United States

Environmental Protection

Agency

National Conference on

Management and Treatment of

Contaminated Sediments

Proceedings

Cincinnati, OH

May 13-14, 1997

Office of Research and

Development

Washington, DC 20460

EPA/625/R-98/001

August 1998
i

EPA/625/R-98/001

August1998

National Conference on Management and

Treatment of Contaminated Sediments

Proceeedings

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
ii

Notice

Mention of trade names or commercial products does not

constitute endorsement or recommendation for use.
iii

Foreword

The U.S. Environmental Protection Agency is charged by Congress with protecting the

nation’s land, air, and water resources. Under a mandate of national environmental laws, the

Agency strives to formulate and implement actions leading to a compatible balance between

human activities and the ability of natural systems to support and nurture life. To meet this

mandate, EPA’s research program is providing data and technical support for solving environmental 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 environmental risks in the future.

The National Risk Management Research Laboratory is the Agency’s center for investigation 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 Of fice 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
iv
v

Contents

1. 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. ............. 1

Thomas M. Armitage and F. James Keating

Office of Science and Technology

U.S. Environmental Protection Agency

Washington, D.C.

2. EPA Role in Managing Contaminated Sediment .................................................................. 9

Thomas M. Armitage and Jane Marshall Farris

Office of Science and Technology

U.S. Environmental Protection Agency

Washington, D.C.

3. Strategies and Technologies For Cleaning Up Contaminated Sediments

in the Nation’s Waterways: A Study by the National Research Council ............................. 12

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

4. Solving Great Lakes Contaminated Sediment Problems .................................................... 18

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

5. Perspective on Remediation and Natural Recovery of Contaminated Sediments.............. 27

Dolloff F. Bishop

National Risk Management Research Laboratory

U.S. Environmental Protection Agency

Cincinnati, OH

6. Natural Recovery of Contaminated Sediments—Examples from Puget Sound ................. 37

Todd M. Thornburg and Steve Garbaciak

Hart Crowser, Inc.
vi

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

USACE, 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 .................... 71

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 ........................ 82

Matthew H. Williams, George D. Graettinger, Howard Zar,

Dr. Yichun Xie and Brian S. Cooper

12. Remediation Strategies and Options for Contaminated Sediment ..................................... 85

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 .................................................................................................... 90

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)
vii

14. Overview of Ongoing Research and Development ............................................................. 94

Dennis L. Timberlake

U.S. Environmental Protection Agency

National Risk Management Research Laboratory

Cincinnati, OH

15. Corps of Engineers Research Programs on Contaminated Sediments .............................. 97

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............................................. 101

Steven A. Rock

Environmental Engineer

Land Remediation and Pollution Control Division

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, WI

18. Treatment of Dredged Harbor Sediments by Thermal Desorption ................................... 112

Mary Hall, Ed Alperin and Stuart Shealy, IT Corporation

Keith Jones, Brookhaven National Laboratory

19. Solvent Extraction Process Development to Decontaminate Sediments.......................... 119

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 ...................................................................... 131

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)
viii

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, WI

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
ix

Acknowledgments

The success of the conference and this document is due largely to the efforts of many individuals.

Gratitude goes to each person who was involved.

Presenters and Exhibitors

A special thanks goes to the authors of the papers and demonstrations that were presented at the

conference. Their efforts in preparing papers made this document possible and led to the overall

success of the conference. The participation of the exhibitors whose displays added to the

conference is also appreciated.

Special Thanks

The contributions of the following individuals in the development of the conference are especially

appreciated.

Thomas Armitage, Ph.D., EPA, Office of Water, Washington, D.C.

Edwin Barth, 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.
x

Introduction

The National Conference on Management and Treatment of Contaminated Sediment was held in

Cincinnati, OH, May 13 to 14, 1997. This technology transfer meeting was held for 213 professionals 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 highvolume, 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.
1

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 adverse effects on human and environmental health. The

EPA has prepared this report in response to requirements set forth in the Water Resources Development

Act (WRDA) of 1992, which directed EPA, in consultation with the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Army Corps of Engineers

(USACE), 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 information on the quantity, chemical and physical composition, and geographic location of pollutants in aquatic

sediment, including the probable source of such pollutants and identification of those sediments which are

contaminated. The Act further required EPA to report to

the Congress the findings, conclusions, and recommendations 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 comprehensive and continuing program to assess aquatic sediment quality. As part of this continuing program, EPA

must submit a national sediment quality report to Congress 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 repository for persistent and toxic chemical pollutants released

into the environment. In the aquatic environment, chemical 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 contaminant levels can be devoid of sensitive species and, in

some cases, all species. For example, benthic amphipods were absent from contaminated waterways in Commencement 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 dominate 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 contaminants 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 bullheads in an area of the Black River in Ohio contaminated by PAHs from a coke plant (Baumann et al.,

1987). Examples of risks to fish-eating birds and mammals posed by sediment contaminants include reproductive 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 exposure 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 advisories 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
2

contaminants upon human health and the environment

demonstrate that sediment cleanup is central to effective 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 contaminants include sewage treatment plants and overflows from combined sewers. Industrial point sources

include manufacturing plants and power-generating operations. Atmospheric deposition of contaminants such

as mercury, polychlorinated biphenyls (PCBs) and pesticides 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 agricultural 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 significant human health and ecological risks, Congress directed 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 contaminated sites for additional study, source control and

remediation. WRDA, 1992 defined contaminated sediment as, “sediment containing chemical substances in

excess of appropriate geochemical, toxicological, or sediment quality criteria or measures; or otherwise considered 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, conclusions, and recommendations for action. EPA has produced the first report to Congress in four volumes:

Volume 1: National Sediment Quality Survey—screening analysis to estimate the probability of adverse human or ecological effects based on a weight of evidence

evaluation; Volume 2: Data Summary for Areas of Probable 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 Inventory—screening analysis to identify probable point source

contributors of sediment pollutants; and Volume 4: Sediment Contaminant Nonpoint Source Inventory—screening 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, represented 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 information, 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 Atmospheric 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 Assessment Program (EMAP), and the U.S. Geological Survey

(Massachusetts Bay) Data. In addition to sediment chemistry data, the NSI includes fish tissue residue data,

sediment toxicity bioassay data, benthic abundance data,

histopathology data, and fish abundance data. The sediment 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 assessment of NSI sampling stations.

Data Evaluation Approach

The approach used to evaluate the NSI data focuses on

risks to benthic organisms exposed directly to contaminated 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 sediment 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 conducted. 1) Sediment chemistry measurements were compared 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 apparent effects thresholds for selected organics and metals

(Barrick et al., 1988). 2) The molar concentration of acid
3

volatile sulfides ([AVS]) in sediment was compared to

the molar concentration of simultaneously extracted

metals ([SEM]) in sediment. 3) Available sediment toxicity 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 guidance values (Department of Health and Human Services, 1994; 40CFR 180.213a and 180.142). 2) Fish

tissue contaminant levels were compared to EPA cancer and noncancer risk levels and FDA tolerance, action, or guidance values.

The sediment chemistry screening values used in this

analysis were contaminant concentration reference values above which potential threats to aquatic life may

occur. Independent analyses of matching chemistry and

bioassay data reveal that sediments are frequently nontoxic when chemical concentrations are lower than ERL/

ERMs and TEL/PELs. Sediments are frequently toxic

when chemical concentrations exceed these values (Figure 2). The sediment chemistry screening values used

in the NSI analysis include both theoretically and empirically 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 screening 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 screening values can relate measured concentrations of contaminants to a probability of association with adverse

effects, but do not establish a cause and effect for a

specific chemical. Sediment toxicity bioassays were also

used in the NSI analysis to evaluate sediment sampling

stations.

Theoretical bioaccumulation potential (TBP) and tissue

residue data may be indicative of exposure to contaminated sediments, and were used in the NSI analysis to

evaluate the potential human health effects of sediment

contaminants. TBP is an estimate of contaminant concentration at equilibrium in tissue derived from the sediment 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 concentrations of contaminants that should protect consumers from adverse health effects over a lifetime of

exposure.

Incidence of Sediment Contamination

Sediment sampling stations in the NSI were classified

according to probability of adverse effects. Tier 1 stations are those with sediment contamination associated

with a higher probability of adverse effects. Tier 2 stations 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 values), 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 evaluated, 5,521 (26%) were classified as Tier 1, 10,401

National Monitoring Data 1980-1993

Sediment Chemistry

Measures

Fish Tissue

Residue levels

Acute

Toxicity Tests

Peer Reviewed Screening Level Assessment of

Potential Threat to Human Health or the Environment

Classification of Sampling Stations

Classification of Watersheds

Figure 1. National sediment inventory data.

Fish Tisue

Residue

Levels
4

(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 approximately 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) Program suggest that approximately 10% (by area) of the

near coastal water sediments in the Virginian and Louisianan 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 associated 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

Figure 2. Predicting toxicity with correlative aquatic life screening values. (Long et al., in press)

Figure 3. Sample station classification methodology.

A s mphipod Survival Tests More Sensitive Bioassay

Chemical

Concent c rations % c not toxi % c signif. toxi % c highly toxi % c not toxi % c signif. toxi % highly toxi

A 4 ll <ERLs 6 32 21 76 582

>1 or more

ERL 5 2 9 2 91 02 51 46

>1 or more

ERM 4 3 5 1 24 31 708

A 1 ll <TELs 6 92 01 09 55

>1 or more

TEL 6 1 2 2 71 22 91 95

>1 or more

PEL 4 3 9 1 83 41 887

Sediment Chemistry Aquatic

Life

Sediment Chemistry

Human Health

Tissue Residue Human

H e ealth Toxicity Tests Aquatic Lif

Tier 1

Exceeds 2 upper thresholds*

( s or SQC) T s BP exceeds risk level Exceeds risk level

2 or more tests (different species)

demonstrate significant mortality

[ * SEM]-[AVS]>5 and*

T d ier 2 E s xceeds 1 lower threshol T s BP exceeds risk level TBP exceeds risk level

At least 1 test demonstrates

significant mortality

[SEM]-[AVS]>0

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)
5

throughout the U.S. as APCs (Figure 6). An APC designation 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 identify, 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 importance of these classes of chemicals reflects both the

occurrence of those contaminants in APCs as well as

the evaluation methodology used for the analysis.

Conclusions

Evaluation of the NSI data strongly suggests that sediment 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 contamination 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 areas, and oceans. At the most severely contaminated

sites identified in the NSI, PCBs, mercury, organochlorine pesticides, and PAHs are the most frequent chemical indicators of sediment contamination. The NSI

evaluation methodology was designed to provide a

screening-level assessment of sediment quality. Therefore, further evaluation may be required to confirm that

sediment contamination poses risks to aquatic life or

human health for any given sampling station or watershed. Although Areas of Probable Concern were selected 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 management action.

• Tier 1: Sampling stations with sediment contamination associated with a higher probability of adverse

effects

• Tier 2: Sampling stations with sediment contamination associated with a lower to intermediate probability of adverse effects

• Tier 3: No indication of adverse effects (data may be

very limited or quite extensive)

Figure 4. Classification of NSI sampling stations.

Figure 5. Chemical indicators of probable effects.

12,000

10,000

8000

6000

4000

2000

0

Tier 1 Tier 2 Tier 3

Tier 1

(%)

Tier 1

and 2

(%)

P 8 CBs 5 43

M 0 ercury 2 72

P 5 esticides 1 1 -1 14-2

P 8 AHs 3 3 - 7-1

M 5 etals 0 5 - 7-4

N 1 umber of Stations 5 2 ,52 15,92

Percent of stations indicating a probability of adverse effects
6

Figure 6. Areas (watersheds) of probable concern for sediment contamination.
7

References

1. Aurlich, R. J., R.K. Ringer, and S. Iwamoto. 1973.

Reproductive failure and mortality in mink fed on

Great Lakes fish. Journal of Reproductive Fertility

Suppl. 19:365.

2. Barrick, R., S. Becker, L. Brown, H. Heller, and R.

Pastorok. 1988. Sediment Quality Impairment:

1988 Update and Evaluation of Puget 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 concentrations in brown bullheads from an industrialized 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.

D.J. 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. Development and evaluation of sediment quality assessment guidelines. Prepared for Florida Department

of Environmental Protection, Office of Water Policy,

Tallahassee, Florida, by MacDonald Environmental 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, and T.C. Erdman. 1989. Microcontaminants and reproductive impairment of Forster’s

tern on Green Bay, Lake Michigan, 1983. Archives of Environmental Contamination and Toxicology 18:706-727.

7. Long, E.R., D.D. MacDonald, S.L. Smith, and F.D.

Calder. 1995. Incidence of adverse biological effects within ranges of chemical concentrations in

marine and estuarine sediments. Environmental

Management 19(1):81-97.

8. Long, E.R., L.J. Field, and D.D. MacDonald. Predicting toxicity in marine sediments with numerical

sediment guidelines. Submitted to Env. Toxicol.

Chem.

9. Lyman, W.J., A.E. Glazer, J.H. Ong, and S.F.

Coons. 1987. An Overview of Sediment Quality in

the United States. Prepared for U.S. Environmental 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 contaminants? Hydrobiologia 149:13-30.

12. Swartz, R.C. , W.A. Deben, K.A. Sercu, and J.O.

Lamberson. 1982. Sediment toxicity and distribution of amphipods in Commencement Bay, Washington, U.S.A. Marine Pollution Bulletin 13:359-

364.

13. Van Veld, P.A., D.J. Westbrook, B.R. Woodin,

R.C. Hale, C.L. Smith, R.J. Huggett, and J.J.

Stegman. 1990. Induced cytochrome P-450 in

intestine and liver of spot (Leiostomus xanthurus)

from a polycyclic aromatic contaminated environment. 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-

01a. U.S. Environmental Protection Agency, Office 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. Environmental Protection Agency, Office of Water, Washington, D.C.

16. U.S. EPA. 1993. Technical Basis for Establishing

Sediment Quality Criteria for Nonionic Organic

Contaminants for the Protection of Benthic Organisms 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 Chemical Contamination Data for Use in Fish Advisories,

Volume II : Development of risk-based intake

limits. U.S. Environmental Protection Agency, Office 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 Quality

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
8

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.

21. U.S. EPA. 1997(c) The Incidence and Severity of

Sediment Contamination in Surface Waters of the

United States. Volume 3: National Sediment Contaminant Point Source Inventory. EPA-823-R-97-

008. U.S. EPA Office of Science and Technology,

Washington D.C.
9

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 contaminated 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, controlling the industrial and municipal discharge of sediment

contaminants to water and air, and regulating the disposal 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 Contaminated Sediments - Relevant Statutes and EPA Program Activities (U.S. EPA, 1990).

EPA program offices implement contaminated sediment

management activities or coordinate implementation

where EPA has established geographically focused programs, such as the Chesapeake Bay, the Great Lakes,

and the Gulf of Mexico. EPA program offices with sediment management responsibilities include: the Office of

Water, the Office of Pollution Prevention and Toxics, the

Office of Pesticide Programs, the Office of Emergency

and Remedial Response, and the Office of Solid Waste.

EPA’s Office of Research and Development conducts

research to support sediment management activities

conducted by the program offices.

Contaminated Sediment Management

Goals

EPA’s Contaminated Sediment Management Strategy

(EPA, 1998) describes actions the Agency intends to

take to a accomplish four strategic sediment management 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 consistently apply methodologies for analyzing contaminated sediments.

Elements of Contaminated Sediment

Management

EPA can accomplish the Agency’s strategic goals for

management of contaminated sediment by taking action

in the areas of contaminated sediment assessment,

prevention, remediation of dredged material, research,

and outreach. This paper summarizes EPA’s role in

each of these areas.

Assessment

Many different methods have been developed to assess

contaminated sediment. EPA is working to develop improved assessment methods, standardize the assessment methods, and ensure that all Agency program

offices use standard methods to determine whether

sediments are contaminated. The Agency has also developed chemical-specific sediment quality criteria for

the assessment of contaminated sediment. EPA has

developed standard acute sediment toxicity test methods, 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 assessment 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-
10

tify sites associated with adverse effects to human health

and the environment. Through the use of consistent

sediment assessment methods and the National Sediment 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

bioaccumulation test methods for monitoring and interpretation of narrative water quality standards. The EPA

Office of Pesticide Programs pesticides can use standard sediment toxicity tests when registering or reregistering pesticides. The EPA Office of Pollution Prevention

and Toxics can use standard sediment toxicity tests to

assess the toxicity of industrial use chemicals. The EPA

Office of Emergency and Remedial Response can use

standard sediment toxicity and bioaccumulation test

methods to evaluate contaminated sediment sites by

incorporating these methods into remedial investigation

and feasibility studies, and the EPA Office of Solid

Waste can use biological sediment toxicity test methods

for assessing and monitoring contaminated sediment at

hazardous waste facilities. Sediment quality criteria, when

final, can be used by all EPA program offices conducting

sediment monitoring to interpret sediment chemistry

data.

Prevention

EPA’s role in prevention of contaminated sediments

involves the use of authority provided under the Clean

Water Act, the Federal Insecticide Fungicide, and Rodenticide 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 sediment, 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 Assurance can take action to prevent sediment contamination

by negotiating, in appropriate cases of noncompliance

with permits, enforceable agreements to require sediment contaminant source recycling and source reduction 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

states to prevent point and nonpoint sources of contaminants 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 narrative 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 protect sediment quality; 4) use of discharge data to identify

point sources of sediment contaminants for potential

permit compliance tracking after evaluation using program-specific criteria; 5) ensuring that discharges from

CERCLA and RCRA facilities subject to NPDES permits

comply with future NPDES permit requirements to protect sediment quality; and 6) use of National Sediment

Inventory data to identify watersheds where technical

assistance and grants could effectively be used to reduce nonpoint source loads of sediment contaminants.

Remediation

EPA has an important role in remediation of contaminated 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 circumstances, the best strategy may be to implement

pollution prevention measures as well as point and

nonpoint source controls, to allow natural recovery processes 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 restitution from responsible parties. EPA’s Office of Water,

Office of Emergency and Remedial Response, Office of

Solid Waste, and Office of Enforcement and Compliance 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 requiring 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 options 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 contaminated sediment research. Research is conducted to

understand the extent and severity of sediment contamination, develop methods and data to assess human

health and ecological effects of sediment contaminants,
11

develop and validate chemical-specific sediment quality

criteria, and to develop and evaluate sediment cleanup

methods.

Contaminated Sediment Planning and

Outreach Processes

Outreach is also a critical component of EPA’s role in

contaminated sediment management. Public understanding 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 contaminated 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 channels to facilitate two-way communication on sediment

management issues. EPA can communicate four contaminated 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 interagency coordination and on building alliances with

other agencies, industry, and the public.

References

1. U.S. Environmental Protection Agency. 1990. Contaminated Sediments, Relevant Statutes and EPA

Program Activities. EPA-506-6-90-003. U.S. Environmental Protection Agency, Washington, D.C.

2. U.S. Environmental Protection Agency. 1998.

EPA’s Contaminated Sediment Management Strategy. EPA-823-F-98-001. U.S. Environmental Protection Agency, Washington D.C.

3. U.S. Environmental Protection Agency. 1997(a).

The Incidence and Severity of Sediment Contamination in Surface Waters of the United States.

Volume 1: National Sediment Quality Survey. EPA823-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 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, Washington D.C.

5. U.S. Environmental Protection Agency. 1997(c).

The Incidence and Severity of Sediment Contamination in Surface Waters of the United States.

Volume 3: National Sediment Contaminant Point

Source Inventory. EPA-823-R-97-008. U.S. EPA

Office of Science and Technology, Washington

D.C.
12

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

The management of contaminated sediments is a complex and difficult process. The factors that contribute to

the complexity are multiple and, in combination, exacerbate 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 federal, 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 technologies

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 developed a risk-based framework for making management

decisions and for selecting remediation technologies.

This framework, presented in Figure 1, provides the

Introduction

This presentation is an overview of a study performed by

the National Research Council (NRC) Marine Board

Committee on Contaminated Marine Sediments. The

fifteen-member committee included national experts from

academia, industry, and the professional services sector. 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 (USACE),

the US Navy, the National Marine Fisheries Service of

the US Department of Commerce, the Maritime Administration of the US Department of Transportation, and

the US Geological Survey. The names and affiliations of

the committee members, government liaison representatives, and NRC staff are listed in Table 1.

The Challenge

Contaminated marine sediments pose a threat to ecosystems, marine resources, and human health. Sediment 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 management. Given that approximately 95% of total U.S. trade

passes through dredged ports, potential economic impacts due to sediment contamination may be severe.
13

Table 1. Committee on Contaminated Marine Sediments

HENRY BOKUNIEWICZ, co-chair, State University of New York at Stony Brook

KENNETH S. KAMLET, co-chair, Linowes and Blocher

W. FRANK BOHLEN, University of Connecticut, Avery Point

J. FREDERICK GRASSLE, Rutgers University

DONALD F. HAYES, University of Nebraska

JAMES R. HUNT, University of California at Berkeley

DWAYNE G. LEE, Ralph M. Parsons Company

KENNETH E. MCCONNELL, University of Maryland

SPYROS P. PAVLOU, URS Greiner, Inc

RICHARD PEDDICORD, EA Engineering, Science, and Technology

PETER SHELLEY, Conservation Law Foundation, Inc.

RICHARD SOBEL, Clean Sites, Inc.

LOUIS J. THIBODEAUX, Louisiana State University

JAMES G. WENZEL, NAE, Marine Development Associates, Inc.

LILY Y. YOUNG, Rutgers University

Government Liaison Representatives

SABINE APITZ, U.S. Navy

CHARLES C. CALHOUN, U.S. Army Waterways Experiment Station

MILES CROOK National Marine Fisheries Service

ROBERT ENGLER, U.S. Army Waterways Experiment Station

KENNETH HOOD, U.S. Environmental Protection Agency

EVIE KALKETENIDOU, Maritime Administration

DANIEL LEUBECKER, Maritime Administration

FRANK MANHEIM, U.S. Geological Survey

JANET MORTON, U.S. Geological Survey

ANNA PALMISANO, U.S. Navy

CARL SOBREMISANA, Maritime Administration

MARK SPRENGER, U.S. Environmental Protection Agency

CRAIG VOGT, U.S. Environmental Protection Agency

LARRY ZARAGOZA, U.S. Environmental Protection Agency

Staff

JOSEPH L. ZELIBOR, Project Officer

LAURA OST, Editor
14

MARINE BOARD

NATIONAL RESEARCH

COUNCIL

Conceptual Overview of ContaminatedSediment Management

Driving Forces:

Navigation

Environmental Cleanup

Contaminants

Present?

Remediation

Required?

YES

NO

NO

No

Action

Interim Control?

Source Control?

Conduct PreliminarySite

Assessment/Data

Gathering

Identify Decisions Criteria

and Constraints

Stakeholders Interest

Regulatory Realities

Define Problem

Statement,

Objective and Data

Needs

Removal

Required?

Conduct Site

Specific Assessment

Conduct Analyses:

Risk

Economic

Benefit

Risk-Cost-Benefit

Tradeoff

Decision

Identify and Prioritize

Management

Options

Develop

Management

Plan

Implement

Management

Plan

YES

NO

Remove/Clean

Materials

YES

Figure 1. Conceptual overview of contaminated sediment management.

MARINE BOARD

NATIONAL RESEARCH

COUNCIL
15

basis for a systematic and consistent approach to contaminated sediment management, including dredging

and disposal.

It must be emphasized here that the approach appears

similar to existing decision-making frameworks developed by USEPA and USACE. One of these decisionmaking frameworks was developed by USEPA for

evaluating alternatives for remediation in Superfund

projects. The other was developed jointly by USEPA

and USACE 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 representation (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 components in a logical sequence of evaluations.

Scope of the Study and Approach

The committee’s charge was to: (1) assess best management practices and emerging technologies for reducing adverse environmental impacts; (2) appraise

interim control measures for use at contaminated sediment sites; (3) address how information about risks,

costs, and benefits can be used and communicated to

guide decision making and; (4) assess existing knowledge and identify research needs for enhancing contaminated sediment remediation technology.

Technical information was reviewed and assessed. Committee 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 workshops 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 recommendations.

Conclusions and Recommendations

Improving Decision Making

Factors influencing decision making include regulatory

realities, stakeholder interests, site-specific characteristics and data uncertainty, and availability of remediation

technologies. The committee examined all of the above

factors in making the following conclusions and recommendations:

• Stakeholder involvement early in the decision process is important in heading off disagreements

and building consensus among all parties involved.

In situations where decisions are complex and

divisive, obtaining consensus among stakeholders can be facilitated by using formal analytical

tools, e.g., decision analysis.

• The trade-off evaluation of risks, costs and benefits and the characterization of their associated

uncertainties in selecting a preferred management alternative offer the best chance for effective

management and communication of the decisionmaking 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 USACE 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 containment, 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 preferred management alternative.

• The use of systems engineering can strengthen

project cost effectiveness and acceptability. In

choosing a remediation technology, systems engineering can help ensure that the solution meets

all removal, containment, transport, and placement requirements while satisfying environmental, social and legal demands.

• Federal, state, and local agencies should work

together with appropriate private sector stakeholders to interpret statutes, policies, and regulations in a constructive manner so that negotiations

can move forward and sound solutions are not

blocked or obstructed.

• The USEPA and USACE should continue to develop uniform or parallel procedures to address

human health and environmental risks associated

with freshwater, marine, and land-based disposal,

containment, or beneficial reuse of contaminated

sediments.

• The USEPA and USACE should develop and

disseminate information to stakeholders regarding: the availability and applicability of decision

analytical tools; appropriate risk analysis techniques to be used throughout the management

process, including the selection and evaluation of
16

remedial alternatives; and the demonstration and

appropriate use of decision analysis in an actual

contaminated sediment remediation case.

• The USACE should modify their cost-benefit analysis guidelines and practices to ensure comprehensiveness and uniformity in method application.

Improving Remediation Technologies

Technologies were identified and grouped into four categories: interim control, in-situ management, sediment

removal and transportation, and ex-situ management.

Technologies were compared qualitatively in terms of

state of maturity, frequency of usage, scale of application, cost per cubic yard, and use limitations. The technologies were then scored according to four criteria:

effectiveness, feasibility, practicality, and cost. Based on

the latter information, technologies were ranked according to preference factors. Other topics addressed included technology cost issues across all categories and

the need for remediation technology research, development, testing, and demonstration.

Technology Costs

• Capping, containment and natural recovery are

effective management methods for most contaminated sediments. Where remediation is necessary, high-volume low-cost technologies are the

first choice, assuming they are feasible and succeed in attaining the required risk reduction for

protecting human health and the environment.

Because treatment is expensive, reducing volume

is important.

• Treatment is usually justified only for relatively

small volumes of highly contaminated sediments.

Advanced treatment is too costly in the majority of

cases, which typically involve low-level contamination.

• Cost data for full-scale remediation systems must

be improved to allow for fair overall comparisons

and development of benchmarks for R&D and

systems design. The USEPA and USACE should

develop guidelines for calculating costs of

remediation systems, including technologies and

management methods. The agencies should maintain a database on the costs of systems that have

actually been used.

In-situ Controls

• Natural recovery is viable and can be considered

as an optimum remediation solution when contaminant concentrations are low. If natural recovery is not feasible, capping may be appropriate to

reduce bioavailability. Monitoring is required to

test the efficacy of capping. The use of capping

might be advanced if it were viewed as a permanent remedy under Superfund.

• In-situ chemical treatment has conceptual advantages but considerable R&D will be needed before

successful application can be demonstrated. Similarly, using bioremediation to treat in-place sediments requires further R&D to resolve microbial,

geochemical, and hydrological issues.

Sediment Removal Technologies

The high costs of ex-situ treatment relative to dredging

calls for improvement of dredging technologies to enable sediment removal at near in-situ densities and

precise removal of contaminated sediments to limit the

capture of clean sediments and water. In this manner,

the volume of dredged material requiring containment or

treatment can be reduced.

Ex-situ Controls

• Research is needed to improve control of contaminant releases, long-term monitoring methods,

and techniques for preserving the capacity of

existing confined disposal facilities (CDFs).

• The potential for acceptability of constructing contained aquatic disposal (CAD) facilities on or near

contaminated sites must be explored fully. The

USEPA and USACE should support research to

improve design tools for preventing containment

failure, improve monitoring methods for assessing

long-term performance, control contaminant loss,

and determine risk-reduction effectiveness through

contaminant isolation.

• The USEPA and USACE should support research

for promoting the reuse of CDFs and CADs and

for improving tools for the design and evaluation

of their long-term stability and effectiveness.

• R&D on ex-situ treatment technologies is warranted in the search for cost-effective treatment of

large sediment volumes. Bench- and pilot-scale

testing of ex-situ treatment technologies, and, eventually, full-scale demonstrations in marine systems, are needed to improve cost estimates, resolve technical problems, and improve treatment

effectiveness.

Technology Innovation

Additional R&D and demonstration projects are needed

to improve existing technologies and reduce risks associated with developing and implementing innovative approaches. The advancement of cost-effective and

innovative technologies could be facilitated by peer review of R&D proposals and side-by-side demonstrations

of new and current technologies. The USEPA and

USACE should develop a program to support such R&D

and demonstration projects.
17

Improving Project Implementation

Although improvements in decision-making and

remediation technologies would contribute to cost-effective contaminated sediment management, a variety of

practical issues must be addressed to remove constraints in project implementation. These include responsibility for source control, site characterization needs

and technologies, interim controls, and promotion of

beneficial uses. The committee’s conclusions and recommendations regarding these issues are presented

below.

