AirQualityAnalysistoSupportMaryland’sProposedStateImplementationPlanRevisionforSinteringPlantsVisibleEmissionsRequirements 

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MDEPreparedbyTheMarylandDepartmentoftheEnvironmentAirandRadiationManagementAdministration1800WashingtonBlvd.Baltimore,Maryland21230-1720April2009TableofContents(\TableofContents1Introduction2AirQualityAnalysisObjectives2SectionA3PM10EmissionsScenario3SectionB3StackParametersandEmissionRates3LandUseClassification3ReceptorGrid/TerrainElevations4GoodEngineeringPracticeStackHeightAnalysesMeteorologicalData5BackgroundAirQualityData8DispersionModelSelection/Options8SectionC9ModelingResults/NAAQSAnalysis9SectionD9Conclusion/AnalysisFindings91IntroductionThepurposeofthisairqualitymodelingimpactanalysisweretodemonstratethatthe24-hourPM10NationalAmbientAirQualityStandard(NAAQS)wouldnotbeadverselyaffectedbytheproposedStateImplementationPlan(SIP)revisionthatwouldaffectonlytheSeverstalSparrowsPointSinteringPlant.TheproposedSIPrevisionwouldremovethevisibleemissionsrequirementsforthissinteringplant.TheSeverstalSparrowsPointSinteringPlantistheonesinteringplantaffectedbythisproposedSIPrevisionandiscurrentlycontrolledwithtwowaterscrubberseachhavingtwofans.TheSeverstalSparrowsPointSinteringPlantwasinitiallysubjecttovisibleemissionsandparticulatematterrequirements;however,theconfigurationoftheside-by-sidescrubbersforthisparticularplantcausesittobedifficulttodemonstratecompliancewithvisibleemissionsrequirementsusingthemethod9observationalprocedures.Theheavysteamplumesfromthescrubbersareusuallycombinedmakingitdifficulttoobserveanyresidualplume.Stacktests,however,havedemonstratedthattheparticulatematteremissionsarealwayswellwithinthe0.03grainloadingrequirementforparticulatematter.TheDepartment,in2007,amendedtheregulationtoexempttheSeverstalSparrowsPointSinteringPlantfromthevisibleemissionsrequirementandestablishedopenendedrequirementsforthescrubberpressuredropandwaterflowrate.ThisSIPrevisionwillincludespecificlimitsforthescrubberpressuredropandwaterflowrate.TheairqualitymodelingimpactanalysiswillbebasedonaPM10emissionratethatcorrespondstotheSinteringPlant’smaximumgrainloadingof0.03gr/dscf.ThemethodusedtocalculatethePM10emissionratewasbasedonstacktestdata,where0.0285gr/dscfcorrespondedtoaPM10emissionrateof133.16lbs/hr(16.8g/sec).AirQualityAnalysisObjectivesTheairqualityimpactanalysiswastoaccomplishthefollowingobjectives:A.DeterminePM10emissionsusedformodeling.B.Providethefollowing:stackparameters,landuseclassification,thereceptorgridandterrainelevations,aGoodEngineeringPractice(GEP)stackheightanalyses,themeteorologicaldata,backgroundairqualityandadescriptionofthemodel/optionsusedintheanalysis.C.DemonstratethatthisproposedSIPrevisionwillnotcauseorcontributetoaviolationofthePM10NAAQS.D.Conclusion/Analysisoffindings.C2SectionAPM10EmissionsScenarioThePM10emissionsusedforthisdispersionmodelinganalysiswerebasedontheSeverstalSparrowsPointSinteringPlant’sapplicablemaximumemissionratebasedonagrainloadingof0.03gr/dscf.Afterreviewingstacktestdataitwasdeterminedthat0.0285gr/dscfwouldbeequaltoaPM10emissionrateof133.16lbs/hr(16.8grams/second).Thisemissionratewasusedforbothstacksinthedispersionmodelinganalysis.SectionBStackParametersandEmissionRatesTheSeverstalSparrowsPointSinteringPlanthastwoscrubberstacks(northstackandsouthstack).Thenorthstackwasmadethecenterofthegridformodelingpurposes.ThemethodusedtocalculatethePM10emissionratefordispersionmodelingpurposeswasdescribedpreviouslyinSectionA.ThePM10emissionratesandstackparametersusedindispersionmodelingarepresentedinTableB-i.CTABLEB-I.SinteringPlantPM10EmissionRatesandStackParametersPM10StackCoordinatesEmissionBaseStackExitStackExitRateXyElevationHeightDiameterTemperatureVelocityStack(glsec)(m)(m)(m)(m)(m)(K)(mis)Ni16.8372782.084341504.004.0847.245.0310.6514.335116.8372781.484341483.654.4847.245.0310.6514.33LandUseClassificationTheSeverstalSparrowsPointSinteringPlantislocatedinanareathatiscategorizedasurbanbasedonthelanduseproceduresdescribedinsection8.2.8oftheU.S.EPA“GuidelineonAirQualityModels(Revised)”datedJuly1986andAuer,A.H.