# OAR Box 1818 Prepped by Ollie Stewart p. 1



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Number: 

# 62 ) ll-F- 4 Docket Number: 

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Printed 11/6/2008 3:12:45PM

Sheet 62 of 79P. 2 

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, D.C . 2046 0



### JU L8 198

7 omcEO F AI R AN D RADIATIO N

NOT E TO AR T FRAAS , OMB

Enclose d ar e additiona l write-up s for th e Refueling an

d Volatilit ypreamble s a s w e discussed . I believ e the point s addres s the concern s OMB ha s raised . A s I mentioned , Le e Thoma s woul d ver ymuc hlik e t o hav e thes e package s publishe d befor e h e testifie s t o the Senat e on Jul y22 . Pleas e cal l me i f yo u have an yquestions .

Ri-dnaF d Wilso n Director , Offic e o f Mobil e Source s Enclosure sP. 3

•*' ' OMBOflR D PRE/M B L E(I0SER. T

• « T o be inserte d following Onboar d decisio n rational e

presentation :

III . KeyAnalytica l Issue s Affecting EPA' s Decisio n

The above discussio n ha s attempte d t o full yse t fort h th e analyse s an

d interpretation s used b yEP Ain arriving a t it s decisio n t o propos e th e onboar d contro l progra m containe d in today' s notice . Th e Agenc yha s expende d considerabl e effor t i n it s analyse s an

d i s convince d tha t i t ha s fairl yconsidere d th e man yissue s an

d uncertaintie s involved . A t th

e sam e time , EP

Ai s cognizan t tha t ther e i s disagreemen t regarding th e refueling contro l issue an d i s desirou s o f obtaining the fulles t degre e o f publi c participatio n i n th e rulemaking process . T o assis t commenters , thi s sectio n wil l agai n revie wth e mai n option s considere d b

ythe Agenc yan

d the n presen t a discussio n o f th e analytica l issue s whic h ma ybe mos t importan t i n affecting th

e outcome o f EPA' s fina l decision .

A . Option s

EPA' s firs t decisio n concerning refueling wa s t o choos e betwee n controlling o r no t controlling refueling emissions . A s describe d earlie r i n thi s preamble , th e Agenc ybelieve s tha t contro l i s appropriate . RefuelingP. 4

contro l i s importan t for reducing th e generatio n o f ozon e pre-cursor s in non-attainmen t areas . In addition , today' s proposa l wil l provid e additiona l benefit s in term s o f cance r incidenc e reduction s an d in term s o f ozon e reduction s i n attainmen t areas . Give n th

e need for refueling control , Agenc yanalyse s indicat e tha t bot h onboard an d Stag e I I ar e cos t effectiv e approaches . Thus , th e secon d deciso n facin

g th e Agenc ywa s betwee n competing technologie s for control . A s alread y indicated , th

e onboard contro l approac hha s bee n selecte d for proposal . Stag e I I ha s a potentia l advantag e i n term s o f tota l cos t becaus e i t coul d be applie d selectivel yi n non-attainmen t area s only . I t als o ha s the potentia l fo r implementatio n i n th e shortes t overal l leadtime (althoug h tha t advantag e i s no t completel yclear ) . However , onboard' s greate r tota l cos t arise s largel yfro mit s nationwid e character , whic h bring s substantiall ygreate r overal l benefit s than Stag e I I (maintainin g a comparabl e cos t effectiveness ) . Thus , eve n i f onboar d require d somewha t greate r implementatio n time than Stag e II, , i t woul d be preferabl e i n th e lon g run . Give n th

e decisio n t o propos e onboard controls , the optio n t o propos e Stag e I I contro l fo r the shor t ter m wa s considered . Thi s approac hcoul d provid e emissio nP. 5

reduction s i n the shor t ter mwhil e newcar s wit h onboard control s wer e bein g phase d int o the fleet . However , the realizatio n o f thes e shor t ter mbenefit s i s unclear , becaus e o f uncertaint yove r the timetabl e fo r implementing Stag e II . Theywoul d als o b e substantiall ymor e costl ythan the benefit s o f eithe r onboard o r Stag e I I alon e sinc e the y woul d be shor t ter m benefit s an

d incrementa l t o onboard . Thus , a s descibe d earlie r in Sectio n II , EPAbelieve s tha t decision s abou t th e us e o f Stag e I I in the shor t ter m shoul d b

e include d i

n the Stat e Implementatio n Plan developmen t process .

B . Analytica l Issue s

Th e decisio n betwee n onboard an d Stag e I I ha s relie d upon a n extensiv e bod

yo f analysi s whic hha s bee n conducte d ove r a severa l yea r period . Thes e analyse s ar e quit e comple x an

d b ythei r natur e involve a grea t numbe r o f projections , judgement s an d assumptions . Som e o f thes e area s ar e generall yagree d upon , whil e other s ar e not . I n addition , some matter s have mor e impac t o n the outcome o f th e analyse s than others . Th e following section s revie w assumption s whic har e eithe r controversia l or know n b yEPA t o have a significan t impac t o n it s analyses . • Theyar e bein g describe d her e for the purpos e o f invitin g publi c scrutin yan d comment .P. 6

Th e Agenc ywishe s t o cautio n commenter s however , tha t i t i s quit e possibl e tha t importan t analytica l issue s exis t whic har e no t identifie d below . ' fflPVMMIiHnBafl l

Ife Thus , the Agenc y encourage s al l partie s t o carefull yreviewal l o f it s analyse s an

d no t t o confin e comment s solel yt o issue s raised below .

1 . Fue l Volatilit y

Th e impac t o f fue l volatilit yo n the analysi s o f refueling control s wil l be reviewe d furthe r i n Sectio n V , therefor e i t wil l no t b e describe d in dept h here . A s noted , th

e analyse s describe d i n today' s proposa l have bee n conducte d unde r th e assumptio n o f in-us e fuel s bein g a t curren t ASTM limit s (11. 5 RV P for summertime month s i n Clas s C areas ) . Thes e condition s pos e the mos t difficul t technica l challeng e an d greates t cos t t o manufacturers . I f th e Agenc yfinalize s it s propose d reductio n o f fue l volatilit yt o 9. 0 RV P fo r Clas s C areas , the n manufacture r cost s woul d declin e whil e cos t effectivenes s value s woul d increase . A s describe d above , the cos t effectivenes s o f onboar d control s woul d increas e abou t 2 2 percen t whil e Stage-I I woul d increas e abou t 1 3 percent .