• As ports currently bear an unfair share of the

responsibility for remediation and placement of

contaminated sediments, project implementation

would be facilitated by transferring the burden for

source control to states and polluters. Federal and

state regulators, together with the ports, should

investigate the use of appropriate legal and enforcement tools to require the upstream contributors to the contamination to share equitably in the

cleanup costs.

• New and improved techniques are needed to

reduce the costs and enhance the precision of site

assessments. The use of remote sensing technologies, including rapid and accurate sensors

may accomplish this goal. The USEPA and USACE

should jointly support R&D to advance the state of

science in site assessment technologies. Objectives should include the identification and development of advanced survey approaches and new

and improved chemical sensors for surveying and

monitoring.

• In cases where sediment contamination poses an

imminent danger, administrative and engineering

or structural controls can be used to reduce risks

to potential human and ecological receptors from

exposure to contaminated sediments over a short

term until a more permanent remedy can be implemented.

• Beneficial uses of dredged contaminated material

can provide disposal alternatives that are socially

acceptable. These may include creation of islands

for seabird nesting, landfills for urban development, beach nourishment, wetlands, shoreline stabilization, topsoil for landfill covers, and other

potential marketable uses of the material. The

USACE should revise its policies to allow for

placement strategies that incorporate the beneficial use of contaminated sediments even if they

are not the lowest cost alternatives. Regulatory

agencies involved in contaminated sediment disposal should develop incentives for and encourage implementation of beneficial use alternatives.

Funding should be continued for R&D of innovative beneficial uses of contaminated sediments

and the development of technical guidance and

procedures for environmentally acceptable beneficial reuse.

Summary

There is no simple solution to the problems created by

contaminated marine sediments. However, the NRC

Marine Board study summarized in this presentation

indicates that careful problem formulation and good

information provide the foundation for good decisions in

managing contaminated sediments. Incremental improvements can be made in decision making, remediation

technologies, and project implementation that may result in cost-effective, socially acceptable, and environmentally sound solutions.
18

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

in 1972) specifically recognized that there is a need to

jointly address concerns about persistent toxic contaminants 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 anthropogenic pollution or perturbation. It has been documented by the International Joint Commission that

sediment contamination is a major cause of such impairment in 42 of the 43 AOCs (3). For the 31 AOCs on the

U.S. side, all RAPs written to date have identified contaminated 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 contaminated sediments, in the 1987 amendments to the Clean

Water Act, Congress authorized the U.S. Environmental

Protection Agency’s (EPA) Great Lakes National Program Office (GLNPO) to coordinate and conduct a 5-

year study and demonstration project relating to the

appropriate treatment of toxic pollutants in bottom sediments. Five areas were specified by Congress as requiring priority consideration in conducting demonstration

projects: Ashtabula River, OH; Buffalo River, NY; Grand

Calumet River, IN; Saginaw Bay, MI; and Sheboygan

Harbor, WI. To fulfill the requirements of this Congressional mandate, GLNPO initiated the Assessment and

Remediation of Contaminated Sediments (ARCS) Program. ARCS was an integrated program for the development and testing of remedial action alternatives for

contaminated sediments.

Introduction

Formed by glacial activity approximately 12,000 years

ago, the Great Lakes comprise a unique ecosystem

that, as a result of industrialization and human intervention, 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 populations of plants and animals, providing a drinking water

supply to support 24 million people and yielding the

mobility to enhance technological production and transportation (1).

Years of point and nonpoint source discharges from

industrial and municipal facilities and urban and agricultural runoff to the Great Lakes and its tributaries have

introduced toxic substances to the Great Lakes ecosystem. 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 contaminants. 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
19

A primary goal of the ARCS Program was to develop an

integrated, comprehensive approach to assessing the

extent and severity of sediment contamination, assessing 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, immobilization, and advanced treatment technologies, as well as the “no action” alternative; and

• Provide guidance on contaminated sediment problems 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 economically feasible.

In meeting the set objectives, issues such as determining the nature and extent of sediment contamination,

defining three-dimensional boundaries of sediment problems, 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 approach, incorporating chemical analyses, toxicity

testing and benthic community surveys, is essential to define the magnitude and extent of sediment contamination at a site.

• Risk assessment and modeling activities are valuable techniques for evaluating the potential impacts associated with contaminated sediments.

• A number of treatment technologies are effective

in removing or destroying sediment contamination.

• Broad public involvement and education are critical in any sediment assessment and remedy seFigure 1. Forty-three areas of concern where beneficial use of water resources is impaired.
20

lection study in order to develop a common understanding of the problem and the environmental

and economic impacts of alternative remedial actions (5).

Though the ARCS Program was completed in August

1994, the guidance that was provided and the technical

knowledge that was gained continue to influence the

ongoing process of addressing contaminated sediments

in the U.S. AOCs.

Assessment

In response to the momentum gained from the ARCS

Program in evaluating sediment contamination in the

Great Lakes, various assessment tools have been utilized and have proven to be beneficial in obtaining an

understanding of sediment contamination and dynamics. A few of these tools include:

• Chemical and Biological Testing

• Research Vessel (R/V) Mudpuppy

• Acoustical Mapping of Bottom and Subbottom

Sediments

• Sediment Resuspension Modeling

• Database Management

Chemical and Biological Testing—One of the recommendations from the ARCS Program that is continually

utilized to define the nature and extent of sediment

contamination at a particular site is the integrated sediment assessment approach (6, 7). This integrated approach 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 surveys 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 assessments 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 information 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 tripleaxle 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 develop sampling plans, testing protocols, and Quality

Assurance Project Plans (QAPPs) for individual projects.

Mudpuppy surveys provide data that allow the threedimensional mapping of these project sites. To date, the

Mudpuppy has been used to perform sediment assessments 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 information necessary for making remedial decisions. The overall goal of this effort is to generate the information

needed to make scientifically defensible remediation

decisions.

Acoustical Mapping of Bottom and Subbottom Sediments—A cost-effective and rapid means of mapping

the distribution of sediments in harbors and rivers facilitates 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 between core sites. Often, due to spatial variation, this

extrapolation provides inaccurate estimates of soft sediment volume and distribution which may require

remediation.

Acoustical profiling of bottom and subbottom sediments

may provide an accurate cost-effective method for mapping sediment distribution. The acoustical coring analysis method developed by Caulfield Engineering and

applied, under contract to the U.S. Army Corps of Engineers, Waterways Experiment Station, was developed

to classify sediments for dredging operations. This approach 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-sections 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 estimates (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 applicability to other AOCs.

Sediment Resuspension Modeling—When attempting to remediate contaminated sediments it is important

not only to know the chemical and biological composi-
21

tion of the sediments, but also to understand the

resuspension/erosion properties associated with the sediments. 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 volumes, depths, and velocities of water in response to

changes in flow and water surface elevation. Additionally, 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 experiments, 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 capabilities enhances both Agency decision making and public

education at all stages of a sediment project.

Toward Remediation

Following completion of the characterization and assessment 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 sediments 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.

Harbor Canal

Maumee R.

L.St. Cla ir

b l

s u

e o

Pre q e Isle Bay

Ashta u a R.

Buffalo R.

Osw g R.

Mile Cr.

Eighteen

R. Raisin

Detroit R.

Clinton R.

Pine R.

Bay

Saginaw

White L.

Menominee R.

Fox R. and

Lower Green Bay

St. Louis R.

Muskegon L.

Harbor

Wauke an g

and Indiana

Grand Calumet R.

Figure 2. Nineteen Great Lakes sites sampled with R/V Mudpuppy.
22

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 placing contaminated sediments in CDFs. The ARCS Program 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 feasible, although they varied in their effectiveness depending 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 (11). 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 demonstrated 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 technologies to be used depended on matching the characteristics of each technology with the specific sediment

type and contaminants present. The results of the benchscale 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 temperature thermal desorption, which uses indirect heat to

separate organic contaminants from contaminated sediments 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 residual 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

Figure 3. Typical shallow seismic system configuration.
23

process removed more than 80% of the PAHs present in

the Buffalo River sediments.

Sediment Washing at Saginaw River, MI—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 sediment 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 chlorinated hydrocarbons not present in significant concentrations at the Buffalo River AOC. The process removed

86% of the PCBs, up to 99% of the semivolatile compounds and more than 92% of the chlorinated volatile

compounds. Mercury was the only heavy metal removed by the process.

Bioremediation at Sheboygan River, WI—Bioremediation 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 manipulate 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 microorganisms, 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.

Figure 4. Sediment cross section from accoustical survey on Trenton Channel, MI.
24

Current Bench-Scale Demonstrations

Building upon information gained from the ARCS program, current projects continue to expand the knowledge base of technologies to remediate contaminated

sediments.

Buffalo River Dredging Demonstration—A demonstration of various dredging technologies was conducted

by the U.S. Army Corps of Engineers (ACE) in collaboration with the U.S. EPA GLNPO. Mechanical and hydraulic dredging equipment were demonstrated for

precise removal of contaminated sediments in the Buffalo 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 benchscale 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 chosen 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 anticipated 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 contaminated sediment sites.

Remediation

Over the last few years a number of sediment cleanups

have occurred in the Great Lakes basin. All of these

have been conducted in association with enforcement

actions, either under Superfund or other authorities.

Descriptions of a number of these cleanups are included

below.

Manistique River, MI—The Manistique River is a tributary to Lake Michigan that is both an AOC and on the

National Priorities List (NPL) for Superfund. The contaminant of concern is PCBs, with concentrations ranging 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 Michigan. Concentrations in carp (Cyprinus carpio) average

approximately 6 ppm of PCB.

In-situ capping had been the preferred alternative of the

Potentially Responsible Parties (PRPs), but the U.S.

EPA Region 5 preferred that the contaminated sediments be removed (dredged). In 1995-6, Region 5 conducted an emergency removal of approximately 18,000

cubic yards of contaminated sediments from a portion of

the River and placed a temporary cap on another deposit to prevent its erosion. Dredging was conducted

using diver assisted techniques to reduce the amount of

resuspension. Prior to commencing of dredging activities in 1995, EPA designed, built or installed:

• Sheet piling and silt barriers to prevent any releases 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 sediments 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 community. The PRPs agreed to pay $6.4 million for EPA to

finish dredging all the river and harbor sediments. Dredging of the rest of the sediments (approximately 100,000

cubic yards) is slated to be started in the Spring of 1997.

Sheboygan River, WI—The Sheboygan River, WI, 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 conducted a voluntary pilot study to evaluate bioremediation

and sediment armoring of PCB-contaminated sediments.

To conduct the bioremediation studies, a 14,000 squarefoot 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 different environments in which to study the effectiveness of

degrading PCBs by enhanced natural biodegradation.

The CTF has a capacity for approximately 1,500 cubic

yards of 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 averaging 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
25

material and gabions placed around the edges to permanently hold the fabric in place. A layer of cobbles was

placed over the geotextile and a layer of roadbed material 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 regarding 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 destroyed at an off-site facility. Over 12,700 tons of material 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 technologies.

For the materials between 50 and 500 ppm PCBs, Slip 3

was made into a permanent containment cell by constructing 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 yards of

PCB-contaminated sediment was placed into this containment cell. This work was completed in the fall of

1993.

Black River, OH—The Black River is an AOC and

tributary to Lake Erie, near Lorain, OH. The primary

contaminant of concern is PAHs, which have been

associated with a number of fish tumors and abnormalities in the river. The U.S. EPA Region 5 and USX-Kobe

Steel Company signed a consent decree in 1985 resulting 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 portion of the Black River.

Between 1988-9, USX-Kobe removed approximately

40,000 cubic yards of 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 contaminated 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 Environmental Management (IDEM) have successfully pursued a

series of enforcement actions against industries and

municipalities in northwest Indiana for violations of various federal and state environmental laws. A significant

amount of the compensation obtained through these

actions will be directed at contaminated sediment

remediation.

The first sediment remediation action completed in this

AOC was conducted by LTV Steel in a slip adjacent to

Indiana Harbor. Approximately 100,000 cubic yards of

contaminated sediments were removed in 1994-5. Initially, dredging was conducted using diver-assisted suction 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 disposal 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 modified 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 contaminants. 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 excavated 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 conducted 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
26

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 undertaken by the U.S. EPA GLNPO please visit the

following Internet site: http://www.epa.gov/glnpo/.

Acknowledgments

The authors would like to thank the following people for

assisting with the completion of this paper: John Filkins,

U.S. EPA, ORD-LLRS, Grosse Ile, MI; Brian Stage, U.S.

EPA, GLNPO, Chicago, IL; and Art Ostaszewski, Michigan Department of Environmental Quality, Lansing, MI.

References

1. Hartig, J.H., and Thomas, R.L. 1988. Development 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, MI.

4. U.S. EPA. 1988. U.S. Progress in Implementing

the Great Lakes Water Quality Agreement, Annex

Reports to the IJC. EPA 905/9-89/006. Chicago,

IL.

5. U.S. EPA. 1994. ARCS Program Final Summary

Report. EPA 905-S-94-001. Chicago, IL.

6. U.S. EPA. 1994. ARCS Assessment Guidance

Document. EPA 905-B94-002. Chicago, IL.

7. Chapman, P.M. 1986. Sediment Quality Criteria

from the Sediment Quality Triad—An Example.

Environ. Toxicol. Chem. 5: 957-964.

8. McGee, R.G., Ballard, R.F., Jr., and Caulfield,

D.D. 1995. A Technique to Assess the Characteristics 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 contaminants in the lower Saginaw River. Journal of Great

Lakes Research. 22(3):669-682.

11. U.S. EPA. 1994. ARCS Program Remediation

Guidance Document. EPA 905-B94-003. Chicago,

IL.

12. U. S. EPA. 1993. ARCS Program Pilot Scale

Demonstration of Thermal Desorption for the Treatment of Buffalo River Sediments. EPA 905-R93-

005. Chicago, IL.

13. U.S. EPA. 1994. ARCS Program Pilot Scale Demonstration 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 Demonstration 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 Demonstration of Thermal Desorption for the Treatment of Ashtabula River Sediments. EPA 905-

R94-021. Ch IL.

16. Averett, D.E., B.D. Perry, E.J. Torrey, and J.A.

Miller. “1990 Review of containment and treatment technologies for remediation of contaminated sediment in the Great Lakes.” Miscellaneous Paper EL-90-25. U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.
27

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 organic matter, that control sediment cohesiveness. Cohesive sediments have large surface area-to-volume

ratios, a net negative charge on their surface and exchangeable cations (1). Thus cohesive sediments adsorb 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 contaminants in sediments, therefore, include a wide variety

of organic compounds and metals adsorbed to the cohesive 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 pesticides, dioxin/dibenzofurans and polynuclear aromatic

hydrocarbons (PAHs) from widely used multicomponent

aroclors, pesticides, and creosotes. These organics partition strongly to and persist in sediments (4, 5, 6). In

addition, less widely used chlorinated organics such as

hexachlorobenzene and trichlorobenzenes can be important contaminants at specific sites (4, 7).

Attenuation Chemistry and Biology

Attenuation mechanisms of the contaminants in sediments include biodegradation, biotransformation, bioturbation (mixing by sediment organisms), dispersion,

dilution, adsorption, volatilization, chemical stabilization

or destruction and burial by clean sediment. With organic contaminants in sediments often highly hydrophobic which can significantly increase the volatility of high

molecular weight organics in wet environments, volatilization 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 contamination are anaerobic except in the upper layer (a few

cm) adjacent to the water column (10). Dissolved oxygen 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 processes (11). Indeed, mass transport limitations in quiescent 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 transports 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 accelerate bioaccumulation. The mixing of sediments into the

water column usually produces only limited and slow

aerobic oxidation or transformation of aerobically degradable or transformable contaminants because the

sediment transport, sorption and bioaccumulation processes are usually substantially faster than the aerobic

degradation or transformation processes (13). Finally,

with dispersion and dilution by clean sediments, biodegradation and/or transformation of the sediment contaminants may be limited because of low concentrations of

contaminant and insufficient biodiversity in the microbial

community.

Concentrations of trace metals in sediments are not

good measures of metal toxicity in watersheds because

field and laboratory studies have revealed that different

sediments exhibit different degrees of toxicity for the

same total quantities of metals (14, 15). Since most

contaminated sediments have low redox potentials, metal
28

reduction processes and precipitation reactions with

sulfides sequester many metals in sediments, usually as

insoluble sulfides (4, 16). The sequestering reduces the

environmental availability and toxic impact of metals to

benthic organisms, watershed fish, animals and humans

(17 - 19).

As an empirical characteristic of sediments, acid volatile

sulfide (AVS) is the sulfide liberated when a sediment is

treated with hydrochloric acid at room temperature under 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 treatment 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 mercury (16 - 19). As a result these important SEMs have

low divalent metal ion concentrations in pore water of

sediments with high ferrous sulfide content.

Based upon research on freshwater and marine sediments 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 transformed 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 hydrophobic contaminants with appropriate Henry Constants in sediments can occur significantly 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 dynamics at the water surface. Currently, uncertainty exists concerning the relative importance of the volatilization

routes and the other attenuation mechanisms for reduction 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 anaerobic and aerobic microorganisms (21 - 26). In general,

the greater the molecular weight of the organic contaminants the greater the partitioning to sorption sites. Large

resident times of contaminants in the sediment (aging)

usually results in increased sequestration. Both effects

reduce the availability of the organic compounds to

microorganisms and thus reduce the extent and rates of

biodegradation.

The PAHs biodegrade most readily through aerobic

processes and the degradation rates usually decrease

as the number of aromatic rings increases (24 - 26).

Biodegradation of most PAHs does not occur appreciably 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 dechlorinate 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 dechlorinated organic species, in general, bioaccumulate less

than the highly chlorinated congeners or species. The

lightly chlorinated PCBs exhibit significantly less potential human carcinogenic and dioxin-like (coplanar structure) toxicity (28, 30) but may be transformed in humans

with potential for other human toxicity (31). While aerobic processes may then biodegrade the lightly chlorinated 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 sediments. Unfortunately the degradation products may be

equally or more toxic and persistent than the original

pesticide or chlorinated organic. As an example, dichlorodiphenyl-trichloroethane (DDT) can be transformed under anaerobic conditions to dichloro-diphenyldichloroethane (DDD) and under aerobic conditions to

dichloro-diphenyl-dichloroethylene (DDE) (34, 35). Although all three DDT constituents may be found in

sediments, DDE is the constituent most widely detected

in the environment (7, 36) and the constituent that is

resistant to further biotransformation (37).

Bioaccumulation

Persistent organic compounds and some metals, principally mercury, bioaccumulate in watersheds with significant 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, mercury, lead, selenium and arsenic can be biologically

methylated. Methylation increases their mobility and, for

mercury, its bioconcentration potential (38). Arsenic sulfides 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
29

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 loadings to a contaminated watershed, may provide less

bioaccumulative impact on migratory fish than large

volumes of low-to-moderately contaminated sediment

which are dispersed over a wide area. Non-migratory

fish and shellfish in highly contaminated areas obviously

will exhibit higher bioaccumulation of contaminants in

their tissues than those in areas with lower levels of

contamination.

Site Characterization

Site characteristics impacting natural attenuation/recovery in sediments include hydraulic flow rates and their

potential chaotic variability; tidal effects; types, depths

and redox conditions of contaminated sediment; distribution, concentrations and types of contaminants; concentrations of total organic carbon in sediments; shoreline

and water uses and conditions; and navigational requirements. The effects of these site characteristics on

the fate and transport of contaminants are not fully

understood, especially for estuarine and marine sediments. Indeed, the rates of natural degradation or transformation of contaminants under various site conditions

are not generally available.

Hydraulic transport of uncontaminated sediments in watersheds can lead to natural covering of contaminated

sediments. Such covering can reduce the availability of

the contaminants and thus bioaccumulation. As an example, the kepone contaminated sediments in the James

River, VA, were covered by uncontaminated sediment

(43). The process of covering or burial by uncontaminated 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 attenuated or require conflicting conditions to support

effective natural attenuation/recovery. As examples, divalent metals in general need anaerobic conditions with

sufficient sulfides (AVS) to minimize metals released to

the water column and eventual bioaccumulation. However, biomethylation of mercury, increasing mobility and

bioaccumulation potential of mercury, is produced under

both anaerobic and aerobic conditions (20). PCB dechlorination requires anaerobic conditions and sufficient organic carbon, probably generating appropriate amounts

of molecular hydrogen, to efficiently dechlorinate the

dioxin-like meta and para chlorine on the biphenyl molecule. Anaerobic conditions, unfortunately, prevent practical aerobic degradation of the resulting lightly chlorinated

PCBs and other aerobically degradable organics such

as PAHs. 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 minimize the effectiveness of natural attenuation.

Monitoring

Long-term monitoring of contaminants in sediments, the

water column and in fish or shellfish has revealed decreasing concentrations of both metals and persistent

organic contaminants (7). With the attenuation mechanisms at sites removing contaminants, with the banning

of many persistent compounds and the improved removal from industrial and municipal point sources, contaminant 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 tissue PCB concentrations with time. However, recently a

leveling of the PCB concentration in the tissue has been

observed (7). In an ongoing survey of mussels and

oysters conducted by the National Oceanic and Atmosphere 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 (45). The main finding, however, was that in the

majority of cases (1898 test areas) there was no statistical 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 estuaries and subsequent sediment dispersion over large areas of the watershed.

Modeling and Risk Assessment

A key factor controlling the fate and migration of persistent contaminants in watersheds is the resuspension

(sediment erosion), transport and dispersion of cohesive

and non-cohesive sediments over wide areas of watersheds. The non-cohesive sediments such as sand do
30

Figure 1. Lake Michigan lake trout (7).

Figure 2. Coho salmon fillets (7).

71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91

Year

5

10

15

20

25

30

Total PCB (μg/g)

Total PCB (μg/g)

0.5

1.0

1.5

2.0

2.5

0

1980 1981 1982 1983 1984 1986 1987 1988 1989 1990 1991

Year

Ct=Co•e-KT

r2=89.6 p<.01

not strongly adsorb contaminants, but do dilute and bury

the contaminated cohesive sediments. A series of models have been developed by the U.S. Environmental

Protection Agency and the Corp of Engineers to characterize the resuspension of sediments in rivers and

streams, estuaries and coastal areas and other large

bodies of water (1, 12, 46 - 52). These models have

been applied and calibrated at various sites (13, 53 -

57). 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 dispersion in the watershed. The state-of-the-art for modeling,

however, is reasonably developed to permit assessments using field data.

A second factor affecting contaminant transport in watersheds involves water erosion of contaminated soil.

Three types of water erosion are usually recognized;

sheet, rill and gully (58). A suitable model for estimating

soil erosion is the Modified Universal Soil Loss Equation

(MUSLE) (59).

Methods for assessing ecological and health risk associated with contaminated sediments are described in appendices 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 criteria (SQC) and sediment quality advisory levels (SQALs)

for nonionic organic chemicals; EPA’s empirical toxicity
31

Figure 3. Cumulative frequency distribution of PCB fish tissue data (4).

A

B

C

D

E

F

1.00E-01 1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04 1.00E+05

PCB in fish tissue concentration (ppb)

0.00

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0.30

0.20

0.10

% of Monitoring Stations

assessment approach for divalent metals using SEM

and AVS concentrations; methods for selecting biotasediment accumulation factors and percent lipid in fish

tissue used to derive theoretical bioaccumulation potentials; screening values of chemicals and frequency of

detection values with estimates of the probability effect

levels; watershed species characteristics related to tissue bioaccumulation; methodology for evaluating toxicity levels; and additional analyses providing perspective

on the important contaminants, PCBs and mercury (Figures 3 and 4; Tables 1 and 2).

Detailed EPA methods are also available for assessing

toxicity and bioaccumulation of contaminants associated with sediments for freshwater (60) and marine

waters (61).

Practical Remediation Approaches

Practical remedial approaches for contaminated sediments include removal by dredging with offsite containment or treatment, in-situ containment (capping), natural

attenuation/natural recovery with long-term monitoring,

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 approaches should involve a site specific risk based cost/

benefit assessment of the various approaches. Procedures are available or can be developed to evaluate

cost/benefits for dredging with offsite containment or

treatment of the dredged sediment and for natural attenuation/natural recovery. Dredging costs, including

the cost for improved environmental dredging technology, and the costs of site characterization and monitoring for natural attenuation/natural recovery can be readily

determined. The effectiveness of in-situ containment

(capping) and no-action with monitoring and institutional

controls are uncertain, although costing of the approaches

on a site specific basis can be estimated.

Natural Attenuation/Recovery

Uncertainties

In summary, a number of factors contribute to uncertainty in and limit the utility of natural attenuation/recovery as a means of remediation of contaminated

sediments. These factors include:

• Anaerobic conditions in sediments that limit aerobic biodegradation of PAHs, partially dechlorinated PCBs and other aerobically degradable contaminants.
32

A

B

C D E F

% of Monitoring Stations

Concentration (ppb)

1.00E-01 1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04

1.00

0.80

0.70

0.60

0.50

0.40

0.30

0.20

0.10

0.00

0.90

Figure 4. Cumulative frequency distribution of mercury fish tissue data (4).

Table 1. Fish Tissue Sampling Stations with Detectable Levels of PCBs that Exceed Various Screening Values (4)

Associated level Level letter in Number of stations Percentage of

Protection of consumers (ppb) PCB exceeding level stations

Cancer risk level 10-6 1.4 A 2,354 99.3

10-5 14 B 2,256 95.2

10-4 140 C 1,686 71.1

Noncancer hazard quotient of 1 220 E 1,473 62.2

FDA tolerance level 2000 F 489 20.6

Wildlife criteria 160 D 1,620 68.4

Table 2. Fish Tissue Sampling Stations with Detectable Levels of Mercury that Exceed Various Screening Values (4)

Associated level Level letter in Number of stations Percentage of

Protection of consumers (ppb) mercury figures exceeding level stations

Canadian guideline 200 B 908 35.1

Noncancer hazard quotient of 1 1,100 E 91 3.5

(1995)

Noncancer hazard quotient of 1 3,231 F 15 0.6

(pre-1995)

Noncancer hazard quotient of 1 646 C 204 7.9

(pre-1995 for infants)

FDA action level 1000 D 103 4.0

Wildlife criteria 57.3 A 2,150 83.0
33

• Mobilization of metals by microbial 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 contaminated sediments and erodible soils caused by

high and chaotic hydraulic flow rates or tidal effects. 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 contaminants even from low [ppb) but widely dispersed

concentrations in sediments.

• With aging of sediments, continued contaminant

availability to bioaccumulation and biomagnification but reduced availability of persistent organics

to biodegradation.

• Widespread quasi-steady-state contaminant residuals in fish and shellfish.

• Ineffective institutional controls to prevent human

consumption of contaminated fish and shellfish.

• Uncontrollable consumption of contaminated fish

and shellfish by watershed predators.

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33. Harkness, M.R., J.B. McDermott, D.A. Abramowicz,

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34. Johnsen, R.E. 1976. DDT metabolism in microbial

systems. Residue Rev. 61:1-28.

35. Rochkind, M.L., and J.W. Blackburn. 1986. Microbial Decomposition of Chlorinated Aromatic Compounds. EPA/600/2-86/090 U.S. Environmental

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36. Stull, J.K., D.J.P. Swift, and A.W. Niedoroda. 1996.

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United States’ rivers. Chem. Geol. 24:315-325.

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EPA 823-R-93-002. U.S. Environmental Protection Agency. Office of Water. Washington, DC.

August.

42. Hesse, J.L. 1993. Case study: Michigan. 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 Water. Washington, DC. September. p 4-45.

43. Hugget, R.J., M.M. Nichols, and M.E. Bender.

1980. Kepone contamination of the James River

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Publishers, Inc. Ann arbor, MI. pp 33-52.

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from the James River Estuary. Sci. And the Total

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U.S. coast from 1996-1993. Marine Environ. Res.

41:183-200.

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Lakes Res. Station. Grosse Ile, NH.

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Modeling System (SMS). Instruction Report CERC92-1. Department of the Army. U.S. Corps of

Engineers. Waterways Experiment Station.

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48. Hanson, H., and N.C. Kraus. 1989. Genesis: Generalized Model for Simulating Shoreline Change.

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the Army. U.S. Corps of Engineers. Waterways

Experiment Station. Vicksburg, MS. December.

49. Rosati, J.D., R.A. Wise, N.C. Kraus, and M. Larson.

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Storm-induced Beach Change, User’s Manual.

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of Engineers. Coastal Engineering Research Program. Washington, DC. May.

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Sedimentation. TABS-MD. IR HL85-1. USAE Waterways Experiment Station. Vicksburg, MS. Orig.

Publication date July 1985.

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using CH3D computer model. In: Proceedings of

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53. Velleux, M., S. Bums, J.V. DePinto, and J.P.

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Contaminants with Freshwater Invertebrates. U.S.

Environmental Protection Agency, Office of Research and Development, Duluth, MN. June.

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Agency. Office of Research and Development.

Washington, DC. September.
37

Natural Recovery of Contaminated Sediments—

Examples from Puget Sound

Todd M. Thornburg and Steve Garbaciak

Hart Crowser, Inc.

