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# OAR Box 1830 Prepped byOllie Stewart



### Document

Number: 

# 34 ) IV-B-3 2 Docket Number: 

# A-87-1 1

Printed 11/13/20087:20:52 AM Sheet 34of 232P. 2 

# USB J UNITE D STATE S ENVIRONMENTA LPROTECTIO N AGENC Y AN N ARBOR . MICHIGA N 4810 5 

## JA N * 0 199*

MEMORANDU

M SUBJECT : FROM :
T O : 

# DJjLLUJLg

lUi j JA N 24199 4Wj OFFIC E O F AI R AN D RADIATIO N

Revie wan d Analysi s o f Sierr a Researc hRepor t Glen nW . Passavant , Chie f ^ycS^c-w . (JJ -^fcKAJ^uu^ZA^ Specia l Regulator yProject s Branc h Publi c Docke t A-87-1 1 I . Introductio n O nNovembe r 5 , 199 3 EP Areceive d a lette r fro mth e America n Automobil e Manufacturer s Associatio n(AAMA ) transmittin g a repor t entitle d " AComparativ e Studyo f th e Effectiv e o f Stag e I I Refuelin g Control s an d Onboar d Refuelin g Vapo r Recovery " . Th e repor t ha d bee n prepare d b ySierr a Research , Inc . fo r AAMA. Th e mos t recen t commen t perio d o nth e propose d onboar d refuelin g vapo r recover y(ORVR ) requiremen t close d o nAugus t 22 , 1993 . Thi s repor t wa s receive d mor e tha nsi xweek s afte r th e clos e o f th e commen t period . However , i nth e spiri t o f maximizin g th e consideratio no f publi c inpu t o n th e rulemakin g decisions , w e ar e assessin g th e content s o f th e repor t i nth e cours e o f th e fina l rulemakin g deliberations . Th e remainde r o f thi s memorandu mi s divide d int o fou r sections . Sectio nI I review s th e fundamenta l issues , analytica l approac han d conclusion s o f th e Sierr a Report . Sectio nII I describe s genera l an d specifi c point s o f disagreemen t betwee nth e Sierr a repor t an d EPA' s Regulator yImpac t Analysi s (RIA) . Sectio nI V compare s th e Stag e I I an d ORVReffectivenes s value s a s derive d fro mth e Sierr a Repor t an d EPA' s RI Aan d discusse s th e differences . Finally , Sectio n V present s discussio nan d conclusion s o nORVRcontrol s benefit s incrementa l t o Stag e I I base d o nEPA' s analysis . II . Summar yo f Sierr a Repor t Th e Sierr a repor t identifie d thre e fundamenta l issue s t o b e assesse d i nth e report : Thes e included : 1 . Identifyin g whic happroach , Stag e I I o r ORVR , i s bes t fo r improvin g ai r quality ; 2 . Determinin g what , i f any , incrementa l ai r qualit y benefit s wil l resul t fro ma combinatio no f Stag e I I an d ORVRcontrol s relativ e t o th e implementatio n o f onl y Stag e I I systems ; an dP. 3

3 . Assessin g wha t impac t a phase-ou t o f Stag e I I control s woul d hav e o nrefuelin g emission s afte r ORVRsystem s ar e i nwidesprea d use . Sierr a the nidentifie d thre e step s t o asses s thes e concern s a s show nbelow . 1 . Identificatio no f area s require d b yth e CAA At o implemen t Stag e I I controls ; 2 . Determinatio n o f th e statu s o f Stag e I I implementatio n i n area s wher e i t wil l b e require d an d estimatio no f th e percentag e o f refuelin g emission s tha t wil l b e eliminate d i neac hare a byStag e I I system s durin g th e 1993 , 1994 , an d 199 6 ozon e seasons ; an d 3 . Performanc e o f a n emission s inventor yanalysi s ove r a 20

