AIR DISPERSION MODELING REPORT WILSON … DISPERSION MODELING REPORT WILSON STATION SO2 DESIGNATION...

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AIR DISPERSION MODELING REPORT

WILSON STATION SO2 DESIGNATION ANALYSIS

REVISION 1

Preparedfor:MarkBertram

Manager,EnvironmentalBigRiversElectricCorporation

201ThirdStreetHenderson,KY42420

PreparedBy:

TRINITYCONSULTANTS1717DixieHighway

Suite900Covington,Kentucky41011

Project151801.0045

August25,2015

1-0 Big Rivers Electric Corporation – Wilson Station 1-Hour SO2 NAAQS Designation Modeling Report

TABLE OF CONTENTS

1.EXECUTIVESUMMARY 1-3

2.INTRODUCTION 2-0 2.1.FacilityInformation..............................................................................................................................................2‐0 2.2.BasisforAnalysis...................................................................................................................................................2‐1 2.3.RegulatoryBackground.......................................................................................................................................2‐2 2.4.EmissionRatesforWilsonStation...................................................................................................................2‐3

3.1‐HOURSO2DESIGNATIONMODELINGMETHODOLOGY 3-0 3.1.ModelSelection......................................................................................................................................................3‐0 3.2.RuralUrbanOptioninAERMOD.......................................................................................................................3‐1 3.3.MeteorologicalData..............................................................................................................................................3‐3

3.3.1.SurfaceData................................................................................................................................................................................3‐4 3.3.2.UpperAirData...........................................................................................................................................................................3‐5 3.3.3.LandUseAnalysis......................................................................................................................................................................3‐5

3.4.CoordinateSystem................................................................................................................................................3‐6 3.5.ReceptorLocations...............................................................................................................................................3‐6 3.6.TerrainElevations.................................................................................................................................................3‐9 3.7.WilsonStationEmissionSources..................................................................................................................3‐10 3.8.OtherSourceInventory....................................................................................................................................3‐11 3.9.BuildingInfluences............................................................................................................................................3‐13 3.10.SourceContributions......................................................................................................................................3‐13 3.11.BackgroundConcentrations.........................................................................................................................3‐13 3.12.ModelingFiles...................................................................................................................................................3‐15

4.1‐HOURSO2DESIGNATIONMODELINGRESULTS 4-1


LIST OF FIGURES

Figure2‐1.AerialPhotographofWilsonStation 2‐0

Figure2‐2.AreaMapofWilsonStation 2‐1

Figure2‐3.Locationof1‐hourSO2ModelingSourcesinRelationtoWilsonStationandNearbyTowns 2‐3

Figure3‐1.DistributionofLandUseWithin3kmofWilsonStation 3‐2

Figure3‐2.MeteorologicalStationsandSO2MonitorsintheAreaNearWilsonStation 3‐4

Figure3‐3.ModelingTADReceptorGridShowingExampleExcludedLocationsOverWater 3‐7

Figure3‐4.InnermostPortionoftheModelingReceptorGridforWilson 3‐8

Figure3‐5.OverallModelingReceptorGridforWilson 3‐9

Figure3‐6.MapShowingRegionalSO2SourcesNearWilsonStation 3‐11

Figure3‐7.99thPercentileSO2AveragesbyHourofDayforBaskettMonitor(21‐101‐0014) 3‐15

Figure4‐1.SpatialDisplayof3‐yearAverage99thPercentileAnnualDistribution 4‐2


LIST OF TABLES

Table3‐1.ModelingTADUrban/RuralCategories 3‐1

Table3‐2.WilsonStationUrban/RuralDetermination 3‐2

Table3‐3.ProximityAnalysisofMeteorologicalStationstoWilsonStation 3‐5

Table3‐4.MoistureCalculationforEvansvilleAirport(inchesofprecipitation) 3‐7

Table3‐5.WilsonStationSourceCharacterization 3‐10

Table3‐6.NearbySourceCharacterization 3‐12

Table4‐1.Highest4thHighModeled1‐hourSO2ResultsforComparisontotheNAAQS 4‐1


1. EXECUTIVE SUMMARY

TheBigRiversElectricCorporation(BREC)inassociationwithourairqualitycontractor,TrinityConsultants(Trinity),submitsthisdispersionmodelingreportforairqualitymodelinganalysisthatwasperformedwithrespecttoBREC’sD.B.WilsonStation(Wilson)andthesurroundingarea.ThisworkwasundertakeninsupportoftheKentuckyDivisionforAirQuality(KDAQorDivision)responsetotheMarch20,2015letterfromtheU.S.EnvironmentalProtectionAgency(U.S.EPA)toCommissionerScottoftheKentuckyDepartmentforEnvironmentalProtection(KDEP)regardingdesignationsofareascurrentlyunclassifiedwithrespecttothe20101‐hourSO2NationalAmbientAirQualityStandard(NAAQS).Inthatletter,U.S.EPAidentifiedtheWilsonStationasoneoftheKentuckysourcesmeetingthecriteriaforevaluationofunclassifiedareasinthefirstroundofdesignationsthroughmodelingaspartofarequiredresponsebyU.S.EPAtotherecentSierraClubvs.ReginaMcCarthyConsentDecree1.WilsonwasalsoidentifiedontheU.S.EPAwebsitelistingallareaswheredesignationswouldberequiredundertheconsentdecreebytheJuly2,2016date2.ThecriteriatodetermineifasourcewassubjecttotheConsentDecreeare:1)anearbymonitorshowingaviolation,and2)thatanareacontainastationarysourcethataccordingtotheEPA’sAirMarketsDatabaseeitheremittedmorethan16,000tonsofSO2in2012oremittedmorethan2,600tonsofSO2andhadanemissionrateofatleast0.45lbsSO2/MMBtuin2012.AccordingtoEPA’sAirMarketsDatabase,theWilsonStationemitted7,387tonsSO2in2012andhadanaverageSO2emissionrateof0.45lbsSO2/MMBtuin2012.WilsonStationislocatedonStateHighway85justeastofIsland,KentuckyinOhioCounty.JustaftertheConsentDecreewassigned,U.S.EPAstatedthatitwouldbasethedesignationoftheOhioCountyandsurroundingareaontheemissioncriteriaalone(CriteriaNo.2)asnoSO2monitorsareinthearea.However,U.S.EPAinvitedstateagenciestosubmitupdatedrecommendationsandsupportinginformationthatcouldbeconsideredinthefinaldesignations.Tothatend,BRECcommissionedthismodelinganalysistoaidKDEP/KDAQinthedesignationdeterminationfortheOhioCountyarea.ThismodelingwasdesignedtomeettherequirementsofU.S.EPA’smodelingTechnicalAssistanceDocumentforSO2NAAQSdesignationmodelingguidance3(ModelingTAD).Tothatend,dispersionmodelingwasconductedfollowingtheTADguidance.Asallowedbytheguidance,anallowableemissionratewasusedfortheWilsonStationasasurrogateforactualemissions.Commensuratewiththeseallowablelimits,aGoodEngineeringPractice(GEP)stackheightwasused(theuseoftheactualstackheightispermissibleundertheTADifactualemissionswereused).NearbysourceswereconsideredwithintheTAD‐suggested20kmrangeofWilsonbutalsooutto50kmtoallowcomprehensiveconsiderationoflargenearbysources.OfthesetheGreenRiverStation,10kmtothesouthofWilsonhasannouncedshutdownoftheirunitsbyApril2016;theTVAParadiseStationabout22kmtothesoutheastofWilsonhasannouncedshutdownofUnits1and2byApril2016leavingUnit3tobeincludedinthemodeling;severalfacilitiesatabout40‐50kmtothenorthwestofWilsonweredistantenoughtofalloutsideoftheTADgeneralconsiderationguidanceandwerelikelycapturedaspartoftheregional,ruralbackgroundconcentration.GiventhisstrategyandcharacterizationofsourcesaffectingairqualityintheOhioCountyarea,modelingperformeddemonstratedthatambientconcentrationsintheareawouldbebelowthe3‐yearaverageofthe99thpercentileoftheannualdistributionofdailymaximum1‐hrconcentrationswhichistheformofthe1‐hourSO2NAAQS.Therefore,thismodelingdemonstratesthattheareawillbeconsideredfordesignationasattainment.

1OrderGrantingJointMotiontoApproveandEnterConsentDecreeandDenyingOtherMotionsasMoot,SierraClubet.al.v.ReginaMcCarthy,AdministratoroftheUnitedStatesEnvironmentalProtectionAgency,UnitedStatesDistrictCourt,NorthernDistrictofCalifornia,DocketNos.120,149,March2,2015.2http://www.epa.gov/airquality/sulfurdioxide/designations/pdfs/sourceareas.pdf3SO2NAAQSDesignationsModelingTechnicalAssistanceDocument,Draft,U.S.EPA,OfficeofAirQualityPlanningandStandards,AirQualityAssessmentDivision,December2013.


