United States
        Environmental Protection
           Office of Research and
           Washington, DC 2046O
August 1998
National Conference on
Management and Treatment of
Contaminated Sediments

Cincinnati, OH
May 13-14, 1997


                                              August"! 998
National Conference on Management and
  Treatment of Contaminated Sediments

                  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

Mention of trade names or commercial products does not
  constitute endorsement or recommendation for use.

       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


    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.
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,
    Technical Director of Environmental Risk Economics, URS Greiner Inc.,
    Seattle, WA
    Louis J. Thibodeaux
    Member, NRC Marine Board Committee on Contaminated Marine Sediments,
    Emeritus Director, Hazardous Substance Research Center (South/Southeast),
    USEPA and Jesse Cpates Professor of Chemical Engineering,
    Louisiana State University, Baton Rouge, LA
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.

                          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

                          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
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

                        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

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
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.

 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.

   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

 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

                                      National Monitoring Data 198B-1993
                     Sediment Chemistry
  Fish Tisue
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

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
 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

All 1 or more
>1 or more
AII1 or more
>1 or more
Amphipod Survival Tests
% not toxic % siqnif. toxic
% highly toxic
% not toxic
% signif.
toxic % highly toxic
 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
2 or more tests (different species)
 demonstrate significant mortality
    Tier 2     Exceeds 1 lower threshold    TBP exceeds risk levels   TBP exceeds risk levels

                           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.

   Tier 1: Sampling stations with sediment contamina-
   tion associated with a higher probability of adverse

   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 —




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
                            and 2



Number of Stations
                        0-5     7-45

                      5,521   15,922

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.

Figure 6. Areas (watersheds) of probable concern for sediment contamination.


 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.

 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-

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.

         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

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

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.


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


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.


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,

develop and validate chemical-specific sediment quality
criteria, and to develop and evaluate sediment cleanup

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.

 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

          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

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-

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

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

                                 JOSEPH L. ZELIBOR, Project Officer
                                 LAURA OST, Editor


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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-
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-
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

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

   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

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.

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-

     Broad public involvement and education are criti-
     cal in any sediment assessment and  remedy se-

     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.


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

  •   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

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

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-

                    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.

        Typical Shallow Seismic System Configuration
     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

Data File: BP010000
Subfile:     2        3
Geographical Position •
      0      1

     +    -f
5     0
      e.  -s
                            CORE 17/18
                                                             0  5 10m

                                                      LATERAL DISTANCE SCALE
Basic Soil Description
silty clay to clayey silt
silty 'sand to sandy silt






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.

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

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.


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

 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

 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-

 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

 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

 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

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/.


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.


 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,

 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,

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-

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.

               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

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

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

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
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).


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).
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

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

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.


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

                                                                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
                         .  95% confidence limit

                         +  Mean concentration
                  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

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,
   1.00E+01       1.00E+02
PCB in fish tissue concentration (ppb)
 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
10-6 1.4
10-5 14
10-4 140
Level letter in
• . E
F '
Number of stations
exceeding level
2,256 '
Percentage of
stations ••
'71.1 ,
• 68.4

   I               I
1.00E+01         1.00E+02

Concentration (ppb)
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
           Level letter in
          mercury figures
Number of stations
 exceeding level
Percentage of
Canadian guideline

Noncancar hazard quotient of 1

Noncancer hazard quotient of 1

Noncancer hazard quotient of 1
Cpre-1995 for infants)

FDA action (avel

Wildlife criteria




















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

                          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:

    Anaerobic conditions in sediments that limit aero-
    bic biodegradation  of  PAHs, partially dechlori-
    nated RGBs and other aerobically degradable con-

    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.

 1.   Hayter, E.J., M.A. Bergs, R. Gu, S.C. McCutcheon,
     and S.J. Smith. 1997. SED2D, A Finite Element
     Model for  Cohesive Sediment Transport. Draft
     report. U.S. Environmental Protection Agency. En-
     vironmental Research Laboratory. Athens, GA.

 2.   Dyer, K. R. 1986. Coastal and Estuarian Sediment
     Dynamics. John Wiley and Sons. London.

 3.   Preston, A., D.F.  Jefferies, J.W.R. Dutton,  B.R.
     Harvey, and A.K. Steele. 1972. British Isles coastal
     waters: The concentration of selected heavy met-
     als in seawater, suspended matter and biological
     indicators - A pilot survey. J. Environ. Poll. 3:69-
4.   U.S. EPA. 1996. The National Sediment Quality
     Survey: A Report to Congress on the Extent and
     Severity of Sediment Contamination in Surface
     Waters of the United States. EPA-823-D-96-002.
     U.S. Environmental Protection Agency. Office of
     Science and Technology. Washington, DC. July.

5.   Karickhoff,  S.W.,  D.S.  Brown, and  T.A.  Scott.
     1979. Sorption of hydrophobic pollutants on natu-
     ral sediments. Water Res. 13:241-248.

6.   Safe, S. 1980. Metabolism uptake, storage, and
     bioaccumulation. In: Halogenated Biphenyls, Naph-
     thalenes, Di-benzodioxins and Related Products.
     R. Kimbroush, ed. Elsevier, North Holland, pp 81-

7.   U.S. EPA. 1992. National Study of Chemical Resi-
     dues in  Fish, Volumes I and II. EPA 823-R-92-
     008a,b.  U.S.  Environmental  Protection Agency.
     Office of Science and Technology. Washington,
     DC. September.

