United States Office of CERI-9M9
Environmental Protect! Research and Development May 1991
Agency Cincinnati Ohio 45268
x>EPA
Contaminated
Sediments Seminar
Speaker Slide Copies
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CERI-91-19
May 1991
CONTAMINATED SEDIMENTS SEMINAR
Speaker Slide Copies
Summer 1991
Printed on Recycled Paper
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Notice
The U.S. Environmental Protection Agency (EPA) strives to provide accurate, complete and useful information.
However, neither EPA nor any person contributing to the preparation of this document makes any warranty,
expressed or implied, with respect to the usefulness or effectiveness of any information, method, or process
disclosed in this material. Nor does EPA assume any liability for the use of, or for damages arising from the use
of, any information, methods, or process disclosed in this document.
Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
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Table of Contents
Page
Overview of Contaminant Problem and Remediation Approach for Uncontrolled Hazardous Waste Sites ....1-1
Physical/Chemical Characteristics of Sediments 2-1
Overview of Test Methods and Criteria for Evaluating Contaminated Sediments.... 3-1
Sampling Methods for Determining Extent of Contamination 4-1
Modeling of Contaminated Sediment Movement 5-1
Removal and Transport Processes 6-1
Dewatering and Other Pre-treatment Processes 7-1
Technology Screening and Integration Processes '. 8-1
Extraction Technologies 9-1
Thermal Technologies (Incineration, LT Desorption, Recovery Systems) 10-1
Bioremediation 11-1
Solidification/Stabilization 12-1
Residual Disposal Methods (Confined Disposal Facilities, Capping, and Landfills) 13-1
in
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Overview of Contaminant Problem
and Remediation Approach
for Uncontrolled Hazardous Waste Sites
Dr. Carol Bass
U.S. Environmental Protection Agency
Washington, D.C.
Contaminated sediments may pose risks to both human and environmental health. Such sediments may be found
in large sites, such as the harbors of industrialized ports. However, they are also frequently found in smaller sites,
such as streams, lakes, bayous, and rivers.
The Office of Emergency and Remedial Response (OERR) analyzed 486 Records of Decision (RODs) using the
ROD Information Directory to obtain a list of Superfund sites identifying contaminated sediments as a human or
ecosystem health concern. This list was subsequently evaluated for specific information regarding sediment
contamination, response, action, methods, and performance goals.
Twenty percent of these RODs, from 69 sites, addressed potential sediment contamination. Of these 69 sites,
remediation was selected for 49; no remediation was selected for 20 (i.e., no excavation, treatment, or disposal).
Of the 49 sites where remediation was selected, 30 chose excavation with treatment as the remedy. The remaining
19 sites utilized excavation followed by disposal (containment).
Additional evaluations focused on the prevalence of contaminants of concern at all 69 sites. Of the 67 sites where
specific sediment contaminants of concern were provided, 45 (67%) listed metals as contaminants of concern. The
second most prevalent contaminant group was volatile organic compounds (VOCs). Other organic compounds
frequently identified were polynuclear aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs).
Cleanup goals varied between sites due to site specific applications of ARARs and risk assessment.
1-1
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EXTENT OF CONTAMINATED
SEDIMENT PROBLEM
24% of National Priorities List Sites
were found to have potentially contaminated
sediments
20% of the Record of Decisions in the ROD
Information Director addressed potential
sediment contamination
RODs: 69 SITES WITH
CONTAMINATED SEDIMENTS
Remediation Selected for 49 Sites
No Remediation Selected for 20 Sites
1-2
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RODs: 49 REMEDIATED SITES
30 Chose Excavation with Treatment
13 incineration
10 solidification
2 biodegradation
1 dechlorination
1 in situ vitrification
3 to be determined
RODs: 49 REMEDIATED SITES
19 Chose Excavation
Followed by Disposal
10 off-site disposal
7 on-site disposal
2 on-site storage
REASONS FOR NO REMEDIATION
DECISIONS (20 ROD Sites)
Contaminated sediments had been isolated (9 sites)
Sediment monitoring (3 sites)
Sediment treatment deferred (2 sites)
No correlation between off-site and on-site contaminants
(2 sites)
Surface water diverted (2 sites)
Fund balancing waiver invoked (1 site)
Remediation a greater risk (1 site)
1-3
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METAL CONTAMINANTS OF CONCERN
(67 ROD Sites)
lead (26 sites/39%)
chromium (18 sites/27%)
cadmium (15 sites/22%)
arsenic (13 sites/19%)
zinc (13 sites/19%)
all metals (45 sites/67%)
ORGANIC CONTAMINANTS
OF CONCERN
(67 ROD Sites)
VOCs (31 sites/46%)
PAHs (24 sites/36%)
PCBs (18 sites/27%)
IDENTIFIED RISK FACTORS
(69 ROD Sites)
Threat to Human Health
Extent of Sediment Contamination
Toxicity of Contaminants
Mobility of Contaminants
Increased Risk Posed by Disruption of Contaminated Sediments
Threat to Wildlife and Aquatic Life
1-4
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Physical/Chemical Characteristics of Sediments
Dr. Robert P. Gambrell and Dr. William H. Patrick, Jr.
Laboratory for Wetland Soils and Sediments
Louisiana State University
Baton Rouge, Louisiana
Sediment is the material that settles to the bottom of any body of water. Its primary components are interstitial water
and soil particles. Interstitial watercan comprise up to 90 percent of the total volume of unconsolidated, top sediment
horizons and close to 50 percent of deeper, more compacted sediments. Soil particles found in sediments are
derived from surface erosion of soils in the watershed, bank erosion, and redistribution of the bed load in waterways.
Sediments vary widely in particle size distribution and are generally finer in texture than their source soils.
Segregation of particle size occurs within the water body as a result of currents such that the smaller particles
accumulate in quiescent zones and coarser particles are found where the current is greater. Organic matter, another
important component of sediment, may range from near zero to greater than 10 percent of the sed iment solid phase.
Minor (but not necessarily unimportant) components of sediments include shells and other animal parts, plant
detritus, sewage, and industrial wastes such as metals, other inorganic chemicals, synthetic organic compounds,
and oil and grease.
Sediments are a very important part of aquatic ecosystems and in and of themselves should not be considered a
problem. Sediments can become a problem when contaminated. Sediments are considered contaminated when
anthropogenic sources of pollution exist in high enough concentrations and are sufficiently available to affect human
and/or ecosystem health.
Contaminants enter the water body from point sources (such as municipal and industrial effluents), non-point
sources (such as agricultural and urban runoff), and other sources (such as spills, leaks, and dumping of wastes).
Common contaminants of concern include halogenated hydrocarbons (PCBs, dioxins, many pesticides, etc.),
polycyclic aromatic hydrocarbons (PAHs such as naphthalene, pyrenes, etc.), and other organics (such as
benzene), as well as metals (including iron, manganese, lead, cadmium, and mercury).
The physical and chemical characteristics of sediments exert a great deal of influence upon the bioavailability of
sediment contaminants. These characteristics vary greatly from site to site. As a result, site characteristics should
impact remediation decisions.
The primary physical characteristic is texture, or the distribution of sand, silt, and clay sized particles. Generally,
sandy sediments have little attraction for either toxic metals or synthetic organics (pesticides and industrial
organics). Fine textured sediments such as silt and clay have a much greateraff inity for all classes of contaminants.
Another very important physical property is the organic matter content, including humic material. Humic material
is important in two respects: the humic material greatly increases the affinity of sediments for metals and nonpolar
organic contaminants and it serves as an energy source for sediment microbial populations. Measurement of
sediment in situ water content is also usually important to remediation decisions.
The chemical properties of sediments also greatly affect the mobility and biological availability of contaminants.
Important chemical analyses include pH, oxidation-reduction, salinity conditions, and sulf ide content as well as the
amount and type of cations and anions, and the amount of potentially reactive iron and manganese.
Contaminants may be mobilized or immobilized as the physical and chemical environment of the sediment changes
during remediation operations. For example, metal carbonates may release their metals if the pH is reduced during
removal and treatment. Understanding the influence of the sediment chemical environment, and controlling
changes in this environment, are important to the selection of disposal alternatives for contaminated sediments.
2-1
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SEDIMENT:
Major
Components:
Other Important
Components:
Animals
and Detritus:
Contaminants,
if Present:
Material that settles to the bottom
of a body of water.
eroded soil and interstitial water
organic matter, iron oxides,
sulfides, carbonates
benthic organisms, shell, plant
and animal detritus
sewage, agricultural chemicals, oil and
grease.and industrial chemicals such as
metals, other inorganic chemicals, and
synthetic organic compounds
SEDIMENTS
solids
interstitial
water
PROPERTIES OF SEDIMENTS
Physical:
• moisture content
• particle size distribution
• type of clay minerals
• organic matter content
Chemical:
• pH
• redox potential
• salinity
• carbonate content
• amount and forms of sulfur
• reactive iron and hydrous oxides
• kinds and amounts of contaminants
2-2
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PARTICLE SIZE AND
AFFINITY FOR CONTAMINANTS
I
C33
CD
CZ3
§
o
gravel
sand
silt
clay
>50 microns
[contaminants]
50-2 microns
<2 microns
[contaminants] [contaminants]
PHYSICAL PROPERTIES
Type of Clay Minerals
\
kaolinite
= 3-15cmol(+)kg-1
smectite
= 80-120cmol(+)kg-1
PHYSICAL PROPERTIES
Organic Matter Content
Amount
low
high
Paniculate
Coatings
2-3
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Typical Range of pH and Redox Potential in
Soils, Sediments, and Dredged Materials
Sediments
(pH 6.5 - 8.5)
Upland Applied
Dredged Sediments
(pH 3.5 - 8.5)
Upland Soils
(pH 5.0 - 8.5)
Marsh Soils, Spoil Banks
(pH 3.5 - 8.0)
I I
-200 -100
strongly reducing
i i i i i i i
0 100 200 300 400 500 600
REDOX POTENTIAL, mv well oxidized
CONTAMINANTS IN SEDIMENTS
Interstitial water
•for
benthic organisms sediment solids
metal contaminants
organic contaminants
CONTAMINANTS IN SEDIMENTS
Interstitial water
benthic organisms
sediment solids
Soluble concentrations of contaminants and biological
availability are affected by physical and chemical
properties of the sediment solid phase.