2. INTRODUCTION

ThissectionofthemodelingreportprovidesanoverviewoftheWilsonStationalongwithbackgroundinformationforthebasisfortheSO2designationmodeling.

2.1. FACILITY INFORMATION

BigRiversElectricCorporation(BREC)ownsandoperatesa417MWcoalfiredpowerplantinCentertown,KYwhichconsistsofonegeneratingunit(EU01).Thispowergeneratingunitisapulverizedcoalfiredboilerwithamaximumcontinuousratingof4,585MMBtu/hr.TheunitisequippedwithmultiplecontroldevicestoreduceemissionsofpollutantsregulatedundervariousFederalandCommonwealthprograms.Thecontrolsinclude:anelectrostaticprecipitator,lowNOXburners,hydratedlimeinjection,wetfluegasdesulfurization(WFGD),andselectivecatalyticreduction(SCR).Thisunitandotheremissionunits(emergencygenerators,etc.,notconsideredundertheConsentDecree)atWilsonStationaresubjecttopermitunderthenowdraftTitleVoperatingpermitV‐12‐012currentlypendingapprovalbyKDAQ.EU01istheonlysignificantsourceofSO2emissionsatWilsonstationandassuchEU01istheonlysourcerepresentedinthemodelinganalysis.TheD.B.WilsonStationislocatedinOhioCounty,approximately3.5mileseastofthecityofIsland,Kentucky.AnaerialphotographandareamapofthefacilityandsurroundingareaareprovidedinFigures2‐1and2‐2,respectively.Thesemapsshowthefacilityrelativetopredominantgeographicalfeaturessuchasroads,rivers,andtownareasaswellassignificantfeaturesofthepropertyincludingthecontrolledarealinesandbuildings.Figure2‐1showsthecontrolledareaatWilson.Thesefiguresandthelocationsofallemissionsources,structures,andreceptorsinthemodelinganalysisarerepresentedintheUniversalTransverseMercator(UTM)coordinatesystem.ThedatumisbasedonNorthAmericanDatum1983(NAD83).UTMcoordinatesforthisanalysisarelocatedinUTMZone16.ThecentrallocationofWilsonStationisapproximately492,883metersEastand4,144,768metersNorthinZone16oftheUTMsystem.

Figure2‐1.AerialPhotographofWilsonStation


Figure2‐2.AreaMapofWilsonStation

2.2. BASIS FOR ANALYSIS

BigRiversElectricCorporation(BREC)inassociationwithourairqualitycontractor,TrinityConsultants(Trinity)submitsthisdispersionmodelingprotocolfortheairqualityanalysisthatwillbeconductedaspartofarequiredresponsetotherecentenforceableSierraClubvs.ReginaMcCarthyConsentDecree4forthefirstroundofunclassifiedareassubjecttothe20101‐hourSO2NationalAmbientAirQualityStandard(NAAQS).TheBRECfacilitythatfallsunderthisrequirementistheD.B.WilsonStationonStateHighway85locatedinOhioCounty,KentuckyjusteastofIsland,Kentucky.TheareainthevicinityofWilsonStationpossiblyincludingsomeorallofOhioCountyandbecauseofitsproximitymayincludeportionsofMcLeanandMuhlenbergCounties,isrequiredtobedesignatedasattainmentornonattainmentaccordingtoanacceleratedscheduleascomparedtotheDataRequirementsRule(DRR)schedule(promulgatedAugust10,2015)5.UndertheSO2DataRequirementsRule(priortotheconsentdecreewhichisnotdependentontheDRRaspertheconsentdecree),KDAQhadtheoptionofinstallinganewmonitorintheareaaroundWilsonStationorperformingdispersionmodeling.Ineithercase,ascheduleforcompletionofthedesignationswasestablishedasDecember31,2017formodelingandDecember31,2020formonitoring.Undertheconsentdecree,however,thedesignationoftheareaaroundtheWilsonStationmustbecompletednolaterthanJuly2,2016,whichdoesnotallowsufficienttimeforcollectionofthree(3)yearsofvaliddata,letaloneundergoingthemonitorsitingprocess.Thus,KDAQisrequiredtoperformdispersionmodelingoftheWilsonStationtodeterminetheattainmentstatusofthearea.BREChasperformedthismodelinganalysesandisprovidingtheresultstoKDAQtoassistinthe 4OrderGrantingJointMotiontoApproveandEnterConsentDecreeandDenyingOtherMotionsasMoot,SierraClubet.al.v.ReginaMcCarthy,AdministratoroftheUnitedStatesEnvironmentalProtectionAgency,UnitedStatesDistrictCourt,NorthernDistrictofCalifornia,DocketNos.120,149,March2,2015.5DataRequirementsRuleforthe1‐HourSulfurDioxide(SO2)PrimaryNationalAmbientAirQualityStandards(NAAQS):ProposedRule,FederalRegisterVol.79No.92,pages27445‐27472,May13,2014.


designationprocess.ThismodelingfollowsthemethodologyandmodelingguidancefromtheU.S.EPAintheformoftheSO2NAAQSdesignationmodelingguidanceTAD6andassistsinKDAQ’sdeterminationoftheambientlevelsofSO2atthe1‐houraveragingperiodintheareaaroundWilsonStation.ThisreportonlycoversthedispersionmodelingrequirementanddoesnotcovertheotheritemsrequiredtobeincludedinKDAQ’sconsiderationofthefive‐factoranalysiscomponentsfordeterminingtheboundaryoftheattainmentarea.

2.3. REGULATORY BACKGROUND

TheU.S.EnvironmentalProtectionAgency(U.S.EPA)iscurrentlygoingthroughamulti‐phasedesignationprocesswithvariabletimelineswithrespecttothe20101‐hourSO2NationalAmbientAirQualityStandard(NAAQS).TheprocessofdesignatingareashasbeenslowedconsiderablycomparedtoformercriteriapollutantNAAQSwherebymonitoringdatawastheprimarytoolforassessingattainment/nonattainmentstatusofareasaroundthecountry.Inadequatemonitoringatasparsenumberofsitesdoesnotallowthisprimarytooltobeusedasinthepast.Underthecurrentregulatoryguidanceandproposedrules,EPA:

OnJune2,2010issuedanew1‐hrSO2NAAQS, OnSeptember21,2011soughtpubliccommentondraftguidanceforimplementingthenewNAAQS, MayandJune2012heldstakeholdermeetingswithindustry,tradegroups,andenvironmentalgroupstoascertaintheinterestandconcernoverusingdispersionmodelingversusmonitoringdatawhichhadbeenthestandardmethodologypriortothisNAAQS;

February2013developedandreleasedwhitepapersonthestrategyforstatestocharacterizeairqualitynearlargesources,

August5,2013designated29areasin16statesasnonattainmentbasedonmonitoring, 2014,releasedadraftandfinaldraftsetoftwoTechnicalAssistanceDocuments(TADs)offeringguidancetostatesonamethodologytoperformmodeling(modelingTAD)ortoconductsource‐orientedmonitoring(monitoringTAD)tosupportadesignationapproach7,8,

May13,2014releasedtheproposedDataRequirementRule(DRR), AndMarch2,2015signedtheConsentDecreewithSierraClubtorequirecertainlargesourcesacrosstheU.S.toundergoearlyconsiderationfordesignation.

August10,2015releasedthefinalDataRequirementRule(DRR).FollowingtheU.SEPA’sMay2014publicationoftheproposedDataRequirementsRule,theU.S.EPAwassuedfor“failingtoundertakeacertainnondiscretionarydutyundertheCleanAirAct(“CAA”),42U.S.C.§§7401‐7671q,andthatsuchallegedfailureisactionableundersection304(a)(2)oftheCAA,42U.S.C.§7604(a)(2)”.ThelawsuitresultedintheConsentDecreethatwasenteredonMarch2,2015intheU.S.DistrictCourtfortheNorthernDistrictofCalifornia(sameasthatmentionedaboveandreferencedinFootnote1).AsaresultoftheConsentDecree,anadditionaldesignationphasewasaddedtothetwodesignationphasesthatwerealreadyincludedintheU.S.EPA’sMay2014proposedDataRequirementsRule.TheadditionalphaseaffectsareaswithstationarysourcesthatmeetspecificemissioncriterialaidoutintheConsentDecreeanddescribedabove.TheU.S.EPAreleasedamemorandumonMarch20,2015(referredtohereinasthe2015SO2AreaDesignationGuidance)totheRegionalDirectorsclarifyingthepathforwardforstateswithsourcesaffectedbythedecree9.BRECisveryawareoftheserequirementsandhashadinformaldiscussionswithKDAQtodetermineapathforwardtomeetthedeadlinesformodeling,strategicassessment,andeventualdesignationoftheareaaroundtheWilsonStation.

6Ibid.7Ibid.8SO2NAAQSDesignationsSource‐OrientedMonitoringTechnicalAssistanceDocument,draft,U.S.EnvironmentalProtectionAgency,ResearchTrianglePark,NC,December2013.9UpdatedGuidanceforAreaDesignationsforthe2010PrimarySulfurDioxideNationalAmbientAirQualityStandard,memorandumfromStephenPagetoRegionalAirdivisionDirectors,Regions1‐10,March20,2015.


