INDIANADEPARTMENTOFENVIRONMENTALMANAGEMENTWeProtectHoosiersandOurEnvironment.100N.SenateAvenue•Indianapolis,IN46204(800)451-6027•(317)232-8603•www.idem.IN.govMichaelR.PenceGovenw1·Ms.SusanHedmanRegionalAdministratorU.S.EnvironmentalProtectionAgencyRegion577WestJacksonBoulevardChicago,IL60604-3950DearMs.Hedman:September16,2015CarolS.ComerCon1missimJe1·Re:PreliminaryRecommendationsConcerningRound2AirQualityDesignationsforthe2010Primary1-HourSulfurDioxideNationalAmbientAirQualityStandardThisletterisinresponsetotheUnitedStatesEnvironmentalProtectionAgency's(U.S.EPA's)March20,2015updatedguidanceconcerningairqualitydesignationsforthe2010primary1-hoursulfurdioxide(S02)NationalAmbientAirQualityStandard(NAAQS).OnMarch2,2015,theU.S.DistrictCourtfortheNorthernDistrictofCaliforniaacceptedanenforceableorderagreement(ConsentDecree)betweenU.S.EPA,theSierraClub,andtheNaturalResourcesDefenseCounciltoresolvelitigationconcerningdeadlinesforcompleting1-hourS02NAAQSairqualitydesignationsfortheremainderofthecountry.U.S.EPAmustcompleteremainingdesignationsinthreeadditionalrounds:Round2byJuly2,2016,Round3byDecember31,2017,andRound4byDecember31,2020.U.S.EPAwillcompletethesedesignationsbydesignatingareasaseithernonattainment,attainment,orunclassifiable.ThecourtorderdirectsU.S.EPAtodesignatetwogroupsofareasunderRound2airqualitydesignationsforthe2010primary1-hourS02NAAQS:(1)areasthathavecurrentmonitoreddesignvaluesinviolationoftheNAAQSthatwerenotpreviouslydesignatedduringRound1designationsand(2)areasthatcontainanystationarysource(s)that,accordingtoU.S.EPA'sAirQualityMarketsDatabaseeitheremittedmorethan16,000tonsofS02in2012oremittedmorethan2,600tonsofS02andhadanannualaverageemissionrateofatleast0.45lbsS02/MMBtu(poundsperonemillionBritishthermalunits)in2012andthathasnotbeenannounced(asofMarch2,2015)forretirement.AnEqualOpportunityEmployer0(i)RecycledPaperAStateMs.SusanHedmanPage2of3U.S.EPAidentifiedthefollowingfivecoal-firedelectricpowerplantsinIndianaasmeetingRound2criteriaestablishedintheConsentDecree:CountyFacilityName20128022012802EmissionsEmissions(tons)Rate(lbs/MMBtu)SpencerRockport54,3900.583GeneratingStationJeffersonCliftyCreek52,8391.767GeneratingStationGibsonGibson22,4470.249GeneratingStationLaPorteMichiganCity11,5841.006GeneratingStationPoseyA.B.Brown7,0910.521GeneratingStationU.S.EPAisprovidingstatestheopportunitytosubmitupdatedrecommendationsandsupportinginformationforconsiderationfortheaffectedareas.TheguidanceindicatesU.S.EPA'sintentiontoproposestatedesignationsonoraboutFebruary3,2016,andfinalizethembyJuly2,2016.Assuch,theguidancerequeststhatstatessubmittheirrecommendationsforareadesignationsbySeptember18,2015.EnclosedyouwillfindIndiana'sassessmenttosupportfinalboundarydeterminationsforRound2designationsforthe2010primary1-hourS02NAAQS(Enclosure3).Indianahasalsoenclosedquality-assuredambientairqualitymonitoringdatafrom2012-2014forIndiana'sSOzmonitoringnetwork(Enclosure2).Basedonthisdata,therearenonewareasinthestatethatmonitoredconcentrationsabovethestandardinadditiontothoseidentifiedinRound1airqualitydesignations.Thefollowingenclosuresareincludedwiththisletter:•Enclosure1Indiana'sPreliminaryDesignationRecommendationsConcerningRound2AirQualityDesignationRecommendationsforthe2010Primary1-HourSOz.Standard•Enclosure2Indiana's2012-2014SOzMonitoringDataSummaryComparedtothe1-HourStandard•Enclosure3Indiana'sAssessmentofRound2AirQualityDesignationsforthe2010Primary1-HourS02StandardIndianaisrecommendingthatU.S.EPAusecountyboundariesforthepurposesofprovidingaclearlydefinedlegalboundaryforcarryingouttheairqualityplanningandenforcementfunctionsforthearea.Ms.SusanHedmanPage3of3Basedontheresultsofthisevaluation,IndianaisrecommendingGibson,Jefferson,LaPorte,Posey,andSpencercountiesbedesignatedasattainmentunderthe20101-hourprimaryS02standard.ThisrecommendationisbasedonthefactthatIndiana'sassessment,performedinaccordancewithU.S.EPA's"UpdatedGuidanceforAreaDesignationsforthe2010PrimarySulfurDioxideNationalAmbientAirQualityStandards"datedMarch20,2015anddraftS02NAAQSDesignationsModelingTechnicalAssistanceDocumentguidancedatedDecember2013,clearlydemonstratesthatthesefacilities,basedon2012-2014quality-assuredambientairqualitymonitoringdataandambientairqualitymodeling,arenotlocatedinanareacurrentlyviolatingtheNAAQSorarecausingorcontributingtoamonitoredviolationofthestandard.AnelectronicversionofthisrequestinPDFformat,aswellasadiskcontaininginputandoutputfilesusedtoconductappropriateairdispersionmodelinganalysestosupportIndiana'sassessmenthavebeensenttoRandyRobinsonandJohnSummerhaysofU.S.EPARegion5.Indianareservestherighttosupplementand/orrevisetherecommendationscontainedhereinasadditionalmonitoringand/ormodelinginformationbecomesavailable.IwouldliketothankyouforthisopportunitytoprovidefeedbacktoU.S.EPAregardingRound2airqualitydesignationsforthe2010primary1-hourS02NAAQS.WelookforwardtoworkingwithyourstaffasU.S.EPAmovesforwardwiththedesignationsprocess.IfyouhaveanyquestionsregardingIndiana'sdesignationrecommendations,pleasefeelfreetocontactmeat(317)232-8611orbyemailatccomer@idem.IN.govorKeithBaugues,AssistantCommissioner,OfficeofAirQuality,at(317)232-8222orbye-mailatkbaugues@idem.IN.gov.CSC/kb/sd/bc/gfAttachments:Commissionercc:GeorgeCzerniak,U.S.EPARegion5(noenclosure)ChrisPanos,U.S.EPARegion5(noenclosure)RandyRobinson,U.S.EPARegion5(noenclosure)JohnSummerhays,U.S.EPARegion5(noenclosure)DougAburano,U.S.EPARegion5(noenclosure)KeithBaugues,IDEM-OAQ(noenclosure)ScottDeloney,IDEM-OAQ(noenclosure)BrianCallahan,IDEM-OAQ(w/enclosure)MarkDerf,IDEM-OAQ(w/enclosure)GaleFerris,IDEM-OAQ(w/enclosure)FileCopyEnclosure1Indiana'sPreliminaryDesignationRecommendationsConcerningRound2AirQualityDesignationsforthe2010Primary1-HourSulfurDioxideNationalAmbientAirQualityStandardCountyRecommendationGibsonAttainmentJeffersonAttainmentLaPorteAttainmentPoseyAttainmentSpencerAttainmentPageIofIEnclosure2IndianaSulfurDioxide(S02)2012-2014MonitoringDataSummaryComparedtothe1-HourStandard2012-2014MonitorDesignCountySiteID201220132014ValueBartholomew18-005-000716.2*17.417**Daviess18-027-000278150107112Floyd18-043-000438306544Floyd18-043-10043220.543.832Fountain18-045-000130342229Gibson18-051-000276647772Wabash,IL17-185-000189555366JaSQer18-073-000233402533Lake18-089-00224743.253.148Lake18-089-20082823.720.224LaPorte18-091-00052115*1517**Marion18-097-005791.578.1105.692Marion18-097-00735642.359.153Marion18-097-007861.17080*70**Morgan18-109-100182649079Pike18-125-0005140.2169.4156.7155Porter18-127-001136362733Vanderburgh18-163-002116.518.632.322Vigo18-167-001872.579.18579llVigo18-167-1014128103120117Wayne18-177-000622.414.3715Whitley18-183-00035.813.310***Notacompleteyearofdata**LessthanthreeyearsofdataDesignValuegreaterthanorequalto76ppburIllinoisMonitorPageIof4

# Indiana S0 2 

# 2008

- 2014 Monitoring Data Summary Compared to the 1

- Hour Standard

:-.rote: U.S. EPA es t ab l ished a new !-h o ur primary S02 standard o n June 2. 2010. The new !

- hou r standard is 75 parts per billion (ppb). Attain m ent is determined b y evaluating th e th r ee

- year average of the 99 'h percentile

va l ues of the daily ma'<i m um ! -h our average at each monitor within an area, which mu st not exceed 75 ppb

. Any three

- year design value over the !

- hour standa rd has been h igh li ghted in ye llow

. Data pr io r to 2010 were

compared to the annua l and 24-hour 

# sol standards.

99'b Pe r centile Va lu es (ppb) Three

- Year Design Value (ppb)

County Site ID 

# I I I 20 08 2009 2010 2011 2012 2013 2 014 08

- 10 09

- ll 10-12 11-13 12-14

Bartholomew 18-005

- 0007 Monitor began operatio n on 05 / 02/20 1 3

. 16.2 1 7.4 Operation began o per ation on 16 17 05 / 0212013.

Dav ies s 18-027-0002 1 22 1 38 1 1 5 100 78 !50 107 125 118 98 109 112

Floyd 18-043-0004 117 87 72 36 38 30 65 

# 92 65 49 35 44

Floyd 18-043-1004 138 125 123 38 32 20.5 43.8 129 95 64 30 32

Fountain 18-045

- 000 I 236 38 26 29 30 34 22 100 31 28 31 29

Gibson 1 8

- 05 1-0 002 90 65 74 68 76 64 77 76 69 73 69 72



# Wabash. IL 

# 17-185-0001 90 69 66 47 89 55 53 75 61 67 64 66

Jaspe r 18-0 7 3-000 2 61 88 39 32 33 40 25 63 53 35 35 33

Lake 18-089

- 0022 67 59 57.2 58 47 43

. 2 53.1 61 58 54 49 48

Lake 18-089-2008 37 37 34.3 40 28 23.7 20.2 36 37 34 31 24

LaPorte 18-091-0005 29 23 30 19 21 15 15 27 24 23 18 1 7

Marion 18

- 097-0057 79 75 103.4 63 91.5 78.1 105

. 6 86 80 86 78 

# 92

Marion 18

- 097-0073 29 61 47.7 59

. 5 56 42.3 59

. 1 46 56 54 53 53

Marion 18-097- 0078 Monitor began o peration in 20 59.7 61.1 70 80 20 40 47 64 70

2010.

