1 --- - --- - -- - -- - --- - -- - -- - --- - - - --- - --- - -- - -- - --- - -- - -- - --- - - - ----- - -- - -- - --- - -- - -- - --- - - - --- - --- - -- - -- - --- - -- - -- - --- - - - --- - -

T ec hn i c al Su p p o rt Do c u m e n t ( TS D)

Iowa

A re a D e sig n a t io n s F or

t h e

2010 S O 2 P r i m a r y Na t i o n al A m b i e n t Air Q u ali t y S t a nd a r d

Su m m a r y

P u r su a nt to s ec tion 107 ( d) of the C l ea n Air A c t ( C AA ) , E P A must d e si g n a t e a r ea s a s e ith e r

“nonattainment

, ” “attainment

, ” or “unclassifiable” f or the 2010 1

- hour su l f ur dio x ide ( S O 2 ) p r im ary

n a tion a l a mbi e nt a ir qu a l i t y st a nd ar d ( NA A Q S )

. T he C AA d ef in e s a non a t t a inm e nt ar e a a s one t h a t

do es not m ee t the NAAQS or th a t c ont r ibut e s to poor a ir qu a li t y in a n e ar b y ar e a th a t do e s not m ee t the

NAAQ S . T a ble 1 b e low id e nti f i e s the c ounti e s or po r tions of c ounti e s in I o wa t h at E P A is initi a l l y

d e si g n a t ing “ non a tt a inm e n t ” b a s e d on monito re d viol a tions. EPA is not yet prepared to designate other

areas in Iowa , and will address those other areas and their sources in a future final designations action

.

T a b le 1. No n a tt ai n m e n t A re a D e sig n a t io n s f or Io w a

Co un t y Na m e Io w a R ec o mme nd ed

D e sig n a t ion of

A re as/Co un t i es E P A ’ s D e sig n a t ion

of A re as/Co un t i es

Mus ca tine Un c l a ssi f i a ble Non a tt a inm e nt

B a c k g r o un d

On J une 2, 2010, E P A re vis e d the p r im a r y S O 2 NAAQS ( 75 F R 35520, J une 22, 2010) b y

e st a blis h ing a n e w 1

- hour st a n d ar d a t a l e v e l of 75 p ar ts p e r billion ( ppb)

, whi c h is met at an

ambient air quality monitoring site wh e n the 3

- y e a r a v e r a ge of the annual ( 99 t h p erce ntile ) of the

d a i l y m a x imum 1

- hour a v er a g e c on c e nt ra tion s d o not e x cee d 75 ppb , as determined in accordance

with Appendix T of 40 CFR part 50

. 40 CFR 50.17(a)

- (b). E P A h a s d e t er min e d th a t this is the

l e v e l n e c e ss a r y to p r ovide p r ot ec tion of pub l ic h ea lth with a n a d e q u a te m ar g in o f s a f e t y

,

e sp ec i a l l y f or c hild re n, the e l d e r l y a nd those with a sthm a . Th e se g r oups a r e p ar ti c u l ar l y

su s ce ptible to the h e a lth eff e c ts a sso c i a t e d with b rea thing S O 2 . The Ag e n c y is re voki n g the t wo

p r ior p r im a r y st a n d a r ds of 140 ppb e v a lu a t e d ov e r 24

- hou r s, a nd 30 p p b e v a lu a t e d o v e r a n e nti r e

y ea r b e ca u s e the st a nd a r ds will not a dd a ddition a l public h ea lth p r ot ec tion g iv e n a 1

- hour st a n d ar d

a t 75 p pb. A cc o r di n g l y , E P A is not d e si g n a ti n g a rea s in this p r o ce ss on the b a sis of e ith e r of

th e se two p r ior p r im a r y st a nd ar ds. S imil ar l y , t h e s ec on d a r y st a n d ar d f or S O 2 h a s not b ee n

re vis e d, so E P A is not d e si g n a ti n g a r ea s in this p r o ce ss on the b a sis of the s ec ond a r y st a nd ar d.

EPA’s SO 2 Designation Approach

S ec tion 107 ( d) of the C A A provides th a t not l a t e r t h a n 1 y e a r af t e r p r omu l g a tion of a n e w o r re vis e d

NAAQ S , st a te Gov e r no r s may submit th e ir rec o mm e nd a tions f or d e s i g n a tions a nd bound ar i e s to E P A.

This d ea dline w a s in J un e , 2011. S ec tion 107 ( d) a lso re qui re s E P A to p r o vide a noti f i ca tion to st a t e s

of no l e ss th a n 120

- d a y s p r i or to p r omul g a ti n g a n in i ti a l are a d e si g n a tion th a t is a modi f i ca tion of a

st a t e’ s rec omm e nd a tion. E P A h a s re vi e w e d the S t a t e’ s rec omm e nd a tions a nd h a s noti f i e d the S t a te

C ommission e r th r ou g h a l e tt e r si g n e d b y t h e Re g ion a l Administ ra tor of a n y i nt e nd e d modi f i ca tions. I f

a s t a te does not submit d e si g n a tion rec omm e nd a tions, E P A will p r omul g a te the d e si g n a tions th a t it2 d ee m s a pp r op r i a t e

. I f a st a t e dis a g r e e s with E P A ’ s int e nd e d a re a d e si g n a tions, it has a n oppo r tuni t y to

d e monst ra te w h y a n y p r opos e d m odi f i ca tion is in a pp r op r i a t e

.

D e si g n a tions g uid a n c e w a s issu e d b y E P A th r o u gh a M arc h 24, 2011, m e mo ra ndum fr om S t e ph e n D.

P a g e

, Di rec t o r , U. S . E P A, O ff i c e o f Air Q u a li t y P l a nning a nd S t a nd ar ds, to Air Division Di rec to r s,

U

. S . E P A R e g ions I

- X. This m e mo ra ndum id e nti f i e s f ac to r s E P A int e nds to e v a lu a te in d e t er mini n g

bound ar i e s f or ar e a s d e s i g n a t e d non a tt a inm e nt. T h e se 5 f a c to r s in c lud e : 1 ) a ir qu a li t y d a t a ; 2)

e missions a nd e mission s

- re l a t e d d a ta ( lo c a tion of sou rce s a nd po t e nti a l c o n t r ibution to a mbi e nt S O 2

c on ce nt r a tions ) ; 3) m e t e o r olo g y ( w ea t h er /t ra nsp o r t p a tt er ns ) ; 4) g e o g ra p h y / top o g ra p h y ( mount a in

ra n g e s or oth e r a ir b a sin bound ar i e s ) ; a nd 5 ) j u r isdi c tion a l bound ar i e s (e

. g

. , c ounti e s, a ir dist r i c ts, p r e

e x isting non a tt a inm e nt area s, re s er v a tions, m e t r o p olit a n pl a nning o r g a ni z a t ion )

, a mong a n y oth e r

in f o r m a tion d ee m e d r e l e v a nt to e st a blishing a pp r op r i a te a r e a d e si g n a tions a nd bound ar i e s f or the 1

-

hour S O 2 NAAQ S

.

The M arc h 2 4 , 2011, m e mo rec omm e nd e d th a t a r e a bound ar i e s be d e fa ult e d to the c oun t y boun d a r y

unl e ss a ddition a l p r ovid e d in f o r m a tion justi f i e s a l a r g e r o r sm a ll e r bound a r y th a n th a t of t h e c oun t y

. E P A b e li e v e s it is a pp r o p r i a te to e v a lu a t e e a c h po t e nti a l ar e a on a c a s e

- b y

- c a se b a sis, a nd to

r ec o g ni z e th a t are a

- sp ec i f ic a n a l y s e s c ondu c t e d b y st a t e s a nd/or E P A m a y suppo r t a di ff e re nt

bound a r y th a n a d efa ult c oun t y bound a r y

.