8.   MacKay, D.,  and P.J.  Leinonen. 1975. Rate of
     evaporation of  low solubility contaminants from
     water bodies to atmosphere. Environ. Sci. Technol.

9.   Swackhamer, D.L., B.D. McVeety and R.A. Hites.
     1988. Deposition and evaporation of polychlorobi-
     phenyl congeners to and from Siskiwit Lake, Isle
     Royale,  Lake Superior. Environ.  Sci.  Technol.

 10.  National  Research Council. 1997.  Contaminated
     Sediments in Ports and Waterways. National Acad-
     emy Press. Washington, DC. p66.

 11.  U.S. EPA. 1994. Assessment and Remediation of
     Contaminated Sediments Program: Remediation
     Guidance Document EPA/905/R-94/003. U.S. En-
  ,   vironmental Protection  Agency.  Great Lakes Na-
     tional Program  Office. Chicago, IL.

 12.  Velleux,  M.,  J. Gailani, and D. Endicott 1996.
     Screening-level approach for estimating contami-
     nant  export  from  tributaries. J. Environ. Engr.

 13.  Velleux,  M., and D. Endicott. 1994. Development
     of a  mass balance  model  for estimating PCB
     export from the Lower Fox River to Green Bay.
     Great Lakes Res. 20:416-434.

 14.  DiToro,  D.M.,  J.D. Mahony, D.J. Hanson,  K.S.
     Scott, M.B. Hicks, S.M. Mays, and M.S. Redmond.
     1990. Toxicity of cadmium in sediments: The role
     of acid-volatile sulfide. Environ. Toxicol.  Chem.

 15.  Luoma, S.N. 1983. Bioavailability of trace metals
     to aquatic organisms - A review. Set. Tot. Environ.

 16.  Allen, H.E., G. Fu, and B. Deng. 1993. Analysis of
     acid-volatile sulfide (AVS) and simultaneous ex-
     tracted metals (SEM) for estimation of potential
     toxicity  in aquatic sediments. Environ.  Toxicol.
     Chem. 12:1441-1453.

 17.  DiToro, D.M., J.D. Mahony, DJ. Hansen, K.J.
     Scott, A.R.  Carlson, and GT. Ankley. 1992. Acid-
     volatile sulfide predicts the acute toxicity of cad-
     mium and  nickel  in  sediments. Environ.  Sci.
     Technol. 26:96-101.

 18.  Casas, A.M., and  E.A. Creceilus. 1994. Relation-
     ship between acid-volatile sulfide and the toxicity
     of zinc, lead  and copper in marine sediments.
     Environ. Toxicol. Chem. 13:529-536.

 19.  Meyer, J.S., W. Davison, B. Sundby, J.T. Ores,
     DJ. Lauren, U. Forster, J. Hong, and D.G. Crosby.
     1994. Synopsis of discussion  sessions: The  ef-
     fects of variable redox potential, pH and light  on
     bioavailability in dynamic water-sediment environ-
     ments. In: Bioavailability, Physical, Chemical, and
     Biological Interactions. Proceedings of the  Thir-
     teenth Pellston  Workshop.  Eds. J.L. Hamelink,
     P.F. Landrum, H.L. Bergman, and W.H. Benson,
     Lewis Publishers. Boca Raton, FL Pp. 155-170.

20.  Bisogni, J.J., and A.W. Lawrence. 1973. Kinetics
     of Microbially Mediated Methylation of Mercury in
     Aerobic and Anaerobic Aquatic Environments. Re-
     port to OWRR. Department of the Interior. Techni-
     cal  Report No. 63. Cornell University Water Re-
     sources and Marine Science Center. Ithaca,  NY.

21.  Bedard, D.L., and  R.J. May. 1996. Characteriza-
     tion of the polychlorinated biphenyls in sediments
     of Woods Pond: Evidence for microbial dechlori-
     nation of aroclors 1260 in-situ Environ.  Sci.
     Technol. 30:237-245.

22.  Brown, J.F., Jr.,  R.E. Wagner, H.  Feng,  D.L.
     Bedard, M.J. Brennan, J.C. Carnahan,  and  R.J.
     May. 1987. Environmental dechlorination of PCBs.
     Environ. Toxicol. Chem. 6:579-593.

23.  Abramowiz, D.A., and D.R. Olsen. 1995. Acceler-
     ated biodegradation of PCBs. Chemtech. 24:36-

24.  Shuttleworth, K.L.,  and C.E. Cerniglia. 1995. Envi-
     ronmental aspects of  PAH biodegradation. Appl.
     Biochem. Biotechnol. 54:291 -302.

25.  Cemiglia, C.E. 1992. Biodegradation of polycyclic
     aromatic hydrocarbons. Biodegradation 3:351-368.
26.  Seech, A., B. O'Neil, and LA. Comacchio. 1993.
     Bioremediation of sediments contaminated with
     polynuclear aromatic hydrocarbons (PAHs). In:
     Proceedings of the Workshop  on the Removal
     and Treatment of Contaminated Sediments. Envi-
     ronment Canada's Great Lakes Cleanup Fund.
     Wastewater  Technology  Centre, Burlington,

27.  Brown, J.F.,  Jr.,  R.E.  Wagner, H. Feng,  D.L.
     Bedard, M.J.  Brennan, J.C. Carnahan, and R.J.
     May. 1987. Environmental dechlorination of PCBs.
     Environ. Toxicol. Chem. 6:579-593.