“CorrelationofLandUseandCoverwithMeteorologicalAnomalies”,JournalofAppliedMeteorology,Volumel7,May1978.Thepercentageoflandfallingintooneoffivelandusetypes(11,12,Cl,R2,R3)withinathreekilometercirclearoundthepowerplantwassubjectivelydeterminedusingLandUse/LandCovermap.Byinspection,itwasdeterminedthatover50percentoftheareawasurbaninnature.Thus,urbandispersionmodelingcoefficientsandwindprofileexponentswereusedinthedispersionmodelinganalysis.3ProvidedinFigureB-iisamapdepictingthelanduse/landcoveraroundtheSeverstalSparrowsPointSinteringPlant.ReceptorGrid/TerrainElevationsACartesianreceptorgridconsistingof1,703receptorswereusedforthisdispersionmodelinganalysis.TheCartesianreceptorgridconsistedonthefollowingsubgrids:.Fenceline:-Evenlyspacedreceptors50metersapartplacedalongthepropertyline.•Fencelineto2kilometers:-Evenlyspacedreceptorsusing100meterincrementalspacing.•2—5kilometers:-Evenlyspacedreceptorsusing500meterincrementspacing.Terrainelevationswerecalculatedforeachofthediscretereceptorsusing7.5—minuteDEMfilesasinputintotheAERMAPprogram.FigureB-i.LandUse/LandCoverwithin3KilometersoftheSeverstalSparrowsPointSinteringPlant4GoodEngineeringPracticeStackHeightAnalysesIfastackislowerthanGoodEngineeringPractice(GEP),excessiveambientpollutantconcentrationsduetoaerodynamicdownwashmayoccur.Stackstallerthan65meters(213feet)arelimitedtoGEP,theheightusedtocompletethemodelingneededtoestablishpollutantemissionlimitations.TheGEPstackheighttakesintoaccountthedistanceanddimensionsofnearbystructures,whichaffectsthedownwindwakeofthestack.Thedownwindwakeisconsideredtoextendfivetimesthelesserofthestructure’sheightorwidth.AGEPstackheightisdeterminedforeachnearbystructurebythefollowingformula:HgH+1.5LWhere:HgistheGEPstackheightHisthestructureheightListhestructure’slesserdimension(heightorwidth)AllbuildingsthatwerelargeenoughandcloseenoughtoinfluencetheSeverstalSparrowsPointSinteringPlantstackswereconsideredintheGEPanalyses.ToperformthisanalysisandensureallEPArequirementswereproperlyimplemented,commerciallyavailablesoftwarefromLakesEnvironmentalwasused.TheLakesEnvironmentalBPIPprovidedaninputfilecontaining36direction-specificbuildingheightsandwidthsfordirectinputintothedispersionmodel.BothoftheSeverstalSparrowsPointSinteringPlantstackheightsare155feet(47.24meters)andarethusshorterthan213feet(65meters)sofordispersionmodelingpurposesbothstacksareshorterthanGEPandsubjecttodownwashandweremodeledwiththeappropriateBPIPstructureparameters.MeteorologicalDataThemeteorologicaldataselectedforthisairqualityanalysisconsistedofsurfacedatafromBaltimore-WashingtonInternationalThurgoodMarshallAirport(BWI)andupperairdatafromSterling,VA.BWIislocatedapproximately17kilometers(11miles)awayinLinthicum,MDandSterling,VAislocatedapproximately90kilometers(56miles)away.Thefive-yearperiodof1986-1990wasusedforthedispersionmodelinganalyses.Thisfive-yearperiodwaschosenbecauseitwasthemostrecentreadilyavailabledata.ThedatawasprocessedusingtheAermetprogram.PriortousingtheBWIsurfacemeteorologicaldataananalysiswascompleted,whichcomparedtheSeverstalSparrowsPointSinteringPlant’ssurfacecharacteristicswiththoseofBWItodetermineiftheBWImeteorologicaldatacouldbeusedinthismodelinganalysis.ThisanalysiswascompletedusingtheAERSURFACEprogram,thisEPAtoolisusedfordeterminingrealisticandreproduciblesurfacecharacteristicvalues(i.e.,Albedo,BowenRationandSurfaceRoughness).Theresultsofthe12sectoranalysisarepresentedinTableB-2.05TABLEB-2.AERSURFACESiteSpecificSurfaceCharacteristicsforBWIandtheSeverstalSparrowsPointSinteringPlantSurfaceCharacteristicsSectorAlbedoBowenRatioSurfaceRoughnessNumberDegreeRangeBWIPlantBWIPlantBWIPlant10-300.160.120.760.220.0360.870230-600.160.120.760.220.0190.705360-900.160.120.760.220.0170.310490-1200.160.120.760.220.0440.6625120-1500.160.120.760.220.0310.4806150-1800.160.120.760.220.1650.2567180-2100.160.120.760.220.6420.2308210-2400.160.120.760.220.3560.0769240-2700.160.120.760.220.3250.02610270-3000.160.120.760.220.0500.41811300-3300.160.120.760.220.0250.61512330-3600.160.120.760.220.4200.767AccordingtotheAERMODImplementationGuide,iflandcovervariessignificantlybydirection,thensurfaceroughnessshouldbedeterminedbasedonasector.Basedonthewindrose(seeFigureB-2)developedwith1986-1990BWIdatathewinddirectionispredominatelyfromthewesterndirection.6C 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ON ON 00 ON 0 ci) ci) N /TheAERSURFACEprogramwasrunagainusinga90degreesectorof225°-315°inordertomakethemostreasonablecomparisonbetweenthetwolocations.PresentedinTableB-3aretheresultsofthiscomparison.Basedonthiscomparisonofthesurfaceroughness;BWImeteorologicalstationsufficientlymatchthoseoftheSeverstalSparrowsPointSinteringPlantandtheBWImeteorologicalcanbeusedforthismodelinganalysis.TABLEB-3.AERSURFACESurfaceRoughnessComparisonUsinga90°SectorCenteredonDueWestILocationSectorSurfaceRoughnessBWIII0.113N225-315Plant0.102BackgroundAirQualityDataPM10ambientairqualitybackgrounddatawasobtainedfromMDE’sSoutheastPoliceStationPM10monitor,whichislocatedapproximately11kilometers(7miles)awayfromtheSeverstalSparrowsPointSinteringPlant.TheSoutheastPoliceStationmonitorwastheclosestPM10monitortotheSeverstalSparrowsPointSinteringPlantandwasalsoconsideredrepresentativeofthearea.TheSoutheastPoliceStationPM10datawascollectedduringtheyears2005-2007.Tobeconservative,the24-hour1sthighPM10backgroundconcentrationsweredeterminedbasedoncalculatingtheaverageofthemaximumconcentrationsfromtheperiod2005-2007.ProvidedinTableB-4isthe24-hourPM10ambientbackgrounddatafor2005-2007.TABLEB-4.PM10BackgroundAmbientAirMonitoringDataMonitorYear1stHigh24-Hour(tg/m3)200549SoutheastPoliceStation200645(SiteID:245100008)200752Background49DispersionModelSelection/OptionsThemostrecentversion(07026)oftheAMS/EPARegulatoryModel(AERMOD)wasusedtocompletethedispersionmodelinganalysis.8Thefollowingregulatorydefaultoptionswereused:•Stack-tipDownwash-•ElevatedTerrainEffects•UseCalmsProcessingRoutine•“UpperBound”ValuesforSupersquatBuildingsSectionCModelingResu1tsINAAQSAnalysisTheSeverstalSparrowsPointSinteringPlantwasmodeledtodemonstratecompliancewiththe24-hourPM10NAAQSduetotheproposedSIPrevisionthatwouldaffectonlytheSeverstalSparrowsPointSinteringPlant.TheproposedSIPrevisionwouldremovethevisibleemissionsrequirementforthisSinteringPlant.TheFirsthigh24-hourmodeledPM10concentrationwas47.56jig/rn3andoccurredin1988.Addinga24-hourbackgroundconcentrationof49jig/rn3resultedinatotalPM10concentrationof96.56jig/rn3,whichislessthanthePM1024-hourNAAQSof150jig/rn3.ProvidedinTableC-iarethemaximum24-hourPM10concentrationsforeachofthefiveyearsmodeled.TABLEC-i.SeverstalSparrowsPointSinteringPlant24-HourPM10ModelingResultsModeled24-HourTotal.ReceptorConcentrationConcentrationYear(jig/rn3)X(rn)Y(m)(jig/rn3)198642.36373532.694341232.0091.36198739.10373532.694341232.0088.10198847.56373532.694341232.0096.56198945.88373532.694341232.0094.88199045.42373532.694341232.0094.42Notes:TotalConcentration=Modeled24-HourConcentration+Background(49jig/rn3).24-hrPM10NAAQSis150jig/rn3.Boldvaluerepresentsmaximumtotalconcentration.SectionDConclusion/AnalysisFindingsBasedonthePM10dispersionmodelinganalysis,itwassuccessfullydemonstratedthatairqualitywouldnotbeadverselyaffectedbytheproposedSIPrevisionthatwouldaffectonlythe9SeverstalSparrosPointSinleringPlant.TheproposedSIPrevisionmildremovethevisibleemissionsrequirementsforthissinteringplant.•l(1CCC