I n this T S D, E P A dis c us s e s its re vi e w a nd t e c hni c a l a n a l y sis of the r ec o m m e nd a tions submitt e d b y the

S tate of I o wa f o r d e s i g n a tions of the 1

- hour S O 2 st a nd ar d a nd a n y modi f i ca tions f r om th e se

rec omm e n d a tions.

D ef i n ition of i m

porta n t t e r

m s u s e d i n t h i

s do cu m e n t:

1) D e sig n a te d “ n o n a tt ai n m e n t ” a re a

– a n a r e a w hi c h E P A h a s d e t er min e d , b a s e d on a st a te

rec omm e nd a tion a nd/ o r on the t ec hni ca l a n a l y sis in c lud e d in this do c um e nt, h a s viol a t e d the 2010

S O 2 NAAQ S , b a s e d on the m ost rece nt th r e e y e ar s of a ir qu a li t y monito r i n g d a t a , or c ont r ibut e s to a

viol a tion in a n ear b y a re a

.

2) R ec o mme nd e d n o n a tt ai n m e n t a re a

– a n a r e a that a s t a te or tribal government h a s rec omm e n d e d to

E P A to be d e si g n a t e d a s no n a tt a i nm e nt.

3) Viola t i n g m o n i t or

– a n a mbi e nt a ir monitor m ee ting a ll m e thods, qu a li t y a ssu ra n c e a nd c iti n g

c r it er ia a nd re qui r e m e nts whose v a lid d e si g n v a l u e e x ce e ds 75 ppb, a s d e s cr ib e d i n App e ndix T of 40

C F R p ar t

50.

4) 2010 S O 2 NAAQS

- 7 5 ppb, n a tion a l a mbi e nt a ir qu a li t y st a nd a r d f or S O 2 p r omul g a t e d in 2010.

B a s e d on t h e 3

- y e a r a v e r a ge of the 99 t h p er c e ntile of the a nnu a l dist r ibution of d a i l y m a x imum 1

-

hour a v er a ge c o n ce nt r a tions

5) D e sign Val u e

– a st a t istic th a t d e s cr ib e s the a ir qu a li t y st a tus of a g iv e n are a re l a tive to the l e v e l

of the NAAQ S

.3 No n a tt ai n me n t D e sig n a t io n s

I n tr o du ct ion

I n I ow a ’ s d e s i g n a tion r ec omm e nd a tion l e tt e r to E P A, d a t e d J une 2, 2011, T er r y E. B r a nst a d, Gov e r nor

of I ow a

, rec omm e n d e d th a t 5 c ounti e s be d e s i g n a t e d a s a tt a inm e nt f or the 2010 S O 2 NAAQS b a s e d on

monito re d a ir qu a li t y d a ta fr om 2008

- 2010, with a ll oth e r c ounti e s d e si g n a t e d a s un c l a ssi f i a b l e

.

B a s e d on E P A ’ s t ec hni ca l a n a l y sis, E P A notified the Governor of Iowa (in the 120 day letter) of its

intention to designate the entire c oun t y of Muscatine

, I owa a s non a tt a inm e nt ( T a ble 1 )

. In response to

EPA’s 120

- day letter explaining our intention of designating Muscatine County , Iowa as nonattainment,

the Iowa Department of Natural Resources (IDNR) prep ared and submitted a technical analysis re butting

our presumptive county

- wide nonattainment boundary. This technical analysis examined several factors,

including monitoring data, meteorological data, proximity and magnitude of emissions. As a component

of the technical analysis, IDNR provided a windrose analysis of exceedance days that included the

violating monitor at Musser Park and 2 additional SO 2 monitors in the area. This windrose analysis

identifies several SO 2 sources in Muscatine County that contribute to the violating monitor at Musser Park

. In addition to the daily windrose analysis, IDNR submitted hourly monitoring and win d direction

information identifying the predominant SO 2 source(s) causing the violation at the Musser Park monitor

and locating them to the south, within a revised nonattainment boundary IDNR proposed that EPA adopt

.

Fina lly, although EPA is not relying upon it at this time, IDNR provided dispersion modeling that it

believes would help inform the extent of the nonattainment boundary and included all major sources

surrounding the Musser Park monitor along with a conservative bac kground value. Upon reviewing the

analysis provided by IDNR, EPA finds that a smaller than county

- wide boundary is appropriate and that

the boundary recommended by IDNR includes those sources that are appropriate to initially identify as

contributing to the violation observed at the monitor. Therefore, EPA is finalizing the nonattainment

boundary for Muscatine, Iowa proposed by IDNR. This boundary is based on violations observed at the

Musser Park monitor and a design value established over the years 2 009 and 2011. E P A is not y e t

reaching a conclusion concerning areas , and their sources, that are outside of the finalized nonattainment

boundary

, and will address these areas in a future final designations action

.

U pon receipt of IDNRs recommendation and technical analysis supporting a smaller nonattainment

boundary than proposed by EPA in our 120

- day letter, we analyzed IDNR’s submission and integrated its

analysis , apart from IDNRs dispersion modeling, into the five factor analysis we prepared for Muscat ine

County in our 120

- day letter

. The five factor analysis prepared for the 120

- day letter included a review of:

1. Air Quality Data

2. Emissions and Emissions Related Data

3. Meteorology

4. Geography and Topology

5. Jurisdictional Boundaries

This technical support document also includes an additional review of other relevant information supplied

by the IDNR in its submission that contribute to the five factors analysis found in a later section

.4 No n a tt ai n me n t D e sig n a t io n s

T ec hn i c al a n alysis f or M u s c a t i n e Co un t y, Iowa

I n tr o du ct ion

This t ec hni ca l a n a l y sis f o r Mus ca tine C oun t y

, I owa id e nti f i e s a portion of the county with a monitor

( AQS I D 191390020) th a t viol a t e s the 2010 S O 2 NAAQS b a s e d on 2009

- 2011 d a t a

, a nd e v a lu a t e s n e ar b y

c ou n ti es f or c ont r ibutions to S O 2 c on ce nt r a tions in the ar e a . E P A h a s e v a l u a t e d this c oun t y a nd n e a r b y

c ou n ti e s b a s e d on the w e i g ht of e vid e n c e of the f a c to r s r ec omm e nd e d in the M arc h 24, 2011, E P A

g uid a n ce.

F i g u r e 1 is a m a p o f the a re a in I owa t h a t E P A is initially d e s i g n a t ing n o n a tt a inm e nt f or the 2010 1

- hr

S O 2 NAAQS

, in c luding sou r c e in f o r m a tion a nd the lo ca tion of the monitor viol a ting the st a n d ar d.

F ig u re 1. M u s c a t i n e C o un t y, IA No n a tt ai n me nt B o und a r y5 F i g u r e 2 is a m a p o f the a re a a n a l y z e d sh o wing t h e lo ca tion of the a ir q u a lity monito r s in the a r ea , t h e

Mus ca tine C oun t y line in re d, a nd significant sou r ce s of S O 2 in the g rea t e r Mus c a tine C o. ar e a

.

F ig u r e 2 : M u s c a t i n e C o un t y Sh o w i n g S O 2 M o n i t or a n d S o u rce s of S O 26 On J une 2, 2011

, Gov er nor of I o w a , T e r r y E. B ra n st a d, rec omm e n d e d th a t 5 c ounti e s in I o wa with S O 2

monito r s re po r ting a mbi e nt c on ce nt ra tions b e low t he 75ppb st a nd ar d b e d e s i g n a t e d a tt a inm e nt a nd a l l

oth e r a r ea s of the st a t e be d e si g n a t e d un c l a ssi f i a b l e f or the 2010 S O 2 NA A QS b a s e d on monito re d a ir

qu a li t y d a ta fr om 2008

- 2 010. At that time, the S t a te p r ovid e d no f u r th e r in f o r m a tion or a n a l y sis

suppo r ti n g its a tt a inm e nt rec omm e n d a tions oth e r th a n the monito re d v a lu e s f o r the y e ar s 2 008 th r ou g h

2010.

