Review of Human and Ecological Risk Related to Contaminants, Containment Measures and Potential...
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Transcript of Review of Human and Ecological Risk Related to Contaminants, Containment Measures and Potential...
Review of Human and Ecological Risk Related to
Contaminants, Containment Measures and Potential Remediation Strategies
Meghan Montgomery, Lisa Fredette, and Noelle Bramer
History of Pine Street Barge1906-1966: Coal Gasification Plant
1960-1970: Landfill construction debris, manufacturing wastes
1983: EPA listed site Superfund National Priorities
1985: 500 cubic yards excavated, solidified, disposed
Clay lining/sand cap applied on top and underwater
2006: First five year review of remedial actions
(EPA, 2010)
(EPA, 2006).
Problem StatementFive Year Review of the Pine Street Barge Canal
Despite capping of contaminated sediment in canal and wetlands - coal tar leaks
EPA concluded that capping of coal tar is not effective for long term management
Long term solution evaluated Eliminate releases of coal tar into surface waters of
canal and adjacent areas Prevent spread to Lake Champlain Prevent completion of exposure pathways Remove threat to ecological and human health
(EPA, 2006)
Goals/ObjectivesAssess conditions at Pine Street Barge Canal at
presentConsider the nature of the contaminantsLocal geologyCurrent control strategies
Review potential remediation strategiesNo action option Soil WashingBioremediation
Provide recommendations for actionEffective in removing pollutantsMinimize riskRestore land for community use
ApproachResearch using search engines:
Science DirectAcademic Search PremierWeb of ScienceGoogleScholar
Literature ReviewedAbstractCredibilityTables/graphsGeological survey presented at the New
England Intercollegiate Conference
FindingsContaminants
Hydrocarbons: Benzene, Toluene, Ethylbenzene, Xylene
PAH compounds – NaphthaleneCyanide
Exposure pathwaysEcological receptors on siteReceptors in Lake ChamplainRisk to human health
Hydrocarbons: BTEXBenzeneToluene EthylbenzeneXylene
Non-aqueous phase liquid Surface water, groundwater , soil layers
(EPA ROD, 1998)
Benzene Toluene Carcinogenic
Effects bone marrow Hematological issues
reported at 1ppm airborne
Lower evaporation rate
Mobility into groundwater
(ASTDR, 2007) (Johnson et al., 2007)
Nervous System
Brain, liver and kidney damage
Volatilization to air
Sorption to organic matter
(DEFRA, 2004) (NHDES, 2005) (ASTDR, 2006)
Ethylbenzene Xylene High ability to break
down in air and surface water
Chronically affects blood
Possible human carcinogen
(ASTDR, 2006)
Easily Evaporate
Inhalation and Skin contact
Central nervous system depression
Blood and liver damage
(Clayton& Clayton, 1981) (MDSD,
2008) (TTNAT, 2007)
Polycyclic Aromatic Hydrocarbons
Toxic for immune system and development
Complete carcinogens
mutations in DNA
proliferative capacity of mutated cells
Skin and eye irritants
(Flowers et al., 2003)
Persist in environment for long periods of time
Natural and man-made sources
Naphthalene
(University of Wisconsin, 2010)
Cyanide
Contact: inhalation, absorption, ingestionEffects:
Forms cytochrome oxidase in bloodstream cannot use oxygen – hypoxia
Fish/aquatic invertebrates Very sensitive to exposure: 5.0 – 7.2 micrograms/L Reduces swimming performace Inhibits reproduction
(NYS, 2004) (CMC, 2006)
Exposure Pathways
(Menzie & Coleman, 2007)
Danger: FoodchainPAH in water, sedimentBenthic organisms:
algae, mollusks, invertebratesDo not metabolize =
accumulateFish consume = health
risks + biomagnification
People consume = health risks
(Menzie & Coleman, 2007) (UKMSAC, 2001)
Options for Remediation“No Action” Soil Washing
Bioremediation
“No Action Option”Hydrogeology of Pine Street Barge
Site 70 acres between Lake Champlain and Pine Street
Boundaries - East by Pine Street, West by Vermont Railroad Track, North by Burlington Street Dept., South by Lakeside Avenue
Natural geology and hydrology protects lake and bedrock aquifer
(Maynard, 1999)
Geology
Surface: Protective Sand Cap
•20 feet peat saturated with coal tar waste
Center: •45- 110 feet laminated silt/clay from Champlain Sea deposits and Glacial Lake Vermont
Base:•Coarse silty gravel from Wisconsin Ice Sheet•Quartzite bedrock
•Structural faults (fractures) – aquifer(Maynard, 1999)
Geological ProtectionBase: structural faults form “steplike” benches
of vertical walls and bedding planes slope 10-20o away from lake
Center: layered silt/clay deposits from Champlain Sea and Glacial Lake VermontContinuous over siteVery low hydraulic conductivity1,000’s years to infiltrate through
Hydrology: Gradient (direction of water flow) is upwardsLimits migration
(Maynard, 1999)