28.  Quensen, J.F., III, S.A. Boyd,  and J.M.  Tiedje.
     1990. Dechlorination of four commercial polychlo-
     rinated biphenyl mixtures (aroclors) by anaerobic
     microorganisms from sediments. Appl. Environ.
     Microbial. 56:2360- 2369.

29.  Liu, S.M., and W.J. Jones. 1995. Biotransforma-
     tion of dichloroaromatic compounds in non-adapted
     and adapted freshwater sediment slurries. Appl.
     Microbiol. and Biotech. 43:725-732.

30.  Safe, S. 1992. Toxicology structure-function rela-
     tionship and human environmental health impacts
     of polychlorinated  biphenyls: Progress and prob-
     lems. Environ. Health Perspect.  100:259-268.

31.  Bolger, M. 1993. Overview of PCB toxicology. In:
     Proceedings of the U.S. Environmental Protection
     Agency's National Technical Workshop "PCBs in
     Fish  Tissue" EPA/823-R-93-003.  U.S. Environ-
     mental  Protection Agency, Office of Water. Wash-
     ington,  DC. September, pp 1-37 to 1-53.

32.  Flanagan, W.P., and R.J. May. 1993.  Metabolic
     detection as evidence for naturally occurring aero-
     bic PCB biodegradation in Hudson River sedi-
     ments.  Environ. Sci. Technol. 27:2207-2212.

33.  Harkness, M.R., J.B. McDermott, D.A. Abramowicz,
     J.J. Salvo, W.P. Flanagan, M.L. Stephens, F.J.
     Mondello, R.J. May, J.H. Lobos,  K.M. Carrol, M.J.
     Brennan,  A.A. Bracco, K.M. Fish, G.L. Wagner,
     P.R. Wilson, O.K. Dierich, D.T. Lin,  C.B. Morgan,
     and W.L Gately. 1993. In-situ stimulation of aero-
     bic PCB biodegradation  in Hudson River sedi-
     ments.  Science 159:503-507.

34.  Johnsen, R.E. 1976. DDT metabolism in microbial
     systems. Residue Rev. 61:1-?8.

35.  Rpchkind, M.L., and J.W. Blackburn. 1986. Micro-
     bial Decomposition of Chlorinated Aromatic Com-
     pounds. EPA/600/2-86/090 U.S. Environmental
     Protection Agency. Office of Research and  Devel-
     opment. Hazardous Waste Environmental  Re-
     search  Laboratory, Cincinnati, OH.

36.  Stull, J.K., D.J.P. Swift, and A. W. Niedoroda. 1996.
    Contaminant dispersal on the Palos Verdes conti-
    nental margin: I.  Sediments and biota near a
    major California wastewater discharge. Sci. of the
    Total Environment 179:73-90.
37. National Research Council, National Academy of
    Sciences. 1977. Drinking Water and Health, Part
    II, Chapter VI. Report of the Safe Drinking Water
    Committee. PB-270-423. pp 97-105.
38. Callahan,  M.A., M.W. Siimak, N.W.  Gabel, IP.
    May, C.F. Fowler, J.R. Freed, P. Jennings, R.L.
    Durfee, F.C. Whitmore, B. Maestri, W.R. Mabey,
    B.R. Holt, and C.  Gould.  1979. Water-Related
    Environmental Fate of 129 Priority Pollutants.EPA-
    440/4-79-029a. U.S. Environmental Protection
    Agency, Office of Water Planning and Standard
    and Office of Water and  Waste Management.
    Washington, DC.

39. Waslenchak, D.G.,  and H.L Windom. 1978. Fac-
    tors controlling the estuarine chemistry of arsenic.
    Estuaries coastal Mar. Sci. 7:455-464.

40. Waslenchak, D.G.  1979. The geochemicai con-
    trols or arsenic  concentrations  in southeastern
    United States' rivers. Chem. Geo/. 24:315-325.

41. U.S. EPA. 1993. Guidance for Assessing Chemi-
    cal Contaminants Data for Use in Fish Advisories.
    EPA 823-R-93-002. U.S. Environmental Protec-
    tion Agency. Office of Water. Washington, DC.

42. Hesse, J.L 1993. Case study: Michigan. In: Pro-
    ceedings  of the U.S. Environmental Protection
    Agency's National  Technical Workshop "PCBs in
    Fish Tissue." EPA/823-R-93-003. U.S. Environ-
    mental Protection Agency, Office of Water. Wash-
    ington, DC. September, p 4-45.

43. Hugget, R.J., M.M. Nichols, and  M.E.  Bender.
     1980.  Kepone contamination of the James River
    Estuary. In: Contaminants and Sediments. R.A.
    Baker, ed. Amer. Chem.  Soc. Ann Arbor Science
     Publishers, Inc. Ann arbor,  Ml. pp 33-52.

44. Nichols, M.M. 1990. Sedimentologic fate and cy-
    cling of Kepone in an estuarine system: Example
    from the James River Estuary. Sci. And the Total
     Environment. Elsevier Science  Publishers B.V.
    Amsterdam, pp 407-440.