Figure2‐3.Locationof1‐hourSO2ModelingSourcesinRelationtoWilsonStationandNearbyTowns

2.4. EMISSION RATES FOR WILSON STATION

AsdiscussedunderSection5.3AllowableEmissionsoftheguidanceprovidedinthemodelingTAD,thedispersionmodelingcanbeconductedeitheratallowableemissionrateoratactualemissionspreferablyonanhourbyhourbasis.ThemodelingTADstatesthattheapproachofusingallowableemissionsisasimplerwaytoperformthemodelingandprovideairqualityimpactsforthedesignationprocess.TheTADgoesontosaythatanairagencymaychoosetofollowthistypeofapproachiftheconservativeanalysisofthistypestillindicatesattainmentfortheareaofinterest,inthiscasetheOhioCountyareaandsurroundingportionsofothercounties.Forthismodelinganalysis,anallowableemissionratelessthanthecurrentratewasused,namely0.85lbSO2/MMBturatherthanthecurrent1.2lbSO2/MMBtu.AsperSectionV.B.1.(b)oftheproposedDataRequirementsRule,aslongasthislimitisagreedtoandpermittedbythedesignationsprocessdecisiondateofJanuary15,2016(whenKDAQhastoselecteitheramodelingormonitoringpath),itsconsiderationinthemodelingisacceptable.ThismodelingoftheWilsonStationwillallowproactiveparticipationwithKDAQintermsofwhatactionscanbetakenandthedesignationofnonattainmentareaboundariesasdescribedintheMarch20,2015guidancememorandum.Thisdispersionmodeling,thus,istheappropriatetoolfordesignatingattainmentstatusofthearea.


3. 1-HOUR SO2 DESIGNATION MODELING METHODOLOGY

AsprescribedbytheEPAintheDataRequirementsRuleandmodelingTAD,dispersionmodelingwasusedtoevaluatetheattainmentstatusoftheareainthevicinityoftheBRECWilsonStation.EPA’srationaleforallowingtheuseofdispersionmodelingratherthanrequiringnewSO2monitorstobeestablishedarethatSO2sourcesarelimitedindistancetowhereambientconcentrationimpactsoccurandthus,modelingisapplicableandrepresentative.Inpreparationforprovidingmodelingguidancefordesignationanalysis,EPAreviewedSO2ambientmonitoringandmodelingofconcentrationsaroundandnearSO2sourcesandfoundthatmostofthehighestimpactsfallwithinafew10’sofkilometersforlargesourcesandafewkilometersforsmallersources.Alsoofnotewasthatthegradientoftheseconcentrationsfallsoffsignificantlyafterthemaximumisreached.Thus,thismodelingfocusedontheuseofappropriatecomputationalmethodssuchthatEPA’sprimarypreferredindustrialsourcemodel,theAERMODModel,istheprimarymodelrecommendedforuse.InadditiontoAERMODandtoallowthebestrepresentationofsimulatedambientairconcentrations,themodelingTADrecommends:

Usingactualemissionsasaninputforassessingviolationstoprovideresultsthatreflectcurrentactualairquality(i.e.,modelingthatsimulatesamonitor)oruseallowableemissionswhichwillresultinamoreconservativeestimateofactualambientairimpactsofthesource;

Usingthreeyearsofmodelingresultstocalculateasimulateddesignvalueconsistentwiththe3‐yearmonitoringperiodrequiredtodevelopadesignvalueforcomparisontotheNAAQS;

Placingreceptorsforthemodelingonlyinlocationswhereamonitorcouldbeplaced;and UsingactualstackheightsratherthanfollowingtheGoodEngineeringPractice(GEP)stackheightpolicywhenusingactualemissionsandtheGEPstackheightwhenusingallowableemissions.

FollowingthesemodelingguidelinesforDRRmodeling,dispersionmodelingwasperformedfortheWilsonStationandtheareaaroundit.TheremainderofthissectionprovidesanoverviewofthemodelingthatwasfollowedfortheWilsonStationwhichwasapprovedbyKDAQ10inthemodelingprotocol11submittedforWilsonStationmodeling.

3.1. MODEL SELECTION

Modelingwasperformedfor1‐hourSO2analysisusingtheAERMODModelinitsmostcurrentversionatthetimeofthemodeling.ThecurrentapplicableversionisVersion15181whichreleasedbyU.S.EPAonJuly24,2015.U.S.EPAalsoreleasedanupdatedproposedversionofitsmodelingguidanceintheformoftheGuidelineonAirQualityModels12aboutthatsametime.ThisproposedguidanceandenhancedAERMODmodelhasnewbetaoptionsthatareexpectedtoaffecttheoutcomeofdesignationmodelingwithrespecttosomeofthelowwindoptions(LOWWIND)inthemodel.AsofthereleaseoftheproposedGuideline,theoptionsremainedbetaandweresubjecttoscrutinyattheU.S.EPARegionalandClearinghouselevelpriortouse.TheseoptionswerenotusedinthismodelingfortheWilsonStation.OftheoptionsintheAERMODModel,thefollowingwereselected.Thepollutantidentificationwassetto“SO2”inAERMOD,whichallowedadditionalinternalmodeloptionstobeavailablethusenablingtheoutputoptionsto

10LetterfromBenCordes,Supervisor,AirDispersionModelingSectiontoMarkBertram,BigRiverElectricCorporation,July15,2015.11AirDispersionModelingProtocolWilsonStationSo2DesignationAnalysis,preparedforBigRiversElectricCorporation,preparedbyTrinityConsultants,Covington,Kentucky,June12,2015.12Guideline on Air Quality Models. Appendix W to 40 CFR Parts 51 and 52. Federal Register, November 9, 2005. pp. 68217-68261.


beconfiguredproperlyforSO2.Becauseoftheprobabilisticformofthe1‐hourNAAQS,selectingthesecorrectinputoptionsallowedAERMODtoproperlycalculateanSO2designvaluebasedonthe3‐yearaverageofthe99thpercentileoftheannualdistributionofthedailymaximum1‐hourconcentrationsforcomparisonwiththe1‐hourSO2NAAQSof75ppb(196g/m3).

3.2. RURAL URBAN OPTION IN AERMOD

AsstatedbySection6.3,Urban/RuralDeterminationofthemodelingTAD,foranydispersionmodelingexerciseforSO2,the“urban”or“rural”determinationofthelocationsurroundingthesubjectsourceisimportantindeterminingtheapplicableboundarylayercharacteristicsthataffectamodel’scalculationofambientconcentrationsaswellasthepossibleinvocationofAERMOD’s4‐hourhalf‐life.Thus,adeterminationwasmadeofwhethertheareaaroundtheWilsonStationwasurbanorrural.ThefirstmethoddiscussedinthemodelingTAD(alsoreferredthereintoSection7.2.3coftheGuidelineonAirQualityModels,AppendixW)wasusedtodeterminetheurbanorruralstatusoftheareaaroundWilson.Thisistheso‐called“landuse”techniquebecauseitexaminesthevariouslandusewithin3kmofWilsonandquantifiesthepercentageofareainvariouslandusecategories.Followingthisguidance,2011landusedata(mostrecentavailable)wereobtainedfromtheU.S.GeologicalSurvey13throughArcGISanda3kmradiuscircleinscribedelectronicallyaroundtheWilsonstackcoordinates.AlldataweregeoreferencedandtabulatedusingthecategoriesshowninTable3.1forurbanandruraldesignation.

Table3‐1.ModelingTADUrban/RuralCategories

Figure3‐1showsthelayoutofthelandusewheregreens,yellowsandbrownsarefarmland,forests,andgrassesandredandpinksareurbanareas.Table3‐2showstheresultsofthislandcategorizationprocess.Ascanbeseentheareaispredominantlyruralbyanoverwhelmingmarginat99.2percentandthereforewastreatedasruralintheAERMODModel.

