controls the activity and availability of trace divalent
metals in the pore water of anoxic sediments (16 -19).
Metals that are extracted by the hydrochloric acid treat-
ment are called simultaneously extracted metals (SEMs).
Important SEMs have sulfide solubility products that are
smaller than the solubility product of ferrous sulfide and
include nickel, zinc, cadmium, lead, copper, and mer-
cury (16 - 19). As a result these important SEMs have
tow divalent metal ion concentrations in pore water of
sediments with high ferrous sulfide content.
Based upon research on freshwater and marine sedi-
ments at EPA's Narragansett Environmental Research
Laboratory, EPA's Office of Science and Technology
has selected a difference in mol concentrations of (SEMs)
- (AVS)>5 as an empirical condition which establishes
high probabilities for most metal toxicity and availability
In sediments (4). Since mercury sulfide is easily trans-
formed to methyl mercury, mercury is not included in the
(SEMs) - (AVS) empirical characterization to determine
its probability of metal toxicity or availability (4, 20).
Volatilization of hydrophobia contaminants with appro-
priate Henry Constants in sediments can occur signifi-
cantly in tidal and riverbank sediments exposed to
fluctuations in water levels. The exposure of sediments
to the atmosphere permits direct contaminant losses
from the wet sediment through volatilization (8, 9) or by
wind transport of dried sediment fines. Volatilization
from the surface of water is controlled by diffusion and
bioturbation of contaminants in the sediment and pore
water, by diffusion and dispersion of contaminants and
sediments through the water column, and by wind dy-
namics at the water surface. Currently, uncertainty ex-
ists concerning the relative importance of the volatilization
routes and the other attenuation mechanisms for reduc-
tion of contaminant concentrations and ecological and
health risk from contaminated sediment.
Intrinsic degradation of high molecular weight organic
compounds occurs naturally but slowly in soils and
sediments and is usually catalyzed by indigenous anaero-
bic and aerobic microorganisms (21 - 26). In general,
the greater the molecular weight of the organic contami-
nants the greater the partitioning to sorption sites. Large
resident times of contaminants in the sediment (aging)
usually results in increased sequestration. Both effects
reduce the availability of the organic compounds to
microorganisms and thus reduce the extent and rates of
biodegradation.
The PAHs biodegrade most readily through aerobic
processes and the degradation rates usually decrease
as the number of aromatic rings increases (24 - 26).
Biodegradation of most PAHs does not occur apprecia-
bly under anaerobic conditions. Thus, the PAHs persist
in anoxic or anaerobic sediments (4, 6).
In contrast, highly chlorinated congeners of PCBs and
other chlorinated contaminants may gradually dechlori-
nate naturally in contaminated anaerobic sediments (27
- 29); the PCBs to congeners with the residual chlorines
at the ortho position on the biphenyl molecule (27, 28).
Lightly chlorinated PCBs and other partially dechlori-
nated organic species, in general, bioaccumulate less
than the highly chlorinated congeners or species. The
lightly chlorinated PCBs exhibit significantly less poten-
tial human carcinogenic and dioxin-like (coplanar struc-
ture) toxicity (28,30) but may be transformed in humans
with potential for other human toxicity (31). While aero-
bic processes may then biodegrade the lightly chlori-
nated PCB congeners and other lightly chlorinated
organics (32, 33), the anaerobic or anoxic conditions in
many sediments limit significant degradation and these
partially dechlorinated organics may accumulate and
persist (4, 33).
Chlorinated pesticides and other chlorinated organics
may also be transformed or partially degraded in sedi-
ments. Unfortunately the degradation products-may be
equally or more toxic and persistent than the original
pesticide or chlorinated organic. As an example, dichloro-
diphenyl-trichloroethane (DDT) can be transformed un-
der anaerobic conditions to dichloro-diphenyl-
dichloroethane (DDD) and under aerobic conditions to
dichloro-diphenyl-dichloroethylene (DDE) (34, 35). Al-
though all three DDT constituents may be found in
sediments, DDE is the constituent most widely detected
in the environment (7, 36) and the constituent that is
resistant to further biotransformation (37).
Bioaccumulation
Persistent organic compounds and some metals, princi-
pally mercury, bioaccumulate in watersheds with signifi-
cant biomagnification in fish (4). The persistent organic
contaminants generally partition strongly to organic
phases and thus rapidly bioaccumulate. Unfortunately,
some metals are also biologically transformed to more
toxic or biologically available forms. As examples, mer-
cury, lead, selenium and arsenic can be biologically
methylated. Methylation increases their mobility and, for
mercury, its bioconcentration potential (38). Arsenic sui-
fides can also be biologically oxidized, if sediments are
oxygenated, to water soluble arsenate, a more readily
available form of arsenic (39, 40). In addition, metals
may also bioaccumulate directly via uptake by benthic
organisms in the sediments (38).
9
Bioaccumulation with substantial biomagnification in fish
increases the ecological and health risk associated with
large volumes of low (ppb) to moderately contaminated
sediments and thus ultimately threatens fish-consuming
28
-------
predators and humans (7). Institutional controls such as
fish consumption advisories have not been completely
successful, especially with people who use fishing to
supplement their diets (41, 42).
Finally, while low concentrations of contaminants and
site conditions may not induce microbial activity, these
low concentrations can still bioaccumulate (4). Indeed,
high concentrations of contaminants in limited volumes
of sediments, but representing relative low mass load-
ings to a contaminated watershed, may provide less
bioaccumulative impact on migratory fish than large
volumes of low-to-moderately contaminated sediment
which are dispersed over a wide area. Non-migratory
fish and shellfish in highly contaminated areas obviously
will exhibit higher bioaccumulation of contaminants in
their tissues than those in areas with lower levels of
contamination.
Site Characterization
Site characteristics impacting natural attenuation/recov-
ery in sediments include hydraulic flow rates and their
potential chaotic variability; tidal effects; types, depths
and redox conditions of contaminated sediment; distri-
bution, concentrations and types of contaminants; con-
centrations of total organic carbon in sediments; shoreline
and water uses and conditions; and navigational re-
quirements. The effects of these site characteristics on
the fate and transport of contaminants are not fully
understood, especially for estuarine and marine sedi-
ments. Indeed, the rates of natural degradation or trans-
formation of contaminants under various site conditions
are not generally available.
Hydraulic transport of uncontaminated sediments in wa-
tersheds can lead to natural covering of contaminated
sediments. Such covering can reduce the availability of
the contaminants and thus bioaccumulation. As an ex-
ample, the kepone contaminated sediments in the James
River, VA, were covered by uncontaminated sediment
(43). The process of covering or burial by uncontami-
nated sediment, a component of natural attenuation/
recovery, led to a significant reduction in the ecological
and health risks associated with fish and shellfish in the
James River (44). Unfortunately, such natural recovery
depends upon the uncertain natural maintenance of the
uncontaminated sediment cap.
Indeed, the contaminated sediments in rivers and streams
and erodible soils at Superfund sites are large reservoirs
of contaminants. Severe storms and precipitation events
such as occurred in the Fox River in Wisconsin (13) can
easily erode soil, scour sediments and redistribute the
contaminants over wide areas.
The various types of contaminants may be poorly at-
tenuated or require conflicting conditions to support
effective natural attenuation/recovery. As examples, di-
valent metals in general need anaerobic conditions with
sufficient sulfides (AVS) to minimize metals released to
the water column and eventual bioaccumulation. How-
ever, biomethylation of mercury, increasing mobility and
bioaccumulation potential of mercury, is produced under
both anaerobic and aerobic conditions (20). PCB dechlo-
rination requires anaerobic conditions and sufficient or-
ganic carbon, probably generating appropriate amounts
of molecular hydrogen, to efficiently dechlorinate the
dioxin-like meta and para chlorine on the biphenyl mol-
ecule. Anaerobic conditions, unfortunately, prevent prac-
tical aerobic degradation of the resulting lightly chlorinated
PCBs and other aerobically degradable organics such
asPAHs. Thus, poor attenuation of some contaminants
and conflicting site conditions necessary to efficiently
attenuate other contaminants coupled with relatively
rapid bioaccumulation and biomagnification effects, even
at low contaminant concentrations, significantly mini-
mize the effectiveness of natural attenuation.
Monitoring
Long-term monitoring of contaminants in sediments, the
water column and in fish or shellfish has revealed de-
creasing concentrations of both metals and persistent
organic contaminants (7). With the attenuation mecha-
nisms at s.ites removing contaminants, with the banning
of many persistent compounds and the improved re-
moval from industrial and municipal point sources, con-
taminant concentrations would be expected to continue
to decrease.
In surveys on PCBs in migratory fish tissue (Figures 1
and 2) in the Great Lakes, the fish in Southern Lake
Michigan revealed an initial substantial decrease in tis-
sue PCB concentrations with time. However, recently a
leveling of the PCB concentration in the tissue has been
observed (45). In an ongoing survey of mussels and
oysters conducted by the National Oceanic and Atmo-
sphere Administration at 100 U.S. coastal sites, the
concentration of 14 monitored contaminants revealed
some decreases (217 test areas) and some increases
(41 test areas) with time in the contaminant levels in the
shellfish (46). The main finding, however, was that in the
majority of cases (1898 test areas) there was no statisti-
cal change in tissue contaminant concentration.
Indeed, while natural attenuation or recovery may occur,
these recent findings suggest that quasi-steady-state
contaminant concentrations in fish and shellfish appear
to be very widespread. Finally, this recently observed
leveling of contaminant concentrations in fish tissues
and shellfish is likely caused by continuing sediment
transport at high flow conditions in streams and estuar-
ies and subsequent sediment dispersion over large ar-
eas of the watershed. •
Modeling and Risk Assessment
A key factor controlling the fate and migration of persis-
tent contaminants in watersheds is the resuspension
(sediment erosion), transport and dispersion of cohesive
and non-cohesive sediments over wide areas of water-
sheds. The non-cohesive sediments such as sand do
29
-------
A 95% confidence limit
Mean concentration
71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91
Figure 1. Lake Michigan lake trout (45). Year
,0)
DO
O
CL
F
2.5
2.0
1.5
1.0
0.5
. 95% confidence limit
+ Mean concentration
_L
J_
_L
_L
_L
1980 1981 1982 1983 1984 1986 1987 1988 1989 1990 1991
Figure 2. Coho salmon fillets (45). Year
not strongly adsorb contaminants, but do dilute and bury
the contaminated cohesive sediments. A series of mod-
els have been developed by the U.S. Environmental
Protection Agency and the Corp of Engineers to charac-
terize the resuspension of sediments in rivers and
streams, estuaries and coastal areas and other large
bodies of water (1, 12, 47 - 53). These models have
been applied and calibrated at various sites (13, 54 -
58). Some of the models, especially for estuaries and
marine coastal areas, are complex numerical modeling
methods and may require modification to specifically
address sediment resuspension, transport and disper-
sion in the watershed. The state-of-the-art for modeling,
however, is reasonably developed to permit assess-
ments using field data.
A second factor affecting contaminant transport in wa-
tersheds involves water erosion of contaminated soil.
Three types of water erosion are usually recognized;
sheet, rill and gully (59). A suitable model for estimating
soil erosion is the Modified Universal Soil Loss Equation
(MUSLE) (60).
Methods for assessing ecological and health risk associ-
ated with contaminated sediments are described in ap-
pendices B through I of the National Sediment Quality
Survey (4). The methods described in these appendices
with appropriate supporting references include sediment
screening parameters; EPA's draft sediment quality cri-
teria (SQC) and sediment quality advisory levels (SQALs)
for nonionic organic chemicals; EPA's empirical toxicity
30
-------
assessment approach for divalent metals using SEM
and AVS concentrations; methods for selecting biota-
sediment accumulation factors and percent lipid in fish
tissue used to derive theoretical bioaccumulation poten-
tials; screening values of chemicals and frequency of
detection values with estimates of the probability effect
levels; watershed species characteristics related to tis-
sue bioaccumulation; methodology for evaluating toxic-
ity levels; and additional analyses providing perspective
on the important contaminants, RGBs and mercury (Fig-
ures 3 and 4; Tables 1 and 2).
Detailed EPA methods are also available for assessing
toxicity and bioaccumulation of contaminants associ-
ated with sediments for freshwater (61) and marine
waters (62).
Practical Remediation Approaches
Practical remedial approaches for contaminated sedi-
ments include removal by dredging with offsite contain-
ment or treatment, in-situcontainment (capping), natural
attenuation/natural recovery with long-term monitoring,
1.00
0.90
1.00E-01
1.00E+00
I
1.00E+01 1.00E+02
PCB in fish tissue concentration (ppb)
1.00E+03
1.00E+04
Figure 3. Cumulative frequency distribution of PCB fish tissue data (4).
Table 1. Fish Tissue Sampling Stations with Detectable Levels of PCBs that Exceed Various Screening Values (4)
Protection of consumers
Cancer risk level-
Noncancer hazard quotient of 1
FDA tolerance level
Wildlife criteria
Associated level
(ppb)
10-6 1.4
10-5 14
10-4 140
220
2000
160
Level letter in
PCB
A
B
C
• . E
F '
D
Number of stations
exceeding level
2,354
2,256 '
1,686
1,473
489
1,620
Percentage of
stations ••
99.3
95.2
'71.1 ,
62.2
20.6
• 68.4
31
-------
1.00E-01
I
1.00E+00
I I
1.00E+01 1.00E+02
Concentration (ppb)
I
1.00E+03
T
1.00E+04
Figure 4. Cumulative frequency distribution of mercury fish tissue data (4).
Tabl« 2. Fish Tissue Sampling Stations with Detectable Levels of Mercury that Exceed Various Screening Values (4)
Protection of consumers
Associated level
(ppb)
Level letter in
mercury figures
Number of stations
exceeding level
Percentage of
stations
Canadian guideline
Noncancar hazard quotient of 1
(1995}
Noncancer hazard quotient of 1
(pfe-1995)
Noncancer hazard quotient of 1
Cpre-1995 for infants)
FDA action (avel
Wildlife criteria
200
1,100
3,231
646
1000
57.3
B
E
F
C
D
A
908
91
15
204
103
2,150
35.1
3.5
0.6
7.9
4.0
83.0
and no action with long-term monitoring and institutional
controls. A review of remediation technologies and costs
are provided in EPA's Assessment and Remediation of
Contaminated Sediments (ARCS) Program: Remediation
Guidance Document (11). Selection of remedial ap-
proaches should involve a site specific risk based cost/
benefit assessment of the various approaches. Proce-
dures are available or can be developed to evaluate
cost/benefits for dredging with offsite containment or
treatment of the dredged sediment and for natural at-
tenuation/natural recovery. Dredging costs, including
the cost for improved environmental dredging technol-
ogy, and the costs of site characterization and monitor-
Ing for natural attenuation/natural recovery can be readily
determined. The effectiveness of in-situ containment
(capping) and no-action with monitoring and institutional
controls are uncertain, although costing of the approaches
on a site specific basis can be estimated.
Natural Attenuation/Recovery
Uncertainties
In summary, a number of factors contribute to uncer-
tainty in and limit the utility of natural attenuation/recov-
ery as a means of remediation of contaminated
sediments. These factors include:
32
-------
Anaerobic conditions in sediments that limit aero-
bic biodegradation of PAHs, partially dechlori-
nated RGBs and other aerobically degradable con-
taminants.
Mobilization of metals by microbiai activity such as
methylation of mercury.
Undefined and wide variability in site specific rates
of attenuation of persistent organic contaminants,
especially when low contaminant concentrations
and limited biodiversity restrict microbial activity.
Uncontrolled dispersion of reservoirs of contami-
nated sediments and erodible soils caused by
high and chaotic hydraulic flow rates or tidal ef-
fects. This lack of control leads to uncertainty in
burial of contaminated sediment and eroded soils
by clean sediment.
Air emissions of hydrophobic contaminants with
, uncertain impact on ecological and health risks.
Bioaccumulation and biomagnification of contami-
nants even from low [ppb) but widely dispersed
concentrations in sediments.
With aging of sediments, continued contaminant
availability to bioaccumulation and biomagnifica-
tion but reduced availability of persistent organics
to biodegradation.
Widespread quasi-steady-state contaminant re-
siduals in fish and shellfish.
Ineffective institutional controls to prevent human
consumption of contaminated fish and shellfish.
Uncbntrollable consumption of contaminated fish
and shellfish by watershed predators.
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36
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Natural Recovery of Contaminated Sediments-
Examples from Puget Sound
Todd M. Thornburg and Steve Garbaciak
Hart Crowser, Inc.
Introduction
With the development of Sediment Quality Objectives
(SQOs) for the Commencement Bay Superfund Site in
Tacoma [1] and the promulgation of the Washington
State Sediment Management Standards (SMS [2]), state
and federal regulatory agencies have been actively pur-
suing the investigation and cleanup of contaminated
sediment sites in Puget Sound. This paper presents
case studies on the application of natural recovery at
three such contaminated sediment sites, and a survey of
technical approaches which are available for evaluating
the speed and effectiveness of the recovery process
and predicting future risk at a site.
Natural recovery is a fundamental component of state
and federal regulatory programs, and of EPA's Contami-
nated Sediment Management Strategy [3]. These pro-
grams emphasize that the aggressiveness of a cleanup
remedy should be commensurate with the level of risk
posed by contaminated sediments to human health and
the ecological community, to ensure the most efficient
use of our limited resources. Higher risk areas may
require more aggressive removal or containment ac-
tions (i.e., dredging or thick capping), whereas areas
which pose a lower risk may be suitable for natural
recovery.
EPA [3] states that active remediation may not be re-
quired "if a combination of pollution prevention and
source controls will allow the sediments to recover natu-
rally in an acceptable period of time." Natural recovery
encompasses the cumulative physical, chemical, and
biological processes which result in a reduction in con-
taminant concentrations and the risks posed by con-
taminated sediments over time. Natural recovery is
contingent on source control to prevent ongoing recon-
tamination of sediments. Source control efforts should
consider pollutant inputs to a water body (i.e., control of
outfall discharges, bank/soil erosion, groundwater seep-
age, etc.) as well as containment of in-water hot spots
which could disperse contaminants into surrounding
areas if left unremediated.
The advantages of natural recovery include (1) existing
benthic habitat is not disturbed; (2) buried contaminants
are not remobilized during remedial construction activi-
ties; and (3) low cost. The disadvantages include (1)
residual contamination is left in place and must be
monitored; (2) the alternative ,may not be viable in
navigational areas which require maintenance dredging;
(3) the public may perceive natural recovery as a "do
nothing" alternative, and may require education regard-
ing the advantages of this approach for optimizing our
limited resources as we strive to minimize site risk. To
properly evaluate the feasibility of natural recovery, regu-
latory guidance must be provided regarding the time
period over which recovery can take place, the depth of
compliance for sediment concentrations, the level of risk
that can be tolerated during the recovery period, and the
monitoring requirements during recovery.
Natural Recovery Processes and Data
Needs
Given an appropriate level of source control, natural
recovery of contaminated sediments can occur through
a variety of physical, chemical, and biological processes,
including those depicted on Figure 1. Physical pro-
cesses include sediment transport and redistribution
processes involving currents (advection), tides (disper-
sion), sedimentation and resuspensipn—processes which
can bury or dilute existing contaminants with inputs of
clean sediment. Chemical processes include diffusion
from sediments to the overlying water column, and
volatilization to the atmosphere—processes which allow
contaminants to diffuse from sediments into more fluid
media where they are rapidly dispersed. Biological pro-
cesses include biodegradation, which can metabolize
organic contaminants to carbon dioxide resulting in a
permanent loss of risk, and bioturbation. Bioturbation
refers to the overturning and mixing of surface sedi-
ments (usually the upper 5 to 20 centimeters) by benthic
organisms, a process which can mitigate the impacts of
short-lived pollutant loads, such as storm events, upsets
in wastewater discharges, or other slug loads.
37
-------
Water
Column
Surface
Sediment
Subsurface
Sediment
i Volatilization
Advection
••
Dispersion
Diffusion
Sedimentation
Resuspension
f ~^0 itoturbatiort
%& ** "* ^^^
•MNMMM ^
Figure 1. Summary of physical, chemical, and biological processes which contribute to the natural recovery of sediments, provided
source controls are in place.
Several types of site-specific data are needed to make a
technically defensible demonstration that natural recov-
ery is a viable remedial alternative. A detailed map of
contaminant distributions in surface sediments is needed
to define Initial conditions, and to outline in a preliminary
manner those areas which may be suitable for natural
recovery versus those which may require a more active
remedy. Current and tidal dynamics in an estuary (ad-
vection and dispersion terms) may be obtained from
current meter deployments, dye-tracing studies, or by
analysis of salinity distributions. Sediment transport pa-
rameters (sedimentation and resuspension rates) are
typically developed using sediment trap deployments
and age-dated sediment cores. Sediment cores may be
dated by radioisotopic methods (cesium-137 and
lead-210 being the most common), or by the identifica-
Bellingham
Whatcom Waterway
Everett
Ifseattle
/ fe'r*
/'Manchester?
/f Annex
Thea Foss Waterway
Tacoma
Olympia
Washington
State
N
Figure 2, Location map of Puget Sound case studies. Whatcom Waterway is a state-lead (Dept. of Ecology) RI/FS; Manchester
Annex Is a federal-lead (Corps of Engineers) RI/FS; Thea Foss Waterway Is a federal-lead (EPA) remedial design.
38
-------
tion of stratigraphic markers, such as the depth to a
geologic contact which corresponds to a datable dredg-
ing event. Finally, a quantitative assessment of current
source loads to the water body, and potential pollutant
reductions which may be realized by implementing addi-
tional source controls in upland drainages, is a critical
component of the evaluation.,
Case Studies in Puget Sound
Case studies are presented for three contaminated sedi-
ment sites in Puget Sound where natural recovery is or
will be a key component of the cleanup strategy. The
sites include the Whatcom Waterway in Bellingham, the
Manchester Annex near Bremerton, and the Thea Foss
Waterway in Tacoma (Figure 2).
The sites provide examples of the application of natural
recovery analysis to sediments containing a variety of
chemicals of concern (mercury, RGBs, and PAHs). In
addition, the sites provide examples of three different
technical approaches to natural recovery analysis, in-
cluding (1) empirical trend analysis, (2) one-dimensional
sedirnentation/bioturbation modeling [4], and (3)
two-dimensional contaminant transport modeling [5].
Whatcom Waterway Site
The Whatcom Waterway site occupies the primary fed-
eral navigation channel on the Bellingham waterfront.
The site is undergoing a RI/FS under the lead of the
Washington State Department of Ecology. The primary
contaminant of concern in sediments is mercury, de-
rived from historical discharges from a chlor/alkali plant
at a pulp and paper mill on the waterway. Untreated
chlor/alkali wastewater was discharged from 1965 to
1970, at which time aggressive source control measures
were implemented and the discharge was practically
ceased. Present-day sediment contamination is the re-
sult of residual mercury accumulations in the Whatcom
Waterway which have also dispersed into the inner parts
of Bellingham Bay. Natural recovery is not proposed for
the waterway itself, because much of the channel is
already above navigation depth; however, natural recov-
ery is a viable alternative for lower-risk mercury concen-
trations in the sediments of the inner bay.
Mercury Concentration in mg/kg
1-2 3 4
o
I
"
o
O
Peak depth at 52 cm
Chlor/alkali plant discharge
1965 to 1970
B
-100
-120
Figure 3.
1.4
1.2
c
o
1
0.8
c
o
O
I 0.6
0.4
0.2
1970 1975 1980 1985 1990 1995 2000 2005
Year
Empirical projection of sediment concentrations following source control, Whatcom Waterway, Bellingham. (A) High-resolution
core profile of subsurface mercury concentrations; mercury peak of 4.5 mg/kg at 52 cm depth corresponds to chlor/alkali plant
discharges from 1965 to 1970. (B) Trend analysis of upper 45 cm of core (period following source control). Depth axis is
converted to time using a sedimentation rate of 1.6 cm/yr. Data are fit with an exponential decay curve to allow predictions of
future recovery rates.
39
-------
A high-resolution mercury profile in a sediment core
from the inner bay is shown on Figure 3A. The subsur-
face mercury peak of 4.5 mg/kg, between about 45 and
55 cm depth, corresponds to the peak historical dis-
charges between 1965 and 1970. Following source
control, mercury concentrations were abruptly reduced,
to about 1 mg/kg, and concentrations have continued to
decrease through time to less than 0.5 mg/kg at the
present sediment surface.
The depth profile of mercury in the sediment core was
translated Into a time series, shown on Figure 3B, using
a sedimentation rate of 1.6 cm/yr which was indepen-
dently estimated using radioisotopic dating methods. A
least-squares regression line was fit to the post-1970
data (the period following source control) using an expo-
nential decay model. The regression line indicates that
mercury concentrations undergo a 50% reduction every
thirteen years; this decay rate can be extrapolated to
estimate future mercury concentrations in the inner bay.
The advantage of this type of trend analysis lies in its
simplicity. The disadvantages include its limited applica-
bility, which is largely restricted to historical discharges
which were shut down at some point in the past. In
addition, the extrapolation may be invalidated if the
dynamics of the site are changed. For example, if re-
moval actions are implemented in the navigation chan-
nel such that the channel no longer contributes
suspended sediments with elevated mercury concentra-
tions to the inner bay, natural recovery will be acceler-
ated.
Manchester Annex Site
The Manchester Annex site is a historical Navy fuel
depot where a coastal lagoon was infilled with solid
waste between 1946 and 1962, forming a coastal landfill
which extends onto the upper tideflat of Clam Bay.
Some of the landfill debris contained waste oil contami-
nated with PCBs, and PCBs have since dispersed into
the tideflat sediments and the clams that live in those
sediments. The landfill continues to provide an ongoing
source of PCBs to the tideflat, largely through mechani-
cal erosion of the toe of the landfill. However, the
preferred remedial alternative at this site includes exca-
vation of the intertidal portion of the landfill, and hydrau-
lic and structural controls for the upland portion of the
landfill, which should eliminate future inputs of PCBs to
the tideflat sediments. The risk associated with this site
B
PCB Concentration in ug/kg
50 100
150
10
15
20
Modeled Profile
PCB Concentration in ug/kg
50 100
150
10
Q.
0)
Q
15
20
Model
Prediction
(2005)
Core Profile
(1995)
Figure 4. Application of 1-D sedimentatton/bioturbation model (Officer and Lynch, 1989) to natural recovery predictions, Manchester
Annex Site near Bremerton. (A) Model verification step—core profile is simulated using a peak "discharge" period from 1946 to
1962 resulting from PCB disposal in a coastal landfill. (B) Ten-year model prediction shows relatively rapid recovery in upper 5
cm of sediment in response to burial and resuspension of serface sediments, following Isolation of source inputs from the
tandfiif.
40
-------
is primarily a human health concern from ingestion of
PCB-contaminated shellfish.
The PCB profile in a sediment core from the upper
tideflat, just beyond the edge of the landfill, is shown on
Figure 4A. The solid line depicts the actual analytical
results from this core, and the dashed line is the PCB
profile which was simulated using a one-dimensional
sedimentation/ bioturbation model developed by Officer
and Lynch [4]. The PCB profile was simulated by sup-
plying a history of PCB source inputs, and specifying
sedimentation and resuspension rates, a bioturbation
coefficient (a dispersion term), and a bioturbation depth,
below which dispersion of contaminants ceases. The
modeled profile agrees well with the actual data.
A subsurface peak concentration of 150 fig/kg, between
about 10 and 15 cm depth, corresponds to the period of
active infilling of the lagoon; PCBs were also mixed to
greater depths and into native sediments by bioturba-
tion. PCB concentrations remain elevated to the
present-day sediment surface, as a result of continued
inputs from coastal erosion of the landfill.
The modeled PCB sediment profile was run forward in
time for ten years, assuming that remediation of the
landfill would reduce future PCB inputs by at least 90%;
the predicted profile ten years after remediation is shown
on Figure 4B. The model predicts that PCB concentra-
tions in the upper 5 cm' of the core will recover rapidly
following the curtailment of source inputs. The pro-
cesses responsible for the PCB reductions include burial
of contaminated sediments with new clean sediments,
and mixing.of clean sediments into the upper sediment
column through bioturbation. The PCB concentrations
in clam tissue are also expected to recover rapidly,
because these filter-feeding organisms are primarily
exposed to PCBs in the upper few centimeters of sedi-
ment, i.e., those sediments which are available for
resuspension into the water column. Based on a corre-
lation between sediment and tissue PCB concentrations
at the site (biota-to-sediment accumulation factor
[BSAF]), the natural recovery model for PCBs in sedi-
ment also predicts that PCBs in clam tissue will be
reduced to an acceptable level of risk within ten years.
Thea Foss Waterway Site
The Thea Foss Waterway is a navigation channel that
was carved into the Puyallup River delta near the turn of
the century; the waterway is part of the Commencement
~Bay Superfund Site and is presently undergoing reme-
dial design. The waterway has had a long and complex
urban land use history, and has accumulated a variety
of contaminants, but PAHs and phthalates appear to
pose the greatest risk to the ecological community. In
addition, two large storm drains—remnants of a
once-natural stream channel—collect runoff from much
of the City of Tacoma and discharge to the head of the
waterway.
A more complex model was warranted at this site, due to
the complexity of sources, the diversity of contaminants,
and to help the City manage pollutant loads associated
with storm water discharges. A two-dimensional con-
figuration of the EPA-supported computer code WASP
(Water Quality Analysis Simulation Program) was devel-
oped. The site was partitioned into seven horizontal
segments and four vertical segments (surface and deep
water, surface and subsurface sediment segments), as
shown on Figure 5A. Comprehensive data collection
efforts were required to develop site-specific model in-
put parameters, including age-dated cores, sediment
trap deployments, hydrodynamic studies, long-term out-
fall monitoring, water column sampling, sediment leach-
ability testing, and biodegradation rate measurements.
An example of model output for phenanthrene (a
low-molecular weight PAH) is shown on Figure 5B. The
model predicts surface sediment concentrations (seg-
ments 15 through 21) on a yearly basis for ten years;
shaded boxes indicate predicted sediment concentra-
tions which exceed the Sediment Quality Objective (SQO)
for phenanthrene (1,500 (ig/kg) in Commencement Bay.
Although initial sediment concentrations are above the
SQO at the head of the waterway (segments 19, 20, and
21) and in an isolated hot spot at the mouth of the
waterway (segment 16), sediment concentrations are
everywhere predicted to recover to below the SQO
within eight years in all waterway segments.
Although it usually requires more costly data collection
efforts and more rigorous calibration, the WASP model
is a flexible and powerful analytical tool for use in natural
recovery predictions, and for managing contaminated
sediments in general. The model is capable of describ-
ing all of the contaminant transport processes depicted
on Figure 1, and is one of the best tools available for
quantifying the relationship between spatially distributed
source loads and sediment concentrations in a receiving
water body.
Conclusions
Natural recovery should be given due consideration in
the formulation of sediment remedial alternatives, if not
alone, then in combination with more active remedial
technologies such as dredging and/or capping. Natural
recovery has been successfully applied as a key compo-
nent in cleanup strategies at several sites in Puget
Sound, and has been recognized by regulators for its
importance in optimizing our limited resources while
reducing site risk. Several technical approaches to natu-
ral recovery analysis are available, with varying levels of
complexity, which can be tailored to the special needs of
a project.
41
-------
(A) WASP Model Segments
Thea Foss Waterway
. Surface Water
Deep Water Layer
Surface Sediment Bed (0 to 10 cm)
Subsurface Sediment Bed (10 to 40 cm)
(B) Predicted Phenanthrene Concentration in Surface Sediment (jig/kg)
Surface Sediment Segment Number
Year
0
1
2
3
4
5
6
7
8
9
10
Steady-State
15
1,240
1,170
1,100
1,050
995
948
906
868
834
804
777
540
16
- 2,790
y | ]t
^ pi
* 2,iOO *'
f -]t
1,920
*iii j i en
1.7^ \
i «
T ' *
1 1'S2° I
1,410
1,320
1,240
673
| Predicted Sediment Concentration
17
1,230
1,150
1,090
1,040
998
962
933
909
889
872
859
791
Exceeds SQO
18
1,090
1,100
1,110
11,20
1,130
1,130
1,130
1,140
1,140
1,140
1,140
1,150
19
?^
•jkjiijjjtft ^
1,480
1,310
1,190
1,110
1,040
997
964
941
878
20
sftJifsR m
1,350
1,220
1,140
1,080
1,050
1,020
1,000
991
982
963
21
^§8^ •
^wsj$i?8U-<
$SK^M
|^|drf
-------
References ,3.
1. U.S. EPA, 1989. Commencement Bay Nearshore/
Tideflats Record of Decision, Region 10, Seattle,
WA, September 1989. 4.
2. Washington State Department of Ecology, 1995.
Sediment Management Standards, Chapter
173-204 Washington Administrative Code,
Amended December 1995.
U.S. EPA, 1994. EPA's Contaminated Sediment
Management Strategy, Washington, DC, August
1994.
Officer, Charles B., and Daniel R. Lynch, 1989.
Bioturbation, Sedimentation and Sediment-Water
Exchanges. Estuarine, Coastal and Shelf Science
28:1-12.
Ambrose, Robert B., Tim A. Wool, and James L
Martin, 1993. The Water Quality Analysis Simula-
tion Program, WASP 5, Environmental Research
Laboratory, Athens, GA, September 20,1993.
43
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In-Situ Capping of Contaminated Sediment
bverview and Case Studies
Michael R. Palermo
Research Civil Engineer, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS
Abstract
In-situ capping, the placement of a subaqueous cover-
ing or cap of clean isolating material over an in-situ
deposit of contaminated sediment, is a potentially eco-
nomical and effective approach for remediation of con-
taminated sediment. A number of sites have been
remediated by in-situ capping operations worldwide.
EPA has developed detailed guidelines for planning,
design, construction, and monitoring of in-situ capping
projects. This paper briefly describes the major aspects
of In-situ capping as an option and provides a summary
of recent case studies.
In-Situ Capping Defined
In-silu capping (ISC) refers to placement of a subaque-
ous covering or cap over an in-situ deposit of contami-
nated sediment. The cap may be constructed of clean
sediments, sand, gravel, or may involve a more complex
design with geotextiles, liners and multiple layers. In-situ
capping can serve three primary functions:
a. physical isolation of the contaminated sediment
from the benthic environment,
b. stabilization of contaminated sediments, prevent-
ing resuspension and transport toother sites, and
c. reduction of the flux of dissolved contaminants
into the water column.
To achieve these results, an in-situ capping project must
be treated as an engineered project with carefully con-
sidered design, construction, and monitoring. The basic
criterion for a successful capping project is simply that
the cap required to perform some or all of these func-
tions be successfully designed, placed, and maintained.
Design Guidance for In-Situ Capping
Detailed guidelines for designing, constructing and man-
aging in-situ capping as a sediment remediation alterna-
tive have been developed by the U.S. Environmental
Protection Agency (USEPA) under the Assessment and
Remediation of Contaminated Sediments Program, ad-
ministered by USEPA's Great Lakes National Program
Office, in Chicago, IL. (1) The major activities associated
with evaluating an ISC option include:
1. Set a cleanup objective, i.e., a contaminant con-
centration or other benchmark, The cleanup ob-
jective will be developed as a prerequisite to the
evaluation of all remediation alternatives.
2. Characterize the contaminated sediment site un-
der consideration for remediation. This includes
gathering data on waterway features (water depths,
bathymetry, currents, wave energies, etc.); water-
way uses (navigation, recreation, water supply,
wastewater discharge, etc.); and information on
geotechnical conditions (stratification of underly-
ing sediment layers, depth to bedrock, physical
properties of foundation layers, potential for ground-
water flow, etc.). Determine if advective processes
are present and the ability of the cap to control
advective contaminant losses. Determine any in-
stitutional constraints associated with placement
of a cap at the site.
3. Characterize the contaminated sediments under
consideration. This includes the physical, chemi-
cal, and biological characteristics of the sediments.
These characteristics should be determined both
horizontally and vertically. The results of the char-
acterization, in concert with the cleanup objective,
will determine the areal extent or boundaries of
the area to be capped.
4. Make a preliminary determination on the feasibility
of ISC based on information obtained about the
site and sediments. If site conditions or institu-
tional constraints indicate that ISC is not feasible,
other remediation options must be considered.
5. Identify potential sources of capping materials,
including clean sediments that might be dredged
44
-------
and upland sites or commercial sources for soil,
gravel and stone.
6. Design the cap composition and thickness. Caps
will normally be composed of clean sediments,
however, other materials such as armor stone or
geotextiles may be considered. The cap design
must consider the need for effective short- and
long-term chemical isolation of contaminants, bio-
turbation, consolidation, erosion, and other perti-
nent processes. If the potential for erosion of the
cap is significant, the cap thickness can be in-
creased, provisions can be made for placement of
additional cap material following .erosion, other
capping materials could be considered, or an
armor layer could be incorporated into the design.
Cross sections illustrating the designs of several
caps are shown in Figure 1.
7. Select appropriate equipment and placement tech-
niques for the capping materials. The potential for
short-term contaminant losses associated with cap
placement should be considered in selecting a
placement approach.
8. Evaluate if the capping design meets the cleanup
objectives. If not, either reevaluate cap design or
consider other alternatives.
9. Develop an appropriate monitoring and manage-
ment program to include construction monitoring
during cap placement and long-term monitoring
following cap placement. The site management
program should include actions to be taken based'
on the results of monitoring and provisions for
future maintenance.
10. Develop cost estimates for the project to include
construction, monitoring and maintenance costs.
If costs are acceptable, implement. If costs are
unacceptable, reevaluate design or consider other
alternatives.
Case Studies
A number of ISC operations have been performed under
varying site conditions, and are summarized in Table 1.
ISC has been applied to riverine, nearshore, and estua-
rine settings. Conventional dredging and construction
equipment and techniques have been used for ISC
projects, but these practices were precisely controlled.
The success of projects to date and available monitoring
data at several sites indicates that ISC can be an
effective technique for long-term containment of con-
taminants.
In-situ capping of nutrient-laden sediments with sand
has been demonstrated at a number of sites in Japan,
including embayments and interior lakes (2). The pri-
mary objective of the capping was to reduce the release
of nutrients (nitrogen and phosphorous) and oxygen
depletion by bottom sediments which were contributing
to degraded water quality conditions. Studies have in-
cluded measurements of nutrients in interstitial and over-
lying water at capped sites, development of a numerical
model for predicting water quality improvements from
capping, and monitoring benthos recovery at capped
sites.
A variety of ISC projects have been conducted in the
Puget Sound area. At the Denny Way project, a layer of
sandy capping sediment was spread over a three-acre
contaminated nearshore area with water depths of 20 to
60 feet (see Figure 2). A combination of a sewer outfall
discharge and combined sewer overflow (CSO) had
contaminated the site with lead, mercury, zinc, PAHs
and PCBs. The capping was a cooperative effort be-
tween the Municipality of Metropolitan Seattle (METRO)
and the Seattle District, USAGE (3, 4). At the Simpson-
Tacoma Kraft paper mill, ISC was conducted as part of a
Superfund project. Discharges of paper and pulp mill
waste had contaminated-the site with PAHs, naphtha-
lene, phenol, dioxins, and other contaminants. A 17-
acre area was capped with material from a sand bar in
the adjacent Puyallup River. An in-situ capping project
at the Eagle Harbor Superfund site at Brainbridge Island
placed a 3-to-6 foot layer of sand over creosote contami-
nated sediments in water depths of 40-60 feet. Sedi-
ments dredged from the Snohomish River navigation
project were transported to Eagle Harbor and placed
over a capped area of about 54 acres (4). It was decided
to cap two areas at the site with different materials (see
Figure 3). Areas 1 and 2 are at a water depth of 17 and
13 m, respectively. A split hull barge was used in Area 1
and the water jet washing of material off of a barge was
used for Area 2. Other ISC projects in the Puget Sound
area include those at the West Waterway and Piers 51,
53, and 54.