2-4
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GENERAL CHEMICAL FORMS OF TRACE
AND TOXIC METALS IN SEDIMENTS
Readily Available:
• dissolved
• exchangeable
Potentially Available:
- exchangeable
• precipitated, i.e., Me(OH)2
• complexed with organic matter
• co-precipitated with hydrous oxides
• precipitated as sulfides
Unavailable:
• fixed within the crystalline lattice structure of clay
minerals
DISSOLVED METALS
free cation
metal cation complexed
with soluble ligands
EXCHANGEABLE METALS
©
clay mineral
2-5
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SEDIMENT pH EFFECT ON METAL
PRECIPITATION AND ADSORPTION
low pH (acid)
4
near neutral
or alkaline pH
Me(OH)i
Me2*
precipitation and adsoprtion
INFLUENCE OF CARBONATE CONTENT
ON pH AND METAL FORMS UPON
SEDIMENT OXIDATION
Oxidized Dredged Material
low carbonate may
contribute to low pH
upon oxidation
high carbonate
pH near neutral or
higher
MeCCXi
Me2* h
Me(OH),l
METAL COMPLEXED BY HUMIC ACID
2-6
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LONG-TERM RESPONSE OF HUMIC ACID
TO AN INCREASE IN REDOX POTENTIAL
Reduced Environment
Oxidized Environment
+ CO2 + Me2*
HYDROUS IRON OXIDES
Sediment particle with a coating of amorphous iron
oxhydydroxides containing co-precipitated trace and
toxic metals
HYDROUS IRON OXIDES
Oxidized Environment Reduced Environment
Fe2+ + H20
Reaction:
Fe203 + 6H* + 2e-
2Fe2* + 3H2O
2-7
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HYDROUS IRON OXIDE RESPONSE TO
CHANGES IN pH AND REDOX POTENTIAL
Reduced sediment,
near neutral pH
Oxidized sediment,
near neutral pH
Oxidized sediment,
acid pH
a Fe2*
AMORPHOUS METAL
SULFIDE PRECIPITATES
SULFIDE PRECIPITATION
Reduced Sediment
Oxidized Interstitial Water
MeSi
insoluble metal
sulfide precipitate
Me2* + SO4-
metals released
from sulfide
2-8
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Clay particle or primary mineral containing
trace/toxic metals in crystalline structure
2-9
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Overview of Test Methods and Criteria
for Evaluating Contaminated Sediments
Mr. Mike Kravttz, Mr. Chris Zarba, Mr. Tom Wall
U.S. EPA Office of Water: Office of Science and Technology
Washington, D.C.
Addressing the toxicity of sediments and any potential threat they pose to human health and the environment is an
important step in the remediation process. Several kinds of tools are available to use in making decisions concerning
sediment quality assessment and desired levels of remediation. Primary tools include environmental regulations
and sediment assessment methods. Brief descriptions of these tools, the development of nationally applicable
sediment quality criteria, and a synopsis of EPA's agency-wide Sediment Management Strategy form the basis of
this presentation.
Under CERCLA, Superfund remedial action must meet any federal standards, requirements, criteria, or limitations
that are determined to be legally applicable or relevant and appropriate requirements (ARARs). Environmental
regulations can be a source of ARARs and should be understood as part of the assessment and remediation
process. Major laws or agreements that relate to contaminated sediments will be briefly discussed; further
information is available in Chapter II of the seminar handbook, "Remediation of Contaminated Sediments" (EPA
625/6-91/028) and "Contaminated Sediments: Relevant Statutes and EPA Program Activities" (EPA506/6-90/003,
USEPA. 1990).
To identify levels at which specific contaminants in sediment cause harmful effects, the EPA is developing nationally
applicable sediment quality criteria using the equilibrium partitioning (EqP) method. The EqP approach uses water
quality criteria and partitioning coefficients (between sediment sorbents and pore water) of specific contaminants
to derive sediment quality criteria. The sediment quality criterion for a given contaminant is determined by
calculating the sediment concentration of the contaminant that would correspond to an interstitial pore water
concentration equivalent to the EPA water quality criterion for the contaminant. EqP-derived sediment quality
criteria will soon be available for a number of non-ionic organic chemicals, and research is continuing on
development of criteria for metals.
EPA is also investigating other methods used to assess the quality of potentially contaminated sediments. A draft
"Sediment Classification Methods Compendium" provides a description of each method, associated advantages
and limitations, and existing applications. The sediment assessment methods described can be classified into two
basic types: numeric ordescriptive. In particular, EPAis developing more sensitive toxicity tests to identify sediment
problems caused by complex mixtures of contaminants. Though toxicity testing does not directly identify the
problem contaminants, the use of techniques such as toxicity identification evaluation (TIE) allows one to identify
contaminants most likely responsible for the observed toxicity.
In January 1990, EPA's Sediment Steering Committee decided to prepare an agency-wide Sediment Management
Strategy and formed four workgroups to draft options for the strategy. The workgroups are Assessment and
Identification of Risk; Prevention; Remediation; and Management of Dredged Material. The staff on these
workgroups prepared fourteen issue papers addressing such topics as the preparation of a national inventory of
contaminated sites and of facilities that contaminate sediments; need for a consistent, tiered testing approach to
assess sediment quality; and enforcement-based remediation. In May. afterconsidering input from EPA managers,
other Federal and state agencies, the Steering Committee met to select preliminary options for the Strategy. This
summer, a draft Strategy will be presented to industry and environmental groups for review.
3-1
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COORDINATING THE AGENCY'S
CONTAMINATED SEDIMENTS ACTIVITIES
Contaminated Sediments Steering Committee
- Policy Coordination
Contaminated Sediments Technical
Committee
- Coordinating Research, Technical, and
Field Activities
EPA SEDIMENT OVERSIGHT
TECHNICAL COMMITTEE
Sediment Classification Methods Compendium
Contaminated Sediments: Relevant Statutes
and EPA Program Activities
Contaminated Sediments News
Guidance on Selecting Techniques for
Remediating Contaminated Sediments
SOME MAJOR LAWS OR AGREEMENTS
THAT RELATE TO
CONTAMINATED SEDIMENTS
Clean Water Act (CWA)
Resource Conservation and Recovery Act (RCRA)
Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA)
Marine Protection, Research, and Sanctuaries Act (MPRSA)
Toxic Substances Control Act (TSCA)
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)
Clean Air Act (CAA)
National Environmental Policy Act (NEPA)
Rivers and Harbors Act (RHA)
U.S.-Canada Great Lakes Water Quality Agreement
(GLWQA)
3-2
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CONTAMINATED SEDIMENTS:
RELEVANT STATUTES AND
EPA PROGRAM ACTIVITIES
(U.S. EPA, 1990)
Provides information on Program Office Activities
relating to contaminated sediment issues, and the
specific statutes under which these actitivites fall.
OVERVIEW OF
CRITERIA DEVELOPMENT
EFFORT
WATER QUALITY CRITERIA
• Protective of
- Aquatic life (95%)
- Human health
• Established
• Defensible
3-3
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WORKSHOP SEDIMENT
CRITERIA DEVELOPMENT
Legal Authority
Review Approaches
National Assessment
November, 1984
UNCERTAINTY ANALYSIS
Sediment Criteria
Increasing
Concentration
I
\\
Uncertainty
BIOAVAILABILITY
3-4
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EQUILIBRIUM PARTITIONING
APPROACH
A sediment quality value for a given contaminant
is determined by calculating the sediment
concentration of the contaminant that would
correspond to an interstitial water concentration
equivalent to the EPA water quality criterion for
the contaminant.
EQUILIBRIUM PARTITIONING
\
Non-Ionic
Organics
Metals
Ionic
Organics
i
Science
Advisory
Board Review
POTENTIAL REGULATORY USES
FOR SEDIMENT CRITERIA
• Superfund
• Dredging
• Ocean Dumping
• Monitoring
• Permitting
• Other
3-5
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SEDIMENT CLASSIFICATION
METHODS COMPENDIUM
Describes the Various Methods Used to Evaluate
Sediment Contamination, Including Their
Advantages, Limitations, and Existing Applications.
(June 1989 draft is under revision.)
SEDIMENT CLASSIFICATION
METHODS COMPENDIUM
[Sample Contents]
Chapter 1. Introduction
1.0 Background
2.0 Objective
3.0 Overview
Chapter 2. Bulk Sediment Toxicity Test Approach
1.0 Specific Applications
2.0 Description
3.0 Usefulness
4.0 Status
SEDIMENT QUALITY
ASSESSMENT METHODS
Numeric Methods
Method
Type(s) of Data
Spiked-sediment Toxicity
Interstitial Water Toxicity
Equilibrium Partitioning
Tissue Residue Approach
Sediment Quality Triad
Apparent Effects Threshold
Chemistry, Toxicity
Chemistry, Toxicity
Chemistry
Chemistry, Toxicity
Chemistry, Toxicity,
In Situ Studies
Chemistry, Toxicity,
In Situ Studies
3-6
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SEDIMENT QUALITY
ASSESSMENT METHODS
Descriptive Methods
Method
Type(s) of Data
Bulk Sediment Toxicity
Freshwater Benthic Community
Structures
Marine Benthic Community
Structures
Sediment Quality Triad
Toxicity
In Situ Studies
In Situ Studies
Chemistry, Toxicity,
In Situ Studies
BULK SEDIMENT TOXICITY
TEST APPROACH
Test organisms are exposed in the laboratory to
field-collected sediments. Mortality orsublethal
effects in different sediments (sites) are compared
quantitatively to one another or to effects observed
in reference sediments.
INTERSTITIAL WATER
TOXICITY APPROACH
(Toxicity Identification Evaluation)
Toxicity of interstitial water is quantified and identifi-
cation evaluation procedures are applied to identify
and quantify chemical components responsible for
sediment toxicity.
3-7
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BENTHIC COMMUNITY STRUCTURE
(Freshwater, Marine)
Environmental degradation is measured by
evaluating alterations in benthic community
structure.
TISSUE RESIDUE APPROACH
Sediment chemical concentrations that will result in
acceptable residues in exposed biotic tissues are
determined.
2-step process:
1. Link toxic efffects to residues (e.g., through
dose-response relationships)
2. Link chemical residues in specific organisms to
sediment chemical concentrations.
SEDIMENT QUALITY TRIAD
Examines the correspondence among three
measures of sediment contamination:
• Concentrations of chemical contaminants
in sediment
• Toxicity
• In situ studies (usually infauna data)
3-8
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APPARENT EFFECTS
THRESHOLD APPROACH
One possible way to derive a single index from trie
triad components.
An AET is the sediment concentration of a
contaminant above which statistically significant
biological effects (e.g., amphipod mortality in
bioassays, depressions in abundance of benthic
infauna) would always be expected.
GUIDANCE ON SELECTING
TECHNIQUES FOR THE REMEDIATION
OF CONTAMINATED SEDIMENTS
Will Provide Guidance on Selecting Procedures and
Technology for the Remediation of Contaminated
Sediments in Site-Specific Situations.
(In draft form; final expected by end of FY91)
EPA SEDIMENT
MANAGEMENT STRATEGY
Will establish national priorities for assessing sedi-
ment problems, source controls, remediation efforts
and dredged material disposal options.
Being developed from the input of four workgroups:
1. Assessment and Identification of Risk
2. Prevention
3. Remediation
4. Management of Dredged Material
3-9
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EXTENT AND SEVERITY OF
.SEDIMENT CONTAMINATION
Should We Do a National Inventory?
- S/feswith Contamination
- Sources of Contamination
Who Will Take the Lead?
How Will We Do an Inventory?
- New vs. Existing Data
- General Extent of Problem vs. List of
Specific Sites/Sources
- Ranking System for Follow-up Actions
Resource Needs
STRATEGY ISSUE:
How Do We Define the Extent and Severity of
the Risks of Sediment Contamination?
Should We Use Consistent Tiered Testing Across All
EPA Programs?
- Agree on a hierarchy of biological effects-based
testing and physical/chemical analysis.
