Investigation and Cleanup of Ethanol Investigation and Cleanup of Ethanol and Ethanoland Ethanol--Blended FuelsBlended Fuels

Mark A. TosoMark A. Toso

Minnesota Pollution Control AgencyMinnesota Pollution Control Agency

Minnesota Air, Water, and Waste Environmental Minnesota Air, Water, and Waste Environmental ConferenceConference

February 28, 2008February 28, 2008

Emergency Response and Large Emergency Response and Large Facility Cleanup ProgramFacility Cleanup Program

Sites >1 million gallons liquid storageSites >1 million gallons liquid storage

Petroleum, Chemical, Food and Petroleum, Chemical, Food and EthanolEthanol

2600 spills reported per year, 60% petroleum2600 spills reported per year, 60% petroleum

Cleanup generally follows Petroleum Cleanup generally follows Petroleum Remediation Program PolicyRemediation Program Policy

Yearly Ethanol Production in Minnesota

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400

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120019

90

1991

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1995

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1997

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Year

Volu

me

(Milli

ons

of G

allo

ns)

March 2004 March 2004 -- Lanesboro, MN Lanesboro, MN 7700 gals E957700 gals E95

January 2005 January 2005 -- Tank Overfill at Ethanol PlantTank Overfill at Ethanol Plant400 gals E95400 gals E95

Ethanol in Motor FuelsEthanol in Motor FuelsE95 E95 –– FuelFuel--grade denatured ethanolgrade denatured ethanol

Denatured with gasoline or other petroleum productDenatured with gasoline or other petroleum productMinimum denaturant required is 2%Minimum denaturant required is 2%Transported by rail or truck to blending terminalsTransported by rail or truck to blending terminals

E85E85 -- 85% ethanol, 15% gasoline85% ethanol, 15% gasolineWinter blend is actually 70/30Winter blend is actually 70/30

E10E10 -- Mandated by MN legislature since 1997Mandated by MN legislature since 1997

E20E20 –– Future state mandates?Future state mandates?

Assumptions about E85/95Assumptions about E85/95

Rapidly evaporatesRapidly evaporates

Degrades quickly in soil and ground waterDegrades quickly in soil and ground water

NonNon--toxic and not a hazardous substancetoxic and not a hazardous substance

Cleanup not required if released to secondary Cleanup not required if released to secondary containment containment

Gasoline denaturant fraction insignificantGasoline denaturant fraction insignificant

E85/95 ConcernsE85/95 Concerns

Ethanol is not a regulated compound, no cleanup Ethanol is not a regulated compound, no cleanup standardsstandards

Miscible with water (but can phase separate) Miscible with water (but can phase separate)

High BOD loading and toxicity in surface waterHigh BOD loading and toxicity in surface water

Toxicity problem in WWTPToxicity problem in WWTP

E85/95 ConcernsE85/95 Concerns

Known to extend petroleum plumes in ground water : Known to extend petroleum plumes in ground water :

CoCo--solvency results in higher BETX concentrationssolvency results in higher BETX concentrationsPreferential degradation of ethanol over BETXPreferential degradation of ethanol over BETXAltered sorption and retardation of BETXAltered sorption and retardation of BETXToxicity to microorganismsToxicity to microorganisms

Reduces soil capillary forces and spreads LNAPL Reduces soil capillary forces and spreads LNAPL

Alters soil structure (dehydrates and fractures clay Alters soil structure (dehydrates and fractures clay soils)soils)

Current E85/95 CleanCurrent E85/95 Clean--up Strategyup Strategy

Excavation of all visually impacted soilExcavation of all visually impacted soil

Soil borings and monitoring wells required when full Soil borings and monitoring wells required when full excavation isn’t possibleexcavation isn’t possible

Ground water cleanup based on BETX standardsGround water cleanup based on BETX standards

Ethanol analysis not always requiredEthanol analysis not always required

Soil disposal options include thin spreading and Soil disposal options include thin spreading and landfilllandfill

Problems with E85/95 CleanProblems with E85/95 Clean--up Strategyup StrategyNo standard laboratory analytical methods for ethanol No standard laboratory analytical methods for ethanol and gasoline mixtures (high detection limits)and gasoline mixtures (high detection limits)

Properties and composition of denaturants unknownProperties and composition of denaturants unknown

Methane generation is known to occurMethane generation is known to occur

Current inCurrent in--situ remedial technologies thought to work situ remedial technologies thought to work (but little experience)(but little experience)

Degradation pathways not well understoodDegradation pathways not well understood

Mixing EthanolMixing Ethanol--Blended Fuels with WaterBlended Fuels with Water(Adapted from Jim Barker, University of Waterloo)(Adapted from Jim Barker, University of Waterloo)