13http://www.mrlc.gov/viewerjs/

Modeling TAD Rural or Urban

11 Open Water A5 Water Surfaces rural

12 Perennial Ice/Snow A5 Water Surfaces rural

21 Developed, Open Space A1 Metropolitan Natural rural

22 Developed, Low Intensity R1 Common Residential rural

23 Developed, Medium Intensity I1, I2, C1, R2, R3Industrial/Commercial/Compact

Residentialurban

24 Developed, High Intensity I1, I2, C1, R2, R3Industrial/Commercial/Compact

Residentialurban

31 Barren Land A3 Undeveloped (Grasses/Shrub) rural

41 Deciduous Forest A4 Undeveloped (Wooded) rural

42 Evergreen Forest A4 Undeveloped (Wooded) rural

43 Mixed Forest A4 Undeveloped (Wooded) rural

52 Shrub/Scrub A3 Undeveloped (Grasses/Shrub) rural

71 Grassland/Herbaceous A3 Undeveloped (Grasses/Shrub) rural

81 Pasture/Hay A2 Agricultural rural

82 Cultivated Crops A2 Agricultural rural

90 Woody Wetlands A4 Undeveloped (Wooded) rural

95 Emergent Herbaceous Wetlands A3 Undeveloped (Grasses/Shrub) rural

Auer Land-Use Classification2011 NLCD Land Cover Classification


Figure3‐1.DistributionofLandUseWithin3kmofWilsonStation

Table3‐2.WilsonStationUrban/RuralDetermination

CategoryID

CategoryDescription Percent

11 OpenWater 3.8%

21 Developed,OpenSpace 4.3%

22 Developed,LowIntensity 0.4%

23Developed,MediumIntensity

0.3%

24Developed,HighIntensity

0.1%

31 BarrenLand 0.7%41 DeciduousForest 27.3%

42 EvergreenForest 0.1%

43 MixedForest 0.0%

52 Shrub/Scrub 0.0%

71 Grassland/Herbaceous 1.9%

81 Pasture/Hay 8.9%

82 CultivatedCrops 44.1%

90 WoodyWetlands 4.3%

95 EmergentHerbaceousWetlands 3.8%

Total 100%

Urban 0.8%

Rural 99.2%

PercentLandCategorizationArcGISAnalysisResultsforWilsonStation


3.3. METEOROLOGICAL DATA

MeteorologicaldatawasrequiredasinputtotheAERMODmodeltoallowthecharacterizationofthetransportanddispersionoftheWilsonStationSO2emissionsintheatmosphere.AsperthemodelingTAD,threeyearsofrecentdatawereobtained.OnsitemeteorologicaldatawascollectedbyBREC.Apreliminaryevaluationoftheonsitemeteorologicaldataindicatedthatthe2014datawasavailableandthus,wasevaluatedforinclusioninthestudy.ThewindinstrumentsarelocatedonthenorthwestportionoftheBRECpropertyonacellandmicrowavetransmissiontower.Theplacementanddispositionoftheinstrumentswereevaluatedtodetermineiftheywerelocatedsuchthatthetowerwasnotinfluencingthereadingofwindspeedanddirectionandcausinganypotentialbiasinthedatapriortouse.Althoughonsitedataaregenerallypreferredformodeling,inthiscasetheproximityoftheinstrumentsensorstothecelltoweronwhichtheywereplaceddidnotmeetthesitingcriteriaforsuchinstrumentswhichcausedsignificantbiasinthemeasurements.Therefore,thisdatawasnotconsideredfurtherfortheanalysis.Data,therefore,wereobtainedfromtheNationalWeatherService(NWS).Thedatacollectedwasreportedinthreeformatsincludingsurfacedatainboththehourlyaveragedformataswellastheminutedataandupperair(radiosonde)meteorologicaldata.Themostrecentthreefullyeardataset(2012,2013,and2014)wasobtainedandprocessedfromarchiveddatafromthemostrepresentativeNWSmeteorologicalstationinthevicinityoftheWilsonStation.Thisrepresentativenesswasdeterminedonthebasisofproximity,similarityintermsoflanduse(anditseffectonsurfaceroughness,albedo,andBowenratio),andmeteorologicaljudgementastoapplicabilitytotheWilsonStationarea.Detailsonthedataselectionareprovidedinthefollowingsubsections.AERMOD‐readymeteorologicaldatawerepreparedusingthelatestversionoftheAERMETmeteorologicalprocessingutility(Version15181).StandardU.S.EPAmeteorologicaldataprocessingguidancewasusedasoutlinedinarecentU.S.EPAmemorandum14aswellasotherAERMETandassociatedprocessordocumentation.NWSsiteswerelocatednearbyandwereofsimilargeographicalsettingtotheWilsonStation.ApreliminaryevaluationoftheNWSmeteorologicaldatasiteswithinapproximately150kmindicatedthatseveralairportswerelocatedintheregion.SeveraloftheseweresmallerairportsintheregionincludingMadisonvilleMunicipalAirport(MADI,30kmtoWilsonStation),Owensboro‐DaviesCountyAirport(KOWB,34kmtoWilsonStation),andHendersonCity‐CountyAirport(66kmtoWilsonStation)andareincloseproximitytotheWilsonStation.However,eachofthesesmallerairportslacksufficienthour‐by‐hourfullyearmeteorologicaldatasetsthatcanbeusedinthedispersionmodeling.Thus,otherairportswereevaluatedintheregion.Figure3‐2showsthelocationsoftheairportshavingmeteorologicaldatasetsthatwereconsideredforthismodeling.Ofthesecandidatesites,themostrepresentativesite,theEvansvilleRegionalAirport,wasoneofonlythreesiteshavingthesufficienthour‐by‐hourandone‐minutemeteorologicaldatasetsthatcanbeusedinthedispersionmodeling.Table3‐3presentstheresultsofaNWSidentificationexercisebasedonproximitytoWilsonStationandavailabilityofdatawithallcandidatesites.AscanbeseenthethreesmallerairportsarecloserthanEvansvillebutfailtohaveadequatedata.Ascanbeseen,othercandidatesitesarelocatedfartherawayandinadifferentgeographicalsettingthantheWilsonStation.

14Fox,Tyler,U.S.EnvironmentalProtectionAgency.2013.“UseofASOSMeteorologicalDatainAERMODDispersionModeling.”AvailableOnline:http://www.epa.gov/ttn/scram/guidance/clarification/20130308_Met_Data_Clarification.pdf


Figure3‐2.MeteorologicalStationsandSO2MonitorsintheAreaNearWilsonStation

Themostrepresentative2012‐2014surfacemeteorologydatawasdeterminedtobefromtheEvansvilleRegionalAirport(KEVV,WBANNo.93817)withupperairdatafromtheNashvilleInternationalAirport(KBNA,WBANNo.13897).TheEvansvilleRegionalAirportliesabout76.5kmtothenorthwestoftheWilsonStation.

3.3.1. Surface Data

UnprocessedhourlysurfacemeteorologicalfielddatawasobtainedfromtheU.S.NationalClimaticDataCenter(NCDC)fortheEvansvilleRegionalAirport(KEVV)for2012‐2014inthestandardISHD(integratedsurfacehourlydata)format15.Thisdatawassupplemented,asrecommendedbytheU.S.EPAwithTD‐6405format(so‐

15ftp://ftp.ncdc.noaa.gov/pub/data/noaa/


Table3‐3.ProximityAnalysisofMeteorologicalStationstoWilsonStation

called“1‐minute”)winddataalsofromtheKEVVarchives16andprocessedusingthelatestversionoftheAERMINUTEpre‐processingtool(version14337).The“Ice‐FreeWindsGroup”AERMINUTEoptionwasselectedforprocessingduetothefactthatasonicanemometerhasbeeninstalledatKEVVin2006.

3.3.2. Upper Air Data

Inadditiontosurfacemeteorologicaldata,AERMETrequirestheuseofdatafromanupperairsoundingtoestimatemixingheightsandotherboundarylayerturbulenceparameters.UpperairdatafromthenearestU.S.NWSradiosondeequippedstationwasutilizedinthemodelinganalysis.Inthiscase,upperairdatafromtheNashvilleInternationalAirport(KBNA,WBANNo.13897)wasobtainedfromtheNationalOceanicandAtmosphericAdministration(NOAA)inFSL(ForecastSystemsLaboratory)format17.

3.3.3. Land Use Analysis

Parametersderivedfromanalysisoflandusedata(surfaceroughness,Bowenratio,andalbedo)arealsorequiredbyAERMET.InaccordancewithU.S.EPAguidance,thesevalueswillbedeterminedusingthelatestversionoftheAERSURFACEtool(version13016).18AERSURFACEreadsgriddedlanduse,landcoverdataasprovidedbytheUSGS19andassociatessuchdatawithrepresentativevaluesofthethreeparameterslistedabove.SpecificAERSURFACEsettingswillbeusedthatrepresentthelocationoftheEvansvillemeteorologicalstation.Theseincludesettingslikelocationcoordinates,monthlyversusseasonaldifferentiation,aridity,andsurfacemoisturedetermination.ThesurfacemoisturewillbedeterminedbasedonwhetherprecipitationattheEvansvilleAirportisclassifiedaswet,dry,oraverageincomparisontoarecent30‐yearclimatologicalrecordatthesite.ThisdeterminationisusedinAERSURFACEtoadjusttheBowenratioestimatedbyAERSURFACEwhich

16ftp://ftp.ncdc.noaa.gov/pub/data/asos‐onemin17http://www.esrl.noaa.gov/raobs/18U.S.EnvironmentalProtectionAgency.2013.“AERSURFACEUser’sGuide.”EPA‐454/B‐08‐001,Revised01/16/2013.AvailableOnline:http://www.epa.gov/scram001/7thconf/aermod/aersurface_userguide.pdf19http://www.mrlc.gov/viewerjs/

StationName

WBANStationID

StationCallSign Lat. Long.