# 4P. 7

Th e singl e bes t volatilit yasssumptio n t o us e i s difficul t t o determin e a t thi s point , sinc e EPAha s no t ye t finalize d it s volatilit yregulation . Th e presentatio n in * today' s notic e indicate s tha t EP Awoul d expec t t o procee d wit honboar d control s regardles s o f whethe r o r no t volatilit yi s controlle d t o the level s proposed . At the sam e time , interaction s betwee n the tw o proposal s dictat e tha t th

e questio n o f fue l volatilit ybe resolve d befor e fina l actio n o n refueling . Thus , a t th e tim e o f fina l rulemaking , EP

Aintend s t o presen t it s refueling analyse s unde r the volatilit ycondition s bein g promulgate d a t tha t time . I n th

e meanwhile , commenter s ar e requeste d t o conside r the effec t o f varying fue l volatilit yin thei r comment s o n thi s proposal .

2 . Numbe r o f Non-Attainmen t Area s

Base d upo n 198 2 throug h 198 4 (th

e lates t dat a fo r whic hmodeling i s completed) , ther e ar e currentl y6 1 urba n non-attainmen t area s outsid e o f California . I n valuing ozon e reductions , EPAha s credite d reduction s in al l 6 1 o f thes e area s a s contributing t o solutio n o f the non-attainmen t problem . However , th e projection s o f futur e condition s used in analyzing the effect s o f contro l sho w tha t th

e numbe r o f non-attainmen t area s ma ydro p significantl yi n th e mid-1990s . Fo r example , th e analysi s



## 5 "P. 8

supporting the volatilit yproposa l indicate s tha t ther e ma y b e a s fewa s 2 9 non-attainmen t area s in 199 5 wit hth e adoptio n o f bot h volatilit ycontro l an d onboard controls.[1 ] Thus , i t migh t be argue d tha t ozon e reduction s shoul d b e counte d in a s fe

wa s abou t 3 0 areas .

Ther e ar e severa l importan t reason s wh yth e Agenc yha s no t followe d th

e above approac hin it s analyses . First , the same projection s whic hindicat e a declin e i n the numbe r on non-attainmen t area s t o 2 9 als o predic t an increas e t o 3 9 agai n b

ythe yea r 2010 , the perio d whe n onboar d control s wil l be full yphase d i n an d come t o thei r maximu mleve l o f control . Thus , a t leas t 4 0 area s mus t be used . Second , an d mor e importantly , a close r look a t th e modeling result s indicate s tha t almos t non e o f th e modele d area s eve r gai n a substantia l margi n o f complianc e agains t th e ozon e ai r

[1 ] Th e volatilit yai r qualit yanalysis , whic hi s mor e recen t than th

e onboar d analysis , i s base d upo n somewha t differen t assumption s concerning the futur e o f stationarysourc e controls . Ther e i s considerabl e uncertaint yabou t howmuc h newVO C contro l i s availabl e fro

m stationarysource s fo r the future . Th e onboar d analysi s assume s n o additiona l stationary sourc e controls , whil e the volatilit yanalysi s include s som

e moderat e gains . Fo r th e same conditions , thi s cause s th e onboar d analysi s t o predic t 4 t o 8 mor e non-attainmen t area s than the volatilit yanalysis . EP Ai s unsur e whic ho f thes e approache s i s th

e mor e accurate . Fo r thi s discussion , the lowe r number s fro mth e volatilit yanalysi s ar e bein g used .P. 9

qualit ystandard . Fo r example , eve n assuming volatilit y contro l t o 9 RV

P an d the adoptio n o f onboard controls , 5 8 o f the 6 1 area s modele d remai n a t o r above 0.1 1 pp mozon e throughou t th

e perio d o f analysis . Thi s represent s onl y abou t a 1 2 percen t margi n belowthe 0.1 2 pp mstandard . Suc hlevel s ar e wel l withi n th e uncertaint yo f EPA' s models , whic hhave historically , tende d t o overpredic t reductions.[2 ] Thus , EPAbelieve s tha t reduction s in al l th e modele d area s have valu e i n controlling non-attainmen t conditions . I t i s als o wort hnotin g tha t the ambien t ai r qualit ystandard for ozon e i s currentl yunde r reviewb yth e Agency , wit hthe consequen t possibilit ytha t the standard migh t b

e lowere d fro

mit s presen t level . I f thi s wer e t o happen , ther e woul d als o b e an increas e in th e numbe r o f non-attainmen t areas .

[2 ] The Agenc yha s consistentl ystresse d th e need for cautio n in interpreting modeling result s o f thi s sort . Yea r t o yea r meteorologyvariation s ca n rapidl y chang e the numbe r o f non-attainmen t area s whe n s o man y area s li e ver

yclos e t o th

e standard . On e indicatio n o f thi s effec t i s foun d in recen t dat a estimating th e numbe r o f non-attainmen t areas . Base d upo n 198 3 throug h198 5 data , th

e numbe r o f non-attainmen t area s appear s t o have increase d fro m6 1 t o 6 5 whil e modelinc woul d predic t som

e declin eP.1 0

Ther e i s anothe r reaso n arguing for considering a n eve n large r numbe r o f area s than th e 6 1 whic hEP

Aha s identified . Ozon e i s a broad regiona l phenomena , no t confine d withi n th e specifi c geographi c boundarie s o f non-attainmen t areas . Th e transpor t o f ozon e formin g precursor s int o non-attainmen t area s fro madjacen t attainmen t area s i s a significan t contributo r t o non-attainmen t problems . Thus , emission s in area s adjacen t t o th e 6 1 non-attainmen t area s shoul d als o b e value d for attainmen t o f the standard (th e inheren t abilit yo f onboar d t o contro l suchemission s i s on e o f th e advantage s o f thi s technology ) . EP

