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# OAR Box 1778

Prepped by Ollie Stewart



### Document

Number: 

# 93 ) ll-C-3 5

Docket Number: 

# A-90-0 6

Printed 10/28/20089:50:55AM

Sheet 93 of 276

## f) P. 2

£%"\ UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y

- • ^&7 S Offic e o f Ai rQualityPlannin g an d Standard s i^lhfr' / Researc h Triangl e Park , Nort h Carolin a 2771 1

JA N 1 8 199

0

Mr . Morto nSterling , Directo r Environmenta l Protectio n Detroi t Ediso nCompany \X< y

,-,

• n 20 0 Secon dAvenue , 48 2 WC B \ xi'\\ m \ ? ^ ' \ Detroit , Michiga n4822 6 fe.; J.;. Dea r Mr . Sterling : Thi s i s a followu pt o th e Octobe r 19 , 198 9 meetin g durin g whic hDetroi t Ediso nfurthe r discusse dit s positio ntha t th e additio no f natura l ga s firin g capacit y t o th e Greenwoo dUni t I Powe r Plan t shoul dno t b e subjec t t o a preventio no f significan t deterioratio n(PSD ) review . A t th e meeting , yo u requeste dtha t Environmenta l Protectio nAgenc y (EPA ) Headquarter s review Regio nV s previou s determinatio ntha t th e propose dfue l conversio nwa s a "majo r modification " fo r PS D purposes .
A s yo u ar e aware , i

na lette r date dDecembe r 20 , 1988 , EPA Regio nV conclude dtha t th e propose dconversio no f th e oil-fire dGreenwoo dUni t t o dua l capacit y fo r oi l an

d ga s firin g woul dsubjec t th e plan t t o a PS D review fo r nitroge noxide s (NO x ) . Th e Region' s conclusio nwa s base do na determinatio n tha t 1 ) th e sourc e wa s no t capabl e o f firin g natura l ga s prio r t o Januar y 6 , 197 5 (an

d therefor e wa s no t covere db y th e PS D exemptio nfo r modification s unde r 4 0 CF R52.21(b)(2)(iii)(e)(l)) ; an d 2 ) ther e woul db e a significan t ne t increas e o f N0 Xresultin g from th e change . A s yo u hav e requested , w e hav e reevaluate dthi s findin g i nligh t o f th e additiona l informatio nsubmitte db y Detroi t Ediso ndurin g th e Octobe r 1 9 meeting . Th e informatio npresente db y Detroi t Ediso nindicate s tha t th e emission s uni t a t th e sourc e wa s initiall y designe dan

d permitte dt o fir e bot hoi l an d gas . However , ther e i s n o evidenc e t o demonstrat e tha t th e sourc e a s a whol e had , o r a t any

tim e initiate dconstructio non , th e equipmen t necessar y t o delive r natura l ga s t o th e combustio nunit . Withou t suc hequipment , i t woul d no t b e possibl e fo r th e sourc e t o utiliz e natura l ga s a s a nalternat e fuel . Consequently , i t i s ou r vie w tha t th e sourc e wa s no t capabl e o f accommodatin g natura l ga s prio r t o Januar y 6 , 1975 . Therefore , th e change s necessar y t o accommodat e th e firin g o f natura l ga s a t th e Greenwoo dPlan t would , fo r PS D purposes , b e considere da "physica l change " t o th e source .
A s requested , w e hav e als o evaluate dth e ne t emission s chang e a t th e sourc e tha t woul dresul t from th e modification . I t i s Detroi t Edison' s positio ntha t th e larg e decrease s i n"allowable " emission s o f sulfu r dioxide , particulat e matter , an d NO xwhe nburnin g natura l ga s rathe r tha noi l a s a resul t o f th e modification , warrant s specia l consideration . Specifically , Detroi t Ediso nfeel s tha t th e us e o f a cleane r fue l a t th e Greenwoo dPlan t warrant s a findin g tha t there i s no increas e i nactua l emission s an d accordingl y

n o "majo r modification. "2

Unde r th e PS Dregulation , a "majo r modification " occur s whe nth e physica l o r operationa l chang e at th e sourc e (i nthi s cas e th e installatio no f natura l ga s handlin g facilitie s an dth e firin g o f natura l gas ) woul dresul t i n a significan t ne t emission s increas e fo r any regulate dpollutan t a t th e source . Whethe r th e propose dus e o f natura l ga s a t th e Greenwoo dPlan t woul d resul t i na "significan t ne t emission s increase " depend s o na compariso n betwee nth e "actua l emissions " befor e andafte r th e physica l o r operationa l change . Where , a s here , th e sourc e ha s no t ye t begu noperation s firin g natura l gas , "actua l emissions " afte r th e chang e t o natura l ga s firin g ar e deeme dt o b e th e source' s "potentia l t o emit " fo r tha t fue l [se e 4 0 CF R 52.21(b)(21)(iv)] . Potentia l annua l N0 Xemission s whe nfirin g natura l ga s a t th e Greenwoo dPlan t greatl y excee dit s curren t actua l emissions . Therefore , a s a result o f th e abilit y t o fir e natura l ga s afte r th e change , th e emission s of N0 Xa t th e sourc e woul dexperienc e a "significan t ne t emission s increase, " withi nth e meanin g o f th e PS Dregulations . Th e fac t tha t curren t annua l "allowabl e emissions " fo r th e Greenwoo dPlan t whe nfirin g oi l ma y greatl y excee dfutur e allowabl e (o r potential ) emission s whe nfirin g natura l ga s i s no t relevan t fo r PS Dapplicabilit y purposes . Se e Puert o Rica nCemen t Co. . Inc . v . EPA

No.89-107 0 (Firs t Circuit ) (sli pop . Octobe r 31, . 1989) .