On February 6

, 2013

, E P A sent a letter to the G overnor of Iowa notifying the S tate of our intention of

designating all of Muscatine County, Iowa a s the presumptive no n a tt a inm e nt boundary

, and initiating the

required 120

- day minimum period for state review prior to EPA issuing a final designation

. E P A ’s

proposal was based upon a v a il a ble monitoring data for the 3

- year period of the monitor’s operation

spanning years 2009 through 2011 indicating a violation at the Musser Park monitor

, a nd the a ppli ca tion

of 40 C F R P ar t 50 App e ndix T 3 ( d ) to replace missing data during this 3

- year period and allow for the

calculation of a valid design value

.

A monito r ’ s d e si g n v a l u e indi ca t e s wh e th e r th a t monitor a tt a ins a sp ec i f i e d a ir qu a li t y st a n d ar d. T h e

2010 S O 2 NAAQS is m e t a t a monito r ing site wh e n the id e nti f i e d d e s i gn v a lue is v a lid a nd l e ss th a n or

e qu a l to 75 ppb a s d e s cr ib e d in App e ndix T of 40 C F R P ar t 50

. H ow e v er

, even though the monitor was

in place and operating for over the minimum necessary 3

- year period, d a ta fr om the M u ss e r P ar k monitor

in Mus ca tin e

, I owa c ould not be v a lid a t e d usi n g the st a nd ar d p r o c e du r e f ound in App e ndix T b eca use a

subst a nti a l a mount of d a ta h a d b e e n f l a gg e d fr o m the y e ar s 2008, 2009 a nd 2010.

The d a ta w a s f l a g g e d a s a re sult of a m a l f un c tion of the int er n a l c a lib ra tion s y st e m of the

monito r . The m a l f un c tion w a sn ’ t d e t e c t e d imm e d i a t e l y

, a nd the monitor c o ntinu e d to c oll ec t d a ta f or

ov e r a y e a r . The m a l f un c tion w a s dis c ov e re d f ollowing p e rf o r m a n c e o f a r e fe r e n c e

p r o ce du r e on the monito r ’ s S O 2 ca lib ra tion s y st e m

. F ollowing the re f ere n c e p r o ce du r e a ref e re n c e a udit

w a s c o m pl e t e d whi c h in f o r m e d I DNR a nd E P A th a t the monitor h a d b ee n op era ti n g out of sp ec i f i c a tion.

F ollowing the a udi t , E P A a nd I DNR re v i e w e d the re sults a nd joint l y a g r e e d to: 1) a dj u st the o r i g in a l

r ec o r d e d v a lu e s to acc ount f or the c a lib ra tion err o r ; 2) cer ti f y the a djust e d v a lu e s into the Air Qu a li t y

S y s t e m ( AQ S ) d a t a b a s e ; a n d , 3) f l a g the a djust e d d a ta in the AQS d a t a b a se so it c ould not be us e d f or

r e g ul a to r y p u rpos e s.

Due to the l a r g e a mount of f l a g g e d d a ta

, the Mus s e r P ar k monitor no long e r m e t the minimum d a ta

c ompl e t e n e ss cr it er i a f or the 3

- year p er iod of time w hi c h we a r e usi n g to e v a l u a te c ompli a n c e with the

NAAQ S , even though the monitor had been in place and operating for well over the minimum

necessary 3 years . The c ompl e t e n e ss cr it e r ia sp e c i f i e d in App e ndix T of 40 C F R P ar t 50 re qui re 3 y ea r s

of c ompl e te d a ta to e st a blish a d e si g n v a lu e

. A y e a r is c ompl e t e wh e n a ll 4 qu ar t er s a r e c ompl e t e . A

qu ar t e r is c ompl e te wh e n 75% of t h e d a y s a r e c ompl e t e

. A d a y is c ompl e t e wh e n it h a s 75% of its hou r s.

Althou g h Ap p e ndix T of 40 C F R P ar t 50 in c lud e s d a t a substitution p r ovisions, due to the l a r g e a mount

of missing d a t a fr om the Muss e r Pa r k monito r , the d a ta substitution p r ovisions w er e not a ppli c a bl e

. Ho w e v er , 40 C F R P ar t 50 A p p e ndix T 3 ( d) a llows the Administ ra tor of E P A to c onsid e r oth e r fac t o r s,

su c h a s c onsist e n c y a nd l e v e ls of the v a lid c on ce nt r a tion m ea su re m e nts th a t ar e a v a il a ble f o r the pu r pose

of e st a blishing a d e s i g n v a lu e covering a monitor’s 3 years of operation

.

The App e ndix T 3 ( d) p r o vision w a s a ppli e d in the Muss e r P ar k situ a tion b e ca use the v a lid d a ta rec o r d e d

fr om the moni t or f or the numb e r of y e a r s p rece di n g a nd f ollowing the m a l f u n c tion in c lud e d su ff i c i e nt

h i g h hou r l y m e a su re m e nts to d e monst ra te that the a mbi e nt S O 2 c on ce nt ra tion in Mus ca tin e

, I owa w a s

si g ni f i ca nt l y a bove the 2010 S O 2 1

- hr p r im a r y NAAQ S

. I n fa c t, in e v a lu a ting w h e th e r t o a pp l y the7 App e ndix T 3 ( d) p r ovision to the Muss e r P ar k d a t a , E P A R e g ion 7 took the most c ons er v a tive a p p r o ac h

po s sible a nd a ssum e d th a t a ll the d a ta th a t w a s f l a g g e d b e tw e e n the d a t e s o f Au g ust 30, 2008 to

S e pt e mb e r 20, 2010 w a s z er o ( i. e ., the monitor re p o r t e d a z er o d a i l y c o n ce n t ra tion of S O 2 in the a mbi e nt

a ir f or the p er iod of m a l f un c tion ) . This a p p r o ac h r e sult e d in a d e s i gn v a lue 127 ppb ( w h e n c a l c ul a t e d f or

the th r ee y ea r p e r iod of the monitor’s operation b e g inni n g on J a nu a r y 1, 2009 a nd e n d ing on D e ce mb e r

31, 20 1 1 ) , whi c h e x cee ds the NAAQS b y 150 %

, a nd d e monst ra t e s th a t the mo n itor is for that 3

- year

period rec o r di n g a viol a t i on of the 1

- hr standard.

In response to our proposed designation, IDNR prepared comments to our proposal recommending that

EPA finalize a revised boundary that did not include the entire county. In this analysis, the state reviewed

the impact at the monitor of sources emitting SO 2 in and around all of Muscatine County , and found that

establishing a nonattainment boundary for the entire county was not warranted

. IDNR has instead

recommended that the EPA finalize a boundary that is approximately 1/3 the size of our proposed

boundary. I n this T S D, E P A dis c us s e s its re vi e w a nd t e c hni c a l a n a l y sis of the r ec o m m e nd a tions

submitt e d b y the S tate of I o wa f o r d e s i g n a tions of the 1

- hour S O 2 st a nd ar d a nd a n y modi f i ca tions f r om

th e se rec omm e n d a tions.