- yea r period , base d o nEPA' s MOBILES.O a emissio nfacto r model , t o compar e th e benefit s o f Stag e II , ORVR , an d combination s o f Stag e I I an d ORVRsystem s i nthre e area s representativ e o f moderat e (Phoenix , Arizona) , seriou s (Boston , Massachusetts) , an d sever e (Houston , Texas ) ozon e nonattainmen t areas . Afte r gatherin g th e desire d informatio nan d makin g assumption s whe nnecessar ySierr a conducte d a nanalysi s comparin g th e effectivenes s o f Stag e I I an d ORVRcontrols . Base d o nth e separat e analyse s fo r Stag e I I an d ORVRcontrol s Sierr a reache d th e followin g conclusions . 1 . Implementatio no f Stag e I I system s withou t ORVRwil l eliminat e 75-85 % o f th e sumo f refuelin g an d fue l spillag e VO C emission s b y1996 , reaffirmin g tha t Stag e I I system s wil l eliminat e th e bul k o f refuelin g emission s befor e th e sal e o f th e firs t ORVR-equippe d vehicle . 2 . Implementatio n o f ORVRsystem s o npassenge r car s alon e would , i nth e absenc e o f Stag e I I controls , eliminat e onl y50-60 % o f refuelin g emission s byth e yea r 2015 , base d o nEPA' s ORVRassumptions . MOBILE5.0 a run s base d o nmor e realisti c assumption s regardin g ORVR effectivenes s indicat e tha t ORVRsystem s o npassenge r car s wil l reduc e refuelin g emissions , b yonl y30-45% . Therefore , ORVRo n passenge r car s alon e wil l provid e 15

- 55 % les s contro l tha n implementatio n o f Stag e I I system s alone . 3 . Implementatio n o f ORVRsystem s o nal l gasoline-fuele d vehicles , i nth e absenc e o f Stag e I I controls , woul d ultimatel yresul t i n greate r contro l o f refuelin g emission s tha nimplementatio n o f Stag e I I system s alone , usin g EPA' s optimisti c assumption s regardin g ORVR performanc e i ncustome r service . However , thi s woul d no t occu r unti l som e tim e afte r 2005 , mor e tha n1 0 year sP. 4

afte r th e tim e bywhic hful l implementatio no f Stag e I I requirement s coul d hav e occurre d i nmos t ozon e nonattainmen t areas . Further , th e incrementa l reductio n i nrefuelin g emission s woul d b e n o mor e tha nabou t 10 % fo r anyo f th e thre e citie s considere d i nthi s analysis . I ncontrast , th e analysi s base d o nmor e realisti c assumption s o f ORVReffectivenes s indicate s tha t th e us e o f ORVRo nal l gasoline-fuele d vehicle s woul d provid e les s contro l o f refuelin g emission s tha t Stag e I I throug h a t leas t 2015 . 4 . Implementatio n o f ORVRo neithe r passenge r car s o r al l gasoline-fuele d vehicle s i ncombinatio nwit hStag e I I requirement s woul d resul t i ngreate r contro l o f refuelin g emission s tha nStag e I I alon e i f EPA' s ORVRassumption s ar e use d i nth e analysis . However , eve ni f th e optimisti c EP Aassumption s ar e used , th e incrementa l reduction s i nrefuelin g emission s ar e smal l fo r ORVR implementatio no npassenge r car s an d eve nsmalle r fo r th e extensio no f ORVRrequirement s t o light-dut ytruck s an d heavy-dut yvehicles . Mor e importantly , thes e benefit s ma yb e illusor ybecaus e whe n breathin g los s effect s ar e considered , th e us e o f ORVRi n combinatio nwit hStag e I I system s lead s t o les s contro l o f refuelin g emission s tha n wit hStag e I I alone . (Thi s counter-intuitiv e resul t occur s becaus e ORVR-equippe d vehicle s preven t Stag e I I system s fro m

returnin g vapor s t o th e undergroun d storag e tank . Withou t th e retur n o f th e vehicl e tan k vapors , th e undergroun d tan k mus t breath e i n fres hair , whic hlead s t o additiona l vaporizatio no f liqui d fuel. ) 5 . I f a phase-ou t o f Stag e I I requirements , provide d fo r by th e CAAA , wa s t o occu r i n 201 0 wit hORVRimplemente d onl y o npassenge r cars , i t woul d resul t i na 15-55 % increas e i nrefuelin g emission s relativ e t o th e leve l o f contro l provide d b yStag e I I system s alone . Th e Stag e I I phase

ou t would , however , hav e littl e impac t o nrefuelin g emission s relativ e t o th e ORVR-onl ycas e wher e ORVRi s require d o nal l gasoline-powere d vehicles . III . EP ACritiqu e o f Sierr a Repor t EP Adisagree s wit hbot hth e genera l issue s raise d b ySierr a a s th e area s fo r analysi s an d som e specific s o f th e Stag e I I an d ORVR analyse s conducte d bySierr a t o asses s thes e issue s an d reac hthei r conclusions . Eac ho f thes e i f discusse d below . A . Genera l A s a resul t o f th e Clea n Ai r Ac t Amendment s o f 199 0 bot hStag e I I an d ORVRcontrol s ar e required . B yth e tim e ORVRcontrol s begi n i nth e 199 8 mode l year , Stag e I I wil l b e i nplac e i nal l seriou s an d wors e ozon e NAarea s an d man ymoderat e area s wil l hav e voluntaril y implemente d Stag e I I control s a s well . However , ORVRcontrol s o nP. 5