ISC, with an armoring layer, has also been demon-
strated at a Superfund site in Sheboygan Falls, Wl. This
project involved placement of a composite cap, with
layers of gravel and geotextile to cover several small
areas of PCB-contaminated sediments in a shallow (<5
feet) river and floodway (see Figure 1). A total area of
about one acre of cap was placed with land-based
construction equipment and manual labor (5).
At Eitrheirn Bay in Norway, a composite cap of geotextile
and gabions was constructed as a remediation project in
a fjord at an area contaminated with heavy metals (6). A
total area of 100,000 square meters was capped, in
water depths of up to 10 meters.
At Manistique, Ml, an interim cap of 40-mil thick plastic
liner was placed over a small (0.5 acre) deposit of PCB-
contaminated sediments in order to prevent the
resuspension and transport of sediments until a final
remediation was implemented. A larger area was evalu-
ated for capping, with the cap design incorporating an
armor layer and sand layer enhanced with activated
carbon (see Figure 1).
45
-------
Geotextile
A. Sheybogan, Wl
Sand
Gravel
Geogrid
Existing sediment
24" Win.
B. Convair Lagoon, CA
Geotextile Fabric
12" Graded Armor Stone
20"Sand Material-
Sediment
Bedrock.
Geotextile Fabric-
12" Graded Armor Stone
20" Enhanced Sand Material
gumenteti
Carbon)
(Augumented with Activated/"
Sediment-
Bedrock—
f
_r
C. Manistique,
Figure 1. Illustrations of alternative combinations of cap components.
46
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Table 1. Summary of Selected In-Situ Capping Projects
Project Location
Lakaemjaa'pnaner
Contaminants Site Conditions
Nutrients 3,700 m2
Cap Design
Fine sand, 5 and
20cm
Construction
Methods
Reference
Nutrients
20,000m2
Fine sand, 20 cm
Denny Way, WA PAHs, RGBs
Simpson-
Tacoma, WA
Eagle Harbor,
WA
Sheboygan
River, Wl
creosote,
PAHs, dioxins
cresote
p_R
PCBs
3 acres nearshore with
depths from 20 to 60 ft.
17 acres nearshore with
varying depth
54 acres within
embayment
several small areas of
shallow river/ floodplain
sediment* ^"^ barge sPreadin9 Sumeri et al. 1995
4 to 20 feet of sandy hydraulic pipeline
sediment
3 ft of sandy
sediment
sand layer with
armor stone
with "sandbox"
direct mechanical
placement
Sumeri etal. 1995
Sumeri i
Eleder
Manistique
River, Ml
PCBs
20,000 ft2 shoal in river
with depths of 10-15 ft
40 mil plastic liner Placement by crane Hahnenberg, pers
r from barge comm
Hamilton Harbor, PAHs, metals,
Ontario nutrients
10,000 m2 portion of
large, industrial harbor
0.5 m sand
Tremie Tube
:Zeman, pers comm
Convair Lagoon, D,^0
CA robs
No2apy' ^a,s
St. Lawrence
River, Massena, PCBs
NY
5 acres nearshore
1 00,000 M2
75,000ft2
sand and gravel
geotextile and
gabions
6 in sand/6 in
gravel/6 in stone
under construction
deployed from barge
placed by bucket
from barge
Instanes 1994
Kenna, pers comm
PCB-contaminated sediments at the .General Motors
Superfund site in Massena, NY, were removed from the
St. Lawrence River by dredging. The remedial objective
for the site was 1 ppm, but areas remaining at concen-
trations greater than 10 ppm after repeated dredging
attempts were capped. An area of approximately 75,000
square feet was capped with a three-layer ISC com-
posed of 6 inches of sand, 6 inches of gravel and 6
inches of armor stone.
At Convair Lagoon, in San Diego Bay, a multilayer cap
with a layer of gravel and sand is currently under con-
struction (7). The total area to be capped is approxi-
mately 5 acres (see Figure 4). The full sand and gravel
cap will be placed over a portion of the site, and a sand
cap layer over a less-contaminated portion. The site will
also be confined by a submerged gravel berm. This
project is unique in that the gravel layer was incorpo-
rated into the cap design to prevent bioturbation by deep
burrowing shrimp which were known to inhabit the area.
The gravel layer was located below the sand layer as a
barrier to the burrowing shrimp (see Figure 1). The
materials are to be placed from barges.
At Hamilton Harbor, in Burlington, Ontario, a 0.5 m-thick
sand cap was placed over a 10,000 rrf area of PAH-
contaminated sediments (see Figure 5) as a technology
demonstration conducted by Environment Canada (8,9).
The cap material was placed using a barge-mounted
array of tremie tubes for sand spreading. The barge was
guided by a system of anchors and cables for precise
positioning (see Figure 6). ,.-...
Field monitoring studies have been conducted on long-
term effectiveness of dredged material caps located in
Long Island Sound, the New York Bight, and in Puget
Sound. Sequences of cores taken over time periods of
up to 15 years (10,11,12) show a clear visual transition
from cap to contaminated sediment and are closely
correlated with sharp changes in the sediment chemistry
profiles. The data collected to date suggests that there
has been minimal long-term transport of contaminants
up into the caps. All of the in-situ capping projects
mentioned above have monitoring programs in place, so
there will be a great deal of additional data on capping
effectiveness available in the future.
47
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Figure 2. Sandy capping sediment over a three-acre contaminated nearshore area—Denny Way project.
YSQWM.T
Figure 3. Sandy capping sediment over a three-acre contaminated nearshore area—Eagle Harbor project.
Summary
An ISC operation must be treated as an engineered
project with carefully considered design, construction,
and monitoring to ensure that the design is adequate. A
number of ISC projects have been implemented world-
wide for a wide range of project conditions. These
projects have incorporated several types of cap designs,
cap materials, and cap placement methods. Detailed
guidance for planning, design, construction, and moni-
toring of in-situ capping projects has been developed by
EPA and should be followed when evaluating the feasi-
bility of in-situ capping as a sediment remediation tech-
nique.
48
-------
Top of sea wall
(+10 ft)
Legend
[Bathymetry lines
•Geotextile cap
Biolayer cap
Sand cap
Perimeter bemn
Figure 4. Total area to be capped (approximately 5 acres, Convair Lagoon).
49
-------
LaSalte
Park
^-"-location
ofeapstte
Hamilton Harbour
o 1 2km
Figure 5. Sand cap over PAH-contaminated sediments (Hamilton Harbor, Burlington, Ontario).
Anchor
Cable
Winch
Barge
47941OO
5834QQ
47941OO *
5S35OO
Guide
J
47940OO
593400
4794QO0
59350G «
Anchor
Cable
Winch
50
Scale (m)
too
Figure 6. System of anchors and cables for precise positioning (Hamilton Harbor, Burlington, Ontario).
Acknowledgment
This paper summarizes work conducted for the U.S.
Environmental Protection Agency Assessment and
Remediation of Contaminated Sediments (ARCS) Pro-
gram by the U.S. Army Engineer Waterways Experiment
Station. Permission to publish this material was granted
by the Chief of Engineers.
References
1. Palermo, M.R., S. Maynord, J. Miller, and D.
Reible, Guidance for In-Situ Subaqueous Cap-
ping of Contaminated Sediments, EPA 905-1396-
004, Assessment and Remediation of Contami-
nated Sediments Program, Great Lakes National
4.
Program Office, U.S. Environmental Protection
Agency, Chicago, IL
Zeman, A. J., S. Sills, J.E. Graham, and K.A.
Klein, 1992. Subaqueous Capping of Contami-
nated Sediments: Annotated Bibliography, NWRI
Contribution No. 92-65, National Water Research
Institute, Burlington, Ontario.
Sumeri, A. 1989. "Confined Aquatic Disposal and
Capping of Contaminated Bottom Sediments in
Puget Sound," 12th World Dredging Congress,
Orlando, FL.
Sumeri, A. 1995. "Dredged Material is Not Spoil—
A Status on the Use of Dredged Material in Puget
Sound to Isolate Contaminated Sediments," 14th
50
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World Dredging Congress, Amsterdam, The Neth-
erlands.
5. Eleder, B. 1992. "Sheboygan River Capping/
armoring Demonstration Project," Presented at a
Workshop on Capping Contaminated Sediments,
May 27-28, 1992, Chicago, IL
6. Instanes. D. 1994. "Pollution Control of a Norwe-
gian Fjord by Use of Geotextiles," Fifth Interna-
tional Conference on Geotextiles, Geomembranes,
and Related Products, Singapore, 5-9 September
1994.
7. Ogden Environmental and Energy Services. 1993.
Environmental Impact Report—Remedial Action
Plan - Convair Lagoon Remediation, Report pre-
pared for San Diego Unified Port District, San
Diego, California.
8. Zeman, A.J. and T.S. Patterson, 1996a. "Prelimi-
nary Results of Demonstration Capping Project in
Hamilton Harbor," NWRI Contribution No. 96-53,
National Water Research Institute, Burlington,
Ontario.
9.
10.
11.
12.
Zeman, A.J. and T.S. Patterson, 1996. "Results of
the In-situ Capping Demonstration Project in
Hamilton Harbor, Lake Ontario," NWRI Contribu-
tion No. 96-75, National Water Research Institute,
Burlington, Ontario.
Fredette, T. J., J.D. German, P.G. Kullberg, D.A.
Carey, and P. Murray, 1992. "Chemical Stability of
Capped Dredged Material Disposal Mounds in
Long Island Sound/USA." 1st International Ocean
Pollution Symposium, Mayaguez, Puerto Rico.
Chemistry and Ecology.
Brannon, J., and M.E. Poindexter-Rollins, 1990.
"Consolidation and Contaminant Migration in a
Capped Dredged Material Deposit," Sci. TotEnv.,
91,115-126.
Sumeri, A., T.J. Fredette, P.G. Kullberg, J.D. Ger-
man, D.A. Carey, and P. Pechko, 1994. "Sedi-
ment Chemistry Profiles of Capped Dredged Ma-
terial Deposits Taken 3 to 11 Years after Cap-
ping," Dredging Research Technical Note DRP-5-
09, U.S. Army Engineer Waterways Experiment
Station, Vicksburg, MS.
51
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Observations Regarding Brownfieids and Sediment
Disposal at Indiana Harbor
David M. Petrovski, Environmental Scientist
U.S. Environmental Protection Agency
Region 5, Chicago, IL
Richard L Nagle, Attorney
U.S. Environmental Protection Agency
Region 5, Chicago, IL
Jan Miller, Environmental Engineer
USAGE, Great Lakes and Ohio River Division
Chicago, IL
Gregory N. Richardson, Principal
G.N. Richardson & Associates
Raleigh, NC
Abstract
To date, the 25-year delay in dredging the federal project
at Indiana Harbor in East Chicago, IN, has emphasized
the difficulties associated with implementing the current
federal approach to the disposal of contaminated sedi-
ments in the Great Lakes. The current method is pre-
mised upon the availability and provision of a clean,
close, cost-free upland or in-water site, which reverts
back to the provider after disposal operations have
ceased. An urban setting, high contaminant concentra-
tions, and liability concerns have made application of
this strategy at Indiana Harbor especially challenging.
Efforts to predict the liability exposure associated with
the use of a former refinery to dispose of Indiana Harbor
sediments have raised issues which may possess ge-
neric utility. Concepts rooted in these issues suggest a
new approach for the disposal of contaminated sedi-
ments. The new approach would preferentially select
contaminated brownfield sites associated with espe-
cially challenging remedial issues for the construction of
sediment disposal facilities. Properly implemented, this
would enhance public acceptance, reduce expenditures,
remediate unaddressed contaminated sites and allow
problematic dredging projects to proceed in a more
timely fashion.
The views contained in Ihis paper represent those of the authors and not the
policies or positions of the U.S. EPA or the USAGE.
Introduction
Every year in the Great Lakes approximately 4 million
cubic yards of sediments are dredged. Most of the
dredging is performed to maintain safe depths for com-
mercial and recreational navigation. Approximately half
of these dredged materials are clean, and can be dis-
posed in an unrestricted manner. The remaining 50% of
the sediments dredged (2 million cubic yards) are suffi-
ciently contaminated to preclude direct release to the
environment. Although some contaminated dredged
material may be suitable for beneficial uses such as
daily landfill cover or fill, such low-cost environmentally
acceptable disposal options are not always available. In
the absence of such disposal options, contaminated
dredged materials are generally placed in a confined
disposal facility (CDF).
The United States Army Corps of Engineers (USAGE)
constructs CDFs for the disposal of contaminated sedi-
ments dredged from federal navigation projects. In sev-
eral cases, CDFs have also been constructed for the
disposal of clean material where open-water disposal
was infeasible and a beneficial use was not identified.
CDF designs reflect both the nature of the sediments
slated for disposal and characteristics of the disposal
site (1). CDFs constructed at upland sites typically re-
semble a simple landfill, consisting of a perimeter earthen
dike with a weir for sediment dewatering. CDFs have
also been constructed in open-water settings, com-
monly with perimeter dikes of graded stone. The graded
52
-------
stone dike functions as a large filter, retaining the sedi-
ment particles while allowing the free passage of water.
The USAGE has constructed some 44 CDFs for the
disposal of contaminated dredged material from naviga-
tion projects in the Great Lakes. The size of these
facilities ranges from several to hundreds of acres, with
capacities of less than 100,000 to more than 15 million
cubic yards.
The siting, construction, operation and closure of CDFs
are handled by the USAGE under its civil works project
guidance. Application of this guidance is focused upon
the identification of a "local sponsor" for the proposed
dredging project. Referred to as "lands, easements &
rights-of-way," the central responsibility of the local spon-
sor is to provide the USAGE with a piece of property for
the construction of the CDF. According to the civil works
guidance (2), the site must be environmentally clean,
suitably close to the water body under consideration,
sufficiently sized to meet the projected disposal needs
and without debilitating access problems or other re-
strictions. This regulation specifically mandates that the
site either be uncontaminated initially or that the local
sponsor render the site clean before providing it to the
Corps. The purpose of this requirement is the elimina-
tion of any potential state or federal Superfund liability
under the Comprehensive Environmental Response,
Compensation and Liability Act (CERCLA) or hazardous
waste liability under the Resource Conservation and
Recovery Act (RCRA-Subtitle C), due to the provision of
a contaminated site by a local sponsor.
The Water Resource Development Act of 1996 contains
several sections which clarify federal policy on CDFs,
including the responsibilities of local sponsors. For all
deep-draft navigation projects (<18 feet), the local spon-
sor must provide a share of the construction costs as
well as the land, easements and rights-of-way for the
CDF. The cash cost share for the local sponsor ranges
from 25 to 50%, depending upon the depth of the harbor
and the value of the property used for CDF construction.
The local sponsor must be a public entity with taxing
authority; typically a municipality, county, state or in
several cases a port authority. Once the facility is con-
structed, filled with sediments and closed, the site and
CDF revert back to the local sponsor for long-term care
and maintenance.
As discussed below, this approach is difficult to apply
and can act as a barrier to the timely implementation of
navigation dredging projects. In addition to implementa-
tion problems, many of the perceived clean-site benefits
as well as contaminated-site liabilities could prove illu-
sionary.
The Two Traditional Approaches And
Associated Problems
The In-Water Approach
In practice, the CDF siting strategy has been imple-
mented in the Great Lakes in one of two ways. The more
common scenario centers upon a local sponsor provid-
ing the USAGE with a near-shore portion of lake or river
bottom upon which a CDF can be constructed and filled.
After filling and final closure, the site and the CDF
reverts back to the sponsor for long-term maintenance
and care. This approach is generally workable if the
sediments slated for disposal are viewed as only mildly
contaminated (i.e., could be essentially considered fill)
and the environmental concerns associated with the
project are regarded as limited. In-water sponsor identi-
fication can also be relatively straightforward, as a sub-
aqueous site provided to the USAGE at nominal cost
can result in the acquisition of a valuable piece of
waterfront property. In essence, the closed CDF's value
as real estate compensates for the costs of mainte-
nance and monitoring, as well as making any liability
concerns more palatable. However, if the contaminant
concentrations are viewed as elevated, implementation
of the in-water approach tends to become problematic.
In this case, environmental concerns can cause the in-
lake/water CDF disposal to become highly controversial,
dissipate local support and make regulatory approval
questionable.
In February of 1986, the problems this scenario can
entail were manifested with effect by a previous attempt
to dredge Indiana Harbor. A Draft Environmental Impact
Statement (DEIS) was prepared and released under the
National Environmental Policy Act (NEPA) (3).The pre-
ferred alternative in the 1986 DEIS consisted of the
construction of an in-lake CDF. The closed facility would
have formed a small island in Lake Michigan just east of
Jeorse Park in East Chicago, IN. Due to elevated con-
taminant concentrations (documented in the DEIS) and
the associated environmental considerations, local, state
and federal opposition became strident. After the inevi-
table delays and significant negative press, the proposal
was dropped.
The Upland Approach
The second CDF siting scenario is premised upon a
local sponsor providing a clean upland site at no cost to
the USAGE for CDF construction and sediment dis-
posal. Like an in-water site, the CDF subsequently
reverts back to the local sponsor after closure. As noted,
in addition to the need for a suitably sized proximal site
USAGE policy has traditionally required that the site be
uncontaminated. This requirement is in accordance with
USAGE guidance and is consistent with generally held
presumptions regarding future liability and site prepara-
tion costs.
Not surprisingly, implementation of the upland disposal
scenario for highly contaminated sediments (e.g., Indi-
ana Harbor) has also proven difficult. Like Indiana Har-
bor, most federal dredging projects are found in highly
urbanized/industrial settings, where clean, adequately
sized sites are rare. Should an acceptable contaminant-
free site be identified, its acquisition is almost invariably
not cost free. Apparently, few entities seem willing to
provide clean, multiple-acre urban sites to the federal
53
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government for the land disposal of contaminated sedi-
ments without compensation. In addition, but in contrast
to the filled-inlake CDF (i.e., newly created waterfront
property), reacquiring an upland site after CDF closure
Is generally not viewed as economically advantageous.
Above and beyond maintenance responsibilities and
costs, the local sponsor may also have significant con-
cerns regarding site liability.
Lastly, as the public views an upland CDF as a landfill,
the necessary public support can also be limited. Be-
cause of the urban setting, the surviving clean, adequately
sized sites proximal to many federal projects exist pri-
marily as parks or preserves. Other sites may have
escaped industrialization because of the presence of
wetlands and are now unavailable because of their
ecological importance and state and federal protection.
Invariably, local preferences for the use of these rela-
tively rare uncontaminated properties do not include the
construction of land disposal facilities, and upland CDF
proposals typically find little or no support from either the
local community or environmental organizations. Should
the selected proposal require trucking the sediments
from the federal project to the upland CDF site, the costs
of transportation can be coupled with enhanced local
concerns and opposition.
Application at Indiana Harbor
The difficulties outlined above tend to magnify as sedi-
ment contaminant levels increase, making efforts to
implement either the in-water or the upland disposal
scenarios at Indiana Harbor especially difficult. The
highly industrialized urban setting in conjunction with the
no-contamination stipulation in the Corps' civil works
guidance, disqualified numerous sites proximal to the
navigation channel from further consideration. Of the 20
clean sites identified and subjected to varying degrees
of further review, all were eliminated due to excessive
acquisition costs or distances to the federal project,
insufficient acreage, and/or wetland or ecologic issues.
The inability of the standard federal approach to effec-
tively identify an acceptable disposal site has precluded
dredging Indiana Harbor for over 25 years.The absence
of dredging has imparted a significant environmental
cost on Lake Michigan in the form of the continual and
unhindered migration of the grossly contaminated project
sediments into the southern portion of the basin. The
nature of the project sediments is discussed later in the
paper. As the factors hindering disposal site selection
are unlikely to abate, consideration of other disposal
strategies is warranted. The purpose of this paper is to
suggest and outline an alternative approach.
Navigational Projects And Brownfields
The United States Environmental Protection Agency
(USEPA) has defined brownfields as abandoned, idled
or under-utilized industrial or commercial sites where
expansion and redevelopment is hindered by real or
perceived environmental contamination (4). Ownership
of brownfield sites can range from private individuals
and corporations to states or municipalities which ac-
quired the property through tax default. The current
brownfield site owner may have had little or no involve-
ment with the activities which contaminated the site and
is commonly unable or unwilling to finance the site's
remediation. Brownfield redevelopment can mitigate the
need to develop pristine, ecologically valuable areas,
while increasing the economic viability of the surround-
ing community through supporting the local tax base
and creating jobs. Unlike the rare and costly clean
properties, brownfield sites are frequently common in
urban settings.
As reflected in the USAGE regulation, the real or per-
ceived presence of environmental contamination fosters
reluctance on the part of owners and potential develop-
ers to invest in the site. This hesitation is a manifestation
of the concern that they could become liable for site
remediation even if they had no involvement with the
contamination of the property. Financial institutions are
also disinclined to grant loans on brownfield properties
because of the same liability concerns and the fear that
the remedial costs could exceed the value of the prop-
erty (4).
Although reluctant to spend large sums on remediation,
current brownfield owners are frequently anxious to find
a productive use for their vacant or under-utilized prop-
erty. Site-use proposals which would address at least a
portion of the site's remedial needs would receive recep-
tive consideration from many brownfield owners. Use
scenarios coupled to entities willing to share in remedial
costs and other liabilities (real or perceived), should be
especially welcome. If remedial expenditures can be
kept reasonable, brownfield investors would be attracted
by low costs of site acquisition or access, centralized
urban locations, and the likelihood of sharing the reme-
dial costs and any liability with the current owner as well
as any associated potentially responsible parties (PRPs).
Site-use proposals coupled with remediation may also
prove more acceptable to the local community and
interested environmental groups. Given an estimated
450,000 brownfield sites in the U.S. (4) and the ten-
dency for these sites to concentrate in the historically
urbanized and industrialized areas which surround fed-
eral navigation projects, brownfield candidate sites should
be readily identifiable at many locations where CDFs are
needed.
The remedial needs of brownfield sites can range from
the trivial to the intractable. This range is a reflection of
the nature of the hydrogeologic factors at the site and
the nature and extent of the contamination. Through the
Technical Impracticability (Tl) guidance, the USEPA has
acknowledged that the presence of immiscible non-
aqueous phase liquids (NAPLs) at a site can entail
remedial issues which are especially challenging and
which may pose technical limitations to aquifer restora-
tion (5). Essentially this is due to the immobility of a
significant portion of the NAPL contamination under
most groundwater flow conditions. The immobile NAPL
54
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fraction resides as small discontinuous accumulations in
the pore space of the geologic material, and is termed,
residual saturation (VNAPL/VVOI ) (6, 7). The concept of
residual saturation has long been recognized by the
petroleum industry as a limitation to the recovery of
crude oil from petroleum reservoirs (8). Residual satura-
tion for NAPLs typically ranges from 10 to 20% in the
unsaturated zone, and from 10 to 50% saturated zone
(6, 7). NAPLs can be both more dense than water
(DNAPLs), or less dense than water (LNAPLs). LNAPL
accumulations are commonly composed of hydrocar-
bons and can generally be found at sites associated with
the refining and storage of crude oil products.
The remedial technologies available to address NAPL
contamination are not as advanced as the approaches
developed for other groundwater contamination prob-
lems (6, 9,10). NAPL accumulations at residual satura-
tion can act as a significant and long-term source of
groundwater contamination (6). Due to the practical
limitations regarding NAPL recovery, containment of the
NAPL may be a technically implementable and environ-
mentally acceptable remedial option (7).
Conceptually, containment can be conducted in one of
four ways. While not eliminating the source of the con-
tamination, the purpose behind all containment ap-
proaches is to render the impact of the contamination in
the area to be contained on adjacent areas environmen-
tally negligible. With proper consideration of the site's
hydrogeology, all of the containment approaches dis-
cussed below can be incorporated into the design of the
CDF.
The first approach relies on the manipulation of the
groundwater gradients in the vicinity of the region under
consideration through the creation of areas of low hy-
draulic head. This can eliminate or significantly mitigate
the migration of impacted water from the area to be
contained. Gradient alteration is generally conducted by
the placement of water removal mechanisms (com-
monly in the form of wells). Without the physical place-
ment of a barrier material between the area to be
segregated and the adjacent areas of the site, hydraulic
isolation can effectively segregate the contaminated
area from the other portions of the site. In contrast, a
second approach would rely on the placement of a
physical barrier between the contamination and the
adjacent materials. Usually a barrier material associated
with a reduced ability to transmit water (e.g., hydraulic
conductivity values in the range of 1QS to 1Q-7 cm/s,
comparable to a compacted soil liner) would be con-
structed around the area to be isolated. A third approach
is a composite design which couples both of the gradient
control and barrier placement approaches. Specifically,
this involves constructing a barrier with a reduced ability
to transmit around the area to be isolated and placing a
water removal mechanism within the interior side of the
perimeter to control the hydraulic gradient. Most con-
tainment systems which incorporate physical barriers
also include groundwater extraction (7). Currently, a
fourth approach is receiving much attention and is ac-
tively being investigated by the research community (7,
11). This method consists of surrounding the area to be
contained (or at least a section of the down-gradient
boundary) with a barrier composed of a reactive mate-
rial. As impacted groundwater migrates through the
reactive barrier, the contaminant concentration(s) is suf-
ficiently reduced through chemical, physical or biological
processes to meet the remedial needs of the site.
At brownfield sites where containment is viewed as an
appropriate remedial goal, the remedial containment
components could be incorporated into the proposed
CDF design. Such a "composite or remedial CDF,"
addressing at least a portion of the site's environmental
needs could significantly enhance the potential for local
acceptance as well as support from interested environ-
mental organizations. After closure of the CDF, the
property could be used for a va'riety of low-impact appli-
cations, such as parks (e.g., a golf course), or light
industry.
The Indiana Harbor Experience
Indiana Harbor
The Grand Calumet River and the Indiana Harbor Canal
(GCR/IHC) drain an area of approximately 174 knf (67
mi2) located on the southern shore of Lake Michigan in
northwest Indiana (12) (Figure 1).The area surrounding
the GCR/IHC is home to one of the most significant
concentrations of heavy industry in the world. The fed-
eral navigation project extends from the harbor at Lake
Michigan to approximately 4 miles upstream and covers
approximately 265 acres (Figure 2). Initially a drainage
ditch, the federal project at Indiana Harbor was originally
authorized by the River and Harbor Act of 1910, and has
been repeatedly widened, deepened and dredged since
that time. Sediments which enter the GCR/IHC tend to
accumulate in the artificially deepened federal naviga-
tion channel, reducing depths and ultimately restricting
navigation traffic. In order to maintain adequate naviga-
tional depths, the USAGE is authorized to dredge these
sediments when necessary.
From 1955 to 1972, approximately 75,000 rrf of sedi-
ments were dredged annually from the federal project at
Indiana Harbor (12). Until 1966, dredged materials were
dumped directly into Lake Michigan at approved open-
lake disposal areas. During the next several years,
maintenance dredgings were placed at several lake-fill
disposal sites in the vicinity of the project. However,
since 1972, the inability to identify an acceptable dis-
posal site has precluded dredging. This has resulted in
the accumulation of over 760,000 nf (one million cubic
yards) of highly contaminated sediments within the limits
of the federal project.
Current contaminant sources for the federal project in-
clude municipal and industrial discharges, combined
sewer overflows, runoff from urban and industrial areas,
contaminated sediment migration from the upstream
river reaches, and potential erosion of contaminated soil
55
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/ i
{ City boundary
1
Calumet
FIflura 1. Location of Indiana Harbor (3).
Indiana Harbor, Indiana
Vicinity Map
Plate 1
56
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jj 6u|9q B9JV
a
a
C
o
I
2
04
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57
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and fill along the unrestrained portions of the channel
banks. Municipal and industrial discharges, combined
sewer overflows and urban runoff have been estimated
to contribute over 110,000 m3 of sediment to the IHC/
GCR annually (12). A significant portion of the existing
sediment contamination is considered to be the result of
spills and point-source releases which predated most of
the current federal and state environmental legislation
Including the Clean Water Act.
Indiana Harbor contains some of the most heavily con-
taminated sediments in the Great Lakes. The bottom
sediments in all portions of the IHC/GCR are known to
be associated with a variety of contaminants, including
free phase oil, polychlorinated biphenyls (PCBs), poly-
cyclic aromatic compounds (PAHs), volatile organic com-
pounds, and heavy metals. For example, dry weight oil
and grease concentrations for 0.91 m (3 ft) core samples
collected by the USAGE in 1979 from 13 locations within
the project, averaged 56,146 mg/kg (3). In 1973, the
IHC/GCR were designated a "Problem Area" by the
International Joint Commission (IJC) for the Great Lakes.
In addition, the project sediments have been classified
as "heavily polluted," under the USEPA1977 Guidelines
for the Pollutional Classification of Great Lakes Harbor
Sediments (13), and in 1981, the IJC designated IH/
GCR as one of the Areas of Concern (AOC) around the
Great Lakes (12). Two reaches of the channel have
been found to contain PCB concentrations exceeding 50
pprn, and would be regulated under the Toxic Sub-
stance Control Act (TSCA) if dredged. Through a sam-
pling effort in 1992, Region 5 determined that a portion
of the sediments in the outer harbor would require
handling under the RCRA-Subtitle C as hazardous waste
if dredged.
The federal project at Indiana Harbor has not been
dredged since 1972. As a result, it is believed that the
federal channel is no longer functioning as a trap for the
sediments which enter the project. In essence, sediment
input into the federal project equals sediment output to
Lake Michigan. This conclusion is supported by 25
years of bathymetric survey data. These data reveal that
the rates of sediment accumulation in the project were
greatest between 1972 and 1980 and that subsequently
sedimentation rates have decreased notably (12).Cur-
rently, sediments which would settle within the limits of
the project if dredged to authorized depths, are dis-
charging to the Lake. The contaminated nature of the
sediments make their release to Lake Michigan highly
undesirable. Contaminants which enter Lake Michigan
are quickly dispersed by wave action and near-shore
currents, rendering subsequent capture and remediation
unlikely. The USAGE has estimated that 75,000 to
150,000 m3 of contaminated sediments are currently
being discharged from the mouth of Indiana Harbor
annually (12). Restoring and maintaining the navigation
channel at authorized depths would create a sediment
trap capable of reducing this release rate by an esti-
mated 50 to 70% (12).
Current Indiana Harbor Proposal
A second DEIS for the dredging of Indiana Harbor was
jointly issued by the USAGE and USEPA Region 5 in
October 1995. Despite the USAGE preference for clean
sites, the recommended alternative in the DEIS con-
sisted of the construction of an upland CDF at the
Energy Cooperative Incorporated (ECI) site in East Chi-
cago, IN (Figure 3). As documented in the DEIS, the
selection of the ECI property was based upon the ab-
sence of available, clean, close, cost-effective, adequately
sized sites in the area surrounding the federal naviga-
tion project at Indiana Harbor (12).
From 1919 until the early 1980s, the ECI site housed a
petroleum refining operation. In 1980, ECI acquired
interim status under RCRA Subtitle C through the opera-
tion of several onsite hazardous waste units. Shortly
thereafter, ECI declared bankruptcy under chapter 7.
Subsequently, the facility structures were razed and the
site was graded. Despite these activities, the RCRA
hazardous waste units were never formally closed and
the onsite contamination was never addressed. In com-
pensation for taxes, the site was acquired by the City of
East Chicago in 1990. As a consortium of companies,
ECI left an estate of almost $33 million upon filing for
chapter 11 bankruptcy in 1984. In May of 1992, the
Department of Justice on behalf of USEPA and the
Coast Guard, filed a claim for the costs of environmental
remediation. This activity resulted in the procurement of
$13.22 million for site remediation and CDF construc-
tion. As discussed in more detail below, the site
remediation components and the CDF design compo-
nents exhibit considerable overlap, thereby further re-
ducing the expenditures associated with the use of the
ECI site.
Covering approximately 168 acres, the ECI site-use
proposal is large enough to meet the disposal needs at
Indiana Harbor for approximately 30 years.The site also
is located to the north of the Lake George Branch of the
federal navigation project (Figure 3).This proximal loca-
tion minimizes transportation difficulties, costs and any
associated public concerns. In addition, because of the
nature and extent of the onsite contamination, the ECI
site is available for use by a local sponsor through the
City of East Chicago at nominal cost.
The geology at the ECI site consists of a 30-foot layer of
sand overlying a glacial till of low permeability. In addi-
tion, much of the site is covered by a thin veneer of fill
(generally thought to consist primarily of iron and steel
slag), ranging in thickness from several to approximately
10 feet and hydraulically behaving much like the sand
(14). The water table at the site ranges from grade to
several feet below grade. The 60-plus years of refinery
operations severely contaminated the onsite soil materi-
als and ground water. Over large portions of the site, the
water table is covered by a layer of lighter-than-water
free-phase hydrocarbons (oil) or LNAPLs, which in places
58
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• Slurry
wall
North cell area
occupied
by CDF 43 acres
D
>^ •
sVt*\ 1 1 '
_,
X 1 1 1 IN
! \ I i I I j
Decant structure
' / i i i i *
SI 1 ( i !>•
South cell area .
occupied by CDF
88 acres
~-^~\
1
1
I
*"" ' " '" " " ' """ •"" ^ -- -- *•-- ~ -- -- ~ ^~- ~— ~~~.
t-j-,-,v-,-,-,-,-,-,-,-r:::.:.:: r '_'.' '_'. .v.
Lake George canal
CDF
dike
walls
. Slurry
Xwall
Figure 3. Plan view of the proposed ECI site CDF (12).
400 200 0 - 400
59
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can exceed a thickness of 8 feet. In addition to the
hydrocarbon contamination, other contaminants known
to be associated with the site include PCBs and heavy
metals. Many of these same contaminants are also
found In the IHC sediments. The ground water at much
of the site initially discharged to the Lake George Branch
of the federal navigation project. This resulted in the
release of free-phase oil from the site to the surface
water in the IHC. This situation was corrected in the
early 1990s, when under the direction of the Indiana
Department of Environmental Management (IDEM), an
oil removal system was installed along the edge of the
canal.
Composite/remedial CDF Design
In the early 1990s, Region 5, USAGE, IDEM, the City of
East Chicago and other parties became actively in-
volved in assessing the feasibility of coupling the con-
ceptual CDF design with the outstanding RCRA closure
and corrective action needs of the site. After extensive
discussions, consensus was reached regarding a CDF
design which would meet the engineering necessities of
the USAGE, and fulfill the closure and corrective action
needs of RCRA. If constructed and operated properly,
this CDF design would provide a comprehensive envi-
ronmental solution for the underlying portions of the ECI
site and a sediment disposal capacity projected to meet
USAGE needs for 30 years. The proposed CDF design
would cover approximately 168 acres of the ECI site,
and would have a containment capacity of 4.7 million
cubic yards. Once the CDF is filled and closed, future
site use options could include use as a park or a golf
course.
The proposed CDF design (Figure 4) features a trap-
ezoidal dike wall which would surround the perimeter of
the facility. The interior face of the dike wall will be
covered by a compacted layer of clay several feet thick.
The compacted layer of clay will be tied into an underly-
ing vertical slurry wall of low permeability.The slurry wall
would extend down through the slag and sand layers
into the underlying low permeability clay till. A series of
well points located along the interior perimeter of the
CDF would function as a gradient control/sediment de-
watering/leachate collection system (12) (see figure 4).
After the CDF is filled, the closure design would consist
of a layer of compacted clay, overlain by a drainage
layer and topped by a layer of seeded top soil. The
proposed CDF design should ensure the containment of
the underlying in-situ LNAPL contamination, address
the RCRA corrective action requirements and comply
with the closure performance specifications for RCRA
hazardous waste units. In addition, the CDF will also
environmentally isolate the contaminated IHC sediments,
meet the TSCA requirements for PCS contaminated
sediment disposal, fulfill the USAGE'S engineering re-
quirements for sediment disposal and meet the long-
term disposal capacity needs of the USAGE at Indiana
Harbor. Obviously, the same CDF design components
will meet the needs of various overlapping regulatory
and engineering requirements. For example, the well
points placed into the underlying sand aquifer and used
to extract ground water from the interior of the facility,
would function as a gradient control, sediment dewater-
ing and/or leachate collection system. As all of these
terms refer to the same mechanism, language prefer-
ences would tend to be Agency and program depen-
dent.
Liability Considerations
Successful CDF partnerships are commonly based upon
the equitable partitioning of the liability which the CDF
could represent. Liability for existing CDFs is shared
between USAGE and the local sponsor. The sponsor is
required to "hold harmless" the federal government from
any damages not due to the fault or negligence of the
Corps or its contractors. Essentially, the USAGE retains
liability for the CDF design and construction in perpetu-
ity, while the sponsor is primarily liable for maintenance
of the facility after closure and any damages or impacts
due to a lack of maintenance during the post-closure
period. The time needed for CDF construction, project
completion and CDF closure can range from several
years to several decades. For example, the projected
operational life of the Indiana Harbor CDF is 30 years.
Should a third party wish to use the CDF for sediment
disposal, an agreement for the partitioning of the associ-
ated liability would need to be established.
In the case of Indiana Harbor, a worst-case remedial
scenario has been projected as a situation which would
require complete replacement of the CDF's perimeter
slurry wall. The cost of implementing this worst-case
scenario has been estimated to be approximately $6
million (1993 dollars). During the approximately 30 years
needed to construct, operate and close the CDF, the
USAGE will bear most of the liability associated with the
site, and could be called upon should the CDF require
some form of remediation. During this same period, the
local sponsor would need to establish the assurances
required to effectuate the worst-case remedial scenario
(the $6 million at the same 1993 valuation). This would
need to be completed prior to the reversion of the site
back to their control. Lastly, any local entity which used
the CDF for sediment disposal would also acquire a
portion of the liability represented by the CDF. This
could be converted into a negotiated cash sum provided
to the local sponsor and/or the USAGE.
At Indiana Harbor, although final agreements have not
been reached, a conceptual framework for the manage-
ment of the liability has been discussed. These ideas
include: environmental insurance purchased as part of
the local sponsor's annual operation and maintenance
(O&M) responsibilities; a per-cubic yard surcharge to
the local CDF users for the establishment of the $6-
million fund; and local bonding that would provide the
necessary funds though a number of possible surcharges.
60
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2' Clean fill
Dewatering well
Dredged material
SJt^yssjyssyysjyss^^
Top of existing soil
Top of existing grade
Medium dense sand
33'
Soil bentonite -
slurry wall
Monitoring
well
Stiff to very stiff clay
Cap detail
Grass
5" Topsoil
6" Sand
Top of dredged material
Figure 4. Section view of the proposed ECI site CDF (12).
Brownfields vs. Greenfields
At first glance, although use of a green site would
appear to have fewer liability concerns than use of a
brownfield site, this may not always be the case. The
soils and ground water at a pristine site would need to
be kept pristine. Consequently, acceptable green-site
CDF designs for highly contaminated sediments tend to
be more involved and costly to construct than an accept-
able brownfield site design. Although site-specific, an
upland clean-site CDF designed to contain highly con-
taminated sediments could entail several feet of com-
pacted clay, and one or more synthetic liners and leachate
collection systems. Generally, these green/clean-site
CDF design components would cover the entire base of
the facility. Such enhanced designs are premised upon
the need to isolate the contamination associated with
the sediments from the proximal environment and pre-
clude groundwater contamination. However, should a
contaminant release to ground water occur despite the
more-involved design, the resulting remediation effort
can entail significant and long-term expenditures. Lastly,
groundwater monitoring at a pristine CDF site needs to
be sufficiently sensitive to detect slight alterations in the
aqueous chemistry of the underlying aquifer. Such moni-
toring programs can entail significant costs through both
the operational and post-closure periods.
