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ITRC Internet-based training and Technical and Regulatory Guidance

Incorporating Bioavailability Considerations into the Evaluation of Contaminated

Sediment Sites (CS-1, 2011)

Welcome – Thanks for joining this ITRC Training Class

Sponsored by: Interstate Technology and Regulatory Council (www.itrcweb.org) Hosted by: US EPA Clean Up Information Network (www.cluin.org)

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Copyright 2014 Interstate Technology & Regulatory Council, 50 F Street, NW, Suite 350, Washington, DC 20001

3ITRC (www.itrcweb.org) – Shaping the Future of Regulatory Acceptance

Host organization Network

• State regulators All 50 states, PR, DC

• Federal partners

• ITRC Industry Affiliates Program

• Academia• Community stakeholders

Disclaimer

• Full version in “Notes” section

• Partially funded by the U.S. government

ITRC nor US government warrantee material

ITRC nor US government endorse specific products

• ITRC materials copyrighted

Available from www.itrcweb.org

• Technical and regulatory guidance documents

• Internet-based and classroom training schedule

• More…

DOE DOD EPA

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Meet the ITRC Instructors

Greg NeumannNew Jersey Department of

Environmental Protection

Trenton, New Jersey 609-633-1354greg.neumann@

dep.nj.gov

Steve CloughHaley & Aldrich, Inc.Manchester, New Hampshire 603-391-3341sclough@

haleyaldrich.com

Diana MarquezBurns & McDonnell

Engineering CompanyKansas City, Missouri816-822-3453dmarque@burnsmcd.com

John CargillDelaware Department of

Natural Resources and Environmental Control

New Castle, Delaware 302-395-2622john.cargill@state.de.us

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ITRC Sediments Team

States• Alabama• California• Delaware• Florida• Kentucky • Michigan• New Jersey• New York• Oklahoma• Oregon• Pennsylvania • Texas• Washington

Universities• Purdue• U. of Florida• U of Texas

Federal Agencies• Navy• Army• AFCEE• EPA Including

Region 2 & 5• USACE• DOE

Community Stakeholders

• Mtn Area Land Trust

• AAEJCIndustry

• AMEC • Alta

Environmental• AECOM• AFMC• Alcoa • Arcadis

• Battelle • Beacon• Brown and

Caldwell • Bootheel

LEPC• Burns &

McDonnell• BP • CDM

CH2MHill• CETCO • Columbia

Analytical• DuPont

Geosyntec • EMCBC • Environ • ExxonMobil • Haley &

Aldrich, Inc

• Kleinfelder• Langan

Engineering• LATA-Kemron• Malcolm Pirnie• M.W. Global• MWH • RegTech • Neptune and Co.• SAIC W.L. • Gore• SRNL• Test America

labs• Tetra Tech • URS• WRI• SPAWAR • SSC• Shell

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ITRC Web-based Guidance Outline

Introduction and background on bioavailability

Overview of bioavailability processes

Bioavailability pathway exposure assessment• Screening• Background• Pathway exposure assessment

Benthic invertebrates Fish and water column

invertebrates Wildlife Plants Human health

Risk management decision-making

http://www.itrcweb.org/contseds-bioavailability/

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What You Will Learn…

What is bioavailability? When do we apply bioavailability

adjustments? What are the available tools and how do we

use them? How do we use the information to make risk

management decisions? You will NOT learn how to conduct a Risk

Assessment that incorporates bioavailability.

The intended users of this guidance are individuals who have a working knowledge of contaminated sediment management but seek additional information about bioavailability.

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The Problem!

US EPA reports – 10% (1.2 billion yds3) of U.S. sediment underlying surface water pose a potential ecological or human health risk

Cost of clean-up is in the trillions Contaminant concentration in

sediment and actual exposure is not a direct relationship

Bioavailability will give a more accurate characterization of exposure

USACE 2008. Technical Guidelines for Environmental Dredging of

Contaminated Sediments

Conventional Clamshell

Excavator

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What is Bioavailability?

“…individual physical, chemical, and biological interactions that determine the exposure of plants

and animals to chemicals associated with soils and sediment (National Research Council, 2003).”

Specifically, bioavailability addresses the fact that only a fraction of the contaminant concentration present in the environment may be taken up or

result in an effect on an organism!

10How can Bioavailability Make a Difference?

If contaminants are not physically accessible, or chemically or biologically available, they should not be included in the calculation of risk

Can optimize the extent of cleanup required to be protective

Can provide optimization of remedial approach and cost

Can be an important factor in balancing the risks caused by remedial action

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How is Bioavailability Being Used?