50 50

50

25

25

75 75

75

ethanol

water gasoline

2 phase field

1phasefield

E10

E95E85

CapiroCapiro, N.L. Fuel, N.L. Fuel--grade ethanol transport and impacts to grade ethanol transport and impacts to ground water in a pilotground water in a pilot--scale aquifer tank. Water Res. (2006)scale aquifer tank. Water Res. (2006)

Bench scale E95 release into a continuous flow sand tank

Found that ethanol migrated upwards and spread laterally within Found that ethanol migrated upwards and spread laterally within the capillary fringe the capillary fringe area above the water tablearea above the water table

Significantly retarded vertical and horizontal migrationSignificantly retarded vertical and horizontal migration

Hydrocarbons phase separated within the capillary fringeHydrocarbons phase separated within the capillary fringe

Resulted in lower than expected dissolved contaminationResulted in lower than expected dissolved contamination

Pumping recovered 98% of released ethanol but only 25% of hydrocPumping recovered 98% of released ethanol but only 25% of hydrocarbonsarbons

Possible implications to release site investigations?Possible implications to release site investigations?

Research on EthanolResearch on Ethanol--Blended Fuel ReleasesBlended Fuel Releases

National level research is lackingNational level research is lacking

MPCA in collaboration with the University of Nebraska, the MPCA in collaboration with the University of Nebraska, the American Petroleum Institute and the Minnesota Department American Petroleum Institute and the Minnesota Department of Health Environmental laboratory conducting field research of Health Environmental laboratory conducting field research at two E95 releases in S. Minnesotaat two E95 releases in S. Minnesota

MPCA seeking funding for benchMPCA seeking funding for bench--scale geochemistry and scale geochemistry and microbiology column studies with the University of Minnesotamicrobiology column studies with the University of Minnesota

Research will have a direct bearing on policy and protocol Research will have a direct bearing on policy and protocol development in Minnesota, with likely extension to other development in Minnesota, with likely extension to other states already with or progressing towards greater use of states already with or progressing towards greater use of ethanol blended fuelsethanol blended fuels

July 2004 July 2004 -- Balaton, MNBalaton, MN60,000 gals E9560,000 gals E95

Pooled E95 at Balaton, MNPooled E95 at Balaton, MN

November 2006 November 2006 -- Cambria, MNCambria, MN25,000 gals E9525,000 gals E95

MN Field Research SitesMN Field Research SitesBoth sites previously cleaned up following current policyBoth sites previously cleaned up following current policy

Investigation by MPCA and University of Nebraska to Investigation by MPCA and University of Nebraska to collect additional soil gas and ground water datacollect additional soil gas and ground water data

June 2007June 2007BalatonBalaton -- 10 temporary wells and vapor points10 temporary wells and vapor pointsCambria Cambria -- 6 temporary wells and vapor points6 temporary wells and vapor points

November/December 2007November/December 2007BalatonBalaton -- 9 wells, 8 vapor points, 2 surface gas samplers9 wells, 8 vapor points, 2 surface gas samplersCambria Cambria -- 8 wells, 5 vapor points, 3 surface gas samplers8 wells, 5 vapor points, 3 surface gas samplers

BalatonBalaton -- November 2007November 2007

BalatonBalaton –– November 2007November 2007

Cambria Cambria -- November 2007November 2007

Cambria Cambria -- November 2007November 2007

June 2007 ResultsJune 2007 Results

BalatonBalaton (spill date 7/04)(spill date 7/04)

Methane at saturation limits in groundwater (28,000 Methane at saturation limits in groundwater (28,000 ugug/L)/L)Very high methane in soil gas Very high methane in soil gas -- 53.8%53.8%Low ethanol in ground water Low ethanol in ground water -- 1020 1020 ugug/L /L

Cambria (spill date 11/06)Cambria (spill date 11/06)

Low methane in groundwater Low methane in groundwater -- 2130 2130 ugug/L /L Lower methane in soil gas Lower methane in soil gas -- 4.6%4.6%Very high ethanol 55,000,000 Very high ethanol 55,000,000 ugug/L (5.5%) in ground water/L (5.5%) in ground water

December 2007 ResultsDecember 2007 ResultsBalatonBalaton

Similar low ethanol and high methane concentrations in ground Similar low ethanol and high methane concentrations in ground waterwaterMuch lower methane in soil gas Much lower methane in soil gas -- 5.9%5.9%Methane detected in surface soil gas sampler Methane detected in surface soil gas sampler –– 2.7% 2.7%