Ai s no t i n a positio n a t thi s tim e t o quantif ythi s ovelap , bu t believe s i t coul d be substantial . Comment s on estimating thi s effec t woul d b e helpful . Examinatio n o f a fewdifferen t assumption s abou t th e numbe r o f non-attainmen t area s t o us e indicate s tha t the sensitivit yo f onboar d cos t effectivenes s t o thi s paramete r i s smal l fo r mos t combination s (Tabl e 7 ) . Fo r example , Tabl e 7 indicate s tha t decreasing th e numbe r o f area s fro m 6 1 t o 5 0 increase s the cos t effectivnes s o f onboar d control s b

y9 t o 1 3 percen t (dependin g upo n whic hset s o f benefit s ar e bein

g valued , se e Tabl e 6 ) . Using 4 0 area s represent s a 1 9 t o 2 7 percen t increase . (I t shoul d be note d tha t i f al l ga s vapo r relate d incidence s ar e



# 8P.1 1

credited , the non-attainmen t are a VO C cos t effectivenes s remain s negativ e for al l selecte d set s o f non-attainmen t areas. )

Increasing th

e numbe r o f non-attainmen t area s ha s a simila r effect . Here , becaus e th e exac t identificatio n o f adjacen t area s whic hmigh t be directl yinvolve d i n transpor t i s difficult , EP Alack s a specifi c se t o f area s t o include . I n th e alternative , a n increas e i n the fractio n o f fue l assume d consume d i n non-attainmen t area s (whichidentifie s benefit s t o be counted ) ha s bee n used . The curren t 6 1 area s represen t 3 5 percen t o f nationwid e fue l Consumption . Assuming an increas e i n the amoun t o f controlle d fue l t o 5 0 percen t woul d improv e th e cos t effectivenes s o f onboar d b y2 0 t o 3 0 percent . 3 . Valu e o f Healt h Benefit s an d Attainmen t Are a Ozon e Reduction s Closel yrelate d t o the questio n o f howman y non-attainmen t area s t o us e i s the questio n o f the valu e o f th e benefit s o f reducin g cance r incidence s an d the ozon e reduction s fro

m attainmen t areas . Lacking clearl ydefine d value s fo r thes e factors , EPA' s analysi s examine d the overal l cos t effectivenes s o f onboar d assuming value s o f $7.5M M pe r incidenc e avoide d (fo r variou s assume d incidenc e levels ) an

d $25 0 pe r ton o f VO C reductio n i n attainmen t area s (whic e EPAbelieve s i s conservative) . T o illustrat eP.1 2

th e effec t o f changing th e assume d values , some alternat e value s hav e bee n considered . Th e cos t pe r incidenc e avoide d (assumin

g onl ybenzen e plu s C 6 an d abov e gasolin e vapo r incidences ) ha s bee n assume d t o rang e fro m$3.5M M pe r incidenc e avoide d t o a s hig h a s $10MM . Fo r attainmen t are a benefits , a valu e o f $50 0 pe r ton ha s been used in additio n t o $25 0 pe r ton . Tabl e 8 present s th e result s of : thi s sensitivit y analysis . Fro

mTabl e 8 , i t can b e see n tha t th

e overal l attainmen t are a VO C cos t effectivenes s o f onboar d range s fro ma lowo f $15 0 pe r ton fo r th e maximu

mvaluatio n o f al l benefit s u

p t o a s hig

h a s $220 0 pe r ton i f no valu e i s assigne d t o eithe r attainmen t are a VO C reduction s o r incidenc e reductions . Tabl e 8 doe s no t includ e th e cas e wher e incidence s attributabl e t o includin g al l gasolin e vapor s ar e valued . Theyhav e bee n omitte d fro mth e tabl e t o indicat e th e cost-effectiv e natur e o f onboar d control s eve n i f thi s mor e controversia l sourc e o f incidence s i s excluded . I f al l ga s vapor s wer e included , the cos t effectivenes s o f VO C contro l i n non-attainmen t area s woul d remai n negativ e for mos t o f th e case s give n i n Tabl e 8 .



### -**- i o4 . In-us e Efficienc yo f Onboar d Control s

Ther e ar e thre e factor s affecting th e averag e in-us e efficiencyo f onboard systems : the theoretica l efficiency , th e rat e o f tampering wit h in-us e system s an d th e rat e o f malmaintenanc e an

d defect s fo r in-us e systems . Fo r al l o f thes e areas , th

e Agenc yha s ha

d t o deriv e appropriat e value s t o us e base d upo n indirec t data , sinc e onboar d system s ar e no t ye t in routin e production . Sinc e th e overal l contro l efficienc ydirectl yaffect s emissio n reduction s t o be gained , EPA' s approac h t o thes e area s i s important . Th e theoretica l efficienc yused for EPA' s analysi s correspond s t o a 9 7 percen t reductio n o f uncontrolle d emissions . B

ycomparison , th e reduction s require d t o attai n the standard o f today' s proposa l ar e abou t 9 9 percent . Th e reaso n fo r the differenc e i n value s come s fro mthe fac t tha t th e basi c analysi s o f onboar d impact s wa s conducte d base d upo n earlie r estimate s o f onboar d contro l efficienc ythan tha t eventuall yembodie d in the propose d standard . Th e impact s analyse s have no t bee n update d t o reflec t thi s mor e recen t assessment , largel y becaus e th

e impac t i s smal l an d becaus e an

yerro r ca n be considere d conservativ e (i.e. , underestimating benefit s rathe r than overestimating them) . Arevise d analysi s woul d reflec t abou t a tw o percen t improvemen t i n cos t



## / IP. M

effectivenes s du e t o the inclusio n o f thi s change . EPA.' s analysi s fo r it s fina l rul e wil l reflec t th e efficienc yo f th e standard adopted . Tampering rate s for onboar d system s wer e derive d fro m EPA' s experienc e wit h evaporativ e controls . Thos e component s o f onboard system s directl yaccessibl e t o th e operato r (vapo r lines , purg e lines , canisters , etc. ) ar e essentiall yth

e sam e a s component s o n curren t evaporativ e controls . Thus , EP Aassume d tha t tampering wit hthes e component s woul d occur a t th e same rat e a s currentl yoccur s on evaporativ e systems . Thi s tampering rate , on a flee t weighte d averag e basis , amount s t o 2. 8 percent . Assuming tha t tampere d system s ar e completel ydisabled , ther e i s a corresponding 2. 8 percen t los s i n averag e contro l efficiency .