2008 – ITRC Team distributed questionnaire to assess extent bioavailability was used for the development of site cleanup levels

35 case studies collected (Table 9-1 and Appendix D)• Summarized exposure

pathways addressed

• Summarized contaminants evaluated/addressed

• Summarized tools used at each site

• Includes contacts for more information about each site

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Questionnaire Results

Most common exposure pathways evaluated• Benthic exposure

• Human health

• Pelagic exposure Most common tools used to assess bioavailability

• Bulk sediment chemistry

• Tissue sampling (fish, bivalves, other water column receptors)

• Porewater chemistry

• Bioassays of benthic invertebrates

13Risk Management Role in Decision-Making

Risk management integrates the results of the risk assessment with• Technical

• Political

• Legal

• Social

• Economic objectives

Bioavailability is used to make risk management decisions within the• Risk assessment - Section 9.1

• Remedy selection – Section 9.2, Table 9-2

• Remedial design/Implementation – Section 9.2

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Risk Assessment

The assessment of risk to all receptors identified at a contaminated sediment site related to

physical, chemical, and biological processes!

Bioavailability should be used to actively refine conceptual site model (CSM)

Risk assessment will likely involve a “weight of evidence” approach, or “multiple line of evidence” approach• Be aware of sources of variation in

risk assessments• Collect data essential to risk assessment• Analyze to understand exposure and risk• Remember: bioavailability is highly site

specific Be aware of your stakeholder interests,

and communicate with them regularly View ITRC’s Use of Risk Assessment in

Management of Contaminated Sites (Risk-2, 2008) – available from www.itrcweb.org

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Risk Assessment & Bioavailability

Advantages• If contaminants aren’t bioavailable, then they aren’t included

in the evaluation of risk (no exposure)

• Optimization of cleanup goals, with a possible cost reduction

• More effective use of available resources

• Can achieve more accurate defensible cleanup goals while ensuring protection of receptors

Challenges• Uncertain acceptance by regulators, stakeholders, and the

public

• Bioavailability may vary across a site (or operational units)

• Potentially higher site characterization costs

• May take longer to gain full understanding of site conditions

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Remedy Selection

Bioavailability evaluation within risk assessment process will result in selection of remedy that will better address concerns at site

Example: Mocks Pond Case Study• Site history and bulk sediment testing identified

contaminants of potential concern (COPCs) • Further evaluated using bioavailability tools

In-situ pore water metal concentrations Chemical analyses of whole body and fillets of pelagic fish

species

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Remedial Design and Implementation

Risk mitigation, reduction, or removal is ultimate goal of every remedial action

If bioavailability indicates adverse impact to receptors, then design the remedy accordingly

Bioavailability measurement tools can be used to monitor effectiveness of remedy

Reduction in uncertaintywill enhance ability to evaluate monitored natural recovery

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Limitations and Uncertainty

There are uncertainties with data assessment methods and models

Aquatic environments are dynamic, which may alter physical, chemical and biological properties, and therefore bioavailability factors, through time

Stakeholder interests and land usage at or surrounding a site can change over time, thus shifting remedial priorities

Regulatory acceptance cannot be assumed

Just remember . . . Collect data that answers a question about the site Knowing your site and good communication is the key

19Contaminated Sediment Assessment Approach

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Scoping Your Site….Chapter 2

Site history - Due Diligence Site boundaries (extent of

contamination) Contaminants of potential

concern (COPC) Conceptual site model

(CSM) – source, exposure pathway/route, receptors, space, time, fate & transport

21Processes to Consider During Scoping

Physical• Bed Transport• Deposition/ Resuspension• Bioturbation• Advection/diffusion• Grain size COPC distribution• Burial• Temperature

Chemical• Sorption/desorption • Transformation/

degradation• Geochemical (TOC,

salinity, pH, Redox)

Caution – Sediment are mixtures

Biological• Uptake• Biotransformation• Bioaccumulation• Mode of action• Critical body burden

22Example Conceptual Site ModelAnacostia River

FlowDirection Resuspension

Deposition

Tidal Mixing/ Potomac River Surface Water

Suspended Particles

AdsorptionDesorption

Urban Tributaries

• Storm Water• Sewer• Water Treatment

Plant• CSO

Permitted Facility

Discharge

Uncharacterized Point

Discharges

Volatilization Precipitation

Groundwater Recharge

Deep SedimentGroundwater Discharge

BurialEpifauna InfaunaSurface Sediment

Non-Point Surface Run-off

Erosion

Dissolution FlowDirection

Bed Load Transport

Bioaccumulation

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Screening Your Site…Chapter 3