light-dut yvehicle s (LDVs ) ar e als o require d unde r th e Act , wit hEP A holdin g th e statutor yauthorit yt o requir e ORVRcontrol s fo r light

dut ytruck s (LDTs ) and/heavy-dut yvehicle s (HDVs ) unde r sectio n 202(a ) (1 ) . Thus , th e questio ni s no t Stag e I I v s ORVRa s suggeste d by Sierra , bu t whic hi s th e bette r choic e fo r th e lon g term , retainin g Stag e I I solel yfo r th e purpos e o f capturin g LDT/HD V refuelin g emissio no r requirin g LDT/HD V ORVRcontrol s wit hth e eventua l phase

ou t o f Stag e I I control s a s allowe d unde r sectio n202(a)(6 ) o f th e Act . I nmakin g suc ha decisio n th e compariso nshoul d b e mad e o n whic hstrateg yi s th e mos t effectiv e (get s th e greates t o f refuelin g emissio nreduction s overall ) an d o n whic hstrateg yi s th e mos t cos t effectiv e i nth e lon g term . Th e Sierr a repor t addresse s neithe r th e absolut e ton s o f emissio nreductio no r th e cos t effectivenes s o f controllin g LDT/HD V refuelin g emissio nbyeithe r Stag e I I o r ORVR controls . Thus , it s utilit ya s a ninpu t t o decisio nmakin g i s limited . B . Specifi c Concern s I npreparin g th e RI Afo r th e ORVRrule , EP Aan d Sierr a considere d man yo f th e sam e points . Whil e ther e ar e som e mino r difference s betwee n th e EP Aan d Sierr a analyse s o f th e effectivenes s o f Stag e I I an d ORVRcontrols , th e ke ydifference s ar e identifie d below .

• EP Aan d Sierr a d o no t agre e o nth e numbe r o f moderat e ozon e NAarea s whic hwil l hav e Stag e II . I t i s no t require d no r wil l i t b e installe d i nal l moderat e NA areas .

• Th e gasoline/servic e statio n throughpu t distribution s i n Tabl e 7 o f th e Sierr a repor t weigh t fue l distributio n to o muc htowar d large r stations . Th e EP Ametr o distributio n i s appropriat e fo r mos t NAAs , bu t i nth e cas e wher e Stag e I I i s require d throug ha n entir e state , th e nationwid e distributio ni s considere d mor e representative .

• Th e ORVRin-us e efficienc yrat e ignore s th e positiv e impact s o f ful l lif e usefu l lif e an d onboar d diagnosti c systems .

• Th e liqui d sea l ORVRsyste mentrainmen t rat e use d by Sierr a i s of f bya facto r o f 2 . Eve nG Mi nthei r comment s indicate d a valu e o f 2 5 percent .

• Fo r th e reason s discusse d i nth e Summar yan d Analysi s o f Comments , th e assertio ntha t ORVRcontrol s wil l negat e th e claime d effectivenes s o f Stag e I I i nreducin g emptyin g los s emission s i s exaggerate d i f no t unfounded .P. 6

IV . Compariso no f Sierr a an d EP AEffectivenes s Estimate s fo r Stag e I I an d ORVR A . Stag e I I Sierr a compare d th e effectivenes s o f Stag e I I an d ORVRplu s Stag e I I fo r thre e areas , Phoenix , A Z (moderate) , Boston , MA (serious) , Houston , T X(severe) , an d dre wit s conclusion s base d o n tha t analysis . Sierr a projecte d Stag e I I efficiencie s o f 80.2 , 85.5 , an d 85. 5 percen t fo r thes e thre e areas , respectively . EPA' s analysi s wa s no t don e o na nare a b yare a basis , bu t rathe r o na combine d basi s fo r al l areas . T o simplify , EP Ause d a n 8 6 percen t efficienc y(annua l enforcement ) fo r al l area s an d a 10/1 0 exemptio nleve l a s indicate d i nth e 199 1 EP AStag e I I Technica l Guidanc e document . O na noveral l basis , thes e simplification s wer e conservative , sinc e the ylea d t o highe r Stag e I I effectivenes s values . Als o a s wa s mentione d above , EP Ause d a metr o servic e statio nthroughpu t distributio n fo r al l area s excep t fo r situation s wher e Stag e I I i s a statewid e requirement , suc ha s i s th e cas e i n Massachusetts . I nthos e state s EP Ause d a nationwid e servic e statio nthroughpu t distribution . EPA' s estimat e o f th e averag e Stag e I I effectivenes s (80. 7 percent) , fall s wel l withi nth e distributio no f state-by-stat e Stag e I I effectivenes s value s foun d i nTabl e 9 o f th e Sierr a report . However , EP Adoe s no t believ e tha t Stag e I I implementatio nwil l b e a s widesprea d a s indicate d by Sierra . B . ORVR Sierra' s estimat e o f th e in-us e effectivenes s o f ORVRcontrol s i s foun d i nAppendi xC o f th e Sierr a Report . Sierr a estimate s a valu e o f abou t 8 0 percen t assumin g