The advantages of natural recovery include (1) existing

benthic habitat is not disturbed; (2) buried contaminants

are not remobilized during remedial construction activities; 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 regarding 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, regulatory guidance must be provided regarding the time

period over which recovery can take place, the depth of

compliance for sediment concentrations, the level of risk

that can be tolerated during the recovery period, and the

monitoring requirements during recovery.

Natural Recovery Processes and Data

Needs

Given an appropriate level of source control, natural

recovery of contaminated sediments can occur through

a variety of physical, chemical, and biological processes,

including those depicted on Figure 1. Physical processes include sediment transport and redistribution

processes involving currents (advection), tides (dispersion), sedimentation and resuspension—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 processes 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 sediments (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.

Introduction

With the development of Sediment Quality Objectives

(SQOs) for the Commencement Bay Superfund Site in

Tacoma [1] and the promulgation of the Washington

State Sediment Management Standards (SMS [2]), state

and federal regulatory agencies have been actively pursuing 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 Contaminated Sediment Management Strategy [3]. These programs 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 actions (i.e., dredging or thick capping), whereas areas

which pose a lower risk may be suitable for natural

recovery.

EPA [3] states that active remediation may not be required “if a combination of pollution prevention and

source controls will allow the sediments to recover naturally in an acceptable period of time.” Natural recovery

encompasses the cumulative physical, chemical, and

biological processes which result in a reduction in contaminant concentrations and the risks posed by contaminated sediments over time. Natural recovery is

contingent on source control to prevent ongoing recontamination of sediments. Source control efforts should

consider pollutant inputs to a water body (i.e., control of

outfall discharges, bank/soil erosion, groundwater seepage, etc.) as well as containment of in-water hot spots

which could disperse contaminants into surrounding

areas if left unremediated.
38

Several types of site-specific data are needed to make a

technically defensible demonstration that natural recovery 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 (adFigure 1. Summary of physical, chemical, and biological processes which contribute to the natural recovery of sediments, provided

source controls are in place.

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.

vection and dispersion terms) may be obtained from

current meter deployments, dye-tracing studies, or by

analysis of salinity distributions. Sediment transport parameters (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 identificaVolatilization

Advection

Dispersion

Diffusion

Sedimentation Resuspension

Bioturbation Biodegradation

Burial

Water

Column

Surface

Sediment

Subsurface

Sediment

Washington

State

Bellingham

Whatcom Waterway

Everett

Seattle

Thea Foss Waterway

Tacoma

Manchester

Annex

Olympia
39

tion of stratigraphic markers, such as the depth to a

geologic contact which corresponds to a datable dredging event. Finally, a quantitative assessment of current

source loads to the water body, and potential pollutant

reductions which may be realized by implementing additional source controls in upland drainages, is a critical

component of the evaluation.

Case Studies in Puget Sound

Case studies are presented for three contaminated sediment 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, PCBs, and PAHs). In

addition, the sites provide examples of three different

technical approaches to natural recovery analysis, including (1) empirical trend analysis, (2) one-dimensional

sedimentation/bioturbation modeling [4], and (3)

two-dimensional contaminant transport modeling [5].

Whatcom Waterway Site

The Whatcom Waterway site occupies the primary federal 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, derived 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 result 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 recovery is a viable alternative for lower-risk mercury concentrations in the sediments of the inner bay.

A

Figure 3. 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.

B

0 1 2 3 4 5

0

-20

-40

-60

-80

-100

-120

1.4

1.2

1.0

0.6

0.4

0.2

0

1970 1975 1980 1985 1990 1995 2000 2005

Mercury Concentration in mg/kg

Core depth in cm

Peak depth at 52 cm

Chlor/alkali plant discharge

1965 to 1970

Mercury Concentration in mg/kg

Year

(A) (B)

0.8
40

dynamics of the site are changed. For example, if removal actions are implemented in the navigation channel such that the channel no longer contributes

suspended sediments with elevated mercury concentrations to the inner bay, natural recovery will be accelerated.

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 contaminated 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 mechanical erosion of the toe of the landfill. However, the

preferred remedial alternative at this site includes excavation of the intertidal portion of the landfill, and hydraulic 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

Figure 4. Application of 1-D sedimentation/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

landfill.

A B

A high-resolution mercury profile in a sediment core

from the inner bay is shown on Figure 3A. The subsurface mercury peak of 4.5 mg/kg, between about 45 and

55 cm depth, corresponds to the peak historical discharges 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 independently estimated using radioisotopic dating methods. A

least-squares regression line was fit to the post-1970

data (the period following source control) using an exponential 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 applicability, 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

(A)

Modeled Profile

Core Profile

PCB Concentration in ug/kg

Core Profile

(1995)

Model

Prediction

(2005)

PCB Concentration in ug/kg

0 50 100 150 0 50 100 150

5

10

15

20

0

Depth in Centimeters

5

10

15

20

0

Depth in Centimeters

(B)
41

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 supplying 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 μg/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 bioturbation. 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 concentrations in the upper 5 cm of the core will recover rapidly

following the curtailment of source inputs. The processes 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 sediment, i.e., those sediments which are available for

resuspension into the water column. Based on a correlation between sediment and tissue PCB concentrations

at the site (biota-to-sediment accumulation factor

[BSAF]), the natural recovery model for PCBs in sediment 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 remedial design. The waterway has had a long and complex

urban land use history, and has accumulated a variety

of contaminants, but PAHs and phthalates appear to

pose the greatest risk to the ecological community. In

addition, two large storm drains—remnants of a

once-natural stream channel—collect runoff from much

of the City of Tacoma and discharge to the head of the

waterway.

A more complex model was warranted at this site, due to

the complexity of sources, the diversity of contaminants,

and to help the City manage pollutant loads associated

with storm water discharges. A two-dimensional configuration of the EPA-supported computer code WASP

(Water Quality Analysis Simulation Program) was developed. 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 input parameters, including age-dated cores, sediment

trap deployments, hydrodynamic studies, long-term outfall monitoring, water column sampling, sediment leachability 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 (segments 15 through 21) on a yearly basis for ten years;

shaded boxes indicate predicted sediment concentrations which exceed the Sediment Quality Objective (SQO)

for phenanthrene (1,500 μg/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 describing all of the contaminant transport processes depicted

on Figure 1, and is one of the best tools available for

quantifying the relationship between spatially distributed

source loads and sediment concentrations in a receiving

water body.

Conclusions

Natural recovery should be given due consideration in

the formulation of sediment remedial alternatives, if not

alone, then in combination with more active remedial

technologies such as dredging and/or capping. Natural

recovery has been successfully applied as a key component 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 natural recovery analysis are available, with varying levels of

complexity, which can be tailored to the special needs of

a project.
42

Figure 5. Application of EPA’s Water Quality Analysis Simulation Program (WASP) to natural recovery predictions, Thea Foss Waterway,

Tacoma. (A) 2-D model segmentation scheme, including 7 horizontal segments and 4 vertical segments (surface and deep

water, surface and subsurface sediment). (B) Ten-year model predictions of surface sediment concentrations for phenanthrene

(a PAH). Shaded boxes indicate exceedences of the cleanup level in segments 16, 19, 20, and 21; however, these areas are

predicted to recover within 2 to 8 years.

(B) Predicted Phenanthrene Concentration in Surface Sediment (μg/kg)

Surface Sediment Segment Number

Year 15 16 17 18 19 20 21

0 1,240 2,790 1,230 1,090 2,490 1,800 3,050

1 1,170 2,530 1,150 1,100 2,040 1,530 2,650

2 1,100 2,300 1,090 1,110 1,710 1,350 2,340

3 1,050 2,100 1,040 11,20 1,480 1,220 2,100

4 995 1,920 998 1,130 1,310 1,140 1,900

5 948 1,770 962 1,130 1,190 1,080 1,740

6 906 1,640 933 1,130 1,110 1,050 1,620

7 868 1,520 909 1,140 1,040 1,020 1,520

8 834 1,410 889 1,140 997 1,000 1,450

9 804 1,320 872 1,140 964 991 1,380

10 777 1,240 859 1,140 941 982 1,330

Steady-State 540 673 791 1,150 878 963 1,140

Predicted Sediment Concentration Exceeds SQO

(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)

Thea Foss Waterway

Commencement Bay

14

21

28

13

20

27

12

19

26

Wheeler-Osgood

11

18

25

10

17

24

9

16

23

8

15

22

7

6

2

3

5

4
43

References

1. U.S. EPA, 1989. Commencement Bay Nearshore/

Tideflats Record of Decision, Region 10, Seattle,

WA, September 1989.

2. Washington State Department of Ecology, 1995.

Sediment Management Standards, Chapter

173-204 Washington Administrative Code,

Amended December 1995.

3. U.S. EPA, 1994. EPA’s Contaminated Sediment

Management Strategy, Washington, DC, August

1994.

4. Officer, Charles B., and Daniel R. Lynch, 1989.

Bioturbation, Sedimentation and Sediment-Water

Exchanges. Estuarine, Coastal and Shelf Science

28:1-12.

5. Ambrose, Robert B., Tim A. Wool, and James L.

Martin, 1993. The Water Quality Analysis Simulation Program, WASP 5, Environmental Research

Laboratory, Athens, GA, September 20, 1993.
44

In-Situ Capping of Contaminated Sediment

Overview and Case Studies

Michael R. Palermo

Research Civil Engineer, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS

Abstract

In-situ capping, the placement of a subaqueous covering or cap of clean isolating material over an in-situ

deposit of contaminated sediment, is a potentially economical and effective approach for remediation of contaminated 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-situ capping (ISC) refers to placement of a subaqueous covering or cap over an in-situ deposit of contaminated 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, preventing resuspension and transport to other 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 considered 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 functions be successfully designed, placed, and maintained.

Design Guidance for In-Situ Capping

Detailed guidelines for designing, constructing and managing in-situ capping as a sediment remediation alternative have been developed by the U.S. Environmental

Protection Agency (USEPA) under the Assessment and

Remediation of Contaminated Sediments Program, administered 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 concentration or other benchmark, The cleanup objective will be developed as a prerequisite to the

evaluation of all remediation alternatives.

2. Characterize the contaminated sediment site under consideration for remediation. This includes

gathering data on waterway features (water depths,

bathymetry, currents, wave energies, etc.); waterway uses (navigation, recreation, water supply,

wastewater discharge, etc.); and information on

geotechnical conditions (stratification of underlying sediment layers, depth to bedrock, physical

properties of foundation layers, potential for groundwater flow, etc.). Determine if advective processes

are present and the ability of the cap to control

advective contaminant losses. Determine any institutional constraints associated with placement

of a cap at the site.

3. Characterize the contaminated sediments under

consideration. This includes the physical, chemical, and biological characteristics of the sediments.

These characteristics should be determined both

horizontally and vertically. The results of the characterization, 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 institutional 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
45

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, bioturbation, consolidation, erosion, and other pertinent processes. If the potential for erosion of the

cap is significant, the cap thickness can be increased, 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 techniques 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 management program to include construction monitoring

during cap placement and long-term monitoring

following cap placement. The site management

program should include actions to be taken based

on the results of monitoring and provisions for

future maintenance.

10. Develop cost estimates for the project to include

construction, monitoring and maintenance costs.

If costs are acceptable, implement. If costs are

unacceptable, reevaluate design or consider other

alternatives.

Case Studies

A number of ISC operations have been performed under

varying site conditions, and are summarized in Table 1.

ISC has been applied to riverine, nearshore, and estuarine 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 contaminants.

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 primary 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 included measurements of nutrients in interstitial and overlying water at capped sites, development of a numerical

model for predicting water quality improvements from

capping, and monitoring benthos recovery at capped

sites.

A variety of ISC projects have been conducted in the

Puget Sound area. At the Denny Way project, a layer of

sandy capping sediment was spread over a three-acre

contaminated nearshore area with water depths of 20 to

60 feet (see Figure 2). A combination of a sewer outfall

discharge and combined sewer overflow (CSO) had

contaminated the site with lead, mercury, zinc, PAHs

and PCBs. The capping was a cooperative effort between the Municipality of Metropolitan Seattle (METRO)

and the Seattle District, USACE (3, 4). At the SimpsonTacoma 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, naphthalene, 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 contaminated sediments in water depths of 40-60 feet. Sediments 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 demonstrated at a Superfund site in Sheboygan Falls, WI. 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, MI, an interim cap of 40-mil thick plastic

liner was placed over a small (0.5 acre) deposit of PCBcontaminated sediments in order to prevent the

resuspension and transport of sediments until a final

remediation was implemented. A larger area was evaluated for capping, with the cap design incorporating an

armor layer and sand layer enhanced with activated

carbon (see Figure 1).
46

B. Convair Lagoon, CA

C. Manistique, MI

A. Sheybogan, WI

Figure 1. Illustrations of alternative combinations of cap components.

Sand

Gravel

Geogrid

Existing sediment

24" Min.

12"

Sediments

Gravel

Cobbles

Geotextile
47

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 concentrations 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 composed 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 construction (7). The total area to be capped is approximately 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 incorporated 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 m2

 area of PAHcontaminated 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 longterm 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.

Table 1. Summary of Selected In-Situ Capping Projects

P s roject Location C s ontaminant S n ite Condition Cap Desig

Construction

Methods Reference

Kihama Inner

Lake, Japan N m utrients 3,700 2 Fine sand, 5 and

20cm

Akanoi Bay,

Japan N m utrients 20,000 2 Fine sand, 20 cm

D s enny Way, WA PAHs, PCB 3 acres nearshore with

depths from 20 to 60 ft.

Avg 2.6 of sandy

sediment b 5 arge spreading Sumeri et al. 199

SimpsonTacoma, WAcreosote,

PAHs, dioxins

17 acres nearshore with

varying depth

4 to 20 feet of sandy

sediment

hydraulic pipeline

with “sandbox” Sumeri et al. 1995

Eagle Harbor,

WA cresote 54 acres withinembayment

3 ft of sandy

sediment

barge spreading and

hydraulic jet Sumeri et al. 1995

Sheboygan

River, WI PCBs several small areas ofshallow river/ floodplain

sand layer with

armor stone

direct mechanical

placement Eleder

Manistique

River, MI PCBs 20,000 ft

2 shoal in river

with depths of 10–15 ft 40 mil plastic liner placement by cranefrom barge

Hahnenberg, pers

comm

Hamilton Harbor,

Ontario

PAHs, metals,

nutrients

10,000 m2 portion of

large, industrial harbor 0 e .5 m sand T m remie Tub Zeman, pers com

Convair Lagoon,

CA P e CBs 5 l acres nearshor s n and and grave under constructio

Eitrheim Bay,

Norway

m M etals 100,000 2 geotextile and

gabions d 4 eployed from barge Instanes 199

St.Lawrence

River, Massena,

NY

P t CBs 75,000 f 2 6 in sand/6 in

gravel/6 in stone

placed by bucket

from barge Kenna, pers comm
48

Summary

An ISC operation must be treated as an engineered

project with carefully considered design, construction,

and monitoring to ensure that the design is adequate. A

number of ISC projects have been implemented worldwide 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 monitoring of in-situ capping projects has been developed by

EPA and should be followed when evaluating the feasibility of in-situ capping as a sediment remediation technique.

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.
49

Figure 4. Total area to be capped (approximately 5 acres, Convair Lagoon).

Bathymetry lines

Armor cap

Geotextile cap

Biolayer cap

Sand cap

Perimeter berm
50

Acknowledgment

This paper summarizes work conducted for the U.S.

Environmental Protection Agency Assessment and

Remediation of Contaminated Sediments (ARCS) Program by the U.S. Army Engineer Waterways Experiment

Station. Permission to publish this material was granted

by the Chief of Engineers.

References

1. Palermo, M.R., S. Maynord, J. Miller, and D.

Reible, Guidance for In-Situ Subaqueous Capping of Contaminated Sediments, EPA 905-1396-

004, Assessment and Remediation of Contaminated Sediments Program, Great Lakes National

Figure 5. Sand cap over PAH-contaminated sediments (Hamilton Harbor, Burlington, Ontario).

Figure 6. System of anchors and cables for precise positioning (Hamilton Harbor, Burlington, Ontario).

Program Office, U.S. Environmental Protection

Agency, Chicago, IL.

2. Zeman, A. J., S. Sills, J.E. Graham, and K.A.

Klein, 1992. Subaqueous Capping of Contaminated Sediments: Annotated Bibliography, NWRI

Contribution No. 92-65, National Water Research

Institute, Burlington, Ontario.

3. Sumeri, A. 1989. “Confined Aquatic Disposal and

Capping of Contaminated Bottom Sediments in

Puget Sound,” 12th World Dredging Congress,

Orlando, FL.

4. Sumeri, A. 1995. “Dredged Material is Not Spoil—

A Status on the Use of Dredged Material in Puget

Sound to Isolate Contaminated Sediments,” 14th
51

World Dredging Congress, Amsterdam, The Netherlands.

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 Norwegian Fjord by Use of Geotextiles,” Fifth International Conference on Geotextiles, Geomembranes,

and Related Products, Singapore, 5–9 September

1994.

7. Ogden Environmental and Energy Services. 1993.

Environmental Impact Report—Remedial Action

Plan - Convair Lagoon Remediation, Report prepared for San Diego Unified Port District, San

Diego, California.

8. Zeman, A.J. and T.S. Patterson, 1996a. “Preliminary Results of Demonstration Capping Project in

Hamilton Harbor,” NWRI Contribution No. 96-53,

National Water Research Institute, Burlington,

Ontario.

9. Zeman, A.J. and T.S. Patterson, 1996. “Results of

the In-situ Capping Demonstration Project in

Hamilton Harbor, Lake Ontario,” NWRI Contribution No. 96-75, National Water Research Institute,

Burlington, Ontario.

10. 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.

11. Brannon, J., and M.E. Poindexter-Rollins, 1990.

“Consolidation and Contaminant Migration in a

Capped Dredged Material Deposit,” Sci. Tot Env.,

91, 115–126.

12. Sumeri, A., T.J. Fredette, P.G. Kullberg, J.D. German, D.A. Carey, and P. Pechko, 1994. “Sediment Chemistry Profiles of Capped Dredged Material Deposits Taken 3 to 11 Years after Capping,” Dredging Research Technical Note DRP-5-

09, U.S. Army Engineer Waterways Experiment

Station, Vicksburg, MS.
52

Observations Regarding Brownfields 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

USACE, Great Lakes and Ohio River Division

Chicago, IL

Gregory N. Richardson, Principal

G.N. Richardson & Associates

Raleigh, NC

Abstract

To date, the 25-year delay in dredging the federal project

at Indiana Harbor in East Chicago, IN, has emphasized

the difficulties associated with implementing the current

federal approach to the disposal of contaminated sediments in the Great Lakes. The current method is premised 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 concentrations, 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 generic utility. Concepts rooted in these issues suggest a

new approach for the disposal of contaminated sediments. The new approach would preferentially select

contaminated brownfield sites associated with especially 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.

Introduction

Every year in the Great Lakes approximately 4 million

cubic yards of sediments are dredged. Most of the

dredging is performed to maintain safe depths for commercial and recreational navigation. Approximately half

of these dredged materials are clean, and can be disposed in an unrestricted manner. The remaining 50% of

the sediments dredged (2 million cubic yards) are sufficiently 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 (USACE)

constructs CDFs for the disposal of contaminated sediments dredged from federal navigation projects. In several 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 resemble a simple landfill, consisting of a perimeter earthen

dike with a weir for sediment dewatering. CDFs have

also been constructed in open-water settings, commonly with perimeter dikes of graded stone. The graded The views contained in this paper represent those of the authors and not the

policies or positions of the U.S. EPA or the USACE.
53

stone dike functions as a large filter, retaining the sediment particles while allowing the free passage of water.

The USACE has constructed some 44 CDFs for the

disposal of contaminated dredged material from navigation 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 USACE 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 sponsor is to provide the USACE 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 restrictions. 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 elimination 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 sponsor 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 constructed, 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 implementation problems, many of the perceived clean-site benefits

as well as contaminated-site liabilities could prove illusionary.

The Two Traditional Approaches And

Associated Problems

The In-Water Approach

In practice, the CDF siting strategy has been implemented in the Great Lakes in one of two ways. The more

common scenario centers upon a local sponsor providing the USACE 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 identification can also be relatively straightforward, as a subaqueous site provided to the USACE 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 maintenance 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 inlake/water CDF disposal to become highly controversial,

dissipate local support and make regulatory approval

questionable.

In February of 1986, the problems this scenario can

entail were manifested with effect by a previous attempt

to dredge Indiana Harbor. A Draft Environmental Impact

Statement (DEIS) was prepared and released under the

National Environmental Policy Act (NEPA) (3). The preferred 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 contaminant concentrations (documented in the DEIS) and

the associated environmental considerations, local, state

and federal opposition became strident. After the inevitable 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 USACE for CDF construction and sediment disposal. 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

USACE policy has traditionally required that the site be

uncontaminated. This requirement is in accordance with

USACE guidance and is consistent with generally held

presumptions regarding future liability and site preparation costs.

Not surprisingly, implementation of the upland disposal

scenario for highly contaminated sediments (e.g., Indiana Harbor) has also proven difficult. Like Indiana Harbor, most federal dredging projects are found in highly

urbanized/industrial settings, where clean, adequately

sized sites are rare. Should an acceptable contaminantfree 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
54

government for the land disposal of contaminated sediments 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 concerns regarding site liability.

Lastly, as the public views an upland CDF as a landfill,

the necessary public support can also be limited. Because of the urban setting, the surviving clean, adequately

sized sites proximal to many federal projects exist primarily 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 relatively 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 sediment 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 effectively 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 acquired the property through tax default. The current

brownfield site owner may have had little or no involvement 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 surrounding 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 USACE regulation, the real or perceived presence of environmental contamination fosters

reluctance on the part of owners and potential developers 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 property (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 property. Site-use proposals which would address at least a

portion of the site’s remedial needs would receive receptive 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 remedial 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 tendency for these sites to concentrate in the historically

urbanized and industrialized areas which surround federal navigation projects, brownfield candidate sites should

be readily identifiable at many locations where CDFs are

needed.

The remedial needs of brownfield sites can range from

the trivial to the intractable. This range is a reflection of

the nature of the hydrogeologic factors at the site and

the nature and extent of the contamination. Through the

Technical Impracticability (TI) guidance, the USEPA has

acknowledged that the presence of immiscible nonaqueous phase liquids (NAPLs) at a site can entail

remedial issues which are especially challenging and

which may pose technical limitations to aquifer restoration (5). Essentially this is due to the immobility of a

significant portion of the NAPL contamination under

most groundwater flow conditions. The immobile NAPL
55

fraction resides as small discontinuous accumulations in

the pore space of the geologic material, and is termed,

residual saturation (VNAPL/VVOIDS) (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 saturation 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 hydrocarbons 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 problems (6, 9, 10). NAPL accumulations at residual saturation 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 environmentally acceptable remedial option (7).

Conceptually, containment can be conducted in one of

four ways. While not eliminating the source of the contamination, the purpose behind all containment approaches is to render the impact of the contamination in

the area to be contained on adjacent areas environmentally negligible. With proper consideration of the site’s

hydrogeology, all of the containment approaches discussed below can be incorporated into the design of the

CDF.

The first approach relies on the manipulation of the

groundwater gradients in the vicinity of the region under

consideration through the creation of areas of low hydraulic 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 (commonly in the form of wells). Without the physical placement 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 10-6 to 10-7 cm/s,

comparable to a compacted soil liner) would be constructed 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 containment systems which incorporate physical barriers

also include groundwater extraction (7). Currently, a

fourth approach is receiving much attention and is actively 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 material. As impacted groundwater migrates through the

reactive barrier, the contaminant concentration(s) is sufficiently 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 environmental organizations. After closure of the CDF, the

property could be used for a variety of low-impact applications, such as parks (e.g., a golf course), or light

industry.

The Indiana Harbor Experience

Indiana Harbor

The Grand Calumet River and the Indiana Harbor Canal

(GCR/IHC) drain an area of approximately 174 km2 (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 federal 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 navigation channel, reducing depths and ultimately restricting

navigation traffic. In order to maintain adequate navigational depths, the USACE is authorized to dredge these

sediments when necessary.

From 1955 to 1972, approximately 75,000 m3 of sediments were dredged annually from the federal project at

Indiana Harbor (12). Until 1966, dredged materials were

dumped directly into Lake Michigan at approved openlake 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 disposal site has precluded dredging. This has resulted in

the accumulation of over 760,000 m3 (one million cubic

yards) of highly contaminated sediments within the limits

of the federal project.

Current contaminant sources for the federal project include 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
56

Figure 1. Location of Indiana Harbor (3).

P L A T E 1
57

Figure 2. Federal navigation project at Indiana Harbor (12).
58

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 contaminated 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), polycyclic aromatic compounds (PAHs), volatile organic compounds, and heavy metals. For example, dry weight oil

and grease concentrations for 0.91 m (3 ft) core samples

collected by the USACE 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 USEPA 1977 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

ppm, and would be regulated under the Toxic Substance Control Act (TSCA) if dredged. Through a sampling 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). Currently, sediments which would settle within the limits of

the project if dredged to authorized depths, are discharging 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 USACE 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 estimated 50 to 70% (12).

Current Indiana Harbor Proposal

A second DEIS for the dredging of Indiana Harbor was

jointly issued by the USACE and USEPA Region 5 in

October 1995. Despite the USACE preference for clean

sites, the recommended alternative in the DEIS consisted of the construction of an upland CDF at the

Energy Cooperative Incorporated (ECI) site in East Chicago, IN (Figure 3). As documented in the DEIS, the

selection of the ECI property was based upon the absence of available, clean, close, cost-effective, adequately

sized sites in the area surrounding the federal navigation 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 operation 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 compensation 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 construction. As discussed in more detail below, the site

remediation components and the CDF design components exhibit considerable overlap, thereby further reducing 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 location 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 addition, 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 materials 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
59

Figure 3. Plan view of the proposed ECI site CDF (12).
60

can exceed a thickness of 8 feet. In addition to the

hydrocarbon contamination, other contaminants known

to be associated with the site include PCBs and heavy

metals. Many of these same contaminants are also

found in the IHC sediments. The ground water at much

of the site initially discharged to the Lake George Branch

of the federal navigation project. This resulted in the

release of free-phase oil from the site to the surface

water in the IHC. This situation was corrected in the

early 1990s, when under the direction of the Indiana

Department of Environmental Management (IDEM), an

oil removal system was installed along the edge of the

canal.

Composite/remedial CDF Design

In the early 1990s, Region 5, USACE, IDEM, the City of

East Chicago and other parties became actively involved in assessing the feasibility of coupling the conceptual 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 USACE, and fulfill the closure and corrective action

needs of RCRA. If constructed and operated properly,

this CDF design would provide a comprehensive environmental solution for the underlying portions of the ECI

site and a sediment disposal capacity projected to meet

USACE needs for 30 years. The proposed CDF design

would cover approximately 168 acres of the ECI site,

and would have a containment capacity of 4.7 million

cubic yards. Once the CDF is filled and closed, future

site use options could include use as a park or a golf

course.

The proposed CDF design (Figure 4) features a trapezoidal 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 underlying 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 dewatering/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 PCB contaminated

sediment disposal, fulfill the USACE’s engineering requirements for sediment disposal and meet the longterm disposal capacity needs of the USACE 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 dewatering and/or leachate collection system. As all of these

terms refer to the same mechanism, language preferences would tend to be Agency and program dependent.

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 USACE 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 USACE retains

liability for the CDF design and construction in perpetuity, 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 associated 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

USACE 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 USACE.

At Indiana Harbor, although final agreements have not

been reached, a conceptual framework for the management 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.
61

Figure 4. Section view of the proposed ECI site CDF (12).
62

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 acceptable brownfield site design. Although site-specific, an

upland clean-site CDF designed to contain highly contaminated sediments could entail several feet of compacted 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 preclude 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 monitoring programs can entail significant costs through both

the operational and post-closure periods.

The environmental benefits associated with the construction of a more-enhanced and costly clean/green

site CDF design at locations with significant LNAPL

accumulation, could be limited. At such sites, the additional expenditures required by the enhanced green-site

design components may only succeed in segregating

the in-situ/onsite contamination from the contamination

associated with the sediments. Specifically, the placement of such a green-site design at the ECI site would

do little to remediate the underlying LNAPL contamination, and would leave the RCRA corrective action and

closure needs unaddressed. Should a more-costly greensite 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 greensite CDF and an underlying containment unit were constructed, 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 environmental 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 limitations 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 include 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 underlying the CDF (once constructed) would also generally 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 problems associated with LNAPL contamination are well

documented. Due to the widespread nature of the problem, Agency representatives and local property owners

are attempting to address the issue from a regional

perspective.

Traditionally, under many waste disposal programs, (e.g.,

TSCA, RCRA-Subtitle C, RCRA-Subtitle D), the performance of the waste disposal unit is monitored through

the periodic assessment of the adjacent groundwater

quality down-gradient of the unit’s perimeter. The detection of or an increase in the concentration of a contaminant 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 nature of the onsite contamination (LNAPLs); monitoring

the performance of the proposed CDF through alterations 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 significant interpretational challenges and have little to do

with the performance of the CDF. Properly constructed

and operated, measured alterations in groundwater quality 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 probable that water quality monitoring along the facility perimeter would provide little direct indication of unit

performance, facility performance monitoring may need
63

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 levels) along the exterior of the facility exceeded the hydraulic head value along the adjacent facility interior, the

flow of groundwater would be directed toward the interior of that portion of the CDF.