Screening values (e.g. SQVs) are not site specific Conservative values

• Levels below which there is a good probability there is low risk

• Values above screening levels do not imply unacceptable level of risk

Determine if there is a need for further investigation

Do not use as clean up levels/PRGs

Many SQVs have been established Beware – know how your

screening levels were derived! (e.g. McDonald 2000 “consensus” values)

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Screening and Bioavailability

Source: NRC, 2003

Normalization of bulk sediments (section 3.1.2.2) can be applied within the screening process under some state regulatory programs (e.g. TOC for PAHs/EqP; iron, aluminum for metals)

However the assessment of site impacts is improved by incorporating bioavailability in later stages of the site investigation using site specific considerations

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Specific Exposure Pathways

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Most Common Exposure Pathways

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Benthic Pathway…Chapter 4

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Sediment Quality Triad (SQT):

Procedures for Assessing Bioavailability to Benthic Invertebrates

Chemistry(bulk sediment and pore water concentration)

Toxicity(solid phase;

extract/leachate; bioaccumulation)

Biology(macroinvertebrate abundance,

diversity, benthic indices, body burden)

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SEM/AVS• Simultaneously

Extracted Metals/ Acid Volatile Sulfides

SEM-AVS/fOC

From EPA-600-R-02-011, 2005

No Toxicity

Toxicity Uncertain

Toxicity Probable

Tools to Assess the Benthic Pathway; Chemical - Sediment

130 3000

30Tools to Assess the Benthic Pathway; Chemical - Porewater

Porewater (Direct)• Centrifugation (lab)• Syringes/suction devices• Piezometers• Ultraseep/Trident probe• SPME (solid phase

microextraction; EPA SW-846 8272; ASTM D73-63-07)

Porewater (Indirect)• Peeper• SPMD (semi-permeable

membrane device) / dialysis bags

• Diffusion in thin films (DGT)• SPME, POM

(Polyoxymethylene) film, PE (Polyethylene) strips

• GORE® Module• Diffusive flux

Surface Water

Oligochate

Sediment Surface

Sediment Particles

Porespace filled with water

(porewater)

31Tools to Assess the Benthic Pathway; Chemical - Porewater (Direct) – Suction Devices

Airstone “Before” Airstone “After”

32Tools to Assess the Benthic Pathway; Chemical - Porewater (Indirect) – SPMD/Dialysis Bags

SPMD “Before” SPMD “After”

33Tools to Assess the Benthic Pathway; Chemical - Porewater (Indirect) – “Peepers”

Clear acrylic body

Cell

Lexane wedge

Membrane

Assembled Sampler components

Base plateDialysis

membrane Cover

34Tools to Assess the Benthic Pathway; Chemical - Porewater (Indirect) – “Peepers”

Photographs courtesy of A. Lee Gustafson, Net Zero LLC

Depth (cm)

40

20

0

-20

-40

-60

-80

Arsenic (mg/L)

SouthCentralNorth

0 1 2 3 4 5 6

Water column

Black ooze

Tan medium sand

35 Tools to Assess the Benthic Pathway; Chemical - Porewater (Direct) – Trident Probe and Ultraseep

Ultraseep*

Trident Probe*

*http://www.oceanscience.com/pdf/ultraseep_trident.pdf

36 Tools to Assess the Benthic Pathway; Chemical - Porewater (Direct/Indirect) – SPME (Solid Phase Micro Extraction)

Sample Vial

Syringe

37Tools to Assess the Benthic Pathway; Chemical - Porewater (Indirect) – GORE® Module

Screening tool that can be used to sample porewater Measure concentrations in

GORE lab only Verified use in groundwater Mainly effective for VOCs

To SurfaceCord attached to float or insertion probe

Water and soil particles remain outside

Organic vapors pass through

Multiple sorbents in sample

GORE-TEX membrane

38Tools to Assess the Benthic Pathway; Biological - Sediment Toxicity Tests

Neanthes arenaceodentata

Chironomus dilutus

Hyalella azteca

Eohaustorius estuarius

FRESHWATERBRACKISH ORSALTWATER

39Tools to Assess the Benthic Pathway; Biological - Macroinvertebrate Surveys

“Pollution Sensitive” “Pollution Tolerant”