CambriaCambriaHigher methane in ground water Higher methane in ground water -- 23,500 23,500 ugug/L /L Lower methane in soil gas Lower methane in soil gas -- 1.0%1.0%Lower ethanol in ground water Lower ethanol in ground water -- 0.10%0.10%Methane detected in surface soil gas sampler Methane detected in surface soil gas sampler –– 1.6%1.6%

BalatonBalaton: Ethanol in Groundwater 6/07: Ethanol in Groundwater 6/07

BalatonBalaton: Ethanol in Groundwater 12/07: Ethanol in Groundwater 12/07

BalatonBalaton: Methane in Ground Water 6/07: Methane in Ground Water 6/07

BalatonBalaton: Methane in Ground Water 12/07: Methane in Ground Water 12/07

Cambria: Ethanol in Ground Water 6/07Cambria: Ethanol in Ground Water 6/07

Cambria: Ethanol in Ground Water 12/07Cambria: Ethanol in Ground Water 12/07

Cambria: Methane in Ground Water 6/07Cambria: Methane in Ground Water 6/07

Cambria: Methane in Ground Water 12/07Cambria: Methane in Ground Water 12/07

What Happened?What Happened?Loss of methane in soil gas between June and DecemberLoss of methane in soil gas between June and December

Differences between temporary and permanent well and vapor Differences between temporary and permanent well and vapor point construction?point construction?

No valves on vapor probes?No valves on vapor probes?

Time of year, temperature, barometric effects?Time of year, temperature, barometric effects?

Methane in ground water still at saturation levels, where’s the Methane in ground water still at saturation levels, where’s the soil soil gas?gas?

Natural AttenuationNatural Attenuation

Very high acetate detected in ground water at both sitesVery high acetate detected in ground water at both sites

Generally low nitrate but high sulfate. Possible stratified Generally low nitrate but high sulfate. Possible stratified biobio--geochemical geochemical zonationzonation? ?

Methanogenesis in capillary fringe?Methanogenesis in capillary fringe?

Strong odors of manure, yeast, vinegar Strong odors of manure, yeast, vinegar

Other ObservationsOther Observations

Difficulty in zeroing methane field meters in July at Difficulty in zeroing methane field meters in July at BalatonBalaton, possible off, possible off--gassing at site?gassing at site?

Very strong odors at Cambria in surface water, Very strong odors at Cambria in surface water, sampling indicated ethanol still present sampling indicated ethanol still present -- 0.12%0.12%

Good correlation between GEM 500 and 3Good correlation between GEM 500 and 3--CCMight have better results with inMight have better results with in--line carbon filter line carbon filter (removes VOCs)(removes VOCs)

ConclusionsConclusions

Based on current investigation and riskBased on current investigation and risk--based policy based policy both sites were potential closure candidatesboth sites were potential closure candidates

Methane in soil gas has accumulated to explosive levels Methane in soil gas has accumulated to explosive levels at both sitesat both sites

Dissolved methane concentrations in groundwater at Dissolved methane concentrations in groundwater at both sites at saturationboth sites at saturation

High acetate indicates methane generation will continue High acetate indicates methane generation will continue in absence of ethanolin absence of ethanol

Future ResearchFuture Research

Continued monitoring with emphasis on methane Continued monitoring with emphasis on methane generation and natural attenuationgeneration and natural attenuation

Development of laboratory analytical methodsDevelopment of laboratory analytical methodsEvaluation of directEvaluation of direct--reading field metersreading field metersEvaluation of acetate and other degradation productsEvaluation of acetate and other degradation products

U of M benchU of M bench--scale geochemistry and microbiology scale geochemistry and microbiology column studies with soils collected at column studies with soils collected at BalatonBalaton

Emphasis on natural attenuation pathways and metabolic Emphasis on natural attenuation pathways and metabolic productsproductsExpand to include various ethanol blends (E20, E50, ect).Expand to include various ethanol blends (E20, E50, ect).

AcknowledgmentsAcknowledgments

Tom Higgins and Adam Tom Higgins and Adam SekelySekely, MPCA, MPCA

Bruce Bauman, American Petroleum Institute Bruce Bauman, American Petroleum Institute

Roy Spalding, University of NebraskaRoy Spalding, University of Nebraska

Minnesota Dept of Health Environmental LaboratoryMinnesota Dept of Health Environmental Laboratory

For more informationFor more information

Mark TosoMark TosoMinnesota Pollution Control AgencyMinnesota Pollution Control Agency

520 Lafayette Road 520 Lafayette Road St. Paul, MN 55155St. Paul, MN 55155

651651--297297--86698669mark.toso@pca.state.mn.usmark.toso@pca.state.mn.us

http://www.pca.state.mn.us/programs/ethanol.htmlhttp://www.pca.state.mn.us/programs/ethanol.html