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Contaminated Sediment Remediation
Guidance for Hazardous Waste Sites
January 2005 Draft, Peer Review Document:
DO NOT CITE OR QUOTE

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Office of Solid Waste and Emergency Response
OSWER 9355.0.g5 DRAFT
NOTICE
This document provides technical and policy guidance to the U.S. Environmental Protection
Agency (EP A) and state staff on making risk management decisions for contaminated sediment sites. It
also provides information to the public and to the regulated community on how EP A intends to exercise
its discretion in implementing its regulations at contaminated sediment sites. It is important to
understand, however, that this document does not substitute for statutes EP A administers nor their
implementing regulations, nor is it a regulation itself. Thus, this document does not impose legally-
binding requirements on EPA, states, or the regulated community, and may not apply to a particular
situation based upon the specific circumstances. Rather, the document suggests approaches that may be
used at particular sites as appropriate, given site-specific circumstances. EP A made many changes to this
document based on public comment on a draft document. Even though the document is now fmal,
however, EP A welcomes public comments on the document at any time and will consider those
comments in any future revisions to the document which EP A may make without public notice.
ADDITIONAL COPIES
This document is available on the Internet at http://www.epa.gov/superfund/. No fee is required
to download the document.
EP A employees can obtain copies of this guidance, or copies of documents referenced in this
guidance, by calling the Superfund Document Center at 703-603-9232 or by sending an e-mail request to
suoerfund.docmnentcentcr(a),cpa.fZov. No fee is required.
Non-EPA employees can obtain copies of this guidance, or copies of documents referenced in
this guidance, by contacting the National Technical Information Service (NTIS) at 703-605-6000, or by
using their Internet site at http://superfulld.fedworld.gov. Fees for these documents are determined by
NTIS.
January 2005 Draft, Peer Review Document

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Contaminated Sediment Remediation Guidance
for Hazardous Waste Sites
ACKNOWLEDGMENTS
Initial drafts of this document were prepared by an Inter-Agency workgroup led by the U.S.
Environmental Protection Agency (EPA) Office of Emergency and Remedial Response [now Office of
Superfund Remediation and Technology Innovation (OSRTI)]. In addition to EPA, the workgroup
included representatives from the following organizations:
National Oceanic and Atmospheric Administration (NOAA)
U.S. Army Corps of Engineers (USACE)
U.S. Fish and Wildlife Service (USFWS)
Representatives of other organizations contributed to the guidance by commenting on early
drafts. These included the following:
Environment Canada
U.S. Navy
U.S. Geological Survey
U.S. Department of Energy
Oregon Department of Environmental Quality
Massachusetts Department of Environmental Quality
Wisconsin Department of Natural Resources
The following individuals led subgroups to draft various sections of the guidance or otherwise
contributed substantially to the overall character of the guidance:
Steve Ells (EPA OSRTI)
Allison Hiltner (EPA Region 10)
Doug Johnson (EPA Region 4)
Fran Kremer (EP A ORD)
Judith McCulley (EP A Region 8)
Richard Nagle (EP A Region 5)
Michael Palermo (formerly USACE)
The following individuals drafted sections of the guidance or assisted in various substantial ways
in preparation of the document and EP A also sincerely appreciates their assistance:
David Allen (USFWS)
Daniel Averett (USACE)
Ed Barth (EPA ORD)
Gary Baumgarten (EP A Region 6)
Stacey Bennett (EP A Region 6)
Barbara Bergen (EP A ORD)
Ned Black (EPA Region 9)
Richard Brenner (EP A ORD)
Daniel Chellaraj (EPA OSRTI)
Scott Cieniawski (EP A GLNPO)
Sherri Clark (EPA OSRTI)
Barbara Davis (EP A OSRTI)
Kevin E. Donovan (EP A OSW)
David Drake (EP A Region 7)
Bonnie Eleder (EPA Region 5)
Jane Marshall Farris (EP A OST)
Joan Fisk (EPA OSRTI)
Tom Fredette (USACE)
Gayle Garman (NOAA)
Joanna Gibson (EPA OSRTI)
January 2005 Draft, Peer Review Document

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Contaminated Sediment Remediation Guidance
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Ron Gouguet (NOAA)
Patricia Gowland (EP A OSRTl)
Jim Hahnenberg (EP A Region 5)
Earl Hayter (EPA ORD)
Richard Healy (EP A OST)
Glynis Hill (EPA OWOW)
Robert Hitzig (EPA OSRTI)
Michael Horne (USFWS)
Michael Hurd (EPA OSRTl)
Sheila Igoe (EP A OGe)
Sharon Jaffess (EPA Region 2)
Brenda Jones (EPA Region 5)
Kymberlee Keckler (EPA Region 1)
Karen Keeley (EP A Region 10)
Anne Kelly (EP A Region 2)
Michael Kravitz (EP A ORD)
Tim Kubiak (USFWS)
Carlos Lago (EP A OSW)
Amy Legare (EP A OSRE)
Sharon Lin (EP A OWOW)
John Lindsay (NOAA)
Terry Lyons (EP A ORD)
Kelly Madalinski (EPA OSRTl)
John Malek (EP A Region 10)
Steve Mangion (EP A Region 1)
Dale Matey (EP A OSWER)
Bruce Means (EP A OSRTl)
Amy Merten (NOAA)
David Mueller (USGS)
Jan A. Miller (USACE)
William Nelson (EP A ORD)
Walter Nied (EPA Region 5)
Mary Kay O'Mara (USACE)
Charles Openchowski (EP A OGe)
David Petrovski (EPA Region 5)
Cornell Rosiu (EPA Region 1)
Fred Schauffler (EP A Region 9)
Ken Seeley (USFWS)
Robert Shippen (EP A OST)
Craig Smith (EP A Region 7)
Mark Sprenger (EPA OSRTl)
Laurel Staley (EP A ORD)
Pam Tames (EP A Region 2)
Dennis Timberlake (EP A ORD)
Yolaanda Walker (EPA OSRE)
Larry Zaragoza (EPA OSRTI)
Craig Zeller (EP A Region 4)
Technical support for this project was provided by Rebecca Tirrell, Molly Wenner, Aaron
George, William Zobel, and others at DynCorp Systems & Solutions LLC (DSS), a CSC company, under
EP A Contract Number 68- W7 -0051. Workgroup facilitation services were provided by Kim Fletcher,
SRA International, Inc., and by Jim Fary, EPA OSRTI. EPA very much appreciates their able support.
Ernie Watkins, Chair, Contaminated Sediment Remediation Guidance Workgroup
Leah Evison, Project Manager, Office of Superfund Remediation and Technology Innovation
January 2005 Draft, Peer Review Document

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ContaminaJed Sediment Remediation Guidance
for Hazardous Waste Sites
TABLE OF CONTENTS
Appendices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

Highlights. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. x
1.0 INTRODUCTION[[[ 1-1

1.1 PURPOSE[[[ 1-1
1.2 CONTAMINATED SEDIMENT........... . .. .. . .. . .. .. . ..................1-2
1.3 RISK MANAGEMENT PRINCIPLES AND REMEDIAL APPROACHES. . . . . . . . . . 1-3
1.3.1 Remedial Approaches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
1.3.2 Urban Revitalization and Reuse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
1.4 DECISION-MAKING PROCESS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
1.4.1 Decision Process Framework. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
1.4.2 Technical Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
1.5 STATE, TRIBAL, AND TRUSTEE INVOLVEMENT......................... 1-11
1.6 COMMUNITY AND OTHER STAKEHOLDER INVOLVEMENT ...............1-12
2.0 REMEDIAL INVESTIGATION CONSIDERATIONS .................................2-1
2.1 SITE CHARACTERIZATION........ . .. . ....... ...... .. ........... .......2-1
2.1.1 Data Quality Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2.1.2 Types of Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
2.1.3 Background Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
2.2 CONCEPTUAL SITE MODELS. .. . .. . . . . . . .. . . . . . . . . . . . .. . .. .. . . . . .. . . . . . 2-7
2.3 RISK ASSESSMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-12
2.3.1 Screening Risk Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
2.3.2 Baseline Risk Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
2.3.3 Risks from Remedial Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
2.4 CLEANUP GOALS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
2.4.1 Remedial Action Objectives and Remediation Goals. . . . . . . . . . . . . . . . . . .2-15
2.4.2 Cleanup Levels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ; . 2-16
2.5 WATERSHED CONSIDERATIONS....................................... 2-17
2.5.1 Role of the Contaminated Water Body. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18
2.5.2 Water Body and Land Uses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18
2.6 SOURCE CONTROL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20
2.7 PHASED APPROACHES AND EARLY ACTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21
2.8 SEDIMENT STABILITY AND CONTAMINANT FATE AND TRANSPORT...... 2-22
2.8.1 Data Collection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-25
2.8.2 Routine and Extreme Events. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-27
2.8.3 Bioturbation[[[ 2-30
2.8.4 Predicting the Consequences of Sediment and Contaminant Movement. . . . 2-31

2.9 MODELING[[[ 2-32

2.9.1 Sediment/Contaminant Transport and Fate Model Characteristics. . . . . . . . . 2-33
2.9.2 Detennining Whether A Mathematical Model is Appropriate. . . . . . . . . . . . . 2-36

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3.0 FEASIBILITY STUDY CONSIDERATIONS. .. . .. .. . .. ........ . .. ..... . .. ...... .. ..3-1
3.1 DEVELOPING REMEDIAL ALTERNATIVES FOR SEDIMENT... . .. ........ ..3-1
3.1.1 Alternatives which Combine Approaches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3.1.2 The No-Action Alternative. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.1.3 In-Situ Treatment Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.2 NCP REMEDY SELECTION CRITERIA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3.3 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS FOR
SEDIMENT ALTERNATIVES.......................................... 3-7
3.4 LONG-TERM EFFECTIVENESS AND PERMANENCE OF SEDIMENT

ALTERNATIVES...... .. . .. ... ............. . .. ...... .. .......... . ...3-12

3.5 COST[[[ 3-15

3.5.1 Capital Costs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15
3.5.2 Operation and Maintenance Costs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-18
3.5.3 Net Present Value. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . 3-19
3.5.4 State Cost Share. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-19
3.6 INSTITUTIONAL CONTROLS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20
4.0 MONITORED NATURAL RECOVERY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1 INTRODUCTION[[[ 4-1
4.2 POTENTIAL ADVANTAGES AND LIMITATIONS........................... 4-3
4.3 LINES OF EVIDENCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
4.4 NATURAL RECOVERY PROCESSES. .. . . . . . . . . . .. .. . . . . .. .. . .. . . . .. . .. . . . 4-6
4.4.1 Physical Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
4.4.2 Biological and Chemical Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
4.5 ENHANCED NATURAL RECOVERY...... .. . .. . ....... . .. ..... . .. ..... . . 4-10
4.6 ADDITIONAL CONSIDERATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
5.0 IN-SITU CAPPING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1 INTRODUCTION[[[ 5-1
5.2 POTENTIAL ADVANTAGES AND LIMITATIONS........................... 5-3
5.3 EVALUATING SITE CONDITIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
5.3.1 Physical Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
5.3.2 Sediment Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
5.3.3 Waterway Uses and Infrastructure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
5.3.4 Habitat Alterations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
5.4 FUNCTIONAL COMPONENTS OF A CAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7
5.4.1 PhysicalIsolationComponent .....................................5-7
5.4.2 StabilizationlErosion Protection Component. . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8
5.4.3 Chemical Isolation Component. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9
5.5 OTHER CAPPING CONSIDERATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10
5.5.1 Identification of Capping Materials .................................5-11
5.5.2 Geotechnical Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13

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6.0 DREDGING AND EXCAVATION......... .. . .................... . ., . .. .. ... . .. ..6-1

6.1 INTRODUCTION[[[ 6-1
6.2 POTENTIAL ADVANTAGES AND LIMITATIONS........................... 6-3
6.3 SITE CONDITIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
6.3.1 Physical Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
6.3.2 Waterway Uses and Infrastructures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6
6.3.3 Habitat Alteration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6
6.4 EXCAVATION TECHNOLOGIES .........................................6-7
6.5 DREDGING TECHNOLOGIES ........................................... 6-10
6.5.1 Mechanical Dredging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10
6.5.2 Hydraulic Dredging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11
6.5.3 Dredge Equipment Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12
6.5.4 Dredge Positioning .'. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-20
6.5.5 Predicting and Minimizing Resuspension, Contaminant Release and Transport
During Dredging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21
6.5.6 Containment Barriers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23
6.5.7 Predicting and Minimizing Dredging Residuals. . . . . . . . . . . . . . . . . . . . . . . 6-25
6.6 TRANSPORT, STAGING, AND DEWATERING............................. 6-27
6.7 SEDIMENT TREATMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-29
6.7.1 Pre-Treatment................................................. 6-29

6.7.2 Treatment[[[ 6-30
6.7.3 Beneficial Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-33
6.8 SEDIMENT DISPOSAL. .. . .. .. . . . . .. .. . .. . .. .. . .. . .. .. . . . . .. .. . .. . .. .. . 6-34
6.8.1 Sanitary/Hazardous Waste Landfills. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-34
6.8.2 Confined Disposal Facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-35
6.8.3 Contained Aquatic Disposal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-36
6.8.4 Losses from Disposal Facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-36
7.0 REMEDY SELECTION CONSIDERATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
7.1 NCP REMEDY SELECTION FRAMEWORK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
7.2 CONSIDERING REMEDIES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
7.3 COMPARING NET RlSK REDUCTION ....................................7-14
7.4 CONSIDERING INSTITUTIONAL CONTROLS .............................7-16
7.5 CONSIDERING NO-ACTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-17
7.6 CONCLUSIONS[[[ 7-18
8.0 REMEDIAL ACTION AND LONG-TERM MONITORING. . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
8.1 INTRODUCTION[[[ 8-1
8.2 SIX RECOMMENDED STEPS FOR SITE MONITORING. . . . . . . . . . . . . . . . . . . . . . 8-3
8.3 POTENTIAL MONITORING TECHNIQUES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-8
8.3.1 Physical Measurements. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9
8.3.2 Chemical Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-10
8.3.3 Biological Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-10
8.4 REMEDY-SPECIFIC MONITORING APPROACHES. .................. . .. .. .8-11

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APPENDICES
A PRINCIPLES FOR MANAGING CONTAMINATED SEDIMENT RISKS AT HAZARDOUS

WASTE SITES...... .............. .. .. . .......... ... .. ...... .. ...... .. . .... A-I
January 2005 Draft, Peer Review Document
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Contaminated Sediment Remediation Guidance
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HIGHLIGHTS
Highlight 1-1: Potential Sources of Contaminants in Sediment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Highlight 1-2: Major Contaminants at Superfund Sediment Sites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Highlight 1-3: Why Sediment Sites Are a Unique Challenge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Highlight 1-4: Risk Management Principles Recommended for Contaminated Sediment Sites. . . . . . . 1-5
Highlight 1-5: Remedial Approaches for Contaminated Sediment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Highlight 1-6: Superfund Remedial Response Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
Highlight 1-7: Hypothetical Framework for Cleanup of Contaminated Sediment. . . . . . . . . . . . . . . . . 1-9
Highlight 1-8: National Research Council- Recommended Framework for Risk Management. . . . . . 1-11
Highlight 1-9: Common Community Concerns about Contaminated Sediment. . . . . . . . . . . . . . . . . . 1-13
Highlight 1-10: Common Community Concerns about Sediment Cleanup. . . . . . . . . . . . . . . . . . . . . . 1-13
Highlight I-II: Community Involvement Guidance and Advice. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14
Highlight 2-1: Example Site Characterization Data for Sediment Sites. . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Highlight 2-2: Typical Elements of a Conceptual Site Model for Sediment. . . . . . . . . . . . . . . . . . . . . . 2-8
Highlight 2-3: Sample Conceptual Site Model Focusing on Ecological Threats. . . . . . . . . . . . . . . . . . 2-9
Highlight 2-4: Sample Pictorial-Style Conceptual Site Model Focusing on Human and Ecological Threats

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-10

Highlight 2-5: Sample Conceptual Site Model Focusing on Human Health Threats. . . . . . . . . . . . . . 2-11
Highlight 2-6: Sample Remedial Action Objectives for Contaminated Sediment Sites. . . . . . . . . . . . 2-15
Highlight 2-7: Potential Examples of Early Actions at Contaminated Sediment Sites. . . . . . . . . . . . . 2-23
Highlight 2-8: Potential Causes of Sediment and/or Contaminant Movement. . . . . . . . . . . . . . . . . . . 2-24
Highlight 2-9: Principal Types of Armoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-26
Highlight 2-10: Key Empirical Methods to Evaluate Sediment and Contaminant Movement. . . . . . . 2-28
Highlight 2-11: Sample Depths of Bioturbation Activity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-31
Highlight 2-12: Key Characteristics of the Major Types of Sediment/Contaminant
Transport and Fate Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-34
Highlight 2-13: Sample Conceptual Site Model Focusing on Sediment-WaterInteraction ......... 2-35
Highlight 2-14: Sample Contaminant Exposure Modeling Framework. . . . . . . . . . . . . . . . . . . . . . . . 2-38
Highlight 2-15: Important Principles to Consider in Developing and Using Models
at Sediment Sites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-41
Highlight 3-1: SITE Program In-situ Treatment Technology Demonstrations. . . . . . . . . . . . . . . . . . . . 3-4
Highlight 3-2: Examples of Potential ARARs for Sediment Sites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8
Highlight 3-3: Examples of Categories of Capital Costs for Sediment Remediation. . . . . . . . . . . . . . 3-16
Highlight 3-4: Some Key Points to Remember about Feasibility Studies for Sediment. . . . . . . . . . . . 3-22
Highlight 4-1: General Hierarchy of Natural Recovery Processes for Sediment Sites. . . . . . . . . . . . . . 4-2
Highlight 4-2: Some Site Conditions Especially Conducive to Monitored Natural Recovery. . . . . . . . 4-3
Highlight 4-3: Potential Lines of Evidence of Monitored Natural Recovery. . . . . . . . . . . . . . . . . . . . . 4-5
Highlight 4-4: Sample Conceptual Model of Natural Processes Potentially Related to MNR ........ 4-7
Highlight 4-5: Some Key Points to Remember When Considering Monitored Natural Recovery. . . . 4-13
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Highlight 5-1: Some Site Conditions Especially Conducive to In-Situ Capping. . . . . . . . . . . . . . . . . . 5-2
Highlight 5-2: Sample Cap Designs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12
Highlight 5-3: Sample Capping Equipment and Placement Techniques. . . . . . . . . . . . . . . . . . . . . . . . 5-15
Highlight 5-4: Some Key Points to Remember When Considering In-Situ Capping. . . . . . . . . . . . . . 5-16
Highlight 6-1: Sample Flow Diagram for Dredging/Excavation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Highlight 6-2: Some Site Conditions Especially Conducive to Dredging or Excavation. . . . . . . . . . . . 6-2
Highlight 6-3: Example of Excavation Following Isolation Using Sheet Piling. . . . . . . . . . . . . . . . . . . 6-8
Highlight 6-4: Examples of Permanent or Temporary Rerouting of a Water Body. . . . . . . . . . . . . . . . 6-9
Highlight 6-5: Examples of Mechanical Dredges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11
Highlight 6-6: Examples of Hydraulic Dredges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13
Highlight 6-7a: Example Environmental Dredging Operational Characteristics and Selection Factors

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-14

Highlight 6-7b: Footnotes for Example Environmental Dredging Operational Characteristics
and Selection Factors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-17
Highlight 6-8: Sample of Dredging Dewatering Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-28
Highlight 6-9: NY/NJ Harbor - An Example of Treatment Technologies and Beneficial Use. . . . . . . 6-32
Highlight 6-10: Cross Section of a Typical Confmed Disposal Facility Dike with a Filter Layer. . . . 6-35
Highlight 6-11: Some Key Points to Remember When Considering Dredging and Excavation. . . . . . 6-37
Highlight 7-1: Key NCP Remedy Expectations and Their Potential Application
to Contaminated Sediment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
Highlight 7-2: Some Site Conditions Especially Conducive to Particular Remedial Approaches for
Contaminated Sediment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
Highlight 7-3: Examples of Some Key Differences Between Remedial Approaches for Contaminated

Sediment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7
Highlight 7-4: Sample Factors for Comparative Evaluation of Net Risk Reduction. . . . . . . . . . . . . . . 7-15
Highlight 8-1: Key Questions For Environmental Monitoring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
Highlight 8-2: Recommended Six-Step Process for Developing and Implementing a Monitoring Plan

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4

Highlight 8-3: Sample Cap Monitoring Phases and Elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-14
Highlight 8-4: Some Key Points to Remember About Monitoring Sediment Sites. . . . . . . . . . . . . . . . 8-18
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ContaminaJed Sediment Remediation Guidance
for Hazardous Waste Sites
Executive Summary
In 2004, the U.S. Environmental Protection Agency (EP A) released the Updated Report on The
Incidence and Severity of Sediment Contamination in Surface Waters of the United States: National
Sediment Quality Survey, that identifies areas in all regions of the country where sediment may be
contaminated at potentially hannfullevels (U .S. EP A 2004a). Contaminated sediment has significantly
impaired the navigational and recreational uses of rivers and harbors in the U.S. (NRC 1997 and 2001)
and is a contributing factor in many of the 2,800 fish consumption advisories nationwide (U.S. EPA
2003a). As of 2001, EPA had decided to take action to clean up sediment at approximately 140 sites
under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and
additional sites under the Resource Conservation and Recovery Act [(RCRA), U.S. EPA 200Ia]. The
remedies for more than 65 sites are large enough that they are being tracked at the national level. Many
other sites are being cleaned up under state authorities, other federal authorities, or as voluntary actions.
This document provides technical and policy guidance for project managers and management
teams making remedy decisions for contaminated sediment sites. It is primarily intended for project
managers considering actions under CERCLA, although technical aspects of the guidance are also
intended to assist project managers addressing sediment contamination under RCRA. However, many
aspects of this guidance will be useful to other governmental organizations and potentially responsible
parties (pRPs) that may be conducting a sediment cleanup. Although aspects related to characterization
and risk assessment are summarized, the guidance focuses on considerations regarding feasibility studies
and remedy selection for sediment. Provided below is a short summary of each of the eight chapters.
Sediment cleanup is a complex issue, and as new techniques evolve, EP A will issue new or updated
guidance on specific aspects of contaminated sediment assessment and remediation.
Chapter I, Introduction, describes the general backdrop for contaminated sediment remediation
and reiterates EPA's previously issued OSWER Directive 9285.6-08, Principles for Managing
Contaminated Sediment Risks at Hazardous Waste Sites (U.S. EPA 2002a). Other issues addressed here
include the role of the natural resource trustees, states, tribes, and the community at sediment sites.
Where there are natural resource damages associated with sediment sites, coordination between the
remedial and trusteeship roles a~ the federal, state, and tribal levels is especially important. In addition to
their role as natural resource trustees, certain state cleanup agencies and certain Indian tribes or nations
have an important role as co-regulators and/or affected parties and as sources of essential information.
Communities of people who live and work adjacent to water bodies containing contaminated sediment
should be given understandable information about the safety of their activities, and be provided
significant opportunities for involvement in the EP A's decision-making process for sediment cleanup.
Chapter 2, Remedy Investigation Considerations, introduces investigation issues unique to the
sediment environment, including those related to characterizing the site, developing conceptual site
models, understanding current and future watershed conditions, controlling sources, and developing
cleanup goals. Especially important at sediment sites is an accurate conceptual site model that identifies
contaminant sources, transport mechanisms, exposure pathways, and receptors at various levels of the
food chain. Project managers should consider the role of a sediment site in the watershed context,
including other potential contaminant sources, key issues within the watershed, and current and
reasonably anticipated or desired future uses of the water body and adjacent land. Essential parts of good
site characterization and remedy selection include the identification and control of continuing sources of
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Contaminated Sediment Remediation Guidance
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contamination and an accurate understanding of their contribution to site risk and potential for re-
contamination. It is also very important that remedial action objectives, remediation goals, and cleanup
levels are based on site-specific data and are clearly defmed. At most Superfund sites, chemical-specific
remediation goals should be developed into fmal contaminated sediment cleanup levels by weighing the
National Oil and Hazardous Substances Pollution Contingency Plan (NCP) balancing and modifying
criteria and other factors relating to uncertainty, exposure, and technical feasibility.
Chapter 2 also introduces issues relating to sediment bed stability, contaminant fate and transport,
and modeling at sediment sites. An important part of the remedial investigation at many sediment sites is
a site-specific assessment of the extent of sediment disturbance in the past, and a prediction about whether
there is likely'to be significant disturbance in the foreseeable future. An accurate assessment of sediment
stability (e.g., erosion and deposition rates) and contaminant fate and transport (e.g., transformation and
movement of contaminants) can be one of the most important factors in identifying areas suitable for
monitored natural recovery (MNR), in-situ caps or near-water confmed disposal facilities. Evaluation of
alternatives should include consideration of dIsruption from human and natural causes, including at a
minimum, the I OO-year flood and other events with a similar probability of occurrence. Project managers
should make use of the variety of empirical field methods available for evaluating sediment stability and,
where appropriate, also use numerical models for evaluating events for which there is no field record and
for predicting future stability. There is a wide range of empirical models and more robust computer
models that can be applied to contaminated sediment sites. Models are useful tools, but they can be very
time consuming and expensive to apply at complex sediment sites. Nevertheless, models are helpful in
that, when properly applied, they provide a more complete understanding of the future transport and fate
of contaminants. When using models, project managers should be aware of the uncertainties and
variability of model predictions and, where possible, quantify these using sensitivity analysis or other
evaluation methods. Project managers should, where possible, use verified models that are in the public
domain, calibrated and validated to site-specific conditions.
Chapter 3, Feasibility Study Considerations, supplements existing EP A guidance by offering
sediment-specific guidance about developing alternatives, applying the NCP remedy selection criteria,
identifying applicable or relevant and appropriate requirements (ARARs), evaluating long-term
effectiveness and permanence, estimating cost, and using institutional controls. Major remedies include
dredging and excavation, in-situ capping, and MNR. Innovative pilot and lab testing of in-situ treatment
in the form of reactive caps or sediment additives are underway and may be useful in the future. Due to
the limited number of cleanup methods available for contaminated sediment, generally project managers
should evaluate each of the three major remedies (sediment removal, capping, and MNR) at every site
where they might be appropriate. At large or complex sites, project managers have found that alternatives
that combine a variety of approaches are frequently cost effective. All fmal remedial actions at CERCLA
sites must be protective of human health and the environment, and must comply with ARARs unless a
waiver is justified. Developing accurate cost estimates is an essential part of evaluating sediment
alternatives. Project managers should evaluate capital costs, operation and maintenance costs (including
long-term monitoring), and net present value. When evaluating alternatives with respect to the long-term
effectiveness and permanence criterion, it is important to remember that each of the three major remedies
may be capable of reaching acceptable levels of long-term effectiveness and permanence, and that site-
specific characteristics must be reviewed during the alternatives evaluation to ensure that the alternative
selected will be effective in that environment. Institutional controls are frequently evaluated as part of
sediment alternatives to prevent or reduce human exposure to contaminants. Common types of
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Contaminated Sediment Remediation Guidance
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institutional controls at sediment sites include fish consumption advisories, commercial fishing bans, and
waterway use restrictions. In some cases, land use restrictions or structure maintenance requirements
have also been important elements of an alternative.
Chapter 4, Monitored Natural Recovery, summarizes the natural processes that should be
considered when evaluating MNR as a remedy, and briefly discusses enhanced natural recovery through
thin-layer placement. The chapter defmes MNR as a remedy that uses known, ongoing, naturally
occurring processes to contain, destroy, or otherwise reduce the bioavailability or toxicity of contaminants
in sediment. Although "natural recovery" may be ongoing at many sites, the key factors that distinguish
use ofMNR as a remedy are the presence of unacceptable risk (i.e., the need for action), ongoing
processes that reduce risk from the contaminated sediment, and the establishment of a cleanup level that is
expected to be met in a particular time frame. Although burial by clean sediment is often the dominant
process relied upon for natural recovery, multiple physical, biological, and chemical mechanisms
frequently act together to reduce risk. Evaluation of MNR should usually be based on site-specific data
collected over a number of years, including multiple lines of evidence. Project managers should evaluate
the long-term stability of the sediment bed and the mobility of contaminants within it. Contingency
measures should be included as part of a MNR remedy when there is significant uncertainty that the
remedial action objectives will be achieved within the predicted time frame. MNR should generally be
used as one component of an overall site remedy, and cautiously as the sole risk reduction approach.
Chapter 4 also discusses the major advantages and disadvantages of MNR. The major advantages
of MNR are its relatively low cost and its non-invasive nature involving minimal disruption to the
existing human and biological community. Because no construction or infrastructure is needed, it is
generally much less disruptive to communities than active remedies. Major disadvantages of MNR are
that it generally leaves contaminants in place without engineered containment; it can be slow to reach
cleanup levels in comparison to active remedies; and its effectiveness may be more uncertain than active
remedies. As any risk reduction approach that takes a period of time to reach remediation goals, remedies
that include MNR frequently rely upon institutional controls, such as fish consumption advisories, which
may have limited effectiveness in controlling human exposure during the recovery period.
Chapter 5, In-Situ Capping, summarizes the major capping technologies and describes the site
conditions that are important to understand in evaluating the feasibility and effectiveness of in-situ
capping. In-situ capping refers to placement of a subaqueous covering or cap of clean material over
contaminated sediment that remains in place. Caps are generally constructed of clean sediment, sand, or
gravel, but can also include geotextiles, liners, or the addition of material, such as organic carbon, to
attenuate the flux of contaminants. A cap reduces risk through the following three primary functions: I)
physical isolation of the contaminated sediment from the aquatic environment; 2) stabilization of
contaminated sediment, preventing resuspension and transport to other sites; and 3) reduction of the
movement of dissolved and colloidally transported contaminants. Backfill of clean material designed to
mix with dredging residuals or to fill post-dredging depressions, rather than act as a engineered cap to
isolate buried contaminants, is not considered in-situ capping in this guidance.
Chapter 5 also discusses the major advantages and disadvantages of in-situ capping. The major
advantage of in-situ capping is that it can quickly reduce exposure to contaminants. Compared to
dredging and excavation, less infrastructure is needed (e.g., materials handling, treatment, disposal), and
the potential for contaminant resuspension and the risks associated with dispersion of contaminated
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Contaminated Sediment Remediation Guidance
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materials during construction is typically lower. In-situ capping may also be less disruptive to
communities than dredging or excavation. The major disadvantage of in-situ capping is that the
contaminated sediment is left in place in the aquatic environment where contaminants may be exposed or
dispersed if the cap is not properly maintained or if contaminants move through the cap in significant
amounts. Another potential disadvantage to in-situ capping may be that in some situations a preferred
habitat may not be provided by the cap materials.
Chapter 6, Dredging and Excavation, summarizes excavation (conducted in the dry) and dredging
(conducted under water) technologies; the components involved in transport, treatment, staging, and
disposal of dredged or excavated contaminated sediment; and describes the importance of evaluating site
conditions that are critical to the feasibility and effectiveness of dredging and excavation. A dredging or
excavation alternative should include a thorough evaluation of the details concerning all phases of the
project, including removal, staging, de-watering, water treatment, sediment transport, and sediment
treatment, re-use, or disposal. Transport and disposal options for contaminated sediment are sometimes
complex and controversial and should be discussed with stakeholders early in the project. In some cases,
specialized methods of operation or equipment may be needed in order to minimize resuspension of
sediment and transport of contaminants. Project managers should make realistic, site-specific predictions
of residual contamination based on pilot studies or comparable sites. Where effective debris removal and
over-dredging (removal of some clean sediment below the contaminated sediment) are possible, residual
contamination is generally lower than where these practices are not possible. In some environments,
excavation may lead to lower levels of residual contamination than dredging, although site preparation for
excavation can be more complex due to the need for re-routing or draining the water body.
Chapter 6 also discusses the major advantages and disadvantages of contaminated sediment
removal by dredging and excavation. One of the principal advantages of removing contaminated
sediment from the aquatic environment is that, if cleanup levels are achieved, it results in the least
uncertainty regarding future environmental exposure to contaminants because they are removed from the
aquatic ecosystem and treated and/or disposed in a controlled environment. Sediment removal also
allows maximum flexibility regarding future use of a water body. Although remedies at sites with
bioaccumulative contaminants usually require the development or continuation of fish consumption
advisories for a period of time after removal, other types of institutional controls might not be necessary
to protect a cap or layer of natural sedimentation. The principal disadvantages of sediment removal are
that it is usually more complex and costly than in-situ cleanup methods, and that there is frequently
significant uncertainty concerning the extent of residual contamination. The need for transport, storage,
treatment (where applicable), and disposal facilities may lead to increased social or risk impacts on
communities. In particular, disposal capacity may be limited in existing municipal or hazardous waste
landfills and it may be difficult to site new local disposal facilities. Another disadvantage includes the
potential for contaminant losses during dredging through resuspension, and to a generally lesser extent,
through other processes during transport, treatment, or disposal. Finally, short-term disruption of the
benthic environment is unavoidable during sediment removal, as it is for a capping remedy.
Chapter 7, Remedy Selection Considerations, discusses the NCP's remedy selection framework,
including applying the NCP expectations (40 CFR ~300.430(a)(I)(iii» to CERCLA contaminated
sediment remedies, considering a no-action alternative, choosing among sediment remedies and
comparing net risk reduction, and considering alternatives that include institutional controls. Generally,
selecting a "no-action" remedy may be appropriate when: 1) the site poses no current or potential threat to
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Contaminated Sediment Remediation Guithlnce
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human health or the environment; 2) CERCLA or RCRA do not provide the authority to take action; or 3)
a previous action has eliminated the need for further action. Where a remedy is necessary, the best route
to overall risk reduction depends on a large number of site-specific considerations, some of which may be
subject to significant uncertainty. Any decision regarding the specific choice of a remedy for
contaminated sediment should be based on careful consideration of the advantages and disadvantages of
each available option and a comparison among them. This chapter includes two summary tables to help
with this process: one describes site conditions especially conducive to each of the three major remedies
for sediment (MNR, capping, dredging), and the other summarizes key differences between the three
major remedies with respect to the NCP's nine remedy selection criteria. Documenting and
communicating how and why remedy decisions were made are especially important at complex sediment
sites. When considering remedies that include institutional controls, project managers should determine
what entities possess the legal authority, capability and willingness to implement, and where applicable,
monitor, enforce and report on the status of the control. When evaluating cleanup alternatives, project
managers should include realistic assumptions concerning residuals and contaminant releases from in-situ
and ex -situ remedies, the potential effects of those residuals and releases, and the length of time over
which a risk may persist.
At many sites, but especially at large sites, a combination of sediment cleanup methods may be
the most appropriate way to manage the risk. The remedy selection process for sediment sites should
include a clear understanding of the uncertainties involved, including uncertainties concerning the
predicted effectiveness of various alternatives and the time frames for achieving remedial goals. The
uncertainty of factors very important to the remedy decision should be quantified, so far as this is
possible. Where it is not possible to quantify uncertainty, sensitivity analysis may be helpful to determine
which apparent differences between alternatives are most likely to be significant.
Chapter 8, Remedial Action and Long-Term Monitoring, provides an approach to developing an
effective remedial action and long-term monitoring program at contaminated sediment sites. This chapter
presents the key steps in designing and conducting a monitoring program at a sediment site, introduces
some of the monitoring techniques available for physical, chemical, and biological measurements, and
summarizes some of the factors to consider when monitoring remedies including natural recovery, in-situ
capping, or dredging/excavation. A monitoring program is important for all types of sediment remedies,
both during the remedial action and over the long term to ensure that sediment risks and exposure
pathways at a site have been adequately managed and the remedy remains protective. The development
of monitoring plans should follow a systematic planning process that identifies monitoring objectives,
decision criteria, endpoints, and data collection and analysis methods. Project managers should ensure
that adequate baseline data are available for comparison to monitoring data after a remedial action and
that adequate background data are available, including any continuing off-site contaminant contributions.
Remedial action monitoring includes both construction/operational monitoring and monitoring intended
to measure whether cleanup levels and remedial action objectives have been met. After completion of the
remedial action, long-term monitoring is important to assess potential re-contamination, to evaluate
continued containment of buried or capped contaminants, and to monitor dredging residuals and on-site
disposal facilities. Additional monitoring data will help not only to answer site-specific questions but to
contribute to a better understanding of technology performance at the national level.
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Chapter 1: Introduction
1.0
INTRODUCTION
1.1
PURPOSE
This document provides technical and policy guidance for project managers and management
teams making risk management decisions for contaminated sediment sites. It is primarily intended for
federal and state project managers considering remedial response actions or non-time-critical removal
actions under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA),
more commonly known as "Superfund." Technical aspects of the guidance are also intended to assist
project managers addressing sediment contamination under the Resource COIl$ervation and Recovery Act
(RCRA). Many aspects of this guidance may also be useful to other governmental organizations and
potentially responsible parties (pRPs) that are conducting a sediment cleanup under CERCLA, RCRA, or
other environmental statutes, such as the Clean Water Act (CW A) or the Water Resource Development
Act (WRDA). The guidance may also be useful to members of the community and their technical
representatives.
This guidance can be applied to contaminated sediment in a wide variety of aquatic
environments, including rivers, streams, wetlands, ponds, lakes, reservoirs, harbors, estuaries, bays,
intertidal zones, and coastal ocean areas. Sediment in wastewater lagoons, detention/sedimentation
ponds, on-site storage/containment facilities, or roadside ditches is not addressed. This guidance
addresses both in-situ and ex-situ remedies for sediment, including monitored natural recovery (MNR),
in-situ capping, and dredging and excavation. However, the science and practice of sediment remediation
are rapidly evolving, especially in the area of in-situ treatment options. This guidance is not intended to
limit or delay innovative or developing approaches or technologies that may reduce risk from
contaminated sediment.
Consideration of materials deposited in flood plains, whether considered soil or sediment, is an
important factor in reducing risk in aquatic environments. Much of the general approach recommended in
this guidance can be applied to contaminated flood plains, although the technical considerations are
written with aquatic sediment in mind. Control of upland soils and other upland source materials is also
critical to reducing risk in aquatic environments, but in general, existing guidance should be used for
these materials [e.g., the U.S. Environmental Protection Agency's (EPA's) Soil Screening Guidance (U.S.
EPA 1996a)]. However, flood plain soils which may be a source of contamination to surface water or
sediment also require consideration of fate and transport issues.
Following this introductory chapter, the guidance presents sediment-specific issues to consider
during remedial investigations (see Chapter 2) and feasibility studies (see Chapter 3), followed by
chapters concerning the three major remedies for sediment management (see Chapter 4, Monitored
Natural Recovery; Chapter 5, In-Situ Capping; and Chapter 6, Dredging and Excavation). The guidance
then presents information on selecting sediment remedies (see Chapter 7); and on monitoring sediment
sites (see Chapter 8). Although some issues concerning site characterization and risk are discussed early
in the guidance, the emphasis of the guidance is on evaluating alternatives (e.g., the feasibility study stage
of the Superfund process) and remedy selection.
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Chapter 1: Introduction
1.2
CONTAMINATED SEDIMENT
For the purposes of this guidance, contaminated sediment is soil, sand, organic matter, or other
minerals that accumulate on the bottom of a water body and contain toxic or hazardous materials at levels
that may adversely affect human health or the environment (U.S. EP A 1998a). Contaminants adsorbed to
soil or in other forms may wash from land, be deposited from air, erode from aquatic banks or beds, or
form from the underwater breakdown or buildup of minerals (U.S. EPA 1998a). Contaminated sediment
may be present in wetlands, streams, rivers, lakes, reservoirs, harbors, along ocean margins, or in other
water bodies. In this guidance, "water body" generally includes all of these environments. Some
contaminants have both anthropogenic, or man-made, sources and natural sources (e.g., many metals and
some organic compounds). This guidance addresses management of contaminants present above
naturally-occurring levels that may cause an unacceptable risk to humans or to ecological receptors.
Examples of primary and secondary sources of contaminants in sediment are included in
Highlight 1-1.
. .
.. ,-,'"'''''''''''''''''''''''''''' ,',.....,""""""""'''''''''''''''''''' ....... ............................................... d.
[[[-..............................."[[[
.i!~:~!~~ht.~B1;~9m~!m!~99ril.91P~~~m!~~~~.!~:~~~~aw!~
n'",
.......
Direct pipeline or outfall discharges into a water body from industrial facilities, waste water treatment
plants, storm water discharges, or combined sewer overflows
Chemical spills into a water body
Surface runoff or erosion of soil from flood plains and other contaminated sources on land, such as waste
dumps, chemical storage facilities, mines and mine waste piles, and agricultural or urban areas
Air emissions from power plants, incinerators, pesticide applications, or other sources, that may be
transferred to a water body through precipitation or direct deposition
Up welling or seepage of contaminated ground water or non-aqueous phase liquids (NAPL) into a water
body
Direct disposal from docked and dry-docked ships, or release of contaminants from in-water structures
and over-water structures or ship maintenance
Organic contaminants in sediment typically adsorb to fine sediment particles and exist in the pore
water between sediment particles. Metals also adsorb to sediment and may bind to sulfides in the
sediment. The relative proportion of contaminants between sediment and pore water depends on the type
of contaminant and the physical and chemical properties of the sediment and water. Pore water in
sediment generally is interconnected with both surface water and ground water, although the degree of
interconnection may change from place to place and with flow changes in ground water and surface
water.
Many contaminants persist for years or decades because the contaminant does not degrade or
degrades very slowly in the aquatic environment. Contaminants sorbed to sediment normally develop an
equilibrium with the dissolved fraction in the pore water. Also, contaminants may dissolve back into
surface water, to be taken up by fish and other aquatic organisms. Some bottom-dwelling organisms
ingest contaminated sediment, and in shallow water environments, humans may also come into direct

-------
Chupter 1: Introduction
because of direct toxicity. Although some metals do accumulate in biota (i.e., bioaccumulate), generally
they do not significantly increase in concentration as they are passed up the food chain (i.e., biomagnify).
Others, called persistent bioaccumulative toxics (PBTs) [e.g., polychlorinated biphenyls (PCBs),
pesticides, and methyl mercury] are of concern primarily because they may both bioaccumulate and
biomagnify. Concentrations ofPBTs in fish may endanger humans and wildlife that eat fish. Women of
childbearing age, young children, people that derive much of their diet from fish and shellfish, and people
with impaired immune systems may be especially at risk.
In 2004, the EP A released The Updated Report on the Incidence and Severity of Sediment
Contamination in Surface Waters of the United States (U.S. EPA 2004a). This report identifies locations
where sediment contamination could be associated with probable or possible adverse effects to aquatic
life and/or human health; these locations are in all regions of the country (U.S. EP A 2004a). States have
issued approximately 2,800 advisories limiting consumption offish and wildlife, which cover about 33
percent of the nation's total lake acreage and 15 percent of the nation's totalriver miles, in addition to
100 percent of the Great Lakes, in part due to sediment contamination (U.S. EPA 2003a). In addition,
contaminated sediment has significantly impaired the navigational and recreational uses of rivers and
harbors in the U.S. Navigational dredging is not currently being performed in many harbors and
waterways because of the concern for impacts of dredging on water quality, liability to those doing the
dredging, and disposal options for the contaminated dredged material [National Research Council (NRC
1997 and 2001)]. .
As of 2001, the Superfund program had decided to take an action to address sediment at
approximately 140 sites (U.S. EPA 200la). The remedies for more than 65 sites are large enough that
they are being tracked at the national level [see the Office of Superfund Remediation and Technology
Innovation's (OSRTI's) Contaminated Sediments in Superfund Web site at
.httv:/lwww.cDa.gOv/suDclfundJresources/sedimel1t/sites.htm] These sites include a wide variety of
contaminants, as presented in Highlight 1-2.
Many aspects of the cleanup process may be more complex at sediment sites versus sites with soil
or ground water contamination alone. Some potential complicating factors are listed in Highlight 1-3.
For these and other reasons as presented in this guidance a team of experts is frequently needed to advise
the project manager. .
1.3
RISK MANAGEMENT PRINCIPLES AND REMEDIAL APPROACHES
Office of Solid Waste and Emergency Response (OSWER) Directive 9285.6-08, Principles for
Managing Contaminated Sediment Risks at Hazardous Waste Sites (U.S. EPA 2002a, attached as
Appendix A to this guidance), presents eleven risk management principles that help project managers
make scientifically sound and nationally consistent risk management decisions at contaminated sediment
sites. Project managers should carefully consider these principles when planning and conducting site
investigations, involving the affected parties, and selecting and implementing a response. Although the
directive applies to sediment sites addressed under CERCLA or RCRA, its implementation at particular
sites should be tailored to the size and complexity of the site, to the magnitude of site risks, and to the
type of action contemplated.
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1-3

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Chapter 1: Introduction
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Sediment sites may have a large number of sources, some of which can be ongoing and difficult to
control
The sediment environment is usually dynamic, and understanding the effect of natural forces and man-
made events on sediment movement and stability, and contaminant transport, can be difficult
Cleanup work in an aquatic environment is frequently difficult from an engineering perspective and may
be more costly than other media
Contamination is often diffuse and the sites large and diverse (e.g., mixed use, numerous property
owners)
Many sediment sites contain ecologically valuable resources or legislatively protected species or habitats

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Chapter 1: Introduction
The eleven risk management principles should be applied within the framework of the EP A' s
existing statutory and regulatory requirements, such as the National Oil and Hazardous Substances
Pollution Contingency Plan's (NCP's) nine remedy selection criteria (Title 40 Code of Federal
Regulations (40 CFR) ~300.430(c)). The eleven principles are listed in Highlight 1-4 and are
incorporated throughout this guidance. EPA's OSWER Directive 9285.6-11, supplements the eleven
principles directive cited above by describing how the OSRTI Sediment Team and National Remedy
Review Board are involved at large sediment sites (U.S. EPA 2004b). Copies of both directives can be
found on the Superfund Web site at httn://www.cpa.gOv/suDcrfundJresources/sedimentJdocumcnts.htm.
... n. .......','''''''''''''' ...-,'...'"'''''''''''' -,........,...................... ",.................... """.....".............., '.""" ..............
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1
2.
3.
4.
5.
6.
7.
8.
1.3.1
Control sources early
Involve the community early and often
Coordinate with states, local governments, tribes, and natural resource trustees
Develop and refine a conceptual site model that considers sediment stability
Use an iterative approach in a risk-based framework
Carefully evaluate the assumptions and uncertainties associated with site characterization data and site
models
Select site-specific, project-specific, and sediment-specific risk management approaches that will achieve
risk-based 90als
Ensure that sediment cleanup levels are clearly tied to risk management goals
9.
Maximize the effectiveness of institutional controls and recognize their limitations
10.
Design remedies to minimize short-term risks while achieving long-term protection
11
Monitor during and after sediment remediation to assess and document remedy effectiveness
Source: U.S. EPA 2002a
Remedial Approaches

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Chapter 1: Introduction
. . ..
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Dredging:
.
Single-layer granular caps
.
Hydraulic, mechanical, or combination/hybrid
dredging
.
Multi-layer granular caps
.
Treatment of dredged sediment and/or
removed water
.
Combination granular/geotextile caps
.
Disposal of dredged sediment or treatment
residuals in upland landfill, confined disposal
facility, or other placement
Monitored Natural Recovery:
.
Physical processes
.
Backfill of dredged area, as needed or
appropriate
.
Chemical processes
.
Biological processes
Excavation:
Hybrid Approaches:
.
Water diversion or dewatering
.
Thin layer placement of sand or other material
to enhance recovery from natural deposition
.
Treatment of excavated sediment
.
Disposal of excavated sediment or treatment
'residuals in upland landfill, confined disposal
facility, or other placement
Institutional Controls:
.
Fish consumption advisories
.
Backfill of excavated area, as needed or
appropriate
.
Commercial fishing bans
.
Waterway or land use restrictions (e.g., no
anchor or no wake zones; limitations on
navigational dredging)
.
Dam or other structure maintenance
agreements
In-situ Treatment (under development):
.
Reactive caps
.
Additives/enhanced biodegradation
1.3.2
Urban Revitalization and Reuse
Revitalization of urban areas and returning land and water bodies to productive use have become
increasingly important to the EP A's hazardous waste programs in recent years. Sediment sites may

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Chapter 1: Introduction
and other water bodies. This may involve reviewing local land use plans and identifying potential
partners such as land owners, elected officials, and local land and water planning and development
agencies. It may lead to opportunities to consider remedies that take into account the views of local
stakeholders, land owners, and land use planners. For example, it may be possible to locate disposal
structures or rail lines in areas that maximize future reuse. Beneficial reuse of dredged material also may
present an opportunity for urban revitalization.
1.4
DECISION-MAKING PROCESS
Decision making at sediment sites follows somewhat different processes depending on the scope
of the problem, the entity conducting the work, and the legal authority under which it is conducted.
While meeting all legal and regulatory requirements, it is the intent of the Agency to allow project
managers the flexibility needed to make the most appropriate decisions at sediment sites.
1.4.1
Decision Process Framework
Remedial actions taken under CERCLA generally follow the Superfund remedial response
process shown in Highlight 1-6, taken from A Guide to Preparing Superfund Proposed Plans, Records of
Decision, and Other Remedy Selection Decision Documents, also referred to as the "ROD Guidance"
(U.S. EPA 1999a). See the ROD Guidance for detailed descriptions of each stage of the process.
Corrective actions under RCRA generally follow the RCRA remedial process laid out in the May 1, 1996
Advanced Notice of Proposed Rulemaking [(ANPR), 61 FR 19447].
A general decision-making framework for sediment sites, A Framework for Evaluating and
Managing Contaminated Sediment Sites (U.S. EP A et al. 2004, in prep.) is being developed by a team
including representatives of the EPA, the U.S. Army Corps of Engineers (USACE), the U.S. Navy, and
the National Oceanic and Atmospheric Administration (NOAA). This risk-based framework is being
designed to provide an outline of activities and processes that should generally be considered when
assessing and managing contaminated sediment sites. The joint-agency framework would not supersede
any program-specific guidance, but is being designed to be used in conjunction with program-specific
guidance. Highlight 1-7 presents the general outline of this framework.
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1-7

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Chapter 1: Introduction
. .
....
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Process
Pre-Remedial Process
-Preliminary Assessment
-Site Investigation Inspection
-Hazard Ranking System Evaluation
-National Priorities List Listing
Remediallnvestigation/Feasibility Study (RI/FS)
-Scoping the RI/FS
-Site Characterization
-Baseline Risk
Assessment
-Treatability
Studies
-Development
and Screening
of Altematives
-Detailed
An alys is of
Altematives
Remedy Selection Process
Identification of Preferred Altemative
Proposed Plan
Public Comment
Remedy Selection
Record of Decision (ROD)
Remedy Implementation
-Remedial Design
-Remedial Action
Long-Term Remedy Maintenance
-Operation and Maintenance
-5- Year Reviews
Adapted from: U.S. EPA 1999a
January 2005 Draft, Peer Review Document
Activities
Preliminary identification of site hazards and evaluation of
the need for action under Superfund remedial program
Gather information sufficient to support an informed risk
management decision regarding which remedy appears to
be the most appropriate for a given s~e
Make initial identification of Preferred Alternative based
upon preliminary balancing of tradeoffs among altematives
using the nine NCP criteria
Present Preferred Altemative
Minimum 30-day public comment period held on the
Proposed Plan, RI/FS, and other contents of the
Administrative Record file
Make final determination on remedy
Certify that the remedy complies with CERCLA, outline the
technical goals of the remedy, provide background
information on the s~e, summarize the analysis of
altematives, and explain the rationale for the remedy
selected
Design and construct remedy using information contained
in the ROD and other relevant documents. Write
Explanation of Significant Differences (ESDs) or ROD
Amendments (if appropriate)
Operate and maintain the remedy and ensure
protectiveness through 5-year reviews if contamination
remains
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-------
Chapter 1: Introducdon
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Site
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Data CoDectlon
----,
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Characterization
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January 2005 Draft, Peer Review Document
~
~
~

i
~
1-9

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Chapter 1: Introduction
In the report, A Risk-Management Strategy for PCB-Contaminated Sediments (NRC 2001), the
NRC recommended the use of the iterative decision-making approach shown in Highlight 1-8, adapted
from The PresidentiaVCongressional Commission on Risk Assessment and Risk Management. EP A
project managers should use this approach within the context of EP A's existing remedial process
(Highlight 1-6). The NRC approach emphasizes the unique importance of community involvement
throughout the decision-making process. This approach also emphasizes the usefulness of iteration if new
information becomes available that changes the nature ~r understanding of the problem. It is not
intended, however, to represent an endless loop. As noted by the NRC (2001): "The use of the NRC
approach should not be used to delay a decision at a site if sufficient information is available to make an
informed decision. Particularly in situations where there are immediate risks to human health or the
ecosystem, waiting until more information is gathered may result in more harm than making a preliminary
decision in the absence of a complete set of information."
1.4.2
Technical Support
In 2002, EP A established the Contaminated Sediments Technical Advisory Group (CST AG) to
monitor the progress of, and provide advice regarding, a number of large, complex, or controversial
contaminated sediment Superfund sites. For most sites, the group meets with the site team several times
throughout the site investigation, response selection, and action implementation processes. Involving
CST AG at each major phase of a project provides additional technical support to the project team and
ensures consistency with EP A's national sediment policies. General information about CST AG and site-
specific recommendations and responses are available at
http://www.cpa.goy!supcrfund/rcsourccs!scdimenticstag.htm .
In 2004, EPA established the Superfund Sediment Resource Center (SSRC) to make expert
technical assistance available to EP A project managers of any Superfund sediment site. The SSRC has
the capability of accessing expertise from the EP A's Office of Research and Development, the USACE,
as well as private consultants and academic researchers. Information on how to access the SSRC is
available through OSRTI's Contaminated Sediments in Superfund Web site at
htt;p:/lw\V\v. cpa. gov! superfund/resources/ sediment/ ssrc.htm.
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1-10

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Chapter 1: Introduction
..:..:':i:'I1Is.hi!S:~ti,ii~':Nii~~I":R_~t~h9:~9~P!!ifiR~lmm~~~li~(~mlg~~.f9r:R!~KMI;~~m~h':':'::::::
Source: NRC 2001
1.5
STATE, TRIBAL, AND TRUSTEE INVOLVEMENT
State cleanup agencies and affected Indian tribes or nations at sediment sites or impacted
downstream areas have an important role as co-regulators and/or affected parties and as sources of
essential information at sediment sites. States are the lead agency at some sediment sites, or lead the
cleanup ofland-based source areas or particular operable units within a site. States and tribes are
frequently an indispensable source of historic and current information about water body uses, fish
consumption patterns, ecological habitat, other sources of contamination within a watershed, and other
information useful in characterizing the site and selecting an appropriate remedy. At some sediment sites,
states are also owners of aquatic lands, dams, or flood plains. Where this is the case, states have multiple
roles at the site. At sediment sites, as for all sites, states (and local and tribal governments where
applicable) should be involved early and often in the remedial investigation/feasibility study (RI/FS).
Coordination with the state may be especially helpful in the development of the site conceptual model,
risk assessment, and remediation goals. Additional coordination during Remedial Design!Remedial
Action phases is also very important (e.g., an opportunity to consult during the engineering.design
following remedy selection and on other technical matters related to implementation or monitoring of the
remedy). Additional information on coordinating with states and tribes can be found in OSWER
Directive 9375.3-03P, The Plan to Enhance the Role of States and Tribes in the Superfund Program (U.S.
EPA 1998b), and OSWER Directive 9375.3-06P, Enhancing State and Tribal Role Directive (U.S. EPA
2001b).
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1-11

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Chapter 1: Introduction
Where there is a potential for natural resource injuries and damages associated with sediment
sites, coordination between the remedial and trusteeship roles at the federal, tribal, and state levels is
especially important. Several different federal, state, or tribal natural resource trustees may have an
interest in decisions concerning contaminated sediment sites and should have an opportunity to be
involved throughout the investigation and remedy selection process at sites where they have jurisdiction
and interest. The EP A is required to promptly notify natural resource trustees whenever a release of
hazardous materials, contaminants, or pollutants may injure natural resources (CERCLA ~104 (b)(2».
Trustees may include federal natural resource trustee agencies, such as the U.S. Department of the Interior
(DOl), NOAA, U.S. Department of Agriculture (USDA) Forest Service, U.S. Department of Defense
(DoD), or U.S. Department of Energy (DOE). State agencies and federally recognized tribes may also be
natural resource trustees. Where NOAA is the natural resource trustee, project managers should contact
the Coastal Resource Coordinators (CRCs) who are assigned to each EPA region (except Regions 7 and
8, where there are no NOAA trust resources). These CRCs are also designated natural resource trustee
representatives for marine resources, including migratory fish.
Interests and data needs of the trustees and the EP A may be similar. When trustees are involved,
project managers should consult them early in the RIfFS process regarding potential contaminant
migration pathways, ecological receptors, and characteristics of the water body and watershed. Sharing
information early with federal, tribal, and state trustees (rather than bringing them in later in the process)
often leads to better protection of human health and the environment. Information on coordinating with
trustees is found in EP A's ECO Update: The Role of Natural Resource Trustees in the Superfund Process
(U.S. EP A 1992a), in OSWER Directive 9200.4-22A, CERCLA Coordination with Natural Resource
Trustees (U. S. EP A 1997a), and in OSWER Directive 9285.7 -28P, Ecological Risk Assessment and Risk
Management Principles for Superfund Sites (U. S. EP A 1 999b ).
1.6
COMMUNITY AND OTHER STAKEHOLDER INVOLVEMENT
Communication and outreach with the community and other stakeholders can pose unique
challenges at sediment sites, especially at large sites on publically-used water bodies. Community
Involvement Coordinators often have a critical role as part of the project team at these sites. Sediment
sites that span large areas may present barriers to communicating effectively with different communities,
local governments, and the private sector along the water body. People who live, work, and play adjacent
to water bodies that contain contaminated sediment should receive accurate information about the safety
of their activities, and be provided opportunities for involvement in the EPA's decision-making process
for sediment cleanup. Community members may have a wide variety of needs and wishes for current and
future uses of the water body. Highlights 1-9 and 1-10 list some of the common community concerns
about contaminated sediment and risk reduction methods for sediment. These lists are compiled from
information provided by Superfund project managers and by the NRC (2001). Project managers should
be aware of these potential concerns and others specific to their sites.
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1-12

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Chapter 1: Introduction
......
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Human health impacts from eating fish/shellfish, wading, and swimming
..
Ecological impacts on wildlife and aquatic species
Loss of recreational and subsistence fishing opportunities
Loss of recreational swimming and boating opportunities
Economic effects of loss of fisheries
Loss of traditional cultural practices by tribes and others
Economic effects on tourism
Economic effects on development, reduction in property values, or property transferability
Concern whether all contamination sources have been identified
Increased costs of drinking water treatment, other effects on drinking water, and other water uses
Loss or increased cost of commercial navigation
............. ..... ............. ....... ....... ','" ................. .....................
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.
Long time-frame for
recovery
.
Ongoing human and
ecological exposure during
recovery period
.
Doubts about
effectiveness/spreading of
contamination due to
flooding/other disturbance
.
Extended loss of
resources and uses
.
Perception of "do nothing"
remedy
.
Property value/
transferability concerns
with leaving significant
contamination in place
January 2005 Draft, Peer RevieW Document
.
Increased truck or rail traffic . Increased truck or rail traffic 
Loss of resource/harvesting . Noise, emissions, and lights at
opportunities  treatment and disposal facilities
Increased flooding . Siting of new disposal facilities
Disturbance of aquatic habitat . Loss of capacity at existing 
  disposal facilities 
Cap material source issues   
 . Loss of privacy during 
Loss of boat anchoring access  construction 
Doubts about effectiveness due . Infrastructure needs on
to cap erosion. disruption, or  adjacent land 
contaminant migration through   
cap . Recreation and tourism impacts
Loss of privacy during . Access to private property .
constructio n   
 . Property values near dredging,
Recreation and tourism impacts  treatment and disposal facilities
during construction   

-------
Chapter 1: Introduction
Existing community involvement and sediment guidance from EP A and elsewhere offer some
guidelines for involving the community in meeting these and other concerns, as identified in Highlight I-
lL
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EPA Office of Solid Waste and Emergency Response on Community Involvement (available at
http://www.spa.Qov/supsrfund/action/cornmunitylindsx.htm ):
Early and Meaningful Community Involvement (U.S. EPA 2001 c)
Superfund Community Involvement Toolkit (U.S. EPA 2003b)
Community Advisory Group Toolkit for EPA Staff (U.S. EPA 1997b)
The Model Plan for Public Participation, National Environmental Justice Advisory Council (U.S. EPA
1996b)
Incorporating Citizen Concems into Superfund Decision Making (U.S. EPA 2001 d)
RCRA Community Involvement Guidance (available at
.http://VMW.epa.Qov/epaoswerlhazvvasteica/resource/Quidance.h1m see list under "Public
I nvolvementlCommunication "):
RCRA Public Participation Manual
RCRA Expanded Public Participation Rule (60 FR 63417-34)
RCRA Corrective Action Workshop Communication Tools
Office of Water on Communication of Fish Consumption Risks and Surveys (available at
http://www.spa.Qov/ostlfish):
Guidance for Conducting Fish and Wildlife Consumption Surveys (U.S. EPA 1998c)
National Risk Communication Conference Held in Conjunction with the Annual National Forum on
Contaminants in Fish (May 6-8, 2001, conference proceedings available at
http://wNw.epa.Qov/waterscience/fish/proceedinQs.html)
National Research Council:
A Risk-Management Strategy for PCB-Contaminated Sediments, Chapter 4, Community Involvement
(NRC 2001)
. Considering existing EP A guidance, and advice from the NRC and others, the three points below
highlight some of the most critical aspects of community involvement at sediment sites.
Point 1. Involve the CommunitY and Other Stakeholders Earlv and Often
In addition to the requirements and recommendations regarding stakeholder involvement
available in CERCLA ~117 and the NCP, one of EPA's eleven principles for managing risk of
contaminated sediment is to involve the community early and often. This is an important principle in