Morgan 18-1 09

- 1001 91 98 105 96 82 64 90 98 100 9-4



# ! 79

Pi k e 18- 125

- 0005 205 194 21 1 1 19 140

. 2 169.4 156

. 7 203 175 157 1 -43 15 5

Porter 1 8

- 127-0011 82 51 62 44 

# 36 36 27 65 52 47 39 33

Vanderburgh 18-163-0012/21 41 17 18 .8 19.4 16.5 18. 6 32.3 26 18 18 18 22

Vi go 18- 167

- 0018 120 115 61.4 95.2 72.5 79.1 85 99 91 7 6 82 7 9

Vi go 18

- 167

- 1014 137 142 1 69 139 128 103 120 149 150 145 123 117

Wayne 18-177-0006 109 70 95.2 79.1 22.4 14.3 7 9 1 1 

# 8 1 66 39 15

Whi t ley 18-18 3

- 0003 Monitor began ope r ation i n 2013. 5.8 13.3 Monitor b egan operation in 2013. 6 10

One Year of Data Two Years of Data Incomplete Data 

# lllin ois Monitor Design Yalue greater than or equal to 76 ppb



# Page 2 of 4Source-Oriented10#18-127-0011Source-Oriented10#18-073-0002Source-Oriented10#18-045-0001TerreHauteLafayetteAve.10#18-167-0018Source-OrientedI0#18-027-0002Source-Oriented10#17-185-0001Evansville-BuenaVista10#18-163-0021Note:MonitorSiteIdentificationNumbersUsedbyU.S.EPA'sNrQualitySystemDatabaseOate:OS/11/2015Mappedby:L.Fergusoo,OAQSourcu:OffioeofAirQualityMapProjection:UTMZone16 NMapDatum:NAD832014S02MonitoringNetworl{LaGrangeSteubenElkhartN-:>bleDeKalbMarsh•llLarwillI0#18-183-0003All!nPula!kiWabash¢8'"'"'W!llsAdamsHowardGr!ntOintonTiptonllontgomeryBooneHamilton0IIndiana-OperatedS02Monitor00Source-OperatedS02MonitorPage3of4lndpls-WashingtonParkI0#18-097-0078lndpls-E.16thStI0#18-097-0073Source-Oriented10#18-177-0006Source-Oriented10#18-109-1001Hope10#18-005-0007Source-Oriented10#18-043-0004NewAlbanyI0#18-043-10042550miI2550kmNwsS021-HourDesignValues2012-2014andRound1S02NonattainmentAreasHammond·141stSt.24ID#18-045-000129ID#18-167-1014117TerreHaute·LafayetteAve.79ID#18-027-0002112ID#18-125-0005155ID#17-185-000166Evansville·BuenaVista22Note:1-HourDesignValuesfor2012-2014inpartsperbillion(ppb)Dale:OS/1012015Mappedby:L.FErguson.OAOSources:Offia:ofAirQualityMapProjection:UTMZone1tlNMapDatum:NAOS3BentonWerrenDD•+LaGrang<=SteubenB.hartNobleDEI<albMsnhsllAllenPulaskiWabash,_o<:-Miami;...f!lWells.odanuHcwerdGrantJfr.jlippEOSnoeClintonliptonDel"'vareMontgomeryBooneHamiltonDaviessPikeVlgoNonattainmentArea0IID#18-177-000615lndpls·HardingSt.92ID#18-043-0004442550miIAttainment/Unclassifiable02550kmS02Monitorlessthanorequalto75ppbS02Monitorgreaterthan75ppbPage4of4Enclosure3Indiana'sAssessmentofRound2AirQualityDesignationsforthe2010Primary1-HourSulfurDioxide(S02)StandardBacl{groundOnJune2,2010,theUnitedStatesEnvironmentalProtectionAgency(U.S.EPA)revisedtheprimaryNationalAmbientAirQualityStandard(NAAQS)forsulfurdioxide(S02)[75FR35520].U.S.EPArevokedboththeprevious24-hourandannualprimaryS02standardsandestablishedanew1-hourso2standardatalevelof7 5pmisperbillion(ppb),basedonthetlu-eeyearaverageofthemmual99111percentileofthe1-hour dailymaximumconcentrations.OnAugust5,2013,U.S.EPApublishedanoticeannouncingdesignationsoftwenty-nine(29)areasinsixteen(16)statesasnonattainmentforthe2010primary1-hourS02NAAQS,basedoncertifiedambientairqualitymonitoringdatafortheyears2009-2011thatshowedtheseareaswereviolatingthestandard(78FR47191).1IntheStateoflndiana,fourareascomprisedofninetownshipsinfivecountiesweredesignatednonattainment.However,atthattimeU.S.EPAwasnotyetpreparedtoissuedesignationsfortheremainingareas.OnMarch2,2015,theU.S.DistrictCourtfortheNorthernDistrictofCaliforniaaccepted,asanenforceableorder,anagreementbetweenU.S.EPA,theSierraClub,andtheNaturalResourcesDefenseCounciltoresolvelitigationconcerningthedeadlineforcompletingairqualitydesignationsfortheremainderofthecountry?Thecourt'sorderdirectsU.S.EPAtocompleteremainingdesignationsinthreeadditionalrounds:Round2byJuly2,2016,Round3byDecember31,2017,andRound4byDecember31,2020.U.S.EPAwillcompletethesedesignationsbydesignatingareasaseithernonattainment,attainment,orunclassifiable.ThecourtorderdirectsU.S.EPAtodesignatetwogroupsofareasunderRound2oftheairqualitydesignations:(1)areasthathavenewlymonitoredviolationsofthe2010primaryS02NAAQSthatwerenotpreviouslydesignatedduringRound1designationsand(2)areasthatcontainanystationarysource(s)that,accordingtoU.S.EPA'sAirQualityMarketsDatabase,eitheremittedmorethan16,000tonsofso2in2012oremittedmorethan2,600tonsofso2,hadanannualaverageemissionrateofatleast0.45lbsS02/MMBtu(poundsperonemillionBritishthermalunits)in2012,andthathasnotbeenannounced(asofMarch2,2015)forretirement.1http://www.gpo.gov/fdsys/pkg/FR-2013-08-05/pdf/2013-18835.pdf2http://www.epa.gov/airquality/sulfurdioxide/designations/pdfs/201503FinaiCourtOrder.pdfPage1of34

# In response

to the court's

order,

on March 20,2015,

U.S.

EPA identified

five coal-fired

power plants

in Indiana,

as listed

in Table

1,

as meeting

Round

2 criteria established

in the court's order. County Spencer Jefferson Gibson LaPmte Posey

Table

1: Indiana

S0

2 

# Sources Identified

by U.S.

El'

A

as Meeting Round

2 Air Quality Designation

Criteria Facility

Name

2012

S0

2 

# Emissions

2012

S0

2 

# Emission

Rate (tons)

(lbs/MMBtu) Rockport

54,390

0.583 Generating

Station Clifty

Creek

52,839

1.767 Generating

Station Gibson

22,447

0.249 Generating

Station Michigan

City

11,584

1.006 Generating

Station A.B. Brown

7,091

0.521 Generating

Station The March

2, 2015,

comt

order directs

U.S.

EPA

to complete

the second

round

of area designations

by July

2, 2016.

States

may submit updated recommendations

and supporting information

to U.S.

EPA

for consideration

for

the affected

areas

by

no later

than September

18, 2015. U.S. EPA's

final

area designations

are expected

to

be based

on 2012-2014

ambient

air quality monitoring

data reported

from

S0

2 

# monitors

currently

in place,

as well

as refined modeling states choose

to conduct specifically

for area designations.

U.S.

EPA expects

to designate

areas in the following

mmmer: • Nonattainment:

An area

that

U.S.

EPA

has determined

violates

the 2010 primary!- hour

S0

2 

# NAAQS,

based

on

the most recent

three

years

of ambient

air quality monitoring data

or

an appropriate

modeling

analysis,

or that

U.S.

EPA

has determined

contributes

to a violation

in

a nearby

area. • Attainment:

An area

that

U.S.

EPA

has determined

meets

the 2010 primary

!-hour

S02 NAAQS

and does

not contribute

to

a violation

of the NAAQS

in

a nearby

area based

on either:

a) the most recent

tiu·ee

(3) years

of ambient

air quality monitoring

data

from

a Page

2 of34monitoringnetworkinanareathatissufficienttobecomparedtotheNAAQSperU.S.EPAinterpretationsintheMonitoringTechnicalAssistanceDocument(TAD),3orb)anappropriatemodelinganalysis.•Unclassifiable:AnareawhereU.S.EPAcannotdeterminebasedonavailableinformationwhethertheareaisorisnotmeetingthe2010primary1-hourS02NAAQSandwhethertheareacontributestoaviolationinanearbyarea.Indiana'sAssessmentConsistentwithU.S.EPA'sMarch20,2015,guidancememorandumtitled"UpdatedGuidanceforAreaDesignationsforthe2010PrimarySulfurDioxideNationalAmbientAirQualityStandard,"4theIndianaDepartmentofEnvironmentalManagement(IDEM)hasconductedathoroughreviewoftheaffectedareasinIndiana.IDEM'sreviewfocusedonthefollowinganalysiscriteriaoutlinedintheguidance:•Ambientairqualitydataordispersionmodelingr·esults:Indiana'sevaluationisbasedon2012-2014monitoringdataandairdispersionmodelingresults.Theairqualityanalysisevaluatedthethree-yearaverageofthe99111percentileoftheyearlydistributionof1-hourdailymaximumS02concentrations.AmbientairqualitymonitoringdatawasretrievedfromU.S.EPA'sAirQualitySystem(AQS)andrefineddispersionmodelingwasperformedusingtheAmericanMeteorologicalSociety/EnvirorunentalProtectionAgencyRegulatoryModel(AERMOD)version15181toassessairqualityinaparticularlocation.U.S.EPARegionVreviewedIDEM'smodelingprotocolandprovidedcommentswhichwereaddressed.Modelingresultswereconductedusing4111highmaximumdaily1-hourvaluesaveragedoverthetlu·ee-yearmodeledperiodcombinedwithrepresentativetemporallyvaryingseasonalS02backgroundconcentrationstoindicatewhethertheareaviolatedthestandardorcontributedtoaviolationinanearbyarea.Modelingwasperformedtoshowthattheexistingmonitor(s)areproperlysitedtoassessairqualityinthearea.•Emissions-relateddata:IndianaexamineddetailedemissionsinformationfromtheCliftyCreekGeneratingStation(JeffersonCotmty),A.B.BrownGeneratingStation(PoseyCounty),MichiganCityGeneratingStation(LaPmteCounty),andRockportGeneratingStation(SpencerCounty)andallothersignificantsourcesofS02emissionslocatedinnearbyareas.Significantemissionlevelsinnearbyareasindicatepotentialfortheareatocontributetoobservedormodeledviolationsofthestandard.Tables3http://www.epa.gov/airquality/sulfurdioxide/pdfs/S02ModelingTAD.pdf4http://www.epa.gov/airquality/suIfurdioxide/pdfs/20150320S02designations.pdfPage3of34identifiedinthisanalysisshowallstationarysourceswithrepmiedS02emissionsintonsperyear(tpy)atthefacilitylevel.•Meteorology(weatherandtransportpatterns):Indianaperformedsource-orienteddispersionmodelingtoevaluatemeteorologicaldatatohelpdeterminehowweatherconditions,includingwindspeedanddirection,affecttheplumeofsources contributingtoambientS02concentrations.•Geography/topography:Thegeographyandtopographyanalysisconsideredphysicalfeaturesandlandusethatmighthaveaneffectontheairshedandtherefore,thedistributionofpollutantsoveranarea.IndianadoesnothaveanysignificanttopographicfeaturesthatinfluencethedistributionofSOzconcentrationswithinthestate.•Jurisdictionalboundaries:IndianaisrecommendingthatU.S.EPAusecountyboundariesforthepurposeofprovidingaclearlydefinedlegalboundaryforcarryingouttheairqualityplmmingandenforcementfunctionsforthearea.Indianahasdevelopedthefollowingevaluationfordeterminingm·eadesignationsandappropriateareaboundariesforthe2010!-hourprimaryS02standard.Indianareliedon2012-2014site-specificmonitoringdataindeterminingwhethertheGibsonGeneratingStationislocatedinanareathatviolatesorcontributestoaviolationofthe!-hourS02NAAQSinanearbyarea.IndianareliedonAERMODairdispersionmodelingoftheCliftyCreekGeneratingStation,A.B.BrownGeneratingStation,MichiganCityGeneratingStation,andRockportGeneratingStationforareaattainmentdesignationrecommendationsastherearenosite-specificmonitorsassociatedwiththesefacilities.Basedontheresultsofthisevaluation,IndianarecommendsthatGibson,Jefferson,LaPorte,Posey,andSpencercountiesbedesignatedasattainmentunderthe20I0!-hourprimarySOzstandard.ThisrecommendationisbasedonthefactthatIndiana'sassessment,performedinaccordancewithU.S.EPA'supdatedguidance,clearlydemonstratesthatthesefacilities,basedon2012-2014quality-assuredmonitoringdataandambientairqualitymodeling,arenotlocatedinanareacurrentlyviolatingtheNAAQSorarecausingorcontributingtoaviolationinanearbyarea.MethodologyfortheAh·QualityModelingandMeteorologyInputsU.S.EPAprovidedguidanceinordertoconductappropriateairdispersionmodelinganalysestosupport!-hourS02designationrecommendations.U.S.EPA'sS02NAAQSDesignationsModelingTADguidancehasseveralrecommendationsformodelingmethodologyfordeterminingattainmentdesignationsincluding:Page4of34I)Useofactualemissionstoassessmodeledconcentrationstoreflectcurrentairquality.2)Useof3yearsofmodelingresultstocalculateasimulated!-hourS02designvalueconsistentwiththe3-yearmonitoringperiod.3)Placementofreceptorsonlyinlocationswhereanairqualitymonitorcouldbeplaced.4)Useofactualstackheights ratherthanfollowingtheGoodEngineeringPractice(GEP)stackheightpolicywhenmodelingactualemissions.IndianafollowedU.S.EPA'srecommendationstoconduct!-hourS02designationmodelinginordertomeettherequirementsoftheConsentDecreetodeterminewhethertherearemodeledviolationsofthe!-hourSOzNAAQS.Modelingresultslookatthe41hhighmaximumdaily1-hourconcentrationaveragedoverthe3-yearmodeledperiodcombinedwith representativetemporallyvaryingseasonalS02backgroundconcentrationstodeterminetheattai11111entstatusoftheareawheretheConsentDecreeemissionsourcesreside.ModelSelectionInaccordancewithAppendixAofAppendixWto40CodeofFederalRegulations(CFR)Part51,IndianausedAERMODversion15181foralldispersionmodelingoftheA.B.BrownGeneratingStation,CliftyCreekGeneratingStation,MichiganCityGeneratingStation,andRockportGeneratingStation,aswellasnearbyareas.Additionally,theregulatorydefaultandruralmodeoptionswereselected.U.S.EPA'sS02NAAQSDesignationsModelingTAD,specifictoattai11111entdesignationmodeling,recommendedusingactualstackheightswhenmodelingactualemissionsinsteadoffollowingtheGEPrequirement.AERMAPTheAERMODterrainpreprocessormappingprogram,AERMAP,wasusedtodeterminealltheelevationterrainheightsforthereceptor,building,andsourcelocationsusingtheUniversalTransverseMercator(UTM)coordinatesystem.ThemostrecentAERMAPversionIll03wasusedtoassigntheelevationsfromtheNationalElevationDataset(NED)usingtheNorthAmericanDatum(NAD)1983asrecommendedin"40CFRPmi51,RevisiontotheGuidelineonAirQualityModels"AppendixWandlaterrevisedinthe"AERMODImplementationGuide."ReceptorGridandModelingDomainThereceptorgridandmodelingdomainwasbasedonU.S.EPA'sMarch20,2015,S02guidanceandS02NAAQSDesignationsModelingTAD.Indianaconductedmodelingwithamultinestedrectangularreceptorgridwithappropriatespacingofreceptorsbasedonthedistancefromthemodeledemissionpointstodetectsignificantconcentrationgradients.IndianahasconductedPage5of34

# exploratory

modeling

on each ofthe Consent

Decree somces. Maximum

modeled

1-hour

S0

2 

# impacts

or source-culpab

l e modeled violations

did

not extend

out beyond

three

km from

each source.

To ensure

all maximum

1-hour

S0

2 

# concentrations

were modeled

, the modeling

g rid was extended

out

to

1 0 km from

each source

. The receptor

spac

in

g and distance

each nested

grid covered

from

the source

is listed below. • Receptor

spac

ing

at the fence

lin

e for each facility

were placed

every

50 meters. • Receptor

spac

in

g at 100

met

e

r

s out

to

a distance

of3

, 000

met

e

r

s (3 km) beyond

eac

h facility (extended

if modeling

result

s warranted)

. • Receptor

spacing

at 250 meters

out

to

a distance

of 5,000

meter

s (5 Ian) beyond

each facility (extended

if modeling

re

su

lts warranted). • Receptor

spacing

at 500

met

e

r

s out

to

a distance

of

10 ,00

0 meters

(1



# 0 km)

b eyond

each facility (extended

if mod

e lin

g re

s ult

s warranted). Ba sed

on

the

S0

2 

# NAAQS

De

s

i gnations

Mode

lin

g TAD Section

4.2

, Indi

a na pla

ce

d modeling receptors

only where

it was feasible

to

pl ace

a monitor.

Indiana matched

up each modelin

g domain

for

the four sources modeled

with Google

Maps projections

to ensure

the proximity

of receptor locations. 

# Modeled

S0

2 

# Emissions Indiana

mod

e

l e d the hourly

cont

inu ous emissions monitoring

(CEM)

data

from

each

sou

rc

e mentioned

in the Consent

D ec

r ee

. A

l ong

w ith

the hourly emission

data,

h

o url

y stack

gas flow rat e a

nd temperature

of the exhaust

s tr ea

m (when available)

were modeled

as the

se parameters tend

to vary.

This variation

can

in fluence

the

di

s per

s

i on characteristics

of the exhaust

stream

and have

an impact

on modeled

1-hour

S0

2 

# concentration(s).

In some

cases federally

e nforceable e mi ssio

n limit

s ant

i c ip ated

to

be

in

pl ace

by the July

2,

2 016

, date

for final



# so2

area

d es

i g n

a tions were modeled

. Documentation

of

a

ll controls

and/or emission

limit

s implemented

at the

so urc

es by

the comp

li

a nce date, contrary

to the

2 01

2

- 20

14 CEMS

data

, are provided

for each

sou

rce

's attainment designation recommendation. Intermittent

Sources Int erm

itt en

t so urce

s,

s uch

as emergency

ge

n

e

r ato

rs

, fire pumps,

and startup

/ shutdown

emissions w ill

b

e

h an

dl

e d cons

i ste

nt with

U.S. EPA's

March

1

, 

# 20

11

, guidance

"Addit

ion

a

l Clar

i ficatio

n Regarding

App

li cation

of Appendix

W Modeling Guidance

for

the 1-hour

N0

2 

# NAAQS."

5 

# Thi

s 5 

# ht

t p:

// www

. epa.gov

/ tt

n

/ scra

m

/ gu

i da

n ce

/ clari ficationl Additiona

l Clarification

s Appendix

W

H

o url

y

- N0

2- NAAOS

FINAL

03-0

l

- 20

l l. pdf



# Page

6 of34guidance

was followed

to assess

the !-hour

S0

2 attainment designations

as well.

U.S.

EPA recommended

using appropriate

data based

on emission

scenarios

that

are continuous

enough

or frequent

enough

to contribute significantly

to the annual distribution

of maximum

daily !-hour concentrations.

Review

of the hours

of operation

for combustion

turbines, emergency generators, startup/shutdown,

fire pumps,

and other auxiliary operations

associated

with

the sources mentioned

in the Consent

Decree

were determined

to operate

much

less

than

500 hours per year

and

on

a random

and infrequent

basis

that cannot

be anticipated.

Exploratory

modeling was conducted

on these intermittent

sources

and results showed

a negligible

impact

from

these auxiliary

or emergency

processes

on

the maximum

modeled

!-hour

S02 receptors

from

the electric generating

units (EGUs).

Indiana believes

the intent

of the Consent

Decree

is

to determine

the attainment

status

of the area su!1'ounding

the EGUs

based

on

the actual emissions coming

from

the EGUs identified

by U.S. EPA; therefore

the EGUs

were Indiana's

main

focus in

its assessment. Treatment

of Inventory

Sources Emission

sources

located

in the vicinity

of the Consent

Decree

sources

were evaluated

to determine

if they could

cause

or contribute

to

a NAAQS

violation

near

the Consent

Decree source.

Based

on U.S. EPA's

March

I, 2011 guidance,

Indiana

focused

on areas within

10 km for each

of the modeled

Consent

Decree sources.

U.S. EPA's

S02 NAAQS Designations Modeling

TAD Section

4.1, page

7 mentions

that

the number

of sources

to

be explicitly

modeled should

cause

a significant concentration

gradient

and

the number

of those sources

to

be modeled would generally

be small. Indiana retrieved

a list

of

all

S0

2 emission

sources

in the county

of the source addressed

by

the Consent

Decree,

as well

as S0

2 emission

sources

in adjacent counties

in Indiana

and Kentucky,

in order

to determine

which sources

should

be included

in the modeling

analyses.