Current ProtectionCoal tar waste within 15-20 feet peat
Carbon matrix of soil on site binding capacity – limits bioavailability plant’s cannot access PAH compounds
Buried beneath fill prevent bioaccessibility Unlikely to come into direct contact with compounds
In canal Buried in 5 feet sediment Further restricted by submerged sand cap, land barrier
between it and lake(Maynard,
1999)
PAH Contamination Spread
(EPA, 2006)
Monitoring
Remedial Investigation 1994100 monitoring wells, piezometers, 600 boring logsWater quality testing – maximum contamination
level reached one well on perimeter, none west/towards lake
Level of contamination in well stable – groundwater equilibrium
Public drinking supply – classified as Class IV (not suitable as potable)
(Maynard, 1999)
Sampling Wells
(EPA, 2006)
Despite Protective MeasuresCapping Failures
Subaqueous caps Area 1 and 2 exceed EPA benchmarks for protection of on-site ecological communities
Spread to adjacent area 2003, canal in 2005 Extension of capping, absorbent booms
(EPA, 2006)
ResearchLong-term caps undergo consolidation (sinking
and compression) Pore-water advection (migration) of pollutants outwards
and upwards (Kim et al., 2009)
From “No Action” OptionPollutants appear in a static state, not moving
towards the aquifer nor out to the lake. (Maynard, 1999)
BUT………Presence of contaminants represents long term
riskPotential for completion of exposure pathwaysHazardous substance above health-based levels –
require 5 year reviews by EPACapping FailuresCanal hydrologically connected to Lake
Champlain and subject to flooding Consider effects have on human/ecological health Long term remediation must be evaluated
(EPA, 2006)
Soil Washing
Why are PAHs hard to treat?Low aqueous solubilityBind to carbon matrix of soilNot accessible to plants/bacteria for degradation
(Menzie & Coleman, 2007)
How can soil washing help?Surfactants – counteract these traits make PAH
soluble and removable! Widely available technology
(Maturi & Reddy, 2008)
Surfactants
Amphiphilic: hydrophobic tail, hydrophilic head“Like attracts like.”Hydrophobic tail attracts water-insoluble PAH
Brings compound into ring of tails – micelleHydrophilic head “sticks out” around perimeter
Water can interact with head, flush ring awayProcess for removing compounds environmental
priority
(Gan et al., 2009)
Steps for Soil WashingTwo step process
Desorption/removal of compound from binding siteElution/flushing from fluid
Waste product captured in slurry mixture/bound to activated carbon for disposal
Other steps withinScreening, mixing, scrubbing, sieving
Role of Surfactants – increase effectiveness of system
(Gan et al., 2009)
Basics of Soil Washing
(Diels & Gemoets, 1997)
Surfactant OptionsCombinations
5% 1-pentanol - 10% water – 85% ethanol 1g/100ml, extraction time 24 hours = 95% removal
Single compoundsOrganic solvents: Acetone/ethanol – safe, availableCyclodextrins: high removal efficiency
solution:soil 6:1Vegetable Oil: least expensive, most effective,
biodegradable option
(Lee et al., 2001)(Gan et al., 2009)
Vegetable Oil?Strong sorption medium for PAHsFree fatty acid chains act like chemical
surfactantsSunflower oil - 1kg:4L 81-100% removalPaired with activated carbon 90% removal
consistentOther benefits
Increase biodegradation by acting as medium/substrate for microorganisms
(Gan et al., 2009)
Soil Washing ShortcomingsIneffective at removing heavy metalsProcessing involves excavation of contaminated soil
Vapor emissions: release volatile organic carbons into air
Minneapolis Gas Works - strong community reaction Complaint calls, demonstrations, property damage
Processing produces waste productsResidual sludge/activated carbon processed by
incineration or co-combustion in coal-powered plants/cement kilns
Waste water treat with chemicals to recycle it for use
(Maturi & Reddy, 2008)(Muserait, 2001) ((Symonik et al., 1999) (Diels & Gameots, 1997)
BioremediationProcess: biodegradation
Organisms break down waste products (organic/inorganic) into nutrients
Anaerobic/aerobicOrganisms
Specialized and adaptable native fungi and bacteria
Techniques promoting functionLand farmingComposting
(Gan et al., 2009)
Landfarming
Indigenous microorganismsIncrease effectiveness
Periodic tilling of location – provide homogeneity of soil, aeration
Monitoring soil moisture and nutrients Add bulking agents, nutrients improves
degradation/oxidation
(Gan et al., 2009)
Previous Studies1st: Soil amendments + weekly tilling (15cm) –
100% reduction in 12 weeks2nd: Using soil from MGP
Several hundred ft3 in prepared plot 30cm deep6- 12 months 90% of low molecular weight PAHs
removed
(Gan et al., 2009)
Benefits of Landfarming
SimpleLow maintenance Requires scheduled tilling and monitoring
(Gan et al., 2009)