- Testing continues until a clear basis for decision is
reached on whether sediment poses risks to aquatic
life or humans consuming fin fish and shellfish.
- Good progress has been made in developing a
variety of tests for tiered system.
- Difficulty lies in how each program will decide "How
Clean is Clean" based on test results.
PREVENTING SEDIMENT
CONTAMINATION
Existing Programs
- Sediment criteria
- Effluent guidelines
- Point source controls
- Nonpoint source controls
- Reviewing pesticides
- Reviewing toxic chemicals
Issue: How Do We Implement a Prevention Strategy?
- Consistent tiered testing
- Guidance, Procedure changes
- Resource needs
3-10
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REMEDIATING CONTAMINATED
SEDIMENTS
Existing Programs
• OSWER Supertund and RCRA Corrective Action Programs
- a few cases
• CWA Section 115
- no funding received
• Enforcement-Based Remediation
- several recent cases
• CWA
• CERCLA
• RCRA
• TSCA
REMEDIATING CONTAMINATED
SEDIMENTS (cont.)
Issues
• How do We Determine the Need for Remediation?
• How do We Select Cleanup Goals
• How Do We Implement a Remediation Strategy?
- Statuatory Changes
• Guidance and Procedure Changes
- Resource Needs
MANAGING DREDGED MATERTIALS
Existing Programs
• Ocean Dumping Programs
- national tiered testing system under revision
• CWA Section 404 Program
- first draft of a national tiered testing program
• issues
- Evaluting the Need for Restrictions on Disposal
- Improving the Balance of Environmental and Economic
Factors
- Resource Needs
3-11
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Sampling Methods for
Determining Extent of Contamination
Mr. Jan A. Miller
U.S. Army Corps of Engineers
Chicago, Illinois
Characterization of contaminated sediments begins with the identification of contaminants present and a
description of the vertical and horizontal distributions of the contaminants within the sediments. Characterization
of the sediments is also-Important, as sediment characteristics will have profound effects on contaminant availability
and should impact remediation decisions. Sediment characterization should include physical and chemical
characteristics but also distributions of these within the site of concern.
In order to properly sample and characterize contaminated sediments, extensive planning must first be done. The
sequence in the planning stage should include:
1. Identification of sampling purposes and objectives.
2. Compilation of available data on the site of concern.
3. Collection of preliminary field data.
4. Development of a detailed sampling plan.
Developing a sampling plan appropriate for the site and sampling objectives increases the quality of the site
characterization and minimizes characterization costs. Unfortunately, due to site variability, a systemized sampling
plan applicable to all sites is not feasible.
There are a number of sampling devices that are presently being used to collect sediment samples, including core
samplers, grab samplers, and spoons, scoops, and trowels.
There are many different types of core samplers that may be used for sediments. Some hand held units can be
operated from small vessels. Some core samplers require the use of a tripod or truck mounted drill rig operated
on a floating plant (barge). Core sampling devices include the split-spoon, the piston-tube or Chicago tube, the
vibracore, and hand augers.
Grab samplers, such as the Ponar and Eckman dredge samplers, are small, lightweight, and can be operated by
hand from a small boat. They only collect surface sediments (top 3-6 inches). They have problems with any
consolidated (hard packed) deposits. For larger volumes of sample, sometimes needed for treatability tests, a
small, commercial clamshell dredge (1-3 cubic yard bucket) can be used.
Spoons, scoops, and trowels are only useful in shallow water. They are less costly than other samplers, easy to
use, and may be useful if numerous samples are intended; their low cost allows disposal between sample sites.
Core samplers are generally preferred over other samplers because (1) core samplers can sample to greaterdepth,
(2) core samplers maintain the complex integrity of the sediment, and (3) core samplers do not disturbthe substrate
as much as other sampling procedures. Grab samplers, on the other hand, are less expensive, easier to handle,
and often require less manpower than core samplers. Unfortunately, grab samplers cause considerable disruption
of the sediment. Dredge samplers promote loss of the fine-grained fraction of the sediment as well as water soluble
compounds and volatile organic compounds which may be present in the sediment. Spoons, scoops, and trowels
are somewhat undesirable because the reproducibility of sampling area, depth, and volume from one sampling site
to another is poor. They also tend to disrupt the sediment during sampling.
The type of chemical and physical analyses performed on sediment collected is specific to the purpose and
objectives of the plan. There is no "standard" laundry list of analyses which is appropriate to all cases.
4-1
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DEVELOPMENT OF A SAMPLING PLAN
1. Identification of sampling purposes and
objectives.
2. Compilation of available data on the site of
concern.
3. Collection of preliminary field data.
4. Development of a detailed sampling plan.
IDENTIFICATION OF SAMPLING
PURPOSES AND OBJECTIVES
1. Determine distribution of specific contaminants.
2. Determine sediment contaminant mobility.
3. Determine existing impacts on aquatic/benthic
fauna.
4. Determine disposal alternatives (regulatory).
5. Determine disposal alternatives (treatability).
COMPILATION OF AVAILABLE DATA
1. Water depths/tidal fluctuations.
2. Obstructions (bridges, pipelines, etc.).
3. Access sites for mobilizing equipment.
4. Sediment depths (dredging or construction history).
5. Sources of contaminants (point and non-point) and
other factors affecting contaminant distributions.
6. Hydraulic/other factors affecting sediment distribution.
7. Historic sediment quality data.
8. Survey benchmarks (for referencing sediment and
water elevations).
4-2
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COLLECTION OF PRELIMINARY
FIELD DATA
Helps minimize the costs of sampling and of
laboratory analyses.
DEVELOPMENT OF A
DETAILED SAMPLING PLAN
1. Locations of samples (lateral and vertical)
2. Types of samples (grab or core)
3. Number and volumes of samples required
4. Sampling procedures and equipment
5. Supporting vessels/equipment
6. Types of analytical tests required
7. Quality Assurance Program Plan (QAPP) for
sampling and analysis
8. Cost estimate
SEDIMENT SAMPLING DEVICES
INCLUDE:
1. Core Samplers
2. Grab Samplers
3. Spoons, Scoops, and Trowels
4-3
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ADVANTAGES OF CORE SAMPLERS
1. Core samplers sample to greater depth.
2. Core samplers maintain sediment integrity.
3. Core samplers do not disturb the substrate
as much as other sampling procedures.
LIMITATIONS OF CORE SAMPLERS
1. Core samplers do not work well in sandy
or rocky substrates.
2. Core samplers collect smaller amounts of
sediment and may require additional
sampling.
3. Most core samplers are expensive.
4. Most core samplers are difficult to handle
and, consequently, have limited use under
moderate wave conditions.
CORE SAMPLERS INCLUDE:
1. Split-spoon
2. Piston-tube or Chicago Tube
3. Vibracore
4. Hand Augers
4-4
-------
ADVANTAGES OF GRAB SAMPLERS
OVER CORE SAMPLERS
1. Less expensive
2. Easier to handle
3. Require less manpower
LIMITATIONS OF GRAB SAMPLERS
1. Can cause considerable disruption of the
sediment.
2. Can promote loss of the fine-grained fraction
of the sediment as well as water soluble
compounds and volatile organic compounds
which may be present in the sediment.
TYPICAL GRAB SAMPLERS:
1. Ponar
2. Eckman
4-5
-------
ADVANTAGES OF SPOONS, SCOOPS,
AND TROWELS
1. Cheap
2. Easy to use
3. Applicable for numerous sample collections
LIMITATIONS OF SPOONS, SCOOPS,
AND TROWELS
1. Reproducibility of sampling area, depth, and
volume is poor.
2. Tend to disrupt the sediment during
sampling.
OTHER SAMPLING CONSIDERATIONS
1. Contaminants in the interstitial water
2. Container material for transportation of
samples
3. Preservation of samples
4. Storage time of samples
5. Volume requirements for laboratory analyses
4-6
-------
COMMON PHYSICAL ANALYSES:
1. Particle size and distribution
2. Organic carbon or volatile matter content
3. Total solids/specific gravity
COMMON CHEMICAL ANALYSES:
1. pH
2. Oxidation-reduction
3. Salinity conditions
4. Sulfide content
5. Amount and type of cations and anions
6. Amount of potentially reactive iron and
manganese
4-7
-------
Modeling of Contaminated Sediment Movement
Dr. Stephen C. McCutcheon
U.S. Environmental Protection Agency
Athens, Georgia
Models applicable to contaminated sediments include sediment transport and contaminant transport and fate
models. These models have several applications including: (1) they can be used as a screening tool in predicting
the environmental and health impacts from contaminant exposure during various remediation actions and (2) they
can be used diagnostically to investigate sources of contamination. Current models are limited in their predictive
ability to function as a screening tool or crude design model, but are developed to such a degree that they are being
applied in this respect to the Buffalo River, New York. Diagnostic modeling is being done at the Sheboygan River,
Wisconsin.
Sediment transport models are linked to hydrodynamic models and predict sediment movement due to circulation.
Different models have been developed for a variety of sediment environments including lakes, harbors, estuaries,
coastal areas, and rivers. The models may be one-, two-, orthree-dimensional, depending on the nature of the water
body. The one-dimensional models, HYDRO1D-DYNHYD, HYDRO1D-RIVMOD, and HSPF, are used for rivers,
streams, and watersheds. The two-dimensional model, HYDRO2D-V, is generally the first choice of the Environ-
mental Research Laboratory (ERL) and has application for estuaries, shallow lakes and bays, and streams. The
HYDRO2D-V is being used to model arsenic contamination in New Jersey and is planned for use at Montana mining
district streams and in modeling the south bay of San Francisco Bay. The three-dimensional model, HYDRO3D-
V, has application for stratified bodies of water, such as lakes, and has been tested in PCB studies for Green Bay,
Wisconsin. These models are in different stages of refinement, but all are available from the ERL in Athens,
Georgia.
Fate and transport models mimic the physical and chemical environment of sediments and predict how
contaminants and sediments interact, particularly as conditions change. The HYDRO2D-V, also used as a
sediment transport model, has been used to model adsorbed contaminants, but does not incorporate other
contaminant processes. The WASP4 model is a general purpose, mass balance model incorporating a number
of parameters and is considered the state-of-the-art fate and transport model by ERL and a number of EPA offices.
The WASP4 has been adopted fortoxics management by the Great Lakes National Program Office. Studies using
WASP4 focus on Green Bay, Lake Ontario, and Saginaw Bay. The WASP4 also simulates fish and food chain
bioaccumulation and is being used to model these at the Buffalo River, New York; the Sheboygan River, Wisconsin;
and Saginaw Bay, Michigan.
5-1
-------
EXPOSURE AND ECORISK
TECHNICAL SUPPORT CENTER
ATHENS, GEORGIA
AREAS OF SUPPORT
Geochemical Speciation
Contaminant Transport in Soil-Groundwater
Systems
Sediment-Contaminant Transport in Surface
Water
Ecological Risk Assessment
Simulation Modeling
GEOCHEMICAL SPECIATION
PROBLEMS
Leaching, Mobility of Metals
Potential Bioavailability of. Metals
5-2
-------
SEDIMENT-CONTAMINANT TRANSPORT
IN SURFACE WATER
PROBLEMS
• Existing Contaminant Migration, Risk
• Human, Ecological Risk following
Remediation
SEDIMENT-CONTAMINANT TRANSPORT
IN SURFACE WATER
EXAMPLES
• Clark Fork River/Milltown Reservoir
• Vineland Chemical
• Sheboygan Harbor
MODEL: WASP4
DIMENSIONS: 0-Dimensional (multi-dimensional)
DESCRIPTION: WASP4 is a dynamic compartment
modeling system that can be used to analyze a
variety of water quality problems in a diverse set of
water bodies.
