Transcript Welcome to ITRC’s Internet Training - CLU-IN
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Welcome – Thanks for joining this ITRC Training Class
ITRC Internet-based training and Technical and Regulatory Guidance
Incorporating Bioavailability Considerations into the Evaluation of Contaminated Sediment Sites (CS-1, 2011)
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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Housekeeping
Go to slide 1 Move back 1 slide Move forward 1 slide Go to last slide Go to seminar homepage Download slides as PPT or PDF Submit comment or question Report technical problems Course time is 2¼ hours Question & Answer breaks • Phone - unmute #6 to ask question out loud; *6 mute • Simulcast - ? icon at top to type in a question Turn off any pop-up blockers Move through slides • • Arrow icons at top of screen List of slides on left Feedback form available from last slide –
please
complete before leaving This event is being recorded
Copyright 2014 Interstate Technology & Regulatory Council, 50 F Street, NW, Suite 350, Washington, DC 20001
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ITRC (www.itrcweb.org) – Shaping the Future of Regulatory Acceptance
Host organization Network • State regulators All 50 states, PR, DC • Federal partners
DOE DOD EPA
• 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…
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Meet the ITRC Instructors
John Cargill Delaware Department of Natural Resources and Environmental Control New Castle, Delaware 302-395-2622 [email protected]
Steve Clough Haley & Aldrich, Inc.
Manchester, New Hampshire 603-391-3341 sclough@ haleyaldrich.com
Diana Marquez Burns & McDonnell Engineering Company Kansas City, Missouri 816-822-3453 [email protected]
Greg Neumann New Jersey Department of Environmental Protection Trenton, New Jersey 609-633-1354 greg.neumann@ dep.nj.gov
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ITRC Sediments Team
States
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Alabama California
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Delaware Florida Kentucky Michigan New Jersey New York Oklahoma Oregon Pennsylvania Texas Washington
Universities
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Purdue U. of Florida U of Texas
Federal Agencies
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Navy Army
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AFCEE EPA Including Region 2 & 5
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USACE DOE
Community Stakeholders
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Mtn Area Land Trust
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AAEJC
Industry
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AMEC Alta Environmental
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AECOM AFMC Alcoa Arcadis
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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…
The intended users of this guidance are individuals who have a working knowledge of contaminated sediment management but seek additional information about bioavailability.
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.
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The Problem!
US EPA reports –
10% (1.2 billion yds 3 )
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 Conventional Clamshell Excavator USACE 2008. Technical Guidelines for Environmental Dredging of Contaminated Sediments
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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!
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How 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
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Risk 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 uncertainty will 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
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Contaminated 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
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Processes 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
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Example Conceptual Site Model Anacostia River
Volatilization • Storm Water • Sewer • Water Treatment Plant • CSO Urban Tributaries Permitted Facility Discharge Uncharacterized Point Discharges Precipitation Non-Point Surface Run-off Erosion Tidal Mixing/ Potomac River Surface Water Flow Direction Suspended Particles Adsorption Desorption Resuspension Deposition Groundwater Recharge Bioaccumulation Burial Surface Sediment Dissolution Deep Sediment Epifauna Infauna Flow Direction Bed Load Transport Groundwater Discharge
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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
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 Source: NRC, 2003
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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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Procedures for Assessing Bioavailability to Benthic Invertebrates
Sediment Quality Triad (SQT):
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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Tools to Assess the Benthic Pathway; Chemical Sediment
SEM/AVS • Simultaneously Extracted Metals/ Acid Volatile Sulfides SEM-AVS/f OC
No Toxicity Toxicity Uncertain Toxicity Probable
From EPA-600-R-02-011, 2005
130 3000
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Tools 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 Oligochate Surface Water Sediment Surface Sediment Particles Porespace filled with water (porewater)
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Tools to Assess the Benthic Pathway; Chemical - Porewater (Direct) – Suction Devices
Airstone “Before” Airstone “After”
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Tools to Assess the Benthic Pathway; Chemical - Porewater (Indirect) – SPMD/Dialysis Bags
SPMD “Before” SPMD “After”
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Tools to Assess the Benthic Pathway; Chemical - Porewater (Indirect) – “Peepers”
Assembled Sampler components Clear acrylic body Cell Membrane Lexane wedge Base plate Dialysis membrane Cover
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Tools to Assess the Benthic Pathway; Chemical - Porewater (Indirect) – “Peepers”
Photographs courtesy of A. 40 20 0 -20 -40 -60 -80 0 Lee Gustafson, Net Zero LLC Depth (cm) 1 2 3 4 Arsenic (mg/L) Water column Black ooze Tan medium sand 5 6 South Central North