Benthic Metrics: Abundance, Richness, %EPT, %Dominance, %Chironomids, Hilsenhoff’s or Shannon-Weiner Diversity Indices

40Tools to Assess the Benthic Pathway; Biological - Minimally Disturbed Stream

Photos courtesy of Susan Davies, Maine DEP

41Tools to Assess the Benthic Pathway; Biological - Stream Adjacent to Shopping Mall

Photos courtesy of Susan Davies, Maine DEP

42Tools to Assess the Benthic Pathway Predictive

Equilibrium partitioning

Sediment – Pore Water Exposure

Biota

SedimentCarbon

PoreWater

Equilibrium partitioning Narcosis model SEM-AVS/fOC

Biotic ligand model

Biotic Ligand Model

Organic Matter Complexation

Inorganic Ligand Complexation

Site of Action

Competing Cations

M-DOC

Ca2+

Na+

H

M2+ M-BioticLigand

Free Metal IonMOH+

MHCO3+

MCl+Tipping, 1994

43Case Study Using the Benthic Pathway Tectronix Wetlands Beaverton, OR

Historic operations → sediment metals exceeding Oregon Department of Environmental Quality (DEQ) Level II screening level values• Assessed chemistry, toxicity, SEM/AVS,TOC

Maximum (SEM-AVS)/foc was ~10 less than EPA’s adverse effect level

• Toxicity tests Hyalella azteca mortality Chironomus dilutus growth No adverse effect on amphipods or midges

Assessment concluded concentrations did not pose potential risks to benthic community

NFA for stretch of Beaverton Creek based on• Results from bulk sediment chemistry• Toxicity testing• Comparison to (∑SEM-AVS)/fOC toxicity

threshold

Photo courtesy Kathleen Hurley

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Questions & Answers

45Fish and Water Column Invertebrates Pathway…Chapter 5

46Tools to Assess the Fish and Water Column Invertebrates Pathway Chemical

Measure water quality above sediment bed → compare to • National recommended water quality concentration

• State water quality standards Measure water and tissue residues → compare to

• Bioaccumulation Factors (BAF)

• Critical Body Burden (CBB): ~2.5 umol/g wet weight

• Toxicity Reference Values (TRV) Measure Biota-sediment accumulation factors (BSAFs) =

[COPCtissue/flipid] / [COPCsed/fOC]

• <1 or >1?

47Tools to Assess the Fish and Water Column Invertebrates Pathway Biological

Conduct sediment toxicity tests using appropriate organisms and conditions

Measure in situ bioavailability from field-collected organisms

Conduct population surveys → compare to “reference” conditions

48Tools to Assess the Fish and Water Column Invertebrates Pathway Predictive

Accumulation factors• Bioconcentration factors

USEPA EPISuite

• Bioaccumulation factors Public domain Peer-reviewed literature

• Biota-sediment accumulation factors e.g. U.S. Army Corp of Eng or ORD BSAF Dbase

• Biomagnification factors Biotic ligand model (metals) Food web models

49Case Study Using the Fish and Water Column Invertebrates Pathway

McCormick and Baxter Superfund Site, OR Residual creosote-derived contaminants including PAHs and

dioxins Assessments

• Sediment chemistry• Bioassays• Tissue residues in fish and crayfish• Fish histopathology

Results• Sediment chemistry and toxicity testing

Indicated area of the Willamette River - likely to be toxic• Tissue residues for PAHs were low in

Crayfish (Pacifastacus leniusculus) Large scale sucker (Catastomus macrocheilus) Examination of 249 fish livers found no statistical differences

between the site and upstream locations ROD required placement of an impermeable cap, based on

• Sediment chemistry and bioassay data• Continuing NAPL discharges from sediments to Willamette River

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Wildlife Pathway…Chapter 6

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Freshwater (Mallard) Saltwater (Sandpiper)

CSED (mg/kg) x %diet (kg/day) = mg/kg/day

Dose (mg/kg/day) = % Sediment (in diet)

Tools to Assess the Wildlife Pathway: Indirect Measures

Wildlife effects (already known)• Bulk sediment

(mg/kg)• Literature BAFs• Percent of diet

Calculate: dose (mg/kg/day) Compare: to threshold reference value (TRV) Pass?

• Yes → NFA• No → SLERA/BERA

Exposure/effect: bioaccessibility in sediment

52Tools to Assess the Wildlife Pathway; Indirect Measures

Photo courtesy of Nick Basta, Soil & Envir. Chemistry, Ohio State Univ.