Application to Sediment Remediation

Projects

Contaminated sediments have been identified as a significant 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 contaminated 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 identified. 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; Indiana Harbor-LTV Steel). Unfortunately, the sediment contamination 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 sediment volumes, where commercial facilities are unavailable 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 proponent (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 government 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 approve 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.

Conclusions

The considerations outlined above are not unique to the

USACE 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 adjacent 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 sponsor 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 inadequate, 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 overlapping remedial and engineering aspects into the design 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 future 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 remedial 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 volumes of contaminated sediments from ecologically sensitive near shore channels and harbors, and idle
64

brownfield sites could be addressed and utilized. This

same approach may also be applicable to the remediation

of contaminated sediment sites.

References

1. Richardson G.N., D.M. Petrovski, R.C. Chaney,

and K.R. Demars, 1995. State of the Art: CDF

Containment Pathway Control, from Dredging,

Remediation and Containment of Contaminated

Sediments, ASTM, STP 1293, ASTM publication

code number 04-012930-38.

2. USACE, June 1992. Hazardous, Toxic, and Radioactive Waste (HTRW) Guidance for Civil Works,

ER 1165-2-132

3. USACE, February 1986. Draft Environmental Impact Statement, Indiana Harbor Confined Disposal 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 Guidance 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. Journal 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. Physical and Chemical Hydrogeology

11. Rumer R.R. and J.K. Mitchell, editors, 1995, Chapter 11. Assessment of Barrier Containment Technologies/A Comprehensive Treatment for Environmental Remediation Applications; U.S. DOE/

U.S. EPA/DuPont Company, product of an International Containment Technology Workshop in

Baltimore, Maryland, August 29-31, 1995.

12. USACE, 1995. Letter Report and Draft Environmental Impact Statement, Maintenance Dredging

and Disposal Activities, Indiana Harbor and Canal, Lake County, Indiana.

13. U.S. EPA, Region 5, 1977. Guidelines for the

Pollutional Classification of Great Lakes Harbor

Sediments.

14. USGS, 1997. Characterization of Fill Deposits in

the Calumet Region of Northwestern Indiana and

Northeastern Illinois, Water-Resources Investigations Report 96-4126
65

Environmental Dredging and Disposal

Overview and Case Studies

Michael R. Palermo, Research Civil Engineer

U.S. Army Engineer Waterways Experiment Station (WES)

Vicksburg, MS

Norman R. Francingues, Chief,

Environmental Engineering Division, WES

Danny E. Averett, Chief,

Environmental Restoration Branch, WES

Abstract

Contaminated sediments are a nationwide problem, and

a wide range of remediation approaches have been

proposed for specific projects. Sediment removal or

“environmental dredging” is viewed by the public as the

most obvious alternative, and is being considered in

some of the most seriously contaminated areas. Environmental dredging followed by treatment and disposal

of the contaminated material has been accomplished at

several Superfund sites. This paper summarizes technical considerations for environmental dredging and disposal of contaminated sediments and presents case

studies of three recently completed projects.

Background

Sediments act as a sink for many contaminants, and

consequently, bottom sediments in many locations nationwide have become polluted because of municipal

and industrial discharges and non-point sources. Options 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 involve 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 sediments at another location. If the decision is made to

remove the sediments, the environmental dredging operation cannot be considered as a separate activity. The

dredging operation and the subsequent disposal and

management of the removed sediments must be compatible.

In recent years, the U.S. Environmental Protection

Agency (USEPA), the U.S. Army Corps of Engineers

(USACE), and others have published a wealth of information on contaminated sediment remediation (1 thru

14). Environmental dredging, sediment treatment, disposal 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 contaminated 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 generally applicable in the context of environmental dredging.

However, resuspension of sediment and associated release of contaminants and removal precision are key

environmental concerns when dealing with contaminated sediments.

All dredges resuspend some sediment during the dredging 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 accurately a given dredge can remove desired areas and

thicknesses of contaminated sediment. Precision is important from the standpoint of removing the contaminated material layers while leaving behind as little residual

contamination as possible. Also, precision is critical from
66

the standpoint of not removing excessive amounts of

clean sediment, since any sediments removed would

likely be treated as contaminated material with the associated 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 sediment 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 hopper 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 conventional dredges are unacceptable, a special purpose

dredge may be required. These dredges generally resuspend 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 contaminated 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 consideration 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 alternatives 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. Pretreatment 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, extraction, immobilization, or thermal. Usually, several pretreatment and treatment process must be used in sequence, forming a “treatment train” to achieve a desired

result. Both untreated and treated material must ultimately be disposed of, and options include CDFs, landfills, subaqueous capping and beneficial use (if the

treatment results in a material acceptable for a given

use).

The following three case studies illustrate some of the

principal technical considerations and lessons learned

in recent projects involving environmental dredging and

disposal.

New Bedford Harbor Hot Spot Case Study

The New Bedford Harbor Superfund site is located in

New Bedford, MA, south of Boston. Sediments throughout the harbor are contaminated with polychlorinated

biphenyls (PCBs) and heavy metals as a result of discharges from industries that operated along the waterfront. 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, copper, 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 procedures were developed during the Pilot Study that resulted in the removal of the contaminated sediments

while minimizing the resuspension of sediments.
67

A confined disposal facility (CDF) had been constructed

along the New Bedford shoreline to contain the contaminated 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 cover

over the large cell into which the dredged material was

initially pumped to control volatilization.

Construction activity began in August 1993 with modifications to the CDF and construction of the water treatment facility. Ongoing community opposition to the

incineration component of the project resulted in construction 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 PCBs 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 contributing 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 contaminant release in the water column.

The operation of the CDF was largely successful. The

effluent discharged during filling operations was controlled 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 elimination 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 experience 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 production, resulting in a much slower removal rate than anticipated. Contaminant release pathways other than sediment resuspension (such as release of oil phases or

volatilization) must be carefully considered when dredging 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 discharged into the Hudson River and into cove and marsh

areas hydraulically connected to the Hudson, contaminating sediments in these areas with cadmium, nickel,

and cobalt. The site was placed on the National Priorities 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 sediments 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 USACE 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 milligrams per kilogram (mg/kg), thickening of the dredged

sediments, chemical fixation of the thickened sediments,

truck transport of the fixated sediments to a local sanitary 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 Hudson River (25 ,27).

As part of the design, scientists and engineers from the

USACE, 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 sediments, 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,” reducing the extent of fill operations.

After the project had been advertised for a construction

contract, the principal responsible parties (PRPs) agreed
68

with the U.S. District Court to perform the remedial

action in accordance with the RODs and the construction plans and specifications developed by the USACE.

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 solidification 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 production 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 hydraulic dredge. These areas were excavated with a

clamshell bucket and transported by scow to an offloading 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/stabilization, and transport by rail to a landfill in Michigan. The

PRP contractor originally chose a mechanical dewatering system consisting of screens and centrifuges. However, 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 mechanical 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 hydraulic dredges. Variability of the material to include

changing water content, grain size, presence of debris,

etc. presents substantial difficulty with respect to materials handling and tends to reduce the efficiency of treatment 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 USACE New Orleans District

combined efforts to implement a remedial action. This

case study is summarized from Ives (29) and Sensebe

(30).

The site is an abandoned creosote wood treatment

facility located along a body of water known as Bayou

Bonfouca, and is adjacent to a very expensive residential 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 contaminated with creosote in Bayou Bonfouca were dredged.

The contractor for the site remediation was a joint venture 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 polynuclear aromatics (PNAs). The material to be dredged

and disposed were classified as silts and clays. Excavation 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 constructed 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 dredging was designed only to remove the layer of contaminated sediments with minor allowances for dredging
69

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 separated for treatment in a 500 gpm treatment plant consisting 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 rehandling (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 destruction 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 operation, resulted in removal within tight tolerances, reducing

the amount of material to be treated. Although a complex treatment train was involved, the overall design

accommodated separation of debris and variations in

the material characteristics.

Summary

Environmental dredging is a contaminated-sediment remedial 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 sediment resuspension and removal precision are key environmental 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. Options for ultimate disposal include CDFs, landfills, subaqueous capping and beneficial use. Field experience

from completed projects will continue to yield valuable

information and lessons learned which can be applied to

future projects.

Acknowledgment

This paper summarizes investigations conducted under

various programs of the U. S. Army Corps of Engineers

and the U.S. Environmental Protection Agency. Permission to publish this material was granted by the Chief of

Engineers.

References

1. Averett, D.E., B.D. Perry, E.J. Torrey, and J.A.

Miller, 1990, “Review of Removal, Containment,

and Treatment Technologies for Remediation of

Contaminated Sediments in the Great Lakes,”

Miscellaneous Paper EL-90-25, U.S. Army Engineer Waterways Experiment Station, Vicksburg,

MS.

2. Demars, K.R., G.N. Richardson, R.N. Yong, and

R.C. Chaney, (editors). 1995. Dredging,

Remediation, and Containment of Contaminated

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ASTM, Philadelphia, PA.

3. National Research Council, 1989, Contaminated

Marine Sediments—Assessment and Remediation,

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4. National Research Council, 1997, Contaminated

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Washington, DC.

5. Permanent International Association of Navigation Congresses (PIANC). 1996. “Handling and

Treatment of Contaminated Dredged Material from

Ports and Inland Waterways—CDM,” Report of

Working Group No. 17 of the Permanent Technical Committee I, Supplement to Bulletin No. 89,

1996, Permanent International Association of Navigation Congresses, Brussels, Belgium.

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U.S. Army Corps of Engineers and U.S. Environmental Protection Agency, Washington, DC.

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for Contaminated Sediment, EPA-823-B93-001,

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D.C.

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Office, Chicago, Illinois.

10. USEPA. 1994a. Assessment Guidance Document,

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of Contaminated Sediments Program, Great Lakes

National Program Office, Chicago, Illinois.
70

11. USEPA. 1994b. Remediation Guidance Document,

EPA 905-R94-003, Assessment and Remediation

of Contaminated Sediments Program, Great Lakes

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12. USEPA. 1994c. Bench-scale Evaluation of Sediment Treatment Technologies: Summary Report,

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13. USEPA. 1994. EPA’s Contaminated Sediment

Management Strategy, EPA 823-R-94-001, Office

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Washington, D.C.

14. USEPA. 1995. Cleaning Up Contaminated Sediment—A Citizen’s Guide, EPA 905-K-95-001, Assessment and Remediation of Contaminated Sediments Program, Great Lakes National Program

Office, Chicago, Illinois.

15. Engler, R.M., N.R. Francingues, and M.R. Palermo,

1991. “Managing Contaminated Sediments: Corps

of Engineers Posturing to Meet the Challenge,”

World Dredging and Marine Construction, August

1991.

16. Palermo, M.R., R.M. Engler, and N.R. Francingues,

1993, “The U.S. Army Corps of Engineers Perspective on Environmental Dredging,” Buffalo Environmental Law Journal, Vol. 1, No. 2., Buffalo,

NY.

17. USACE. 1983. Dredging and Dredged Material

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1983, Office, Chief of Engineers, Washington,

D.C.

18. Hayes, D. L. 1986. “Guide to Selecting a Dredge

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EEDP 09-1, U.S. Army Engineer Waterways Experiment Station, Vicksburg,

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Contaminant Release at the Point of Dredging,”

Environmental Effects of Dredging Technical Note

EEDP-09-3, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

20. Herbich, J.B., and S.B. Brahme, 1991. A Literature Review and Technical Evaluation of Sediment Resuspension During Dredging, Technical

Report (in preparation), US Army Engineer Waterways 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. “Environmental 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 Contaminated 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, Philadelphia, PA.

24. Otis, M.J. 1994. “New Bedford Harbor, Massachusetts 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 Conference on Dredging and Dredged Material Placement, American Society of Civil Engineers, 2,

1201-1209.

26. Nocera, John J., and Thomas M. Simmons. 1994.

“Development of an excavation plan for heavy

metal contaminated marsh deposits [for Marathon

Battery],” Dredging 94—Proceedings of the Second 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 Second 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 International Conference on Dredging and Dredged

Material Placement, American Society of Civil Engineers, 2, 1230-1239.

29. Ives, Pete, 1994. “Bayou Bonfouca,” The Military

Engineer, No. 566.

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Site, Slidell, Louisiana—An Overview,” Proceedings of the Southern States Annual Environmental

Conference Session on Federal Waste Cleanup

Experiences, Biloxi, Mississippi.
71

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

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 stockpiling 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 customers are estimated to be no more than $35 per m3

. A cost

decrease is needed to keep the Port viable and competitive 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 largest 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 decontaminating the dredged material. This makes the development 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 publicprivate partnership arrangements may be necessary at

the inception of individual enterprises.

Abstract

Disposal of dredged material taken from the New York/

New Jersey (NY/NJ) Harbor is problematic because of

the presence of inorganic and organic contaminants that

under revised testing criteria render it unsuitable for

return to the ocean or for beneficial reuse. Decontamination 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 processes and to bring them into full-scale use in the NY/NJ

Harbor is now in progress. Tests of selected technologies have been completed at the bench-scale and pilotscale (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 decontamination system by the end of 1999. The overall

project goals and present status of the project are

reviewed here.

Introduction

The Port of New York and New Jersey requires dredging

approximately 4,000,000 m3

 of sediment each year from

navigational channels and from many different types of

public and private berthing areas. At this time the fraction 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).
72

The purpose of this report is to summarize, 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 decontamination 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 operational treatment facility are:

• Treatment train development

° Selection and testing of treatment technologies

° Pretreatment (physical separation/dewatering)

° 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 assessment. This includes risks from the material and from operation of the decontamination procedures.

° End-use criteria. How clean is clean?

• Operational requirements

° Public outreach

° Business development for beneficial reuse

products

° Develop cost- and profit-sharing public-private partnerships for operation of the facility

Characteristics of NY/NJ Harbor Dredged

Material

The physical characteristics of the sediments found in

the Port are generally very fine-grained silts and clays

(80-95%) with a small fraction of larger grain sizes and

large-size debris. The total organic content of Harbor

sediments ranges from 3-10%. The bulk material has

the consistency of a black mayonnaise or gel. The solids

content of the dredged material is 30% to 40% when

obtained using a conventional clam-shell bucket dredge.

The NY/NJ Harbor estuarine salinity ranges from 1.5 to

28 parts per thousand. The concentrations of major

contaminants and metals found in dredged material

from Newtown Creek, NY, are shown in Table 1. This is

of interest in considering possible pathways for beneficial reuse as manufactured soil, cement, or glass.

Inorganic contaminants include heavy metals such as

cadmium, mercury, lead, arsenic, and chromium. Organic compounds include dioxins and furans, polychlorinated biphenyls (PCBs), polynuclear aromatic

hydrocarbons (PAHs), petroleum hydrocarbons, and chlorinated pesticides and herbicides. Generally, the material is chemically stable and is found to pass the toxicity

characteristic leaching program (TCLP) for testing the

leachability 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 specifications 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 industrialized urban port.

Results of Bench- and Pilot-scale Testing

Programs

Technologies that have been tested have fallen into

those that are carried out (1) at ambient or at least low

temperatures, (2) intermediate temperatures that do not

destroy the organic constituents, and (3) high temperatures above the decomposition point of the organic

compounds. The wide variety of contaminants and differing concentration levels make it plausible to search

for technologies that can be applied to specific concentration levels. In addition, the low-temperature technologies may be more acceptable to the local and regulatory

communities and they may be easier to permit. The
73

higher temperature technologies may be more applicable 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 sediment contamination category are:

• Low contamination. Solidification/stabilization,

manufactured soil, and phytoremediation. U.S.

Army Corps of Engineers (5)

• Low-to-medium contamination. Sediment washing and chemical extraction. BioGenesis Enterprises 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 contaminated 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 preparation 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 compounds 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 longterm monitoring.

The soil is produced by mixing the sediment with a

cellulose material such as wood chips, sawdust, or yardwaste 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

Table 1. Contaminant Concentrations of Untreated As-Dredged NY/NJ Harbor Sediments (Dry Weight)

Newtown Newtown NJ

Creek Creek Port Non- NJ NY

Contaminant (Bench) (Pilot) Newark Resid.1 Resid.2 Resid.3

2,3,7,8 TCDD (ppt) 42 81 66 — — —

OCDD (ppt) 17,463 38,881 5560 — — —

TCDD/TCDF TEQ (ppt) 518 1570 109 — — —

Total PCBs (ppm)4 1.55 1.78 0.141 2 0.49 1

Anthracene (ppb) 3702 1074 167 10,000 10,000 50,000

Benzo(a)anthracene (ppb) 4484 8970 283 4000 900 224

Chrysene (ppb) 4564 9973 365 40,000 9000 400

Total PAHs (ppb)4 113,000 130,000 30,000 — n/a5 396,500

Arsenic (ppm) 33 42 15 20 20 7.5

Cadmium (ppm) 37 47 6 100 1 1

Chromium (ppm) 376 432 171 — — 10

Copper (ppm) 1171 1410 212 600 600 25

Lead (ppm) 617 631 300 600 400 SB6

Mercury (ppm) total 1.3 3.7 2.2 270 14 0.1

Zinc (ppm) 1725 2070 526 1500 1500 20

1 NJ Department of Environmental Protection. Non-residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

2 NJ Department of Environmental Protection. Residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

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.
74

reduction in contaminant concentrations through dilution. 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 procedure may be advisable for producing a soil meeting state

standards. The suitability of the soil for growth of different plant species was tested for tomato, marigold, rye

grass and vinca. The soil was most suitable for the

growth of rye grass.

BioGenesis

A schematic diagram of the sediment-washing equipment 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 hydrocarbons coating the individual sediment grains. The

second step combines a chelating agent and highvelocity 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 components, followed by steps to separate the processed

solids from the water which contains the remains of the

contaminants. The water is processed to meet standards 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 experiment are shown in Table 3. These values are compared to the standards for soil cleanup given by NY and

NJ. Similar values have been obtained for other contaminants.

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 encouraging 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 Engineers to produce a material suitable for unrestricted use

as long as the dredged material contamination can be

reduced to acceptable levels consistent with those mentioned above.

Table 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

Man. Soil

30% As Percent NJ NJ NY

Contaminant As Dredged Dredged Reduction Non-Resid.1 Resid.2 Resid.3

2,3,7,8 TCDD (ppt) 41.5 15.2 63.4 --- --- ---

OCDD (ppt) 17463 5290 69.7 --- --- ---

TCDD/TCDF TEQ (ppt) 518 182 64.9 --- --- ---

Total PCBs (ppm)4 1.22 0.782 68.0 2 0.49 1

Anthracene (ppb) 3700 1590 57.0 10,000 10,000 50,000

Benzo(a)anthracene (ppb) 4480 3130 30.1 4 900 224

Chrysene (ppb) 4560 3720 18.4 40 9000 400

Total PAHs (ppb)4 57,900 35,800 38.2 --- n/a5 396,500

Arsenic (ppm) 33.5 12.5 62.7 20 20 7.5

Cadmium (ppm) 3.0 7.9 78.6 100 1 1

Chromium (ppm) 377 140 62.9 --- --- 10

Copper (ppm) 1172 393 66.5 600 600 25

Lead (ppm) 617 331 46.4 600 400 SB6

Mercury (ppm) total 1.29 --- --- 270 14 0.1

Zinc (ppm) 1725 514 70.2 1500 1500 20

1 NJ Department of Environmental Protection. Non-residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

2 NJ Department of Environmental Protection. Residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

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.
75

Metcalf & Eddy

Solvent extraction procedures are similar to the sediment washing process of BioGenesis in the sense that a

chemical solvent is used to remove the surface coatings

of contaminated materials. Removal of volume contamination 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 apparatus than the BioGenesis process and require more

attention to operating conditions because of fire/explosion 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.

Figure 1. Schematic diagram showing the steps in the sediment washing and chemical extraction processing system developed by

BioGenesis Enterprises.

Solids

Contaminated

water

Side stream

Liquid/solid separation

process (dewatering)

Collect data on treated

sediment and

contaminated water

Organic treatment—

oxidation of organic

contaminants

Sediment washer

Water to publicly owned

treatment works

Pretreatment for metals

and other contaminants

(precipitation)

Side stream

sludges to landfill

Side stream—

skimming tank for floatable

organic contaminants

Mixer

Oxidant

High pressure

water

Foam

Foam

Side stream—

oversized material

disposal

Pretreatment—

chemical and water

mixing

Chemicals

Vibrating screen to

separate oversized

material

Holding tank for

dredged material

Delivery of dredged

material by barge

High pressure water

Product stream—

treated sediment

Air
76

Table 3. Summary of BioGenesis Sediment-Washing Process

Percent NJ NJ NY

Contaminant As-dredged Treated Reduction Non-Resid.1 Resid.2 Resid.3

Anthracene (ppb) 771 177 77.0 10,000 10,000 50,000

Benzo(a)anthracene (ppb) 1793 234 86.9 4000 900 224

Chrysene (ppb) 1994 286 85.7 40,000 9000 400

Total PAHs (ppb)4 19,502 3207 83.6 — n/a5 396,500

Arsenic (ppm) 22.2 12.8 42.3 20 20 7.5

Cadmium (ppm) 18.2 1.4 92.3 100 1 1

Chromium (ppm) 226 63 72.1 — — 10

Copper (ppm) n/a5 n/a5 — 600 600 25

Lead (ppm) 454 60 86.8 600 400 SB6

Mercury (ppm) total 13.1 0.3 97.7 270 14 0.1

Zinc (ppm) — n/a5 — 1500 1500 20

1 NJ Department of Environmental Protection. Non-residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

2 NJ Department of Environmental Protection. Residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

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.

Figure 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 Engineers 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 reported 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 solidified and stabilized dredged material are also given in

Table 5.

Raw sediment

• Water decanting/

adjustment

• screening

Screened

sediment

<1/4"

Oversize

sediment

>1/4"

Oversize

washing

Powerwash

sample only

Recycle

filtered

fines and

washwater is

recycled

Clean

oversize

Decanted

seawater

Extracted

waste oil Wastewater

Solvent

extraction

Vent system

carbon adsorber

Reagent

cement

Solvent

make-up

Solidification/

stabilization

Cured products

• contruction fill/soil

• aggregate

N2 inerting
77

Institute of Gas Technology

The Institute of Gas Technology demonstrated the use

of a rotary kiln for the destruction of organic compounds

and immobilization of metals in the cementitious structure. A block diagram of the apparatus is shown in

Figure 3. The process requires adding common mineral

compounds to optimize the overall composition of the

material for pozzolan production. The technology employed is that commonly in use at existing cement

plants. This is encouraging since it means that existing

off-line facilities could possibly be devoted to processing

Table 4. Summary of Results for the Metcalf & Eddy Solvent Extraction Process

Treated Percent NJ NJ NY

Contaminant As-dredged 7-stage Reduction Non-Resid.1 Resid.2 Resid.3

2,3,7,8 TCDD (ppt) 35 10 71 — — —

O CDD (ppt) 13411 3047 77 — — —

TCDD/TCDF TEQ (ppt) 648 106 84 — — —

Total PCBs (ppm)4 1.54 0.029 98.1 2 0.49 1

Anthracene (ppb) 62,900 1292 97.9 10,000 10,000 50,000

Benzo(a)anthracene (ppb) 38490 894 97.7 4000 900 224

Chrysene (ppb) 33.76 1.01 97.0 40,000 9000 400

Total PAHs (ppb)4 858,000 17,000 98.0 — n/a5 396,500

Arsenic (ppm) 68 85 — 20 20 7.5

Cadmium (ppm) 29 32 — 100 1 1

Chromium (ppm) 319 373 — — — 10

Copper (ppm) 1090 1310 — 600 600 25

Lead (ppm) 632 795 — 600 400 SB6

Mercury (ppm) total 3.5 5,3 — 270 14 0.1

Zinc (ppm) 1505 1750 — 1500 1500 20

1 NJ Department of Environmental Protection. Non-residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

2 NJ Department of Environmental Protection. Residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

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.

Table 5. Results of Physical Testing of Solidification/Stabilization Products*

Metcalf & Eddy Treated Sediment U.S. ACE-WES Screened As-Dredged Sediment

15% Cement Mix 30% Cement Mix 10% Cement Mix 20% Cement Mix 40% Cement Mix

USC in psi 217 614 29 128 492

Water Content at 60°C 53.0 26.9 60.7 27.7 18.1

Water Content at 100°C 71.6 53.7 70.3 5.4 32.1

Specific Gravity 2.70 2.69 2.53 2.61 2.63

Coefficient of Permeability-cm/sec 1.16E-06 4.15E-07 1.42E-05 5.46E-06 3.12E-07

Dry Densisty in lbs/ft3 51.6 64.1 38.1 47.5 57.5

Atterburg Limits

 Liquid 103 — 126 — —

 Plastic 59 — 67 — —

Slope Angle Degrees — — 35.5 — —

* All analytical data are based upon the average of all sample test results provided by U.S. ACE-WES.
78

of dredged material. The results for contaminant reduction are shown in Table 6. There is essentially complete

destruction of organic compounds. The metals are reduced by dilution and by loss to the gaseous sidestream. Moreover, the metal values are in the range

found for commercially available cements. Strength tests

have been carried out and show that the sedimentderived product meets compressive strength standards.

Cement production is therefore a method that is successful in reducing the contamination levels and provides an end product suitable for beneficial reuse.

Westinghouse

The Westinghouse Science and Technology Center demonstrated 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 production 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 productionlevel 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 completion date prior to the next century. This schedule is

dependent on availability of funding from the private

sector. Demonstrations of the sediment-washing approach are planned for early 1998 and operation of a

large-scale demonstration facility by the end of 1998.

Conclusions

A short description has been given of the highlights of a

unique federal program for dredged material demonstrating 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 m3 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 demonstrate that decontamination may be a viable method for

Figure 3. Schematic diagram showing the Institute of Gas Technology system for production of blended cement from dredged material.

Modifiers

As-received

sediments

Gas-fired

Reactive

Melter

2400°-2500°F

Natural

gas + air

Flue gas

quench

EconomeltTM

(glassy material with

cementitious properties)

High quality

blended cement

Additives

Gas cleanup

equipment

Clean

flue

gas
79

Figure 4. Schematic diagram showing the production of glass from dredged material using the Westinghouse Science and Technology

Center plasma torch melter.

Table 6. Summary of Results for the Institute of Gas Technology Cement Process

Percent NJ NJ NY

Contaminant As-dredged Treated Reduction Non-Resid.1 Resid.2 Resid.3

2,3,7,8 TCDD (ppt) 23 0.35 98.47 — — —

O CDD (ppt) 11879 3.7 99.97 — — —

TCDD/TCDF TEQ (ppt) 513.2 1.406 99.72 — — —

Total PCBs (ppm)4 8.6 0.31 96.39 2 0.49 1

Anthracene (ppb) 18735 0 100 10,000 10,000 50,000

Benzo(a)anthracene (ppb) 17155 0 100 4000 900 224

Chrysene (ppb) 16878 0 100 40,000 9000 400

Total PAHs (ppb)4 293,854 0.16 100 — n/a5 396,500

Arsenic (ppm) 39 1.52 96.10 20 20 7.5

Cadmium (ppm) 27 0.66 97.55 100 1 1

Chromium (ppm) 298 632.5 212 — — 10

Copper (ppm) 1012 306 69.76 600 600 25

Lead (ppm) 542 29.4 94.57 600 400 SB6

Mercury (ppm) total 2.8 0.092 96.71 270 14 0.1

Zinc (ppm) 1535 280 81.76 1500 1500 20

1 NJ Department of Environmental Protection. Non-residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

2 NJ Department of Environmental Protection. Residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

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.

Feed

Sediment

Press

Lime

Rinse

water

Screen

Dredged

sediment

Soda ash

Settling/wash tank

Filtrate water

Torch

Plasma

melter

Molten

glass

Gypsum

Melter

offgases

Gas

Cleaning

Scrubber

water bleed

Recirculating

water

Stack

Clean

offgases

Metal

removal

Scrubber

water bleed

Glass

product

Molten glass

manufacturing
80

Table 7. Summary of Results for the Westinghouse Vitrification Process

Percent NJ NJ NY

Contaminant As-dredged Treated Reduction Non-Resid.1 Resid.2 Resid.3

2,3,7,8 TCDD (ppt) 19.0 — 100 — — —

O CDD (ppt) 9655 8.0 100 — — —

TCDD/TCDF TEQ (ppt) 335 0.07 100 — — —

Total PCBs (ppm)4 0.900 0 100 2 0.49 1

Anthracene (ppb) 7.72 0 100 10,000 10,000 50,000

Benzo(a)anthracene (ppb) 7.19 0 100 4000 900 224

Chrysene (ppm) 8.76 0 100 40,000 9000 400

Total PAHs (ppb)4 109 0 100 — n/a5 396,500

Arsenic (ppm) 15.8 4.94 68.7 20 20 7.5

Cadmium (ppm) 33.3 0.948 97.1 100 1 1

Chromium (ppm) 344 1001 — — — 10

Copper (ppm) 1145 1077 5.9 600 600 25

Lead (ppm) 594 105 82.3 600 400 SB6

Mercury (ppm) 2.08 0.087 95.8 270 14 0.1

Zinc (ppm) 1695 1240 26.8 1500 1500 20

1 NJ Department of Environmental Protection. Non-residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

2 NJ Department of Environmental Protection. Residential soil, direct contact. J.J.A.C. 7:26D, revised 7/11/96.

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.

handling at least a portion of the contaminated dredged

material from NY/NJ Harbor.