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Chapter 1: Introduction
mission of the Superfund and RCRA community involvement programs is to advocate and strengthen
early and meaningful community participation during Superfund cleanups. Planning for community
involvement at contaminated sediment sites should begin as early as the site discovery and site assessment
phase and continue throughout the entire Superfund process. As noted by the NRC (2001): "Community
involvement will be more effective and more satisfactory to the community if the community is able to
participate in or directly contribute to the decision-making process. Passive feedback about decisions
already made by others is not what is referred to as community or stakeholder involvement." Early
involvement allows necessary input from communities and other stakeholders and facilitates more
comprehensive identification of issues and concerns early in the site management process.
Early community involvement enables EP A to learn what stakeholders, especially community
members, think are important exposure pathways of the contamination and of potential response options.
Available materials about community involvement in the risk assessment process include A Community
Guide to Superfund Risk Assessment- What's it All about and How Can You Help? (U.S. EPA 1999c).
Although the regulators have the responsibility to make the fmal cleanup decision at CERCLA and
RCRA sites, early and frequent community involvement helps the regulators understand differing views
and allows the regulators to factor these views into their decision.
Point 2. Build an Effective Working Relationship with the CommunitY and Other Stakeholders
In addition to the requirements and recommendations regarding public outreach available in
CERCLA ~ 117 and the NCP, building partnerships with key community groups, the private sector, and
other interested parties is critical to implementing a successful outreach program. Involving communities
by fostering and maintaining relationships can lead to better site decisions and faster cleanups. Writing
specifically about PCB-contaminated sites, but with application to all sediment sites, the NRC (2001)
report recommended that: "Community involvement at PCB-contaminated sediment sites should include
representatives of all those who are potentially at risk due to contamination, although special attention
should be given to those most at risk."
Participants at EP A's 2001 Forum on Managing Contaminated Sediments at Hazardous Waste
Sites (U.S. EPA 200le) offered the following ideas, among others, for building effective working
relationships with communities and other stakeholders at sediment sites. Project managers should
consider the following advice as they formulate their outreach plans:
Create realistic expectations up front for both public involvement and sediment cleanup;
Where possible, instead of asking for extra meetings, ask for time at existing community
meetings;
Use store-front on-site offices for public information when possible;
Be aware of tribal cultural and historic sites, not all of which are registered or are on
tribal land; .
Minimize jargon when speaking and writing for the public;
Use independent facilitators for public meetings when needed;
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Chapter 1: Introduction
Include broad representation of the community;
Look for areas where you can act on input from the community; and
Encourage continuity of membership as much as possible.
A complete list of forum presentation materials is available at
http://v.,rww.epa.gov/suDerflind/new/sedforum.hlm.
Point 3. Provide the Community with the Resources They Need to Participate Effectively in the
Decision-Making Process
In addition to the requirements and recommendations regarding public outreach available in
CERCLA ~117 and the NCP, project managers should ensure that community members have access to
the tools and information they need to participate throughout the cleanup process. Educational materials
should be accessible, culturally sensitive, relevant, timely, and translated when necessary. One potential
resource is a video prepared by EPA's Superfund office in 2003, to explain to communities the general
remedial options for sediment.
Contaminated sediment sites often involve difficult technical issues. It is especially important to
give community members opportunities to gain the technical knowledge necessary to become informed
participants. Project managers should provide technical information to communities in formats that are
accessible and understandable. The EP A has a number of resources available to help make large volumes
of complex data more easily understandable. These resources are often valuable communication tools not
only with the community, but also within the EPA and between cooperating Agencies. An example
includes the Region 5 Fully Integrated Environmental Location Decision Support (FIELDS) capabilities.
FIELDS began as an effort to more effectively solve contaminated sediment problems in and around the
Great Lakes and is applied in other regions as well. Information about FIELDS is available at
http://www. cpa. gov/re~ion5fields.
Information about Superfund community services is available at
ht1D://www.eDa.gOv/slIverfund/action/comnnmitv/index.htm.This Web site provides information on
Community Advisory Groups (CAGs), EPA's Technical Assistance Grant (TAG) program, and the
Technical Outreach Services for Communities (TOSC) program. The TOSC program uses university
educational and technical resources to help community groups understand the technical issues involving
hazardous waste sites in their communities. The Superfund statute provides for only one TAG per site.
At very large sites with diverse community interests, communities may choose to form a coalition and
apply for grant funding as one entity. The coalition would need to function as a nonprofit corporation for
the purpose of participating in decision making at the site. Individual organizations may choose to
appoint representatives to a steering committee that decides how TAG funds should be allocated, and
defines the statement of work for the grant. The coalition group may hire a grant administrator to process
reimbursement requests to the EP A and to ensure consistent management of the grant. In some cases,
EPA regional office award officials may waive a group's $50,000 limit if site characteristics indicate
additional funds are necessary due to the nature or volume of site-related information.
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Chapter 2: Remedial IIlvestiKation Considerations
2.0
REMEDIAL INVESTIGATION CONSIDERATIONS
The main purpose of investigating contaminated sediment, as with other media, generally is to
detennine the nature and extent of contamination in order to detennine if there are unacceptable risks that
warrant a response and, if so, to evaluate potential remedies. Investigations may be conducted by a
number of different parties under a number of different legal authorities. Most of this chapter presents
general infonnation of potential use to any investigator. However, the language and program-specific
references are drawn from the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) program, and at times, from the Resource Conservation and Recovery Act (RCRA) program.
Under CERCLA, the investigation process is known as a "Remedial Investigation" (Rl). Under
RCRA, the investigation process is known as a "RCRA Facility Investigation." The Rl process is
described in the U.S. Environmental Protection Agency's (EPA's) Guidancefor Conducting Remedial
Investigations and Feasibility Studies under CERCLA, also referred to as the "Rl/FS Guidance" (U.S.
EPA 1988a). The process in a RCRA corrective action is best described in Office of Solid Waste and
Emergency Response (OSWER) Directive 9902.3-2A, RCRA Corrective Action Plan (U.S. EPA 1994a),
and the May 1, 1996 Advanced Notice of Proposed Rulemaking [(ANPR) 61 FR 19447]. This chapter
supplements these existing guidances by offering brief sediment-specific guidance about site
characterization, risk assessment, and other investigation issues unique to sediment. More detailed.
guidance concerning site characterization is beyond the scope of this document, but may be developed as
needed in the future.
2.1
SITE CHARACTERIZATION
The site characterization process for a contaminated sediment site should allow the project
manager to accomplish the following general goals, at a scale and complexity appropriate to the site:
Identify and quantify the contaminants present in sediment, surface water, biota, flood
plain soils, and in some cases, ground water;
Understand the vertical and horizontal distribution of the contaminants within the
sediment and flood plains;
Identify the sources of historical contamination and quantify any continuing sources;
.
Understand the geomorphological setting and processes (e.g., resuspension, transport,
deposition, weathering) affecting the stability of sediment;
Understand the key chemical, and biological processes affecting the fate, transport, and
bioavailability of contaminants;
Identify the complete or potentially complete human and ecological exposure pathways
for the contaminants;
.
Identify current and potential future human and ecological risks posed by the
contaminants;
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Chapter 2: Remedial Investigation Considerations
Collect data necessary to evaluate the potential effectiveness of natural recovery, in-situ
capping, sediment removal, and promising innovative technologies; and
.
Provide a baseline of data that can be used to monitor remedy effectiveness in all
appropriate media (generally sediment, water, and biota).
The project manager, in consultation with technical experts and stakeholders, should develop site-
specific investigation goals that are of an appropriate scope and complexity for the site. Systematic
planning, dynamic work strategies, and, where appropriate, real-time measurement technologies may be
especially needed at sediment sites. Combined, these three strategies are known as the "triad approach,"
described on EP A's Innovative Technologies Web site at http://\vww.c1uin.or!dtriad.:.This approach
attempts to summarize the best current practices in site characterization, in order to collect the "right"
data, improve confidence in results, and save cost.
Data collection during the remedial investigation frequently has multiple uses, including human
health and ecological risk assessment, identification of potential early actions, and remedy decision-
making. It is important to involve all data users (e.g., risk assessors, modelers, as well as quality
assurance/quality control (QNQC) experts) early throughout data collection.
Data should be of a type, quantity, and quality to meet the objectives of the project. The EP A's
data quality objective (DQO) process is one method to achieve this, as described below. Where other
agencies (e.g., natural resource trustee agencies, state remediation agencies, and health departments) have
an interest at the site, they should be consulted concerning decisions about DQOs so that collected data
can serve multiple purposes, if possible. In addition, the community and other stakeholders (e.g., local
governments and potentially responsible parties) should be consulted in these decision as appropriate.
2.1.1
Data Quality Objectives
The EP A' s DQO process is intended to help project managers collect data of the right type,
quality, and quantity to support site decisions. As described in Guidance for the Data Quality Objective
Process (U.S. EPA 2000a), seven steps generally guide the process. The initial steps help assure that only
data important to the decisions that need to be made are collected. The seven DQO steps include the
following, with an example written in the context of a risk assessment:
1.
State the problem. Example: There is current exposure of humans to site-related
contaminants through eating fish.
2.
IdentitV the decision. Example: Is the exposure causing an unacceptable risk?
3.
IdentifY inouts to the decision. Examples: What are the appropriate fish species, receptor
groups, and consumption rates to evaluate? What existing data are available and what
must be collected? What is the toxicity of the contaminants to all receptor groups?
4.
Define boundaries of studv. Example: For purposes of the human health risk assessment,
should the water body and the human population each be considered as a whole or in
subparts?
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Chapter 2: Remedial InvestiKation Considerations
5.
Develoo a decision rule. Example: If exposure at the upper 95 percent confidence limit
for fish consumption of the recreational fisher population to the mean contaminant
concentration of anyone of the three most popular fish species exceeds a cancer risk
range of 10-6 to 10-4 or a Hazard Index of 1, risk will be considered unacceptable.
6.
SoecifV limits on decision errors. Example: What levels of uncertainty are acceptable for
this decision, considering both false positive and false negative errors?
7.
Optimize the desim (or obtaininf! data. Example: What is the most resource-effective
fish sampling and analysis design for generating data that will meet the data quality
objectives?
Similar hypotheses could be established for evaluating each approach being considered for the
site, and for evaluating the effectiveness of the selected approach. The way in which the process is
followed may vary depending on the decision to be made, from a thought process to a rigorous statistical
analysis. Additional guidance provided in EP A Requirements for Quality Assurance Project Plans
[(QAPPs), U.S. EP A 2001f) describes how DQOs are incorporated into QAPPs.
2.1.2
Types of Data
The types of data the project manager should collect are determined mostly by information
needed to develop the conceptual site model, conduct the human health and ecological risk assessments,
evaluate potential remedies, document baseline conditions prior to implementation of the remedy, and
design and implement the selected remedy.
Highlight 2-1 lists some general types of physical, chemical, and biological data that a project
manager should consider collecting when characterizing a sediment site. It is frequently important to
understand the historical changes in some of these characteristics (e. g., water body bathymetry or
contaminant distributions in surface and subsurface sediment, water, and biota). It may also be important
to understand how characteristics change seasonally, and under various flow and temperature conditions.
The relative importance of these types of data variabilities are dependent on the site. While sediment sites
typically demand more types of data for effective characterization than other types of sites, the type and
quantity of data required should be geared to the complexity of the site and the weight of the decision. In
addition, the data acquisition process should not prevent early action to reduce risk when appropriate.
Site characterization should include collection of sufficient baseline data to be used to compare to
monitoring data collected during and following implementation of the remedy in a statistically defensible
manner. Additional sampling could be needed during remedial design, however, to establish reliable
baseline data for the monitoring program. Chapter 8, Remedial Action and Long-Term Monitoring,
provides a discussion of effective monitoring programs, much of which is also useful during the remedial
investigation.
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Chapter 2: Remedial Investigation Considerations
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Flood frequencies, annual
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Surface water/ground
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January 2005 Draft, Peer Review Document
.
Ground water flow regime
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Sediment toxicity
.
Extent of
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harvesting of fish/shellfish
for human consumption
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.
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.
Habitat stressor analyses
.
Contaminant bioavailability
.
Pathological condition, such

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Chapter 2: Remedial Investi/{ation Considerations
Polvchlorinated Biohenv 1 (PCB) Data
At this time, polychlorinated biphenyls (PCBs) are among the most common contaminant of
concern at contaminated sediment sites. The tenn "PCB" refers to a group of 209 different chemicals
sharing a similar structure of chlorinated biphenyl rings. The 209 PCB fonns are called PCB congeners.
Aroc1ors are commercial mixtures of PCB congeners, with each Aroc1or made up of a certain percentage
of chlorine. For example, Aroclor 1242 contains 42 percent chlorine. Release of an Aroclor into the
environment may result in a change in its congener composition. As also discussed in Chapter 8,
Remedial Action and Long-Tenn Monitoring, for sediment sites contaminated with PCBs, the National
Research Council (NRC) states that total PCB. concentrations determined by analyzing PCBs as Aroclors
are prone to error, because the distribution of PCB congeners in Aroclors is altered considerably by
physical, chemical, and biological processes after release into the environment (NRC 2001). EPA's
Office of Water Guidance for Assessing Chemical Contaminant Datafor Use in Fish Advisories, Volume
1, Fish Sampling and Analysis, Third Edition (U.S. EPA 2000b), also notes that individual PCB
congeners may be preferentially enhanced in environmental media and in biota.
In 1996, EP A released its PCB Cancer Dose-Response Assessment and Application to
Environmental Mixtures (U.S. EPA, 1996a, also referred to as the "PCB Cancer Reassessment"). The
PCB Cancer Reassessment presented a new approach for assessing cancer risk from exposure to PCBs
based on exposure pathways of concern and congener chlorination levels. The PCB Cancer Reassessment
also acknowledged the importance of evaluating risk from dioxin-like PCB congeners in addition to risk
from total PCBs. Dioxin-like PCB congeners are structurally similar to 2,3,7,8-tetrachlorodibenzo-p-
dioxin (fCDD, or dioxin) and recent studies have found that these congeners exhibit similar toxic effects
to dioxin (though they display lesser potency). Toxic Equivalency Factors (TEFs) relating the potency of
these PCB congeners to the potency of dioxin were ftrst published by the W orId Health Organization
(WHO) in 1994, and later updated in 1998 (Van den Berg et al. 1998).
Characterizing PCB risk on a congener-speciftc basis allows for an accounting of the differences
in physicochemical, biochemical, and toxicological behavior of the different congeners in type and
magnitude of effects and, therefore, in risk calculations. Although Aroclor analysis can be useful for
initial assessment of PCB concentrations, for risk assessment purposes NRC recommends that PCB sites
should be characterized on the basis of speciftc PCB congeners and the total mixture of congeners found
at each site. EP A currently provides congener-speciftc analyses through its Non-Routine Program under
the Contract Laboratory Program (CLP), but it may, in the future, be available through its CLP routine
analytical services. This service provides for analytical consistency, centralized contract administration,
and sample tracking.
However, to the extent that it is detennined that PCB congener-speciftc data are useful at a site,
the project manager should not assume that this necessarily need be done for all samples collected. At
times, only a subset of samples or sampling events may need congener analysis. Deciding how best to
characterize a PCB site is a complex issue due in part to issues related to dioxin-like PCBs, the lack of
congener-speciftc toxicological data, the need for comparing present and previously-collected data, and
the cost of congener-speciftc analyses. The decision about what method or methods to use for PCB
analysis should be made on a site-speciftc basis. EPA's Superfund program is in the process of
developing guidance on assessing human health risks posed by PCBs in contaminated soil. The guidance
will be found at lillP-://www.elliLgov/superfund/resources/pcb/index.htm. While the focus of the guidance
is on human health risk from soils, the guidance is being designed to provide an analytical framework that
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Chapter 2: Remedial Investil(ation Considerations
can be used for selecting appropriate PCB analytical methods for ecological risks and for various media,
such as soils, sediments, tissue and water. An appendix to the guidance will consist of a compendium of
analytical methods for PCBs.
Metals Data
Currently, metals are also among the most common contaminant of concern at Superfund
sediment sites. Concentrations of metals in sediment alone may not be good measures of metal toxicity.
Because the bioavailablity of metals is frequently related to the concentration of sulfides in the sediment,
it is important to analyze both acid volatile sulfides (A VS) and simultaneously extracted metals (SEM) in
sediment with metals contamination. A VS controls the activity and availability of divalent metals in the
pore ratios, and differences between A VS and SEM may be used to predict metal toxicity and availability
in sediment (U.S. EPA 1996a). The A VS-SEM approach can be applied on a molar ratio (not
concentration ratio) basis for copper, cadmium, nickel, lead, zinc, and on a half molar basis for silver.
For chromium, if there is any SEM, it is assumed that the chromium is in the trivalent state and not
bioavailable to cause effects (unlike hexavalent chromium which is bioavailable and toxic). The
equilibrium-partitioning approach using A VS and SEM for predicting metals bioavailability is a useful
tool for understanding the sequestration of selected metals, and research in this area is ongoing.
2.1.3 Background Data
Where site contaminants may also have natural or other anthropoge:o.ic (man-made) non-site-
related sources, it may be important to establish background or reference site data for a site. When doing
so, project managers should consult EPA's Role of Background in the CERCLA Cleanup Program (U.S.
EP A 2002b), the EP A ECO Update - The Role of Screening-Level Risk Assessments and Refining,
Contaminants of Concern in Baseline Ecological RiskAssessments (U.S. EPA 200Ig), and Guidancefor
Comparing Background and Chemical Concentrations in Soil for CERCLA Sites (U.S. EPA 2002c).
Although the latter is written specifically for soil, many of the concepts may be applicable to contaminant
data for sediment and biota. It should be noted that a comprehensive investigation of all background
substances found in the environment usually will not be necessary at CERCLA sites. For example, radon
background samples normally would not be collected at a chemically contaminated site unless radon, or
its precursor was part of the CERCLA release.
Where applicable, project managers should consider continuing atmospheric and other
background contributions to sites in order to adequately understand contaminant sources and establish
realistic risk reduction goals (U.S. EPA 2002b). For baseline risk assessments, EPA recommends an
approach that generally includes the evaluation of the contaminants that exceed protective risk-based
. screening concentrations (RBCs), including contaminants that may have natural or anthropogenic sources
on and around the Superfund site under evaluation. However, when site-specific information
demonstrates that a substance with elevated concentrations above RBCs originated solely from natural
causes (i.e., is a naturally occurring substance and not release-related), that contaminant need not be
carried through the quantitative analysis, but should be discussed in the risk characterization summary .
The purpose here is to communicate potential risks to the public. The presence above RBC level
indicates a potential environmental or health risk, and that information should be discussed at least
qualitatively in the document. If data are available, the contribution of background to site conditions
should be distinguished (U.S. EPA 2002b). This approach ensures a thorough characterization of risks
associated with hazardous substances, pollutants, and contaminants at sites (U.S. EPA 2002b).
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Chapter 2: Remedial Investi/(ation Considerations
For risk management purposes, understanding whether background concentrations are high
relative to the concentrations of released hazardous substances, pollutants, and contaminants may help
risk managers make decisions concerning appropriate remedial actions (U.S. EPA 2002b). Generally,
under CERCLA, cleanup levels are not set at concentrations below natural or anthropogenic background
levels (U.S. EPA 1996a, 1997c, 2000c). If a risk-based remediation goal is below background
concentrations, the cleanup level for that chemical may be established based on background
concentrations.
In cases where area-wide contamination may pose risk, that are not appropriate to address under
CERCLA, EP A may be able to help identify other programs or regulatory authorities that are able to
address the sources of area-wide contamination, particularly anthropogenic sources (U.S. EPA 1996a,
1997c, 2000c). In some cases, as part of a response to address CERCLA releases of hazardous
substances, pollutants, and contaminants, EP A may also address some of the background contamination
that is present on a site due to area-wide contamination.
2.2
CONCEPTUAL SITE MODELS
A conceptual site model generally is a representation of the environmental system and the
physical, chemical, and biological processes that determine the transport of contaminants from sources to
receptors. For sediment sites, perhaps even more so than for other types of sites, the conceptual site
model is an important element for evaluating risk and risk reduction approaches. The initial conceptual
site model can provide the project manager with a simple understanding of the site based on data
available early in the investigation. Essential elements generally include information about contaminant
sources, transport pathways, exposure pathways, and receptors. Summarizing this information in one
place helps in testing assumptions and identifying data gaps and areas of critical uncertainty for additional
investigation. Later, this conceptual model should be modified as additional source, pathway, and
contaminant information is collected. A good conceptual site model is a valuable tool in evaluating the
potential effectiveness of actions to reduce exposure of receptors to contaminants. Natural resource
trustee agencies and other stakeholders may have information about the ecosystem that is important in
developing the conceptual site model and it is recommended that they have input at this stage of the site
investigation. Information gaps may be discovered in development of the conceptual site model that
support collection of new data. Typical elements of a conceptual site model for a sediment site are shown
in Highlight 2-2.
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Chapter 2: Remedial Investigation Considerations
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.....
Sources of Contaminants of Concern:
Exposure Pathways for Humans:
.
Upland soils
Flood plain soils
Surface water
Ground water
Non-aqueous phase liquids and other source
materials
Sediment "hot spots"
Outfalls, including combined sewer outfalls
and storm water runoff outfalls
Atmospheric contaminants
.
Game fish/shellfish ingestion
Dermal uptake from wading, swimming
Water ingestion
Inhalation of volatiles
.
.
.
.
.
.
.
Exposure Pathways for Biota:
.
.
.
Fish/shellfish ingestion
Benthic invertebrate activity
Direct uptake from water
.
.
.
Contaminant Transport Pathways:
Human Receptors:
. Sediment resuspension
. Surface water transport
. Runoff
. Bank erosion
. Ground water advection
. Bioturbation
. Food chain
.
Recreational fishers
Subsistence fishers
Waders/swimme rs/birdwatchers
.
.
Ecological Receptors:
.
Bethiclepibenthic invertebrates
Bottom-dwelling fish
Pelagic fish
Mammals and birds (e.g., mink, otter, heron,
bald eagle)
.
.
.
Project managers may find it useful to develop several conceptual site models that highlight
different aspects of the site. At complex sediment sites, often three conceptual site models are developed,
one for sources, release and media, and one each for human health and ecological receptors. HigWight 2-

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Chapter 2: Remedial Investigation Considerations
.......
.....
.....
.....
.....
....
.....
....
........
.....
.....
. .......
Trophic: Level 3
(Tertiary Consumer)
Trophic: Level 2
(Secondary Consum er)
T ro ph ie Level 1
(Prima,y Consumer)
Primary Producers
Expo sur. M adi.
......
......'.mi,~~!1~h~gt~~~~mpliEB9B~e~9~!~!~MI~~E~q~~~Q:gni~9~~~i]hr_:..
.....
........
,........
Omnivorousf
C .rnivorDUS
V.rtebratas (e.g.,
various fish spaci..,
frogs. turtlesl
.'.'.'.'.'.'.'.".",
~
Sit. Source.
Ground Water
W atarshe d/Floodplain
Atm aspheric Cycling
'.'.'.',",",",'.',",",'.',',','.'.'.','.',',',',',",",'.'.'.'.",',',',','.'."'.".'.'.'.",",",".'
[[[
January 2005 Draft, Peer Review Document
.....
....,
.....
,..,
"..
. ,..,
Atm ospheric Cycling
. .
[[[
Carnivorousl
Piscivorous
Mammals (e,g"
mink, otter, fox,
raccoons)
"..
Cern ivorou s/Piscivorous
Birds (e.g., hawks,
eagle., owls, terns,
huons, pelicans. osprey)
.'.'.'.','.',,',','.',' ,','.""','..'..'.",,,'.','.',
.:.:.:':':':.:':':':.:, ,;.:,:.:.;.:.:,:.;.:.:,;,:,:,:,:.:,:,:.
:::;:::::::::;:;::::::::::::::, :'::::::;:::::;:::::::;:;:::::::;:::::;:::::::;
Omnivorousl
Carnivorous
Invert.brates (e.g.,
crayfish. damselflies,
dragonflies)
Om nivorousl
Carnivorous
Mammals (e,g..
moles, shrews, bals)
Omnivorousl
Carnivorous Birds
(e,g., martins, robins,
woodcock, seagulls,
crows, swallows)
.'.'.'-'.'.'.'.".'.'.'..
......"............
.':::::::;:::::::::::::::::::::::::::::

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Chapter 2: Remedial Investigation Considerations
....
, .. ... . . . . ... .
. ...... ..... . ... . .. .. . ......... ...".....-,....-.."'''''''''' ,............... ..........- ... . .....
....
.....
-,...............
.................
......
.,..". ..
..........
n. .
/~.. ~.

/..."'. -""-,,,,,,,.''''r: .


. . . .' fi . "----~--------'-_:=-==~:::-~.:<: t\r .:'

.P' .' -- .-___~_m_-. ~j
..
Source: Adapted from EPA Region 5, Sheboygan Harbor and River Site
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Chapter 2: Remedial Investigation Considerations
.....
....
....
... ..
.....
.....
.......
.....
.....
...
:::'m!~~!~~~~~t~~~!~B~~:8q~l~m~~I~!~1ml~!"ff9~~I~$:9~::~~~;~:ffl~!m.m~t~~ti.::
......
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.. .....
....
...
...,...
.....
...
n..
. .......
.. ......
- . . . . . . . . . . . .
.........
....
...'...
Primary
Sources
Primary
Release
Secondary
Sources
Secondary
Release
Media
Affected
Exposure
Routes
Receptors
Former
Chlorine Plant
Previous
Discharge to
Creek
S~e Process
Area
Release From
U-Drain
System
Solids Present
From
Discharge
Surface Water
Runoff of
Contaminated
Soils from
Process Area
Creek
Surface
Water!
Sediment
Soil
River
Surface Water!
Sediment
January 2005 Draft, Peer Review Document
Storm Water
Runoff
Infiltration into
Ground Water
River Surface Water!
Sediment!Biota
Infiltration into
Ground Water
Flood Events
Wetlands Waterl
Wetlands Sediment!
Biota
Wetlands Waterl
Wetlands Sediment!
Biota
Ingestion &
Dermal Contact
(Surface Water)
Ingestion &
Dermal Contact
Ingestion &
Dermal Contact
Ingestion &
Dermal Contact
Fisherman
Worker
Biota
Worker
Biota
Fisherman
Worker
Biota
Worker
Biota
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Chapter 2: Re1lU!dial Investigation Considerations
2.3
RISK ASSESSMENT
Consistent with the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), a
human health risk assessment and an ecological risk assessment are performed at all contaminated
sediment sites. In addition to assessing risks due to contaminated sediment, in many cases, risks from
soil, surface water, ground water and air pathways may need to be evaluated as well. Generally, the
human health risk assessment should consider the cancer risks and non-cancer health hazards associated
with ingestion offish and other biota appropriate to the site (e.g., shellfish, ducks); dermal contact with
and incidental ingestion of contaminated sediments; inhalation of volatilized contaminants; swimming
and possible ingestion of river water if it is used as a drinking water supply. Separate analyses should
also consider risks from exposure to floodplains and may include direct contact, ingestion, and exposures
to homegrown crops, beef and dairy products where appropriate. As with all RI data collection efforts,
the scope of the assessments should be tailored to the complexity of the site and how much information is
needed to reach and support a risk management decision. It is important to involve the risk assessors
early in the process to assure that the information collected is appropriate for use in the risk assessment.
Risk assessments are designed to evaluate the potential threat to human health and the
environment in the absence of any remedial action. Generally, they provide the basis for determining
whether remedial action is necessary as well as the framework for developing risk-based remediation
goals. Risk assessments should also provide information which can be used to evaluate risks associated
with implementing various remedial alternatives which may be considered for the site. Detailed guidance
on performing human health risk assessments is provided in a number of documents, most of which are
available on EPA's Web site at http://www.epa.gov/superf1md/programs/risk. The RiskAssessment
Guidance for Superfund, also referred to as "RAGS" (U.S. EP A 1989) provides a basic plan for
developing human health risk assessments. Specific guidance on the standardized planning, reporting,
and review of risk assessments is provided at
htt,p:1 iv.'WW. cpa. gov Isuperful1d/programs/ris kJra gsd/il1dex .htm.
Detailed guidance on performing ecological risk assessments is provided in Ecological Risk
Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessment,
also referred to as "ERAGS" (U.S. EPA 1997d). In addition, OSWER Directive 9285.7-28P, Ecological
RiskAssessment and RiskManagement Principles for Superfund Sites (U.S. EPA 1999b), provides risk
managers with several principles to consider when making ecological risk management decisions. As
stated in the Role of the Ecological Risk Assessment in the Baseline Risk Assessment (U.S. EPA 1994b),
the purpose of the ecological risk assessment is to "1) identify and characterize the current and potential
threats to the environment from a hazardous substance release, 2) evaluate the ecological impacts of
alternative remediation strategies, and 3) establish cleanup-levels in the selected remedy that will protect
those natural resources at risk." .
Although not EP A guidance, the recently released Navy guidance Implementation Guide for
Assessing and Managing Contaminated Sediment at Navy Facilities, provides useful information on
performing human health and ecological risk assessments at contaminated sediment sites [U.S. Naval
Facilities Engineering Command (FEC) 2003].
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Chapter 2: Remedial Investi1(ation Considerations
2.3.1
Screening Risk Assessment
A screening risk assessment typically is performed to identify the contaminants of potential
concern (COPCs) and the portions of a site that may present an unacceptable risk to human health or the
environment. Currently, there are no widely accepted sediment screening values for human health risk
from either direct contact with sediment or for eating fish or shellfish, although research is ongoing. For
floodplain and beach soils, human health soil screening levels may be used. Widely-accepted screening
values do exist for ecological risk from direct toxicity, although, similar to the situation for human health
risk, screening values for risk to wildlife and fish from bioaccumulative contaminants have not yet been
fully developed. Each of these issues is discussed further below. In cases where screening levels do
exist, or may be developed in the future, it is very important for project managers to keep in mind that
screening values are not designed to be used as default cleanup levels and generally should not be used
for that purpose. In addition to their intended purpose, in some cases project managers may also fmd
ecological screening values or human health screening level exposure assumptions useful for evaluating
whether detection levels for sediment analytical work are sufficiently low to be useful for risk assessment.
When evaluating human health risks from direct contact with sediments and from
bioaccumulative contaminants in fish and shellfish, RAGS (U.S. EPA 1989), and other risk guidance
discussed above, should be followed to identify the COPC that may present an unacceptable risk. In
general, if bioaccumulative contaminants are found in biota at levels above site background, they should
not be screened out and should be carried into the baseline risk assessment.
When evaluating human health risk from direct contact with floodplain or beach soils, OSWER
and several regions have soil screening values that may be useful. Human health soil screening levels
(SSLs) for residential and industrial properties are available at
http://www.cpa gov/superfund/resources/soil, which provde a generic approach and exposure assumptions
for evaluation of risks from direct contact with soil.
When screening ecological risk to benthic biota from direct toxicity, project managers should
- consult EPA's Eco-Updates EcoTox Thresholds (U.S. EPA 1996c) and The Role of Screening-Level Risk
Assessment and Refining Contaminants ofConcem in Baseline Ecological Risk Assessments (U.S. EP A
200Ig), which describes the process of screening COPC. The EPA equilibrium-partitioning sediment
benchmarks (ESBs) available at http://www.epa.gov/nheerl/pub1ications/ and the Superfund program's
Ecotox Thresholds (ETs) available at http://\vww.cpa.gov/supcrfundiprograms/riskJcco updt.pdf should
be used as screening values for risk to benthic biota from direct toxicity. Other published sediment
guidelines [e.g., National Oceanic and Atmospheric Administration (NOAA) Screening Quick Reference
Tables (SQuiRTs), http://response.rcstoration.noaa.gov/cprlsedimclltlsQuirtisQuin.html] can also be used
as screening values Table 3-1 in the Navy guidance (U.S. Navy FEC 2003) also provides a list of citations
for ecological screening values for sediment.
When screening ecological risks to terrestrial receptors from contaminated floodplain soils, the
recently released OSWER Directive 9285.7-55, Guidance for Developing Ecological Soil Screening
Levels [(Eco-SSLs), U.S. EPA 2003c, http://www.epa.gov/ecotox/ecosslJl should be used. Eco-SSLs for
some receptors have been developed for aluminum, antimony, barium, beryllium, cadmium, cobalt,
dieldrin, iron, and lead. Screening values for arsenic, chromium, copper, dichlorodiphenyltrichloroethane
(DDT), manganese, polycyclic aromatic hydrocarbons (PAHs), pentachlorophenol, and vanadium are
currently under development.
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Chapter 2: Remedial Investigation Considerations
For ecological risk to wildlife or fish from food chain effects, widely-accepted screening values
have not yet been fully developed. As for the human health risk assessment, ifbioaccumulative
contaminants are found in biota at levels above site background, they generally should not be screened
out and should be carried into the baseline risk assessment for ecological risk as well.
2.3.2
Baseline Risk Assessment
At contaminated sediment sites with bioaccumulative contaminants, the human health exposure
pathway driving the risk is usually ingestion of biota, most commonly the ingestion of fish by recreational
anglers. Depending on the contaminant and the use of the site, however, there can also be significant
risks from direct contact with the sediment, water, or floodplain soils, usually through dermal contact. At
sites with non-bioaccumulative or non-biomagnifying contaminants, human health risk is usually driven
by pathways involving direct contact.
Generally, the ecological risk assessment should consider the risks to invertebrates, plants, fish
and wildlife from direct exposure and from food chain expsoures. The selection of appropriate site-
specific assessment endpoints is a critical component of the ecological risk assessment. Once assessment
endpoints have been selected, testable hypotheses and measurement endpoints can be developed to
evaluate the potential threat of the contaminants of potential concern to the assessment endpoints. PCBs,
for example, bioaccumulate in food chains and can diminish reproductive success in upper trophic level
species (e.g., mink, kingfishers) exposed to contaminants through their diet. Therefore, reduced
reproductive success in fish-eating birds and mammals may be an appropriate assessment endpoint. An
appropriate measurement endpoint in this case might be contaminant concentrations in fish or in the
sediment where the concentrations in these media can be correlated to reproductive effects in the top
predator that eats the fish. The sediment concentration range associated with an acceptable level of
reproductive success usually would constitute the remediation goal.
2.3.3
Risks from Remedial Options
. As part of the risk assessment, the short-term, and if appropriate, the long-term risks to human
health and the environment from implementation of each of the considered remedial alternatives should
be estimated and considered in the remedy selection process. For example, excavation of sediment and
capping normally will remove or kill local biota utilizing the areas. These alternatives may also cause
substantial short-term impacts on the biota that relied on the existing sediment bed for habitat or food. It
is generally believed, however, that these impacts will be short lived, and the biota and habitats typically
will recover in less than a year or two. Use of eco-friendly materials as backfill for dredging projects or
as a fmal cap surface can greatly improve the likelihood of quick re-colonization by beneficial biota. The
subject of implementation risks is discussed in more detail in the remedy-specific chapters of this
guidance and in Chapter 7, Section 7.3, Comparing Net Risk Reduction.
2.4
CLEANUP GOALS
To select the most appropriate remedy for a site, it is important to develop clearly defmed
remedial action objectives (RAOs) and contaminant-specific remediation goals (RGs). RAOs generally
are used in developing and comparing alternatives for a site and in providing the basis for developing
more specific RGs, which in turn are used by project managers to select fmal sediment cleanup levels
based on the other NCP remedy selection criteria. RAOs, RGs, and cleanup levels are dependent on each
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Chapter 2: Remedial Investigation Con.viderations
other and represent three steps along a continuum leading from remedial investigation/feasability study
scoping to the selection of a remedial action that will be protective of human health and the environment,
meet applicable or relevant and appropriate requirements (ARARs), and provide the best balance among
the remaining NCP criteria.
2.4.1
Remedial Action Objectives and Remediation Goals
RAOs provide a general description of what the cleanup is expected to accomplish, and help
focus the development of the remedial alternatives in the feasibility study. RAOs typically are derived
from the conceptual site model (Section 2.2), and address the significant exposure pathways. RAOs may
vary widely for different parts, of the site based on the exposure pathways and receptors, regardless if
these parts of the site are managed separately as operable units under CERCLA. For example, a sediment
site may include a recreational area used by fishermen and children, as well as a wetland that provides
critical habitat for fish and wildlife. Though both areas may contain similarly contaminated sediment, the
different receptors and exposure pathways may lead a project manager to develop different RAOs and
RGs for each area that are protective of the different receptors.
The development of RAOs should also include a discussion of how they address all the
unacceptable human health and ecological risks identified in the risk assessment. Examples of RAOs
specific for sediment sites are included in Highlight 2-6. Sediment sites also may need RAOs for other
media (e.g., soils, ground water, or surface water). When developing RAOs, project managers should
evaluate whether the RAO is achievable by remediation of the site or if it requires additional actions
outside the conttol of the project manager. For example, complete biota recovery may depend on the
cleanup of sources that are regulated under other authorities. The project manager may discuss these
other actions in the record of decision (ROD) and explain how the site remediation is expected to
contribute to meeting area-wide goals outside the scope of the site, such as goals related to watershed
concerns, but RAOs should reflect objectives which are achievable from the site cleanup.
......
.. ",......................".,."......... "",',',,,"'."""""" ..,......""...,..."................,...."."""........... .....""",,,............,.,

ii!i~~~~!~II~i~H!~:i~~II!II~II!~~:lgll~illjl~~II~:!~11glll~IR~ill~ll~i~~~!~::!,::::::::}~:::::!::
Human Health:
Reduce the risks to children and adults from the incidental ingestion of and dermal exposure to
contaminated sediment while playing, wading, or swimming at the site to acceptable levels
Reduce the risks to adults and children from ingestion of contaminated fish and shellfish taken from the
site to acceptab,le levels
Ecological Risk:
Reduce the toxicity to benthic aquatic organisms at the site to levels that are acceptable
Reduce the risks to birds and mammals that feed on fish that have been contaminated from sediment at
the site to levels that are acceptable
Generally, preliminary remediation goals (PRGs) that are protective of human health and the
environment are developed early in the remedial investigation process based on readily available
screening levels for both human health and ecological risks (although project managers should be aware
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Chapter 2: Remedial Investi/(ation Considerations
that currently available screening levels for sediment are limited; see Section 2.3.1). Because there are
very few ARARs specifically for sediment, these RGs are nonnally based on the site-specific risk
assessment. Regions should note, however, some states do have standards for contaminated sediment
(e.g., State of Washington) and others are developing them.
As more infonnation is generated during the investigation, these PRGs should be replaced with
site-specific RGs by incorporating an improved understanding of site conditions (e.g., site-specific
infonnation on fish ingestion rates and bioaccumulation of contaminants in sediment into biota; resource
use; other human activities), and other site-specific factors, such as the bioavailability of contaminants.
The completed human health and ecological risk assessments should identify appropriate RGs for each
contaminant of concern in each medium of significance. RGs for sediment often address direct contact
for humans and biota to the sediment as well as bioaccumulation through the food chain. The
concentrations of bioaccumulative contaminants in fish are a function of both the sediment and water
concentrations of the contaminant, and are, to some extent, species-dependent. The development of the
sediment RGs may involve a variety of different approaches that range from the simple application of a
bioaccumulation factor from sediment to fish or more sophisticated food chain modeling. The method
used and the level of complexity in the back calculation from fish to sediment should be consistent with
the approaches used in the human health and ecological risk assessments.
RGs should be represented as a range of values within acceptable risk levels so that the project
manager may consider the other NCP criteria when selecting the fmal cleanup levels. For human health,
general guidance is available regarding the exposure equations necessary to develop RG concentrations in
various media for both cancer risks and non-cancer health hazards (see Section 2.3.) The development of
the human health-based RGs should provide a range of risk levels (e.g., 10~, 10'5, and 10-4 and a non-
cancer Hazard Index of I or less depending on the health end points of the specific contaminants of
concern.) The development of the ecologically-based RGs should also provide a range of risk levels
based on the receptors of concern identified in the ecological risk assessment (see Section 2.3). Human
health and ecological RGs should be developed through iterative discussions between the project
manager, risk assessor, and modeler or other appropriate members of the team.
2.4.2
Cleanup Levels
At most CERCLA sites, RGs for human health and ecological receptors are developed into fmal,
chemical-specific, sediment cleanup levels by weighing a number of factors, including site-specific
uncertainty factors and the criteria for remedy selection found in the NCP at Title 40 Code of Federal
Regulations (40 CFR) ~300.430. These criteria include long-tenn effectiveness and pennanence;
reduction of toxicity, mobility and volume through treatment; short-tenn effectiveness; implementability;
cost; and state and community acceptance. These criteria are discussed in detail in Chapter 3, Section 3.2,
NCP Remedy Selection Criteria.
Uncertainty factors that may be relevant to consider include (among others) the reliability of
inputs and outputs of any model used to estimate risks and establish cleanup levels, reliability of the
potential approaches to achieve those results, and the likelihood of occurrence for the exposure scenarios
being considered. Other technical factors include (among others) limitations of remedial alternatives and
detection and quantification limits of contaminants in environmental media. It is especially important to
assess technical achievability realistically, by considering both background levels of contamination and
what has been achieved at similar sites elsewhere, so that achievable cleanup levels are developed. All of
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Chapter 2: Remedial Investigation Considerations
these factors, along with verified background concentrations of COC, are considered when establishing
fmal cleanup levels that are within the risk range.
The derivation of ecologically based cleanup levels is a complex and interactive process
incorporating contaminant fate and transport processes, toxicological considerations and potential habitat
impacts of the remediation alternatives. Before selecting a cleanup level, the project manager, in
consultation with the ecological risk assessor, should consider at least the following factors (U.S. EP A
I 999b):
.
The magnitude of the observed or expected effects of site releases and the level of
biological organization affected (e.g., individual, local population, or community);
.
The likelihood that these effects will occur or continue;
The ecological relationship of the affected area to the surrounding habitat;
.
Whether the affected area is a highly sensitive or ecologically unique environment; and
The recovery potential of the affected ecological receptors and expected persistence of
the chemicals of concern under present site conditions.
Generally, for CERCLA actions, the ROD should include chemical-specific cleanup levels as
provided in the NCP at 40 CFR ~300.430(c)(2)(I)(A). The ROD should also indicate the approach that
will be used to measure attainment of the cleanup levels. At many sediment sites, especially but not
exclusively those with bioaccumulative contaminants, the attainment of sediment cleanup levels may not
coincide with the attainment of RAOs. For example, this may be due to the length of time needed for fish
or the benthic community to recover. Where cleanup levels have been achieved but progress towards
meeting RAOs is not forthcoming as expected, the five-year review process, or where appropriate, a
similar process conducted sooner than five years, should be used to assess whether additional actions are
needed. Consistent with the NCP (40 CFR g300.430(f)(4)(ii», where contaminants remain present above
unlimited use and unrestricted exposure levels, Superfund sites should be reviewed no less than every five
years after initiation of the selected remedial action. Chapter 8, Remedial Action and Long-Term
Monitoring, provides additional guidance on the information that should be collected for this review to be
effective. As explained further in that chapter, the need for long-term monitoring is not limited to sites
where five-year reviews are required. Most sites where contaminated sediment has been removed also
should be monitored for some period to ensure that cleanup levels and RAOs are met and will continue to
be met.
2.5
WATERSHED CONSIDERATIONS
A unique aspect of contaminated sediment sites is their relationship within the overall watershed,
or drainage area, in which they are located. Within the watershed there often is a spectrum of issues that
the project manager may need to consider. Foremost among them at many sites is to work with the state
to ensure that fish consumption advisories are in place and well publicized. Project managers also should
understand the role of the contaminated water body in the watershed, including the habitat or flood
control functions it may serve, the presence of non- site-related contaminant sources in the watershed, and
current and reasonably anticipated or desired future uses of the water body and surrounding land.
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Chapter 2: Remedial Investigation Considerations
2.5.1
Role of the Contaminated Water Body
Most water bodies provide important habitat for spawning, migration, or food production for fish,
shellfish, birds, and other aquatic and land-based animals. One significant issue is the protection of
migratory fish. These are fish such as salmon, shad, and herring that migrate as adults from marine
waters up estuaries and rivers to streams and lakes where they spawn. The juveniles spend varying
lengths of time in freshwater before migrating back to estuarine/marine waters. It is difficult to evaluate
the impact of a particular contaminated sediment site on wide-ranging species that may encounter several
sources of contamination along their migratory route. This is an important consideration when evaluating
alternatives and establishing remediation goals for a site, as these fish populations may not show
improvement if any link in their migratory route is missing, blocked, or toxic. For migratory species, it
may be more appropriate to measure risk and remedy effectiveness in terms of risk to juveniles.
The size, topography, climate, and land use of a watershed, among other factors, may affect
characteristics of a water body, such as water quality, sedimentation rate, sediment characteristics,
seasonal water flows and current velocities, and the potential for ice formation. For example, watersheds
with large wetland areas tend to store flood waters and enable ground water recharge, thereby protecting
downstream areas from increased flooding, whereas an agricultural or urbanized watershed may have
increased erosion and greater flow during storm events. Watershed changes can result from natural
events, such as wildfires, or from human activities such as road and dam construction/removal,
impoundment releases, and urban/suburban development. When considering watershed characteristics, it
is important to consider both current and future watershed conditions.
Some sediment sites are located in watersheds with a large number of historical and ongoing
point and non-point sources, from many potentially responsible parties. Where this is the case, it is
especially important to attain expert assistance to plan site characterization strategies that are well suited
to the complexity of the issues and designed to answer specific questions. In urban watersheds and others
with a large number of ongoing sources, it may be beneficial for a broader group of stakeholders to
participate in setting priorities for site characterization and remediation efforts. In these areas, it is
especially important to consider background concentrations when developing remedial objectives and to
evaluate the incremental improvement to the environment if an action is taken at a specific site in the
watershed. Approaching management of a site within the watershed context provides an opportunity to
better determine the needs and coordinate the sequence and schedule of cleanup activities in the
watershed.
2.5.2
Water Body and Land Uses
Water body uses at sediment sites may include commercial navigation; commercial fisheries,
shellfisheries, or aquaculture; boating, swimming, and other forms of recreation; other commercial or
industrial uses; recreational or subsistence fishing or shellfishing; and other, less easily categorized uses.
Most water bodies used for commercial navigation, such as for shipping channels, turning basins, and
port areas, are periodically dredged to conform to the minimum depth for the area prescribed by
Congress; such dredging is typically performed by the U.S. Army Corps of Engineers (USACE). Other
commercial or industrial uses of a site may include the presence of gravel pits, drinking water use, and
industrial uses of water including cooling, washing, or waste water disposal.
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Chapter 2: Remedial Investigation Considerations
The NCP preamble (55 FR 8710) states that both current and future land uses should be evaluated
in assessing risks posed by contaminants at a Superfund site and discusses how Superfund remedies
should be protective in light of reasonably anticipated future uses. EP A has provided further guidance on
how to evaluate future land use in the OSWER Directive 9355.7-04, Land Use in the CERCLA Remedy
Selection Process, also referred to as the "Land Use Guidance" (U.S. EPA 1995a). This guidance
encourages early discussions with state and local land use planning authorities and the public, regarding
reasonably anticipated future uses of properties associated with an National Priorities List (NPL) site.
This coordination should begin during the scoping phase of the RIfFS, and ongoing coordination is
recommended to ensure that any changes in expectations are incorporated into the remedial process.
There are additional factors the project manager should include in considering anticipated future
uses for aquatic sites that are not specifically addressed in the Land Use Guidance. For example, future
use of the site by ecological receptors may be a more important consideration for an aquatic sediment
Superfund or RCRA site as compared to an upland terrestrial site. A remediated sediment site may attract
more recreational, subsistence, and cultural uses, including fishing, swimming, and boating. Where
applicable, the project manager should consider tribal treaty rights to collect fish or other aquatic
resources. The project manager should also consider (generally as TBCs, see Chapter 3, Section 3.3 on
ARARs) designated uses in the state's water quality standards, priorities established as a result of total
maximum daily loads (TMDLs), or pollution reduction efforts under various Clean Water Act (CW A)
programs in projecting future waterway uses. In ports and harbors, the project manager should consult
master plans developed by port and harbor authorities for projections offuture use. The USACE should
also be contacted regarding future navigational dredging of federally maintained channels.
There may be more parties to consult about anticipated future use at large sediment sites as
Of' ..:::<;ed to typical upland sites. These parties include the community, environmental groups, natural
rJ';oUrce trustees, Indian tribes, the local deparbnent of health, as well as local government, port and
harbor authorities, and land use planning authorities. As with upland sites, consultation should start at the
RIfFS scoping phase and continue throughout the life of the project. Different stakeholders often have
divergent and conflicting ideas about future use at the site. Local residents and environmental groups
may anticipate future habitat restoration and increased recreational and ecological use while local
industrial landowners may project increased shipping and industrial use. The NCP preamble (55 FR
871 0) states that, in the baseline risk assessment, more than one future use assumption should be
considered when decision makers wish to understand the implications of different exposure scenarios.
Especially where there is some uncertainty regarding the anticipated future uses, the project manager
should compare the potential risks associated with several use scenarios.
The identification of appropriate future use assumptions during the baseline risk assessment and
the feasibility study should allow the project manager to focus on developing protective, practicable, and
cost-effective remedial alternatives. In addition, coordination with stakeholders on land and water body
uses leads to opportunities to coordinate Superfund or RCRA remediation in conjunction with local
development or habitat restoration projects. For example, at some sites the EP A has worked with port
authorities to combine Superfund or RCRA remedial dredging with dredging needed for navigation.
Others have combined capping needed for Superfund or RCRA remediation with habitat restoration,
allowing potentially responsible parties (pRPs) to settle natural resource damage claims in conjunction
with the cleanup. However, as noted in Chapter 1, Section 1.5, State, Tribal, and Trustee Involvement,
whether remediation and restoration are addressed concurrently is a site-specific decision that involves
input from a number of different parties.
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2.6
SOURCE CONTROL
Identifying and controlling contaminant sources is critical to the effectiveness of any Superfund
sediment cleanup. Source control is defmed as those efforts that are taken to eliminate or reduce, to the
extent practicable, the release of contaminants from direct and indirect continuing sources to the water
body under investigation. At some sediment sites, the original sources of the contamination have already
been controlled, but subsequent sources such as contaminated flood plain soils, storm water discharges,
and seeps of ground water or non-aqueous phase liquids (NAPLs) may continue to introduce
contamination to a site. At sites with significant sediment mobility, areas of higher contaminant
concentration may act as continuing sources for less-contaminated areas.
Some sources, especially those outside the boundaries of the Superfund or RCRA site, may best
be handled under another authority, such as the CW A or a state program. These types of sites can present
an opportunity for partnering with private industry and other governmental entities to identify and control
sources on a watershed basis. Water bodies with sources outside the Superfund site also present a need to
balance the desire for watershed-wide solutions with practical considerations affecting a subset of
responsible parties. It can be difficult to determine the proper party to investigate sources outside the
Superfund site, but the site RI/FS must be sufficient to determine the extent of contamination coming onto
the site and its likely effect on any actions at the site. A critical question is whether an action in one part
of the watershed is likely to result in significant and lasting risk reduction, given the probable timetable
for other actions in the watershed.
Source control activities are often broad-ranging in scope. Source control may include
application of regulatory mechanisms and remedial technologies to be implemented according to ARARs,
including the application of technology-based and water quality-based National Pollutant Discharge
Elimination System (NPDES) permitting to achieve and maintain sediment cleanup levels. Source
control actions may include the following, or other actions:
.
Elimination or treatment of waste water discharges (e.g., installing additional treatment
systems prior to discharge);
Isolation or containment of sources (e.g., capping of contaminated soil) with attendant
engineering controls;
Pollutant load reductions of point and non-point sources based on a TMDL;
.
Implementation of best management practices (e.g., reducing chemical releases to a storm
drain line); and
.
Removal or containment of mobile sediment hot spots.
EP A's Contaminated Sediment Management Strategy (U.S. EP A 1998a) includes some
discussion of EP A's strategy for abating and controlling sources of sediment contamination. Source
control activities may be implemented by state or local governments using combinations of voluntary and
mandatory actions.
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The identification of continuing sources and their potential to re-contaminate site sediment are
essential parts of site characterization and the development of an accurate conceptual site model, whether
. or not source areas are part of the site itself. When there are multiple sources, it is important to prioritize
sources to determine the relative significance of continuing sources versus on-site sediment in terms of
site risks to determine where to focus resources. Where sources are a part of the site, project managers
should develop a source control strategy or approach for the site as early as possible in the process of site
characterization. Where sources are outside the site, project managers should encourage the development
of source control strategies by other authorities, and understand those strategies. Generally, a source
control strategy should include plans for identifying, characterizing, prioritizing, and tracking source
control actions, and for evaluating the effectiveness of those actions. It is also useful to establish
milestones for source control that can be linked with sediment remedial design and cleanup actions. If
sources are substantially controlled, it is very important to re-evaluate risk pathways to see if sediment
actions are still needed. If sources are not substantially controlled, it is very important to include ongoing
sources in the evaluation of what sediment actions mayor may not be appropriate and what management
goals are achievable for the site.
Generally, significant continuing upland sources (including ground water, NAPL, or upgradient
water releases) should be controlled to the greatest extent possible before sediment cleanup. Once these
sources are controlled, project managers should evaluate the effectiveness of the actions, and should
refine and adjust levels of source control, as warranted. In most cases, before any sediment action is
taken, project managers should consider the potential for re-contamination and factor that potential into
the remedy selection process. If a site includes a source that could result in significant re-contamination,
source control measures will likely be necessary as part of that response action. However, where
sediment remediation is likely to significantly benefit human health and/or the environment after
considering the risks caused by an unaddressed or ongoing source, it may be appropriate to conduct an
action for sediment prior to completing all land-based source control actions.
2.7
PHASED APPROACHES AND EARLY ACTIONS
At some sediment sites, a phased approach to site characterization, remedy selection, or remedy
implementation may be the best or only practical option. Phasing site characterization can be especially
useful when risks are high, yet some important site-specific factors are unknown. Phasing in remedy
selection and implementation may be especially useful at sites where contaminant fate and transport
processes are not well understood or the remedy has significant implementation uncertainties. Phasing
may also be useful where the effectiveness of source control is in doubt. By knowing the effectiveness of
source control prior to implementing sediment cleanups, the risk of having to revisit re-contaminated
areas is greatly reduced. High remedy costs, the lack of available services and/or equipment, and
uncertainties about the potential effectiveness or the risks of implementing the preferred sediment
management approach, can also lead to a decision to phase the cleanup.
Phasing can also be used at large, multi-source, multi-PRP sites with primarily historic
contamination where contaminated sediment is still near the sources. In these types of sites, working with
single responsible parties to address sediments with higher contaminant concentration near their sources
may be an effective risk reduction measure, while the more complex decision making concerning less-
contaminated downstream areas with mixed contaminants is ongoing.
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Chapter 2: Remedial Investi/(ation Considerations
Project managers are also encouraged to use an iterative approach, especially at complex
sediment sites in order to provide additional certainty of information to support decisions. In general, this
means testing of hypotheses and conclusions and reevaluating site assumptions as new information is
gathered. This is an important component of updating the conceptual site model. For example, an
iterative approach might include gathering and evaluating multiple data sets or pilot testing to determine
the effectiveness of various remedial technologies at a site. The extent to which iteration is cost-effective
is, of course, a site-specific decision. Using iteration to reduce uncertainty may be extremely cost-
effective where it allows use ofless costly alternatives; however, uncertainty in some areas is less critical.
As noted in Chapter, Section 1.4, Decision-Making Process, an iterative approach should not be
misconstrued as an endless loop.
Even before the sediment at a site is well characterized, if risk is obvious, it may be very
important to begin to control significant ongoing land-based sources. It also may be appropriate to take
other early or interim actions, followed by a period of monitoring, before deciding on a final remedy.
Highlight 2-7 provides examples of early actions taken to control sources, minimize human exposure,
control sediment migration, or reduce risk from sediment hot spots at contaminated sediment sites. Early
or interim actions are frequently used to prevent human exposure to contaminants or to control sources of
sediment contamination. However, such actions for sediment are less frequent. Early or interim actions
may be appropriate for sediment to prevent migration or to reduce the current risk from a localized area of
highly contaminated sediment. Factors for determining which response components may be suitable for
early or interim actions include the time frame needed to attain specific objectives, the relative urgency
posed by potential or actual exposure, the degree to which an action may reduce site risks, and
compatibility with likely long-term actions (U.S. EPA 1992b).
An early action taken under Superfund removal authority may be appropriate at a sediment site
when, for example, it is necessary to respond quickly to a release or a threatened release of a hazardous
substance that would present an immediate threat. At contaminated sediment sites, removal authority or
state authorities have been used to implement many of the actions listed in Highlight 2-7. The NCP at 40
CFR ~300.415 outlines criteria for using removal authority, as further explained in the EPA guidance and
directives (U.S. EPA 1993a, U.S. EPA 1996d, U.S. EPA 2000a). Project managers may also consider
separating the management of source areas from other, less concentrated areas by establishing separate
Operable Units (OUs) for the site.
2.8
SEDIMENT STABILITY AND CONTAMINANT FATE AND TRANSPORT
An important part of the remedial investigation at many sediment sites is an assessment of the
extent of sediment and contaminant movement by processes and events in the past and a prediction about
whether there is likely to be significant redistribution or transport in the foreseeable future. It is also
important to characterize the potential movement of sediment and contaminants to accurately assess a
range of risk management approaches. This characterization should include an assessment of sediment
stability and contaminant fate and transport.
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Chapter 2: Remedial Investigation Considerations
. .. . ... . . .
[[["................................................".."............-.....-,.-,....,............................................
"",-,-","""""""""""""""""""""-,""""""""""""""""""""""""-"'"......,""""""""""""""""""'-"""'"[[[
:::::'=:':':::::::'H!s~'I.!Q~!:gf!~:':B9mn#i!.~~~mpjl!!:~~~!Y:A91ili:~!:ignE~~!i~!.~ii!m~n~~~m~:::::':'::'::::!:::!::=.:.::!:::
Actions to prevent releases of contaminants from sources:
Excavation or containment of flood plain soils or other source materials in the flood plain
Engineering controls (e.g., sheet pilings, slurry walls, grout curtains, and extraction) to prevent highly
contaminated ground water, NAPL, or leachate from reaching surface water and sediment
Engineering controls to prevent contaminated runoff from reaching surface water and sediment
Actions to minimize human exposure to contaminants (coordinated with other appropriate agencies):
Access restrictions
Fish consumption advisories
Use restrictions and advisories for water bodies
Actions to protect downstream drinking water supplies
Actions to minimize further migration of contaminated sediment:
Boating controls (e.g., vessel draft or wake restrictions to prevent propeller wash, anchoring restrictions)
Excavating, dredging, capping, or otherwise isolating contaminated sediment hot spots
Actions taken to reduce risk from highly contaminated sediment hot spots:
Capping, excavation, or dredging of localized areas of contaminated sediment that pose a very high risk
In most aquatic environments, surface sediment and any associated contaminants, move over
time. The more important, and more complex issue is whether movement of contaminated sediment
(surface and subsurface) or of contaminants alone is occurring or may occur at scales and rates that will
significantly change their current contribution to human health and ecological risk. Addressing that issue
requires an understanding of the role of natural processes that counteract sediment and contaminant
movement and fate, such as natural sedimentation and armoring, and contaminant transformations to less
toxic or less bioavailable compounds. For this reason, it is important for project managers to use
technical experts to help in the analysis of sediment stability and contaminant mobility, especially where
large amounts of resources are at stake.
Sediment movement is a complex topic also because it has both positive and negative effects on
risk. For example, floods frequently transport both clean and contaminated sediment, which are
subsequently deposited within the water body and on flood plains. This may spread contamination,
isolate (through burial) other existing contamination, and lower concentrations of contaminants (through
dilution) within the immediate site boundaries.

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Chapter 2: Remedial Investigation Considerations
:::.::::::':::::::::::..:.:.:...:.:.:H.!ij~!!~~!:.~m~.:Rii~~~!!!::p~~~llr:_!m!!~'.;~'~t..G~hmm!~!~!Mi:¥II~..::::..::".'.'.'.'.'.'.'.'.'.'.'.."""
Natural causes of sediment movement include:
Routine currents in rivers, streams, and harbors
Tides in marine waters and estuaries
Floods generated by rainfall or snow-melt induced runoff from land surfaces
Ice thaw and ice dam-induced scour
Seiches (oscillation of lake elevation caused by sustained winds), especially in the Great Lakes
Storm-generated waves and currents (e.g., hurricanes, Pacific cyclones, nor'easters)
Seismic-generated waves (e.g., tsunamis)
Earthquakes, landslides, and dam failures
Bioturbation from micro- and macrofauna
Anthropogenic causes of sediment movement include:
Navigational dredging and channel maintenance
Placer mining, and sand and gravel mining
Intentional removal or breaching of hydraulic structures such as dams, dikes, weirs, groins, and
breakwaters
In-water construction
Boat propeller wash, ships' wakes, ship grounding or anchor dragging
Causes of dissolved contaminant movement without sediment movement include:
Flow of ground water through sediment
Molecular diffusion
Gas-assisted transport
Many contaminated sediment sites are located in areas that are primarily depositional, or in areas
where only a limited surface layer of sediment is routinely mobilized. In these fairly stable areas, other
processes may contribute to sediment and contaminant movement. These include, for sediment,
bioturbation, and for dissolved contaminants, ground water flow, molecular diffusion, and potentially,
gas-assisted transport. Like erosion and deposition, these processes continue to operate after remedies are
in place, so an understanding of whether or not they are likely to be significant ongoing contaminant
transport pathways at a particular site is especially important for evaluating in-situ capping and monitored
natural recovery alternatives.
There are a variety of empirical and modeling methods for evaluating sediment and contaminant
movement and their consequences. The models nonnally rely upon site-specific empirical data for input
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Chapter 2: Remedial Investigation Considerations
parameters. Both empirical methods and models have limitations, so it is usually important to consider a
variety of methods in evaluating a site and to compare the results. For large or complex sediment sites,
project managers should approach an assessment of sediment and contaminant movement from the
following aspects:
A site-specific assessment of empirical site characterization data (see Section 2.8.1);
A site-specific assessment of the frequencies and intensities of expected routine and
extreme events which mobilize sediment (see Section 2.8.2);
A site-specific assessment of ongoing processes that mobilize contaminants in otherwise
stable sediment, such as bioturbation, diffusion, and advection (see Section 2.8.3); and
A site-specific assessment of the expected consequences or results of sediment and
contaminant movement (see Section 2.8.4).
As noted above, this assessment will frequently require the use of models. A wide variety of
models are available, ranging from simple models with small numbers of input criteria to complex, multi-
dimensional models that are data intensive. A discussion of model uses and selection is presented in
Section 2.9.
Especially for larger sites, a "lines of evidence" approach should be used to evaluate the stability
of the sediment bed and the contaminants within it for various areas of the water body. Where multiple
lines of evidence point to similar conclusions, project managers may have more confidence in their
predictions. Where the lines of evidence do not concur, project managers should bring their technical
experts together to determine the source of the discrepancies and understand their significance. This
approach is described in more detail in Chapter 4, Section 4.3, Lines of Evidence.
2.8.1
Data Collection
An assessment of sediment and contaminant movement begins with the collection of a variety of
empirical data (i.e., data derived from field or laboratory observation). Although literature values may be
available for some parameters, project managers are encouraged to collect site-specific information for
the most important processes at the site (as identified in the conceptual site model), especially where large
resources are at stake in decision making.
The vertical and horizontal sediment and contaminant distributions present at a site are a result of
all of the routine and extreme, natural and anthropogenic processes that contribute to the physical,
chemical, and biological attributes of a water body. Site conditions at the time of investigation generally
reflect a combination of influences. Project managers should not assume that current conditions represent
stable conditions when, in fact, sediment may be actively responding to recent or current forces and
events. Conversely, project managers should not assume that a site or all areas of a site are unstable or
contaminants are mobile at a scale or rate which significantly impacts risk. At many sites, the same areas
of contamination persist over many years, despite some level of surface sediment and contaminant
redistribution.
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Chapter 2: Remedial Investigation Considerations
Processes that are important in terms of their larger scale influences on a watershed may be less
important to the stability of sediment or mobility. of contaminants in smaller, more isolated areas of a
water body. Both scales of investigation may be important. For example, in some situations, the large
scale rainstorms associated with hurricanes may greatly impact sediment loading to the water body, but
have little effect on stability of the sediment bed itself. When considering the potential impacts of
disruptive forces on sediment movement, it is important to assess these forces as they relate to the overall
watershed and in terms of current and future site characteristics.
Many site characteristics affect sediment stability, but primary among them are the flow-induced
shear stress at the bottom of the water body during various conditions, and the cohesiveness of the upper
sediment layers. In most environments, bottom shear stress is controlled by currents, waves, and bottom
roughness (e.g., sand ripples, biologically formed mounds in fmes). A preliminary evaluation of sediment
stability should include at least site-specific measurements of surface water flow velocities and
discharges, water body bathymetry, and surface sediment types (e.g., by use of surface grab samples).
In some cases, empirically measured erosion rates are lower than anticipated from simple models,
due to natural armoring. Winnowing (suspension and transport) of fines from the surface layers of
sediment is one common form of armoring. Others are listed in Highlight 2-9, including the effect known
as "dynamic armoring", which describes the effect caused by suspended sediment or a fluff, floc, or low
density mud layer (present in some estuaries and lakes) that decreases the expected erosion rate of
underlying sediment.
Physical:
Winnowing of fine grained materials, leaving larger-grained materials on surface
Compaction of fine-grained sediment
Chemical:
Chemical reactions and weathering of surface sediment
Dynamic:
Suspended sediment dampening turbulence during high flow events
Biological:
Physical protection and sequestration by rooted aquatic vegetation
Mucous excretions of polychaetes
Erosion-resistant fecal pellets or digested sediment
Sediment properties that affect cohesion and erosion in many sediment environments include
bulk density, particle size (average and distribution), clay mineralogy, the presence of gas, and the
organic content. It is not unusual for erosion rates to vary by 2 to 3 orders of magnitude spatially at a site,
depending on currents, bathymetry, bioturbation, and other factors (e.g., pore water salinity). In a fairly
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Chapter 2: Remedial Investigation Considerations
uniform cohesive sediment core, erosion rates may drop several orders of magnitude with depth into the
sediment bed, but in more variable cores this may not be the case.
Biological processes by macro- and microorganisms also affect sediment stability in multiple
ways, both to increase erosion (e.g., gas generation and bioturbation by lowering bulk density) and to
decrease erosion (e.g., aquatic vegetation, biochemical reactions which increase shear strength of
sediment). The process of sediment mixing caused by bioturbation is discussed further in Section 2.8.3.
A wide variety of empirical methods is available to assess the extent of past sediment and
contaminant movement. Highlight 2-10 lists some key examples. Each of these methods has advantages
and limitations and generally none should be used in isolation. The help of technical experts is likely to
be needed to determine which methods are most likely to be useful at a particular site.
2.8.2
Routine and Extreme Events
Naturally occurring hydrodynamic forces such as those generated by wind, waves, currents, and
tides, occur with great predictability and significantly influence sediment characteristics and movement
(Hall 1994). While these routine forces seldom cause changes that are dramatically visible, they may be
the events causing highest shear stress and therefore the most important factors in controlling the physical
structure of a given water body. In northern climates, formation of ice dams and ice scour are also routine
events that may have significant effects on sediment. It is important to note that seasonal changes in
water flow may also affect where erosion and deposition occur. Depending on the location of the site,
(e.g., riverine areas, coastal/marine area, inland water bodies), different water body factors will play
important roles in determining sediment movement. To determine the frequency of particular routine
forces acting upon sediment, project managers should obtain historical records on flows and stages from
nearby gauging stations and on other hydrodynamic forces. However, project managers should keep in
mind that residential or commercial development in a watershed may significantly increase the
impervious area and subsequently increase the frequency and intensity of routine flood events. While the
intensity of most routine forces may be low, their high frequency may cause them to be an important
influence on sediment movement within some water bodies.
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Chapter 2: Remedial Investigation Considerations
.. ..
[[[""""""""""""""""""""'"...........................-........................................,".",...",........ ................
[[["...."....,..,."[[["."...................
:.M~Qij,,,!@.~~gf19:'~~~~me~r!$~'M!mg~~'~:i¥i!Mi~~~i~im~g~'~n~RI~m!9i9~M.9¥~lir~i
Bathymetry (evaluates net change in sediment surface elevations)
Single point/local area devices
Transects/cross-sections (with known vertical and horizontal accuracy)
longitudinal river profiles along the thalweg (Le., location of deepest depth)
Acoustic surveys (with known vertical and horizontal accuracy)
Comparison to dredging records, aerial photos, overall geomorphology
Contaminant data (from continuous cores, surface sediment, and water column):
Time-series observations (event scale and long-term seasonal, annual, decade-scale)
Comparison of core pattern or changing pattern in surface sediment, with pollutant loading history
Comparison of concentration patterns during and after high energy events
Sediment data (e.g., from continuous cores or surface samples):
Patterns of grain-size distribution; sediment trend analysis (McLaren and Bowles 1985, McLaren et al. 1993, Pascoe et al.
2002)
In-situ or ex-situ erosion measurement devices [e.g., SEDFLUME (Jepsen et al. 1997, McNeil et al. 1996), PES (Tsai
and Lick 1986), Sea Carousel (Maa et al. 1993), or Inverted Flume (Ravens and Gschwend 1999)]
Sediment water interface camera
Geochronology (evaluates continuity of sedimentation and age of sediment with depth in cores):
137CS, lignin, stable Pb (longer-lived species to evaluate burial rate and age progression with depth)


210Pb, 7Be, 234Th (shorter-lived species to evaluate depth of mixing zone)
X-radiography, color density analysis
Geomorphological studies:
land and water body geometry and bathymetry; physical processes
Human modifications
Sediment-contaminant mass balance studies during high energy events:
Upstream and tributary loadings (grain size distributions and rating curves)
Tidal cycle sampling (in marine estuaries and coastal seas)
Sampling during the rising limb of a rain-event generated runoff hydrograph (frequently greatest erosion)
Dissolved contaminant movement:
Seepage meters at sediment surface

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Chapter 2: Remedial Investigation Considerations
"routine" forces (e.g., wind) but are significantly stronger than routine conditions and capable of moving
large amounts of sediment. Some extreme events, however, have no routine event counterparts (e.g.,
earthquakes). Meteorological events, such as hurricanes, may move large amounts of sediment in coastal
areas due to storm surges and unusually high tides that cause flooding. Flooding may occur from snow-
melt and other unusually heavy precipitation events resulting in the movement of large amounts of upland
soil and erosion of sediment, which are then deposited in other areas of the water body or on flood plains
when the flow slows during the falling limb of the runoff hydrograph. Scour of the sediment bed may
also result from the movement of ice and/or natural or man-made debris during extreme flood events. To
obtain a preliminary understanding of extreme event frequency at a site, it is important to examine both
historical records (e.g., meteorological and flow records) and site characterization data (e.g., core data and
bathymetry ).
Floods are frequently classified by their probability of occurrence; for example 50-year, 100-year,
200-year, and probable maximum flood. Although the term" I OO-year flood" suggests a time frame, it is
in fact a probability expression that a flood has a one percent probability of occurring (or being exceeded)
in any year. Similarly, 200-year flood refer to a flood with a 0.5 percent probability of occurring in any
year. Probable maximum flood refers to the most extreme flood that could theoretically occur based on
maximum rainfall and maximum runoff in a watershed. It is not uncommon for multiple low probability
events to happen more frequently than they are expected, especially when the hydrograph record used to
determine these probabilities is not very long or where land use or climate is changing.
It is important to consider the intensity of extreme hydrodynamic forces as well as their
frequency. Intensity is a measure of the strength, power or energy of a force. The intensity of a force will
be a significant determinant of its possible impact on the proposed remedy. Tropical storms (including
hurricanes) are often classified according to their intensity, that is, the effects at a particular place and
time which is a function of both the magnitude of the event and the distance from it. Tropical storms such
as hurricanes are commonly classified by intensity using the Saflir-Simpson Scale of Category 1 to
Category 5. Other physical forces and events, such as earthquakes, may be classified according to
magnitude, that is a measure of the strength of the force or the energy released by it. Earthquakes are
most commonly classified in this way (e.g., the Richter scale) although they may also be classified by
intensity at a certain surface location (e.g., the Modified Mercalli scale).
For sites in areas that may be affected by extreme events, project managers should assess the
record of occurrence near the site and determine the appropriate category or categories for analysis. At a
minimum, project managers should evaluate the impa~ts on sediment and contaminant movement of a
100-year flood and other events or forces with a similar probability of occurrence (i.e., 0.01 in a year). A
similar minimum probability of occurrence may be appropriate for analysis of other extreme events such
as hurricanes and earthquakes. At some sites, especially where human and ecological risk is high, it may
be appropriate to analyze the effects of events with lower probabilities. Recorded characteristics of
physical events, such as current velocities or wave heights, may provide project managers with
parameters needed to calculate or model sediment movement. If information from historical records is
insufficient or the historical record is too short to be useful, project managers should consider obtaining
technical assistance to model a range of potential events to estimate effects on sediment movement and
transport. Section 2.9 of this chapter discusses modeling in more detail.
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2.8.3 Bioturbation
In many cases, within stable sediment deposits, the most important natural process bringing
contaminants to the sediment surface is bioturbation. Broadly speaking, bioturbation is the movement of
sediment by the activities of aquatic organisms. Although this movement may be in many directions, it is
the vertical mixing that is mainly of concern for project managers because it brings contaminants to the
bed surface, where most exposures occur. While many discussions of bioturbation are focused on
sediment dwelling animals, such as worms and clams, bioturbation may also include the activity of larger
organisms such as fish and aquatic mammals. The effects of bioturbation can include the mixing of
sediment layers, alteration of chemical forms of contaminants, bioaccumulation and transport of
contaminants from the sediment to interstitial/pore water or the water column. Many bottom-dwelling
organisms physically move sediment particles during activities such as locomotion, feeding, and shelter
building. These activities may alter sediment structure, biology, and chemistry, but the extent and
magnitude of the alteration depends on site location, sediment type, and the types of organisms and
contaminants present.
For purposes of a sediment stability analysis, the factor of most concern is the depth to which
significant physical mixing of sediment takes place, sometimes known as the "mixing zone." The mixing
zone is best determined by examination of sediment profile camera results, sediment cores, or other site
characterization data that displays the cumulative results of bioturbation through time. It is also useful to
be aware of the typical burrowing depths of aquatic organisms in environments similar to the site. Project
managers should keep in mind however that population density has a tremendous effect on whether
organisms present at the site may have a significant effect on the mixing zone. It is important to
understand the depth of the mixing zone in the various environments at a site because, where sediment is
physically stable and not significantly mobilized by ground water advection, contaminants below this
zone are unlikely to contribute to current or future risk at a site.
Typically, the upper 15 to 20 centimeters of sediment contain the greatest number of organisms
and activity, and are therefore of greatest interest when attempting to determine the depth of the mixing
zone or when evaluating current exposure of biota to contaminants, although this depth can be greater,
especially in marine environments. Highlight 2-11 provides examples of organisms that cause
bioturbation, their activity type, and the general depth of the activity. However, project managers should
also consider the activity type, the intensity of the activity, and organism population density, when
determining the extent to which bioturbation should be considered in site evaluation. For example, the
depth and effectiveness of bioturbation may be very different in a highly productive estuary and in a
heavily used commercial boat slip. .
A project manager should be aware of at least the following parameters when assessing the depth
of the mixing zone and the potential role bioturbation will play on a given sediment bed:
.
Site location - Salinity, water temperatures, depths, seasonal variation);
Sediment tvoe - Size distribution, organic and carbonate content, bulk density); and
OrJ!anism tyoe - Organisms either present and/or likely to recruit to and re-colonize
the area).
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Chapter 2: Remedial Investigation Considerations
.. . .. ... . .
"[[[-.-....,"""""""""""" ....................................
.............. ....... ......... -........."",-,,"""""""""""""""""".............................................. .....................................