Furman et al., J. Environ. Qual. 35: p. 450 https://www.soils.org/publications/ jeq/articles/36/3/899

Blood Pb (mg kg-1, wet weight)

0 21 643 5 7

4

3

2

1

0

logW

-PB

ET

giz

zard

Pb

(mg

kg-1)

53Tools to Assess the Wildlife Pathway;Direct Measures

Tissue residue analysis• Need clear endpoints

Toxicity testing• Expensive but site-

specific Food web modeling

• Simple vs. complex Population surveys

• Consider scale vs. home range

13.8 ppm

2.07 ppm

0.23 ppm

0.04 ppm

Tertiary consumers

Secondary consumers

Primary consumers

Producers

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Plants Pathway…Chapter 7

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Tools to Assess the Plants Pathway

Bioassay (e.g. seedlings) Bioaccumulation (vegetative) Plant toxicity (e.g. boron)

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Human Health Pathway…Chapter 8

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Exposure in Human Health Pathway

Direct contact with sediment• Ingestion

• Dermal contact

Consumption • Fish

• Wildlife

• Plant

Incidental Sediment Ingestion

Aquatic Vegetation

Soil/Groundwater Sediment

Pore Water

Benthic Organisms

Surface Water

Fish

Water Fowl

Fish & Wildlife Ingestion

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Direct Contact

Preliminary screening • Compare bulk sediment concentrations to human health-

based soil screening levels (SSLs) Refine screening levels

• Modify exposure variables

• Modify bioavailability assumptions Adherence of sediments to skin Dermal absorption efficiency Gastrointestinal absorption efficiency

59Human Consumption of Fish and Shellfish

Contaminants of concern• Primarily concerned with bioaccumulative constituents

• In general bioaccumulation concerns should be limited to select classes of organics (pesticides, PCBs, dioxins) and mercury

Adjust screening levels• Contaminant concentration available in sediment pore water

(Section 4)

• Site specific conditions such as TOC or fish lipid fraction

Direct tissue analysis

60Human Consumption of Fish and Shellfish

Adjust screening levels – example (Text Box 8-1)• Recreational human fisherman screening level =

0.019 mg/kg for hexachlorobenzene (HCB) Default values for fish lipid fraction = 0.03 Sediment fraction organic carbon (foc) = 0.01

• Site-specific screening level = 0.28 mg/kg Used site-specific fish lipid fraction of 0.02 and foc

of 0.10

• Applying site-specific information raises screening value 15x

61Human Consumption of Wildlife and Plants

Wildlife • Incidental ingestion of sediment, aquatic

vegetation and benthic and/or pelagic organisms• Obtain information on dietary habits of species of

concern• Addressed in Chapter 6

Plants• Grown in contaminated area (e.g. seaweed, wild

rice) or crops in dredge spoils• Tissue sampling to determine COPCs• Addressed in Chapter 7

62Case Study – Industri-plex Superfund Site

Once nation’s leading producer of lead arsenate

2-step study of arsenic in river sediments • Step 1 – Narrow focus for live tests

In vitro test on river sediments from four areas

Sediments in reactor that simulates the stomach fluid of humans

• Step 2 – Test relative bioavailability to humans

Tested two sets of river sediment materials Immature swine fed dough balls with

sediment test materials RBA of the site sediments were 37% and

51%, respectively

Study reduced the estimated human health risk in half

63

Case Study Using Bioavailability

Indiana Steel and Wire Site - Mocks Pond

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Site Description and Background

Galvanizing plant, Muncie, Indiana 2.8 acre former limestone quarry

• Received plant production wastewater from 1962-1973

• Lime was added to neutralize wastewater before discharge to pond

• Pond contained 51,000 cubic yards of stabilized spent pickling sludge

• Sediment samples contained high concentrations Heavy metals (Sb, As, Cd, Cr, Cu, Pb, and Zn) Cyanide

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Site Characterization Efforts

Sediment and surface water investigations• Sediment toxicity and leachability studies (1980’s)• Waste characterization study (1993)• Standard bulk chemistry sediment and surface

water sampling for metals and cyanide (1999) Biological assessment

• Water column properties assessment including plankton type

• Macroinvertebrate and fish surveys

• Fish tissue sampling for metals and cyanide

• Wildlife surveys

66Site Characterization Results: Surface Water and Sediment

Physical nature of the sludge not conducive to benthic organisms• Fine grained• No organic matter/nutrients

Neutralization of the wastewater discharge with lime forming insoluble metal hydroxides suggested lack of metals bioavailability