Acknowledgments

Work at Brookhaven National Laboratory was supported

in part by the U.S. Department of Energy under Contract

No. DE-AC02-76CH00016 and by Interagency Agreements between the U.S. Environmental Protection

Agency (Nos. DW89941761-01-0 and DW89937890-

01-0), the U.S. Army Corps of Engineers (No. NYD-94-

39), and the U.S. Department of Energy.

References

1. U.S. Army Corps of Engineers, New York District.

September 1996. Dredged Material Management

Plan for the Port of New York and New Jersey.

Interim Report.

2. Stern, E. A., Donato, K., Jones, K. W., and Clesceri,

N. L. “Processing contaminated dredged material

from the Port of New York/New Jersey.” Presented at the Estuarine and Coastal Sciences

Association (ECSA) Estuarine Research Federation (ERF) 96 Symposium, Middelburg, The Netherlands, 16-20 September 1996. Estuaries. In

press.

3. Jones, K. W., Stern, E. A., Donato, 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 Conference, The Geo-Institute/ASCE, July 16-17, 1997,

Logan, UT. pp. 49-66.

4. Jones, K. W., Stern, E. A., Donato, K. R., and

Clesceri, N. L. Commercialization of dredgedmaterial decontamination technologies.

Remediation. 8 (2) 43-54 (1998).

5. C. R. Lee, U.S. Army Corps of Engineers, Waterways Experiment Station, Attention: CEWES-ESF, Environmental Processes and Effects Division,

3909 Halls Ferry Road, Vicksburg, MS 39180-

6199.

6. Mohsen Amiran, BioGenesis Enterprises Inc., 610

West Rawson Avenue, Oak Creek, WI 53154.
81

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 Corporation, 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 sediments.” Proceedings of Geoenvironment 2000,

New Orleans, LA, February 1995.

11. Samtani, Naresh C.; Tanal, Vahan; Wang, Joe;

and Lanclelotti, Anthony R. “Effect of lime admixtures on contaminated dredged sediments.” Proceedings of First International Congress on Environmental 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 Administration, National Marine Fisheries Service,

James J. Howard Marine Science Laboratory,

Highlands, NJ. May 1996.
82

The Fully Integrated Environmental Location Decision

Support (FIELDS) System

An Approach to Identify, Assess and Remediate Contaminated

Sediment

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

Introduction

Sound and timely environmental decisions are best

made using complete and reliable information that can

effectively be communicated to all appropriate audiences. 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 Region 5 Water Division and Superfund programs in Chicago. The Region 5 office covers six midwestern states

of Illinois, Indiana, Ohio, Michigan, Minnesota, and Wisconsin, 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 presentation accompanying this paper will provide

examples of how GIS tools can be used to help solve

environmental problems from “start” to “finish”.

Overview

As a practice, geographic areas of interest are defined

by government (state, county, city), environment

(waterbody, geology, soil), or by other interests (demographics, 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, threedimensional states.

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 environmental 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 system.

Nevertheless, the trend is clear: databases and the GIS

tools applied to them will continue to have a profound

impact on the way environmental decisions are being

evaluated, determined and improved. Those who can

sift through the mounting networks of environmental

information to extract or compile critical data, will be

most adept at understanding environmental problems

and most focused on creating the GIS tools to help solve

them.

GIS Groups

Many environmental agencies and organizations now

have centralized GIS groups charged with providing

technical support for programs. Fundamental to establishing 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:
83

• Aerial Mapping (photography, digital orthoquadsDOQs, imaging)

• Computer System Administration

• Communications

• Differential Global Positioning Systems (DGPS)

• Environmental Assessment (Sampling and In-field

Analytical)

• Geographic Information Systems (GIS)

• Human Health and Ecological Risk Assessment

• Internet Web Design and Graphics

• Relational Database Design and Management

• Remedation Alternatives and Costs

• Remediation Project Management

• Statistics

A focused and technically balanced team is essential

because the power of a GIS tool will reflect the collective

knowledge of those who developed it and the quality of

the data they put into it. Users of these tools can then

benefit greatly by having that knowledge and data fully

integrated and immediately available for their use.

Communication

Maps and images are essential to effective communication. They can portray large- and small-scale problems

simply and rapidly to decision makers—helping them to

pursue worthwhile, long-term environmental solutions.

Based on this, the future of databases and GIS tools is

to allow users to identify, manage and view both old and

new environmental data in a “real-time” fashion. Future

GIS users should be able to instantaneously link newly

acquired real-time data with relevant historical data to

perform analyses and obtain displays to support their

decision-making needs.

Fully Integrated Environmental Location

Decision Support System—FIELDS

On the Web: http://ceita.acad.emich.edu/

fields/SHARED/PAGES/FLDHOME.HTM

The FIELDS system is a collection of technical tools and

applications incorporating relational databases, GIS,

GPS, statistical techniques and in-field analytical technologies to inform decision-makers about a variety of

conditions at a site or geographic area of special concern. The FIELDS focus is an in-depth evaluation of

current and historical site-specific conditions to provide

fast, reliable and affordable support to decision-makers

at some of the region’s most contaminated sites.

FIELDS has supported Region 5 site/program managers with determining the spatial distribution of contaminants, volume, mass, human health risk, and remedial

options and costs for sediment hotspot areas. The statistical/spatial analytical tools in FIELDS have been used

for establishing and tracking sediment cleanups of environmental 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 contaminated 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

• Effectively visualizing and communicating options

to decision-makers

• Implementing and tracking environmental cleanups

Meeting these objectives allows users to make scientifically 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 quality. This image must then be made into a map by using

software (e.g. ARC/INFO) to register and rectify the

photograph to vertical and horizontal ground control

points. The control points are established using a variety

of methods such as real-time global positioning systems

(GPS) with sub-meter accuracy.

2. GIS-Based Sampling Design and

Collection

Once an accurate basemap is created, FIELDS can

support the display and analysis of numerous layers of

spatial data. The FIELDS process utilizes the basemap

to design a GIS-based sampling plan for contaminants

of concern within the geographic area of interest. The

sampling design module runs using ArcView Avenue/
84

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 values associated with sample locations and directly generates 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, infield analytical techniques such as onsite Gas Chromatograph/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 database is already set up to receive and use these analytic

data. Obtaining real-time data about the levels of chemicals 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 environmental samples can be immediately loaded into the FIELDS

database structure using the Database Loading Function 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 sitespecific 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 products such maps, images, data summaries and

briefings

These capabilities provide immediately useful and highly

valuable information to support environmental decisionmaking 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 assessed. The quality of environmental data put into GIS

systems must be clearly determined in order to understand 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 expanding its capacity to provide GIS and characterization data

to a broad base of users via a real-time, online mapping

tool that will deliver products in an interactive session.

It is anticipated that before long, maps relating to some

environmental issues will become so widely accessed

by Internet and other means that their familiarity will be

not unlike weather maps of today. Although the public

may not be any more persuaded of the decisions made

by environmental officials than they are of today’s weather

predictors, they may be much better informed.

Conclusion

The future of FIELDS and other GIS-based decision

support systems is to potentially drive when, where, why

and how an environmental problem can be solved. The

more efficient the identification, acquisition and management of relevant environmental data the more likely

that decisions based on these data will achieve measurable environmental benefits.

This will require a continued emphasis on the design of

comprehensive and fully integrated spatial data platforms 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 address a variety of contaminated sediment concerns. The

FIELDS Group provides a wide array of skills, technology, 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 GeoInformatics ‘98 Conference

held in Beijing, China, June 17-19, 1998.
85

Remediation Strategies and Options for Contaminated

Sediment

Carol Ancheta

Scientific Project Officer

Environment Canada

Remediation Technologies Program

Downsview, Ontario, Canada

ing (a) benthic community structure; (b) fish community structure; and (c) bioassays. Bioavailability

and bioaccumulation studies should also be considered during this phase of the evaluation. It is

important to note that even though the benthic

community may suggest a healthy structure, persistent 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 identify exposure pathways and evaluate impacts associated 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 biodegradation of the contaminants are anticipated and/or sedimentation and natural burial will most likely occur in the

area of concern. If this option is selected, monitoring of

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 technologies is outlined with a brief discussion on selection

methodologies for preferred options and technologies.

The case study on Thunder Bay provides a current

example of how contaminated sediment is being

remediated.

Understanding the Problem

To determine when remediation is required, the following 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. Examples include conducting interviews, visiting the

site, reviewing historical information including existing reports, describing the site and surrounding

area in detail, and identifying historical and ongoing 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-
86

the area over time is required to determine the implications 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 investigated prior to selection of this option to determine

environmental effects. Monitoring these reactions during

and after application is required.

In-situ 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 biological processes are used. An oxidizing agent is injected into the sediment in order to facilitate microbial

metabolic activity and degradation of contaminants.

Immobilization (solidification/stabilization): technologies

which change the state of the sediment, either physically

or chemically, and reduce the potential for contaminant

migration. Fixatives such as cements, pozzolans, and

thermoplastics are used.

Cap

This option allows for clean material to be placed over

top of the contaminated sediment. The clean material

creates a physical barrier between the contaminants

and the overlying and surrounding environment. Examples of possible environmental issues to consider

before selection of this option include groundwater effects, contaminant migration, bioturbation zones, durability and weathering effects of the cap over time.

Monitoring and possible maintenance of the cap in

perpetuity is required.

Capping technologies include:

Figure 1. Remedial options and technologies.

Natural Remediation

Dewater

passive/mechanical

physical separation

slurry injection

Re-use

Biological

chemical

extraction

Confined disposal facility

industrial landfill

hazardous waste landfill

Dispose Treat

Mechanical

hydraulic

hybrid

In-situ treat Remove Cap Contain

Sheetpiling

earthen dikes

rubble mound

Monitor natural

biodegradation

sedimentation and

natural burial

Biological

chemical

chemical/biological

immobilization

Subaqueous

dry

thermal

immobilization

radiant energy

Industrial fill

construction projects

commercial use

Pre-treat

Remedial Options
87

Subaqueous cap: Controlled and accurate placement of

clean material is laid over top of in place contaminated

sediment creating a bioturbation zone.

Dry cap: placement of a large volume of clean material

over the sediment so that the final elevation of the cap

surface is above the water level.

Contain

This option allows for containment of the site by creating

a physical barrier which surrounds the zone of contamination. Examples of possible environmental impacts to

consider before selection of this option include groundwater 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 between each piling.

Earthen dikes: generally homogeneous earth material.

Rubble mound: The core material is usually clay. The

core is surrounded by either: (1) fine granular material,

increasing in coarseness and grain size as it moves

outward away from the core; or (2) surrounded by a

synthetic filter material.

Dredge

This option allows for the physical removal of the contaminated sediment from the site. End use of the material 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 horizontal site boundaries; (2) positioning accuracy of the dredge,

both vertical and horizontal, and experience of the operator; (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 performance 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, hopper, pneuma, oozer, and portable dredges.

Hybrid: mechanical force is used for the initial handling

of the material, followed by pumping. An example includes the amphibex.

Contaminants are found predominantly in fine grain size

sediment including clay, silt and sand. Regardless of the

end use of the material, contaminated dredged material

is usually pre-treated to reduce water content, remove

debris, remove oversized uncontaminated particles, to

accelerate settling time and/or to accelerate microbial

action.

Pre-treatment technologies include:

Dewatering: dewatering sediment involves reducing the

water content of the sediment.

Passive: air drying technologies which dewater the sediment 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 accelerated 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 floatation, magnetic separation, and gravity separators.
88

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 categories.

Biological: treatment technologies which use bacteria,

fungi and/or enzymes to accelerate the natural biodegradation 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 temperature, are the mechanisms whereby target contaminants are converted to less or nontoxic byproducts.

Examples include landfarming, and bioslurry.

Chemical: technologies which add chemical reagents to

the sediment in order to destroy, detoxify, or remove the

contaminants. Examples include dechlorination, and oxidation.

Extraction: uses a solvent to desorb or separate the

organic contaminants from the particulate solids, and

concentrate them in reduced volumes. Examples include 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, erosion, volatilization potential of contaminants) after its

disposal. Solidification examples include cements, silicates, and pozzolans. Stabilization examples include

polymers such as urea formaldehyde.

Thermal: technologies which heat the sediment to several 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 consortium, 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 Thunder 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 expensive 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 secondary response. Those sediments below the secondary 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 environmental clay barrier and offshore containment berm has

been constructed to contain and isolate the majority of

contaminants from the harbour. Severely toxic sediments 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 habitat 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 contamination 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 effectiveness 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:
89

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 summations of each dollar value are compared.

Open bidding process: competitive bids decide the preferred option.

Demonstration technology evaluation: bench and/or pilot 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 selected as preferred options.

Project team: consensus is given among project team

members.

Technology Selection:

Many variables need to be considered when selecting

applicable technologies for the preferred option. Some

key considerations include:

Cost versus budget allocation

End use of the material (disposal versus re-use)

Productivity

Time availability

Type of contaminants and variability

Environmental performance

Accurate positioning of equipment (if applicable)

Transportability

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

contamination, currents)

Compatibility with other technologies in the process

stream

Experience of team

SEDTEC

SEDTEC, Sediment Technology Directory, is a userfriendly computer software product listing removal and

treatment technologies for contaminated sediment and

treatment technologies for contaminated soil and sludges. Based on an international inventory of manufacturers and vendors of technologies, this database was

originally developed by Environment Canada to identify

suitable technologies for dealing with contaminated sediment. 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 directory was demonstrated on May 14, 1997 at the U.S.

EPA National Conference on Management and Treatment of Contaminated Sediments in Cincinnati, OH.

Conclusion

This paper introduces the reader to phases involved in a

site assessment, to the types of remedial options available and to the sediment remediation technologies on

the market today. Selection methodologies and considerations for technology selection are also provided.

Understanding the nature and extent of sediment contamination is the first step to defining the solution. Investigating all of the options, individually and collectively,

and identifying suitable technologies is instrumental in

determining the preferred options. Selecting the remedial solution for the area of concern is site specific. One

should draw upon other experiences through case studies. In many cases, the decision will be community

based.

References

1. Ancheta, C. 1996. Randle Reef Sediment

Remediation Project, Analysis of Alternatives Report. 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 Report. Downsview, Ontario.

3. Jaagumagi, R. and D. Persaud. 1995. Sediment

Assessment and Remediation Ontario Approach.

Sediment Remediation ’95. Windsor, Ontario.
90

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

sonal computer (PC)-based design and analysis system

for dredged material management (1). ADDAMS contains 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 USACE/

USEPA technical guidance (2). (See Figure 1.) This

paper describes the system, currently available applications, mechanisms for acquiring and running the system, and provisions for revision and expansion.

Background

Planning, design, and management of dredging and

dredged material disposal projects often require complex or tedious calculations or involve complex decisionmaking criteria. In addition, the evaluations often must

be done for several disposal alternatives or disposal

sites. The Automated Dredging and Disposal Alternatives Modeling System (ADDAMS) is an interactive perFigure 1. ADDAMS modules.
91

Description of ADDAMS

ADDAMS is composed of individual modules or applications, 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 alternatives. The objective of the ADDAMS is to provide stateof-the-art computer-based tools that will increase the

accuracy, reliability, and cost-effectiveness of Corps

dredged material management activities in a timely manner.

Most of the current ADDAMS programs employ a menudriven 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 applications are programmed to run in the Microsoft Windows

environment, and all modules will eventually be converted to a Windows format.

Each ADDAMS application has documentation describing how to run that application, and how that application

functions. A list of references is provided directly onscreen 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 regarding the respective applications. In addition, computerized 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 contents range from simple algebraic expressions, both

theoretical and empirical in origin, to numerically intense

algorithms spawned by the increasing power and

affordability of computers. A brief description of each of

the currently available applications follows.

SETTLE

SETTLE [full title: Design of Confined Disposal Facilities

(CDFs) for Suspended Solids Retention and Initial Storage 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, clarification, and effluent suspended solids. Laboratory column 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

PSDDF [full title: Primary Consolidation, Secondary Compression, 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 storage 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 resulting 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 estimation 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 consolidation properties.

DYECON

DYECON [full title: Determination of Hydraulic Retention

Time and Efficiency of Confined Disposal Facilities]

provides a computer program to determine mean hydraulic retention time and hydraulic efficiency of a confined 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 absence of dye tracer data, the hydraulic efficiency can be

estimated empirically.

D2M2

D2M2 [full title: Optimization of Long-Term Operation,

Expansion, and Acquisition of Multiple Disposal Sites for

Multiple Dredging Reaches], developed by the U.S.

Army Engineer Hydrologic Engineering Center (HEC)

and modified for the San Francisco District, is a simulation-optimization model for systematic analysis of longterm operation and expansion of multiple disposal sites.

The model provides a means of determining the optimum 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 determining the optimum usage based on input data for dredging

volumes, location, frequencies, transportation facilities,

and associated costs.

STFATE

STFATE [full title: Short-Term Fate of Dredged Material

Disposed in Open Water for Predicting Deposition and

Water Quality Effects] provides mathematical modeling

of the physical processes determining the short-term

fate of dredged material disposed at open-water sites,
92

that is, within the first few hours after disposal. STFATE

was developed from the DIFID (DIsposal From an Instantaneous Dump) model. In STFATE, the behavior of

the material is assumed to be separated into three

phases: convective descent, dynamic collapse, and passive transport-dispersion. The model provides estimates

of receiving water concentrations of suspended sediment 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 transport 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 programs. STFATE can be used in evaluating water column

effects of open-water disposal of dredged material in

accordance with section 103 of the Marine Protection,

Research, and Sanctuary Act and section 404(b)(1) of

the Clean Water Act.

EFQUAL

EFQUAL [full title: Analysis of Modified Elutriate Test

Results for Prediction of Effluent Water Quality and

Dilution Requirements for Confined Disposal Facilities]

provides a computer program to analyze the results of

modified elutriate tests and predict the chemical quality

of effluent discharged from confined disposal facilities

(CDFs) during hydraulic filling operations. Such predictions 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 particle-associated contaminants. The modified elutriate

test was developed for use in predicting both the dissolved and particle-associated concentrations of contaminants in the effluent. Results of the modified elutriate

and column settling tests may be used to predict the

total concentrations of contaminants for a given set of

CDF operational conditions.

RUNQUAL

RUNQUAL [full title: Comparison of Predicted Runoff

Water Quality with Standards and Prediction of Dilution

Requirements] provides a computer program to analyze

the results of surface runoff quality tests and to predict

the chemical quality of the surface runoff discharged

from confined disposal facilities (CDFs). Such predictions 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 concentrations of contaminants for a given set of CDF operational conditions.

HELPQ

HELPQ [full title: Hydrologic Evaluation of Leachate

Production and Quality] couples the USEPA Hydrologic

Evaluation of Landfill Performance (HELP) model with

an equilibrium partitioning model for contaminant transport. The model generates estimates of leachate production, collection and leakage from upland confined

dredged material disposal facilities as well as estimates

of contaminant concentrations and mass fluxes in the

leachate.

PUP

PUP [full title: Prediction of Contaminant Uptake by

Freshwater Plants] predicts the contaminant uptake from

dredged material by freshwater plants using DTPA extract data. The model compares the predictions with

reference sites to determine the acceptability of the

uptake in upland and flooded environments.

CDFATE

CDFATE [full title: Fate of Continuous Discharges from

Dredged Material Disposal for Estimating Mixing Zones]

predicts mixing zone requirements to meet water quality

standards or predicts compliance with water quality

standards given a mixing zone. The model is applicable

for nearly all continuous discharges from dredged material disposal operations. The operations considered by

the module include discharge of effluents or runoff from

upland confined disposal from a weir, pipe, or stream;

leakage through porous dikes; overflows from hopper

dredges or barges; and discharge of dredged material

from a pipeline.

DREDGE

DREDGE [full title: Resuspension of Sediments and

Contaminants by Dredging] generates estimates of suspended solids and contaminants released to the water

column during dredging and predicts dispersion.

LTFATE

LTFATE [full title: Long-Term Fate of Dredged Material

Disposed in Open Water] predicts the erosion and dispersion of deposited dredged material and sediment by

storm waves.

MDFATE

MDFATE [full title: Fate of Dredged Material from Multiple Disposals in Open Water] predicts the development, topography, and elevations of dredged material

mounds formed by multiple dumps from barges and

hopper dredges.

RECOVERY

RECOVERY [full title: Evaluation of Contaminant Release from Bottom Sediments] predicts the diffusion of

contaminants from in situ sediments and capped sediments. It is useful to evaluate the bottom contaminant

flux from the “no action” alternative, capping alternatives, and new exposure from dredging.
93

LAT-E / LAT-R

LAT-E and LAT-R [full titles: Laboratory Analysis of

Toxicity from CDF Effluent / CDF Runoff] are programs

for analysis of water column bioassay tests which compute the toxicity (LC50) of CDF effluent or runoff discharges.

Revisions, Updates, Availability, and

Workshops

The ADDAMS applications are revised and updated as

new technical approaches become available. New applications will be developed to address additional management 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. Announcements of revisions to specific applications and

for the entire system will be published in the Environmental Effects of Dredging Programs’ (EEDP) information 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 computerized 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.html#addams). 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 USACE/

USEPA Dredged Material Assessment and Management 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 regarding the scheduling of ADDAMS workshops should be

sent to the following address:

U.S. Army Engineer Waterways Experiment Station

ATTN: CEWES-EP-D

3909 Halls Ferry Road

Vicksburg, MS 39180-6199

References

1. Schroeder, P.R. and Palermo, M.R. 1995. “The

Automated Dredging and Disposal Alternatives

Management System (ADDAMS),” Technical Note

EEDP-06-12, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

2. Department of the Army and U.S. Environmental

Protection Agency. 1992. “Evaluating Environmental Effects of Dredged Material Management Alternatives—A Technical Framework,” EPA842- B92-008, Washington, DC.
94

Overview of Ongoing Research and Development

Dennis L. Timberlake

U.S. Environmental Protection Agency

National Risk Management Research Laboratory

Cincinnati, OH

(silts and clays) which can present material handling difficulties for many treatment processes.

• Organic Content—The organic content of sediments is typically higher than that of soil, resulting

in contaminants being tightly sorbed and creating

an increased oxygen demand for oxidative treatment processes.

• Contaminant Concentration—The concentration of

contaminant in sediments requiring treatment is

typically lower than that encountered in soils requiring treatment. Contaminants present in sediment are, in general, much more bioavailable than

contaminants in upland soils, resulting in relatively

low concentrations of contaminants displaying a

measurable impact on an ecosystem. Removing

relatively low levels of contaminant is difficult and

results in increased treatment costs.

• Mix of Contaminants—Sediments serve as an

effective sink for hydrophobic contaminants, so

contaminated sediments usually contain a mix of

contaminants, both organic and inorganic. The

contaminant mix may require the use of multiple

treatment steps, thereby increasing remediation

costs.

• Salt Content—Estuary and marine sediments have

a high salt content which can negatively impact

the efficiency of some treatment processes such

as biological treatment.

• Material Handling—The high moisture content,

presence of fines, and the presence of debris can

create material handling difficulties.

All of these physical and chemical factors differentiate

sediments from soils and have a negative impact on the

efficiency of most soil treatment technologies. The technologies that perform well with sediments typically do so

at an increased cost relative to the cost of treating

upland soils.

Introduction

The mounting evidence of the ecological risk associated

with contaminated sediments makes clear the realization 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 development opportunities for the risk management of contaminated sediments. Specific lessons learned are presented

from EPA’s National Risk Management Research

Laboratory’s (NRMRL) experience in developing a research program.

Rationale Behind Sediment Management

Research

While sediments are technically a type of soil, the two

are considered distinct media by the remediation community. 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 differences exist between soils and sediments which influence treatment technology efficiency:

• Moisture Content—The moisture content of sediments is considerably higher than that of soils

necessitating the use of technologies that are

compatible with a high moisture content. Alternatively, 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 consist of a high percentage of fine-grained material
95

Types of Sediment to be Managed

Sediments requiring treatment, or some other risk management 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 second 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 techniques 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 constraints, 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 available 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 research 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 technologies 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 concentration sediments, and (3) in-situ containment.

NRMRL’s current Contaminated Sediment Research Program was initiated in FY96 and focuses on the development 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 contaminated 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 laboratoryscale and will address the fundamentals of contaminated sediment risk management. As research

progresses, however, it is anticipated that successful

projects will increase in scale, eventually up to the fieldscale level.

The Contaminated Sediments Research Program focuses on (1) the development and/or evaluation of insitu management approaches, (2) the development and/

or evaluation of technologies for treating sediment contaminants within Confined Disposal Facilities, (3) the

development and/or evaluation of affordable ex-situ technologies, 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 technical assistance to the regions.

Future Research Directions

As has been stated, traditional ex-situ treatment technologies tend not to be cost-effective in sediment risk

management. While new ex-situ technologies will continue 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 application 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 management often dictates the selection of other management 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, however, is needed to develop methods for quantifying and,

if need be, controlling contaminant releases and reclaiming 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 costeffective manner.

The goal of the research community should be to provide decision makers with a range of solutions for the
96

risk management of contaminated sediments. Risk management options should range from low-cost “partial”

solutions to high-cost “complete” solutions. There will

never be one silver bullet that works in every contaminated sediment management situation. Recognizing this,

research programs can be designed to investigate the

entire range of options needed to address the risk

management of contaminated sediments.
97

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

we must dredge, transport, and relocate sediments to

perform our navigation mission. Some of these sediments are considered contaminated. The USACE 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 disposal of dredged material. Although only a small percentage 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 sediments affects the entire navigation program. There is

also concern that contaminated areas outside the navigation channel are contributing to contamination problems within the channel.

Through the direction of the Congress, the USACE has

developed a significant technical expertise in dredging,

dredged material disposal, and management of contaminated sediments to meet the needs of its navigation

program. Regulations, policies, and technical guidance

prepared and used by the USACE are based on extensive operating experience and results from comprehensive 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.

Abstract

The U.S. Army Corps of Engineers (USACE), 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 contaminated sediments. In this paper, the authors present

a brief overview of the research programs being conducted by the USACE on contaminated dredged material 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 disposal 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 management of contaminated sediments in the USACE Civil

Works Programs. The authors conclude by emphasizing

the need to continue to conduct basic and applied

research on contaminated sediments to find solutions to

the contaminated sediment problem. The research should

include risk assessment, management techniques, and

full-scale demonstration projects to verify and refine the

basic research products.

Introduction

Navigation has long been a primary USACE mission,

and the USACE is viewed as the nation’s dredging

agency. In many industrial and urbanized waterways,
98

Background

Environmental research in the 1970s on sediments was

broad and included the basic understanding of ecological impacts associated with management of clean and

contaminated sediment. Research in the 1980s emphasized verification of improved tests and procedures for

the identification, assessment and management of contaminated sediment . Research in the 1990s focuses on

highly contaminated materials emphasizing chronic/sublethal 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 USACE 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 waterways, Great Lakes, estuaries and coastal harbors.

USACE Environmental Effects of Dredging

Programs

The USACE 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 presumptively suitable for any given project (3). Included in

the DMRP were laboratory studies to determine the

amenability of contaminated dredged material to treatment by physical or chemical processes. The conventional treatment techniques available during the I970s

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 treatment 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, filtration technologies, particle separation technologies, and

effluent control measures investigated by this program

have application to treatment trains for contaminated

sediments.

Field Verification Program (FVP)

(1981-1987)

The FVP was a cooperative effort of the Corps and the

U.S. Environmental Protection Agency (4). FVP studies

compared placement of contaminated dredged material

in wetland and upland environments to aquatic disposal.

Contaminant losses were evaluated for each alternative.

Soil amendments and tolerant plant species were added

to an upland site to address stabilization of the surface

layer and minimization of contaminant mobility.

Long-term Effects of Dredging Operations

Research Program (1980-present)

LEDO activities are managed under the umbrella of the

USACE Center for Contaminated Sediments at the Waterways Experiment Station. The principal research effort 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 designed to develop new or improved state-of-the-art technology for predicting long-term environmental impacts of

dredging operations and to improve and develop methods 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 material. The determination that a sediment is contaminated

and unsuitable for unrestricted aquatic disposal is made

by application of effects-based testing and a preponderance of evidence leading to a determination. The

effects-based approach has been developed by the

USACE and USEPA over the past two decades and is

implemented through regulatory testing manuals and a

technical framework for dredged material management

(5).

Assessment and control technologies are required for

aquatic, wetland, and upland environments. Current research emphasizes development and refinement of predictive tests for determining bioaccumulation and

consequences in aquatic organisms; techniques for predicting leachate quality from CDFs; relationships between 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 control at CDFs.

Water Resources Development Act of

1990, Section 412(c) (1991-1994)

The USACE 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 sediment were reviewed, and bench-scale evaluations for

four treatment technologies were completed (6). Solvent
99

extraction, incineration, and base-catalyzed destruction

were effective in removing or destroying dioxins in this

marine sediment.