Seven Indiana

sources

and

six Kentucky

sources

were identified

with

S0

2 emissions

of250

tpy

or more located

within

30 km

of one

of the Consent

Decree sources. Actual emissions

taken

from

the year 2013,

the most recently available

year,

were modeled

for all sources. Meteorological

Data As stated

in

40 CFR

Part

51, Appendix

W, section

8.3.1.2

and

the S02 NAAQS Designations Modeling

TAD, Indiana

used

three

years (2012-2014)

ofNational

Weather

Service

(NWS) surface

and upper

air meteorological

data.

The Indianapolis,

Evansville,

and South

Bend

NWS surface

data

and upper

air data taken

from Lincoln,

Illinois

and Wilmington,

Ohio,

were processed

with

the latest version

of the AERMOD meteorological

data preprocessor

program, AERMET

(version

15181),

and used

in the modeling

of the Clifty

Creek Generating

Station, A.B. Brown Generating

Station, Michigan

City Generating

Station, Rockport Generating

Station, and nearby

areas. Meteorological

data,

taken

from

the Gary-Illinois

Institute

of Technology Page

7 of34

# Research

Institute

(IITRI) meteorological

monitoring

station

located

in Lake County

and near

the shores

of Lake Michigan,

was preprocessed

with

the South

Bend

data

to create

a meteorological data

set more representative

oflakeshore

conditions

(i.e.

lake breezes

and other

wind conditions associated

with

Lake Michigan).

The Michigan

City Generating

Station

was modeled

using

the Gary-IITRI meteorological

dataset. AERMINUTE/AERSURF

ACE 

# The NWS meteorological

data

can contain

a number

of calm

wind speeds

greater

than

ten percent

of the 8,760 annual observation

hours.

The !-minute

wind

speed

and wind direction Automated

Surface Observing

System

(ASOS)

data

from

the NWS stations

were processed

with U.S. EPA's !-minute

data processor

program, AERMINUTE

version

14237. U.S EPA's program, AERSURFACE,

was

used

to determine

the surface characteristics:

albedo, Bowen

ratio,

and surface roughness

for

the Indianapolis,

Evansville,

and South

Bend

NWS meteorological

tower locations.

Surface characteristics

were determined

at each NWS location for each

of the

12 wind direction

sectors

with

a recommended

default

radius

of one

km.

The albedo

and Bowen

ratio surface characteristics

were adjusted

during

the three winter months

of January, February,

and December

in accordance

with

U.S.

EPA Region

V's document

"Regional Meteorological

Data Processing

Protocol,"

dated August

2014. Additionally,

a dry

or wet Bowen

ratio value

was used during months

when

soil moisture conditions

were abnormally

dry or wet; otherwise

the Bowen

ratio value

for average

soil moisture conditions

was used.

The surface roughness

value

for snow

cover

was

used

if more

than

half

of the month

had days

with

at least

one

inch

of snow

on

the ground. Otherwise,

the

no snow

cover surface roughness

value was used. 

# Indiana's Recommendations Duke Energy Indiana,

Inc.- Gibson Generating

Station The Gibson Generating Station (Gibson

Station)

is

a coal-fired power plant

consisting

of five units

that have

a capacity

to generate

3,342 megawatts

(MW)

of electricity

combined.

The Gibson

Station

is located

on the bank

of the Wabash

River

in Montgomery

Township,

Gibson County,

Indiana, approximately

1.5 miles southeast

of Mount Carmel,

Illinois

and

7.5 miles northwest

of Owensville,

Indiana.

The plant

is operated

by Duke Energy Indiana,

Inc. (DEI)

and owned

by DEI, Wabash

Valley

Power Association,

Inc.,

and

the Indiana Municipal

Power Agency.

Gibson

Station

is

a stationary

electric

utility generating

station

with

five coal-fired boilers;

two boilers

are rated

at 5,875 MMBtu/hr,

two boilers

are rated

at 5,987 MMBtu/hr,

and

a fifth boiler

is rated

at 5,900 MMBtu/hr.

Page

8 of34DuetoconditionssetforthintheConsentDecreeandsubsequentU.S.EPAguidance,Indianareliedonexistingambientairqualitymonitoringdatafrom2012-2014todeterminetheattainmentdesignationrecommendationfortheGibsonStation.Cunently,therearethreeactivemonitorsmeasuringambientS02concentrationsintheareaasdepictedinFigureI.TheCoalRoadandPumphousemonitorsarelocatedonGibsonStationpropertynortheastandsouthwestofthemainstacks,respectively.TheMt.Carmelmonitorislocatednorth-northwestofthestationinWabashCounty,Illinois.TheCoalRoadandMt.Carmelmonitorshavebeeninoperationsince1979andreportdatatoU.S.EPA'sAQSdatabase.Twoadditionalmonitors,theTowerandSchrodtmonitors,operateduntilDecember2010andalsoreporteddatatotheAQS.ThePumphousemonitor,whichbecameoperationalonAugust21,2014,isnotreportedtoU.S.EPA'sAQSandis,therefore,notcomparabletothestandard.ThePumphouse,Tower,andSchrodtmonitorshavebeenincludedasweight-of-evidencetoillustratethatambientS02concentrationsintheareahavehistoricallybeen,andcurrentlyare,belowthestandardandthatthecurrentambientnetworkisadequatetocharacterizepotentialimpactsoftheGibsonStation.Page9of34Figure1:S02MonitorsintheVicinityofGibsonStationI01kmMapp.dBy:LFOtgu•co.OliceclAirQu.olnyDate:07115/2015Soureo:IDEM.OfficeofArondEPA,AQSMapProj..,tlon:UTMZono1eNMapOllllum:NAD83*GibsonGeneratingStationActiveS02MonitorsInactiveS02Monitors(Discontinued12131110)Thiim.1phtonrvt1-11nlidInGtlphlortpttstntJIIononly.lhhinto.rmJtionilnetwarr1ntaOforaccuraOJotolharpurpcu-1.Page10of34AsshowninFigure2,modelinghasbeenperformedwhichdemonstratesthatboththeCoalRoadandtheMt.CarmelmonitorsareincloseproximitytotheareaofelevatedimpactsfromtheGibsonStationusing2012-2014meteorologicaldata.Modelingdifferentyearsofmeteorologicaldatamayshiftthelocationofthehighestimpactslightlybut,ingeneral,giventheprevailingsouth-southwestwindpatternasshowninFigure3,thehighestimpactsareexpectedtobeeitheratorveryneartheCoalRoadandMt.Carmelmonitors.Therefore,theCoalRoadandMt.CarmelmonitoringsitesareproperlylocatedtoadequatelycharacterizepeakambientS02concentrationsandsource-orientedimpactsfromtheGibsonStation.PageIIof34

# Figure

2: Gibson

S tation Location

of Elevated

Impact

s I 0



# 1 km **~lap**

**pe**

**d** 

# By

: 

# l.

Fe rguson,

Offic

e

o

f A

i r Quality D

a

l e:08/

14 120

1 5 So

u rcu:Non

O rthophotogr

a phy

Dat

a

·

I DE

M

, O A Q

, Ind

i ana

GI

O

, EP AA

QS

a nd Duke Energy **~lap**



# Pro)

acU

o n:



# U T M

Z one

1 6 N llap

Da

t um

: NAD83



# Gibson Generating

Station S0

2 Monitors •

S0

2 Impact 

# ~ Location

of Highest

Impa

c

t Th

i s map

Is Intended

to

se

r ve

as

an

a id

in 

# graphic

rep<

e senlalion

only

. Th

i s Information

Is no! warranted

lor accuracy

or oCh

e

r purposes

. 