EPA' s analysi s ha s bee n conducte d base d upo n the assumption s a s jus t described . However , ther e i s reaso n t o believ e tha t thes e assumption s ar e overl yconservative . Recen t indication s fro m som e manufacturer s indicat e tha t onboar d canisters , in a t leas t som e applications , wil l b e les s accessibl e than evaporativ e canisters . Tha t is , some manufacturer s have indicate d tha t the yma ylocat e refueling canister s in underbod ylocation s o r toward the rea r o f the vehicle . Th e degre e t o whic h thi s wil l occur i s currentl y unclear . However , i f suchapproache s ar e used , the ywil lP.1 5

likel yreduc e the degre e o f tampering whic hoccurs . Thi s effec t ha s no t bee n estimated , an d comment s o n th e appropriat e approac ht o thi s questio n woul d be valuable . Th e third facto r affecting in-us e efficienc y identifie d abov e i s th e effec t o f malmaintenanc e an d defect s (M&D ) o n emissions . A s fo r tampering rates , EP A ha s relie d o n experienc e wit h evaporativ e system s t o estimat e th

e effec t o f M& D o n onboard systems . However , th e translatio n o f M& D effect s fro mevaporativ e system s t o onboard system s i s mor e problemati c tha n tampering , a s wil l b e describe d below .

In it s approach , EPAexamine d M& D dat a fo r evaporativ e system s t o identif yproblem s whic har e commo n t o onboar d systems . Fo r example , problem s sucha s missing ga s cap s or damage d ai r cleane r gasket s wil l caus e exces s evaporativ e emission s t o occur , bu t wil l no t alte r the performanc e o f onboar d systems . Thes e wer e therefor e exclude d fro mthe onboar d analysis . Afte r thes e exclusions , 7. 9 percen t o f the vehicle s wer e foun d t o hav e M& D problems . Next , using tes t dat a gathere d usin g commercia l (hig h RVP ) fuel , th

e evaporativ e emission s o f thes e problemvehicle s wer e compare d t o th

e emission s o f problemfre e vehicles . Whe n weighte d int o the flee t average , thi s compariso n indicate d a 10. 9 percen t increas e i n evaporativ e emission s wa s occurring du e t o relevan t M& D problem s whe n teste d o n 

## & 1 3P.1 6

commercia l fuel . EP Athe n applie d thi s percen t increas e t o onboard emissions , an d relate d thi s amoun t t o a n equivalen t los s in contro l efficiency . Tha t is , the M& D problem s woul d increas e emission s fro monboard equippe d car s fro m approximatel y0.17 7 gram s pe r gallo n t o 0.19 6 gram s pe r gallo n (compared t o uncontrolle d rate s o f abou t 5. 9 gram s pe r gallon) . Thi s increas e in emissio n corresponde d t o a chang e in contro l efficienc yfro m 9 7 percen t t o 96. 7 percent . Being s o small , the M& D impac t wa s considere d negligibl e an

d no t considere d furthe r i n the analyses .

A n alternativ e approac ht o evaluating M& D impact s ha s bee n advance d whic hindicate s a greate r possibl e effect . Unde r thi s alternativ e approach , rathe r than computing a proportiona l increas e i n emissions , M& D vehicle s ar e evaluate d for a

n indicate d los s i n overal l evaporativ e contro l efficiency , an d thi s los s i s applie d directl yt o th e corresponding onboar d contro l efficiency . Operating o n th e mos t curren t M& D dat a for M& D problemrate s an d emissio n impact s o n commercia l fuel , thi s approac hha s bee n argue d t o produc e a los s in efficienc yo f thre e t o four percent . However , ther e ar e severa l consideration s whic h mus t be addresse d befor e a reasonabl e estimat e ca n be determine d usin

g thi s approach .

Th e viabilit yo f usin g a direc t transfe r o f efficienc y effect s depend s upon establishing equivalen t condition s fo r



## ^ 1 4evaluating impact s fo r th e two technologies . Firs t i s the need t o evaluat e th e effec t o f M& D impact s o n evaporativ e system s unde r condition s thes e system s wer e designe d t o manage . Thi s mean s tha t th e M& D impact s mus t be evaluate d wit h9 RV

P fuel . Eve n problemfre e vehicle s have exces s emission s whe n teste d o n commercia l fuel , becaus e th e evaporativ e control s ar e operating beyon d thei r design capacity . Thus , a smal l disablemen t migh t . increas e emission s o n commercia l fue l bu t have n o impac t wit h 9 RV P fuel . Sinc e onboard control s wil l b e designe d t o properl y operat e o n whateve r commercia l fue l i s eventuall y establishe d throughEPA' s volatilit yproposal , design fue l mus t b e used t o evaluat e evaporativ e emissio n effects . Whe n result s on 9 RV P fue l ar e considered , th e impac t o f M& D problem s on evaporativ e emission s i s different . Th e numbe r o f vehicle s whic hca n be considere d t o have M& D problem s i s reduce d becaus e som e o f the proble mvehicle s mee t th

e evaporativ e standard whe n teste d o n 9 RVP fuel . Th e absolut e amoun t o f exces s emission s i s als o greatl y decreased . However , emission s fro m problemfre e vehicle s declin e eve n furthe r and , expresse d a s a percentag e change , M& D problem s have a greate r effec t a t 9 • RV P than a t 11.5 , increasing averag e emission s b y3 0 percen t (comparabl e t o th e 10. 9 percen t valu e give n above) . Using EPA' s origina l methodology , thi s woul d mea n a reductio n o f onboar d contro l efficienc yt o 96. 3 percent . 