Alternatives were developed for six treatment technologies 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 alternatives.

Dredging Operations and Environmental

Research Program (1997-Present)

The Dredging Operations and Environmental Research

Program (DOER) was established by the USACE to

address critical field needs in finding solutions to dredging related problems in the Nations’s navigation system.

The objective of DOER is to balance environmental and

operational requirements while economically maintaining a viable navigation system. Research is required to

address operations and environmental demands in six

major focus areas: contaminated sediment characterization and management; instrumentation for monitoring

and site management; near-shore and aquatic placement of dredged materials; environmental windows for

dredging operations; innovative equipment and technologies demonstration; and, environmental risk management for dredging and disposal activities. Benefits

will include application of environmental windows,

cost-effective identification and management of contaminated 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 investigations 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 frameworks for contaminated dredged material for detailed

development, in conjunction with EPA; and survey of

critical fiscal and managerial aspects of seasonal environmental dredging restrictions.

Overview of DOER Contaminated

Sediments Focus Area

Two of the most commonly considered alternatives for

contaminated sediments are placement in confined disposal facilities (CDFs) and capping, an option for containment 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 nontraditional areas such as offshore. Treatment to reclaim

CDF capacity may be promising for certain sites. Capping 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 investigation. DOER will address high-priority research needs

aimed at reducing costs associated with screening, assessing potential impacts associated with contaminants,

and increasing the reliability and acceptability of CDF

and capping options for management of contaminated

sediments.

The DOER Contaminated Sediments Focus Area is

addressing high-priority field needs in this area. DOER

will develop low-cost, rapid, and interpretable biological

screening methods for chlorinated hydrocarbons and

other contaminants. These methods will reduce the

number and cost of chemical analyses and quickly

identify contaminated sediments and marginally contaminated 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 computers.

Research will develop risk-based assessments for contaminated dredged material for both open water and

CDF placement options. The risk assessment process

for contaminated sediments includes effects and exposure assessment (e.g. contaminant pathway testing).

Results of risk-based assessments facilitate risk management which, for contaminated dredged material, may

include identification of design requirements for contaminant controls and treatment. Effects assessments

for dioxin contaminated dredged material will tie directly

into the overall environmental risk assessment framework 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 exposure assessment will address CDF groundwater leachate,

surface runoff, and volatile pathways.

CDF research will develop and validate contaminant

controls, treatment methods, and management techniques. Design of CDFs as treatment structures, groundwater and surface water protection, and overall

contaminant retention will be emphasized. Design criteria for treatment and/or control of toxic contaminants will

be developed including low-cost, effective methods for

CDF management to meet State Water Quality Certification requirements. Research on filtration treatment

structures and enhanced biodegradation of contaminants in CDFs will receive the highest priority. Techniques 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. Research on environmental aspects of capping and CDFs

will be integrated with research on physical aspects

under the DOER Nearshore and Offshore Placement
100

focus area to provide comprehensive guidance for these

management options. Laboratory studies and technical

assessment of control and containment technologies for

open water disposal other than capping will also be

conducted.

Benefits will include the ability to improve the

cost-effectiveness of identification and assessment procedures, to reuse existing disposal capacity for contaminated materials, and to design and manage disposal

facilities for enhanced capacity, treatment, and containment objectives.

Summary

There are millions of cubic yards of contaminated sediments in the waters of the United States requiring dredging 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.

The USACE 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 USACE and USEPA need to continue to

conduct intensive basic and applied research on contaminated 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 produce direct benefits in many areas, including reduced

testing costs and more cost-effective project selection

and implementation. Detailed information on USACE

dredging research can be found on the WES Dredging

Operations Technical Support (DOTS) homepage at

www.wes.army.mil/el/dots.

Acknowledgment

This paper summarizes research conducted by the

USACE under a variety of research programs. The

technical summaries were based on research investigations being conducted under the USACE Environmental

Effects of Dredging Programs at the U.S. Army Engineer

Waterways Experiment Station, Vicksburg, MS. Permission to publish this material was granted by the Chief of

Engineers.

References

1. Engler, R. M., Patin, T. R., and Theriot, R. F.

1990. “Update of the Corps’ Environmental Effects of Dredging Programs (FY89),” Miscellaneous Paper D-90-2, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

2. Engler, R.M., Francingues, N.R., and Palermo,

M.R. 1991. “Managing Contaminated Sediments:

Corps of Engineers Posturing to Meet the Challenge,” World Dredging and Marine Construction,

August 1991.

3. 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 Experiment Station, Vicksburg, MS.

4. 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.

5. USEPA and U.S. Army Corps of Engineers. (1992).

Evaluating Environmental Effects of Dredged Material Management Alternatives--A Technical

Framework, EPA 842-B-92-008, Washington, DC.

6. Tetra Tech, Inc., and Averett, D. F. (1994). “Options for Treatment and Disposal of Contaminated

Sediments from New York & New Jersey Harbor,”

Miscellaneous Paper EL-94-1, U.S. Army Engineer Waterways Experiment Station, Vicksburg,

MS.
101

Potential for Phytoremediation of Contaminated

Sediments

Steven A. Rock

Environmental Engineer

Land Remediation and Pollution Control Division

National Risk Management Research Laboratory

United States Environmental Protection Agency

Cincinnati, OH

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 PCP 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). Wetlands can be used as phytoremediation processes. Constructed wetlands planted with reeds and cattails are

used to prevent acid mine drainage from polluting

streams. Other wetlands plants such as duckweed are

also being studied to degrade TNT and its breakdown

products.

Phytoremediation seems to be best suited for cleanups

over a wide area, with contaminants in low-to-medium

concentrations. If the concentration of contaminants is

too high, phytotoxicity results, with no or poor plant

growth. The plant roots physically must contact or be in

very close proximity to the target contaminant, so the

media to be cleaned must be within range of the root

growth. Planted areas can be used in conjunction with

other technologies, for example, following a removal

action of high contaminant concentration once these hot

spots are removed.

Phytoremediation Mechanisms

Because the term phytoremediation covers a range of

plants remediating a range of contaminants, there are

different mechanisms used for different types of phytoremediation. Some plants in some instances may use

more than one mechanism either sequentially or simultaneously. The mechanisms that various plants use in

phytoremediation can be classified into four broad categories.

Abstract

Phytoremediation is an innovative technology that is

being applied to soil and groundwater cleanup. Techniques for using plants for remediation are gaining regulatory and commercial acceptance in the U.S. This

paper considers the potential for application of phytoremediation to the remediation of contaminated sediments,

projecting from what is known about plant -contaminant

mechanisms.

The use of plants to remediate soil and groundwater

problems has been studied for many years and is being

applied nationally. Some of the mechanisms that have

been identified may be applicable for use in sediments.

Planting a contaminated sediment with shallow water

wetland plants or deeper water emergent plants can

form a vegetative root mass that acts as a cap to prevent

movement of the sediment or contaminant while bioremediation is occurring. A dense root mass not only holds

existing sediments in place, it collects and gathers sediments 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 environments along streams, river banks, and in lakes may

release enough oxygen and exudates into the subsurface sediments to promote contaminant degradation.

Background

The term phytoremediation applies to the use of a wide

variety of plants to remediate an equally wide variety of

contaminants. Prairie grasses have been studied to

reduce concentrations of polyaromatic hydrocarbons

(Aprill). Poplar trees have been shown to reduce excess

fertilizer, pesticides and herbicides from agricultural run-
102

• Enhanced Rhizosphere Biodegradation

• Phytodegradation

• Physical Effects

• Accumulation of metals

Enhanced rhizosphere biodegradation is a series of

effects that plants have on the microbial population in

the rhizosphere (the immediate area surrounding the

root). There is some symbiosis which occurs between a

plant and its microbial neighbors. Microbial populations

have been reported to be two orders of magnitude

higher in the soil of the root zone than in adjacent

unplanted 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 penetrate and loosen the sediment there is passive aeration, 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 environmental conditions, parts of plant roots die off during

seasonal water and temperature fluctuations (Anderson). 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 contamination as part of their metabolism, as in the degradation

of PCBs (Lee).

Phytodegradation is the process of the plant itself degrading the contamination. This may occur as metabolism 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, dehalogenase, peroxidase, and others

have been found to be exuded by some plants (Bollag,

Schnoor). These enzymes can either detoxify a contaminant, or render it vulnerable to microbial consumption. 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 (Carriera).

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 ignored. Hazardous wastes and municipal landfills can be

covered and capped with soil and plants, a process also

known as forming a vegetative cap. A vegetative cap

consisting of grasses, clovers, shrubs and trees is being

used to prevent both wind and water erosion on a

Montana mining site. Caps consisting of trees and grass

have been used to cap municipal landfills (Licht). In

Texas a lagoon of hazardous waste has been naturally

vegetated, and now measures a three-foot soil layer

(Fletcher).

Some plants do accumulate heavy metals in their roots

(Dushenkov) and stems and leaves (Chaney, Raskin).

These plants and these contaminants are not appropriate candidates for a vegetative cap. Plant do not tend to

accumulate organics within the plant structure as do

some metals (Banks). Therefore if contaminated sediments can be contained, the environment can be protected, 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 pathways; through suspension in the water table and consumption 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 expensive 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 vegetative matter, and collect sediments the protective cap will

continue to become thicker and more resistant to disturbance.

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 microbial activity limit the kinetically more-rapid aerobic degradation processes. The mass transport limitations reduce

bioavailability and increase the persistence of aerobically degradable organic contaminants in sediments.
103

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 sediments 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 subjected to the phytotoxicity testing, consisting of measuring 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 austalis has 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 environmental engineering with planted systems less predictable.

Bulrushes or cyperus could be used to represent plants

which grow in shallow water. These fast growing, fast

spreading plants thrive in up to two feet of water. They

are hardy and likely to survive fairly high concentrations

of pollutants and have a habitat range from Maine to

Florida, and from East to West Coast.

Another species that may be used is Vallisnera

americana, also known as eelgrass, tapegrass, or wild

celery. This plant grows in water to twelve feet deep. Its

range is also widespread; from Maine to Florida, and

from North Dakota to Texas. The vegetation of the plant

is flexible enough not to cause a navigation hazard,

although boat traffic can damage the plants. If Vallisneria

can be shown to help remediate sediments in situ at

normal growth depths, a large number of sites could

benefit.

Plant screening and selection will be an important component 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 conditions 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 appropriate 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 suppliers 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 component in determining appropriate plant selection. Enzyme

analysis of a candidate species could be performed

either at the USEPA Lab in Athens, GA, with Dr. Steve

McCutcheon, or with Dr. Laura Carriera at the

PhytoWorks Laboratory.

Measuring Phytoremediation Effects in

Sediments

Various test are available to evaluate the progress of

phytoremediation in a sediment environment. Changes

in contamination levels may not be apparent for several

years, but other changes can be gauged by monitoring

treatment progress and differences of sediment COD

and sediment TPH. Data on bioaccumulation and phytotoxicity 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-
104

est. To examine the role of metabolism within the plant,

the leaf and shoot analysis should also search for breakdown products of aerobic degradation. Enhancement of

microbial remediation in the rhizosphere can be studied

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.

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 terrestrial toxicity. Fish toxicity tests may be more appropriate 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 conditions as measured by electrical potential.

Specific Research Efforts on

Phytoremediation Effects in Sediments

Research divisions with USEPA ORD/NHEERL are involved in many lines of sediment research that are

directly related to potential phytoremediation of sediments research. NHEERL scientists have developed

several sediment toxicity test methods to assess toxicity

of contaminated sediments, some of which are proposed 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 considerations.

Several organizations including Tennessee Valley Authority (TVA) and WES have experience in wetland

construction and maintenance for treatment of contaminated groundwater. Their constructed wetland facility at

Milan, TN, has been operating since 1996 treating

groundwater contaminated with TNT and its breakdown

products.

Washington State Departments of Transportation and

Ecology are jointly engaged in searching for alternatives

to conventional dredging and capping in the waterways

in and around the Puget Sound. Bellingham Bay has

been designated an area for testing and evaluating

alternative sediments handling.

Conclusions

It is hypothesized that establishing wetland plants in a

sediment will decrease the mobility of the sediment and

hence its bioavailability compared to unplanted sediments. 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 contaminated sediments, the accelerated deposition of fresh

sediments over contaminated areas promotes the natural recovery of the area.

If it provides an equally effective alternative to conventional techniques of dredging, capping and armoring, a

vegetative cap would be more economical than conventional 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 dredging 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 disadvantages 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. Conventional technologies of sediment containment are specifically 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 conditions of ecosystem restoration, is one of the goals of

EPA research.

If successful, phytoremediation may be shown to provide an in-situ method for managing large volumes of

contaminated sediment for affordable ecosystem restoration and environmental protection. Small- and full-
105

scale research is still to be done to determine if that

potential will be realized.

References

1. Anderson, Todd A. 1996. Rhizosphere technology

for Phytoremediation International Phytoremediation 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. Chemosphere, 20:253-265.

3. Armstrong, W.; Armstrong, J.; Beckett, P.M. Measurement 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. Inventory of Constructed Wetlands in the U.S. Water Science Tech. Vol. 29 No. 4 pp 309-318

5. Brix, Hans; Schierup, Hans-Henrik. 1990. Soil

Oxygenation in Constructed Reed Beds: The Role

of Macrophyte and Soil-Atmosphere Interface Oxygen Transport Constructed Wetland in Water Pollution Control, P.F. Cooper ed. Pergamon Press,

Oxford.

6. Brix, Hans. 1993. Macrophyte-Mediated Oxygen

Transfer in Wetlands: Transport Mechanisms and

Rates. Constructed Wetlands for Water Quality

Improvement, CRC Press.

7. Bollag, Jean-Marc. 1992. Decontaminating Soil

with Enzymes. Environ. Science Technology, Vol.

26, No.10.

8. Carriera, L. H. 1997. “The Use of Antibody Assays

to Predict Plants Capable of Phytoremediation”

The Second International Phytoremediation Conference, Seattle, WA. International Business Communications, Southborough, MA.

9. Chaney, R.L. 1983. Plant uptake of inorganic

waste constituents. In: Land Treatment of Hazardous 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 & Developmental biology-PIant 29P (4): 227 -2 32 1993

11. Dushenkov, Viatcheslav; Kumar, P. B. A. Nanda;

Motto, Harry; Raskin, Ilya. 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 PCP

Contaminated Soils Using Plants. Unpublished.

13. Fletcher, J. 1997. The Role of Phytoremediation in

Intrinsic Bioremediation In Situ and On Site Bioremediation: Vol. 2, Batelle Press.

14. Lee, Euisang; Banks, M. K., Kansas State University. 1993 Bioremediation of Petroleum Contaminated Soil Using Vegetation: A Microbial Study J

Environ Sci Health-Environ Sci Eng vA28, n10,

p2187(12)

15. Lee, M., Bowen B., Washington Dept. Of Transportation Personal communication 1997

16. Michaud, Susan; Richardson, Curtis. 1993. Efficiencies of Substrates, Vegetation, Water Levels

and Microbial Populations: Relative Radial Oxygen 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 v29, n7, p318A(6) July.
106

Treatment of Metal-Bearing Solids

Using a Buffered Phosphate Stabilization System

Thomas Stolzenburg, Senior Applied Chemist

RMT, Incorporated

Madison, WI

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 insitu treatment.

Not all in-situ treatment alternatives are necessarily

economical either. For instance, volume increases associated with chemical addition that causes bulking may

represent an intractable full-scale dilemma. Also, excessive energy requirements or impractability of mixing or

chemical delivery can preclude cost-effective implementation 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 chemical 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 sediments include:

• Iron foundries

• Steel mills

• Brass foundries

• Smelters

• Battery recyclers

• Leaded paint

• Shooting ranges

• Mine tailings

• Lead arsenate pesticides

• Ash

Some of the chemical stabilization alternatives available

to treat lead include:

Introduction

Solid wastes or metal-impacted soils can be classified

as hazardous by their leaching characteristic. The test

protocol used for classification is the Toxicity Characteristic 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 Synthetic 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-situ process for

several reasons. In most cases, permitting requirements

are more extensive for ex-situ treatment. Each materials
107

• pH Control

- Lime

- Carbonates: limestone, dolomite

- Magnesium oxide

• Chemical Fixation

- Iron Hydroxides

- Phosphates

- Sulfides: dithiocarbamates

• Chemical Reduction

- Metallic iron

This paper discusses the use of a pH-buffered phosphate chemical fixation system for treating solids impacted 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 treatable by the described process). The described process

is effective at rendering lead and cadmium solids nonhazardous by the TCLP, and it is also effective at

minimizing metal solubility under rain water and/or ambient 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 phosphate. As might be predicted, if lead occurs in a solid as

lead hydroxide, that solid is often characterized as hazardous in the TCLP (note how high the solubility of lead

hydroxide is at the low pH conditions of the TCLP).

0.00001

0.001

0.1

10

1000

100000

10000000

0 2 4 6 8 10 12 14

pH

Lead Concentration, mg/L

HPO4

PO4

CO3

OH

SO4

5 mg/L

0.37 mg/L

Figure 1. Solubility of lead species as a function of pH.
108

The solubility of cadmium in water is also highly dependent 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. Despite 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.

0.0001

0.001

0.01

1.0

10

100

1000

4 5 6 7 8 9 10

pH

Cd (PO ) 3

4 2

CdCO (octavite) 3

CdSiO (c) 3

Cd(OH) 2

CdO (monteponite)

Soluble Cd (mg/L) +2

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

0.065

0.65

6.5

65

650

6 7 8 9 10 11 12

pH

Zn Concentration (mg/L)

Figure 3. Zinc-contaminated site soils—zinc solubility curve. Soluble Cd2+(mg/L)
109

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

TCLP, and rendering the waste nonhazardous. However, 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.

70

60

50

40

30

20

10

 5 7 11 9 13

 0

pH

TCLP Lead Concentration (mg/L)

Figure 4. Foundry waste.

Table 1. Leachability of Smelter Waste*

TCLP SPLP

Test Test

Lead Lead

(mg/L) Final pHf (mg/L) Final pHf

Untreated 600 6.0 <0.003 8.2

Lime (% by weight)

+5 76 6.5 290 12.2

+10 0.2 8.6 540 12.5

+15 6.2 10.4 510 12.5

Portland Cement

(% by weight)

+5 450 5.3 19 11.5

+15 <0.2 10.4 11 11.9

+25 1.2 11.6 12 11.9

+50 10.0 12.0 3.0 12.1

P + pH

(% by weight)

+4 2.4 5.8 <0.003 10.6

+6 0.4 5.5 <0.003 10.3

+8 <0.2 5.6 <0.003 8.5
110

Figure 5 illustrates the data shown in Table 1. In a 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 treatment is successful in rendering this waste nonhazardous 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 leaching. 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 treatment 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. Economical 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 phosphate 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

Figure 5. Lead solubility vs. pH.

4

Lead Concentration (mg/L)

 5000.0

 500.0

 50.0

5.0

 0.50

 0.050

0.0050

B

C

TCLP Toxicity Limit

TCLP Test Water Test

After

Before

1 2 3 5 6 7 8 9 10 11 12

pH

A

Before

D

After

5.0
111

with the treatment chemical. The sediment that settled

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 classifiable as hazardous for lead leaching. Because of regulations, 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 construction, 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 sediment 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 nonhazardous waste at a fraction of the cost of hazardous waste

treatment. A more complete description of this case can

be found in (2).

Summary

A pH-buffered phosphate chemical fixation process (patented), which has been used successfully at hundreds

of uplands sites, has also been implemented at full-scale

in sediment settings. With minimal engineering controls

it is an economic, environmentally friendly, and robust

process that can be applied in situ for lead-, cadmium-,

and zinc-contaminated sediments.

References

1. Tickanen, L.D., and P.D. 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, MI.

2. Wible, L., S. McAnulty, R. Stanforth, A. Chowdhury,

and M. Warner. 1994. “In-Situ Treatment of Hazardous Sediment.” Proceedings of Second International Conference and Exhibition on Dredging

and Dredged Material Placement. American Society of Civil Engineers, Waterway, Port, Coastal,

and Ocean Division. November 13-16, 1994.
112

Treatment of Dredged Harbor Sediments by Thermal

Desorption

Mary Hall, Ed Alperin and Stuart Shealy, IT Corporation

Keith Jones, Brookhaven National Laboratory

desorption, followed by cement based solidification/stabilization (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 suitable for ocean disposal. These blocks would provide

hard surfaces for reef development. Artificial reefs have

proven to provide habitat for numerous fish and invertebrate 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 leachability 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 Disposal. To accomplish the second goal, the final product

will be formed into blocks suitable for encouraging growth

of marine organisms. The goals of the final product

were:

• an unconfined compressive strength (UCS) of 290

pounds per square inch (psi) or greater,

• metal leaching results below the Toxicity Characteristic (TC) regulatory threshold, and

• minimization of Lethal Concentrations or LC50 results.

The New York/New Jersey Harbor must be regularly

dredged to maintain shipping channels and berthing

areas for commerce and safe navigation. Ocean disposal 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 Protection Agency, Region 2 (EPA-Region 2) established morestringent 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 contaminated dredged material prohibited from ocean disposal 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 different procedures before disposal is possible due to the

complex nature of the contaminants and their widespread spatial distribution within the harbor.

Dredged sediments from various areas of the harbor

may contain elevated levels of a wide variety of contaminants, including heavy metals, polynuclear aromatic hydrocarbons (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 methods to render dredged sediments suitable for unrestricted ocean disposal, land disposal or, preferably,

beneficial use. IT Corporation (IT) investigated a threestage treatment process that included dewatering the

sediment, removing organic contaminants by thermal
113

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

• UCS of 20 psi, and

• metal leaching results below TC regulatory threshold.

Data generated by this study will be used by BNL to

determine:

• treatment effectiveness as determined by a critical

evaluation of the data from chemical and physical

analyses and bioassay testing as well as their

relative contribution to the assessment of the technology,

• composition of end product(s), effluent, and

by-products,

• unit treatment cost estimates and time-scales for

scaleup operations, and

• potential environmental and occupational hazards

posed by the treatment technology or system.

Testing for this treatability study was conducted in three

stages as Figure 1 visualizes. Stage 1 was to dewater

the received material. Stage 2 was to thermally desorb

the remaining moisture and organics from the DES.

Stage 3 was to solidify/stabilize (S/S) the thermally

desorbed DES to prevent the leaching of the inorganic

contaminants.

Sample Description

Four 5-gallon buckets of sample were obtained by

NYDCOE using barge mounted clamshell dredging equipment. 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 leachable

cadmium, copper, lead, nickel and zinc. Due to the small

amount of material used in some of the tests, the DES

was screened prior to use and material 1/2" or larger

was removed.

Dewatering

The water content of the DES was ≥60% (by weight).

This is too high for optimal thermal desorption operation.

High water content lowers the treatment capacity and

increases the energy requirements for a thermal desorber

system. High water content may also result in material

handling problems in typical feed equipment. This results 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 (mls) of liquid was collected in 61 seconds. This material was determined to

be non-drainable.

High pressure, 120 psi, filtration was tested and only 30

mls of liquid was collected in 15 minutes. A filter aid of

hyflo diatomaceous earth was added at a 5% concentration which caused the binding of the filter press with the

collection of only 44 mls 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.

Thermal Desorption

The purpose of the thermal treatment was to identify

treatment conditions (time/temperature) needed to remove pesticides and PCBs from the DES and generate

enough thermally treatment material for S/S testing. All

thermal tests were performed in IT’s Rotary Thermal

Apparatus (RTA), see Figure 2. The RTA is a batch,

bench-scale device that is used to treat material in an

indirectly heated rotary tube. The device simulates the

▲

DES Stage 1 ▲

▲

Dewatering

Stage 2

Thermal

Desorption

Stage 3

Stabilization/

Solidification

▲

Ocean Disposal or Land-Based Product

Figure 1. Three-stage treatment process for DES.
114

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 electric furnace that encloses the tube. As the DES heats to

treatment temperature, steam (from desorption of the

sediment moisture) and desorbed organics evolved and

are carried by the purge air into an offgas treatment

system.

The offgas system used for these tests was a spray

scrubber followed by a carbon absorber. The spray

scrubber removes acid gases, semivolatile organic compounds (SVOCs) and some oxygenated organics. The

carbon absorber removes volatile organic compounds

(VOCs).

Four runs were performed on a homogenous sample to

identify optimal temperature and retention time at temperature to minimize the organic content prior to production 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 analyzed for PAHs, PCBs and OCPs 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 content, 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 thermally treated material.

Table 1. Total Pesticides (μg/kg dry) Untreated and Thermally

Treated Dredged Estuary Sediment

Treatment Temperature (°C)

/Residence Time (min)

Analyte Untreated 350/5 450/0 450/5 550/5

Alderin 75 <3.4 <3.4 <3.4 <3.4

4,4'-DDD 162.1 <3.4 <3.4 <3.4 <3.4

4,4'-DDE 150.6 <3.4 <3.4 <3.4 <3.4

Dieldrin 74.5 <3.4 <3.4 <3.4 <3.4

Total Aroclors (PCBs) (μg/kg dry) Untreated and

Thermally Treated Dredged Estuary Sediment

Treatment Temperature (°C)

/Residence Time (min)

Analyte Untreated 350/5 450/0 450/5 550/5

Aroclor 1016 <930 <66 <66 <66 <66

Aroclor 1221 <930 <66 <66 <66 <66

Aroclor 1232 <930 <66 <66 <66 <66

Aroclor 1242 1400 <66 <66 <66 <66

Aroclor 1248 <930 <66 <66 <66 <66

Aroclor 1254 1500 <66 <66 <66 <66

Aroclor 1260 <930 <66 <66 <66 <66

Total Polyaromatic Hydrocarbons (μg/kg dry)

Thermally Treated Dredged Estuary Sediment

Treatment Temperature (°C)

/Residence Time (min)

Analyte Untreated 350/5 450/0 450/5 550/5

Naphthalene

2729 <660 86 <660 67

Acenapthylene

1288 <660 <650 <660 <650

Acenaphthene

1042 <660 <650 <660 <650

Fluorene

1389 <660 <650 <660 <650

Phenanthrene

6588 <660 <650 <660 <650

Anthracene

3702 <660 <650 <660 <650

Fluoranthene

10324 <660 <650 <660 <650

Pyrene

7102 <660 <650 <660 <650

Benzo(a)anthracene

4484 <660 <650 <660 <650

Chrysene

4585 <660 <650 <660 <650

Benzo(b)fluoranthene

2922 <660 <650 <660 <650

Benzo(k)fluoranthene

1107 <660 <650 <660 <650

Benzo(a)pyrene

2550 <660 <650 <660 <650

Indeno(1,2,3-cd)pyrene

1076 <660 <650 <660 <650

Dibenz(a,h)anthrancene

397 <660 <650 <660 <650

Benzo(ghi)perylene

1255 <660 <650 <660 <650
115

To generate residuals for a mass balance determination, 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 estimated. 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 μg/kg to 1.8 μg/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 μg/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 μg/kg dioxin TTE.

These results show that thermal desorption is effective

in removing or reducing toxic organics (OCPs, PAHs,

PCBs and dioxins) from the DES. It also reduces the

biotoxicity of the thermally treated material.

Solidification/Stabilization

Optimal additive ratios and requirements for the conversion of thermally treated DES into a nonleachable durable 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 (UCS) (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

Figure 2. Rotary thermal apparatus (RTA) schematic.

PI

1

PI

PURGE GAS

1-7 L/min.

ELECTRIC FURNACE

7500 WATT

WASTE

SAMPLE

HEATER

TUBE

GRAPHITE

SEAL

GRAPHITE

FERRULE

HEATER

CLAMP

PURGE GAS

0.3-1 L/min.

TO O CELL 2

RUBBER

SEPTUM

QUARTZ

TUBE CHAIN

DRIVE

PI - Pressure Indicator

TR

2

TR

TR1 - RTA Tube Gas Thermocouple

TR2 - Soil Thermocouple

HEATER

TUBE

GRAPHITE

SEAL

OFF-GAS
116

material handling in the field. This reformulation is designated 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. Formulations would be carried forward based on data from

unconfined compressive strength (UCS) (American Society 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 UCS greater than 290

psi and passed TCLP analyses for constituent metals.

The only method used to compare the land based

formulations was to perform a biotoxicity analysis, so

Formulations 9 and 10 were included in the analysis.

Formulation 9 was designed to use PC for strength and

BFS to react with the calcium hydroxide by product

made by cement hydration reactions. Formulation 10

was based on treating soils and oily materials. This

formulation was given a 1:2 (w/w) lime to FA to lower the

alkalinity for better results in the biotoxicity analysis and

cost.

Table 2. Mass Balance Date for Thermal Treatment of Dredged Estuarine Sediments

Stream Mass Carbon5 Ash5 PCBs5 Dioxin,TTE3,5

Description (g) (wt%) (g) (%) (g) (μg/kg) (mg) (ng/kg) (μg)

In

Feed 24,989 4.7 1,177.0 47.7 11,919.8 2,996.7 74.9 299 7.47

DES

Scrubber 2,082

Water

Total In 27,071 1,177.0 11,919.8 74.9 7.47

Out

Treated 13,744 5.5 714.7 91.5 12,579.9 1.8 0.0 154 2.12

DES

Condensate 12,536 0.5 62.7 na4 63 0.79

Aqueous

Condensate 170 85.0 144.5 452,370.0 76.9 28,147 4.78

Oil

Offgas Solids 147 5.2 7.6 85.0 125.0 0.00

Offgas 211.9

Carbon Traps 498 na4 1,845 0.92

Glassware 640 8,692.6 5.6 888 0.57

Rinse

Total Out 26,5971 1,141.42 12,704.8 82.5 9.18

Recovery % 98.2 97.0 106.6 110.2 122.9

1 Overall mass balance was completed around the desorber and impingers and does not include the carbon traps and solvent rinse of the

glassware.