# Pa

ge

1 2

o

f

3 4AcomprehensivelistofhistoricaldesignvaluesformonitorsinthevicinityoftheGibsonStationareshowninGraph1anddemonstratethatallmonitorsattheGibsonStationarecmTently,andhavebeensince2010,belowtheS02NAAQS.TheCoalRoadmonitorusedinthisanalysisisthesamemonitorusedbyU.S.EPAduringRound1designationsin2013.Itwasestablishedthenthatdatafromthemonitorwasappropriatefordetetminingtheattainmentstatusofthearea.Graph1:GibsonStationS02MonitoringNetworkHistoricalDesignValues200180160rt::140I--iii....120t---(LIcIllt::1001---l1lc.8060---fl------,_J_r-_t--h---r--t---t---1--40r---r--r--t--r---t-----20r--c--r--r--t---t----'---0f-..___..-1----........-1-...__,._..4-4-2005-20072006-20082007-20092008-20102009-20112010-20122011-20132012-2014-CoalRoad-GibsonTower-Mt.Carmel-Schrodt-20101-HourS02StandardTheEvansvilleNationalWeatherServicewindroseplotsareshowninFigure3.Thewindrosesshowthefrequencyofthewinddirectionevery10degreesforeachofthewindspeedrangesforthethree-yearmodeledperiodof2012-2014.Thewinddirectionisthedirectionthewindisblowingfromincompassdegreesandthewindspeedsareinmeterspersecond(tn!s).ThewindrosesdemonstratethattheCoalRoadmonitorissitedappropriatelytoaccuratelycharacterizeambientS02concentrationsneartheGibsonStation.Page13of34':'2012<ll.lRTH'"'•·t··,i'\'! '·,:tAST.'I'tI,'....;....l_!-l[SOVlHv.wsru:o(IIH)•...,,•U-111.,,_.,•H·U[321-U0Figure3:EvansvilleWindRoses2012-20142013.2014,..I.\:+..1..••!oovrn../'"(In's)Ill...,••1!.11,1·Sf·U•H·HD11-UDClh".tt'W">AsshowninFigure2,elevatedlevelsofS02werealsofoundonGibsonStationpropertytothesouthwestofthemainstacks.Inresponse,DukeEnergyinstalledthePumphouseS02monitortoassessambientS02concentrations.Table2outlinesthedaily1-hourmaximumS02valuesforthePumphousemonitoringsiteforAugust21,2014-July31,2015.Monitoringdatafromthis•monitorisnotreportedtoU.S.EPA'sAQSandis,therefore,notcomparabletothestandard,buthasbeenincludedasweight-of-evidencetoshowS02concentrationsrecordedatthismonitorhavebeenwellbelowthestandard.Table2:TopTenDaily1-HourS02MaximumValuesforthePumphouseMonitoringSiteDaily1-HourMaximumValueRank(ppb)Date1694/28/20152645/13/20153619/27/201446010/22/20145519/14/20146483/2/20157409/23/20148389/7/20149389/26/201410378/25/2014Page14of34IndianaevaluatedS02sourceswithin30kmoftheGibsonStation.TheGibsonStationwastheonlysignificantsourceofS02emissionsidentifiedinthisarea.IndianarecommendsthatGibsonCounty,Indianabedesignatedasattainmentunderthe20101-hourprimaryS02standard.ThisrecommendationisbasedonthefactthatIndiana'sassessment,performedinaccordancewithU.S.EPA'supdatedguidance,clearlydemonstratesthattheGibsonStation,basedon2012-2014quality-assuredmonitoringdata,isnotlocatedinanareaviolatingtheNAAQSorcausingorcontributingtoaviolationoftheNAAQSinanearbyarea.Indiana-KentuckyElectricCorporation-CliftyCreekGeneratingStationTheCliftyCreekGeneratingStation(CliftyCreek)isacoal-firedpower plantonthenorthernbankoftheOhioRiverinMadisonTownship,JeffersonCounty,Indiana.Thepowerplantislocatedat1335CliftyHollowRoadinMadison,Indiana.TheplantisownedbyOhioValleyElectricCorporation(OVEC)anditswhollyownedsubsidiary,Indiana-KentuckyElectricCorporation(IKEC),aconsortiumofseveralpowercompaniesincludingAmericanElectricPower(AEP).Allsixofitsgeneratingunitsareratedat217.26MWandhaveacapacitytogenerate1,303.56megawatts(MW)ofelectricitycombined.Five(5)oftheunitsarewet-bottompulverizedcoal-firedboilersidentifiedasUnits1through5,withconstructioncompletedin1955,eachwitharatedcapacityof1,869MMBtu/hr.Thesixthunitisawet-bottompulverizedcoal-firedboileridentifiedasUnit6,withconstructioncompletedin1956,witharatedcapacityof1,869MMBtu/hr.CliftyCreekinstalledafluegasdesulfurization(FGD)systemtoprovideS02controlsforitssixgeneratingunits.TheFGDsystemcameonlineinJuly2013.DuetoconditionssetfmihintheConsentDecreeandsubsequentU.S.EPAguidance,IndianareliedonAERMODairdispersionmodelingtodeterminetheattainmentdesignationrecommendationfortheCliftyCreekGeneratingStationasthereisnosite-specificS02airqualitymonitorassociatedwiththisfacility.Modelingresultswereconductedusing4111highmaximumdaily1-hourvaluesaveragedoverthethree-yearmodeledperiodcombinedwithrepresentativetemporallyvaryingseasonalS02backgroundconcentrationstoindicatewhetherthearea violatesthestandardorcausesorcontributestoaviolationofthestandard.IndianausedmeteorologicaldatafromthesurfaceandupperairstationsoutlinedinTable3toconductmodelingforCliftyCreek.Table3:SurfaceandUpperAit·MeteorologicalStationsFacilitySurfaceMetUpperAirMetCliftyCreekGeneratingStationLouisville,KYNWSWilmington,OHNWSPage15of34TheLouisvilleNationalWeatherServicewindroseplotsareshowninFigure4.ApredominatesoutheasttosouthwestwinddirectionisshownintheLouisvillewindroseplotswiththehigherwindspeedsoccurringwhenthewinddirectionsaremoresoutherlytosouthwesterlyandwesterly.Windspeedsareinmeterspersecond(m/s).1wEsT2012NORTH.-t\i$....'..I-iSOlffit.......EAs-r''Figure4:LouisvilleWindRoses2012-2014\WOSPE.EO'""''.n\11•U·\11•H-88•3e·51CJ71·30(;105·:1I(;41'rnt081...2013soum(rn'&).,..11.1•U-111•'H-U•Hl·51021-30[."]05-21C•'tn'0.")"''wtsf2014EAST,_SOVTH\\\'USPEEO(rn't)•·•11.1·111-111•.§7.11•lO·HGi21-)0Du.;nc.n,O)l"ModelingofCliftyCreekusedadjusted(i.e.withoutupwindmajorsourceimpacts)temporallyvaryingseasonalbackgroundconcentrations.TheNewAlbanyS02monitordata,listedinTable4,isconsideredrepresentativebackgroundforJeffersonCounty,Indiana.991hpercentileS02concentrationsbyseason(winter,spring,summerandfall)foreachhourofthedaywerecalculatedfor2012-2014todeterminethetemporallyvaryingseasonalS02background,whichwereuseddirectlyinthemodel.WinterSpringSummerFallTable4:991hPercentilesforTemporallyVaryingSeasonal802BackgroundValues(ppb)for2012-2014Hr1Hr2Hr·3Hr4Hr5Hr6Hr76.617.815.505.574.255.094.898.105.367.038.255.644.853.516.844.053.995.354.143.104.403.343.503.693.642.803.363.39Page16of34Hr85.955.394.624.62Hr9Hr10HrllHr12Hr13Hr14Hr15 Hr16Winter6.016.628.5612.6714.0310.4312.3110.94Spring9.238.919.1810.1116.5013.2811.349.50Summer6.1618.3111.7711.1114.6112.959.459.50Fall5.986.919.449.3811.1411.248.958.96Hr17Hr18Hr19Hr20Hl"21Hr22Hr23Hr24Winter10.388.808.906.906.158.286.288.04Spring17.5615.0613.3811.969.417.695.089.02Summer7.808.6410.0410.268.106.147.446.50Fall10.8112.777.856.353.903.304.705.55MeteorologicaldatafromtheneareststationtotheFloydCountyNewAlbanymonitor,theCharlestownStateParkmeterologicalstationlistedinTable5,wasusedtodeveloptemporallyvaryingseasonalS02backgroundvaluesforCliftyCreek.Table5:LocationoftheNewAlbanyS02MonitorandCharlestownStateParkMeteorologicalStationforBackgroundAnalysisS02MonitorMonitorMeteorologicalStationStationandlD#LocationandlD#LocationDistanceNewAlbany38.31°NCharlestownStatePark38.39°N10.718-043-100485.83°w18-019-000885.66°wmilesIndianaevaluatedS02sourceswithin30kmofCliftyCreek.CliftyCreekistheonlysignificantsourceofS02emissionsinIndianainthatregion;howevertherearetwolargeS02emissionsourcesintheStateofKentuckythatwereevaluatedtodeterminepossibleimpactsonCliftyCreek.2013actualemissionsforthesefacilities,listedinTable6,weremodeledtoevaluatewhetherthesesourcescouldbecausingorcontributingtoaNAAQSviolationinthearea.Table6:CanollandTrimbleCounties-Kentucky:1-Hom·S02ModelingSourceInventories2013S02SourceSourceIDLocationEmissions(tpy)GhentGeneratingStation21-041-00010CarrollCounty,KY3,522TrimbleCountyGeneratingStation21-223-00002TrimbleCounty,KY13,424Page17of34

# Intermittent

Source Justification Aside

from Clifty Creek's

six coal-fired

EGUs,

there

are several

smaller emission

units

that

are intermittent

and have random operational

schedules

or emit

an insignificant

level

of S02 enllSSIOnS.

• Four

( 4) No.

2 fuel

oil- fired

coal transfer

station heaters, installed

in 1993: (I) One

(I) with

a design

heat capacity

of 1.25 MMBtu/hr

for Station

2; (2) One

(I) 

# with

a design

heat capacity

of 1.75 MMBtu/hr

for Station

5; and, (3) Two

(2) each

with design

heat capacities

of2.75 MMBtu/hr

for Stations

B3

and

84. • Stationary emergency

fire pumps Based

on information

provided

by Clifty

Creek,

the transfer

station heaters'

actual emissions

are estimated

to

be less than

one

(I)

ton

per year

as ultra-low

sulfur

diesel

is used

to fuel these heaters.

Due

to the operation

of the stationary emergency

fire pumps, emissions

are estimated

to be less than

0.25

tons

per year. All these

units

are listed

in their

Part

70 Title

V permit

as "insignificant

activities"

as defined

in 326 lAC

2-7-1

(21). IDEM

did

not include

these sources

in the modeling

analysis

since

their level

of activity

was insignificant,

intermittent,

and random

in nature. Initial modeling,

using hourly

CEM

data

from 2012-2014,

showed

high modeled

!-hour

S02 concentrations.

This modeling

included emissions

before

and after Clifty

Creek

had installed

the FGD system.

A decrease

of90%

or more

of S0

2 emissions

occurred

as

a result

of the installation

and operation

of the FGD system.

Pursuant

to Section

5 of the

S0

2 NAAQS Designations

Modeling

TAD, "sources

that implement

emission

controls

during

the relevant

3- year period

and

that becomes

subject

to

an emission

limit requiring

that control

may

wish

to demonstrate

that limit assures attainment,

even though

the 3-year average emissions

level would be estimated

to yield NAAQS violations."

Fmiher discussion

with

U.S.

EPA Region Vindicated that federally enforceable

emission

limits

in place

by the final

S0

2 area designation

date

of July 2, 2016,

would

be recognized

as

an appropriate assessment

of

an area's attainment designation. Therefore,

Indiana modeled

the S02 emissions

from Clifty

Creek

after

the FGD system became operational

to determine

the attainment designation.

Modeled concentrations

for Clifty

Creek including

the impact

of nearby

large

S0

2 emission

sources

and temporally

varying seasonal

S0

2 background concentrations,

as outlined

in Table

7, are well below

the !-hour

S0

2 NAAQS. Page

18 of34Table7:CliftyCreek1-HourS02ModelingResultsModeledConcentration1-HourS02FacilityIncludingSeasonalHourlyNAAQSModelsModeledSourceBackground(!lg!m3)(1!g/m3)AttainmentCliftyCreek71.6196.2YesGeneratingStationIndianarecommendsthatJeffersonCounty,Indianabedesignatedasattainmentunderthe2010!-hourprimaryS02standard.ThisrecommendationisbasedonthefactthatIndiana'sassessmentperformedinaccordancewithU.S.EPA'supdatedguidanceclearlydemonstratesthatthefacilityisnotlocatedinanareaviolatingtheNAAQSorcausingorcontributingtoaviolationoftheNAAQSinanearbyarea.Vectren-A.B.BrownGeneratingStationTheA.B.BrownGeneratingStation(A.B.Brown)isacoal-firedpower plantonthenorthernbankoftheOhioRiverinMarrsTownship,PoseyCounty,Indiana.Theplantislocatedapproximately8mileseastofMountVernon,Indiana,and5milessouthwestofEvansville,Indiana,justwestofthePosey-VanderburghCountyLine.A.B.BrownisownedbyVectren(formerlySouthernIndianaGasandElectricCompany).Eachofthetwocoal-firedEGUshasaratedcapacityof265.2MW.UnitNo.I,constructedin1974withastartupdateof1979,consistsofonedrybottom,pulverizedcoal-firedboilerwithadesignfuelheatinputcapacityof2,518MMBtu/hr.UnitNo.2,alsoadrybottom,pulverizedcoal-firedboilerwithadesignfuelheatinputcapacityof2,530MMBtulhr,wasconstructedin1979andhadastartupdateof1985.DuetoconditionssetforthintheConsentDecreeandsubsequentU.S.EPAguidance,IndianareliedonAERMODairdispersionmodelingtodetenninetheattainmentdesignationrecommendationfortheA.B.BrownStationasthereisnosite-specificairqualitymonitorassociatedwiththisfacility.Modelingresultswereconductedusing4111highmaximumdaily!-hourvaluesaveragedoverthethree-yearmodeledperiodcombinedwithrepresentativetemporallyvaryingseasonalS02backgroundconcentrationstoindicatewhethertheareaviolatesthestandardorcausesorcontributestoaviolationofthestandard.Indianausedmeteorologicaldatafromthesurfaceandupperairstations,outlinedinTable8,toconductmodelingforA.B.Brown.Page19of34

# Table

8: Surface

and Upper

Air Meteorological

Stations Facility

Surface

Met

Upper

Air Met A.B. Brown Generating

Station

Evansville,

IN NWS

Lincoln,

IL NWS Modeling

of A.B. Brown

used adjusted

(i.e. without

upwind

major

source impacts) temporally varying seasonal background concentrations.

