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