### #3

- \\fP.1 8

T o appl ythi s dat a t o an estimate d los s o f contro l efficiency , the emissio n level s o f the M& D vehicle s on 9 RVP fue l wer e compare d t o expecte d uncontrolle d levels . Expresse d o n thi s basis , the M& D vehicle s experience d a los s o f contro l o f abou t 3 5 percent . Average d ove r th e flee t thi s amount s t o abou t a 2. 5 percen t los s o f efficienc yan

d change s th

e onboard contro l efficienc yt o 94. 5 percent . Thi s valu e represent s a n estimat e o f the maximu m impac t M& D problem s coul d have on onboar d systems . However , th

e actua l impac t i s likel yt o b e muc h less . Fo r example , 4 5 percen t o f the M& D problem s wer e the resul t o f clogge d o r dirt yfilter s o n the evaporativ e canister . EPA expect s tha t most , i f no t all , onboar d system s wil l us e close d bottomcanister s whic h d o no t have suc h filters . Furthermore , ther e i s a n essentia l differenc e betwee n how manufacturer s wil l approac h the design o f onboar d system s compare d t o evaporativ e system s whic hi s impose d b yth e propose d tes t procedure . Th e evaporativ e procedur e test s system s unde r nea r averag e condition s whil e th e onboar d procedur e use s a near "wors t case " se t o f conditions . Thi s differenc e wil l resul t in onboar d system s whic hhav e a substantia l degre e o f exces s capacit yfor averag e conditions . Thus , partia l disablement s a s represente d b y th e M& D problem s on evaporativ e system s wil l have littl e or no impac t o n refuelin g emission s unde r mos t conditions . I n



## \lP.1 9

fact , EP

Abelieve s i t quit e reasonabl e t o assume tha t currentl yknow

n M& D problem s wil l no t noticeabl yaffec t onboard 'emissions , whic h wa s the resul t o f EPA' s origina l approac ht o estimating th e effec t o f thi s problem . Ther e i s actuall ya potentia l benefi t o f onboard control s relate d t o M& D problem s whic hha s ye t t o be quantified . Thi s benefi t i s tin e likel yelimination , o f evaporativ e exces s emission s cause d b yM& D problems . Give n th e exces s capacit yt o b e designe d int o onboar d systems , an d give n the fac t tha t for mos t o f it s driving mile s the onboar d caniste r wil l b e in a highl ypurge d condition , onboar d system s wil l have the abilit yt o absorb M& D effect s withou t an

ycorresponding los s o f evaporativ e emission s control . Thi s mean s tha t onboar d system s coul d captur e exces s evaporativ e emission s whic h ar e no t expecte d t o be eliminate d b

ythe propose d control s o f fue l volatilit yo r othe r change s t o the evaporativ e emissio n tes t procedur e bein g considere d t o mak e i t mor e effective .

Ther e ar e othe r condition s beside s M& D problem s whic h ar e currentl ybelieve d t o caus e exces s evaporativ e emission s whic hwil l als o b e affecte d by

- onboar d controls . I n general , the

yconsis t o f thos e condition s whic hresul t i n cumulativ e evaporativ e emission s whic h wil l excee d the capacit yo f eve n a wel l designe d system . Thi s woul d includ e suc hthing s a s vehicle s whic har e no t drive n



## '** 

## 1 7P.2 0

regularl yan

d underg o repeate d diurna l emissio n load s withou t adequat e opportunit yt o purg e th e canister . A

n onboard caniste r woul d be abl e t o absorb severa l diurnal s befor e emission s breakthroughwoul d occur . Asimila r situatio n woul d occur for vehicle s drive n on mostl yshor t trips , agai n allowing insufficien t opportunit yfor th e evaporativ e system t o purge . A

n onboard syste

mwoul d be muc hmor e toleran t o f suc hdeviation s than woul d curren t evaporativ e systems . Th e Agenc yha s no quantitativ e estimat e o f thi s benefi t a t present , bu t believe s i t coul d b e significant . The questio n o f th e appropriat e leve l o f in-us e efficienc yt o us e for analysi s o f onboar d system s i s an importan t matter . Th e Agenc ytherefor e request s commen t directe d a t thi s issue , especiall ydealing wit hthe point s discusse d above . An yassistanc e fro mcommenter s i n quantifying thes e impact s woul d b e mos t helpful . 5 . Fue l RecoveryCredit s fo r Onboar d

The ne t cos t fo r onboar d o r Stag e I I system s include s a credi t for th

e fue l valu e o f recovere d vapors . Fo r onboar d thi s credi t i s partiall yoffse t b ythe ' impac t o f the adde d weigh t o f th e onboar d hardwar e o n the fue l econom yo f affecte d vehicles . Some manufacturer s hav e argue d tha t whe n the adde d weigh t o f the onboar d hardwar e 

## •4? i yP.2 1

i s incorporate d int o newvehicl e design s ther e wil l b e a n adde d weigh t increas e through the effec t o f the onboard componen t weight s o n the design o f othe r vehicl e system s (e.g. , fram

e members , springs , engin e an d driv e trai n components , etc.) .

Fo r everypoun

d increas e in payload , thi s argumen t goes , ther e wil l b e a n additiona l 0. 7 pound s adde d t o th e res t o f th

e vehicle . Thus , the impac t o f the onboar d weigh t mus t be increase d b ya facto r o f 1. 7 befor e computing it s effec t o n fue l consumption . Manufacturer s have als o argue d tha t the fue l econom ysensitivit yo f newl y designe d vehicle s t o change s in weigh t wil l b e greate r than tha t assume d b

yEPAbecaus e the engin e displacemen t woul d b e adjuste d t o maintai n a constan t driving performanc e characteristic . I n addition , additiona l cos t mus t be associate d wit hthi s adde d weigh t an d counte d a s par t o f th e onboar d contro l cost .