The Evansville-Buena

Vista monitor

data, listed

in Table

9,

is considered representative

background

for Vanderburgh

County,

Indiana.

Because A.B. Brown

and

the modeled inventory

sources

(see Table

11)



# are located southwest

of the Evansville-Buena

Vista monitor,

impacts

from

the southwest

direction

were removed

from

the monitoring

data.

99th percentile

S0

2 

# concentrations

by season (winter,

spring, summer

and

fall) for each

hour

of the

day were calculated

for 2012-2014

to determine

the temporally

varying seasonal

S0

2 

# background,

which

were

used directly

in the model. Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall



# Table

9: 99th Percentiles

for Temporally

Varying

Seasonal

S0

2 

# Background

Values

(ppb)

for 2012-2014 Hr1

Hr2

Hr3

Hr4

HrS Hr6 Hr7 6.00

4.22

3.88

4.27

6.02

4.95

5.25 4.99

3.83

4.30

4.34

3.30

4.47

7.75 2.71

2.22

1.00

1.00

2.87

3.45

3.34 3.46

3.30

2.85

3.52

4.00

4.35

4.80 

# Hr9

Hr

10 Hrll

Hr

12 Hr13 Hr14 Hr15 8.89

11.94

13.62

10.29

14.74

19.17

19.48 9.82

9.05

13.37

13.25

15.49

12.02

9.34 10.12

12.58

9.14

7.55

7.47

4.65

4.08 7.73

11.66

15.88

11.70

11.26

10.28

10.03 

# Hr

17 Hr18

Hr19

Hr20

Hr21

Ht·22

Hr23 16.64

16.70

9.18

6.89

8.01

6.59

6.74 13.01

12.93

11.32

8.26

5.59

3.81

5.90 7.88

8.56

7.12

2.71

2.72 2.22 2.86 10.11



# 9.85

8.87

8.51

5.70

2.59

3.06



# Hr8 7.43 9.52 5.99 5.28 

# Hr16 19.76 10.70 6.05 9.08 

# Hr24 6.22 6.10 3.40 3.31 Meteorological

data

from

the nearest

station

to the Evansville-Buena

Vista monitor,

the Evansville,

IN NWS station,

listed

in Table

10, was used

to develop temporally

varying

seasonal 

# so2 background

values.

Page

20 of34Table10:LocationoftheEvansville-BuenaVistaS02MonitorandEvansvilleNWSMeteorologicalStationforBackgroundAnalysisS02MonitorMonitorStationandID#LocationMeteorologicalStationLocationDistanceEvansville-BuenaVista38.01°NEvansville,INNWS38.05°N4.3miles18-163-002187.58°w87.52°wIndianaevaluatedS02sourceswithin30!anofA.B.Brown.PoseyCounty,Indianahastwoadditionalsources,listedinTable11,contributingS02emissionsabove250tpy.2013actualemissionsforthesefacilitiesweremodeledtoevaluatewhetherthesesourcescouldbecausingorcontributingtoaNAAQSviolationofthestandardinthearea.Table11:PoseyCounty,Indiana:1-HourS02ModelingSourceInventories2013so2SourceSourceIDLocationEmissions(tpy)SABICInnovativePlastics129-00002PoseyCounty,IN5,407CountrymarkRefiningandLogistics129-00003PoseyCounty,IN476IntermittentSourceJustificationAsideti·omA.B.Brown'stwocoal-firedEGUs,thereareseveralsmalleremissionunitsthatareintetmittentwithrandomoperationalschedulesoremitsmallamountsofS02emissions.•One(I)simple-cycle,naturalgas-firedcombustionturbine,designatedasunitABBNo.3,constructedin1991,withadesignfuelheatinputcapacityof897.4MMBtu/hr(nominallowheatingvalue),utilizingdistillateoil(No.2fueloil)asabackupfuelwithaCEMsystemfornitrogenoxides(NOx)andS02,withawaterinjectionsystemforcontrolofNOxemissions,exhaustingtoStackNo.3.•One(!)simplecycle,naturalgas-firedcombustionturbine,designatedasunitABBNo.4,constructedin2002,withadesignfuelheatinputcapacityof1,146MMBtu/hour(maximumhighheatingvalue)withinletfoggerforpoweraugmentationduringhighambienttemperatureoperation,withCEMsystemforNOxandS02,withdrylow-NOxcombustion,exhaustingtoStackNo.4.Page21of34Basedon2012-2014CEMdata,ABBNo.3emitted,onaverage,lessthan650poundsofSOzperyearandABBNo.4emitted,onaverage,lessthan885poundsofSOzperyear.Theactualoperationalhoursfortheturbinesvariedeachquarter.Themaximumnumberofhoursofoperationforanyyearwas435hours.IDEMdidnotincludethesesourcesinthemodelinganalysissincetheirlevelofactivitywasinsignificant,intermittent,andrandominnature.SpecificallyRegulatedInsignificantSourcesInsignificantactivitiesatA.B.Brown,ascoveredby326IndianaAdministrativeCode2-7-1(21),include:•Two(2)dieselgeneratorsnotexceeding1,600horsepower.Thedistillateoil-firedemergencygeneratorswereinstalledin1974andareratedat398boilerhorsepower(bhp)each.•One(1)additionaldistillateoil-firedfirepumpwasinstalledin1974andisratedat200bhp.Thetotalemissionsfromallthreeunitsarenomorethan0.55tpybasedonamaximumof500hoursofoperation.IDEMdidnotincludethesesourcesintheanalysissincetheirlevelofactivitywasinsignificant,intermittent,andrandominnature.Initialmodeling,usingA.B.Brown'shourlyCEMdatafrom2012-2014,showedthatmodeled!-hourS02concentrationsfromA.B.Brownandinventorysourceswouldbeabovethe!-hourSOzNAAQS.Afterfollow-updiscussionswithA.B.Brown,thecompanyhasagreedtomodifytheircurrentPSD/TitleVpermittolowertheirS02emission'slimitforcoal-firedEGUNo.1from1.2lbs/MMBtuto0.8571lbs/MMBtu,whilemaintainingthe0.69lbs/MMBtulimitforUnitNo.2.Thisequatestoemissionratesof3,021.6lbs/hrforUnitNo.1and1,745.7lbs/hrforUnitNo.2.Bothunitscanneverexceed2,158.2lbs/hrwhenoperatingtogether.Assuch,UnitNo.IcannotoperateatfullcapacitywhenUnitNo.2isrunningat0.69lbs/MMBtu.Therevisedemission'slimitforUnitNo.1wouldaccountforatotalS02emissionsreductionof2,609.1lbs/hr.A.B.Brownplansonmovingforwardwiththepermitmodificationrequestandhavingcontt·olsinstalledandoperationalonUnitNo.1bynolaterthanMarch2016inordertomeetthelowerS02emission'slimit,wellinadvanceoftheJuly2,2016consentdecreedeadline.IndianamodeledtheproposedS02emissionlimitsrecommendedbyA.B.Brown.Fivescenariosweremodeled.Modeledconcentrationsfortheworstcasescenario(i.e.UnitNo.2operatingat0.69lbs/MMBtuandUnitNo.1operatingat0.164lbs/MMBtu)addedtothetemporallyvaryingseasonalS02backgroundconcentrations,asoutlinedinTable12,arebelowthe!-hourS02NAAQS.Page22of34Table12:A.B.Brown1-HourS02ModelingResultsModeledConcentration1-HourSOzFacilityIncludingSeasonalHourlyNAAQSModelsModeledSourceBackground(!1g/m3)(!1g/m3)AttainmentA.B.BrownGenerating196.08196.2YesStationIndianarecommendsthatPoseyCounty,Indianabedesignatedasattainmentunderthe20101-hourprimaryS02standard.ThisrecommendationisbasedonthefactthatIndiana'sassessment,performedinaccordancewithU.S.EPA'supdatedguidance,demonstratesthatthefacilityisnotlocatedinanareaviolatingtheNAAQSorcausingorcontributingtoaviolationoftheNAAQSinanearbyarea.Furthermore,limitssupportedbyIDEM'sattainmentmodelingwillbeincorporatedintotheapplicablepermitwellinadvanceoftheeffectivedateofdesignationstoensureongoingcompliancewiththe1-hourS02NAAQS.NorthernIndianaPublicServiceCompany-MichiganCityGeneratingStationTheMichiganCityGeneratingStationisacoalandnaturalgas-firedpowerplantonthesouthernshoreofLakeMichiganinMichiganTownship,LaPmieCounty,Indiana.Thepowerplantislocatedat101WabashStreetinMichiganCity,Indiana.ThefacilityisownedbytheNmihemIndianaPublicServiceCompany(NIPSCO)andoperatedbyNiSource.Thefacilityconsistsofonecyclonecoal-firedboiler,identifiedasBoiler12,withadesignheatinputcapacityof4,650MMBtu/lu·,anactivatedcarboninjectionsystemforcontrolofmercury emissionspermittedin2014,andanelectrostaticprecipitatorwithafluegasconditioningsystemforcontrolofpmiiculatematter,exhaustingtoStack4.ConstructiononBoiler12wascompletedinMay1974.Naturalgascanbefiredduringstartup,shutdown,andmalfunctions.Boiler12hasaselectivecatalyticreduction(SCR)systemforNOxcontrol.AcirculatingdryscrubberFGDsystemandafabricfilterbaghousewerepetmittedtobeinstalledonBoiler12in2013.DuetoconditionssetforthintheConsentDecreeandsubsequentU.S.EPAguidance,IndianareliedonAERMODairdispersionmodelingtodeterminetheattainmentdesignationrecommendationfortheMichiganCityGeneratingStation.ThereceptorgridfortheMichiganCityGeneratingStationwasrevisedinordertoaccountforLakeMichiganandtheinabilitytoplaceamonitorinthewater.Therefore,nomodelingreceptorswereplacedatlocationsthatlieoverLakeMichigan.ThereisonemonitorthatmeasuredambientS02airqualitymonitoringdataintheareathroughtheyear2014.Themonitor,asshowninFigure5withID#18-091-Page23of340005,islocatedapproximately0.5kmsoutheastoftheMichiganCityGeneratingStationat341West4thStreetinMichiganCity,Indiana.Monitoringdata,asoutlinedinTable13,showstheannual99thpercentile1-hourdailymaximumS02valuesfortheyears2012-2014,aswellasthe2012-20141-hourS02designvalue.Indianaisincludingthismonitoringdataasweight-ofevidencetoshowthattheyears2012-2014areallwellbelowthestandard.Figure5:MichiganCity,IndianaAreaS02MonitorsMappodBy:L.Ferguson,OfficeofNrQualityDale:0911112015Sou«e:IDEM.OAOendEPA·AOSMapProjecUon:UThlZone16NMapDa1urn:NADSJ*MichiganCityGeneratingStation•Source-OperatedS02Monitor(Discontinued1213112014)Page24of34Table13:2012-2014Annual99thPercentilesand1-HourS02DesignValue(ppb)forMonitorID#18-091-00052012201320142012-201499th 99th 99thDesignLocationMonitoriDMonitorPercentilePercentilePercentileValueLaPorte18-091-0005Michigan2115*1517*County,INCity*Incomplete dataIndianausedmeteorologicaldatafromthesurfaceandupperairstationsoutlinedinTable14toconductmodelingfortheMichiganCityGeneratingStation.InordertoaddressU.S.EPARegionV'scommentsonIndiana'sconsentdecreemodelingprotocol,IndianaprocessedwindandmeteorologicalparametersfromIDEM'sGary-IITRImonitoringstationinnorthernLakeCounty.TheGary-IITRImeteorologicalparameterswereprocessedwithSouthBenddatatocompileameteorologicaldatasetrepresentativeoftheNorthwestIndianaarea.TheGary-IITRImonitoringlocationwasusedwithAERSURFACEfordeterminingthefirstprioritysurfacecharacteristics.However,sincesnowdepthandprecipitationdataarenotreadilyavailablefromtheGary-IITRImonitoringsite,adjustmentstothealbedoandBowenratiosurfacecharacteristicsstillusedtheprecipitation,soilmoisture,andsnowdepthdataduringthewintermonthsfromtheSouthBendNWSlocation.Table14:SurfaceandUpperAirMeteorologicalStationsFacilitySurfaceMetUpperAirMetMichiganCityGary-IITRImonitoringLincoln,ILNWSGeneratingStationstation/SouthBend,INNWSModelingoftheMichiganCityGeneratingStationusedadjusted(i.e.withoutupwindmajorsourceimpacts)temporallyvaryingseasonalbackgroundconcentrations.TheID#18-091-0005monitor,listedinTable15,isconsideredrepresentativebackgroundforLaPorteCounty,Indiana.991hpercentileS02concentrationsbyseason(winter,spring,summerandfall)foreachhourofthedaywerecalculatedfor2012-2014todeterminethetemporallyvaryingseasonalS02background,whichwereincludeddirectlyintothemodel.Page25of34

# Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall

Table

15: 99th Percentiles

for Temporally

Varying

Seasonal

Hourly

S02 Background

Values

(ppb)

for 2012-2014 Hr1

Hr2

Hr3

Hr4

HrS

Hr6

Ht·7 8.00

7.76

7.00

8.77

8.00

8.67

7.00 7.85

8.88

8.87

8.85

8.00

8.00

8.85 7.00

6.71

6.00

6.00

6.00

7.00

6.00 5.69

5.69

6.00

6.66

6.26

5.67

6.71 Hr9

Ht·10

Hrll

Hr

12 Hr13

Hr

14 Hr15 7.00

8.00

9.00

8.00

8.00

9.00

7.00 7.92

7.99

8.00

9.00

7.94

8.00

7.90 8.00

8.91

7.92

8.91

7.88

7.00

8.00 7.76

8.00

8.00

8.00

8.73

8.54

7.76 Hr17

Hr

18

Hr

19 Ht·20

Hr21

Hr22

Hr23 7.79

7.00

7.00

8.00

7.56

7.00

6.80 6.98

7.00

6.96

7.00

7.00

7.86

8.00 8.86

6.00

7.00

6.00

7.00

6.75

6.00 5.65

6.28

6.16

6.00

5.60

5.61

5.00

Hr8 7.00 8.88 7.00 6.69 Hr16 8.00 6.00 8.00 6.71 Hr24 7.00 8.00 8.00 5.00 Meteorological

data

from

the nearest

station

to the Michigan

City monitor,

i.e.

the Gary-IITRI meteorological

station,

listed

in Table

16, was used

to develop temporally

varying

seasonal

S02 background

values

for

the Michigan

City Generating

Station. Table

16: Location

of the Michigan

City

S0

2 

# Monitor

and Gary-IITRI Meteorological

Station

for Bacl•ground

Analysis Monitor Meteorological

Station

Station MonitoriD

Location

Location

Distance and

ID

# 18-091-0005

41.72°N

Gary-IITRI

41.61°N

21.5 86.91°W

18-089-0022

87.30°



# w

miles The South

Bend

NWS

wind

rose plots

are shown

in Figure

6, and

the Gary-IITRl meteorological data

site wind

rose plots

are shown

in Figure

7.

As shown

in

a comparison

of the

two wind roses,

the Gary-IITRI

wind

rose

has

a higher frequency

of northeast

and northerly

wind directions

and southerly

wind directions

indicating

the Gary-IITRI meteorological

site

is capturing the

Lake Michigan

lake/land

breeze influence.

This provides

the justification

for using Page

26 of34theGary-IITRImeteorologicaldatafortheNIPSCOMichiganCityConsentDecreemodelinganalysissincetheNIPSCOfacilityislocatedontheLakeMichiganshorelineasshowninFigure5.Windspeedsareintnls.20122012JZooTHIi...'EASII'""......I'EASJ1Figure6:SouthBendWindRoses2012-2014vm..oSP££0(mJI)••Ill•lt-11.1•S.7·e8.....,D11-H005-21C•·ms:1.06!to2013·,N<>11>i·I'jIO'A!8%'IFigure7:WiNOSPEED,......,••U·ll.l•u.u•30·6702t-3eDos.,.,wesiGary-IITIUWindRoses2012-2014\W.OSP£1:0(m's)IiinIU•fl·11.1•.S7·U•H-S7[,;),,.,uDo.s-21C•lm•O!loe"i.;,_..WEST2013'-I·I8%-ftl.....••.!•"'"EAsr'WV.OSPEEO(ml•).,.,,,•U-111•S.J.IJ•30-57D2.1-Je005-21C11h>110lG..I'i\VESY2014INORIIII'""....i••'l%Illl._.-,...·:.........EAST. !2014\fQHH·'IlIEASIW\NOSPEED'""''..."''·'•85·111•57-U•'l&-51D21-JG005·11V..V.OSPEEl}(rrJ$).uf\1•e.e.ut•57-88•36-!7(;)2'.1•)80091"IndianaevaluatedS02sourceswithin30kmoftheMichiganCityGeneratingStation.PorterCounty,Indianahastwosources,listedinTable17,contributingS02emissionsabove250tpy.2013actualemissionsforthesefacilitiesweremodeledtoevaluatewhetherthesesourcescouldbecausingorcontributingtoaNAAQSviolationinthearea.Page27of34

# Table

17: Porter County,

Indiana:

1-Hour

S0

2 

# Modeling

Source Inventories 2013

SOz 

# Source

Source

ID Location

Emissions

(tpy) NIPSCO

Bailly

Station

127-00002

Pmier County

2,474 ArcelorMittal

Bums Harbor

127-00001

Pmter County

13,864 

# Intermittent

Source Justification Aside

from Michigan

City Generating

Station's coal-fired

boiler,

there

are several

smaller emission

units

that

are intermittent

with random operational

schedules

or emit small amounts

of 

# SOz emissions. • One

(I) natural gas-fired

auxiliary

boiler, identified

as AUXl,

rated

at 109 MMBtu/hr, constructed

in 2003, equipped

with

low

NOx burners, exhausting

to Stack AUX1,

with

a CEMS

for NOx. Boiler

AUXl operated

2,062

hours

in 2013,

the highest

annual operating

hours

of any

of the

last three

years

(i.e. 2012-20

14). Based

on these

hours

of operation,

Boiler

AUXl emitted approximately

134.88 pounds

ofS0

2 

# in 2013.

Since

the total annual

S0

2 

# emissions

were

very low from

this auxiliary

boiler,

IDEM

did

not include

this emission

source

in the modeling analysis. 

# Specifically Regulated Insignificant

Activities Insignificant

activities

at Michigan

City Generating

Station,

as covered

by 326 Indiana Administrative

Code 2-7-1(21),

include: • One

(1) 

# 480,000

British thermal

unit (BTU)

boiler located

in the Gate House, constructed in 1964. • One

(I) 297,000

BTU boiler located

in the Relay

House (Substation

Bldg. #015), constructed

in 1953. Due

to the fact

that

SOz emissions

from

these

types

of sources

are typically

very

low

and

the boilers

have

a heat input capacity

of less than

1 MMBtu/hr,

IDEM

did

not include

these emission sources

in the modeling

analysis.

Page

28 of34Modeling,usingMichiganCityGeneratingStation'shourlyCEMdatafrom2012-2014,showedthatmodeled!-hourS02concentrationsfromtheMichiganCityGeneratingStationandinventorysources,listedinTable17,wouldbebelowthe!-hourS02NAAQS.ModeledconcentrationsfortheMichiganCityGeneratingStationwhenaddedtothetemporallyvaryingseasonalS02backgroundconcentrations,asoutlinedinTable18,arewellbelowthe!-hourS02NAAQS.Table18:MichiganCityGeneratingStation1-HourS02ModelingResultsModeledConcentration1-HourS02FacilityIncludingSeasonalHourlyNAAQSModelsModeledSourceBackgroundAttainmentMichiganCity169.9196.2YesGeneratingStationIndianarecommendsthatLaPorteCounty,Indianabedesignatedasattaimnentunderthe2010!-hourprimaryS02standard.ThisrecommendationisbasedonthefactthatIndiana'sassessmentperformedinaccordancewithU.S.EPA'supdatedguidanceclearlydemonstratesthatthefacilityisnotlocatedinanareaviolatingtheNAAQSorcausingorcontributingtoaviolationoftheNAAQSinanearbyarea.AmericanElectricPower-RockportGeneratingStationTheRockportGeneratingStation(RockportStation)isacoal-firedpowerplantlocatedalongtheOhioRiverinOhioTownship,SpencerCounty,Indiana.ThepowerplantislocatednearRockport,IndianaalongU.S.Route23I,approximatelyonemilenmihoftheWilliamH.NatcherBridgespanningtheOhioRiver.ThefacilityisownedbyIndianaMichiganPower,aunitofAEP.Eachofthetwocoal-firedelectricgeneratingunitshasaratedcapacityof12,374MMBtu/hr.Theboilersconsistoftwodry-bottom,pulverizedcoal-firedopposedwallboilers,identifiedasunitsMBIandMB2,bothconstructedin1977withstartupdatesof1984and1989.EmissionsfromMBIandMB2areexhaustedthroughacommonstack,StackCSOI2.ThefacilityalsohastwoNo.2fueloil-firedboilers,AuxiliaryBoilerIandAuxiliaryBoiler2,constructedin1977withastmiupdateof1983andeachwithadesignheatinputcapacityof603MMBtu/hr,bothexhaustingthroughStackABI2.Page29of34

# Due

to conditions

set forth

in the Consent

Decree

and subsequent

U.S.