45.  DeVault, D.  1993. PCB trends  in Grreat  Lakes
    fish. In: Proceedings of the U.S. Environmental
     Protection Agency's National Technical Workshop
    "PCBs in  Fish Tissue." EPA/823-R-93-003. U.S.
     Environmental Protection Agency,  Office of Wa-
    ter. Washington, DC. September, p 1-29, 30.
46. O'Conner, T.P. 1996. Trends in chemicaf concen-
    tration in mussels and oysters collected along the
    U.S. coast from 1996-1993. Marine Environ. Res.

47. Velleux,  M., J. Gailani,  and  D. Endicott. 1994.
    User's Guide to the In-place Pollution Export (IPX)
    Water Quality Modeling Framework. Draft report.
    U.S.  Environmental  Protection Agency. Large
    Lakes Res. Station. Grosse Me,  NH.

48. Gravens, M.B.  1992. User's Guide to Shoreline
    Modeling System (SMS). Instruction Report CERC-
    92-1. Department  of the Army.  U.S. Corps of
    Engineers. Waterways Experiment Station.
    Vicksburg, MS. August.

49. Hanson, H., and N.C. Kraus. 1989. Genesis: Gen-
    eralized Model for Simulating Shoreline Change.
    Technical Report,  CERC-89-19.  Department of
    the Army. U.S. Corps of Engineers. Waterways
    Experiment Station. Vicksburg,  MS. December.

50. Rosati, J.D., R.A. Wise, N.C. Kraus, and M. Larson.
    1993. SBEACH: Numerical Model for Simulating
    Storm-induced Beach Change, User's  Manual.
    Instruction  Report  CERC-93-2. U.S.  Army corps
    of Engineers. Coastal Engineering Research Pro-
    gram. Washington, DC. May.

51. Thomas, W.A., and  W.H. McAnally. 1991  (Re-
    vised). User's Manual for the Generalized Com-
    puter Program System, Open Channel Flow and
    Sedimentation. TABS-MD. IR HL85-1. USAE Wa-
    terways  Experiment Station. Vicksburg, MS. Orig.
    Publication date July 1985.

52. Spasojevic, M., and P.M. Holly. 1994. Three-Di-
    mensional Numerical Simulation of Mobile  Bed
     Hydrodynamics. CR HL-94-2. USAE Waterways
     Experiment Station. Vicksburg,  MS.

53.  Engel, J.J., R.H. Hotchkiss, and B.R. Hall. 1995.
    Three dimensional sediment transport modeling
     using CH3D computer model. In: Proceedings of
    the First International Water Resources Engineer-
     ing Conference. W.H. Espey, Jr. and P.G. Combs,
     eds.  Amer. Soc. of Civil Engr. NY. 628-632.

54.  Veileux, M., S. Bums,  J.V. DePinto, and  J.P.
     Hassett. 1995b. A Screening Level Mass Balance
     Analysis Mirex Transport and Fate in the Oswego
     River. J Great Lakes Res. 21:95-111.

55.  Gailani,  J., W. Lick, C.K. Ziegler, and D.  Endicott.
     1996. Development and calibration of 2 fine grained
     sediment transport models for the Buffalo River. J
     Great Lakes Res. 22:765-778.

56.  Teeter, A.M. 1988. New Bedford Harbor Superfund
     Project,  Acushnet River Estuary Engineering Fea-
     sibility Study of Dredging and Dredged Material

                Disposal Alternatives: Report 2-Sedlment and Con-   60.
                taminant Hydraulic Transport Investigators. De-
                partment of the Army. U.S. Corps of Engineers.
                Waterways Experimental Station. Vicksburg, MS.

           57.  Heath, R.E., T.L Fagerburg, and T.M. Parchure.
                1995. Soour of contaminated  sediments in the   61.
                Ashtabula River. Water Resources Engineering,
                vol. Proceedings of the First International Confer-
                ence sponsored by the Water Resources Division
                ofASCE. San Antonio, TX.

           58.  Scheffner, N.W. 1996. Systematic analysis of long-
                term fate of disposed dredge material. J. Water-   62.
                way, Port Coastal and Ocean Engr. 122:127-133.

           59.  Buckman, H.O., and N.C. Brady. 1969. The Na-
                ture and Properties of Soils: Seventh Edition.Jhe
                MacMillan Company, NY. p 229.
Williams, J.R. 1975. Sediment yield prediction
with universal equation using run off energy fac-
tors. In: Present and Prospective Technology for
Predicting Sediment Yields and Sources. ARS-S-
40. U.S. Department of Agriculture.
U.S. EPA. 1994. Methods for Measuring the Tox-
icity and Bioaccumulation of Sediment Associated
Contaminants with Freshwater Invertebrates.U.S.
Environmental  Protection Agency, Office of Re-
search and Development, Duluth, MN. June.
Lee, H., 11, B.L. Boise, J. Pollitier, M. Winsor, D.T.
Specht, and R.C. Randall. 1993. Guidance Manual:
Bedded Sediment Bioaccumulation Tests. EPA/
600/R-93/183. U.S.  Environmental  Protection
Agency. Office of Research  and Development.
Washington,  DC. September.