EPA' s curren t analysi s assume s tha t the onboard hardwar e o n futur e vehicle s wil l no t impac t th e weigh t o f an yothe r part s o f newvehicles . I t i s appropriat e in som e context s t o relat e overal l vehicl e weigh t t o "payload " weight , sinc e the desig n o f frames , springs , etc. , i s clearl ydetermine d b ythe require d payload . However , i n the rang e o f fou

r t o five pound s o f ne t weigh t chang e a s involve d here , the vehicl e platfor m desig n shoul d no t be 

# t* 

# I?sensitiv e t o suchsmal l changes . Thi s i s a chang e

comparabl e t o th

e weigh t o f a se t o f floo r mats . Ther e ar e undoubtedl ychange s o f greate r magnitud e than thi s mad e t o newvehicl e component s a s the vehicl e design evolves , an d EP Adoe s no t believe i t i s reasonabl e t o argu e tha t change s ar e mad e in , for example , howbi g th e spring s wil l b

e eac h tim e thi s happens . Indeed , thi s valu e undoubtedl yfall s wel l withi n th

e rang e o f norma l design toleranc e an d eve n rando mvehicl e t o vehicl e weigh t variability . Th e allocatio n o f tota l vehicl e weigh t t o payloa d ite mweight s in thi s rang e i s mor e an accounting techniqu e than a reflectio n o f actua l effects . Whil e EP

Adoe s no t necessaril yfee l tha t th e weigh t multiplicatio n argumen t i s appropriat e i n the onboar d situatio n becaus e o f the smal l weigh t change s involved , i t ha s don e a sensitivit yanalysi s t o asses s the impac t o f suc ha n assumption . Thi s analysi s ha s bee n don e usin g a weigh t multiplying facto r o f 1. 3 instead o f the 1. 7 valu e advance d b

ysome manufacturers . Th e 1. 7 valu e ha s bee n develope d b

yNHTSAi n connectio n wit h th e developmen t o f bumpe r standards , an d used for weigh t change s generall y twic e o r mor e thos e bein g considere d here . Th e rang e o f possibl e value s for thi s paramete r according t o th e NHTS A analysi s wa s fro

m 1. 3 t o 2.0 . Give n the minima l weigh t chang e involved , EP Aha s selecte d 1. 3 fo r it s sensitivit y analysis . Arecen t industr ysponsore d analysi s b y 

### ZOP.2 3

Multinationa l Busines s Service s ha s used a valu e o f 1. 4 fo r thi s factor . I n addition , an yeffec t fo

r light-dut ytruck s or heavy-dut yvehicle s woul d b e lowe r than for passenge r cars , becaus e truc k design i s mor e heavil ydetermine d b y carg o weigh t requirements .

EPAha s mad e no adjustmen t t o th e sensitivit yfacto r fo r fue l econom

yversu s weigh t change . The change s involve d ar e simpl yto o smal l t o be reasonabl yabl e t o impac t engin e design . Fo r example , th e chang e in 0 t o 6 0 mile s pe r hour acceleratio n tim e associate d wit hthe weigh t o f onboar d control s woul d amoun t t o a n acceleratio n los s o f som e 0.0 3 seconds . Suc ha smal l chang e woul d no t eve n be detectable . EP

Afind s littl e basi s t o assume tha t suc h smal l impact s woul d actuall yeffec t engin e desig n decisions .

I n determining a cos t valu e t o assign t o the adde d weigh t th

e Agenc ybegan wit hrepresentativ e cost s fo r stee l purchase d b

yth e automobil e industr y(20jz5/lb ) , assume d 10 0 percen t i n valu e adde d an d 2 6 percen t fo r overhea d an d profi t t o arriv e a t a valu e o f 50 ^ pe r pound . Sinc e the effec t i s bein

g assume d t o onl yaffec t newl ydesigne d vehicles , a phase-i n schedul e wa s develope d assuming a two yea r lag following implementatio n o f th e newstandards , an d a flee t turn-ove r o f six year s following that .



# uP.2 4

Base d upo n the abov e assumptions , EP Aestimate s tha t th e overal l cos t o f onboar d control s on newl ydesigne d vehicles " woul d increas e b yabou t 1 0 percen t ($1.40) . Th e flee t averag e impac t considering th e phase-i n schedul e woul d b e t o increas e the overal l onboard cos t effectivenes s b yabou t 5. 5 percent .

Ther e i s anothe r facto r i n th e calculatio n o f fue l recover ycredit s whic h directl yaffect s thei r overal l value . Tha t i s th e assume d pric e for a gallo n o f gasoline . Th e valu e used in EPA' s curren t analysi s i s $1.20 , whic hrelate s approximatel yt o a crud e oi l pric e o f $3 0 pe r barrel . Some forecast s o f futur e crud e oi l price s indicat e cost s risin g above th

e $3 0 pe r barre l level . Base d upon an increas e i n the crud e oi l pric e t o $3 3 pe r barrel , ther e woul d be a 6-z ? pe r gallo n increas e in the cos t o f gasoline . I f such an increas e i s applie d t o th e fue l recoverycredit s fo r onboard , ther e i s a ne t reductio n in th e onboar d cos t effectivenes s o f abou t 3 percent . I n a simila r fashion , a 6-z f pe r gallo n increas e in fue l cos t woul d improv e stag e I I cos t effectivenes s abou t 3 percent .