2 Carbon (organic) content of aqueous condensate and offgas are estimated from earlier work on other soils.

3 Dioxin is reported as nanogram/kg of 2,3,7,8-tetrachlorodioxin Total Toxicity Equivalents.

4 Not Analyzed.

5 Wt% carbon, ash, PCB, dioxins have been corrected for 57% moisture content of partially dried DES used in the RTA tests.

Table 3. Formulation Matrix for Preliminary Evaluation

Blast

Portland Furnace Silica Fly

Run Cement Slag Fume Ash Sediment

Number (g) (g) (g) (g) (g)

1 20 4 0 4 100

2 20 4 3 30 100

3 20 50 3 4 100

4 20 50 0 30 100

5 50 50 0 4 100

6 50 50 3 30 100

7 50 4 3 4 100

8 50 4 0 30 100

3R 20 14 40 0 100

9 5 0 5 0 100

10 5 (Lime) 10 0 0 100
117

All untreated samples passed the TC regulations for

metals. The thermally treated sediments contained low

levels of leachable (TCLP) cadmium, copper, lead, nickel

and zinc. Stabilization was performed to determine if the

metals could be fixed into the matrix. All stabilization

formulas resulted in effective the fixation of metals. All

metals but zinc were nondetected in the TCLP. Leachable (TCLP) zinc was reduced from 26.1 mg/L to 0.115 -

0.076 mg/L. The UCS of monolith formulas ranged from

240 to 550 psi.

All TCLP analyses were nondetected for the tested

parameters. The test materials were metals, pesticides,

herbicides, VOC, SVOC, dioxins, and furans. This shows

that very little of the constituents are leaching. This

agrees with the very low LC50 and EC50 values for the

chosen formulation.

All PCB, pesticides, and herbicides were non-detect in

the total analysis. Comparing the thermally treated/stabilized material with the untreated material, percent

reductions were calculated using the method detection

limits for nondetected analytes. The PCB and pesticides

were reduced by >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 μg/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 organisms, 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 stabilization 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 formulations.

Formulation 3R has identical toxicity as the thermally

treated DES. The LC50 values for Formulation 3Rare all

greater than 100% leachate, the leachable metals are

Table 4. S/S TCLP Results

Formulation Arsenic Barium Cadmium Chromium Copper Lead Nickel Selenium Silver Zinc UCS

Number (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (psis)

1 <0.178 0.308 <0.026 <0.028 <0.011 <0.201 <0.03 <0.147 <0.017 0.076 310

2 <0.178 0.371 <0.026 <0.028 <0.011 <0.201 <0.03 <0.147 <0.017 0.100 240

3 <0.178 0.429 <0.026 <0.028 <0.011 <0.201 <0.03 <0.147 <0.017 0.087 360

4 <0.178 0.451 <0.026 <0.028 <0.011 <0.201 <0.03 <0.147 <0.017 0.076 420

5 <0.178 0.477 <0.026 <0.028 <0.011 <0.201 <0.03 <0.147 <0.017 0.096 420

6 <0.178 0.491 <0.026 <0.028 <0.011 <0.201 <0.03 <0.147 <0.017 0.104 550

7 <0.178 0.513 <0.026 <0.028 <0.011 <0.201 <0.03 <0.147 <0.017 0.098 460

8 <0.178 0.604 <0.026 <0.028 <0.011 <0.201 <0.03 <0.147 <0.017 0.120 330

9 <0.178 0.412 <0.026 <0.028 <0.011 <0.201 <0.03 <0.147 <0.017 0.115 380

10 <0.178 0.361 <0.026 <0.028 <0.011 <0.201 <0.03 <0.147 <0.017 0.100 40

Air

Dried <0.178 0.277 0.325 <0.028 0.286 0.242 2.43 <0.147 <0.017 18.2 34

DES

Thermally

Treated <0.178 0.305 0.665 <0.028 1.58 0.159 1.75 <0.147 <0.017 26.1 NA2

DES1

1 550°C for 5 minutes. 2 Not analyzed.
118

Table 5. Detected Treated Material SVOCs Comparisons With

Feed

μg/kg in the μg/kg in the

SVOC Analyte Product Feed

Naphthalene 47.9 2729

2-Methylnaphthalene 25.0 2304

Diethylphthalate 33.4 –*

Di-n-butylphthalate 60.4 –*

bis-2-Ethylhexylphthalate 243.3 48631

* Common laboratory contaminant often arising from the gloves,

rubber O-rings, and plastic containers in contact with the sample or

a leachate of the sample.

Table 6. Biotoxicity Testing Results

Formulation

Air Dried Thermally

Biological Species Procedure DES Dried DES1 3R 4 5 9 10 Blank2

Menidia berylina LC50 (% Sample) 58.79 >100.0 >100.0 >100.0 >100.0 65.7 66.39 >100.0

(Silverside Minnows) Mortality in 100% 95 0 15 25 10 100 82.5 17.5

sample (%)

Mysidopsis bahia LC50 (% Sample) 82.78 >100.0 >100.0 >100.0 >100.0 31.57 22.36 >100.0

(Mysid Shrimp) Mortality in 100% 65 2.5 27.5 42.5 17.5 70 100 0

 sample (%)

Mytilus edulis LC50 (% Sample) 75.02 >100.0 >100.0 >100.0 >100.0 >100.0 87.06 >100.0

(Mussel Larvae) Mortality in 100% 77.0 15.8 44.0 35.0 30.0 41.5 52.5 42.0

sample (%)

EC50 (% 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 (%)

1 Thermally treated at 550°C for 5 minutes. 2 Instant Ocean® extraction fluid.

low and the USC is greater than 290 psi. These three

factors indicate that Formulation 3R has significant potential 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.

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

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.

Cost Estimate

The process costs are base on a 12 mo-24 hr operation. The capital cost for the treatment system is

estimated at $23,650,000 or $23.65 per yd3 of sediment. 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/yd3.
119

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

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 Material Management Plan for the Port of New York and New

Jersey.” The options for solving the contaminated sediments problem are containment islands, direct upland

disposal in landfills, and treatment by several technologies.(3) The overall treatment cost of using these technologies (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 sediments is solvent extraction, which has been extensively

used in the manufacturing industries as well as for the

decontamination of soils/sludges. Moreover, it is effective in extracting contaminants for high-resolution gas

chromatograph analysis, such as polychlorinated biphenyls (PCBs) and dioxin/furans. Solvent extraction removes only organics and can be part of the overall

treatment plant to produce useable products that potentially have some resale value. Heavy metal contaminants, 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

Abstract

Solvent extraction of organic contaminants is one of the

relatively low-cost methods currently under development 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 materials. Furthermore, the technology has been applied successfully on contaminated soils and sludges with low

moisture content. However, the application of this technology to contaminated sediments presents unique challenges. 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 describes the technical issues associated with solvent

extraction and recent bench- and pilot-scale test results.

These tests indicate that this technology is safe and

cost-effective for further development and engineering

design as part of a full-scale commercial plant.

I. Introduction

Sediments slowly accumulate in our ports, harbors,

rivers, and lakes and eventually restrict shipping access

and navigational safety. Accordingly, both the U.S. Environmental Protection Agency (EPA) and U.S. Army Corps

of Engineers (USACE) manage and regulate the dredging of approximately 400 million cubic yards of sediments each year in the United States. It is estimated that

approximately 14 to 28 million cubic yards/year of sediments from the federal waterways and from the industrial sites are contaminated with low levels of

toxic-regulated organics and/or heavy metals. To date,
120

also presents some of the results of the recent benchand pilot-scale tests conducted on the NY/NJ Harbor

sediments for which the ORG-X proprietary process was

applied in combination with stabilization/solidification.

The effects of some of the important process variables

are reported. The performance results and conceptual

treatment costs are favorable for continuing to the next

phases:

1) additional investigation of other process variables to

improve and optimize contaminants removal; and

2) preliminary engineering of a commercial plant with a

capacity of 100,000 to 500,000 cubic yards/year.

II. Technical Considerations for

Applying Solvent Extraction

A. General

There are three fundamental technical considerations

for applying solvent extraction to treat contaminated

sediment. These are

• the chemical and physical characteristics of the

sediment to be treated;

• the clean-up goal(s) for the selected final product(s)

or treatment objectives for the solvent extraction

process; and

• the process to achieve the goal(s).

The latter involves the development and application of

the particular solvent extraction process to convert the

contaminated raw sediments to the desired final

product(s). 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. Générale de Réhabilitation des Sites (GRS)

is a French affiliate of the larger CGE/Anjou Recherche

organization.

B. Sediment Characterization

Although sediment comes from numerous locations and

differ in physical and chemical content, there are some

general common characteristics. It is usually a black,

sticky and mayonnaise-like muck. It has a high water

content in the range of 60 to 70% in situ because of the

high total surface area from the high percentage of

hydrophilic fines (clays and silt). Carbon content is high

(2 to 10% TOC 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, insoluble 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 traditional 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 sediment 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 semivolatiles 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 program is to minimize cost over a given time horizon while

satisfying various constraints/criteria/desires/specifications. Cost minimization also applies to treating the

contaminated sediments with the solvent extraction process. Although a clean-up criteria has not been established for low but undesired levels of toxic compounds,

reasonably safe goals can be proposed for useful products. 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 products 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 stabilized, 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
121

• to treat a variety of organic contaminants at various concentrations;

• to pretreat sediments to reasonable but flexible

specifications;

• to design the commercial plant with flexible level

of organics removal in order to attain the safe

levels of the reusable product;

• to produce various desirable products to maximize reuse; and

• to integrate the solvent extraction plant with a

solidification plant and its requirements (i.e., produce organic contaminant-free sediment with moisture content required by solidification plant).

D. Brief Review of Solvent Extraction

Technology, Applications and Approach

1. Organic Contaminant Extraction

Approach

Applying solvent extraction for treating sediments is

more complex than the two standard types found in

textbooks: liquid-solid extraction or liquid-liquid extraction. The sediments are already two phases (liquid and

solid) in the form of an aqueous slurry, and the introduction of a partially miscible solvent creates a second

liquid phase. Moreover, there is a multitude of contaminants 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 conventional 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 processing equipment is required;

• aggressive mechanical dewatering is ineffective

and forms a gel-like material with little or no release of water.

Table 1. Newtown Creek (NY Harbor) Sediment Characteristics

Physical Characteristics - Almost in the In Situ State

Solids (%) 30 - 40%

Gravel (% of solids) 0.1 - 34%, frequently on low side

Sand (% of solids) 35 - 47%, frequently near average

Silt (% of solids) 8 - 43%, frequently near average

Clay (% of solids) 10 - 65%, frequently near average

Chemical Characteristics

Organics Level TCLP

PAHs 1 - 50 ppm <0.01 mg/l

Pesticides ND - 177 ppb <0.01 - 0.0005 mg/l

Dioxins/Furans (total) 0.01 - 15 ppb <0.001 - 0.01 ng/l

PCBs (total) 1 - 10 ppm 0.0001 - 0.02 &g/l

Total Organic Carbon 2 - 8% ---

Metals Level TCLP

Arsenic 5 - 33 ppm <0.1 mg/l

Cadmium 1 - 20 ppm <0.1 mg/l

Chromium 100 - 400 ppm 0.03 mg/l

Copper 61 - 770 ppm

Lead 68 - 554 ppm <0.05 mg/l

Mercury 1 - 3 ppm <0.001 mg/l

Nickel 12 - 140 ppm

Silver 2 - 3 ppm

Zinc 104 - 1260 ppm
122

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 compounds from oil, antibiotics from fermenter broth, vitamins 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 contaminants 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 (CHCl2, CHCl3, 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 hazardous and regulated.

Figure 1. Solvent extraction approaches for contaminant removal from sediments.

Water

Drying

high energy - cost

Liquid

solvent(s)

(Liquid - solid)

liquid extraction

Screened raw sediment

(<1/4")

(aqueous slurry)

Liquid

solvent(s)

Liquid - solid

extraction

This is the focus of

M&E’s process

development
123

Figure 2. Single contact stage of contaminated sediments and solvent at equilibrium.

Figure 3. Contaminant transfer mechanisms on mixing.
124

The ART International technology initially uses a hydrophilic solvent to extract the organic contaminants from

sediments or soil. The solvents used are acetone, methanol, or isopropanol. Then a hydrophobic solvent is used

to extract the contaminants from the hydrophilic solvent.

This requires separation of the two solvents and additional equipment for handling and recovery of individual

solvents.

The RCC/Ionics technology uses triethylamine which is

hydrophilic (high solubility in water) at less than 20°C

and hydrophobic at greater than 20°C with wet sediments or soil slurries. Therefore, the mixtures must be

cooled and heated in cycles for each stage. It should be

noted that triethylamine is now a listed hazardous waste

and additional regulatory and health risks need to be

addressed.

The CF/MK technology uses very low boiling solvents

(carbon dioxide, hexane, or ethers) at supercritical conditions 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 extract 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 handling properties, thermal stability, safety and environmental considerations, and cost.(4)

Selectivity—Solvent choice is influenced by the interactions of the structure of the chemicals. The main contaminants of concern are the non-polar to slightly polar

polyaromatic hydrocarbons, and multi-chlorinated hydrocarbons such as PCBs, dioxins, furans and pesticides. The acetate offers both a slightly polar and

non-polar group and provides affinity for the contaminants. Unfortunately, the solubility of the acetates increases 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 increasing the solubility of other contaminants selective to

the alcohol. This blend also exhibits higher than expected 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 decanting.

The acetate/alcohol blend has several important properties that reduce processing cost. First, some combinations 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

Table 2. Solvent Extraction Processes for Soils/Sediments Treatment

Solvents

Extraction Temperature (T) Solubility in Water

Process/Vendor Solvents and Pressure (P) (Sediment Slurry)

ART International Proprietary: Ambient @ 1 Atmosphere 1st: very high

1st: hydrophilic (acetone, 2nd: very low

methanol, isopropanol);

2nd: hydrophobic

RCC/Ionics Triethylamine Ambient to 100°+C @ 1 High at low Temp.

(now ECRA-hazardous) Atmosphere Low at high Temp.

CFS/M-K CO2, propane, ethers Ambient temperatures @ High at critical T and P

Critical Pressure (Pc)

Terra-Kleen Proprietary

Mixture of up to 14 solvents Ambient @ 1 Atmosphere Not known

M&E Acetates, alcohols, and other Ambient to 100°+C @ Moderate

special blends 1 Atmosphere
125

and is non-sticking to inexpensive materials of construction such as carbon steel, plastics, and glass.

Thermal Stability and Non-Reactivity—The solvent blends

of acetate/alcohol are thermally stable and non-reactive

at the processing temperatures (maximum temperature

expected at distillation reboiler is <200°C) and neutral

conditions. The concern that the acetates hydrolyze to

the primary alcohol and acetic acid is minimal as the pH

of the sediment is near neutral.

Safety and Environmental Considerations—The selected

acetate/alcohol blend is nontoxic to workers and the

OSHA exposure threshold levels are relatively high.

Some of these compounds are used in household products and are considered safe. Unfortunately, in the purer

nonaqueous state, these solvents are flammable and

present an explosion hazard. This is overcome by inerting

and specifying explosion-proof equipment systems. Dust

releases are also limited by keeping the sediments wet

with water during operation.

The acetate/alcohol solvent blend does not pose environmental problems. The solvents are biodegradable if

trace quantities are left in the sediment. The compounds

selected are not listed in the Phase III land disposal

restrictions and are not ECRA-hazardous. Atmospheric

emissions are controlled by enclosure of unit operations.

The wastewater effluent is steam stripped to low solvent

levels for acceptance by the POTW or in-plant treatment.

Costs—Cost is an important consideration when selecting solvents for two reasons. One, the solvents should

be commercially available and relatively inexpensive.

Although the solvent is recovered, some makeup is

needed to replenish the amount lost from fugitive emissions and the amount left in the waste oil to maintain

fluidity. Two, the solvents are recovered efficiently from

downstream operations. The energy cost is minimized

by not removing all of the water from the sediments. The

high volatility and minimum azeotrope with water also

helps to keep energy costs low during the distillation and

steam stripping steps. This is important because experience has often shown that only 15% of the investment

and 5% of the operating cost is associated with the

extraction step. The balance of 85% of the investment

and 95% of the operating cost are associated with the

solvent recovery steps.(5)

III. Bench-Scale and Pilot-Scale Tests

A. Test Program and Objectives

Metcalf & Eddy, Inc. completed both bench-scale and

pilot-scale tests to evaluate its Integrated Sediment

Decontamination System (ISDS) using sediments

dredged from Newtown Creek in the New York Harbor.

The studies were funded under the Water Resources

Development Set and jointly administered by U.S. Environmental Protection Agency and U.S. Army Corps of

Engineers. The ISDS system, shown in Figure 5, consists of three sequential technologies:

Figure 4. Solubility of acetate/alcohol azeotrope mixture in sediment.

20 24 28 32 36 40 44

Sediment, % solids

80

70

60

50

40

30

20

10

0

Acetate/alcohol azeotrope blend

% soluble in sediment

Solvent solubility

too high

Viscosity too high

slurry not flowable

Solubility/ penetration

of acetate/alcohol

blend in water

Practical

operating

range
126

Figure 5. M&E Integrated Sediment Decontamination System.

Step I HYDRO-SEPSM: A soil washing process to produce 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

is greater than 30%.

Step II ORG-XSM: A solvent extraction process to remove organics contaminants and produce organic contaminant-free sediments and a waste

oil for off-site disposal (incineration). The solvent is recovered by partially drying the sediment, distilling the waste oil and steam stripping the wastewater.

Step III 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-products.

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 quantity (10 cy) of actual sediment feedstock, and

produce products with desirable physical properties; 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 removal at reasonable cost. The main operating

variables were 1:1 solvent to sediment ratio for

each extraction that was well-agitated for 15 minStep I: Hydro-Sep Step II: Org-X Step III: Solfix

Concept: Hydrosep separates the coarse particles

of the sediment (sand and gravel) from

the fine fractions (silts, clays, and

humates) using screens and hydraulic

systems. The screening and water

washing is enough to clean the coarse

particles. Only the “fines” need further

treatment.

Concept: A solvent is used to extract the organic

contaminants (oils, PCBs, dioxins,

pesticides...) strongly attached to the

fines. After extraction, the clean sediment

is dried. The recovered solvent is

decanted, distilled and recycled while the

organic contaminants are concentrated

as oils. The oils are shipped offsite for

disposal.

Concept: To stabilize heavy metals (lead,

cadmium, arsenic...) the sediment is

reacted with cement, pozzolanic materials

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 concretelike solid. The inert end-product can be

crushed for beneficial uses as construction aggregate, road base or landfill

cover.

Gravity separator

(hydrosizer)

Raw

contaminated

sediment

Coarse

screen

Wet fine

screen

(trommel)

Decanter

Spent

solvent

Secondary

extraction

clarifier

Dryer

Solvent

Clean

gravel

Contaminated

fines

Recyclable

as

construction

aggregate

Attrition

scrubber

Silt, sand,

clay

Humates

Silt,

clay

Sand Dewatering

Clean

sand

Primary

extraction

tank

Fines

Vaporizer

Concentrated

contaminant

oil (for off-site

disposal)

Organics

free fines

Surge

hopper

Reagents

Reagent

Mixer Curing Crusher

End product: Solidified

sediment—recyclable as

construction aggregate, road

base, landfill cover...

Sediment washing—volume reduction Solvent extraction of organic contaminants Stabilization of inorganic contaminants
127

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 investigate an alternative to the more expensive mixersettler 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 fullscale solvent extraction plant requires large quantities 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 directly 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 demonstrated 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, washing can reduce the quantity of sediment to be

treated by as much as 85% for very coarse sediment. 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 required intensive mixing and a long period (> 20

minutes).

• The sediment was difficult to handle as it adhered

to laboratory hardware.

In order to overcome these difficulties and seek greater

organics contaminant removal, the pilot-plant program

was improved by using a mixture of warm acetate/

alcohol as the solvent. Moreover, some of the extraction

equipment was coated to reduce fouling due to stickiness of the sediment. The sensitivity of organics removal was measured versus the number of extraction

stages. The performance of a continuous extraction

column was also compared with the mixer-settler type

extractor.

Figure 6. Block flow diagram of pilot test program.

Raw sediment

5cy in one roll-off

 (20 drums)

Surge

hopper

Clean

oversize

Powerwash

sample only Washwater is

recycled within

Hydro-sep

Recycle

filtered

fines

Hydro-sep

oversize

washing

Wastewater

• Water decanting/

adjustment

• screening

• transfer to 5-gal

containers

Concentrated

organics

(analysis only)

Wastewater

(analysis only)

N2 inerting

Screened sediment

<1/4" Solvent

make-up

Vent system

(negl)

Org-X

pilot plant Organics-free

sediment

Reagent

cement

Solfix

pilot plant

(metal fixation)

Cured products

• construction fill

• aggregate
128

The pilot-plant performance improved considerably compared 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 compared to 2,3,7,8-TCDD), the reduction was a few percent lower than calculated using the actual concentration

values. The reduction improves as the number of extractions increases, but is not very sensitive after five extractions. 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 intensity, contact time, or a different solvent blend with another 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 sediments than the stabilized-only sediments.

3. Physical Properties and Product Uses—Solidification 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 properties 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 various 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 compost, manure, sludge, other soils to produce a landscaping 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 (UCS)

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 solidification with Portland cement in a pugmill. This lower moisture 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 process data to design a full-scale automated plant with

some confidence. The full-scale plant should be fully

continuous, with large flexibility to accommodate sediment 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 (minutes 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 advantage. 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 3. 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

Dioxin/Furans *

Residual Carbon 37

Total Organic Carbon 30

TCLP Metals Below MDL

TCLP Organics Up to 99

* Not meaningful due to low concentration and precision. The solvent

contained 81-84% of initial total dioxins/furans.
129

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

ORG-X Only

Screened ORG-X Only ORG-X Only ORG-X Only Bench Scale

Untreated Pilot Scale Pilot Scale Pilot Scale @ GRS,

Sediment Used @ Port Newark @ Port Newark @ Port Newark France

Contaminant/ in Pilot Plant (5 extractions with (7 extractions with (Continuous extraction (3 extractions

Class @ Port Newark Acetate/Alcohol) Acetate/Alcohol) with Acetate/Alcohol) with Acetate)

Conc./% Conc./% Conc./% Conc./%

Concentration Reduction Reduction Reduction Reduction

Total 123 ppt 27.7 ppt 29.1 ppt 30.3 ppt Not

Individual 77.6% 76.5% 75.5% meaningful

Dioxins

(TEQ)

Total 5,342 ppt 1,029 ppt 1,030 ppt 1,062 ppt -35% to

Dioxins 80.7% 80.7% 80.1% +66%

Total 750 ppt 96.8 ppt 97.4 ppt 99.3 ppt Not

Individual 87.1% 87.0% 86.8% meaningful

Furans

(TEQ)

Total 30,200 ppt 3,382 ppt 3,300 ppt 3,198 ppt -80% to

Furans 88.8% 89.1% 89.4% +40%

Total 7,946 ppb 125.3 ppb 125.0 ppb 134.3 ppb 79 - 92%

Group 97.8% 98.4% 97.7%

PCBs

Notes:

All analyses are on a dry basis.

ppb = parts per billion

ppt = parts per trillion

TEQ = Total Equivalency Quotient (ref. 2,3,7,8-TCDD)

Table 5. SOLFIX Performance Using Leachability, TCLP Method

Regulatory Bench-Scale Pilot

Toxicity Screened Untreated Pilot SOLFIX-Only ORG-X + SOLFIX

Contaminant Characteristics Sediment 0.2 Parts Cement 0.15 Parts Cement

Total Group PCBs 133 ng/L 64 ng/L 8 ng/L

Semi-volatiles <200 μg/L <200 μg/L <100 μg/L

Total Dioxins/Furans <100 pg/L <100 pg/L <100 pg/L

Metals (mg/L)

Arsenic 5.0 <0.100 0.018 0.018

Barium 100 <0.500 0.232 0.292

Cadmium 1.0 <0.010 <0.001 0.035

Chromium 5.0 <0.028 0.017 0.100

Lead 5.0 <0.050 <0.002 0.007

Mercury 0.2 <0.001 <0.0004 0.034

Selenium 1.0 <0.100 0.014 0.016

Silver 5.0 <0.010 0.001 0.192
130

Table 6. Physical Characterization Data for Stabilized/Solidified Sediments

Water Water Particle Bulk Dry

Sample, Cement/ Content Content Specific Permeability, Density,

Sediment Ratio UCS, psi @ 60°C @ 100°C Gravity cm/sec lbs/cu ft

0.1 Cement SOLFIX Only 26 60.1 69.8 2.54 8.05E-06 37.7

0.2 Cement SOLFIX Only 123 27.9 51.2 2.61 7.05E-06 48.9

0.4 Cement SOLFIX Only 501 18.1 31.0 2.63 2.81E-07 58.8

0.15 Cement 234 50.3 71.1 2.70 1.61E-06 51.4

ORG-X + SOLFIX

0.3 Cement 658 23.4 53.7 2.69 5.62E-07 64.7

ORG-X + SOLFIX

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 solvent 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 estimated 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 various cases and sites by preparing a preliminary engineering design. Moreover, the markets for beneficial use

products must be developed further.

IV. Conclusions

Solvent extraction is a promising and competitive technology for removal of organic contamination from sediments. The acetate/alcohol solvent blend is highly effective 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 engineering design to refine costs.

References

1. Priore, W. and E. Cichon. 1996. Sediment Management, 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. (September).

4. Kirk-Othner. 1980. Encyclopedia of Chemical Technology. Volume 9, Third Edition. New York, NY.

John Wiley & Sons. pp. 672-739.

5. Cusack, R. W. and D. J. Glatz. 1996. Apply LiquidLiquid Extraction to Today's Problems. Chemical

Engineering. (July). pp. 94-103.
131

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

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 undoubtedly moved some quantities about, however the bed

remains relatively secure. But there are other transport

processes besides particle scour; these include molecular diffusion of solutes in porewater after desorption from

solids and out-diffusion of colloids and bioturbation.

These and other in-bed release processes are illustrated in Figure 1. In order to assess the overall effectiveness 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 chemicals 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 issues 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 directed toward this complex process. The local equilibrium 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 concentration. In the case of hydrophobic organics and

inorganics, in-particle hindered diffusion release (4) and

Introduction

Chemical contaminants including inorganics, metals and

organics exist within sediment beds of water bodies both

fresh and marine. These substances may exist in relative 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 loadings 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 constituents within a bed-like form so that their mobility and

hence propensity for contacting the biota can be managed. This paper covers some of the research activities,

ongoing and planned, aimed at enhancing the technology 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 moderate 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 concentration in the bottom sediment. Many of these contaminated beds have been in existence for long time periods
132

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 technologies 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 hydrophobic 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 performed (11). Due to its complexity, the process is under

active investigation (12,13). Typically Fickian type chemical transport models have been used to quantify this

process and algorithms exist with which to compute

release rates (14,4). The latter reference contains algorithms and procedures for computations of release rates

and bed-surface concentrations for the coupled processes of molecular diffusion, bioturbation and hydrodynamic boundary layer resistance to transport.

Typically, contaminants, both organics and metals, exist

in a bed layer ten-to-fifty centimeters in thickness. Figure 2 shows typical profiles, and they represent approximately 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 concentration profile at site DR is due to downcurrent/storm movement 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

Figure 1. Bed-sediment chemical processes.

1 Water-side film

Diffusion molecular brownian*

Bioturbation

Groundwater advection

Localized advection

2

Particle resuspension*

Particle deposition*

Bed translocation*

Reaction

Suspended particle*

Gas bubble advection

Colloid transport*

* Denotes mechanisms tied to fine particle behavior

3

4

5

6

7

8

9

10

11

12
133

understood conceptually and means of quantifying rates

of release and concentrations in the water column exist

(15), a real understanding of contaminant release remains elusive. Recent laboratory work with contaminated 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 predictions of release rates and concentration.

Any proposed containment technology for a so-called

operable site must be judged against the existing release 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

predictable in an engineering design sense. Comparable released and exposed quantities must be quantified 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 estuarine system, the technologies also apply to lake and

riverine systems. A total of five technologies are illustrated: natural recovery, in-situ capping, contained aquatic

disposal (CAD), a confined disposal facility (CDF), and

an upland solid waste landfill. A recent National Research Council report (22) highlights these technologies. This paper will address aspects of the first four

technologies.

Natural recovery

Conceptually natural recovery consists of in-bed processes that retain, destroy, and retard the release of

contaminants. It can be very effective due to a combinaFigure 2. PCB concentration profiles in the bed.
134

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 individually 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 unified theory connecting its many contributing processes

needs to be developed and key features verified by

experiment. For this reason, some of the positive attributes of natural recovery are unappreciated and therefore 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 factors including the complexities of the decision making

process plus political and economic considerations. Healing 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 demonstrate enhance effectiveness. Undertaking more aggressive technologies usually involves dredging. Environmental 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 addition, 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 contaminant mobility studies need to be done to further

verify and test this technology as an aid in its further

adoption.