5-3
-------
MODEL: HSPF
DIMENSIONS: 1-Dimensional
DESCRIPTION: The Hydrologic Simulation Pro-
gram (HSPF) is a comprehensive package for simu-
lation of watershed hydrology and water quality for
both conventional and toxic organic pollutants.
MODEL: SED2D
DIMENSIONS: 2-Dimensional
DESCRIPTION: SED2D is a finite element model-
ing system for simulating 2-dimensional (depth-
averaged) surface water and cohesive sediment
transport.
MODEL: SED3D
DIMENSIONS: 3-Dimensional
DESCRIPTION: SED3D is a finite difference
modeling system for calculating 3-dimensional
unsteady currents and sediment transport in lakes
and estuaries.
5-4
-------
ECOLOGICAL RISK ASSESSMENT
PROBLEM
• Assess Ecological Risk from Present
Contaminants
ECOLOGICAL RISK ASSESSMENT
EXAMPLES
• New Jersey Zinc/Eagle River
• Clear Creek/Central City
• DuPont Newport
• Nascolite Site
U.S. EPA
CENTER FOR
EXPOSURE ASSESSMENT
MODELING
OFFICE OF RESEARCH
AND DEVELOPMENT
ATHENS, GEORGIA
5-5
-------
MODEL SUPPORT
Surface Water - Quality
Surface Water - Dilution, Hydrodynamics
Runoff and Erosion
Soil and Groundwater
SURFACE WATER - QUALITY
Conventional Water Quality
Chemical Transport and Fate
Sediment Transport
Metals Speciation
Fish Bioaccumulation
SURFACE WATER - DILUTION,
HYDRODYNAMICS
» Mixing Zone Analysis
• Pollution Dilution
• Hydrodynamics
5-6
-------
RUNOFF AND EROSION
• Urban
• Rural
SOIL AND GROUNDWATER
• Chemical Transport
• Metals Speciation
• Subsurface Hydrology
SURFACE WATER QUALITY MODELS
QUAL2E stream water quality
WASP4 general water quality,
chemical fate
HSPF upland stream water quality,
chemical fate
EXAMS general chemical fate
FGETS fish bioaccumulation
SED2D-V 2-dimensional, vertically integrated
cohesive sediment transport
MINTEQ metals speciation
5-7
-------
RUNOFF, SOIL, AND
GROUNDWATER MODELS
PRZM
pesticide root zone transport
MULTIMED multimedia hazardous waste
screening
RUSTIC soil and groundwater pesticide
transport
HSPF watershed runoff, erosion
SWMM urban stormwater runoff
MINTEQ metal speciation
WASP4
GENERAL WATER QUALITY ANALYSIS MODEL
Waste Load Allocation of Conventional
and Toxic Pollutants
Dynamic Water Quality
Ponds, Rivers, Lakes, Estuaries
Simple 1-D to Multidimensional Networks
Linkage to Hydrodynamic Models
Linkage to Loading Models
Surface Water - Benthic Sediment Interaction
Dissolve Oxygen Balance
Simple Sediment Balance
Nutrient Cycling and Phytoplankton Growth
Chemical Transport and Fate
Linkage to Bioaccumutation Models
EXAMS2
ORGANIC CHEMICAL EXPOSURE
ANALYSIS MODEL
Screening and Evaluation of Organic Chemicals
in Aquatic Systems
Steady-state and Quasidynamic Pollutant Fate
Ponds, Rivers, Lakes
Simple 1-D to Multidimensional Networks
Linkage to Loading Models
Surface Water - Benthic Sediment Interaction
Chemical Transport and Fate
Linkage to Bioaccumulation Models
5-8
-------
MINTEQA2
GEOCHEMICAL EQUILIBRIUM - METALS
SPECIATION MODEL
Exposure Assessment of Metals
Equilibrium Speciation of Metals, Ions, Ligands
Groundwater and Surface Water
Organic and Inorganic Complexation, Sorption, and
Precipitation/Dissolution
Thermodynamic Data Base over 1400 Species
13 Trace Metals/Metalloids of Major Concern:
Ag, As, Ba, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, Ti, Zn
FGETS
ORGANIC CHEMICAL BIOACCUMULATION MODEL
Risk Assessment for Bioaccumulation of Organic
Chemicals in Fish
Pharmokinetics Based on Gill and Gut Exchange
of Nonmetabolized Organic Chemicals
Physiological and Morphological Data Base
Dynamic Exposure
Simple Food Chains
Linkage from Chemical Fate Models
Internal Partitioning to Blood, Fat, Structure
Estimates Death by Narcosis
Predicts Relative Significance of Exposure Routes
HSPF
HYDROLOGIC SIMULATION OF
UPLAND WATERSHEDS
Pesticide Exposure Assessment, Nonpoint Source
Load Allocation
Dynamic Runoff, Water Quality, Pollutant Fate
Uplands Watershed
Pervious and Impervious Land Segments
Branching Stream Network
Sediment Erosion and Transport
Nutrient Runoff, Erosion, and Transport
Pesticide Runoff, Erosion, and Transport
Surface Water - Benthic Sediment Interaction
Dissolved Oxygen Balance
Phytoplankton
5-9
-------
SWMM
URBAN STORM WATER MANAGEMENT MODEL
Hydraulic and Runoff Quality Analysis of Urban
Drainage Networks
Single Event or Continuous Simulation
Catchment Schematization Course or Fine
Pollutant Buildup on Catchments
Rainfall, Snowmelt, Runoff
Flow Routing through Drainage Network
Dynamic Flow through Sewer Pipes
Storage and Treatment
PRZM
PESTICIDE ROOT ZONE MODEL
Exposure Assessment, Leaching Potential of Pesticides
Runoff, Erosion, and Vertical Leaching
Hydrologic Component - SCS Curve Number Technique
Water Movement by Generalized Soil Terms
Chemical Transport, Partitioning, Decay
Linkage to Surface Water Models
ENVIRONMENTAL MODELING
SOFTWARE AT THE USEPA
CENTER FOR
EXPOSURE ASSESSMENT
MODELING
Athens, GA (404-546-3549)
water quality, exposure assessment, surface water,
soil, groundwater, multimedia
5-10
-------
ENVIRONMENTAL MODELING
SOFTWARE AT THE USEPA
ATMOSPHERIC SCIENCES
RESEARCH LABORATORY
RTP.NC (919-541-4564)
air dispersion, human exposure (UNAMAP Series)
ENVIRONMENTAL MODELING
SOFTWARE AT THE USEPA
OFFICE OF TOXIC SUBSTANCE
Washington, D.C. (202-382-3894)
Graphical Exposure Modeling Systems - GEMS, PCGEMS
• exposure models, surface water, soil, groundwater,
air, multimedia
• estimation techniques
• environmental data
ENVIRONMENTAL MODELING
SOFTWARE AT THE USEPA
OFFICE OF HEALTH AND
ENVIRONMENTAL ASSESSMENT
Washington, D.C. (202-475-8924)
RISK * ASSISTANT
• human risk assessment
• various exposure pathways
5-11
-------
Removal and Transport Processes
Mr. Steve Garbaciak
U.S. Army Corps of Engineers
Chicago, Illinois
The process of selecting removal and transport technologies should be driven by treatment and/or disposal
decisions. This is because treatment/disposal options typically have the higher costs and are more controversial
from a social, political, or regulatory perspective.
A primary concern during the removal and transport of contaminated sediments is the danger of introducing con-
taminants into previously uncontaminated areas. Contamination during these steps occurs primarily from the
resuspension of sediments during removal and from spills and leaks during transport.
To increase efficiency and reduce sediment resuspension, dredges, operational controls, and barriers should be
used together. Of these, dredges actually remove the sediments; operational controls and barriers minimize the
resuspension and spread of contaminated sediments during removal. Dredges available for the removal of
contaminated sediments include mechanical and hydraulic.
Mechanical dredges remove sediments by the direct application of mechanical force to dislodge sediment material.
The most commonly used mechanical dredge is the clamshell dredge which has widespread application for the
removal of contaminated sediments, although the use of a modified, watertight bucket may be required.
Hydraulic dredges use centrifugal pumps to remove sediments in a liquid slurry form. They are widely available
in the U.S. Often a cutterhead, or similar device, is fitted to the suction end of the dredge to assist in dislodging
bottom materials. New dredge designs attempt to reduce the amount of resuspension caused by dredging and to
decrease the water content of the pumped slurry.
Operational controls include the cutter speed, the depth of cut, the swing speed and/or speed of advance, and the
positioning of equipment. Operator experience is of primary importance in implementing operational controls.
Barriers help reduce the environmental impact of sediment removal. Structural barriers include dikes, sheet pilings,
caissons, and other weir enclosures. Non-structural barriers include oil booms, pneumatic barriers, sediment traps,
silt curtains, and silt screens. Application of barrier options is site specific and functions to control contaminants
only during removal.
The primary emphasis during transport is towards spill and leak prevention. Transport options include pipelines,
barges or scows, railroads, trucks, or hopper dredges. Selection of transport options will be affected by both dredge
selection and pre-treatment and treatment decisions.
6-1
-------
REMOVAL AND TRANSPORT
PROCESSES FOR
CONTAMINATED SEDIMENTS
CONTAMINATED SEDIMENT
REMEDIATION COMPONENTS
1. Removal
2. Transport
3. Pre-treatment
4. Treatment
5. Disposal
6. Effluent/leachate treatment
DREDGING METHODS
1. Mechanical
2. Hydraulic
6-2
-------
MECHANICAL DREDGES
1. Dipper
2. Bucket ladder
3. Dragline
4. Clamshell
BUCKET DREDGE
DIPPER DREDGE
6-3
-------
CLAMSHELL DREDGE
PLAIN SUCTION
HYDRAULIC DREDGES
1. Plain Suction
2. Cutterhead
3. Dustpan
4. Others
6-4
-------
CUTTERHEAD DREDGE
CUTTERHEAD
LAOOC/I HCAO
CUTTER SHAFT
LOOSE MATSHIAL
\ O«£ DGf D SOTTO
DUSTPAN DREDGE
U JZ. _
r-ANCHOM LINES
6-5
-------
MUD CAT DREDGE
- DISCHARGE UNE
D
ANCHOR
'LINE
--L
1—
AUGER
ADVANTAGES OF
MECHANICAL DREDGES
1. In-situ water content
2. Maneuverability
3. Debris removal
DISADVANTAGES OF
MECHANICAL DREDGES
1. Resuspension
2. Rehandling
3. Lower production rate
6-6
-------
ADVANTAGES OF
HYDRAULIC DREDGES
1. Limited resuspension
2. No rehandling
3. High production rate
DISADVANTAGES
OF HYDRAULIC DREDGES
1. Large water volume
2. Pipeline
3. Debris
DREDGING IMPACT CONTROLS
1. Closed bucket
2. Operations
3. Barriers
6-7
-------
WATERTIGHT BUCKET
FOR CLAMSHELL DREDGE
0 COVER
0 COVER
0 RUBBER PACKING
OR WELDED TONGUE
AND GROOVE
0 ROD
CUTTERHEAD DREDGE - PLAN VIEW
This view illustrates operation complexity of a cutterhead and,
thus, the importance of operator experience.