6 . Contro l o f Spillag e Emission s

On e sourc e o f gasolin e vapo r emission s associate d wit h refueling operation s i s th e spillag e o f fuel . Wha t migh t generall ybe considere d spillag e ca n come fro msevera l 

### 22

-causes . Spitbac k spillag e ca n occur whe n fue l i s

discharge d fro

mth e fillpip e du e t o exces s pressur e buildu p i n the fue l tan

k vapo r space . Thi s can happe n nea r th e en d o f a fillu

p a s th

e tan k i s nearl yfull . I t ca n als o occur earlie r whe n in-us e fue l dispensing rate s excee d th e rate s tha t th

e fillpip e an

d fue l tan

k ar e abl e t o accept . Overflo wspillag e can als o occu r fro mth e operator' s attemp t t o "to

p off " th

e fue l tan

k following automati c nozzl e shutoff , o r i f th e nozzl e malfunction s an d fail s t o shu t off . Take n a s a whol e spillag e emission s have bee n estimate d t o represen t abou t 5 percen t o f tota l refueling emission s an

d hav e bee n considere d unchange d b yeithe r onboard o r Stag e I I controls . Althoughno t ye t considered , bot h onboar d an d Stag e I I equipmen t ar e likel yt o affec t spillage . The onboar d tes t procedur e requirement s wil l requir e vehicle s t o b e abl e t o refue l a t the maximu min-us e dispensing rate , thu s eliminating spitback . Finally , give n th e improve d fillabilit ythi s represents , i t i s likel ytha t reduce d toppin g of f operation s wil l occur . Stag e I I equipmen t wil l no t directl ybring abou t the eliminatio n o f spillag e sources . However , sinc e th e fue l woul d be containe d withi n th e vapo r collectio n boo t o n the Stag e I I nozzle , spillag e woul d be containe d somewhat . However , sinc e som e o f tha t fue l coul d subsequentl yb eP.2 6

spille d a s the operato r replace d th e nozzl e o n the dispenser , th

e degre e o f possibl e contro l i s difficul t t o estimate . I n addition , sinc e the operato r canno t visuall y observ e th

e refuelin

g operation , attempt s t o to p of f th

e tan k ma ycaus e increase d spillage . Overall , i t appear s tha t onboar d an d Stag e I I wil l hel p reduc e spillage . Onboar d appear s likel yt o contro l spillag e bette r than wil l Stag e II , bu t th e Agenc yha s no t incorporate d thes e benefit s int o it s analysis . Base d upo n the estimate s o f spillag e note d above , withou t an yfue l recover ycredi t fo r the recovere d fue l the tota l contro l o f spillag e coul d improve cos t effectivenes s a s muc ha s 5 percent .

7 . Contro l o f Emptying Losse s

Anothe r componen t o f overal l refueling emisison s i s tha t categoryo f emission s know n a s emptying losses . Thes e emissions , whic h contribut e abou t 5 percen t o f overal l levels , ar e considere d t o be generate d a s par t o f the proces s i n whic hambien t ai r i s draw n int o the gasolin e undergroun

d storag e tan

k t o replac e th

e los t volume o f fue l havin g bee n dispensed . Th e air , a s i t become s saturate d wit hthe gasolin e vapor s i n the undergroun d tank , expand s slightly . Thi s expansio n i s the n presume d t o giv e ris e t o emission s bac k ou t th e undergroun

d tank' s ven t pipe . 

## 2 4P.2 7

Emptying losse s have no t bee n measured , bu t have bee n estimate d base d upo n th e theoretica l consideration s jus t outlined . EPAbelieve s tha t ther e i s reaso n t o believe tha t emptying losse s ma yactuall yb

e eithe r muc hsmalle r than estimate d or essentiall ynon-existent . Th e proces s o f drawing ou t fue l i s relativel yslowcompare d t o th e whol e volume o f th

e undergroun

d tank , an

d i t appear s likel ytha t ai r draw

n int o th

e tan k during th

e earl yportio n o f a refuelin

g even t wil l come int o equilibriu m whil e th

e refueling operatio n i s continuing . I n thi s event , rathe r than causing a

n actua l releas e o f vapo r saturate d air , th e expansio n proces s woul d merel yreduc e the amoun t o f replacemen t ai r neede d t o be draw n in during the late r portion s o f the refuelin g event . Thus , th e onl ylikel y emission s woul d come a t th e ver yen d o f th e refueling event . Beyond this , sinc e refuelin g i s an ongoing proces s wherei n multipl e refueling event s ar e generall yoccuring in overlapping fashion , eve n th e potentia l emptying los s emission s a t th

e en d o f on e refueling even t woul d ten d t o b e eliminate d b

yentrainmen t demand s fro mother , continuing refuelings . Thus , i t appear s tha t emptying losse s may , i n fact , be ver ysmall . I n EPA' s curren t analysis , thes e emission s ar e assume d t o be controlle d b yStag e II , whic hrecirculate s vapo r bac k fro

mthe vehicl e fue l tan k t o the undergroun dP.2 8

tank , eliminating ai r entrainment . Onboard , o n th e othe r hand , i s assume d t o have no effec t on emptying losses . Thus , eliminating the 5 percen t o f emptying los s emission s fro mth e analysi s woul d no t chang e onboard cos t effectiveness , bu t woul d increas e the Stag e I I valu e abou t 5 percent . 8 . Stag e I I Exemptio n Level s an d Inconvenienc e Cost s

Bot h exemptio n level s an d inconvenienc e cost s have bee n discusse d earlie r i n thi s preambl e an d thei r effect s upon Stag e I I performanc e an d cos t effectivenes s described . Th e exemptio n leve l used b yEPAcorrespond s t o approximatel yth

e mos t cos t effectiv e leve l fo r Stag e II . Reducing exemption s woul d increas e the fractio n o f vapor s capture d b

yStag e II , bu t woul d d o s o a t hig h margina l cos t effectiveness . Fo r example , VO C reduction s fro mincluding station s betwee n 2,00 0 an d 10,00 0 gal/mo woul d cos t mor e than nin e time s thos e include d in EPA' s primaryanalysi s an d woul d increas e the averag e cos t effectivenes s o f Stag e I I abou t 5 5 percent . Inconvenienc e cost s have bee n show n t o hav e a dramati c impac t upo n Stag e I I cos t effectivenes s eve n a t a ver ylow valuation . A t onl ylOjz f pe r refueling event , inconvenienc e