.......... . :::~r~!n~*=m:::::::::::::::::::}:::AM:i.¥!~myij! .............. .:~!pli:::(::\r:::n... .............. .J{~i~f~ij~j) :::::::::::::::::
Tubificid worm Burrowing/Feeding 0-3cm Matisoff, Wang and McCall 1999 
(oligochaete)   Pennak 1978
Midge and Mayfly Burrowing/Feeding 0 -15 cm Matisoff and Wang 2000
(insects)   Pennak 1978
Crayfish (crustacean) Burrowing Ocm-3m Pennak 1978
Burbot (fish) Burrowing Ocm-30cm Boyer et al. 1990
Bristleworrn (polychaete) Burrowing 0 cm -15 cm Hylleberg 1975
Bamboo worm Burrowing/Feeding Ocm-20cm Rhoads 1967
(polychaete)   
Fiddler crab (crustacean) Burrowing 0 cm - 30.5 cm Warner 1977
Clam (bivalve) Burrowing Ocm-3cm Risk and Moffat 1977
Bristleworrn (polychaete) Burrowing Ocm-15cm Hylleberg 1975
Fiddler crab (crustacean) Burrowing 0 cm - 30.5 cm Warner 1977
Clam (bivalve) Burrowing 0 cm - 3 cm Risk and Moffat 1977
This analysis may be done for naturally deposited sediment as well as potential in-situ capping
material or dredging backfill material. Where bioturbation is likely to be a significant process, it is
important to evaluate the depth over which it causes significant mixing, using site-specific data and
assistance by technical experts, to assess alternative approaches for the site.
2.8.4
Predicting the Consequences of Sediment and Contaminant Movement
Depending on its extent, movement of sediment or contaminants mayor may not have significant
consequences for risk, cost, or other important factors at a specific site. A number of differing factors
may be important in determining whether expected or predicted movements are acceptable. Historical
records or monitoring data for contaminant concentrations in sediment and water during events such as
floods may be valuable in analyzing the increase in exposure and risk. Where this information is not
available or has significant uncertainty, models may also be very useful to help understand and predict
changes. This analysis should include not only increased risk from contaminant releases to the immediate
water body, but wherever those contaminants are likely to be deposited. Increased cost may include
remedy costs such as cap repair or costs related to contaminant dispersal, such as increased disposal cost
of downstream navigational dredging. There may also be societal or cultural impacts of contaminant

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Chapter 2: Remedial Investigation Considerations
Project managers should assess the impacts of contaminant release on potential receptors on a
site-specific basis, using information generated during the baseline human health and ecological risk
assessments. Where natural recovery is being evaluated, project managers should recognize that not only
the rate of net sedimentation, but also the frequency of erosive episodes, can help determine the rate of
recovery for surface sediment and biota. Where in-situ capping is being evaluated, project managers
should recognize that some amount of erosion and sediment transport may be acceptable and can be
incorporated into plans for remedial design and cap maintenance. Increased risk to human or ecological
receptors due to contaminant releases during dredging may be a related analysis when considering
dredging. Comparing the increased risks, costs, or other consequences of sediment disruption due to
natural causes or the remedy itself also may be an important part of the remedy selection process.
When evaluating in-situ remedy alternatives, the significance of potential harm due to re-
exposure of contaminated sediment or contaminated sediment redistribution is an important
consideration. Factors to be considered include the nature of the contaminants, the nature of the potential
receiving environment and biological receptors, and the potential for repair or recovery from the
disturbance. These factors can be used to evaluate risks, costs, and/or other effects of different events on
existing contaminated sediment or sediment remedies.
2.9
MODELING
This section briefly discusses the role of modeling in evaluating alternative remedies at sediment
sites. It is intended to assist project managers in deciding whether models can be a useful tool at a site,
and if so, what type of model (or level of analysis) should be considered. This section does not advocate
the use of models at every site, nor does it recommend specific models. Whether to use a model and what
model to use are site-specific decisions for which modeling experts should be consulted (e.g., U.S. EPA
2004c and 2004d). Guidance on the recommended process to follow in making these decisions is given
below. This section focuses on sediment transport models, but the general principles also apply to other
models, such as food web models. Technical assistance is available to project managers from EP A's
Superfund Sediment Resource Center (SSRC), where experts from inside and outside the Agency may be
accessed. Additional research about contaminated sediment transport and food web modeling is
underway at the Office of Research and Development (ORD) and project managers should monitor the
Superfund sediment Web site at htt,p:!/www.epa.gov/superfund/rcsources/sediment or contact their
region's ORD Hazardous Substance Technical Liaison for more information.
There is a wide range of assessment techniques, empirical models, and more robust computer
(i.e., multi-dimensional numerical) models that can be applied to contaminated sediment sites. Numerical
models are frequently applied to the most complex sites. These sites typically have a long history of data
collection, have documented contaminant concentrations in sediment and biota, and often have fish
consumption advisories already in place.
Models can be useful tools, even though they can be time consuming and expensive to apply at
complex sediment sites. Most modeling efforts require large quantities of site-specific data, and typically
a team of experienced modelers is needed. Nevertheless, models are helpful in that they give, when
properly applied, a more complete understanding of the transport and fate of contaminants than typically
can be provided by empirical data (from field or laboratory) alone. Modeling of contaminated sediment,
just as with other modeling, should follow a systematic planning and implementation process. In most
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Chapter 2: RefllJ!dial Investigation Considerations
cases, models are expected to complement environmental measurements and address gaps that exist in
empirical information. Examples of the uses of models include the following: .
Illustrating how contaminant concentrations vary spatially at a site. Empirical
information can provide useful benchmarks that can be interpolated or modeled to get a
better understanding of the distribution of contaminants;
Predicting contaminant fate and transport over long periods of time (e.g., decades) or
during episodic, high-energy events (e.g., tropical storm or low-frequency flood event);
Predicting future contaminant concentrations in sediment, water and biota to evaluate
relative differences among the proposed remedial alternatives, ranging from monitored
natural recovery to extensive removal; and
Comparing modeled results to observed measurements to show convergence of
information. Both modeling results and empirical data usually will have a measure of
uncertainty, and modeling can help to examine the uncertainties (e.g., through sensitivity
analysis) and refme estimates, which may include indications for where to sample next.
The use of models at sediment sites is not limited to the remedy selection phase. Most sites that
do use models for evaluation of proposed remedies have previously developed a mass balance or other
type of model during the development of the baseline risk assessment to quantify the relationships among
contaminant sources and exposure pathways. At these sites, the same model is generally used to predict
the response of the system to various cleanup options. Where this is done, it is important to continue to
test the model predictions by monitoring during the remedy implementation and post-remedy phases to
assess whether cleanup is progressing as predicted by the model. Where it is not, information should be
relayed to researchers so that the model can be modified or re-calibrated and lead to more accurate future
predictions.
2.9.1
Sediment/Contaminant Transport and Fate Model Characteristics
A sediment/contaminant transport and fate model typically is a mathematical or conceptual
representation of the movement of sediment and associated contaminants, and the chemical fate of those
contaminants, as governed by physical, chemical and biological factors, in bodies of water. These models
are inherently limited by our current understanding of the factors governing these process and our ability
to quantify them (Le., represent mathematically their interactions and effects on the transport and fate of
sediment and contaminants). Even the most complex sediment model may be a relatively simplistic
representation of the movement of sediment through natural and engineered water bodies. It may be
simplistic due to the following:
Limitations in our understanding of natural systems, as reflected in the current state-of-
the-science;
Empiricism inherent in predicting flow-induced sediment transport, bank erosion, and
non-point source loads;
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Chapter 2: Remedial Investi/{ation Considerations
.
The relatively coarse spatial and temporal discretization (i.e., breaking space and time
into blocks) of the water body being modeled when using a numerical model; and
The inability to realistically simulate geomorphological processes such as river
meandering, bank erosion, and localized effects (e.g., due to natural debris or beaver
dams).
Nevertheless, sediment/contaminant transport and fate models generally are useful tools when
properly applied, although they are data intensive and require specialized expertise to apply and interpret.
This type of model is one of several tools that could assist a remedial decision.
Currently, there are two basic types of sediment transport models: conceptual and mathematical
models. In addition there are several different types of mathematical models. General types of models
are described in Highlight 2-12, and an example of a conceptual site model is presented in HigWight 2-13.
. .... .. .............. .................... ..... ..... ............... . ... ... . ..
",',',',',',',',',',',",',',',",','.",",",",",".",",",",",",",".",".",",",",',', .".".',",",",".'.".",".",".".",",",".",".",".",".",".",".'.'.',".".".".",'.'.".'.',','.'.",".",".",".",".",".','.",".",'.',',','.',",",',',',',",",".",",".".".".".".".".".".".". ','.',",',",',",",",',",",",".",".",".",".",".",".",".",".",",".",".",",".','.',',',".',',".'.'.','.',','.','.','.",',",",".".'.".
........................................ [[[ .............................................
.:::.:::::::::::..::fltil1l~9h~:?f~g::R~y:gl1~~~~!~I.~:Pf:~h!M~jg![YP!~p~$~~~I!i@ijygp~~m!~~gJ::
...... .:::.:<:::':::":.:':::'::':::::mt~9~PP!~:~n#.:F!mM~~~~:.::::::::<.......::::::.....:::::::::::::::
Conceptual Model:
.......
.........
.......
Identifies the following: 1) contaminants of potential concem; 2) sources of the contaminants; 3) physical and
biogeochemical processes and interactions that control the transport and fate of sediment and associated
contaminants; 4) exposure pathways; and 5) ecological and human receptors.
Mathematical Model:
A set of equations that quantitatively represent the processes and interactions identified by the conceptual model
that govern the transport and fate of sediment and associated contaminants. Mathematical models include
analytical, regression, and numerical models.
Analytical Model:
An analytical model is one or more equations (e.g., simplified - a linearized, one-dimensional form of the
advection-diffusion equation) for which a closed-form solution exists. This type of model would not be applicable
at most sediment sites due to the complexities associated with the forcing hydrodynamics and spatial and temporal
heterogeneities in sediment and contaminant properties/characteristics.
Regression Model:
A regression model is a statistically determined equation that relates a dependent variable to one or more
independent variables. A stage-discharge rating curve is an example of a regression model in which stage (e.g.,
water level) and discharge (e.g., amount of water flow) are the independent and dependent variables, respectively.
Numerical Model:
In a numerical model, an approximate solution of the set of governing differential equations is obtained using a
numerical technique. Examples of numerical techniques include finite difference and finite element methods. A

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Chapter 2: Remediallnvesti1:ation Considerations
........ .:: High"i~~(#f:1~i:$afu~iJ:'C9ri2~PtY~I.'~!~M9~~(FS~~~iHgB:~:$~dim~~tiWater:lnt~r~tHok::'
....-..... .......'.
......,..........."
"....................
',,',"n ",........
.. ................
. ....
....
.. .
........... . ...
",-",-,","""
.....,...........
...
. .
. ....
.....
....
.. ..."
n..
.. .
.... . .
......."
'..."
... .
Ground Water
Ground Water
. .
Sorption!
Desorption
Diagenesis
Source: Modified from Sediment Management Workgroup (SMW3)
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Chapter 2: Remedial Investigation Considerations
2.9.2
Determining Whether A Mathematical Model is Appropriate
Mathematical transport and fate models can be time-intensive and expensive to apply, both in
tenns of costs to collect the data required for the models as well as to perfonn the modeling study, and
their use and interpretation generally require specialized expertise. Because of this, mathematical
modeling is not recommended for every sediment site. In some cases, existing empirical data and new
monitoring data may be sufficient to support a decision. A mathematical modeling study is usually not
warranted for very small (i.e., localized) sites, where cleanup may be relatively easy and inexpensive.
However, mathematical modeling would generally be recommended for large or complex sites, especially
where it is necessary to predict contaminant transport and fate over extended periods of time to evaluate
relative differences among possible approaches. Mathematical modeling becomes especially important
when the existing empirical data are insufficient to predict future scenarios.
Project managers should use the following series of questions to help guide the process of
deciding whether to use a site-specific mathematical model:
.
Have the questions or hypotheses that the model is intended to answer been detennined?
.
Are historical data and/or simple quantitative techniques available to answer these
questions with the desired accuracy?
Have the spatial extent, heterogeneity and levels of contamination at the site been
dermed?
.
Have all significant ongoing sources of contamination been dermed?
Do sufficient data exist to support the use of a mathematical model, and if not, are time
and resources available to collect the required data to achieve the desired level of
confidence in model results? and
.
Are time and resources available to perfonn the modeling study itself?
If the decision is made that some level of mathematical modeling is appropriate, the following
section should assist project managers in deciding what level of analysis (i.e., what type of model) should
be used.
2.9.3
Determining the Appropriate Level of Model
When the decision is made that a mathematical model is appropriate at a site, project managers
should generally consider three steps in detennining what level of modeling to use. It is important to
consider all three steps in order. In some cases, these three steps may be more useful when perfonned in
an iterative fashion (for example, based on additional data analysis or from results obtained during Step 3,
it may become apparent that the conceptual site model should be modified).
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Chapter 2: Remedial Investi/(ation Consitkrations
Step 1: Develop Conceptual Site Model
Development of a Conceptual Site Model (CSM) is recommended as the key ftrst step in this
process. As described in Section 2.2, a CSM identiftes the processes and interactions that typically
control the transport and fate of contaminants, including sediment associated contaminants. If this step is
not performed, then the decision of what level of modeling is appropriate may be made with less than the
requisite information that might be needed to make a scientiftcally defensible decision.
The development of a CSM usually requires examination of all existing site data to assist in
determining the signiftcant physical and biogeochemical processes and interactions. Relatively simple
quantitative expressions of key transport and fate processes using existing site data, such as presented by
Reible and Thibodeaux (1999) or Cowen et al. (1999), may help in identifying those processes that are
most signiftcant at the site.
Step 2: Determine Processes that Can and Cannot be Modeled
This step concerns determining if all significant processes and interactions that control the
transport and/or fate of sediment contaminants, as identifted in the CSM, can be simulated with one or
more existing sediment transport and fate models. If it is determined that there are existing models
capable of simulating at a minimum the most signiftcant (i.e., ftrst-order) processes and interactions, then
the project manager should (using the appropriate technical experts) identify the types of models (e.g.,
analytical, regression, numerical) that have this capability and eliminate those types of models that do not
have this capability from further consideration.
Mathematical models (in particular numerical models) that can simulate most of the processes
that control the transport and fate of sediment and contaminants in water bodies (including a wide variety
of physical, chemical, and biological processes) have been developed. Highlight 2-14 depicts the inter-
relationship of some major processes and the type of model with which they are associated. Depending
on the needs at the site, models or model components ("modules") may link many of these processes into
one model. Examples of the processes that can be modeled include the following:
Land and air: Physical processes that result in loading of contaminants to water bodies
may include point discharges, overland flow (i.e., runoff), discharge of ground water,
NAPL seeps, and air deposition;
Water column: Physical processes that may result in movement of dissolved or sediment-
sorbed contaminants include transport via the water's ambient flow (advection),
diffusion, and settling of sediment particles containing sorbed contaminants;
Sediment bed: Important physical processes include the movement of pore water and
dissolved contaminants, seepage into and out of the sediment bed and banks, and the
mixing of dissolved and sediment-sorbed contaminants by bioturbation. In addition, both
sorbed and dissolved material may be exchanged between the water column and sediment
bed due to sediment deposition and resuspension or erosion; and
Water column and sediment bed: Physiochemical processes influencing the fate and
transport of contaminants include two-phase and three-phase chemical partitioning as
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Chapter 2: Remedial Investigation Considerations
described below. Biogeochemical reaction processes influencing the fate of
contaminants include speciation, volatilization, anaerobic gas formation, hydrolysis,
oxidation, photolysis, biotransformation, and biological uptake.
.......
':'Hiilj~!~h~'?S14~~ijffiit~::qpijtJmtijijffl~i*~9$.9.~~MI~i~h~Ft~m~w~t~
. .....
......
......
MOIELS
t+pod}nuricl
Rlid Transport
Sedmert
Transport
I
1
ChenicaJ Fae
and Transport

Volatilization
Food Chain
BioacctmJ\atioo
AIR
I1sso1ved
Oganic
Carbon(!XJC)
Partitioning
~
WATER
I-~~I
I1sso1ved
Carpona1t (DS)
Pa1itioning
~
Net
SedirrentatiCll

~
I
Sdtling Soour
+
PartiaJlate
Corrponent
(PAR1)
Predat.
Interfacial
Bed Layer
[)!fusion
Groundt.ater
Pdvection
Irtermedicte
Layer
am~lo
Deep Bed
Pa1itiClling
BED
Deep Bed
[)!fusion am BJriailo
Deep Bed
Source: NRC 2001
In Highlight 2-14 above and in other modeling discussions, generally "two-phase partitioning"
refers to modeling the contaminant in two parts or phases: a bioavailable dissolved fraction and a
generally non-bioavailable particulate fraction. In "three-phase partitioning," contaminant concentrations
normally are considered in three phases: the bioavailable dissolved phase, a generally non-bioavailable
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Chapter 2: Remedial Investil(ation Considerations
dissolved organic carbon phase, and a generally non-bioavailable particulate organic carbon phase. A
three-phase model usually is appropriate for waters in which internally produced organic material (e.g.,
produced in-situ) is a significant proportion of total solids as compared to other organic and inorganic
matter supplied by watershed runoff, bank and bed erosion.
If it is determined that there are no existing models capable of simulating, at a minimum, the most
significant (i.e., first-order) processes and interactions, then project managers may need to rely on other
tools or methods for evaluating proposed approaches, or develop and test new models or modules. This
latter approach is a research and development level effort and normally should be avoided.
Examples of processes that cannot be dynamically simulated, even using state-of-the-art sediment
transport models, may include geomorphological processes such as the development of meanders in
streams and rivers, and bank cutting/erosion. There are empirical methods for estimating the total
quantity of sediment that would be introduced to a water body due to the failure of a river/stream bank,
but this process normally cannot be dynamically simulated.
Step 3: Select an Appropriate Model
If one or more models or types of mathematical models exist that are capable of simulating the
controlling transport and fate processes and interactions, then project managers should use the process
described above to choose the appropriate type of model (i.e., level of analysis). If the decision is made
to apply a numerical model at a sediment site, selection of the most appropriate contaminated sediment
transport and fate model to use at a specific site is one of the critical steps in a modeling program. During
this process, familiarity with existing sediment transport models is essential. Comprehensive technical
reviews of available models have been conducted by the EPA's National Exposure Research Laboratory
(see U.S. EPA 2004c and U.S. EPA 2004d).
Where numerical models are used, the following components typically should be performed to
yield a scientifically defensible modeling study: verification, calibration, validation, sensitivity analysis,
and uncertainty analysis. The project manager should be aware that the terms "verification" and
"validation" are frequently used interchangeably in modeling literature. These terms, for purposes of this
guidance, mean:
Model verification: Evaluating the model theory, consistency of the computer code with
model theory, and evaluation of the computer code for integrity in the calculations. This
should be an ongoing process, especially for newer models. Model verification should be
documented, or the model or model component should be peer-reviewed by an
independent party if it is new;
Model calibration: Using site-specific information from a historical period of time to
adjust model parameters in the governing equations (e.g., bottom friction coefficient in
hydrodynamic models) to obtain an optimal agreement between a measured data set and
model calculations for the simulated state variables;
Model validation: Demonstrating that the calibrated model accurately reproduces known
conditions over a different period of time with the physical parameters and forcing
functions changed to reflect the conditions during the new simulation period, which is
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Chapter 2: Remedial Investigation Considerations
different from that used for calibration. The parameters adjusted during the calibration.
process should NOT be adjusted during validation. Model simulations during validation
should be compared to the measured data set. If an acceptable level of agreement is
achieved between the data and model simulations, then the model can be considered
validated as an effective tool, at least for the range of conditions defmed by the
calibration and validation data sets. If an acceptable level of agreement is not achieved,
then further analysis should be carried out to determine possible reasons for the
differences between the model simulations and measured data during the validation
period. The latter sometimes leads to refmement of the model (e.g., using a finer model
grid) or to the addition of one or more physical/chemical processes that are represented in
the model;
.
Sensitivity analvsis: This process 'consists of varying each of the input parameters by a
fixed percent (while holding the other parameters constant) to determine how the
predictions vary. The resulting variations in the state variables are a measure of the
sensitivity of the model predictions to the parameter whose value was varied; and
.
Uncertainty analvsis: This process consists of propagating the relative error in each
parameter (that was varied during the sensitivity analysis) to determine the resulting error
in the model predictions. A probabilistic model (e.g., Monte Carlo Analysis) is one
method of performing an uncertainty analysis (see guidance on Superfund's risk Web
page at htto://www.cva.gov/suvcrfund/vrograms/risk). In general, while quantitative
uncertainty analyses are possible and practical to perform with watershed loading models
and food chain/web models, they are not so (at the current time) for fate and transport
models.
The extent to which these components of a modeling study are performed using verified models
can determine to a large degree the defensibility of the modeling project. If a verified model has not been
sufficiently calibrated or validated for a specific site, and if sensitivity and uncertainty analyses have not
been performed, then the modeling study may lack defensibility and be of little value. Where possible,
project managers should use verified models that are in the public domain, calibrated and validated to
site-specific conditions. Proprietary models may also be useful, but project managers should be aware
that they contain code that has not been shared publicly and may not have been verified. The
interpretation of modeling results and the reliance placed on .those results should heavily consider the
extent of documented model verification, calibration, validation, sensitivity analysis, and uncertainty
analysis performed.
2.9.4
Peer Review
It is EP A policy that a peer review of numerical models is often appropriate to ensure that a
model provides decision makers with useful and relevant information. Project managers should use
EP A's Guidance for Conducting External Peer Review of Environmental Regulatory Models (U.S. EP A
1994c) and Peer Review Handbook (U.S. EPA 2000d) to determine whether a peer review of a model is
appropriate and, if so, what type of peer review should be used. As a rule of thumb, when a model is
being used outside the niche for which it was developed, is being applied for the first time, or is a critical
component of a decision that is very costly, a peer review should be performed. In addition, project
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Chapter 2: Remedial Investigation Considerations
managers should refer to OSWER Directive 9285.6-08, Principles for Managing Contaminated
Sediments at Hazardous Waste Sites, Principle 6 (U.S. EPA 2002a, see Appendix A).
EP A peer review guidance for models also notes that: "Environmental models that may form part
of the scientific basis for regulatory decision making at EP A are subject to the peer review policy.
However, it cannot be more strongly stressed that peer review should only be considered for judging the
scientific credibility of the model including applicability, uncertainty, and utility (including the potential
for misuse) of results and not for directly advising the Agency on specific regulatory decisions stemming
in part from consideration of model output" (U.S. 1994c). Peer reviewers advise the Agency regarding
proper use and interpretation of a model; it is then the Agency's task to properly apply that advice to
regulatory decisions.
.....
Highlight 2-15 summarizes some important points to remember about modeling at sediment sites.
1.
Consider modeling results in conjunction with empirical data to inform site decision-making. Mathematical
models are useful tools that, in conjunction with site environmental measurements, can be used to characterize current
site conditions, predict future conditions and risks, and evaluate the effectiveness of remedial alternatives in reducing
risk. Modeling results generally should not be relied upon exclusively as the basis for cleanup decisions.
2.
Develop and refine a conceptual site model that identifies the key areas of uncertainty where modeling
information may be needed. When evaluating if a model is needed and in deciding which models might be
appropriate, a conceptual site model should be developed that identifies the key exposure pathways, the key sediment
and water-body characteristics, and the major sources of uncertainty that may affect the effectiveness of potential
remedial alternatives (e.g., capping, dredging, and/or monitored natural recovery).
3.
Consider site complexity before deciding if a mathematical model is necessary. Site complexity and
controversy, available resources, project schedule, and the level of uncertainty in model predictions that is acceptable,
are generally the critical factors in determining whether a simple, intermediate, or advanced level model should be
developed and used. Potential remedy cost and magnitude of risk are generally less important, but they can
significantly affect the level of uncertainty that is acceptable.
4.
Determine what model output data are needed to facilitate decision-making. As part of problem formulation, the
RPM should consider: 1) what site-specific information is needed to make the most appropriate remedy decision (e.g.,
degree of risk reduction that can be achieved, correlation between sediment cleanup levels and protective fish tissue
levels, time to achieve risk reduction levels, degree of short-term risk), 2) what model(s) are capable of generating this
information, and 3) how the model results can be used to help make these decisions. Site-specific data collection
should concentrate on input parameters that will have the most influence on model ,outcome.
5.
Understand and explain model uncertainty. The model assumptions, limitations, and the results of the sensitivity
and uncertainty analyses should be clearly presented to decision makers and should be clearly explained in decision
documents such as proposed plans and RODs.
6.
Conduct a complete modeling study. If an intermediate or advanced level model is used in decision making, the
following components should be included in every modeling effort:
Model verification (or peer-review if a new model is used)
Model calibration
Model validation
Sensitivity analysis
Uncertainty analysis
7.
Learn from modeling efforts. If post-remedy monitoring data demonstrate that the remedy is not performing as
expected (e.g., fish tissue levels are much higher than predicted), consider sharing these data with the modeling team
to allow them to perform a post-remedy validation of the model. This could provide a basis for model enhancements
that would improve future model performance at other sites. If needed, this information could also be used to re-
estimate the time frame when RAOs are expected to be met at the site.
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Chapter 3: Feasibility Study Considerations
3.0
FEASIBILITY STUDY CONSIDERATIONS
Generally, the purpose of a feasibility study for a contaminated sediment site is to develop and
evaluate a number of alternative methods for achieving the remedial action objectives (RAOs) for the site.
This process lays the groundwork for proposing and selecting a remedy for the site that best eliminates,
reduces, or controls risks to human health and the environment. The feasibility study process is described
in the U.S. Environmental Protection Agency's (EPA's) Guidancefor Conducting Remedial
Investigations and Feasibility Studies under CERCLA, also referred to as the "RIfFS Guidance" (U.S.
EPA 1988a). The proposed plan and record of decision (ROD) process is described in the EPA's Guide
to Preparing Superfund Proposed Plans, Records of Decision, and other Remedy Selection Decision
Documents, also referred to as the "ROD Guidance" (U.S. EPA 1999a). This chapter is intended to
supplement existing guidance by offering sediment-specific guidance about developing alternatives,
considering the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) criteria,
identifying applicable or relevant and appropriate requirements (ARARs), estimating cost, and
implementing institutional controls. Chapters 4,5, and 6 present more detailed guidance on evaluating
alternatives based on the three major approaches for sediment: monitored natural recovery (MNR), in-situ
capping, and dredging (or excavation) with treatment or disposal.
Although this chapter focuses on remedial alternatives for managing contaminated sediment,
project managers beginning this stage of site management should keep in mind that the fIrst step at almost
every sediment site should be to implement measures to control any significant ongoing sources and to
evaluate the effectiveness of those controls. Until this is done, appropriately evaluating alternatives for
sediment may be difficult. However, it may be appropriate to evaluate implementation of interim
sediment clean-up measures prior to completing source control in order to control further dispersal of
sediment hot spots or reduce risks to human health and the environment due to sediment contamination.
In addition, project managers should keep in mind that flexibility is frequently important in the
feasibility study process at sediment sites. Iterative or adaptive approaches to site management are likely
to be appropriate at these sites. Also, project managers should consider pilot testing various approaches
as part of the feasibility study process.
3.1
DEVELOPING REMEDIAL ALTERNATIVES FOR SEDIMENT
As described in Section 1.3.1 Remedial Approaches, there are typically three major approaches
that can be taken to reduce risk from contaminated sediment when source control measures are
insufficient to reduce risks: MNR, in-situ capping, and sediment removal by dredging or excavation.
Hybrid approaches may combine these three. A fourth approach, in-situ treatment, is currently under
development and may become a viable alternative in the future, especially in combination with in-situ
caps. Highlight 1-5 in Chapter I briefly summarizes these major approaches for sediment sites.
Project managers should consider the following steps, which build on EP A' s RI/FS Guidance by
adding details specifIc to sediment, when developing alternatives at sediment sites:
1.
Develop remedial action objectives specifying the contaminants and media of interest,
exposure pathways, and remediation goals that permit a range of alternatives to be
developed including each of the three major approaches (natural recovery, capping, and
removal), and that consider state and local objectives for the site;
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Chapter 3: Feasibility Study Considerations
2.
Identify estimated volumes or areas of sediment to which the approaches may be applied,
taking into account the need for protectiveness as identified in the remedial action
objectives and the biological, chemical and physical characteristics of the site;
3.
Develop additional detail concerning the equipment, methods, and locations to be
evaluated for each alternative, including the three major approaches (e.g., potential
natural recovery processes, potential cap materials and placement methods, number and
types of dredges or excavators, transport methods, treatment methods, type of disposal
units, general disposal location, need for monitoring and/or institutional controls);
4.
Develop additional detail concerning known major constraints on each alternative,
including the three major approaches at the site (e.g., need to maintain flow capacity for
flood control, need to accommodate navigational dredging);
5.
To the extent possible with information available at this stage of the FS, identify the time
frame(s) in which the alternatives are expected to achieve cleanup levels and remedial
action objectives; and
6.
Assemble the more detailed methods into a set of alternatives representing a range of
options, including natural recovery, in-situ capping, and removal options or combination
of options, as appropriate.
This process often is best done in an iterative fashion, especially at complex sites. For example,
investigation into equipment and disposal options for sediment removal may lead to evaluation of a
variety of time frames for achieving risk reduction goals. Typically, the number and type of remedial
alternatives that a project manager develops for any site is a site-specific decision. The project manager
should take into account the size, characteristics, and complexity of the site. However, due to the limited
number of approaches that may be available for contaminated sediment, generally project managers
should evaluate each approach carefully, including the three major approaches (MNR, in-situ capping,
and removal through dredging or excavation) at every sediment site at which they might be appropriate.
3.1.1
Alternatives which Combine Approaches
At sites with multiple water bodies or sections of water bodies with differing characteristics or
uses, or differing levels of contamination, project managers have found that alternatives that combine a
variety of approaches are frequently the most promising. In many cases, institutional controls are also
part of many alternatives (see Section 3.5, Institutional Controls). The following examples illustrate a
few examples of how different approaches might be combined into alternatives for evaluation at sediment
sites:
An alternative might combine a variety of dredging, transport, and disposal methods that
remove differing volumes of contaminated sediment "hot spots," with capping or MNR
for more widespread areas oflessor contamination;
An alternative might combine armored in-situ capping of contaminated sediment which is
more erodible or hot spot areas causing higher risk, with MNR for more highly
depositional areas;
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Chapter 3: Feasibility Study Considerations
An alternative might combine dredging in federal navigation channels or for areas where
there is insufficient water depth to maintain navigation or flood capacity with a cap, with
in-situ capping of flood plain, intertidal or under-pier areas where a less costly approach
is desired; and
An alternative might combine thin-layer placement (see Chapter 4, Monitored Natural
Recovery) with MNR where the natural rate of sedimentation is insufficient to bury
contaminants in a reasonable time frame.
3.1.2
The No-Action Alternative
The NCP at Title 40 Code of Federal Regulations (40 CFR) ~300.430(e)(6) provides that the no-
action alternative should be considered at every site. The no-action alternative should reflect the site
conditions described in the baseline risk assessment and remedial investigation. This alternative may be a
no-further-action alternative if some removal or remedial action has already occurred at the site, such as
under another ROD.
No-action or no-further-action alternatives normally do not include any treatment, engineering
controls, or institutional controls but may include monitoring. For example, at a site where risk is
acceptable (e.g., because contaminant levels in surface sediment and biota are low and the site is stable),
but the site contains higher levels of contamination at depth, it may be advisable to periodically evaluate
the continued stability of buried contaminants. A "no action" alternative may include monitoring of these
buried contaminants. Project managers and others should not confuse this however with MNR, where
natural processes are relied upon to reduce an unacceptable risk to acceptable levels. The difference is
often the increased level and frequency of monitoring included in the MNR alternative and the fact that
the MNR alternative includes a cleanup level and expected time frame for achieving that level. Project
managers should normally evaluate both a No Action and an MNR alternative at sediment sites.
If a no-action or no-further action alternative does not meet the N CP' s threshold criteria allowed
in 40 CFR ~300.430 (i.e., protection of human health and the environment and meeting applicable or
relevant and appropriate requirements), it is not necessary to carry it though to the detailed analysis of
alternatives. However, the ROD should explain why the no-action alternative was dropped from the
analysis. Chapter 7, Remedy Selection Considerations, includes guidance on when it may be appropriate
to select a no-action alternative.
3.1.3 In-Situ Treatment Alternatives
Generally, in-situ treatment is an approach that involves the biological, chemical, or physical
treatment of contaminated sediment in place. This approach is currently under development by
researchers. Although significant technical limitations exist currently, active laboratory, bench and field
scale pilot studies may make it a viable alternative in the future. Project managers are encouraged to
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Chapter 3: Feasibility Study Considerations
track the development of in-situ treatment methods. Potential in-situ treatment methods include the
following:
Biolo,?ical Treatment: Microbial degradation of contaminants by the addition of
enhancement materials such as oxygen and nutrients (e.g., nitrogen), or microorganisms
into the sediment or a reactive cap;
.
Chemical Treatment: The destruction of contaminants through oxidation and
dechlorination processes by providing chemical reagents, such as permanganate,
hydrogen peroxide, or potassium hydroxide, into the sediment or a reactive cap; and
Immobilization Treatment: Solidification or stabilization by adding Portland cement, fly
ash, limestone, or other additives to the sediment for encapsulating the contaminants in a
solid matrix and/or chemically altering the contaminants by converting them into a less
bioavailable, less mobile, or less toxic form.
Techniques for in-situ treatment of sediment are in the early stages of development, and few
methods are currently commercially available. Experiences gained to date in experimental or small-scale
applications of in-situ remedies have indicated that technical limitations to the effectiveness of available
in-situ treatments continue to exist. For example, in-situ remedies relying on the addition of required
substrates and nutrients, reagents, or catalysts have been developed for some contaminants, such as
polychlorinated biphenyls (PCBs), but developing an effective in-situ delivery system to add and mix the
needed levels of reagents to contaminated sediment is more problematic. The lack of an effective
delivery system has also hindered the application of in-situ stabilization systems [National Research
Council (NRC) 2001]. However, new developments may make this a more promising approach in the
future.
Several EPA-funded bench and field studies in this area are underway. These include studies
conducted by EPA's Superfund Innovative Technology Evaluation (SITE) program, which encourages
the development and routine use of innovative treatment, monitoring, and measurement technologies.
The SITE program is in the process of demonstrating in-situ treatment technologies (Highlight 3-1).
More information on the SITE program is available at hftp://ww-w.epa.gov/ORD/SlTE/. Also, the
Hazardous Substance Research Center (HSRC) - South and Southwest, currently centered at Louisiana
State University, has received funding for research about in-situ treatment and other innovative capping
alternatives for contaminated sediment in the Anacostia River in Washington, D.C. More information on
this program is available from the HSRC at htlp:i/www.hsrc.org.
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Chapter 3: Feasibility Study Considerations
3.2
NCP REMEDY SELECTION CRITERIA
The NCP at 40 CFR ~300.430(e)(9) establishes a framework of nine criteria for evaluating
remedies. These criteria address the requirements of the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA), and additional technical and policy considerations that are
important for selecting remedial actions. Many of these criteria are also important for actions under the
Resource Conservation and Recovery Act (RCRA).
The NCP at 40 CFR ~300.430(e)(7) describes a method for screening potential alternatives prior
to developing detailed alternatives when a number of alternatives are being considered at a site. Only the
alternatives judged as the best or most promising following this screening should be retained for further
development and detailed analysis. The three broad criteria for screening preliminary remedial
alternatives are: 1) effectiveness; 2) implementability; and 3) cost. Although a screening level analysis
may be necessary in some cases, due to the relatively limited number of approaches available for
sediment, project managers generally should not screen out any of the major approaches early in the FS.
More detailed discussions of what should be addressed under each of the nine criteria can be
found in the ROD Guidance (U.S. EPA 1999a) and the RIfFS Guidance (U.S. EPA 1988a). The
following provides a summary of the nine criteria (U.S. EPA 1988a):
Threshold Criteria
.,
Overall Protection o(Human Health and the Environment: This criterion is used to
evaluate how the alternative as a whole achieves and maintains protection of human
health and the environment;
Comoliance with Applicable or Relevant andAoorooriate Requirements (ARARs): This
criterion is used to evaluate whether the alternative complies with chemical-specific,
action-specific, and location-specific ARARs or if a waiver is justified. In addition to
ARARs, this criterion also commonly includes whether the alternative considers other
criteria, advisories, and guidance that are to be considered at the site. This criterion is
discussed further with respect to contaminated sediment in Section 3.3;
Balancing Criteria
LonJ;!-Term Effectiveness and Permanence: This criterion includes an evaluation of the
magnitude of human health and ecological risk from untreated contaminated materials or
treatment residuals remaining after remedial action has been concluded (known as
residual risk), and the adequacy and reliability of controls to manage that residual risk. It
also includes an assessment of the potential need to replace technical components of the
alternative, such as a cap or a treatment system, and the potential risk posed by that
replacement. This criterion is discussed further with respect to contaminated sediment in
Section 3.4;
.
Reduction of Toxicity. Mobility. and Volume Throuf:h Treatment: This criterion refers to
the evaluation of whether treatment processes can be used, the amount of hazardous
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Chapter 3: Feasibility Study Considerations
material treated, including the principal threat that can be addressed, the degree of
expected reductions, the degree to which the treatment is irreversible, and the type and
quantity of treatment residuals. This criterion is discussed further with respect to
contaminated sediment in the chapters related to the individual remedies;
Short-Term Effectiveness: This criterion includes an evaluation of the effects of the
alternative during the construction and implementation phase until remedial objectives
are met. This criterion includes an evaluation of protection of the community and
workers during the remedial action, the environmental impacts of implementing the
remedial action, and the expected length of time until remedial objectives are achieved.
This criterion is discussed further with respect to contaminated sediment in the chapters
related to the individual remedies;
Implementabilitv: This criterion is used to evaluate the technical feasibility of the
alternative, including construction and operation, reliability, monitoring, and the ease of
undertaking an additional remedial action if the remedy fails. It also considers the
administrative feasibility of activities needed to coordinate with other offices and
agencies, such as for obtaining permits for off-site actions, rights of way, and institutional
controls, and the availability of services and materials necessary to the alternative, such
as treatment, storage, and disposal facilities. This criterion is discussed further with
respect to contaminated sediment in the chapters related to the individual remedies;
.
Cost: This criterion includes an evaluation of direct and indirect capital costs, including
costs of treatment and disposal, annual costs of operation, maintenance, monitoring of the
alternative, and the total present worth of these costs. This criterion is discussed further
with respect to contaminated sediment in Section 3.5;
Modifying Criteria
State (Or Support AgenCJ() Acceptance: This criterion is used to evaluate the technical
and administrative concerns of the state (or the support agency, in the case of state-lead
sites) regarding the alternatives, including an assessment of the state or the support
agency's position and key concerns regarding the alternative, and comments on ARARs
or the proposed use of waivers. Tribal acceptance is also evaluated under this criterion.
This criterion is discussed further with respect to contaminated sediment in Chapter 1,
Section 1. 5; and
.
Communitv Acceptance: This criterion includes an evaluation of the concerns of the
public regarding the alternatives. It determines which component of the alternatives
interested persons in the community support, have reservations about, or oppose. This
criterion is discussed further with respect to contaminated sediment in Chapter 1, Section
1.6.
Additional guidance about how to apply these criteria to sediment alternatives is found
throughout the guidance, as indicated above. In addition, Chapter 7, Remedy Selection Considerations,
summarizes general considerations of each of the nine criteria with respect to the three major approaches.
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Chapter 3: Feasibility Study Considerations
3.3 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS FOR
SEDIMENT ALTERNATIVES
Pursuant to CERCLA ~12l(d)(4), all remedial actions at CERCLA sites must be protective of
human health and the environment. In addition, on-site actions need to comply with the substantive
portions of ARARs unless the ARAR is waived. ARARs may be waived only under limited
circumstances. Compliance with administrative procedures, such as permits, is not required for on-site
response actions. Off-site actions must comply with both substantive and administrative requirements of
legally applicable laws and regulations.
.
Sediment cleanup levels for response actions under CERCLA generally are based on site-specific
risk assessments, but occasionally are based on ARARs. Project managers may also consider non-
promulgated advisories or guidance issued by federal, state or tribal governments, frequently called TBC
('to be considered"). While TBCs may not be legally binding on their own, and thus do not have the
same status as ARARs, TBCs can be used as a basis for making cleanup decisions. The project manager
should refer to CERCLA Compliance with Other Laws Manual (U.S. EPA 1988b). Also, the preamble to
the fmal NCP (55 Federal Register (FR) 8741) states that, as a matter of policy, it is appropriate to treat
Indian tribes as states for the purpose of identifying ARARs (see NCP at 40 CFR ~300.5l5(b) for
provisions dealing with tribal governments).
The process of identifying ARARs typically begins in the scoping phase of the RIfFS, continues
until the ROD is finalized, and may be reexamined during the five-year review process. Identification of
ARARs should be done on a site-specific basis and usually involves a two-part analysis. First, a
determination of whether a given requirement is applicable should be made, and second, if it is not
applicable, then a determination should be made as to whether it is relevant and appropriate. Highlight
3-2 lists some examples of potential federal, state, and tribal ARARs for sediment sites and actual and
hypothetical examples of how remedial strategies have been adapted to comply with ARARs.
For more information about ARARs, the project manager should consult the Compendium of
CERCLA ARARs Fact Sheets and Directives (U.S. EP A 1991a), and the Assessment and Remediation of
Contaminated Sediments (ARCS) Program Remediation Guidance Document (U.S. EPA 1994d).
As part of the ARARs analysis, project managers, in consultation with the site attorney, should
consider appropriate requirements promulgated under the Clean Water Act (CW A). As described in the
examples in Highlight 3-2, federal water quality criteria as well as state-promulgated regulations
including state water quality standards may be potential ARARs for surface water when water is
discharged from dewatering or treatment areas or as effiuent from CDFs. Furthermore, some states may
have their own promulgated sediment quality standards that may be potential ARARs for sediment.
Total maximum daily loads (TMDLs) established or approved by the EP A under the CW A are
planning tools designed to reduce contributing point and non-point sources of pollutants in water quality
limited segments (wQLS). TMDLs calculate the greatest amount of loading of a pollutant that a water
body can receive without exceeding CW A water quality standards. TMDLs are usually established by the
states, territories, or authorized tribes and approved by the EP A. Effluent limits in point source national
pollutant discharge elimination system (NPDES) permits should be consistent with the assumptions and
requirements in a wasteload allocation in an approved TMDL.
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Chapter 3: Feasibility Study Considerations
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Clean Water Act ~304(a)
EPA publishes national recommended Ambient Water
Quality Criteria (AWQC) for the protection of aquatic life and
human health. CERCLA ~121(d)(2) requires EPA to
consider whether nationally recommended AWQC should be
relevant and appropriate requirements at a site. CERCLA
~121 (d)(2)(B) establishes the guidelines to consider in
determining when AWQC may be relevant and appropriate
requirements, including consideration of the designated or
potential uses of surface water, the purposes for which the
criteria were developed and the latest information available.
Clean Water Act ~404
40 CFR 230
Regulates the discharge of dredged or fill materials into
waters of the U.S. Discharges of dredged or fill materials are
not permitted unless there is no practicable alternative that
would have less adverse impact on the aquatic ecosystem.
Any proposed discharge must avoid, to the fullest extent
practicable, adverse effects, especially on aquatic
ecosystems. Unavoidable impacts must be minimized, and
impacts that cannot be minimized must be mitigated.
January 2005 Draft, Peer Review Document
In developing a remedy that included treatment of water
following dewatering sediment, EPA determined that a
revised AWQC was a relevant and appropriate criteria for
discharging to the waterway.
Work at the ASARCO, Tacoma WA, National Priorities List
(NPL) site included construction of an armored cap in the
inter-tidal zone. Work at the Wyckoff/Eagle Harbor, WA, NPL
site included construction of a sheet pile barrier wall to
control subsurface non-aqueous phase liquid (NAPL)
migration. To compensate for the loss of habitat, intertidal
habitat was created in another part of these two sites.
Work at the Lavaca Bay, TX site involved construction of a
CDF with effluent discharge to the Bay. CDF effluent
discharged to waters of the U.S. is defined as a dredged
material discharge under Section 404.
.
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Chapter 3: Feasibility Study Considerations
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Resource Conservation and
Recovery Act (RCRA); 40
CFR 260 to 268
Rivers and Harbors Act,
Section 10
33 CFR 320 to 323
Endangered Species Act
Toxic Substances. Control Act
(TSCA) 40 CFR 761
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Dredged material may be subject to RCRA regulations if it
contained a listed waste, or if it displays a hazardous waste
characteristic, for example by the Toxicity Characteristic
Leaching Procedure (TCLP). Most states have been
authorized to implement the RCRA program in lieu of EPA.
RCRA regulations may potentially be ARARs for the storage,
treatment, and disposal of the dredged material unless an
exemption applies. One such exemption is if CWA 404
applies to the cleanup activity (40 CFR 261).
Activities that could impede navigation and commerce are
prohibited. Prohibits authorized obstruction or alteration of
any navigable waterway.
Section 7 requires federal agencies to ensure that the
actions they authorize, fund or carry out are not likely to
jeopardize the continued existence of endangered or
threatened species, or adversely modify or destroy their
critical habitat Will be an applicable requirement where a
threatened or endangered species or their habitat is or may
be present. By policy, EPA consults with the U.S. Fish and
Wildlife Service and the National Marine Fisheries Service
(NMFS).
Regulates the storage, treatment and disposal of material
contaminated with PCBs. Contaminated dredged sediment
would generally follow the substantive requirements of 40
CFR 761.61, cleanup and disposal requirements for PCB
remediation waste. Material meeting the definition of PCB
remediation waste (761.3) would be disposed of using the
three options under 761.61, which include a self-
implementing option (761.61 (a», a performance-based
option (761.61(b», and a risk-based option (761.61 (c».
January 2005 Draft, Peer Review Document
The material to be dredged contains a listed pesticide
formulation waste, and thus RCRA may be a applicable.
However, the site is located in a state where EPA implements
the RCRA program, and the on-site cleanup action will
comply with substantive requirements of a 404 permit. Thus
the cleanup action is exempted from RCRA. This situation is
explained in the description of the selected remedy in the
ROD.
A site with contaminated sediment has an authorized
navigation depth of 30 feet The evaluation of altematives
needs to consider the need to maintain this minimum depth
when evaluating whether capping is or is not a feasible
altemative for the entire site.
Chinook salmon are threatened species that are found at the
Commencement Bay NPL site during part of the year. After
following EPA's policy of consulting with the NMFS, EPA
decides that to avoid harming the species, some in-water
remedial work will be done only during a window of time
when juvenile salmon are not migrating through the area.
Other in-water work will be performed outside of this window,
using special conditions recommended by NMFS to minimize
impacts to salmon.

Example 1. Although the source of PCBs is not known at this
site, 761.61 may be relevant and appropriate. The risk-
based option under 761.61 is selected. EPA's remedy is to
dredge the contaminated sediment and dispose of the de-
watered sediment and resulting liquid, as per the disposal
requirements for PCB remediation waste. As dewatering is a
physical means of separation, de-watered sediment is
sampled to determine the disposal option, landfilling in either
a municipal landfill or a TSCA chemical waste landfill, based
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Chapter 3: Feasibility Study Considerations
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on the concentration of PCBs in the de-watered sediment.
In general, if sediment containing PCBs is de-watered or
physically separated, the separated solids and liquids can
then be sampled to determine disposal options. Barring the
occurrence of other contaminants, if PCBs in the separated
sediment is below 50 ppm, federal standards allow these
sediments to be taken to a municipal sanitary landfill.
Generally, if PCB levels are greater than 50 ppm in the
separated sediments, they would go to a TSCA chemical
waste landfill and those greater than 500 ppm would be
treated.
Example 2. A PCB transformer is known to have broken
open in the area of PCB-contaminated sediment prior to
1978, resulting in sediment, currently at the site, with PCB
concentrations greater than 50 ppm. As this meets the 761.3
definition for PCB remediation waste, 761.61 may be
applicable. A risk-based disposal plan is selected and is
made part of the ROD.
State Water Quality Standards
Regulation
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......
Determination of whether there is a PCB remediation waste
(as per 761 .3) at the site may require determination of date
of spill, PCB concentration of material spilled, or PCB
concentration currently at site. If information is not available
(e.g., date of spill), 761.61 may still be relevant and
appropriate. The definition of PCB remediation waste, under
761.3, may include any concentration of PCBs. As such,
761.61 may be an ARAR for any concentration of PCBs.
Selection of cleanup/disposal options under 761.61 for a
Superfund site is made at the regional level. The risk-based
option under 761.61 (c) would be expected to be selected
most often at Superfund sites.
Under the CWA, states are required to designate surface
water uses, and to develop water quality standards based on
those uses and the AWQC. Often an applicable requirement
for discharges to surface water. Where a tribe has
promulgated water quality standards, these may also be an
applicable requirement.
January 2005 Draft, Peer Review Document
A tribe has an EPA approved water quality standard
regulation which designates the uses of a river to include
rearing of aquatic life and other uses. Design and
construction of the selected remedy, including the confined
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Chapter 3: Feasibility Study Considerations
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Many states have been authorized by EPA to implement the
RCRA Subtitle C Hazardous Waste Program in lieu of EPA.
Most states have regulations for the location, design,
construction, operation and dosl:Jre of solid waste
management facilities. Potential applicable or relevant and
applicable requirement for disposal of non-hazardous waste
contaminated sediment.
Some states have established wasteload allocations in State-
promulgated and EPA-approved TMDLs. These altocations
may be an applicable or a relevant and appropriate
requirement, where such regulations exist, depending on
whether the regulation specifically addresses the site as a
discharge. Non-promulgated TMDLs may be a TBC.
Under the CWA, many states have been delegated the
authority for the NPDES permit program. These regulations
generally regulate discharges, including monitoring
requirements and effluent discharge limitations for point
sources. Where a remedy has a point discharge that is on-
site, the substantive requirements may be an applicable
regulation.
January 2005 Draft, Peer Review Document
....
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The sediment at a site was contaminated with a listed
hazardous waste. The state has been authorized for RCRA,
and decided to not adopt the hazardous waste identification
rule (HWIR) sediment exemption. Treatment and disposal of
the dredged contaminated sediment must meet or waive the
state's hazardous waste regulations.
A remedial alternative indudes on-site upland disposal of
dredged sediment. The feasibility study examines the state
solid waste regulations and determines that a disposal facility
at two of the three possible sites can be designed to meet the
ARAR. The third site is eliminated from further analysis.
A remedial dredging alternative includes an expected
temporary increase in total suspended solids in the water
body and residual contamination that provides a small
continuing load to the water body. EPA consulted with the
state TMDL program to determine whether TMDLs are a
potential ARAR or TBC and how they interact with the
alternative.
A Superfund remedy includes ground water remediation with
discharge of the water to surface water. EP A consulted with
the state NPDES permit program to determine water
treatment standards prior the discharge.
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Chapter 3: Feasibility Study Considerations
EP A-established TMDLs are not promulgated as rules, are not enforceable, and, therefore, are not
ARARs. TMDLs established by states, territories or authorized tribes mayor may not be promulgated as
rules. Therefore, TMDLs established by states, territories, or authorized tribes, should be evaluated on a
regulation-specific and site-specific basis. Even if a TMDL is not an ARAR, it may aid in setting
protective cleanup levels and may appropriately be a TBC. Project managers should work closely with
regional EPA Water program and state personnel to coordinate matters relating to TMDLs. The project
manager should remember that even when a TMDL or wasteload allocation is not enforceable, the water
quality standards on which they are based may be ARARs. TMDLs can also be useful in helping project
managers evaluate the impacts of continuing sources, contaminant transport, and fate and effects.
Similarly, Superfund's remedial investigation/feasibility study may provide useful information and
analysis to the federal and state water programs charged with developing TMDLs.
Project managers should also be aware of Executive Orders such as those covered by the
Statement of Procedures on Floodplain Management and Wetland Protections, 40 CFR Part 6, Appendix
A. Although few Executive Orders provide requirements under federal environmental laws, making them
ARARs, the Agency normally follows Executive Orders as a matter of policy. The Statement of
Procedures cited above sets forth EP A policy and guidance for carrying out Executive Orders 11990 and
11988, which were written in furtherance of the National Environmental Policy Act (NEPA) and other
environmental statutes. Executive Order 11988 concerns flood plain management and the evaluation by
federal agencies of the potential effects of actions they may take in a flood plain to avoid, to the extent
possible, adverse effects associated with direct and indirect development of a flood plain. Executive
Order 11990 concerns protection of wetlands and the avoidance by federal agencies, to the extent
possible, of the adverse impacts associated with the destruction or loss of wetlands if a practical
alternative exists. OSWER Directive 9280.0-03, Considering Wetlands at CERCLA Sites (U.S. EPA
1994c), contains further guidance on addressing this Executive Order.
Examples of ways in which remedial strategies for sediment have been adapted in light of these
Executive Orders as a matter of policy include the following:
EP A determined that capping above grade would be an inappropriate alternative for
remediating contaminated sediment in a small river, as the increased bottom elevation
would increase the risk of flooding. Instead, the fmal EP A remedy called for dredging
contaminated sediment and capping back to the existing grade; and
When evaluating possible alignments for the access road to the contaminated sediment
site, the region selected a route that avoided the wetland and that would minimize the
potential for effects on the flood plain. During design of the access road, additional
features were incorporated to further minimize any indirect impact on the flood plain.
3.4 LONG-TERM EFFECTIVENESS AND PERMANENCE OF SEDIMENT
AL TERNA TIVES
This first of the five NCP balancing criteria is one of the most critical criteria in evaluating
alternatives. As described in EPA's general RI/FS Guidance, the "long-term effectiveness and
permanence" criterion includes an evaluation of two basic factors, magnitude of residual risk and the
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Chapter 3: Feasibility Study Considerations
adequacy and reliability of controls for that residual risk. As applied to sediment, project managers
should consider:
Marmitude or residual risk: this factor is designed to assess the level of expected residual
risk in the sediment after the completion of the remedy (i.e., after capping, dredging, in-
situ treatment, or several years ofMNR). The volume, toxicity, mobility, bioavailability,
and propensity to bioaccumulate of the residuals should be considered in this evaluation;
and
Adeauacv and reliabilitv or controls: this factor is designed to assess the adequacy and
expected long-term reliability of controls that can be used to manage post-remediation
sediment residuals or untreated contamination that remains in the sediment. It may also
include an assessment of the expected effectiveness of institutional controls, such as fish
consumption advisories, to ensure that exposures are within protective levels. This factor
also addresses the long-term reliability and the potential need to replace technical
components such as a cap, backfill after dredging, or a slurry wall; and their risks posed
should the remedy need replacement.
Developing answers to the following questions may help the project manager in evaluating the
long-term effectiveness of alternatives:
What is the level of human health and/or ecological risk after implementation?
.
How much of the risk is due to sediment residuals versus unremediated areas of
contamination?
.
What is the likelihood that the planned cap, dredging approach, or MNR will meet the
cleanup levels and RAOs?
What type and degree of long-term management will be required?
.
What are the requirements for operation and maintenance (O&M) and long-term
monitoring?
What is the potential need for replacing or modifying the technical components of the
alternative?
What is the magnitude of risk should the remedy fail?
.
What is the degree of confidence that there are adequate controls to identify and prevent
remedy failure?
.
What are the uncertainties associated with the disposal of treatment residuals or dredge
materials?
It is important to remember that each of the three major approaches may be capable ofreaching
acceptable levels of short-term effectiveness, long-term effectiveness, and permanence, and that site-
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Chapter 3: Feasibility Study Considerations
specific characteristics should be reviewed during the alternatives evaluation to ensure that the selected
alternative will be effective in that environment. Project managers should evaluate and compare the
effectiveness of in-situ (capping and MNR) and ex -situ (dredging) alternatives under the conditions
present at the site. There should not be a presumption that removal of contaminated sediments from a
water body will necessarily meet these criteria better than capping or MNR. What constitutes an
acceptable level of effectiveness and permanence is a site-specific decision that should also consider each
of the other NCP remedy selection criteria. Each of the major approaches for sediment has its own
remedy-specific considerations under this criteria. These are summarized below. Some aspects are
discussed in more detail in the following remedy-specific chapters.
Monitored Natural Recovery
For a successful MNRremedy, the risk present at the time of remedy selection should be the
same as baseline risk, but as natural processes progress, the risk should decrease with time. The level of
risk reduction afforded by this remedy generally depends on what cleanup levels the natural processes are
expected to be able to achieve in a reasonable time frame and the level of contamination which may
continue to enter the system from any uncontrolled sources. Residual risk for an MNR alternative
normally is the risk remaining after the remedial action has been concluded (i.e., after natural processes
have reduced risks to acceptable levels). To evaluate the level of permanence and residual risk associated
with an MNR alternative, the project manager might ask: "If MNR processes are currently proceeding at
an acceptable rate, will that rate continue such that the residual risk will be low for the long-term"? This
frequently is related to the stability of the sediment bed, or the chance that clean sediment overlying
buried contaminants may be eroded to such an extent that an unacceptable risk from buried contamination
is created in the future. Residual risk for an MNR remedy may also be related to the chance that ground
water flow, bioturbation, or other mechanisms may move buried contaminants to the surface where they
could cause unacceptable human or ecological exposure, even in otherwise stable, non-erosional
sediment. However, erosion of some portions of a sediment bed, or some movement of contaminants
through bioturbation, may not create an unacceptable risk; therefore, it is important to review such factors
on a site-specific basis. Evaluating the adequacy of controls for these risks in an MNR remedy may
include evaluating the ability of the monitoring plan to detect significant sediment erosion or contaminant
movement, and evaluating the adequacy of any institutional controls that are relied upon to control
erosion (e.g., dam or breakwater maintenance agreements).
In-Situ Capping
For a successful in-situ capping remedy, risk due to direct exposure to contaminated sediment in
the capped area generally decreases rapidly, although risks may remain from un-capped areas. The level
of risk reduction associated with this remedy generally depends on the action level selected for capping
(i.e., what level of contamination will remain outside the capped area) and the level of contamination
which may continue to enter the system from any uncontrolled sources. Residual risk, after the cap is in
place, usually is related to the following: 1) short-term risk remaining from contaminants still in the food
chain; 2) likelihood of cap erosion or disruption exposing contaminants; 3) likelihood of contaminants
migrating through the cap; and 4) risks from contaminants remaining in uncapped areas. An evaluation of
long-term effectiveness and permanence for capping also should include an evaluation of the ability to
monitor the effectiveness of the cap and to replace or replenish components of the cap through time
before any significant contaminant releases occur.
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Chapter 3: Feasibility Study Considerations
Dredging or Excavation
For a successful dredging or excavation remedy, risks wj.thin the site itself may increase due to
increased exposure to contaminants released into the surface water during sediment removal, but this
increase should be temporary and localized. After this time, risk should decrease. The speed of the
decrease and the level of long-term risk reduction associated with this remedy generally depends on the
action level and/or cleanup levels selected for sediment removal (i.e., what level of contamination will
remain outside of the dredged/excavated area), the level of residual contamination in the area after
dredging, and the level of contamination which may continue to enter the system from any uncontrolled
sources. Residual risk, after the dredging or excavation is complete, usually is related to the following: 1)
short-term risk remaining from contaminants still in the food chain; 2) risk from contaminated sediment
left behind outside of the dredged or excavated areas; 3) risk from the residual contamination left in place
after dredging (and backfilling if the remedy included this); and 4) risk posed by untreated contaminants
and treatment residuals at their disposal location. Similar to capping, the evaluation should include the
need to replace technical components of the remedy after remedial action is completed. For dredging or
excavation, this usually focuses on technical components of anyon-site disposal units and the need to
replenish backfill material in the dredged areas.
Project managers should recognize that all approaches for sediment leave some contaminants in
place after remedial actions are completed, whether buried beneath a natural sediment layer or engineered
cap, left near the surface or mixed with backfill as residuals following dredging or excavation, or as low
levels of contamination outside of areas that were capped or dredged. All of these residual contaminants
are affected by a variety of natural processes that can disperse, contain or sequester them. As described
above and in the three remedy-specific chapters of this guidance that follow, MNR, in-situ-capping, and
sediment removal each may be capable of achieving acceptable levels of long-term effectiveness and
permanence. Site-specific site characteristics should be reviewed to ensure that the selected alternative
will provide long-term effectiveness at a particular site.
3.5
COST
Developing accurate cost estimates is an essential part of evaluating alternatives. Guidance on
preparing cost estimates and the general role of cost in remedial alternative selection is discussed inA
Guide to Developing and Documenting Cost Estimates During the Feasibility Study (U.S. EPA and
USACE 2000). The general elements of a cost estimate include capital costs, annual and periodic O&M
costs, and net present value (U.S. EPA and USACE 2000). A cost estimate prepared as part of the
CERCLA cleanup process should not include potential claims for natural resource damages or potential
restoration credits, but may include costs for mitigation of habitat lost or impaired by the remedial action,
where appropriate.
3.5.1
Capital Costs
Capital costs are those expenditures that are needed to construct a remedial action (U.S. EP A and
USACE 2000). Capital costs include only those expenditures that are initially incurred to implement a
remedial alternative and major capital expenditures in future years. Capital cost elements that may be
important at sediment sites include those listed in Highlight 3-3. As indicated in the Highlight, capital
costs may include construction monitoring and environmental monitoring before, during and immediately
following the remedial action. Monitoring beyond that point should be considered part of O&M.
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Chapter 3: Feasibility Study Considerations
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Mobilization/de mobilization
Site preparation (e.g., fencing, roads, utilities)
Construction monitoring, sampling, testing, and analysis before, during and
immediately following construction (e.g., bathymetric surveys)
Environmental monitoring before, during, and immediately following
construction (e.g., water quality monitoring)
Debris and/or structure (e.g., piers, pilings) removal and disposal
Project management and support throughout construction, including
preparation of remedial action documentation and construction submittals
Engineering needs during construction (not pre-construction design)
Post-construction habitat restoration (e.g., plantings)
Pilot studies
General contingency
Indirect costs
Implementation of institutional controls
Monitoring and reporting prior to attainment of cleanup levels
Cap materials
- Material costs
- Equipment and labor costs
- Cost of mitigation if required under CWA ~404
.
Transport, storage, and placement of cap materials
- Barge/tug lease costs
- Stockpiling of cap material
- Land use cost
.
Dredging or excavation equipment and labor costs
.
Engineering controls to protect water quality (e.g., silt curtains)
.
Site decontamination for support facilities (e.g., truck wash, dewatering
area)
.
Sediment isolation for excavation (e.g., sheetpile, earthen dams)
.
Construction of dewatering area/temporary storage of dredged material
.
Transporting sediment to treatment or disposal site
- Barge/tug lease costs
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Chapter 3: Feasibility Study Considerations
Pipeline costs
Land acquisition costs for cons1ruction easements or relocating utilities
Pre- T reatmentIT reatment
Land acquisition costs
Construction of pre-treatmentl1reatmentlstorage buildings
Treatment of sediment
Treatment and discharge of water from dewatering process
Engineering controls to protect water quality (e.g., process water and storm
water runoff controls)
Disposal of trea1rnent residuals
In-Water Contained
Aquatic Disposal, In-
Water or Upland Confined
Disposal Facilities
Land acquisition or use costs
Construction of disposal site and any associated disposal costs
Demolition of existing facilities
Excavation to support berm
Equipment and labor costs
Berm construction
Imported materials for berm
Equipment costs
Capping disposal site
Cap materials
Equipment and labor costs
Engineering controls to protect water quality
Cost of mitigation if required under CWA 9404
Upland Landfill Disposal
Land acquisition costs
Construction costs
Transportation costs
Tipping fees for regional landfill
The basis for a cost estimate may include a variety of sources, including cost curves, generic unit
costs, vendor information, standard cost estimating guides, and similar estimates, as modified for the
specific site. Where site-specific costs are available from pilot studies or removal actions, they are likely
to be the best source of realistic cost information. Where this is not available, actual costs from similar
projects implemented at other sites is frequently the next best source of costs.
Substantial amounts of historical cost data for some components of sediment remediation (for
example removal, transport, disposal, and residue management) may be available from other project
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Chapter 3: Feasibility Study Considerations
managers. EP A's Office of Superfund Remediation and Technology Innovation (OSRTI) can help
project managers locate sites where a similar approach has been implemented. The project manager also
may fmd it useful to refer to the ARCS program (U.S. EPA 1994d) for a discussion on the general
elements of cost estimates for sediment sites. This document provides examples of percentages for
general costs and site-specific costs for both in-situ and ex-situ remedies. Also, many of the local district
U.S. Army Corps of Engineers (USACE) offices have extensive experience with dredging and in-water
construction and may be an additional source of good cost information.
3.5.2
Operation and Maintenance Costs
O&M costs generally are those post-construction costs necessary to ensure or verify the
continued effectiveness of a remedial action (U.S. EP A and USACE 2000). These costs may be annual or
periodic (e.g., once only, or once every five years). It is important to note that short-term O&M costs
generally are incurred as part of the Remedial Action phase of a project, while long -term O&M costs or
long-term cap maintenance generally are part of the O&M phase of a project (U.S. EPA and USACE
2000). At Fund-lead sites it can be very important to differentiate these two cost categories because
CERCLA has specific requirements that address paying for long-term O&M (CERCLA 104(c)(3»(See
Section 3.5.4, State Cost Share). Some examples of categories that are generally considered short-term
O&M at sediment sites include the following:
Operation of sediment or water treatment facilities during the remedial action;
Monitoring, sampling, testing, analysis, and reporting during the remedial action (some
may be considered capital costs, see Section 3.5.1 above);
Maintenance of in-situ cap or on-site disposal site during the shake-down period (e.g.,
one year);
Maintenance of engineering site controls during shake-down period (e.g., one year);
Cost overrun contingency; and
.
Project management and support.
Some examples of categories that are generally considered long-term O&M at sediment sites
include the following:
.
Maintenance and monitoring of institutional controls;
.
Long-term monitoring, sampling, testing, analysis, and reporting;
Long-term maintenance of in-situ cap or on-site disposal unit; and
.
Long-term maintenance of engineering site controls.
Additional issues related to long-term monitoring and maintenance of all three remedial
approaches (MNR, capping, and dredging or excavation) are discussed in Chapter 8 of this guidance.
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Chapter 3: Feasibility Study Considerations
3.5.3 Net Present Value
The NCP also provides that an analysis of remedy net present value, or present worth, should be
used [NCP ~300.430(e)(9)(iii)]. A net present value analysis should be used to compare expenditures that
occur over different time periods. This standard methodology allows for a cost comparison of different
alternatives that have capital and operation, maintenance, and monitoring costs that would be incurred in
different time periods on the basis of a single cost figure for each alternative. In general, the period of
analysis should be equivalent to the project duration, resulting in a complete life cycle cost estimate for
implementing the remedial alternative. Past EP A guidance recommended the general use of a 30-year
period of analysis for estimating present value costs (U.S. EP A 1988a). Although this may be appropriate
in some circumstances, the blanket use of a 30-year period is no longer recommended. Site-specific
justification should be provided for the period of analysis selected, especially when the project duration
(i.e., time period required for design, construction, operation and maintenance, and closeout) exceeds the
selected period of analysis (U.S. EP A and USACE 2000).
For sediment approaches that leave significant quantities of contaminated sediment in place, such
as in-situ capping or monitored natural recovery based on natural burial, the actual monitoring period is
likely to be longer than 30 years, although project managers are encouraged not to assume that monitoring
in perpetuity will be necessary at every site. This is discussed further in Chapter 8, Remedial Action and
Long-Term Monitoring.
The discount rate that should be used for this analysis is established by the Office of Management
and Budget (OMB). Based on current Agency policy, as reflected in the NCP preamble (55 FR 8722) and
the OSWER Directive 9355.3-20, Revisions to OMB Circular A-94 on Guidelines and Discount Rates for
Benefit-Cost Analysis (U.S. EPA 1993b), a seven percent discount rate should be used in estimating the
present worth value for potential alternatives. This figure could be revised in the future, and project
managers should use the current figure contained in an update of the OSWER Directive 9355.3-20.
Project managers should be aware that this rate may not be the same as rates that various potentially
responsible parties (pRPs) or federal facilities use for similar analyses. For example, some industries use
a higher discount rate that includes an opportunity cost of capital when the pool of capital dollars is
limited for a particular business. This typically will increase the net present value of alternatives with
high long-term O&M costs in their analysis. The project manager should refer to A Guide to Developing
and Documenting Cost Estimates for the Feasibility Study (U.S. EP A and USACE 2000) for more
information.
3.5.4
State Cost Share
At Fund-lead sites, generally the state is responsible for ten percent of remedial action costs and
100 percent oflong-term O&M costs (see 40 CFR 300.5l0(b) and (c)). Different requirements may apply
if the facility was publicly operated at the time of disposal of hazardous substances and for federal
facilities. Where O&M costs are significantly different between alternatives, this may add to differences
of opinion about preferred alternatives. For the discussion to be based on the best available information,
it is especially important that cost estimates be as accurate as possible, including costs of long-term
O&M.
After a joint EP Nstate inspection of an implemented Fund-fmanced remedial action, EP A may
share, for a period of up to one year, in the cost of the operation of the remedial action to ensure that the
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Chapter 3: Feasibility Study Considerations