Limitations of Landfarming
Only applicable in top 10-35 cm of soilEffectiveness may be limited in highly
contaminated sitesNative communities may not be effective in
degrading compounds – may add white button mushrooms, white rot fungus, and specialized bacteria to complement
(Gan et al., 2009)
CompostingViable option effective at treating soils with
PAHsScientists studied use of composting mixture
White button mushroomsWheat strawChicken manureGypsumSoil from MGP
Maintained optimal temperatures/aeration54 days later
PAH concentration reduced 20-60%Additional removal 37- 80% after 100 days
(Gan et al., 2009)
White Rot Fungus: One Key to Composting
Ability to degrade wide variety of heavy aromatic hydrocarbons (persistent compounds)
Ability stems from specialized enzymes – extracellular lignin degrading enzymes
Irpex lacteus and Pleurotus ostreatusDegrade 58-73% 4-ring PAHsEffective at treating cyanide
(Gan et al., 2009)
Chart
(Gan et al., 2009)
Bacteria in Composting Attach to surface of sedimentsProduce biosurfactants release PAHs from soilCombination of bacteria and fungi
Study: degrade 16 types PAHsCombination of bacteria
Study: combining Mycobacterium and Spingomonas reduced PAH concentration by 30%
Complement the degradative actions of each other “co-metabolism” Increases tolerance for mixed contaminants
(Gan et al, 2009) (Hughes et al., 1997)
+Bioremediation +Naturally occurring microorganismsMetabolically driven breakdownSpecialized strains efficient in removalLowest environmental impact
Neither bacteria nor fungi pose significant environmental threat
Capable of spreading across location remove PAH may have migrated
(Diels & Gemoets, 1997)
-Bioremediation-Aeration required for respiration: electron
acceptor for hydrocarbon breakdownMixtures of contaminants inhibit degradationLimited effectiveness compared to surfactantsRequires excavation: release of VOC’s
Potential release into lake is released into canal waters
(Gan et al., 2009) (Hughes et al., 1997)
VOC ControlsVOC release main concern
Reduce size of excavation areaDig in winter – cold temps limit release/human
exposureCover work area – water, surface foams, tentsMonitoring stations perimeter – safe working
environment, protect residents (within 1 mile)
(Muserait, 2001) (Diels & Gameots, 1997)
Other Considerations: Stakeholders
Minneapolis, MN Minnegasco + Pollution Control Agency +
citizens + business owners+ interest groups = advisory board
MN State Office of Dispute ResolutionStakeholders: ID, informed, involved in
remediation optionsDiffused tensions, educated public
(Symonik et al., 1999)
Minnesota ResultsWest River Parkway – returned for
community useBike trailsHikingPicnic area
Success storyRemediation of similar siteUrban settingSensitive to environmental health issues,
community involvement
(Symonik, 1999)
Recommendations
Remediation of Pine Street Barge Canal in Burlington, VTChemical nature of pollutants Continued human/ecological health risksPotential mobilization to adjacent land/Lake
ChamplainLost potential land use
Formation of city-wide council identify stakeholders, educate, approval for remediation, recommendations for site use
RecommendationsUse of both soil washing and bioremediation
PAH tightly bound over time, multiple compoundsSurfactants make bioaccessible/available
Pretreatment allows bioremediation to occur 2 -6x faster Vegetable oil as solvent
Bioremediation remove additional PAH compounds & cyanide Adding PAH degrading bacteria & white rot fungus Landfarming – only requires tilling (possibly fertilization)
Excavation – sequentially, winter, tent, air monitoring perimeter, protective equipment for workers
Sources:
Sources:
Sources:
University of Wisconsin. (2010). Image of Polycyclic Aromatic Hydrocarbon Molecules. Retrieved from fti.neep.wisc.edu.
SummaryProblem: Present control measures to prevent spread of coal tar
contaminated sediment from Pine Street Barge to adjacent land and Lake Champlain ineffective for long term management.
Goals/Objectives: Assess conditions at Pine Street Barge Canal at present (nature of
the contaminants, geology, current control strategies) Review potential remediation strategies (no action, soil washing,
bioremediation Provide recommendations for action (effective, minimize risk,
restore)
Findings: Contaminants: hydrocarbons - BTEX , PAHs (carcinogens damage body
systems) Contaminants: cyanide (damage nervous system)
Treatment Soil washing: use surfactants, high removal efficiency, can be used as
pretreatment Bioremediation: use bacteria/fungi, remove additional PAHs and cyanide
Recommendations: combine soil washing and bioremediation, form council of stakeholders education/approval, safely remove contamination, return site to community use