UoP.2 9

cost s mor e than tripl e th e Stag e I I cos t effectiveness . Whil e the Agenc ydoe s no t have an exac t estimat e fo r actua l inconvenienc e cost s for Stag e II , th e us e o f Stag e I I system s require s the involvemen t o f th e publi c an

d wil l resul t i n som

e inconvenienc e t o them . 9 . Coordinatio n o f Stag e I I an d EPA' s Undergroun d Storag e Tan

k Progra

m

Th e Agency' s recentl ypropose d Undergroun d Storag e Tan k (UST ) progra

mcoul d potentiall yreduc e th e overal l cos t o f a Stag e I I vapo r recover yprogram . Th e US T progra m i s designe d t o detec t an d replac e or repair , a s needed , leaking storag e tank s tha t caus e groundwate r contamination . I f the installatio n o f Stag e I I control s wer e coordinate d wit hundergroun d tan

k repai r o r replacement , the trenching an d paving cost s associate d wit h Stag e I I vapo r recover yline s potentiall ycoul d b e reduced . Th e Agency' s sensitivit yanalysi s o f a . coordinate d Stag e II/US T progra m i s containe d in Volume 1 o f th e draf t RIA . I n essence , EP Aassume d a five-yea r phase-i n perio d for the coordinate d progra mt o correspond t o th e US T provision s requiring tha t al l undergroun d storag e tan

k system s mus t be teste d for leak s withi n tha t time . Further , i t wa s assume d tha t 3 5 percen t o f the tank s woul d b e foun d leakin

g an d tha t immediat e correctiv e actio n a t



# - ^ 7servic e station s woul d occur a t a relativel ylinea r rat e

ove r th

e five-yea r period . Base d o n thes e principl e assumptions , combining th e Stag e I I progra m wit hth

e US T progra mwoul d improve the cos t effectivenes s o f Stag e I I b y abou t si x percent . Nonetheless , eve n thi s smal l improvemen t ma ybe overl y optimistic . The assumptio n tha t 3 5 percen t o f the undergroun

d storag e tank s wil l need repai r o r replacemen t i s a worst-cas e estimate . Informatio n tha t i s onl y recentl ybecoming availabl e suggest s thi s valu e i s to o high , perhap s b

ya facto r o f three . I f the fina l valu e i s close r t o 1 0 percent , th e resulting improvemen t i n Stag e I I cos t effectivenes s woul d be onl ytwo percent . Thes e result s ar e als o predicate d o n full ycoordinating th e tw o programs . I n reality , i t i s doubtfu l tha t Stag e I I installatio n an

d US T repair s woul d occur simultaneousl yin ever yinstance . Finally , i t i s importan t t o not e tha t a coordinate d Stag e II/US T progra m coul d dela

ythe environmenta l benefit s o f vapo r recover ycontrols . Th e Agency' s "optimum " phase-i n schedul e for Stag e I I i n non-attainmen t area s i s thre e years , bu t a s discusse d above thi s coul d b e extende d t o five year s i f coordinate d wit hthe US T requirements . The n again , eve n thi s latte r phase-i n schedul e assume s tha t leak detectio n an

d correctiv e actio n occu r a t a relativ e



# zSP.3 1

linea r rat e ove r the five-yea r period . Thi s ma ybe unrealistic , becaus e man ytan k owner s ar e likel yt o wai t unti l th

e las t momen t t o conduc t lea k tests . I f thi s i s th e case , a shortag e o f . contractor s t o perform th e necessar

ywork ma

ydevelop , leading t o a delayin correctiv e actio n an d a stretch-ou t o f Stag e I I implementation . The longe r Stag e I I implementatio n takes , th e mor e i t approache s th e onboar d phase-i n schedule , erroding o r eliminating the potentia l short-ter memission s reductio n advantag e o f Stag e II .

C . Summaryo f Sensitivit yIssue s

Th e previou s sectio n ha s reviewe d a numbe r o f issue s affecting onboard an d Stag e I I cos t effectivenes s values , an d attempte d t o identif yth e possibl e impact s associate d wit heach . Mos t o f th e impact s ar e small , excep t for Stag e I I inconvenienc e costs . Some item s improv e cos t effectivenes s an

d som e item s worse n it . Overall , EPA believe s tha t i t ha s fairl yconsidere d thes e matter s i n it s analyse s an

d conclusions . However , a s note d a t th e outse t o f thi s Section , the Agenc yencourage s commen t o n al l o f thes e factors , along wit han yother s .whic

h commenter s believ e t o b

e o f importance . Clearly , specifi c quantitativ e analysi s wit hsupporting dat a wil l be o f mos t us e t o th

e Agenc yi n completing it s fina l study .



## -&- 2- 1P.3 2

Tabl e 7 Effec t o f Varying the Numbe r o f Non-Attainmen t Area s on Onboar d Cos t Effectivenes s

N/ AAre a VO C Cos t Effectivenes s 4 0 Area s 5 0 Area s 6 1 Area s >6 1 Area s Benefit s Include d (28%) * (31%) * (35% ) * (50% ) * N/ AAre a VO C Onl y280 0 240 0 220 0 150 0 • N/ AAre a VO C + B Z 100 0 92 4 85 0 67 0 an d C 6 G V Incidence s + A AVO C Reduction s

Percen t o f nationa l gasolin e consumption .



### 3 0P.3 3

Tabl e 8 ONBOARD COS T EFFECTIVENES S ($/Mg )

VO C Valu e i

n N/ AArea s Considering BZ+C 6 G V Benefi t Valu e Incidenc e an d A/ AVO C $MM/INCI D $/M

g o f A/ AVO C Reductio n Benefit s 0 3. 5 7. 5 1 0 3. 5 7. 5 1 0 0

•25 0 25 0 25 0 50 0 50 0 50 0 220 0 130 0 35 0 54 0 95 0 46 0 15 0



## - 3 1P.3 4 

### Docke t A-87-1 1 Categor y IV- H Interagenc yRevie wMaterial s

Documen t Numbe r Dat e Sen t t o

Docke t Commenter , Addressee , o rTitl e (a s applicable ) Dat e o t Documen t IV-H-2 1 IV-H-2 2 01/13/9 4

01/13/9 4 Lette rto Barr yFelrice , NHTSA , fro m Richar d Wilson , EPA . Lette rfro m Richar d Wilson , EPA , to Barr yFelrice , NHTSA . 01/05/9 4 01/05/9 4