Preliminary surface water sampling results in compliance with water quality standards

Sediment results exceed sediment screening criteria (SSC)

Concentration SSC

Cr 21 - 2,100 ppm 120 ppm

Cu 150 - 6,210 ppm 100 ppm

Pb 201 - 8,000 ppm 82 ppm

67Site Characterization Results: Biological Assessment

Healthy populations• Present

Pelagic fish Phytoplankton Zooplankton species

• Absent Benthic fish Macroinvertebrates

68Bioavailability Investigation Activities: Human Health Risk Assessment

Screened sediment and fish data • Indiana Tier II residential cleanup goals for soil

• EPA Region III Residential RBCs for fish tissue COPECs in sediment: Sb, Cr, Pb and Zn Fish tissue: As Exposure routes

• Incidental ingestion

• Dermal contact

• Ingestion of fish Receptors

• Future construction workers

• Park worker and recreational visitors

• Anglers

69Bioavailability Investigation Activities: Human Health Risk Assessment (continued)

Used exposure modeling to determine risk • IEUBK model for Pb

• Intake modeling for other metals

Conclusion: Remediation of pond sediment is necessary to address direct contact issues with Pb in sediment to the future construction worker and ingestion of arsenic in fish tissue for future recreational anglers.

70Bioavailability Investigation Activities: Ecological Risk Assessment

Screened sediment and fish tissue data• Sediment criteria

Assessment and Remediation of Contaminated Sediments (ARCS) Program for the Great Lakes Threshold Effects Levels (TELs)

Lowest Effects Levels (LELs) (Persuad, 1993) Washington State Lowest

Apparent Effects Thresholds (LAETs)

• Fish tissue criteria Compared to background

concentrations from White River

71Bioavailability Investigation Activities: Ecological Risk Assessment (continued)

Sediment COPCs• Sb, As, Cd, Cr, Cu, Pb, Hg,

Ni, Ag, Zn and cyanide Fish tissue COPCs

• None (concentrations less than background)

Exposure routes• Incidental ingestion

• Dermal contact

• Ingestion of fish

Receptors• Benthic invertebrate

• Piscivorous birds

• Piscivorous mammals Used dietary exposure

modeling to determine risk to higher trophic level organisms

Conclusion: Considerable level of risk exist to benthic organisms, benthic fish and submerged and emergent aquatic macrophytes from sediment exposures due to levels of metals in sediment and the absence of these feeding guilds in the pond

72Remedial Design: Sediment Excavation and Capping

Dredging sediment to clear water depth of 10 feet

Placement of a geotextile fabric liner followed by a subaqueous fine to medium grain sand cap atop the residual sediment

Post-construction monitoring (borings/bathymetry)

Five years of annual post-remedial monitoring to evaluate cap performance in restricting the migration of constituents into the biotic zone

735 Year Post-Remedial Monitoring and Bioavailability Testing

5 Year Annual Monitoring Plan Pore water sampling to evaluate cap performance

• In situ sampling via large diameter peepers

• Inserted 10 centimeters into the sediment Surface water sampling to assess

functional effects on the water column community

Sediment sampling to confirm isolation of metal contamination

74Post-Remedial Monitoring/ Bioavailability Investigation Findings

Post-Construction Monitoring Results Cap performed in accordance with design

• Uniformly overlies pond bottom

• Physically stable

• Effectively isolating the residual underlying sediment

5 Yr Annual Monitoring Results Sediment, surface water and pore water quality met

site-specific standards• Metals tightly sequestered

• Metals not biologically available

75Sediment Quality Improvements and Case Study Summary

Constituent

Initial Concentration Range (1999)

Post-Remedial Concentrations

(at 5th Year)

Sediment Cleanup Standard

(mg/kg) (mg/kg) (mg/kg)

Antimony 36 to 315 0.034 to 0.11B 64

Arsenic 8.9 to 18 2.2 to 6.7 48

Cadmium 1.3 to 12 0.13 to 0.39 3.2

Chromium 21 to 2,100 ND 120

Copper 150 to 6,210 5.9 to 80.4 100

Lead 201 to 8,000 4.6 to 63.8 82

76

Overall Course Summary

Bioavailability should be an integral part of characterization and remedial decision making

Bioavailability can be assessed throughout the process but is more justifiable after the initial screening process

Bioavailability will help you refine your exposure results and refine your risk management decisions

See also: ITRC’s Remedy Selection for Contaminated Sediments

http://www.itrcweb.org/contseds_remedy-selection/

77

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