The environmental benefits associated with the con-
struction of a more-enhanced and costly clean/green
site CDF design at locations with significant LNAPL
accumulation, could be limited. At such sites, the addi-
tional expenditures required by the enhanced green-site
design components may only succeed in segregating
the /n-s/ftj/onsite contamination from the contamination
associated with the sediments. Specifically, the place-
ment of such a green-site design at the ECI site would
do little to remediate the underlying LNAPL contamina-
tion, and would leave the RCRA corrective action and
closure needs unaddressed. Should a more-costly green-
site CDF design be placed at the ECI site, a second
containment unit for the underlying onsite hydrocarbon
contamination could still be needed. If both the green-
site CDF and an underlying containment unit were con-
structed, these stacked containment units would perform
in a manner comparable to the current proposal.These
stacked units (with their duplicative design components)
would substantially increase the complexity and cost of
the project, while providing little additional environmen-
tal benefit.
61
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A review of the potential liability exposure associated
with use of the ECI site versus a clean site also raises
some interesting issues. Many of the liability issues
encountered are rooted in the current technical limita-
tions associated with the remediation of sites with NAPL
contamination. As discussed, the soils and ground water
at a pristine site used for CDF construction would need
to be kept pristine. Once constructed, should the more
involved green-site CDF design fail and a contaminant
release to the adjacent soils and ground water occur,
remediation would need to be initiated. This would in-
clude steps to correct the facility defect which caused/
allowed the release, as well as the remediation of any
impacted soils and ground water. Such a green-site
event could represent significant liability exposure, as
standard groundwater cleanup approaches tend to be
long-term and costly. In contrast and as acknowledged
by USEPA, the probable remediation scenarios at a
NAPL site such as ECI can be much more limited (5,7).
Unfortunately, at ECI the same LNAPL contamination
which the slurry wall will be placed to contain also exists
in abundance on the exterior of the slurry wall. As the
characteristics of the contamination outside as well as
Isolated by the slurry wall are similar, the same remedial
limitations associated with the in-situ contamination un-
derlying the CDF (once constructed) would also gener-
ally apply to the contamination beyond the CDF boundary.
These remedial limitations would not be altered by a
short-term release from the CDF. Consequently, in the
event of a release from the proposed CDF, an argument
could be made that the required remedial steps should
focus upon correcting the facility defect which allowed
the release to occur. In addition it should also be noted
that the ECI site is located in an area where the prob-
lems associated with LNAPL contamination are well
documented. Due to the widespread nature of the prob-
lem, Agency representatives and local property owners
are attempting to address the issue from a regional
perspective.
Traditionally, under many waste disposal programs, (e.g.,
TSCA, RCRA-Subtitle C, RCRA-Subtitle D), the perfor-
mance of the waste disposal unit is monitored through
the periodic assessment of the adjacent groundwater
quality down-gradient of the unit's perimeter. The detec-
tion of or an increase in the concentration of a contami-
nant known to be associated with the waste in the
disposal unit, is generally viewed as an indication of unit
failure. This definition of failure presumes a notable
difference in the chemical nature and/or concentration of
contaminants associated with the material in the unit
versus the material along the unit's exterior. However,
these prerequisites may not exist at the ECI site. Due to
the similarities between the IHC sediment and onsite
contamination, and the extensive and problematic na-
ture of the onsite contamination (LNAPLs); monitoring
the performance of the proposed CDF through alter-
ations In the quality of the groundwater adjacent to the
facility may not be feasible. In essence, the nature and
extent of the contamination within the unit may be little
different from the contamination along the unit's exterior.
Although groundwater samples could be collected and
alterations in the level of chemical constituents would no
doubt be measured, these alterations may involve sig-
nificant interpretational challenges and have little to do
with the performance of the CDF. Properly constructed
and operated, measured alterations in groundwater qual-
ity are at least as likely to reflect events which occurred
on the CDF's exterior than an indication of contaminant
migration from the facility interior. Since it seems prob-
able that water quality monitoring along the facility pe-
rimeter would provide little direct indication of unit
performance, facility performance monitoring may need
to rely primarily upon monitoring the hydraulic gradient
across the slurry wall. The hydraulic gradient would be
monitored by tracking the hydraulic head values on both
the interior and exterior sides of the vertical slurry wall.
As long as the hydraulic head value (groundwater lev-
els) along the exterior of the facility exceeded the hy-
draulic head value along the adjacent facility interior, the
flow of groundwater would be directed toward the inte-
rior of that portion of the CDF.
Application to Sediment Remediation
Projects
Contaminated sediments have been identified as a sig-
nificant non-point source of pollution in many rivers,
harbors and lakes. Contaminated sediments have been
positively linked to elevated levels of contaminants in
fish, degraded water quality conditions, and waterway
use limitations. At all of the 43 Areas of Concern (AOCs)
in the Great Lakes identified under the Great Lakes
Water Quality Agreement between the U.S. and Canada,
contaminated sediments have been associated with a
number of use impairments. The remediation of con-
taminated sediments is also an integral part of the
Remedial Action Plans at many of these AOCs, and is
the focus of numerous remedial activities under
Superfund and other cleanup authorities.
There are several prerequisites which must be met to
initiate the remediation of contaminated sediments. First
and most critically, a source of funding must be identi-
fied. This has resulted in a number of projects where
enforcement cases were brought against responsible
parties with the ability to fund sediment cleanups (e.g.,
Waukegan Harbor-OMC; Black River-USX Kobe; Indi-
ana Harbor-LTV Steel). Unfortunately, the sediment con-
tamination at most sites commonly originated from a
variety of point and non-point sources. This can make it
difficult to assign responsibility, and require a substantial
effort to build a sediment enforcement case. Although
rarely seen as the sole funding source, public funding
(federal or state) has also been used to augment or
match funding provided by the responsible party.
In addition to funding, sediment remediation projects
that involve removal (dredging) invariably entail access
and use of a piece of property. Ideally, the site is
adjacent to the area to be dredged, minimizing logistical
costs and difficulties. Where the volume of sediments
removed is small, and ultimate disposal is to an existing
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disposal facility (not uncommonly a commercial landfill),
the property is needed to conduct sediment dewatering
and rehandling (e.g., Cedar Creek-Tecumseh; Manistique
River-Manistique Paper). For projects with large sedi-
ment volumes, where commercial facilities are unavail-
able or cost prohibitive, the property is also needed for
CDF construction (e.g., Waukegan Harbor-OMC; Black
River-USX Kobe; Sheboygan River-Tecumseh).
As exhibited by the discussion above, the prerequisites
needed for navigation dredging and sediment remediation
can exhibit considerable overlap. Both require a propo-
nent (i.e., local sponsor or responsible party) armed with
sufficient funds, and access to a suitably placed and
appropriately sized piece of property. For a navigation
project, the proponent must provide all the property and
a portion of the funding, although the federal govern-
ment provides the larger share of the construction costs.
For an enforcement-based sediment remediation project,
the proponent(s) may be responsible for all or part of
these requirements. The primary need for brownfield
restoration is an investor willing to work with the site
owner and the appropriate agencies to review and ap-
prove an acceptable restoration plan for the property. In
the case of a remedial CDF constructed for sediment
cleanup, the required investor could consist of the PRP(s)
liable for the contamination, or a partnership consisting
of the PRP(s) and the brownfield site owner.The PRP(s)
in turn would acquire use or access of a suitably sized
and located brownfield site at minimal cost, while the
site owner would have a site-use scenario identified
which would address at least a portion of the site's
remedial needs.
s-
Conclusions
The considerations outlined above are not unique to the
USAGE project at Indiana Harbor or the ECI site. The
approach outlined in this paper preferentially selects
highly contaminated brownfield sites where containment
is a preferred remedial option for the construction of
sediment disposal facilities. Such brownfield sites adja-
cent or proximal to a federal navigation channel in need
of dredging should prove much more common than
proximal, clean, and sufficiently sized upland sites. In
contrast to the owners of clean upland sites, the owners
of a contaminated brownfield may welcome local spon-
sor status and may prove willing to not only provide the
needed property, but also help finance a CDF project
which would utilize their idle site as well as address at
least a portion of the site's environmental/remedial needs.
Should the future performance of the CDF prove inad-
equate, it is likely that the costs to upgrade the CDF and/
or remediate any resultant environmental contamination
would be shared by the local sponsor(s) and other
involved parties. A brownfield CDF, coupling the over-
lapping remedial and engineering aspects into the de-
sign and addressing the underlying in-situ soil and
groundwater contamination can be simpler and less
costly than a green-site design. Arguments can also be
made that such remedial CDFs can represent less fu-
ture liability than a comparable facility constructed at an
uncontaminated upland site. As discussed in this paper,
the selection of a site adjacent to the federal project also
minimizes logistical expenditures and eliminates any
associated public relations problems. The. inherent re-
medial aspects of the CDF design should also help to
enhance overall public acceptance for the project.Should
this approach prove generically feasible, long-delayed
dredging projects could be initiated removing large vol-
umes of contaminated sediments from ecologically sen-
sitive near shore channels and harbors, and idle
brownfield sites could be addressed and utilized. This
same approach may also be applicable to the remediation
of contaminated sediment sites.
References
1. Richardson G.N., D.M. Petrovski, R.C. Chaney,
and K.R. Demars, 1995. State of the Art: CDF
Containment Pathway Control, from Dredging,
Remediation and Containment of Contaminated
Sediments, ASTM, STP 1293, ASTM publication
code number 04-012930-38.
2. USAGE, June 1992. Hazardous, Toxic, and Ra-
dioactive Waste (HTRW) Guidance for Civil Works,
ER 1165-2-132
3. USAGE, February 1986. Draft Environmental Im-
pact Statement, Indiana Harbor Confined Dis-
posal Facility and Maintenance Dredging, Lake
County, Indiana.
4. U.S. EPA, January 1996. Basic Brownfields,U.S.
EPA Region 5 Fact Sheet Publication
5. U.S. EPA, September 1993. Interim Final Guid-
ance for Evaluating the Technical Impracticability
of Water Restoration, EPA/540-R-93-080
6. Mercer J.W. and R.M. Cohen, 1990. A review of
Immiscible Fluids in the Subsurface: Properties,
Models, Characterization and Remediation. Jour-
nal of Contaminant Hydrology, 6, pp. 107-163.
7. U.S. EPA, 1996b, Pump-and-Treat Ground-Water
Remediation, A Guide for Decision Makers and
Practitioners, EPA/625/R-95/005, July 1996.
8. Levorsen A.I., 1967. Geology of Petroleum, 2nd
Edition, p 461
9. Fetter C.W., 1993. Contaminant Hydrogeology
10. Domenico P.A. and F.W. Schwartz, 1990. Physi-
cal and Chemical Hydrogeology
11. RumerR.R. and J.K.Mitchell, editors, 1995, Chap-
ter 11. Assessment of Barrier Containment Tech-
nologies/A Comprehensive Treatment for Envi-
ronmental Remediation Applications; U.S. DOE/
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U.S. EPA/DuPont Company, product of an Inter- 13.
national Containment Technology Workshop in
Baltimore, Maryland, August 29-31,1995.
12. USAGE, 1995. Letter Report and Draft Environ- 14.
mental Impact Statement, Maintenance Dredging
and Disposal Activities, Indiana Harbor and Ca-
nal, Lake County, Indiana.
U.S. EPA, Region 5, 1977. Guidelines for the
Pollutional Classification of Great Lakes Harbor
Sediments.
USGS, 1997. Characterization of Fill Deposits in
the Calumet Region of Northwestern Indiana and
Northeastern Illinois, Water-Resources Investiga-
tions Report 96-4126
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Environmental Dredging and Disposal
Overview and Case Studies
Michael R. Palermo, Research Civil Engineer
U.S. Army Engineer Waterways Experiment Station (WES)
Vicksburg, MS
Norman R. Francingues, Chief,
Environmental Engineering Division, WES
Danny E. Averett, Chief,
Environmental Restoration Branch, WES
Abstract
Contaminated sediments are a nationwide problem, and
a wide range of remediation approaches have been
proposed for specific projects. Sediment removal or
"environmental dredging" is viewed by the public as the
most obvious alternative, and is being considered in
some of the most seriously contaminated areas. Envi-
ronmental dredging followed by treatment and disposal
of the contaminated material has been accomplished at
several Superfund sites. This paper summarizes techni-
cal considerations for environmental dredging and dis-
posal of contaminated sediments and presents case
studies of three recently completed projects.
Background
Sediments act as a sink for many contaminants, and
consequently, bottom sediments in many locations na-
tionwide have become polluted because of municipal
and industrial discharges and non-point sources. Op-
tions for remediating contaminated sediments include
no action, non-removal and removal. No action involves
simply allowing natural processes to gradually improve
conditions. Non-removal options are those which in-
volve restricted use of a contaminated area or treatment
or isolation of the contaminated sediments in place.
Removal options are those which involve environmental
dredging followed by treatment or disposal of the sedi-
ments at another location. If the decision is made to
remove the sediments, the environmental dredging op-
eration cannot be considered as a separate activity. The
dredging operation and the subsequent disposal and
management of the removed sediments must be com-
patible.
In recent years, the U.S. Environmental Protection
Agency (USEPA), the U.S. Army Corps of Engineers
(USAGE), and others have published a wealth of infor-
mation on contaminated sediment remediation (1 thru
14). Environmental dredging, sediment treatment, dis-
posal options, and a wide range of other related topics
have been described at varying levels of detail from
citizen's guides to technical guidance for designers.
These publications are a resource for acquiring more
detailed information.
Environmental Dredging
Dredging for cleanup purposes has been considered for
some time as a primary means for managing contami-
nated sediments (15, 16). Guidance for selection of
dredging equipment and advantages and limitations of
various types of dredges in the navigation dredging
context is available (17), and this information is gener-
ally applicable in the context of environmental dredging.
However, resuspension of sediment and associated re-
lease of contaminants and removal precision are key
environmental concerns when dealing with contami-
nated sediments.
All dredges resuspend some sediment during the dredg-
ing process. Some contaminants in the dissolved form
and some contaminants associated with resuspended
particles will be released and transported away from the
dredging site. Removal precision refers to how accu-
rately a given dredge can remove desired areas and
thicknesses of contaminated sediment. Precision is im-
portant from the standpoint of removing the contami-
nated material layers while leaving behind as little residual
contamination as possible. Also, precision is critical from
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the standpoint of not removing excessive amounts of
clean sediment, since any sediments removed would
likely be treated as contaminated material with the asso-
ciated high cost of disposal and management.
Research supplemented by field demonstrations has
resulted in general guidance for selection of equipment
and techniques for dredging contaminated sediments
(11,18,19, 20, 21, 22). Much can be done to limit sedi-
ment resuspension from conventional dredges without
substantial impact upon the efficiency of the dredging
operation. Precautions in operation and/or minor plant
modifications can be made with only a small increase in
cost In general, pipeline cutterhead dredges and hop-
per dredges without overflow generate less resuspended
sediment than clamshell dredges or hopper dredges
with overflow. It should be recognized, however, that
other factors such as maneuverability requirements,
hydrodynamic conditions, and location of the disposal
site may dictate the type of dredge that must be used.
The strategy then must be to minimize the resuspension
levels generated by any specific dredge type. If conven-
tional dredges are unacceptable, a special purpose
dredge may be required. These dredges generally re-
suspend less material than conventional dredges, but
associated costs may be much greater. As in the case of
conventional dredges, the selection of a special purpose
dredge will likely be dictated by site-specific conditions,
economics, and availability.
Treatment and Disposal Alternatives
Environmental dredging involves removal of contami-
nated sediment from a water body. What to do with this
dredged material, i.e. what disposal or management
option is appropriate or acceptable, is a major consider-
ation for any cleanup project.
A large number of options for dredging, placement of
sediments, treatment processes, and control measures
are available. The resulting range of possible alterna-
tives or scenarios is therefore potentially large. Any
strategy for evaluation of treatment and disposal options
must be technically sound, consistent, and compatible
with applicable laws and regulations (23).
The basic approaches for management and disposal of
material removed by environmental dredging include
containment, treatment, or combinations. Containment
refers to the placement and management of a material
at a site such that the contaminants are isolated from the
environment. Examples include subaqueous capping,
confined (diked) disposal facilities (CDFs), or disposal in
licensed landfills. Treatment refers to processes which
destroy, detoxify, or immobilize the contaminants. Pre-
treatment may be required prior to sediment treatment
and disposal and refers to processes such as solids
separation or dewatering which might be required for a
sediment treatment process to be effective. There are
many potential sediment treatment processes, and these
generally are categorized as biological, chemical, ex-
traction, immobilization, or thermal. Usually, several pre-
treatment and treatment process must be used in se-
quence, forming a "treatment train" to achieve a desired
result. Both untreated and treated material must ulti-
mately be disposed of, and options include CDFs, land-
fills, subaqueous capping and beneficial use (if the
treatment results in a material acceptable for a given
use).
The following three case studies illustrate some of the
principal technical considerations and lessons learned
in recent projects involving environmental dredging and
disposal.
New Bedford Harbor Hot Spot Case Study
The New Bedford Harbor Superfund site is located in
New Bedford, MA, south of Boston. Sediments through-
out the harbor are contaminated with polychlorinated
biphenyls (PCBs) and heavy metals as a result of dis-
charges from industries that operated along the water-
front. The harbor has been the focus of intensive study
since the late 1970s. This case study is summarized
from Otis (24).
The site is divided into three geographical study areas:
the hot spot area, the Acushnet River Estuary, and the
Lower Harbor and Upper Buzzards Bay. This summary
focuses on the hot spot remediation. The hot spot is a
20,200 square meter area located along the western
bank of the Acushnet River Estuary, directly adjacent to
an electrical capacitor manufacturing facility that was
the major source of PCB discharges to the harbor. The
hot spot is defined as those areas where the sediment
PCB concentration is 9000 parts per million (ppm) or
greater. Concentrations to over 100,000 ppm have been
detected in this area. Contamination at these levels is
found in the top 0.6 meters of sediment and extends to a
depth of 1.2 meters in several areas. In addition to
PCBs, heavy metals (notably cadmium, chromium, cop-
per, and lead) are found in the sediment. The volume of
sediment to be removed from the hot spot was originally
estimated at approximately 7,650 cubic meters and
contained approximately 45% of the total PCB mass in
sediment from the entire site.
The remedy selected by EPA consisted of the following
components: 1) removal using a small hydraulic pipeline
dredge, 2) disposal and dewatering of the sediments in
a CDF with treatment of the water prior to discharge
back into the harbor, 3) incineration of the sediments
with disposal of the ash in the CDF, and 4) capping of
the CDF.
Several studies evaluating dredging as a means of
removing the contaminated sediments from the harbor
were performed, including a full-scale field Pilot Study in
the estuary area which involved the onsite evaluation of
three hydraulic dredges. Site specific dredging proce-
dures were developed during the Pilot Study that re-
sulted in the removal of the contaminated sediments
while minimizing the resuspension of sediments.
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A confined disposal facility (CDF) had been constructed
along the New Bedford shoreline to contain the contami-
nated sediments removed during the Pilot Study. The
facility was modified and used again during the hot spot
remedial action. The modifications included dividing the
facility into three cells to facilitate the water treatment
process, installation of a high density polyethylene
geomembrane liner and installation of a floating coyer
over the large cell into which the dredged material was
initially pumped to control volatilization.
Construction activity began in August 1993 with modifi-
cations to the CDF and construction of the water treat-
ment facility. Ongoing community opposition to the
incineration component of the project resulted in con-
struction delays and eventually led to the elimination of
this phase of the project. Dredging began in April 1994.
The contractor used an Ellicott Model 370 dredge with
the sediments being pumped from the hot spot to the
CDF through approximately 1.6 kilometers of floating
pipeline. Silt curtains and oil booms were installed around
the dredge prior to the start of operations.
Once dredging began, It quickly became apparent the
production rate on which the contract was based could
not be sustained. Dredging operations brought a layer of
PCB oils to the surface which resulted in elevated levels
of volatilized RGBs in the air. Dredging procedures and
equipment were modified to minimize the oil releases.
These included reducing the dredge's swing speed,
fabricating a shroud to catch oil as it was released, and
using multiple swings of the dredgehead to remove a lift
of material prior to advancing the dredge. Silt curtains
were removed because they appeared to be contribut-
ing to the oil problem by their continuous disturbance of
the bottom in the varying tidal and weather conditions.
With these modifications, the dredging effort proved
successful in removing contaminated sediments. There
were no problems with sediment resuspension or con-
taminant release in the water column.
The operation of the CDF was largely successful. The
effluent discharged during filling operations was con-
trolled by addition of flocculents for enhanced suspended
solids removal and treatment using UV oxidation. The
removal of the hot spot material was completed in
September 1995, with a total volume of 15,000 cubic
yards of material placed in the CDF. Following elimina-
tion of incineration as a treatment option, EPA initiated
treatability studies which are now nearing completion.
The material currently remains in the CDF awaiting, a
final decision on treatment.
The major lessons learned from the New Bedford expe-
rience were related to the levels of release of PCBs
during the dredging process, which proved to be much
higher than anticipated. The hot spot sediments had
such high concentrations of PCB that they exhibited a
non-aqueous or oil-like phase which was easily released
as a floating sheen and exhibited a high volatilization
rate. This problem greatly affected the dredge produc-
tion, resulting in a much slower removal rate than antici-
pated. Contaminant release pathways other than sedi-
ment resuspension (such as release of oil phases or
volatilization) must be carefully considered when dredg-
ing highly contaminated sediments.
Marathon Battery Case Study
The Marathon Battery Project involved cleanup of a
Superfund site located in the Village of Cold Spring, NY,
located upstream of New York City on the Hudson River.
Marathon Battery produced nickel-cadmium batteries
for the military and for commercial use from 1952 until
1979 (25). During its operation, wastewater was dis-
charged into the Hudson River and into cove and marsh
areas hydraulically connected to the Hudson, contami-
nating sediments in these areas with cadmium, nickel,
and cobalt. The site was placed on the National Priori-
ties List in 1981. Remedial investigations and feasibility
studies culminated in a plan to dredge the top one foot of
sediment to achieve 10 ppm residual cadmium in sedi-
ments in the cove and achieving an action level of 100
ppm cadmium in the marsh. Attaining the marsh action
level required excavation of 12 to 42 inches of sediment
(26). After dredging and excavation, the ROD specified
that sediments would be dewatered, chemically fixed,
and transported to an offsite disposal area.
Remedial design for the Marathon Battery remedial
action was originally performed by the USAGE through
an interagency agreement with the USEPA. The original
design concept involved constructing an earthen berm
around the marsh and flooding the marsh, hydraulic
dredging of the contaminated sediments from the marsh
with cadmium-concentrations greater than 100 milli-
grams per kilogram (mg/kg), thickening of the dredged
sediments, chemical fixation of the thickened sediments,
truck transport of the fixated sediments to a local sani-
tary landfill, and restoration of the marsh. As the design
progressed, it was determined that the bermed marsh
would also be used to dewater dredged sediments from
East Foundry Cove and the Hqdson River (25 ,27).
As part of the design, scientists and engineers from the
USAGE, USEPA, and Malcolm Pirnie convened for a
five-day value engineering session to evaluate the
remediation plan specified in the ROD. This is believed
to be the first application of value engineering to a
hazardous waste project. More than 60 variations on
techniques to remediate the site were formulated, and
then evaluated and scored with regard to technical
feasibility and cost. The alternatives were narrowed
down to three concepts that were to be implemented,
including: 1) using amphibious equipment rather than
traditional hydraulic dredging to remove marsh sedi-
ments, 2) reusing clean berm material as an integral part
of the final marsh restoration rather than trucking in new
fill, and 3) restoring the wetland as a more ecologically
valuable "low marsh" rather than a "high marsh," reduc-
ing the extent of fill operations.
After the project had been advertised for a construction
contract, the principal responsible parties (PRPs) agreed
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with the U.S. District Court to perform the remedial
action in accordance with the RODs and the construc-
tion plans and specifications developed by the USAGE.
Cleanup activities began in 1993 and were substantially
complete in 1995 (27). Value engineering proposals
were made by the PRP contractor modifying some of the
original design concepts. These included: 1) dewatering
by mechanical methods vs. containment/settling basins,
2) use of a water-filled containment structure vs. an
earth containment dike, and 3) use of a proprietary
chemical stabilization process vs. the generic solidifica-
tion mix presented in the contract documents.
Sediments in shallow, open-water areas (coves/ponds),
were removed using a small hydraulic, horizontal auger,
dredge operated by Aqua Dredge, Inc. The 8-ft wide
auger was reported to be capable of a vertical precision
control of 0.1 inch (27). Low tides limited daily produc-
tion times for the dredge, but during optimum conditions,
a production rate of 1000 cu yds per day was reported.
Dredged material from the hydraulic dredge was initially
piped directly to the pre-treatment/dewatering process.
Some areas of the site were obstructed with rocks,
debris, and other physical limitations to the small hy-
draulic dredge. These areas were excavated with a
clamshell bucket and transported by scow to an off-
loading area prior to treatment. Marsh areas of the site
were excavated using low ground pressure amphibious
excavating equipment with hoppers for transport to the
treatment facilities. Project plans called for removing
approximately 52,000 cu yds from the cove and pond
areas, 10,000 cu yds from pier areas, and 14,000 cu yds
from the marsh (27).
The treatment and disposal process for the dredged
material consisted of dewatering, solidification/stabiliza-
tion, and transport by rail to a landfill in Michigan. The
PRP contractor originally chose a mechanical dewater-
ing system consisting of screens and centrifuges. How-
ever, the dewatering system did not perform as expected.
The variability of the physical characteristics of the
dredged material, rocks, wood, and vegetation, plugged
the coarser screens, and the fine silts and clays blinded
the finer screens and overloaded the centrifuges (28).
To overcome these problems, the dewatering system
was modified to include settling ponds prior to the me-
chanical dewatering system (consistent with the original
design) to equalize the feed and remove debris. Settled
solids were excavated mechanically from the ponds and
stockpiled into a paved staging area to await further
dewatering using belt filter presses. Excess water from
the dredging operation was treated with a polymer and
filtered through a sand filter prior to release to the
waterway. Dewatered solids were stabilized using the
proprietary Maectite process to pass leachate testing,
loaded onto rail cars, and transported to an offsite
landfill in Michigan (27).
One important lesson learned can be drawn from the
Marathon Battery experience. Conventional waste water
treatment trains are not easily adapted to treatment of
sediment pumped directly to the treatment train by hy-
draulic dredges. Variability of the material to include
changing water content, grain size, presence of debris,
etc. presents substantial difficulty with respect to materi-
als handling and tends to reduce the efficiency of treat-
ment process components designed for a more uniform
"feed". Conventional settling basins (essentially CDFs)
attenuate changes in the material characteristics as
dredging progresses and can eliminate these problems.
Bayou Bonfouca Case Study
Bayou Bonfouca is a Superfund project located in Slidell,
LA, approximately 45 miles northeast of New Orleans.
Region 6, USEPA and the USAGE New Orleans District
combined efforts to implement a remedial action. This
case study is summarized from Ives (29) and Sensebe
(30).
The site is an abandoned creosote wood treatment
facility located along a body of water known as Bayou
Bonfouca, and is adjacent to a very expensive residen-
tial area. The source of contamination is the former
American Creosote plant. The plant was constructed
around the turn of the century to create creosote pilings
and is located at the head of a Federal navigation
channel, which includes a small luxury boat marina. The
land site consists of approximately 50 acres of land
area. Over 160,000 cubic yards of sediment contami-
nated with creosote in Bayou Bonfouca were dredged.
The contractor for the site remediation was a joint ven-
ture between IT-Environmental and OH Materials, Inc.
The environmental dredging was subcontracted with
Bean Dredging Corporation.
The action level for cleanup was 100 mg/kg total poly-
nuclear aromatics (PNAs). The material to be dredged
and disposed were classified as silts and clays. Excava-
tion included both fine grain silty materials and stiff clays
which extend below the sedimentation in the bayou. The
cleanup operations included computerized mechanical
dredging from a floating platform, separation of debris,
slurry operations to pump the material using two Mudcat
dredges, dewatering using filter presses, incineration in
a portable rotary kiln, and final disposal of the incinerator
ash in an onsite secure (RCRA) double-lined, landfill. In
addition, there were five air monitoring stations around
the site.
The dredging/excavation was typically done between
8:00 a.m. to 5:00 p.m., Monday through Friday. A total of
164,246 cubic yards of sediment was removed. A new
dredge (Bonacavor) was designed and specially con-
structed for this site by Bean Dredging Corporation. It
consists of a floating plant, a five cubic yard, mechanical
bucket operated like a backhoe, and a large hopper/
screen where the dredged sediments/debris were
dumped. High-pressure fire hoses were used to wash
the sediment from the debris in the bar screen/(grizzly)
hopper. Precision dredging was required by the contract
with a strict penalty for overdepth dredging. The dredg-
ing was designed only to remove the layer of contami-
nated sediments with minor allowances for dredging
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accuracy. Actual tolerances achieved were within 6
inches and an average overdredge dimension of 0.17
feet. The excavation depth criteria set by the USEPA
were met or exceeded in all cases.
The screened, dredged sediments were pumped to a
holding pond (small CDF) where the water was sepa-
rated for treatment in a 500 gpm treatment plant consist-
ing of physical, chemical, and biological unit operations.
Lime was used in the wastewater treatment plant to
precipitate the solids. The settled solids were pumped
by two mudcat dredges to the conditioning and re-
handling (dewatering) facility. About 250 tons/day were
processed for feed as filter cake which is transported by
an enclosed conveyor belt to the rotary kiln, incinerator.
The incinerator trial burns were completed in November
1994, and the entire operation went online immediately
thereafter. The incinerator is required to meet destruc-
tion removal efficiencies (DREs) of four 9s. The ash has
to meet a PNA concentration less than 10 ppm. Any
material greater than 100 ppm PNA is sent to the
incinerator. The incineration of the material is scheduled
to be completed in 1997.
Lessons learned from Bayou Bonfouca are related to
the overall success of the operation. Use of a specially
designed dredge, with careful control during the opera-
tion, resulted in removal within tight tolerances, reducing
the amount of material to be treated. Although a com-
plex treatment train was involved, the overall design
accommodated separation of debris and variations in
the material characteristics.
Summary
Environmental dredging is a contaminated-sediment re-
medial option requiring removal of sediments from the
water body followed by treatment or disposal of the
sediments at another location. The dredging operation
and the subsequent disposal and management of the
removed sediments must be compatible. Control of sedi-
ment resuspension and removal precision are key envi-
ronmental concerns for the removal process. A large
number of options are available for management and
disposal of material removed by environmental dredging
including containment, treatment, or combinations. Op-
tions for ultimate disposal include CDFs, landfills, sub-
aqueous capping and beneficial use. Field experience
from completed projects will continue to yield valuable
information and lessons learned which can be applied to
future projects.
Acknowledgment
This paper summarizes investigations conducted under
various programs of the U. S. Army Corps of Engineers
and the U.S. Environmental Protection Agency. Permis-
sion to publish this material was granted by the Chief of
Engineers.
References
1. Averett, D.E., B.D. Perry, E.J. Torrey, and J.A.
Miller, 1990, "Review of Removal, Containment,
and Treatment Technologies for Remediation of
Contaminated Sediments in the Great Lakes,"
Miscellaneous Paper EL-90-25, U.S. Army Engi-
neer Waterways Experiment Station, Vicksburg,
MS.
2. Demars, K.R., G.N. Richardson, R.N. Yong, and
R.C. Chaney, (editors). 1995. Dredging,
Remediation, and Containment of Contaminated
Sediments, American Society of Testing and Ma-
terials (ASTM) Special Technical Publication 1293,
ASTM, Philadelphia, PA.
3. National Research Council, 1989, Contaminated
Marine Sediments—Assessment and Remediation,
Marine Board, National Research Council, Na-
tional Academy Press, Washington, DC.
4. National Research Council, 1997, Contaminated
Sediments in Ports and Waterways—Cleanup
Strategies and Technologies, Marine Board, Na-
tional Research Council, National Academy Press,
Washington, DC.
5. Permanent International Association of Naviga-
tion Congresses (PIANC). 1996. "Handling and
Treatment of Contaminated Dredged Material from
Ports and Inland Waterways—COM," Report of
Working Group No. 17 of the Permanent Techni-
cal Committee I, Supplement to Bulletin No. 89,
1996, Permanent International Association of Navi-
gation Congresses, Brussels, Belgium.
6. USACE/EPA, 1992, Evaluating Environmental Ef-
fects of Dredged Material Management Alterna-
tives—A Technical Framework,EPA842-B-92-QQ8,
U.S. Army Corps of Engineers and U.S. Environ-
mental Protection Agency, Washington, DC.
7. USEPA. 1991. Handbook—Remediation of Con-
taminated Sediments, EPA/625/6-91/028, Envi-
ronmental Protection Agency, Washington, D.C.
8. USEPA. 1993. Selecting Remediation Techniques
for Contaminated Sediment, EPA-823-B93-001,
Environmental Protection Agency, Washington,
D.C.
9. USEPA . 1993. "Risk Assessment and Modeling
Overview Document," EPA 905-R93-007, Assess-
ment and Remediation of Contaminated Sedi-
ments Program, Great Lakes National Program
Office, Chicago, Illinois.
10. USEPA. 1994a. Assessment Guidance Document,
EPA 905-R94-002, Assessment and Remediation
of Contaminated Sediments Program, .Great Lakes
National Program Office, Chicago, Illinois.
69
-------
11. USEPA. 1994b. Remediation Guidance Document,
EPA 905-R94-003, Assessment and Remediation
of Contaminated Sediments Program, Great Lakes
National Program Office, Chicago, Illinois.
12. USEPA. 1994c. Bench-scale Evaluation of Sedi-
ment Treatment Technologies: Summary Report,
EPA 905-R94-Q23, Assessment and Remediation
of Contaminated Sediments Program, Great Lakes
National Program Office, Chicago, Illinois.
13. USEPA. 1994. ERA'S Contaminated Sediment
Management Strategy, EPA 823-R-94-001, Office
of Water, U.S. Environmental Protection Agency,
Washington, D.C.
14. USEPA. 1995. Cleaning Up Contaminated Sedi-
ment—A Citizen's Guide, EPA 905-K-95-001, As-
sessment and Remediation of Contaminated Sedi-
ments Program, Great Lakes National Program
Office, Chicago, Illinois.
15. Engler, R.M., N.R. Francingues, and M.R. Palermo,
1991. "Managing Contaminated Sediments: Corps
of Engineers Posturing to Meet the Challenge,"
World Dredging and Marine Construction, August
1991.
16. Palermo, M.R., R.M. Engler, and N.R. Francingues,
1993, The U.S. Army Corps of Engineers Per-
spective on Environmental Dredging," Buffalo En-
vironmental Law Journal, Vol. 1, No. 2., Buffalo,
NY.
17. US ACE. 1983. Dredging and Dredged Material
Disposal, Engineer Manual 1110-2-5025,25 March
1983, Office, Chief of Engineers, Washington,
D.C.
18. Hayes, D. L 1986. "Guide to Selecting a Dredge
for Minimizing Resuspension of Sediment," Envi-
ronmental Effects of Dredging Technical Note
EEDP 09-1, U.S. Army Engineer Waterways Ex-
periment Station, Vicksburg,
19. Hayes, D. L. 1988. "A Preliminary Evaluation of
Contaminant Release at the Point of Dredging,"
Environmental Effects of Dredging Technical Note
EEDP-09-3, U.S. Army Engineer Waterways Ex-
periment Station, Vicksburg, MS.
20. Herbich, J.B., and S.B. Brahme, 1991. A Litera-
ture Review and Technical Evaluation of Sedi-
ment Resuspension During Dredging, Technical
Report (in preparation), US Army Engineer Water-
ways Experiment Station, Vicksburg, MS.
21. Palermo, M.R. 1991. "Equipment Choices for
Dredging Contaminated Sediments," Remediation,
Autumn 1991.
22. Palermo, M.R. and D.F. Hayes, 1992. "Environ-
mental Effects of Dredging," Vol. 3, Chapter 15 of
Handbook of Coastal and Ocean Engineering,
Gulf Publishing Company, Houston, Texas.
23. Palermo, M.R. and J.A. Miller, 1995. "Strategies
for Management of Contaminated Sediments," in
Dredging, Remediation, and Containment of Con-
taminated Sediments, edited by Demars, K.R.,
G.N. Richardson, R.N. Yong, and R.C. Chaney,
American Society of Testing and Materials (ASTM)
Special Technical Publication 1293, ASTM, Phila-
delphia, PA.
24. Otis, M.J. 1994. "New Bedford Harbor, Massachu-
setts Dredging/Disposal of PCB Contaminated
Sediments," Dredging 94—Proceedings of the
Second International Conference on Dredging and
Dredged Material Placement, American Society of
Civil Engineers, 1, 579-587.
25. Simmons, Thomas M., Gregory P. Matthews, and
Nick Multari. 1994. "Preparation of bid documents
for dredging/excavating contaminated sediments,
soils and marsh deposits at the Marathon Battery
Superfund Site Cold Spring, NY," Dredging 94—
Proceedings of the Second International Confer-
ence on Dredging and Dredged Material Place-
ment, American Society of Civil Engineers, 2,
1201-1209.
26. Nocera, John J., and Thomas M. Simmons. 1994.
"Development of an excavation plan for heavy
metal contaminated marsh deposits [for Marathon
Battery]," Dredging 94—Proceedings of the Sec-
ond International Conference on Dredging and
Dredged Material Placement, American Society of
Civil Engineers, 2, 1220-1229.
27. Taylor, Michael P., Pamela N. Tames, and Alan R.
Elia. 1994. "Marathon Battery Superfund Project—
a review of design, construction, and lessons
learned," Dredging 94—Proceedings of the Sec-
ond International Conference on Dredging and
Dredged Material Placement, American Society of
Civil Engineers, 2, 1210-1219.
28. Logigian, John M., Edward A. Dudek, and Michael
R. Palermo. 1994. "Design of dredge containment
and dewatering facilities [for Marathon Battery],"
Dredging 94—Proceedings of the Second Inter-
national Conference on Dredging and Dredged
Material Placement, American Society of Civil En-
gineers, 2, 1230-1239.
29. Ives, Pete, 1994. "Bayou Bonfouca," The Military
Engineer, No. 566.
30. Sensebe, Joe, 1994. "Bayou Bonfouca Superfund
Site, Slidell, Louisiana—An Overview," Proceed-
ings of the Southern States Annual Environmental
Conference Session on Federal Waste Cleanup
Experiences, Biloxi, Mississippi.
70
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Integrated Sediment Decontamination for the
New York/New Jersey Harbor
E. A. Stern
U.S. Environmental Protection Agency, Region 2, New York, NY
K. R. Donate
U.S. Army Corps of Engineers, New York District, New York, NY
N. L Clesceri
Rensselaer Polytechnic Institute, Troy, NY
K.W.Jones
U.S. Department of Energy, Brookhaven National Laboratory, Upton, NY
Abstract
Disposal of dredged material taken from the New York/
New Jersey (NY/NJ) Harbor is problematic because of
the presence of inorganic and organic contaminants that
under revised testing criteria render it unsuitable for
return to the ocean or for beneficial reuse. Decontami-
nation of the dredged material followed by beneficial
reuse is one attractive component of the comprehensive
dredged material management plan being developed by
the U.S. Army Corps of Engineers, New York District. A
demonstration program to validate decontamination pro-
cesses and to bring them into full-scale use in the NY/NJ
Harbor is now in progress. Tests of selected technolo-
gies have been completed at the bench-scale and pilot-
scale (2-15 m3) levels. Procedures for demonstration
testing on scales from 750 m3 to 75,000 m3 are being
developed with the goal of producing a usable decon-
tamination system by the end of 1999. The overall
project goals and present status of the project are
reviewed here.
Introduction
The Port of New York and New Jersey requires dredging
approximately 4,000,000 nf of sediment each year from
navigational channels and from many different types of
public and private berthing areas. At this time the frac-
tion of dredged material that can be disposed of in the
coastal Atlantic Ocean at the Historic Area Remediation
Site (HARS) represents perhaps 25% of the total. Other
disposal options must be chosen for the bulk of the
material. One option or component to dredged material
management is to decontaminate the sediments and put
the treated material to a beneficial reuse (1).