TRANSPORT TECHNIQUES
1. Pipeline
2. Barge/scow
3. Others
6-8
-------
DREDGE TYPE SELECTION FACTORS
1. Volume
2. Location
3. Material
4. Pre-treatment
VOLUME FACTORS
1. Economy of scale
2. Production rate
LOCATION FACTORS
1. Obstacles
2. Areal layout
3. Distance to disposal
4. Time limits
6-9
-------
Dewatering and Other Pre-treatment Processes
Pre-treatment technologies are defined as those methods that prepare dredged materials for additional treatment
and/or disposal activities. Pre-treatment decisions are greatly influenced by dredging, treatment, and disposal
decisions. Pre-treatment technology types include dewatering, particle classification processes, and slurry
injections. They are primarily applicable to hydraulically dredged sediment.
The objective of dewatering is to reduce the water content (increase the solid content) of sediments for one of the
following reasons: dewatering improves dredged material handling characteristics; dewatering reduces treatment
costs; dewatering reduces transportation costs; and dewatering is required prior to land disposal.
Dewatering technologies can be subdivided into two general processes: air drying processes and mechanical
processes. "Air drying" refers to those dewatering techniques by which the moisture is removed by natural
evaporation and gravity or by induced drainage. Air drying is less complex, easier to operate, and requires less
operational energy than mechanical dewatering. Air drying also can produce a dryer sediment than mechanical
dewatering. The most widely applicable and economical air drying process available for sediments is an
appropriately managed confined disposal facility (CDF).
Mechanical dewatering involves processes in which water is forced out of the sediment through mechanically
induced pressures. Mechanical dewatering processes include the following: filtration, including belt filter presses,
chamber filtration, and vacuum rotary filtration; centrifuges, including solid bowl and basket; and gravity thickening.
Particle classification technologies separate the slurry according to grain size or removes oversize material that is
incompatible with subsequent processes. Classification by grain size is important in the management of sediments
contaminated with toxic materials since the contaminants tend to adsorb primarily onto fine grain clay and organic
matter. The small grain solids of a specific size or less can be treated while the relatively non-contaminated, coarser
soils and sediments can be disposed of with minimal or no additional treatment. Particle classification technologies
include: impoundment basins, hydraulic classifiers, hydrocyclones, grizzlies, and screens.
Slurry injection is the injection of chemicals, nutrients, or microorganisms into the dredged slurry. Chemical
injections condition the sediment for further treatment and/or accelerate the settling of suspended solids. Nutrient
and/or microbe injections may enhance biodegradation of organics, either by providing a suitable environment for
microbe growth or by supplying the microbes themselves.
The amount of handling and rehandling required by various pre-treatment options will also influence pre-treatment
decisions. Especially with severely contaminated sediments, all equipment that comes in contact with the
sediments will require subsequent decontamination. Furthermore, rehandling also mechanically disrupts the
sediments and increases the probability of introducing contaminants into the environment. Conversely, a series
of pre-treatment steps requiring rehandling may bethe most efficient way of separatingthe contaminated sediments
and preparing them for treatment.
The water generated during dewatering generally contains suspended solids and may contain contaminants. Its
quality may exceed effluent standards for receiving waters and may, therefore, require further treatment or a permit
for discharge.
7-1
-------
PRE-TREATMENT TECHNOLOGIES
ARE...
those methods that prepare dredged materials for
additional treatment and/or disposal activities.
PRE-TREATMENT OBJECTIVES:
1. To enhance or accelerate settling of the
dredged material solids.
2. To reduce the water content of the dredged
material solids.
3. To separate coarser solids from
fine-grained solids.
4. To reduce the overall cost of the remedial
action.
PRE-TREATMENT TECHNOLOGY TYPES
1. Dewatering
2. Particle classification
3. Slurry injection
7-2
-------
PRE-TREATMENT DEFINITIONS:
1. Percent Solid (Solid Content)
2. Percent Water (Water Content)
3. Percent Moisture (Moisture Content)
DEWATERING ADVANTAGES
1. Improved handling characteristics
2. Reduced treatment costs
3. Reduced transportation costs
4. Required prior to land disposal
DEWATERING TECHNOLOGIES
1. Air Drying Processes
2. Mechanical Processes
7-3
-------
MECHANICAL DEWATERING
PROCESSES INCLUDE:
1. Belt - filter presses
2. Chamber filter presses
3. Vacuum rotary filter presses
4. Centrifuges
5. Gravity thickeners
BELT FILTER PRESS
Independent High
Pressure Section
CHAMBER FILTER PRESS
7-4
-------
VACUUM ROTARY FILTRATION
BASKET CENTRIFUGE
Feed!
Basket Wall
/
Filler Paper
(Used With
Perforated Wall)
Effluent
SOLID BOWL CENTRIFUGE
Drive Assembly
Rotor Drive Assembly
Solids
Discharge
7-5
-------
PARTICLE CLASSIFICATION
TECHNOLOGIES...
separates the slurry according to grain size
or removes oversized material.
PARTICLE CLASSIFICATION IS
IMPORTANT BECAUSE...
contaminants tend to sorb to fine grain clay
and organic material.
PARTICLE CLASSIFICATION
PROCESSES INCLUDE:
1. Impoundment basin
2. Hydraulic classifiers
3. Hydrocyclones
4. Grizzlies
5. Screens
7-6
-------
TYPICAL IMPOUNDMENT BASIN
Plan
use c*«mro
m.
^^•—•:••:• :::::
««f A FO* iCD«(NiMriON
^v :
^
""-^
^
TYPICAL IMPOUNDMENT BASIN
Cross Section
D»fDC£0 U riKUI.
r»ui. jroMCf
TYPICAL CYCLONE
7-7
-------
SLURRY INJECTION TYPES
1. Chemical injections
(coagulants and flocculants)
2. Nutrient injections
3. Microbe injections
TYPICAL CONFIGURATION OF AN
ANIONIC POLYMER IN SOLUTION
©
©
©
USE OF A PRE-TREATMENT TRAIN?
7-8
-------
Technology Screening and Integration Processes
Dr. George Hyfantis
International Waste Management Systems
Knoxville, Tennessee
Technology screening is the systematic appraisal of remediation approaches in orderto select the most appropriate
alternative(s). The first step in this appraisal is to determine treatment goals. In determining treatment goals,
questions of whetherto remediate a site and what degree of cleanup is necessary should be addressed. Once these
questions are answered, methods to be used in achieving the desired remediation can be determined.
Contaminants and contaminant concentrations vary widely between sites and within sites. Furthermore, there is
usually a high degree of variability among site characteristics. Because of these sources of variability, selection
of appropriate and feasible remediation techniques for contaminated sediments is a complex task. No simple
management plan or screening procedure exists for selecting among available options. A screening logic is needed
that can take into account specific site factors, the degree of protection required, costs, and availability and reliability
of cleanup alternatives.
The fundamental steps in searching for a feasible technology to remediate a contaminated sediment are to:
(1) identify site and contaminant characteristics, (2) develop a list of treatment options, and (3) conduct a detailed
evaluation of the possible treatments.
^
The "treatment train approach", an integration process, is a valuable concept for remediating contaminated
sediments. Taking such an approach acknowledges the complexity of dealing with contaminated sediments and
the fact that a multifaceted approach, combining several technologies into a sequence of steps, may permit more
flexibility in addressing problems. In many cases, a treatment train may be essential to clean up sediments
containing different types of contaminants.
The term "side stream" refers primarily to the need to address contaminants generated by primary technologies.
Forexample, while incineration may effectively destroythe organic contaminants in dredged material,the off-gases
and/or ash may contain other types of contaminants. Thus, "side stream" treatment may be required to furthertreat
contaminants collected. Necessary side stream technologies would be part of the overall evaluation for a
remediation approach.
8-1
-------
TREATMENT TECHNOLOGIES
SCREENING OF
FEASIBLE TECHNOLOGIES
PROCESS
1. Site and contaminant characteristics
2. Based on site evaluation list appropriate
technologies
3. Evaluate each treatment option
8-2
-------
TREATMENT
TRAIN APPROACH
Sequenced technologies must be
compatible
The correct sequence must be chosen
Consider effects/impacts of
by-products
ESTABLISH THE
CLEAN UP GOALS OF
THE SITE
8-3
-------
BIOLOGICAL TECHNOLOGIES CONSIDERED
FOR NEW BEDFORD HARBOR SEDIMENTS
For For
Sediment Water PCB Metal
Matrix Matrix Treatment Removal
Advanced Biological Methods Yes No Yes No
Aerobic Biological Methods No Yes No No
Anaerobic Biological Methods Yes No No No
Composting Yes No No No
Land Spreading Yes No No No
PHYSICAL TECHNOLOGIES CONSIDERED
FOR NEW BEDFORD HARBOR SEDIMENTS
Air Stripping
Soil Aeration
Carbon Adsorption
Flocculatbn/Precipitatbn
Evaporation
Centrifugation
Extraction
Filtration
Solidification
Sediment
Matrix
No
Yes
No
No
Yes
Yes
Yes
Yes
Yes
Water
Matrix
Yes
No
Yes
Yes
Yes
No
No
No
No
For
PCB
Treatment
No
No
Yes
Yes
No
No
Yes
No
Yes
For
Metal
Removal
No
No
No
Yes
No
No
No
No
Yes
PHYSICAL TECHNOLOGIES CONSIDERED
FOR NEW BEDFORD HARBOR SEDIMENTS (cont.)
Granular Media Filtration
In Shu Adsorption
Ion Exchange
Molten Glass
Steam Stripping
Supercritical Extraction
Vitrification
Particle Radiation
Microwave Plasma
Sediment
Matrix
No
Yes
No
No
No
Yes
Yes
No
No
Water
Matrix
Yes
No
Yes
No
Yes
No
No
No
No
For
PCB
Treatment
No
Yes
No
Yes
No
Yes
Yes
Yes
Yes
For
Metal
Removal
Yes
No
Yes
No
No
No
Yes
No
No
8-4
-------
PHYSICAL TECHNOLOGIES CONSIDERED
FOR NEW BEDFORD HARBOR SEDIMENTS (cont.)