D et ail ed Ass e s s m e n t

A ir Q u ality Data

W e re v i e w e d S O 2 a ir qu a li t y m o nito r ing d a ta fr om E P A ’ s Air T re nds w e bsite ( s e e

http://www. e p a

. g ov / a i r t re nds/v a lu e s.html ) , i n c luding the d e si g n v a lue ca l c ul a t e d f or the monitor in

Mus ca tine C oun t y

, I o w a f or t h e y e a r s 2009

- 2011. This fac tor c onsid e r s the S O 2 a ir qu a li t y monito r i n g

d a t a (found in EPA’s Air Trends website at http://www.epa.gov/airtrends/values.html) , in c luding t h e

d e s i g n v a l u e s ( in ppb) c a l c u l a t ed f or a ll a ir qu a li t y monito r s in Mus ca tine C oun t y a n d the su rr oundi n g

a r e a b a s e d on d a ta f o r the 2009

- 2011 period.

E P A ’s final nonattainment boundary for Muscatine County, I owa is b a s e d on d a ta f r om (a ) Fe d e ra l

R e f ere n c e M e t h od (F R M) or Fe d eral Equiv a l e nt M e thod (F E M) monito r( s) lo ca t e d in the st a t e

.

The 2011 S O 2 NAAQS d e si g n v a l u e s f or a ll c ounti e s (c ont a ini n g a monito r ) in the S t a te of I owa

a nd su rr ounding ar e a a r e sh o wn in T a ble 2.

T a b le 2. Air Q u ali t y D a t a f or All M o n i t o r s in t h e S t a t e of Io w a

C ou n t y State

R ec o mm e n d ed

N o n atta i n m e n t? Mo n it o r N a m e Mo n it o r A ir Q u ali t y

S y s t e m I D Mo n it o r

L o cati o n SO 2 De s i g n Val u e,

2009

- 2 0 1 1

(ppb)

M u s c at ine No M u ss er Pa rk 191 3 90 0 20 M u s c at ine, IA 127 *

C l i n t o n No Ch a n c y P a r k 190 4 50 0 19 C l i n t o n 21

L i n n No 500

11TH 191130040 C e d ar R a p i d s 28

P o lk No P u b lic Health

B u il d i n g 191 5 30 0 30 Des Mo i n es 3

Sc o tt No J e ff e r s o n

Sc h ool 191 6 30 0 15 Da v e n por t 13

Van B u r en No L a k e S u g e m a 191 7 70 0 06 Ke o su a q ua 5

* T h e D V i s b a s e d o n a n a

p p l i c a t i o n o f th e 4 0 C F R P a r t 5 0 A p p e n d i x T 3 ( d ) p rov id i n g a u th ori t y fo r th e A d m ini s t r at o r t o a p p rov e th e u se o f

an i n c o m p l e t e d a t a s e t t o e s t a b l i s h a v a li d DV.8 The Muss e r P ar k monit o r in Mus ca tin e

, I owa shows a viol a tion of the 2010 S O 2 NAAQ S

. Due to the

violating monitor

, E P A must d e t er mine an a pp r o p r i a te bound ar y f or the are a s u rr oundi n g the monitor

to be d e si g n a t e d non a tt a inm e n t, oth er wise b y d e f a ult E P A id e nti f i e s the e nti r e c oun t y a s the ar e a of

non a tt a inm e nt. The a bs e n c e of a viol a ti n g monitor a lone is not a su ff i c i e nt rea son to e limin a te n e ar b y

c ounti e s a s ca ndi d a t e s f o r in c lusion in a non a tt a inm e nt are a a s w e ll. E a c h are a h a s b e e n e v a l u a t e d

b a s ed on the w e i g ht of e vid e n c e of the f ive fac t o r s a nd o th e r re l e v a nt in f o r m a tio n

.

E

m issio n s a n d E missio n s

- R e lat e d Data

Evid e n c e of S O 2 e missions sou rce s in the vi c ini t y of a viol a ting monitor is a n impo r t a nt fac tor f or

d e t er mining w h e th e r a n e ar b y a r e a is c ont r ibuti n g to a monito re d viol a tion. F or this f a c to r , E P A

e v a lu a t e d c oun t y l e v e l e missions d a ta f or S O 2 a nd a n y significant change in S O 2 e mi t ting ac tiviti e s

sin c e the d a te re p re s e nt e d b y those e m i ssions d a t a

.

Emissions

E P A r e li e d on v er i f i e d e missions d a ta c u rre nt l y a v a il a ble in the 2008 N a tion a l Emissions I n v e nto r y

( N E I ) e missi o ns d a t a b a se ( N E I 200 8 V3 .0 )

. G e n e r a l l y , the point s ou rc e inv e nto r y found in the database

re p re s e nts the bulk of the S O 2 e missions in R e g ion 7.

T a ble 3 shows tot a l e missions of S O 2 ( g iv e n in tons p e r y e a r ) f o r viol a ting a nd pot e nti a l l y c ont r ibuting

c ounti e s in a nd ar ound Mus ca tine C oun t y

, in c luding sou r ce s e mit t ing g r e a t e r t h a n 100 tons p er yea r of

S O 2 a c c o r di n g to the 2008 N E I . The two I owa c ounti e s a dj a c e nt to Mus ca tin e C o unty with sou rce s

within 50 kilom e t er s a nd e mitting g rea t e r th a n 100 tons p e r y e a r a r e f ound i n L ouisa C oun t y

, I owa

, a nd

S c ott C oun t y

, I A . The s ou rc e in L ouisa C oun t y is a n e l ec t r i c g e n e ra ti n g u nit own e d a nd op e r a t e d b y

MidAm er i ca n En e rg y ( t h e L oui s a P ow e r S t a tion )

. The oth e r sou r c e of S O 2 ( 2,488 tons p e r y e ar

- not

list e d in the t a ble 3 b e low) lo ca t e d outside of M u s ca tine C o unty is L af a r g e N o r th Am er i c a C e m e nt Kiln

in B u f f

a lo, I owa ( S c ott C ount y )

, a pp r o x im a t e l y 31.5 ki l om e t er s E a st

- N o r th ea st o f the viol a ting monito r

. At the time of proposal, EPA was uncertain over the contribution or direct impact specific sources had

on the violating monitor; however, windrose analysis (discussed in more detail later) provided by IDNR

supports that emissions from Grain Processing Corporation (GPC), Muscatine Power and Water

(MPW), and Monsanto Company are contributing to the violations recorded by the monitor.9 T a b le 3. A nnu a l S O 2 E m issio n s 2008

C ou n t y Facili t y > 8 0 t p y

(EI S o r State Facili t y I D) Facili t y E mi ss i o n s ( t p y ) T o tal C o un t y S O 2

E m i s s i on s

( t o n s p er y ea r )

M us cat i n e G r ain P ro ce ss i n g

C orpor ati on 14

, 9 79

26,4 79 C e n t r al I o w a P o w er

– Fair

Stati o n 7,068

M us cat i n e P o w er a n d

W ater 3160

Mo ns a n to C o m p a ny 520

S S A B I o w a I n c 374

Ge rd au A m e r i s teel US 80

L o u i s a M idA m e r ican

– L o u i s a

Stati o n 2,453 2,453

Sc o tt L a Fa r g e N or th A m e r ican 2,488 2,488

Area T otal 31,4 2 0

Emissions C ont r ols

The e missions d a ta us e d b y E P A in this t ec hni ca l a n a l y sis a nd p r ovid e d in T a ble 3 re p re s e nt e missions

l e v e ls t a king into a cc ou n t a n y c ont r ol st ra t e g i e s i mpl e m e nt e d on st a tion a r y sou r ce s in Mus ca tine

County a nd surrounding area s up to a nd in c luding the y e a r 2008. E P A h a s not re c e iv e d a n y a ddition a l

in f o r m a tion on e missions re du c tions re s ulting fr om fe d e r a l l y e n f o rcea b l e c ont r ols put into pl ac e a f t e r

2008. Emission c ont r ol in f o r m a tion f or t he sou rce s id e nti f i e d in T a ble 3 is summ ar i z e d b e low.