EPA guidance,

Indiana relied

on AERMOD

air dispersion

modeling

to determine

the attainment designation recommendation

for

the Rockport

Station

as there

is

no site-specific

air quality monitor associated

with

this facility. Modeling

results

were conducted

using

4

1 h 

# high maximum

daily



# !- hour values averaged

over

the three-year

modeled

period, combined

with representative temporally

varying

seasonal

S0

2 

# background concentrations

to indicate

whether

the area violates the standard

or causes

or contributes

to

a violation

in

a nearby

area. Indiana

used meteorological

data from

the surface

and upper

air stations

outlined

in Table

19

to conduct modeling

for

the Rockpmi

Station.



# Table

19: Surface

and Upper

Air Meteorological

Stations Facility

Surface

Met

Uppe1·

Air Met Rockport Generating

Station

Evansville,

IN NWS

Lincoln,

IL NWS Modeling

for

the Rockport

Station

used adjusted

(i.e. without

upwind

major

source impacts) temporally

varying

seasonal background concentrations.

The Evansville-Buena

Vista

S0

2 

# monitor

data, listed

in Table

20,

is considered representative

background

for Spencer

County, Indiana.

99

1 h 

# percentile

S0

2 

# concentrations

by season (winter,

spring, summer

and

fall)

for each hour

of the

day were calculated

for 2012-2014

to determine

the temporally

varying seasonal

S02 background,

which

was included

directly

into

the model. Winter Spring Summer Fall Winter Spring Summer Fall



# Table

20: 99

1 h 

# Percentiles

for Tempomlly

Varying

Seasonal

Hourly

S0

2 

# Background

Values

(ppb)

for 2012-2014 Hr1 Hr2 Hr3

Hr4

HrS

Hr6

Hr7 6.00

4.25

3.81

4.20

5.75

4.76

5.66 4.48

3.87

3.57

4.06

2.91

3.31

4.47 2.37

2.38

1.00

1.00

3.60

3.90

3.83 2.23

2.28

2.22

3.20

3.54

3.00

3.99 

# Hr9

Hr10

Hrll

Hr

12 H1·l3

Hr

14

Hr

15 8.86

10.80

12.58

10.87

14.64

19.51

19.33 8.36

8.89

13.01

11.98

8.85

11.87

10.46 5.55

12.12

8.41

8.80

5.72

4.40

4.81 7.56

11.32

11.34

11.68

10.07

10.39

7.16 Page

30 of34



# Hr8 7.41 8.25 4.26 5.26 

# Hr16 19.31 12.29 5.27 7.79Ht·17

Hr18

Hr

19 Ht·20

Hr21 Hr22 Hr23 Hr24 Winter

15.65

17.13

9.25

10.40

8.60

8.35

6.29

6.12 Spring

12.28

13.04

11.68

8.29

5.26

3.81

5.76

6.06 Summer

6.35

9.76

7.11 4.74 4.04

2.21

3.04

1.00 Fall

10.68

10.11

6.67

4.68

4.42

2.59

2.80

2.79 The modeling

analysis

used temporally

varying seasonal background

values

taken

from

the Evansville-Buena

Vista

S02 monitor

located

in Evansville, Vanderburgh

County,

Indiana.

!- hour

S0

2 impacts

from

the southeast

direction

were removed

from

the monitoring

data because the Rockport

Station

and

the modeled inventory

sources

are located southeast

ofthe monitor. Meteorological

data from

the nearest

station

to the Evansville-Buena

Vista monitor,

i.e.

the Evansville

NWS station,

listed

in Table

21, was used

for !-hour

S0

2 background

values

for

the Rockport

Station.

Table

21: Location

of the Evansville-Buena

Vista

S0

2 Monitor

and Evansville

NWS Meteorological

Station

for Bacl,ground

Analysis so2

Monitor

Station Monitor

Location Meteorological

Station

Location

Distance and

ID

# Evansville-Buena

Vista

38.01°N

Evansville

NWS Station

38.05°

N

4.3 miles 18-063-0021

87.58°

w

87.52°

w Indiana evaluated

S0

2 sources

within

30 km

of the Rockport

Station.

Warrick

County,

Indiana has three additional

sources contributing

S0

2 emissions

above

250

tpy.

Four

S0

2 emission sources

in the State

of Kentucky

were

also included

in the modeling

analysis

to determine possible

impacts.

2013 actual emissions

for these facilities,

listed

in Table

22, were modeled

to evaluate

whether

these sources

could

be causing

or contributing

to

a NAAQS

violation

in the area.

Page

31 of34

# Table

22: Warrick

County,

Indiana

and Daviess

and Hancock

Counties, Kentucky: 1-Hour

S0

2 

# Modeling

Source Inventories

2013

SOz 

# Source

Source

ID

Location

Emissions (tpy) 

# ALCOA

Warrick

Power

Plant 18-173-00002

Warrick

County,

IN

5,699 ALCOA

Warrick Operations

18-173-00007

Warrick

County,

IN

3,853 SIGECO

Culley

18-173-00001

Wanick

County,

IN

1,948 Big Rivers Electric

Corp 21-091-00003

Hancock

County,

KY

8,146 Owensboro

Municipal

Utilities 21-059-00027

Daviess

County,

KY

8,064 Century Aluminum

ofKY 21-091-00004

Hancock

County,

KY

2,262 Owensboro

Grain

Co. 21-059-00039

Daviess

County,

KY

382 Intermittent

Source Justification 

# Aside

from

AEP Rockport

Station's

two coal-fired

Main Boilers,

MB1

and MB2,

there

are several

smaller emission

units

that

are intermittent

with random operating

schedules

or emit small amounts

of S02 emissions. • Two

(2) No.

2 fuel oil-fired

boilers, identified

as Auxiliary

Boiler

1 and Auxiliary

Boiler 2, constructed

in 1977

with

a stmiup

date

of 1983,

each

with

a design

heat input capacity of 603 MMBtu/hr,

both exhausting

through

Stack

AB

12. • Three

(3) No.2

fuel oil-fired emergency

diesel generators,

identified

as DG1, DG2,

and DG3,

each

with

a design

heat input capacity

of25.16 MMBtu/hr. The highest

annual operating

hours

for Auxiliary

Boiler

1 

# and Auxiliary

Boiler

2, during

the

last three years, 2012-2014,

were

149 hours

and

108 hours, respectively.

In 2014, annual

S02 emissions

from

both auxiliary

boilers

totaled

0.4

tpy. Emergency

diesel generators

DG

1, DG2, and DG3

are restricted

to operating

no more

than

780 hours

per twelve

(12) consecutive

month period

when

main boilers

MB1

and MB2

are

in operation.

In 2014, annual

S0

2 emissions

from the emergency

diesel generators

totaled

0.02

tpy. IDEM

did

not include

these sources

in the modeling

analysis

since

their

level

of activity

was insignificant,

intermittent,

and random

in nature

and annual emissions

were

well below

1 tpy. Page

32 of34Specifically

Regulated Insignificant

Activities Insignificant

activities

at Rockport

Station,

as covered

by 326 Indiana Administrative

Code

2-7- 1(21), include: •

Six

(6) No.

2 fuel oil-fired

space heaters, identified

as WHU-5,

WHU-6,

WHU-7,

WHU8, WHU-9,

and WHU-10

with design

heat input capacities

of 4.5 MMBtu/hr,

3.0 MMBtu/hr,

2.75 MMBtu/hr,

3.5 MMBtu/hr,

4.5 MMBtu/hr,

and

2.2 MMBtu/hr, respectively. • Two

(2) No.2

fuel oil-fired

space heaters, identified

as WHU-1

and WHU-2,

each

with design

heat input capacities

of

1.1 MMBtu/hr. Since

the total annual

S0

2 emissions

from

these insignificant

activities

were

not reported

through Indiana's

Emission

Inventory

Tracking

System (EMITS)

and

are

not expected

to

be significant, IDEM

did

not include

these emission

sources

in the modeling

analysis. Modeling,

using Rockport

Station's

hourly

CEM

data

from 2012-2014,

showed

that modeled!- hour

S0

2 concentrations

from

the Rockport

Station

and inventory

sources

would

be below

the

!- hour

SOz NAAQS.

Modeled concentrations

for

the Rockpmt

Station,

when

added

to the temporally

varying

seasonal

S0

2 background concentrations,

as outlined

in Table

23,

are well below

the !-hour

S0

2 NAAQS.

Table

23: Rockport Generating

Station

1-Hour

S0

2 Modeling

Results Modeled Concentration

1-HourSOz

Facility Including

Seasonal

Hourly

NAAQS

Models Modeled

Source

Background

**(~o~g/m**

**)**

**(~o~g/mJ)**

Attainment Rockport Generating

Station

152.1

196.2

Yes Indiana recommends

that Spencer

County,

Indiana

be designated

as attainment

under

the

20

I 0

!- hour primary

S0

2 standard.

This recommendation

is based

on

the

fact

that Indiana's assessment performed

in accordance

with

U.S. EPA's updated guidance

clearly demonstrates

that

the Rockpmt

Station

is not located

in

an area violating

the NAAQS

or causing

or contributing

to

a violation

of the NAAQS

in

a nearby

area.

Page

33 of34

# Summary

of Recommendations Based

on

the results

of this evaluation,

Indiana recommends

that Gibson, Jefferson,

LaPmte, Posey,

and Spencer

counties

be designated

as attainment

under

the 2010 !-hour primary

S02 standard.

This recommendation

is based

on the

fact

that Indiana's assessment,

performed

in accordance

with

U.S. EPA's updated guidance,

clearly demonstrates

that these facilities,

based on 2012-2014 quality-assured

monitoring

data

and ambient

air quality modeling,

are

not located in

an area currently

violating

the NAAQS

or causing

or contributing

to

a violation

of the NAAQS

in

a nearby

area.

Page

34 of34