         Natural Recovery  of Contaminated Sediments-
                         Examples from  Puget  Sound
                                 Todd M. Thornburg and Steve Garbaciak
                                          Hart Crowser, Inc.

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

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

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.

                     i Volatilization
f ~^0 itoturbatiort
 %& ** "* ^^^
 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-
                                        Whatcom Waterway
                          /          fe'r*
                         /f Annex
                                         Thea Foss Waterway

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.

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
                         Peak depth at 52 cm
                         Chlor/alkali plant discharge
                         1965 to 1970
 Figure 3.

                                                      I 0.6
                                                          1970  1975   1980  1985  1990   1995  2000  2005

          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.

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-
          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
                PCB Concentration in ug/kg

                    50          100
                 Modeled Profile
                             PCB Concentration in ug/kg
                               50          100

                                                  Core Profile
 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

 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

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.


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.

 (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


- 2,790
y | ]t

^ pi
* 2,iOO *'
f -]t
*iii j i en
1.7^ \
i «
T ' *
1 1'S2° I
| Predicted Sediment Concentration

Exceeds SQO



•jkjiijjjtft ^



sftJifsR m

^§8^ •

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

Officer, Charles B., and Daniel R. Lynch, 1989.
Bioturbation, Sedimentation and Sediment-Water
Exchanges. Estuarine, Coastal and Shelf Science

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.

              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

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

      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

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-

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

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).

                                                   A. Sheybogan, Wl
                     Existing sediment
                                                                               24" Win.
                                             B. Convair Lagoon, CA
     Geotextile Fabric

12" Graded Armor Stone

20"Sand Material-


    Geotextile Fabric-
12" Graded Armor Stone
  20" Enhanced Sand Material
(Augumented with Activated/"
                                                 C.  Manistique,
Figure 1.     Illustrations of alternative combinations of cap components.


   Table 1.  Summary of Selected In-Situ Capping Projects
Project Location
Contaminants Site Conditions
Nutrients 3,700 m2
Cap Design
Fine sand, 5 and


                                                   Fine sand, 20 cm
   Denny Way, WA  PAHs, RGBs
Tacoma, WA

Eagle Harbor,
River, Wl
PAHs, dioxins

3 acres nearshore with
depths from 20 to 60 ft.

17 acres nearshore with
varying depth

54 acres within

several small areas of
shallow river/ floodplain
                                                 sediment* ^"^     barge sPreadin9      Sumeri et al. 1995

                                                 4 to 20 feet of sandy   hydraulic pipeline

                                                3 ft of sandy
                                                sand layer with
                                                armor stone
                                                                     with "sandbox"
                                                    direct mechanical
Sumeri etal. 1995

Sumeri i

   River, Ml
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
5 acres nearshore
1 00,000 M2
sand and gravel
geotextile and
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.

Figure 2.    Sandy capping sediment over a three-acre contaminated nearshore area—Denny Way project.
Figure 3.    Sandy capping sediment over a three-acre contaminated nearshore area—Eagle Harbor project.

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-

                                                                                               Top of sea wall
                                                                                                 (+10 ft)
        [Bathymetry lines
        •Geotextile cap
        Biolayer cap
        Sand cap
        Perimeter bemn
Figure 4.     Total area to be capped (approximately 5 acres, Convair Lagoon).

                                     Hamilton Harbour
                        o  1   2km
Figure 5.     Sand cap over PAH-contaminated sediments (Hamilton Harbor, Burlington, Ontario).

       47941OO *
         59350G «
                                            Scale (m)
Figure 6.     System of anchors and cables for precise positioning (Hamilton Harbor, Burlington, Ontario).

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.

 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
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

     World Dredging Congress, Amsterdam, The Neth-

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

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,
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.,

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.

      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

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.

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

 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-

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

 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

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

 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

 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

 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

 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

/  i
    { City boundary
FIflura 1.    Location of Indiana Harbor (3).
                                                        Indiana  Harbor,  Indiana

                                                              Vicinity  Map
                                                                                    Plate 1

 jj 6u|9q B9JV

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

                      • Slurry
                                               North cell area
                                               by CDF 43 acres
>^ 	 • 	
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

*"" ' " 	 '" " " ' """ •"" ^ 	 -- -- *•-- ~ -- -- ~ ^~- ~— ~~~.
                                         t-j-,-,v-,-,-,-,-,-,-,-r:::.:.:: r '_'.'  '_'. .v.
Lake George canal
                                                                                                   .   Slurry
Figure 3.      Plan view of the proposed ECI site CDF (12).
                                                                  400  200   0      - 400

 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

 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

 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-
 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.

                                                                                         2' Clean fill

                                                                                          Dewatering well
    Dredged material
   Top of existing soil
                                         Top of existing grade
                                         Medium dense sand
                                                                            Soil bentonite -
                                                                            slurry wall
                                         Stiff to very stiff clay
                Cap detail
                          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.

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

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

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

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.


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.

 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/

    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

USGS, 1997. Characterization of Fill Deposits in
the Calumet  Region of Northwestern Indiana and
Northeastern Illinois, Water-Resources Investiga-
tions Report  96-4126

                 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

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.


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-
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

 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

 The following three case studies illustrate some of the
 principal technical considerations and  lessons learned
 in recent projects involving environmental dredging and

 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.