- a 9 7 percen t efficienc yfo r a properl yoperatin g syste m

- a 6. 2 percen t in-us e failur e rat e

- a 5 0 percen t increas e i n emission s fro mfaile d system s du e t o th e liqui d sea l

- a nattributio no f a claime d increas e i nemptyin g los s emission s t o ORVRsystem s I ncalculatin g th e effectivenes s Sierr a use d a nemissio nrat e o f 4.5 4 g/ga l fo r refuelin g emission s an d .45 4 g/ga l fo r emptyin g losses . Th e calculatio ni s show nbelow :

(1-.062 ) (.97 ) (4.54 ) + (0M.454 ) + ( . 062 ) ( . 5 ) ( 4 . 54 ) = (4.54 ) + (.454 )

EPA' s estimat e o f th e in-us e effectivenes s o f ORVRsystem s i s describe d i nth e RIA . EP Aexpect s tha t ORVRsystem s wil l b eP. 7



### designe d fo r essentiall yzer o emission s a t certification . The effectivenes s o f a properl yoperating integrate d systemwil l depend onth e fue l RVP , temperatures , an d amoun t o f fue l dispense d during an ygive n event . Whe n thes e factor s ar e take nint o account , EPA' s bes t estimat e i s abou t 9 7 percen t i nozon e N Aarea s an

d 9 3 t o 9 5 percen t nationwide , depending o n wha t fue l temperatur e distributio n i s assume d fo r th e southeas t US . Thes e value s ar e decrease d b yin-us e failures . However , a s i s discusse d below , EPA' s estimat e o f in-us e failures , base d on evaporativ e emissio nexperience , i s muc hles s tha n tha t use d b y Sierra . Ther e ar e tw o type s o f system failure s commo nt o evaporativ e control , system

pressur e failure s an d purg e failures . System pressur e failure s ar e no t expecte d t o impac t ORV Refficienc ybecaus e o f th e shor t duratio n o f refueling event s an d th e highsystem pressur e an

d vapo r flowrate s during refueling . However , a s i s discusse d belo wonboar d diagnostic s (OBD ) an d enhance d I/ Mwoul d b e helpfu l i n dealing wit hpressur e failur e relate d emission s shoul d theyb e significant . Wit hregar d t o purg e systemfailures , curren t evaporativ e systempurg e failur e rate s ar e abou t 3. 5 percen t fo r 50,00 0 miles . Suc ha highfailur e rat e woul d no t b e expecte d wit hORV Rsystem s fo r severa l reasons . Th e ful l lif e usefu l lif e requiremen t wil l upgrad e componen t reliability . Base d o n thi s requiremen t EPAexpect s a purg e systemfailur e rat e ove r th e ful l lif e t o b e simila r t o tha t see nove r th e half-lif e (3.5%) . Furthermore , enhance d I/Man d OBD wil l reduc e thi s failur e rate , sinc e bot hsystem s wil l chec k th e functionalit yo f th e purg e system . Dat a availabl e t o EPAsuggest s tha t enhance d I/ Man d OBD wil l reduc e thes e failure s b y8 0 percen t i nNAAs . However , i n area s withou t enhance d I/M , OBD alon e wil l b e les s effective . A t leas t 8 0 percen t o f failure s wil l b e identifie d b yth e system , bu t onl y6 0 percen t o f th e faile d vehicle s (3/ 4 o f th e identifie d failures ) wil l b e corrected . Ona weighte d basis , th e failur e rat e i s abu t 1. 2 percent . Enhance d I/ Mand OBD wil l discourag e system tampering . Furthermore , tampering wil l b e discourage d b ymovemen t o f th e caniste r fro

mth e engin e compartmen t t o th e rea r o f th e vehicl e a s manufacturer s indicat e i s likel yi nman yORV Rsystems . A s i s discusse d i n th e RIA , liqui d seal s mayincreas e vapo r generatio n i n ORV