Crystallization
Dialysis/Electrodialysis
Distillation
Resin Adsorption
Reverse Osmosis
Ultrafiltration
Acid Leaching
Catalysis
Sediment
Matrix
No
No
No
No
No
No
Yes
No
Water
Matrix
Yes
Yes
Yes
Yes
Yes
No
No
No
For
PCB
Treatment
No
No
No
No
No
No
No
No
For
Metal
Removal
No
No
No
Yes
Yes
No
Yes
No
CHEMICAL TECHNOLOGIES CONSIDERED
FOR NEW BEDFORD HARBOR SEDIMENTS
Alkali Metal Dechlorination
Alkaline Chlorination
Catalytic Dehydrochlorination
Electrolytic Oxidation
Hydrolysis
Sediment
Matrix
Yes
No
No
No
No
Water
Matrix
No
No
No
No
Yes
For
PCB
Treatment
Yes
No
Yes
No
No
For
Metal
Removal
No
No
No
No
No
CHEMICAL TECHNOLOGIES CONSIDERED
FOR NEW BEDFORD HARBOR SEDIMENTS (cont.)
Chemical Immobilization
Neutralization
Oxidation/Hydrogen Peroxide
Ozonation
Polymerization
Ultraviolet Photolysis
Sediment
Matrix
Yes
Yes
Yes
No
Yes
No
Water
Matrix
No
No
Yes
No
No
No
For
PCB
Treatment
No
No
No
No
No
Yes
For
Metal
Removal
Yes
No
No
No
No
No
8-5
-------
THERMAL TECHNOLOGIES CONSIDERED
FOR NEW BEDFORD HARBOR SEDIMENTS
Electric Reactors
Fluidized Bed Reactors
Fuel Blending
Industrial Boilers
Infrared Incineration
In Situ Thermal Destruction
Liquid Injection Incineration
Sediment
Matrix
Yes
Yes
No
No
Yes
No
No
Water
Matrix
No
No
No
No
No
No
No
For
PCB
Treatment
Yes
Yes
Yes
Yes
Yes
Yes
Yes
For
Metal
Removal
No
No
• No
No
No
No
No
THERMAL TECHNOLOGIES CONSIDERED
FOR NEW BEDFORD HARBOR SEDIMENTS (cont.)
Molten Salt
Multiple Hearth Incineration
Plasma Arc Incineration
Pyrolysis Processes
Rotary Kiln Incineration
Wet Air Oxidation
Supercritical Water Oxidation
Sediment
Matrix
No
Yes
No
Yes
Yes
No
Yes
Water
Matrix
No
No
Yes
No
No
Yes
Yes
For
PCB
Treatment
Yes
Yes
Yes
Yes
Yes
No
Yes
For
Metal
Removal
No
No
No
No
No
No
No
8-6
-------
Extraction Technologies
Mr. Dennis Timberlake
U.S. Environmental Protection Agency
Cincinnati, Ohio
Extraction technologies remove organic or metallic contaminants from sediments but do not destroy or chemically
alter contaminants. Effluent streams will be much more concentrated with contaminants than was the original
sediment. Extraction technologies should be viewed as one part of a treatment train since organic contaminants
still need to be destroyed after extraction. The contaminant-rich effluentfrom extraction technologies can be treated
by any of a number of thermal, physical/chemical, and/or biological treatment technologies. By concentrating the
contaminants in a smaller volume of sediment or residual, a significant cost savings may be realized.
Traditionally, the term "extraction" has referred to chemical extraction but as used here it refers to a larger group
of technologiesthat essentially achieve volume reduction by removing a contaminant from a waste stream and then
concentrating it. For example, soil washing is usually thought of as being separate from chemical extraction, but
using the present definition soil washing is considered an extraction technology.
Soil washing is a water based, volume reduction process in which contaminants are extracted and concentrated
into a small residual portion of the original volume using physical and chemical means. The principal process
involves transfer of the contaminants from the sediment to the wash water and their subsequent removal from the
water. The small volume of contaminated residual concentrate is then treated by destructive or immobilizing
processes. By changing steps in the process, soil washing may be made amenable to a variety of site
characteristics.
Chemical extraction involves removing contaminants from sediment by dissolution in a solvent that is later
recovered and treated. A variety of chemical extraction processes exist and they employ a number of solvents.
Solvents are chosen based on contaminant solubility and on whether the contaminant is organic or inorganic.
Chemical extraction processes include CF Systems Organic Extraction Process and Resources Conservation
Corporation's Basic Extraction Sludge Treatment (BEST).
9-1
-------
DEFINITION OF EXTRACTION
The use of solvents to separate contaminants from
solvents.
ADVANTAGES
Volume reduction
LIMITATIONS
Contaminants are not destroyed.
Not a stand-alone technology.
9-2
-------
EXTRACTION
\
Soil Washing Chemical Extraction
DEFINITION OF SOIL WASHING
A water-based process for mechanically scrubbing
soils to remove undesirable contaminants.
MECHANISMS FOR
REMOVING CONTAMINANTS
Dissolving or suspending them in the wash
solution
Concentrating them into a smaller volume of
soil through particle size separation techniques.
9-3
-------
APPLICABILITY OF SOIL WASHING ON
ORGANIC CONTAMINANTS
Sandy/ Sitty/Clay
Gravelly Soils Soils
Hatogenated volatiles 2 1
Hatogenated semivolatiles 1 1
Nonhatogenated semivolatiles 2 1
RGBs 1 1
Pesticides (hatogenated) 1 1
Dtoxins/Furans 1 1
Organic cyanides 1 1
Organic corrosives 1 1
2 - Good to Excellent Applicability; 1 - Moderate to Marginal
Applicability; 0 - Not Applicable
APPLICABILITY OF SOIL WASHING ON
INORGANIC & REACTIVE CONTAMINANTS
Sandy/ Silty/Clay
Gravelly Soils Soils
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganice cyanides
Oxidizers
Reducers
2 1
2 1
0 0
1 1
1 1
1 1
1 1
1 1
2 - Good to Excellent Applicability; 1 - Moderate to Marginal
Applicability; 0 - Not Applicable
KEY PHYSICAL PARAMETERS
Particle Size Distribution
>2mm
0.25 - 2 mm
0.063 - 0.25mm
< 0.063mm
Moisture Content
Pre-treatment required
Effective Soil Washing
Limited Soil Washing
Difficult Soil Washing
9-4
-------
KEY CHEMICAL PARAMETERS
Organics - concentration
volatility
partition coefficient
Metals
Humic Acid
SOIL WASHING APPLICABLE
PARTICLE SIZE RANGE
Clay . Silt , Sand
1001 LH 1
Gravel
Stone
50
III
increasing particle size
LIMITATIONS
Silt/Clay
Hydrophobic Contaminants
Mixtures
9-5
-------
AQUEOUS SOIL WASHING PROCESS
VOIMfbs
ComamkuMd
Sol
Trtattd Air Emissions
M*»tpW«lsc
Extracting Agsnt(i)
(Surt«cunt«.»1c.)
Sol | Soil
Preparation
(1)
SludgtV
Denominated Fines
Ov«tslz»d Rsjscts
DEFINITION OF CHEMICAL EXTRACTION
An organic solvent-based process for separating
contaminants from soils.
E
EFFECTIVENESS OF
XTRACTION ON ORGANIC
Treatability Groups
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides (halogenated)
Dtoxins/Furans
Organic cyanides
Organic corrosives
SOLVENT
CONTAMINANTS
Effectiveness
1
1
1
1
2
1
1
1
1
2 - Good to Excellent Applicability; 1 - Moderate to Marginal
Applicability; 0 - Not Applicable
9-6
-------
EFFECTIVENESS OF SOLVENT
EXTRACTION ON INORGANIC & REACTIVE
CONTAMINANTS
Treatability Groups
Volatile metals
Nonvolatile metals
Asbestos
Radioactive Materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Effectiveness
0
0
0
0
0
0
0
2 - Good to Excellent Applicability; 1 - Moderate to Marginal
Applicability; 0 - Not Applicable
LIMITATIONS
Metals
Residual Solvent
Solvent Selection
SOLVENT EXTRACTION PROCESS
t
*. Emb
* Co
%$* I »• Treated Emissions
4 Recycled Solvent (4) |
Excavate 1 fc Waste (1 ) 1 k
• * Preparation I '
Extr^or I ,
Separator 1
(3) 1
nr**h'e L^Concentrafed
ContSnts Contaminants (5)
9-7
-------
r CF SYSTEMS
Solvent - liquified hydrocarbon gases
Pumpable slurry
<1/8" particle diameter
CF SYSTEMS ORGANIC
EXTRACTION SYSTEM
Compressor
Recycled Solvents
Solvents and Organics
Solvent
l
actor
1
— »»
Separator
Solvent
Recovery
Still
^f^
1
\ i
Solids and Water
Solid/Liquid
Separator
• Solids
Water
Resources Conservation Corporation's
BASIC EXTRACTION SLUDGE
TREATMENT (BEST)
Solvent - aliphatic amines
Batch operation
<1" particle diameter
9-8
-------
PCB SAMPLES TESTED IN
RCC's LABORATORY
Raw Sample
River Sediment "B"
Superfund B (#13)
Harbor Sediment "B"
Harbor Sediment "C"
Harbor Sediment "D"
Harbor Sediment NB-A
Harbor Sediment NB-B
PCB
(mg/kg)
960
83
20,000
30,000
430
5,800
16,500
Phase
Composition
Oil% Water % Solids %
26
44
3
5.6
0.38
1.9
4.3
17
40
22
62
47
69
51.6
83
16
75
32
53
29
44.1
PCB SAMPLES TESTED IN
RCC's LABORATORY
River Sediment "B"
Superfund B (#13)
Harbor Sediment "B"
Harbor Sediment "C"
Harbor Sediment "D"
Harbor Sediment NB-A
Harbor Sediment NB-B
PCBs
Oil
(mg/kg)
N/A
N/A
970,000
550,000
N/A
280,000
360,000
in Product Fraction
Water
(mg/kg)
N/A
N/A
<.006
N/A
N/A
<.005
<.005
Solids
(mg/kg)
40
1.0
27
94
32
35
75
%
Removal
96.5%
99.8%
99.9%
99.9%
96.0%
99.4%
99.8%
OTHER CHEMICAL
EXTRACTION TECHNOLOGIES
Extralesol
Low Energy Extraction Process (LEEP)
9-9
-------
Thermal Technologies
(Incineration, LT Desorption, Recovery Systems)
Dr. George Hytantis
International Waste Management Systems
Knoxvile, Tennessee
As a result of the increased awareness surrounding the proper management of hazardous waste disposal and
cleanup from a future liability standpoint, the use of thermal technologies for the treatment of contaminated
sediments is supplanting other remedial actions, most notably land disposal. The lack of sufficient cost and
performance information on other promising treatment technologies, such as various biotreatment technologies,
has also contributed to the popularity of well-established, yet often costly thermal treatments for the destruction of
hazardous wastes.
Types of processes used to thermally remediate soils and sediments include rotary kiln incineration, pyrolysis,
infrared incineration, circulating bed combustion, and low temperature thermal desorption. Ideally, the ultimate goal
of thermal combustion is to convert waste materials into benign end-products (CO2, H2O vapor, SO2, NOX, HCL, and
ash) using high temperature oxidation under controlled conditions. The suitability of contaminated sediments for
the application of thermal treatment processes is determined by the physical and chemical makeup of the material
and by the volume to be treated. These characteristics impact:
1. The extent of screening required.
2. The amount of dewatering required and the selection of a dewatering method.
3. The type of thermal treatment utilized.
4. * Air pollution control system design.