G ra in P r o ce ssi n g C o r po r a tion ( G PC )

G P C p r o ce ss e s g ra in f or the p r odu c tion of f ood a n d liquor g r a de e t h a nol, a s w e ll a s a v a r i e t y of g r a in

b a s e d f ood p r od u c ts a nd a nim a l fee ds. G P C is lo c a t e d 1.2 kilom e t er s S outh

- S outh ea st of the viol a ting

monito r . As p ar t of the g ra in c onv e r sion a nd p r o d u c tion p r o ce ss G P C op e r a t e s a v a r i e t y of boil er s f or

h ea ting a nd pow e r p r od u c tion. G PC ’ s m a in sou rc e of S O 2 e missions is e m ission point #1 ( E P

- 1) whi c h

in c lud e s boil er s 1, 2, 3, 4, 6 a nd 7. The boil er s r a n g e in h ea t input ca p ac ity f r om 105

– 230 MM B t u/h r

. The boil er s a r e c a p a ble o f bu r ning c o a l a nd n a tu r a l g a s. E P

- 1 is limit e d to 3915 lbs of S O 2 /hr (a v er a g ed

ov e r a 24

- ho u r p er io d ) a n d 6 lb/MM B tu. E P

- 1 is not e quipp e d with a n y S O 2 c ont r ol s y s t e m. E P

- 1 is

e quipp e d with a n S O 2 c ontinuous e mission mon it or ( C EM ) . G P C op era t e s f our g er m d r y e r s. T h e g er m

d r y e r s h a v e the f ollowi n g S O 2 e mission limit s : 1 3 .73 lb/hr ( E P

- 15 ) , 9.20 lb/hr ( E P

- 97 ) , 0.53 lb/hr ( E P

126) a nd 500 ppm ( E P

- 1 78 ) . The g er m d r y er s ar e not e quipp e d with a n y S O 2 c ont r ol s y st e ms. E P

- 600

is ca p a ble of b u r ning bi o g a s a nd n a tu r a l g a s. E P

- 600 is limit e d to 4.86 lb S O 2 /h r . E P

- 600 is e qui p p e d

with a w e t g a s s c r ubb er

. G P C op era t e s g lut e n f l a s h d r y e r #4 ( E P

- 17 3 ) whi c h is ca p a ble of b u r ning

bio g a s. E P

- 173 h a s a h e a t input ca p ac i t y of 29 M M B tu/h r . E P

- 173 is lim i t e d to no mo r e th a n 4.5 lb

S O 2 /h r . The d r y e r is e q u ipp e d with a w e t s cr ub b e r th a t is e x p ec t e d to ac hi e ve a 91.2% c o nt r ol

eff i c i e n c y while bu r ning bi o g a s. G P C op era t e s f our n a tu ra l g a s

- f i re d “ P ow e r House B oil er s” ( E P

- 103,

104, 1 42

a nd 153) with h ea t input ca p a c iti e s th a t ra n g e fr o m 120

– 124 MM B tu/h r . Th e se boil er s bu r n n a tu r a l

g a s on l y a nd h a ve a n e m i ssion limit of 500 ppm. Th e se units ar e not e quipp e d with a n y S O 2 c ont r ol

s y st e m. G P C op era t e s a n a ddition a l “ P ow e r Ho u se B oil e r ” ( E P

- 177) with a h ea t input ca p ac i t y of 3 60

MM B tu/h r . This unit is l imit e d to 500 ppm a nd 0.23 lb S O 2 /h r . This un i t i s a lso not e quipp e d with a n y

S O 2 c ont r ol s y st e m. G P C op era t e s s e v era l sm a ll n a tu ra l

- g a s f i re d e missi o n units in c luding d r y er s.

Th e se units ar e limit e d to 500 ppm S O 2 a nd ar e not e quipp e d with a n y S O 2 c ont r ol s y st e m.

In response to EPA’s 120

- day letter and technical support document, IDNR notified EPA of the following10 changes that have occurred at the GPC facility. The following sources were removed: EP

- 103.0, EP

104.0, EP

- 542.0, and EP

- 543.0. The stack height for EP195.0 was increased to 66.5 feet. Two new

sources were added (EP

- 546.0 and EP

- 548.0). And, the emissions from EP

- 551.0 were changed from

internally

- venting to a point source.

C e nt ra l I owa P o w e r C o o p

– Fa ir S t a tion ( C I PC O )

C e nt ra l I owa P o w e r C o o p (Fa ir S t a tion) is a n e l e c t r ic g e n e r a ting fac ili t y th a t is lo ca t e d 25.4 kilom e t er s

E a st

- No r th e a st of the vi o l a ting monito r

. C I PC O ’ s m a in S O 2 e mis s ion sou rce s ar e E P

- 1 a nd E P

- 2.

E P

- 1 is a 280 MM B tu/hr boil e r th a t is ca p a ble o f b u r ning c o a l a nd n a t u ra l g a s. E P

- 1 is limit e d to 6 l b

S O 2 /MM B tu. E P

- 1 is n o t e quipp e d with a n y S O 2 c ont r ol s y st e m. E P

- 1 is not e quipp e d with a S O 2

C EM. E P

- 2 is a 477 MM B tu/hr boil e r th a t is c a p a ble of bu r ni n g c o a l a nd n a tu ra l g a s. E P

- 2 is limit e d to

6 lb S O 2 /MM B tu. E P

- 2 i s not e quipp e d with a n y S O 2 c ont r ol s y st e m. E P

- 2 is e quipp e d with a S O 2

C EM. C I P C a lso op era t e s a sm a ll n a tu ra l g a s/di e s e l boil e r a nd two sm a ll e m er g e n c y g e n e r a to r s.

In response to EPA’s 120

- day letter and technical support document, IDNR notified EPA that CIPCO is

currently scheduled to cease operation in September of 2013. However, b ecause EPA is not aware of an

enforceable agreement that requires CIPCO to cease operation, CIPCO must be included in any analysis

reg arding its impact on the area exceeding the SO 2 NAAQS.

Mus ca tine P ow er & W a t er ( M PW )

M P W is a nonp r o f it pub l ic utili t y o f fer i n g e l ec t r i c , w a t er

, a nd c ommuni ca t i ons s er vi ce s to the g r ea t e r

Mus ca tine muni c ip a l a r e a lo ca t e d 1.9 km S outh

- S outh ea st of the viol a ting monito r . M PW ’ s m a in S O 2

e mission sou rce s a r e e l ec t r ic g e n e r a ting units d e s i g n a t e d E P

- 70, E P

- 80 a nd E P

- 90. E P

- 70 is a 289

MM B tu/hr boil e r th a t is ca p a ble o f bu r ni n g c o a l a nd n a tu ra l g a s. E P

- 70 is limit e d to 6 lb S O 2 /MM B tu.