remedy is operational and functional (40 CFR 300.5 I 0(c)(2)). Where this appli~s to sediment sites, it
may mainly involve in-situ caps and on-site disposal facilities.
The RAOs of most sediment sites address sediment and biota. However, a few sediment site
remedies may also include surface water restoration as a goal of the remedial action. The NCP specifies
the following in 40 CFR 300.510(c)(2):
In the case of the restoration of ground or surface water, EP A shall share in the cost of
the state's operation of ground or surface water restoration remedial actions as specified
in 40 CFR 300.435(f)(3).
The NCP at 40 CFR 300.435(f)(3) specifies that
For Fund-fmanced remedial actions involving treatment or other measures to restore
ground- or surface-water quality to the level that assures protection of human health and
the environment, the operation of such treatment or other measures for a period of up to
10 years after the remedy becomes operational and functional will be considered part of
the remedial action. Activities required to maintain the effectiveness of such treatment or
other measures following the I O-year period, or after remedial action is complete,
whichever is earlier, shall be considered O&M.
In 40 CFR 300.435 (f)(3) and (4), the NCP also addresses when a restoration activity will be considered
administratively "complete" for purposes offederal funding and discusses several actions that are
excluded from consideration under this provision.
Where a sediment site includes surface water restoration as a goal, the project manager should
consult with their Office of Regional Counsel to determine how these provisions apply to their site.
3.6
INSTITUTIONAL CONTROLS
The term "institutional control" (IC) generally refers to non-engineering measures intended to
affect human activities in such a way as to prevent or reduce exposure to hazardous substances, often by
limiting land or resource use. ICs can be used at all stages of the remedial process to reduce exposure to
contamination. Chapter 7, Remedy Selection Considerations, offers guidance on when it may be
appropriate to select a remedy that includes institutional controls at sediment sites and considerations
regarding their effectiveness and enforceability. For more detailed information on ICs in general, refer to
OSWER Directive 9355.0-74FS-P, Institutional Controls: A Site Manager's Guide to IdentifYing,
Evaluating, and Selecting Institutional Controls at Superfund and RCRA Corrective Action Cleanups
(U.S. EPA 2000e) and Federal Facilities Restoration and Reuse Office (FFRRO) guidance, Institutional
Controls and Transfer of Real Property under CERCLA Section J 20 (h)(3)(A), (B), or (C) (U.S. EP A
2000f).
As explained in the OSWER Directive cited above (U.S. EPA 2000e), there are four general
categories ofICs:
Governmental controls;
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Chapter 3: Feasibility Study Considerations
Proprietary controls;
Enforcement and permit tools with IC components; and
Information devices.
Usually, governmental controls (e.g., bans on harvesting fish or shellfish) are implemented and
enforced by the state or local government. Proprietary controls, such as easements or covenants, typically
involve legal instruments placed in the chain of title of the site or property. Enforcement tools normally
include provisions ofCERCLA Unilateral Administrative Orders (UAOs), Administrative Orders on
Consent (AOCs), or Consent Decrees (CD). Information devices are designed to provide information or
notification to the public. The three most common types of ICs at sediment sites include fish
consumption advisories and commercial fishing bans, waterway use restrictions, and land use
restriction/structure maintenance agreements. Each of these is discussed in more detail below.
Fish Consumption Advisories and Fishin~ Bans
Fish consumption advisories are informational devices that are frequently selected as part of
sediment site remedies. Commercial fishing bans are government controls that ban commercial fishing
for specific species or sizes offish or shellfish. Usually, state departments of health are the governmental
entities that establishes these advisories and bans. Frequently, fish consumption advisories and fishing
bans are already in place before a site is listed on the NPL, but if not, it could be necessary for the state to
issue or revise them in conjunction with an early or interim action, or the final remedial action. An
advisory usually consists of informing the public that they should not consume fish from an area, or
consume no more than a specified number of fish meals over a specific period of time from a particular
area. Sensitive sub-populations or subsistence fishers may be subject to more stringent advisories.
Advisories can be publicized through signs at popular fishing locations, pamphlets, or other educational
outreach materials and programs. Information should be provided in appropriate languages to meet the
needs of the impacted communities. However, project managers should be aware that consumption
advisories are not enforceable controls and their effectiveness can be extremely variable. This is
discussed further in Chapter 7, Remedy Selection Considerations.
Waterway Use Restrictions
For any alternative where subsurface contamination remains in place (e.g., capping, monitored
natural recovery, or an in-water confmed disposal site), waterway use restrictions may be necessary in
order to ensure the integrity of the alternative. Examples include restricting boat traffic in an area to
establish a no-wake zone, or prohibiting anchoring of vessels. In considering boating restrictions, it is
important to determine who can enforce the restrictions, and under what authority and how effective such
enforcement has been in the past. In addition, it may be necessary to evaluate remedial alternatives that
involve changing the navigation status of a waterway. For a federally authorized navigation channel,
de authorization of the channel would be required. This can be a lengthy process that requires a formal
request to the USACE, an opportunity for users of the waterway to comment, and, ultimately,
de authorization by Congress. The state also may have additional authority to change harbor lines or the
navigation status of a waterway. Lastly, a restriction on easements for installing utilities, such as fiber
optic cables, can be an important mechanism to help ensure the overall protectiveness of a remedy.
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Chapter 3: Feasibility Study Considerations
Land Use Restrictions and Structure Maintenance Agreements
Where contamination remains in place, it may be necessary for the project manager to work with
private parties, state land management agencies, or local governments to implement use restrictions on
nearshore areas and adjacent upland properties. For example, construction of boat ramps, retaining walls,
or marina development can expose subsurface contamination and compromise the long-term effectiveness
of a remedy. Ownership of aquatic lands varies by state and locality. In many cases, nearshore areas can
be privately owned out to the end of piers. For private property owners, more traditional ICs, such as
proprietary controls or enforcement tools with IC components, can be considered. Potentially, some of
these restrictions can be implemented through agencies who permit construction activities in the aquatic
environment. Several federal, state, and local laws place restrictions on and may require permits to be
obtained for dredging, filling, or other construction activities in the aquatic environment. These include
Section 404 of the Clean Water Act, Title 33 United States Code (U.S.C.) Section 1344, and Sections 9
and 10 of the Rivers and Harbors Act of 1899,33 US.C. 401 and 403. It may also be possible to
implement some ICs through coordination with existing permitting processes. Harbor Master Plans,
state-designated port areas, and local authorities may also function to restrict certain uses. In addition,
long-term maintenance of structures such as dams or breakwaters may be a necessary component of some
sediment remedies. Where this is the case, it is important that project managers clarify how this
maintenance is part of the remedy and who is responsible for it. Where maintenance decisions may
change through time, contingencies may be needed for additional actions.
Highlight 3-4 summarizes some important points to .t;'emember about feasibility studies at
sediment sites.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
...8igHligH~.~-4:.$pm~k~y .~Pi~~~.t~.~~m~m~r.~b,~~t.F~~SibilitY.$j~~i~~f~t$~~il"f1~~t...

Generally, project managers should implement and evaluate the effectiveness of major source control
actions before finalizing the evaluation of alternatives for sediment.
Generally, project managers should evaluate each of the three major approaches: MNR, in-situ capping,
and removal through dredging or excavation, at every sediment site at which they might be appropriate.
At sites with multiple water bodies or sections of water bodies with different characteristics or uses,
alternatives that combine a variety of remedial approaches are frequently the most promising.
MNR, in-situ capping, and sediment removal are each capable of achieving acceptable levels of long-
term effectiveness and permanence. Site-specific site characteristics should be reviewed to ensure that
the selected alternative will be effective at a particular site.
Accurate cost estimates, including long-term O&M costs and, where appropriate, materials handling,
transport, and disposal costs, are very important to a good comparison of alternatives. Actual costs from
pilot projects at a site and at similar, completed sediment sites are among the best cost resources.
Institutional controls can be used at all stages of the remedial process to reduce exposure to
contamination. Project managers should consider the effectiveness and enforceability of controls used at
their site and evaluate their role in risk reduction.
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Chapter 4: Monitored Natural Recovery
4.0
MONITORED NATURAL RECOVERY
4.1
INTRODUCTION
Monitored natural recovery (MNR) is a remedy for contaminated sediment that typically uses
ongoing, naturally occurring processes to contain, destroy, or reduce the bioavailability or toxicity of
contaminants in sediment. Not all natural processes result in risk reduction; some may increase or shift
risk to other locations or receptors. Therefore, to implement MNR successfully as a remedial option,
project managers should identify and evaluate those processes that contribute to risk reduction. MNR
usually involves acquisition of information over time to conftrm these potential risk-reduction processes.
Implementation of MNR usually requires assessment, modeling, and monitoring to demonstrate risk
reduction. Project managers should also be aware of the potential for combining natural recovery with
engineering approaches, for example by installation of flow control structures to encourage deposition or
by the placement of a thin layer of additional clean sediment or additives to enhance sorption or chemical
transformation. These combined approaches are discussed further in Section 4.5, Enhanced Natural
Recovery .
MNR may rely on a wide range of naturally occurring processes to reduce risk to human and/or
ecological receptors. These processes may include physical, biological, and chemical mechanisms that
act together to reduce the risk posed by the contaminants. Depending on the contaminants and the
environment, this risk reduction may occur in a number of different ways. HigWight 4-1 lists the most
common risk reduction processes. Processes which reduce toxicity through destructive processes or
reduce bioavailability through increased sorption usually are preferable to mechanisms that reduce
exposure through natural burial or mixing-in-place because the destructive/sorptive mechanisms generally
have a higher degree of permanence. However, many contaminants which remain in sediment are not
easily transformed or destroyed. For this reason, risk reduction due to natural burial through
sedimentation is more common and can be an acceptable sediment management option. The last
mechanism of the four most common processes, dispersion, typically is the least preferable basis for
MNR because, while it may reduce risk in the source area, generally it increases contaminant loading to
downstream areas. As reiterated in Chapter 7, Remedy Selection Considerations, project managers
should carefully evaluate the effects of this increased loading on receiving bodies before selecting MNR
where dispersion is the primary risk reduction mechanism, to ensure that it is not simply transferring risk
to a new area. Project managers should be aware that at most sites, a variety of natural processes are
occurring which may reduce risk. All mechanisms are valid as a part of a potentially viable basis for
selection of MNR after all criteria have been weighed.
As used for purposes of this guidance, MNR is similar in some ways to the Monitored Natural
Attenuation (MNA) remedy used for ground water and soils (U.S. EPA 1999d). The key difference
between MNA for ground water and MNR for sediment is in the type of processes most often being relied
upon to reduce risk. Whereas transformation of contaminants usually is the major attenuating process
relied upon for contaminated ground water, these processes are frequently too slow for the persistent
contaminants of concern in sediment to provide for remediation in a reasonable time frame. Therefore,
isolation and mixing of contaminants through natural sedimentation is the process most frequently relied
upon for contaminated sediment.
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Chapter 4: Monitored Natural Recovery
......
........ .. ...... . .. .
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::i:M!9h'~9,"it~;:9in!r!!H'!r!~9h¥P!N~~4r~j:Rley!rYB~991!!~t9~~i,m!n'~'~!!:{:{
...
Many different natural processes may reduce risk from contaminated sediment, including the following, listed from
generally most to least preferable, though all potentially acceptable, as a basis for selecting MNR:
A
The contaminant is converted to a less toxic form through transformation processes, such as
biodegradation or abiotic transformations
B
Contaminant mobility and bioavailability are reduced through sorption or other processes binding
contaminants to the sediment matrix
C
Exposure levels are reduced by a decrease in contaminant concentration levels in the near-
surface sediment zone through burial or mixing-in-place with cleaner sediment
D
Exposure levels are reduced by a decrease in contaminant concentration levels in the near-
surface sediment zone through dispersion of particle-bound contaminants or diffusive or
advective transport of contaminants to the water column or (see caveats in text regarding use of
these processes for risk reduction)
The information needed to select an MNR remedy for sediment generally include the following:
.
A detailed understanding of the natural processes that are affecting sediment and
contaminants at the site;
.
A predictive tool (generally based either on computer modeling or extrapolation of
empirical data) to predict effects of those processes in the future;
A means to control any significant ongoing contaniinant sources;
An evaluation of ongoing risks during the recovery period and exposure control, where
possible; and
.
The ability to monitor the natural processes and/or concentrations of contaminants in
sediment or biota to see if recovery is occurring at the expected rate.
Some consider that all sediment site remedies are using natural recovery to some extent because
natural processes are ongoing whether or not an active cleanup is underway [e.g., National Research
Council (NRC) 2001]. It is true that natural processes in most cases will continue whether or not an
active cleanup is underway, but these processes may either reduce, transfer, or increase risk. Natural
processes may reduce residual risk following dredging or in-situ capping at many sites, and it is can be
very valuable to monitor that further reduction in risk. However, it is also important for project
managers to distinguish whether they are relying upon natural processes to reduce risk to an acceptable
level (i.e., using MNR as a remedy), or simply noting the fact that natural processes are ongoing at a site
and are expected to continue to reduce residual risks that are already at an acceptable level. Therefore,
the key factors that Mrmally distinguish MNR as a remedy are the presence of unacceptable risk, the
ongoing burial or degradation/transformation, or dispersion of the contaminant, and the establishment of a
cleanup level that MNR is expected to meet within a particular time frame.
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Chapter 4: Monitored Natural Recovery
MNR has been selected as a component of the remedy for contaminated sediment at about a
dozen Superfund sites so far. Historically, at many sites it has been combined with dredging or in-situ
capping of other contaminated sediment areas of a site. Although natural recovery has been observed in
some areas (e.g., decreases in contaminant levels in sediment), long-term monitoring data on fish tissue
are not yet available at most sites to document continued risk reduction. However, monitoring results
from some areas are promising (e.g., U.S. EPA 200lh, U.S. EPA 200li, Swindoll et al. 2000). MNR does
not generally meet the Comprehensive Environmental Response, Compensation and Liability Act
(CERCLA) ~l2l(b)(l) preference for treatment. However, just as is the case with many traditional land
remedies, if the proposed remedy meets other requirements, it can still be selected under CERCLA ~12l
and existing guidance. When contaminants left in place are above levels that allow for unlimited use and
unrestricted exposure, five-year reviews generally are necessary (U.S. EP A 200lk).
Although each of the three major remedies (MNR, in-situ capping, and removal) should be
considered at every site at which they might be appropriate, MNR should receive detailed consideration
where the site conditions listed in Highlight 4-2 are present.
...!..,":~!~'~!~1~1:~f,~~'~gml::~!~9~ij~~~gnj'~~~~$!li!!M=pgij~ij$!yijgMpQ:!,~tl:!:Nimrm:.R~99Y~tY:::::::.::::::::'
Risk is low to moderate
Anticipated land uses or new structures are not incompatible with natural recovery
Natural recovery processes have a reasonable degree of certainty to continue at rates that will contain,
destroy, or reduce the bioavailability or toxicity of contaminants within an acceptable time frame
Expected human exposure is low and/or can be reasonably controlled by institutional controls
Site includes sensitive, unique environments that could be irreversibly damaged by capping or dredging
Sediment bed is reasonably stable and likely to remain so
Sediment is resistant to resuspension (e.g., cohesive or well-armored sediment)
Contaminant concentrations in biota and in the biologically active zone of sediment are moving towards
risk-based goals on their own
Contaminants already readily biodegrade or transform to lower toxicity forms
Contaminant concentrations are low and cover diffuse areas
Contaminants have low ability to bioaccumulate
4.2
POTENTIAL ADVANTAGES AND LIMITATIONS
In most cases, the two key advantages of MNR are its relatively low implementation cost and its
non-invasive nature. While costs associated with characterization and often, modeling, necessary to
evaluate natural recovery can be extensive, the costs associated with implementing MNR are primarily
associated with monitoring. However, implementation costs may also include the cost of implementing
institutional controls and public education to increase the effectiveness of those controls. MNR typically
involves no man-made physical disruption to the existing biological community, which may be an
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Chapter 4.; Monitored Natural Recovery
important advantage for some wetlands or sensitive environments where the harm to the ecological
community due to sediment disturbance may outweigh the risk reduction of an active cleanup.
Other advantages of MNR may include the fact that no construction or infrastructure is needed,
and therefore it may be much less disruptive of communities than active remedies such as dredging or in-
situ capping. No property should be needed for materials handling, treatment, or disposal facilities, and
no contaminated materials should be transported through communities.
Two key limitations of MNR may be that it generally leaves contaminants in place and that it can
be slow in comparison to active remedies. Any remedy that leaves untreated contaminants in place
probably includes some risk of re-exposure of the contaminants. When MNR is based primarily on
natural burial, there is some risk of buried contaminants being re-exposed or dispersed if the sediment bed
is significantly disturbed by unexpectedly strong natural or man-made forces. The potential effects ofre-
exposure may be greater if high concentrations of contaminants remain in the sediment, and likewise,
lower if contaminant concentrations or risks are low. There is also some risk of dissolved contaminants
being transported to the surface water at levels that could cause unacceptable risk. The time frame for
natural recovery may be slower than that predicted for dredging or in-situ capping. However, realistic
estimates of the longer design and implementation time for active remedies should be factored in to the
comparison. Like any remedy which takes a period of time to reach remediation goals, remedies that
include MNR frequently rely upon institutional controls, such as fish consumption advisories, to control
human exposure during the recovery period. These controls may have limited effectiveness and usually
have no ability to control ecological exposures.
Another limitation of MNR may be a high level of uncertainty associated with it. Major areas of
uncertainty frequently include uncertainty related to predicting future sedimentation rates in dynamic
environments and uncertainty related to the ability to predict rates of contaminant flux through stable
sediment. It can be especially difficult to predict rates of natural recovery where contaminant levels and
risks are already low because small additional factors become relatively more important. However, a
higher level of uncertainty may be more acceptable in these situations as well.
4.3
LINES OF EVIDENCE
An evaluation of MNR as a potential remedy or remedy component should be supported with
site-specific characterization, analysis, and usually, modeling. A variety of types of information, or lines
of evidence, is usually needed. The lines of evidence approach for evaluation of natural attenuation of
contaminants in soil and ground water can provide a general framework for evaluating MNR in sediments
(e.g., u.s. EPA I 999d). Swindoll and his colleagues include a chapter on natural remediation of
sediment which presents a useful summary discussion (Swindoll et al. 2000). EP A's Office of Research
and Development (ORD) is in the process of drafting a technical resource document specifically for MNR
in sediments and may also include suggested protocols.
As with the evaluation of any sediment alternative, an evaluation of MNR should be based on a
thorough conceptual site model that includes current and future pathways of human and ecological
exposure to the contaminants. This conceptual understanding should be based on site-specific data
collected over a number of years and, for factors known to fluctuate seasonally, data collected during
different seasons. Lines of evidence that can be used to construct a plausible case for the use of MNR
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Chapter 4: Monitored Natural Recovery
include those listed in Highlight 4-3. It is important to note that not all lines of evidence or types of
information are appropriate at every site, but generally, multiple lines of evidence are needed.
.....
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
......... ........................-..."""""""""""'" .,. ................... [[[
.::..;.::::::::ft~i~!i,~~~:!~f.gR'~n~i.~!i!ij~~Rf!Ji:i,~i~~.BtM9n~!Br~~..N~~H:~!I.:.iIB~ir¥::::::.:.:.:..:::::::::::::;::::::::
.......
....
.......
.
Characterization of historical sources of contamination and documentation that significant ongoing
sources have been controlled
.
Characterization of transport and fate processes for sediment and contaminants
.
Compilation of sufficient historical record for contaminants in sediment to evaluate temporal trends of
concentration, mass, or toxicity over time
.
Compilation of sufficient historical trends in biological endpoint data to corroborate chemical data trends
.
Development of an acceptable and defensible predictive tool(s) to allow prediction offuture recovery and
reduction in risk
Source: Adapted from Davis et al. 2003
Examples of types of site-specific information that could be collected to support the lines of
evidence listed in Highlight 4-3 include the following:
Contaminant concentrations in water column, sediment, and/or biota before and after
source control or hot spot sediment remediation measures are implemented;
Sediment core data demonstrating a trend in historical surface contaminant
concentrations through time;
Rates of sedimentation and erosion through time;
Depth of the sediment mixing zone (e.g., due to bioturbation);
Knowledge of contaminant transport into sediment or surface water from ground water
advection or movement of non-aqueous phase liquids (NAPL);
Extent of contaminant sorption to sediment and bioavailability to receptors;
Extent of anaerobic/aerobic chemical or biotransformation occurring at the site; and
Identification of bioaccumulation pathways from sediment to biota.
The amount of physical, biological, and chemical processes information needed to adequately
assess the applicability of MNR is site specific. An important step in documenting the potential for MNR
as a management alternative normally is to show that observed reductions in sediment and biological risks
can reasonably be expected to continue into the future. In systems where the mechanisms causing the
recovery is unknown, or where the fate and transport processes driving recovery may be complex and
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Chapter 4: Monitored Natural Recovery
well-constructed numerical model can be a useful tool for predicting future behavior of the system. This
is discussed further in Chapter 2, Section 2.9 Modeling.
Integration of the Data Quality Objective (DQO) process with the risk evaluation process should
identifY which natural processes are most critical to the evaluation of MNR at a site. Generally, the
identification of MNR data needs and preparation of study design can be structured similarly to the DQO
process (U.S. EPA 2000a) that is normally integrated within the remedial investigation and feasibility
study (RIfFS). The DQO process is discussed in greater detail in Chapter 2, Section 2.1.1.
4.4
NATURAL RECOVERY PROCESSES
The success of MNR as a risk reduction approach typically is dependent upon understanding the
dynamics of the contaminated environment and the fate and mobility of the contaminant in that
environment. The natural processes of interest for MNR may include a variety of processes that, under
favorable conditions, act without human intervention to reduce the mass, toxicity, mobility, or
concentration of contaminants in the sediment bed. These natural processes may include the following:
.
Phvsical processes: sedimentation, advection, diffusion, dilution, dispersion,
bioturbation, volatilization;
Biolof!ical processes: biodegradation, biotransformation, phytoremediation, biological
stabilization; and
Chemical processes: oxidation/reduction, sorption, or other processes resulting in
stabilization or reduced bioavailability.
Highlight 4-4 illustrates some of the natural processes that the project manager should consider
when evaluating MNR. With few exceptions, these processes interact in aquatic systems, sometimes
increasing the risk-reduction effects of a process compared to what they might be for that process in
isolation, and sometimes reducing those risk-reduction effects. For example, as recognized by the U.S.
Environmental Protection Agency's (EPA) Science Advisory Board (SAB) Environmental Engineering
Committee, Monitored Natural Attenuation: USEP A Research Program - An EP A Science Advisory
BoardReview (U.S. EPA 200Ij), sustained burial processes remove contaminants from the bioavailable
zone, but also can impede certain degradation processes, such as aerobic biodegradation. Likewise,
contaminant sorption to sediment particles may both reduce bioavailability and reduce rates of
contaminant transformation. In addition, in the case of mixed contaminants, the same natural process
may result in very different environmental fates. When dealing with mixed contaminants at a site, care
should be taken not to focus unduly on one contaminant without understanding the effects of natural
processes on the other contaminants. Understanding the interactions between effects and prioritizing the
significance of these effects to the MNR remedy should be part of a.natural process analysis.
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Chapter 4: Monitored Natural Recovery
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............. ........ . ......... ............................
"",......................
...........
...... .
..............
......
......
,.....
......
............ ...
........
..........
Volatilization
Ground
Water
Advection
Chemical and
Biological
Status
Bioaccumulation
Hydrodynamics and
Geomorphologic
Change
Water
Column
Deposition and


/"""
Resuspension
and Dispersion


\
Phytoprocesses
Suspended
Particles
Biodegradation
1
Bioturbation
Bioavailability
Surface Sediment
---------
Mixed Zone'
.....................
Buried Sediment
-Identify temporal
and spatial changes
-Evaluation of additional
contaminant sources in the
watershed (terrestrial,
aquatic, and atmospheric)
-Geochemistry, redox
effects, and chemical
enhanced desorption
4.4.1
Physical Processes
Generally, physical processes do not directly change the chemical nature of contaminants.
Instead, physical processes may bury, mix, dilute, or transfer contaminants to another medium. Physical
processes of interest for MNR include sedimentation, erosion, re-suspension, diffusion, dilution,
dispersion, bioturbation, advection, and volatilization (including temperature-induced desorption of semi-
volatiles). All of these processes may reduce contaminant concentrations in surface sediment, and thus
reduce risk associated with the sediment. Sedimentation normally reduces risk physically by containing
contaminants in place. Other physical processes, such as erosion, dispersion, dilution, bioturbation,
advection, and volatilization may reduce contaminant concentrations in sediment as a result of
transferring the contaminants to another medium or dispersing them over a wider area (e.g., via ground
water or surface water). These processes may reduce, increase, or transfer the risk posed by the
contaminants. As discussed previously in Section 4.1, project managers should carefully evaluate the
effects of increased loading on receiving bodies before selecting MNR where dispersion is the primary
risk reduction mechanism.
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Chapter 4: Monuored Natural Recovery
Physical processes in sediment can operate at vastly different rates. Some may occur faster than
others, but mayor may not have more impact on risk. In general, processes in which contaminants are
transported by bulk movement of particles or pore water (e.g., erosion, dispersion, bioturbation,
advection) occur at faster rates than processes in which contaminants are transported by diffusion or
volatilization and, therefore, are frequently, but not always, more important when evaluating MNR.
Processes that result in particle movement are particularly important for hydrophobic or other
contaminants that are strongly sorbed to sediment particles. Some physical processes are continuous, and
others seasonal or episodic. Depending on the environment, any of these types of processes (i.e.,
continuous, seasonal, or episodic) may have the most impact on natural recovery of a site. For example,
project managers should not assume that episodic flooding will have a positive or negative effect on risk
over an entire site. Flooding is most likely to cause erosion in some areas, while causing significant
deposition in others.
Transport and deposition of cleaner sediment in a watershed may lead to natural burial of
contaminated sediment in a quiescent environment. Natural burial may reduce the availability of the
contaminants to aquatic plants and animals and, therefore, may reduce toxicity and bioaccumulation. The
overlaying cleaner sediment also serves to reduce the flux of contaminants into the surface water by
creating a longer pathway that the desorbed contaminants must travel to reach the water column.
However, while bioturbation by burrowing organisms may promote mixing and dilution of contaminated
sediment with the newly deposited cleaner sediment, for bioaccumulative contaminants it may also result
in continued bioaccumulation into the food web until contaminant isolation occurs.
The long-term protectiveness provided by sedimentation depends upon the physical stability of
the new sediment bed and the rates of movement of contaminants through the new sediment. Major
events, such as severe floods or ice movements may scour the buried sediment, exposing contaminated
sediment and releasing the contaminants into to the water column. Ground water that flows through the
sediment bed also may transport dissolved contaminants into the water column. Depending upon their
extent, processes such as these may extend the natural recovery period or, in some cases, inhibit it
altogether. A site-specific evaluation of both sediment stability and contaminant mobility are important
to evaluating MNR as a remedy. There are a variety of empirical and modeling methods to assess rates of
various physical processes at specific sites. These are discussed in Chapter 2, Section 2.8, Sediment
Stability and Contaminant Fate and Transport, and Section 2.9, Modeling.
4.4.2 Biological and Chemical Processes
Like most natural processes, biological processes also depend on site-specific conditions and are
highly variable. During biodegradation, a chemical change is facilitated by microorganisms living in the
sediment. One of the important limitations to the usefulness of biodegradation as a risk-reduction
mechanism is that the greater the molecular weight of the organic contaminants, the greater partitioning to
sorption sites on sediment particles (MaIlhot and Peters 1988) and the lower the contaminant availability
to microorganisms. Some degradation of high molecular weight organic compounds occurs naturally in
soil and sediment with anaerobic and aerobic microorganisms (Brown et al. 1987, Abramowicz and Olsen
1995, Bedard and May 1996, Shuttleworth and Cerniglia 1995, Cerniglia 1992, Seech et al. 1993).
Degradation rates vary with depth in sediment partly due to the change from aerobic or anaerobic
conditions. This changes frequently occurs at depths of a few millimeters to a few centimeters where
sediments have substantial organic content and conditions are quiescent, and may occur deeper in some
circumstances. Longer residence times of contaminants in the .sediment (aging) also usually results in
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Chapter 4: Monitored Natural Recovery
increased sequestration (Luthy et al. 1997, Dec and Bollag 1997). These processes reduce the availability
of the organic compounds to microorganisms and, therefore, reduce the extent and rates of biodegradation
(Luthy et al. 1997, Tabak and Govind 1997). However, this also reduces the availability of the
contaminant to receptors living in the sediment and as well as at higher trophic levels.
Chemical processes in sediment are especially important for metals contaminants. Many
environmental variables govern the chemical state of metals in sediment, which in turn affects their
mobility, toxicity, and bioavailablity making natural recovery due to chemical processes difficult to
predict. Much of the current understanding of the role of chemical processes in controlling risk is focused
on the important geochemical changes in bioavailability of metal and organic metal compounds with
changes in redox potential. Formation of relatively insoluble metal sulfides under reducing conditions
often can effectively control the risk posed by metal contaminants if reducing conditions are maintained.
Environmental variables include pore water pH and alkalinity, sediment grain size, oxidation-reduction
(redox) conditions, and the amount of sulfides and organic carbon present in the sediments. Furthermore,
many chemical processes in sedimentary environments are biologically mediated.
Biochemical Processes for Polycyclic Aromatic Hydrocarbons (P AHs)
The class of hydrocarbons known as polycyclic aromatic hydrocarbons (PAHs) is a common
contaminant in sediment and biota at Superfund sites. Many organisms are capable of accumulating P AH
contaminants in their tissue, but biomagnification generally does not occur in vertebrate species (Suendel
et al. 1994). Fish generally do not accumulate higher tissue P AH concentrations than their prey due to
their ability to metabolize and eliminate P AH; however, the P AH metabolites may themselves cause
chronic toxicity, such as reduced growth and reproduction and increased incidence of neoplasms in fish.
The potential exists for biomagnification in some invertebrate species because of their lesser ability to
metabolize and eliminate PAHs (Meador et al. 1995).
P AHs may be subject to physical, chemical and biological breakdown in the environment and
where these processes are effective, may be especially amenable to natural recovery. The type of process
which dominates may depend on time. For example, following a release ofPAHs into the environment,
physical-chemical processes such as dispersion, volatilization, and photodegredation may dominate.
Where these processes are effective in attenuating the contaminants to less toxic levels, tolerant microbial
species may cause further biodegradation. There is a wide variation in levels of microbial activity and
rate of toxicity reduction, depending on the physical and chemical conditions of the site and the
abundance of microbes and other species that influence biodegredation rates (Swindoll et al. 2000).
P AHs biodegrade more quickly through aerobic than anaerobic processes, although the degradation rate
usually decreases as the number of aromatic rings increases (Shuttleworth and Cerniglia 1995, Cerniglia
1992, Seech et al. 1993). While biodegradation ofPAHs may occur under anaerobic conditions, PAHs
usually persist longer in anaerobic sediment compared to aerobic environments (U.S. EPA 1996d, Safe
1980).
Although low P AH degradation rates are often attributed to low bioavailability (see review by
Reid et al. 2000), recent evidence reported by Schwartz and Scow (2001) demonstrates that it may be the
lack of enzyme induction amongst the P AH -degrading bacteria that is responsible for low mineralization
rates below a threshold P AH concentration. Other researchers have reported this phenomenon for P AHs
(Ghiorse et al. 1995, Langworthy et al. 1998) and other aromatic organics (Zaidi et al. 1988, Roch and
Alexander 1997). At elevated PAH concentrations in sediments, there is selective pressure for PAH-
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Chapter 4: Monitored Natural Recovery
degrading bacteria, which can increase the capacity to naturally attenuate P AHs. However, there is
uncertainty about whether and how fast this degradation may reach acceptable risk levels.
Biochemical Processes for Polychlorinated Biphenyls (PCBs)
Release of a PCB Aroclor (see PCB data information in Section 2.1.2, Types of Data) into the
environment may result in a change in its congener composition. This is a result of the combined
weathering effects and such processes as differential volatilization, solubility, sorption, anaerobic
dechlorination, and metabolism, and results in changes in the composition of the PCB mixture in
sediment, water, and biota over time and between trophic levels (NRC 2001).
Highly chlorinated congeners of PCBs may gradually partially dechlorinate naturally in anaerobic
sediment (Brown et al. 1987, Abramowicz and Olsen 1995, Bedard and May 1996). In general, less-
chlorinated PCBs bioaccumulate less than the highly chlorinated congeners, but are more soluble and,
therefore, more readily transported into and within the water column than highly chlorinated PCBs. The
less chlorinated PCBs exhibit significantly less potential human carcinogenic and dioxin-like (coplanar
structure) toxicity (Abramowicz and Olsen 1995, Safe 1992), but may be transformed in humans into
forms with potential for other toxicity (Bolger 1993).
Aerobic processes may then biodegrade the less chlorinated PCB congeners (Flanagan and May
1993, Harkness et al. 1993). The sediment concentrations of other chemicals and the total organic content
tend to control these processes. However, little evidence exists that lower chlorinated congeners under
the anaerobic or anoxic conditions found in most sediment are significantly transformed. Therefore, these
partially dechlorinated organics tend to accumulate and persist (U.S. EPA 1996d, Harkness et al. 1993).
Although desirable, it is unclear whether biologically mediated dechlorination of PCBs would be
effective in achieving remedial objectives in a reasonable time frame and may result in the production of
more toxic byproducts.
4.5
ENHANCED NATURAL RECOVERY
In some areas, natural recovery may appear to be the most appropriate remedy, yet the rate of
sedimentation or other natural processes is insufficient to reduce risks within an acceptable time frame.
Where this is the case, project managers could consider accelerating the recovery process by engineering
means, for example by the addition of a thin layer of clean sediment.' This approach is sometimes referred
to as "thin-layer capping" or "particle broadcasting." Thin-layer placement accelerates natural recovery
by adding a layer of clean sediment over contaminated sediment. The acceleration can occur through
several processes, including increased dilution through bioturbation of clean sediment mixed with
underlying contaminants. Thin-layer placement is different than the isolation caps discussed in Chapter
5, In-situ Capping, because it does not provide as much long-term isolation of contaminants from benthic
organisms. While thickness of an isolation cap can range up to several feet, the thickness of a thin layer
placement could be as little as a few inches. The grain size and organic carbon content of the clean
sediment to be used for thin-layer placement should be carefully considered in consultation with aquatic
biologists. In most cases, natural materials (as opposed to manufactured materials) approximating
common substrates found in the area should be used. Clean sediment can be placed in a uniform thin
layer over the contaminated area or it can be placed- in berms or windrows, allowing natural sediment
transport processes to distribute the clean sediment to the desired areas.
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Chapter 4: Monitored Natural Recovery
Project managers might also consider the addition of flow control structures to enhance
deposition in certain areas of a site. Enhancement or inception of contaminant degradation through
additives might also be considered to speed up natural recovery. However, when evaluating the
feasibility of these approaches, project managers should consult state and federal water programs
regarding the introduction of clean sediment or additives to the water body. For example, in some areas,
potentially erodible clean sediment already is a major non-point source pollution problem, especially in
areas near sensitive environments such as those with significant sub-aquatic vegetation or shellfish beds.
4.6
ADDITIONAL CONSIDERATIONS
MNR is likely to be effective most quickly in stable depositional environments after source
control actions and active remediation of any sediment hot spots have been completed. Where external
sources were controlled many years previously and no discernable hot spot areas can be identified, yet
site risks remain unacceptable, it may be questionable whether natural processes alone will reduce risks
significantly in the future. For MNR, as for other sediment remedies, effective source control is critical to
reaching remedial objectives in a reasonable time frame and to preventing re-contamination.
As discussed in Chapter 7, Remedy Selection Considerations, when evaluating MNR, the short-
term effects on human health and the environment during the recovery period (i.e., the baseline risks for
the site) should be compared to the short-term effects of other approaches such as effects of resuspension
of contaminants due to dredging and habitat changes caused by capping. Section 7.2, Considering
Remedies, discusses the process of comparing short-term and long-term risks associated with various
approaches in a net comparative risk analysis.
In most cases, the long-term effectiveness of MNR is dependent on the dynamic processes of
mixing and burial over time remaining dominant over sediment resuspension or contaminant movement
via advective flow or other mechanisms. Assessment of sediment stability and contaminant mobility are
therefore very important at most sites. Some potential mechanisms for physical disruption of overlying
cleaner sediment, such as keel drag or pipeline construction, may be amenable to human management.
Others mechanisms for physical disruption, such as ice scour or flooding, may only be partly manageable
or not manageable. The importance of contaminant movement through overlying sediment to surficial
sediment and the overlying water depends on the chemical characteristics of the contaminant, physical
characteristics of the sediment, and patterns of ground water flow. Both issues are also of concern for in-
situ capping and discussed further in Chapter 2, Section 2.8, Sediment Stability and Contaminant Fate and
Transport, in Chapter 5, In-Situ Capping, and in the U.S. Army Corps of Engineers (USACE) Technical
Note, Subaqueous Capping and Natural Recovery: Understanding the Hydrogeologic Setting at
Contaminated Sediment Sites (Winter 2002).
Similar to EP A's policy for MNA of ground water and soil, MNR for sediment should generally
be used as one component of an overall site remedy and cautiously as the sole risk reduction approach at a
contaminated sediment site. Generally, MNR should usually be used either in conjunction with source
control or active sediment remediation or as a follow-up measure to an active remedy. For example,
MNR may be an appropriate approach for some sediment sites after control of floodplain soils and NAPL
seeps. At other sites, MNR may be an appropriate approach to control risk from areas of wide-spread,
low-level sediment contamination, following dredging or capping of hot spots. MNR may also be an
appropriate measure to reduce residual risk from dredging or excavation in cases where the active cleanup
is not expected to achieve risk-based measures alone.
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Chapter 4: Monitored Natural Recovery
When considering the use of MNR as a follow-up measure, project managers should consider the
change in conditions caused by the active remedy. As noted by the SAB (U.S. EPA 200Ij): "lfMNA [or,
as used in this guidance, MNR] is to be considered after a remedial action (e.g., the removal of heavily
contaminated portions or capping), the effects of the remedial action on the chemistry, biology, and
physics of contaminated sediments should be evaluated. The effects include: I) potential disturbances on
reaction conditions and aquatic life when dredging is used, and 2) changes on reaction conditions and
mass transfer in the sediment and at the sediment/water interface when capping is used."
MNR should be considered when it would meet remedial objectives within a time frame that is
reasonable compared to active remedies. However, the Agency recognizes that MNR may take longer to
reach cleanup levels in sediment than dredging or in-situ capping and, therefore, may take longer to reach
all remedial action objectives, such as contaminant reductions in fish. It is important to compare time
frames on as accurate a basis as possible, including for example, accurate assessments of time for design
and implementation of dredging or capping and realistic assumptions concerning dredging residuals.
Factors that the project manager should consider in determining whether the time frame for MNR is
"reasonable" include the following:
The extent and likelihood of human exposure to contaminants during the recovery period,
and if controlled by institutional controls, the effectiveness of those controls;
The value of ecological resources that may continue to be impacted during the recovery
period;
The time frame in which affected portions of the site may be needed for future uses
which will be available after MNR has achieved cleanup levels; and
The uncertainty associated with the time frame prediction.
As with any remedy, project managers should carefully evaluate the uncertainties involved and
consider the need for contingency measures, contingency remedies, or interim decisions where there is
significant uncertainty about effectiveness. For MNR, as for other approaches which take a period of
time to reduce risk, project managers should carefully consider how risks can be controlled during the
recovery period. For sites with bioaccumulative contaminants, institutional controls such as fish
consumption advisories are frequently needed to reduce human exposures during this period. In most
cases, no institutional controls are possible for reducing ecological exposure during the recovery period.
See Chapter 3, Section 3.6, Institutional Controls, and Chapter 7, Section 7.4, Considering Institutional
Controls, for more information concerning institutional controls at sediment sites. Highlight 4-5 lists
some important points to remember from this chapter.
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Chapter 4: Monitored Natural Recovery
::::::I!~~!!=~~!:I~ffi!~~mi.K~~!~~~~~f!t8!~ml~;~~~n.g90~~~1~Oq!Mg~:!~II!!N~~~ti!!!R~B9Y~~.::::::'!

Source control generally should be implemented to prevent re-contamination
MNR frequently includes multiple physical, biological, and chemical mechanisms that act together to
reduce risk
Evaluation of MNR usually should be based on site-specific data collected over a number of years. At
some sites, this may include an assessment of seasonal variation for some factors
Project managers should evaluate the long-term stability of the sediment bed, the mobility of
contaminants within it, and the likely ecological and human health impacts of disruption
Multiple lines of evidence are frequently needed to evaluate MNR (e.g., time-series data, core data,
modeling)
Thin-layer placement of clean sediment may accelerate natural recovery in some cases
Contingency measures should be included as part of an MNR remedy when there is significant
uncertainty that the remedial action objectives will be achieved within the predicted time frame
MNR should generally be used as one component of an overall site remedy, and cautiously as the sole
risk reduction approach
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Chapter 5: In-Situ CappinK
5.0
IN-SITU CAPPING
5.1
INTRODUCTION
For purposes of this guidance, in-situ capping refers to the placement of a subaqueous covering or
cap of clean material over contaminated sediment that remains in place. Caps are generally constructed of
granular material, such as clean sediment, sand, or gravel. A more complex cap design can include
geotextiles, liners, and other permeable or impermeable elements in multiple layers that may include
additions of material to attenuate the flux of contaminants (e.g., organic carbon). Depending on the
contaminants and sediment environment, a cap is designed to reduce risk through the following primary
functions:
Physical isolation of the contaminated sediment from the aquatic environment;
Stabilization/erosion protection of contaminated sediment, preventing resuspension and
transport to other sites; and/or
Chemical isolation/reduction of the movement of dissolved and colloidally transported
contaminants into the water body.
Caps may be designed with different layers to serve these primary functions or in some cases a single
layer may serve multiple functions.
In-situ capping has been selected as a component of the remedy for contaminated sediment at
about a dozen Superfund sites as of 200 I and at additional, non-Superfund sites. At some sites, in-situ
capping has served as the primary approach for sediment, and at other sites it has been combined with
sediment removal (i.e., dredging or excavation) or monitored natural recovery (MNR) of other sediment
areas. In-situ capping has not been implemented at many sites in states east of the Rockies, but has been
successfully used at a number of sites in the Pacific Northwest, several of which were constructed over a
decade ago (see site list at http://www.epa.gov/superfund/resources/sedimcnt/sites.htm).
Variations of in-situ capping include installation of a cap after partial removal of contaminated
sediment, innovative caps, which incorporate treatment components, and thin-layer placement, or particle
broadcasting, to enhance natural recovery. Capping is sometimes considered following partial sediment
removal where capping alone is not feasible due to a need to preserve water body depth for navigation or
flood control, or where it is desirable to leave deeper contaminated sediment in place to preserve bank or
shoreline stability following removals. There are a number of pilot studies underway to investigate in-
situ caps which incorporate various forms of treatment (see Chapter 3, Section 3.1.3, In-Situ Treatment
Alternatives). Application of thin layers of clean material may be used to enhance natural recovery
through burial and mixing with clean sediment when natural sedimentation rates are not sufficient (see
Chapter 4, Section 4.5, Enhanced Natural Recovery). Placement of a thin layer of clean material is also
sometimes used to backfill dredged areas, where it mixes with dredging residuals and further reduces risk
from contamination that remains after dredging. In this application, the material is not often designed to
act as an engineered cap to isolate buried contaminants is therefore not considered in-situ capping in this
guidance.
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Chapter 5: In-Situ Cap pin/! 