UTMEast(m)

UTMNorth(m)

ASOSOneMinuteDataAvailable

DistancetoWilson(km)

MadisonvilleMunicipalAirpor 00421 MADI 37.350 ‐87.400 464,573 4,133,775 No 30.4Owensboro‐DaviessCountyAirp 53803 KOWB 37.750 ‐87.167 485,288 4,178,091 No 34.2HendersonCity‐CountyArpt 53886 KEHR 37.800 ‐87.683 439,872 4,183,845 No 65.9EvansvilleRegionalAirport 93817 KEVV 38.044 ‐87.521 454,285 4,210,825 Yes 76.5BowlingGreen21Nne 63849 NBWG 37.250 ‐86.233 568,021 4,122,882 No 78.3BowGrn‐WarrenCo.RgnlAp 93808 KBWG 36.965 ‐86.424 551,274 4,091,145 Yes 79.3HuntingburgAirport 53896 KHNB 38.249 ‐86.954 504,025 4,233,444 No 89.4CampbellAafAirport 13806 KHOP 36.667 ‐87.483 456,838 4,058,041 No 93.9Clarksville 03894 KCKV 36.624 ‐87.419 462,536 4,053,245 Yes 96.4GodmanAafAirport 13807 KFTK 37.900 ‐85.967 590,819 4,195,223 No 110.2GlasgowMunicipalAirport 00361 KGLW 37.033 ‐85.950 593,386 4,099,049 No 110.4CarmiMinicipalAirport 63840 KCUL 38.089 ‐88.123 401,521 4,216,285 No 116.0Harrisburg‐RaleighAirport 53897 KHSB 37.811 ‐88.549 363,649 4,185,976 No 135.6MountCarmelMunicipalAirpor 63853 KAJG 38.607 ‐87.727 436,701 4,273,417 No 140.4LouisvilleIntl‐StandifordF 93821 KSDF 38.181 ‐85.739 610,442 4,226,649 Yes 143.3KyleOakleyFieldAirport 00437 KCEY 36.665 ‐88.373 377,299 4,058,589 No 144.2BowmanFieldAirport 13810 KLOU 38.228 ‐85.664 616,936 4,231,956 Yes 151.6NashvilleInternationalAirpo 13897 KBNA 36.119 ‐86.689 527,988 3,997,192 Yes 151.7Lrncvll‐VincnesIntlArpt 13809 KLWV 38.764 ‐87.606 447,351 4,290,762 Yes 152.9FairfieldMunicipalArpt 53891 KFWC 38.379 ‐88.413 376,581 4,248,812 No 156.0Olney‐NobleAirport 53822 KOLY 38.722 ‐88.176 397,769 4,286,584 No 170.8FloraMunicipalAirport 53889 KFOA 38.665 ‐88.453 373,588 4,280,604 No 180.8CentralCoordinatesofWilson: 492,883 4,144,768


inturnaffectsthecalculationofthedaytimemixingheightsusedinAERMOD.Tomakethemoistureconditionsdetermination,climatologicalrecordsoftheannualprecipitationineachmodeledyear(2012‐2014)willbecomparedtothe1985‐2014climatologicalrecordforeachsite20.Table3‐4showsthe30yearprecipitationbymonthforEvansvillealongwiththeseasonaltotals,averages,and30thpercentilehighandlowvalues.ThesewerecomparedtotheactualrainfallineachseasonforeachyearofJanuary1,2012throughDecember31,2014whichdeterminedtheaverage,wet,ordryoptioninAERSURFACEforeachyearandeachseason.

3.4. COORDINATE SYSTEM

Inallmodelinginputandoutputfiles,thelocationsofemissionsources,structures,andreceptorswillberepresentedintheappropriateZoneoftheUniversalTransverseMercator(UTM)coordinatesystemusingtheNorthAmericanDatum1983(NAD83).TheWilsonStationandthesurroundingarealieswithinZone16.

3.5. RECEPTOR LOCATIONS

ThedispersionmodelingfollowedtheguidanceofthemodelingTADintermsofonlyputtingreceptorsinareaswhereitisfeasibletoplaceanactualmonitor.AsshownintheexampleFigure3‐3fromthemodelingTAD,noreceptorswereplacedinlakes,riversorsimilarareas.AsthemodelingTADstates:

receptorplacementshouldbeofsufficientdensitytoprovideresolutionneededtodetectsignificantgradientsintheconcentrations,withreceptorsplacedclosertogethernearthesourcetodetectlocalgradientsandplacedfartherapartawayfromthesource.Inaddition,theusershouldplacereceptorsatkeylocationssuchasaroundfacilityfencelines(whichdefinetheambientairboundaryforaparticularsource)ormonitorlocations(forcomparisontomonitoredconcentrationsformodelevaluationpurposes).

ThereceptorgridforthemodelingoftheWilsonStationcombinedamulti‐nestedCartesiangridatvariousspacingcenteredonthemainWilsonStationstackalongwithreceptorpointsalongthefacility’scontrolledarea.Fortheairdispersionmodelinganalyses,ground‐levelconcentrationswerecalculatedfromthecontrolledareaoutto50km.Thereceptorsarecharacterizedbythefollowinggrids:

FenceLineGrid:“Fenceline”gridconsistingofevenly‐spacedreceptors50metersapartplacedalongthecontrolledareaoftheWilsonStationincludingthemaingenerationarea,coalpilesandconveyingareasandtheashlandfills,

FineCartesianGrid:A“fine”gridcontaining100‐meterspacedreceptorsextendingto3kmfromthecenterofthepropertyandbeyondthefenceline,includingreceptorsalongStateRoute85,

Medium‐FineCartesianGrid:A“medium‐fine”gridcontaining250‐meterspacedreceptorsextendingfrom3kmto5kmfromthecenterofthefacility,exclusiveofreceptorsonthefinegrid,

20NationalClimacticDataCenter.2014LocalClimatologicalData(LCD).


Table3‐4.MoistureCalculationforEvansvilleAirport(inchesofprecipitation)

Figure3‐3.ModelingTADReceptorGridShowingExampleExcludedLocationsOverWater

YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANNUAL Winter Spring Summer Fall1985 1.76 4.24 6.10 3.80 2.97 4.68 1.18 3.76 3.59 4.46 7.61 1.74 45.89 7.74 12.87 9.62 15.661986 1.15 5.77 2.64 2.29 2.93 3.77 5.39 2.07 3.84 3.30 2.35 2.18 37.68 9.10 7.86 11.23 9.491987 0.77 3.51 2.11 2.31 3.90 5.97 3.19 0.47 1.98 1.23 3.36 5.71 34.51 9.99 8.32 9.63 6.571988 3.28 3.94 2.89 1.77 1.33 1.11 6.63 2.72 1.19 2.86 7.96 2.75 38.43 9.97 5.99 10.46 12.011989 3.35 7.00 6.40 4.19 3.72 4.00 7.83 3.46 2.21 2.16 1.64 1.38 47.34 11.73 14.31 15.29 6.011990 4.26 5.60 2.15 3.75 11.34 3.22 1.01 3.47 2.54 4.81 2.92 7.45 52.52 17.31 17.24 7.70 10.271991 3.02 2.99 4.27 2.56 3.11 0.65 2.58 0.46 2.60 3.05 3.67 3.72 32.68 9.73 9.94 3.69 9.321992 0.85 1.51 4.50 1.19 3.44 1.44 8.40 4.39 2.89 1.17 4.34 1.69 35.81 4.05 9.13 14.23 8.401993 3.57 2.61 3.23 4.38 4.20 4.65 2.37 2.17 5.59 3.76 6.62 2.68 45.83 8.86 11.81 9.19 15.971994 3.18 2.32 1.88 5.77 0.94 3.45 2.30 2.52 2.61 2.67 6.52 2.59 36.75 8.09 8.59 8.27 11.801995 2.82 2.98 2.53 5.59 13.51 4.56 2.88 3.60 0.47 2.01 2.32 3.19 46.46 8.99 21.63 11.04 4.801996 3.51 1.50 5.19 11.83 7.32 7.78 4.56 1.20 8.45 2.53 6.66 3.50 64.03 8.51 24.34 13.54 17.641997 4.20 3.35 6.90 4.16 7.57 6.12 1.71 4.02 1.31 1.73 4.17 2.34 47.58 9.89 18.63 11.85 7.211998 2.24 2.71 3.07 8.50 5.91 5.31 3.89 3.91 0.49 3.38 2.78 3.48 45.67 8.43 17.48 13.11 6.651999 6.00 1.94 4.30 6.15 3.21 6.27 2.00 0.64 0.39 2.80 0.51 5.13 39.34 13.07 13.66 8.91 3.702000 4.36 7.26 3.21 2.35 2.60 5.86 4.14 5.60 5.03 0.59 3.43 4.12 48.55 15.74 8.16 15.60 9.052001 1.29 3.26 2.23 1.60 3.82 3.82 5.54 6.09 2.40 7.27 5.40 7.16 49.88 11.71 7.65 15.45 15.072002 3.72 0.74 6.20 8.58 5.70 2.86 4.32 0.63 5.22 3.75 2.97 5.65 50.34 10.11 20.48 7.81 11.942003 0.90 4.92 2.60 3.91 6.48 4.50 4.38 1.88 3.17 1.61 4.36 1.20 39.91 7.02 12.99 10.76 9.142004 2.95 0.59 2.17 1.91 9.31 1.66 7.56 3.08 0.09 5.62 6.23 2.31 43.48 5.85 13.39 12.30 11.942005 4.59 2.77 2.85 2.13 2.33 4.88 2.69 8.51 2.00 0.73 5.93 1.76 41.17 9.12 7.31 16.08 8.662006 4.09 2.17 9.36 3.44 5.77 3.73 6.46 7.41 8.75 5.46 4.95 4.59 66.18 10.85 18.57 17.60 19.162007 5.47 3.41 2.66 2.88 2.73 2.71 1.97 0.99 2.22 4.64 1.77 6.34 37.79 15.22 8.27 5.67 8.632008 3.97 5.97 12.34 5.07 8.07 3.09 3.90 0.52 1.16 1.61 3.42 4.76 53.88 14.70 25.48 7.51 6.192009 2.85 2.76 3.32 6.01 6.47 2.20 6.46 1.91 5.17 8.21 1.22 3.62 50.20 9.23 15.80 10.57 14.602010 2.41 1.58 3.97 3.27 3.03 2.49 3.51 0.84 0.36 1.06 8.46 1.80 32.78 5.79 10.27 6.84 9.882011 1.65 4.52 5.34 11.77 7.90 6.52 6.66 0.62 8.20 2.49 8.32 6.04 70.03 12.21 25.01 13.80 19.012012 3.39 1.75 2.51 1.44 2.29 0.15 2.34 4.10 7.60 2.90 1.19 3.47 33.13 8.61 6.24 6.59 11.692013 6.76 2.77 4.08 3.86 5.08 7.55 3.59 1.64 2.81 6.07 2.04 7.33 53.58 16.86 13.02 12.78 10.922014 1.69 2.26 2.85 10.97 3.72 3.87 4.02 4.80 2.55 4.20 2.85 3.43 47.21 7.38 17.54 12.69 9.60