Rsystem

wit hfaile d purg e system s b y2 5 percent . Thi s increase s th e effec t o f th e failur e rat e t o abou t 0. 9 percen t i nNAA s an

d 1. 5 percen t overall . Unlik e th e Sierr a report , EPA' s analysi s include s n o detrimen t fo r emptying losses . A s i s discusse d mor e full yi nth e Summaryan d Analysi s o f Comments , emptying los s emission s ar e no t wel l characterize d o r understood . I t i s no t clea r i f and whe nemptying losse s occu r i n conventiona l tanks , i f an d ho weffectiv e Stag e I I i s i nreducing emptying losses , an d wha t effec t ORV

Rwoul d hav e onP. 8

thi s control . Eve nwit hthes e uncertainties , ther e i s a n alternativ e contro l strateg yavailabl e shoul d i t b e deeme d necessary . Apressure/vacuu mven t valv e o r limitin g orific e whic h wil l contai nemission s ca n b e place d a t th e outle t o f th e ven t pip e fro mth e undergroun d storag e tank . Whe nused , thi s technolog ywoul d b e effectiv e o nconventiona l an d Stag e I I equippe d fue l dispensin g systems . Give nthes e uncertaintie s an d alternativ e approache s i t i s no t necessar yo r appropriat e t o includ e emptyin g losse s i n th e ORVRsyste meffectivenes s evaluation . Thus , i nsummary , EP Apredict s a n ORVRsyste mefficienc yo f abou t 9 5 percen t i nozon e NAarea s an d 92-9 5 percen t overal l dependin g o nwha t i s assume d abou t th e dispense d fue l temperatur e i nth e southeas t U.S . V . Discussion/Conclusio n Th e discussio nabov e an d th e analysi s i nth e RI Asuppor t a numbe r o f conclusions . Wit hexemptions , Stag e I I wil l contro l abou t 8 0 percen t o f refuelin g emission s i nth e area s wher e i t i s installed . Thi s contro l wil l largel yb e i nplac e befor e ORVR control s begi nan d wil l b e effectiv e o nmos t gasoline-powere d highwa yvehicles . ORVRcontrol s ar e expecte d t o provid e emission s contro l a t a leve l o f abou t 9 5 percen t i n ozon e N Aareas . I f installe d o n al l vehicl e classe s i t wil l cove r essentiall yal l o f th e consumptio n Stag e I I woul d contro l an d th e extr a emission s contro l i nth e lon g ter mwoul d b e abou t 1 5 percentag e point s i nthes e areas . Eve n a modes t decreas e i nth e scop e o f th e ORVRprogra mo r a decreas e i n syste m efficienc ywoul d no t affec t th e conclusio ntha t ORVRcontrol s woul d provid e grate r emissio n reduction s tha nStag e I I i nth e lon g term . However , i f ORVRcontrol s ar e no t applie d t o LDT s / HDV s th e reductio no f benefit s woul d b e dramatic , sinc e togethe r the y compris e abou t 4 0 percen t o f refuelin g emissions . Th e benefit s o f LDT/HD V

control s incrementa l t o Stag e I I ar e i nth e sam e 1 5 percen t rang e i narea s wher e Stag e I I i s installed , bu t substantiall y greate r i nth e ozon e NAA s wher e ther e i s n o Stag e II . However , i narea s wher e Stag e I I i s installed , th e benefit s o f a ful l ORVRprogra m woul d no t excee d Stag e I I unti l abou t 2010 . A t tha t point , i t woul d b e appropriat e t o conside r Stag e I I phase-ou t sinc e ther e woul d b e fe wbenefits , an d th e cos t effectivenes s o f thos e benefit s woul d b e ver yunattractive . EPA ' RI Acontain s a ful l discussio no f th e costs , emissio n reductions , cos t effectiveness , an d benefit-cos t rati o o f LDT/HD V ORVRcontrol s incrementa l t o Stag e I I an d compare s i t t o retainin g Stag e I I solel yfo r controllin g LDT/HD V

refuelin g emissions . A s ca nb e see ni ntha t analysi s th e ORVRoptio ni s superio r i nth e lon g term .