E P

- 70 a nd E P

- 80 a r e a l s o limit e d to a c ombin e d 2,772 lb S O 2 /hr (a v er a g e d ov e r a 24

- ho u r c a l e nd a r d a y )

a nd 12,141 tons S O 2 / y r

. E P

- 70 is not e quipp e d with a n y S O 2 c ont r ol s y s t e m. E P

- 70 is e quipp e d with a

S O 2 C EM. E P

- 80 is a 8 9 0 MM B tu/hr boil e r th a t is ca p a ble o f bu r ni n g c o a l , n a tu ra l g a s, w a ste solv e nt

( limit e d ) , di e s e l oil ( limi t e d) a nd w a ste oil ( limit e d ) . E P

- 80 is limit e d to 6 l b S O 2 /MM B tu. E P

- 70 a nd

E P

- 80 ar e a lso limit e d to a c ombin e d 2,772 lb S O 2 /hr (a v e r a g e d o v e r a 2 4

- h our ca l e n d a r d a y ) a nd

12,141 tons S O 2 / y r . E P

- 80 is not e quipp e d with a n y S O 2 c ont r ol s y st e m. E P

- 80 is e quipp e d with a S O 2

C EM. E P

- 90 is a 1,556 MM B tu/hr boil e r th a t is ca p a ble o f bu r ni n g c o a l a nd n a tu ra l g a s. E P

- 90 is

limit e d to 0.56 lb S O 2 / M M B tu (a v er a g e d ov e r a 2 4

- hr ca l e nd a r d a y ) a nd 0

. 45 lb S O 2 /MM B tu (a v er a g ed

ov e r a 30

- d a y p er io d )

. E P

- 90 is a lso subj ec t to a 92% re du c tion in S O 2 fr o m the f lue g a s d e sul f u r i z a tion

s y st e m ( s c r ubb er s C E

- 93 a nd C E

- 94 ) . E P

- 90 is a l so subj ec t to N SP S subpart Da e mission li m its. As

m e ntion e d, E P

- 90 is e quipp e d with two s cr ubb e r s ( C E

- 93 a nd C E

- 94) th a t c ont r ol S O 2 e missions. E P

90 is e quipp e d with a S O 2 C EM. M P W a lso op era t e s s e v era l sm a ll di e s e l a nd g a solin e

- pow e re d

e mission units.

L a F a r g e

– N o r th Am er i c a n

L a fa r g e ' s c e m e nt m a nu f a c tu r ing pl a nt lo c a t e d in B u ffa lo, I owa m a in so u rc e o f S O 2 e missions is the

p re h ea t er /p r e ca l c i n er /kiln/ ra w mill s y st e m ( EP

- 0 4 66

- 0) lo ca t e d a pp r o x im a t e l y 31 kilom e t er s E a st

Northeast of the viol a ting monitor in Mus ca tin e

, I owa T h e c e m e nt p r o ce ssing p l a nt h a s a c a p a c i t y of

145.3 tons c link e r p e r hou r

. EP

- 0466

- 0 is limi t e d to 4,850 tons S O 2 / y r a nd 2,900 lb S O 2 /h r

. EP

- 0 466

- 0

is e quipp e d with a d r y

a bso r b e nt a ddition s y s t e m. EP

- 0466

- 0 is a lso e quipp e d with a n S O 2 c ontinuous e mission monito r

. L a fa r ge c a n bu r n a ra n g e of a pp r ov e d m a t er i a ls in the kiln.

L a fa r ge a lso h a s a c ouple of sm a ll f ossil

- f i re d e m i ssion units in c luding a di e s e l

- f i r e d e m e r g e n c y

g e n era t o r a nd a d i e s e l

- f i r e d w a t e r pump th a t ar e l i mit e d to 2.5 lb S O 2 /M MB tu limit a nd ar e not e q u ipp e d11 with a n y S O 2 c ont r ols.

Due to EPA not including any portion of Fort Scott County , I owa in the nonattainment area we proposed

in our 120

- day letter, the Lafarge facility was not included in the analysis submitted by IDNR in

response to EPA ’s proposal . We note that the Lafarge facility is east of the violating monitor

, and that

IDNR’s windrose analysis does not indicate that sources east of the monitor are contribut ing violation at

the Musser Park monitor. Based on this, we are not yet prepared to conclude that the emissions from the

Lafarge fac ility contribute to the monitored violation or to other possible violations . I n a subsequent

round of designations we will make final designations decisions for areas (and their sources) , like Fort

Scott County , that are not currently included in the nonattainment area designation addressed in this

TSD

.

MidAm er i ca n En e rg y C omp a n y

– L ouisa G e n e ra t i ng S t a tion ( MidAm er i ca n or LGS)

MidAm er i ca n En e rg y C omp a n y is a f or

- p r o f it pow e r p r odu c tion c om p a n y th a t op era t e s a n e l e c t r ic

g e n era ti n g f ac ili t y in L o u isa C oun t y

, I owa 13.9 kil o m e t er s S outh

- S outhw e st of the viol a ting monito r

lo ca t e d in Mus ca tine C o un t y

, I owa . T h e L ouisa G e n era ti n g St a tion is just s o uth of the Mus ca tine

c o u n t y line with a po r tion of its p r op er t y l y i n g acr oss the c oun t y lin e . MidAm e r i c a n ’ s m a in S O 2

e mission sou rc e is E P

- 1 ( Utili t y B oil er) . MidAm er i c a n a l s o op era t e s two a u x ili a r y boil er s ( E P

- 2 a nd

E P

- 3) a nd two e m e r g e n c y g e n e ra to r s ( E P

- 4 a nd E P

- 5 ).

E P

- 1 is a 8,624 MM B tu/hr boil e r th a t is ca p a b l e o f bu r ning c o a l, #2 f u e l oil a nd n a tu ra l g a s. E P

- 1 is

limit e d to 0.96 lb S O 2 / M M B tu ( B A C T) (a v e r a g e d ov e r a 30

- d a y p er io d ) , 1

. 20 lb S O 2 /MM B tu ( N S P S D)

while bu r ning solid f ossil f u e l, a nd 0.80 lb S O 2 /MM B tu ( N SP S D) while b u r ning liquid f ossil f u e l. E P

- 1

is a lso limit e d to 3,450 lb S O 2 /hr (a v er a g e d o v e r a 30

- d a y p er io d ) . The sul f ur c ont e nt of a n y c o a l is

limit e d to 2.0 lb/MM B tu or l e ss. E P

- 1 is e quipp e d with a lime sp r a y d r y e r f lue g a s d e sul f u r i z a tion

s y st e m ( s c r ubb e r ) . E P

- 1 is e quipp e d with a S O 2 C EM. E P

- 2 a nd E P

- 3 a r e 98 MM B tu/hr boil er s th a t ar e

ca p a ble o f bu r ni n g n a tu r a l g a s a nd #2 f u e l oil. E P

- 2 a nd E P

- 3 a r e limit e d to 98.3 lb S O 2 /hr eac h. The

sul f ur c ont e nt of the f u e l oil is li m it e d to 0.5% b y w e i g ht. E P

- 2 a nd E P

- 3 a r e not e quipp e d with a n y S O 2

c ont r ol s y st e m. E P

- 2 a n d E P

- 3 ar e not e quipp e d with a n S O 2 C EM. E P

- 4 a nd E P

- 5 ar e 16 MM B t u /hr

e m e r g e n c y g e n e ra to r s t h a t ar e ca p a b l e of #2 f u e l oil on l y . E P

- 4 a nd E P

- 5 a r e limit e d to 8.4 lb S O 2 / hr

eac h. T h e sul f ur c on t e nt of the f u e l oil is limit e d t o 0.5% b y w e i g ht. E P

- 4 a nd E P

- 5 ar e not e quipp e d

with a n y S O 2 c ont r ol s y s t e m. E P

- 4 a nd E P

- 5 a r e n ot e quipp e d with a n S O 2 C EM.

EPA ’s proposed default nonattainment boundary did not include the LGS facility in neighboring Louisa

County, however IDNR’s analysis included an evaluation of the LGS facility for its contribution at the

violating monitor

. T he LGS facility is located south of the violating monitor, which is the general

direction of the sources implicated by IDNR’s windrose analysis as causing or contributing to the

violations detected at the Musser Park monitor. However, as our 120

- day letter to Iowa did not address

this source, we are not yet prepared to conclude that the emissions from the LGS facility contribute to the

monitored violation or to other possible violations , and we will make final designations decisions for

areas and sources outside Muscatine County in a subsequent round of designations.