Insummary , ou r revie w indicate s tha t Regio nV correctl y

applie dth e PS D applicabilit y

criteria . Th e PS Drequirement s includ e anai r qualit y an dadditiona l impac t analysi s andth e applicatio no f bes t availabl e contro l technolog y (BACT) . Th e BAC T requiremen t applie s t o "eac hpropose demission s uni t a t whic ha ne t emission s increas e woul doccu r a s a resul t of a physica l chang e or chang e i n th e metho dof operatio ni nth e unit " [se e 52.21(j)(3)] . Consequently , althoug hth e additio nof ga s firin g woul dsubjec t th e sourc e a s a whol e t o a PS Dreview , th e requiremen t t o appl y BAC T i s applicabl e onl y t o thos e emission s unit s a t th e sourc e whic hunderg o bot ha physica l or operationa l chang e anda significan t ne t emission s increase . I t appear s tha t th e onl y emission s uni t a t th e Greenwoo dPlan t affecte dby th e proposa l t o fir e ga s woul db e th e existin g boiler . Historically , i t ha s bee nEPA' s polic y tha t wher e th e individua l boile r bein g converte di s capabl e of accommodatin g th e alternat e fuel , BAC T woul dno t apply . Inthi s case , i

nadditio nt o th e physical change s a t th e sourc e necessar y

t o delive r natura l ga s t o th e existin g boiler , a numbe r of cane s capabl e o f burnin g natura l ga s woul db e installe di nth e existin g burne r assemblies . Modification s t o th e unit' s overfire dai r duc t ar e als o planned . We als o understan dtha t ther e wil l b e n o change s i nth e presen t oi l burnin g system , whic hwil l b e retained . Ou r revie w

indicate s that , bv

itself , th e additio no f ga s cane s t o th e burner s i s no t a physical chang e o r chang e i nth e metho do f operatio ni nth e uni t and , consequently , woul dno t subjec t th e boile r t o a BAC T review . Therefore , i f th e sol e chang e t o th e boile r i s th e additio no f th e canes , then , i nthi s case , th e onl y requirement s necessar y fo r a PS Dpermi t ar e an ai r qualit y

analysis , additiona l impact s analyses , an d(i f applicable ) a Clas s I impac t analysis--th e applicatio no f BAC T i s no t required . However , P. 3P. 4

th e informatio nsubmitte db y Detroi t Ediso nindicate s tha t change s t o th e boiler' s overfire dai r duc t ar e als o planned . At thi s time , withou t additiona l informatio no nth e natur e andscop e o f th e wor kt o b e don e o nth e overfire dai r duct , w e canno t determin e whethe r thes e ar e physica l o r operationa l change s t o th e boile r tha t ar e necessar y t o mak e th e boile r capabl e o f accommodatin g natura l gas . I f th e ductin g wor ki s necessar y fo r thi s purpose , the na BAC T analysi s woul dlikel y b e required .

Inaddition , i t i s unclea r from th e informatio nsubmitte dwhethe r Detroi t Ediso nplan s t o undertak e furthe r modification s t o th e boile r whic h woul dallo w

10 0 percen t loa dwhe nfirin g natura l gas . Currently , th e uni t a s presentl y

configure dha s th e potentia l of'achievin g onl y 7 5 percen t loa dwhe n firin g natura l gas . T o achiev e a highe r load , substantia l modification s t o th e uni t apparentl y

woul db e required . Thes e type s o f physica l change s t o th e boile r likel y

woul drequir e a ful l PS Dreview , includin g a BAC T analysi s fo r th e boiler . Th e BAC T analysi s woul drequir e tha t th e sourc e evaluat e th e us e o f al l availabl e additiona l ai r pollutio ncontrol s fo r reducin g N0 Xemissions . Th e analysi s woul dconside r retrofi t cost s fo r add-o ncontrol s andth e fac t tha t ga s i s a relativel y clean-burnin g fuel . Consequently , i nthi s case , i t i s possibl e tha t th e currentl y planne dus e o f a low-N0 xburne r desig nma y b e BAC T fo r ga s firing . However , suc ha conclusio nwoul dhav e t o b e demonstrate d throug hth e requisit e BAC T analysis . I hav e aske dRegio nV t o wor kwit hyo u shoul dyo unee dassistanc e i npreparin g th e analysis .

Geral dA . Emiso n Directo r Offic e o f Ai r Qualit y Plannin g andStandard s

cc : J . Calcagni , EPA/AQM D D . Kee , EPA/Regio nV G . Foote , EPA/OG C