Much has been written about subaqueous capping of contaminated sediment. The majority of thi~
work has been performed by, or in cooperation with, the U.S. Army Corps of Engineers (USACE).
Comprehensive technical guidance on in-situ capping of contaminated sediment can be found in the U.S.
Environmental Protection Agency's (EP A) Assessment and Remediation of Contaminated Sediment
(ARCS) Program Guidance for In-Situ Subaqueous Capping of Contaminated Sediments (U.S. EP A
1998d), available on the Web at www.epa.gov/glllpo/sedimentliscmain and the Assessment and
Remediation of Contaminated Sediments (ARCS) Program Remediation Guidance Document (U.S. EPA
1 994d). Unless an effective treatment component is incorporated into the cap, in-situ capping does not
generally meet the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA)
~12l(b)(1) preference for treatment. However, just as is the case with many traditional land remedies, if
the proposed remedy meets other requirements, it can still be selected under CERCLA ~12l and existing
guidance. When contaminants left in place are above levels that allow for unlimited use and unrestricted
exposure, five-year reviews generally are necessary (U.S. EP A 200lk).
Although each of the three major remedies (MNR, in-situ capping, and removal) should be
considered at every site at which they might be appropriate, capping should receive detailed consideration
where the site conditions listed in Highlight 5-1 are present.
,',.,',',..,.".",...,..',.,",.,'[[[
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Suitable types and quantities of cap material are readily available
n''',
..
.......
Anticipated infrastructure needs (e.g., piers, pilings, buried cables) are compatible with cap
Water depth is adequate to accommodate cap with anticipated uses (e.g., navigation, flood control)
Incidence of cap-disrupting human behavior, such as large boat anchoring, is low or controllable
Weight of the cap can be supported by the underlying sediment without slope failure
Expected human exposure is substantial and not well-controlled by institutional controls
Long-term risk reduction outweighs habitat disruption, and/or habitat improvements are provided by the
cap
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Chapter 5: In-Situ Cappinl!
5.2
POTENTIAL ADVANTAGES AND LIMITATIONS
Two advantages of in-situ capping are that it can quickly reduce exposure to contaminants and
that, unlike dredging or excavation, it requires less infrastructure in terms of material handling,
dewatering, treatment and disposal. A well-designed and well-placed cap should provide fast reduction in
exposure of fish and other biota to contaminated sediment and often also should provide a clean substrate
for re-colonization by bottom-dwelling organisms. Changes in bottom elevation caused by a cap may
create more desirable habitat, or specific cap design elements may enhance or improve habitat substrate.
Another possible advantage is that the potential for contaminant resuspension and the risks associated
with dispersion and volatilization of contaminated materials during construction are typically much lower
for in-situ capping than for dredging operations. Most capping projects use conventional equipment and
locally available materials, and may be implemented more quickly and may be less expensive than
remedies involving removal and disposal or treatment of sediment.
In-situ capping may be less disruptive of communities than dredging or excavation. Although
some local land-based facilities are often needed for materials handling, usually no dewatering, treatment
or disposal facilities need to be located and no contaminated materials are transported through '\
communities. Where clean dredged material is used for capping, a much smaller area of land facilities is
needed.
The major limitation of in-situ capping is that the contaminated sediment is left in place in the
aquatic environment where contaminants could be exposed or dispersed if the cap is significantly
disturbed or if contaminants move through the cap in significant amounts. In addition, in some
environments it is difficult to place a cap without significant contaminant losses from compaction and
disruption of the underlying sediments. Also, although the cap is designed to reduce exposure of biota to
the contaminated sediment, it is sometimes necessary to rely on institutional controls, which can be
limited in terms of effectiveness and reliability, to protect people from eating fish that were previously
contaminated and to protect the cap from disturbances such as keel drag.
Another potential limitation of in-situ capping may be that in some situations a preferred habitat
may not be provided by the surficial cap materials. To provide erosion protection, it may be necessary to
use coarse cap materials that are different from native soft bottom materials and thus can alter the
biological community. In some cases, however, it may be desirable to select capping materials that
discourage colonization by native deep-burrowing organisms to limit bioturbation.
5.3
EVALUATING SITE CONDITIONS
A good assessment of site-specific conditions typically is critical to understanding the expected
feasibility and effectiveness of in-situ capping. Site conditions can affect all aspects of a capping project,
including design, equipment and cap material selection, and monitoring and management programs.
Some limitations in site conditions can be accommodated in the cap design. A thorough examination of
site conditions should determine if further consideration of capping is appropriate. General aspects of site
characterization are discussed in Chapter 2, Remedial Investigation Considerations. Some specific
aspects of site characterization important for in-situ capping are introduced briefly below.
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Chapter 5: In-Situ Cappin~
5.3.1
Physical Environment
Aspects of the physical environment of an in-situ cap that should be considered include water
body dimensions, depth and slope (bathymetry) of sediment bed, and flow patterns, including tides,
currents, and other potential disturbances in cold climates, such as an ice scour. Existing infrastructure
such as bridges, utility crossings, and other marine structures are discussed in Section 5.3.3.
The bathymetry of the site influences how far cap material will spread during placement and the
cap's stability. Flatter bottom slopes should allow material to be placed more accurately, especially if
capping material is to be placed hydraulically. Water depth also should influence the amount of spread
during cap placement. Generally, the longer the descent of the cap material through the water column, the
more water is entrained in the plume, resulting in a thinner layer of cap material over a larger area.
The energy of flowing water is also an important consideration. Capping projects are easier to
design in low energy environments (e.g., protected harbors, slow-flowing rivers, or micro-tidal estuarine
systems). In open water, deeper sites are generally less influenced by wind or wave generated currents
and less prone to erosion than shallow, near-shore environments. However, armoring techniques or
selection of erosion-resistant capping materials can make capping technically feasible in some high
energy environments. Currents within the water column can affect dispersion during cap placement and
can influence the selection of the equipment to be used for cap placement. . Bottom currents can generate
shear stresses that can act on the cap surface and may potentially erode the cap. In addition to ambient
currents due to normal riverine or tidal flows, the project manager should consider the effects of storm-
induced waves and other episodic events (e.g., floods, ice scour).
The presence of an in-situ cap can alter existing hydrodynamic conditions. In harbor areas or
estuaries, the decrease in depth or change in bottom geometry can affect the near-bed current patterns, and
thus the flow-induced bed shear stresses. In a riverine environment, the placement of a cap generally
reduces depth and restricts flow and may alter the sediment and flood-carrying capacity of the channel.
Modeling studies may be useful to assess these changes in site conditions where they are likely to be
significant. Project managers are encouraged to draft decision documents which include some flexibility
in requirements for how a cap affects carrying capacity of a water body, while still meeting applicable or
relevant and appropriate requirements (ARARs). For example, in some water bodies a cap may be
appropriate even though it decreases the flood-carrying capacity, if that decrease is not significant. In
depositional areas, the effect of new sediment likely to be deposited on the cap should be considered in
predicting future flood-carrying capacity. Clean sediment accumulating on the cap can increase the
isolation effectiveness of the cap over the long term and may also increase consolidation of the
underlying sediment bed.
5.3.2
Sediment Characteristics
The project manager should determine the physical, chemical, and biological characteristics of
the contaminated sediment pursuant to the data quality objective (DQO) process during the remedial
investigation. The results of the characterization, in combination with the remediation goals and
objectives, should determine the areal extent or boundaries of the area to be capped.
Shear strength of contaminated sediment deposits is of particular importance in determining the
feasibility of in-situ capping. Most contaminated sediment is fine-grained, and is usually high in water
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Chapter 5: In-Situ Cappin/[
content and relatively low in shear strength. Although a cap can be constructed on sediment with low
shear strengths, the ability of the sediment to support a cap and the need to construct the cap using
appropriate methods to avoid displacement of the contaminated sediment should be carefully considered.
The presence of other materials within the sediment bed, such as debris, wood chips or high sludge
fractions, or other non-mineral-based sediment fractions, can also present special problems when
interpreting grain size and other geotechnical properties of the sediment. It could be necessary to remove
large debris prior to placing a cap, for exaItlple if it will extent beyond the cap surface and cause scouring.
Side-scan sonar can be an effective tool to identify debris.
The chemical characteristics of the contaminated sediment are an important factor that may affect
design or selection of a cap, especially if capping highly mobile or highly toxic sediment. Capping may
change the uppermost layer of contaminated sediment from an oxidizing to an anoxic condition, which
may change the solubility of metal contaminants and the susceptibility of organic contaminants to
microbial decomposition in this upper zone. For example, many of the divalent metal cations (e.g., lead,
nickel, zinc) become less soluble in anaerobic conditions, while other metal ions (e.g., arsenic) become
more soluble. Mercury becomes methylated through the action of anaerobic bacteria and highly
chlorinated polychlorinated biphenyls (PCBs) may degrade to less chlorinated forms in an anaerobic
environment. These issues are also discussed in Chapter 4, Section 4.4.2.
When contaminated sediments are capped, the organic matter may be decomposed by anaerobic
microorganisms. The products of this decomposition process may include methane and hydrogen sulfide
gases. As these dissolved gases accumulate and transfer into a gaseous phase they could percolate
through the capped matrix by convective or diffusive transport. This transport of gases percolating
through the cap can facilitate a more rapid contaminant migration (than that due to diffusion) by
providing avenues for contaminant release or solubilizing the contaminants of concern and carrying them
through the saturated porous media dissolved in the gaseous molecules. The grain size of the capping
material controls in part how these avenues are developed. Finer grained caps may develop fissures while
coarser grained caps such as sands allow gas to pass through. However, a compensating factor in some
cases is caused by the caps insulation ability, which can cause underlying sediments to stay cooler and
thus reduce expected decomposition rates. Where gas generation is expected to be significant, these
factors should be considered during cap design.
5.3.3
Waterway Uses and Infrastructure
If the site under consideration is adjacent to or within a water body used for navigation, recreation
or flood control, the effect of cap placement on those uses should be evaluated. As described in Section
5.3.1, the flood carrying capacity of a water body could be reduced by a cap. If water depths are reduced
in a harbor or river channel, some commercial and recreational vessels may have to be restricted or
banned. The acceptable draft of vessels allowed to navigate over a cappeq area depends on water level
fluctuations (e.g., seasonal, tidal, and wave) and the potential effects of vessel groundings on the cap.
Potential cap erosion caused by propeller wash should be evaluated. Where circumstances dictate, an
analysis should be conducted for activities which may affect cap integrity such as the potential for routine
anchoring of large vessels. Anchoring by small recreational vessels typically would not compromise the
integrity of most caps. Such activities may indicate the need for restrictions or a modification of the cap
design to accommodate certain activities. It may be necessary to restrict fishing and swimming to prevent
recreational boaters from dragging anchors across a cap. In some situations, partial dredging prior to cap
placement may minimize these limitations of capping.
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Chapter 5: In-Situ CappinK
Other activities in and around the water body may also impact cap integrity and maintenance
needs, and should be evaluated. These include the following:
.
Water supply intakes;
Storm water or effluent discharge outfalls;
Utilities and utility crossings;
Construction of bulkheads, piers, docks, and other waterfront structures;
.
Navigational dredging adjacent to the cap area; and
.
Future development of commercial navigation channels in the vicinity of the cap.
Utilities (e.g., storm drains) and utility crossings (e.g., water, sewer, gas, oil, telephone, cable, and
electric lines) are commonly located in urban waterways. It may be necessary to relocate existing utility
crossings under portions of water bodies if their deterioration or failure might impact cap integrity. More
commonly however, pipes or utilities are left in place under caps, and long-term operation and
maintenance plans include repair of cap damage caused by the need to remove, replace, or repair the pipes
or utilities. Future construction or maintenance of utility crossings would have to consider the cap, and it
may be necessary to consider limiting those activities through institutional controls if cap repair cannot be
assured. The presence of the cap can also place constraints on future waterfront development that could
require dredging in the area.
To date, environmental agencies have little experience with the ability to enforce use restrictions
necessary to protect the integrity of an in-situ cap (e.g., vessel size limits, bans on anchoring, etc.),
although experience is growing. Generally, a state or local enforcement mechanism is necessary to
control specific use restrictions. Project managers should consider mechanisms for compliance assurance,
enforcement, and the consequences of non-compliance, on use restrictions when evaluating in-situ
cappmg.
5.3.4
Habitat Alterations
In-situ capping alters the aquatic environment and, therefore, can affect aquatic organisms in a
variety of ways. As is discussed. further in Chapter 6, Dredging or Excavation, while a project may be
designed to minimize habitat loss or degredation, or even to enhance habitat, both sediment capping and
sediment removal and disposal do alter the environment. Where risks are low and there is the option of
taking action or not, it is important to determine whether the potential loss of a contaminated habitat is a
greater impact than the benefit of providing anew, modified but less contaminated habitat. Habitat
considerations are especially important when evaluating materials for the uppermost layers of a cap.
Sandy sediment and stone armor layers are often used to cap areas with existing fme-grained sediment.
Through time, sedimentation and other natural processes will change the uppermost layer of the cap. At
least initially, changes in organic carbon content of the capping material may change the feeding behavior
of benthic organisms in the capped area. Generally, the uppermost cap layers become a substrate for re-
colonization. Where possible, caps should be designed to provide habitat for desirable organisms. In
some cases it is possible to provide a habitat layer over an erosion protection layer by filling the
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Chapter 5: In-Situ Cappin1:
interstices of armor stones with materials such as crushed gravel. In some cases, natural sedimentation
processes after cap placement can create desirable habitat characteristics. For example, placement of a
rock cap in some riverine systems can result in a fmal cap surface that is similar to that which previously
existed because the rock may become embedded with sands/silts through natural sedimentation.
Desirable habitat characteristics for cap surfaces vary by location. Providing a layer of
appropriately sized rubble that can serve as hard substrate for attached molluscs (e.g., oysters or mussels)
can greatly enhance the ecological value at some sites. Material suitable for colonization by foraging
organisms, such as bottom-dwelling fish, can also be appropriate. A mix of cobbles and boulders may be
desirable for aquatic environments in areas With substantial flow. In addition, the potential for attracting
burrowing organisms incompatible with the cap design or ability to withstand additional physical
disturbances should be considered. Habitat enhancements should not impair the function of the cap or its
ability to withstand the shear stresses of storms, floods, propeller wash, or other disturbances. Project
managers should consult with local resource managers and natural resource trustee agencies to determine
what types of modifications to the cap surface would provide suitable substrate for local organisms.
Habitat considerations are also important when evaluating post-capping bottom elevations.
Capping often increases bottom elevations, which in itself can alter the pre-existing habitat. For example,
a remediated subtidal habitat can become intertidal, or lake habitat can become a wetland (Cowardin et al.
1979). Changes in bottom elevation may enhance or degrade desirable habitat, depending on the site.
Project managers should consult EPA staff working with the Clean Water Act, as well as natural
resource trustees and USACE, where Section 404 of the Clean Water Act is applicable or relevant and
appropriate (see Chapter 3, Section 3.3, Applicable or Relevant and Appropriate Requirements for
Sediment Alternatives). Where remedies are being considered which degrade aquatic habitat, substantive
requirements may include minimizing the permanent loss of habitat and mitigating it by creation or
restoration of a similar habitat elsewhere. However, it should not be assumed that in-situ caps result in a
permanent loss of habitat; this is a site-specific decision. In addition, project managers should be aware
that any mitigation related to meeting the substantive requirements of ARARs for the site, such as the
Clean Water Act, may be independent of the Natural Resource Trustees' natural resource damage
assessment process.
5.4
FUNCTIONAL COMPONENTS OF A CAP
As introduced in Section 5.1 of this chapter, generally caps generally are designed to fulfill three
primary functions: physical isolation, stabilization/erosion protection, at1.d chemical isolation. In some
cases, multiple layers of different materials are used to fulfill these function and in some cases, a single
layer may serve multiple functions. Project managers are encouraged to consider the use of performance-
based measures for caps in remedy decisions, to preserve flexibility in how the cap may be designed to
fulfill these functions.
5.4.1
Physical Isolation Component
The cap should be designed to isolate contaminated sediment from the aquatic environment. The
physical)solation component of the cap should also include a component to account for consolidation of
cap materials.
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Chapter 5: In-Situ Capping
To provide long-term protection, a cap should be sufficiently thick to effectively separate
contaminated sediment from aquatic organisms which dwell or feed on, above, or within the cap. This
serves two functions: 1) to decrease exposure of aquatic organisms to contaminants, and 2) to decrease
the ability of burrowing organisms to move buried contaminants to the surface (i.e., bioturbation). To
design a cap component for this second function, the depth of the effective mixing zone (i.e., the depth of
effective sediment mixing due to bioturbation and/or frequent sediment disturbance) and the population
density of organisms within the sediment profile should be evaluated and considered in selecting cap
thickness. Although not usually a major pathway for contaminant release, project managers should also
be aware of the potential for wetland/aquatic plants to penetrate a cap and create pathways for some
contaminant migration. Especially in marine environments, the potential for colonization by deep
burrowing organisms (e.g., certain species of mud shrimp) could lead to a decision to design a thicker
cap. Measures to prevent colonization or disturbance of the cap by deep burrowing bottom-dwelling
organisms can be considered in cap design, and in developing biological monitoring requirements for the
project. Project managers should refer to Chapter 2, Section 2.8.3 and consult with aquatic biologists
with knowledge of local conditions for evaluation of the bioturbation potential. In some cases, a site-
specific biological survey ofbioturbators would be appropriate. In addition, the USACE Technical Note
Subaqueous Cap Design: Selection of Bioturbation Profiles, Depths and Process Rates (Clarke et al.
2001), provides information on designing in-situ caps and also provides many useful references on
bioturbation. This document (DOER-C2l) is available at
http://www.wes.armv.miVel/dots/doer/technote.html.
The project manager should consider consolidation when designing the cap. Fine-grained
granular capping materials can undergo consolidation due to their own weight. The thickness of granular
cap material should have an allowance for consolidation so that the minimum required cap thickness is
maintained following consolidation. An evaluation of consolidation is important in interpreting
monitoring data to differentiate between changes in cap surface elevation or cap thickness due to
consolidation, as opposed to erosion.
Even if the cap material is not compressible, most contaminated sediment is highly compressible.
Underlying contaminated sediment will almost always undergo consolidation due to the added weight of
the capping material or armor stone. The degree of consolidation should provide an indication of the
volume of pore water that will be expelled through the contaminated layer and capping layer to the water
column due to consolidation. The consolidation-driven advection of pore water should be considered in
the evaluation of short-term contaminant flux. Also, consolidation may decrease the vertical permeability
of the capped sediment and thus reduce long-term flux. Methods used to defme and quantify
consolidation characteristics of sediment and capping materials, such as standard laboratory tests and
computerized models, are available (U.S. EPA 1998d, Palermo et al. 1998a, Liu and Znidarcic 1991).
5.4.2
Stabilization/Erosion Protection Component
This component of the cap is intended to stabilize both the contaminated sediment and the cap
itself to prevent either from being resuspended and transported off site. The potential for erosion
generally depends on the magnitude of the applied bed shear stresses due to river, tidal and wave-induced
currents, turbulence generated by ships/vessels (due to propeller action and vessel draft), and sediment
properties such as particle size, mineralogy and bed bulk density. At some sites, there is also the potential
for seismic disturbance, especially where contaminated sediment or cap material are of low shear'
strength. These and other aspects of investigating sediment stability are discussed in Chapter 2, Section
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Chapter 5: In-Situ Cappin/{
2.8, Sediment Stability and Contaminant Fate and Transport. Conventional methods for analysis of
sediment transport are available to evaluate erosion potential of caps, ranging from simple analytical
methods to complex numerical models (U.S. EPA 1998d, Palermo et al. 1998a). Uncertainty in the
estimate of erosion potential should be evaluated as well.
The design of erosion protection features of an in-situ cap (i.e., armor layers) should be based on
the magnitude and probability of occurrence of relatively extreme erosive forces estimated at the capping
site. At a minimum, in-situ caps should be designed to withstand forces with a probability of 0.01 per
year, for example, the lOO-year storm. As is discussed further in Chapter 2, Section 2.8, Sediment
Stability and Contaminant Fate and Transport, in some circumstances, lower probability events should
also be considered.
Another consideration for capping, especially capping of contaminated sediment with high
organic content (e.g., wood processing sites) is whether significant gas generation due to anaerobic
degradation will occur. Gas generation in sediment beneath the cap could either add significant uplift
forces and threaten the physical stability of the overlying capping materials, or carry significant amounts
of contaminants through the cap. Little has been documented in this area to date, but the possible
influence of this process on cap effectiveness presents an uncertainty that the project manager should
consider in the analysis ofremedial alternatives.
5.4.3
Chemical Isolation Component
If a cap has a properly designed physical isolation component, contaminant migration associated
with the movement of sediment particles should be controlled. However, the vertical movement of
dissolved contaminants by advection (flow of ground water or pore water) through the cap is possible,
while movement of contaminants by molecular diffusion (movement across a concentration gradient) over
long periods usually is inevitable. However, in assessing these processes, it is important to also assess the
sorptive capacity of the cap material, which will act to retard contaminant flux through the cap, and the
long-term fate of capped contaminants which may transform through time. Very slow releases of
dissolved contaminants through a cap at low levels may not create an unacceptable risk. If reduction of
contaminant flux is necessary to meet remedial action objectives, a more involved analysis to include
capping effectiveness testing and modeling should be conducted as a part of cap design. Because of the
uncertainties involved in predicting future flux rates over very long time periods, this guidance does not
advocate a particular minimum rule of thumb for the appropriate time frame for design with respect to
chemical isolation. In general, it is reasonable for the physical isolation component (i.e., physical
stability) ora cap design to be based on a shorter time frame (e.g., a disruptive event with a more frequent
recurrence interval) than the much longer time frames considered in design for chemical isolation (e.g.,
the time required for accumulation of contaminants in the cap material or that required to attain the
maximum chemical flux through the cap), in part because erosion of small areas of a cap is easier to
repaIr.
Nevertheless, both advective and diffusive processes should be considered in cap design. If a
ground water/surface water interaction study indicates that advection is not significant over the area to be
capped (e.g., migration of ground water upward through the cap would not prevent attaining the remedial
action objectives), the cap design may only need to address diffusion and the physical isolation and
stabilization of the contaminated sediment. In this case, it may not be necessary to design for dissolved
and/or colloidally facilitated transport due to advection (Ryan et al. 1995).
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Chapter 5: In-Situ Cappinl[
In contrast, where ground water flow upward through the cap is expected to be significant, the
hydraulic properties of the cap should also be detennined and factored into the cap design. These
properties should include the hydraulic conductivity of the cap materials, the contaminated sediment, and
underlying clean sediment or bedrock. According to a USACE laboratory study, ground water flow
velocities exceeding 10-5 cm/sec potentially result in conditions in which equilibrium partitioning
processes essential to cap effectiveness could not be maintained (Myers et al. 1991). Such conditions
should be carefully considered in the cap design. In areas with high rates of ground water flow through
contaminated sediment, in-situ capping may not be an effective remedial approach without additional
protective measures. Use of amended caps (caps containing reactive or sorptive material to sequester
organic or inorganic contaminants) is one potential option that is undergoing pilot studies (see
http://www.rtdf.org). More infonnation on the interactions of ground water and in-situ caps can be found
in the USACE Technical Note, Subaqueous Capping and Natural Recovery: Understanding the
Hydrogeologic Setting at Contaminated Sediment Sites (Winter 2002).
Where non-aqueous phase liquids (NAPL) are present in part of an area to be capped, the process
for potential contamination migration should be carefully considered. In situations where conventional
cap designs are not likely to be effective, it may be possible to consider impervious materials
(geomembranes, clay, concrete, steel, or plastic) or reactive materials for the cap design. Where this is .
done, however, care must be taken such that head increases along the edges of the impervious area do not
lead to additional NAPL migration. Project managers are encouraged to draw on the experience of others
who have conducted pilot or full scale caps in the presence ofNAPL.
Laboratory tests can be used to calculate sediment- and capping material-specific diffusion and
chemical partitioning coefficients. Several numerical models are available to predict long-tenn
movement of contaminants due to advection and diffusion processes into or through caps, including caps
with engineered components. The models can evaluate the effectiveness of varying thicknesses of
granular cap materials with differing properties [grain size and total organic carbon (TOC)]. The results
generated by such models include flux rates to overlying water and sediment contaminant and pore water
concentrations in the entire sediment and cap profile as a function of time. These results can be compared
to remediation goals such as sediment action levels or applicable water quality criteria in overlying
surface water, or interpreted in tenns of a mass loss of contaminants as a function of time. Results could
also be compared to similar calculations for other remediation technologies.
5.5
OTHER CAPPING CONSIDERATIONS
The general elements or components of an in-situ capping project include those listed .below. A
feasibility study to evaluate in-situ capping for a site should address each of the following:
.
Identifying candidate capping materials that are physically and chemically compatible
with the environment in which they will be placed;
.
Evaluating geotechnical considerations including consolidation of compressible materials
and potential interactions and compatibility among cap components;
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Chapter 5: In-Situ Cappinl!
Assessing placement methods which will minimize short-tenn risk from release of
contaminated porewater and resuspension of contaminated sediment during cap
placement; and
Identifying perfonnance objectives and monitoring methods for cap placement and long-
tenn assessment of cap and biota.
However, many of the aspects are often addressed in more detail during design.
These topics are discussed briefly below. In addition, project managers should refer to Chapter 8,
Section 8.4.2 for a discussion of general monitoring considerations for in-situ capping, and to Chapter 3,
Section 3.6 for a discussion of institutional controls that may relate to caps.
5.5.1
Identification of Capping Materials
Caps are generally composed of clean granular materials, such as upland sand-rich deposits or
sandy sediment; however, more complex cap designs could be required to meet site-specific remedial
action objectives. As discussed below, the project manager should take into consideration the expected
effects of bioturbation, consolidation, erosion, and other related processes on the short- and long-tenn
chemical isolation of contaminants. For example, if the potential for erosion of the cap is significant,
protection could be increased by increasing cap thickness or by engineering the cap to be more erosion-
resistant, through use of cap material with larger grain size, or an armor layer. Porous geotextiles do not
contribute to contaminant isolation, but serve to reduce the potential for mixing and displacement of the
underlying sediment with the cap material. A cap composed of naturally occurring sand is generally
preferred over processed sand because the associated fme fraction and organic carbon content found in
natural sands are more effective in providing chemical isolation by sequestering contaminants migrating
through the cap.
Specialized materials may be used to enhance the chemical isolation ~apacity or otherwise
decrease the thickness of caps compared to sand caps. Examples include engineered clay aggregate
materials (e.g., AquaBlokTM), and reactive/adsorptive materials such as activated carbon, apatite, coke,
organoclay, zero-valent iron and zeolite. Composite geotextile mats containing several of these materials
(i.e., reactive core mats) are beginning to become available commercially.
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Chapter 5: In-Situ Cappinl!
Highlight 5-2 illustrates some examples of cap designs.
A. Eagle Harbor, WA
Geotextlle
B. Sheboygan, WI
G eog rid
C. Convair Lagoon, CA
Source: Modified from U.S. EPA 1998d
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24" Min.
12"
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Chapter 5: In-Situ CappinK
5.5.2
Geotechnical Considerations
Usually, contaminated sediment is predominately fme-grained, and often has high water content
and low shear strength. These materials are generally compressible. Unless appropriate controls are
implemented, contaminated sediment can be easily displaced or resuspended during cap placement.
Following placement, cap stability and settlement due to consolidation can become two additional
geotechnical issues which may be important for cap effectiveness.
As with any geotechnical problem of this nature, the shear strength of the underlying sediment
will influence its resistance to localized bearing capacity or sliding failures, which could cause localized
mixing of capping and contaminated materials. Cap stability immediately after placement is critical,
before any excess pore water pressure due to the weight of the cap has dissipated. Usually, gradual
placement of capping materials over a large area will reduce the potential for localized failures.
Information on the behavior of soft deposits during and after placement of capping materials is limited,
although some field monitoring data have shown successful sand capping of contaminated sediment with
low shear strength. Conventional geoteclmical design approaches should, therefore, be applied with
caution (for example, by building up a cap gradually over the entire area to be capped). Similarly, caps
with flat transition slopes at the edges are not generally subject to a sliding failure normally evaluated by
conventional slope stability analysis.
5.5.3 Placement Methods
A variety of equipment types and placement methods have been used for capping projects. The
use of granular capping materials (Le., sand, sediment, and soil), geosynthetic fabrics, and armored
materials are all in-situ cap considerations discussed in this section. Important considerations in selection
of placement methods include the need for controlled, accurate placement of capping materials. Slow,
uniform application that allows the capping material to accumulate in layers is often necessary to avoid
displacement of or mixing with the underlying contaminated sediment. Uncontrolled placement of the
capping material can also result in the resuspension of contaminated material into the water column.
Granular cap material can be handled and placed in a number of ways. Mechanically excavated
materials and soils from an upland site or quarry usually have relatively little free water. Normally, these
materials can be handled mechanically in a dry state until released into the water over the contaminated
site. Mechanical methods (e.g., clamshells or release from a barge) rely on gravitational settling of cap
materials in the water column, and could be limited by depth in their application. Granular cap materials
can also be entrained in a water slurry and carried to the contaminated site wet, where they can be
discharged by pipe into the water column at the water surface or at depth. These hydraulic methods offer
the potential for a more precise placement, although the energy required for slurry transport could require
dissipation to prevent resuspension of contaminated sediment. Armor layer materials can be placed from
barges or from the shoreline using conventional equipment, such as clamshells. Placement of some cap
components, such as geotextiles, could require special equipment. Examples of equipment types :used for
cap placement are shown in Highlight 5-3. The Guidance for In-Situ Subaqueous Capping of
Contaminated Sediments (U.S. EPA 1998d) contains more detailed information about cap placement
techniques.
Monitoring sediment resuspension and contaminant releases during cap placement is important.
Cap placement can resuspend some contaminated sediment. Contaminants can also be released to the
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Chapter 5: In-Situ Cappin~
water column from compaction of disruption of underlying sediments during cap placement. Both can
lead to increased risks during and following cap placement. Applying cap material slowly and uniformly
can minimize the amount of sediment disruption and resuspension. Therefore, designs should include
plans to minimize and monitor impacts during and after construction.
5.5.4
Performance Monitoring
Performance objectives for an in-situ cap relate to its ability to provide sufficient physical and
chemical isolation and stabilization of contaminated sediment. Broader remedial action objectives for the
site such as decreases in contaminant concentrations in biota or reduced toxicity also should be monitored
when applicable. The following processes should be considered when evaluating the performance of a
cap, and in developing a cap monitoring program:
.
Erosion or other physical disturbance of cap;
Contaminant flux into cap material from underlying contaminated sediment (e.g., ground
water advection, molecular diffusion);
.
Contamination of cap surface from other sources (e.g., unremediated sediment, flood
plains other land-based sources);
Recolonization of cap surface and resulting bioturbation; and
Recovery of biota related to remedial action objectives.
General considerations related to monitoring caps and an example of cap monitoring elements are
presented in Chapter 8, Remedial Action and Long-Term Monitoring.
Performance monitoring of a cap should be related to the design standards and remedial action
objectives related to the site. Generally, physical monitoring is conducted on a more frequent schedule
than chemical or biological monitoring because it is less expensive to perform. Some processes (such as
contaminant flux) are generally not assessed directly because some are very difficult to measure, but are
assessed by measuring contaminant concentrations in bulk samples from the cap surface, in shallow cores
into the surface layer of a cap, and by bathymetric surveys and various photographic techniques. It is
often desirable to establish several permanent locational benchmarks so that repeated surveys can be
accurately compared. In some cases, contaminant flux and the resulting contaminant concentration in
surface sediment, cap pore water or overlying surface water can be compared to site-specific sediment
cleanup levels or water quality standards (e.g., federal water quality criteria or state promulgated
standards). In addition, the concentration of contaminants accumulating in the cap material as a function
of time can be compared to site-specific target cleanup levels during long-term cap performance
monitoring. Both analytical and numerical models exist to predict cap performance and have been
compared and validated with laboratory tests and field results (e.g., Ruiz et al. 1999).
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Chapter 5: In-Situ Cappinl!
......... ..........
.....
.. "".....,...
Source: u.s. EPA 1998d
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Chapter 5: In-Situ CappinK
Highlight 5-4 presents some general points to remember from this chapter.
..............H..tf.i.S:h!~I~!:I~:~Am~~~YR#i.~~~i~m~m~~t~~~h:P~~~~~~t~~O.~~~!~4.G~~pi~~:

Source control generally should be implemented to prevent re-contamination
.......
In-situ caps generally reduce risk through three primary functions: physical isolation, stabilization, and
reduction of contaminant transport .
Caps may be most suitable where water depth is adequate, slopes are moderate, ground water flow
gradients are low or contaminants not mobile, substrates are capable of supporting a cap, and an
adequate source of cap material is available
Evaluation of capping alternatives and design of caps should consider buried infrastructure, such as
water, sewer, electric and phone lines, and fuel pipelines
Substrate and depth alteration from capping should be evaluated for effects on aquatic biota
In evaluating a capping project in natural riverine environments, the project manager should consider a
fluvial system's inherent dynamics, especially the effects of channel migration, flow variability including
extreme events, and ice scour
Evaluation of capping alternatives should include consideration of cap disruption from human and natural
sources, including at a minimum, the 1 DO-year flood and other events such as seismic disturbances with
a similar probability of occurrence
Cap placement methods should be selected to minimize the resuspension of contaminated sediment and
releases of dissolved contaminants from compacted sediment
The use of experienced contractors skilled in marine construction techniques is very important to
placement of an effective cap
In-situ caps should be monitored during and after placement to evaluate long-term integrity of the cap,
recovery of biota, and evidence of re-contamination
Periodic needs for maintenance should be expected for in-situ caps
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Chapter 6: Dredging and Excavation
6.0
DREDGING AND EXCAVATION
6.1
INTRODUCTION
Dredging and excavation are the two most common means of removing contaminated sediment
from a water body, either while it is submerged (dredging) or after water has been diverted or drained
(excavation). Both methods typically necessitate transporting the sediment to a location for treatment
and/or disposal. They also frequently include treatment of water from dewatered sediment prior to
discharge to an appropriate receiving water body. Sediment is dredged on a routine basis at numerous
locations for the maintenance of navigation channels. The objective of navigational dredging is to
remove sediment as efficiently and economically as possible to maintain waterways for recreational,
national defense, and commercial purposes. Use of the term environmental dredging has evolved in
recent years to characterize dredging performed specifically for the removal of contaminated sediment.
Environmental dredging is intended to remove sediment contaminated above certain action levels while
minimizing the spread of contaminants to the surrounding environment during dredging [National
Research Council (NRC 1997)].
The key components to be evaluated when considering dredging or excavation as a cleanup
method are removal, staging and transport, treatment (pre-treatment, treatment of decant, and/or
dewatering effluents and sediment, if necessary), and disposal (liquids and solids). Highlight 6-1
provides an example flow diagram of the possible steps in a dredging or excavation alternative. The
simplest dredging or excavation projects may consist of as few as three of the components shown in
Highlight 6-1. More complex projects may include most or all of these components. Efficient
coordination of each component is very important for a cost-effective cleanup. Project managers should
recognize that, in general, fewer sediment rehandling steps leads to lower implementation risks and lower
cost.
......... ..... ...,......... . dO""" .n. ..... ....." ............ ..... . ..... ...d.. d" ............,",.................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ..................................... [[[
""""""""""",""""""""""'" """""""",,"""""""""""""""""".......................................,.....
[[[
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Chapter 6: Dredging and Excavation
Sediment removal by dredging or excavation has been the most frequent cleanup method for
sediment used by the Superfund program. Dredging or excavation has been selected as a cleanup method
for contaminated sediment at more than 100 Superfund sites (some as an initial removal action). At about
15 to 20 percent of these sites, in-situ cleanup method [i.e., capping or monitored natural recovery
(MNR)] were also selected for sediment at part of the site.
Project managers should also refer to the U.S. Environmental Protection Agency's (EPA's)
Assessment and Remediation of Contaminated Sediments (ARCS) Program Remediation Guidance
Document (U.S. EPA 1994d), and Handbook: Remediation of Contaminated Sediments (U.S. EPA
1991b), the NRC's Contaminated Sediments in Ports and Waterways: Cleanup Strategies and
Technologies (NRC 1997), and Palermo and colleagues' Operational Characteristics and Equipment
Selection Factor for Environmental Dredging (in press) for detailed discussions of the processes and
technologies available for dredging and excavation.
Although each of the three major remedies (MNR, in-situ capping, and removal) should be
considered at every site at which they might be appropriate, sediment removal by dredging or excavation
should receive detailed consideration where the site conditions listed in Highlight 6-2 are present.
....... ........... ...... ""'" ...... ......
',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',.. ..,',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',",',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',",',",',",',',',',',',',",',',',',',',',',',',',',',',",",",",",',',',',',',',',',',',",',',",",',',',',',',',',',',","
.......::::::~,~hj~~~i~t~ffi:~9m~:.~~~9gij~~IBn~:j,ip~B,ii!¥.:@9n~i9,yi~B.p~~~~i,n~:Br:l!e!Y~~~r:::::
Risk is high
Suitable disposal sites are available and nearby
Suitable area is available for staging and handling of dredged material
Existing shoreline areas and infrastructure (e.g., piers, pilings, buried cables) can accommodate dredging or
excavation needs
Navigational dredging is scheduled or planned
Water depth is adequate to accommodate dredge but not so great as to be infeasible; or excavation in the dry is
feasible
Maneuverability and access not unduly impeded by piers, pilings, or other structures
Expected human exposure is substantial and not well-controlled by institutional controls
Long-term risk reduction of sediment removal outweighs sediment disturbance and habitat disruption
Water diversion is practical, or current velocity is low or can be minimized, to reduce resuspension and downstream
transport during dredging
Contaminated sediment is underlain by clean sediment (so that over-dredging is feasible)
Sediment contains low incidence of debris (e.g., logs, boulders, scrap material) or is amenable to effective debris
removal prior to dredging or excavation
High contaminant concentrations cover discrete areas
Contaminants are highly correlated with sediment grain size (to facilitate separation and minimize disposal costs)
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Chapter 6: Dredging and Excavation
6.2
POTENTIAL ADVANTAGES AND LIMITATIONS
One of the advantages of removing contaminated sediment from the aquatic environment often is
that, if it achieves cleanup levels for the site, it may result in the least uncertaintY about long-term
effectiveness of the cleanup, particularly regarding future environmental exposure to contaminated
sediment. Removal of contaminated sediment can minimize the uncertainty associated with predictions
of sediment bed or in-situ cap stability and the potential for future exposure and transport of
contaminants.
Another potential advantage of removal of contaminated sediment is the flexibility it may leave
regarding future use of the water body. In-situ cleanup methods such as monitored natural recovery and
capping frequently need institutional controls that limit water body uses. Although remedies at sites with
bioaccumulative contaminants usually require the development or continuation of fish consumption
advisories for a period of time after removal, other types of institutional controls might not be necessary
to protect a cap or layer of natural sedimentation.
Another possible advantage, where dredging residuals are low, concerns the time to achieve
remedial action objectives. Active cleanup methods such as sediment removal and, particularly, capping
may reduce risk more quickly and achieve remedial action objectives faster than would be achieved by
natural recovery. (However, in comparing time frames between approaches, it is important to include
accurate estimates of the time for design and implementation of active approaches.) Also, although it is
not often cost-effective and therefore not often selected, sediment removal is presently the only cleanup
method that can allow for treatment and/or beneficial reuse of dredged or excavated material. (Caps that
incorporate treatment measures, sometimes called "active" caps, are currently under development by
researchers. See Chapter 3, Section 3.1.3.)
There are also significant potential limitations to sediment removal. Implementation of dredging
or excavation is usually more complex and costly than MNR or in-situ capping because of the removal
technologies themselves (especially in the case of dredging) and the need for transport, staging, treatment
(where applicable), and disposal of the dredged sediment. Treatment technologies for contaminated
sediment frequently offer implementation challenges because of limited full-scale experience and high
cost. In some parts of the country, disposal capacity may be limited in existing municipal or hazardous
waste landfills and it may be difficult to locate new local disposal facilities. Dredging or excavation may
also be more complex and costly than other approaches due to accommodation of equipment
maneuverability and portability/site access. Operations and effectiveness may be affected by utilities and
other infrastructures, surface and submerged structures (e.g., piers, bridges, docks, bulkheads, or pilings),
overhead restrictions, and narrow channel widths.
Another possible limitation of sediment removal is the high level of uncertainty associated with
estimating the extent of residual contamination left following removal. No removal technology can
remove every particle of contaminated sediment, and especially where work is conducted under water,
there can be significant residual contamination. Residual contamination is likely to be greater in the
presence of cobbles, boulders, or buried debris, in high energy environments, at greater water depths, and
where contaminated sediment directly overlies bedrock or a hard bottom. Residuals may also be greater
in very shallow waters and when dredging sediments with high water contents. These complicating
factors can make the sediment removal process and achievement of risk-based remediation goals difficult
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Chapter 6: Dredging and Excavation
complicating factors, were not present. For some sites, this has resulted in not meeting cleanup levels or
remedial action objectives.
Another limitation of dredging may include the potential for significant contaminant losses
through resuspension and, generally to a lesser extent, through volatilization. Resuspension of sediment
from dredging nonnally results in both dissolved and particle-associated releases of contaminants to the
water column. Resuspended particulate material may be redeposited at the dredging site or, if not
controlled, transported to other locations in the water body downstream. Some resuspended contaminants
may also dissolve into the water column where they are more available for uptake by biota. While
aqueous resuspension generally is much less of a concern during excavation, there may be increased
concern with releases to air. Losses en route to and/or at the disposal or treatment site may include
effluent or runoff discharges to surface water, leachate discharges to ground water, or volatile emissions
to air. Each component of a sediment removal alternative typically necessitates additional handling of the
material and presents a possibility of contaminant loss, as well as other potential risks to workers and
communities.
Finally, like for in-situ capping, disruption of the benthic environment nonnally is unavoidable
during dredging or excavation and usually includes at least a temporary destruction of the aquatic
community and habitat within the remediation area. If removed sediment is to be disposed of in an in-
water disposal site, there may be additional impacts to sensitive ecological environments in or near the in-
water disposal site.
Where it is feasible, excavation often has advantages over dredging for the following reasons:
.
Excavation equipment operators and oversight personnel can much more easily see the
removal operation. Although in some cases diver-assisted hydraulic dredging or video-
monitored dredging can be used, turbidity, safety and other technological constraints
typically make it necessary for dredging to be perfonned without visual assistance;
Removal of contaminated sediment is usually more complete (i.e., residual contamination
tends to be lower);
.
Far fewer waterborne contaminants are released when the excavation area has been
dewatered; and
In-water bottom conditions (e.g., debris) and sediment characteristics (e.g., grain size and
specific gravity) typically require much less consider~tion.
However, site preparation for excavation can be more lengthy and costly than for a dredging
project due to the need for dewatering or water diversion. For example, cofferdams, sheet pile walls, or
other diversions/exclusion structures would need to be fabricated and installed. Maneuvering around
diversion/exclusion structures may be required because either earth moving equipment cannot access the
site or double handling may be required to move material outside of the site. In addition, excavation
generally is limited to relatively shallow areas.
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.J
Chapter 6: Dredging and Excavation
6.3
SITE CONDITIONS
6.3.1
Physical Environment
Several aspects of the physical environment may make sediment removal more or less difficult to
implement. In the remedial investigation, the following types of information should be collected, as they
can affect the type of equipment selected and potentially the feasibility of sediment removal:
Bathymetry, slope of the sediment surface and water depth;
Currents and tides;
.
Bottom conditions, especially the presence of debris and large rocks both on top of and
within the sediment bed;
Depth to and (un)evenness of bedrock or hard bottom (e.g., stiff glacial till);
.
Sediment particle size distribution, degree of consolidation, and shear strength;
Thickness and vertical delineation of contaminated sediment;
Distance between dredging and disposal locations;
The presence and maintenance condition of structures such as piers, pilings, cables, or
pipes; and
Land access to water body.
Additionally, sediment removal may change the hydrodynamics and slope stability of the
remediation area. These changes should be evaluated to insure that the removal activity does not cause
bank or structural instability, shoreline facility damages, or other adverse effects in or near the removal
operation that are unacceptable.
Thorough horizontal and vertical characterization of both the physical and chemical sediment
characteristics and characteristics of other physical debris present on top of or buried in the sediment bed
at the site normally is needed during the remedial investigation to evaluate the feasibility, cost, and
potential effectiveness of dredging or excavation. The results of this characterization should help
determine the area, depth, and volume to be removed, and the volume of sediment requiring treatment
and/or disposal. Some aspects of sediment characterization are discussed in Chapter 2, Section 2.1, Site
Characterization.
There are several tests that may help provide the project manager with needed information for
feasibility study or design of dredging, treatment, or disposal methods. In addition, the time and cost
needed to conduct engineering and environmental testing should be considered. The project manager
should refer to Evaluation of Dredged Material Proposed for Disposal at Island, Nearshore or Upland
Confined Disposal Facilities - Testing Manual (USACE 2003) and Evaluation of Dredged Material
Proposedfor Discharge in Waters of the u.s. - Testing Manual (Inland Testing Manual) (U.S. EP A and
.
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Chapter 6: Dredging and Excavation
USACE 1998) for further infonnation. In addition, several guidance documents on estimating
contaminant losses from dredging and disposal have been developed by the EP A and USACE. The
project manager should refer to Estimating Contaminant Losses from Components of Remediation
Alternativesfor Contaminated Sediments (U.S. EPA 1996f).
6.3.2
Waterway Uses and Infrastructures
Any evaluation of the feasibility of a dredging or excavation project should consider impacts to
existing and reasonably anticipated future uses of a waterway. Waterway uses that may need to be
considered when evaluating a sediment removal alternative include the following:
.
Navigation (commercial, military, recreational);
.
Residential/commercial/military moorage;
.
Flood control;
Recreation;
Fishing (subsistence, commercial, recreational);
Water supply, such as presence of intakes;
Stonn water or effluent discharge outfalls;
.
Use by fish and wildlife, especially sensitive or important aquatic habitats;
.
Waterfront development;
.
Utility crossings;
Existing dredge disposal sites; and
Moorage and anchorage areas.
Evaluation of the feasibility of a sediment removal project should include an analysis of whether
impacts to these potential uses may be avoided or minimized both during construction and in the long
tenn.
6.3.3
Habitat Alteration
The proj ect manager should consider the impact of habitat loss or alteration in evaluating a
dredging or excavation alternative. As is also discussed in Chapter 5, In-Situ Capping, while a project
may be designed to minimize habitat loss, or even enhance habitat, sediment removal and disposal, as
well as sediment capping, do alter the environment. It is important to detennine whether the loss of a
contaminated habitat is a greater impact than the benefit of providing a new, modified but less
contaminated habitat. For example, a sediment removal alternative mayor may not be appropriate where
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Chapter 6: Dredging and Excavation
extensive damage to an existing forested wetland will occur. If the contaminated sediment in the wetland
is bioavailable and may be impacting wildlife populations, the short-tenn disruption of the habitat may be
warranted to limit ongoing long-tenn impacts to wildlife. On the other hand, if the wetland is functioning
properly and is not acting as a contaminant source to the biota and the surrounding area, it may be
appropriate to leave it intact rather than remove it. Deliberations as to whether to alter wetland and
aquatic habitats should be a routine component in the remedial decision process, and each site offers its
own unique considerations. Appropriate coordination with natural resource agencies typically will assist
the project manager in detennining the extent of impacts that a dredging project may have on aquatic
organisms or their habitat, and how to minimize these impacts.
Another consideration is avoidance of short-tenn ecological impacts during dredging. This may
involve timing the project to avoid water quality impacts during migration and breeding periods of
sensitive species or designing the dredging project to minimize suspended sediment during dredging and
disposal.
6.4
EXCAVATION TECHNOLOGIES
Excavation of contaminated sediment generally involves isolating the contaminated sediment
from the overlying water body by pumping or diverting water from the area, and managing any
continuing inflow followed by sediment excavation using conventional dryland equipment. However,
excavation may be possible without water diversion in some areas such as wetlands during dry seasons or
while the sediment and water are frozen. Typically, excavation is perfonned in streams, shallow rivers
and ponds, or near shore areas.
Prior to pumping out the water, the area can be isolated using one or more of the following:
.
Sheet piling;
Earthen dams;
Coffer dams;
.
Geotubes, inflatable dams;
.
Rerouting the water.body using temporary dams or pipes; or
Pennanent relocation of the water body.
Sediment isolation using sheet piling commonly involves driving interlocking metal plates (sheet
piles) into the subsurface, and thereby either blocking off designated areas or splitting a stream down the
center. Highlight 6-3 shows an example of where this has been used. If a stream is split down its center,
then one side of the stream may be excavated in the dry, after pumping out the trapped water. When the
excavation of the first side of the stream is completed, water may be diverted back to the excavated side
and sediment on the other side may be excavated. Sheet piling may not be feasible where bedrock or hard
strata are present at or near the bottom surface. Where sheet piling is used to isolate a dredging or
excavation action, project managers should consider potential hydraulic impacts of the diverted flow.
Such diversion in most cases will increase natural flow velocity, which may scour sediment outside the
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Chapter 6: Dredgillg alld Excavatioll
diversion wall. If the sediment is also contaminated, as is likely to be the case, the increased dispersion of
the sediment should be considered in design choices. Temporarily rerouting a water body with dams is
sometimes done for small streams or ponds (Highlight 6-4). This includes the use of temporary dams to
divert the water flow allowing excavation of now "dry" contaminated sediment. The ability and cost to
provide hydraulic isolation of the contaminated area during remediation is a major factor in selecting the
appropriate removal technology.
..
... . '..,", ," ,'..".,',., "'" .. ... - .. ". . .. ..... .. ... . ... .... ... ........... .... ,_.
... ... ... ..... ......... . ... .-. .. ... . ..... .. ..... .... ... ... .
... ...."::::H(~~iigh~:6i~~~¥~i11pl.~9.LEx8~y#.tib,f F911$;.yirigl~qi~tiqh q$mg~H~~~ROJri~:::". ::::....". "
...",...
...""
....
.,.. .
.... .
....... .,
.... .
..,....
Source: Pine RiverNelsicol, EPA Region 5
Once isolated, standing water within the excavation area will need to be removed. Although
surface water flows are eliminated, ground water may infiltrate the confined area. The ground water can
be collected in sumps or dewatering wells. Mter collection, the ground water should be characterized,
managed, treated (if necessary), and discharged to an appropriate receiving water body. Management of
water within the confined area is another important logistical and cost factor that can influence the
decision of wet versus dry removal techniques.
Isolation and dewatering of the area is normally followed by excavation using conventional
earthmoving equipment such as a backhoe or dragline. Where sediment is soft, support of the excavation
equipment in the dewatered area can be problematic because underlying materials may not have the
strength to support equipment weight. This also may reduce excavation depth precision. Both factors
should be accounted for in design. When the excavation activities are complete, temporary dames) or
sheet piling(s) are removed and the water body is restored to its original hydraulic condition.
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Chapter 6: Dredging and Excavation
. ..
..... Bi.gh@ht.~;4:.~~~ro~I~~pffJ~tm.~~~~!9rY.~~~t~tYR~f~g!i~~:.pt~w~!~ij~p~
. ..
.....
..
. .
A: Permanent River Relocation - TrianalTennessee River Site
The TrianalTennessee River Site consists of an 11-mile stretch of two tributaries, the Huntsville Spring Branch and
Indian Creek, which both empty into the Tennessee River. Remedial actions involved rerouting of the channel in
Huntsville Spring Branch (HSB mile 5.4 to 4.0), the filling and burial in place of the total DOT (dichloro diphenyl
trichloroethane and its metabolites) in the old channel, the construction of diversion structures at the upper and
lower end of the stream to prevent stream reversion to the former stream channel, and the diversion of storm water
runoff to prevent flow across the filled channel. Remedial actions for HSB mile 4.0 to 2.4 consisted of constructing
four diversion structures; excavating a new channel between HSB mile 3.4 and 2.4; filling three areas; constructing
a diversion ditch around the fill areas; and excavating portions of the sediment from the channel.
These remedial actions effectively isolated in place 93% of the total DOT in the Huntsville Spring Branch-Indian
Creek system of the Tennessee River. These remedial actions began on April 1 , 1986, and were completed on
October 16, 1987. Through March 1, 2001, the remedial actions have been inspected yearly by a federal and
state Review Panel. The remedial action has not required any repair of the structures to maintain their integrity,
and monitoring has shown that total DOT concentrations in fish and water continue to decline.
B: Temporary ReRouting of a River - Bryant Mill Pond Project at the Allied Paper, Inc./Portage
Creek/Kalamazoo River Site
In EPA Region 5, an EPA-conducted
removal and onsite containment
action removed polychlorinated
biphenyls (PCBs)-contaminated
sediments from the Bryant Mill Pond
area of Portage Creek. During the
removal action, that was conducted
from June 1998 - May 1999, Portage
Creek was temporarily diverted from
its normal streambed so that 150,000
cu yds of the creek bed and floodplain
soils could be excavated using
conventional excavation equipment.
PCB concentrations remaining after
the removal action were below 1 ppm.
Source: u.S. EPA Region 5
Another less common type of excavation project involves permanent relocation of a water body
(also shown in Highlight 6-4). This, for example, was accomplished at the Triana/Tennesee River
Superfund Site in Alabama and is being implemented at the Moss-American Superfund Site in Wisconsin.
The initial phases of such a project may be similar to excavation projects that temporarily reroute a water
body. However, in a pennanent stream relocation project, a replacement stream is constructed and then
the original water body is excavated or capped and converted into an upland area. Because the original
water body is covered over, direct exposure to residual contamination is generally eliminated.
Excavation may also include excavation of sediment in areas that experience occasional dry
conditions, such as intermittent streams and wetlands. These types of projects are logistically similar to
upland construction projects and frequently use conventional earthmoving equipment.
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Chapter 6: Dredging and Excavation
6.5
DREDGING TECHNOLOGIES
For purposes of this guidance, dredging means the removal of sediment from an underwater
environment, typically using floating excavators called dredges. Dredging involves mechanically
grabbing, raking, cutting, or hydraulically scouring the bottom of a waterway to dislodge the sediment.
Once dislodged, the sediment may be removed from a waterway either mechanically with buckets or
hydraulically by pumping. Therefore, dredges may be categorized as either mechanical or hydraulic
depending on the basic means of removing the dredged material. Some dredges employ pneumatic
(compressed air) systems to pump the sediment out of the waterway (U.S. EPA 1994d); however, these
have not generally gained acceptance on environmental dredging projects.
6.5.1
Mechanical Dredging
The fundamental difference between mechanical and hydraulic dredging equipment is the form in
which the sediment is removed. Mechanical dredges offer the advantage of removing the sediment at
nearly the same solids content and, therefore, volume as the in-situ material. Little additional water is
entrained with the sediment as it is removed. Thus, the volumes of contaminated material and process
water to be disposed, managed, and/or treated are minimized. However, the water that is present in the
bucket above the sediment must either be collected, managed, and treated, or be permitted to leak out,
which generally leads to higher contaminant losses during dredging.
The mechanical dredges most commonly used in the U.S. for environmental dredging are the
following (Palermo et al. in press): .
.
Clamshell: Conventional clamshell dredges, wire supported, conventional open clam
bucket, circular shaped cutting action;
Enclosed Bucket: Wire supported, near watertight or sealed bucket as compared to
conventional open bucket (recent designs also incorporate a level cut capability as
compared to a circular-shaped cut for conventional buckets, for example, the Cable Arm
and Boskalis Horizontal Closing Environmental Grab); and
Articulated Mechanical: Backhoe designs, clam-type enclosed buckets, hydraulic closing
mechanisms, all supported by articulated fixed-arm (e.g., Ham Visor Grab, Bean
Hydraulic Profiling Grab (HPG), Toa High Density Transport, and the Dry Dredge).
The mechanical dredge types listed above reflect equipment used for environmental dredging and
generally readily available in the U.S. The enclosed bucket dredges were designed to address a number
of issues often raised relative to remedial dredging induding contaminant removal efficiency and
minimizing sediment resuspension. However, redesigned dredging equipment may not be cost-effective
at every site. For example, in some environments an enclosed bucket may be most useful for soft
sediment but may not close efficiently on debris. A conventional clamshell dredge may have greater
leverage and be able to close on or cut debris in some cases. However, material mounded over the top
may be resuspended. An articulated mechanical dredge may have advantage in stiffer sediment since the
fixed-arm arrangement can push the bucket into the sediment to the desired cut-level, and not rely on the
weight of the bucket for penetration. Highlight 6-5 shows two examples of mechanical dredges including
a type used at New Bedford Harbor.
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Chapter 6: Dredging and Excavation
Note: A = Cable Arm Corp. dredge cutterhead (Source: Cable Arm, Corp.)
B = Bean Company Horizontal Profiling Grab (HPG) dredge, New Bedford Harbor Site (Source: Barbara Bergen, U.S. EPA)
6.5.2
Hydraulic Dredging
Hydraulic dredges remove and transport sediment in the form of a slurry through the inclusion or
addition of high volumes of water at some point in the removal process (Zappi and Hayes 1991). The
total volume of material processed may be greatly increased and the solids content of the slurry may be
considerably less than that of the in-situ sediment although solids content varies between dredges (U.S.
EP A 1994d). The excess water is usually discharged as effluent at the treatment or disposal site and often
needs treatment prior to discharge. Hydraulic dredges may be equipped with rotating blades, augers, or
high-pressure water jets to loosen the sediment (U.S. EP A 1995b). The hydraulic dredges most
commonly used in the U.S. for environmental dredging are the following (Palermo et al. in press):
Cutterhead: Conventional hydraulic pipeline dredge, with conventional cutterhead;
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Chapter 6: Dredging and Excavation
Horizontal AUJ!er: Hydraulic pipeline dredge with horizontal auger dredgehead (e.g.,
Mudcat);
.
Plain Suction: Hydraulic pipeline dredge using dredgehead design with no cutting action,
plain suction (e.g., cutterhead dredge with no cutter basket mounted, Matchbox
dredgehead, articulated Slope Cleaner, Scoop-Dredge BRABO, etc.);
Pneumatic: Air operated submersible pump, pipeline transport, either wire supported or
fixed-arm supported (e.g., Japanese Oozer, Italian Pneuma, Dutch "d", Japanese
Refresher, etc.);
Svecialty DredfJeheads: Other hydraulic pipeline dredges with specialty dredgeheads or
pumping systems (e.g., Boskalis Environmental Disc Cutter, Slope Cleaner, Clean
Sweep, Water Refresher, Clean Up, Swan 21 Systems, etc.); and
Diver Assisted: Hand-held hydraulic suction with pipeline transport.
Some of the hydraulic dredges included above have been specifically developed to reduce
resuspension during the removal process. As with modified mechanical dredges, project managers should
be aware that there may be tradeoffs in terms of production rate and ability to handle debris with many of
these modifications. Highlight 6-6 presents examples of hydraulic dredges.
6.5.3
Dredge Equipment Selection
The selection of appropriate dredging equipment is essential for an effective environmental
dredging operation. The operational characteristics of the three types of mechanical and five types of
hydraulic dredges presented in the guidance sections above are listed in Highlights 6-7a and 6-Th
(palermo et al. in press). This information was reviewed by an expert panel and attendees at a special
session on environment dredging at the Meeting of the Western Dredging Association (WEDA XXI) and
33rd Annual Texas A&M Dredging Seminar in Houston, Texas. The operational characteristics and
selection factors have been drawn from information compiled for the public review draft of this guidance
as well as earlier published reviews of dredge characteristics. Quantitative operational characteristics
(both capabilities and limitations) are summarized for conditions likely to be encountered for many
environmental dredging projects. The numbers are not representative of all dredge designs and sizes
available, but represent those most commonly used for environmental dredging. Qualitative selection
factors for each dredge type are presented based on the best professional judgement and interpretation of
readily available data. Site-specific results and supporting references are available in Palermo and
colleagues' Operational Characteristics and Equipment Selection Factors for Environmental Dredging
(palermo et al. in press).
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Chapter 6: Dredging and Excavation
Note: A = Fox River, WI; horizontal auger hydraulic dredge deployment (Source: Jim Hahnenberg U.S. EPA)
B = Manistique, MI; closeup of twin-vortex pump, hydraulic dredge cutterhead (Source: Ernie Watkins U.S. EPA)
C = Closeup of swinging ladder hydraulic dredge cutterhead (Source: Ellicott Corporation)
The information in Highlights 6-7a and 6-7b is intended to help project managers make initial
assessments of dredge capabilities, and screen equipment types for evaluation at a Feasibility Study stage
or for pilot field testing. It is not intended as a guide for final equipment selection for remedy
implementation. There are many site specific circumstances that dictate which equipment type is most
appropriate for any given situation, and each type can be applied in different ways to adapt to site
conditions. In addition, because new equipment is being continuously developed, project managers will
need to consult with experts who are familiar with the latest technologies. Experience has shown that an
effective environmental dredging operation also depends on the use of highly skilled dredge operators
familiar with the goals of environmental remediation, in addition to close monitoring and management of
the dredging operation.
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Chapter 6: Dredging and Excavation
Operating  48 (2 m3 bucket)   23 (15 cm pump)  Site Equipment 10 Site Specific
Production Rate  95 (4 m3 bucket)   41 (20 cm pump)  Specific Specific  
(m3Ihr)14  143 (6 m3 bucket)   64 (25 cm pump)     
  193 (8 m3 bucket)   93 (30cm pump)     
Percent Solids Near Near Near 5 5 5 15 or Equipment <5 In-Situ
(by weight) 15 In-Situ In-Situ In-Situ    higher Specific  or greater
Vertical . 15 15 10 10 10 10 15 10  5
Operating          
Accuracy (cm)16          
Horizontal 10 10 10 10 10 10 10 10  5
Operating          
Accuracy (cm)17          
Maximum Stability Stability 15 15 5 15 45 15 30 Stability
Dredging Depth Limitations Limitations        Limitations
(m)18          
Minimum     0.5  5  0.5 
Dredging Depth          
(m)19          
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Chapter 6: Dredging and Excavation
Sediment Low High High Medium Medium High High High High High
Resuspension21          
Contaminant Low High High Medium Medium Medium Medium Medium High High
Release          
Control22          
Residual Low Medium Medium Medium Medium Medium Medium Medium High High
Sediment!          
Cleanup Levels23          
Transport by Medium Medium Medium High High High High High High Medium
Pipeline24          
Transport by High High High Medium Medium Medium Medium Medium Low High
Barge25          
Positioning High High High High Medium High High High Medium High
Control in          
currentslwindl          
tides26          
Maneuverability27 High High High Low Low Low Low Low High High
Portabilityl High High High High High High High Medium High High
Access26          
Availability29 High High High High High High Medium Medium High High
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Chapter 6: Dredging and Excavation
Debris/Loose High High High Low Low Low Low Low Low High
Rock!          
Vegetation30          
Hardpan/Rock Low Low Low Low Low Medium Medium Medium High High
Bottom31          
Flexibility for High High Medium High Medium Low Low Low Low High
Varying          
Conditions32          
Thin Low Medium Medium Medium High High High High High High
Lift/Residual          
Removal33          
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Chapter 6: Dredging and Excavation
',',',',',',",'.',',",' .,.".. .....-,.. ,',',',',',',',',',',',',',',',','.','
1
This table provides general information to help project managers initially assess dredge capabilities, and screen and select
equipment types for evaluation at the feasibility study stage or for pilot field testing. This table is NOT intended as a guide
for final equipment selection for remedy implementation. There are many site-specific, sediment-specific, and
project-specific circumstances that will dictate which equipment is most appropriate for any given situation, and each
equipment type can be applied in different ways to adapt to site and sediment conditions. In addition, because new
equipment is being continuously developed, project managers will need to consult with experts who are familiar with the
latest technologies. For additional information on development and technical basis for the entries in this table refer to:
Palermo, M., N. Francingues, and D. Averett. 2005. Operational Characteristics and Equipment Selection Factors for
Environmental Dredging. Journal of Dredging Engineering, Western Dredging Association, in preparation.
2
Equipment types shown here are considered the most commonly used for environmental dredging in the U.S. Other
dredge types are available. Equipment used for environmental dredging is usually smaller in size than that commonly
used for navigation dredging. Information presented here is tailored for mechanical bucket sizes from 3 to 10 cubic yards
(about 2 to 8 cubic meters), and hydraulic/pneumatic pump sizes from 6 to 12 inches (about 15 to 30 cm). Larger sizes
are available for many equipment types.
3
Clamshell- conventional clamshell dredges, wire supported, conventional open clam bucket.
4
Enclosed bucket - wire supported, near watertight or sealed bucket usually incorporating a level cut capability.
5
Articulated Mechanical- backhoe designs, clam-type enclosed buckets, hydraulic closing mechanisms, all supported by
articulated fixed-arm.
6
Cutterhead - conventional hydraulic pipeline dredge, with conventional cutterhead.
7
Horizontal auger - hydraulic pipeline dredge with horizontal auger dredgehead.
8
Plain Suction - hydraulic pipeline dredge using dredgehead design with no cutting action.
9
Pneumatic - air operated submersible pump, pipeline transport, either wire supported or fixed-arm supported.
10
Specialty Dredgeheads - other hydraulic pipeline dredges with specialty dredgeheads or pumping systems
11
Diver assisted - hand-held hydraulic suction with pipeline transport.
12
Dry Excavation - conventional excavation equipment operating within dewatered containments such as sheet-pile
enclosures or cofferdams.
13
OPERATIONAL CHARACTERISTICS are shown as quantitative entries, reflecting capabilities and limitations of dredge
types, and are solely a function of the equipment itself.
14
Production rate - in-situ volume of sediment removed per unit time. Rates shown are for production cuts as opposed to
.cleanup passes" and are for active periods of operation under average conditions. Rates for two bucket or pump sizes
are shown for comparison. For mechanical dredges, the rates were calculated assuming 80% bucket fill with a bucket
cycle time of 2 minutes. For hydraulic dredges, the rates were calculated assuming in-situ sediment 35% solids by weight,
5% solids by weight for slurry, and pump discharge velocity of 10 feet/sec. The rate shown for diver-assisted assumes a
maximum pump size of 15 cm and roughly 50% efficiency of diver effort while working. Production rate for dry excavation
is would be largely dictated by the time required to isolate and dewater the areas targeted for excavation. A variety of
factors may influence the effective operating time per day, week, or season, and should be considered in calculating times
required for removal.
15
Percent solids by weight - ratio of weight of dry solids to total weight of the dredged material as removed, expressed as a
percentage. Percent solids for mechanical dredging is a function of the in-situ percent solids and the effective bucket fill
(expressed as a percentage of the bucket capacity filled by in-situ sediment as opposed to free water), and near in-situ
percent solids is possible for production cuts. A wide range of percent solids for hydraulic dredges is reported, but 5%
solids can be expected for most environmental dredging projects.
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Chapter 6: Dredging and Excavation
. . ... ..... ... .. ..... ........ "' .
..... ....' ..... ..... ............. ....... -...-
""""""""""""""'","'...-....-...-........."...."....".............,"...."..."...."........................... ..".... ............." -[[[
-""""""'.....-..-.........-....-....-....,"......."....".........."..."[[[""""",,",,"""""""..""""""""""""
[[["""'''''''''''''''''''''''''''''''''''''''''''''''''''''''''HHHHH'HHH''''''HHHH"""'H"''''''''''''''''''''''''''''''''''
16
Vertical operating accuracy - the ability to position the dredgehead at a desired depth or elevation for the cut and maintain
or repeat that vertical position during the dredging operation. Although positioning instrumentation is accurate to within a
few centimeters, the design of the dredge and the linkages between the dredgehead and the positioning system will affect
the accuracy attainable in positioning the dredge head. A vertical accuracy of cut of about 15 cm (one-half foot) is
considered attainable for most project conditions. Fixed arm equipment holds some advantage over wire-supported in
maintaining vertical operating accuracy. The accuracies achievable for sediment characterization should be considered in
setting performance standards for environmental dredging operating accuracy (both vertical and horizontal).
17
Horizontal operating accuracy - the ability to position and operate the dredgehead at a desired location or within a desired
surface area. Considerations are similar to those for vertical accuracy.
18
Maximum dredging depth - physical limitation to reach below a given depth. Wire-supported buckets or pumps can be
deployed at substantial depths, so the maximum digging depth is limited by stability of the excavation. Reach of fixed arm
supported buckets or hydraulic dredges is limited by the length of the arm or ladder. Conventional backhoe equipment is
limited to about 15 meters reach. Smaller hydraulic dredges are usually designed for a maximum dredging depth of about
15 meters. Hydraulic dredges also have a limiting depth of removal of about 50 feet due to the limitation of atmospheric
pressure, but this limitation can be overcome by addition of a submerged pump on the ladder. The table entries should
NOT be considered as hard and fast limits. Larger dredge sizes and designs are available for deeper depths.
19
Minimum dredging depth - constraints on draft limitations of some floating dredges or potential loss of pump prime for
hydraulic dredges. Such limitations can be managed if the dredge "digs its way into the area". For smaller dredges, these
limitations are at approximately the 1-meter water depth. Pneumatic dredges require a minimum water depth of about 5
meters for efficient pump operation.
20
SELECTION FACTORS are shown as qualitative entries, reflecting the potential performance of a given dredge type, and
are a function of both the capability of the equipment type and the site and!or sediment conditions. Entries defined as
follows:
(High) - indicating the given dredge type is generally suitable or favorable for a given issue or concern,
(Medium) - indicating the given dredge type addresses the issue or concern, but it may not be preferred, and
(Low) - indicating the given dredge type may not be a suitable selection for addressing this issue or concern.
21
Sediment Resuspension - potential of a given dredge type in minimizing sediment resuspension. Clamshell (Low) -
Circular-shaped cutting action, crate red bottom subject to sloughing, open bucket design subject to washout and spillage,
scows and workboats working in shallow areas. Enclosed Bucket (High) - Seal around the lips of the bucket and an
enclosed top when in the shut position, level cut design minimizes sloughing. Articulated Mechanical (High) - Less
resuspension as compared to conventional clamshell dredges. Cutterhead! Horizontal Auger (Medium) - Conventional
cutterhead dredges and horizontal augers result in less resuspension as compared to conventional clamshell dredges.
May be fitted with hoods or shrouds to partially control resuspension. Plain Suction! Pneumatic (High) - No mechanical
action to dislodge the material. Specialty (High) - Although designs vary, all the so-called specialty dredges have features
specifically intended to reduce resuspension. Diver (High) - Precision of diver assisted hydraulic dredging, the smaller size
of the dredgeheads used, and inherently slow speed of operation. Dry Excavation (High) - Completely isolates the
excavation process from the water column.
22
Contaminant Release Control- the inherent ability to control sediment resuspension and dissolved and volatile releases for
the given equipment type and associated operation. Clamshell (Low) - can be operated such that the excavation and
water column exposure of the bucket is within a silt curtain containment or enclosure, however, high suspended solids
within the silt curtain may be released when the curtain is moved. Enclosed bucket! Articulated Mechanical (Medium) -
can be operated such that the excavation and water column exposure of the bucket is within a silt curtain enclosure with
relatively small footprint. Enclosed buckets act as a control to greatly reduce resuspension within the enclosures and
potential for release. Cutterhead! Plain suction! Horizontal auger! Pneumatic! Specialty Dredgeheads! (Medium) - capable
of transporting the material directly by pipeline, minimizing exposure to the water column and to volatilization. Can be
operated within enclosures, but the footprint of such enclosures would necessarily be larger than that for mechanical
dredges. Diver assisted (High) - scale of diver-assisted dredging would seldom require contaminant release controls. Dry
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Chapter 6: Dredging and Excavation
';';';':':'.',',','.",'.',',',',',',',',',',',',',",......':-:.:-:.:.:.:'.',',',",'.",',',','.':';':':-:':':'.......';':'.'....':':':':':':':':':';'.'.'.'.'...............','.','.','.'.',':':':';':':':':-:'.'.'...........',',',',',',',',',',', ,':';';';';':':';',....,';':',',',',',',':':':':';':';':';,:,;,;,;,:';':"';"""""""""""...'.'.;.:.;.;.:';':':';':';':';':':'..........