Precipitationlocationfromhttp://www.ncdc.noaa.gov/cdo‐web/datatools/findstation Upper30th 11.11 17.31 12.88 11.94KEVVprecipitationdata‐obtained2014cumulativereportfromhttp:/wwwi.ncdc.noaa.gov/pub/orders Lower30th 8.58 8.97 9.11 8.65

A=AveragePrecipitation 2012 A D D AW=WetPrecipitation 2013 W A A AD=DryPrecipitation 2014 D W A A


Medium‐CoarseCartesianGrid:A“medium‐coarse”gridcontaining500‐meterspacedreceptorsextendingfrom5kmto10kmfromthecenterofthefacility,exclusiveofreceptorsonthefineandmedium‐finegrids,

CoarseCartesianGrid:A“coarsegrid”containing1,000‐meterspacedreceptorsextendingfrom10kmto20kmfromthecenterofthefacility,exclusiveofreceptorsonthefine,medium‐fine,andmedium‐coarsegrids.

VeryCoarseCartesianGrid:A“verycoarsegrid”containing2,000‐meterspacedreceptorsextendingfrom20kmto50kmfromthecenterofthefacility,exclusiveofreceptorsonthefine,medium‐fine,medium‐coarse,andcoarsegrids.

Thelattergridextendedoutto50kmandwasdeemedadequatetocapturethemaximumimpactsofWilsonStationandcombinedimpactsduetoothernearbysourcesandbackgroundconcentrations.Thisdomaindistancewasdeemedsufficienttocapturethedistancestomaximumconcentrationsaswellasthesignificantgradientsofconcentrations.Figures3‐4and3‐5showtheinnermostgridsofthereceptorsaswellastheoverallreceptorgridacrossthemodelingdomain,respectively.Ascanbeseen,receptorsinvariousnearbycreeksandlakeshavebeeneliminatedfromtheanalysis.Alsoshownisthecurrentcontrolledareaofthefacility(innermostlineofyellowreceptors).

Figure3‐4.InnermostPortionoftheModelingReceptorGridforWilson


Figure3‐5.OverallModelingReceptorGridforWilson

3.6. TERRAIN ELEVATIONS

Theterrainelevationforeachreceptor,building,andemissionsourceweredeterminedusingUSGS1arc‐secondNationalElevationData(NED).TheNED,obtainedfromtheUSGS21,hasterrainelevationsat30‐meterintervals.UsingtheAERMODterrainprocessor,AERMAP(version11103),theterrainheightforeachreceptor,building,andemissionsourceincludedinthemodelweredeterminedbyassigningtheinterpolatedheightfromthedigitalterrainelevationssurroundingeachpointofinterest.ThesewereuseddirectlyintheAERMODmodel.Inaddition,AERMAPwasusedtocomputethehillheightscalesassociatedwitheachelevatedreceptorlocatedatadifferentelevationthanthebaseoftheWilsonstack.ThiscomputationenabledtheAERMODModeltodeterminetheeffectthatterrainhasonplumesfromtheWilsonstackaswellasothersourcesconsidered.AERMAPsearchesallnearbyelevationpointsfortheterrainheightandlocationthathasthegreatestinfluenceoneachreceptortodeterminethehillheightscaleforthatreceptor.AERMODthenusesthehillheightscaleinordertoselectthepointwhereaplumemaydividebetweengoingaroundaterrainfeatureandloftingoverthefeature.InitialreviewoftheareadoesnotindicatethatanysignificantterrainfeaturesexistneartheWilsonStation,buttheterrainwillbeincorporatedasrequired.

21http://www.mrlc.gov/viewerjs/


3.7. WILSON STATION EMISSION SOURCES

TheWilsonStationhasonlyonesourceofSO2emissions,whichistheflueinthemainstackassociatedwithcoal‐firedUnit1.Table3‐5belowsummarizesthestackparametersthatwereusedinthisinitialmodelingoftheWilsonStationmainstack.Modelingwasperformedatanemissionrateof0.853lbSO2/MMBtuand4,585MMBtu/hrcapacitywhichisalimitthatBRECiswillingtotakefortheWilsonStation.ThisuseofanewallowableemissionratelimitiscommensuratewiththeproposedDataRequirementsRuleguidanceforemissionstobeconsideredformodelinginSectionV.B.1.b(Emissions–AccountingforRecentEmissionReductionsinModelingAnalyses22).AsstatedinSectionV.B.1.b:

…theairagencymaywishtoconsultwiththesourceandconductadditional(modeling)analysiswiththesourcetoidentifyacontrolmeasureoranemissionlimitthatwouldensureattainmentwiththe1‐hourSO2standardfortheareaaroundthesource.

Thus,BREChaselectedtoperformthismodelingtoassistKDAQindemonstratingthattheareaaroundtheWilsonStationisinattainmentviathemodelingroute.ThisemissionlimitwouldbeenforceablebyJanuary2017andthus,qualifiesforthismodelingdemonstration.AsperthemodelingTADandguidanceonareadesignations,ifthisanalysisresultsinconcentrationslessthantheNAAQS,thentheareacanbedesignatedattainment.InthespiritofthemodelingTADandrelatedDRRguidance,themodelingwasperformedtosimulatewhatamonitormayhavemeasuredifonehadbeenavailable.Tothisend,themodelinghereindemonstrateswhattheambientairqualitywouldbeifamonitorweremeasuringtheairqualityintheareaafterthenewlimitisset.

Table3‐5.WilsonStationSourceCharacterization

StackIdentification

XCoordinate

(m)a

YCoordinate

(m)a

StackHeight(ft)

StackDiameter

(ft)

ExitVelocity(ft/s)

FlowRate(acfm)

ExitTemperature

(˚F)

EmissionRate(lb/hr)

Unit1b 492,876.8 4,144,766 600 22 67.4 1,536,428 130 3,911 aUTMZone16,NAD83.

bAtapermittedrateof0.853lbSO2/MMBtuand4,585MMBtu/hrcapacity.MostothersourcesattheWilsonStationarerelatedtocoalandashhandling,conveying,andtransportanddonotrelatetoSO2emissions.HowevertwoothersourcesofSO2emissionsattheWilsonStationfacilityincludea380hpFirePumpengine(EU06)whichrunsondieselfuelandan1,130hpemergencygeneratorwhichrunsondieselfuel.AccordingtothependingTitleVpermitfortheWilsonStation,eachunitislimitedto50hoursofnon‐emergencyoperation.Maintenancechecksandreadinesstestingoftheseunitsislimitedto100hoursperyear.AccordingtothemodelingTAD,Section5.4IntermittentEmissions,onlysourcesthatarecontinuousorfrequentenoughtocontributesignificantlytotheannualdistributionofmaximumdaily1‐hourconcentrationsshouldbeconsidered.AspertheTAD‐referencedU.S.EPAclarificationmemorandum23,forthereasonsstatedtherein,i.e.,thesesourcesdonotoperatecontinuousoroftenenoughtocontributetotheannualdistributionofdailymaximum1‐hourSO2concentrations,thesetwosourceswereexcludedfromthedispersionmodelingoftheWilsonStation.NoothersourcesofSO2emissionsexistattheWilsonStation.