5. Treatment of residual ash prior to final disposal.
The applicability of a number of thermal processing methods on sediments have already been demonstrated in
private and government sponsored cleanups. Although incineration and other thermal technologies have been
shown to be among the most effective treatment technologies for hazardous and toxic waste destruction, costs tend
to be high due to the intensive energy requirements and subsequent disposal of ash and slag.
10-1
-------
RANGE OF CURRENT COST FOR
ROTARY KILN INCINERATION
Volume(CY) Cost ($ PER CY)
<6750
6950-20250
20250-40500
>40500
675-2025
405-1215
270-810
135-540
UNIT COST ESTIMATES FOR
STEPS INVOLVED IN TREATMENT
AND OF DISPOSAL OF
PCB-CONTAMINATED SEDIMENTS
Operation Cost ($ PER CY)
Dredging
Transport
Storage
Redeposition
15
10-96
8
25-375
Afterburner
Rotary Kiln and an Afterburner.
10-2
-------
Pyrolysis Schematic
Infrared Incineration Process Flow Diagram
STACK
COMBUSTOR
Circulating Bed Combustor Schematic
10-3
-------
Bioremediation
Dr. Carol D. Litchfield
Foster Wheeler Enviresponse, Inc.
Livingston, NJ
Bioremediation is a complex process that converts organic contaminants into microorganism biomass and simpler,
"waste" substances. In complete conversion the waste products are harmless metabolic by-products, such as CO2,
CH4, water, and inorganic salts. In incomplete conversion the waste products are organic compounds that are
simpler than the original contaminants and that are hopefully less toxic. In most cases, bacteria and/or fungi are
the principle types of organisms involved in bioremediation.
The rate and completeness of bioremediation processes may be improved in four ways: enhancement of the
degradative potential of the natural microbial assemblages through nutrient and electron acceptor addition;
introduction of specially selected microbial strains with distinctive degradative capacities; application of enzymes;
and vegetative uptake. Enhancement of the natural microbial assemblages is the most commonly used bioreme-
diation technique.
The rate of biodegradation may often be limited by the bioavailability of the contaminants and the presences of
heavy metals. Sediment properties which impact bioavailability influence the interaction between sediment and
contaminants. These properties include type and amount of clay, cation exchange capacity, organic matter content,
pH, oxidation-reduction conditions, and the conductivity of the water. Pre-treatments which may increase the
bioavailability of contaminants include grinding to increase the surface area, adding a bulking material, and soil
washing. Heavy metals may often be removed through pre-treatment methods; biosorption of metals using bacterial
or algal cells is one possible method.
The biodegradation of contaminated sediments can be done in two ways: biotreatment after dredging the polluted
sediments from the waterway or leaving the sediments in place and treating in situ.
Dredging allows four types of biological treatment processes: composting, bioslurries, solid phase treatment, and
land-farming. Composting involves the storage of the target sediment with a bulking agent, such as hay or wood
chips. Bioslurries require the production of a slurry which is then treated in a bioreactor in orderto maintain intimate
mixing of the sediment with the microorganisms. In solid phase treatment, the dredged materials are placed in
treatment cells and moisture and nutrients controlled through mixing and nutrient application. In land-farming, the
dredged materials are mixed with surface soils to a depth of six to nine inches by placing the dredged material on
the soil surface and then tilling. The area may potentially be farmed if the contaminant levels are reduced to safe
levels.
In situ bioremediation is the enhancement of naturally occurring biodegradative processes. It relies on the addition
of nutrients and an electron acceptor to increase the rate of degradation. If oxygen is to be added as the electron
acceptor, the amounts of iron and manganese present in the sediment are important considerations.
To date, most of the work on the bioremediation of sediments has involved bench scale treatability studies. Rates
for bioremediation in the field will likely be slower than in the laboratory where conditions can be optimized.
11-1
-------
THE BIOREMEDIATION PROCESS
Organic Contaminant
+
Action of Fungi and Bacteria
Microorganism Biomass + Harmless Byproducts
(C02, CH4, salts)
ORGANISMS CAPABLE OF BIOREMEDIATION
Obligate Anaerobic Bacteria (Clostridium, Desulfovibrio,
Methanogens Consortium)
Heterotrophic Aerobic Bacteria (Pseudomonas Arthrobacter,
Acinetobacter, Micrococcus, Achromobacter)
Photosynthetic Bacteria (Chromatium, Rhodopseudomonas,
Athiorhodaceae)
Oligotrophic Bacteria (Cautobacter, etc.)
Algae (Chlorella, etc.)
Cyanobacteria (Blue - Green Algae)
Actinomycetes (Nocardia, Mycobacterium)
Fungi (Fusarium, Aspergillus, Penicillium)
COMPOUNDS SUSCEPTIBLE
TO BIOREMEDIATION
CLASSES OF
CONTAMINANTS
Halogenated and
Nonhatogenated Alphatics
Halogenated and
Nonhatogenated Aromatics
Polycyclic Aromatics
Halogenated Polycyclic
Aromatics
Pesticides
Nitrosamines
Phthalate Esters
Nitro and Chlorophenols
PRIORITY POLLUTANT
EXAMPLE
Methylene Chloride
Chlorobenzene
Anthracene
2-Chloronaphthalene
Dieldrin
N-Nitrosodiphenylamine
Bis (2-Ethylhexyl) Phthalate
Pentachlorophenol
11-2
-------
DETERMINANTS OF THE RATE OF
MICROBIAL BIOREMEDIATION
1. Presence of microorganisms
2. Availability of nutrients
3. Availability of contaminants
4. Redox conditions
5. Water activity
6. Environmental factors.
METHODS OF BIOREMEDIATING
REMOVED SEDIMENTS
1. Composting
2. Bioslurries
3. Solid Phase Treatment
4. Land Farming.
SOLID PHASE BIOREMEDIATION
Pre-Treatment
Sediment
Screening
Oversized Material
to Special Handling
Solid-Phase
Treatment
11-3
-------
SOLID PHASE BIOREMEDIATION
Treatment
Perforated
Drain Pipe
Solid-Phase
Treatment
Sediment Layer
/ / /Compacted Clay/
Sprinkler
System
IMPORTANT SITE CHARACTERISTICS
FOR IN SITU BIOREMEDIATION
1. Characteristics
2. Microorganisms present and their capability to degrade
the contaminants
3. Type of contaminant
4. Bioremediation products
5. Depth, profile, and areal distribution of constituents in
the sediments
6. Sediment properties for biological activity
7. Sediment characteristics
8. Hydrodynamics of the site
TYPES OF IN SITU
BIOREMEDIATION APPROACHES
1. Enhancement of the natural bioremediative
potential
2. Introduction of exogenous, specialized
microorganism application
11-4
-------
TWO-STEP COMBINED ANAEROBIC/
AEROBIC PROCESS TO BIOREMEDIATE
HALOGENATED ORGANICS
anaerobic
bacteria
aerobic
bacteria
cells
C02
+
H2O
ENHANCEMENT EXAMPLES
1. Increasing the sediment's dissolved oxygen
levels.
2. Providing alternative electron acceptors.
3. Mixing the sediments to improve bacterial
access to contaminants.
MICROBIAL CHARACTERISTICS TO BE
CONSIDERED PRIOR TO USING
EXOGENOUS ORGANISMS
1. Ability of the microorganisms to survive in a
foreign environment.
2. Ability of the microorganisms to move through-
out the contaminated site.
3. Ability of the microorganisms to retain their
activity.
4. Assurance that the microorganisms are non-
pathogenic to humans and the ecosystem.
11-5
-------
Solidification/Stabilization
Mr. Ed Barth Mr. Tommy E. Meyers
U.S. Environmental Protection Agency U.S. Army Corps of Engineers
Cincinnati, Ohio Vicksburg, Mississippi
Solidification/stabilization, as a type of containment technology, immobilizes and/or isolates contaminated
sediments. Solidification/stabilization refers to the use of additives or processes to transform hazardous waste into
a more manageable or less toxic form.
Solidification/stabilization functions both physically and chemically. Solidification is a physical process which refers
to the conversion of a liquid or semi-solid to a solid, resulting in a substantial reduction of surface area and, thus,
contaminant leaching. Solidification is considered an effective process in the immobilization of both metals and
inorganics. Stabilization is a chemical process which refers to the alteration of the chemical form of contaminants.
Generally, stabilization is considered an effective process in the immobilization of metals, but not organics. In fact,
organics may actually interfere with solidification/stabilization setting reactions.
The applicability of solidification/stabilization processes to the sediments of concern is determined by chemical and
physical analysis. Several leach tests are available for this purpose. Listed wastes requires the Toxicity
Characteristics Leaching Procedure (TCLP). Additional leaching tests may be chosen from American National
Standards Institute (ANSI) procedures appropriate for the contaminant. Newer procedures, such as the Standard
Batch Leachate Test (SBLT), are constantly being reviewed and accepted according to the need or circumstance.
Physical testing, aimed at such product characteristics as bearing capacity, trafficability, and permeability, is
accomplished through established engineering tests. For example, ratios of waste to binder in each system are
evaluated using the Unconfined Compressive Strength (UCS) Test. Bulk density, permeability, and moisture
content are also commonly tested to determine the degree of solidification/stabilization.
Solidification/stabilization applications to contaminated sediments include:
1. Marathon Battery Company site in the Village of Cold Spring, New York.
2. The Upper Acushnet River Estuary in New Bedford, Massachusetts
3. The navigation channel at Indiana Harbor, Indiana.
4. Buffalo River sediment, New York.
5. Halby Chemical site in Wilmington, Delaware.
Solidification/stabilization has been tested at the bench-scale level or better at these sites. Contaminants ranged
from organics, including PCBs, to metals, including cadmium, cobalt, nickel, lead, copper, chromium, and arsenic.
12-1
-------
WHY USE S/S?