Mons a nto C omp a n y ( M o ns a nto)

Mons a nto is a n a g r i c ult u ra l s er vi c e s c omp a n y th a t p r odu ce s on

- site po w e r a nd h ea t a t its p r odu c t

d e v e lopm e nt f a c ili t y a p p r o x im a t e l y 9.0 kilom e t e r s S outh

- S outhw e st of the viol a ting monito r

, Mons a nto ’ s m a in S O 2 e mission sou rce s ar e B oil e r #6, #7 a nd #8. E P

- 33 ( B oil e r # 6 ) is a 73 MM B tu/hr

boil e r th a t is ca p a ble o f b u r ning f u e l oil a nd n a tu r a l g a s. E P

- 33 is limit e d to 36.6 lb S O 2 /h r . The a mount

of f u e l oil E P

- 33 ca n c o mbust is d e p e nd e nt on wh e th e r E P

- 45 is bu r ni n g f u e l oil. The sul f ur c ont e nt of12 the f u e l oil is limit e d to 0 .5% b y w e i g ht. E P

- 33 is not e quipp e d with a n y S O 2 c ont r ol s y st e m. E P

- 3 3 is

not e quipp e d with a n S O 2 C EM. E P

- 45 ( B oil e r #7) is a 124 MM B tu/hr b o il e r th a t is ca p a ble o f bu r ning

f u e l oil a nd n a tu ra l g a s. E P

- 45 is limit e d to 61.4 l b S O 2 /h r . The a mount of f u e l oil E P

- 45 ca n c om b ust

is d e p e nd e nt on wh e th e r E P

- 33 is bu r ning f u e l oil. The sul f ur c ont e nt of t h e f u e l oil is limit e d to 0. 5 %

b y w e i g ht. E P

- 45 is not e quipp e d with a n y S O 2 c ont r ol s y st e m. E P

- 45 is not e quipp e d with a n S O 2

C EM. E P

- 195 ( B oil e r # 8) is a 150 MM B tu/hr b o il e r th a t is ca p a ble o f bu r ning c o a l, slud g e ( limit e d) a nd

s ee d c o r n ( limit e d ) . E P

- 195 is limit e d to 292.5 lb S O 2 /hr a nd 1.95 lb S O 2 / MM B tu (a v e r a g e d ov e r a 3

- hr

p er iod ) . E P

- 195 is not e quipp e d with a n y S O 2 c o nt r ol s y st e m. E P

- 195 is e quipp e d with a n S O 2 C EM.

E P

- 21 ( B oil e r # 5 ) is a 73 MM B tu/hr boil e r th a t is ca p a ble o f n a tu r a l g a s o n l y . E P

- 21 is limit e d to 500

ppm S O 2 . Mons a nto a l s o op era t e s s e v e r a l sm a ll n a tu ra l g a s

- f i re d e missi o n units a nd a sm a ll di e s e l

e m e r g e n c y g e n e ra to r

.

SS AB I o w a

, I n c

. ( SS A B )

SS AB I n c . is a st ee l m a n u fac tu r e r th a t is lo ca t e d 2 1.6 kilom e t er s E a st

- No r t h ea st of the viol a ti n g monito r

, SS A B ’ s m a in S O 2 e mission sou rc e is E P

- 1 ( E A F / L M F) . E P

- 1 is a n e l ec t r i c a r c f u r n ac e a n d a l a dle

m e t a llu rg y f u r n ace

. The e l ec t r ic a r c f u r n a c e h a s a ca p ac i t y of 200 to n s of liquid st ee l/h r . E P

- 1 is limit e d

to 0.70 lb S O 2 /t o n of st ee l p r odu c e d a nd 6 13.2 tons S O 2 / y r . E P

- 1 i s not e quipp e d with a n y S O 2 c ont r ol

s y st e m. E P

- 1 is not e quipp e d with a n S O 2 C EM. S S AB a lso op e r a t e s a 371 MM B tu/hr f u r n ac e ( E P

- 13)

th a t bu r ns n a tu r a l g a s on l y . E P

- 13 is limit e d to 0.52 lb S O 2 /hr a nd 2 tons of S O 2 / y r

. SS AB a lso op era t e s

s e v e r a l sm a ll n a tu ra l g a s a nd di e s e l

- f i re d e mission units.

Based on its location and distance to the east of the violating monitor at Musser Park, IDNR’s windrose

analysis does not indicate that the SSAB facility is causing or contributing to the violating Musser Park

monitor. Based on this, we are not yet prepared to conclude that the emissions from the SSAB facility

contribute to the monitored violation or to other possible violations

. In a subsequent round of

designations we will make final designations decisions for areas and sources not currently included in

the nonattainment area designation addressed in this TSD

.

G er d au Am er ist eel U S

, I n c. ( G e r d a u)

G er d a u Am er ist ee l is a s t ee l m a nu f a c tu r e r th a t is lo ca t e d 20.5 kilom e t er s N o r th of the viol a ting mo n ito r

. G er d a u ’ s m a in S O 2 sou rc e is E P

- 01 ( whi c h in c lu d e s the e l ec t r ic a r c f u r n a ce ) . The e l e c t r ic a r c f u r n a c e

h a s a ca p ac i t y of 90 tons of liquid st ee l/h r . E P

- 01 is limit e d to 70.2 lb S O 2 / hr a nd 190 tons S O 2 / y r

. Th er e ar e p er mit c onditions th a t limit the a mount of liquid st ee l p r o ce ss e d, the car bon so u rce s f or t h e

e l ec t r ic ar c f u r n a c e a nd t he a mount of n a tu r a l g a s c ombust e d. E P

- 01 is not e quipp e d with a n y S O 2

c ont r ol s y st e m. E P

- 01 is not e quipp e d with a n S O 2 C EM. G er d a u a lso op e ra t e s a 150 M M B tu/hr B i ll e t

R e h ea t F u r n a c e ( E P

- 04 )

. This f u r n a c e bu r ns n a tu r a l g a s on l y . T h e S O 2 e missions ar e limit e d to 500

ppm. G er d a u a lso op era t e s s e v e r a l sm a ll n a tu ra l g a s a nd di e s e l

- f i re d e miss i on units.

Based on its location and distance to the north of the violating monitor at Musser Park, IDNR’s

windrose analysis does not indicate that the Gerdau facility is causing or contributing to the violating

Musser Mark monitor. Based on this, we are not yet pre pared to conclude that the emissions from the

Gerdau facility contribute to the monitored violation or to other possible violations

. In a subsequent

round of designations we will make final designations decisions for areas and sources not currently

include d in the nonattainment area designation addressed in this TSD

.13 M e t e orology ( w e at h e r/tra n sport patt e r n s)

W e e v a lu a t e d m e t e o r ol o g i ca l d a t a to h e lp d e t er mine how w e a th e r c onditions, in c luding wind sp ee d a n d

di rec tion, af f

ec t the pl u me of sou rce s c ont r ibuting to a mbi e nt S O 2 c on ce nt r a tions. The N a t i on a l

W ea th e r S er vi c e m a int a ins su rfac e a nd upp e r a ir monito r ing sit e s acr oss the Unit e d S t a t e s. Autom a t e d

S u rfa c e Ob s er ving S y st e m ( A S O S ) ( http://www.w ea th er

. g o v / a sos ) sit e s c oll ec t hou r l y a v er a g e d wind

m ea s u r e m e nts in c luding wind di rec tion a nd wind sp e e d

.