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

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

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

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.

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.

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

 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,

 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,

 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.

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

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,

 17. US ACE. 1983. Dredging and Dredged Material
    Disposal, Engineer Manual 1110-2-5025,25 March
    1983, Office,  Chief of  Engineers, Washington,

 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,

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.

           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

                     U.S. Department of Energy, Brookhaven National Laboratory, Upton, NY

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.


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.

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-

      *    Pretreatment (physical  separation/dewater-

      »    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

          Develop cost- and profit-sharing public-pri-
          vate partnerships for operation of the facility

Characteristics of NY/NJ Harbor Dredged

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

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

Table 1.   Contaminant Concentrations of Untreated As-Dredged NY/NJ Harbor Sediments (Dry Weight)
2,3,7,8 TCDD (ppt)
OCDD (ppt)
Non- NJ
Resid.1 Resid.2
— —
— — ;
Total PCBs (ppm)4
Anthracene (ppb)
Benzo(a)anthracene (ppb)
Chrysene (ppb)
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.
Protection. Non-residential soil,
Protection. Residential soil, dire
Conservation. Recommended :
direct contact. J.J.
A n 7-?RD
set contact. J.J.A.C. 7:26D, revi
soil cleanup objectives. HWR-9
revised 7/1 1/96.
sed 7/1 1/96.
4-046 (Revised).
0.1 •
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

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.


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-
                        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
2,3,7,8 TCDD(pp«)
OCDO {ppt}
As Dredged
Man. Soil
30% As
Percent NJ NJ NY
Reduction Non-Resid.1 Resid.2 Resid.3
63.4 —
69.7 —
64.9 — -- —
Total PCBs (ppm}«
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)
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.

                                                   Vibrating screen to
                                                   separate oversized
                                                                              • Chemicals
                                                                             High pressure water
             Delivery of dredged
              material by barge
           ' Side stream—
          oversized material
                  chemical and water
                          Sediment washer
Organic treatment—
oxidation of organic

        Side stream—
    skimming tank for floatable
      organic contaminants

Collect data on treated
   sediment and
 contaminated water
                                              Pretreatment for metals
                                              and other contaminants
                      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.

Tab!o 3,   Summary ol BioGenesis Sediment-Washing Process
Anthracene (ppb)
Benzo(8)anthracene (ppb)
Chryssne (ppb)
Total PAHs (ppb)<
Arsenic (ppm)
Cadmium (ppm)
Chromium (ppm)
Lead (ppm)
Mercury (ppm) total
Zinc (ppm)
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/
                              fines and
                             washwater Is
 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.

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
2,3,7,8 TCDD (ppt)
O ODD (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)
1 NJ Department of Environmental Protection.
2 NJ Deoartment of Environmental Protection.
Non-residential soil,
Residential soil, dire
direct contact
ct contact J.I
J J A C 7-26D
.A.C. 7:26D. revi:
1 14
revised 7/1 1/96.
sed 7/1 1/96.

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
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
Slope Angle Degrees
Cement Mix
— -
30% Cement Mix
10% Cement Mix
20% Cement Mix
40% Cement Mix
• — ' •
 * All analytical data are based upon the average of all sample test results provided by U.S. ACE-WES.


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.

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.


                        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
                                                     Flue gas
                                               Gas cleanup
                                              _  flue
 (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.



2,3,7,8 TCDD (ppt)
O ODD (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)

1 NJ Department of Environmental Protection.
2 NJ Deoartment of Environmental Protection.

Non-residential soil,
Residential soil, dire
98.47 '
direct contact J J
ct contact. J.J.A.C
. 100
A C 7-26D
7-26D. rev
1 Resid.2
1 .
- — - -
, revised 7/1 1/96.
ised 7/1 1/96.

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.
                     1 Filtrate water
Figure 4.      Schematic diagram showing the production of glass from dredged material using the Westinghouse Science and Technology
              Center plasma torch melter.

Tablo 7,   Summary of Results for the Westinghouse Vitrification Process
2,3,7,8 TCDD{ppl)
0 COD (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
ntal Protection.
Non-residential soil.
direct contact
J.J.A.C. 7:26D
1 Resid.2
.revised 7/1 1/96.

* 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.


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.


  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

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-
Mohsen Amiran, BioGenesis Enterprises Inc., 610
West Rawson Avenue, Oak Creek, Wl 53154.

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.

   The  Fully Integrated  Environmental  Location  Decision
                          Support (FIELDS) System

  An Approach to Identify, Assess and Remediate Contaminated

            Matthew H. Williams, George D. Graettinger, Howard Zar, Dr. Yichun Xie and Brian S. Cooper

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-

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
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".

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:

      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


      Differential Global Positioning Systems (DGPS)

      Environmental Assessment (Sampling and In-field

      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


 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.


 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/

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-

 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

 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/

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

 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.


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.

    Remediation Strategies and Options for Contaminated
                                            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

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

                                              Remedial Options
 Natural Remediation
                        In-silu treat
    Monitor owrtl
    natural bariii




earthen dikes

rubble mound
                                           physical separation
                                             slurry injection
                              Biological   thermal
                              chemical immobilization
                              extraction radiant energy
                                         Confined disposal facility
                                           industrial landfill
                                         hazardous waste landfill
                                     Industrial fill
                                   construction projects
                                    commercial use
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.