....- ..... .....
23
Residual sediment! Cleanup levels - efficiency of the dredge is in removing material without leaving a residual, and
potentially meeting a cleanup criterion. Clamshell (low) - high potential to leave residual sediment because of the
circular-shaped cutting action and the tendency to leave a cratered bottom subject to sloughing. Enclosed bucket!
Articulated Mechanicall Cutterheadl Horizontal augerl Plain Suctionl Pneumaticl Specialty Dredgeheads (Medium) - all
dredges with active dredge heads and/or movement in contact with the bottom sediment will leave some residual sediment.
The control offered by the articulated arm provides an advantage for removal of thin residual layers. Diver assisted (High)
- hand-held action of diver-assisted work has a low potential for generating residual sediment. Dry Excavation (High) - any
fallback of sediment excavated under dry conditions can be readily observed and managed.
24
Transport by Pipeline -compatibility of the dredge with subsequent transport by pipeline. Clamshelll Enclosed bucket!
Articulated Mechanical (Medium) - All mechanical dredges remove material at near in-situ density, and additional reslurry
and rehandling equipment must be employed to allow for pipeline transport. Cutterheadl Plain suctionl Horizontal augerl
Pneumaticl Specialty Dredgeheadsl Diver Assisted (High) - All hydraulic and pneumatic dredges are designed for pipeline
transport. Dry Excavation (Medium) - Additional reslurry and rehandling equipment must be employed to allow for pipeline
transport.
25
Transport by barge - compatibility of the dredge with subsequent transport by barge. Clamshelll Enclosed bucket!
Articulated Mechanical (High) - material excavated with mechanical dredges is close to in-situ density and may be directly
placed in barges for transport. Cutterheadl Plain suctionl Horizontal augerl Pneumaticl Specialty Dredgeheadsl Diver
Assisted (Medium) - barge transport of hydraulically dredged material is inefficient. Although pneumatic and some
specialty dredges are capable of removing soft sediments at high water content, intermittent operation for change-out of
barges will significantly reduce efficiency. Dry Excavation (High) - material excavated in the dry may be placed directly in
barges using conveyers or front-end loaders.
26
Positioning Control in currents/wind/tides - ability of the dredge to hold a desired position of the dredge head horizontally
with current, wind, or vertically with fluctuating tides. Clamshelll Enclosed bucket! Articulated Mechanical (High) - operate
with spuds or jack-up piles and are inherently stable against movement by normal winds and currents. Cutterheadl Plain
suctionl Specialty Dredgeheads (High) - equipped with spuds and use "walking spud" method of operation inherently
stable against movement by normal winds and current. Horizontal auger (Medium) - free floating and operate using an
anchor and cable system, subject to movement with longer anchor sets. Pneumatic (High) - operate from spudded barges
or platforms and are inherently stable against movement by normal winds and currents. Diver assisted (Medium) - ability
of divers to maintain a desired position will be hampered by currents. Dry Excavation (High) - not affected by wind and
currents.
27
Maneuverability - ability of the dredge to operate effectively in close proximity or around utilities and other infrastructure,
narrow channel widths, surface and submerged obstructions, and overhead restrictions. Clamshelll Enclosed bucket!
Articulated Mechanical (High) - buckets are wire supported or fixed-arm articulated and may be operated close in to
infrastructure and within tightly restricted areas. Cutterheadl Plain suctionl Horizontal augerl Pneumaticl Specialty
Dredgeheads (Low) - swinging action of the walking spud method of operation for hydraulic pipeline dredges and the need
for long anchor and cable setup for horizontal auger dredges limits their ability to operate near infrastructure or within
tightly restricted areas. Diver assisted (High) - can be conducted close to infrastructure and within tightly restricted areas.
Dry Excavation (High) - containments for dry excavation can be designed for areas near infrastructure and tightly restricted
areas may be completely contained.
28
Portability/Access - ability of the dredge to pass under bridges, through narrow channels, or to be transported by truck and
easily launched to the site. Clamshelll Enclosed bucket! Articulated Mechanicall Cutterheadl Plain suctionl Horizontal
augerl Pneumatic! Diver assistedl Dry Excavation (High) - dredge types considered here are the smaller size and are
generally truck transportable. Specialty Dredgeheads (Medium) - some specialty dredge designs are too large for truck
transport.
29
Availability - This factor refers to the potential availability of dredges types to contractors and the potential physical
presence of the equipment in the U.S. Clamshell! Enclosed bucket! Articulated Mechanicall Cutterheadl Plain suctionl
Horizontal augerl Pneumatic! Diver assistedl Dry Excavation (High) - Most dredge types are readily available. Specialty
Dredgeheads (Medium) - Some specialty dredges are only available through one contractor, or may be subject to
restrictions under the Jones Act.
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Chapter 6: Dredging and Excavation
... .. ..... ...... .
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.....
30
Debris/Loose RockNegetation - susceptibility of a given dredge type to clogging by debris and subsequent loss of
operational efficiency. Clamshelll Enclosed bucket! Articulated Mechanical (High) - mechanical dredges can effectively
remove sediments containing debris, although leakage may result. Mechanical equipment is the only approach for
debris-removal passes. Cutterheadl Plain suctionl Horizontal augerl Pneumatic! Specialty Dredgeheads (Low) - subject to
clogging by debris and are incapable of removing larger pieces of loose rock and larger debris. Loose rock and large
debris can also cause inefficient sediment removal. Diver assisted (Low) - presence of logs and large debris may present
dangerous conditions for diver-assisted dredging. Although divers can remove sediment from around large debris or
rocks, this type of operation would be inefficient. Dry Excavation (High) - dry excavation allows use of conventional
excavation equipment. Leakage from buckets caused by debris is not a consideration for dry excavation.
31
Hardpanl Rock Bottom - ability of a dredge type to efficiently remove a sediment layer overlying hardpan or rock bottom
without leaving excessive residual sediment. Clamshelll Enclosed bucket! Articulated MechanicaliCutterheadl Horizontal
auger (Low) - closing action of buckets and cutting action of dredgeheads result in problems maintaining a desired vertical
cutting position and would tend to leave behind excessive residual sediment. Power associated with articulated
mechanical has advantage in removing hard materials. Plain suctionl Pneumaticl Specialty Dredges (Medium) - lack an
active closing or cutting action and can operate over an uneven hard surface, although removal efficiency may be low.
Diver assisted (High) - may be the most effective approach for precise cleanup of a hard face, since the divers can feel the
surface and adjust the excavation accordingly. Dry Excavation (High) - allows the visual location of pockets of residual
remaining on an uneven hard surface.
32
Flexibility for Varying Conditions - flexibility of a given dredge type in adapting to differing conditions, such as sediment
stiffness, variable cut thicknesses, and the overall ability to take thick cuts. Clamshelll Enclosed bucket (High) - buckets
are capable of taking thin cuts or thicker cuts in proportion to the bucket size, and bucket sizes can be easily switched.
Articulated Mechanical (Medium) - ability to change bucket sizes for articulated mechanical is limited. Cutterhead (High) -
capable of taking variable cut thicknesses by varying the burial depth of the cutter. Different cutterhead sizes or designs
can be used to adapt to changing cut thicknesses or sediment stiffness. Horizontal auger (Medium) - designed for a set
maximum cut thickness, and attempts to remove thick cuts may result in plowing actions with excessive resuspension and
residual. Plain suctionl Pneumatic (Low) - no cutting action limits ability to take thicker cuts or remove stiffer materials.
Specialty Dredgeheads (Low) - specialty dredges are designed for a specific application and have limited flexibility. Diver
assisted (Low) - removal is limited to thin cuts. Dry Excavation (High) - allows use of a full range of conventional
excavation equipment.
33
Thin lift! residual removal- ability of a given dredge type to removal thin layers of contaminated material without excessive
overdredging. Clamshell (Low) - circular shaped cut not suited to efficient removal of thin layers. Enclosed bucket!
Articulated Mechanical (Medium) - level cutting action is capable of removing thin layers, but the buckets would only be
partially filled, resulting in inefficient production and higher handling and treatment costs. Cutterheadl Horizontal Auger
(Medium) - capable of removing thin layers, but the percent solids is reduced under these conditions. Plain suctionl
Pneumatic (High) -well suited for removal of thin lifts, especially loose material such as residual sediment. Specialty
Dredgeheads (High) - some specialty dredges are designed specifically for removal of thin lifts. Diver assisted (High) -
precision of diver-assisted dredging is well suited for removal of thin layers, especially residuals. Dry Excavation (High) -
allows for a precise control of cut thickness, amenable to removal of thin layers.
6.5.4
Dredge Positioning
An important element of sediment remediation is the precision of the dredge cut, both
horizontally and vertically. Teclmological developments in surveying (vessel) and positioning
(dredgehead) instruments have improved the dredging process. . Vertical control may be particularly
important when contamination occurs in a relatively thin or uneven layer, in order to avoid a more than
necessary amount of over-dredging and excess handling of uncontaminated sediment. Video cameras are
sometimes useful in monitoring dredging operations, although turbidity effects and lack of spatial
references may present limitations to their use. The working depth of the dredgehead may be measured
using acoustic instrumentation and by monitoring dredged slurry densities. In addition, surveying
software may be used to generate pre- and post-dredging bathymetric charts, determine the volume of
dredged sediment, locate obstacles, and calculate linear dimensions of surface areas (see e.g., St.
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Chapter 6: Dredging and Excavation
Lawrence Centre 1993). Digital positioning systems are also available that enable dredge operators to
follow a complex sediment contour (see e.g., Van Oostrum 1992).
Depending on site conditions (e.g., currents, winds, tides), the horizontal position of the dredge
may need to be continuously monitored during dredging. Satellite- or transmitter-based positioning
systems, such as differential global positioning systems (DGPS) can be used to defme the dredge position.
In some cases, however, the accuracy of these systems is inadequate for precise dredging control. Where
the accuracy of site characterization data or the high cost of disposal warrant very precise control, it is
possible to use optical (laser) surveying instruments set up at one or more locations on shore. These
techniques, in conjunction with on-vessel instruments and spuds (if water depths are less than about 50
feet) and anchoring systems may enable the dredge operator to more accurately target specific sediment
deposits. The effectiveness of anchoring systems diminishes as water depth increases.
The positioning technology described above enhances the accuracy of dredging. The accuracies
achievable for sediment characterization should be considered in setting performance standards for
environmental dredging vertical and horizontal operating accuracy (palermo et al. in press). However,
project managers should not develop unrealistic expectations of dredging accuracy. Contaminated
sediment cannot be removed with surgical accuracy even with the most sophisticated equipment.
Equipment may not be the only factor affecting the accuracy of the dredging operation. Site conditions
(e.g., weather, currents), sediment conditions (e.g., bathymetry, physical characteristics), and the skill of
the dredge operator are all important factors. In addition, the distribution of sediment contaminants may
only be defined at a crude level and there could be a substantial margin for error. Accurately dredging to
pre-established cut-lines is an important component of meeting remedial action objectives, but alone is
not generally sufficient for meeting them. The section below describes the equally important factors of
controlling dredging losses and residual contamination.
6.5.5 Predicting and Minimizing Resuspension, Contaminant Release and Transport
During Dredging
Sediment resuspension and unwanted contaminant release and transport in the water body arise
due to a variety of activities associated with a dredging remedy. These frequently include resuspension
caused by operation of the dredgehead, by operation of work boats and tug boats, and by deployment and
movement of control measures such as silt screens or sheet piles. Contaminated sediment may also be
lost from barges used during the dredging operation. In environments with significant water movement
due to tides or currents, resuspended sediment may be transported away from a dredging site; therefore,
limiting resuspension or increasing containment (so that resuspended sediment is later redeposited and
dredged) should be an important consideration. Storm events may also result in transport of contaminants
beyond the dredging area. Use of containment barriers to limit transport of resuspended contaminated
sediment is discussed in Section 6.5.6 of this guidance.
When evaluating the resuspension effects of dredging, it is important to compare these impacts to
baseline conditions including water quality impacts due to any natural sediment disruption that would
continue to occur if the contaminated sediment was not dredged, and consider the length of time over
which dredging-related contaminant releases would occur. In general, two types of contaminant release
are associated with resuspended sediment: particulate and dissolved. Particulate release refers to the
transport of contaminants associated with the particle phase. Dissolved refers to the release of dissolved
contaminants from the particles into the water column. This form of release is significant because
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dissolved contaminants are the most readily bioavailable. Consequently, resuspension can result in the
release ofbioavailable organic and inorganic contaminants into the water column which may cause
toxicity or enhanced bioaccumulation. Research is currently being performed to address the risk
associated with resuspension at contaminated sites. Until further guidance is available, at most sites, it is
important to monitor resuspension during dredging to evaluate its effects on water quality. Project
managers should be aware that most engineering measures implemented to reduce resuspension also
reduce dredging efficiency. Estimates of production rates, cost, and project time-frame, should take these
measures into account.
Some contaminant release and transport during dredging is inevitable and should be factored into
the alternatives evaluation and planned for in the remedy design. Releases can be minimized by choice of
dredging equipment, dredging less area and/or using certain operational procedures (e.g., slowing the
dredge clamshell descent just before impact with the sediment bed.) A careful assessment of all causes of
resuspension is necessary to realistically predict the likely contaminant releases during a dredging
operation. The magnitude of sediment resuspension and resulting transport of contaminants during a
dredging operation is influenced by many factors, including:
Physical properties of the sediment [e.g., grain size distribution, organic carbon content,
Acid Volatile Sulfides (A VS) concentration];
Vertical distribution of contaminants in the sediment;
.
Water velocity and degree of turbulence;
Type of dredge;
Methods of dredge operation;
Skill of operators;
.
Extent of debris;
Water salinity; and
.
Extent of workboatJtugboat activity.
To adequately compare various remedies for a site, to the extent possible, project manager should
estimate the magnitude of these releases, either by comparison to dredging projects in similar
environments or by performing early actions or pilot studies during the feasibility study. However, at
present, no fully verified empirical or predictive tools are available to accurately quantify the predicted
releases. As research in predicting resuspension and contaminant release associated with dredging
progresses, project managers should watch for verified methods to be developed to assist in this estimate.
Although the degree of res us pension will be site-specific, recent analyses offield studies and available
predictive models of the mass of sediment resuspended range from generally less than one percent of the
mass dredged (Hays and Wu 2001, Palermo and Averett 2003) to between 0.5 and 9 percent (NRC 2001).
The methods contained in EPA's Estimating Contaminant Losses from Components of Remediation
Alternatives for Contaminated Sediments (U.S. EP A 1996f), may be useful to estimate the dredgehead
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Chapter 6: Dredging and Excavation
component of resuspension losses. To the extent possible, total dredging losses should be estimated on a
site-specific basis and considered in the comparison of alternatives during the feasibility study.
If conventional clamshell dredges are unacceptable due to anticipated losses, a special purpose
dredge may be considered. These dredges generally resuspend less material than conventional dredges,
but associated costs may be greater and they also may not be usable in the presence of significant debris
or obstructions. 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 (palermo et aJ. 1998b). Other
factors unrelated to resuspension, such as maneuverability requirements, hydrodynamic conditions, or
others listed in Section 6.5.3 above, may also dictate the type of dredge that should be used. The strategy
for the project manager should be to minimize the resuspension levels generated by any specific dredge
type, while also ensuring that the project can be implemented in a reasonable time frame. The EPA's
Office of Research and Development and others are in the process of evaluating resuspension and its
effects, both in field and modeling studies. The results of this research should help project managers to
better understand and control effects of res us pension during future cleanup actions.
Another potential route of contaminant release during dredging or excavation may be the
volatilization of contaminants, either near the dredge or excavation site or in a holding facility like a
confmed disposal facility (CDF) (Chiarenzeli et al. 1998). At sites with high concentrations of volatile
contaminants, dredging or excavation may present special challenges for monitoring and operational
controls if they may pose a potential risk to workers and the nearby community. This exposure route may
be minimized by reducing dredging production rates so that resuspension is minimized. Covering the
surface of the water with a physical barrier or an absorbent compound may also minimize volatilization.
At the New Bedford Harbor site, a cutterhead dredge was modified by placing a cover over the
dredgehead that retained PCB-laden oils, thus reducing the air concentrations of PCBs during dredging to
background levels, see Report on the Efftcts of the Hot Spot Dredging Operations: New Bedford Harbor
Superfund Site, New Bedford, MA (U.S. EPA 1997e and available at
http://www.cua.gov/rcgion01/suDcrfund/sitcs/ncwbcdtord/4n03.udf). In addition, the CDF that the
dredged sediment was pumped into was fitted with a plastic cover that effectively reduced air emissions.
To further minimize the potential for volatile releases, dredging operations were conducted during cooler
weather periods, such as at night. During excavation, volatilization could be of greater concern as
contaminated materials may be exposed to air. Care should be taken in dewatering activities to ensure
that temperatures are not elevated (e.g., cautious application of lime or cement for dewatering), and other
control measure should be taken as needed (e.g., foam).
6.5.6
Containment Barriers
Transport of resuspended contaminated sediment released during dredging can often be reduced
by using physical barriers around the dredging operation. Barriers commonly used to reduce the spread
of contaminants during the removal process include oil booms, silt curtains, silt screens, sheet-pile waij.s,
cofferdams, and bubble curtains (U.S. EPA 1994d, Francingues 2003). Under favorable site conditions
these barriers help limit the areal extent of particle-bound contaminant migration resulting from dredging
resuspension and enhance the long-term benefits gained by the removal process. Conversely, because the
barriers contain resuspended sediment, they may increase, at least temporarily, residual contaminant
concentrations inside the barrier compared to what it would have been without the barriers.
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Chapter 6: Dredging and Excavation
Structural barriers, such as sheet pile walls, have been used for sediment excavation and in some
cases (e.g., high current velocities) for dredging projects. The determination of whether these types of
barriers are necessary should be made based on a thorough evaluation of the site. This can be
accomplished by evaluating the relative risks posed by the anticipated release of contaminants from the
dredging operation absent use of such structural barriers, the predicted extent and duration of such
releases, and the potential for trapping and accumulating residual contaminated sediment within the
barrier. The project manager should consult the Risk Assessment and Modeling Overview Document
(U.S. EPA 1993c) and Estimating Contaminant Lossesfrom Components of Remediation Altemativesfor
Contaminated Sediment (U.S. EPA 1996f) for further information about evaluating the need for structural
barriers.
Sheet pile containment structures are more likely to provide reliable containment of resuspended
sediment than silt screens or curtains, although at significantly higher cost and with different
technological limitations. Where water is removed on one side of the wall, project managers should be
aware of the hydraulic loading effects of water level variations inside and outside of these walls. Project
managers should also be aware of the increased potential for scour to occur around the outside of the
containment area, and the resuspension that will occur during placement and removal of these structures.
In addition, use of sheet piling may significantly change the carrying capacity of a stream or river and
make it temporarily more susceptible to flooding.
Oil booms are appropriate for sediment that may likely release oils or floatables (such as light
non-aqueous-phase liquids, or LNAPL) when disturbed. Such booms typically consist of a series of
synthetic foam floats encased in fabric and connected with a cable or chains. Oil booms may be
supplemented with oil absorbent materials, such as polypropylene mats (U.S. EPA 1994d). However,
booms do not aid in retaining the soluble portion offloatables [e.g., polycyclic aromatic hydrocarbons
(PARs) from oils].
Silt curtains and silt screens are flexible barriers that hang down from the water surface. Both
systems use a series of floats on the surface and a ballast chain or anchors along the bottom. Although the
terms "silt curtain" and "silt screen" may frequently be used interchangeably, there are fundamental
differences. Silt curtains are made of impervious materials, such as coated nylon, and primarily redirect
flow around the dredging area. In contrast, silt screens are made from synthetic geotextile fabrics, which
allow water to flow through, but retain a large fraction of the suspended solids (Averett et al. 1990). Silt
curtains or silt screens may be appropriate when site conditions dictate the need for minimal transport of
suspended sediment, for example when dredging hot spots of high contaminant concentration.
Silt curtains have been used at many locations with varying degrees of success. For example, silt
curtains were found to be effective in limiting suspended solids transport during in-water dike
construction of the CDF for the New Bedford Harbor pilot project. However, the same silt curtains were
ineffective in limiting contaminant migration during dredging operations at the same site primarily as a
result of tidal fluctuation and wind (Averett et al. 1990). Problems ~ere experienced during installation
of silt curtains at the General Motors site (Massena, New York) due to high current velocities and back
eddies. Dye tests conducted after installation revealed significant leakage and the silt curtains were
removed. Sheet piling was then installed around the area to be dredged with silt curtains used as
supplemental containment for hot spot areas. A silt curtain and silt screen containment system was
effectively applied during dredging of the Sheboygan River in 1990 and 1991, where water depths were
two meters or less. A silt curtain was found to reduce suspended solids from approximately 400
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Chapter 6: Dredging and Excavation
milligrams per liter (inside) to 5 milligrams per liter (outside) during rock fill and dredging activities in
Halifax Harbor, Canada (MacKnight 1992). At some sites, changes in dredging operating procedures
may offer more effective control of resuspension than containment barriers.
The effectiveness of silt curtains and screens is primarily determined by the hydrodynamic
conditions at the site. Conditions that may reduce the effectiveness of these and other types of barriers
include the following:
.
Significant currents;
High winds;
Changing water levels, such as tidal fluctuation;
.
Excessive wave height, including ship wakes; and
Drifting ice and debris.
Silt curtains and screens are generally most effective in relatively shallow, undisturbed water. As
water depth increases and turbulence caused by currents and waves increases, it becomes difficult to
isolate the dredging operation effectively from the ambient water. The St. Lawrence Centre (1993)
advises against the use of silt curtains in water deeper than 6.5 meters or in currents greater than 50
centimeters per second.
The effectiveness of containment barriers is also influenced by the quantity and type of
suspended solids, the mooring method, and the characteristics of the barrier. To be effective, barriers
should be deployed around the dredging operation and remain in place until the operation is completed,
although it may need to be opened to allow transport of barges in and out of the dredge site, which may
release some resuspended contaminants. For large projects it may be necessary to relocate the barriers as
the dredge moves to new areas. Where possible, barriers should not impede navigation traffic.
Containment barriers may also be used to protect specific areas, for example valuable habitat, water
intakes, or recreational areas, from suspended sediment contamination.
6.5.7 Predicting and Minimizing Dredging Residuals
All dredging operations leave behind some residual contamination in sediment. Similar to
resuspension releases discussed above, the extent of that residual contamination is dependent on a number
off actors including:
.
Type and size of dredging equipment;
Amount of contaminated sediment resuspended by the dredging operation;
Extent of controls on dispersion of resuspended sediment (e.g., silt curtains, sheet piling);
.
Surface and sub-surface contaminant concentrations in the area to be dredged;
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Chapter 6: Dredging and Excavation
Contaminant concentrations in surrounding un-dredged areas;
.
Characteristics of underlying sediment or bedrock (e.g., whether over-dredging is
feasible);
.
Extent of debris, obstructions or confmed operating area (e.g., which may limit
effectiveness of dredge operation); and
.
Skill of operators.
Project managers should factor a realistic estimate of dredging residuals into their evaluation of
alternatives which include dredging. Field results to date for completed environmental dredging pilots
and projects suggest that average post-dredging residual contamination levels in the past have often not
met desired cleanup levels. However, aside from past experience, there is no commonly accepted method
to predict accurately the exact degree of residual contamination likely to result from use of a given dredge
type to remove a given sediment type under given site conditions. Additional guidelines are needed in
this area and are likely to be developed in the future. Generally, residual concentrations would be
expected to be higher where average contaminant concentrations in the sediment are higher. Residual
contamination also tends to be higher where over-dredging is not possible and where substantial debris is
present in the dredged area. Limitations of site or technology such as these should be factored into the
comparison of alternatives and selection of the best risk reduction alternative for the site.
To achieve cleanup levels, additional passes of the dredge may be needed to achieve the desired
results. Placement of a thin layer of clean material designed to mix with underlying sediment or the
addition of reactive/sorptive materials to surface sediment can also be used to reduce the residual
contamination: Project managers should consider developing a contingency remedy if there is sufficient
uncertainty concerning the ability to achieve low cleanup levels. Where a contingency remedy involves
containment of residuals by in-situ capping, project managers should consider whether containment
without dredging may be a more cost-effective solution.
When conducting post-dredging sampling to confmn residual contamination levels, it is
important to differentiate samples taken within and outside of the dredged area, and to report both a
dredged area residual and a wider residual contaminant concentrations. The former is usually essential
for assessing whether dredging is capable of meeting desired results at the site, and the latter is usually
essential for assessing contaminant levels to which biota will be exposed at the site overall and in
assessing the likelihood of achieving all remedial action objectives.
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Chapter 6: Dredging and Excavation
6.6
TRANSPORT, STAGING, AND DEWATERING
After removal, sediment often is transported to a staging or rehandling area for dewatering (if
necessary), and further processing, treatment, or [mal disposal. Transport links all dredging or excavation
components and may involve several different technologies or modes of transport. The fIrst element in
the transport process is to move sediment from the removal site to the disposal, staging, or rehandling site.
Sediment may then be transported for pretreatment, treatment, and/or ultimate disposal (U. S. EP A
1994d). As noted previously, where possible, project managers should design for as few rehandling
operations as possible, in order to decrease risks and cost. Project managers should also consider
community concerns regarding these operations (e.g., odor, noise, lighting, and other issues). Health and
safety plans should address both workers and community members.
Modes of transportation may include one or more of the following waterborne or overland
technologies:
.
Pioeline: Direct placement of material into disposal sites by pipeline is economical only
when the disposal and/or treatment site is located near the dredging areas (typically a few
kilometers or less unless booster pumps are used). Mechanically dredged material may
also be reslurried from barges and pumped into nearshore disposal sites by pipeline;
.
BarIle: A rehandling facility located on shore is a commonly considered .option. With a
rehandling facility, dredging can be accomplished with mechanical (bucket) dredges
where the sediment is excavated at near in-situ density (water content) and placed in a
scow or barge for transport to the rehandling facility;
Convevor: Conveyors may be used to move material from barges to adjacent rehandling
facilities or to move material relatively short distances. Materials should be in.a
dewatered condition for transport by conveyor;
.
Railcar: Rail spurs may be constructed to link rehandling/treatment facilities to the rail
network. Many licensed landfIlls have rail links, so long-distance transport by rail is
generally an option; and/or
Truck/Trailer: Dredged material can be rehandled directly from the barges to roll-off
containers or dump trucks for transport to a CDF by direct dumping or unloading into a
chute or conveyor. Truck transport of treated material to landfIlls may also be
considered. The material should be dewatered prior to truck transpo~t over surface streets.
In some smaller sites where construction of dewatering beds may be difficult or the cost
of disposal is not great, addition of non -toxic absorbent materials such as lime or cement
may be feasible.
A wide variety of transportation methods are available for moving sediment and residual wastes
with unique physical and chemical attributes. In many cases, contaminated sediment is initially moved
using waterborne transportation. Exceptions are the use of land-based or dry excavation methods.
Project managers should consider the compatibility of the dredge with the subsequent transport of the
dredged sediment. For example, hydraulic and pneumatic dredges produce contaminated dredged-
material slurries that can be transported by pipeline to either a disposal or rehandling site. Mechanical
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removal methods typically produce dense, contaminated material that is hauled by barge, railcar,
truck/trailer, or conveyor systems. The feasibility, costs of transportation, and need for additional
equipment are frequently influenced by the scale of the remediation project (Churchward et al. 1981,
Turner 1984, U.S. EPA 1994e).
Temporary storage of contaminated sediment may also be necessary in order to dewater it prior to
upland disposal or to allow for pretreatment and equalization prior to treatment. For example, a
temporary CDF may be designed to store dredged material for periods when dredging or excavation is not
possible due to weather or environmental concerns, while the treatment process may continue on a near
24-hour operating schedule. Storage may be temporary staging (e.g., pumping onto a barge with frequent
off-loading) or more permanent disposal (e.g., moving the sediment to a land-based CDF where it may be
dewatered and treated). A typical dewatering schematic is shown in Highlight 6-8.
, , . ". .. .. . .. .. . .. .
......................... [[[ .. ..... .........................................
. ..::::..:::::. ....:.::::::.Hiijh!iij~~.~i~~i~P!~~tPtl~ihS..P~o/~t,~~~"9Rr9~~i.
...
....
... ...
.......
....
.......
Depending upon the quality of the water after it is separated from sediment and upon applicable
or relevant and appropriate requirements (ARARs), it may be necessary to treat water prior to discharge.
Where water treatment is required, it can be a costly segment of the dredging project and should be
included in cost estimates for the alternative. Water treatment costs may also affect choices regarding
dredging operation and equipment selection, as both can affect the amount of water entrained.
The project manager should consider potential contaminant losses to the water column and
atmosphere during transport, dewatering, temporary storage, or treatment. For example, conventional
mechanical dredging methods and equipment often rely on gravity dewatering of the sediments on a
dredge scow, with drainage water and associated solids flowing into the surrounding water. Project
managers should evaluate what engineering controls are necessary and cost-effective, and include these
controls in planning and design. Implementation risks, both to workers and to the community, differ
significantly between the various transport methods listed above. These risks should be evaluated and
included when comparing alternatives. Best management practices for protection of water quality should
also be followed.
The risks associated with a temporary storage or staging sites are similar to those associated with
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Chapter 6: Dredging and Excavation
nuisances, especially to waterfowl, by providing attractive habitat that encourages use of the CDF by
wildlife and present the opportunity for exposure to contaminants. For highly contaminated sites, it may
be necessary to provide a temporary cover or sequence dredging to allow for coverage of highly
contaminated sediment with cleaner sediment to minimize short-term exposures. This method of control
has proven effective for minimizing exposures at upland sanitary landfills. In addition, because some
holding areas may not be designed for long-term storage of contaminated sediment, the risk of
contaminant transport to ground water should be evaluated and monitored.
6.7
SEDIMENT TREATMENT
For the majority of sediments removed from Superfund sites, treatment is not conducted prior to
disposal, although pretreatment, such as particle size separation to distinguish between hazardous and
non-hazardous waste disposal options, is common. Although EP A prefers treatment for principal threat
waste, at present it is not frequently selected for sediment, generally due to concerns related to cost,
effectiveness, and/or (for on-site operations) community preferences. However, treatment of sediment is
the best option in some circumstances and innovations in ex-situ or in-situ treatment technologies may
make treatment a more viable cost-effective option at additional sediment sites in the future. Especially
for contaminated sediment that is considered a principal threat waste, project managers should evaluate at
least one alternative that includes treatment of the dredged sediment.
The treatment of contaminated sediment is not usually a single process, but often involves a
combination of processes to address various contaminant problems, including pre-treatment, operational
treatment and/or effluent treatment/residual handling. Some form of pre-treatment and eftluent
treatment/residual handling are necessary at almost all sediment removal projects. Sediment treatment
processes of a wide variety of types have been applied in pilot -scale demonstrations, and some have been
applied full-scale. However, the relatively high cost of most treatment alternatives, especially those
involving thermal and chemical destruction techniques, can be a major constraint on their use (NRC
1997). The base of experience for treatment of contaminated sediment is still limited. Each component
of a potential treatment train is discussed below.
6.7.1
Pre- Treatment
Pre-treatment modifies the dredged or excavated material in preparation for fmal treatment or
disposal. When pre-treatment is part of a treatment train, distinguishing between the two components
may be difficult and is not always necessary. Pre-treatment is generally performed to condition the
material to meet the chemical and physical requirements for treatment or disposal; and/or to reduce the
volume and/or weight of sediment that requires transport, treatment, or restricted disposal. Pre-treatment
processes typically include dewatering and physical or size separation technologies.
Most treatment technologies require that the sediment be relatively homogeneous and that
physical characteristics be within a relatively narrow range. Pre-treatment technologies may be used to
modify the physical characteristics of the sediment to meet these requirements. Additionally, some
pretreatment technologies may divide sediment into separate fractions, such as organic matter, sand, silt,
and clay. Often the sand fractions contain lower contaminant levels and may be suitable for unrestricted
disposal and/or beneficial use if it meets applicable standards and regulations. Selection factors, costs,
pilot-scale demonstrations, and applicability of specific pre-treatment technologies are discussed in detail
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in EP A' s Assessment and Remediation of Contaminated Sediments (ARCS) Program Remediation
Guidance Document (U.S. EPA 1994d).
6.7.2
Treatment
Depending on the contaminant concentration and composition of the sediment, it may be
advisable or necessary to treat the sediment to reduce the toxicity, mobility, or volume of the
contaminants before disposal. In general, treatment processes have the ability to reduce sediment
contaminant concentrations, mobility, and/or sediment toxicity by contaminant destruction or
detoxification, extraction of contaminants from sediment, reduction of sediment volume or sediment
solidification/stabilization.
Treatment technologies for sediment are generally classified as biological, chemical, extraction or
washing, immobilization (solidification/stabilization), and thermal (destruction or desorption). In some
cases, particle size separation is also considered a treatment technology. The following treatment
technologies are among those which might be considered for evaluation.
Bioremediation
Generally, bioremediation is the process in which microbiological processes are used to degrade
or transform contaminants to less toxic or nontoxic forms. In recent years, it has been demonstrated as a
technology for destroying some organic compounds in sediment. The project manager should refer to
EPA (1994d), Myers and Bowman (1999), and Myers and Williford (2000) for a summarization of
bioremediation technologies and their application under site-specific conditions.
Chemical Treatment
Generally, chemical treatment refers to processes in which chemical reagents are added to the
dredged or excavated material for the purpose of contaminant destruction. Contaminants may be
destroyed completely, or may be altered to a less toxic form. Averett and colleagues (1990) reviewed
several general categories of chemical treatment. Of the categories reviewed, treatments including
chelation, dechlorination, and oxidation (of organic compounds) were considered most promising.
Extraction/W ashing
Generally, the primary application of extraction processes is to remove organic, and in some
cases, metal contaminants from the sediment particles. Sediment washing is another term used to
describe extraction processes, primarily when water may be a component of the solvent. In the extraction
process, dredged or excavated material is slurried with a chemical solvent and cycled through a separator
unit. The separator divides the slurry into the three following fractions: 1) particulate solids; 2) water;
and 3) concentrated organic contaminants. The concentrated organics are removed from the separator for
post-process treatment. Extraction or washing also may generate large volumes of contaminated
wastewater that generally must be treated prior to di~charge.
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Immobilization or Solidification/Stabilization
Generally, immobilization, commonly referred to as solidification/stabilizati~n, alters the physical
and/or chemical characteristics of the sediment through the addition of binders, including cements and
pozzolans (U.S. EPA 1994d). Immobilization technologies primarily work by changing the engineering
properties of the sediment so that contaminants are less prone to leaching. Alteration of the physical
character of the sediment to form a solid material, such as a cement matrix, reduces the accessibility of the
contaminants to water and entraps the contaminated solids in a stable matrix (Myers and Zappi 1989).
Another form of immobilization, chemical stabilization, minimizes the solubility of metals primarily
through the control of pH and alkalinity. Chemical stabilization of organic compounds also may be
possible (Barth et al. 2001, Wiles and Barth 1992, Myers and Zappi 1989).
Thermal Treatment
Generally, thermal technologies include incineration, pyrolysis, thermal desorption, sintering, and
other processes that require heating the sediment to hundreds or thousands of degrees above ambient
temperatures. Thermal destruction processes, such as incineration, are generally effective for destroying
organic contaminants but are also expensive and have significant energy costs. Generally, thermal
treatment does not destroy toxic metals.
Particle Size SeDaration
Generally, particle size separation involves separation of the fme material from the coarse
material by physical screening. A site demonstration of the Bergman USA process resulted in the
successful separation of less than 45 micron fmes from washed coarse material and a humic fraction (U. S.
EP A 1994f). As previously noted, particle size separation may serve as a pretreatment step prior to
implementation of a treatment alternative. Many treatment processes require particle sizes of 1 em or less
for optimal operation.
Effluent TreatmentlResidue Handling
Generally, treatment of process effluents means treatment of liquid, gas, or solid residues and is a
major consideration during selection, design, and implementation of dredging or excavation. As shown in
Highlight 6-1, dredging or excavation may require management of several types of residual wastes from
the pretreatment and operational treatment processes that include liquid and/or air/gas effluents from
dewatering or other pretreatment/treatment processes, residual solids and runoff/discharges from active
CDFs. Generally these wastes can be handled through the use of conventiOlial technologies for water, air,
and solids treatment and disposal. However, the technical, cost, and regulatory requirements can be
important considerations during the evaluation of dredging or excavation as a cleanup method.
Pilot and full-scale treatment processes have been conducted at a number of sites, although there
is limited experience at Superfund sites. Where treatment has been used at Superfund sites, the most
common treatment method is immobilization by solidification or stabilization. Additional information
concerning treatment technologies for contaminated sediment may be found in U. S. EP A Office of
Water's Selecting Remediation Technologiesfor Contaminated Sediment (U.S. EPA 1993d). Specific
applications, limitations, specifications, and efficiencies of many sediment treatment processes are
discussed in the ARCS Program's Remediation Guidance Document (U.S. EPA 1994d). The NY/NJ
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Chapter 6: Dredging and Excavation
Harbor Project is an example of a large-scale demonstration of a number of dredged decontamination
technologies, (see HigWight 6-9.)
... .':::H!ijlj~!ijh~i~;':NMtN~.I~~9,if4~'lt;ooP'!~P!.]t~~tffi~i![~~hij~l~i!~~.;~;:p~~Ip,i~tQ~~:"""""
The goal of the NY/NJ Harbor Sediment Decontamination Project is to assemble a complete
decontamination system for cost effective transformation of dredged material into an environmentally safe material
used in the manufacturing of a variety of beneficial use products.
The following four treatment technologies are being used at the NY/NJ site: 1) sediment washing; 2)
thermal treatment; 3) solidification; and 4) vitrification. Each technology has a sponsor from the private sector that
will provide the capital needed for facility construction and operation.
Sediment washing (extraction) uses high-pressure water jets and proprietary chemical additives to extract
both organic and inorganic contaminants from the sediment. The resulting materials can be used to produce
manufactured soil for commercial, and in some cases, residential landscaping applications. The advantages to
this treatment are modest capital costs and high throughput. The patented washing system has been
demonstrated capable of decontaminating sediments containing high quantities of silt and clay.
A thermal treatment being used is a thermo-chemical manufacturing process that, at high temperatures,
will destroy organic contaminants. The process will melt a mixture of sediment and modifiers, and the resulting
product is a manufactured grade cement comparable to Portland Cement. This is a very effective treatment, but
expensive.
A third process is a "treatment train" that includes dewatering, pelletizing, and transport to an existing
light-weight aggregate facility. Pelletizing is a type of solidification treatment. After the sediment is dewatered, it is
mixed with shale fines and extruded into pellets. The pellets are fed into a rotary kiln, and the organic matter
explodes. The resulting material can be used as a structural component in concrete, insulation (pipeline) and for
other geotechnical uses.
Finally, the process includes a high temperature vitrification, which uses an electrical current to heat
(melt) and vitrify the soil in place. This process can destroy organic contaminants and incorporate metals into a
glassy matrix that can be used to produce an architectural tile.
Source: Stern et at 2000, Mulligan et at 2001, Stern 2001, NRC 1997
Potential sediment treatment technologies will continue to change as new technologies are
developed and other technologies are improved. EP A has recognized the need for an up-to-date list of
treatment alternatives and has developed the following databases:
EP A Remediation and Characterization Innovative Technologies (EP A REACH IT):
Provides information on more than 750 service providers that offer almost 1,300
remediation technologies and more than 150 characterization technologies (includes a
variety of media, not just sediment). More information is available at
http://www.epareachit org/index3.html; and
.
EPA National RiskManagement Research Laboratorv (NRMRL) Treatabilitv Database:
Provides results of published treatability studies that have passed the EP A quality .
assurance reviews, it is not specific to sediment, and is available on CD from the EP A' s
National Risk Management Research Laboratory in Cincinnati, Ohio, 45268. Contact
information may be found at http-//www epa goviORD/NRMRL/treat hun.
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Chapter 6: Dredging and Excavation
6.7.3
Beneficial Use
Beneficial use may be an appropriate management option for treated or untreated sediment
resulting from environmental dredging projects. Significant cost saving may be realized if physical and
chemical properties of the sediment allow for beneficial use, especially where disposal options are costly.
For example, at Rouge River/Newburgh Lake, Michigan, a Great Lakes Area of Concern, significant cost
savings were realized by using lightly contaminated dredged sediment as daily cover at a local sanitary
landfill, where it did not pose risk within the landfill boundary. However, beneficial use of dredged or
excavated sediment has only been implemented infrequently to date for remedial projects, mainly due to
lack of cost-effective uses in most instances. Where beneficial use is considered, the contaminant levels
and environmental exposure, including considerations of future land use, should be assessed.
Options for beneficial use may include the following:
e
Construction fill;
eo
Sanitary landfill cover as in the above example;
Mined lands restoration (e.g., Bark Camp Mine Reclamation Project
httu://www.dep.state.Da.us/deu/DEPUT A TE/MINRES/BAMRlbark camu/barkhomepage
.hun);
Sub grade cap material or sub grade in a restoration fill project (topped with clean
sediment or other fill);
Building materials (e.g., architectural tile, see Highlight 6-9); and
Beach nourishment (for a clean sand fraction).
A series of technical notes on beneficial uses of contaminated material has been developed by the
USACE (Lee 2000), and the USACE maintains a Web site of beneficial use case studies which is
currently available at http://www.wes.anny .miVeJ/dots/budm/budm.html. Use of contaminated materials
from CDFs (to include treated material) is a major thrust of the USACE Dredging Operations and
Environmental Research (DOER) program (http://www.wes.annv.millelldotc;/doer). In addition, Barth
and associates evaluated beneficial reuse using several availability tests in an effectiveness protocol
(Barth et al. 2001).
In some cases, a CDF (see description in Section 6.8.2) can be integrated with site reuse plans to
both reduce environmental risk and simultaneously foster redevelopment in urban areas and brownfields
sites. For example, at the Sitcum Waterway cleanup project in Tacoma, Washington, contaminated
sediment was placed in a near shore fill in the Milwaukee Waterway, which was then developed into a
container terminal. Also, there may be innovative and environmentally protective ways to reuse dredged
contaminated sediments in habitat restoration projects (e.g., placement of lightly contaminated material
over highly contaminated materials to build up elevations necessary for fmal placement of clean emergent
marshlands).
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Chapter 6: Dredging and Excavation
6.8
SEDIMENT DISPOSAL
For purposes of this guidance, disposal refers to the placement of dredged or excavated material
and process wastes into a temporary or penn anent structure, site, or facility. The goal of disposal is to
prevent contaminants associated with sediment and/or residual wastes from reentering the environment
and impacting human health and the environment. Disposal typically is a major cost and logistical
component of any dredging or excavation alternative. The identification of disposal locations can often
be the most controversial component of planning and implementing a dredging remedy and therefore
should be considered very early in the Feasibility Study.
Contaminated sediment is typically managed in upland sanitary landfills, or hazardous or
chemical waste landfills, and less frequently, in CDFs, or contained aquatic disposals (CADs). Also, the
material may have a beneficial use in an environment other that the aquatic ecosystem from which it was
removed (e.g., foundation material beneath a newly constructed brownfields site), especially if the
sediment has undergone treatment. As noted below, all disposal options have the potential to create some
risk. These risks may result from routine practices (such as worker exposure and physical risks and
volatilization), while other risks may result from unintended events, such as transportation accidents and
contaminant losses at the disposal site. All potential risks should be considered when comparing
alternatives. The ARCS Program's Remediation Guidance Document (U.S. EPA 1994d) provides a
discussion of the available disposal technologies for sediment, including an in-depth discussion of costs,
design considerations, and selection factors associated with each technology. Averett et al. (1990), EPA
(1991b), and Palenno and Averett (2000) provide additional discussion of disposal options and
considerations.
6.8.1
Sanitary/Hazardous Waste Landfills
Existing commercial, municipal, or on-site sanitary and hazardous waste landfills are the most
widely used option for disposal of dredged or excavated sediment and pre-treatment/treatment residuals
from environmental dredging and excavation. Landfills also are sometimes constructed on-site for a
specific dredging or excavation project. Landfills can be categorized by the types of wastes they accept
and the laws regulating their operation. Most solid waste landfills accept all types of waste (including
hazardous substances) that are not regulated as Resource Conservation and Recovery Act (RCRA)
hazardous waste or Toxic Substances Control Act (TSCA) toxic materials.
Due to typical restrictions on liquids in landfills, most sediment should be dewatered and/or
stabilized/solidified before disposal in a landfill. Temporary placement in a CDF or pretreatment using
mechanical equipment may therefore be necessary (palenno 1995). As also explained in the section on
ARARs in Chapter 2, if sediment containing PCBs are dewatered or physically separated, the dewatered
solids and resulting liquids can then be sampled to determine disposal options. Baring the occurrence of
other contaminants, if PCBs in the dewatered or separated sediment is below 50 ppm, generally, it can be
taken to a municipal sanitary landfill, those greater than 50 ppm generally are taken to a TSCA chemical
waste landfill, while those greater than 500 ppm generally are treated.
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Chapter 6: Dredging and Excavation
6.8.2
Confined Disposal Facilities
CDFs are engineered structures enclosed by dikes and specifically designed to contain
contaminated sediment. With the exception of combined navigational/environmental dredging projects,
CDFs have not been widely used for environmental dredging sites, due in part to siting considerations and
risk concerns. However, they have been used to meet the needs of specific sites, as have other innovative
in-water fill disposal options, for example the filling of a previously used navigational waterway or slip to
create new container terminal space (e.g., Hylebos Waterway cleanup and Sitcum Waterway cleanup in
Tacoma, Washington). In some cases, new nearshore habitat has also been created as mitigation for the
fill.
Under normal operations of a CDF, water is discharged over a weir structure or allowed to
migrate through the dike walls while solids are retained within the CDF. Typically effluent guidelines or
discharge permits govern the monitoring requirements of the return water. Details regarding the
engineering design of CDFs to include sizing to retain solids are available in the USACE Engineer
Manual, Confined Disposal of Dredged Material (USACE 1987).
A cross-sectional view of a typical nearshore CDF dike design is shown in Highlight 6-10. CDFs
may be located either upland (above the water table), near-shore (partially in the water), or completely in
the water (island CDFs). There are several documents available containing thorough descriptions,
technical considerations, and costs associated with CDFs (U.S. EPA 1996f, U.S. EPA 1994d, U.S. EPA
1991b, and Averett et al. 1990). Additionally, Black and Veatch are describing a history and evaluation
of the design and performance of CDFs used for navigational dredging projects in the Great Lakes Basin,
including a review and discussion of relevant contaminant loss and contaminant uptake studies (Black and
Veatch, in prep).
::::':':m,~~iif.~h!~f19;i2~~~~.~~I~~iA!:~:TI!~i:qln{~~~::P!~;~~!F!i!i.!~::g!i~¥f!~h'!:F~~~t.:g~~t~::':."'.:,
Disposal Side
Lake Side
Steet Sheet Piling
Sand FUt.r
Not.: 1ft.. O.3m
Note: Adapted from US. EPA 1998d
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Chapter 6: Dredging and Excavation
6.8.3
Contained Aquatic Disposal
For purposes of this guidance, contained aquatic disposal is a type of subaqueous capping in
which the contaminated dredged sediment is placed into a natural or excavated depression elsewhere in
the water body. A related form of disposal, known as level bottom capping, places the dredged sediment
on a level b~ttom elsewhere in the water body, where it is capped. These disposal options are only very
rarely considered for environmental dredging projects, largely due to risk concerns. However, there may
be instances in which both other disposal options and capping contaminated sediments in-situ are
infeasible. In these instances, it may be appropriate to evaluate CADs. The depression used in the case of
a CAD should provide lateral containment of the contaminated material, and also should have the
advantage of requiring less maintenance and being more resistant to erosion than level-bottom capping.
The depression for the CAD cell may be excavated using conventional dredging equipment or natural or
historically dredged depressions may be used. Uncontaminated material excavated from the depression
may subsequently be used for the cap (U.S. EPA 1994d).
6.8.4
Losses from Disposal Facilities
Evaluation of a new on-site disposal facility for placement of contaminated sediments should
include assessment of contaminant migration pathways and incorporation of management controls in the
facility design as needed. Landfill disposal options may have short-term releases which include spillages
during transport and volatilization to the atmosphere as the sediment is drying. As for any disposal
option, longer-term releases depend in large part on the characteristics of the contaminants and the design
and maintenance of the facility.
For CDFs, contaminants may be lost via effluent during filling operations, surface runoff due to
precipitation, seepage through the bottom and the dike wall, volatilization to the air, and uptake by plants
and animals. The USACE has developed a suite of testing protocols for evaluation of each of these
pathways (U.S. EPA and USACE 1992), and these procedures are included in ARCS guidance for
estimating contaminant release (U.S. EPA 1996f). The USACE has also developed a contaminant
pathway testing and evaluation manual for CDFs (USACE 2003). Depending on the likelihood of
contaminants leaching from the confmed sediment, a variety of dike and bottom linings and cap materials
may be used to minimize contaminant loss (U.s. EPA 1991b, U.S. EPA 1994d, Palermo and Averett
2000). CDFs for sediment remediation projects are more likely to need control measures such as bottom
or sidewall liners or low permeability dike cores than would CDFs constructed for navigation dredged
material.
For CADs, contaminants may be lost to the water column or air during placement of the
contaminated sediment, seepage of pore water during the initial consolidation of the sediment following
placement, and by any of the risk pathways common to in-situ caps, such as through erosion of the cap or
movement of contaminants through the cap (see Chapter 5, In-Situ Capping). Whatever disposal options'
are evaluated, the effects of contaminant losses during construction and in the long term should be
considered.
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Chapter 6: Dredging and Excavation
Highlight 6-11 presents some general points to remember from this chapter.
::~~~~~:':H!ij~!!~~~~M'1t:~!M~~~Y.Rp.lh.~~R.~M~m~!iV!ti.iij'g~i~!~~f~i~:~tili.ijij:':~ij~::'II¥~!@~~::::\'::~
Source control should be generally implemented to prevent re-contamination
A dredging or excavation alternative should include details concerning all phases of the project, including
sediment removal, staging, dewatering, water treatment, sediment transport, and sediment treatment,
reuse, or disposal
Transport and disposal options may be complex and controversial; investigate options early and discuss
them with stakeholders
In predicting risk reduction effects of dredging or excavation of deeply buried contaminants remember
that current risk, and therefore current biota exposure, normally is related only to contaminants that are
bioaccessible
Environmental dredging should be conducted to take advantage of methods of operation, and in some
cases specialized equipment, that minimize resuspension of sediment and transport of contaminants
Project managers should conduct a site-specific assessment or pilot study of anticipated sediment
resuspension, contaminant release and transport, and its potential ecological impacts, prior to full scale
dredging
Project managers should make realistic, site-specific predictions of residual contamination based on pilot
studies or comparable sites. Where over-dredging is not possible, be aware that residual contamination
is generally higher than where this practice is possible
Excavation (conducted after water diversion) often leads to lower levels of residual contamination than
dredging (conducted under standing water)
The use of experienced operators and oversight personnel skilled in environmental dredging or
excavation technologies as well as other phases of the project is very important to an effective cleanup
A dredging or excavation project should be monitored during implementation to assess resuspension and
transport of contaminants, immediately after implementation to assess residuals, and after
implementation to measure long-term recovery of biota and test for re-contamination
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Chaoter 7: Remedv Selection Considerations
7.0
REMEDY SELECTION CONSIDERATIONS
No two sites are identical and therefore the risk-management strategy will vary from site
to site... The strategy selected should be one that actually reduces overall risk, not merely
transfers the risk to another site or another affected population. The decision process
necessary to arrive at an optimal management strategy is complex and likely to involve
numerous site-specific considerations...
Management decisions must be made, even when information is imperfect. There are
uncertainties associated with every decision that need to be weighed, evaluated, and
communicated to affected parties. Imperfect knowledge must not become an excuse for
not making a decision.
In these two statements from the National Research Council's (NRC's) A RiskManagement
Strategy for PCB-Contaminated Sediments report (NRC 2001), the NRC identifies some of the key
challenges faced by many project managers at the remedy selection stage. The program goal of the
Superfund remedy selection process is to select remedies that are protective of human health and the
environment, that maintain protection over time, and that minimize untreated waste (Title 40 Code of
Federal Regulations (40 CFR) ~300.430(a)(1)(i». Superfund remedies must also be cost-effective and
use permanent solutions to the maximum extent practicable (Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA) ~ l2l(b». The best route to meeting these and other
requirements, as well as the best route to overall risk reduction, depends on a large number of site-specific
considerations, some of which may be subject to significant uncertainty. Although decision making in the
face of imperfect knowledge is often necessary, it may be appropriate to postpone a fmal decision if there
is significant doubt about the proposed action's ability to reduce site risks substantially in light of the
potential magnitude of costs associated with addressing certain sediment sites.
This guidance addresses many considerations and uncertainties in the context of the Superfund
program's blueprint, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP).
Consistent with the NCP, each of the risk management principles in the U.S. Environmental
Protection Agency's (EP A's) Principles for Managing Contaminated Sediment Risks at Hazardous Waste
Sites (U.S. EP A 2002a), included in this guidance as Appendix A, is important to consider for achieving a
successful sediment cleanup. Several of the principles apply more directly to the remedy selection stage,
especially Principle 7: "Select site-specific, project-specific, and sediment-specific risk management
approaches that will achieve risk-based goals." Any decision regarding the specific choice of a remedy
for contaminated sediment should be based on a careful consideration of the advantages and limitations of
available approaches and a balancing of tradeoffs among alternatives. This and other risk management
principles that apply at the remedy selection stage are discussed further in Section 7.6, Conclusions.
EPA's Rules of Thumb for Superfund Remedy Selection (U.S. EPA 1997c, also referred to as the
"Rule of Thumb Guidance") is another helpful guidance for project managers to review when selecting
remedies at sediment sites. The Rules of Thumb Guidance describes key principles and expectations,
interspersed with "best practices" based on program experience and policies. In addition, this guidance
discusses how remedy selection may also be applicable to the Resource Conservation and Recovery Act
(RCRA) Corrective Action Program. For more information on the two cleanup programs, the project
January 2005 Draft, Peer Review Document
7-1
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Chapter 7: Remedv Selection Considerations
manager should refer to Office of Solid Waste and Emergency Response (OSWER) Directive 9200.0-25
Coordination Between RCRA Corrective Action and Closure and CERCLA Site Activities (U.S. EPA
1996g).
Decisions regarding remedy selection should also consider pertinent recommendations from
stakeholders, which frequently include the local community, local government, states, tribes, and
responsible parties. Remediation may significantly impact day-to-day activities of residents and
recreation-seekers, and operations of commercial establishments near the water body for extended
periods. Stakeholders should be involved when designing and scheduling remedial operations, not just
during the remedy selection process. Documenting and communicating how and why remedy decisions
are made are very important tasks at sediment sites. For guidance on documenting remedy decisions
under CERCLA, project managers should refer to EP A's A Guide to Preparing Superfund Proposed
Plans, Records of Decision, and other Remedy Selection Documents, also referred to as the "ROD
Guidance" (U.S. EPA 1999a).
7.1
NCP REMEDY SELECTION FRAMEWORK
In the NCP, EPA provides a series of expectations (see Highlight 7-1) to reflect the principal
requirements of CERCLA ~ 121 and to help focus the remedial investigation/feasibility study (RI/FS) on
appropriate cleanup options. EP A developed nine criteria for evaluating remedial alternatives to ensure
that all important considerations are factored into remedy selection decisions. Chapter 3, Feasibility
Study Considerations, outlines the NCP's nine remedy selection criteria in Section 3.2. These criteria are
derived from the statutory requirements ofCERCLA ~12l, as well as technical and policy considerations
that have proven to be important for selecting among remedial alternatives. The nine criteria analysis is
comprised of the following two steps: 1) an evaluation of all alternatives with respect to each criterion;
and 2) a comparison among the alternatives to determine the relative performance of the alternatives and
identify major trade-offs among them (i.e., relative advantages and limitations). Ultimately, the remedy
selected must be protective of human health and the environment, attain (or waive) applicable or relevant
and appropriate requirements (ARARs), be cost effective, use permanent solutions and alternative
treatment technologies or resource recovery technologies to the maximum extent practicable, and satisfy a
preference for treatment or provide an explanation as to why this preference was not met.
The NCP provides that each remedial action selected shall be cost-effective, provided that it first
satisfies the threshold criteria (40 CFR 300.430(f)(ii)(D)). Cost-effectiveness is determined by evaluating
three of the five balancing criteria: 1) long-term effectiveness and permanence; 2) reduction oftoxicity,
mobility, or volume of hazardous substances through treatment; and 3) short-term effectiveness. A
remedy typically is considered cost effective when its cost is proportional to its overall effectiveness. As
described in the Preamble to the NCP, more than one alternative may be considered cost-effective (55
Federal Register (FR) 8728, March 8, 1990). The relationship between overall effectiveness and cost is
examined across all alternatives to identify which options afford effectiveness proportional to their cost.
The evaluation of an alternative's cost effectiveness usually is concerned with the reasonableness of the
relationship between the effectiveness afforded by each alternative and its costs when compared to other
available options (U.S. EPA 1999a). For some complex sediment sites, there may be a high degree of
uncertainty about the predicted effectiveness of various remedial alternatives. Where this is the case, it is
especially important to identify and factor that uncertainty into site decisions.
January 2005 Draft, Peer Review Document
7-2
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Chapter 7: Remedv Selection Considerations
The NCP lists six "expectations" that EP A generally considers in developing appropriate
remedial alternatives at Superfund sites (40 CFR ~300.430(a)(1)(iii». Highlight 7-1 discusses how the
six expectations may be relevant for sites with contaminated sediments. Generally, the expectations are
addressed by seeking the best balance of trade-offs among the alternatives evaluated.
........ ...... .............. . . ........... [[[ ........ ..",
',',',',',',',',', ',',',',',',', ,',",",',',',',',',',',',',',',',',',',',',',',',',",',",',',',',',',',', . ,',',',',',',',',',',',',',',',',',',',',',',',',",',',',",',',',',',',',',',',',',',',',',',',',',',",',',',',',',',',',',',',',', ,',',',',',',',', ',',",'.',

[[[~.:.:.:.:,g.P9n~mln~~~.~!~!m~Q~.:::.:::::::.::.'.:.:....:::...........;:.:::::::..:.:.::.::.
The EPA expects to use treatment to address the principal threats posed by a site, wherever practicable:
.
In general, wastes, including contaminated sediment, may be considered a principal threat where toxicity
and mobility combine to pose a potential human health risk of 10.3 or greater for carcinogens (U.S. EPA
1991 c). For these areas, project managers should evaluate an alternative that includes treatment.
However, the practicability of treatment, and whether a treatment alternative should be selected, should
be evaluated against the NCPs nine remedy selection criteria. Based on available technology, treatment
is not considered practicable at most sediment sites
The EPA expects to use engineering controls, such as containment, for waste that poses a relatively low long-term
threat or where treatment is impracticable:
.
Containment options for sediment generally focus on in-situ capping. Where possible, a project manager
should evaluate in-situ capping for every sediment site that includes low-level threat waste. Where a
containment alternative is clearly not appropriate for a detailed evaluation, project managers should
evaluate ex-situ containment (i.e., disposal without treatment). It should be recognized that in-situ
containment can also be effective for principal threat wastes, where that approach represents the best
balance of the NCP nine remedy selection criteria
The EPA expects to use a combination of methods, as appropriate, to achieve protection of human health and the
environment
.
Large or complex contaminated sediment sites or operable units frequently require development of
altematives that combine various approaches for different parts of the site. For a broader discussion on
this topic, refer to Chapter 3, Section 3.1.1, Altematives that Combine Approaches
The EPA expects to use institutional controls, such as water use and deed restrictions, to supplement engineering
controls as appropriate for short- and long-term management to prevent or limit exposure to hazardous
substances, pollutants, or contaminants:
.
Institutional controls such as fish consumption advisories, fishing bans, ship draft/anchoring/wake
controls, or structural maintenance requirements (e.g., dam or breakwater maintenance) are frequently a
part of sediment alternatives, especially where contaminated sediment is left in place, or where remedial
goals in fish tissue cannot be met for some time. See Chapter 3, Section 3.6, Institutional Controls, for
additional discussion
The EPA expects to consider using innovative technology when such technology offers the potential for
comparable or superior treatment performance or implementability, fewer or lesser adverse impacts than other
available approaches, or lower costs for similar levels of performance than demonstrated technologies:
.
Innovative technologies are technologies whose limited number of applications may result in less cost and
performance data, frequently due to limited field application. Additional cost and performance data may
be needed for many sediment remedies, and field demonstrations of new techniques and approaches
especially may be needed, including both innovative in-situ and ex-situ technologies. Although most
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Chaoter 7: Remedv Selection Considerations
The EPA expects to return reusable ground waters to their beneficial uses wherever practicable, within a time
frame that is reasonable given the circumstances for the site. \I\I11en restoration of ground water to beneficial uses
is not practicable, EPA expects to prevent further migration of the plume, prevent exposure to the contaminated
ground water, and evaluate further risk reduction:
Ground water may be a continuing source of sediment and surface water contamination. \I\I11ere this is
the case, ground water migration prevention may be very important to a successful sediment cleanup and
to protect benthic biota. Ground water restoration may also be needtd in order to return the ground water
to a beneficial use
7.2
CONSIDERING REMEDIES
If the baseline risk assessment determines that contaminated sediment presents an unacceptable
risk to human health or the environment, remedial alternatives should be developed to reduce those risks
to acceptable levels. As discussed in Chapter 3, Section 3.1, Developing Remedial Alternatives for
Sediment, due to the limited number of approaches available for contaminated sediment, generally,
project managers should evaluate each of the three major approaches: monitored natural recovery (MNR),
in-situ capping, and removal through dredging or excavation, at every sediment site where they might be
appropriate. Depending on site-specific conditions, contaminant characteristics, and/or health or
environmental risks at issue, certain methods or combinations of methods may prove more promising than
others. Each site and the various sediment areas within it presents a unique combination of circumstances
that should be considered carefully in selecting a comprehensive site-wide cleanup strategy. At large or
complex sediment sites, the remedy decision frequently involves choices between areas of the site and
how they are best suited to particular cleanup methods, rather than a simple one-size-fits-all choice
between approaches for the entire site.
Project managers should keep in mind that deeper contaminated sediment that is not currently
bioavailable or bioaccessible, and that analyses have shown to be stable to a reasonable degree, do not
necessarily contribute to site risks. The decision whether or not to leave buried contaminated sediment in
place should include an analysis of several factors, including the potential for erosion due to natural or
anthropogenic forces, and the effectiveness of any institutional controls to limit disturbance. In some
cases, the most appropriate approach may be long-term monitoring, with contingency actions, if
necessary .
To assist project managers in evaluating cleanup options, two summary highlights are presented
below. They are not requirements or expectations for the use of the three approaches.
Highlight 7-2 provides general site, sediment, and contaminant characteristics that are especially
conducive to each of the three common sediment approaches. This highlight is intended as a general tool
for project managers as they look more closely at particular approaches when most of these characteristics
are present. It is important to remain flexible when evaluating sediment alternatives and consider
approaches that at first may not appear most appropriate for a given environment. When an approach is
selected for a site which has one or more site characteristics or conditions that appear problematic,
additional engineering or institutional controls may be available to enhance the remedy. Some of these
situations are discussed in the remedy-specific chapters (Chapters 4, 5, and 6).
January 2005 Draft, Peer Review Document
7-4
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Chanter 7: Remedv Selection Considerations
. .. . .
',',',",",',','.. ".',".",'.",',',',',',",".',',".',', .".".",".'.".',',",".',',",",',".",". ,".',',".",',".','.",',',',',',',',',',. ,",'.",".",",'.',',','.','.".".".'.'.",',',',",",",",",",",",',",',',',',',', ,".".".",",','.".',',',".', .'.'.".".'.".",".".".".'...'.",".'.'.".'.'.",'.'. ,', ,'.',",",',','.',',',',',',',',',',',',',',',',",',''',',',',',',',',',',',
:::.::ft.i.9H!!g6.!:~g;~p.m~~!i:gpQ~~~~g6.!:~I~!~I.!y;qP.O~9~1.Y~:19:R~r11~9.!~r.;R~m~~I.~I.:;Appr91~fj~~:~::::::;
:::::::::::::::::::::::::::::::::.:::::;;;;;;f:9fHPV!mJ.9~~~#.;~!q!m~i.1~;;:;:.::;::::::::;:;:::::~::(::::.::::::::::.:((~~~~~(~?::
','.",".",".",".',".'.'.'.'.",".".".".',",".",',",'.','.'.'.'.'
.."............' ............... . ",..
......... ............ .....,.."", """"""..,......""""""" ..."........, ...."............ .........., ,,",""""" """""",..,..,,,,,..,,..
,', ,',',',',',',', ,',',',',',',',',',',',',', ,',',',',',', ,',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',', ,',',',',',',',',',',',',',',', ,',',',',',',',',',',',',',',',',',',',' ',',' ,',',',',',',', ',',',',',',',','..,',',',',',',',',',',',",',",',',',
"""",.""""""""""""", ".,..",."""""""..""""""""""" """'.',.....,.""""""""'.',,,,, .."""",.."..""""""",...,.",.""",
... i;:~@ij~r~#:Wij~ij9!::...... ;::M9ij{m,~Ni~ijf~E/r::::::::~!nt#:'m~pe~n~:~....:::::.:.::.. .::~Prf~i,ijij(~~f~iil~:::;:~;::::::::::
........:.... .. ..............................:::R~##t~bi::::: ....... ......... . .... ................... ..............:::.:::..............:::::
.. .
General Site
Characteristics
Risk is low to moderate
Anticipated land uses or
new structures are not
incompatible with natural
recovery
Natural recovery
processes have a
reasonable degree of
certainty to continue at
rates which will contain,
destroy, or reduce the
bioavailability or toxicity of
contaminants within an
acceptable time frame
Human and
Ecological
Environment
Expected human
exposure is low and/or
reasonably controlled by
institutional controls
Hydrodynamic
Conditions
Site includes sensitive,
unique environments that
could be irreversibly
damaged by capping or
dredging

Sediment bed is
reasonably stable and
likely to remain so
January 2005 Draft, Peer Review Document
Risk is moderate to high
Suitable types and
quantities of cap material
are readily available
Anticipated infrastructure
needs (e.g., piers, pilings,
buried cables) are
compatible with cap
Water depth is adequate
to accommodate cap with
anticipated uses (e.g.,
navigation, flood control)
Incidence of cap-
disrupting human
behavior, such as large
boat anchoring, is low or
controllable
Expected human
exposure is substantial
and not well-controlled by
institutional controls
Long-term risk reduction
oumeighs habitat
disruption, and/or habitat
improvements are
provided by the cap

Hydrodynamic conditions
(e.g., floods, ice scour)
are not likely to
compromise cap or can
be accommodated in
design
Rates of ground water
flow in cap area are low
and not likely to create
unacceptable contaminant
releases
Risk is high
Suitable disposal sites are
available and nearby
Suitable area is available for
staging and handling of
dredged material
Existing shoreline areas and
infrastructure (e.g., piers,
pilings, buried cables) can
accommodate dredging or
excavation needs
Navigational dredging is
scheduled or planned
Water depth is adequate to
accommodate dredge but not
so great as to be infeasible; or
excavation in the dry is
feasible
Maneuverability and access
not unduly impeded by piers,
pilings, or other structures

Expected human exposure is
substantial and not we 11-
controlled by institutional
controls
Long-term risk reduction of
sediment removal oumeighs
sediment disturbance and
habitat disruption
Water diversion is practical, or
current velocity is low or can
be minimized, to reduce
resuspension and downstream
transport during dredging
7-5
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Chapter 7: Remedv Selection Considerations
';::::::::::::::::::::::::::::::::::::::::':"',',',',-::::::::::::::::::::: ..;.;.;.;.;.:-:.:::.;.:.:.:.;::::.:::.:.;.:.:::::::::::::::'".'..'.,.,.',
:::9ijAr.~~Wrt~~9.~::. .... ...::MPH~~rl~!~~r~!::?
.,;-:,;"[[[' ... ...... ... .
............................................. ..........:R'f9¥,tWr..::...
Sediment
Characteristics
Sediment is resistant to
resuspension, e.g.,
cohesive or well-armored
sediment
Contaminant
Characteristics
Contaminant
concentrations in biota
and in the biologically
active zone of sediment
are moving towards risk-
based goals on their own
Contaminants already
readily biodegrade or
transform to lower toxicity
forms
Contaminant
concentrations are low
and cover diffuse areas
Contaminants have low
ability to bioaccumulate
...,",,'....................................
,',',',",',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',',
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
:::~?~!Imgiep,~~i:::
...................................... .........
...-...-.............................. .........
. . . . . . . . . . . , , ' ., . , , ' . , . , . , . , , , , , , , . , . , . , , " , , , , ,
""""""""",.,..".""".,.,..,..""""",.
:.:P!~~~!ijii-~##:!¥!!pij:
.. ,....
...., ,
""""""""""""""" "",.
,',',',',',',',',',',',',',',',',',',',',',',',',',',',', ,',',',',',',
, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
, , ' , ' , , , , , , ' , , ' , , ' , . , , . , , , ' , , ' , , " ,,',,','
,',',',',',',',',',',',',',',',',',',',',',',',',',',',',','.',',',',',',',',',',',',
, . . . , . , ' , , ' , , ' , , ' , , , , , , , , , , , , , , , , , , , , , , , , .
" "
,.. ........,....
. ..
""'"
......
Sediment has sufficient
strength to support cap
(e.g., has high density/low
water content)
Contaminated sediment is
underlain by clean sediment
(so that over-dredging is
feasible)
Sediment contains low
incidence of debris (e.g., logs,
boulders, scrap material) or is
amenable to effective debris
removal prior to dredging or
excavation
Contaminants have low
rates of flux through cap
High contaminant
concentrations cover discrete
areas
Contamination covers
contiguous areas (e.g., to
simplify capping)
Contaminants are highly
correlated with sediment grain
size (Le., to facilitate
separation and minimize
disposal costs)
Highlight 7-3 may assist project managers in evaluating cleanup options. For convenience these
comparisons are organized around the NCP's nine remedy selection criteria. This highlight is intended
only to identify some of the general differences between these three remedy types, not as an example of
an actual comparative alternatives analysis for a site. An actual site alternatives analysis would typically
include more complex alternatives and many site-specific details, as described in the ROD Guidance
(U.S. EP A 1999a) and EP A's Guidance for Conducting Remedial Investigations and Feasibility Studies
under CERCLA (U.S. EPA 1988a, commonly referred to as the "RIfFS Guidance"). The example
criterion components column used in Highlight 7-3 below are adapted from the RIfFS Guidance and are
intended only as examples of some of the components that may be considered when evaluating each
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Chanter 7: Remedv Selection Considerations
. . .'
;.:.;.;.;.:.:.;.:.:.:-:.:,;,;,:,:"...,,;.;.>:.;.;.:.:.;.:.;.:-:.;.:-:.;.;.:.:.;.:.;';';';':':';';':':';';':',..,';':';':';':-:',',...';'>;'>:':',.......:':';':':':':';';';';':':':',...'.':.:.:.:.;.;.:.;.:.;.;.:.;'......:-;':';';':';':';':';';';':';':'[[[-:.>;.:-:-:.;.:.;.;.;.;.:.;,.....,,;.:-:.:.;.:.:.;.:.;.:.;.;.;.;.;.;.;.>
""H' ''''''H''
".................
......,............. ',""" ....,,,,.,,,
. . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . .
..... ....... ...... ..... ......... ........"............... ...........,,"""''''
';.;.NC:P>:-:.. :-:.;.>;.:-:::...... ;:;:;:;:;:;:;:;:;:;:;':""'" ,.;.:-:.;.:-::;:::::::;:;""':.... :::.: ... """"""'........... ........:::: :.::::.:.:.:.:.:.;:~r:rrr:::::::::::':<';,;,>:: :::::::::::::::::::::::::::::::::::::::::::::

:llllil~~:.lill.,"""il.!I!!:..I~f~~I.I.......:.:.:.....:.:.:..'~ijijJ@i~ij..'~i~~~..::::,.,..,.',.,',.,.,.".,:,:,:,',.,.",.,',.", ,',,',',"... "'.'.'.'.'.'.:.:.:"'."'" : "".....:,:.:':.:,:.......:.....:.:..'[[[
:Pff.~rt~:.:.......::..'.P9ffip.M~~w.:.........R~9Py!6W......:.:..::.i~i-iiw..p~~~irtQ........:..,.:.Qi~~gi~9tg!~~Vi#i9#.......