Contained Aquatic Disposal (CAD)

This option, considered to be more aggressive, involves

dredging and transporting the contaminant mass. In

some instances such as maintaining the required water

depth in ports and harbors, mass removal is necessary.

After transporting the material it must be placed on the

bottom again. This can be on-the-flat or within a depresFigure 3. Conceptual illustration—containment, disposal and natural recovery technologies for contaminated bed sediments (adapted

from Mike R. Palermo, USAE, Vicksburg, MS).
135

sion 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 disadvantages 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 engineering 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 material is placed in a confined disposal facility (CDF). These

facilities are constructed near or adjacent to the shoreline 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 extending above the mean water level. Once in place, the

contaminated material can exhibit several release mechanisms 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 Waterways 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 environmental contamination, the traditional engineering approach 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 contaminated sediment which exists in thin layers covering large

areal expanses, removal is very problematic. Once removed 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 technologies needed is very expensive and largely unverified (22). However, if the goal in remediation of

contaminated sediment is risk management at reasonable 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 released.

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 algorithms 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. However, 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 defended 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, sensors, monitoring procedures, etc., need to be developed

so that failures are detected and the magnitudes can be

quantified. As with any engineered system, failure always has a finite probability. In the case of these containment 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 contaminated 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-
136

nance activities can be planned so that breaches in the

barriers can be repaired effectively and promptly.

Conclusions

This manuscript contains a brief review of the state of

containment research for contaminated bed sediment

and contaminated dredged material primarily from a

university/academic perspective. In large part this review has reflected many of the ongoing activities of the

Hazardous Substance Research Center, South and

Southwest, because its main mission is the development of remediation technologies for this category of

hazardous substances. Four containment technologies:

natural recovery, capping, CAD and CDF were described and their respective research activities reviewed.

It can be concluded that while much work has been

done, much remains to be done. This work must produce high-quality engineering design algorithms based

on laboratory and field data capable of predicting the

release of trace chemical quantities from each containment device. In addition, research efforts should be

focused on detecting containment structure failure and

on making realistic probability estimates of the type and

frequencies of such failures.

Acknowledgment

This work was supported through the U.S. Environmental Protection Agency Cooperative Agreement No.

R819165. It was performed at the Hazardous Substance

Research Center South and Southwest, Louisiana State

University, Baton Rouge, LA. Dr. Danny D. Reible is

Center Director.

The results and opinions given are those of the authors

and do not reflect official U.S. EPA positions or policies.

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and L.J. Thibodeaux, 1993. Diffusive Transport of

Organic Colloids from Sediment Beds. Jo. Environmental Engineering 122: 722-729.

11. Bosworth, W.S. and L.J. Thibodeaux, 1990. Bioturbation: A Facilitator of Contaminant Transport

in Bed Sediment. Environmental Progress 9:

211-217.

12. Mahanty, S. and D.D. Reible, 1998. A Levy

Flight-Random Walks Model of Bioturbation. Water Research (submitted).

13. Reible, D.D., V. Popov, K. T. Valsaraj, L.J.

Thibodeaux, F. Lin, M. Dikshit, M.A. Todaro and

J.W. Fleeger. 1996. Contaminant Fluxes from Sediment Due to Tubiflex Bioturbation. Water Research 30: 704-714.

14. Thibodeaux, L.J., D.D. Reible and W.S. Bosworth.

1990. A Theoretical Evaluation of the Effectiveness of Capping PCB Contaminated New Bedford

Harbor Bed Sediment. Baton Rouge. La. State

University Hazardous Waste Research Center Final Report pp. 12-16.

15. Wilberg, P.L. and C.A. Butman. 1991. Bed Response During Storms at the STRESS Inner Shelf

Site EOS. Trans. AGU. 72 (44).

16. Dennett, K.E., T.W. Sturm, A. Amirtharajah and T.

Mahmood. 1995. “Effect of Adsorbed Natural Or-
137

ganic Matter on the Erosion of Kaolinite Sediments.” Proceedings of the 68th Annual Conference Water Env. Fed., WEFTEC ‘95 4:1 pp. 5-115.

17. Dennett, K.E., T.W. Sturm, A. Amirtharajah, and

T. Mahmood. 1995. “Erosion of Cohesive Sediment in Uniform Flows.” Proceedings Georgia

Water Resources Conf., Athens, GA. April: pp.

221-223.

18. Dennett, K.E., T.W, Sturm, A. Amirtharajah, and

T. Mahmood. 1995. “Flume Studies on the Erosion of Cohesive Sediments.” Proceedings First

International Conf. Water Resources Engineering.

ASCE. August: pp. 199-203.

19. Valsaraj, K.T., R. Ravikrishna, J. Orlius, L.J.

Thibodeaux, D.D. Reible, J.S. Smith. 1997.

Sediment-to-Air Fluxes of Semi-volatile Organic

Compounds due to Sediment Resuspension in

Water. Advances in Environmental Research (in

press).

20. Valsaraj, K.T., B. Choy, G. deSeze. D.D. Reible

and L.J. Thibodeaux. 1998. Sediment-to-Water

Mass Transfer of Semi-volatile Contaminants due

to Sediment Resuspension in Water. Advances in

Environmental Research (accepted).

21. U.S. EPA. 1992. West Harbor Operable Unit

Wyckoff/Eagle Harbor Superfund Site Record of

Decision. Region 10, Seattle, Washington.

22. National Research Council. 1997. Contaminated

Sediments in Ports and Waterways. National Academy Press. Washington, D.C.

23. Thibodeaux, L.J. 1996. Environmental

Chemodynamics. New York, N.Y: John Wiley, pp.

311-344, 350-356.

24. Hugett, R.J. and M.E. Bender. 1980. Kepone in

the James River. Environ. Sci. Technology 14:

918-923.

25. Wang, X.Q., L.J. Thibodeaux, K.T. Valsaraj and

D.D. Reible. 1991. The Efficiency of Capping Contaminated Sediments in Situ: 1. Laboratory Scale

Experiment of Diffusion/Adsorption in the Capping

Layer. Environ. Sci. Technology 25: 1578-1584.

26. Thoma, G.J., D.D. Reible, K.T. Valsaraj and L.J.

Thibodeaux. 1993. Efficiency of Capping Contaminated Sediments in Situ: 2. Mathematics of

Diffusion/Adsorption in the Capping Layer. Environ.

Sci. Technology 27: 2412-2419.

27. Sumeri, A., T.J. Fredette, P.G. Kellog, J.D.

Germano, D.A. Carey and P. Pechko. 1991. “Sediment Chemistry Profiles of Capped in Situ and

Dredged Sediment Deposits: Results from USAE

Offices.” Proceedings 24th Annual Dredging Seminar. Texas A & M, College Station, Report No.

321.

28. Bokuniewicz, H. 1989. Behavior of Sand Caps on

Subaqueous Dredged-Sediment Disposal Sites.

In: Hood, D.W., A. Schoener and P.K. Parks, Eds.

Ocean Processes in Marine Pollution V. 4, Sci.

Monitoring Strategies for Ocean Waste Disposal.

Krieger Pub., Malabar, FL.

29. Zeman, A.J. and T.S. Patterson. 1997. Preliminary Results of Demonstration Capping Project in

Hamilton Harbor. Water Qual. Res. J. Canada 32:

439-452.

30. Poindexter-Rollings, Marian E. 1990. Methodology of Analysis of Subaqueous Sediment Mounds.

Technical Report D-90-2, U.S. Army Engineers

Waterways Experiment Station, Vicksburg, MS.

31. Reible, D.D., S.A. Savant-Malhiet, L.J. Thibodeaux,

K.T. Valsaraj, and T.E. Myers. 1994. “Seepage

Through Dike Walls of Confined Disposal Facilities.” Proceedings of Second International Conference on Dredging and Dredged Material Placement ‘94 Conf., Orlando, FL.

32. Valsaraj, K.T., L.J. Thibodeaux and D.D. Reible.

1995. Modeling Air Emissions from Contaminated

Sediment Dredged Materials. ASTM Special Technical Publication 1293: pp. 227-238.

33. Valsaraj, K.T., B. Choy, R. Ravikrishna, L.J.

Thibodeaux, D.D. Reible, C.B. Price, J.M. Brannon

and T.E. Myers. 1998. Air Emissions form Exposed Sediments and Contaminated Dredged

Material 1. Experimental Data in Laboratory Microcosms and Mathematical Modeling. Jo. Hazardous Materials (submitted).
138

Summary of Conference on

Management and Treatment of Contaminated Sediments

Panel Participants:

Norman Francingues

U.S. Army Corps of Engineers (U.S. COE)

Vicksburg, MS

Emily Green

Sierra Club

Madison, WI

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

considered running experiments under a larger scale

where modifications of the dynamics and movement of

water could be altered to observe the effects of turbulent

mixing on the system?

Response 1. Dr. Thibodeaux has not addressed turbulent conditions in his experiments; however, some researchers have started to analyze the effects on the cap

diffusion rate. Benthic flux chambers and peepers (oily

strips placed into sediment to analyze the migration of

materials up and into the cap from the contaminated

layers) are two technology options suggested to monitor

the diffused flux rate for field study migration projects.

More field study migration projects are needed to compile data and further investigate alternative cap materials and engineering techniques. Conference participant,

Brian Ross, EPA Region 9, also identified a project

where field flux measurements were taken in the outer

channel area of northern San Diego Bay by a Navy

project group. Mr. Ross offered to locate more information to identify the main contact person on the project.

Comment 2. During the conference, a few presenters

discussed the use of natural recovery as a remedial

option. Some consider natural recovery to be a risk

Summary of Panel Discussion: Future

Direction/Research Needs

The panel discussion provided an opportunity for attendees and speakers to identify future research needs for

the management and treatment of contaminated sediments and an open forum for questions and comments

arising from the conference presentations. Below is a list

of the panel participants, followed by a summary of

comments/questions and subsequent responses.

I. Questions/Comments by Spyros

Pavlou, URS Greiner, Inc., Seattle, WA

Comment 1. The stability of a cap and its ability to

minimize flux is a function of bottom currents and the

physical dynamics of the aqueous-solid interface. Louis

Thibodeaux’s presentation, Containment Research for

Contaminant Sediment and Dredged Materials, outlined

various ongoing research projects at Hazardous Substance Research Center South/Southwest. The research

described in Dr. Thibodeaux’s presentation typically included experiments at quiescent conditions under low

flow. Can the release of diffusive flux from the caps in a

turbulent environment be measured? Has Dr. Thibodeaux
139

reduction and management alternative, not a remedial

option. In order for natural recovery to be effective, the

time it takes to reduce a contaminant concentration in

the sediments to a maximum allowable level must be

shorter than the maximum time a population can be

exposed to the contaminant without health risks. The

National Research Council considers natural recovery

to be very effective in conjunction with other technologies, particularly with hot spot remediation where highly

contaminated sediments are removed and the marginally contaminated sediments consequently have sufficient time to reach the maximum allowable concentration.

The concept of natural recovery needs to be looked at

separately for each site, and requires further study.

Response 2. Mike Palermo on the panel responded that

natural recovery is always a part of a remediation solution. Every contaminated site has gradients of contamination, as it is not possible to dredge, remove, or cap it

all. There is always a cut-off at some distance from a hot

spot, beyond which natural recovery is the remedial

option.

Comment 3. The commercialization of remedial technology is escalating at a fast rate. A wide array of

remedial development and management options is being researched to treat sediment contamination levels.

The beneficial uses and the marketability of dredged

sediments are important; however, the costs and benefits and the outcome of beneficial sediment uses were

not fully addressed in this conference.

Response 3. Norman Francingues, U.S. COE, announced that the Corps is sponsoring a conference in

Baltimore, Maryland July 29 to August 1, 1997, that will

identify case studies and methods on how sediments

can be used beneficially.

II. Question by An Unidentified Attendee

Comment. Contaminated sediment treatment or remedial technologies presented during the conference ranged

from options that treat highly contaminated levels of

sediments (nationally characterized as low volume and

high rate of return on investment) to the treatment

options for lower levels of contaminant (nationally characterized as high volume and low rate of return on

investment). Traditionally high-end treatment technologies that work well are being reviewed as alternatives for

the low-end contaminated sites. Since site projects are

often limited by money and sediment volume, and regions are overloaded with information and need help to

effectively consider the ever-growing list of possibilities,

a classification or set of guidelines developed from

these workshops would be useful for decision-making.

This framework would help the regions efficiently evaluate treatment and remedial alternatives appropriate for a

specific site. The need for a guidance document was

further reiterated by Brian Ross, who requested a better,

clearer guidance document, written in more accessible

terms, that would include state, federal, and public outreach efforts to show the public that low-technology

solutions may be acceptable at sites with marginal contamination.

Response. Mike Palermo stated that the alternatives for

treating contaminated sediments need to be classified in

the context of the project scope. A clear distinction

needs to be made between projects that include dredging for navigation and projects that have been initiated

for remedial purposes. Navigation dredging projects typically encounter high volumes of low-level contaminated

sediments, whereas the strictly remedial projects typically encounter sites with higher levels of contamination.

He stated that guidance material is already available,

but that a step-by-step procedure is not appropriate

because of the variation in each site. Emily Green also

responded to the request by identifying a project by the

International Joint Commission for Great Lakes Region;

over the next few years, the commission will be working

on a decision-making guidance document for treating

contaminated sediments.

III. Question by Another Unidentified

Attendee

Comment. How can one respond to the skeptics who

think that capping harbor sediment, which is a highly

liquefied, mobile layer of contamination, will not work

because the sand placement of the cap will only force

the spread and movement of the contamination? How

serious a problem is this movement of contaminant

layers when capping?

Response. Field data have proven that we can place

capping sediments on very soft, contaminated material

above the liquid level; however, capping material for

these sites has to be placed in a controlled manner with

specified technologies, like hydraulic discharging or splithull barges for feathering material. These controlled

methods enable the cap to gradually build up without

displacing the contaminated sediments. Not enough

information is available about the geotechnical aspects

of the buildup or the speed at which the capping sediments can be placed on the contaminated area; the U.S.

COE will perform research and development activities

related to capping sediments throughout the next several years.

IV. Questions by Brian Ross

Comment. Mr. Francingues is presently a member of a

working group, Permanent International Association Navigation Conferences, that addresses maintenance and

construction of port waterway facilities. Introduction of

contaminants into the facilities is one of the biggest

issues facing the maintenance of the international waterways. Because channels collect sediment from point

and nonpoint source discharges, the causes and sources

of the sediment and the contamination into channels

need to be addressed. Otherwise, long-term maintenance (e.g., dredging, capping) will always be required.

Besides addressing historical point source discharges,

what actions are occurring in watershed management?
140

Response. Dennis Timberlake, NRMRL, USEPA, Cincinnati, OH, acknowledged the need to address watershed management, and he explained that EPA is trying

to incorporate watershed management into its efforts.

EPA is trying to place more emphasis on ecosystem

restoration and ecosystem health in conjunction with

human health issues, which were the only issues addressed in the past.

V. Question by Jason Goffinet, Scientist

from Consoer Townsend Envirodyne

Engineers, Inc.

Question. Has the deposition of sediments increased in

navigational channels due to increased travel along the

channel and increased industrialization? Are any methods being taken to reduce erosion (i.e., bank stabilization) and subsequent problems?

Response. Mike Palermo identified some research and

development in the sediment reduction areas that U.S.

COE has performed. The New York Corps District is in

the process of developing a dredge material management plan to meet its long-term needs. One of the issues

being addressed in the plan is the reduction in the load

input into the channels, which will require interagency

cooperation and further research and development. Emily

Green noted that the Sierra Club, Wisconsin Department of Natural Resources, EPA, and other agencies

are collaborating efforts to analyze tools (total maximum

daily loads and the National Pollutant Discharge Elimination System for point sources) that will enable the

incorporation of sediment pollution loads into the river

when setting a maximum daily load. That cooperative

group is also investigating its authority to set permit

costs based on perceived future cleanup costs, in hopes

to encourage pollution prevention and contaminant reduction.

Summary of Questions and Responses

Questions From Day 1 of Sediments

Conference

I. Question by Brian Ross to Thomas

Armitage, Office of Water, EPA, Washington,

DC, Following Presentation of EPA’s National

Sediment Quality Survey

Question. How does EPA plan on improving the quality

and the depth of its inventory database, especially when

the regulatory agencies in the regions are not receiving

any money or resources to compile or to electronically

transfer this data? In addition, how is EPA going to

prevent the problems previously associated with obtaining effective monitoring data for regulatory purposes?

Response. Information currently in the survey database

was compiled from large national databases, which

were made available to EPA. Additional data for the

database should be made available upon individual

discussions with the various states, as EPA has not yet

obtained data from the state monitoring programs. Efforts to obtain more data will increase as the funds

become available. Some of the current limitations of the

database identified in the presentation are the age and

the quality of the data (roughly data from 1980 to 1993

or older); the incomplete sampling coverage (11% of

river and coastline segments); and the dearth of TOC,

acid volatile solids, and toxicity test data in national

scale databases. While these limitations do not prevent

the intended uses of the database, temporal trends of

the data, details of the quality of the data set, and a

closer look at the most current conditions across the

country will be incorporated to improve the database

and to improve future reports to Congress.

II. Question by John Stansbury from the

University of Nebraska to Todd Thornburg,

Hart Cowser, Inc., Seattle, WA, Following

Presentation on the Natural Recovery of

Contaminated Sediments—Examples From

Puget Sound

Question. In the presented studies on natural recovery,

it was shown that contamination concentration decreased

over time. What is the mechanism (e.g., burial and

dilution, degradation) by which the contamination is

decreasing?

Response. Mechanisms for reduction in the contamination vary from site to site and from chemical to chemical

(i.e., some chemicals are more susceptible to volatilization, while others may not volatilize). Sedimentation is

generally the most important physical process for natural recovery; continuous sedimentation of clean material

on top of contaminated sediments can help to control

the contamination problem.

III. Question by Gail Garman, National

Oceanic and Atmospheric Administration—

Hazardous Waste Remedial Actions Program,

to David Petrovski, Chicago, IL, Following

Presentation on Brownfields and Sediment

Disposal at Indiana Harbor

Question. In Mr. Petrovski’s presentation, he discussed

shared liability as an advantage for projects where a

potential exists to combine sediments from various sites

at a facility or in specific parts of the country. Typically,

shared liability is regarded as a disadvantage. Has the

problem of shared liability been resolved; can Mr.

Petrovski offer any guidance on the advantages of sharing liability?
141

Response. Mr. Petrovski indicated that Mr. Nagle, an

attorney who is a co-author of the paper, could not

attend the conference; however, he could give advice on

the advantages of shared liability. Contact Mr. Petrovski

for Mr. Nagle’s telephone number.

IV. Question by Unidentified Attendee to

Douglas Austin, Sevenson Environmental

Services, Inc., Munster, IN, Following

Presentation on Environmental Dredging and

Disposal—Overview and Case Studies

Question. Why were the cleanup standards presented

during the discussion in terms of totals instead of the

more common TCLPs?

Response. A number of standards have been adopted

by regulators to deal with the uncertainty of treatment

systems, one of which is a total standard criteria. Mr.

Austin used the example of total lead concentrations.

Chemical systems do not alter total lead concentrations,

but the systems can tie up the lead into a non-leachable

form; therefore, applying a total lead standard to chemical systems is completely inappropriate. Likewise, requiring uniform compressive strength or capping to the

requirements for treatment plans is also not applicable

to chemical treatment systems. The list of methods the

regulators use to deal with treatment systems includes

much uncertainty and not all the methods are necessarily applicable to chemical treatment systems.

Questions From Day 2 of Sediments

Conference

V. Question by Mike Palermo to Carol

Ancheta, Environment Canada, Downsview,

Ontario, Canada, Following Presentation on

Remediation Strategies and Options for

Contaminated Sediment: Thunder Bay Case

Study Using SEDTEC© in Decision-Making

Question. In what computer program was SEDTEC©, a

directory of contaminated sediment removal and treatment technologies, created? Can the SEDTEC© program be altered to fit a specific customer’s needs?

Response. SEDTEC© is currently available in Microsoft

Access, so it is easily altered to fit the specific needs of

a customer. SEDTEC© will also be available on the

Internet by fall 1997. The current cost for SEDTEC© is

$250 Canadian; the Environment Canada price is only

set to recover costs.

VI. Question by Doug Grosse, NRMRL,

EPA, to Norman Francingues Following

Presentation on U.S. COE Research Programs

Question. What is the difference between bioaccumulation and biomagnification?

Response. Bioaccumulation and biomagnification are

two words that have been used interchangeably. Mr.

Francingues was not clear on the distinction between

the two terms. Attendees Gail Garman and Spyros

Pavlou attempted to clarify the difference, describing

bioaccumulation as a process whereby certain substances accumulate along the whole trophic chain while

biomagnification is a process whereby substances are

transferred from one trophic level to another via the food

chain. Likewise, EPA Terms of Environment1 defines

bioaccumulants as substances, not easily metabolized

or excreted by living organisms, that increase in concentration as the organism takes in contaminated air, water,

or food; biological magnification is defined as a process

whereby certain substances, such as pesticides or heavy

metals, become concentrated in tissues or internal organs as they move up the chain. These substances

migrate up the food chain by working their way into

rivers or lakes where they are eaten by aquatic organisms such as fish, which in turn, are eaten by large birds,

animals, or humans.

VII. Questions to John Quensen, Michigan

State University, East Lansing, MI, Following

Discussion on Microbial Dechlorination and

Bioremediation of PCBs

Question 1. What are the effects of oxygen on the

application of ferrous sulfate in the microbial dechlorination and bioremediation system?

Response 1. Dechlorination is inhibited by the presence

of oxygen. Ferrous sulfate has been produced under

anaerobic conditions.

Question 2. What are the limiting conditions in a sediment that is close to the surface? Does the system need

to be completely anoxic for treatment processes to

proceed?

1 U.S. EPA. 1993. Terms of Environment: Glossary, Abbreviations,

and Acronyms. EPA 175-B-93-001. February 1993.
142

Response 2. Oxygen is normally consumed within the

first few millimeters or centimeters of the sediment surface, depending on a variety of factors (e.g., organic

content). In an earlier test performed by Mr. Quensen,

incubated bottles of sediment left open to the atmosphere reportedly produced substantial dechlorination.

This experimental result indicates that oxygen is consumed as it diffuses through the first few millimeters or

centimeters of sediment. Ken Fisher, from General Electric, performed more detailed experiments on limiting

conditions in surface sediments. Mr. Fisher buried test

tubes of sediments in an aquarium; the test tubes were

open to the overlying oxygenated water. In this experiment, surficial sediments appeared to undergo a combined anaerobic/aerobic process; dechlorination was

reported below the first few millimeters.

VIII. Questions to Thomas Stolzenburg,

RMT, Inc., Madison, WI, Following

Presentation on the Treatment of MetalBearing Solids

Question 1. What were the physical conditions of the

Foundry Waste project site?

Response 1. The Foundry Waste project site consisted

of a 17-acre lagoon with variable sediment grain size,

ranging from sandy to fine-grained material. Sediments

onsite were not high in plasticity, and were separated

and sorted effectively. Consequently, when the sediments were hydraulically dredged, clumping and sticking did not occur, and the sediments mixed easily in the

in-line treatment system.

Question 2. What was the chemical source used in the

reaction described for the coffer dams?

Response 2. Triple super phosphate (TSP) was used in

this reaction. Because TSP has some residual phosphoric acid, a highly reactive, local limestone was also

incorporated into the reaction to buffer the pH. A variety

of phosphate sources may be used in the reaction

described by Mr. Stolzenburg; however, some very reactive phosphates are too acidic, while other phosphate

rock available does not react in the required time frame.
143

Conference on Management and Treatment of

Contaminated Sediments

Exhibitor List

L.V. Benningfield

Vice President of Operations

CF Environmental

18300 West Highway 72

Arvada, CO 80007

303-420-1550

Fax: 303-420-2890

Paul Bucens

Project Manager

Grace Bioremediation Technologies

3451 Erindale Station Road

Misissauga, Ontario, L5C 2S9

Canada

905-272-7474

Fax: 905-272-7472

Bruce Coufombe

Hydrogeologist

RETEC

1001 West Seneca Street

Ithaca, NY 14850

607-277-5716

Fax: 607-277-9057

Georgia Dunaway

Environmental Protection Specialist

Site Management Support Branch

National Risk Management

Research Laboratory

U.S. Environmental

Protection Agency

26 West Martin Luther King Drive

(472)

Cincinnati, OH 45268-0001

513-569-7650

Fax: 513-569-7585

E-mail:

dunaway.georgia@epamail.epa.gov

Robert Amick

Senior Project Manager

IT Corporation

11499 Chester Road

Cincinnati, OH 45246

513-782-4700

Fax: 513-782-4807

Carol Ancheta

Remedial Technologies Program

Environmental Technologies

Advancement Division

Environment Canada

4905 Dufferin Street

Downsview, Ontario, M3H 5T4

Canada

416-739-5874

Fax: 416-739-4342

Douglas Austin

Regional Manager

Sevenson Environmental

Services, Inc.

9425 Calumet Avenue - Suite 101

Munster, IN 46321

219-836-0116

Fax: 219-836-2838

Ed Barth

Environmental Engineer

Site Management Support Branch

National Risk Management

Research Laboratory

U.S. Environmental

Protection Agency

26 West Martin Luther King Drive

Cincinnati, OH 45268-0001

513-569-7669

Fax: 513-569-7585

E-mail: barth.ed@epamail.epa.gov

Bob Ferguson

Director of Sales

Grace Bioremediation Technologies

3451 Erindale Station Road

Misissauga, Ontario, L5C 2S9

Canada

905-272-7473

Fax: 905-272-7472

Annette Gatchett

Office of Research and Development

U.S. Environmental Protection

Agency

26 West Marfin Luther King Drive

Cincinnati, OH 45268-0001

513-569-7697

Fax: 513-569-7920

Norman Grant

President

Normrock Industries

3360 Boulevard De Enterprises

Terrebonne, Quebe~,J6X 4J8

Canada

514-477-5132

Fax: 514-477-2020

Renee Haltmeier

BioGenesis Enterprises, Inc.

7420 Alban Station Boulevard

Suite B-208

Springfield, VA 22150

703-913-9700

Fax: 703-913-9704

John Henningson

North Eastern Region

Operations Manager

Hart Crowser, Inc.

One Exchange Place - Suite 1000
144

Jersey City, NJ 07802-3902

201-309-3087

Fax: 201-309-3040

E-mail: jzh@hartcrowser.com

Tom Janszen

IT Corporation

312 Directors Ddve

Knoxsville, TN 37923

423-690-3211, Ext. 2133

Fax: 423-690-3626

Michael Mensinger

Institute of Gas Technology

ENDESCO Services, Inc.

1700 South Mount Prospect Road

Des Plaines, IL 60018

847-768-0602

Fax: 847-768-0516

E-mail: mensing@igt.org

Ian Orchard

Chief

Remedial Technologies Program

Environmental Technologies

Advancement Division

Environment Canada

4905 Dufferin Street

Downsville, Ontario, M3H 5T4

Canada

416-739-5874

Fax: 416-739-4342

E-mail: ian.orchard@ec.gc.ca

Spyros Pavlou

URS Greiner, Inc., for

National Research Council

2101 Constitution Ave. N.W.

Washington D.C. 20418

William Priore

National Director of Sediment

Remediation Services

Metcalf & Eddy, Inc.

2800 Corporate Exchange Drive

Suite 250

Columbus, OH 43231

614-890-5501, Ext. 223

Fax: 614-890-7421

E-mail: bpriore@acc-net.com

Denise Rousseau

Hazardous Substance Research

Center

Louisiana State University

Baton Rouge, LA

504-388-6770

Paul Schroeder

Waterways Experiment Station

U.S. Army Corps of Engineers

(CEWES-EE-P)

3909 Halls Ferry Road

Vicksburg, MS 39180

601-634-3709

Fax: 601-634-3707

E-mail: schroep@exl.wes.army.mil

Mark Serwinowski

Manager, Business Development

Blasland, Bouck, and Lee

6723 Towpath Road

P.O. Box 66

Syracuse, NY 13214

315-446-9120

Fax: 315-449-0023

E-mail: mas2%bbl@mcimail.com

Howard Shaffer

Program Development Manager

Science and Technology Center

Westinghouse Electric Corporation

1310 Beulah Road

Pittsburgh, PA 15235-5098

412-256-2740

Fax: 412-256-1222

E-mail: shaffer.h.w@wec.com

Eric Stern

Project Manager

New York Harbor Project

U.S. Environmental

Protection Agency

290 Broadway - 24th Floor

New York, NY 10007-1866

212-637-3806

Nancy Ulerich

Program Manager

Science and Technology Center

Westinghouse Electric Corporation

1310 Beulah Road

Pittsburgh, PA 15235-5098

412-256-2198

Fax: 412-256-1222

Starnes Walker

Vice President of Technology

CF Environmental

18300 West Highway 72

Arvada, CO 80007

303-420-1550

Fax: 303-420-2890