                                  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:

 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.


 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.


 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

 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.

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-

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-

 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:

 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
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)


Time availability

Type of contaminants and variability

Environmental performance

Accurate positioning of equipment (if applicable)


Compatibility with site conditions (e.g. size, depth of
contamination, currents)

Compatibility with other technologies in the process

Experience of team

 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.


 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


 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.

     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

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.
            Dredged Material


            SETTLE     DYECON


             LTFATE      MDFATE

  Environmental Effects



        DREDGE    STFATE


         RECOVERY   PUP
 Figure 1.    ADDAMS modules.

Description of ADDAMS
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-
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 [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 [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 [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  [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,

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 [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 [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 [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


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 [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 [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 [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 [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 [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.


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-

Revisions, Updates,  Availability, and

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
3909 Halls Ferry Road
Vicksburg, MS 39180-6199


 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.

        Overview of Ongoing Research and  Development
                                         Dennis L Timberlake
                                  U.S. Environmental Protection Agency
                              National Risk Management Research Laboratory
                                           Cincinnati, OH

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

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

     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.

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

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.

 Corps  of Engineers  Research Programs on Contaminated
                                       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

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.


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.


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

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

Field Verification Program (FVP)

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

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

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-

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

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-

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

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

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.


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


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
    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,

         Potential for Phytoremediation of Contaminated
                                          Steven A. Rock
                                       Environmental Engineer
                              Land Remediation and Pollution Control Division
                              National Risk Management Research Laboratory
                              United States Environmental Protection Agency
                                           Cincinnati, OH

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

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.


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

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-

     Enhanced Rhizosphere Biodegradation
  •   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

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-

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.

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
 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

 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-

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-

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

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-

scale research is still to be done to determine if that
potential will be realized.


 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,

 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,

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.

                    Treatment  of Metal-Bearing Solids

             Using a Buffered Phosphate Stabilization System
                               Thomas Stolzenburg, Senior Applied Chemist
                                          RMT, Incorporated
                                            Madison, Wl

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
     Battery recyclers
     Leaded paint
     Shooting ranges
  •  Mine tailings
     Lead arsenate pesticides
  •  Ash

Some of the chemical stabilization alternatives available
to treat lead include:

     pH Control
          Carbonates: limestone, dolomite
          Magnesium oxide
     Chemical Fixation
          Iron Hydroxides
          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).
1 • ' 1 • I •
:\ v : -f - 7
V,;\ \ / '•/;
^ \ \j jf
	 •• .L- 4 \ - ^'^'l-j- 	
' » \ L' ' / /
! * * /
\ \ /! ' : '
; \ <-/ /
I '\ , /•
\ /
\ X
— -5 mg/L
«*»»» ^u.oi my/L

                                2    4     6     8    10   12   14

Figure 1.    Solubility of lead species as a function of pH.

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
Figure 2.    Solubility of cadmium species as a function of pH.



  650 —I

   65 -



0.065 —
 Figure 3.    Zinc-contaminated site soils—zinc solubility curve.

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.
1 '
™ ,.«. ™. », «„ ^..Kto,^,.,.™,™.™™,^,™,^^.^,^^ „<-,>.„ im. .TO „„
1 1 1 „ J 1 l 1011
5 7 9 11 13
Figure 4.
Foundry waste.
Table 1.   teachability of Smelter Waste*
Lime (% by weight)
Portland Cement
(% by weight)
P + pH
(% by weight)



Final pH,






Final pH,




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

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.


 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.

     Treatment of Dredged  Harbor Sediments by Thermal
                           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

      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-

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-

 Data  generated by this study will be used  by BNL to

      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-
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

Sample Description
was screened prior to use and material 1/2" or larger
was removed.


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
Stage 1

Stage 2

Stage 3
                                                           "Ocean Disposal or Land-Based Product
Figure 1.     Three-stage treatment process for DES.

Tabla 1.   Total Pesticides (ng/kg dry) Untreated and Thermally
         Treated Dredged Estuary Sediment
                         Treatment Temperature (°C)
                           /Residence Time (min)
         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
          Total Polyaromatic Hydrocarbons (jig/kg dry)
          Thermally Treated Dredged Estuary Sediment
                         Treatment Temperature (°C)
                           /Residence Time (min)
Untreated   350/5
lncteflo{1 ,2,3-cd5pyrene
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

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

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.

           PURGE GAS
            1-7 L/min.
                                                    PURGE GAS
                                                    0.3-1 L/min.
                                                                           HEATER   \

     TR1 - RTA Tube Gas thermocouple
     TR2 - Soil Thermocouple
     PI - Pressure Indicator
                               ELECTRIC FURNACE
                                  7500 WATT
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.


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

Table 2.    Mass Balance Date for Thermal Treatment of Dredged Estuarine Sediments
  Stream    Mass
Description   (g)


Tola) to    27,071

47.7     11,919.8      2,996.7
Treated 13,744
Ccmdensate 12,536
Condensate 170
OBgas Solids 147
Carbon Traps 498
Glassware 640
Total Out 26,597'
Recovery % 98.2
5.5 714.7
0.5 62.7
85.0 144.5
5.2 7.6

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
* 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
Run Cement
Number (g)
5 (Lime)
                                                        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

Table 4.
S/S TCLP Results










Chromium .'