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Tools to Assess the Benthic Pathway; Chemical - Porewater (Direct) – Trident Probe and Ultraseep
Trident Probe* Ultraseep* *http://www.oceanscience.com/pdf/ultraseep_trident.pdf
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Tools to Assess the Benthic Pathway; Chemical Porewater (Direct/Indirect) – SPME (Solid Phase Micro Extraction) Syringe Sample Vial
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Tools 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
To Surface
Mainly effective for VOCs
Cord attached to float or insertion probe Multiple sorbents in sample
Water and soil particles remain outside GORE-TEX membrane Organic vapors pass through
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Tools to Assess the Benthic Pathway; Biological - Sediment Toxicity Tests Hyalella azteca
FRESHWATER
Chironomus dilutus Neanthes arenaceodentata
BRACKISH OR SALTWATER
Eohaustorius estuarius
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Tools 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
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Tools to Assess the Benthic Pathway; Biological - Minimally Disturbed Stream
Photos courtesy of Susan Davies, Maine DEP
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Tools to Assess the Benthic Pathway; Biological - Stream Adjacent to Shopping Mall
Photos courtesy of Susan Davies, Maine DEP
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Tools to Assess the Benthic Pathway Predictive
Sediment – Pore Water Exposure Equilibrium partitioning Biota Narcosis model SEM-AVS/
f
OC Biotic ligand model
Biotic Ligand Model
Ca 2+ Na + H Competing Cations Sediment Carbon Pore Water
Equilibrium partitioning
M-DOC M 2+ M-Biotic Ligand Organic Matter Complexation MOH + Free Metal Ion Site of Action MHCO 3 + MCl + Inorganic Ligand Complexation Tipping, 1994
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Case 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)/f oc 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)/f OC threshold toxicity Photo courtesy Kathleen Hurley
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Questions & Answers
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Fish and Water Column Invertebrates Pathway…Chapter 5
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Tools 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) = [COPC tissue /f lipid ] / [COPC sed /f OC ] • <1 or >1?
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Tools 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
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Tools 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
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Case 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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Tools to Assess the Wildlife Pathway: Indirect Measures
Wildlife effects (already known) • Bulk sediment (mg/kg) • • Literature BAFs Percent of diet
Freshwater (Mallard)
Calculate: dose (mg/kg/day)
Saltwater (Sandpiper)
Compare: to threshold reference value (TRV) Pass?
• • Yes → NFA No → SLERA/BERA Exposure/effect: bioaccessibility in sediment
Dose (mg/kg/day) = % Sediment (in diet) C SED (mg/kg) x % diet (kg/day) = mg/kg/day
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Tools to Assess the Wildlife Pathway; Indirect Measures
Photo courtesy of Nick Basta, Soil & Envir. Chemistry, Ohio State Univ.
4 3 2 1 0 0 1 2 3 4 5 6 Blood Pb (mg kg -1 , wet weight) 7 Furman et al., J. Environ. Qual. 35: p. 450 https://www.soils.org/publications/ jeq/articles/36/3/899
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Tools 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 Fish & Wildlife Ingestion Water Fowl Fish Aquatic Vegetation Benthic Organisms Pore Water Surface Water Soil/Groundwater Sediment
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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
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Human 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
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Human 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
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Human 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
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Case 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
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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
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Site 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
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Site Characterization Results: Biological Assessment
Healthy populations • Present Pelagic fish Phytoplankton Zooplankton species • Absent Benthic fish Macroinvertebrates
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Bioavailability 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
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Bioavailability 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.
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Bioavailability 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
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Bioavailability 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
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Remedial 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
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5 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
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Post-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
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Sediment Quality Improvements and Case Study Summary
Constituent
Antimony Arsenic Cadmium Chromium Copper Lead
Initial Concentration Range (1999) Post-Remedial Concentrations (at 5th Year) (mg/kg) (mg/kg)
36 to 315 8.9 to 18 1.3 to 12 21 to 2,100 0.034 to 0.11B
2.2 to 6.7
0.13 to 0.39
ND 150 to 6,210 201 to 8,000 5.9 to 80.4
4.6 to 63.8
Sediment Cleanup Standard (mg/kg)
64 48 3.2
120 100 82
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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 See also:
ITRC’s Remedy Selection for Contaminated Sediments
http://www.itrcweb.org/contseds_ remedy-selection/ Bioavailability will help you refine your exposure results and refine your risk management decisions
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