The cleanup goal is clearly achievable from a purely
technical standpoint and has already been demonstrated
in many soil remediation projects. However, in the Port
there are additional factors to consider in the actual
creation of a decontamination processing option. The
facility must be large enough for handling and stockpil-
ing an enormous amount of material (some fraction of
the total yearly dredging volume) that arrives at highly
irregular time intervals throughout the year, and it must
do so with a treatment cost which can be borne by the
various customers in the Port. The minimal costs for
dredging followed by unrestricted ocean disposal can be
in the range from $6 to $12 per m3. Additional costs that
can be borne presently by the larger of the Port custom-
ers are estimated to be no more than $35 per nf. A cost
decrease is needed to keep the Port viable and competi-
tive for the future. Thus, there is a strong impetus for the
development of beneficial reuses which can generate a
revenue stream that can be combined with a tipping fee
of the magnitude just mentioned to give the foundation
for an economically viable business.
In addition, there is need for substantial capital funding
for decontamination infrastructure construction. The larg-
est volume of dredged material is generated by the U.S.
Army Corps of Engineers and the Port Authority of New
York/New Jersey. Under present contract procedures, it
is impossible to provide assurances of long-term streams
of materials to a vendor and/or facility capable of decon-
taminating the dredged material. This makes the devel-
opment of a business difficult using private funding
alone since the risks to potential investors is very high.
Thus, in the long term, the use of innovative public-
private partnership arrangements may be necessary at
the inception of individual enterprises.
71
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The purpose of this report is to summarise, from a
technical and practical standpoint alone, the work that is
in progress in the Harbor of New York and New Jersey,
as called for under the Water Resources Development
Acts (WRDA) of 1992 and 1996. This project is aimed at
development and construction of a large-scale decon-
tamination facility as part of a stable long-term solution
to the handling of dredged material in the region. Earlier
summaries have been given by Stern et al. (2) and
Jones et al. (3). Cost considerations will be presented
elsewhere (4).
Project Components
There are many components contained in a project
designed to produce an operating facility for dredged
material processing and decontamination. There are
also many different research, university, and industrial
sector institutions working on tasks that relate to the
needs of the project. However, in general, there is no
pathway for coordinating and integrating the data and
results produced into a systems package that is useful
for meeting specific decontamination goals for a range
of sediment contaminants. As a result, the present work
has components that span a range of research and
development activities from relatively basic science to
applied engineering and business activities. Some of the
key components that are needed in producing an opera-
tional treatment facility are:
* Treatment train development
* Selection and testing of treatment technolo-
gies
* Pretreatment (physical separation/dewater-
ing)
» Facility siting
• Facility design and construction
* Technology and facility permitting
• Fundamentals
• Sediment toxicity identification evaluations
• Toxicity testing of post-treated material
• 3-D visualization of contaminant distributions
to assist in making dredging decisions
* Environmental and human health risk as-
sessment. This includes risks from the mate-
rial and from operation of the decontamina-
tion procedures.
• End-use criteria. How clean is clean?
• Operational requirements
Public outreach
Business development for beneficial reuse
products
Develop cost- and profit-sharing public-pri-
vate partnerships for operation of the facility
Characteristics of NY/NJ Harbor Dredged
Material
The physical characteristics of the sediments found in
the Port are generally very fine-grained silts and clays
(80-95%) with a small fraction of larger grain sizes and
large-size debris. The total organic content of Harbor
sediments ranges from 3-10%. The bulk material has
the consistency of a black mayonnaise or gel. The solids
content of the dredged material is 30% to 40% when
obtained using a conventional clam-shell bucket dredge.
The NY/NJ Harbor estuarine salinity ranges from 1.5 to
28 parts per thousand. The concentrations of major
contaminants and metals found in dredged material
from Newtown Creek, NY, are shown in Table 1. This is
of interest in considering possible pathways for benefi-
cial reuse as manufactured soil, cement, or glass.
Inorganic contaminants include heavy metals such as
cadmium, mercury, lead, arsenic, and chromium. Or-
ganic compounds include dioxins and furans, polychlori-
nated biphenyls (PCBs), polynuclear aromatic
hydrocarbons (PAHs), petroleum hydrocarbons, and chlo-
rinated pesticides and herbicides. Generally, the mate-
rial is chemically stable and is found to pass the toxicity
characteristic leaching program (TCLP) for testing the
teachability of contaminants. The concentrations found
in Newton Creek sediments are not high enough to
warrant classification as hazardous materials, but are
sufficient to cause them to fail bioaccumulation and
toxicity tests required prior to ocean disposal and speci-
fications for soil cleanup levels in New York and New
Jersey. Contaminant concentrations found in Newtown
Creek, NY, and in Port Newark, NJ, sediments are also
compared to several soil criteria for the States of New
York and New Jersey in Table 1. These chemicals are
characteristic of a historically used, heavily industrial-
ized urban port.
Results of Bench- and Pilot-scale Testing
Programs
Technologies that have been tested have fallen into
those that are carried out (1) at ambient or at least low
temperatures, (2) intermediate temperatures that do not
destroy the organic constituents, and (3) high tempera-
tures above the decomposition point of the organic
compounds. The wide variety of contaminants and dif-
fering concentration levels make it plausible to search
for technologies that can be applied to specific concen-
tration levels. In addition, the low-temperature technolo-
gies may be more acceptable to the local and regulatory
communities and they may be easier to permit. The
72
-------
Table 1. Contaminant Concentrations of Untreated As-Dredged NY/NJ Harbor Sediments (Dry Weight)
Contaminant
2,3,7,8 TCDD (ppt)
OCDD (ppt)
TCDD/TCDF TEQ (ppt)
Newtown
Creek
(Bench)
42
17,463
518
Newtown
Creek
(Pilot)
81
38,881
1570
Port
Newark
66
5560
109
NJ
Non- NJ
Resid.1 Resid.2
— —
— — ;
NY
Resid.3
—
—
—
Total PCBs (ppm)4
1.55
1.78
0.141
0.49
Anthracene (ppb)
Benzo(a)anthracene (ppb)
Chrysene (ppb)
3702
4484
4564
Total PAHs (ppb)4 113,000
Arsenic (ppm)
Cadmium (ppm)
Chromium (ppm)
Copper (ppm)
Lead (ppm)
Mercury (ppm) total
Zinc (ppm)
1 NJ Department of Environmental
2 NJ Department of Environmental
3 NY Department of Environmental
4 See Reference 1 2.
5 n/a = not available.
6 SB = Site background.
33
37
376
1171
617
1.3
1725
1074
8970
9973
130,000
42
47
432
1410
631
3.7
2070
Protection. Non-residential soil,
Protection. Residential soil, dire
Conservation. Recommended :
167
283
365
30,000
15
6
171
212
300
2.2
526
direct contact. J.J.
10,000
4000
40,000
—
20
100
—
600
600
270
1500
A n 7-?RD
set contact. J.J.A.C. 7:26D, revi
soil cleanup objectives. HWR-9
10,000
900
9000
n/a5
20
1
—
600
400
14
1500
revised 7/1 1/96.
sed 7/1 1/96.
4-046 (Revised).
50,000
224
400
396,500
7.5
1
10
25
SB6
0.1 •
20
January 24, 1994.
higher temperature technologies may be more appli-
cable to the most contaminated sediments that are
found outside of navigational channel and depositional
areas. These areas may lend themselves to "Hot Spot"
remediation. High temperature technologies may well
produce beneficial use products that have higher resale
values. Examples of the technologies that fit each sedi-
ment contamination category are:
Low contamination. Solidification/stabilization,
manufactured soil, and phytoremediation. U.S.
Army Corps of Engineers (5)
Low-to-medium contamination. Sediment wash-
ing and chemical extraction. BioGenesis Enter-
prises Inc. (6)
Medium contamination. Solvent Extraction. Metcalf
& Eddy, Inc. (7)
High contamination. High-temperature rotary kiln.
Institute of Gas Technology (8)
High contamination. High-temperature plasma
torch. Westinghouse Electric Corporation, Science
& Technology Center (9)
Taken together these technologies form the basis of an
integrated "treatment train" for the management of con-
taminated dredged material from the Port of NY/NJ or
other locations worldwide.
U.S. Army Corps of Engineers
The simplest approach to decontamination is the prepa-
ration of a manufactured soil using dredged material.
The advantages of this method include relatively low
cost and easy implementation with no need for complex
capital equipment or dewatering of the material. The
disadvantages are that establishing growth of cover
plants may be difficult since degradation of some com-
pounds may be slow, and trophic transfer issues could
restrict use as a topsoil since removal of contaminants is
an in-situ process that proceeds slowly and needs long-
term monitoring.
The soil is produced by mixing the sediment with a
cellulose material such as wood chips, sawdust, or yard-
waste compost, cow manure or sewage sludge, and
lime and fertilizer as needed. Specific mixtures that were
tested contained dredged material, sawdust or yard
waste, and cow manure. The tests showed that the
optimum dredged material concentration was about 30%
of the soil mixture by weight, thus giving an overall
73
-------
reduction in contaminant concentrations through dilu-
tion. These concentrations are compared to New York
and New Jersey standards for residential and industrial
soil cleanup standards in Table 2. It was found that
some of the contaminant concentrations exceeded the
soil cleanup criteria. Hence, a decontamination proce-
dure may be advisable for producing a soil meeting state
standards. The suitability of the soil for growth of differ-
ent plant species was tested for tomato, marigold, rye
grass and vinca. The soil was most suitable for the
growth of rye grass.
BloGenesis
A schematic diagram of the sediment-washing equip-
ment of BioGenesis is shown in Figure 1. The first step
in the process is to use surfactants combined with a
water jet to break up agglomerates and solubilize hydro-
carbons coating the individual sediment grains. The
second step combines a chelating agent and high-
velocity water jet that further strip organic coatings from
the particles and remove metals sorbed to the base
materials. The water-solid mixture is then passed through
a cavitation-oxidation unit to break up the organic com-
ponents, followed by steps to separate the processed
solids from the water which contains the remains of the
contaminants. The water is processed to meet stan-
dards required for disposal at wastewater treatment
plants. The testing program to date has been confined to
study of the contaminant reduction efficiency. Results
obtained for reduction of PAHs and metals in one ex-
periment are shown in Table 3. These values are com-
pared to the standards for soil cleanup given by NY and
NJ. Similar values have been obtained for other con-
taminants.
The bench-scale experimental results indicate that it is
possible to expect reductions that exceed 90% in a
single pass through the apparatus. Results found from
sequential passes through the system have been en-
couraging and make it plausible to think that further
improvements in the system efficiency can be attained.
The next step would be testing on a pilot-scale level of
up to 1000 yd3. The final product can be combined with
the manufactured soil approach of the Corps of Engi-
neers to produce a material suitable for unrestricted use
as long as the dredged material contamination can be
reduced to acceptable levels consistent with those men-
tioned above.
Toblo 2. Summary of Results for U.S. Army Corps of Engineers Waterways Experiment Station Bench-scale Manufactured Soil
Demonstration: 30% Dredged Material, 50% Sawdust, 10% Cow Manure
Contaminant
2,3,7,8 TCDD(pp«)
OCDO {ppt}
TCDD/rCDF TEQ (ppt)
As Dredged
41.5
17463
518
Man. Soil
30% As
Dredged
15.2
5290
182
Percent NJ NJ NY
Reduction Non-Resid.1 Resid.2 Resid.3
63.4 —
69.7 —
64.9 — -- —
Total PCBs (ppm}«
1.22
0.782
68.0
0.49
Anthracene (poo)
Banzo(a)ar,thracene (ppb)
Chrysena (ppb)
Total PAHs (ppb)*
Arsenic (pom)
Cadmium (ppm)
Chromium (ppm)
Copper (ppm)
Lead (ppm)
Mercury (ppm) total
Zinc (ppm)
3700
4480
4560
57,900
33.5
3.0
377
1172
617
1.29
1725
1590
3130
3720
35,800
12.5
7.9
140
393
331
—
514
57.0
30.1
18.4
38.2
62.7
78.6
62.9
66.5
46.4
—
70.2
10,000
4
40
—
20
100
—
600
600
270
1500
10,000
900
9000
n/as
20
1
—
600
400
14
1500
50,000
224
400
396,500
7.5
1
10
25
SB8
0.1
20
1 NJ Department of Environmental Protection. Non-residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.
* NJ Department of Environmental Protection. Residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.
a NY Department of Environmental Conservation. Recommended soil cleanup objectives. HWR-94-046 (Revised). January 24,1994.
'See Reference 12.
*n/a« not available.
•SB » Site background.
74
-------
Vibrating screen to
separate oversized
material
• Chemicals
High pressure water
Delivery of dredged
material by barge
' Side stream—
oversized material
disposal
Pretreatment—
chemical and water
mixing
oam
Oxidant
T
Sediment washer
Organic treatment—
oxidation of organic
contaminants
~u
-Foanv-
Side stream—
skimming tank for floatable
organic contaminants
Collect data on treated
sediment and
contaminated water
Pretreatment for metals
and other contaminants
(precipitation)
a
Liquid/solid separation
process (dewatering)
Product stream—
treated sediment
Water to publicly owned
treatment works
Side stream
sludges to landfill
Figure 1. Schematic diagram showing the steps in the sediment washing and chemical extraction processing system developed by
BioGenesis Enterprises.
Metcalf& Eddy
Solvent extraction procedures are similar to the sedi-
ment washing process of BioGenesis in the sense that a
chemical solvent is used to remove the surface coatings
of contaminated materials. Removal of volume contami-
nation depends on the porosity of the material and the
treatment time as well as on the details of the chemical
interactions of the contaminants with the bulk material of
the sediment. A block diagram of the apparatus used by
Metcalf & Eddy is shown in Figure 2. The extraction
process operated at a temperature of 37.7-60.0°C and
employed isopropyl alcohol and isopropyl acetate as the
solvents. These conditions require more elaborate ap-
paratus than the BioGenesis process and require more
attention to operating conditions because of fire/explo-
sion hazards. Pilot-scale experiments were carried out
using multiple passes through the system and in a
continuous mode.-Results obtained for decontamination
are shown in Table 4 for a 5-cycle treatment. This
particular experiment did not use a chelator and the
metal levels are not substantially reduced.
75
-------
Tab!o 3, Summary ol BioGenesis Sediment-Washing Process
Contaminant
Anthracene (ppb)
Benzo(8)anthracene (ppb)
Chryssne (ppb)
Total PAHs (ppb)<
Arsenic (ppm)
Cadmium (ppm)
Chromium (ppm)
Coppar(ppm)
Lead (ppm)
Mercury (ppm) total
Zinc (ppm)
As-dredged
771
1793
1994
19,502
22.2
18.2
226
n/a5
454
13.1
—
Treated
177
234
286
3207
12.8
1.4
63
n/a5
60
0.3
n/a5
Percent
Reduction
77.0
86.9
85.7
83.6
42.3
92.3
72.1
—
86.8
97.7
—
NJ
Non-Resid.1
10,000
4000
40,000
—
20
100
—
600
600
270
1500
NJ
Resid.2
10,000
900
9000
n/a5
20
1
—
600
400
14
1500
NY
Resid.3
50,000
224
400
396,500
7.5
1
10
25
SB6
0.1
20
1 NJ Department of Environmental Protection. Non-residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.
f NJ Department of Environmental Protection. Residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.
1 NY Department of Environmental Conservation. Recommended soil cleanup objectives. HWR-94-046 (Revised). January 24,1994.
4 Sea Reference 12.
* n/a - not available.
•SB - Site background.
Raw sediment
WaSer decanting/
adjustment
screening
Recycle
filtered
fines and
washwater Is
recycled
Ffflura 2. Schematic diagram showing the Metcalf & Eddy solvent extraction process for treatment of dredged material.
The testing included production of stabilized materials
from both untreated and treated dredged material by
Metcalf & Eddy, Inc. and the U.S. Army Corps of Engi-
neers Waterways Experiment Station. The results are
summarized in Table 5. It can be seen that compressive
strengths of over 100 pounds per square inch can be
achieved. These values are comparable to values re-
ported by Tanal et al. (10) and Samtani et al. (11) for a
project carried out on dredged material from the Port of
Boston. Other relevant physical properties of the solidi-
fied and stabilized dredged material are also given in
Table 5.
76
-------
Institute Of Gas Technology Figure 3. The process requires adding common mineral
compounds to optimize the overall composition of the
The Institute of Gas Technology demonstrated the use material for pozzolan production. The technology em-
of a rotary kiln for the destruction of organic compounds ployed is that commonly in use at existing cement
and immobilization of metals in the cementitious struc- plants. This is encouraging since it means that existing
ture. A block diagram of the apparatus is shown in off-line facilities could possibly be devoted to processing
Table 4. Summary of Results for the Metcalf & Eddy Solvent Extraction Process
Contaminant
2,3,7,8 TCDD (ppt)
O ODD (ppt)
TCDD/TCDF TEQ (ppt)
Total PCBs (ppm)4
Anthracene (ppb)
Benzo(a)anthracene (ppb)
Chrysene (ppb)
Total PAHs (ppb)4
Arsenic (ppm)
Cadmium (ppm)
Chromium (ppm)
Copper (ppm)
Lead (ppm)
Mercury (ppm) total
Zinc (ppm)
As-dredged
35
13411
648
1.54
62,900
38490
33.76
858,000
68
29
319
1090
632
3.5
1505
1 NJ Department of Environmental Protection.
2 NJ Deoartment of Environmental Protection.
Treated
7-stage
10
3047
106
0.029
1292
894
1.01
17,000
85
32
373
1310
795
5,3
1750
Non-residential soil,
Residential soil, dire
Percent
Reduction
71
77
84
98.1
97.9
97.7
97.0
98.0
—
—
—
—
—
—
—
direct contact
ct contact J.I
NJ
Non-Resid.1
—
—
—
2
10,000
4000
40,000
—
20
100
—
600
600
270
1500
J J A C 7-26D
.A.C. 7:26D. revi:
NJ
Resid.2
—
—
—
0.49
10,000
900
9000
n/a5
20
1
—
600
400
1 14
1500
revised 7/1 1/96.
sed 7/1 1/96.
NY
Resid.3
—
—
—
1
50,000
224
400
396,500
7.5
1
10
25
SB6
0.1
20
3 NY Department of Environmental Conservation. Recommended soil cleanup objectives. HWR-94-046 (Revised). January 24,1994.
4 See Reference 12.
5 n/a = not available.
6SB = Site background.
Table 5. Results of Physical Testing of Solidification/Stabilization Products*
Metcalf & Eddy Treated Sediment
U.S. ACE-WES Screened As-Dredged Sediment
15%
USC in psi
Water Content at 60°C
Water Content at 100°C
Specific Gravity
Coefficient of Permeability-cm/sec
Dry Densisty in Ibs/ft3
Atterburg Limits
Liquid
Plastic
Slope Angle Degrees
Cement Mix
217
53.0
71.6
2.70
1.16E-06
51.6
103
59
— -
30% Cement Mix
614
26.9
53.7
2.69
4.15E-07
64.1
—
—
10% Cement Mix
29
60.7
70.3
2.53
1.42E-05
38.1
126
67
35.5
20% Cement Mix
128
27.7
5.4
2.61
5.46E-06
47.5
—
40% Cement Mix
492
18.1
32.1
2.63
3.12E-07
57.5
—
• — ' •
* All analytical data are based upon the average of all sample test results provided by U.S. ACE-WES.
77
-------
of dredged material. The results for contaminant reduc-
tion are shown in Table 6. There is essentially complete
destruction of organic compounds. The metals are re-
duced by dilution and by loss to the gaseous side-
stream. Moreover, the metal values are in the range
found for commercially available cements. Strength tests
have been carried out and show that the sediment-
derived product meets compressive strength standards.
Cement production is therefore a method that is suc-
cessful in reducing the contamination levels and pro-
vides an end product suitable for beneficial reuse.
Westinghouse
The Westinghouse Science and Technology Center dem-
onstrated the use of a plasma torch for destruction of
organic contaminants and immobilization of metals in a
glassy matrix. The plasma torch is an effective method
for heating sediments to temperatures higher than can
be achieved in a rotary kiln. On the other hand, feeding
of the material into the plasma region is more complex
since dewatering is necessary, and residence times in
the high temperature regions are difficult to adjust. A
schematic diagram of the Westinghouse apparatus is
shown in Figure 4. The results for contaminant reduction
are given in Table 7. The end goal of the processing is
not only to reduce contaminant concentrations, but, also
to produce a useful final product. In order to do this, the
overall composition of the treated material is optimized
for glass production. Glass tiles and fiber glass materials
were successfully produced during the pilot-scale test
work. Glass production can, therefore, be considered as
successful in reduction of contaminant levels and pro-
duction of a valuable end product.
5. Operational-Scale Program
As mandated under WRDA 1996, the end goal of the
testing program is to produce one or more production-
level demonstration facilities that can used as part of the
total solution for management of dredged material from
the harbor. Detailed engineering designs of plants for
the production of cement and glass are now in progress
and will be completed in early 1998. Construction of the
facilities may begin in 1998 with a prospective comple-
tion date prior to the next century. This schedule is
dependent on availability of funding from the private
sector. Demonstrations of the sediment-washing ap-
proach are planned for early 1998 and operation of a
large-scale demonstration facility by the end of 1998.
Conclusions
A short description has been given of the highlights of a
unique federal program for dredged material demon-
strating decontamination. This program began with tests
at the bench-scale level and will progress to a goal of
production-scale volumes of up to 375,000 nf utilizing a
"treatment train" approach. The breadth of the program
has been increased through cooperation with groups
who have carried on self-funded test programs. The
bench- and pilot-scale results described here demon-
strate that decontamination may be a viable method for
Modifiers
As-received
sediments
Gas-fired
Reactive
Melter
2400°-2500°F
Natural
gas
•air
Flue gas
quench
Gas cleanup
equipment
Clean
_ flue
gas
Additives
Economelt™
(glassy material with
cementitious properties)
High quality
blended cement
Figure 3. Schematic diagram showing the Institute of Gas Technology system for production of blended cement from dredged material.
78
-------
Contaminant
2,3,7,8 TCDD (ppt)
O ODD (ppt)
TCDD/TCDF TEQ (ppt)
Total PCBs (ppm)4
Anthracene (ppb)
Benzo(a)anthracene (ppb)
Chrysene (ppb)
Total PAHs (ppb) i
Arsenic (ppm)
Cadmium (ppm)
Chromium (ppm)
Copper (ppm)
Lead (ppm)
Mercury (ppm) total
Zinc (ppm)
As-dredged
23
11879
513.2
8.6
•18735
17155
16878
293,854
39
27
298
1012
542
2.8
1535
1 NJ Department of Environmental Protection.
2 NJ Deoartment of Environmental Protection.
Treated
0.35
3.7
1.406
0.31
0
0
0
0.16
1.52
0.66
632.5
306
29.4
0.092
280
Non-residential soil,
Residential soil, dire
Percent
Reduction
98.47 '
99.97
99.72
96.39
100
100
100
100
96.10
97.55
212
69.76
94.57
96.71
81.76
direct contact J J
ct contact. J.J.A.C
NJ
Non-Resid:
—
—
—
2
10,000
4000
40,000
—
20
. 100
—
600
600
270
1500
A C 7-26D
7-26D. rev
NJ
1 Resid.2
—
—
—
0.49
10,000
900
9000
n/a5
20
1 .
- — - -
600
400
14
1500
, revised 7/1 1/96.
ised 7/1 1/96.
NY
Resid.3
—
—
—
1
50,000
224
400
396,500
7.5
1
10
25
SB6
0.1
20
3 NY Department of Environmental Conservation. Recommended soil cleanup objectives. HWR-94-046 (Revised). January 24, 1994.
4 See Reference 12.
5 n/a = not available.
6 SB = Site background.
Clean
offgases
Feed
Sediment
1 Filtrate water
Glass
product
Figure 4. Schematic diagram showing the production of glass from dredged material using the Westinghouse Science and Technology
Center plasma torch melter.
79
-------
Tablo 7, Summary of Results for the Westinghouse Vitrification Process
Contaminant
2,3,7,8 TCDD{ppl)
0 COD (ppt)
TCDD/rCDFTEQ(ppt}
Tote! PCBs (ppm)4
AnUiracane (ppb)
Benzo(a)anthracene (ppb)
Chrysarta (ppm)
Total PAHs (ppb)4
Arsenic (ppm)
Cadmium (ppm)
Chromium (ppm)
Copper (ppm)
Lead (ppm)
Mercury (ppm)
Zinc (ppm)
' Ml Datuirtment of Environmei
As-dredged
19.0
9655
335
0.900
7.72
7.19
8.76
109
15.8
33.3
344
1145
594
2.08
1695
ntal Protection.
Treated
—
8.0
0.07
0
0
0
0
0
4.94
0.948
1001
1077
105
0.087
1240
Non-residential soil.
Percent
Reduction
100
100
100
100
100
100
100
100
68.7
97.1
—
5.9
82.3
95.8
26.8
direct contact
NJ
Non-Resid.
—
—
—
2
10,000
4000
40,000
—
20
100
—
600
600
270
1500
J.J.A.C. 7:26D
NJ
1 Resid.2
—
—
—
0.49
10,000
900
9000
n/a5
20
1
—
600
400
14
1500
.revised 7/1 1/96.
NY
Resid.3
—
—
—
1
50,000
224
400
396,500
7.5
1
10
25
SB6
0.1
20
* NJ Department of Environmental Protection. Residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.
* NY Department of Environmental Conservation. Recommended soil cleanup objectives. HWR-94-046 (Revised). January 24,1994.
* See Reference 12.
* n/a - not available.
•SB - Site background.
handling at least a portion of the contaminated dredged
material from NY/NJ Harbor.
Acknowledgments
Work at Brookhaven National Laboratory was supported
in part by the U.S. Department of Energy under Contract
No. DE-AC02-76CH00016 and by Interagency Agree-
ments between the U.S. Environmental Protection
Agency (Nos. DW89941761-01-0 and DW89937890-
01-0), the U.S. Army Corps of Engineers (No. NYD-94-
39), and the U.S. Department of Energy.
References
1. U.S. Army Corps of Engineers, New York District.
September 1996. Dredged Material Management
Plan for the Port of New York and New Jersey.
Interim Report.
2. Stem, E. A., Donate, K., Jones, K. W., and Clesceri,
N. L "Processing contaminated dredged material
from the Port of New York/New Jersey." Pre-
sented at the Estuarine and Coastal Sciences
Association (ECSA) Estuarine Research Federa-
tion (ERF) 96 Symposium, Middelburg, The Neth-
erlands, 16-20 September 1996. Estuaries. In
press.
Jones, K. W., Stern, E. A., Donate, K., and Clesceri,
N. L. "Processing of" NY/NJ Harbor estuarine
dredged material. Dredging and Management of
Dredged Material," Proceedings of 3 Sessions
Held in Conjunction with the Geo-Logan 97 Con-
ference, The Geo-lnstitute/ASCE, July 16-17,1997,
Logan, UT. pp. 49-66.
Jones, K. W., Stern, E. A., Donate, K. R., and
Clesceri, N. L. Commercialization of dredged-
material decontamination technologies.
Remediation. 8 (2) 43-54 (1998).
C. R. Lee, U.S. Army Corps of Engineers, Water-
ways Experiment Station, Attention: CEWES-ES-
F, Environmental Processes and Effects Division,
3909 Halls Ferry Road, Vicksburg, MS 39180-
6199.
Mohsen Amiran, BioGenesis Enterprises Inc., 610
West Rawson Avenue, Oak Creek, Wl 53154.
80
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7. John Cardoni, Metcalf & Eddy, Inc., Post Office
Box 1500, Somerville, NJ 008876-1251.
8. Amir G. Rehmat, Institute of Gas Technology,
1700 South Mount Prospect Road, Des Plaines,
IL 60018-1804.
9. Nancy H. Ulerich, Westinghouse Electric Corpora-
tion, Science & Technology Center, 1310 Beulah
Road, Pittsburgh, PA 15235-5098.
10. Tanal, Vahan; Wang, Jaw-nan; Samtani, Naresh
C.; and Lancellotti, Anthony. "Lime stabilization
and disposal of contaminated dredged harbor sedi-
ments." Proceedings of Geoenvironment 2000,
New Orleans, LA, February 1995.
11. Samtani, Naresh C.; Tanal, Vahan; Wang, Joe;
and Lanclelotti, Anthony R. "Effect of lime admix-
tures on contaminated dredged sediments." Pro-
ceedings of First International Congress on Envi-
ronmental Geotechnics, Edmonton,,Alberta,
Canada, July 10-15, 1994.
12. NOAA. 1996. Contaminant Levels in Muscle and
Hepatic Tissue of Lobster from the New York
Bight Apex. Report to the U.S. Environmental
Protection Agency and the U.S. Army Corps of
Engineers. National Oceanic and Atmospheric Ad-
ministration, National Marine Fisheries Service,
James J. Howard Marine Science Laboratory,
Highlands, NJ. May 1996.
81
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The Fully Integrated Environmental Location Decision
Support (FIELDS) System
An Approach to Identify, Assess and Remediate Contaminated
Sediment
Matthew H. Williams, George D. Graettinger, Howard Zar, Dr. Yichun Xie and Brian S. Cooper
Introduction
Sound and timely environmental decisions are best
made using complete and reliable information that can
effectively be communicated to all appropriate audi-
ences. The better and faster GIS-based tools can help
people identify and analyze environmental problems,
the better the chance to understand these problems and
find ways to solve them.
This paper reviews the practices, achievements, and
future of geographic information system (GIS) based
decision support systems used by the United States
Environmental Protection Agency (USEPA) at its Re-
gion 5 Water Division and Superfund programs in Chi-
cago. The Region 5 office covers six midwestern states
of Illinois, Indiana, Ohio, Michigan, Minnesota, and Wis-
consin, and has further responsibilities for the Great
Lakes. Several groups in the region are applying and
refining comprehensive databases and innovative GIS
tools to significantly advance the Agency's efforts to
protect and enhance the environment.
The process of collecting, organizing, analyzing and
visualizing data for a geographic area in multiple layers
is often a complex, time-consuming and expensive task.
With the advancement of GIS technologies over the past
ten years, this process has made noteworthy gains in
some areas, while presenting new sets of complexities
in others. Current systems can already represent envi-
ronmental situations in their three-dimensional states
with impressive visual displays and are becoming easier
to use and more affordable. However, the functionality
of these systems must be improved along with the
methods of collecting the data that is put into the sys-
tem.
Nevertheless, the trend is clear: databases and the GIS
tools applied to them will continue to have a profound
impact on the way environmental decisions are being
evaluated, determined and improved. Those who can
sift'through the mounting networks of environmental
information to extract or compile critical data, will be
most adept at understanding environmental problems
and most focused on creating the GIS tools to help solve
them.
The presentation accompanying this paper will provide
examples of how GIS tools can be used to help solve GIS Groups
environmental problems from "start" to "finish".
Overview
As a practice, geographic areas of interest are defined
by government (state, county, city), environment
(waterbody, geology, soil), or by other interests (demo-
graphics, urban, rural, industrial, residential, land use). It
has always been difficult to display multi-variant data
from these areas on a two dimensional sheet of paper.
Data were commonly evaluated by one theme, or data
layer, at a time—not in their actual multilayered, three-
dimensional states.
Many environmental agencies and organizations now
have centralized GIS groups charged with providing
technical support for programs. Fundamental to estab-
lishing a successful GIS-based decision support system
is the challenge of bringing together a well-rounded,
highly skilled group of individuals to do the work.
We have brought together one such a group at USEPA
Region 5 and in our partner universities to support
Water Division and Superfund Program needs. The
Water Division GIS Team and FIELDS Group includes
individuals with the following technical expertise:
82
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Aerial Mapping (photography, digital orthoquads- fast, reliable and affordable support to decision-makers
DOQs, imaging) at some of the region's most contaminated sites.
Computer System Administration
Communications
Differential Global Positioning Systems (DGPS)
Environmental Assessment (Sampling and In-field
Analytical)
Geographic Information Systems (GIS)
Human Health and Ecological Risk Assessment
Internet Web Design and Graphics
Relational Database Design and Management
Remedation Alternatives and Costs
Remediation Project Management
Statistics
A focused and technically balanced team is essential
because the power of a GIS tool will reflect the collective
knowledge of those who developed it and the quality of
the data they put into it. Users of these tools can then
benefit greatly by having that knowledge and data fully
integrated and immediately available for their use.
Communication
Maps and images are essential to effective communica-
tion. They can portray large- and small-scale problems
simply and rapidly to decision makers—helping them to
pursue worthwhile, long-term environmental solutions.
Based on this, the future of databases and GIS tools is
to allow users to identify, manage and view both old and
new environmental data in a "real-time" fashion. Future
GIS users should be able to instantaneously link newly
acquired real-time data with relevant historical data to
perform analyses and obtain displays to support their
decision-making needs.
Fully Integrated Environmental Location
Decision Support System—FIELDS
On the Web: http://ceita.acad.emich.edu/
fields/SHA RED/PA GES/FLDHOME.HTM
The FIELDS system is a collection of technical tools and
applications incorporating relational databases, GIS,
GPS, statistical techniques and in-field analytical tech-
nologies to inform decision-makers about. a variety of
conditions at a site or geographic area of special con-
cern. The FIELDS focus is an in-depth evaluation of
current and historical site-specific conditions to provide
FIELDS has supported Region 5 site/program manag-
ers with determining the spatial distribution of contami-
nants, volume, mass, human health risk, and remedial
options and costs for sediment hotspot areas. The sta-
tistical/spatial analytical tools in FIELDS have been used
for establishing and tracking sediment cleanups of envi-
ronmental sites in Region 5 states.
The system was developed by the FIELDS Group that
resides in the Region 5 Water Division and Superfund
program. The group provides multimedia (groundwater,
surface water, soil, sediment, etc.) technical assistance
for many priority environmental sites in the region.
The FIELDS Group helps address site-specific contami-
nated sediment issues by:
Identifying hot spots and pollutant sources
Assessing risks and contaminant mass loadings
Prioritizing and targeting areas for cleanup
Evaluating remedial alternatives and costs
j? **
Effectively visualizing and communicating options
to decision-makers
Implementing and tracking environmental clean-
ups
Meeting these objectives allows users to make scientifi-
cally based, mission-critical decisions about areas of
environmental concern.
There are four main modules of the FIELDS system.
1. The Basemap
The first step to focusing on a specific geographic site is
to create a spatially accurate basemap of the area of
concern. Typically, this process involves obtaining an
aerial photograph or digital ortho quad of sufficient qual-
ity. This image must then be made into a map by using
software (e.g. ARC/INFO) to register and rectify the
photograph to vertical and horizontal ground control
points. The control points are established using a variety
of methods such as real-time global positioning systems
(GPS) with sub-meter accuracy.
2. GIS-Based Sampling Design and
Collection
Once an accurate basemap is created, FIELDS can
support the display and analysis of numerous layers of
spatial data. The FIELDS process utilizes the basemap
to design a GIS-based sampling plan for contaminants
of concern within the geographic area of interest. The
sampling design module runs using ArcView Avenue/
83
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Dialogue Designer scripts as a stand alone extension to
support statistically based hotspot and user defined
sampling designs. The FIELDS sampling design module
generates x-y coordinates and sample identification val-
ues associated with sample locations and directly gen-
erates a waypoints file (a file with latitude and longitude
coordinates for samples) that can be exported to a GPS
unit. This waypoint file is then used to navigate, using
the GPS, to the design sample locations where samples
are to be collected for analysis. These sample sites are
then input into the FIELDS database and are ready to
receive the chemical analytical data as it is returned.
3. Real-Time Analytical
Samples collected from locations defined by the FIELDS
GIS-based sampling design and collection module, can
be analyzed for chemicals of concern using rapid, in-
field analytical techniques such as onsite Gas Chro-
matograph/Mass Spectrometer (GC/MS), x-ray
fluorescence and immunoassay kits. Real-time analysis
and the sample design module allows these data to be
used as soon as the results are available as the data-
base is already set up to receive and use these analytic
data. Obtaining real-time data about the levels of chemi-
cals of concern in field samples provides maximum
efficiency in mapping hotspots of contamination while in
the field, as well as reducing the overall costs and time
associated with these activities.
4. Database Loading Function
The data resulting from in-field analyses of environmen-
tal samples can be immediately loaded into the FIELDS
database structure using the Database Loading Func-
tion module. The Database Loading function is a
standalone Visual Basic/Map Objects application to an
Access database. The data are input to the designed
sample sites and become part of the FIELDS Database/
GIS system. These data can then be used to perform
numerous database and GIS analyses for the site.
The result of the FIELDS four-part process is a site-
specific decision support system that can:
Map contaminants
Define hotspots
Calculate area, volume, mass, loadings
Estimate risks—human health and ecological
Prioritize areas for cleanup
Evaluate remedial alternatives and costs
Create communication tools—Internet-ready prod-
ucts such maps, images, data summaries and
briefings
These capabilities provide immediately useful and highly
valuable information to support environmental decision-
making and actions in areas of specific concern.
Data Quality
The application of FIELDS will continue to expand in
scope and capability. At the same time, the detail and
quality of the environmental data upon which the tools
are applied must be more closely monitored and as-
sessed. The quality of environmental data put into GIS
systems must be clearly determined in order to under-
stand the limitations of decisions made against these
data. Data quality assessment includes evaluating the
accuracy and precision of sample locations, collection,
storage, custody and analysis (raw data sheets, data
quality standards, detection limits, reporting limits, etc.)
Therefore, efforts should be made to incorporate data
quality criteria into databases and GIS tools so that
users can determine the appropriate use of data.
The FIELDS Group has developed and will be expand-
ing its capacity to provide GIS and characterization data
to a broad base of users via a real-time, online mapping
tool that will deliver products in an interactive session.
It is anticipated that before long, maps relating to some
environmental issues will become so widely accessed
by Internet and other means that their familiarity will be
not unlike weather maps of today. Although the public
may not be any more persuaded of the decisions made
by environmental officials than they are of today's weather
predictors, they may be much better informed.
Conclusion
The future of FIELDS and other GIS-based decision
support systems is to potentially drive when, where, why
and how an environmental problem can be solved. The
more efficient the identification, acquisition and man-
agement of relevant environmental data the more likely
that decisions based on these data will achieve measur-
able environmental benefits.
This will require a continued emphasis on the design of
comprehensive and fully integrated spatial data plat-
forms capable of managing important environmental
information from the initial identification of a problem to
the development and implementation of a final solution.
USEPA Region 5 programs have had a great deal of
success with combining GIS, GPS and statistics with
environmental sciences and engineering to help ad-
dress a variety of contaminated sediment concerns. The
FIELDS Group provides a wide array of skills, technol-
ogy, data and institutional knowledge to the programs or
projects we support. Responding to customer needs,
focusing on obtaining solutions, and adapting to political
and environmental concerns has allowed us to be a
highly effective unit. FIELDS will continue to support
USEPA Region 5 efforts to locate, define and cleanup
contaminated sediment.
This paper has been adapted from USEPA Region 5's
paper written for the Geolnformatics '98 Conference
held in Beijing, China, June 17-19, 1998.
84
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Remediation Strategies and Options for Contaminated
Sediment
Carol Ancheta
Scientific Project Officer
Environment Canada
Remediation Technologies Program
Downsview, Ontario, Canada
Executive Summary
When faced with the problem of contaminated sediment,
one must look at all of the options for the site and select
which option or options are most feasible on a site
specific basis. This paper introduces the reader to some
of the issues which must be addressed to understand
the problem before making decisions on a solution. An
overview of remedial options and applicable technolo-
gies is outlined with a brief discussion on selection
methodologies for preferred options and technologies.
The case study on Thunder Bay provides a current
example of how contaminated sediment is being
remediated.