Water Content
Shear Strength
Need to
t shear strength
I compressibility
I permeability
for land disposition
200-300% (slurry)
0
MODEL OF CONVECTIVE TRANSPORT (CT)
TO DIFFUSIVE TRANSPORT (DT)
II
CT
DT
III
L-
P
o s
IV
D
1/2
IMPORTANT RATIOS
Binder
Waste
Water
Total Solids
.1-.5
.4
12-2
-------
COSTS
Binder
30% Solids:
2000 Ibs x .3 = 600 Ibs solids
10%BS:
600 Ibs x .1 60 Ibs binder
$50/T = $.025/lb:
60 Ibs x .025/lb = $1.50
Labor
Handling
Equipment
SLT
Plot cumulative release with time
Compare to WQC
Each step represents x pore volumes
GRAIN SIZE DISTRIBUTION
MASS
CLAY
SILT SAND GRAVEL
GRAIN SIZE
12-3
-------
DISTRIBUTION OF METALS
IN SIZE FRACTIONS
r
As
Pb
Cd
Cr
Cu
Hg
Zn
Coarse
1.0
3.2
.06
4.8
3.7
0.17
17
Mixed Fine
1.1 111
7.0 447
.51 13
4.6 452
3.0 385
0.14 13
12 1920
(from Rizkaliah)
SEDIMENT SHEAR STRENGTH
no montmorillinite
low organic content
Binder
FA (2-10%)
L(2-10%)
C(2-10%)
C/FA(2-10%)
Shear Strength (undrained)
<10KN/m
10KN/m
high
high
(from Rizkaliah}
MARATHON BATTERY SEDIMENTS
32000 CY
24% Solids
pH 6.6-6.8
EP TOX
ASTM G21
ASTM G22
12-4
-------
MARATHON
Raw
Vendor
Vendor
Vendor
Vendor
BATTERY S/S
EP TOX (mg/l)
Cji C_s Eb_
.01 .01 .14
.01 .02 .10
0.1 .02 .02
0.08 .13 .29
RESULTS
M
.53
.88
.21
1.3
B. R. SEDIMENTS (jig/g)
O&G 9100
TOC 21,400
Zn 151
Pb 81
PAH 5.9 mg/l
B. R. S/S RESULTS
T UCS with time (>50 psi)
t Cr, Cu in TCLP
i Pb, Ni, An in TCLP
Cr, Cu, Pb, Ni below WQC in SLT
no conclusion on PAHs
12-5
-------
INDIANA HARBOR S/S RESULTS
As, Pb, Cr, Zn leaching decreased in SLT
Fly ash, lime did not reduce leaching
12-6
-------
Residual Disposal Methods
(Confined Disposal Methods, Capping and Landfills)
Dr. Robert P. Gambrell and Dr. William H. Patrick, Jr.
Laboratory for Wetland Soils and Sediments
Louisiana State University
Baton Rouge, Louisiana
Disposal alternatives for dredged material consist of unrestricted and restricted options. Most dredged materials
are the product of maintenance dredging; the majority of this material is not contaminated and is thus suitable for
unrestricted disposal. Unrestricted alternatives include unrestricted open-water disposal ("dumping"), sanitary
landfills, and beneficial uses. Restricted alternatives suitable for contaminated sediments include capping, confined
disposal facilities (CDF), and hazardous landfills. Pre-testing is essential in deciding on a particular restricted
alternative and on the proper design of that alternative.
The principal concept for reducing long-term environmental effects associated with open water disposal is to "cap"
(cover or encapsulate) the contaminated material with clean dredged material. Contaminated sediments can be
capped with clean sediments in situ, or they can be dredged, moved, and then capped. By keeping contaminated
sediment in the waterway, stable geochemical and geohydrologic conditions are maintained in the sediment,
minimizing release of contaminants to surface water, ground water, and air. Placement of a clean cap or cover on
top of the contaminated sediment reduces diffusion and convection of contaminants into the water column and
prevents bioperturbation or uptake by aquatic organisms. Capping could also be considered for disposal of residual
solids from treatment or pre-treatment processes. Capping options include level bottom capping and contained
aquatic disposal (CAD).
Capping techniques may not be suitable for the most highly contaminated sediments. They may be favorable in
some applications because of ease of implementation, lack of upland requirements, comparatively low cost, and
highly effective contaminant containment efficiency. The principal disadvantages for open water disposal options
are the concern for long term stability and effectiveness of the cap and the complications that may occur if
remediation of the disposal site should be required in the future. Capped sites require monitoring and maintenance
to ensure site integrity.
CDFs are engineered structures enclosed by dikes and designed to retain dredged material. They may be located
upland (above the water table), partially in the water near shore, or completely surrounded by water. The primary
goal of CDF design is minimization of contaminant loss. Contaminants are potentially lost via leachate through the
bottom of the CDF, seepage through the CDF dikes, volatilization to the air, and uptake by plants and animals living
or feeding in the CDF. A variety of linings have been used to prevent seepage through the dike walls. The most
effective are clay or bentonik-cement slurries, but sand, soil, and sediment linings have also been used. Caps are
the most effective way to minimize contaminant loss from CDFs through contaminant volatilization and plant and
animal uptake.
Offsite landfills may be considered for highly contaminated material or for treated residuals. There are two types
of landfills: sanitary and hazardous. Highly contaminated sediments or sediment wastes may be inappropriate for
sanitary landfills and must be disposed of in hazardous landfills, which will add greatly to total treatment cost.
Because dredging often results in large quantities of dredged material with high water contents, dredging may not
be compatible with landfill disposal. Large quantities of dredged material and high water content both increase the
volume of material the landfill must accommodate and thus drive up costs. If use of a landfill is required .then specific
pre-treatment options (such as dewatering) and/or treatment options may have to be considered.
13-1
-------
DISPOSAL OF DREDGED MATERIAL,
CONTAMINATED SEDIMENTS, AND
TREATED SEDIMENTS
R.P. Gambrell
W.H. Patrick, Jr.
Laboratory for Wetland Soils and Sediments
Louisiana State University
Baton Rouge, Louisiana
Disposal alternative for
contaminated sediments refer
to the various possible
placement options to minimize
contaminant release.
Disposal alternatives apply to:
1. Untreated dredged sediments
2. Sediments treated to remove contaminants
3. Sediments treated to immobilize contaminants
13-2
-------
DISPOSAL OPTIONS
1. Restricted
2. Unrestricted
RESTRICTED OPTIONS
1. Capping
2. Confined Disposal Facility
3. Landfill
4. Disposal site selection and management
to maintain a contaminant immobilizing
environment.
UNRESTRICTED OPTIONS
1. Open water disposal
2. Sanitary landfills
3. Beneficial uses
13-3
-------
CAPPING
Covering or encapsulating contaminated
sediments, usually in deep, quiescent water, with
clean dredged material to isolate and immobilize
contaminants.
Capping may be applicable to contaminated
sediments in situ, but it is more often implemented
after contaminated sediments have been dredged
and transported to a disposal site.
ADVANTAGES TO CAPPING:
1. Reduced transport of dredged material.
2. Sometimes applicable in situ.
3. Contaminated sediments are maintained in a
biogeochemical environment that favors
contaminant immobilization.
4. Contaminated sediments are isolated from
significant diffusive losses or contact with
benthic organisms.
5. Expensive upland disposal sites may not be
required.
IMPORTANT CAPPING
CONSIDERATIONS:
1. Current velocity
2. Water depth
3. Salinity and temperature stratifications
4. Bathymetry (bottom contours)
5. Dispersion and mixing
6. Navigation and other location factors
(Culinane, etal., 1989)
13-4
-------
VARIANTS OF CAPPING:
1. Level bottom capping employs stable mound-
ing of contaminated dredged material which
can then be covered with clean sediments.
2. Contained aquatic disposal (CAD) employes
an exisiting depression, excavation of a
subaqueous disposal pit, or construction of
submerged confining dikes (Palermo et al.,
1989). '
SUBAQUEOUS DISCHARGE METHODS.
1. Minimizes potentially adverse impacts of
capping
2. Increases placement accuracy
(Averett et al., 1990)
LEVEL BOTTOM CAPPING
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CONTAINED AQUATIC DISPOSAL
DERRICK
DISCHARGE
WATER SURFACE
LINE ^^
=N.« «\
•I ^^-—SUBMERGED DIFFUSER
JL. ^-ICLEAN SAND, ETC.)
CAPPING CONCERNS
1. Long-term stability and effectiveness of the
cap
2. Difficulties if future remediation of the disposal
site is required (Averett et al., 1990)
3. Maintenance and long-term monitoring may
be required (Palermo et al., 1989)
CONFINED DISPOSAL FACILITY (CDF):
CDFs are structures designed to retain dredged
material. Their primary function is to minimize
contaminant losses.
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CDF CONSTRUCTION:
Large cells enclosed by dikes
Smaller cells or multiple cells may be used for
separating water
Linings are designed to minimize contaminant
loss by seepage (clay and bentonite-cement
linings are most effective, but soil, sediment,
and synthetic linings have been successfully
used).
CDF LOCATION:
1. Upland (above water table)
2. Near shore partially within water table zone
3. Island in a water body
POSSIBLE ROUTES OF CONTAMINANT
LOSS FROM A CDF:
1. Vertical seepage through bottom
2. Lateral seepage through dikes
3. Volatilization
4. Uptake by plants and animals
(Garbaciak, 1990; Miller, 1990)
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Capping a CDF with clean sediment
or another liner material will
minimize uptake losses and
may reduce volatilization losses.
TYPES OF LANDFILLS:
1. Sanitary
2. Hazardous waste
LIMITATIONS OF HAZARDOUS WASTE
LANDFILLS FOR DREDGED MATERIAL
DISPOSAL:
1. High costs
2. Available capacity limited for typical large
volume dredging projects
3. Dewatering and other pre-treatments may be
required.
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CONSIDERATIONS FOR SELECTING
DISPOSAL ALTERNATIVES FOR
CONTAMINATED SEDIMENTS
1. The kinds and amounts of contaminants present.
2. Physical, chemical, and biological characteristics of the
dredged sediments.
3. The particular risk represented by the contaminants.
4. The disposal options available based on technological,
economic, regulatory and environmental considerations.
5. The environmental chemistry and fate of the contaminants
under conditions of the various disposal alternatives.
MAJOR DISPOSAL ALTERNATIVES:
A. Subaqueous Placement
B. Application to Intertidal Sites for Disposal
or Productive Use
C. Upland Application
SUBAQUEOUS DISPOSAL
A. Disposal not in conflict with important economic or
ecological productivity
1. Confined Disposal
a. Stable mounding with option for capping
b. Confined in a depression, constructed pit, or by
underwater berms with capping
2. Unconfined - wide dispersal with apparent loss from
disposal area
B. Application to important ecological zones.
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APPLICATION TO INTERTIDAL SITES
A. Habitat development
1. Confined by boundary structure - resistant to erosion
2. Unconfined - some erosion and some consolidation
(i.e., mudflat, marsh or island construction or
enhancement)
B. Non-biological purposes
1. Shoreline stabilization, modification
2. Confined by boundary structure
UPLAND APPLICATION
A. Long-term confinement for disposal purposes
B. Interim confinement
C. Unconfined upland
D. Habitat development
E. Agricultural soil amendment and land reclamation
F. Use for fill and other construction or engineering
purposes.
MANAGEMENT PRACTICE APPLICABLE
TO DISPOSAL ALTERNATIVES
• Scheduling to coincide project with the least sensitive
portions of the life cycle of potentially affected organisms.
Applicable to subaqueous, intertidal.
• Covering with uncontaminated material (capping).
Applicable to subaqueous, intertidal, upland.
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MANAGEMENT PRACTICE APPLICABLE
TO DISPOSAL ALTERNATIVES (cont.)
• Use of confinement structures to minimize dispersion and
transport by erosion and currrents.
Applicable to subaqueous, intertidal, upland.
• Pre-treatment to remove or immobilize contaminants prior
to long-term disposal or use.
Applicable to subaqueous, intertidal, upland.
MANAGEMENT PRACTICE APPLICABLE
TO DISPOSAL ALTERNATIVES (cont.)
• Managing plant and animal populations to reduce uptake.
Applicable to intertidal, upland.
• Reducing suspended solid loads in effluents.
Applicable to subaqueous, intertidal, upland.
• Reducing leaching losses.
Applicable to intertidal, upland.
ftU.S. GOVERNMENT PRINTING OFFICE;! 991 -5i»8 -187/ 25606
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