22FRVolume79No.92,DataRequirementsRuleforthe1‐HourSulfurDioxide(SO2)PrimaryNationalAmbientAirQualityStandard(NAAQS);ProposedRule,May13,2014,pp27464‐27465.23AdditionalClarificationRegardingApplicationofAppendixWModelingGuidanceforthe1‐HourNO2NationalAmbientAirQualityStandard,fromTylerFox,LeadertoRegionalAirDivisionDirectors,U.S.EnvironmentalProtectionAgency.March11,2011.


3.8. OTHER SOURCE INVENTORY

OthersourcesofSO2emissionsintheareasurroundingtheWilsonStationwereincludedasrequiredforthemodelingoftheWilsonStationtofullycharacterizetheairqualityinthearea.Sourceswithinabout20kmofWilsonwereincluded(orlargesourcesjustbeyondthe20kmrange)inthemodelingandwereobtainedfromavailableinventoriesfromKDAQ.Otherlargesourcesinthe20kmto50kmrangefromWilsonwerereviewedtodetermineiftheyshouldbeincludedinthemodelingandwerereviewedonthebasisofKDAQdataarchivesaswellasfromaperspectiveofpossiblefutureshutdowns(therebynotrequiringconsideration).Datasetswerereducedbyeliminatingverysmallsources(lessthan100tonsperyear).Figure3‐5showsmajorsourcesofSO2emissionswithinthe50kmrangeofWilson.

Figure3‐6.MapShowingRegionalSO2SourcesNearWilsonStation

Asummaryoftheconsiderationofeachsourceintheareaisasfollows:

WilsonStation,Unit1–modeledat0.853lbSO2/MMBtu.


TVA–ParadiseStation–Units1and2willshutdownbyApril201624;Unit3modeledusinghourly2013‐2014CEMsdatafromtheU.S.EPAAirMarketsProgramDataforemissionsonly25;temperatureandgasexitvelocitywerenotavailableandwere,thereforesetequaltothatintheKDAQarchivedata.

GreenRiverStation–allunitswillshutdownbyApril201626.

CenturyAluminumlocatedover40kmtothenorthwestofWilsonStationwasdistantenoughthatitsimpactswouldbesignificantlyreducedintermsofitsimpactsoverlappingwiththoseofWilsonStation;SO2impactsweretreatedasregionalinnatureandassumedtobecapturedbytheambientmonitorattheHendersonCountymonitorlocatedattheBaskettFireHouse(AQS‐ID21‐101‐0014)whichisdownwindalargeportionofthetimewhenwindsarefromthesouthwestthroughsoutheastasshownbythemonitorlocationandwindrosefor2012‐2014inFigure3‐6.

TheReid/HendersonStationIIGeneratingStationandBRECLandfillarelocatedover40kmtothenorthwestofWilsonStation,whichisdistantenoughthattheirimpactswouldbesignificantlyreducedintermsofitsimpactsoverlappingwiththoseofWilsonStation;SO2impactsweretreatedasregionalinnatureandassumedtobecapturedbytheambientmonitorattheHendersonCountymonitorlocatedattheBaskettFireHouse(AQS‐ID21‐101‐0014)whichisdownwindalargeportionofthetimewhenwindsarefromthesouthwestthroughsoutheastasshownbythemonitorlocationandwindrosefor2012‐2014inFigure3‐6.

GreenStationlocatedover40kmtothenorthwestofWilsonStationwasdistantenoughthatitsimpactswouldbesignificantlyreducedintermsofitsimpactsoverlappingwiththoseofWilsonStation;SO2impactsweretreatedasregionalinnatureandassumedtobecapturedbytheambientmonitorattheHendersonCountymonitorlocatedattheBaskettFireHouse(AQS‐ID21‐101‐0014)whichisdownwindalargeportionofthetimewhenwindsarefromthesouthwestthroughsoutheastasshownbythemonitorlocationandwindrosefor2012‐2014inFigure3‐6.

TheElmerSmithStationislocatedabout35kmtothenorthofWilsonStationandisdistantenoughandinalocationthatisnotlikelytooverlapwiththemaximumconcentrationsduetoWilsonnorisWilsonlikelytocontributesignificantlytoconcentrationsinthevicinityofElmerSmithStation.

Thus,onlyTVAParadiseUnit3wasincludedasadirectsourceinthemodelinganalysis.Table2‐2providesthepertinentsourcesparametersandemissionsforthisunit.

Table3‐6.NearbySourceCharacterization

StackIdentification

XCoordinate

(m)a

YCoordinate

(m)a

StackHeight(ft)

StackDiameter

(ft)

ExitVelocity(ft/s)

FlowRate(acfm)

ExitTemperature

(˚F)

EmissionRate

(lb/hr)bTVA3‐EU03 502,305.5 4,123,697.4 600 37 50.44 3,254,000 130 CEMS aUTMZone16,NAD83.

bBasedonCEMSemissiondatafrom2012‐2014fromAirMarketsProgramData

24U.S.EnergyInformationAdministrationreporting,http://www.eia.gov/todayinenergy/detail.cfm?id=1549125AirMarketsProgramData,http://ampd.epa.gov/ampd/26CoalAge,http://www.coalage.com/news/latest/4152‐green‐river‐coal‐plant‐will‐remain‐in‐operation‐until‐april‐2016.html#.VckdfflVhBc


3.9. BUILDING INFLUENCES

TheU.S.EPA’sBuildingProfileInputProgram(BPIP)withPlumeRiseModelEnhancements(PRIME)(version04274),willbeusedtoaccountforbuildingdownwashinfluencesontheUnit1mainstack.Thepurposeofabuildingdownwashanalysisistodetermineiftheplumedischargedfromastackwillbeinfluencedbytheturbulentwakeofanyonsitebuildingsorotherstructures,resultingindownwashoftheplume.Thedownwashoftheplumecanresultinelevatedground‐levelconcentrationsinthenearwakeofabuildingandisrequiredforconsiderationinthemodeling.For“other”sourcesthataremodeledinthearea,downwashwillnotbeconsidered.

3.10. SOURCE CONTRIBUTIONS

AnumberofoutputoptionsareavailableinAERMODtotabulateanddisplaytheconcentrationestimatesmade.TheoutputsthatwereofbestusewereMAXDCONTandthesummaryofmaximum4th‐highestmaximumdaily1‐hourconcentrationsaveragedoverthethreeperiod.Beyondjustthemaximumvalues,theuseofMAXDCONTallowsthemodeltogenerateoutputthatprovidesthemaximum4th‐highestmaximumdaily1‐hourconcentrationsaveragedoverthethreeperiodforeveryreceptor(orforthoseaboveauserestablishedthresholdvalue)andindicatesboththecumulativeconcentrationsaswellasindividualcontributionsfromeachuser‐specifiedgrouporindividualsource.TheoutputfromthiscomputationisintheformatandoverthetimeperiodthatiscommensuratewiththeformoftheNAAQS.Section4ofthisreportwillutilizetheseoutputoptions.

3.11. BACKGROUND CONCENTRATIONS

AsdescribedinSection8ofthemodelingTAD,theinclusionofbackgroundambientmonitoredconcentrationsaspartofthemodeledconcentrationsisimportantindetermininganddecipheringthecumulativeambientairimpacts.TheTADdiscussesafirsttierapproachbasedontheoverallhighesthourlymonitoredSO2concentrationandgoesontonotethatthisisaveryconservativemethodtoestablishthebackgroundconcentration.Asecond,lessconservativemethod,isrecommendedwherebythemonitoreddesignvaluesforthelatestthreeyearperiodisused.Forarelativelyisolatedsource,likeWilson,themodelingTADproposesusingaregionalmonitoringsitethatislocatedawayfromtheWilsonareabutisimpactedbysimilarnaturalanddistantanthropogenicsources.Thisregionalsourceshouldberepresentativeofallsourcesimpactinganareaandshouldnotdouble‐countsourceimpactsinthemodelingandmonitoring.Theotheralternativefordeterminingtheappropriatebackgroundconcentrationsistheuseofthe3‐yearaveragesofthe99thpercentilesbyseasonandhourofdayorthe3‐yearaveragesbyhourofday(acrossallseasons).AswithmanylocationsinKentucky,anearbymonitordoesnotexistandaregionalsitewasdeterminedtobethebestchoiceforcharacterizingbackgroundconcentrations.InthepreviouslypresentedFigure3‐2,fourSO2monitorsweredeterminedtobewithin100kmoftheWilsonStation,namely:

1. 18‐163‐0021,Evansville‐BuenaVista,75kmnorthwestofWilson2. 21‐101‐0014,BaskettFireHouse,55kmnorthwestofWilson3. 21‐059‐0005,OwensboroPrimary,35kmnorthofWilson4. 21‐061‐0501,MammothCaveNationalPark,95kmeastsoutheastofWilson

Considerationofeachmonitorasanappropriatebackgroundmonitorwillconsidera)thedistancefromWilsonStationtothemonitor,2)thelanduseinthesurroundingareaascomparedbetweenWilsonStationandthemonitor,3)thelikelihoodofinfluencingnearbylocalpopulation‐relatedsources(vehicles,residentialheating,etc.),4)abilityofthemonitortocapturetheimpactsofsourcesdistantfromtheWilsonStationthatmaynot


explicitlybemodeledbecauseofthedistancebetweenthemandWilsonStationandtheapparentlackofoverlappingsignificantconcentrationgradients,and5)comparisonofpersistentwinddirectionswithlikelydownwindimpactareasforregionalsourceinfluencesonthecandidatemonitors.TheMammothCaveNPmonitor(21‐061‐0501)sitehadthelowestSO2concentrationsduetoitslocationandmonitoringobjective,i.e.,“General/Background”.ThismonitorwastheonelocatedfarthestfromWilsonStationatabout95kmtotheeastsoutheast.Duetoitsbackgroundstatus,thismonitorwasthoughttonotberepresentativeofthesmalltownsandruralcommunitythatinfluencetheairqualityaroundWilsonStation.Alsothismonitor,giventhewindpatternsinthearea(asshownbytheEvansvilleAirportwindroseinFigure3‐6)willnotreflectanycontributionsfromsourceslocatednorthandnorthwestofWilsonStation.Therefore,thissitewasnotchosentorepresentthebackgroundconcentrationsfortheWilsonStationmodelinganalysis.TheEvansville‐BuenaVistamonitor(SiteNo.18‐163‐0021)siteislocatedasa“Neighborhood”sitejusttothenorthofdowntownEvansville.Thismonitorisapproximately75kmtothenorthwestoftheWilsonStation.ThesurroundinglanduseandlocationbeinginsuchanurbansituationaswellasitsdistancefromtheWilsonStationdonotmakeitasuitablemonitorforbackgroundconcentrationsfortheDRRanalysis.Therefore,thissitewasnotchosentorepresentthebackgroundconcentrationsfortheWilsonStationmodelinganalysis.TheOwensboroPrimarymonitor(SiteNo.21‐059‐0005)siteislocatedasa“Neighborhood”sitejustnortheastofthecityofOwensboro.OfthecandidatemonitorsthisoneistheclosesttotheWilsonStationatabout35kmtothenorth.ThesurroundinglanduseandlocationareresidentialandjustoutsideanddownwindoftheurbancoreofOwensboroinalessdenselypopulatedareabutlikelyinfluencedbythemoredenseurbanpopulation‐relatedsources.Themonitorislocatedonly2kmfromtheOwensboroMunicipalElmerSmithStationlocatedupriver.ThepotentialinfluenceofthisstationwhenwindsarefromthenortheastwindfetchandbytheCityofOwensboroforallsouththroughwestwindfetcheslikelyoverwhelmanygeneralregionalSO2impactsandmakethisanunlikelycandidateforusingasthebackgroundfortheWilsonStationmodelinganalysis.Therefore,thissitewasnotchosentorepresentthebackgroundconcentrationsfortheWilsonStationmodelinganalysis.TheBaskettFireHousemonitor(SiteNo.21‐101‐0014)siteislocatedasageneral“PopulationExposure”siteabout8‐9kmsoutheastofEvansville,Indiana.Thiscandidatemonitorislocatedabout55kmtothenorthwestoftheWilsonStation.ThesurroundinglanduseandlocationareverylightdensityresidentialsurroundedbyruralagriculturalandwoodlandareassimilartoWilsonStation.AllsourcesnotedtothenorthwestofWilsonStationatthe40‐50kmrangeincludingCenturyAluminum,BRECLandfill,andGreenStationarelocatedwithrespecttothemonitorandwithrespecttotheprevailingwinds(seeFigure3‐6)thattheirregionalimpactsarelikelycapturedbytheBaskettmonitor.AlsoduetoitsproximitytotheBaskettmonitorandgiventhedownwinddirectionforcertainmeteorologicalevents,theElmerSmithStationwasassumedtoalsoaffecttheBaskettmonitorataregionalscale.Onthesebases,therefore,thissitewaschosentorepresentthebackgroundconcentrationsfortheWilsonStationmodelinganalysis.Ofthemethodsdescribedaboveforthedeterminationofthebackgroundconcentrations,themethodchosenwastheuseofthe3‐yearaveragesofthe99thpercentilesbyhourofday(acrossallseasons).Thisselectionwasbasedonthereviewofthe99thpercentilehourlyvaluesacross2012‐2014whichshowsadiurnalvariationoflowestSO2concentrationsatnightandhighestintheday.Figure3‐7showsthedailydistributionofhourly99thpercentileconcentrationsacrossallthreeyearsofdata.


Figure3‐7.99thPercentileSO2AveragesbyHourofDayforBaskettMonitor(21‐101‐0014)

3.12. MODELING FILES

AllmodelingfileswillbeprovidedtoKDAQinelectronicformatonacompactdisk.Modelandprocessorinput,output,anddatafileswillbeprovided.Spreadsheetstabulatingsource,emission,andotherinputdatasetswillalsobeprovided.AppendixAprovidesalistingofthesourcesincludedforKDAQconsideration.


4. 1-HOUR SO2 DESIGNATION MODELING RESULTS

DispersionmodelingoftheWilsonStationwasconductedusingtheAERMODModel(Version15181).IncludedinthismodelingwastheWilsonStationat0.85lbSO2/MMBtu,TVAUnit3usingtheAirMarketsCEMSSO2data,andbackgroundconcentrations(withtheassumptionthatitwascharacteristicoftheregionalimpactsfrommoredistantlargeSO2sourcesaswellasgeneralruralandnaturalbackgroundsources.Table4‐1presentstheoverallresultsofthemodelingforallsourcesandacontributiondistributionforeachsource(s)andbackgroundtothe3‐yearaverageofthe99thpercentileoftheannualdistributionofdailymaximum1‐hrconcentrations,whichistheformofthe1‐hourSO2NAAQS.AscanbeseenfromTable4‐1,theconcentrationsarealllessthantheNAAQSandthus,theareacanbesaidtobeachievingthestandardsandbedesignatedasattainment.Tofurthershowthis,Table4‐1notonlygivestheoverallmaximumconcentrationbutalsopresentsthehighestranked10highest4thhighconcentrations,allatdifferentreceptorswhichfurtherdemonstratescomplianceacrossabroaderareathanatthemaximumreceptor.

Figure4‐1showsthedistributionof1‐hourSO2concentrationsacrossthenearmodelingdomainasafurthergraphicalpresentationoftheairconcentrationsestimatesandtheirdistribution.

Table4‐1.Highest4thHighModeled1‐hourSO2ResultsforComparisontotheNAAQS

AllSources1

(µg/m3)

AllSourcePercentof1‐hourSO2

NAAQS2

(µg/m3)

WilsonStationContribution

(µg/m3)

TVAUnit3Contribution

(µg/m3)

Background

Contribution1

(µg/m3)

UTMEasting(m)

UTMNorthing(m)

Elevation(m)

186.5 95.2% 146.4 0.1 40.0 490,583 4,144,568 115.8186.2 95.0% 144.0 0.1 42.1 489,983 4,144,468 116.8185.9 94.8% 153.7 0.3 31.9 490,483 4,144,568 116.0185.8 94.8% 155.1 0.3 30.5 490,483 4,144,468 115.9185.4 94.6% 146.5 0.3 38.6 490,783 4,144,368 116.4184.9 94.3% 144.8 0.1 40.0 490,083 4,144,468 118.4184.8 94.3% 146.9 0.4 37.4 491,083 4,144,468 116.6184.4 94.1% 146.5 0.4 37.4 491,183 4,144,468 117.4184.3 94.1% 146.8 0.1 37.4 489,133 4,144,518 125.6184.3 94.0% 146.5 0.4 37.4 490,683 4,144,368 117.0

1Modeledconcentrationsincludeanhourlybackgroundconcentrationdeterminedbytakingthe3‐yearaverageofthe99thpercentileoftheannualdistributionofdailymaximum1‐hrconcentrationsattheBaskettFireDepartmentSO2MonitornorthwestofWilsonStation.2BasedonthePrimaryNationalAmbientAirQualityStandard(NAAQS)forSO2fortheaveragingperiodof1‐hr,75ppb(196µg/m

3).


Figure4‐1.SpatialDisplayof3‐yearAverage99thPercentileAnnualDistributionofDailyMaximum1‐hrSO2Concentrations

AIR DISPERSION MODELING REPORT WILSON … DISPERSION MODELING REPORT WILSON STATION SO2 DESIGNATION...

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