Understanding the Problem
To determine when remediation is required, the follow-
ing question needs to be addressed sufficiently: Does
the site pose a threat to the ecosystem and/or human
health? The complexity of the answer to this question is
site specific. In general, one must undertake a site
assessment. Four phases to understanding the nature
and extent of contamination at a site include:
1. Phase I: Existing information is collected. Ex-
amples include conducting interviews, visiting the
site, reviewing historical information including ex-
isting reports, describing the site and surrounding
area in detail, and identifying historical and ongo-
ing sources of contamination.
2. Phase II: Sample collection is undertaken. A
screening level sampling program is designed and
implemented, and if necessary, followed up with a
more detailed sampling program in identified
area(s) within the site.
3. Phase III: Severity of chemical contamination is
analyzed and compared with available guidelines.
Biological contamination is analyzed by measur-
ing (a) benthic community structure; (b) fish com-
munity structure; and (c) bioassays. Bioavailability
and bioaccumulation studies should also be con-
sidered during this phase of the evaluation. It is
important to note that even though the benthic
community may suggest a healthy structure, per-
sistent toxics present in the sediment may be
bioavailable/bioaccumulative to other organisms
in the food chain, including humans. For this
reason, uptake studies are useful to measure
contaminant release from the sediment into the
water column. Tissue residue studies are also
useful to measure the availability of contaminants
to biota and potential for transfer of contaminants
through the food chain.
4. Phase IV: Risk assessment is undertaken to iden-
tify exposure pathways and evaluate impacts as-
sociated with environmental, economic, social,
legal, and technical issues.
An Introduction to Remedial Options
Remedial options for contaminated sediment include: do
nothing; in-situ treat; cap; contain; and dredge (see
Figure 1). For all options, end use of the material needs
to be considered. Particularly if the material is to be
dredged, end use could include disposal or beneficial
reuse of the material. An introduction to each option is
discussed below, and technologies applicable to each
activity are identified. Options and technologies can be
selected individually or can be used in combination with
one another.
Natural Remediation
Nature is allowed to take its own course with this option.
Normally, this option is preferred when natural biodegra-
dation of the contaminants are anticipated and/or sedi-
mentation and natural burial will most likely occur in the
area of concern. If this option is selected, monitoring of
85
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Remedial Options
Natural Remediation
In-silu treat
Remove
Cap
Contain
JL
Monitor owrtl
natural bariii
Biological
chemical
chemical/biological
immobilization
Mechanical
hydraulic
hybrid
_L
Subaqueous
dry
Sheetpiling
earthen dikes
rubble mound
Pre-treat
Dewater
passive/mechanical
physical separation
slurry injection
Treat
Dispose
Biological thermal
chemical immobilization
extraction radiant energy
Confined disposal facility
industrial landfill
hazardous waste landfill
Re-use
Industrial fill
construction projects
commercial use
1
Figure 1. Remedial options and technologies.
the area over time is required to determine the implica-
tions and affects of deciding to leave the site alone.
In-situ Treat
This option allows for the treatment of sediment in place.
Understanding the chemical nature of the contaminants
at the site is an essential component to this option.
Potential chemical reactions may occur due to the change
In the environment from application of one or more of
these techniques. These reactions will need to be inves-
tigated prior to selection of this option to determine
environmental effects. Monitoring these reactions during
and after application is required.
In-sttu treatment technologies include:
Biological: Microorganisms, in the presence of oxygen
and nutrients (aerobic) or in oxygen-deficient areas
(anaerobic), biodegrade organic contaminants.
Chemical: Chemicals are used to neutralize, precipitate,
or dechlorinate contaminants.
cal/biological: A combination of both chemical and bio-
logical processes are used. An oxidizing agent is in-
jected into the sediment in order to facilitate microbial
metabolic activity and degradation of contaminants.
Immobilization (solidification/stabilization): technologies
which change the state of the sediment, either physically
or chemically, and reduce the potential for contaminant
migration. Fixatives such as cements, pozzolans, and
thermoplastics are used.
Cap
This option allows for clean material to be placed over
top of the contaminated sediment. The clean material
creates a physical barrier between the contaminants
and the overlying and surrounding environment. Ex-
amples of possible environmental issues to consider
before selection of this option include groundwater ef-
fects, contaminant migration, bioturbation zones, dura-
bility and weathering effects of the cap over time.
Monitoring and possible maintenance of the cap in
perpetuity is required.
Capping technologies include:
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Subaqueous cap: Controlled and accurate placement of
clean material is laid over top of in place contaminated
sediment creating a bioturbation zone.
Dry cap: placement of a large volume of clean material
over the sediment so that the final elevation of the cap
surface is above the water level.
Contain
This option allows for containment of the site by creating
a physical barrier which surrounds the zone of contami-
nation. Examples of possible environmental impacts to
consider before selection of this option include ground-
water effects, site security from humans and terrestrial
wildlife, weathering and storm events. Monitoring and
possible maintenance of the containment structure will
be required in perpetuity.
Techniques used to contain a site include, but are not
limited to:
Sheetpiling: Metal piles are driven into the bottom of the
waterbed. Once anchored, steel sheets are placed be-
tween each piling.
Earthen dikes: generally homogeneous earth material.
Rubble mound: The core material is usually clay. The
core is surrounded by either: (1) fine granular material,
increasing in coarseness and grain size as it moves
outward away from the core; or (2) surrounded by a
synthetic filter material.
Dredge
This option allows for the physical removal of the con-
taminated sediment from the site. End use of the mate-
rial needs to be determined prior to selection of this
option. Disposal or beneficial re-use of the material
should be considered. Disposal of the dredged material
may include placement into a confined disposal facility,
a licensed industrial landfill or a licensed hazardous
waste landfill. Beneficial re-use may include using the
material for construction projects, as industrial fill, or for
any other use where the quality of material meets the
local government standards for use on the identified
lands, (e.g. the material meets commercial/industrial
criteria for use on industrial land), and is acceptable to
the local community. Pretreatment and/or treatment of
the material may be required to meet the end use goal.
Some factors to consider before selecting this option
include: (1) contaminant variability of the site is an
important factor in delineating both vertical and horizon-
tal site boundaries; (2) positioning accuracy of the dredge,
both vertical and horizontal, and experience of the op-
erator; (3) type of contaminants present and potential for
chemical reactions during the operation (e.g. dredging
highly contaminated polycyclic aromatic hydrocarbons
such as naphthalene may cause a release of volatile
organic carbons into the atmosphere and consequently
cause a negative impact on air quality and a potential
health and safety concern for site workers); (4) presence
of debris and possible impact on operational perfor-
mance of the dredge; and (5) environmental monitoring
of the site before, during, and after the dredge operation
• to ensure environmental compliance.
Dredge technologies include:
Mechanical: dredges which use mechanical force to
remove sediment from the bottom of a water column.
Examples include clamshell, backhoe, bucket ladder,
dragline, and dipper.
Hydraulic: dredges which use water, mixed with the
sediment, to remove and transport the material in a
slurry phase. Air is sometimes substituted for water in
pneumatic dredging operations. Examples include
cutterhead, suction, eddy pump, matchbox fluidizer, hop-
per, pneuma, oozer, and portable dredges.
Hybrid: mechanical force is used for the initial handling
of the material, followed by pumping. An example in-
cludes the amphibex.
Contaminants are found predominantly in fine grain size
sediment including clay, silt and sand. Regardless of the
end use of the material, contaminated dredged material
is usually pre-treated to reduce water content, remove
debris, remove oversized uncontaminated particles, to
accelerate settling time and/or to accelerate microbial
action.
Pre-treatment technologies include:
Dewatering: dewatering sediment involves reducing the
water content of the sediment.
Passive: air drying technologies which dewater the sedi-
ment passively over time.
Mechanical: dewatering processes which use energy to
force water out of the sediment.
Slurry injection:
Chemical: chemicals such as polymers and flocculants,
can be injected into the pipeline of an hydraulic dredging
operation to condition the dredged material for acceler-
ated settling in a disposal or treatment facility
Microorganisms: microbes and nutrients can be injected
into the dredged material at the disposal facility to
enhance the biodegradation of organics.
Physical separation: classification of coarser sediment
grains and debris allows for oversized material to be
removed from the dredged material with little or no
treatment requirements. Examples include vibrating
screens, grizzlies, trommels, hyrdocyclones, froth floata-
tion, magnetic separation, and gravity separators.
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Treatment technologies may be used to change the
state of the contaminants to levels acceptable for end
use goals. Many types of technologies are on the market
today. The following is a generic list of treatment catego-
ries.
Biological: treatment technologies which use bacteria,
fungi and/or enzymes to accelerate the natural biodeg-
radation of organic contaminants or to transform the
contaminants to less or nontoxic forms. Accelerated
growth of microorganisms and the increased production
of enzymes, balanced with nutrients, oxygen and tem-
perature, are the mechanisms whereby target contami-
nants are converted to less or nontoxic byproducts.
Examples Include landfarming, and biosiurry.
Chemical: technologies which add chemical reagents to
the sediment in order to destroy, detoxify, or remove the
contaminants. Examples include dechlorination, and oxi-
dation.
Extraction: uses a solvent to desorb or separate the
organic contaminants from the particulate solids, and
concentrate them in reduced volumes. Examples in-
clude inorganic and organic.
Radiant energy: any system where waves of energy are
used to treat contaminants. Wave forms include light at
various wave lengths (e.g. visible light, UV, electron
beam), sound waves and radio waves.
Immobilization (stabilization/solidification): technologies
which change the state of the sediment to reduce the
potential for contaminant migration (i.e. leaching, ero-
sion, volatilization potential of contaminants) after its
disposal. Solidification examples include cements, sili-
cates, and pozzolans. Stabilization examples include
polymers such as urea formaldehyde.
Thermal: technologies which heat the sediment to sev-
eral degrees above ambient temperature to destroy,
encapsulate, desorb or volatilize contaminants. Examples
include pyrolysis, vitrification, high-pressure oxidation,
thermal desorption and incineration.
Case Study Thunder Bay
Thunder Bay is located on the northern shores of Lake
Superior, Ontario, Canada. In 1997, a five-party consor-
tium, including three private sector and two public sector
groups, signed an agreement to remediate creosote
based contaminated sediment in the harbour. Remedial
options for the site were investigated individually and
collectively. Public consultation was extensive and played
a large role in the decision making process. The Thun-
der Bay project is currently underway and involves the
natural remediation, contain, cap, and dredge options.
Once dredged the material will be pre-treated, treated
and re-used as industrial fill.
All options for the site were assessed individually and
collectively. Individually, options were either found not
suitable for the site due to the level and varying degrees
of contamination or the options were deemed very ex-
pensive and not feasible to implement. By combining the
options, all levels of contamination are addressed. Also,
by combining the options, desirable characteristics of all
approaches are optimized while minimizing the possible
negative attributes associated with individual approaches.
The Thunder Bay project was developed to reflect
remediation needs in different zones of contamination,
resulting in the integration of containment, removal,
treatment and capping activities. A site specific, risk
assessment approach was used to establish a cleanup
criterion. In establishing this criterion, the objective was
to maximize aquatic enhancement while at the same
time permitting an economically viable remediation
project. The primary cleanup criterion for sediment was
based on the toxicity of the sediment to organisms most
likely to come into contact with the contaminants. Those
sediment responses which resulted in a severe toxic
biological effect were recommended to be isolated from
the lake waters or removed. A secondary criterion was
developed based on less severe toxic biological effects.
It was recommended that contaminants be isolated from
the water column when the sediment elicited this sec-
ondary response. Those sediments below the second-
ary criterion which appeared to elicit no observed toxic
biological response from the test organisms were to be
left in place and monitored for natural biodegradation
and sedimentation over time.
Based on the project specific clean up criteria, various
activities are currently being implemented. An environ-
mental clay barrier and offshore containment berm has
been constructed to contain and isolate the majority of
contaminants from the harbour. Severely toxic sedi-
ments have and are currently being removed with use of
an environmental dredge. The dredged material will be
treated to a level consistent with the Canadian Council
of Ministers of the Environment (CCME) Industrial Soil
Criteria. Once treated to acceptable levels, the material
will be used as industrial fill along with other clean fill.
The fill will be placed behind the new containment berm,
creating new industrial lands. To compensate for the
construction of the berm, infilling activities and fish habi-
tat loss, a fish habitat program is being implemented.
This program will include the excavation and sculpting of
reclaimed marshland and development of new habitat
for fish, waterfowl and wildlife. The zone of contamina-
tion left outside of the containment berm will be left in
place for natural degradation, on the basis that these
contaminants are relatively immobile, some are found to
be "hard packed" and less susceptible to resuspension.
Monitoring programs are in place to determine the effec-
tiveness of the remediation activities.
Remedial Option Selection Methods
There are a variety of methods which can be used to
determine a preferred remedial option. One or more
may be used at a given time during the decision making
process. Examples include:
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Risk assessment: evaluation of environmental, social,
economical, legal, scientific and technical issues.
Cost/benefit analysis: monetary values are given to
project components of each remedial option and sum-
mations of each dollar value are compared.
Open bidding process: competitive bids decide the pre-
ferred option.
Demonstration technology evaluation: bench and/or pi-
lot scale testing technologies
Weighted scoring system (e.g. Concordance Method):
rank and give weights to selection criteria based on their
order of importance. Highest weighted options are se-
lected as preferred options.
Project team: consensus is given among project team
members.
Technology Selection:
Many variables need to be considered when selecting
applicable technologies for the preferred option. Some
key considerations include:
Cost versus budget allocation
End use of the material (disposal versus re-use)
Productivity
Time availability
Type of contaminants and variability
Environmental performance
Accurate positioning of equipment (if applicable)
Transportability
Compatibility with site conditions (e.g. size, depth of
contamination, currents)
Compatibility with other technologies in the process
stream
Experience of team
SEDTEC
SEDTEC, Sediment Technology Directory, is a user-
friendly computer software product listing removal and
treatment technologies for contaminated sediment and
treatment technologies for contaminated soil and slud-
ges. Based on an international inventory of manufactur-
ers and vendors of technologies, this database was
originally developed by Environment Canada to identify
suitable technologies for dealing with contaminated sedi-
ment. Today, it is a tool which identifies technologies for
site specific needs, provides case studies for projects,
outlines costs and operational efficiencies, lists contacts
for technology auditors, project funding agencies, and
technology vendors/manufacturers worldwide. This di-
rectory was demonstrated on May 14, 1997 at the U.S.
EPA National Conference on Management and Treat-
ment of Contaminated Sediments in Cincinnati, OH.
Conclusion
This paper introduces the reader to phases involved in a
site assessment, to the types of remedial options avail-
able and to the sediment remediation technologies on
the market today. Selection methodologies and consid-
erations for technology selection are also provided.
Understanding the nature and extent of sediment con-
tamination is the first step to defining the solution. Inves-
tigating all of the options, individually and collectively,
and identifying suitable technologies is instrumental in
determining the preferred options. Selecting the reme-
dial solution for the area of concern is site specific. One
should draw upon other experiences through case stud-
ies. In many cases, the decision will be community
based,
References
1. Ancheta, C. 1996. Handle Reef Sediment
Remediation Project, Analysis of Alternatives Re-
port. Hamilton Harbour Remedial Action Plan.
Burlington, Ontario. Volume 3.
2. Environment Canada et al. 1996. Northern Wood
Preservers Site Sediment Remediation Project,
Thunder Bay Harbour, Comprehensive Study Re-
port. Downsview, Ontario.
3. Jaagumagi, R. and D. Persaud. 1995. Sediment
Assessment and Remediation Ontario Approach.
Sediment Remediation '95. Windsor, Ontario.
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The Automated Dredging and Disposal Alternatives
Modeling System (ADDAMS):
Summary and Availability
Paul R. Schroeder
Research Civil Engineer
U.S. Army Engineer Waterways Experiment Station (WES)
Vicksburg, MS
Michael R. Palermo
Research Civil Engineer WES
Background
Planning, design, and management of dredging and
dredged material disposal projects often require com-
plex or tedious calculations or involve complex decision-
making criteria. In addition, the evaluations often must
be done for several disposal alternatives or disposal
sites. The Automated Dredging and Disposal Alterna-
tives Modeling System (ADDAMS) is an interactive per-
sonal computer (PC)-based design and analysis system
for dredged material management (1). ADDAMS con-
tains a collection of computer programs (applications)
designed to assist in managing dredging projects and in
evaluating the environmental effects of dredged material
management alternatives in accordance with the USAGE/
USEPA technical guidance (2). (See Figure 1.) This
paper describes the system, currently available applica-
tions, mechanisms for acquiring and running the sys-
tem, and provisions for revision and expansion.
ADDAMS
Dredged Material
Management
SETTLE DYECON
PSDDF
LTFATE MDFATE
D2M2
Environmental Effects
Evaluation
EFQUAL CDFATE LAT-E
DREDGE STFATE
HELPQ RUNQUAL LAT-R
RECOVERY PUP
Figure 1. ADDAMS modules.
90
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Description of ADDAMS
PSDDF
ADDAMS is composed of individual modules or applica-
tions, each of which has computer programs designed
to assist in the evaluation of a specific aspect of a
dredging project. The creation of the system was in
response to requests by Corps field offices for tools to
rapidly evaluate dredged material management alterna-
tives. The objective of the ADDAMS is to provide state-
of-the-art computer-based tools that will increase the
accuracy, reliability, and cost-effectiveness of Corps
dredged material management activities in a timely man-
ner.
Most of the current ADDAMS programs employ a menu-
driven environment and support full-screen data entry.
Single keystrokes (usually the F1-F10 function keys,
number keys, Esc key, cursor keys, and the Enter key)
select menu options in the system. The newer applica-
tions are programmed to run in the Microsoft Windows
environment, and all modules will eventually be con-
verted to a Windows format.
Each ADDAMS application has documentation describ-
ing how to run that application, and how that application
functions. A list of references is provided directly on-
screen within the applications including those concerned
with the technical background and theory involved and
documentation for the programming as appropriate.
Points of contact for each application are also listed
directly on the screens for answering questions regard-.
ing the respective applications. In addition, computer-
ized demonstrations are available for many applications
and example data files are provided for all applications.
ADDAMS applications and their methodologies are richly-
diverse in sophistication and origin, reflecting the nature
of dredged material management activities. The con-
tents range from simple algebraic expressions, both
theoretical and empirical in origin, to numerically intense
algorithms spawned by the increasing power and
affordability of computers. A brief description of each of
the currently available applications follows.
SETTLE
SETTLE [full title: Design of Confined Disposal Facilities
(CDFs) for Suspended Solids Retention and Initial Stor-
age Requirements] provides a computer program to
assist users in the design of a CDF for solids retention
and initial storage. Various settling processes occurring
in the CDF control the initial storage during filling, clarifi-
cation, and effluent suspended solids. Laboratory col-
umn settling tests are an integral part of these design
procedures, and the data from these tests are required
in order to use this application. The SETTLE application
analyzes laboratory data from the settling tests and
calculates design parameters for CDFs.
PSDDF [full title: Primary Consolidation, Secondary Com-
pression, and Desiccation of Dredged Fill provides a
mathematical model to estimate the storage volume
occupied by a layer or layers of dredged material in a
confined disposal facility (CDF) as a function of time.
Management of CDFs to provide maximum storage
capacity is becoming more necessary as both the stor-
age capacity of existing sites and availability of land for
new sites decrease. Maximum site capacity is achieved
through densification of the dredged material by removal
of interstitial water. The volume reduction and the result-
ing increase in storage capacity are obtained through
both consolidation and desiccation (drying) of the dredged
material. The PSDDF model relies on the results of
laboratory consolidation tests to estimate the magnitude
and rate of consolidation and on climatic data for estima-
tion of the rates of drying at a given site. This updated
module has improved solution techniques, a secondary
compression model, and an on-line data base of con-
solidation properties.
DYECON
DYECON [full title: Determination of Hydraulic Retention
Time and Efficiency of Confined Disposal Facilities}
provides a computer program to determine mean hy-
draulic retention time and hydraulic efficiency of a con-
fined disposal facility (CDF) from a dye tracer slug test.
Determination of retention time of ponded water is an
important aspect of CDF design. Dye tracer studies may
be undertaken to provide retention time data for large
sites, or those with unusual characteristics. In the ab-
sence of dye tracer data, the hydraulic efficiency can be
estimated empirically.
D2M2
D2M2 [full title: Optimization of Long-Term Operation,
Expansion, and Acquisition of Multiple Disposal Sites for
Multiple Dredging Reaches], developed by the U.S.
Army Engineer Hydrologic Engineering Center (HEC)
and modified for the San Francisco District, is a simula-
tion-optimization model for systematic analysis of long-
term operation and expansion of multiple disposal sites.
The model provides a means of determining the opti-
mum usage of multiple disposal areas to meet the
dredging requirements at multiple dredging sites, for
example, along the length of a navigation channel.
D2M2 uses a linear-optimization approach in determin-
ing the optimum usage based on input data for dredging
volumes, location, frequencies, transportation facilities,
and associated costs.
STFATE
STFATE [full title: Short-Term Fate of Dredged Material
Disposed in Open Water for Predicting Deposition and
Water Quality Effects] provides mathematical modeling
of the physical processes determining the short-term
fate of dredged material disposed at open-water sites,
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that is, within the first few hours after disposal. STFATE
was developed from the DIFID (Disposal From an In-
stantaneous Dump) model. In STFATE, the behavior of
the material is assumed to be separated into three
phases: convective descent, dynamic collapse, and pas-
sive transport-dispersion. The model provides estimates
of receiving water concentrations of suspended sedi-
ment and dissolved constituent and the initial deposition
of material on the bottom. Estimates of water column
concentrations are often needed to determine mixing
zones; whereas, the initial deposition pattern of material
on the bottom is required in long-term sediment trans-
port that assess the potential for erosion, transport and
subsequent redeposition of the material. This model can
also serve as a valuable aid in field monitoring pro-
grams. STFATE can be used in evaluating water column
effects of open-water disposal of dredged material in
accordance with section 103 of the Marine Protection,
Research, and Sanctuary Act and section 404(b)(1) of
the Clean Water Act.
EFQUAL
EFQUAL [full title: Analysis of Modified Elutriate Test
Results for Prediction of Effluent Water Quality and
Dilution Requirements for Confined Disposal Facilities,
provides a computer program to analyze the results of
modified elutriate tests and predict the chemical quality
of effluent discharged from confined disposal facilities
(CDFs) during hydraulic filling operations. Such predic-
tions are necessary to evaluate the acceptability of the
effluent discharge under section 404 of the Clean Water
Act The effluent may contain both dissolved and par-
ticle-associated contaminants. The modified elutriate
test was developed for use in predicting both the dis-
solved and particle-associated concentrations of con-
taminants in the effluent. Results of the modified elutriate
and column settling tests may be used to predict the
total concentrations of contaminants for a given set of
CDF operational conditions.
RUNQUAL
RUNQUAL [full title: Comparison of Predicted Runoff
Water Quality with Standards and Prediction of Dilution
Requirements] provides a computer program to analyze
the results of surface runoff quality tests and to predict
the chemical quality of the surface runoff discharged
from confined disposal facilities (CDFs). Such predic-
tions are necessary to evaluate the acceptability of the
surface runoff under section 404 of the Clean Water Act.
The surface water runoff may contain both dissolved
and particle-associated contaminants. Results of the
surface runoff quality tests and the column settling tests
may be used to predict the dissolved and total concen-
trations of contaminants for a given set of CDF opera-
tional conditions.
HELPQ
HELPQ [full title: Hydrologic Evaluation of Leachate
Production and Quality] couples the USEPA Hydrologic
Evaluation of Landfill Performance (HELP) model with
an equilibrium partitioning model for contaminant trans-
port. The model generates estimates of I each ate pro-
duction, collection and leakage from upland confined
dredged material disposal facilities as well as estimates
of contaminant concentrations and mass fluxes in the
leachate.
PUP
PUP [full title: Prediction of Contaminant Uptake by
Freshwater Plants] predicts the contaminant uptake from
dredged material by freshwater plants using DTPA ex-
tract data. The model compares the predictions with
reference sites to determine the acceptability of the
uptake in upland and flooded environments.
CDFATE
CDFATE [full title: Fate of Continuous Discharges from
Dredged Material Disposal for Estimating Mixing Zones,
predicts mixing zone requirements to meet water quality
standards or predicts compliance with water quality
standards given a mixing zone. The model is applicable
for nearly all continuous discharges from dredged mate-
rial disposal operations. The operations considered by
the module include discharge of effluents or runoff from
upland confined disposal from a weir, pipe, or stream;
leakage through porous dikes; overflows from hopper
dredges or barges; and discharge of dredged material
from a pipeline.
DREDGE
DREDGE [full title: Resuspension of Sediments and
Contaminants by Dredging] generates estimates of sus-
pended solids and contaminants released to the water
column during dredging and predicts dispersion.
LTFATE
LTFATE [full title: Long-Term Fate of Dredged Material
Disposed in Open Water\ predicts the erosion and dis-
persion of deposited dredged material and sediment by
storm waves.
MDFATE
MDFATE [full title: Fate of Dredged Material from Mul-
tiple Disposals in Open Watei\ predicts the develop-
ment, topography, and elevations of dredged material
mounds formed by multiple dumps from barges and
hopper dredges.
RECOVERY
RECOVERY [full title: Evaluation of Contaminant Re-
lease from Bottom Sediment^ predicts the diffusion of
contaminants from in situ sediments and capped sedi-
ments. It is useful to evaluate the bottom contaminant
flux from the "no action" alternative, capping alterna-
tives, and new exposure from dredging.
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LAT-E / LAT-R
LAT-E and LAT-R [full titles: Laboratory Analysis of
Toxicity from CDF Effluent/CDF Runoff are programs
for analysis of water column bioassay tests which com-
pute the toxicity (LC50) of CDF effluent or runoff dis-
charges.
Revisions, Updates, Availability, and
Workshops
The ADDAMS applications are revised and updated as
new technical approaches become available. New appli-
cations will be developed to address additional manage-
ment needs. Each application is designed as a module
so that revisions or the addition of new applications can
be easily accomplished. New users are provided with
the most current version of each respective application.
Version numbers are displayed on-screen for the
ADDAMS system and the various applications. An-
nouncements of revisions to specific applications and
for the entire system will be published in the Environ-
mental Effects of Dredging Programs' (EEDP) informa-
tion exchange bulletin and on the WES Dredging
Operations Technical Support (DOTS) World Wide Web
page (http://www.wes.army.mil/el/dots/dots.html).
The latest versions of ADDAMS applications and com-
puterized demonstration programs are available either
by mail or by electronic transfer from a WES FTP server
or the WES World Wide Web pages (http://
www.wes.army.mil/el/elmodels/index.htmltfaddams). In
addition, workshops are held on an as-needed basis to
provide Corps personnel with hands-on instruction of
the ADDAMS system. Workshops can also be arranged
for other governmental agencies. Training for both the
private and public sectors is presented at the USAGE/
USEPA Dredged Material Assessment and Manage-
ment Seminar which is held once or twice per year.
Requests for additions to the mailing list for the EEDP
bulletin or the technical note series and inquiries regard-
ing the scheduling of ADDAMS workshops should be
sent to the following address:
U.S. Army Engineer Waterways Experiment Station
ATTN: CEWES-EP-D
3909 Halls Ferry Road
Vicksburg, MS 39180-6199
References
1. Schroeder, P.R. and Palermo, M.R. 1995. "The
Automated Dredging and Disposal Alternatives
Management System (ADDAMS)," Technical Note
EEDP-06-12, U.S. Army Engineer Waterways Ex-
periment Station, Vicksburg, MS.
2. Department of the Army and U.S. Environmental
Protection Agency. 1992. "Evaluating Environmen-
tal Effects of Dredged Material Management Alter-
natives—A Technical Framework," EPA842- B-
92-008, Washington, DC.
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Overview of Ongoing Research and Development
Dennis L Timberlake
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
Cincinnati, OH
Introduction
The mounting evidence of the ecological risk associated
with contaminated sediments makes clear the realiza-
tion that remediation of contaminated sediments will
sometimes be necessary in order to control risks. With
this realization, however, comes the awareness that
many times effective techniques simply do not exist for
the management of contaminated sediments. A clear
need exists to conduct research into the development
and evaluation of sediment management techniques.
The following is a discussion of research and develop-
ment opportunities for the risk management of contami-
nated sediments. Specific lessons learned are presented
from EPA's National Risk Management Research
Laboratory's (NRMRL) experience in developing a re-
search program.
Rationale Behind Sediment Management
Research
While sediments are technically a type of soil, the two
are considered distinct media by the remediation com-
munity. When soils are referred to, it is generally in
reference to upland soils which are meant, while the
term sediments is used to refer to naturally deposited
material that exists in rivers, lakes, harbors, and marine
environments. A number of physical and chemical differ-
ences exist between soils and sediments which influ-
ence treatment technology efficiency:
* Moisture Content—-The moisture content of sedi-
ments is considerably higher than that of soils
necessitating the use of technologies that are
compatible with a high moisture content. Alterna-
tively, if technologies not compatible with a high
moisture content are utilized, the sediment will
have to be dewatered prior to treatment resulting
in increased processing costs.
Particle-Size Distribution—Sediments typically con-
sist of a high percentage of fine-grained material
(silts and clays) which can present material han-
dling difficulties for many treatment processes.
Organic Content—The organic content of sedi-
ments is typically higher than that of soil, resulting
in contaminants being tightly sorbed and creating
an increased oxygen demand for oxidative treat-
ment processes.
Contaminant Concentration—-The concentration of
contaminant in sediments requiring treatment is
typically lower than that encountered in soils re-
quiring treatment. Contaminants present in sedi-
ment are, in general, much more bioavailable than
contaminants in upland soils, resulting in relatively
low concentrations of contaminants displaying a
measurable impact on an ecosystem. Removing
relatively low levels of contaminant is difficult and
results in increased treatment costs.
Mix of Contaminants—Sediments serve as an
effective sink for hydrophobic contaminants, so
contaminated sediments usually contain a mix of
contaminants, both organic and inorganic. The
contaminant mix may require the use of multiple
treatment steps, thereby increasing remediation
costs.
Salt Content—Estuary and marine sediments have
a high salt content which can negatively impact
the efficiency of some treatment, processes such
as biological treatment.
Material Handling—The high moisture content,
presence of fines, and the presence of debris can
create material handling difficulties.
All of these physical and chemical factors differentiate
sediments from soils and have a negative impact on the
efficiency of most soil treatment technologies. The tech-
nologies that perform well with sediments typically do so
at an increased cost relative to the cost of treating
upland soils.
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Types of Sediment to be Managed
Sediments requiring treatment, or some other risk man-
agement approach, may be generated in two different
manners. First, historical pollution may have led to the
contamination of sediments in a river, lake, or harbor.
These sediments may serve as a significant continuing
source of organic and inorganic contaminants in many
freshwater and marine ecosystems. Removal and/or
treatment of the sediments may be necessary in order to
guarantee the future health of the ecosystem. The sec-
ond source of contaminated sediments is maintenance
dredging activities. In the course of keeping shipping
and docking channels open, sediments may be dredged
which are considered too contaminated for traditional
deep water disposal.
A research program for developing and evaluating tech-
niques for the management of contaminated sediment
must consider whether the sediments are the result of
maintenance dredging or remediation efforts. Issues
such as in-situ versus ex-situ management, cost con-
straints, time line for implementation, scale of operation,
and level of contamination are all influenced by the
reason for sediment management.
NRMRL's Program
NRMRL first became involved in sediment management
research through hosting a workshop on innovative
sediment treatment technologies. The workshop was
held in June, 1990 and was a success in bringing
together researchers and the community of technology
users. What became apparent during the course of the
workshop, however, was that while there were a number
of technologies which possibly could be effective in
treating sediments, there were no technologies avail-
able which were developed with the issues unique to
sediments in mind. The technologies which could be
applied to sediment risk management typically were less
cost efficient than when used in soil remediation.
In determining the allocation of a limited sediment re-
search budget, NRMRL concluded that the focus of
research should be on developing and/or evaluating
management solutions that address those problems
unique to sediments. NRMRL would develop new and
innovative approaches to sediment treatment. A positive
consequence of this decision was that low-cost tech-
nologies developed for sediment remediation might also
see application with upland soil sites.
NRMRL conducted an informal survey of EPA personnel
within Program Offices and the Regions plus a range of
experts outside of the Agency. People were asked to
identify the key risk management issues surrounding
contaminated sediments that needed to be addressed.
Three priority areas emerged from this effort: (1) in-situ
treatment, (2) the treatment of high volume/low concen-
tration sediments, and (3) in-situ containment.
NRMRL's current Contaminated Sediment Research Pro-
gram was initiated in FY96 and focuses on the develop-
ment of low-cost options for the management of
contaminated sediment resulting from maintenance
dredging operations and remedial actions. The program
has been designed by NRMRL to build upon existing
technical expertise developed through research into the
risk management of contaminated soils, but with the aim
of developing risk management solutions unique to con-
taminated sediments. Initial efforts consist of a number
of projects exploring the use of physical, chemical, and
biological treatment approaches. Since the program is
just beginning, initial efforts are necessarily laboratory-
scale and will address the fundamentals of contami-
nated sediment risk management. As research
progresses, however, it is anticipated that successful
projects will increase in scale, eventually up to the field-
scale level.
The Contaminated Sediments Research Program fo-
cuses on (1) the development and/or evaluation of in-
situ management approaches, (2) the development and/
or evaluation of technologies for treating sediment con-
taminants within Confined Disposal Facilities, (3) the
development and/or evaluation of affordableex-s/ft/tech-
nologies, and (4) research into the fate and transport of
contaminants in sediments. Another vital item, while not
research, is NRMRL's ongoing effort to provide techni-
cal assistance to the regions.
Future Research Directions
As has been stated, traditional ex-situ treatment tech-
nologies tend not to be cost-effective in sediment risk
management. While new ex-situ technologies will con-
tinue to be developed, it is unlikely that costs can be
reduced by an order of magnitude from current levels, a
step necessary for these technologies to compete with
options such as containment. Given the high price tag,
the use of ex-situ technologies will find the most applica-
tion in the remediation of hot spots.
While treatment resulting in the ultimate destruction of
contaminants may be the preferred risk management
option, the economics of contaminated sediment man-
agement often dictates the selection of other manage-
ment options. Containment, both in-situ and ex-situ, is a
traditional and cost-efficient management strategy and
the economics of sediment management suggest that it
will continue to be used in the future. Research, how-
ever, is needed to develop methods for quantifying and,
if need be, controlling contaminant releases and re-
claiming disposal facility capacity.
The development of in-situ treatment approaches, while
difficult, holds the promise of permitting large quantities
of contaminated sediment to be remediated in a cost-
effective manner.
The goal of the research community should be to pro-
vide decision makers with a range of solutions for the
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risk management of contaminated sediments. Risk man- nated sediment management situation. Recognizing this,
agement options should range from low-cost "partial" research programs can be designed to investigate the
solutions to high-cost "complete" solutions. There will entire range of options needed to address the risk
never be one silver bullet that works in every contami- management of contaminated sediments.
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Corps of Engineers Research Programs on Contaminated
Sediments
Norman R. Francingues
Chief, Environmental Engineering Division (EED)
U.S. Army Engineer Waterways Experiment Station (WES)
Vicksburg, Mississippi
Michael R. Palermo
Research Civil Engineer, EED, WES
Daniel E. Averett
Chief, Environmental Restoration Branch WES.
Robert M. Engler
Senior Research Scientist WES
Abstract
The U.S. Army Corps of Engineers (USAGE), along with
other federal agencies, such as the U.S. Environmental
Protection Agency (USEPA), has developed over the
last twenty-five years, a research base that emphasizes
the identification, assessment, and management of con-
taminated sediments. In this paper, the authors present
a brief overview of the research programs being con-
ducted by the USAGE on contaminated dredged mate-
rial and contaminated sediments. In the basic research
program, a risk-based approach to assessment and
evaluation, along with a preponderance of evidence is
the foundation for determining whether a sediment to be
dredged is suitable for placement in the ocean, estuary,
waterway, or upland environment in unrestricted dis-
posal or must be managed. In the applied research
programs, the emphasis is on moving technologies from
the laboratory to the field for the treatment and manage-
ment of contaminated sediments in the USAGE Civil
Works Programs. The authors conclude by emphasizing
the need to continue to conduct basic and applied
research on contaminated sediments to find solutions to
the contaminated sediment problem. The research should
include risk assessment, management techniques, and
full-scale demonstration projects to verify and refine the
basic research products.
Introduction
Navigation has long been a primary USAGE mission,
and the USAGE is viewed as the nation's dredging
agency. In many industrial and urbanized waterways,
we must dredge, transport, and relocate sediments to
perform our navigation mission. Some of these sedi-
ments are considered contaminated. The USAGE also
has a major regulatory role under Section 10 of the
Rivers and Harbors Act, Section 404 of the Clean Water
Act, and Section 103 of the Ocean Dumping Act, the
three principal laws which regulate dredging and dis-
posal of dredged material. Although only a small per-
centage of the sediments dredged to maintain navigation
on a nationwide basis is contaminated, the problem is
severe in certain areas, and the technical problems and
public perception associated with contaminated sedi-
ments affects the entire navigation program. There is
also concern that contaminated areas outside the navi-
gation channel are contributing to contamination prob-
lems within the channel.
Through the direction of the Congress, the USAGE has
developed a significant technical expertise in dredging,
dredged material disposal, and management of con-
taminated sediments to meet the needs of its navigation
program. Regulations, policies, and technical guidance
prepared and used by the USAGE are based on exten-
sive operating experience and results from comprehen-
sive research programs and project specific studies (1).
Over $125 million has been invested in research and
development on dredged material management, and
this effort has had significant influence on legislation,
regulations and international treaties concerned with
dredged material disposal.
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Background
Environmental research in the 1970s on sediments was
broad and included the basic understanding of ecologi-
cal Impacts associated with management of clean and
contaminated sediment. Research in the 1980s empha-
sized verification of improved tests and procedures for
the identification, assessment and management of con-
taminated sediment. Research in the 1990s focuses on
highly contaminated materials emphasizing chronic/sub-
lethal effects and genotoxicity evaluations, cleanup and
remediation of hot spots, risk analysis, endangerment
assessments, and treatment technology (1,2).
The need to continue research on the environmental
consequences of contaminated sediments was stated
by the USAGE during Congressional hearings in early
1980 and most recently in 1997. The Congress, as a
result of testimony received, has continued to express
concern over the long-term environmental effects of
contaminated sediments in our Nation's inland water-
ways, Great Lakes, estuaries and coastal harbors.
USAGE Environmental Effects of Dredging
Programs
The USAGE research on contaminated sediments is
managed and conducted by the U.S. Army Engineer
Waterways Experiment Station, WES, in Vicksburg, MS.
Corps of Engineers Dredged Material
Research Program (DMRP) (1973-1978).
The DMRP was a comprehensive nationwide research
program that evaluated the environmental effects of
various dredged material disposal options, including
open-water, upland, and wetland disposal. The program
concluded that no single disposal alternative is pre-
sumptively suitable for any given project (3). Included in
the DMRP were laboratory studies to determine the
amenability of contaminated dredged material to treat-
ment by physical or chemical processes. The conven-
tional treatment techniques available during the 1970s
were found not economically feasible or impractical
because of the relatively high solids content, low organic
content, high flow rates, and variable nature of dredged
material slurry. Most technologies applied to the treat-
ment of dredged material require temporary storage in a
confined disposal facility (CDF) to equalize dredge flows
and to pretreat or dewater the material. Settling and
consolidation processes, dewatering techniques, filtra-
tion technologies, particle separation technologies, and
effluent control measures investigated by this program
have application to treatment trains for contaminated
sediments.
Field Verification Program (FVP)
(1981-1987)
The FVP was a cooperative effort of the Corps and the
U.S. Environmental Protection Agency (4). FVP studies
compared placement of contaminated dredged material
in wetland and upland environments to aquatic disposal.