Overall N/A Relies upon natural Relies upon adequate Relies upon effective
Protectlve- processes for cap placement and removal and low residual
ness protection maintenance for levels for protection
protection
'''H
n'"
..H'HH'
..'HH'
H"H'H
,.'HH
"HHHH
'H'HHH
May provide low level
of short-term
protection, but may
provide potentially
acceptable long-term
protection
Compliance
with
Applicable
or Relevant
and
Appropriate
Require-
ments
(ARARs)
N/A
Generally, only
che mica l-specific
ARARs apply (these
would also apply to
other approaches)
.
January 2005 Draft, Peer Review Document
. ...
.....HH
May provide moderate to
high level of protection,
depending upon areal
extent and design of cap
Generally, the Clean
Water Act (CWA) 9404
(regulates discharge of
dredged or fill materials
into waters of the U.S.)
and the Rivers and
Harbors Act (prohibits
obstruction or alteration
of a navigable waterway)
are ARARs
..."'HH
May provide moderate to
high level of protection,
depending on residual. May
not be as protective in the
short term as capping (due
to resuspension and
residuals) but may provide
high long-tenn protection in
areas with acceptable
residuals or in areas
favorable to additional
natural recovery
Generally, CWA 9404 and
the Rivers and Harbors Act
are ARARs. Generally,
treatment facilities and in-
water disposal sites should
meet substantive
requirements of the CWA
99404 and 401 for
discharge of effluents into
waters of the U.S.
See Chapter 3, Section Generally, RCRA is an
3.3 for additional example ARAR for disposal in solid
ARARs or hazardous waste landfills
For polychlorinated biphenyl
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Chaoter 7: Remedv Selection Considerations
Long-Term Magnitude of May provide low to high May provide moderate to May provide moderate to
Effectlve- Risk level of risk reduction high level of risk high level of risk reduction
ness and Reduction and and residual risk, reduction and low to and low to moderate
Permanence Residual Risks depending on moderate residual risk, residual risk, depending on
  processes being relied depending on cap design, effectiveness of dredging
  upon and site-specific placement, construction, and use of backfill material
  characteristics that and maintenance to 
  might prevent long- address site May provide low (upland) to
  term isolation or characteristics that might moderate (in-water) residual
  destruction of otherwise prevent long- risk for sediments and
  contaminants term isolation of treatment residuals
   contaminants contained at controlled
    disposal sites
 Adequacy and May provide low May provide moderate to May provide high control
 Reliability of control, but potentially high control, depending due to removal of
 Controls for acceptable, depending on cap stability and contaminants, if residual
 Residual Risk on processes being contaminant migration contamination is below
  relied upon and site- through cap cleanup levels
  specific conditions  
   May provide low to May provide high control if
  May provide moderate moderate ability to control residual risk from
  ability to control physical disturbance due contaminants remaining in
  physical disturbance to human and natural place is similar to MNR
  due to human activity forces through cap design 
  via institutional and moderate ability to May leave residual risks at
  controls; may provide control disruption through upland disposal sites that
  little ability to control institutional controls are easily controlled; at in-
  physical disturbance  water sites control can be
  due to natural forces May provide some ability more complex
   to control effects of 
  May provide no ability advective flow and 
  to control advection diffusion rates through 
  and diffusion of cap design 
  contaminants through  
  overlying cleaner  
  sediment, where this is  
  of concern  
 Need for Flve- Five-year reviews Five-year reviews Five-year review generally
 Year Reviews probably would be probably would be required for dredged site, at
  required for most sites required for most sites least until cleanup levels
  due to waste left in due to waste left in place and remedial action
  place and possible and possible continuing objectives are met and site
  continuing need for use need for use restrictions is available for unrestricted
  restrictions  use
    Reviews generally required
    for on-site disposal facilities
January 2005 Draft, Peer Review Document
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Chapter 7: Remedv Selection Considerations
.................. .".""""""" ......,..."",...
.. ...... '."""" ........ :':':':':':':';';':':';';':';';':':'. :':-:';':':':';';':':':':':';';':';', ":':':':':':':':':':':':';':':';':'.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
::ijg!p::!:::':::"""""""...,:,::::::: """" "'" ,"',""" ",",',' ,::::::,:,:',:::...::.::::::""""".""::':;.,..,..:....:.:,::<,:
:~~m!~Y\""",:,,:,:,,:,:,:,:,:,:,::,::::.:,:::.:,"::::,:::.:,.::~C',.,'..':'.'.:*,'.,',.:,:I~,',~,:,'.,m,'.,.,:.,:,'.,.,',.;p,':,.~.',:.I,:,..n',:,.,'.,.:,;::':,'.::,.:.,':,.:,.::':,;::.:,.::.:,:,':,.:,.::.,.,.,., """:::"""":::':':' ,", """""""'"",:::::;:/:\\",':'"" ":.:::::::::::)))f:',,
"Selection'" '~.. . ::M~~jJ~ttij..N.~w.t~{: ,',,", '::, " "'", ',:, "".. ',:.::.:.:.:'" '..,::':::::::::::,::::;;;;;;:'::;:::;;:((::;.::,
il~~~~~i~i;:iii!i!ij'::::::;'.;Y9ffiP'pijMft:/", ,RM9.y~5f:?" ':!!i~IW.:9#.ppj#!Ji .::::::.Pr~ij~:i.~qtg!~@V!19.ij.:::.:::.::,
Reduction of N/A No treatment is Typically, no treatment is Most often, no sediment
Toxicity,  involved involved treatment is involved.
Mobility, and    Sediment can be treated if
Volume   Research is ongoing cost-effective; stabilization
(TMV)   conceming the is most common form
Through   combination of innovative 
Treatment   in-situ treatment Potential exists for
   components within a cap beneficial reuse of dredged
    sediment
    Water treatment can reduce
    TMV of contaminants where
    significant quantities of
    toxies are removed from the
    water
Short-Term Envlron- No additional impact to May provide high impact May provide high impact to
Effectlve- mental bottom-dwelling to bottom habitat in area bottom habitat in dredged
ness Impacts ecological community of cap; potential for re- area; potential for re-
 During from the remedy itself colonization is site colonization generally good,
 Remedy  specific, Cap design can but site specific. Backfill
 Implemen- Impacts of facilitate re-colonization in design can facilitate re-
 tatlon contaminated sediment some cases colonization in some cases
  on environment  
  continue but should May provide low potential There could be moderate
  gradually decline until for impacts from releases potential for impacts to biota
  protection is achieved to the environment during from release during
   cap placement and initial dredging; releases partially
   consolidation controllable by physical
    barriers and by selection
    and operation of dredging
    equipment
January 2005 Draft, Peer Review Document
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Chaoter 7: Remedv Selection Considerations
Short-Term Community There should be no There should be low There should be low to
Effectlve- and Worker additional health potential for health moderate potential for
ness (cont.) Protection impacts to community impacts to community health impacts to
 During from the remedy itself; and workers from community and workers
 Remedy pre-existing impacts will contaminant releases from contaminant release
 Implementa- continue but should during cap placement; during dredging, staging,
 tlon gradually decline until engineering controls may transport, and disposal.
  protection is achieved minimize these releases; Engineering controls may
   worker protection minimize these releases;
  May provide moderate generally available worker protection generally
  ability to control  available
  community impacts Increased truck or rail 
  from fish/shellfish traffic for transport of cap Increased truck or rail traffic
  ingestion and, where material may impact for transport of dredged
  applicable, direct workers and the material may impact
  contact with community workers and the community
  contaminated  
  sediment, through Staging needs for cap Dredged materials and
  consumption advisories placement may disrupt water handling or treatment
  and use restrictions local community during needs may disrupt local
   placement community
  There should be  
  minimal impacts on  
  workers from  
  monitoring activities  
  There should be no  
  additional local   
  community disruption  
  beyond existing  
  condition  
 Time Until Generally, longest time Generally, shortest time Time to achieve protection
 Protection Is to achieve protection, to achieve protection varies significantly
 Achieved depending on rates of  depending on the size and
  natural processes and Complete biota recovery complexity of the project
  bioavailability of the could take several years 
  contaminants  Complete biota recovery
   Generally, most certainty could take several years
  Time to achieve concerning time to 
  protection is frequently achieve protection Time frame generally more
  highly uncertain  uncertain than for capping
    due to difficulty of predicting
    residual contamination
January 2005 Draft, Peer Review Document
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Chapter 7: Remedv Selection Considerations
.....
......... .....
.......... .....
'...."'" ..."" ...........
. . . . . . . . . . . . . . . . . . . . . . . . .
:.::.::.N.:'..'.(;.:.:.:p..'.::.'::.::.::.::::.::.::.::.::.::.::.::.::.::.: ....",'::.><.......:::, ....... ..............:.... ......... .:'::""..... """....... ....,," "'.'.'.'.'.'.'."...... "".:::::'::":......':::::
-"......................... ..
:~~ffl~~y:...:',.... ...:~*-~mp.!i??:b::::::.::::.:.:..::}........ ............. ........... ...... ":::::.::,.....""":::::::.,"""",....:::::::"
..$.!t~i#!Mi.:..:.. ..::9rl~rt~m:::..':.M9ij!@.t~~~w.t~..::....................'.'.'.'.'.'.'."",... ,,"'.'. ... '..::::. .. ."""" '::.:.:.:.:':....//./::::."".:::.
"'Bft~~rm..'."::::::::Y9mp.pMij~"'.$.M9.Vii.Y':>..::::.)#~jw..9#.ip!#~...::..:::.:..m~~ii.iji.t~~*#vi~9.~.::.:..
Implement-
ability
Technical
Feasibility
Generally, no
construction is required
Reliability can be
uncertain in some
environments due to
uncertain rates of
natural processes and
uncertainties
conceming sediment
stability
...,'..
Cap placement methods Dredging and excavation
are generally well- methods are generally well-
established; ability to established; technical
construct a cap depends feasibility of dredging
on a number of factors depends mainly on
including, mainly on water accessibility, extent of
depth and currents, slope debris and obstructions,
and geotechnical stability and the ability to over-
of underlying materials, dredge
and stability of the cap
itself during and after
construction
Disposal in upland landfills
is a well-established
technique; in-water disposal
methods are less well-
established and may require
greater monitoring;
technical feasibility
generally depends on
distance to the disposal
Relatively easy to repair site, ease of dewatering,
cap in case of localized and slope and geotechnical
erosion or disruption, but stability of disposal site
can be difficult or costly to
implement sediment
removal if cap is not
effective
Where site-specific
conditions allow, should Reliability generally high,
be relatively easy to depending on site-
implement a different specific conditions, and
remedy if MNR is not degree of monitoring and
effective maintenance
Methods for monitoring
sediment cleanup
levels are relatively well
established
January 2005 Draft, Peer Review Document
Methods for monitoring
cap integrity and
contaminant migration
within cap are relatively
well established
Reliability should be higher
for excavation than
dredging; reliability of
dredging depends on site-
specific conditions and skill
of equipment operators
Transport of sediment to
disposal site may present
cosUy technical and/or
public policy challenges
Where site-specific
conditions allow, should be
relatively easy to re-dredge,
cap or implement MNR if
remedy is not effective, but
cost consequences can be
high
Monitoring methods for
sediment cleanup levels
and short-term releases
from dredging are relatively
well established
7-11
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Ch(llJter 7: Remedv Selection Considerations
Implement-
ability
(cont)
Administra-
tive Feasibility
Availability of
Services,
Materials,
Capacities,
and
Equipment
State-regulated Containment in public
institutional controls, INaters can require long-
including fish term coordination with
'consumption advisories state and local regulators
where contaminants due to potential need for
are bioaccumulative, long-term controls on
are frequently needed INaterway use
for a longer period than
for other remedies
Monitoring and
analytical services are
generally readily
available
January 2005 Draft, Peer Review Document
Where contaminants are
bioaccumulative, fish
consumption advisories
frequently needed for a
period of years to
decades. Length of time
generally depends on
residual contamination
outside of capped area
Location and suitability of
capping material source
is critical and can be
problematic if not
available locally
Specialized cap
placement equipment
may be needed in some
environments, but are
generally available
Availability of suitable cap
material staging areas is
critical and can be
problematic for some
sites (e.g., some urban
areas)
Dredging and excavation
plan should be coordinated
with other agencies to
ensure compatibility with
other waterway uses and
habitat concerns during the
removal operation
Fish consumption
advisories frequently
needed for a period of years
to decades, where
contaminants are
bioaccumulative. Length of
time generally depends on
residual contamination
within and outside of
dredged area
Disposal siting often
requires intensive
coordination with several
government agencies and
the public
Environmental dredging and
excavation equipment is
generally available,
although availability may be
a problem for large projects.
Specialized equipment may
need to be constructed for
special situations
Availability of suitable
dredged material staging,
separation, and, where
required, INater treatment
capacity is critical and can
be problematic for some
sites (e.g., some urban
areas)
Availability of a suitable
disposal facility with
adequate capacity is critical
and can be problematic for
some sites (e.g., where
local disposal is infeasible
or high volumes are
involved)
7-12
-------
Chapter 7: Remedv Selection Considerations
.....
......
...........,..,...
.................
.................
..,.........,.,..
... ......." .............. ..... ....... ",',',','............................ ...
.,.,.NCp. "':..-. ""':.:.:,:,:,',',',', ... ,',",',',',',' ....... ............. ...... t~?rrrrf~{(t:~~trrr ..:.:<.:.;.;:.:.:.:>;.;.;.;.;.;.~.;.;.;.;.;.:::...... :::::::::::::::::
::iR.ffli~~:::,:}" ',',':,::,,::,::,,:':,'::':,::":::':.:,:,'.:::,.:'.:,'~,:,.,'.,".,::~r',,:,,:,.!'~,::~,','"ffl,',.,'.,:r',::':1,P,':,'O'.,',',:,..n&,',',.,':'.:,.:,'.:,":,'::,::,::,::::", ::,:: ,:...:.::::" ,:.:::::::.:: "'" """,""""""':""""":: ::::{:}:::::::::::::::::, ,,:.::::.:::::::::....:.rr:::???
:::$.:i!.J~gl.m.1:::' '::" "'" ~ ~..::::M9.ij!W.r!i:N~~rl.ij.::."",::::::::::::::::""""""""",,::, ',',',',' "" ' ,,<:<"'<:':::::::r:f::::f::::::::.:fffff
dn~*-~di.HH.:.::.:::P~mp.po~o#:::::::r....::.R~~9.V~rY::::::::.:::::!rtmiW.:'9~ijijirtij.:........:..Pr~~~.i.~it~~9!Vij9~::@:.
Cost
N/A
Generally, no capital
cost
Long-term monitoring
costs typically continue
until cleanup levels and
remedial action
objectives are met.
Length of long-term
monitoring is generally
dependent on
assurance of sediment
stability
January 2005 Draft, Peer Review Document
Capital costs generally
higher than MNR and
lower than dredgingl
excavation
Long-term maintenance
and monitoring costs
generally higher than
MNR and dredgingl
excavation
Capital costs generally
higher than MNR or capping
and more difficult to
estimate accurately
Long-term monitoring costs
generally lower than MNR
and capping
Long-term monitoring costs
typically continue until
Long-term monitoring cleanup levels and remedial
costs typically continue action objectives are met
until cleanup levels and Length of long-term O&M
remedial action objectives period dependent on extent
are met Length of long- of residual contamination
term operation and and use of on-site disposal
maintenance (O&M)
period dependent on time
necessary to verify long-
term stability of cap and
lack of significant
contaminant fluxes
through cap
7-13
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Chapter 7: Remedv Selection Considerations
State
Acceptance
and
Community
Acceptance
Commonly identified
benefits include lack of
disruption to local
residents, lack of
disruption to aquatic
and terrestrial animal
and plant life, and low
cost
Commonly identified
benefits include use of an
active remedy with no
disposal issues, generally
moderate cost, and
potentially faster biota
recovery than MNR or
dredging due to rapid
placement of exposure
barrier
N/A
(2
Commonly identified
concems include
objections to a "do Commonly identified
nothing" remedy, concems include leaving
leaving contamination contamination in place,
in place, possible temporary disruption to
spread of contaminants local residents and
during flooding or other businesses, increased
disruption; truck, rail or barge traffic
uncertainties of during capping;
predicting rates of temporarily reduced
natural burial; and a recreational access;
potentially lengthy potentially long-term
period of fish reduction of navigational
consumption advisories waterway access;
reduced access to buried
utilities, possible long-
term anchoring or other
waterway use restrictions,
and costs to potentially
responsible parties
(PRPs) and/or state
during O&M
7.3
COMPARING NET RISK REDUCTION
Commonly identified
benefits include removing
contaminants from
waterway, possible
treatment of contaminants,
faster biota recovery than
MNR, increased/restored
navigational depth,
decreased flooding, and
lack of use limitations after
completion
Commonly identified
concerns include temporary
disruption to local residents
and businesses,
contaminant releases
during dredging, temporary
reduction of recreational
and navigational waterway
access during dredging;
siting of and risks from local
disposal facilities; increased
truck, rail, or barge traffic
during dredging, and a
period of fish consumption
advisories, generally longer
than for capping but shorter
than for MNR
Each approach to managing contaminated sediment has its own potential uncertainties and
relative risks. The concept of comparative net risk reduction was discussed by the National Academy of
Sciences Committee of the NRC as a method to ensure that all positive and negative aspects of each
sediment management approach were appropriately considered at contaminated sediment sites. The
Committee states that (NRC 2001):
All remediation technologies have advantages and disadvantages when applied at a
particular site, and it is critical to the risk management that these be identified
individually and as completely as possible for each site. For example, managing risks
from contaminated sediment in the aqueous environment might result in the creation of
additional risks in both aquatic and terrestrial environments... Removal of contaminated
materials can adversely impact existing ecosystems and can remobilize contaminants,
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Chanter 7: Remedv Selection Considerations
resulting in additional risks to humans and the environment. Thus, management
decisions at a contaminated sediment site should be based on the relative risks of each
alternative management action... For a site, it is important to consider "overall" or "net"
risk in addition to specific risks.
Project managers are encouraged to use the concept of comparing net risk reduction between
alternatives \s part of their decision-making process for contaminated sediment sites, within the overall
framework of the N CP remedy selection criteria. Consideration should be given not only to risk
reduction associated with reduced human and ecological exposure to contaminants, but also to risks
introduced by implementing the alternatives. The magnitude of risk associated with each alternative
generally is extremely site-specific, as is the time frame over which implementation risks may apply to
the site. Evaluation of both implementation risk and residual risk are existing important parts of the NCP
remedy selection process. By evaluating these two concepts in tandem, additional information may be
gained for remedy selection. Highlight 7-4 provides examples of factors that should be evaluated by
project managers in this comparative evaluation.
P'
.. ....... :.....H!~.~.i.~~ij~.!l~~..!~~I#~~...F~i~~~.!f~t'~9:~#~rl,i,V!.!I~~!Mi1il...~tNi~B~~~..!I"#M~~!~ij........:...'.,.'...:.....'.....:....'.'.

Factors Potentially Reducing Risk
....
.......
.
Reduced exposure to bioavailablelbioaccessible contaminants
.
Removal of bioavailable/bioaccessible contaminants
.
Removal or containment of buried contaminants that are likely to become bioaccessible
Factors Potentially Continuing or Increasing Risk
For MNR:
.
Continued exposure to contaminants already at sediment surface and in food chain
Potential for undesirable changes in the site's natural processes (e.g., lower sedimentation rate)
Potential for contaminant exposure due to erosion or human disturbance
.
.
For In-Situ Capping:
.
Contaminant releases during capping
Continued exposure to contaminants currently in the food chain
Other community impacts (e.g., accidents, noise, residential or commercial disruption)
Worker risk during transport of cap materials and cap placement
Releases from contaminants remaining outside of capped area
Disruption of benthic community
.
.
.
.
.
For Dredging or Excavation:
.
Contaminant releases during sediment removal, transport, or disposal
Continued exposure to contaminants currently in the food chain
Other community impacts (e.g., accidents, noise, residential or commercial disruption)
Worker risk during sediment removal and handling
Residual contamination following sediment removal
Releases from contaminants remaining outside dredged/excavated area
Disruption of benthic community
.
.
.
.
.
.
January 2005 Draft, Peer Review Document
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Chapter 7: Remedv Selection Considerations
7.4
CONSIDERING INSTITUTIONAL CONTROLS
Institutional controls (lCs) such as fish consumption advisories, fishing bans, ship
draft/anchoring/wake controls, or structural maintenance agreements for dams or breakwaters are
common parts of sediment remedies (see Chapter 3, Section 3.6, Institutional Controls). 40 CFR
~300.430(a)(1)(iii)(D) contains the following general EP A expectations with respect to ICs. These
expectations generally apply to all Superfund sites, including sediment sites: .
EP A expects to use institutional controls such as water use and deed restrictions
to supplement engineering controls as appropriate for short- and long-term
management to prevent or limit exposure to hazardous substances, pollutants, or
contaminants;
Institutional controls may be used during the conduct of the RI/FS and
implementation of the remedial action and, where necessary, as a component of
the completed remedy; and
The use of institutional controls shall not be substituted for active response
measures (e.g., treatment and/or containment of source material, restoration of
ground waters to their beneficial uses) as the sole remedy unless such active
measures are determined not to be practicable, based on the balancing of trade-
offs among alternatives that is conducted during the selection of remedy.
EP A policies concerning ICs are explained in Institutional Controls: A Site Manager's Guide to
IdentifYing, Evaluating, and Selecting Institutional Controls at Superfund andRCRA Corrective Action
Cleanups (U.S. EPA 2000e). In addition to considering the NCP expectations concerning ICs, the project
manager should determine what entities possess the legal authority, capability and willingness to
implement, and where applicable, monitor, enforce, and report on the status of the IC. An evaluation
should also be made of the durability and effectiveness of any proposed IC. The objectives of any ICs
contained in the selected alternative should be clearly stated in the ROD or other decision document
together with any relevant performance standards. While the specific IC mechanism need not be
identified, the types of ICs envisioned should be discussed in sufficient detail to support a conclusion that
effective implementation of the ICs can reasonably be expected. For some federal facilities in the
CERCLA program, the IC implementation details (i.e., the specific IC mechanism) should be placed in
the ROD. The program manager should refer to EPA's Guidance on the Resolution of the Post-ROD
Dispute (U.S. EPA 2003d) for guidelines describing and documenting ICs in Federal Facility RODs,
Remedial Designs, Remedial Action Workplans, and Federal Facility Agreements/Interagency
Agreements.
Reliability and effectiveness of I Cs are of particular concern with sediment alternatives, whether
they are used alone or in combination with MNR, in-situ capping, or sediment removal. Project managers
should recognize that ICs generally cannot protect ecological receptors, or prevent disruption of an in-situ
cap by bottom-dwelling organisms. In addition, in many cases ICs have been only partially effective in
modifying human behavior, especially in the case of voluntary or advisory controls. Although fish
consumption advisories can be an important component of a sediment remedy, it should be recognized
that they are unlikely to be entirely effective in eliminating exposures. Where advisories or bans are
January 2005 Draft, Peer Review Document
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ChUDter 7: Remedv Selection Considerations
relied upon to reduce human health risk for long periods, public education, and where applicable,
enforcement by the appropriate agency, are critical. This point is emphasized in Principle 9 of EPA's risk
management principles for sediment: "Maximize the effectiveness of institutional controls and recognize
theirlimitations" (U.S. EPA 2002a, see Appendix A).
Implementing and overseeing ICs can often be more difficult at sediment sites where control of
the water body may involve multiple entities and a single landowner is not present to provide oversight
and enforcement. As for other types of sites, at sediment sites, project managers should review ICs
during the five-year review. Where a water body is owned or controlled by local, state, or federal
government entities, their regulations and guidance should be consulted to determine what governmental
controls can be used to restrict the use of the water body, and the regulatory or administrative process to
enforce such a restriction. In complex situations it may be useful to layer a number of different ICs as
discussed in Institutional Controls: A Site Manager's Guide to IdentifYing, Evaluating, and Selecting
Institutional Controls at Superfund and RCRA Corrective Action Cleanups (U.S. EP A 2000e). Additional
guidance on other aspects of ICs is under development by EP A.
7.5
CONSIDERING NO-ACTION
The ROD Guidance, Section 8.1, indicates that a no-action remedy may be appropriate in the
following situations:
.
When the site or operable unit poses no current or potential threat to human health or the
environment;
.
When CERCLA does not provide the authority to take remedial action; or
When a previous response(s) has eliminated the need for further remedial response [often
called a "no further-action" alternative].
Generally, if ICs are necessary to control risks caused by a contaminant of concern at a site, a no-
action remedy is not appropriate. For example, if fish consumption advisories or fishing bans are
necessary to control risks from contaminants of concern at a site, a no-action remedy for sediment is not
appropriate, even if the advisories or bans are already in place. Instead, a remedy should be considered
that includes at least the institutional control (e.g., advisories or bans), and, if appropriate, other actions
for sediment or other media.
A no-action ROD however may include monitoring. For example, sediment may pose no current
or potential threat to human health or the environment; however, uncertainties concerning that evaluation
may make it wise to continue some level of monitoring. In this case, a no-action ROD that includes
monitoring may be an appropriate remedy. It is important to note that this is different from an MNR
remedy where current or expected future risk is unacceptable and natural processes are being relied upon
to reduce that risk to an acceptable level within a reasonable time frame. Although a no-action remedy
may require long-term monitoring, an MNR remedy generally needs more intensive monitoring to show
that contaminant concentrations are being reduced by anticipated mechanisms at the predicted rates.
January 2005 Draft, Peer Review Document
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Chaoter 7: Remedv Selection Considerations
7.6
CONCLUSIONS
The focus of remedy selection should be on selecting the alternative which represents the best
overall risk reduction strategy for the site according to the NCP nine remedy selection criteria. As
discussed in the OSWER Directive 9285.6-08 Principles for Managing Contaminated Sediment Risks at
Hazardous Waste Sites (U.S. EPA 2002a), EPA's policy has been and continues to be that there is no
presumptive remedy for any contaminated sediment site, regardless of the contaminant or level of risk.
Generally, as discussed in Chapter 3, Feasibility Study Considerations, project managers should evaluate
each of the three major remedies (i.e., MNR, in-situ capping, and removal through dredging or
excavation) at every sediment site at which they might be appropriate.
Controlling any continuing sources of contaminants is an important factor for any sediment
remedy (U.S. EPA 2002a). Where source control is uncertain, cannot be achieved, or is outside the scope
of the remedial action, project managers should consider the potential for re-contamination and factor that
potential into the remedy selection process and into the long-term monitoring plan for the site. However,
project managers should note that delaying an action to complete source control may not always be wise.
Early actions in some areas may be appropriate as part of a phased approach to address site-wide
contamination even if sources are not fully controlled initially; in such situations, careful consideration
should be given as to whether the uncontrolled sources will cause the early action to be ineffective.
At many sites, but especially at large sites, the project manager should consider a combination of
sediment approaches as the most effective way to manage the risk. This is because the characteristics of
the contaminated sediment and the settings in which it exists are not usually homogeneous throughout a
water body (NRC 2001). As discussed in the remedy-specific chapters of this guidance, when evaluating
alternatives, project managers should include realistic assumptions concerning residuals and contaminant
releases from in-situ and ex-situ remedies, the potential effects of those residuals and releases, and the
length of time a risk may persist. In addition to considering the impacts of each alternative on human
health and ecological risks, the project manager should assess the societal and cultural impacts of each
alternative on the community and the opportunities for site reuse and redevelopment.
The project manager should include a scientific analysis of sediment stability in the remedy
selection process for all sites where sediment erosion or contaminant transport is a potential concern.
Typically, it is not sufficient to assume that a site as a whole is depositional or erosional. Generally, as
discussed in Chapter 2, Remedial Investigation Considerations, project managers should make use of
available empirical methods for evaluating sediment stability, especially when there are significant
differences between alternatives. At large or complex sites, and sites with limited historical data, project
managers may also consider using a numerical model for evaluating events for which no field records are
available and for predicting future stability.
The project manager should include in the remedy selection process a clear analysis of the
uncertainties involved, including uncertainties concerning the predicted effectiveness of various
alternatives and the time frames for achieving cleanup levels and remedial action objectives. Project
managers should quantify, as far as possible, the uncertainty of important factors in the remedy decision.
Where it is not possible to quantify uncertainty, the project manager should use a sensitivity analysis to
determine which apparent differences between alternatives are most likely to be significant.
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Chaoter 7: Remedv Selection Considerations
The project manager should monitor all sediment remedies during and after implementation to
determine if the actions are effective and if all cleanup levels and remedial action objectives are met.
Sediment remedies should not only include monitoring of surficial sediment immediately following
implementation of the action, but also should include long-term monitoring of sediment to assess changes
in residual contamination and possible re-contamination, and monitoring of fish or other relevant biota
recovery data. Without these data, an assessment of the long-term effectiveness of the remedy is difficult
and five-year reviews may be difficult to perform acurately. Additional monitoring data may help not
only to assess the site, but to help build a body of knowledge that will decrease uncertainties in decision-
making at future sites. Chapter 8, Remedial Action and Long-Term Monitoring, discusses these and other
general monitoring considerations for contaminated sediment sites.
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Chapter 8: Remedial Action and LonK-TermMonitor;nK
8.0
REMEDIAL ACTION AND LONG-TERM MONITORING
This chapter provides a recommended approach to developing an effective monitoring plan at
contaminated sediment sites. A monitoring plan is recommended for all types of sediment remedies, both
during and after remedial action in order to evaluate how effective the remedy is in meeting the clean-up
levels for the site and the remedial action objectives (RAOs). Monitoring data are also needed to
complete the five-year review process at sites where they are required.
For Fund-lead sites that are subject to a state cost share, it may be necessary to distinguish
monitoring that is part of the remedial action phase of a remedy from monitoring that is associated with
the operation and maintenance (O&M) phase of the remedy. Distinguishing these two is a site-specific
decision. Project managers may fmd it useful to refer to Chapter 3, Section 3.5.2, Operation and
Maintenance Costs for suggestions about what types of activities are frequently associated with long-term
O&M as distinguished from similar activities that are typically conducted during the remedial action
itself.
This chapter is based on a lot of the information in the framework presented in EP A's new
"Monitoring Guidance," Office of Solid Waste and Emergency Response (OSWER) Directive 9355.4-28
Guidance for Monitoring at Hazardous Waste Sites: Framework for Monitoring Plan Development and
Implementation (U.S. EPA 2004e). Project managers are encouraged to consult the Monitoring Guidance
for more detailed information about the monitoring framework and how it incorporates EP A's Data
Quality Objective (DQO) process. This chapter presents more specific guidance for monitoring of
sediment sites; however, many technical details are outside the scope of this chapter. More specific
guidance on particular monitoring topics is under development by EP A to assist project managers.
8.1
INTRODUCTION
As described in EPA's Monitoring Guidance (U.S. EPA 2004e), monitoring may be viewed as
"the collection and analysis of repeated observations or measurements to evaluate changes in condition
and progress toward meeting a management objective." Monitoring should include the collection of field
data (Le., chemical, physical, and/or biological) over a sufficient period of time and frequency to
determine the status at a particular point in time and/or trend over a period of time in a particular
environmental parameter or characteristic, relative to clearly defmed management objectives. The data,
methods, and endpoints should be directly related to the RAOs and clean-up levels or goals for the site.
Environmental sampling and analysis is typically conducted during all phases of the Superfund
process to address various questions. By the time a project manager is implementing a remedial action or
writing a monitoring plan, a considerable amount of baseline site data should have been collected during
the remedial investigation or site characterization phase. In the site characterization phase, sampling is
performed to determine the nature and extent of contamination, to develop the information necessary to
assess risks to human health and the environment, and to assess the feasibility of remedial alternatives.
During site characterization, the project manager should anticipate expected post-remedy monitoring
needs in order to ensure that adequate baseline data are collected to allow comparisons to future data sets.
It is important to note that data colfection is a dynamic and iterative process.
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Chapter 8: Remedial Action and Long- Term Monitoring
,
Project managers should ensure that agreements with contractors or responsible parties
concerning remedial design and remedial action include requirements for development of an appropriate
monitoring plan. The need for environmental monitoring and how the data will be used to measure
performance against clean-up levels and RAOs should be discussed early in the remedial design process.
Where institutional controls are part of the remedy, this discussion should also include implementation
and, where appropriate, monitoring plans for those controls. Having an early discussion of the
monitoring needs as they relate to any engineering performance standards for the particular remedies
should allow the project manager sufficient time to resolve logistical or other implementation issues long
before the monitoring program is put in place. This discussion during remedial design is also important
to determine whether sufficient baseline data have been collected so that both the remedial action and
long-term monitoring data can be easily compared to pre-remedy conditions.
At sediment sites, it is also frequently necessary to continue collecting background data from
upstream or other reference areas away from the direct influence of the site. This can be especially
important where there are uncertainties or potentially changing conditions in background areas, for
example, where upstream urban storm water runoff or other possible continuing sources of contamination
could impact a remedy.
During the remedial design phase, it is also important to develop a clear understanding of how the
monitoring data will be used in the post-remediation decision process, and to ensure that reviews of the
monitoring results are conducted in a timely fashion so additional actions can be taken when necessary.
In this way, the monitoring data should become a key element of the decision process both in terms of
whether the clean-up levels and RAOs are being met and whether additional management actions are
warranted.
Although sediment sites vary widely in size and complexity, monitoring typically requires a
higher degree of planning at sediment sites than some other types of sites for the following reasons:
.
Sediment sites often involve more than one affected medium (e.g., sediment, surface
water, biota, and floodplain soils) and multiple contaminants of concern;
Contaminants at sediment sites are often from a variety of sources, some of which may be
outside of the site in question;
.
Sediment sites may require monitoring over large areas and in a variety of physical and
ecological settings;
The spatial and temporal variabilities of aquatic sediment and biota can be great; and
.
For sites with bioaccumulative contaminants, the relationship between contaminant levels
in sediment and biota is frequently complex.
An especially important issue for project managers at large sites is the need to monitor both the
effectiveness of individual sediment actions and the ability of achieving overall site RAOs. Frequently,
the monitoring parameters at large sites are different. For example, where contaminants from multiple
sources are indistinguishable, it may be necessary to find unique parameters for monitoring effectiveness
of individual actions. However, it also may be very important to monitor parameters that may be
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Chapter 8: Remedial Action and Long-Term Monitoring 
responding to multiple sources or areas of a site, such as some fish species. Key steps for developing and
implementing a monitoring plan for sediment sites and some potential monitoring techniques and
approaches for sediment remedies are discussed in the remainder of this chapter.
Highlight 8-1 lists some key questions that should be answered before developing a monitoring
plan.
...
.. .....
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.::.:.ft,~~!~~tl~it1.ffi::~lyI9!!'!99~:!9r;nY'!9nm~9~!.:M9n~m!!~Q.::::,::':'r::::):::;:;::'::\::..'.:::::'::...
.....
..
............
.....,
What is the purpose of the monitoring?
Are detection limits adequate to meet the purpose of the monitoring?
Are there likely to be other factors, such as non site-related releases, beside the cleanup that will influence the
monitoring results, and are these well understood?
How often should monitoring take place, and how long should it continue?
Can the monitoring results be readily placed into searchable, electronic databases and made available to the
project team and others?
Is it clear who is responsible for reviewing the monitoring data and what the triggers are for identifying important
trends (positive or negative) in the results?
What are the most appropriate methods for analyzing the monitoring data? Should these be based on statistical
tests or other quantitative analysis? Will there be sufficient data to support these statistical measures?

Is there agreement on what actions will be taken should the monitoring data indicate the following: 1) the site
appears to be improving and the RAOs are likely to be met; or 2) the site does not appear to be improving and
the RAOs are not likely to be met?
How will the results be communicated to the public, and who is responsible for doing this?
8.2
SIX RECOMMENDED STEPS FOR SITE MONITORING
Monitoring is conducted at contaminated sediment sites for a variety of reasons, but primary
among them are the following: 1) to assess compliance with design and performance standards (e.g.,
monitoring sediment resuspension or contaminant release during dredging, measuring cap thickness
during and after cap placement); 2) to assess short-term remedy performance and effectiveness in meeting
sediment cleanup levels; and/or 3) to evaluate long-term remedy effectiveness in achieving remedial
action objectives and in reducing human health and/or environmental risk.
When developing a monitoring plan, it is important to review the record of decision (ROD) and
all supporting documents for the site. The ROD generally should contain numerical cleanup levels and/or
action levels for sediment and sometimes for other media, and narrative RAOs that relate more directly to
reducing risk. These form the basis of the monitoring plan. RODs or other site documents may also
contain specific performance criteria or objectives for the short-term and long-term performance of the
remedy that should be incorporated into the monitoring plan.
EPA's Monitoring Guidance (U.S. EPA 2004e) describes certain key steps that are recommended
in developing and implementing a monitoring plan. These steps are listed in Highlight 8-2 and explained
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Chapter 8: Re11ll!dial Action and LonK- Term MonitorinK
briefly along with sediment site examples in the following text. This guidance was developed for use at
all hazardous waste sites, not just Superfund sites, and therefore, uses the tenn "site activity" to apply to
implementation of removal actions, remedial actions, institutional controls, or habitat mitigation.
..... .. ....... ........ ....... ....... ..
Step 1. Identify Monitoring Plan Objectives
Evaluate the site activity
- Identify the activity objectives
- Identify the activity endpoints
- Identify the activity mode of action
Identify monitoring objectives
Obtain stakeholder input

Step 2. Develop Monitoring Plan Hypotheses
.
.
.
.
Develop monitoring conceptual models
Develop monitoring hypotheses and questions
.
Step 3. Formulate Monitoring Decision Rules
Step 4. Design the Monitoring Plan
Identify data needs
Determine monitoring plan boundaries
Identify data collection methods
Identify data analysis methods
Finalize the decision rules
Prepare monitoring quality assurance project plans (QAPPs)

Step 5. Conduct Monitoring Analyses and Characterize Results
.
.
.
.
.
.
.
Conduct data collection and analysis
Evaluate results per the monitoring DQOs (developed in Steps 1-4) and revise data collection and
analysis as necessary
Characterize analytical results and evaluate relative to the decision rules
.
.
Step 6. Establish the Management Decision
.
Monitoring results support the decision rule for site activity success
- Conclude the site activity and monitoring
Monitoring results do not support the decision rule for site activity success but are trending toward
support
- Continue the site activity and monitoring
Monitoring results do not support the decision rule and are not trending toward support
- Conduct causative factor and uncertainty analysis
- Revise site activity and/or monitoring plan and implement
.
.
Source: u.S. EPA 2004e
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Chapter 8: Remedial Action and Long-Term Monitoring 
SteD 1. Identify Monitoring Plan Objectives
Generally, the most important element in developing an effective monitoring plan is for the
project manager to identify clear and specific monitoring objectives. Identifying appropriate monitoring
objectives includes examining the intended outcomes of the action and the methods used to achieve that
outcome at the site. Inadequate or vague monitoring objectives can lead to uncertainty about why the
monitoring is being conducted and how the data will be used. Furthermore, funding for monitoring is
often limited. Specifying objectives helps to focus the experimental design and ensure that the most
useful information is collected. When identifying monitoring objectives other than those already
established in decision or enforcement documents, the project manager should involve participants from
all concerned stakeholders [e.g., public, natural resource trustees, state agencies, potentially responsible
parties (pRP)].
In general, physical and chemical objectives or endpoints are less costly and more easily
measured and interpreted than biological objectives or endpoints, and therefore may be more appropriate
where quick decisions are needed. However, the ability of physical and chemical endpoints to quantify
changes in ecological risk may be less direct than biological measurements, for example where risk is due
to direct contact with multiple contaminants. In this case, toxicity tests or bioassessments may provide an
integrated measurement of the cumulative effects of all contaminants and, therefore, can be a better
assessment of ecological risks in some situations. Conversely, where the primary risk is due to humans
and wildlife eating fish, chemical endpoints in fish may be most appropriate.
When identifying appropriate endpoints, it is important for the project manager to ensure that the
measure employed matches the time frame established for the criteria. For example, acute toxicity tests
quantify short-term effects on an organism; therefore, this type of test may be appropriate for operational
monitoring (e.g., monitoring during remedial dredging), where it can be performed in a short period of
time. Other biological endpoints, such as changes in community species diversity, typically occur over
long periods of time and may be more appropriate for use in a long-term monitoring program designed to
look at ecological recovery. Although no single endpoint can quantify all possible risks, a combination of
physical, chemical, and biological endpoints usually provides the best overall approach for measuring risk
reduction.
Example: In the ROD, EPA established a remedial action objective of reducing
polychlorinated biphenyl (PCB) concentrations in fish tissue to levels that would
eliminate the need for a fish consumption advisory for PCBs (for this site, 0.05 ppm). To
achieve this objective, EP A selected a cleanup level of 0.5 ppm total PCBs in sediment.
The short-term objective of the monitoring program is to monitor PCB concentrations in
sediment until the cleanup level is met and the long-term objective of the monitoring
program is to monitor PCB concentrations in fish tissue until the remedial action
objective is met.
SteD 2. DeveloD Monitoring Plan Hvpotheses
Typically, monitoring hypotheses represent statements and/or questions about the relationship
between a site activity, such as sediment remediation and one or more expected outcomes (U.S. EPA
2004e). The development of the monitoring hypotheses is analogous to the problem formulation step
(Step 1) of the DQO process (U.S. EPA 2000a). The monitoring hypothesis may be generally stated as
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Chapter 8: RemedialAction and Lonl(-TermMonitorinl(
"The site activity has been successful in reaching its stated goals and objectives," or in question fonn, as
"Has the site activity reached its stated goals and objectives"?
Example: Has the PCB concentration in sediment reached the cleanup level of 0.5 ppm?
Has the PCB concentration in fish tissue reached the remedial goal of 0.05 ppm?
SteD 3. Formulate Monitoring Decision Rules
Once monitoring objectives and hypotheses are agreed upon and stated explicitly, the next step
should be to identify specific decision rules that will be used to assess whether the objectives are met. A
decision rule nonnally is an "if... then..." statement that defmes the conditions that would cause the
decision maker to choose an action. In a monitoring plan, the decision rules should establish criteria for
continuing, stopping, or modifying the monitoring or for taking an additional response action. Four main
elements of a decision rule usually are: I )the parameter of interest; 2)the expected outcome of the
remedial action; 3)an action level, the basis on which a monitoring decision will be made; and 4)
alternative actions, the monitoring decision choices for the specified action (U.S. EPA 2004e).
Another factor the project manager should consider when developing decision rules is the time
frame under which they will operate. For example, when dredging highly contaminated sediment, a real-
time monitoring program could be established to analyze water samples before proceeding with the next
day's dredging. In contrast, the time frame required to assess a long-tenn monitoring objective (e.g., to
lower fish tissue concentrations) would be longer. In either case, the time frame should be explicitly
stated and understood by all the participants.
Examples: A decision rule could be established to require certain actions if suspended
sediment or contaminant concentration in the surface water due to releases from dredging
exceed certain criteria. A decision rule could be established to assess whether the
sediment cleanup level of 0.5 ppm PCBs has been reached, defmed as an average of 0.5
ppm PCBs in each often grids over the. A decision rule could be established to assess
whether progress is being made toward the remedial action objective of reduced PCB
concentrations in fish tissue by establishing an interim goal of achieving two ppm in fish
tissue within five years, after which monitoring frequency will be revisited. PCB
concentrations in fish species "A" will be measured on a specific frequency (e.g.,
annually) that is commensurate with the relevant species' uptake and depuration rates.
SteD 4. Design the Monitoring Plan
The fourth recommended step for the project manager is to identify the monitoring design for
collecting the necessary data. Design considerations include identifying data needs; determining
monitoring boundaries (frequency, location, duration); identifying data collection methods; and
identifying data analysis methods, including uncertainty analysis. EP A requires that a systematic
planning approach be used to develop acceptance or perfonnance criteria for all environmental data
collection and use. The Agency's DQO process is a planning approach normally appropriate for sediment
sites (U.S. EP A 2000a). Quality assurance project plans (QAPPs) or their equivalent are also needed for
environmental data collection and use.
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The spatial and temporal aspects of a monitoring plan typically defme where and when to collect
samples. In general, sampling locations should be based on the areal extent and magnitude of the
contaminated sediment and the propensity for the contaminants to move, either through transport (e.g.,
remediation, natural events) or through the food chain. Generally, the more dynamic the conditions, the
more frequently sampling is necessary to accurately represent conditions. However, a less costly
alternative can be to use data endpoints which respond to cumulative, longer-term conditions, where
appropriate.
Selecting a statistical approach to use in evaluating the data is another important aspect of the
monitoring program design. Data are sometimes collected in a manner that is incompatible with or
insufficient for the statistical tests used to analyze the data. For example, the amount of data required to
reliably establish a trend in data typically is significantly more than that required to compare point-in~time
data. Especially for critical decisions, project managers should seek expert advice in order to design a
sampling program that will yield statistically defensible results. One potential method, power analysis, is
described in Biostatistical Analysis (Zar 1999).
Another crucial element of developing a monitoring plan is cost. Generally, it is more cost-
effective to collect less of the "right" data than it is to collect more of the "wrong" data. Following these
key steps to design a monitoring plan should help project managers determine what the "right" data are.
Project managers may also fmd it useful to consider the use of indicator or surrogate parameters that
correlate with those of primary interest, as a supplement to primary parameters that are especially costly
or problematic to collect.
Finally, this step of monitoring plan development should ensure that there are mechanisms in
place for modifying the plan based on new information.
Example: From the remedial investigation data, we know that smallmouth bass spend
most of their time in the contaminated area and spawn in late spring. The proposed
sampling plan would consist of overlying an unbiased sampling grid onto a map of the
contaminated area of River X as well as in the areas upstream and downstream of the site.
Based on available funding, it is decided that 30 four-year old female bass will be
collected in the early spring, before spawning, in each of these areas. A power analysis
on baseline data indicated 20 fish would allow the project team to discern a 0.5 ppm or
greater change in tissue concentration with 0.25 ppm confidence intervals (90 percent).
However, given cost considerations, only ten samples will be analyzed immediately and
the other 20 archived for further analyses pending the results.
Step 5. Conduct Monitoring Analvses and Characterize Results
The next recommended step in developing a monitoring plan includes data collection and
analysis, evaluating analytical results, and addressing data deviations from the monitoring DQOs. At this
point, the project manager should evaluate the data with regard to the monitoring hypotheses, the DQOs,
and the monitoring decision rules developed in previous steps. At this step, decision rules should be
implemented that may call for continuing, stopping, or modifying the monitoring or for taking additional
action at the site monitored.
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Chapter 8: RemedialAction and Long-Term Monitoring 
In addition, the project manager should communicate data and results to the appropriate
audiences. Frequently, the importance of communicating the results is underestimated. Because
information is often provided to individuals with various levels of technical expertise, it should be
comprehensible at multiple levels of understanding. Complex scientific data are not often easily
understood by those without a technical background, and ineffective data communication often leads to
skepticism about the conclusions. Therefore, it is important that the project manager consider the
audience and present results in multiple formats. To those less familiar with the technical presentation of
data, information can be presented in easily understood visual formats [e.g., geographic information
system (GIS)]. This approach maximizes the effective dissemination of information to the greatest
number of individuals, thus increasing the probability that the conclusions will be understood and
believed.
Example: At this point, three years of fish tissue data have been collected, analyzed, and
validated. The decision criterion for this monitoring objective was to reduce the PCB
concentrations in fish tissue to two ppm within five years. The data show that after the
third year, fish tissue concentrations have decreased significantly but the averages are
still above two ppm; however, the higher levels are restricted to a relatively small area
and most fish are below two ppm. The results are summarized and presented to the
stakeholders. Due to the declining trend, the decision is made that the monitoring
objective is expected to be met within five years and the fourth year monitoring effort can
be skipped.
SteD 6. Establish the Management Decision
The fmal step of a monitoring plan should be an extension of Step 5, to evaluate monitoring
results and uncertainties and come to a decision regarding any changes in site activities or changes in the
monitoring plans that may be appropriate at this time.
Example: Due to the declining trend, the decision is made that the monitoring objective
is expected to be met within five years and the fourth year monitoring effort can be
skipped.
An outline of the six steps and suggested subparts is shown in Highlight 8-2. It should be noted
that the following outline essentially follows EP A's DQO process, with modification for ease of
application to a contaminated sediment site. Project managers should refer to the DQO process guidance
(U.S. EPA 2000a) to supplement this outline when preparing a sediment site monitoring program.
8.3
POTENTIAL MONITORING TECHNIQUES
This section provides a brief overview of the types of monitoring techniques and data endpoints
that the project manager should consider when developing a monitoring plan. The endpoints to select
depend on the requirements in the decision and/or enforcement documents, as well as more general
considerations related to the cleanup methods selected and the phase of the operation, as discussed in
previous sections. For complex sites, frequently a combination of physical, chemical, and biological
methods and a tiered monitoring plan, as described above, is the best approach to determine whether a
sediment remedy meets sediment cleanup levels, remedial objectives or goals, and associated performance
criteria both during remedial action and in the long term. Monitoring, sampling, and analysis methods are
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Chapter 8: Remedial Action and Lonl{-Term Monitorinl{
constantly being improved based on research and increased field experience. Project managers should
watch for new methods and, where they offer additional accuracy or lower cost but also allow for data to
be compared to existing data, consider using them.
Generally, physical and chemical endpoints are easier to measure and interpret than biological
endpoints. In the case of human health risk, chemical measurements are most often used to assess risk.
In contrast, measurement of the biological community is a direct but often complex measurement for
monitoring changes in ecological risk. Caged organisms (e.g., Macoma, or mussels) at the site over a
defmed time frame can identify changes in bioavailable concentrations of many contaminants. Collection
of fish and tissue analysis can address both human health and ecological response of the system, if both
needs are considered during design of the sampling and analysis plan. The project manager should refer
to Office of Water' s Methodsfor Collection, Storage, and Manipulation of Sediments for Chemical and
Toxicological Analyses (U.S. EP A 200lk) and Managing and Sampling and Analyzing Contaminants in
Fish and Shellfish (U.S. EPA 2000g) for more detailed information.
Biological endpoints (e.g., toxicity tests) typically provide an integrated measurement of the
cumulative effects of all contaminants. When using biological endpoints, it is important for the project
manager to ensure that the biological test employed fits the intended criteria. For example, acute toxicity
tests are designed to quantify short-term effects on an organism; therefore, this type of test may be
appropriate when monitoring for short-term impacts of a remedy. Other biological endpoints, such as
changes in community species diversity, typically occur over long periods of time and normally are more
appropriate for use in a long-term monitoring program designed to look at ecological recovery. While no
single endpoint can quantify all possible risks, project managers should consider a combination of
physical, chemical, and biological endpoints to provide the best overall approach for assessing the long-
term effectiveness of a remedial action in achieving the RAOs.
8.3.1
Physical Measurements
Physical testing at a site may include measurements of erosion and/or deposition of sediment,
ground water advective flow, particle size, surface water flow rates, and sediment
homogeneity/heterogeneity. Potential types of physical data and their uses include the following:
.
Sediment Geovhvsical Proverties: Uses include fate and transport modeling,
determination of contaminant bioavailability, and habitat characteristics of post-cleanup
sediment surface;
Water Column Phvsical Measurements (e.$!.. turbiditv. total suspended solids): Uses
include monitoring the amount of sediment resuspended during dredging and during
placement of in-situ caps;
.
Bathvmetry Data: Uses include evaluating post-capping or post-dredging bottom
elevations for comparison to design specifications, and evaluating sediment stability
during natural recovery;
Side Scan Sonar Data: Uses include remote sensing to monitor the distribution of
sediment types and bedforms;
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.
Settlement Plate Data: Uses include monitoring changes in cap thickness over time and
measuring cap consolidation;
.
Sediment Profile Camera Data: Uses include monitoring of changes in thin layering
within sediment profiles, sediment grain sizes, bioturbation and oxidation depths, and the
presence of gas bubbles; and
.
Subbottom Pro filer Data: Uses include remote sensing measurement of changes in
sediment surface and subsurface layers, bioturbation and oxidation depths, and presence
of gas bubbles.
8.3.2
Chemical Measurements
Chemical testing may include sediment chemistry (both the upper biological surficial zone and/or
deeper sediment), evaluating biodegradation, contaminant partitioning to the pore water, and
concentrations of total organic carbon. Potential sampling tools and environmental monitoring methods
used in support of chemical measurements include the following:
.
Sediment Grab Samolers: Uses include collection of samples for measurement of surface
sediment chemistry;
.
Corin,? Devices (e.,?.. vibracore. ,?ravity oiston. or droo tube samplers): Uses include
obtaining a vertical profile of sediment chemistry, or detection of contaminant movement
through a cap or through a layer of naturally deposited clean sediment;
Direct Water Column Measurements (orobes): Uses include measurement of parameters
such as pH and dissolved oxygen in the water column;
Surface Water Samolers: Uses include measurement of chemical concentrations
(dissolved and particulate) in water or contaminant releases to the water column during
construction;
.
Semi-Permeable Membrane Devices: Uses include measurement of dissolved
contaminants at the sediment-water interface; and
Seeoa,?e Meters: Uses include measurement of contaminant flux into the water column.
8.3.3
Biological Measurements
Biological testing can include toxicity bioassays, examining changes in the biological
assemblages at sites, either to document problems or evaluate restoration efforts, and/or determining
toxicant bioaccumulation and food chain effects. Potential types of biological monitoring data and their
uses also include the following:
Benthic Communitv Analvsis: Uses include evaluations of population size and diversity,
and monitoring of recovery following remediation;
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Toxicitv Testinfl: Uses include measurement of acute and long-term lethal or sublethal
effects of contaminants on organisms to help establish protective range of remediation
goals;
Tissue Samolinfl: Uses include measurement ofbioaccumulation, modeling trophic
transfer potential, and estimating food web effects;
CafJed Fish/Invertebrate Studies: Uses include monitoring change in uptake of
contaminants by biota from the sediment or water column to measure the effect of the
remedy on bioaccumulation rates; and
Sediment Profile Camera Studies: Uses include indirect measurement of
macroinvertebrate recolonization, for example, measuring population density of
polychaetes by counting the number of burrow tubes per linear centimeter along the
sediment-water interface.
The interpretation of fish tissue results and their relationship to sediment contaminant levels can
be especially complex. Potential complications may relate to questions of home range, lipid content, age,
feeding regime, contaminant excretion rates, and other factors. Especially at low contaminant
concentrations, these variabilities can make understanding the relationship between trends in sediment
and biota concentrations especially difficult.
Fact sheets are under development at EP A concerning biological monitoring at sediment sites,
including:
.
An approach for using biological measures to evaluate the short-term and long-term
remedial effects at Superfund sites; and
Using bioaccumulation information from biota sediment accumulation factors (BSAFs)
and food chain models to access ecological risks and to develop sediment remediation
goals.
8.4
REMEDY-SPECIFIC MONITORING APPROACHES
The following sections discuss monitoring issues particular to natural recovery, in-situ capping,
and dredging or excavation. Many sediment remedies involve a combination of cleanup methods, and for
these remedies, the monitoring plan will likely include a combination of techniques to measure short and
long term success. At many sediment sites, monitoring of source control actions is an important first step.
8.4.1
Monitoring Natural Recovery
Generally, monitoring is an essential component of a remedy that includes monitored natural
recovery (MNR), as normally contaminants are left in place without protection from physical or
biological disturbances. Monitoring continued effectiveness of source control actions can be especially
important at MNR sites. Depending on the quality of existing trend data, MNR remedies may require
more intensive monitoring early in the recovery period, which may be relaxed if predicted recovery rates
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Chapter 8: Re1llJ!dialAction and Long-Term Monitoring
are being attained. Also, there may be a need to collect additional data after an intensive disturbance
event.
Monitoring of natural recovery often tests the hypothesis that natural processes are continuing to
operate at a rate that is expected to reduce contaminant concentrations in appropriate media such as biota
to an acceptable level in a reasonable time frame. Other measures of reduced risk may also be appropriate
for a site. In most cases, monitoring involves measuring natural processes indirectly or measuring the
effects of those processes. As a sound strategy for monitoring natural recovery the project manager
should consider monitoring the following:
.
Direct or indirect measures of natural processes (e. g., sediment accumulation rates,
degradation products, sediment and contaminant transport);
Contaminant levels in surface sediment and biota; and
Measures of biota recovery (e.g., sediment toxicity, benthic community size and/or
diversity).
EPA's Science Advisory Board (SAB), in its May 2001 report, Monitored Natural Attenuation:
USEP A Research Program - An EP A Science Advisory Board Review (U.S. EP A 200Ij), Section 3.4,
Summary of Major Research Recommendations, indicates the need for the development of additional
monitoring methods to quantify attenuation mechanisms, contaminated sediment transport processes, and
bioaccumulation to support footprint documentation and analysis of permanence. EP A is aware of these
research needs and plans to address some of these topics in ongoing and future work.
For areas that may be subject to sediment disruption, the project manager should conduct more
extensive monitoring when specified disruptive events (e.g., storms or flow stages of a specified
recurrence interval or magnitude) occur in order to evaluate whether buried contaminated sediment has
been disturbed or transported and the extent to which that disturbance has caused a release of
contaminants and increased exposure. The project manager should design the monitoring plan to handle
the relatively quick turnaround times needed to effectively monitor disruptive events. However,
interpretation of these data in terms of increased risk should take into account the length of time
organisms may be exposed to higher levels of contaminant concentrations.
The project manager should include periodic comparisons of monitoring data to rates of recovery
expected for the site in an MNR monitoring program. Where predictions were based on modeling, the
project manager should make monitoring results available to researchers in order to conduct field
validation of the model. Where contingency remedies or triggers for additional work are part of a remedy
decision, the project manager should design the monitoring plan to help determine whether those triggers
are met. For example, a contingency for additional evaluation or additional work may be triggered by an
increasing or insufficiently decreasing trend in contaminant concentrations in sediment, surface water, or
biota at specified locations. Where contingencies for additional work are triggered, the project manager
may need to include measures such as additional source control, additional institutional controls, the
placement of a thin layer of clean sediment to enhance natural recovery, or an active cleanup such as
dredging or capping.
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Chapter 8: RemedialAction and Long-Term Monitoring
Following attainment of cleanup levels and remedial action objectives, monitoring may still be
needed at some MNR sites. For sites where natural recovery is based on burial with clean sediment,
continu,ed monitoring may be necessary in order to assess whether buried contaminants remain buried
after an intensive disturbance event. This monitoring should continue until the project team has
reasonable confidence in the continued effectiveness of the remedy.
8.4.2
Monitoring In-Situ Capping
Generally, monitoring is an essential component of a remedy that includes in-situ capping.
Remedial action monitoring for capping generally includes monitoring of construction and placement,
and of cap performance during an initial period. It may also include monitoring of broader remedial
action objectives such as recovery of the benthic community or of contaminant levels in fish. Long-term
monitoring for capping generally includes continued monitoring of cap performance and maintenance
activities, and continued monitoring of remedial action objectives. In some cases (e.g., Fund-lead sites) it
may be necessary to distinguish monitoring that is part of remedial action from monitoring that is part of
O&M. This should be a site-specific decision. Highlight 8-3 lists sample elements of monitoring an in-
situ cap.
As shown in Highlight 8-3, a variety of monitoring equipment and methods can be used for
capping projects during both remedial action and long-term monitoring. Decisions about what
monitoring to require should be site-specific and also depend on decision and enforcement document
requirements. In general, bathymetric surveys to determine cap thickness and stability over time, sediment
core chemistry (including surface sediments and upper portion of cap) to confmn physical and chemical
isolation and test for recontamination, and some form of biological monitoring are needed for most
capping projects. Specialized equipment, such as seepage meters, diffusion samplers (e.g., peepers and
semi-permeable membrane devices), sediment profile cameras, sediment traps, or use of caged organisms,
may also be useful in some cases.
Construction monitoring for capping normally is designed to measure whether design plans and
specifications are followed in the placement of the cap and to monitor the extent of any contaminant
releases during cap placement. During construction, monitoring results can be used to identify
modifications to design or construction techniques needed to meet unavoidable field constraints.
Construction monitoring frequently includes interim and post-construction cap material placement
surveys. Appropriate methods for monitoring cap placement include bathymetric surveys, sediment
cores, sediment profiling camera, and chemical resuspension monitoring for contaminants. For some
sites, visual observation in shallow waters or surface visual aids, such as viewing tube or diver
observations, can also be useful.
Biological monitoring in the initial period following cap construction may include monitoring of
the benthic community that may recolonize the capped site and the bioturbation behavior of benthic
organisms. Where contaminants are bioaccumulative, fish or other biota edible tissue or whole body
monitoring are also likely to be needed.
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Chapter 8: Remedial Action and Long-TennMonitoring
Cap Construction Cap material quality Cap material sampling Physical properties, size 5% of loads
 and size   
 Cap thickness and Bathymetry Thickness of cap layers Baseline
 areal extent Subbottom profile Areal extent of cap Initial placement
    Final surveys over entire area
  Sediment profile camera Thickness of cap layers Baseline
  (SPC)  Initial placement
    Defined grid for remaining cells
  Cores Layer thickness and physical properties Defined grid
   Chemical properties for baseline 
 Sediment Plume tracking Suspended sediment 5% of load placements
 resuspension Acoustic doppler current Water column chemistry 
  profile (ADCP)  
  Water column samples  
 Sediment Sediment samples Chemical properties of sediment Sediment bed near cap boundaries
 displacement   
Cap Performance Re-colonization SPC Layer thickness Defined grid - frequency determined by local
  Benthic community analysis Re-colonization, population size, and diversity information about recolonization rates
 Physical isolation Subbottom profile Layer thickness Annual checks in some cases
  Bathymetry, cores  Surveys over entire area every five years
 Chemical isolation Cores Physical properties Defined grid every five years
  Peepers, seepage meters Sediment chemistry, pore water chemistry 
Severe Event Cap integrity Subbottom profile  Following major storms or earthquakes
Response  SPC  
  Cores  
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Chapter 8: Remedial Action and Long-Term Monitoring 
. Long-tenn monitoring of in-situ capping sites is important to ensure that the cap is not being
eroded or significantly compromised (e.g., penetrated by submerged aquatic vegetation, ground water
recharge, or bioturbation) and that chemical contaminant fluxes that ultimately do move through the cap
to surface water do so at the low projected rate and concentration. It is also frequently desirable to
include ongoing monitoring for recontamination of the cap surface and non-capped areas from other
sources.
For areas that may be subject to cap disruption, more extensive monitoring should be triggered
when specified disruptive events (e.g., stonns or flow stages of a specified recurrence interval or
magnitude) occur, in order to evaluate whether the cap was disturbed and whether any disturbance caused
a significant release of contaminants and increased risk. Additional monitoring for the effects of tidal and
wave pumping and boat propeller wash is also recommended. In general, the project manager should
monitor cap integrity both routinely and following all storm/flood events that approach the design stonn
magnitude envisioned by the cap's engineers. As for other types of sediment remedies, the project
manager should design the monitoring plan to handle the relatively quick turnaround times needed to
effective monitoring of expected disruptive events.
Cap maintenance is generally limited to the repair and replenishment of the erosion protection
layer in potentially high erosion areas where this is necessary. Project managers should consider the
ability to detect and quickly respond to a loss of the erosion protection layer when evaluating a capping
alternative. Seasonal limitations, such as ice fonnation or closure of navigation structures (locks), can
limit the ability to monitor in-situ caps after a significant erosion event. This can also limit the project
manager's ability to respond if maintenance is needed.
Capping remedies frequently include provisions for actions to be taken in the case that one or
more cap functions are not being met. Options for modifying the cap design mayor may not be available.
If monitoring shows that the stabilization component is being eroded by events of lesser magnitude than
planned, or the erosive energy at the capping site was underestimated, then eroded material can be
replaced with more erosion-resistant cap material. If monitoring indicates that bottom-dwelling
organisms are penetrating the cap in significant numbers, then project managers should consider placing
additional cap material on top of the cap to maintain isolation of the contaminated sediment. These types
of management options are usually feasible where additional cap thickness, and the resulting decrease in
water depths at the site, does not conflict with other waterway uses. Where a cap has been closely
designed to a thickness that will not limit waterway use (i.e., recreational or commercial navigation), the
options for modifying a cap design after construction can be limited. .
8.4.3 Monitoring Dredging or Excavation
Like all sediment remedies, monitoring generally is an essential component of a remedy that
includes dredging or excavation. Monitoring for this type of remedy generally includes construction and
operational monitoring of the dredging or excavation, transport, dewatering, any treatment, transport, and
anyon-site disposal placement. Following dredging or excavation, the residual sediment contamination
should also be monitored. Additional monitoring following sediment removal may include monitoring of
sediment toxicity or benthic community recovery or, for bioaccumulative contaminants, tissue
concentrations in fish or shellfish, as well as continued monitoring of anyon-site disposal facilities and
monitoring sediment and/or biota for recontamination.
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Chapter 8: Remedial Action and Long-Term Monitoring
Depending on the levels of contamination and the selected methods of dredging/excavation,
transport, treatment or disposal, potential construction and operational monitoring may include the
following:
.
Surface water monitoring at the dredging site and any in-water disposal sites (e.g., total
suspended solids, total and dissolved contaminant concentrations, caged fish toxicity,
caged mussel intake);
Monitoring of dredging/excavation residuals at the sediment surface to determine
whether cleanup levels are met;
.
Effiuent quality monitoring after sediment dewatering and/or treatment;
Air monitoring at the dredge, transport, on-site disposal, and treatment sites; and
.
Monitoring of on-site disposal of dredged sediment or treatment residuals.
A thorough monitoring plan will normally enable project managers to make design or
construction changes in order to ensure that the spread of contamination to uncontaminated areas of the
water body, sensitive habitats, or adjacent human populations is minimized during dredging, transport,
treatment, or disposal. Depending on the contaminants present and their tendency to volatilize or
bioaccumulate, the project manager should consider water, air, and biological sampling in the monitoring
plan.
Generally, a monitoring plan for dredging should include collecting data to test the effectiveness
of silt curtains, dredge operating practices, and any other measures used to control sediment resuspension
or sediment or contaminant transport. In most cases the project manager should include sampling
up gradient of the dredging operation and both inside and outside of any containment structures.
Generally this sampling should also include dissolved compounds in the water column, although in some
cases it may be a appropriate to, use a tiered approach with analysis of dissolved compounds triggered by
exceedances of threshold criteria for total compounds or for suspended solids. Also, where contaminants
may be volatile, project managers should consider including air sampling. At highly contaminated sites,
it may be necessary for the project manager to conduct a pilot study on a small area to determine if the
sediment may be removed without causing unacceptable risks to adjacent human populations or adjacent
benthic habitat. This information can help to determine what containment barriers or dredging methods
work best and what performance standards are achievable at the site. The project manager should
compare monitoring results baseline data for contaminant concentrations in water and, where appropriate,
in air. This should ensure that effects due to dredging may be separated and evaluated from natural
perturbations, such as tide and storm influence. The project manager should develop contingency plans to
guide changes in operation where performance standards are not met.
Following dredging, it is usually essential for project managers to conduct monitoring in order to
determine whether cleanup levels in sediment are achieved. Initial sampling should be analyzed rapidly,
so that contingency actions, such as additional dredging, excavation, or backfilling, can be implemented
quickly if cleanup levels have not been met.
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Chapter 8: RemedialAction and Long-Term Monitoring 
Following sediment removal, it is usually necessary for the project manager to conduct long-term
monitoring to ensure that the dredged or excavated area is not re-contaminated by additional sources or
by disturbance of any residuals that remain above cleanup levels. Long-term monitoring is usually
necessary to provide data to determine whether remedial action objectives are met, and may be necessary
for a period of time following remedial action to provide confidence that the objectives will remain met.
If an in-water or upland disposal facility is constructed on-site as part of the remedy, it should
also be monitored to ensure that it remains intact and that there are no unacceptable contaminant releases
in the long term. Monitoring is recommended to resolve whether contaminants are leaking through the
bottom or walls of the on-site confined disposal facility (CDF) or landfill, and that any surface cap
remains intact to ensure protection from infiltration. Depending on the type of disposal site and the
nature of the contamination, long-term disposal site monitoring may include the following:
Seepage from the CDF containment cells to surrounding surface water;
Ground water monitoring;
.
Surface water run-off monitoring;
Monitoring of disposal area cap integrity; and
Monitoring ofre-vegetation or re-colonization by plant and animal communities, and
their potential uptake of contaminants.
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Chapter 8: Remedial Action and LonK- Term MonitorinK
Highlight 8-4 lists important points to remember related to monitoring sediment sites.
.............. ...... .'"''''
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A monitoring plan may be important for all types of sediment remedies, both during and following any
physical construction, to ensure that exposure pathways and risks have been adequately managed
The development of monitoring plans should follow a systematic planning process that identifies
monitoring objectives, decision criteria, endpoints, and data collection, analysis, and data interpretation
methods
Before implementing a remedial action, project managers should review baseline data and collect
additional data if needed to ensure that an adequate baseline exists for comparison to monitoring data
Where background conditions may be changing or where uncertainty exists conceming continuing off-site
contaminant contributions to a site, it is likely to be necessary to continue collecting data from upstream
or other reference areas for comparison to site monitoring data
Monitoring needs include both monitoring of construction and operation and monitoring intended to
measure whether cleanup levels in sediment and remedial action objectives for biota or other media have
been met
Monitoring plans should be designed to evaluate whether performance standards of the remedial action
are being met and should be flexible enough to allow revision if operating procedures are revised
Field measurement methods and quick turnaround analysis methods with real-time feedback are
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Contaminated Sediment Remediation Guidance
for Hazardous Waste Sites
REFERENCES
Abramowicz, D.A, and D.R. Olsen. 1995. Accelerated Biodegradation of PCBs. Chern tech 24:36-41.
Averett, D.E., B.D. Perry, E.I. Torre, and J.A Miller. 1990. Review or Removal, Containment, and
Treatment Technologies for Remediation of Contaminated Sediments in the Great Lakes,
Miscellaneous Paper EL-90-25. U.S. Army Corps of Engineers Waterways Experiment Station,
prepared for U.S. Environmental Protection Agency - Great Lakes National Program Office,
Chicago, IL.
Barth, E., B. Sass, A Polaczyk, and R. Lundy. 2001. Evaluation of Risk from Using Poultry Litter to
Remediate and Reuse Contaminated Estuarine Sediments. Journal of Remediation. Autumn.
Bedard, D.L., and R.I. May. 1996. Characterization of the Polychlorinated Biphenyls in Sediments of
Woods Pond: Evidence for Microbial Declorination of Aroclors 1260 In-situ. Environ. Sci.
Technol. 30:237-245.
Bergen, B.I., W.G. Nelson, J. Mackay, D. Dickerson, and S. Jayaraman. In preparation. Environmental
Monitoring of Remedial Dredging at the New Bedford Harbor, Massachusetts Superfund Site.
Expected release 2004.
Black and Veatch. In preparation. Confmed Disposal Facility Report to Congress. Submitted to U.S.
Army Corps of Engineers - Great Lakes Division and U.S. Environmental Protection Agency -
Great Lakes National Program Office. Expected release 2004.
Bolger, M. 1993. Overview of PCB Toxicology. In: Proceedings of the U.S. Environmental Protection
Agency's National Technical Workshop PCBs in Fish Tissue. U.S. Environmental Protection
Agency Office of Water, Washington, DC. EPA 823-R-93-003. September.
Boyer, L.F., P.L. McCall, F.M. Soster, and R.B. Whitlatch. 1990. Deep Sediment Mixing by Burbot
(Lota Iota), Caribou Island Basin, Lake Superior, USA Ichnos 1: 91-95, in: Matisoff, G. 1995.
Effects of Bioturbation on Solute and Particle Transport in Sediments. In: Allen, H.E. (Ed.).
1995. Metal Contaminated Aquatic Sediments, Ann Arbor Press, Inc., Chelsea, MI. pp.
201-272. .
Brown, J.F., Jr., R.E. Wagner, H. Feng, D.L. Bedard, M.I. Brennan, J.C. Carnaham and R.I. May. 1987.
Environmental Declorination of PCBs. Environ. Toxicol. Chern. 6:579-593.
Cerniglia, C.E. 1992. Biodegradation of Polycyclic Aromatic Hydrocarbons. Biodegradation
3:351-368.
Chiarenzeli, J., R. Scrudata, B. Bush, D. Carpenter, and S. Bushart. 1998. Do Large Scale Remedial
Dredging Events Have the Potential to Release Significant Amounts of Semivolatile Components
to the Atmosphere? Environmental Health Perspectives. Vol1'06, Number 2. February.
Churchward, v., E. Isely, and AT. Kearney. 1981. National waterways study-overview of the
January 2005 Draft, Peer Review Document
-------
Contaminated Sediment Remediation Guidance
for Hazardous Waste Sites

transportation industry. U.S. Army Corps of Engineers, Institute for Water Resources, Water
Resources Support Center, Fort Belvoir, Virginia.
Clarke, D.G., Palermo, M.R, and Sturgis, T.C. 2001. Subaqueous cap design: Selection of bioturbation
profiles, depths, and rates. DOER Technical Notes Collection. ERDC TN-DOER-C21, U.S.
Army Corps Engineer Research and Development Center, Vicksburg, Mississippi
\""\vw. wes.armv .mil/el/dots/doer
Cowardin, L.M., V. Carter, F.C. Golet and E.T. LaRoe. 1979. Classification of Wetlands and Deepwater
Habitats of the United States. U.S. Fish and Wildlife Service. U.S.DOI, FWS/OBS-79/31, 103
pp.
Cowen, C.E., et al., eds. (1999) The Multi-media fate model: A vital tool for predicting the fate of
chemicals. SET AC Press.
Davis, J.W., Dekker, T., Erickson, M., Magar, v., Patmont, C., and Swindoll, M, 2003, Framework for
evaluating the effectiveness of monitored natural recovery (MNR) as a contaminated sediment
management option. Proceedings: 2nd International Conference on Remediation of Contaminated
Sediments, Venice, Italy (September 30,2003), Battelle, Columbus, Ohio. (Working draft also
available on the Remedial Technologies Development Forum Web site at w,,,,,"w.rtdf.org.)
Dec, 1., and J.M. Bollag. 1997. Determination of Covalent Binding Interaction Between Xenobiotic
Chemicals and Soils. Soil Sci. 162: 858-874.
Flanagan, W.P., and R.I. May. 1993. Metabolic Detection as Evidence for Naturally Occurring Aerobic
PCB Biodegradation in Hudson River Sediments. Environ. Sci. Techno!. 27: 2207-2212.
Francingues, N.R., and D.W. Thompson. 2000. Innovative Dredged Sediment Decontamination and
Treatment Technologies. DOER Technical Notes Collection (ERDC TN-DOER-T2), U.S. Army
Engineers Research and Development Center, Vicksburg, Mississippi. Available at
http://www.wes.armv.mil/el/dots/doer.
Ghiorse, W. C., Herrick, 1. B., Sandoli, R. L., and E. L. Madsen. 1995. Natural selection ofPAH-
degrading bacterial guilds at coal-tar disposal sites. Environ. Health Perspect. 103(5): 103-111.
Hall, J.S. 1994. Physical Disturbance and Marine Benthic Communities: Life in Unconsolidated
Sediment. Oceanography and Marine Biology: An Annual Review. 32: 179-239.
Harkness, M.R., J.B. McDermott, D.A Abramowicz, U. Salvo, W.P. Flanagan, M.L. Stephens, F.I.
Mondello, R.I. May, 1.H. Lobos', K.M. Carrol, M.I. Brennan, AA Bracco, K.M. Fish, G.L.
Wagner, P.R. Wilson, D.K. Dierich, D.T. Lin, C.B. Morgan and W.L. Gately. 1993. In-situ
Stimulation of Aerobic PCB Biodegradation in Hudson River Sediments. Science 159:503-507.
Hays, D., and P. Wu. 2001. "Simple approach to TSS source strength estimates." Proceedings, 2181
Annual Meeting of the Western Dredging Association (WEDA XXI) and 33rd Annual Texas
A&M Dredging Seminar, Houston, Texas.
January 2005 Draft, Peer Review Document
-------
Contaminated Sediment Remediation Guidance
for Hazardous Waste Sites