<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-

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

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
                            SVOC Anaiyte
                                                     fig/kg in the
             ng/kg in the
                            Naphthalene                  47.9

                            2-Methylnaphtha!ene            25.0

                            Diethylphthalate                33.4

                            Di-n-butylphthalate              60.4

                            bis-2-Ethylhexylphthalate        243.3

                            '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
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 (%)
Dried DES1 3R
• ,17.5
                      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.

             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

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.
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

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

 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

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

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


 0.1 - 34%, frequently on low side

 35 - 47%, frequently near average

 8 - 43%, frequently near average

 10 - 65%, frequently near average
Dioxins/Furans (total)
PCBs (total)
Total Organic Carbon
1-50 ppm
1-10 ppm
2 - 8%
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
<0.01 mg/l
<0.01 - 0.0005 mg/l '
<0.001 - 0.01 ng/l
0.0001 - 0.02 &g/l
<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
      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

 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.

                                         Screened raw sediment
                                           (aqueous slurry)
                     (Uquid - solid)
                     liquid extraction
                         V	S
        high energy - cost
                 This is the focus of
                  M&E's process
  Liquid - solid
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.

            Feed Flow
             Solvent Flow
            Water (A)
        Solid Particles (B)
          with Adsorbed
     Organic Contaminants (C)
              Solvent (D)
             Water (A) @
            Solubility Limit
       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
Figure 2.     Single contact stage of contaminated sediments and solvent at equilibrium.
                                                       Direct Extraction of
                                                      Organic Contaminant
                                                           to Solvent
                       Aqueous Phase
                        Solubility Limit
                                          indirect Extraction of
                                         Organic Contaminant to
                                        Aqueous Phase and then
                                            to Solvent Phase
Figure 3.    Contaminant transfer mechanisms on mixing.

Tabla 2.   Solvent Extraction Processes for Soils/Sediments Treatment
Extraction Temperature (T)
    and Pressurp (P)
Solubility in Water
(Sediment Slurry)
ART International
1st: hydrophilic (acetone,
methanol, isopropanol);
2nd: hydrophobia
    Ambient @ 1 Atmosphere
1st: very high
2nd: very low
(now ECRA-hazardous)
CO2, propane, ethers
Mixture of up to 14 solvents
Acetates, alcohols, and other
special blends
Ambient to 100°+C@ 1
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
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
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
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-

                        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

                          2 i
                          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
               scrubber! Silt,
construction  t'f<*j\
           •L%*» I
          Ctean  Ctean
          gravel  sand
                                                 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
                                                oil (for off-site
                                                                  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
  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-

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-

 Raw sediment -
5cy in one roll-off
  (20 drums) '•
"Water decanting/
• transfer to 5-gal
                            Screened sediment
                                                     |vent system]
                    Washwater is
                   recycled within

Solvent ^s^ ,
make-up >•" \
• "" I
N2 inerting „ t
+ *

pilot plant
analysis only)

[Reagent ^v. 	
Organics-free- ^"fiia
(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

                                             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

 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

Table 4.      Comparison of Pilot Test and Bench-Scale Tests for Dioxin, Furan, and PCB Removal


Dioxins "

Sediment Used
in Pilot Plant
@ Port Newark

123 ppt

5,342 ppt

750 ppt

30,200 ppt

7,946 ppb

ORG-X Only
Pilot Scale
@ Port Newark
(5 extractions with
27.7 ppt

1,029 ppt
96.8 ppt

3,382 ppt
125.3 ppb

ORG-X Only
Pilot Scale
@ Port Newark
(7 extractions with
29.1 ppt

1,030 ppt
97.4 ppt

3,300 ppt
125.0 ppb

ORG-X Only
Pilot Scale
@ Port Newark
(Continuous extraction
with Acetate/Alcohol)
30.3 ppt

1,062 ppt
99.3 ppt

3,198 ppt
134.3 ppb

ORG-X Only
Bench Scale
(3 extractions
with Acetate)

-35% to

-80% to
79 - 92%

     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
Contaminant Characteristics
Total Group PCBs
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
Screened Untreated
<200 ng/L

Pilot SOLFIX-Only
0.2 Parts Cement
<200 ng/L

0.001 '
0.15 Parts Cement
8 ng/L

0.035 .
0.016 '

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
0.3 Cement
UCS, psi
@ 100°C
2.81 E-07
Bulk Dry
Ibs/cu ft
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.


 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-
 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.

  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

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

".-••.-. "•*.•/:'-": 'SUSPENDED ;.'•'•;• • -
 vV ••'-.'"• •-'••' SEDtMENT   • ••-•."-:•.•-.

  (T) Water-side film

  (sf) Diffusion molecular brownian*

  (3) Biaturbalton

  (<[) Gfoundwater advection

  (5) Localized advection

      (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

                  Aroctors 1242/10160,1254 •
                  New Bedford
                  • Sample Station Fx
                                                                   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
                                         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-

 Upland Solid
Waste Landfill
                Estuary or Harbor
Deep Ocean
        Confined                    Contained
   Disposal Facihty  Natura,       Aquatic      in-SITU
                                       Disposal      Capping
                Deep Ocean Basin
                Disposal (Abyssal
 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

                                      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-

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-

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-

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