Contaminant losses were evaluated for each alternative.
Soil amendments and tolerant plant species were added
to an upland site to address stabilization of the surface
layer and minimization of contaminant mobility.
Long-term Effects of Dredging Operations
Research Program (1980-present)
LEDO activities are managed under the umbrella of the
USAGE Center for Contaminated Sediments at the Wa-
terways Experiment Station. The principal research ef-
fort is accomplished in the Long Term Effects of Dredging
Operations (LEDO) research program. This program
was initiated by Congress in 1980 because of concern
about the long-term environmental consequences of
dredged material disposal. The LEDO program is de-
signed to develop new or improved state-of-the-art tech-
nology for predicting long-term environmental impacts of
dredging operations and to improve and develop meth-
ods for minimizing any adverse impacts associated with
dredged material placement. LEDO is planned as a
continuing program, as applied environmental research
must be responsive to the dynamic nature of current
pollution problems and research priorities must as a
consequence be responsive to these needs.
The underlying premise of the research is to embody the
effects-based approach to evaluation of dredged mate-
rial. The determination that a sediment is contaminated
and unsuitable for unrestricted aquatic disposal is made
by application of effects-based testing and a preponder-
ance of evidence leading to a determination. The
effects-based approach has been developed by the
USAGE and USEPA over the past two decades and is
implemented through regulatory testing manuals and a
technical framework for dredged material management
(5).
Assessment and control technologies are required for
aquatic, wetland, and upland environments. Current re-
search emphasizes development and refinement of pre-
dictive tests for determining bioaccumulation and
consequences in aquatic organisms; techniques for pre-
dicting leachate quality from CDFs; relationships be-
tween sediment geochemistry and biological impacts;
evaluation of chronic sublethal and genotoxic effects of
contaminated material; and investigation of physical,
chemical, and biological processes for contaminant con-
trol at CDFs.
Water Resources Development Act of
1990, Section 412(c) (1991-1994)
The USAGE studied options for treatment and disposal
of contaminated sediments from New York/New Jersey
Harbor as part of the Section 412 studies. Available
technologies for treatment of dioxin-contaminated sedi-
ment were reviewed, and bench-scale evaluations for
four treatment technologies were completed (6). Solvent
98
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extraction, incineration, and base-catalyzed destruction
were effective in removing or destroying dioxins in this
marine sediment.
Alternatives were developed for six treatment technolo-
gies and three disposal alternatives and were compared
on the basis of effectiveness, implementability, and costs.
Treatment alternatives were projected to be at least an
order of magnitude higher in cost than disposal alterna-
tives.
Dredging Operations and Environmental
Research Program (1997-Present)
The Dredging Operations and Environmental Research
Program (DOER) was established by the USAGE to
address critical field needs in finding solutions to dredg-
ing related problems in the Nations's navigation system.
The objective of DOER is to balance environmental and
operational requirements while economically maintain-
ing a viable navigation system. Research is required to
address operations and environmental demands in six
major focus areas: contaminated sediment character-
ization and management; instrumentation for monitoring
and site management; near-shore and aquatic place-
ment of dredged materials; environmental windows for
dredging operations; innovative equipment and tech-
nologies demonstration; and, environmental risk man-
agement for dredging and disposal activities. Benefits
will include application of environmental windows,
cost-effective identification and management of con-
taminated sediments, greater flexibility for dredging in
sensitive ecological areas, and expanded options for
beneficial uses of dredged materials. Major program
goals for FY 1997 include selection of cost-effective
sediment screening test methods for.dioxins and investi-
gations to establish accuracy, precision and analytical
costs; established guidance for suitable environmental,
economic and engineering factors for site selection for
nearshore beneficial placement of dredged sediments;
selection of basic ecological risk assessment frame-
works for contaminated dredged material for detailed
development, in conjunction with EPA; and survey of
critical fiscal and managerial aspects of seasonal envi-
ronmental dredging restrictions.
Overview of DOER Contaminated
Sediments Focus Area
Two of the most commonly considered alternatives for
contaminated sediments are placement in confined dis-
posal facilities (CDFs) and capping, an option for con-
tainment in subaqueous sites. CDFs are located on land
or in areas of relatively sheltered water. Many CDFs are
near closure; future CDF locations may include nontra-
ditional areas such as offshore. Treatment to reclaim
CDF capacity may be promising for certain sites. Cap-
ping has significant potential as a disposal alternative,
but issues related to its long-term effectiveness and
potential application to deeper waters or high-energy
environments require additional environmental investi-
gation. DOER will address high-priority research needs
aimed at reducing costs associated with screening, as-
sessing potential impacts associated with contaminants,
and increasing the reliability and acceptability of CDF
and capping options for management of contaminated
sediments.
The DOER Contaminated Sediments Focus Area is
addressing high-priority field needs in this area. DOER
will develop low-cost, rapid, and interpretable biological
screening methods for chlorinated hydrocarbons and
other contaminants. These methods will reduce the
number and cost of chemical analyses and quickly
identify contaminated sediments and marginally con-
taminated dredged material in existing CDFs that can be
reused. Tiered screening tools will be developed for
estimating contaminant losses from CDFs and capped
sites in order to reduce the need for more expensive
environmental testing. Techniques requiring minimal data,
such as bulk sediment chemistry, will be emphasized
and developed for implementation on desktop comput-
ers.
Research will develop risk-based assessments for con-
taminated dredged material for both open water and
CDF placement options. The risk assessment process
for contaminated sediments includes effects and expo-
sure assessment (e.g. contaminant pathway testing).
Results of risk-based assessments facilitate risk man-
agement which; for contaminated dredged material, may
include identification of design requirements for con-
taminant controls and treatment. Effects assessments
for dioxin contaminated dredged material will tie directly
into the overall environmental risk assessment frame-
work developed under the DOER focus area on risk.
Effects data from laboratory testing will be compared
with field measurements of effects on populations of
organisms in areas where sediments are contaminated
with chlorinated hydrocarbons (dioxins). Cost-effective
laboratory test procedures and predictive tools for expo-
sure assessment will address CDF groundwater leachate,
surface runoff, and volatile pathways.
CDF research will develop and validate contaminant
controls, treatment methods, and management tech-
niques. Design of CDFs as treatment structures, ground-
water and surface water protection, and overall
contaminant retention will be emphasized. Design crite-
ria for treatment and/or control of toxic contaminants will
be developed including low-cost, effective methods for
CDF management to meet State Water Quality Certifi-
cation requirements. Research on filtration treatment
structures and enhanced biodegradation of contami-
nants in CDFs will receive the highest priority. Tech-
niques for reclamation of CDF capacity will be developed
for sites with materials marginally contaminated with
chlorinated hydrocarbons. Tools for predicting capped
material chemical migration will be refined and used as
a basis for more cost-effective capping designs. Re-
search on environmental aspects of capping and CDFs
will be integrated with research on physical aspects
under the DOER Nearshore and Offshore Placement
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focus area to provide comprehensive guidance for these References
management options. Laboratory studies and technical
assessment of control and containment technologies for 1.
open water disposal other than capping will also be
conducted.
Benefits will include the ability to improve the
cost-effectiveness of identification and assessment pro-
cedures, to reuse existing disposal capacity for contami-
nated materials, and to design and manage disposal
facilities for enhanced capacity, treatment, and contain- „
ment objectives.
Summary
There are millions of cubic yards of contaminated sedi-
ments in the waters of the United States requiring dredg-
ing as part of a navigation project or for environmental
cleanup. Innovative solutions will need to be developed,
or costs will escalate and inhibit any real progress. 3.
The USAGE and other federal agencies over the past
twenty-five years have developed a significant research
base on the effects of contaminated sediments when
dredged for the purpose of navigation and sediment
remediation. However, the emphasis must shift from
studying the problems to finding solutions. Now, more
than ever, the USAGE and USEPA need to continue to
conduct intensive basic and applied research on con-
taminated sediments to find workable solutions to the
problem. The research should include risk assessment,
management techniques, and full-scale demonstration
projects to verify and refine the basic research products.
Future research and development expenditures will pro-
duce direct benefits in many areas, including reduced
testing costs and more cost-effective project selection
and Implementation. Detailed information on USAGE
dredging research can be found on the WES Dredging 5.
Operations Technical Support (DOTS) homepage at
www.wes.army.mil/el/dots.
Acknowledgment
This paper summarizes research conducted by the
USAGE under a variety of research programs. The
technical summaries were based on research investiga- 6.
tions being conducted under the USAGE Environmental
Effects of Dredging Programs at the U.S. Army Engineer
Waterways Experiment Station, Vicksburg, MS. Permis-
sion to publish this material was granted by the Chief of
Engineers.
4.
Engler, R. M., Patin, T. R., and Theriot, R. F.
1990. "Update of the Corps' Environmental Ef-
fects of Dredging Programs (FY89)," Miscella-
neous Paper D-90-2, U.S. Army Engineer Water-
ways Experiment Station, Vicksburg, MS.
Engler, R.M., Francingues, N.R., and Palermo,
M.R. 1991. "Managing Contaminated Sediments:
Corps of Engineers Posturing to Meet the Chal-
lenge," World Dredging and Marine Construction,
August 1991.
Saucier, R. T., Calhoun, C. C., Jr., Engler, R. M.,
Patin, T. R., and Smith, H. K. (1978). Dredged
Material Research Program Executive Overview
and Detailed Summary, Technical Report
DS-78-22, U.S. Army Engineer Waterways Ex-
periment Station, Vicksburg, MS.
Peddicord, R. K. (1988). Summary of the U.S.
Army Corps of Engineers—U.S. Environmental
Protection Agency Field Verification Program,
Technical Report D-88-6, U.S. Army Engineer
Waterways Experiment Station, Vicksburg, MS.
USEPA and U.S. Army Corps of Engineers. (1992).
Evaluating Environmental Effects of Dredged Ma-
terial Management Alternatives—A Technical
Framework, EPA 842-B-92-008, Washington, DC.
Tetra Tech, Inc., and Averett, D. F. (1994). "Op-
tions for Treatment and Disposal of Contaminated
Sediments from New York & New Jersey Harbor,"
Miscellaneous Paper EL-94-1, U.S. Army Engi-
neer Waterways Experiment Station, Vicksburg,
MS.
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Potential for Phytoremediation of Contaminated
Sediments
Steven A. Rock
Environmental Engineer
Land Remediation and Pollution Control Division
National Risk Management Research Laboratory
United States Environmental Protection Agency
Cincinnati, OH
Abstract
Phytoremediation is an innovative technology that is
being applied to soil and groundwater cleanup. Tech-
niques for using plants for remediation are gaining regu-
latory and commercial acceptance in the U.S. This
paper considers the potential for application of phytore-
mediation to the remediation of contaminated sediments,
projecting from what is known about plant -contaminant
mechanisms.
The use of plants to remediate soil and groundwater
problems has been studied for many years and is being
applied nationally. Some of the mechanisms that have
been identified may be applicable for use in sediments.
Planting a contaminated sediment with shallow water
wetland plants or deeper water emergent plants can
form a vegetative root mass that acts as a cap to prevent
movement of the sediment or contaminant while biore-
mediation is occurring. A dense root mass not only holds
existing sediments in place, it collects and gathers sedi-
ments that had been held in suspension, adding to the
protective cap over the contamination.
Vascular plants release oxygen and enzyme exudates
from their roots. Some plants that grow in aquatic envi-
ronments along streams, river banks, and in lakes may
release enough oxygen and exudates into the subsur-
face sediments to promote contaminant degradation.
Background
The term phytoremediation applies to the use of a wide
variety of plants to remediate an equally wide variety of
contaminants. Prairie grasses have been studied to
reduce concentrations of polyaromatic hydrocarbons
(Aprill). Poplar trees have been shown to reduce excess
fertilizer, pesticides and herbicides from agricultural run-
off (Licht). Cottonwood trees are being used to intercept
a TCE groundwater plume. Some plants have been
shown to degrade PCBs from transformers (Fletcher).
Ryegrass has been shown to reduce PGP and creosote
from a wood preserving site (Ferro). Various grasses
and field crops have been studied to measure their
effect on petroleum contamination in soil (Banks). Indian
Mustard can extract heavy metals such as lead, and
chromium (Raskin), and sunflowers have been shown to
concentrate uranium in their roots (Dushenkov). Wet-
lands can be used as phytoremediation processes. Con-
structed wetlands planted with reeds and cattails are
used to prevent acid mine drainage from polluting
streams. Other wetlands plants such as duckweed are
also being studied to degrade TNT and its breakdown
products.
Phytoremediation seems to be best suited for cleanups
over a wide area, with contaminants in low-to-medium
concentrations. If the concentration of contaminants is
too high, phytotoxicity results, with no or poor plant
growth. The plant roots physically must contact or be in
very close proximity to the target contaminant, so the
media to be cleaned must be within range of the root
growth. Planted areas can be used in conjunction with
other technologies, for example, following a removal
action of high contaminant concentration once these hot
spots are removed.
Phytoremediation Mechanisms
Because the term phytoremediation covers a range of
plants remediating a range of contaminants, there are
different mechanisms used for different types of phyto-
remediation. Some plants in some instances may use
more than one mechanism either sequentially or simul-
taneously. The mechanisms that various plants use in
phytoremediation can be classified into four broad cat-
egories.
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Enhanced Rhizosphere Biodegradation
Phytodegradation
• Physical Effects
• Accumulation of metals
Enhanced rhizosphere biodegradation is a series of
effects that plants have on the microbial population in
the rhizosphere (the immediate area surrounding the
root). There is some symbiosis which occurs between a
plant and its microbial neighbors. Microbial populations
have been reported to be two orders of magnitude
higher In the soil of the root zone than in adjacent
implanted soil (Schnoor). The limiting factors for most
aerobic microbial consortium growth include oxygen,
nutrients, and water (Cunningham). The roots of many
plants provide these requirements to the microbial zone
as a byproduct of normal plant growth. As roots pen-
etrate and loosen the sediment there is passive aera-
tion, and active aeration as the roots release oxygen as
part of normal plant respiration. Wetland plants have
been examined for their ability to release oxygen from
roots (Armstrong, Brix 90, Michaud). The mechanisms
of oxygen transfer have described by Brix.
As a natural function of reacting to changing environ-
mental conditions, parts of plant roots die off during
seasonal water and temperature fluctuations (Ander-
son). These abandoned or sloughed roots and root hairs
become a nutrient source to the rhizosphere microbial
community. These nutrients may serve as cometabolites,
sustaining microbes that incidentally degrade contami-
nation as part of their metabolism, as in the degradation
of PCBs (Lee).
Phytodegradation is the process of the plant itself de-
grading the contamination. This may occur as metabo-
lism of a contaminant within the plant, or by transforming
or mineralizing it to a less toxic form through exudates.
Various plants produce different enzymes, many of which
are useful in the destruction of contaminants.
Nitroreductase, dehajogenase, peroxidase, and others
have been found to b'e exuded by some plants (Bollag,
Schnoor). These enzymes can either detoxify a con-
taminant, or render it vulnerable to microbial consump-
tion. At the Iowa Army Ammunition Superfund Site,
where wetland phytoremediation was chosen as part of
the Record of Decision (ROD), 18 of 42 plants screened
were shown to contain the enzyme nitroreductase, a key
element in the degradation pathway of TNT, the target
contaminant (Camera).
One physical effect plants can have on contaminated
sites is erosion control. Vegetation has long been used
to prevent soil from washing or blowing away, with the
dust bowl of the 1930s as an example of what happens
when the role of vegetation in soil conservation is ig-
nored. Hazardous wastes and municipal landfills can be
covered and capped with soil and plants, a process also
known as forming a vegetative cap. A vegetative cap
consisting of grasses, clovers, shrubs and trees is being
used to prevent both wind and water erosion on a
Montana mining site. Caps consisting of trees and grass
have been used to cap municipal landfills (Licht). In
Texas a lagoon of hazardous waste has been naturally
vegetated, and now measures a three-foot soil layer
(Fletcher).
Some plants do accumulate heavy metals in their roots
(Dushenkov) and stems and leaves (Chaney, Raskin).
These plants and these contaminants are not appropri-
ate candidates for a vegetative cap. Plant do not tend to
accumulate organics within the plant structure as do
some metals (Banks). Therefore if contaminated sedi-
ments can be contained, the environment can be pro-
tected, and the ecosystem can be restored. A vegetative
cap could promote a diverse ecosystem on top of a
contaminated layer.
Phytoremediation of Sediments
Sediments with organic contaminants are hazardous to
human health and the environment through two path-
ways; through suspension in the water table and con-
sumption of that water directly, or by suspension and
consumption by fish and other aquatic species.
Conventional technologies try to block these pathways
either by removing sediments (dredging), covering them
with clean soil (thin or thick cap), or by covering them
with soil and concrete and metal pieces called rip-rap or
armoring (Lee, M). Dredging and armoring are expen-
sive options, and capping without an armor layer is
subject to washout during storm events.
Shallow freshwater vegetative caps may be established
to accomplish the same pathway blocking function. By
forming an interlocking root mat the plants will tend to
hold the sediments in place. Flowing water is slowed
passing through vegetated wetlands as compared to
unplanted areas, increasing sediment deposition (Brown).
Suspended solids attach to plants stems and are later
added to the sediment layer. As plants drop leaves and
stem material, this build up of organic matter further
contains suspended soil particles.
Once established, these plants can grow for many years,
propagating themselves, slowly degrading compounds
while providing a vegetative cap for the site to hold
contaminants in place to limit the possibility of human or
ecosystem exposure. As the plants grow, drop vegeta-
tive matter, and collect sediments the protective cap will
continue to become thicker and more resistant to distur-
bance.
Sediments are anaerobic except in the upper layer
adjacent to water. Dissolved oxygen of approximately
8.0 mg/l in water, slow oxygen diffusion into sediments,
and slow diffusion of contaminants to the sites of micro-
bial activity limit the kinetically more-rapid aerobic deg-
radation processes. The mass transport limitations reduce
bioavailability and increase the persistence of aerobi-
cally degradable organic contaminants in sediments.
102
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Many contaminants which are persistent in an anaerobic
environment are available to aerobic degradation if an
effective and economical means of delivering oxygen to
the site of microbial activity were available. One possible
technique for delivery of oxygen to contaminants below
the water-sediment interface is by utilizing the natural
tendency of vascular plants to release oxygen from their
roots as part of their respiration cycle (Brix 93).
Wetland technology is steadily growing in the United
States for wastewater and pollution control (Brown).
While the knowledge base is increasing on how to use
plants in wetland configurations, planting for aquatic
vegetative caps for containment or remediation of sedi-
ments has not been implemented to date.
Plant Selection
Many species of submerged or emergent wetland plants
may be considered for phytoremediation. The selection
of an appropriate set of plants adapted to the exact site
conditions is crucial to the successful application of the
technology. Plants must be adapted for the water and
climatic conditions, whether shallow or deeper water or
fluctuating water levels. Final plant selection for a project
will depend on plant tolerance to the contaminant in the
sediment. Each candidate plant species should be sub-
jected to the phytotoxicity testing, consisting of measur-
ing seed germination and root elongation in various
concentrations of the contaminated sediments.
Plant selection for a field application of a vegetative cap
will depend on many factors besides the plants ability to
grow in a contaminated sediment. A variety of factors
would have to be balanced: for example, the common
reed Phragmites austalishas little food value for wildlife,
which is a negative attribute if one of the goals of the site
is increasing wildlife habitat. Phragmites is preferred for
some constructed wetlands precisely because it is not
an attractive food source, and not is not a target for
consumption. Animal predation can make environmen-
tal engineering with planted systems less predictable.
Bulrushes or cyperus could be used to represent plants
which grow in shallow water. These fast growing, fast
spreading plants thrive in up to two feet of water. They
are hardy and likely to survive fairly high concentrations
of pollutants and have a habitat range from Maine to
Florida, and from East to West Coast.
Another species that may be used is Vallisnera
americana, also known as eelgrass, tapegrass, or wild
celery. This plant grows in water to twelve feet deep. Its
range is also widespread; from Maine to Florida, and
from North Dakota to Texas. The vegetation of the plant
is flexible enough not to cause a navigation hazard,
although boat traffic can damage the plants. If Vallisneria
can be shown to help remediate sediments in situ at
normal growth depths, a large number of sites could
benefit.
Plant screening and selection will be an important com-
ponent of any project. The selection may be based on
one or more of the following criteria:
a. Plants that are likely to be viable under the condi-
tions of the study and eventually in the field.
b. Plants that form a dense sediment retentive cap
(plants that form dense root masses of the appro-
priate depth, appropriately dense masses of shoots
that will facilitate the deposition of sediment from
flowing water)
c. Plants that provide some habitat value or that at
least are not objectionable because of invasive or
noxious attributes.
d. Plants that are potentially good oxygen pumps
Initial selection can be made using the peer-reviewed
literature and consultation with researchers, plant sup-
pliers and vendors. After the candidate plant species
target is identified, phytotoxicity tests using the site
specific sediment should be initiated.
Analysis of plant enzymes may be an important compo-
nent in determining appropriate plant selection. Enzyme
analysis of a candidate species could be performed
either at the USEPA Lab in Athens, GA, with Dr. Steve
McCutcheon, or with Dr. Laura Carriera at the
PhytoWorks Laboratory.
Measuring Phytoremediation Effects in
Sediments
Various test are available to evaluate the progress of
phytoremediation in a sediment environment. Changes
in contamination levels may not be apparent for several
years, but other changes can be gauged by monitoring
treatment progress and differences of sediment COD
and sediment TPH. Data on bioaccumulation and phyto-
toxicity assays can be determined over the course of
time, In addition, the changes in EMF measurements
and three sets of phospholipid fatty acid analyses (PLFA)
can be used to evaluate the changes in the microbial
populations in the rhizosphere of the plant roots.
Sediment transport and containment in planted areas
can be characterized and compared to corresponding
sediment transport in unplanted controls. The speed
and volume of water moving will produce a range of flow
conditions. Containment measurements can be achieved
by regularly measuring turbidity, and the amount of
sediment captured or eroded can be assessed by fixed
depth measurements.
Sediment contaminant remediation can be expected to
take place as a result of several of the previously
discussed possible plant mechanisms. To examine the
role of plant uptake of contaminant, tissue of shoots and
leaves should be analyzed for the contaminant of inter-
103
-------
est. To examine the role of metabolism within the plant,
the leaf and shoot analysis should also search for break-
down products of aerobic degradation. Enhancement of
microbial remediation in the rhizosphere can be studied Conclusions
by fatty acid methyl ester analysis. This analysis will
show changes in microbial populations, both quantities
and constituents, and give an indication of an increase
in degrader population.
been designated an area for testing and evaluating
alternative sediments handling.
Contaminant toxicity should be measured to determine
the effect of the remediation. Carolyn Acheson and
others at the USEPA NRMRL Laboratory in Cincinnati,
OH, have found that decreased toxicity and reduction of
contaminant concentration do not always correspond
linearly. Invertebrate toxicological tests and plant root
elongation tests are common tests for determining ter-
restrial toxicity. Fish toxicity tests may be more appropri-
ate for sediments tests.
Fixed electromotive force (EMF) probes have been used
by Greg Sayres, et al, of the USEPA NRMRL Laboratory
In Cincinnati, OH, for measuring subsurface oxygen
changes. Probes can be installed at various depths and
various distances from the plants-to assess the
rhizospheric change in anaerobic/anoxic/aerobic condi-
tions as measured by electrical potential.
Specific Research Efforts on
Phytoremediation Effects in Sediments
Research divisions with USEPA ORD/NHEERL are in-
volved in many lines of sediment research that are
directly related to potential phytoremediation of sedi-
ments research. NHEERL scientists have developed
several sediment toxicity test methods to assess toxicity
of contaminated sediments, some of which are pro-
posed for use in the present study. Other NHEERL
research involves determining sediment phases that
control the bioavailability of organic contaminants in
sediments (primarily organic carbon), and using this
understanding to predict the toxicity of sediments based
on chemical composition.
The experience of the Waterways Experiment Station
(WES) of the Army Corps of Engineers in constructing
and testing wetlands could be extremely valuable in
determining plant selection and aquacultural consider-
ations.
Several organizations including Tennessee Valley Au-
thority (TVA) and WES have experience in wetland
construction and maintenance for treatment of contami-
nated groundwater. Their constructed wetland facility at
Milan, TN, has been operating since 1996 treating
groundwater contaminated with TNT and its breakdown
products.
Washington State Departments of Transportation and
Ecology are jointly engaged in searching for alternatives
to conventional dredging and capping in the waterways
in and around the Puget Sound. Bellingham Bay has
It is hypothesized that establishing wetland plants in a
sediment will decrease the mobility of the sediment and
hence its bioavailability compared to unplanted sedi-
ments. The main objective of a vegetative or any other
cap is to prevent the movement or reentrainment of
sediments in the water column and to accelerate the
deposition of entrained sediments. In the case of con-
taminated sediments, the accelerated deposition of fresh
sediments over contaminated areas promotes the natu-
ral recovery of the area.
If it provides an equally effective alternative to conven-
tional techniques of dredging, capping and armoring, a
vegetative cap would be more economical than conven-
tional methods. It would offer wildlife habitat benefits by
providing food and shelter for fish, birds, and other
animals. A vegetative cap avoids the problem of
resuspension of contaminants that occurs during dredg-
ing and armoring installation.
It is possible that phytoremediation mechanisms, which
may include oxygenation, root enzyme production, plant
uptake of contamination, and in-plant metabolism will
decrease contaminant concentration compared to
unplanted sediments. Phytoremediation of sediments
will have many of the same advantages and disadvan-
tages of phytoremediation of soils and groundwater:
decreased cost but longer time frames, possibly widely
applicable, but as yet unproven.
A key indicator of a healthy ecosystem is a sustainable
and diverse population of plants. Plants not only indicate
the health of an ecosystem, they provide much of the
structure of an ecosystem. A planted sediment zone
tends to add sediment layers as compared to an
unvegetated shallows, which encourages other plant
growth and animal utilization.
•If the health of an ecosystem can be assessed by the
size and diversity of the population of plants and animals
then if the remediation of an area directly causes an
increase in appropriate plant and animal populations,
ecosystem restoration has begun to occur. Conven-
tional technologies of sediment containment are specifi-
cally destructive to plant and animal habitat in rivers,
lakes, and coastal areas. Developing a containment
technology that is as effective as the best conventional
treatment at preventing contact between contaminants
and at-risk population, is less expensive and hence
more widely applicable, and also creates the very condi-
tions of ecosystem restoration, is one of the goals of
EPA research.
If successful, phytoremediation may be shown to pro-
vide an in-situ method for managing large volumes of
contaminated sediment for affordable ecosystem resto-
ration and environmental protection. Small- and full-
104
-------
scale research is still to be done to determine if that
potential will be realized.
References
1. Anderson, Todd A. 1996. Rhizosphere technology
for Phytoremediation International Phytoremedia-
tion Conference, Arlington, VA.
2. Aprill, W., and R.C. Sims. 1990. Evaluation of the
use of prairie grasses for stimulating polycyclic
aromatic hydrocarbon treatment in soil. Chemo-
sphere, 20:253-265.
3. Armstrong, W.; Armstrong, J.; Beckett, P.M. Mea-
surement and Modeling of Oxygen Release from
Roots of Phragmites austalis. J Tissue Cultures
Assn, 29:207-212.
4. Brown, Donald S.; Reed Sherwood C. 1994. In-
ventory of Constructed Wetlands in the U.S. Wa-
ter Science Tech. Vol. 29 No. 4 pp 309-318
5. Brix, Hans; Schierup, Hans-Henrik. 1990. So/7
Oxygenation in Constructed Reed Beds: The Role
ofMacrophyte and Soil-Atmosphere Interface Oxy-
gen Transport Constructed Wetland in Water Pol-
lution Control, P.P. Cooper ed. Pergamon Press,
Oxford.
6. Brix, Hans. 1993. Macrophyte-Mediated Oxygen
Transfer in Wetlands: Transport Mechanisms and
Rates. Constructed Wetlands for Water Quality
Improvement, CRC Press.
7. Bollag, Jean-Marc. 1992. Decontaminating Soil
with Enzymes. Environ. Science Technology, Vol.
26, No.10.
8. Camera, L. H. 1997. "The Use of Antibody Assays
to Predict Plants Capable of Phytoremediation"
The Second International Phytoremediation Con-
ference, Seattle, WA. International Business Com-
munications, Southborough, MA.
9. Chaney, R.L. 1983. Plant uptake of inorganic
waste constituents. In: Land Treatment of Hazard-
ous Wastes, J.F. Parr et al. (eds.). Noyes Data
Corp., Park Ridge, NJ, pp. 5076
10. Cunningham, Scott; Berti, William. 1993.
Remediation of contaminated soils with green
plants: An overview. In Vitro Cellular & Develop-
mental biology-P\ant 29P (4): 227 -2 32 1993
11. Dushenkov, Viatcheslav; Kumar, P. B. A. Nanda;
Motto, Harry; Raskin, llya. 1995 Rhizofiltration:
the Use of Plants to Remove Heavy Metals from
Aqueous Streams Environ Sci Technol v29, n5,
p1239(7) May.
12. Ferro, Ari. 1997. Report on Reclamation of PGP
Contaminated Soils Using Plants. Unpublished.
13. Fletcher, J. 1997. The Role of Phytoremediation in
Intrinsic Bioremediation In Situ and On Site Biore-
mediation: Vol. 2, Batelle Press.
14. Lee, Euisang; Banks, M. K., Kansas State Univer-
sity. 1993 Bioremediation of Petroleum Contami-
nated Soil Using Vegetation: A Microbial Study J
Environ Sci Health-Em\ron Sci Eng vA28, n10,
p2187(12)
15. Lee, M., Bowen B., Washington Dept. Of Trans-
portation Personal communication 1997
16. Michaud, Susan; Richardson, Curtis. 1993. Effi-
ciencies of Substrates, Vegetation, Water Levels
and Microbial Populations: Relative Radial Oxy-
gen Loss in Five Wetland Plants, Constructed
Wetlands for Wastewater Treatment, CRC Press.
17. Raskin, I., P.B.A.N. Kumar, S. Dushenkov, and
D.E. Salt. 1994. Bioconcentration of heavy metals
by plants. Current Opinion in Biotechnology.5:285
18. Schnoor, Jerald L., University of Iowa, Iowa City;
Licht, Louis A.; McCutcheon, Steven C.; Wolfe, N.
Lee; Carreira, Laura H. 1995. Phytoremediation of
Organic and Nutrient Contaminants Environ Sci
Technol\/29, n7, p318A(6) July.
105
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Treatment of Metal-Bearing Solids
Using a Buffered Phosphate Stabilization System
Thomas Stolzenburg, Senior Applied Chemist
RMT, Incorporated
Madison, Wl
introduction
Solid wastes or metal-impacted soils can be classified
as hazardous by their leaching characteristic. The test
protocol used for classification is the Toxicity Character-
istic Leaching Procedure (TCLP). The TCLP was to
designed to predict potential mobility (dissolution) of
metals after disposal, particularly after co-disposal with
other wastes in a municipal landfill. The acetic acid used
in a TCLP represents the organic acids encountered in a
municipal landfill environment.
In many cases, metal-bearing solids are not co-disposed
in a municipal landfill, or in the case of sediments, may
even remain in place. The potential for leaching metals
from these solids is more appropriately modeled with
simulated rain water or site-specific water. Simulated
rain water leaching is accomplished by using the Syn-
thetic Precipitation Leaching Procedure (SPLP).
Conceptually, a wide variety of treatment alternatives
are available to treat metal-bearing solids so that the
residue is nonhazardous by leaching characteristic.
These alternatives include:
• Solidification
• Stabilization
pH Control
Chemical Fixation
• Vitrification
• Physical Separation
* Thermal Separation
Chemical Extraction
However, from a economic perspective, any ex-situ
process will usually cost more than an in-sltu process for
several reasons. In most cases, permitting requirements
are more extensive for ex-situ treatment. Each materials
handling step in an ex-situ remediation accounts for a
significant additional cost. Transport and disposal of
residues is another add-on cost not associated with in-
situ treatment.
Not all in-situ treatment alternatives are necessarily
economical either. For instance, volume increases as-
sociated with chemical addition that causes bulking may
represent an intractable full-scale dilemma. Also, exces-
sive energy requirements or impractability of mixing or
chemical delivery can preclude cost-effective implemen-
tation of in-situ treatment alternatives. For many of these
reasons, in-situ chemical stabilization is conceptually
one of the best treatment alternatives for treating
metal-bearing solids.
Not all RCRA metals exhibit similar chemistry, and
therefore would not respond similarly to a single chemi-
cal stabilization technology. Of the RCRA metals, lead
has attracted the most regulatory concern, primarily
because of its widespread release into the environment.
Sources of lead in contaminated solids, soils, and sedi-
ments include:
Iron foundries
Steel mills
Brass foundries
Smelters
Battery recyclers
Leaded paint
Shooting ranges
• Mine tailings
Lead arsenate pesticides
• Ash
Some of the chemical stabilization alternatives available
to treat lead include:
106
-------
pH Control
Lime
Carbonates: limestone, dolomite
Magnesium oxide
Chemical Fixation
Iron Hydroxides
Phosphates
Sulfides: dithiocarbamates
Chemical Reduction
Metallic iron
This paper discusses the use of a pH-buffered phos-
phate chemical fixation system for treating solids im-
pacted with lead, cadmium and/or zinc (zinc leaching
does not cause a solid to be classified as hazardous, but
it is nevertheless problematic in some cases, and treat-
able by the described process). The described process
is effective at rendering lead and cadmium solids non-
hazardous by the TCLP, and it is also effective at
minimizing metal solubility under rain water and/or ambi-
ent water leaching conditions. This process has been
applied ex situ and in situ at full-scale at hundreds of
sites, and has been applied to sediments at a few sites,
which will be described here.
Chemistry of Lead, Cadmium, and Zinc
Certain metals exhibit an amphoteric behavior; that is,
they are highly water-soluble at both low and high pH
conditions. This is a generalization that does not fully
account for the various solid phases that can form for
any particular metal. However, it is a good rule of thumb
for understanding lead chemistry.
Figure 1 shows the solubilities of various lead solid
phases. A classic amphoteric pattern is illustrated. Of
equal importance to note is that, depending on the
combining anion, a lead solid phase may exhibit more or
less water solubility than the hazardous waste limit of 5
mg/L. Therefore, both pH and the associated anion
strongly influence lead solubility.
Lead in solid wastes in the environment often occurs as
lead hydroxide, lead oxide, or lead sulfate. All of these
forms of lead are rather soluble compared to some other
forms of lead, such as lead carbonate or lead phos-
phate. As might be predicted, if lead occurs in a solid as
lead hydroxide, that solid is often characterized as haz-
ardous in the TCLP (note how high the solubility of lead
hydroxide is at the low pH conditions of the TCLP).
10000000
100000
o
'o3
CD
O
c
o
O
T3
CO
CD
1000
10
0.1
0.001
0.00001
1 • ' 1 • I •
:\ v : -f - 7
V,;\ \ / '•/;
^ \ \j jf
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pH
Figure 1. Solubility of lead species as a function of pH.
107
-------
The solubility of cadmium in water is also highly depen-
dent on pH and on the associated anion forming the
solid phase. Figure 2 shows the pH-solubility pattern for
various cadmium species. Note that cadmium is not
strongly amphoteric. If cadmium species exhibits higher
solubilities at high pH conditions, then it is only at
extreme values.
Figure 3 is a smoothed plot of data for hundreds of
sampling points for zinc-impacted solids at a site. De-
spite the fact that compositional zinc concentrations and
the anion composition were highly variable, the data
showed a remarkable adherence to the graph. As can
be seen, zinc exhibits an amphoteric behavior similar to
that of lead.
00 0.001
0.0001
10
PH
Figure 2. Solubility of cadmium species as a function of pH.
0)
O
1
O
O
N
650 —I
65 -
6.5-
0.65-
0.065 —
7
8
10
I
11
I
12
PH
Figure 3. Zinc-contaminated site soils—zinc solubility curve.
108
-------
Figure 4 is a plot of actual data for leachable lead in
foundry wastes. Once again, the data are remarkably
consistent to a single pH-solubility curve.
Table 1 lists leachable lead data for both TCLP and
SPLP tests of untreated and treated lead-bearing smelter
waste. The data dramatically illustrate the amphoteric
behavior of lead. High pH treatment additives, such as
lime or cement, are successful in lowering the pH in the
TGLP, and rendering the waste nonhazardous. How-
ever, if this waste is placed in a monofill, or placed
anywhere other than an acid condition, the lead is at risk
of leaching because of the high pH environment caused
by the addition of lime or cement.
.--J.
1*
c
.0
to
1 '
CD
0
O
O
•o
CO
™ ,.«. ™. », «„ ^..Kto,^,.,.™,™.™™,^,™,^^.^,^^ „<-,>.„ im. .TO „„
1 1 1 „ J 1 l 1011
5 7 9 11 13
pH
Figure 4.
Foundry waste.
Table 1. teachability of Smelter Waste*
TCLP
Test
Lead
(mg/L)
Untreated
Lime (% by weight)
+5
+10
+15
Portland Cement
(% by weight)
+5
+15
+25
+50
P + pH
(% by weight)
+4
+6
+8
600
76
0.2
6.2
450
<0.2
1.2
10.0
2.4
0.4
<0.2
Final pH,
6.0
6.5
8.6
10.4
5.3
10.4
11.6
12.0
5.8
5.5
5.6
SPLP
Test
Lead
(mg/L)
<0.003
290
540
•510
19
11
12
3.0
<0.003
O.003
<0.003
Final pH,
8.2
12.2
12.5
12.5
11.5
11.9
11.9
12.1
10.6
10.3
8.5
109
-------
Figure 5 illustrates the data shown in Table Una TCLP
scenario, the "Before" data point (A) represents the pH
of the untreated waste subjected to the acid leaching
medium of the TCLP. The acetic acid lowers the pH to a
point where lead is quite water-soluble, and specifically
at a concentration greater than the hazardous waste
limit. Adding lime or cement offsets the acetic acid such
that "After" treatment (point B) the pH in the TCLP is in a
neutral range, effectively lowering the lead solubility to
below the hazardous waste limit. Although this treat-
ment is successful in rendering this waste nonhazard-
ous using the TCLP, the actual lead leaching of this
waste in the environment is probably better represented
by points C and D, if the waste is not co-disposed with
municipal solid waste. In a water leaching test (or SPLP),
the "Before" point (C) represents the actual pH of the
untreated waste in the water leaching test. According to
these data, the waste is nonproblematic for lead leach-
Ing. However, by adding lime or cement to this waste,
the pH Is raised to a point "After" treatment (D) where
lead leaching is significant. In other words, because of
the amphoteric nature of lead, adding a high pH treat-
ment chemical can cause increased lead leaching in the
waste disposal environment.
pH~Buffered Phosphate Chemistry
A pH-buffered phosphate chemical addition is more
robust than most chemical fixation treatment processes,
because it addresses the amphoteric nature of lead in
an environmentally friendly way. Phosphate forms of
lead are very insoluble (Figure 1), and are naturally
occurring in soils, but may not occur in lead-bearing
wastes because of the absence of phosphate. Economi-
cal forms of phosphate can be used in combination with
a pH buffer (Patent Numbers 5,037,479 and 5,202,303)
to create ideal conditions that minimize lead leaching in
both an environment of co-disposal with municipal wastes
(represented by the TCLP) and a nonacidic environment
(represented by the SPLP). A complete description of
this chemistry can be found in (1). The selection of a pH
buffer is crucial to maintaining an ideal pH. Lime and
cement can drive the pH too high, but magnesium oxide
(also covered by the patents) can both raise the pH in a
TCLP and prevent the pH from excessively high values
in a SPLP. The form of phosphate is also crucial, as
some forms are too acidic and others are nonreactive.