Hylleberg, J. 1975. Selective Feeding by Abarenicola vagabunda and a Concept of Gardening in
Lugwonns. Ophelia 14: 113-137. In: Lee, H., II, and R. Swartz. 1980. Biological Processes
Affecting the Distribution of Pollutants in Marine Sediments. I. Biodeposition and bioturbation
In: Baker, R.A. (Ed.). 1980. Contamination and Sediments, Vol. 2, Ann Arbor Science, Ann
Arbor, Michigan. p. 564.
Jepsen, R., 1. Roberts, and W. Lick. 1997. "Effects of Bulk Density on Sediment Erosion Rates." Water,
Air and Soil Pollution, Kluwer Academic Publishers, The Netherlands. 99: 21-37.
Langworthy, D.E., R.D. Stapleton, G.S. Sayler, and R.H. Findlay. 1998. Genotypic and phenotypic
responses of a riverine microbial community to polycyclic aromatic hydrocarbon contamination.
Appl. EnvUon. Microbiol. 64(9): 3422-3428.
Lee, c.R. 2000. Reclamation and Beneficial Use of Contaminated Dredged Material: Implementation
Guidance for Select Options. DOER Technical Notes Collection (ERDC TN-DOER-CI2). U.S.
Anny Corps of Engineers Research and Development Center, Vicksburg, Mississippi. Also
available on the Internet at: http://www.wes.anny.mil/eVdots!doer.
Liu and Znidarcic. 1991. Modeling one dimensional compression characteristics of soils, J. Geotechnical
Engineering, ASCE, 117(1): 162-169.
Luthy, R.G., G.R. Aiken, M.L. Brusseau, S.D. Cunningham, P.M. Gschwend, U. Pingnatello, M.
Reinhard, SJ. Traina, WJ. Weber, Jr. and 1.C. Wenta1l. 1997. Sequestration of Hydrophobic
Organic Contaminants by Geosorbents. Environ. Sci. Tech. 31: 3341-3347.
Maa, J.P.-Y., L.D. Wright, C.-H. Lee, and T.W. Shannon. 1993. VIMS sea carousel: a field instrument
for studying sediment transport. Marine Geology 115: 271-287.
MacKnight, S.D. 1992. Dredging of contaminated sediment between pre-dredging survey and treatment.
In: Proc. of the International Symposium on Environmental Dredging, Buffalo, NY.
MaIlhot, H., and R. H. Peters. 1988. Empirical Relationships Between the L-octane/water Partition
Coefficient and Nine Physiochemical Properties. Environ. Sci. Technol. 22: 1479-1488.
Matisoff, G., X. Wang and P.L. McCall, 1999. Biological redistribution oflake sediments by tubificid
oligochaetes, Journal of Great Lakes Research, 25(1): 205-219.
Matisoff, G. and X. Wang, 2000. Particle mixing by freshwater infaunal bioirrigators: madiges and
mayflies. Journal of Great Lakes Research, 26(2): 174-182.
McLaren, P. and Bowles, D., 1985: The effects of sediment transport on grain-size distributions; Journal
of Sedimentary Petrology, 55: 457-470.
McLaren, P., Cretney, WJ., and Powys, R., 1993: Sediment pathways in a British Columbia fjord and
their relationship with particle-associated contaminants; Journal of Coastal Research, 9:
1026-1043.
January 2005 Draft, Peer Review Document
-------
Contaminated Sediment Remediation Guidance
(or Hazardous Waste Sites

McNeil, 1., C. Taylor, and W. Lick. 1996. Measurements of erosion of undisturbed bottom sediments
with depth. Journal of Hydraulic Engineering 122(6): 316-324.
Meador, J.P., Stein, J.E., Reichert, W.L., Varanasi, U. 1995. Bioaccumulation of polycyclic aromatic
hydrocarbons by marine organisms. Rev. Environ. Contamin. Toxicol. 143:79-163.
Mulligan, C.N., R.N. Yong, and B.F. Gibbs. 2001. Heavy Metal Removal from Sediments by
Biosurfactants. Journal of Hazardous Materials 85: 111-125.
Myers, T.E., and M.E. Zappi. 1989. New Bedford Harbor Superfund Project, Acushnet River Estuary -
Engineering Feasibility Study of Dredging and Dredged Material Disposal Alternatives. Report
No.9, Laboratory-Scale Application of Solidification/Stabilization Technology, Technical Report
EL-88-15. U.S. Army Corps of Engineers Waterways Experiment Station, Vicksburg,
Mississippi.
Myers, T.E., R.P. Gambrell, and M.E. Tittlebaum. 1991. Design of an Improved Column Leaching
Apparatus for Sediments and Dredged Material, Miscellaneous Paper D-91-3. U.S. Army Corps
of Engineers Waterways Experiment Station, Vicksburg, Mississippi.
Myers, T.E., and D.W. Bowman. 1999. Bioremediation ofPAH-Contaminated Dredged Material at the
Jones Island CDF: Materials, Equipment, and Initial Operations. DOER Technical Notes
Collection (ERDC TN-DOER-C5), U.S. Army Engineers Research and Development Center,
Vicksburg, Mississippi. Available at httn://www.wes.armv.mil/e1/dots/doer
Myers, T.E., and D.D. Adrian. 2000. Equipment and Processes for Removing Debris and Trash from
Dredged Material. DOER Technical Notes Collection (ERDC TN-DOER-CI7), U.S. Army
Engineers Research and Development Center, Vicksburg, Mississippi. Available at
http://www. wes.army .miJielldots/doer
Myers, T.E., and Williford. 2000. Concepts and Technologies for Bioremediation in Confmed Disposal
Facilities. DOER Technical Notes Collection (ERDC TN-DOER-Cll), U.S. Army Engineers
Research and Development Center, Vicksburg, Mississippi. Available at
http://\v\vw.wes.armv .mil/ell dots/doer
NRC. 1997. Contaminated Sediments in Ports and Waterways. National Academy of Press,
Washington, DC. Available from the National Academy of Press Web site at
httD:! /www.nap.edu!bookstore.
NRC. 2001. A Risk-Management Strategy for PCB-Contaminated Sediments. Committee on
Remediation of PCB-Contaminated Sediments, Board on Environmental Studies and Toxicology,
Division on Life and Earth Studies, National Research Council. National Academy Press,
Washington, DC. May.
Palermo, M.R. 1995. Considerations for Disposal of Dredged Material in Solid Waste Landfills.
Proceedings of the 16th Annual Meeting of the Western Dredging Association, St. Paul, MN, May
23-26, 1995.
January 2005 Draft, Peer Review Document
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Contaminated Sediment Remediation Guidonce
for Hazardous Waste Sites
Palermo, M.R. 1997. Contained Aquatic Disposal of Contaminated Sediments in Subaqueous Borrow
Pits. Proceedings of the Western Dredging Association 18th Technical Conference and 30th
Annual Texas A&M Dredging Seminar, June 29-July 2, 1997, Charleston, South Carolina.
Palermo, M.R.., and D.E. Averett. 2000. Confmed Disposal Facility (CDF) Containment Measures: A
Summary ofField Experience. DOER Technical Notes Collection (ERDC TN-DOER-CI8), U.S.
Army Engineers Research and Development Center, Vicksburg, Mississippi. Available on the
Internet at: http://v.'W\v.wes.army miVeVdots/doer.
Palmero, M.R., and D.E. Averett. 2003. "Environmental dredging - A state of the art review."
Proceedings of the 2nd International Symposium on Contaminated Sediments: Characterization,
Evaluation, Mitigation/Restoration, Monitoring, and Performance, Quebec, Canada, May 26-28.
Palermo, M.R., J.E. Clausner, M.P. Rollings, G.L. Williams, T.E. Myers, TJ. Fredette, and R.E. Randall.
1998a. Guidance for Subaqueous Dredged Material Capping. U.S. Army Corps of Engineers
Waterways Experiment Station, Vicksburg, Mississippi. Technical Report DOER-I. Available
on the Internet at http://www.wes.armv .miVelldots/doer/pdf/doer-I.pdf.
Palermo, M., N. Francingues, and D. Averett. 1998b. Environmental Dredging and Disposal- Overview
and Case Studies. Proceedings, National Conference on Management and Treatment of
Contaminated Sediments. u.s. Environmental Protection Agency, Office of Research and
Development, Washington DC. EPA 625/R-98/00I.
Palermo, Michael R., Francingues, Norman R., and Averett, Daniel E., in prep., Operational
characteristics and equipment selection factors for environmental dredging. Journal of Dredging
Engineering, Western Dredging Association Vol. x, No. x.
Pascoe, G.A. McLaren, P., and Soldate, M., 2002: Impact of offsite sediment transport and toxicity on
remediation of a contaminated estuarine bay. Marine Pollution Bulletin, 44: 1184-1193.
Pennak, R.W. 1978. Fresh-water Invertebrates of the United States. 2nd Edition. John Wiley & Sons,
New York.
Ravens, T. M., and P. M. Gschwend. 1999. Flume Measurements of Sediment Erodibility in Boston
Harbor. J. Hydraulic Engineering 125: 998-1005.
Reible, D.D., and LJ. Thibodeaux. 1999. Using Natural Processes to Defme Exposure from Sediments.
Sediment Management Work Group Technical Paper. Available at ht4>://www.smwg.org.
Reid, BJ., K.C. Jones, and K.T. Semple. 2000. Bioavailability of persistent organic pollutants in soils
and sediments - a perspective on mechanisms, consequences and assessment. Environ. Poll.
108:103-112.
Rhoads, D. 1967. Biogenic Reworking of Intertidal and Subtidal Sediments in Barnstable Harbor and
Buzzards Bay, Massachusetts. J. Geol. 75: 461-476. In: Lee, H., II, and R. Swartz. 1980.
January 2005 Draft, Peer Review Document
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Contaminated Sediment Remediation Guidance
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Biological Processes Affecting the Distribution of Pollutants in Marine Sediments. I.
Biodeposition and Bioturbation. In: Baker, R.A. (Ed.). 1980. Contamination and Sediments,
Vol. 2, Ann Arbor Science, Ann Arbor, MI. pp. 564, 567.
Risk, M., and J. Moffat. 1977. Sedimentological Significance of Fecal Pellets of Mac om a balthica in
Minas Basin, Bay of Fundy. J. Sediment 47: 1425-1436. In: Lee, H., II, and R. Swartz. 1980.
Biological Processes Affecting the Distribution of Pollutants in Marine Sediments. I.
Biodeposition and Bioturbation. In: Baker, R.A. (Ed.). 1980. Contamination and Sediments,
Vol. 2, Ann Arbor Science, Ann Arbor, MI. p.564.
Roch, F., and M. Alexander. 1997. Inability of bacteria to degrade low concentrations of toluene in
water. Environ. Toxicol. Chern. 16(7): 1377-1383.
Ruiz, C.E., N.M. Aziz, and P.R. Schroeder. 1999. RECOVERY: A Contaminated Sediment-Water
Interaction Model. Miscellaneous Paper D-99-xx. U.S. Army Corps of Engineers Waterways
Experiment Station, Vicksburg, Mississippi.
Ryan IN., S. Mangion and D. Willey. 1995. Turbidity and Colloid Transport, In: U.S. EPA Ground
Water Sampling - A Workshop Summary, Dallas, Texas, November 30-December 2, 1993. EPA
600/R-94/205.
Safe, S. 1980. Metabolism Uptake, Storage, and Bioaccumulation. In: Halogenated Biphenyls,
Napthylenes, Di-benzodioxins and Related Products. R. Kimbroush, ed. Elsevier, North Holland.
pp.81-107.
Safe, S. 1992. Toxicology Structure-function Relationship and Human Environmental Health Impacts of
Polychorinated Biphenyls: Progress and Problems. Environ. Health Perspect. 100:259-268.
Schwartz, E., and K.M. Scow. 2001. Repeated inoculation as a strategy for the remediation oflow
concentrations of phenanthrene in soil. Biodegradation 12: 201-207.
\

Seech, A., B. O'Neil and L.A. Comacchio. 1993. Bioremediation of Sediments Contaminated with
Polynuclear Aromatic Hydrocarbons (PAHs). In: Proceedings of the Workshop on the Removal
and Treatment of Contaminated Sediments. Environment Canada's Great Lakes Cleanup Fund.
Wastewater Technology Centre, Burlington, Ontario.
Sensebe. 1994. Personal communication.
Shuttleworth, K.L., and C.E. Cerniglia. 1995. Environmental Aspects ofPAH Biodegradation. Appl.
Biochem. Biotechnol. 54:291-302.
Simmons. 1993. Personal communication.
St. Lawrence Centre. 1993. Selecting and Operating Dredging Equipment: A Guide to Sound
Environmental Practices, prepared in Collaboration with Public Works Canada and the Ministere
de l' Environment du Quebec, written by Les Consultants Jacques Berube, Inc. Cat. No. En
January 2005 Draft, Peer Review Document
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Contaminated Sediment Remediation Guidance
for Hazardous Waste Sites

40-438/1993E.
Stem, E.A, J. Olba, B. Wisemiller, and AA Massa. 1994. Recent Assessment and Decontamination
Studies of Contaminated Sediments In the New York/New Jersey Harbor. Dredging '94:
Proceedings of Second International Conference on Dredging and Dredged Material Placement,
14-16 November 1994, Orlando, Florida. E.C. McNair (ed.), American Society of Civil
Engineers, New York.
Stem, E.A., J.L. Lodge, K.W. Jones, N.L. Clesceri, H. Feng, and W.S. Douglas. 2000. Decontamination
and Beneficial Use of Dredged Materials.
Stem, E.A 2001. Status Sheet-NY/NJ Harbor Sediment Decontamination Program.
Stull, J.K., DJ.P. Swift and AW. Niedoroda. 1996. Contaminant Dispersal on the Palos Verdes
Continental Margin: I. Sediments and Biota near a Major California Wastewater Discharge. Sci.
of the Total Environment. 179:73-90.
Suendel, B.C., J.A Boraczek, R.K. Peddicord, P. Clifford, T.M. Dillon. 1994. Trophic transfer and
biomagnification potential of contaminants in aquatic ecosystems. Rev. Environ. Contam.
Toxicol. 136:21-89.
Swindoll, M., R.G. Stahl, and SJ. Ells., eds. 2000. Natural Remediation of Environmental
Contaminants: Its Role in Ecological Risk Assessment and Risk Management. Society of
Environmental Toxicology and Chemistry (SET AC) Press.
Tabak, H.H., and R. Govind. 1997. Bioavailability and Biodegradation Kinetics Protocol for Organic
Pollutant Compounds to Achieve Environmentally Acceptable Endpoints During Bioremediation.
In: Bioremediation of Surface and Subsurface Contamination, Annals of New York Academy of
Sciences. 829:36-60.
Tsai, c.-H., and W. Lick. 1986. A portable device for measuring sediment resuspension. J.ofGreat
Lakes Res. 12(4): 314-321.
Turner, T.M. 1984. Fundamentals of hydraulic dredging. Cornell Maritime Press, Centerville,
Mary land. .
USACE. 1983. Dredging and Dredged Material Disposal. Engineer Manual 1110-2-5025. U.S. Army
Corps of Engineers, Washington, DC.
USACE. 1987. Confmed Disposal of Dredged Materials. Engineer Manual 1110-2-5027. U.S. Army
Corps of Engineers, Washington, DC.
USACE. 1992. Thin Layer Placement of Dredged Material Feasibility Analysis, Eagle Harbor,
Washington. U.S. Army Corps of Engineers, Seattle District.
USACE. 1995. LTFATE: A Model to Investigate the Long-Term Fate and Stability of Dredged
.,
January 2005 Draft, Peer Review Document
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Material Disposal Sites; Users Guide (IR DRP-95-1). U.S. Army Corps of Engineers Waterways
Experiment Station, Vicksburg, MS.
USACE. 2003. Evaluation of Dredged Material Proposed for Disposal at Island, Nearshore, or Upland
Confmed Disposal Facilities - Testing Manual. U.S. Army Corps of Engineers Research and
Development Center, Waterways Experiment Station, Vicksburg, Mississippi. ERDC/EL
TR-03-1. January.
USACE WES. 1998. Volatile Losses from Exposed Sediments. Dredging Research Technical Note.
EEDP-02-24. U.S. Army Corps of Engineers, Waterways Experiment Stations, Vicksburg,
Mississippi. May.
USACE and U.S. EPA. 1998. Evaluation of Dredged Material Proposed for Disposal in Inland and Near
Coastal Waters - Testing Manual. U.S. Department of the Army and U.S. Environmental
Protection Agency, Office of Water, Washington, DC. EPA 823-B-98-004. February.
U.S. EPA. 1988a. Guidance for Conducting Remedial Investigations and Feasibility Studies under
CERCLA, Interim Final. U.S. Environmental Protection Agency Office of Emergency and
Remedial Response, Washington, DC. OSWER Directive 9355.3-01. October.
U.S. EPA. 1988b. CERCLA Compliance with Other Laws Manual, Interim Final. U.S. Environmental
Protection Agency Office of Emergency and Remedial Response, Washington, DC. OSWER
Directive 9355.0-67FS. EPA 540-G-89-099. December.
U.S. EPA. 1989. Risk Assessment Guidance for Superfund. U.S. Environmental Protection Agency
Office of Emergency and Remedial Response, Washington, DC. EPA 540/1-89/002. December.
U.S. EPA. 19991a. Compendium ofCERCLA ARARs Fact Sheets and Directives. U.S. Environmental
Protection Agency Office of Solid Waste and Emergency Response, Washington, DC. OSWER
Directive 9347.3 -15.
U.S. EPA. 1991b. Handbook: Remediation of Contaminated Sediments. U.S. Environmental Protection
Agency Office of Research and Development, Cincinnati, OR. EPA 625/91/028. April.
U.S. EPA. 1991c. A Guide to Principal Threat and Low-level Threat Wastes. U.S. Environmental
Protection Agency, Office of Solid Waste and Emergency Response, Washington, DC. OSWER
Directive 9380.3-06FS.
U.S. EPA. 1 992a. ECO Update - The Role of Natural Resource Trustees in the Superfund Process.
Intermittent Bulletin Vol. I, No.3. U.S. Environmental Protection Agency Office of Emergency
and Remedial Response, Washington, DC. OSWER Directive 9345.0-051. March.
U.S. EPA. 1 992b. Early Action and Long-Term Action under SACM - Interim Guidance. U.S.
Environmental Protection Agency Office of Emergency and Remedial Response, Washington,
DC. OSWER Directive 9203.1-051. December.
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U.S. EPA. 1993a. Guidance on Conducting Non-Time-Critical Removal Actions Under CERCLA. U.S.
Environmental Protection Agency Office of Solid Waste and Emergency Response, Washington,
DC. OSWER Directive 9360.0-32. EPA 540/R-93/057. August.
U.S. EPA. 1993b. Revisions to OMB Circular A-94 on Guidelines and Discount Rates for Benefit-Cost
Analysis. Office of Solid Waste and Remedial Response, Washington, DC. OSWER Directive
No. 9355.3-20.
U.S. EPA. 1993c. ARCS Risk Assessment and Modeling Overview Document. U.S. Environmental
Protection Agency Great Lakes National Program Office, Chicago, Illinois.
U.S. EPA. 1993d. Selecting Remediation Technologies for Contaminated Sediment. U.S.
Environmental Protection Agency Office of Water, Washington, DC. EPA 823/B-93/001.
U.S. EPA. 1994a. RCRA Corrective Action Plan (Final). U.S. Environmental Protection Agency, Office
of Waste Programs Enforcement and Office of Solid Waste. OSWER Directive 9902.3-2A.
May.
U.S. EPA. 1994b. Role of the Ecological Risk Assessment in the Baseline Risk Assessment. Office of
Solid Waste and Emergency Response. OSWER Directive 9285.7-17. April 12.
U.S. EPA. 1994c. Guidance for Conducting External Peer Review of Environmental Regulatory Models.
U.S. Environmental Protection Agency, Office of the Administrator, Agency Task Force on
Environmental Regulatory Modeling, Washington, DC. EPA 100/B-94/001. July.
U.S. EPA. 1 994d. Assessment and Remediation of Contaminated Sediments (ARCS) Program
Remediation Guidance Document. EPN905/R-94/003. U.S. Environmental Protection Agency
Great Lakes National Program Office, Chicago, Illinois.
U.S. EPA. 1994e. Considering Wetlands at CERCLA Sites. U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response. EPA 540/R-94/019. May.
U.S. EPA. 1 994f. Pilot-Scale Demonstration of Sediment Washing for the Treatment of Saginaw River
Sediment. Assessment and Remediation of Contaminated Sediments (ARCS) Program. EP A
905/R-4/0l9. July.
U.S. EPA. 1995a. Land Use on the CERCLA Remedy Selection Process. U.S. Environmental Protection
Agency, Office of Emergency and Remedial Response, Washington, DC. OSWER Directive
9355.7-04.
U.S. EPA. 1995b. Cleaning Up Contaminated Sediments: A Citizen's Guide. Assessment and
Remediation of Contaminated Sediment (ARCS) Program. U.S. Environmental Protection
Agency Great Lakes National Program Office, Chicago, Illinois. EPA 905/K-95/001. July.
U.S. EPA. 1996a. Soil Screening Guidance: User's Guide. U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response, Washington, DC. OSWER 9355.4-23, EPA
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540/R-96/0l8. July.
u.s. EPA 1996b. The Model Plan for Public Participation (developed by the National Environmental
Justice Advisory Council). Office of Environmental Justice. EPA 300/K-96/003. November.
u.s. EPA. 1996c. ECO Update on Ecotox Thresholds. U.S. Environmental Protection Agency Office of
Solid Waste and Emergency Response, Washington, DC. EPA 540/F-95/038. January.
Available at httj):/ /www.cpa.gov!supcrfundlrcsourccs!ccotox/indcx.htm .
U.S. EPA. 1996d. Superfund Removal Procedures, Response Management: Removal Action Start-up to
Close-out. U.S. Environmental Protection Agency, Office of Emergency and Remedial
Response, Washington, DC. OSWER Directive 9360.3-04.
U.S. EPA. 1996e. The National Sediment Quality Survey: a Report to Congress on the Extent and
Severity of Sediment Contamination in Surface Waters of the United States. Office of Science
and Technology, Washington, DC. EPA 823-D-96-002. July.
U. S. EP A. 1 996f. Estimating Contaminant Losses from Components of Remediation Alternatives for
Contaminated Sediments. Assessment and Remediation of Contaminated Sediment (ARCS)
Program. U.S. Environmental Protection Agency Great Lakes National Program Office, Chicago,
Illinois. EPA 905/R-96/001. March.
U.S. EPA. 1996g. Coordination between RCRA Corrective Action and Closure and CERCLA Site
Activities. U.S. Environmental Protection Agency Office of Solid Waste and Emergency
Response, Washington, DC. OSWER Directive 9200.0-25. September.
U.S. EPA. 1997a. CERCLA Coordination with Natural Resource Trustees. U.S. Environmental
Protection Agency, Office of Solid Waste and Emergency Response, Washington, DC. OSWER
Directive 9200.4-22A.
U.S. EPA. 1997b. Community Advisory Group Toolkit for EPA Staff. U.S. Environmental Protection
Agency, Office of Solid Waste and Emergency Response, Washington, DC. EPA 540/R-97/038.
U.S. EPA. 1997c. Rules of Thumb for Superfund Remedy Selection. U.S. Environmental Protection
Agency Office of Solid Waste and Emergency Response, Washington, DC. OSWER 9355.0-69,
EPA 540/R-97/013.
U.S. EPA. 1997d. Ecological Risk Assessment Guidance for Superfund: Process for Designing and
Conducting Ecological Risk Assessment. Interim Final. U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response, Washington, DC. EPA 540/R-97/006. June.
U.S. EPA. 1997e. Report on the Effects of the Hot Spot Dredging Operations, New Bedford Harbor
Superfund Site, New Bedford, Massachusetts. U.S. Environmental Protection Agency Region 1.
October.
U.S. EPA. 1 998a. EPA's Contaminated Sediment Management Strategy. U.S. Environmental Protection
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Agency Office of Water, Washington, DC. EPA 823/R-98/001. A fact sheet on this document is
available on the Internet at http://www.epa.gov/OST/cs/stratefs.html. The strategy is available on
the Internet at http://www.epa.gov/OSTics/stratndx.htmi.
U.S. EPA. 1 998b. The Plan to Enhance the Role of States and Tribes in the Superfund Program. U.S.
Environmental Protection Agency Office of Emergency and Remedial Response, Washington,
DC. OSWER Directive 9375.3-03P. EPA 540/R-98/012. March. Available at
htq):/ /WW\v. cpa. gov/supcrfund/statcs/suo1e/iIldex .htl11.
U.S. EPA. 1998c. Guidance for Conducting Fish and Wildlife Consumption Surveys. U.S.
Environmental Protection Agency Office of Water, Washington, DC. EPA 823/B-98/007.
November.
U.S. EPA. 1998d. Assessment and Remediation of Contaminated Sediments (ARCS) Program Guidance
for In-Situ Subaqueous Capping of Contaminated Sediments. Prepared for the Great Lakes
National Program Office, U.S. Environmental Protection Agency, Chicago, Illinois. EPA
905/B-96/004. Available on the Internet at http://'www.epa.gov/gIIJDo/scdimentliscmain.
U.S. EPA. 1999a. A Guide to Preparing Superfund Proposed Plans, Records of Decision, and Other
Remedy Selection Decision Documents. U.S. Environmental Protection Agency Office of Solid
Waste and Emergency Response, Washington, DC. EPA 540/R-98/031.
U.S. EPA. 1 999b. Ecological Risk Assessment and Risk Management Principles for Superfund Sites.
U.S. Environmental Protection Agency Office of Solid Waste and Emergency Response,
Washington, DC. OSWER Directive 9285.7-28P.
U.S. EPA. 1999c.. A Community Guide to Superfund Risk Assessment - What's it All about and How
Can You Help? U.S. Environmental Protection Agency Office of Solid Waste and Emergency
Response, Washington, DC. OSWER Directive 9285.7-30. EPA 540/K-99/003. December.
U.S. EPA. 1999d. Use of Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and
Underground Storage Tank Sites. U.S. Environmental Protection Agency Office of Solid Waste
and Emergency Response, Washington, DC. EPA 540/R-99/009. April.
U.S. EP A. 2000a. Guidance for the Data Quality Objectives Process. (EP A QNG-4). Office of
Environmental Information, Washington, DC. EPA 600/R-96/055. Also available on the Internet
at http://www .epa. goy/quality /qa.docs.html.
U.S. EPA. 2000b. Guidance for Assessing Chemical Contaminant Data for Use in Fish Advisories,
Volume 1, Fish Sampling and Analysis, Third Edition. Office of Water. EPA 823/B-00/007.
November.
U.S. EPA. 2000c. Soil Screening Guidance for Radionuclides: User's Guide. U.S. Environmental
Protection Agency, Office of Radiation and Indoor Air and Office of Solid Waste and Emergency
Response. OSWER 9355.4-16A; EPN540-R-00-007. October.
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U.S. EPA. 2000d. Peer Review Handbook, 2nd Edition. U.S. Environmental Protection Agency Science
Policy Council, Washington DC. EPA 100-B-00-001. December.
U.S. EPA. 2000e. Institutional Controls: A Site Manager's Guide to Identifying, Evaluating, and
Selecting Institutional Controls at Superfund and RCRA Corrective Action Cleanups. U.S.
Environmental Protection Agency Office of Solid Waste and Emergency Response, Washington,
DC. OSWER Directive 9355.0-7FS-P. EPA 540-F-00-005. September.
U.S. EPA. 2000f. Institutional Controls and Transfer of Real Property under CERCLA Section 120
(h)(3)(A), (B), or (C). Federal Facilities Restoration and Reuse Office, Washington, DC.
February. Available at: http://w.vw.epa.gov/swer/ftrr/guide/11ttn.
U.S. EPA. 2000g. Managing and Sampling and Analyzing Contaminants in Fish and Shellfish, Volume
1. U.S. Environmental Protection Agency Office of Water. EPA 823/B-00/008.
U.S. EPA. 200la. Draft Report on the Incidence and Severity of Sediment Contamination in Surface
Waters of the United States, National Sediment Quality Survey: Second Edition. U.S.
Environmental Protection Agency Office of Water, Washington, DC. EPA 823/F-0l/031.
December.
U.S. EPA. 200lb. Enhancing State and Tribal Role Directive. U.S. Environmental Protection Agency
Office of Emergency and Remedial Response, Washington, DC. OSWER Directive 9375.3-06P.
Available at http://w"..iw.epa.gov/superfund./states/strole/index.htm.
U.S. EPA. 200lc. Early and Meaningful Community Involvement. U.S. Environmental Protection
Agency Office of Emergency and Remedial Response, Washington, DC. OSWER Directive
9230.0-99. October.
U.S. EPA. 200ld. Incorporating Citizen Concerns into Superfund Decision-Making. U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response. OSWER
Directive 9230.0-18. January.
U.S. EPA. 200le. Forum on Managing Contaminated Sediments at Hazardous Waste Sites. U.S.
Environmental Protection Agency Office of Emergency and Remedial Response, Washington,
DC. Proceedings available at http://wwwepagov/superfund/new/sedfomm.htm.
U.S. EPA. 200lf. EPA Requirements for Quality Assurance Project Plans. U.S. Environmental.
Protection Agency Office of Environmental Information, Washington DC. EPA/240/B-0l/003.
Also available on the Internet at http://www.epa.gov/quality
U.S. EPA. 200lg. EPA ECO Update: The Role of Screening-Level Risk Assessments and Refming
Contaminants of Concern in Baseline Ecological Risk Assessments. U. S. Environmental
Protection Agency, Office of Solid Waste and Emergency Response. EPA 540/F-0l/014;
OSWER 9345.0-14. June.
U.S. EP A. 200lh. Natural Recovery of Persistent Organics in Contaminated Sediments at the Sangamo-
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Westonffwelvemile Creek/Lake Hartwell Superfund Site. Prepared by Batelle under contract to
U.S. Environmental Protection Agency, National Risk Management Research Laboratory,
Cincinnati, Ohio.
U.S. EPA 200li. Natural Recovery of Persistent Organics in Contaminated Sediments at the
Wykoff/Eagle Harbor Superfund Site. Prepared by Battelle under contract to U.S. Environmental
Protection Agency, National Risk Management Research Laboratory, Cincinnati, Ohio.
U.S. EPA. 200lj. Monitored Natural Attenuation: USEPA Research program - An EPA Science
Advisory Board Review. Environmental Engineering Committee of the EPA Science and
Advisory Board. EPA-SAB-EEC-01-004. May.
U.S. EPA. 2001k. Comprehensive Five-Year Review Guidance. U.S. Environmental Protection Agency
Office of Emergency and Remedial Response, Washington, DC. EP A 540/R-0l/007. June.
U.S. EPA. 20011. Methods for Colle'ction, Storage, and Manipulation of Sediments for Chemical and
Toxicological Analyses: Technical Manual. U.S. Environmental Protection Agency Office of
Water, Washington, DC. EPA 823/B-0l/002.
U.S. EPA. 2002a. Principles for Managing Contaminated Sediment Risks at Hazardous Waste Sites.
U.S. Environmental Protection Agency Office of Emergency and Remedial Response,
Washington, DC. OSWER Directive 9285.6-08. February.
U.S. EPA. 2002b. Role of Background in the CERCLA Cleanup Program. U.S. Environmental
Protection Agency Office of Solid Waste and Emergency Response, Washington, DC. OSWER
Directive 9285.6-07P. April 26.
U.S. EPA. 2002c. Guidance for Comparing Background and Chemical Concentrations in Soil for
CERCLA Sites, U.S. Environmental Protection Agency Office of Emergency and Remedial
Response. EPN540/R-0l/003 OSWER 9285.7-41 September 2002. Also available on the
Internet at httv://www.epa.gov/superfund.
U.S. EPA. 2003a. Update: National Listing ofFish and Wildlift Advisories (Fact Sheet). U.S.
Environmental Protection Agency, Office of Water. EPA-823-F-03-003. May.
U.S. EPA. 2003b. Superfund Community Involvement Toolkit. U.S. Environmental Protection Agency
Office of Emergency and Remedial Response, Washington, DC Available at
htto://www.epa.gov/superfund/tools.
U.S. EPA. 2003c. Guidance for Developing Ecological Soil Screening Levels (Eco-SSLs). U.S.
Environmental Protection Agency, Office of Solid Waste and Emergency Response. OSWER
Directive 9285.7-55. November.
U.S. EPA. 2004a. Updated Report on the Incidence and Severity of Sediment Contamination in Surface
Waters of the United States, National Sediment Quality Survey. U.S. Environmental Protection
Agency Office of Water, Washington, DC. .
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U.S. EPA. 2004b. OSRTI Sediment Team and NRRB Coordination and Large Sediment Sites. U.S.
Environmental Protection Agency, Office of Superfund Remediation and Technology Innovation.
OSWER Directive 9285.6-11. March.
U.S. EP A. 2004c. Evaluation of Contaminated Sediment Fate and Transport Models, Final Report,
Office of Research and Development, National Exposure Laboratory, Athens, Georgia, 141 pp.
U.S. EPA. 2004d. Evaluation of Chemical Bioaccumulation Models of Aquatic Ecosystems, Final
Report, Office of Research and Development, National Exposure Research laboratory, Athens,
Georgia, 122 pp.
U.S. EPA. 2004e. Guidance for monitoring at hazardous waste sites: Framework for monitoring plan
development and implementation. OSWER Directive 9355.4-28, January.
U.S. EPA and USACE. 1977. Environmental Effects of Dredging. Technical Note EEDP-09-3.
U.S. EPA and USACE. 1992. Evaluation of Dredged Material Proposed for Ocean Disposal: Testing
Manual. U.S. Environmental Protection Agency Office of Marine and Estuarine Protection,
Washington, DC, and U.S. Army Corps of Engineers, Washington, DC. EPA 503/8-91/001.
February.
U.S. EPA and USACE. 1998. Evaluation of Dredged Material Proposed for Discharge in Waters of the
U.S. - Inland Testing Manual. U.S. Environmental Protection Agency Office of Water,
Washington, DC, and U.S. Army Corps of Engineers, Washington, DC. EPA 823/B-98/004.
U.S. EPA and USACE. 2000. A Guide to Developing and Documenting Cost Estimates During the
Feasibility Study. EPA 540-R-00-002. U.S. Army Corps of Engineers Hazardous Toxic, and
Radioactive Waste Center of Expertise, Omaha, Nebraska and U.S. Environmental Protection
Agency Office of Emergency and Remedial Response, Washington, DC. July. Available at:
www.cpa.gov/ocrmagc/superfundlrcsomccslremcdv/tinaldoc.pdf.
USGS. 2000. A mass balance approach for assessing PCB movement during remediation of a PCB-
contaminated deposit on the Fox River, Wisconsin, USGS Water-Resources Investigations Report
00-4245, December 2000.
U.S. Naval Facilities Engineering Command. 2003. Implementation Guide for Assessing and Managing
Contaminated Sediment at Navy Facilities. UG-2053-ENV. March.
Van Oostrum, R.W. 1992. Dredging of contaminated sediment between pre-dredging survey and
treatment. In: Proc. of the International Symposium on Environmental Dredging, Buffalo, New
York.
Wardlaw. 1993. Personal communication.
Warner, G.F. 1977. On the Shapes of Passive Suspension-Feeders. In Keegan, B.F., P.O.Ceidigh, and
PJ.S. Boaden, eds. Biology of Benthic Organisms. New York.
January 2005 Draft, Peer Review Document
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Wiles, C.C., and E. Barth. 1992. "Solidification/Stabilization: Is it Always Appropriate?" Stabilization
and Solidification of Hazardous, Radioactive, and Mixed Wastes, 2nd Volume, ASTM STP 1123,
T.M. Gilliam and C.C. Wiles, Eds. American Society for Testing and Materials, Philadelphia, pp.
18-32.
Winter, T.C., 2002, Subaqueous Capping and Natural Recovery: Understanding the Hydrogeologic
Setting at Contaminated Sediment Sites, DOER Technical Notes Collection. ERDC TN-DOER-
C26, U.S. Army Corps Engineer Research and Development Center, Vicksburg, Mississippi
www wes.anny.miVelldots/doer
Zaidi, B. R., G. Stucki, and M. Alexander. 1988. Low chemical concentrations and pH as factors limiting
the success of inoculation to enhance biodegradation. Environ. Toxicol. Chern. 7: 143-151.
Zappi, P.A., and D.F. Hayes. 1991. Innovative Technologies for Dredging Contaminated Sediments.
Miscellaneous Paper EL-91-20. U.S. Army Corps of Engineers, Waterways Experiment Station,
Vicksburg, Mississippi.
Zar, J.H. 1999. Biostatistica1 Ana1vsis Fourth Edition, Prentice Hall, Upper Saddle River, New Jersey.
January 2005 Draft, Peer Review Docutni!nt
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CONTAMINATED SEDIMENT REMEDIATION
GUIDANCE FOR HAZARDOUS WASTE SITES:
APPENDIX A: PRINCIPLES FOR MANAGING
CONTAMINATED SEDIMENT RISKS AT
HAZARDOUS WASTE SITES
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AppendixA: 11 Principles
.,\~"o 91"-4~
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
Feb. 12, 2002
OFFICE OF
SOLID WASTE AND EMERGENCY
RESPONSE
OSWER Directive 9285.6-08
MEMORANDUM
SUBJECT:
Principles for Managing Contaminated Sediment Risks at Hazardous Waste Sites
FROM:
Marianne Lamont Horinko Is! Marianne Lanwnt Horinko
Assistant Administrator
TO:
Superfund National Policy Managers, Regions 1 - 10
RCRA Senior Policy Advisors, Regions 1 - 10
I.
PURPOSE
This guidance will help EP A site managers make scientifically sound and nationally
consistent risk management decisions at contaminated sediment sites. It presents 11 risk
management principles that Remedial Project Managers (RPMs), On-Scene Coordinators
(OSCs), and RCRA Corrective Action project managers should carefully consider when
planning and conducting site investigations, involving the affected parties, and selecting and
implementing a response.
This guidance recommends that EP A site managers make risk-based site decisions using
an iterative decision process, as appropriate, that evaluates the short-term and long-term risks of
all potential cleanup alternatives consistent with the National Oil and Hazardous Substances
Pollution Contingency Plan's (NCP's) nine remedy selection criteria (40 CFR Part 300.430).
EP A site managers are also encouraged to consider the societal and cultural impacts of existing
sediment contamination and of potential remedies through meaningful involvement of affected
stakeholders.
This guidance also responds in part to the recommendations contained in the Nati~nal
Research Council (NRC) report discussed below.
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Appendix A: 11 Principles
II.
BACKGROUND
On March 26, 2001, the NRC published a report entitled A Risk Management Strategy for
PCB-Contaminated Sediments. Although the NRC report focuses primarily on assessment and
remediation of PCB-contaminated sediments, much of the information in that report is applicable
to other contaminants. Site managers are encouraged to read the NRC report, which may be
found at http://www.nrc.edu.
In addition to developing these principles, OSWER, in coordination with other EP A
offices (Office of Research and Development, Office of Water, and others) and other federal
agencies (Department of Defense/U.S. Army Corps of Engineers, Department of
Commerce/National Oceanic and Atmospheric Administration, Department of the Interior/U.S.
Fish and Wildlife Service, and others) is developing a separate guidance, Contaminated
Sediment Remediation Guidance for Hazardous Waste Sites (Sediment Guidance). The
Sediment Guidance will provide more detailed technical guidance on the process that Superfund
and RCRA project managers should use to evaluate cleanup alternatives at contaminated
sediment sites.
While this directive applies to all contaminants at sediment sites addressed under
CERCLA or RCRA, its implementation at particular sites should be tailored to the size and
complexity of the site, to the magnitude of site risks, and to the type of action contemplated.
These principles can be applied within the framework of EPA's existing statutory and regulatory
requirements.
III.
RISK MANAGEMENT PRINCIPLES
1.
Control Sources Early.
I As early in the process as possible, site managers should try to identify all direct and
indirect continuing sources of significant contamination to the sediments under investigation.
These sources might include discharges from industries or sewage treatment plants, spills,
precipitation runoff, erosion of contaminated soil from stream banks or adjacent land,
contaminated groundwater and non-aqueous phase liquid contributions, discharges from storm
water and combined sewer outfalls, upstream contri~utions, and air deposition.
Next, site managers should assess which continuing sources can be controlled and by
what mechanisms. It may be helpful to prioritize sources according to their relative
contributions to site risks. In the identification and assessment process, site managers should
solicit.assistance from those with relevant information, including regional Water, Air, and PCB
Programs (where applicable); state agencies (especially those responsible for setting Total
Maximum Daily Loads (TMDLs) and those that issue National Pollutant Discharge Elimination
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AppendixA: 11 Principles
System (NPDES) permits); and all Natural Resource Trustees. Local agencies and stakeholders
may also be of assistance in assessing which sources can be controlled.
Site managers should evaluate the potential for future recontamination of sediments when
selecting a response action. If a site includes a source that could result in significant
recontamination, source control measures wi11likely be necessary as part of that response action.
However, where EP A believes that the source can be controlled, or where sediment remediation
will have benefits to human health and/or the environment after considering the risks caused by
the ongoing source, it may be appropriate for the Agency to select a response action for the
sediments prior to completing all source control actions. This is consistent with principle #5
below, which indicates that it may be necessary to take phased or interim actions (e.g., removal
of a hot spot that is highly susceptible to downstream movement or dispersion of contaminants)
to prevent or address environmental impacts or to control human exposures, even if source
control actions have not been undertaken or completed.
2.
Involve the Community Early and Often.
Contaminated sediment sites often involve difficult technical and social issues. As such,
it is especially important that a project manager ensure early and meaningful community
involvement by providing community members with the technical information needed for their
informed participation. Meaningful community involvement is a critical component of the site
characterization, risk assessment, remedy evaluation, remedy selection, and remedy
implementation processes. Community involvement enables EP A to obtain site information that
may be important in identifying potential human and ecological exposures, as well as in
understanding the societal and cultural impacts of the contamination and of the potential
response options. The NRC report (p. 249) "recommends that increased efforts be made to
provide the affected parties with the same information that is to be used by the decision-makers
and to include, to the extent possible, all affected parties in the entire decision-making process at
a contaminated site. In addition, such information should be made available in such a manner
that allows adequate time for evaluation and comment on the information by all parties."
Through Technical Assistance Grants and other mechanisms, project managers can provide the
community with the tools and information necessary for meaningful participation, ensuring their
early and continued involvement in the cleanup process.
Although the Agency has the responsibility to make the final cleanup decision at
CERCLA and RCRA sites, early and frequent community involvement facilitates acceptance of
Agency decisions, even at sites where there may be disagreement among members of the
community on the most appropriate remedy.
Site managers and community involvement coordinators should take into consideration
the following six practices, which were recently presented in OSWER Directive 9230.0-99 Early
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AppendixA: 11 Principles
and Meaningful Community Involvement (October 12, 2001). This directive also includes a list
of other useful resources and is available at http://www.epa.gov/superfund/pubs.htm.
(1) Energize the community involvement plan.
(2) Provide early, proactive community support.
(3) Get the community more involved in the risk assessment.
(4) Seek early community input on the scope of the remedial investigation/feasibility
study (RIfFS).
(5) Encourage community involvement in identification of future land use.
(6) Do more to involve communities during removals.
Coordinate with States, Local Governments, Tribes, and Natural Resource
Trustees.
Site managers should communicate and coordinate early with states, local governments,
tribes, and all Natural Resource Trustees. By doing so, they will help ensure that the most
relevant information is considered in designing site studies, and that state, local, tribal, and
trustee viewpoints are considered in the remedy selection process. For sites that include
waterbodies where TMDLs are being or have been developed, it is especially important to
coordinate site investigations and monitoring or modeling studies with the state and with EPA's
water program. In addition, sharing information early with all interested parties often leads to
quicker and more efficient protection of human health and the environment through a
coordinated cleanup approach.
3.
Superfund's statuto!)' mandate is to ensure that response actions will be protective of
human health and the environment. EP A recognizes, however, that in addition to EP A's
response action(s), restoration activities by the Natural Resource Trustees may be needed. It is
important that Superfund site managers and the Trustees coordinate both the EP A investigations
of risk and the Trustee investigations of resource injuries in order to most efficiently use federal
and state resources and to avoid duplicative efforts.
Additional information on coordinating with Trustees may be found in OSWER Directive
9200.4-22A CERCLA Coordination with Natural Resource Trustees (July 1997), in the 1992
ECO Update The Role of Natural Resource Trustees in the Superfund Process
http://www.epa.gov/supeIfund/programs/risk/tooleco.htm). and in the 1999 OSWER Directive
9285.7-28 P Ecological Risk Assessment and Risk Management Principles for Superfund Sites
(also available at the above web site). Additional information on coordinating with states and
tribes can be found in OSWER Directive 9375.3-03P The Plan to Enhance the Role of States and
Tribes in the Superfund Program (http://www.epa.gov/superfundistates/strole/index.htm).
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Appendix A: 11 Principles
4.
Develop and Refine a Conceptual Site Model that Considers Sediment Stability.
A conceptual site model should identify all known and suspected sources of
contamination, the types of contaminants and affected media, existing and potential exposure
pathways, and the known or potential human and ecological receptors that may be threatened.
This information is frequently summarized in pictorial or graphical form, backed up by site-
specific data. The conceptual site model should be prepared early and used to guide site
investigations and decision-making. However, it should be updated periodically whenever new
information becomes available, and EPA's understanding of the site problems increases. In
addition, it frequently can serve as the centerpiece for communication among all stakeholders.
A conceptual site model is especially important at sediment sites because the
interrelationship of soil, surface and groundwater, sediment, and ecological and human receptors
is often complex. In addition, sediments may be subject to erosion or transport by natural or
man-made disturbances such as floods or engineering changes in a waterway. Because
sediments may experience temporal, physical, and chemical changes, it is especially important to
understand what contaminants are currently available to humans and wildlife, and whether this is
likely to change in the future under various scenarios. The risk assessor and project manager, as
well as other members of the site team, should communicate early and often to ensure that they
share a common understanding of the site and the basis for the present and future risks. The May
1998 EP A Guidelines for Ecological Risk Assessment (Federal Register 63(93) 26846-26924,
http://www.epa.gov/superfundlprograms/risk/tooleco.htm). the 1997 Superfund Guidance
Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting
Ecological Risk Assessments (EPA 540-R-97-006, also available at the above web site), and the
1989 Risk Assessment Guidancefor Superfund (RAGS), Volume 1, Part A (EPA 540-1-89-002,
http://www.epa.gov/superfundlprograms/risk/ragsa) provide guidance on developing conceptual
site models.
5.
Use an Iterative Approach in a Risk-Based Framework.
The NRC report (p. 52) recommends the use of a risk-based framework based on the one
developed by the Presidential/Congressional Commission on Risk Assessment and Risk
Management (PCCRARM, 1997, Framework for Environmental Health Risk Management, Vol.
1, as cited by NRC 2001). However, as recognized by the NRC (p. 60): "The framework is
intended to supplement, not supplant, the CERCLA remedial process mandated by law for
Superfund sites."
Although there is no universally accepted, well-defined risk-based framework or strategy
for remedy evaluation at sediment sites, there is wide-spread agreement that risk assessment
should playa critical role in evaluating options for sediment remediation. The Superfund
program uses a flexible, risk-based framework as part of the CERCLA and NCP process to
adequately characterize ecological and human health site risks. The guidances used by the
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AppendixA: 11 Principles
RCRA Corrective Action program (http://www.epa.gov/correctiveactionJresource/guidance) also
recommend a flexible risk-based approach to selecting response actions appropriate for the site.
EP A encourages the use of an iterative approach, especially at complex contaminated
sediment sites. As used here, an iterative approach is defined broadly to include approaches
which incorporate testing of hypotheses and conclusions and foster re-evaluation of site
assumptions as new information is gathered. For example, an iterative approach might include
pilot testing to determine the effectiveness of various remedial technologies at a site. As noted
in the NRC report (p. 66): "Each iteration might provide additional certainty and information to
support further risk-management decisions, or it might require a course correction."
An iterative approach may also incorporate the use of phased, early, or interim actions.
At complex sediment sites, site managers should consider the benefits of phasing the
remediation. At some sites, an early action may be needed to quickly reduce risks or to control
the ongoing spread of contamination. In some cases, it may be appropriate to take an interim
action to control a source, or remove or cap a hot spot, followed by a period of monitoring in
order to evaluate the effectiveness of these interim actions before addressing less contaminated
areas.
The NRC report makes an important point when it notes (p. 256): ''The committee
cautions that the use of the framework or other risk-management approach should not be used to
delay a decision at a site if sufficient information is available to make an informed decision.
Particularly in situations in which there are immediate risks to human health or the ecosystem,
waiting until more information is gathered might result in more harm than making a preliminary
decision in the absence of a complete set of information. The committee emphasizes that a
'wait-and-see' or 'do-nothing' approach might result in additional or different risks at a site."
6.
Carefully Evaluate the Assumptions and Uncertainties Associated with Site
Characterization Data and Site Models.
The uncertainties and limitations of site characterization data, and qualitative or
quantitative models (e.g., hydrodynamic, sediment stability, contaminant fate and transport, or
food-chain models) used to extrapolate site data to future conditions should be carefully
evaluated and described. Due to the complex nature of many large sediment sites, a quantitative
model is often used to help estimate and understand the current and future risks at the site and to
predict the efficacy of various remedial alternatives. The amount of site-specific data required
and the complexity of models used to support site decisions should depend on the complexity of
the site and the significance of the decision (e.g., level of risk, response cost, community
interest). All new models and the calibration of models at large or complex sites should be peer-
reviewed consistent with the Agency's peer review process as described in its Peer Review
Handbook (EP A lOO-B-OO-OO 1, http://v.'ww.epa.gov/ORD/spc/2peerrev.htm).
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AppendixA: 11 Principles
Site managers should clearly describe the basis for all models used and their
uncertainties when using the predicted results to make a site decision. As recognized by the
NRC report (p. 65), however, "Management decisions must be made, even when information is
imperfect. There are uncertainties associated with every decision that need to be weighed,
evaluated, and communicated to affected parties. Imperfect knowledge must not become an
excuse for not making a d'ecision."
7.
Select Site-specific, Project-specific, and Sediment-specific Risk Management
Approaches that will Achieve Risk-based Goals.
EP A's policy has been and continues to be that there is no presumptive remedy for any
contaminated sediment site, regardless of the contaminant or level of risk. This is consistent
with the NRC report's statement (p. 243) that ''There is no presumption of a preferred or default
risk-management option that is applicable to all PCB-contaminated-sediment sites." At
Superfund sites, for example, the most appropriate remedy should be chosen after considering
. site-specific data and the NCP's nine remedy selection criteria. All remedies that may
potentially meet the removal or remedial action objectives (e.g., dredging or excavation, in-situ
capping, in-situ treatment, monitored natural recovery) should be evaluated prior to selecting the
remedy. This evaluation should be conducted on a comparable basis, considering all
components of the remedies, the temporal and spatial aspects of the sites, and the overall risk
reduction potentially achieved under each option.
At many sites, a combination of options will be the most effective way to manage the
risk. For example, at some sites, the most appropriate remedy may be to dredge high
concentrations of persistent and bioaccumulative contaminants such as PCBs or DOT, to cap
areas where dredging is not practicable or cost-effective, and then to allow natural recovery
processes to achieve further recovery in net depositional areas that are less contaminated.
8.
Ensure that Sediment Cleanup Levels are Clearly Tied to Risk Management Goals.
Sediment cleanup levels have often been used as surrogates for actual remediation goals
(e.g., fish tissue concentrations. or other measurable indicators of exposure relating to levels of
acceptable risk). While it is generally more practical to use measures such as contaminant
concentrations in sediment to identify areas to be remediated, other measures should be used to
ensure that human health and/or ecological risk reduction goals are being met. Such measures
may include direct measurements of indigenous fish tissue concentrations, estimates of wildlife
reproduction, benthic macroinvertebrate indices, or other "effects endpoints" as identified in the
baseline risk assessment.
As noted in the NRC report (p. 123), "The use of measured concentrations of PCBs in
fish is suggested as the most relevant means of measuring exposures of receptors to PCBs in
contaminated sediments." For other contaminants, other measures may be more appropriate.
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Appendix A: 11 Principles
For many sites, achieving remediation goals, especially for bioaccumulative contaminants in
biota, may take many years. Site monitoring data and new scientific information should be
considered in future reviews of the site (e.g., the Superfund five-year review) to ensure that the
remedy remains protective of human health and the environment.
9.
Maximize the Effectiveness of Institutional Controls and Recognize their
Limitations.
Institutional controls, such as fish consumption advisories and waterway use restrictions,
are often used as a component of remedial decisions at sediment sites to limit human exposures
and to prevent further spreading of contamination until remedial action objectives are met.
While these controls can be an important component of a sediment remedy, site managers should
recognize that they may not be very effective in eliminating or significantly reducing all
exposures. If fish consumption advisories are relied upon to limit human exposures, it is very
important to have public education programs in place. For other types of institutional controls,
other types of compliance assistance programs may also be needed (e.g., state/local govemment
coordination). Site managers should also recognize that institutional controls seldom limit
ecological exposures. Ifmonitoring data or other site information indicates that institutional
controls are not effective, additional actions may be necessary.
10.
Design Remedies to Minimize Short-term Risks while Achieving Long-term
Protection.
The NRC report notes (p. 53) that: "Any decision regarding the specific choice of a risk
management strategy for a contaminated sediment site must be based on careful consideration of
the advantages and disadvantages of available options and a balancing of the various risks, costs,
and benefits associated with each option." Sediment cleanups should be designed to minimize
short-term impacts to the extent practicable, even though some increases in short-term risk may
be necessary in order to achieve a long-lasting solution that is protective. For example, the long-
term benefits of removing or capping sediments containing persistent and bioaccumulative
contaminants often outweigh the additional short-term impacts on the already-affected biota.
In addition to considering the impacts of each alternative on human health and ecological
risks, the short-term and long-term impacts of each alternative on societal and cultural practices
should be identified and considered, as appropriate. For example, these impacts might include
effects on recreational uses of the waterbody, road traffic, noise and air pollution, commercial
fishing, or disruption of way of life for tribes. At some sites, a comparative analysis of impacts
such as these may be useful in order to fully assess and balance the tradeoffs associated with
each alternative.
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AppendixA: 11 Principles
11.
Monitor During and After Sediment Remediation to Assess and Document Remedy
Effectiveness.
A physical, chemical, and/or biological monitoring program should be established for
sediment sites in order to determine if short-term and long-term health and ecological risks are
being adequately mitigated at the site and to evaluate how well all remedial action objectives are
being met. Monitoring should normally be conducted during remedy implementation and as
long as necessary thereafter to ensure that all sediment risks have been adequately managed.
Baseline data needed for interpretation of the monitoring data should be collected during the
remedial investigation.
Depending on the risk management approach selected, monitoring should be conducted
during implementation in order to determine whether the action meets design requirements and
sediment cleanup levels, and to assess the nature and extent of any short-term impacts of remedy
implementation. This information can also be used to modify construction activities to assure
that remediation is proceeding in a safe and effective manner. Long-term monitoring of
indicators such as contaminant concentration reductions in fish tissue should be designed to
determine the success of a remedy in meeting broader remedial action objectives. Monitoring is
generally needed to verify the continued long-term effectiveness of any remedy in protecting
human health and the environment and, at some sites, to verify the continuing performance and
structural integrity of barriers to contaminant transport.
IV.
IMPLEMENTATION
EP A RPMs, OSCs, and RCRA Corrective Action project managers should immediately
begin to use this guidance at all sites where the risks from contaminated sediment are being
investigated. EP A expects that Federal facility responses conducted under CERCLA or RCRA
will also be consistent with this directive. This consultation process does not apply to Time-
Critical or emergency removal actions or to sites with only sediment-like materials in wastewater
lagoons, tanks, storage or containment facilities, or drainage ditches.
Consultation Process for CERCLA Sites
To help ensure that Regional site managers appropriately consider these principles before
site-specific risk management decisions are made, this directive establishes a two-tiered
consultation procedure that will apply to most contaminated sediment sites. The consultation
process applies to all proposed or listed NPL sites where EP A will sign or concur on the ROD,
all Non- Time-Critical removal actions where EP A will sign or concur on the Action
Memorandum, and all "NPL-equivalent" sites where there is or will be an EP A-enforceable
agreement in place.
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AppendixA: 11 Principles
Tier 1 Process
Where the sediment action(s) for the entire site will address more than 10,000 cubic
yards or five acres of contaminated sediment, Superfund RPMs and OSCs should consult with
their appropriate Office of Emergency and Remedial Response (OERR) Regional Coordinator at
least 30 days before issuing for public comment a Proposed Plan for a remedial action or an
Engineering Evaluation/Cost Analysis (EE/CA) for a Non-Time-Critical removal action.
This consultation entails the submission of the draft proposed plan or draft EE/CA, a
written discussion of how the above 11 principles were considered, and basic site information
that will assist OERR in tracking significant sediment sites. If the project manager has not
received a response from OERR within two weeks, he or she may assume no further information
is needed at this time. EP A believes that this process will help promote nationally consistent
approaches to evaluate, select and implement protective, scientifically sound, and cost-effective
remedies.
Tier 2 Process
.
This directive also establishes a new technical advisory group (Contaminated Sediments
Technical Advisory Group-CST AG) that will monitor the progress of and provide advice
regarding a small number of large, complex, or controversial contaminated sediment Superfund
sites. The group will be comprised often Regional staff and approximately five staff from
OSWER, OW, and ORD. For most sites, the group will meet with the site manager and the site
team several times throughout the site investigation, response selection, and action
implementation processes. For new NPL sites, the group will normally meet within one year
after proposed listing. It is anticipated that for most sites, the group will meet annually until the
ROD is signed and thereafter as needed until all remedial action objectives have been met. The
specific areas of assistance or specific documents to be reviewed will be decided by the group on
a case-by-case basis in consultation with the site team. For selected sites with an on-going RIfFS
or EE/CA, the group will be briefed by the site manager some time in 2002 or 2003. Reviews at
sites with remedies also subject to National Remedy Review Board (NRRB) review will be
coordinated with the NRRB in order to eliminate the need for a separate sediment group review
at this stage in the process.
Consultation Process for RCRA Corrective Action Facilities
Generally, for EP A-lead RCRA Corrective Action facilities where a sediment response
action is planned, a two-tiered consultation process will also be used. Where the sediment
action(s) for the entire site will address more than 10,000 cubic yards or five acres of
contaminated sediment, project managers should consult with the Office of Solid Waste's
Corrective Action Branch at least 30 days before issuing a proposed action for public comment.
This consultation entails the submission of a written discussion of how the above 11 principles
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Appendix A: 11 Principles
were considered, and basic site information that will assist OSW in tracking significant sediment
sites.
If the project manager has not received a response from OSW within two weeks, he or
she may assume no further information is needed. States are also encouraged to follow these
procedures. For particularly large, complex, or controversial sites, OSW will likely call on the
technical advisory group discussed above.
EPA also recommends that both state and EPA project managers working on sediment
contamination associated with Corrective Action facilities consult with their colleagues in both
RCRA and Superfund to promote consistent and effective cleanups. EP A believes this
consultation would be particularly important for the larger-scale sediment cleanups mentioned
above.
EP A may update this guidance as more information becomes available on topics such as:
the effectiveness of various sediment response alternatives, new methods to evaluate risks, or
new methods for characterizing sediment contamination. For additional information on this
guidance, please contact the OERR Sediments Team Leader (Stephen Ells at 703 603-8822) or
the OSW Corrective Action Programs Branch Chief (Tricia Buzzell at 703 308-8632).
NonCE: This document provides guidance to EP A Regions concerning how the Agency
intends to exercise its discretion in implementing one aspect of the CERCLA and RCRA remedy
selection process. This guidance is designed to implement national policy on these issues. Some
of the statutory provisions described in this document contain legally binding requirements.
However, this document does not substitute for those provisions or regulations, nor is it a
regulation itself. Thus it cannot impose legally binding requirements on EP A, states, or the
regulated community, and may not apply to a particular situation based upon the circumstances.
Any decisions regarding a particular situation will be made based on the statutes and regulations,
and EP A decision-makers retain the discretion to adopt approaches on a case-by-case basis that
differ from this guidance where appropriate. Interested parties are free to raise questions and
objections about the substance of this guidance and the appropriateness of the application of this
guidance to a particular situation, and the Agency welcomes public input on this document at
any time. EP A may change this guidance in the future.
cc:
Michael H. Shapiro
Stephen D. Luftig
Larry Reed
Elizabeth Cotsworth
Jim Woolford
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AppendixA: 11 Principles
Jeff Josephson, Superfund Lead Region Coordinator, USEP A Region 2
Carl Daly, RCRA Lead Region Coordinator, US EP A Region 8
Peter Grevatt
NARPM Co-Chairs
OERR Records Manager, IMC 5202G
OERR Documents Coordinator, HOSC 5202G
RCRA Key Contacts, Regions 1 - 10
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