Triple superphosphate or TSP (also covered by the
patents) is an effective and economical form of phos-
phate for treatment.
Full-Scale Application to Sediment
The pH-buffered phosphate chemical fixation process
has been applied several times to sediment. In one
case, a 17-acre lagoon containing 370,000 cubic yards
of hazardous lead-bearing sediment was treated in a
unique way. A hydraulic dredge was used to remove the
sediment and transport it via pipeline to a dewatering
basin. Treatment chemical was injected in-line within the
pipeline. By the time the treated sediment slurry was
discharged to the dewatering basin, it was well mixed
c
o
CD
O
5000.0
500.0
50.0
5.0
1
-------
with the treatment chemical. The sediment that settled Summary
out was nonhazardous for lead, and the return water (to
the original lagoon) was treated for residual phosphate
with iron hydroxide.
In another case, a bridge reconstruction required the
placement of a new footing in sediment that was classi-
fiable as hazardous for lead leaching. Because of regu-
lations, treatment of the sediment ex situ would require
permitting, but in-situ treatment would not. A coffer dam
around the affected area was already required for con-
struction, so the dam was used as a means to conduct
in-situ treatment. During treatment an inward gradient
was maintained within the coffer dam to ensure no
leakage of resuspended material or treatment chemical.
Treatment chemical was added to the top layer of sedi-
ment with standard equipment (a backhoe), and mixed
to a practical depth. After mixing, the top layer of treated
sediment was removed and dewatered. It was later
transported from the site and disposed as a nonhazard-
ous waste at a fraction of the cost of hazardous waste
treatment. A more complete description of this case can
be found in (2).
A pH-buffered phosphate chemical fixation process (pat-
ented), which has been used successfully at hundreds
of uplands sites, has also been implemented at full-scale
in sediment settings. With minimal engineering controls
it is an economic, environmentally friendly, and robust
process that can be applied in situ for lead-, cadmium-,
and zinc-contaminated sediments.
References
1. Tickanen, L.D., and P.O. Turpin. 1996. "Treatment
of Heavy Metal-Bearing Wastes Using a Buffered
Phosphate Stabilization System." Proceedings of
the 51st Industrial Waste Conference. Ann Arbor
Press, Inc., Chelsea, Ml.
2. Wible, L, S. McAnulty, R. Stanforth, A. Chowdhury,
and M. Warner. 1994. "In-Situ Treatment of Haz-
ardous Sediment." Proceedings of Second Inter-
national Conference and Exhibition on Dredging
and Dredged Material Placement. American Soci-
ety of Civil Engineers, Waterway, Port,. Coastal,
and Ocean Division. November 13-16,1994.
111
-------
Treatment of Dredged Harbor Sediments by Thermal
Desorption
Mary Hall, Ed Alperin and Stuart Shealy, IT Corporation
Keith Jones, Brookhaven National Laboratory
The New York/New Jersey Harbor must be regularly
dredged to maintain shipping channels and berthing
areas for commerce and safe navigation. Ocean dis-
posal of the sediments from this dredging operation has
been the primary option for disposal. Revised guidance
from the U.S. Army Corps of Engineers—New York
District (NYDCOE) and the U.S. Environmental Protec-
tion Agency, Region 2 (EPA-Region 2) established more-
stringent biological and chemical test criteria for the
option of ocean disposal. This was published in Draft
Regional Guidance for Performing Tests on Dredged
Material Proposed for Ocean Disposal (Draft, December
1992). Under these new guidelines, the volume of con-
taminated dredged material prohibited from ocean dis-
posal has increased to approximately 500,000 cubic
yards of material requiring treatment each year.
Decontamination technologies were actively investigated
by the EPA-Region 2 and the NYDCOE under Section
405 of the Water Resources and Development Act of
1992 authorizing investigations, including testing and
demonstration. These technologies were demonstrated
to determine their environmental-acceptability and
cost-effectiveness. Treatment may require several dif-
ferent procedures before disposal is possible due to the
complex nature of the contaminants and their wide-
spread spatial distribution within the harbor.
Dredged sediments from various areas of the harbor
may contain elevated levels of a wide variety of contami-
nants, including heavy metals, polynuclear aromatic hy-
drocarbons (PAHs), and organochlorines such as dioxins,
furans, polychlorinated biphenyls (PCBs), pesticides
(OCPs), and herbicides. The treatment system must be
capable of sufficiently reducing the contaminant levels
by separation, destruction, immobilization, or other meth-
ods to render dredged sediments suitable for unre-
stricted ocean disposal, land disposal or, preferably,
beneficial use. IT Corporation (IT) investigated a three-
stage treatment process that included dewatering the
sediment, removing organic contaminants by thermal
desorption, followed by cement based solidification/sta-
bilization (S/S) of thermally treated sediment.
Two waste forms designed to meet different disposal
options were investigated. The first waste form was a
monolithic, high-strength block of treated material suit-
able for ocean disposal. These blocks would provide
hard surfaces for reef development. Artificial reefs have
proven to provide habitat for numerous fish and inverte-
brate species, and increase opportunities for recreational
anglers. These stabilized blocks could be provided to
state sponsored artificial reef programs. The second
waste form was a thermally treated, dry soil-like material
that was treated to reduce teachability of metals. This
product is suitable for fill or road base construction.
Treatment Objectives
Treatability study objectives, as established by
Brookhaven National Laboratory (BNL) were to test
methods of dewatering, thermal treating and S/S of
dredged estuarine sediments (DES) to produce a final
product that may be acceptable for unrestricted marine
disposal and that provides a beneficial use. To meet that
first goal, the final product must meet disposal criteria as
specified in Draft Regional Guidance for Performing
Tests on Dredged Material Proposed for Ocean Dis-
posal. To accomplish the second goal, the final product
will be formed into blocks suitable for encouraging growth
of marine organisms. The goals of the final product
were:
an unconfined compressive strength (UCS) of 290
pounds per square inch (psi) or greater,
metal leaching results below the Toxicity Charac-
teristic (TC) regulatory threshold, and
minimization of Lethal Concentrations or LC50 re-
sults.
112
-------
An additional testing agenda was added to the study to
investigate a land based disposal option. The objective
of this option was to produce a nonhazardous material
to be used as road base or landfill. The goals of the land
based material were:
no free liquid
DCS of 20 psi, and
metal leaching results below TC regulatory thresh-
old.
Data generated by this study will be used by BNL to
determine:
treatment effectiveness as determined by a critical
evaluation of the data from chemical and physical
analyses and bioassay testing as well as their
relative contribution to the assessment of the tech-
nology,
composition
by-products,
of end product(s), effluent, and
unit treatment cost estimates and time-scales for
scaleup operations, and
potential environmental and occupational hazards
• posed by the treatment technology or system.
Testing for this treatability study was conducted in three
stages as Figure 1 visualizes. Stage 1 was to dewater
the received material. Stage 2 was to thermally desorb
the remaining moisture and organics from the DES.
Stage 3 was to solidify/stabilize (S/S) the thermally
desorbed DES to prevent the leaching of the inorganic
contaminants.
Sample Description
was screened prior to use and material 1/2" or larger
was removed.
Dewatering
The water content of the DES was >60% (by weight).
This is too high for optimal thermal desorption operation.
High water content lowers the treatment capacity and
increases the energy requirements for a thermal desorber
system. High water content may also result in material
handling problems in typical feed equipment. This re-
sults in higher treatment costs, therefore dewatering of
high moisture sediments is frequently performed prior to
thermal treatment. Drainage beds and filter aids were
investigated under this program.
Drainage beds are concrete-lined pads or pits where
piles of materials are allowed to release free-draining
water. Plate and frame and belt filter presses have also
been effective. Lime or filter aid additives were used in
an attempt to improve dewatering performance. A bed
height of 6 feet on a standard 25 cubic-feet-per-minute
(SCFM) filter mesh was simulated to represent field
conditions. Only 11 milliliters (mis) of liquid was col-
lected in 61 seconds. This material was determined to
be non-drainable.
High pressure, 120 psi, filtration was tested and only 30
mis of liquid was collected in 15 minutes. A filter aid of
hyflo diatomaceous earth was added at a 5% concentra-
tion which caused the binding of the filter press with the
collection of only 44 mis in 15 minutes. This material
was also determined to be non-filterable.
The sample was allowed to air dry in a hood to produce
a lower moisture level prior to thermal treatment. Four
aliquots were taken for preliminary thermal desorption
analysis and samples from these aliquots were sent to
laboratories for characterization analyses. This data is
presented in Table 1.
Four 5-gallon buckets of sample were obtained by Thermal Desorption
NYDCOE using barge mounted clamshell dredging equip-
ment. The sample IT received was fine-grained sludge
with a high organic content. The percent (%) solids were
34.6%. The gross organic levels were 462 ppm of
organo-chlorinated pesticides, 2997 ppm PCBs, 52,540
ppm PAHs and 0.3 ppm dioxins/furans (as /2, 3, 7,
8-TCDD TTEs). The sample also contained teachable
cadmium, copper, lead, nickel and zinc. Due to the small
amount of material used in some of the tests, the DES
The purpose of the thermal treatment was to identify
treatment conditions (time/temperature) needed to re-
move pesticides and PCBs from the DES and generate
enough thermally treatment material for S/S testing. All
thermal tests were performed in IPs Rotary Thermal
Apparatus (RTA), see Figure 2. The RTA is a batch,
bench-scale device that is used to treat material in an
indirectly heated rotary tube. The device simulates the
DES-
Stage 1
Dewatering
}.
Stage 2
Thermal
Desorption
t
Stage 3
Stabilization/
Solidification
"Ocean Disposal or Land-Based Product
Figure 1. Three-stage treatment process for DES.
113
-------
Tabla 1. Total Pesticides (ng/kg dry) Untreated and Thermally
Treated Dredged Estuary Sediment
Treatment Temperature (°C)
/Residence Time (min)
Anatyte
Akterin
4,4'-DDD
4,4'-DDE
Dieidrin
Untreated
75
162.1
150.6
74.5
360/5
<3.4
<3.4
<3.4
<3.4
450/0
<3.4
<3.4
<3.4
<3.4
450/5
<3.4
<3.4
<3.4
<3.4-
550/5
<3.4
<3.4
<3.4
<3.4
Tolal Arodors (PCBs) (jig/kg dry) Untreated and
Thermally Treated Dredged Estuary Sediment
Treatment Temperature (°C)
/Residence Time (min)
AnaJyte Untreated
Arodor1016 <930
Arodor 1221 <930
Arodor 1232 <930
AfOdOf 1242 1400
Arodor 1248 <930
Arodw1254 1500
Aroclor 1260 <930
350/5
<66
<66
<66
<66
<66
<66
<66
450/0
<66
<66
<66
<66
<66
<66
<66
450/5
<66
<66
<66
<66
<66
<66
<66
550/5
<66
<66
<66
<66
<66
<66
<66
Total Polyaromatic Hydrocarbons (jig/kg dry)
Thermally Treated Dredged Estuary Sediment
Treatment Temperature (°C)
/Residence Time (min)
Anatytft
Untreated 350/5
450/0
450/5
550/5
Naphthalene
2729
Acenapthylane
1288
AconapMhene
1042
Fluorone
1389
Phmanduene
6S88
Anthracene
3702
Rooranthena
1032T
Pyraoa
7102
Benzo(a)anthraeene
4484
Chrysen®
4585
B«nzo(b}tluoranthane
2922
8©nzoCk}fluoranihene
1107
Beozo(a)pyrene
2550
lncteflo{1 ,2,3-cd5pyrene
1076
Dibenz(a,h)anthrancene
397
8eiuo(ghi)perytene
1255
<660
<660
<660
<660
<660
<660
<660
<660
<660
<660
<660
<860
<660
<660
<660
<660
86
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
<660
<660
<660
<660
<660
<660
<660
<660
<660
<660
<660
<660
<660
<660
<660
<660
67
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
<650
heat and mass transfer of a full-scale rotary kiln or
calciner. Soil is charged into an alloy tube, rotated and
purged with air. Indirect heating is provided by an elec-
tric furnace that encloses the tube. As the DES heats to
treatment temperature, steam (from desorption of the
sediment moisture) and desorbed organics evolved and
are carried by the purge air into an offgas treatment
system.
The offgas system used for these tests was a spray
scrubber followed by a carbon absorber. The spray
scrubber removes acid gases, semivolatile organic com-
pounds (SVOCs) and some oxygenated organics. The
carbon absorber removes volatile organic compounds
(VOCs).
Four runs were performed on a homogenous sample to
identify optimal temperature and retention time at tem-
perature to minimize the organic content prior to produc-
tion runs. The matrix used to determine the time/
temperature is 1) 350 C for 5 minutes (at temperature),
2) 450°C for 0 minutes, 3) 450°C for 5 minutes, and 4)
550°C for 5 minutes. This matrix was determined by
past testing experience. The treated material was ana-
lyzed for PAHs, RGBs and OCRs and compared with the
initial characterization. This comparison is tabularized in
Table 1. The comparison of the chemical analyses did
not provide adequate information to select the run to
carry forward to production to produce the necessary
volume for S/S testing. Therefore, the selection was
based on the biotoxicity analysis.
The biotoxicity test was performed to determine the
temperature and time necessary for treatment for ocean
disposal. Treated and untreated sediments crushed to
3/8" and extracted with a 3% Instant Ocean solution.
The amount of Instant Ocean used to leach the samples
was four times the volume of the treated specimen by
the method. The samples were extracted on a rotary
tumbler for 1 hour. The extracts were then centrifuged at
2000 rpm for 1/2 hour to separate the supernatant from
the solids. The extracts were then tested to determine
the Lethal Concentration of LC50 values. This value
represents the amount of leachate necessary to be
lethal to 50% of the test population. Acute mortality of
the leachate was tested using three common salt water
arthropods. The arthropods used as the population were
Silverside Minnow (Menidia berylina), Mysid Shrimp
(Mysidopsis bahia), and Mussel Larvae (Mytilus edulis).
The relative toxicity of the leachates of all run conditions
compared to a sample of the extraction fluid showed
lower toxicity when compared to the untreated material.
Toxicity decreased in severity as the thermal treatment
increased. The run condition of 550°C for 5 minutes at
temperature gave the lowest residual contaminant con-
tent, and this was also the least toxic leachate. This run
condition was chosen to generate thermally treated
material for S/S testing. Twenty-six RTA runs, treating
25 kg DES, were required to produce 13.7 kg of ther-
mally treated material.
114
-------
PURGE GAS
1-7 L/min.
PURGE GAS
0.3-1 L/min.
OFF-GAS
HEATER \
CLAMP
RUBBER
SEPTUM
TR1 - RTA Tube Gas thermocouple
TR2 - Soil Thermocouple
PI - Pressure Indicator
ELECTRIC FURNACE
7500 WATT
WASTE
SAMPLE
GRAPHITE
SEAL
GRAPHITE
FERRULE
Figure 2.
Rotary thermal apparatus (RTA) schematic.
To generate residuals for a mass balance determina-
tion, the scrubber system was replaced by a series of
water impingers in an ice bath, followed by a small
carbon trap. The first impinger contained only enough
water to act as a condenser. The weights of liquid
removed from the system were recorded and the liquids
were collected in a pail. The oil phase that formed was
separated from the liquid phase and the volumes esti-
mated. The carbon at the end of the offgas system was
composited into one jar. The weights of the collected
phases were submitted for analyses and the data used
to perform a mass balance as seen in Table 2.
As Table 2 shows, the PCBs in the sediments were
lowered from 6969 ng/kg to 1.8 |ig/kg (dry basis), while
the dioxins (2,3,7,8-TCDD TTF) lowered from 695 to
154 ng/kg (dry basis). The condensate oil contained 452
mg/kg PCBs and 28 jig/kg dioxin TTE. PCB and dioxin
mass balances were 110 and 122%, respectively, based
on the characterization results. The condensate oil also
contained 93% of the PCBs and 52% of the dioxins and
the activated carbon contained 2 u.g/kg dioxin TTE.
These results show that thermal desorption is effective
in removing or reducing toxic organics (OCPs, PAHs,
PCBs and dioxins) from the DES. It also reduces the
biotoxicity of the thermally treated material.
Solidification/Stabilization
Optimal additive ratios and requirements for the conver-
sion of thermally treated DES into a nonleachable du-
rable matrix was the primary objective of the stabilization
study. The additives studied were determined by IT'S
past experience with the expected waste contaminants.
This experience assisted in selecting additives for a
preliminary evaluation. The additives were: Portland
cement (PC), Class C flyash (FA), blast furnace slag
(BFS), and silica fume (SF). A minimum and maximum
percentage of additive loadings based on the amount of
sample were determined and a statistical experimental
design was used to isolate the most important additives
and to reduce the number and amount of additives
necessary to treat the material. The experimental design
matrix is a basic 24-1 fractional factorial design. The
design matrix uses eight formulations for the ocean
disposal study, see Run Numbers 1-8 in Table 3. There
are no centroid data points and the amount of water to
be added was determined by the consistency of the
grout mixture.
Formulations would be carried forward based on data
from unconfined compressive strength (DCS) (American
Society for Testing and Materials (ASTM) D-2166), and
Toxicity Characteristics Leaching Procedure (TCLP [EPA
SW-846 method 1311]). Biotoxicity testing would be
performed on samples that had a UCS greater than 290
psi and passed TCLP analyses for constituent metals.
Two formulations for the backfill disposal alternative, 9
and 10 in Table 3, were formulated using the UCS and
TCLP data produced by the ocean disposal alternative.
Biotoxicity testing is not necessary since this alternative
is land based. The additives evaluated for the land
based alternative included PC, BFS, and lime (reagent
CaO). The TCLP data is tabulated in Table 4.
Comparison of the TCLP and UCS data trends, see
Table 4, assisted IT in reformulating Sample 3 to reduce
costs by eliminating the expensive additive SF, reducing
the BFS and increasing a less-expensive additive FA.
Formulation 3 was sticky and wet and the reformulation
was more workable and would reduce the problems with
115
-------
Table 2. Mass Balance Date for Thermal Treatment of Dredged Estuarine Sediments
Stream Mass
Description (g)
Carbon5
Ash6
PCBs5
(wt%)
(g)
(g)
Dioxin.TTE3'5
(mg)
(ng/kg)
(HO)
Feed
DES
24,989
2,082
Tola) to 27,071
Scrubber
Water
4.7
1,177.0
1,177.0
In
47.7 11,919.8 2,996.7
11,919.8
Out
74.9
74.9
299
7.47
7.47
Treated 13,744
DES
Ccmdensate 12,536
Aqueous
Condensate 170
Oil
OBgas Solids 147
Offgas
Carbon Traps 498
Glassware 640
Rinse
Total Out 26,597'
Recovery % 98.2
5.5 714.7
0.5 62.7
85.0 144.5
5.2 7.6
211.9
1.141.42
97.0
91.5 12,579.9 1.8 0.0 154 2.12
na" 63 0.79
452,370.0 76.9 28,147 4.78
85.0 125.0 0.00
na" 1,845 0.92
8,692.6 5.6 888 0.57
12,704.8 82.5 9.18
106.6 110.2 122.9
1 Overall mass balance was completed around the desorber and impingers and does not include the carbon traps and solvent rinse of the
glassware.
* Carbon (organic) content of aqueous oondensate and offgas are estimated from earlier work on other soils.
* Dioxin Is reported as nanogram/kg of 2,3,7,8-tetrachlorodioxin Total Toxicity Equivalents.
4 Not Analyzed.
' Wl% carbon, ash, PCS, dioxlns have been corrected for 57% moisture content of partially dried DES used in the RTA tests.
Table 3. Formulation Matrix for Preliminary Evaluation
Portend
Run Cement
Number (g)
1
2
3
4
5
6
7
8
3R
9
10
20
20
20
20
50
50
50
50
20
5
5 (Lime)
Blast
Furnace
Slag
(g)
4
4
50
50
50
50
4
4
14
0
10
Silica
Fume
(g)
0
3
3
0
0
3
3
0
40
5
0
Fly
Ash
(g)
4
30
4
30
4
30
4
30
0
0
0
Sediment
(g)
100
100
100
100
100
100
100
100
100
100
100
material handling in the field. This reformulation is desig-
nated as 3R in Table 3. Two of the ocean disposal
formulations and the reformulation of Sample 3 were
selected to go forward to the biotoxicity testing. All
ocean disposal formulations had high concentrations of
BFS to make them more durable in sea water. Formula-
tions would be carried forward based on data from
unconfined compressive strength (DCS) (American So-
ciety for Testing and Materials (ASTM) D-2166), Toxicity
Characteristics Leaching Procedure (TCLP) (EPA
SW-846 method 1311). Biotoxicity testing would be
performed on samples that had a DCS greater than 290
psi and passed TCLP analyses for constituent metals.
The only method used to compare the land based
formulations was to perform a biotoxicity analysis, so
Formulations 9 and 10 were included in the analysis.
Formulation 9 was designed to use PC for strength and
BFS to react with the calcium hydroxide by product
made by cement hydration reactions. Formulation 10
was based on treating soils and oily materials. This
formulation was given a 1:2 (w/w) lime to FA to lower the
alkalinity for better results in the biotoxicity analysis and
cost.
116
-------
Table 4.
Formu-
lation
Number
1
2
3
4
5
6
7
8
9
10
Air
Dried
DES
Thermally
Treated
DES1
S/S TCLP Results
Arsenic
(mg/L)
<0.178
<0.178
<0.178
<0.178
<0.178
<0.178
<0.178
<0.178
<0.178
<0.178
<0.178
<0.178
Barium
(mg/L)
0.308
0.371
0.429
0.451
0.477
0.491
0.513
0.604
0.412
0.361
0.277
0.305
Cadmium
(mg/L)
<0.026
<0.026
<0.026
<0.026
<0.026
<0.026
<0.026
<0.026
<0.026
<0.026
0.325
0.665
Chromium .'
(mg/L)
<0.028
<0.028
<0.028
<0.028
<0.028
<0'.028
<0.028
<0.028
<0.028
<0.028
<0.028
<0.028
Copper
tmg/L)
<0.01 1
99.6 and >90.9%, respectively. The
SVOCs were all non-detects except for the constituents
shown in Table 5. The percentage reduction for SVOCs
was >93.7%. This percentage reduction value is limited
by all the nondetected values in the product. There were
multiple dioxins present in the total analysis. The total
toxicity equivalent as 2,3,7,8-TCDD was 59.0 ng/kg
(dry). This was well below the normal EPA guideline of
1.0 jig/kg for unrestricted landfill.
Biotoxicity results were not improved by stabilization as
measured by screening tests. Land based final waste
forms had higher biotoxicity results than thermally treated
sediments. This increased toxicity of these waste forms
was probably due to higher pH of extracts caused by
leachable lime. The Mortality in 100% Sample (EC) was
also calculated and represents the percentage of organ-
isms, out of 20 per batch, that die in a solution that is
100% from the DES and treated DES material. The
biotoxicity of the stabilized thermally treated material is
presented in Table 6.
The thermal process effectively removed most of the
hazardous organic compounds for the DES. The stabili-
zation process appears to partially hold or fixate the
metal compounds by the clay and sulfide in the DES and
the S/S additives.
The land based Formulations 9 and 10 showed higher
toxicity levels than the ocean disposal formulations. This
was expected due to the higher alkalinity and salinity of
the leachates from the low UCS values of these formula-
tions.
Formulation 3R has identical toxicity as the thermally
treated DES. The LC50 values for Formulation SRare all
greater than 100% leachate, the leachable metals are
117
-------
low and the USC Is greater than 290 psi. These three
factors Indicate that Formulation 3R has significant po-
tential for regulatory acceptance for unrestricted ocean
disposal. This formulation was, therefore selected for
scale up for the >5 kg sample to be sent for analysis. Cost Estimate
for thermal desorption where the offgas would be
treated in a flameless oxidizer. The thermally treated
DES would be stabilized in a batch mixing plant.
Conceptual Treatment Process
Based on 100,00 cubic yards of DES per year, the
treatment process would start with thermal drying to
reduce water content to 30%. The offgas from the dryer
would be carbon treated to eliminate the release of
organics. The material would be fed to a rotary calciner
The process costs are base on a 12 mo-24 hr opera-
tion. The capital cost for the treatment system is
estimated at $23,650,000 or $23.65 per yd5 of sedi-
ment. Utilities (power and fuel) are estimated to be
$21.48 per-yd3. Labor will consist of a substantial staff
to cost $19.99 per yd3. Add $16 per yard for monolithic
waste for a total of $88.64/ycP.
Table 5. Detected Treated Material SVOCs Comparisons With
Feed
SVOC Anaiyte
fig/kg in the
Product
ng/kg in the
Feed
Naphthalene 47.9
2-Methylnaphtha!ene 25.0
Diethylphthalate 33.4
Di-n-butylphthalate 60.4
bis-2-Ethylhexylphthalate 243.3
2729
2304
48631
'Common laboratory contaminant often arising from the gloves,
rubber O-rings, and plastic containers in contact with the sample or
a leachate of the sample.
Tablo 6, Biotoxteity Testing Results
Formulation
BJotogkal Species
Mmidta borylina
(Sttvwskfe Minnows)
.Mysldopsis toMa
(Mysid Shrimp)
Mytaas eduKs
(Mussal Laa-ae)
Air Dried
Procedure DES
LCso (% Sample)
Mortality in 100%
sample (%)
LCso (% Sample)
Mortality in 100%
sample (%)
LCso (% Sample)
Mortality in 100%
sample (%)
58.79
95
82.78
65
75.02
77.0
Thermally
Dried DES1 3R
>100.0
0
>100.0
2.5
>100.0
15.8
>100.0
15
>100.0
27.5
>100.0
44.0
4
>100.0
25
>100.0
42.5
>100.0
35.0
5
>100.0
10
>100.0
• ,17.5
>100.0
30.0
9
65.7
100
31.57
70
>100.0
41.5
10
66.39
82.5
22.36
100
87.06
52.5
Blanka
>100.0
17.5
>100.0
0
>100.0
42.0
ECso (% Sample)) 24.04 71.2 >100.0 58.38 54.68 58.44 23.41 59.22
Effected in 100% 100 92.3 94.9 97.1 97.1 100.0 100.0 94.9
sample (%)
i Thermally treated at 550«C for 5 minutes.
? Instant Ocean® extraction fluid.
118
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Solvent Extraction Process Development to
Decontaminate Sediments
Philip DiGasbarro
Metcalf & Eddy,.Inc., Branchburg, NJ
John Henningson, P.E.
Formerly of Metcalf & Eddy, Inc.
Georges Pottecher
Anjou Recherche/GRS, Paris, France
John J. Cardoni, P.E.
Metcalf & Eddy, Inc., Branchburg, NJ
Abstract
Solvent extraction of organic contaminants is one of the
relatively low-cost methods currently under develop-
ment for decontaminating sediments. The technology
has been used extensively in industrial applications.
Solvent extraction is applied in analytical methods to
remove the organic contaminants from various materi-
als. Furthermore, the technology has been applied suc-
cessfully on contaminated soils and sludges with low
moisture content. However, the application of this tech-
nology to contaminated sediments presents unique chal-
lenges. The high moisture content, the low toxic
contaminant concentrations and high fine-grain material
characteristics of the sediment require special attention
to solvent selection and processing features. This de-
scribes the technical issues associated with solvent
extraction and recent bench- and pilot-scale test results.
These tests indicate that this technology is safe and
cost-effective for further development and engineering
design as part of a full-scale commercial plant.
I.
Introduction
Sediments slowly accumulate in our ports, harbors,
rivers, and lakes and eventually restrict shipping access
and navigational safety. Accordingly, both the U.S. Envi-
ronmental Protection Agency (EPA) and U.S. Army Corps
of Engineers (USAGE) manage and regulate the dredg-
ing of approximately 400 million cubic yards of sedi-
ments each year in the United States. It is estimated that
approximately 14 to 28 million cubic yards/year of sedi-
ments from the federal waterways and from the indus-
trial sites are contaminated with low levels of
toxic-regulated organics and/or heavy metals. To date,
dredged sediments were mainly disposed of in the ocean.
However, recent regulatory restrictions to protect the
environment will require treatment or upland disposal of
these contaminated sediments.(1)(2)
For example, the NY/NJ port is evaluating the various
options in the planning document titled "Dredged Mate-
rial Management Plan for the Port of New York and New
Jersey." The options for solving the contaminated sedi-
ments problem are containment islands, direct upland
disposal in landfills, and treatment by several technolo-
gies.^) The overall treatment cost of using these tech-
nologies (including credits for reusable products) will
have to be less than the landfill disposal costs to be
viable. The disposal costs are estimated at $30 to $60
per cubic yard without considering the possible future
liability of not treating the material.
One of the promising technologies for treating sedi-
ments is solvent extraction, which has been extensively
used in the manufacturing industries as well as for the
decontamination of soils/sludges. Moreover, it is effec-
tive in extracting contaminants for high-resolution gas
chromatograph analysis, such as polychlorinated biphe-
nyls (PCBs) and dioxin/furans. Solvent extraction re-
moves only organics and can be part of the overall
treatment plant to produce useable products that poten-
tially have some resale value. Heavy metal contami-
nants, if any, will have to be treated by other technologies
such as chemical extraction and stabilization/fixation.
This paper discusses the technical issues of applying
solvent extraction to contaminated sediments, which
exhibit high moisture content, low toxic contaminant
concentrations, and high fraction of fines. The paper
119
-------
also presents some of the results of the recent bench-
and pilot-scale tests conducted on the NY/NJ Harbor
sediments for which the ORG-X proprietary process was
applied in combination with stabilization/solidification.
The effects of some of the important process variables
are reported. The performance results and conceptual
treatment costs are favorable for continuing to the next
phases:
1) additional investigation of other process variables to
improve and optimize contaminants removal; and
2) preliminary engineering of a commercial plant with a
capacity of 100,000 to 500,000 cubic yards/year.
II. Technical Considerations for
Applying Solvent Extraction
A. General
There are three fundamental technical considerations
for applying solvent extraction to treat contaminated
sediment. These are
the chemical and physical characteristics of the
sediment to be treated;
• the clean-up goal(s) for the selected final product(s)
or treatment objectives for the solvent extraction
process; and
the process to achieve the goal(s).
The latter involves the development and application of
the particular solvent extraction process to convert the
contaminated raw sediments to the desired final
produces). In order to effectively treat the sediments by
solvent extraction, many process development issues
must be investigated and examined closely. This is best
accomplished by briefly reviewing the solvent extraction
technology, as well as the applications and approaches
to contaminant removal.
After presenting the background on the Metcalf & Eddy/
GRS process, the bench and pilot test results will be
discussed. Geperale de Rehabilitation des Sites (GRS)
is a French affiliate of the larger CGE/Anjou Recherche
organization.
B. Sediment Characterization
Although sediment comes from numerous locations and
differ in physical and chemical content, there are some
general common characteristics. It is usually a black,
sticky and mayonnaise-like muck. It has a high water
content in the range of 60 to 70% in situ because of the
high total surface area from the high percentage of
hydrophilic fines (clays and silt). Carbon content is high
(2 to 10% TOG on a dry basis), and a variety of heavy
metals and organic contaminants, usually generated by
various industrial/commercial activities, can be found.
These organic contaminants, which are the focus of this
solvent extraction process, are usually non-volatile, in-
soluble in water, and not readily biodegradable. Among
these, the hydrophobic organic contaminants of concern
are usually low levels of dioxins, furans, PCBs, and
polyaromatic hydrocarbons. If the sediment is dredged
from the nearby ocean, the salinity in the water phase
can be as high as 3%.
Sediments can be removed from the site using tradi-
tional techniques to produce low solids to water ratios,
or by use of novel techniques to produce material almost
in the in-situ state. After removal of debris, the viscous
sediments may be pumpable as is, or with some dilution
using piston pumps.
The physical and chemical characteristics of the sedi-
ment from Newtown Creek in the NY/NJ Harbor are
presented in Table 1.
In this case the objectionable organic contaminants are
dioxins, furans, and PCBs, based on ecological studies.
A few other contaminants in the pesticides and semi-
volatiles groups may also be unacceptable. The odor
and semi-solid/liquid state is also undesirable when
placed upland and exposed to the atmosphere. Often
heavy metals are not a problem according to the TCLP
criteria for upland disposal. However, it may effect the
suitability for reuse and should be stabilized.
C. Sediment Treatment Objectives and
Solvent Extraction Process Objectives
The overall objective of a sediment management pro-
gram is to minimize cost over a given time horizon while
satisfying various constraints/criteria/desires/specifica-
tions. Cost minimization also applies to treating the
contaminated sediments with the solvent extraction pro-
cess. Although a clean-up criteria has not been estab-
lished for low but undesired levels of toxic compounds,
reasonably safe goals can be proposed for useful prod-
ucts. For example, if the dioxin/furan levels are set at 1
ppt (total equivalent to 2,3,7,8 TCDD) and PCBs levels
are set at 1 ppb, the required removal is usually 1-3
orders of magnitude. Other organics and odoriferous
compounds would also be removed using the solvent
extraction process.
Depending on the type of product desired for beneficial
reuse, the organic-free sediments can be solidified by
drying/pelletizing, or stabilized with Portland cement or
other agents to fix metals. The types of possible prod-
ucts are 1) construction backfill and landfill cover for the
stabilized sediment; and 2) an additive for landscaping
and composting soil blends for the treated, not stabi-
lized, sediment. This beneficial reuse not only eliminates
a disposal cost, but may provide a financial contribution
if the product is sold at $5 - $10/per cubic yard.
After setting the overall goal(s), some of the desirable
objectives of the organic extraction plant are
120
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Table 1. Newtown Creek (NY Harbor) Sediment Characteristics
Physical Characteristics - Almost in the
Solids (%)
Gravel (% of solids)
Sand (% of solids)
Silt (% of solids)
Clay (% of solids)
Chemical Characteristics
In-Situ State
30-40%
0.1 - 34%, frequently on low side
35 - 47%, frequently near average
8 - 43%, frequently near average
10 - 65%, frequently near average
Organics
PAHs
Pesticides
Dioxins/Furans (total)
PCBs (total)
Total Organic Carbon
Metals
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Silver
Zinc
Level
1-50 ppm
ND-177ppb
0.01-15ppb
1-10 ppm
2 - 8%
Level
5-33 ppm
1 - 20 ppm
100 -400 ppm
61 - 770 ppm
68 - 554 ppm
1 - 3 ppm
12- 140 ppm
2-3 ppm
104 -1260 ppm
TCLP
<0.01 mg/l
<0.01 - 0.0005 mg/l '
<0.001 - 0.01 ng/l
0.0001 - 0.02 &g/l
—
TCLP
<0.1 mg/l
<0.1 mg/l
0.03 mg/l
<0.05 mg/l
<0.001 mg/l
to treat a variety of organic contaminants at vari-
ous concentrations;
to pretreat sediments to reasonable but flexible
specifications;
to design the commercial plant with flexible level
of organics removal in order to attain the safe
levels of the reusable product;
to produce various desirable products to maxi-
mize reuse; and
• to integrate the solvent extraction plant with a
solidification plant and its requirements (i.e., pro-
duce organic contaminant-free sediment with mois-
ture content required by solidification plant).
D. Brief Review of Solvent Extraction
Technology, Applications and Approach
1. Organic Contaminant Extraction
Approach
Applying solvent extraction for treating sediments is
more complex than the two standard types found in
textbooks: liquid-solid extraction or liquid-liquid extrac-
tion. The sediments are already two phases (liquid and
solid) in the form of an aqueous slurry, and the introduc-
tion of a partially miscible solvent creates a second
liquid phase. Moreover, there is a multitude of contami-
nants and not just one or a few solutes as found in most
industrial applications. Figure 1 shows two approaches
for extracting contaminants.
One approach is to eliminate the aqueous phase by
drying the sediment and thereafter conduct the conven-
tional liquid-solid extraction. This is practiced in many
industrial applications such as sugar from sugar beets or
sugar cane, vegetable oil from oil seeds, caffeine from
coffee, turpentine and resins from wood, and residual oil
from fish(4). This approach was not selected for two
main reasons:
• the energy cost to evaporate the 60 to 70% water
in sediment adds $5 to $10 per cubic yard to the
operating cost; additional drying and fines pro-
cessing equipment is required;
aggressive mechanical dewatering is ineffective
and forms a gel-like material with little or no re-
lease of water.
121
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Screened raw sediment
(aqueous slurry)
Liquid
so)vent(s)
(Uquid - solid)
liquid extraction
\
Water
V S
Drying
high energy - cost
This is the focus of
M&E's process
development
Liquid - solid
extraction
Liquid
""solvent(s)
Figure 1. Solvent extraction approaches for contaminant removal from sediments.
The second approach is to keep the water, view the
aqueous slurry as the "dense" liquid phase, and use a
partially miscible solvent as the second phase of the
liquid-liquid extraction. This is practiced widely in the
separation of aromatics from aliphatics, sulfur com-
pounds from oil, antibiotics from fermenter broth, vita-
mins from oil, and pollutants from wastewaters.
Selectivity for specific contaminants can still be achieved
by using partially miscible acetate/alcohol solvent blends.
Figure 2 shows the complex equilibrium stage.
There are two possible mechanisms for the contami-
nants to transfer from the solid particle to the solvent
layer. This is shown in Figure 3. The first mechanism is
for the organic contaminant to first dissolve in the new
aqueous/organic layer and then transfer to the organic
layer/droplets. This is probably effective because the
new solvent blend can penetrate the sediment particles.
The second mechanism is for the organic phase solvent
blend to contact the solid particles with proper mixing,
and to extract the organic contaminant directly. This is
effective in solventing molecules such as PCBs, which
are also non-polar.
2. Brief Review of Solvent Extraction
Processes for Soils/Sediments and Types of
Industrial Solvents Used
There are numerous industrial extraction applications
applying many types of common solvents:
Chlorinated Hydrocarbons (CHCl,, CHCI3, PERC)
Ketones (Acetone, MEK, MIBK...)
Acetates (Methyl Acetate, Ethyl Acetate...)
Alcohols (Methanol, Ethanol, PropanoL.)
Aromatics (Benzene, Toluene, Xylene...)
Aliphatics (Propane, Butane, Hexane...)
These processes were developed by proper solvent
selection, meaningful pilot tests and good scaleup (5).
There are several solvent extraction processes that are
emerging from the pilot phase to full-scale production
mainly for contaminated soil. Although some of these
have been tried on sediments using a pilot plant, the
performance was not very successful, or not available to
the authors. Table 2 lists the main process and vendor.
Some of the vendors used solvents that are now hazard-
ous and regulated.
122
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Feed Flow
Solvent Flow
Water (A)
+
Solid Particles (B)
with Adsorbed
Organic Contaminants (C)
Solvent (D)
+
Water (A) @
Solubility Limit
Mix
Solvent (D)
+
Organic Contaminants (C)
+
Water (A) @
Solubility Limit
Water (A)
•+•
Solid Particles (B)
with Less Adsorbed
Organics (C)
+
Solvent (D)
@ Solubility Limit
Aqueous and Organic
Phases in
Equilibrium
Figure 2. Single contact stage of contaminated sediments and solvent at equilibrium.
Direct Extraction of
Organic Contaminant
to Solvent
Organic
Contaminant
Sediment
Particle
(Solid
Phase)
Solvent
Droplet
(Phase)
Aqueous Phase
with
Solvent
Solubility Limit
indirect Extraction of
Organic Contaminant to
Aqueous Phase and then
to Solvent Phase
Figure 3. Contaminant transfer mechanisms on mixing.
123
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Tabla 2. Solvent Extraction Processes for Soils/Sediments Treatment
ProcasaWendor
Solvents
Extraction Temperature (T)
and Pressurp (P)
Solvents
Solubility in Water
(Sediment Slurry)
ART International
Proprietary:
1st: hydrophilic (acetone,
methanol, isopropanol);
2nd: hydrophobia
Ambient @ 1 Atmosphere
1st: very high
2nd: very low
RCC/tortics
CFS/M-K
Torra-Kleen
M&E
Triethylamlne
(now ECRA-hazardous)
CO2, propane, ethers
Proprietary
Mixture of up to 14 solvents
Acetates, alcohols, and other
special blends
Ambient to 100°+C@ 1
Atmosphere
Ambient temperatures @
Critical Pressure (P0)
Ambient @ 1 Atmosphere
Ambient to 100°+C@
1 Atmosphere
High at low Temp.
Low at high Temp.
High at critical T and P
Not known
Moderate
The ART International technology initially uses a hydro-
philic solvent to extract the organic contaminants from
sediments or soil. The solvents used are acetone, metha-
nol, or isopropanol. Then a hydrophobic solvent is used
to extract the contaminants from the hydrophilic solvent.
This requires separation of the two solvents and addi-
tional equipment for handling and recovery of individual
solvents.
The RCC/lonics technology uses triethylamine which is
hydrophilic (high solubility in water) at less than 20°C
and hydrophobic at greater than 20°C with wet sedi-
ments or soil slurries. Therefore, the mixtures must be
cooled and heated in cycles for each stage. It should be
noted that triethylamine is now a listed hazardous waste
and additional regulatory and health risks need to be
addressed.
The CF/MK technology uses very low boiling solvents
(carbon dioxide, hexane, or ethers) at supercritical con-
ditions to attain a one liquid and one solid phase with
wet sediment/soil slurries. Then the pressure is reduced
to attain two liquid phases for separation. Equipment
designed for high pressure costs considerably more
than equipment designed for atmospheric service.
The Terra-Kleen technology uses many solvents to ex-
tract the contaminants from soil in batch tanks. Then
fractional distillation or possibly molecular sieves are
used to remove organic contaminants.
The technology from M&E and its sister company GRS
uses various solvents and has been applied mainly for
contaminated soils in France. M&E has modified the
process for the recent bench and pilot studies done for
the NY/NJ Harbor sediments, using a blend of acetate/
alcohol solvent.
3. Solvent Selection Guidelines/Criteria
for M&E/GRS Process
There are many factors considered for selection of the
acetate/alcohol blend to extract contaminants from the
wet sediments. These factors can be classified under
selectivity for contaminants, physical and material han-
dling properties, thermal stability, safety and environ-
mental considerations, and cost.(4)
Selectivity—Solvent choice is influenced by the interac-
tions of the structure of the chemicals. The main con-
taminants of concern are the non-polar to slightly polar
polyaromatic hydrocarbons, and multi-chlorinated hy-
drocarbons such as PCBs, dioxins, furans and pesti-
cides. The acetate offers both a slightly polar and
non-polar group and provides affinity for the contami-
nants. Unfortunately, the solubility of the acetates in-
creases as the aliphatic group increases. To increase
solubility of the acetate in water, an alcohol is added.
This blend also provides the additional benefit of in-
creasing the solubility of other contaminants selective to
the alcohol. This blend also exhibits higher than ex-
pected solubility and penetration into the sediments as
shown in Figure 4. The sensitivity of solubility to solids
content is very high. This is favorable as it occurs in the
30 to 35% solids range, where the two low viscosity
liquid layers readily mix and quickly separate for decant-
ing.
The acetate/alcohol blend has several important proper-
ties that reduce processing cost. First, some combina-
tions form heterogeneous minimum azeotropes with
water. This allows the removal of essentially all the
solvent from sediments without removing most of the
water. Second, the heterogeneous azeotrope improves
the solvent recovery distillation step. Third, the density
of the acetate/alcohol blend is significantly less than
water or aqueous slurry and makes the separations
easy. Fourth, the solvated sediment mixture flows well
124
-------
.1
.
2 i
II
81
3 §
-------
Step I: Hydro-Sep
SecSmant washing—volume reduction I
Conoopt!Hydrwop separates the coarse particles
o» U>e segment (sand and gravel) from
ttto fine fractions (siits, clays, and
iHHmi(os) using screens and hydraulic
systems. The screening and water
washing is enough to clean the coarse
policies. Only tha lines" need further
iraatrogrM. ,
Gravity separator
(hydrosizer)
Humates
Attrtion
scrubber! Silt,
day
Dewatering
Recydabla
at
construction t'f<*j\
•L%*» I
Ctean Ctean
gravel sand
Contaminated
fines
Step II: Org-X
Solvent extraction of organic contaminants
Concept: A solvent is used to extract the organic
contaminants (oils, PCBs, dioxlns,
pesticides...) strongly attached to the
fines. After extraction, the clean sediment
is dried. The recovered solvent is
decanted, distilled and recycled while the
organic contaminants are concentrated
as oils. The oils are shipped offsite for
disposal.
Concentrated
contaminant
oil (for off-site
disposal)
Organics
free fines
Step III: Splfix
Stabilization of inorganic contaminants
Concept: To stabilize heavy metals (lead,
cadmium, arsenic...) the sediment is
reacted with cement, pozzolanic material!
and other special additives. The mix is
allowed to "cure" (rested) for several
days, during which the metals are
chemically immobilized into insoluble
forms and encapsulated into a concrete-
like solid. The inert end-product can be
crushed for beneficial uses as construc-
tion aggregate, road base or landfill
cover.
Reagents
Mixer
End product: Solidified
sediment—recyclable as
construction aggregate, road'
base, landfill cover...
Bgure 5, M&E Integrated Sediment Decontamination System.
Step I HYDRO-SEPSM: A soil washing process to pro-
duce clean, larger-size fractions and reduce
the quantity of sediments to be treated by
downstream operations. It consists mainly of
scalping debris for disposal and separating
sands, gravel, and cobbles for water washing.
Dewatering is not necessary if solids content
!s greater than 30%.
Step II ORG-X8": A solvent extraction process to re-
move organics contaminants and produce or-
ganic contaminant-free sediments and a waste
oil for off-site disposal (incineration). The sol-
vent is recovered by partially drying the sedi-
ment, distilling the waste oil and steam strip-
ping the wastewater.
Step HI SOLFIXSM: A solidification/stabilization process
that adds Portland Cement to the sediments to
improve the leaching properties of inorganic
contaminants and to improve the mechanical/
physical properties to produce useful end-prod-
ucts.
After completing bench-scale treatability studies that
showed promise of decontamination and production of
potential useful products, a pilot plant was operated at
Port Newark in the Fall of 1996 to treat 10 cubic yards of
sediments. The objectives of the test program were:
to demonstrate how most of the steps of the
technologies can decontaminate a significant quan-
tity (10 cy) of actual sediment feedstock, and
produce products with desirable physical proper-
ties; and
to collect process data for the preliminary design
of a commercial facility.
The test program, illustrated as a block flow diagram in
Figure 6, focused on these tests:
screening the sediments to remove debris, >1/4"
oversize and >18 mesh oversize.
removing organics contaminants using a batch
solvent extraction and semi-continuous solvent
recovery process. The solvent was a blend of
warm acetate/alcohol believed to offer high re-
moval at reasonable cost. The main operating
variables were 1:1 solvent to sediment ratio for
each extraction that was well-agitated for 15 min-
126
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Raw sediment -
5cy in one roll-off
(20 drums) '•
"Water decanting/
adjustment
screening
• transfer to 5-gal
containers
Screened sediment
|vent system]
(negl)
Washwater is
recycled within
Hydro-sep
Solvent ^s^ ,
make-up >•" \
• "" I
N2 inerting „ t
+ *
Org-X
pilot plant
\
Concentrated
organics
analysis only)
\
[Reagent ^v.
Solfix
Organics-free- ^"fiia
sediment
r
Wastewater
(analysis only)
^ Cured products
tion) • aggregate
Figure 6. Block flow diagram of pilot test program.
utes and settled for 10 minutes prior to decanting
the solvent phase with extracted contaminants.
Organic contaminant removal was investigated for
3, 5, and 7 extractions.
removing organic contaminant using a continuous
system with a glass Scheibel column having 18
mixing/settling zones. The objective was to inves-
tigate an alternative to the more expensive mixer-
settler'type extractor.
recovering the solvent for repetitive reuse; drying
the decontaminated sediments; concentrating the
waste oil; and stripping the wastewater.
stabilizing/solidifying the organic-free sediments
to produce end-products with improved physical
properties/The organic- free sediment with 45 to
50% water was blended with 0.15 parts and 0.30
parts cement.
B. Test Results
1. HYDRO-SEPSM/Pre-Treatment Process—A full-
scale solvent extraction plant requires large quan-
tities of homogeneous screened (<1/4") feedstock
for proper control of operation. The desired solids
content is 30-35%. The sediment is delivered in
barges/scows up to a size of 10,000 cy. After
removing any water on top, the settled sediment
can be pumped or removed by a clam shell di-
rectly to a vibrating grizzly. Subsequently, the
sediment can be screened, mixed and adjusted
for moisture content, pumped and stored in silos.
These unit operations are already practiced in the
mining/dredging industry. The pilot plant demon-
strated that the 35-40% solids sediments can be
screened with vibratory screens down to 18 mesh.
The oversize can be washed to produce clean
cobbles, gravel and sand, or can be crushed.
Depending on the sediment granulometry, wash-
ing can reduce the quantity of sediment to be
treated by as much as 85% for very coarse sedi-
ment. However, the Newtown Creek sediments
used for the pilot plant only contained a few
percent of the +1/4" oversize.
2. Chemical Test Results from Solvent Extraction
Process—The performance of the ORG-X solvent
extraction plant is presented in Table 3 for the
bench treatability study using only the acetate
solvent. The percent removal with three extraction
stages was moderate (low 90s%) for most organic
contaminants and low for dioxins/furans.
Difficulty was encountered in two areas:
Penetration of the solvent into the sediment re-
quired intensive mixing and a long period (> 20
minutes).
The sediment was difficult to handle as it adhered
to laboratory hardware.
In order to overcome these difficulties and seek greater
organics contaminant removal, the pilot-plant program
was improved by using a mixture of warm acetate/
alcohol as the solvent. Moreover, some of the extraction
equipment was coated to reduce fouling due to sticki-
ness of the sediment. The sensitivity of organics re-
moval was measured versus the number of extraction
stages. The performance of a continuous extraction
column was also compared with the mixer-settler,type
extractor.
127
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Tablo3. Bench-Scale Chemical Results Using Three
Extraction Stages and Acetate Solvent
Parameters/Contaminants % Removal
Light Hydrocarbons 99.9
Medium-Weight Hydrocarbons 86
Total Hydrocarbons 91
Heavy Hydrocarbons 92
Pesticides 94 - 98
PCBs 79 - 92
DtoxWFurans *
Residual Carbon 37
Totel Organic Carbon 30
TCIP Metals Below MDL
TCLP Organtcs Up to 99
* Not meaningful due to low concentration and precision. The solvent
contained 81-84% of Initial total dioxins/furans.
The pilot-plant performance improved considerably com-
pared to the bench scale. Table 4 presents the reduction
for the main contaminants of concern: dioxins, furans,
and PCBs. The reduction in total group PCBs increased
by almost one order of magnitude to the high 90s%. The
reduction improved to the low 80s% for total dioxin and
to the high 80s% for total furans. In terms of the total
equivalency quotient (TEQ) (using toxicity factors com-
pared to 2,3,7,8-TCDD), the reduction was a few per-
cent lower than calculated using the actual concentration
values. The reduction improves as the number of extrac-
tions Increases, but is not very sensitive after five extrac-
tions. The operation of the continuous extraction column
with 18 zones is approximately equivalent to 5-stage
mixer/settler extractions.
Although removal of most organic contaminants is high,
it may not be adequate for dioxins/furans. The final
concentration attained is about 1 ppb total dioxin, 3 ppb
total furan, and 129.8 ppt total individual dioxins plus
furans (TEQ). These dioxins/furans are more difficult to
extract than PCBs, and the extraction rate may be more
sensitive to other parameters, such as agitation inten-
sity, contact time, or a different solvent blend with an-
other non-polar solvent such as hexane or heptane.
Further laboratory work is recommended to potentially
improve removal performance to 90-99%.
The performance of the SOLFIX solidification/fixation
process is presented in Table 5 in terms of leachability
(TCLP method). Except for PCBs, the reduction is not
calculable as the concentrations are below the minimum
detectable limits. The heavy metals already meet the
upland disposal criteria. As expected, the reduction in
amount of total group PCB extracted is significantly
greater with the solvent-extracted-and-stabilized sedi-
ments than the stabilized-only sediments.
3. Physical Properties and Product Uses—Solidifi-
cation of the sediments with Portland cement (or other
weaker binding agents such as flyash or kiln dust) also
changes the physical properties of the products made.
By varying the amount of water and cement, different
properties can be attained. Table 6 presents the proper-
ties of both the SOLFIX-only products and the ORG-X +
SOLFIX products as measured by USACE-WES.
The addition of a small proportion of cement (0.1, 0.15
and 0.2 parts to 1 part sediments) produces a light and
soft agglomerated material that can be crushed to vari-
ous sizes. The soil-like material meets the specifications
for operational and interim landfill cover or construction
fill for depressions, sinkholes, and stripmine areas. It
can also be blended with other materials such as com-
post, manure, sludge, other soils to produce a landscap-
ing soil. The addition of larger proportions of cement (0.3
and 0.4 parts) produces a cured block of material that is
stronger with the unconfined compressive strength (DCS)
approaching 1,000 psi. The cured material is similar to a
soft sandstone that can be crushed to various sizes to
resemble crushed stone or aggregate. However, it does
not meet the specifications for use as a road sub-base.
The material crumbles with vibrations and expansions/
contractions, as indicated by the freeze and thaw tests.
For the same reason, it appears that producing other
more expensive structural concrete-like products may
not be practical.
The ORG-X process produces a viscous, flowable slurry
at the optimal moisture content (40-50%) for solidifica-
tion with Portland cement in a pugmill. This lower mois-
ture content than the 60-70% of the raw sediment requires
less cement to attain similar properties. If heavy metals
are not a problem, the ORG-X product can also be used
directly with other dry materials to produce a landscape
soil or construction fill.
4. Process Design—The operation of the batch
and semi-continuous pilot plant generated some pro-
cess data to design a full-scale automated plant with
some confidence. The full-scale plant should be fully
continuous, with large flexibility to accommodate sedi-
ment with varying granulometry and contaminants. The
best extractor type appears to be the mixer-settler. It is
favorable over the column type extractors, which are for
more specific applications with low residence times (min-
utes to hours). The mixer-settlers are widely used in the
industry because of their reliability, flexibility, and high
capacity. The large volume of inventory is another ad-
vantage. It can provide the residence time (many hours)
that may be required for the extraction of contaminants
with slow diffusion rates.
The solvent can be evaporated from sediments in a
steam jacketed ribbon dryer. Packed or sieve distillation
columns are appropriate for recovering the solvent and
128
-------
Table 4. Comparison of Pilot Test and Bench-Scale Tests for Dioxin, Furan, and PCB Removal
Contaminant/
Class
Total
Individual
Dioxins
(TEQ)
Total
Dioxins "
Total
Individual
Furans
CTEQ)
Total
Furans
Total
Group
PCBs
Screened
Untreated
Sediment Used
in Pilot Plant
@ Port Newark
Concentration
123 ppt
5,342 ppt
750 ppt
30,200 ppt
7,946 ppb
ORG-X Only
Pilot Scale
@ Port Newark
(5 extractions with
Acetate/Alcohol)
Conc./%
Reduction
27.7 ppt
77.6%
1,029 ppt
80.7%
96.8 ppt
87.1%
3,382 ppt
88.8%
125.3 ppb
97.8%
ORG-X Only
Pilot Scale
@ Port Newark
(7 extractions with
Acetate/Alcohol)
Conc./%
Reduction
29.1 ppt
76.5%
1,030 ppt
80.7%
97.4 ppt
87.0%
3,300 ppt
89.1%
125.0 ppb
98.4%
ORG-X Only
Pilot Scale
@ Port Newark
(Continuous extraction
with Acetate/Alcohol)
Conc./%
Reduction
30.3 ppt
75.5%
1,062 ppt
80.1%
99.3 ppt
86.8%
3,198 ppt
89.4%
134.3 ppb
97.7%
ORG-X Only
Bench Scale
@GRS,
France
(3 extractions
with Acetate)
Conc./%
Reduction
Not
meaningful
-35% to
+66%
Not
meaningful
-80% to
+40%
79 - 92%
Notes:
All analyses are on a dry basis.
ppb = parts per billion
ppt = parts per trillion
TEQ = Total Equivalency Quotient (ref. 2,3,7,8-TCDD)
Table 5. SOLFIX Performance Using Leachability, TCLP Method
Regulatory
Toxicity
Contaminant Characteristics
Total Group PCBs
Semi-volatiles
Total Dioxins/Furans
Metals (mg/L)
Arsenic 5.0
Barium 100
Cadmium 1 .0
Chromium 5.0
Lead 5.0
Mercury 0.2
Selenium 1.0
Silver 5.0
Bench-Scale
Screened Untreated
Sediment
133ng/L
<200 ng/L
<100pg/L
<0.100
<0.500
<0.010
<0.028
<0.050
<0.001
<0.100
<0.010
Pilot SOLFIX-Only
0.2 Parts Cement
64ng/L
<200 ng/L
<100pg/L
0.018
0.232
<0.001
0.017
<0.002
<0.0004
0.014
0.001 '
Pilot
ORG-X + SOLFIX
0.15 Parts Cement
8 ng/L
<100ng/L
<100pg/L
0.018
0.292
0.035 .
0.100
0.007
0.034
0.016 '
0.192
129
-------
Tablo 6, Physical Characterization Data for Stabilized/Solidified Sediments
Sample, Cement/
Segment Ratio
0.1 Cement SOLFIX Only
OS Cement SOLFIX Only
0.4 Cement SOLFIX Only
0.15 Cement
ORG-X + SOLFIX
0.3 Cement
ORG-X + SOLFIX
UCS, psi
26
123
501
234
658
Water
Content
@60°C
60.1
27.9
18.1
50.3
23.4
Water
Content
@ 100°C
69.8
51.2
31.0
71.1
53.7
Particle
Specific
Gravity
2.54
2.61
2.63
2.70
2.69
Permeability,
cm/sec
8.05E-06
7.05E-06
2.81 E-07
1.61E-06
5.62E-07
Bulk Dry
Density,
Ibs/cu ft
37.7
48.9
58.8
51.4
64.7
concentrating the waste oil. Packed or sieve columns
are appropriate for stripping organics from wastewater
with direct steam. The wastewater is generated because
the water content of the final product is less than the
initial content in the sediment feed. The wastewater can
be treated with conventional techniques to meet the
POTW or other direct discharge requirements.
5. Costs—The operating cost of a full-scale sol-
vent extraction plant mainly depends on the quantity and
cost of makeup solvent, energy to recover the solvent,
incineration of non-regulated waste oil, labor, and costs
from maintenance, overhead and depreciation. It is esti-
mated that unit costs can approach the $30 to $40 per
cubic yard range, especially if the plant capacity is large
(£500,000 cubic yards/yr) and fully utilized. Stabilization/
solidification adds approximately $10 per cubic yard for
each 0.1 part of Portland cement added. There is also
the potential credit of $5 to $10 per cubic yard if the
product can be beneficially used. The disposal cost of
the waste oil can vary considerably depending on the
contaminant content. There is a credit if the waste oil
can be used as a fuel supplement for the plant boiler. If
the waste oil contains a regulated concentration of >1
ppb TEQ dioxin/furan, the unit cost increases by almost
$40 per cubic yard at $2/lb incineration cost. Both the
capital and operating costs can be estimated for vari-
ous cases and sites by preparing a preliminary engi-
neering design. Moreover, the markets for beneficial use
products must be developed further.
IV. Conclusions
Solvent extraction is a promising and competitive tech-
nology for removal of organic contamination from sedi-
ments. The acetate/alcohol solvent blend is highly effec-
tive in removing most organic contaminants without
dewatering/drying the sediments. The treatment costs
are comparable with landfill disposal and are probably
less for large-scale plants. The authors recommend
further process development to improve the dioxin/furan
removal efficiency and completion of preliminary engi-
neering design to refine costs.
References
1. Priore, W. and E. Cichon. 1996. Sediment Man-
agement, Dredging Material from U.S. Waterways.
Water Environment & Technology. (October).
2. National Research Council. 1997. Contaminated
Sediments in Ports and Waterways. Washington,
DC. National Academy Press.
3. U.S. Army Corps of Engineers. 1996. Dredged
Material Management Plan for the Port of New
York and New Jersey. Interim Report. (Septem-
ber).
4. Kirk-Othner. 1980. Encyclopedia of Chemical Tech-
nology. Volume 9, Third Edition. New York, NY.
John Wiley & Sons. pp. 672-739.
5. Cusack, R. W. and D. J. Glatz. 1996. Apply Liquid-
Liquid Extraction to Today's Problems. Chemical
Engineering. (July), pp. 94-103.
130
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Containment Research for Contaminated Sediment and
Contaminated Dredged Material Management—A Review
Louis J. Thibodeaux, Danny D. Reible, and Killait T. Valsaraj
Hazardous Substance Research Center/S & SW
College of Engineering, Louisiana State University
Baton Rouge, LA
Introduction
Chemical contaminants including inorganics, metals and
organics exist within sediment beds of water bodies both
fresh and marine. These substances may exist in rela-
tive high concentrations such that they are transported
in solution and as colloids by both active and passive
processes to the water column. Quantities in high load-
ings on solid particles may also exist at the sediment
bed-water interface. The result of such existence and
movement is the eventual exposure of life forms to
quantities of these chemical constituents. This exposure
may result in enhanced health risks. One effective means
of reducing this risk is to contain these chemical con-
stituents within a bed-like form so that their mobility and
hence propensity for contacting the biota can be man-
aged. This paper covers some of the research activities,
ongoing and planned, aimed at enhancing the technol-
ogy of chemical containment as a risk management
option for contaminated sediment.
Theory of In-bed Containment
Environmental niches in water bodies where bottom
currents are weak usually accumulate particles. The
process is called bed accretion. Particles in all size
ranges from clay to sand size settle from the water
column in these relatively quiet places and, with time,
layers of sediment accumulate. These particles move
closer together with time expelling porewater upward
and become consolidated. Except for a relatively fluffy
interface layer the consolidation process renders the
bed somewhat resilient to erosion during low to moder-
ate increases in water flow. However, storm events can
cause severe erosion at some locations on the bed.
With the chemical contaminants, both in solution and
sorbed onto arriving particles, the bed accretion process
aids in the formation of layers of high chemical concen-
tration in the bottom sediment. Many of these contami-
nated beds have been in existence for long time periods
with some sites accumulating material fifty years or
more. A general lack of chemical mobility over this
period suggests several positive things about the bed
being an effective containment zone.
Sites where this accumulation occurs are natural traps
for particles. Storm events over the years have undoubt-
edly moved some quantities about, however the bed
remains relatively secure. But there are other transport
processes besides particle scour; these include molecu-
lar diffusion of solutes in porewater after desorption from
solids and out-diffusion of colloids and bioturbation.
These and other in-bed release processes are illus-
trated in Figure 1. In order to assess the overall effec-
tiveness of any proposed remediation technology, the
concentration at the sediment-water interface, both on
particles and the adjoining porewaters, must be known.
Bed residing life forms, both infaunal and epifaunal,
usually bioaccumulate substances here. Due to feeding
by fish and out-migration, these organism-bound chemi-
cals may enter human food chains. In addition, an
outward flux of chemicals to the water column occurs.
This release process regulates chemical concentration
levels in the bed, at the sediment-water interface and
within the water column (1). To effectively address is-
sues of containment research, these in-bed processes
must be thoroughly understood. Significant amounts of
information exist but much work needs to be done.
Chemical release processes from the particle-bound
state to the adjoining porewater are key in initiating the
movement process. Much research effort has been di-
rected toward this complex process. The local equilib-
rium assumption (LEA) that relates concentration ratios
on particles and adjoining porewaters is not universally
applicable to this situation. There can be a slow kinetic
release of the mobile fraction, however an irreversible
fraction remains on the solids (2,3). Because of these
two aspects, LEA will overestimate the porewater con-
centration. In the case of hydrophobic organics and
inorganics, in-particle hindered diffusion release (4) and
131
-------
"MUO FLATS" TYPE BOTTOM FORM
-/ft-
WATEft
".-••.-. "•*.•/:'-": 'SUSPENDED ;.'•'•;• • -
vV ••'-.'"• •-'••' SEDtMENT • ••-•."-:•.•-.
•-,..
MOBILE BED TYPE BOTTOM FORM
WATER
BED SEDIMENT
(T) Water-side film
(sf) Diffusion molecular brownian*
(3) Biaturbalton
(<[) Gfoundwater advection
(5) Localized advection
#
1 WORMS
(e_) Particle resuspension*
(7) Particle deposition*
QT) Bed translocation*
(9^ Reaction
Qo) Suspended particle*
* Denotes mechanisms tied to fine particle behavior
nl) Gas bubble advection
62) Colloid transport*
Figure 1. Bed-sediment chemical processes.
quantification of the irreversible fraction for organics (3)
appear to yield a realistic process and algorithms for
quantifying release rate and source strength.
Once released to the porewaters the solute species
moves upward toward the sediment-water interface and
downward further into the bed. Data on this process
both in the laboratory (5,6) and in the field (7) indicate
that molecular diffusion is active and that it is very slow.
Slow mobility is due to the difficulty of solute molecule
diffusion in liquid water and the pathway blocking of silt
and clay platelets creating a tortuous route. The high
degree of containment effectiveness of several tech-
nologies is due to this very slow process when it can be
engineered into the system. Another closely related
process is the Brownian diffusion of colloids in
porewaters. Due to their high organic fraction these
small particles contain elevated concentrations of hydro-
phobic constituents and are transported similar to the
solute fraction (8,9). Quantitative models have been
verified that allow good computational estimates of the
rates of release from beds (10).
In layers several centimeters thick adjoining the
sediment-water interface, macrofauna, when present,
augments and enhances the contaminant availability
and release processes. A review of these bioturbation
processes, so-called because the biota gives rise to
both particle and fluid turbulence-type phenomena as
they relate to contaminants in the bed, has been per-
formed (11). Due to its complexity, the process is under
active investigation (12,13). Typically Fickian type chemi-
cal transport models have been used to quantify this
process and algorithms exist with which to compute
release rates (14,4). The latter reference contains algo-
rithms and procedures for computations of release rates
and bed-surface concentrations for the coupled pro-
cesses of molecular diffusion, bioturbation and hydrody-
namic boundary layer resistance to transport.
Typically, contaminants, both organics and metals, exist
in a bed layer ten-to-fifty centimeters in thickness. Fig-
ure 2 shows typical profiles, and they represent approxi-
mately a half century accumulation of two Aroclors in the
bed of New Bedford Harbor, MA. The relative depletion
of PCBs near the surface is due to outward transport
from the bed and the arrival and deposition of clean
sediment particles on the surface. Bioturbation is active
in the upper approximately ten centimeters. Particle
exchange at the surface occurs even in water bodies
undergoing net bed accretion. This occurs as a result of
storm events, possibly the only times sufficient water
currents are present to dislodge particles from the bed.
This dislodgement moves material about contaminating
regions downcurrent with higher-concentration material.
It is likely that the near-interface peak in the concentra-
tion profile at site DR is due to downcurrent/storm move-
ment of material from Site Fx(7). Storm events lead to
increased suspended sediment loading in the water
column. During and after the storm, quantities of soluble
and colloidal bound chemicals enter the water phase.
While the particle transport process is somewhat well
132
-------
Aroctors 1242/10160,1254 •
New Bedford
• Sample Station Fx
eooo
Aroclors 1242/10160 ,12£
New Bedford
Sample Station Dr
Depth (cm)
Depth (cm)
Figure 2.
PCB concentration profiles in the bed.
understood conceptually and means of quantifying rates
of release and concentrations in the water column exist
(15), a real understanding of contaminant release re-
mains elusive. Recent laboratory work with contami-
nated particles in re-suspension chambers is starting to
clarify this complex process (19, 20). While particle
dislodgement and movement computation algorithms
for noncohesion particles are well developed, those for
cohesive particles are under active investigation (16,17,
18). Once this is completed, the process of contaminant
release associated with suspended particles needs be
developed into quantitative algorithms that allow predic-
tions of release rates and concentration.
Ariy proposed containment technology for a so-called
operable site must be judged against the existing re-
lease and exposure process. This means that release
rates from the bed and concentrations on particles near
and on the surface, plus those in the water, must be Natural recovery
predictable in an engineering design sense. Compa-
rable released and exposed quantities must be quanti-
fied for the proposed containment technologies. The
engineering community and EPA are presently using
this approach (21) although much uncertainty exists in
the design algorithms for predicting released quantities
for all site conditions and remediation technologies.
Containment Technologies
These can take various forms; Figure 3 is a conceptual
illustration showing containment locations in and near
the water body. Although the illustration is for an estua-
rine system, the technologies also apply to lake and
riverine systems. A total of five technologies are illus-
trated: natural recovery, in-situ capping, contained aquatic
disposal (CAD), a confined disposal facility (CDF), and
an upland solid waste landfill. A recent National Re-
search Council report (22) highlights these technolo-
gies. This paper will address aspects of the first four
technologies.
Conceptually natural recovery consists of in-bed pro-
cesses that retain, destroy, and retard the release of
contaminants. It can be very effective due to a combina-
133
-------
Upland
Upland Solid
Waste Landfill
Cove
Estuary or Harbor
Continental
Shelf
Deep Ocean
Basin
Confined Contained
Disposal Facihty Natura, Aquatic in-SITU
Disposal Capping
Treatmod
Sediment
Cap
ff**3
"7
Contaminated
Sediment
Contaminated
Sediment
Deep Ocean Basin
Disposal (Abyssal
Plain)
'7"
Contaminated
Sediment
Figure 3. Conceptual illustration—containment, disposal and natural recovery technologies for contaminated bed sediments (adapted
from Mike R, Palermo, USAE, Vicksburg, MS).
tion of simultaneous processes. Fresh particles arrive
on the bed surface; this lengthens the diffusion transport
path, dilutes the concentration in the surface layer and
provides fresh sorptive surfaces to sequester the
bed-residing contaminants. Chemical reactions, either
biotic or abiotic, may occur within the bed to degrade the
species. Burial at depth occurs as the column of solids
builds. This puts significant quantities deep in the bed
and below the bioturbated zone which has the overall
effect of removing them from the biosphere. These
processes are known and have been investigated indi-
vidually and a few algorithms capable of quantifying
combined and key processes for engineering design
prediction purposes have appeared (23). Nevertheless
the technology suffers from underdevelopment. A uni-
fied theory connecting its many contributing processes
needs to be developed and key features verified by
experiment. For this reason, some of the positive at-
tributes of natural recovery are unappreciated and there-
fore often unrealized by practitioners.
Natural recovery as a remediation technology has been
selected by choice in only a few situations. It was
selected for Kepone in the Chesapeake Bay (24). Most
contaminated sediment sites are undergoing natural
recovery by default. This occurs because of many fac-
tors including the complexities of the decision making
process plus political and economic considerations. Heal-
ing of the effects of contaminations is clearly occurring
at some sites where concentrations in the media and the
biota continue to decrease with time. Where ongoing
monitoring, the dominant technological activity on a site
undergoing natural recovery, is indicating healing, it is
doubly burdensome on advocates of more aggressive
technologies that are based on mass removal to demon-
strate enhance effectiveness. Undertaking more ag-
gressive technologies usually involves dredging. Envi-
ronmental dredging is not a well-developed technology
(22). The fact is that the dredging process may release
significant quantities; this is a short-term effect. In addi-
tion, removal efficiency at most complex and large sites
is not 100%; likely significant quantities remain. This is a
long-term effect. The removed quantity must be
re-contained and/or treated. These operations will result
in additional releases.
In-situ Capping
This involves the dredging of clean material which is
then transported and placed upon the contaminated
bed. The theory and practice of in-situ capping is well
developed. The theory for this chemical containment
process has undergone extensive model development
and laboratory verification (7, 25, 26). Field Data on
measured chemical profiles below and within the cap
material are very suggestive verifications of the models
(27). Detailed pilot- or full-scale studies of interbed bed
migration, water column release, and other related con-
taminant mobility studies need to be done to further
verify and test this technology as an aid in its further
adoption.
Contained Aquatic Disposal (CAD)
This option, considered to be more aggressive, involves
dredging and transporting the contaminant mass. In
some instances such as maintaining the required water
depth in ports and harbors, mass removal is necessary.
After transporting the material it must be placed on the
bottom again. This can be on-the-flat or within a depres-
134
-------
sipn in the bottom. This depression can be a natural one
or one formed by excavation of bed sediment. A low
aspect-to-height ratio mound is formed when the clean
material is placed on the pre-deposited contaminated
material mound. Bokuniewicz, an early advocate of CAD
containment, describes the mounding process at field
sites in the Northeast U.S. (28). Field studies have
dominated the research activities related to the CAD
technology (29). Because of the required mass removal
operations noted previously, CAD suffers several disad-
vantages with regard to knowledge about short-term
and long-term contaminant releases. As noted, research
is needed to evaluate and quantify the amount and
effects of dredging related chemical releases and the
quantity left behind at the original site. Once in place and
capped, the CAD technology has most of the engineer-
ing design and release aspects of the in-situ capping
technology (7,25,26,30).
Confined Disposal Facility
The final chemical containment option to be considered
is that which occurs when contaminated dredged mate-
rial is placed in a confined disposal facility (CDF). These
facilities are constructed near or adjacent to the shore-
line in shallow water as shown in the illustration of
Figure 3. Earthen-type engineered retaining walls are
constructed out into the water enclosing a finite area.
Dredged material is placed in this diked area to the
extent that dry land is created with the material extend-
ing above the mean water level. Once in place, the
contaminated material can exhibit several release mecha-
nisms unrelated to those covered above.
Rainwater enters top-side; this can produce a leachate
that exits through the retaining walls. Tidal pumping of
the external water body also results in contaminant
release (31). Once the upper surface of a CDF is directly
connected to the atmosphere, volatile losses will occur.
An evaluative study ranked the drying surface soils as
the largest source of volatile organic chemicals (32).
Laboratory studies have quantified the magnitude of
such releases and models are in an advanced state of
development (33). When finalized, these will contain
algorithms for making engineering design estimates of
losses based on the contaminant content of the surface
soils and other environmental parameters. The authors
and co-investigators at the U.S. Army Engineers Water-
ways Experiment Station are developing a field site to
verify VOC emission models developed for CDFs.
Research Paradigm
The research paradigm for containment of contaminated
sediment and contaminated dredged material is a unique
engineering undertaking. In research on the treatment of
waste and in large part in the remediation of environ-
mental contamination, the traditional engineering ap-
proach is to undertake some biological, physical and/or
chemical activity. Treatment of gaseous, water and solid
material by measuring percentage contaminant removal
is accepted practice. However, in the case of contami-
nated sediment which exists in thin layers covering large
areal expanses, removal is very problematic. Once re-
moved there appears to be no "silver bullet" treatment
technologies for the vast majority of this material. The
suite of in situ or ex situ process train treatment tech-
nologies needed is very expensive and largely unveri-
fied (22). However, if the goal in remediation of
contaminated sediment is risk management at reason-
able cost, then containment with or without dredging
must be an option that warrants serious consideration.
In this case, the research paradigm must focus on
designing for and measuring small quantities being re-
leased.
Research activities related to the above technologies of
natural recovery, capping, CAD and CDF must be aimed
at developing engineering design algorithms capable of
realistically quantifying the trace quantities of chemicals
being released in each case and the related media (air,
water, solids, biota) concentrations produced. The algo-
rithms need to be robust so that alternatives and unique
conditions at individual sites can be incorporated into
the designs. It is a key issue that designers of such
containment devices focus on the finite quantities of
contaminants being released rather than on complete
(i.e. 100%) containment. The idea here is that one is on
thin ice, so to speak, attempting a technical argument
proposing zero release for any of these devices. First,
you cannot prove it, and if you try, the concept is
unbelievable in the eyes of many stakeholders. How-
ever, finite but low quantities based on sound scientific
principles and backed by laboratory and field data can
be defended. Whereas a zero release cannot be de-
fended since it can't be measured.
Another research focus area should be on the detection
of failures in the containment barriers. It is unlikely (i.e.,
very low probabilities) that a catastrophic failure of the
entire barrier system will occur; however, it is very likely
(i.e. 100% probability) that some parts may fail at some
time. For example, in the cases of the natural recovery,
capping and CAD options, storms may destroy parts of
the barrier. Protocols involving instrumentation, sen-
sors, monitoring procedures, etc., need to be developed
so that failures are detected and the magnitudes can be
quantified. As with any engineered system, failure al-
ways has a finite probability. In the case of these con-
tainment options, the breaches can be effectively
repaired. In other words, the structures will always be in
need of maintenance just as does a bridge, highway,
waterway, etc. With these designs the mass of contami-
nated material remains in the bed and removal by
dredging and transporting remains an option. This final
solution should be made when containment becomes
too risky. In order to defend maintenance as an element
that must be included, the probability of failures must be
quantified and effectively communicated to the impacted
stakeholder. Research is needed in predicting the likely
type of failures that can occur, when these are most
likely to occur, and the number and severity expected
each year. With this information monitoring and mainte-
135
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Jersey City, NJ 07802-3902
201-309-3087
Fax:201-309-3040
E-mail: jzh@hartcrowser.com
Tom Janszen
IT Corporation
312 Directors Ddve
Knoxsville, TN 37923
423-690-3211, Ext. 2133
Fax: 423-690-3626
Michael Mensinger
Institute of Gas Technology
ENDESCO Services, Inc.
1700 South Mount Prospect Road
DesPlaines, IL60018
847-768-0602
Fax:847-768-0516
E-mail: mensing@igt.org
Ian Orchard
Chief
Remedial Technologies Program
Environmental Technologies
Advancement Division
Environment Canada
4905 Dufferin Street
Downsville, Ontario, M3H 5T4
Canada
416-739-5874
Fax:416-739-4342
E-mail: ian.orchard@ec.gc.ca
Spyros Pavlou
URS Greiner, Inc., for
National Research Council
2101 Constitution Ave. N.W.
Washington D.C. 20418
William Priore
National Director of Sediment
Remediation Services
Metcalf & Eddy, Inc.
2800 Corporate Exchange Drive
Suite 250
Columbus, OH 43231
614-890-5501, Ext. 223
Fax: 614-890-7421
E-mail: bpriore@acc-net.com
Denise Rousseau
Hazardous Substance Research
Center
Louisiana State University
Baton Rouge, LA
504-388-6770
Paul Schroeder
Waterways Experiment Station
U.S. Army Corps of Engineers
(CEWES-EE-P)
3909 Halls Ferry Road
Vicksburg, MS 39180
601-634-3709
Fax: 601-634-3707
E-mail: schroep@exl.wes.army.mil
Mark Serwinowski
Manager, Business Development
Blasland, Bouck, and Lee
6723 Towpath Road
P.O. Box 66
Syracuse, NY 13214
315-446-9120
Fax: 315-449-0023
E-mail: mas2%bbl@mcimail.com
Howard Shaffer
Program Development Manager
Science and Technology Center
Westinghouse Electric Corporation
1310 Beulah Road
Pittsburgh, PA 15235-5098
412-256-2740
Fax:412-256-1222
E-mail: shaffer.h.w@wec.com
Eric Stern
Project Manager
New York Harbor Project
U.S. Environmental
Protection Agency
290 Broadway - 24th Floor
New York, NY 10007-1866
212-637-3806
Nancy Ulerich
Program Manager
Science and Technology Center
Westinghouse Electric Corporation
1310 Beulah Road
Pittsburgh, PA 15235-5098
412-256-2198
Fax:412-256-1222
Starnes Walker
Vice President of Technology
CF Environmental
.18300 West Highway 72
Arvada, CO 80007
303-420-1550
Fax: 303-420-2890
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&U.S. GOVERNMENT PRINTING OFF1CE:1998-650-001/80213
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