Evid e n c e of so u rc e

- r e ce p tor re l a tionships b e tw ee n sp ec i f ic e missions sou r c e s a nd h i g h S O 2 v a lu e s at

viol a ting monito r s is a noth e r impo r t a nt fac t o r in d e t er mining the a pp r op r i a te c ont r ibuting ar e a s a nd t he

a pp r op r i a te e x t e nt of the non a tt a inm e nt ar e a bou n d a r y

. F o r this fac to r , E P A c onsid ere d the additional

information submitted by IDNR that contained windrose analysis on exceedance days.

IDNR provided a windrose analysis on exceedance days for three SO 2 monitors in the Muscatine area.

This analysis is found in Figure 3

. Because the Musser Park monitor represents the design value

monitor, the EPA focused on the windrose associated with this monitor, and notes that the majority of

the exceedances are from sources located south of the monitor. This windrose analysis provide s

supporting information to not include in this initial round of designations several SO 2 sources found in

the northern and eastern portion of Muscatine County, including SSAB , Gerdau Ameristeel, and CIPCO

, as the wind does not come from the direction of t hese sources during monitored exceedances at the

Musser Park monitor

. In addition to the daily windrose analysis, IDNR submitted hourly monitoring

and wind direction information , Figure 4

, demonstrating that the predominant SO 2 source(s) impacting

the Mus ser monitor were located to the south

.

EPA finds that the IDNR windrose and meteorological analysis supports a smaller initial boundary that

includes the Muscatine County sources that EPA has sufficient information to conclude are contributing

to the violations at the Musser Park monitor. E P A is not y e t reaching a conclusion concerning areas and

sources not included in the initial nonatt ainment boundary

, and will address these areas and their sources

in a future final designations action

.14 Figure 3 . IDNR Wind roses on observed exceedance days (2010

- 2012).15 Figure 4 . IDNR analysis of hourly winds paired with hourly SO 2 concentrations at Musser Park.

Increased Southerly Wind Speeds Winds Shifted from East to South

Wind Direction: North Wind Direction: East16 G e ograp h y

/Topograp h y ( m o u n tain ra n g e s or ot he r air basin bo un da r i e s)

W e e x a min e d the p h y si c a l fea tu r e s of the l a nd th a t mi g ht af f

ec t the dist r ibution of S O 2 ov e r a n ar e a

. R iv e r v a ll e y s, e s car pm e nts, or oth e r p h y si ca l fea tu r e s m a y aff e c t the dist r ibution of e missions, a nd m a y

h e lp d ef ine bound a r i e s. S a t e llite im a g e s d e pi c ti n g r iv e r v a ll e y s a nd point s o u rce s w er e c onst r u c t e d a nd

e v a lu a t e d to d e t er mine the e f fec ts of t h e topo g ra p h y on point sou rc e e missions.

Mus ca tine C oun t y

, I owa d o e s not h a ve a n y s i g ni f i ca nt g e o g r a phi ca l o r topog r a phi ca l b a r r i er s

s i g ni f i ca nt l y limiting a i r

- pollution t ra nspo r t within its a ir sh e d; how e v er , Mu s ca tine C o u n t y re sts on the

w e st er n

sho r e of the up p e r Mississippi R iv er . This fac tor d i d not pl a y a s i g ni f i c a nt r ole in d e t er mining the

non a tt a inm e nt bound a r y

. The r iv e r v a ll e y c r ea t e d b y the Mississippi R iv e r ca n imp ac t lo ca l winds by

c h a nn e li n g th e m a lo n g t h e v a ll e y no r th a nd south, a nd ca n s e r ve to limit the imp ac t of a p a r ti c ul a r

sou rc e on a monitor sit e d in p r o x i m i t y to the r iv e r v a ll e y

. I n the c a se of M u s ca tin e

, a s the Mississippi

R iv e r f lows south it m a k e s a st r o n g b e nd to the w e st acr oss the e a st er n e d g e o f the c oun t y

, th e n a b r upt l y

tu r ns s outh a g a in a t the C i t y o f Mus ca tin e

. I owa

. T he e x ist e n c e of the r iv e r c h a nn e l th r o u g h and a cr oss

t he e a st er n e d ge of the c ounty is not e x p ec t e d to imp a c t the e missions obs er v e d a t the viol a ting monitor

lo ca t e d in Mus ca tin e

, I owa

.

J

u risdi c tio n a l B o u n dar i e s

On c e the g e o g ra phic a r e a a sso c i a t e d with the a r e a viol a ting the S O 2 st a nd ar d a nd the n ear b y a re a s

c on t r ibuting to viol a tions is d e t er min e d, w e c onsid er e x isting ju r isdi c tion a l bound ar i e s f or the

pu r pos e s o f p r ov i ding a c l ear l y d ef in e d l e g a l bound a r y f o r car r y i n g out the a ir qu a lity pl a nni n g a nd

e n f o r ce m e nt f un c tions f or the no n a tt a inm e nt ar e a

. I f an e x isting ju r isdi c tion a l b o und a r y is us e d to h e lp

d e f ine the non a tt a inm e nt a r ea , it e n c omp a s s e s a ll of the a r e a th a t h a s b ee n i d e nti f i e d a s m ee ti n g the

non a tt a inm e nt d ef inition. Th e se e x isting bound ar i e s m a y in c lude a n e x isting non a tt a inm e nt or

m a int e n a n c e ar e a b o und a r y , a c o u n t y o r township bound a r y

, a m e t r opolit a n are a boun d a r y

, a n a ir

m a n a g e m e nt dist r i c t, or a n u r b a n pl a nning bound a r y e st a b l ish e d f or c oo r di n a ting b u sin e ss

d e v e lopm e nt or t r a nspo r t a tion ac tiviti e s. W h er e e x isting ju r isdi c tion a l bound ar i e s a r e not a d e qu a te to

d e s c r ibe the n on a tt a inm e nt ar e a , oth e r c l e a r l y d ef in e d a nd p er m a n e nt l a ndm a r ks or g e o g ra phic

c oo r din a t e s a r e us e d

.

E P A re vi e w e d j u r isdi c tion bound a r y in f o r m a tion, in c luding townships, c i t y limits, a nd a p re vious S O 2

non a tt a inm e nt bound a r y

. The revised boundary recommended by IDNR encompasses the area that

includes the sources within Muscatine County that we are now prepared to conclude are contributing

to exceedances observed at the monitor

, as well as the area IDNR’s analysis shows is exceeding the

NAAQS. IDNR’s recommend ation is also consistent with jurisdictional (township) boundaries of

the area. Areas and sources that we are not yet prepared to conclude are contributing to the

monitored violation are not included in this initial nonattainment area. The legal description is as

follows in Table 4.17 Table 4 . Legal Description of Iowa DNR Proposed Nonattainment Area.

Township Sections

T77N R3W (Lake township) 1

- 3, 10

- 15, 22

- 27, 34

- 36

T76N R3W (Seventy

- six township) 1

- 3, 10

- 15, 22

- 27, 34

- 36

T77N R2W (Bloomington township) All

T76N R2W (Fruitland township) All

T77N R1W (Sweetland township) All except 1, 12, 13, 24, 25, 36

Ot h e r R e l ev a n t I n

f

or m at ion

To support its revised boundary proposal, IDNR also conducted refined dispersion modeling. We are not

relying upon the specific results of this modeling to support our final initial designation, but provide the

following discussion for informational purposes. IDNR performed two types of modeling

– a culpability

test to assess which sources contributed to the exceedances observed at the Musser Park monitor, and a

full grid analysis to evaluate the extent of the predicted exceedances surrounding the Musser Park

monitor

.

The full grid analysis modeling performed by IDNR was cente red on the Musser Park monitor and

extended out to cover EPA’s presumptive county

- wide nonattainment boundary. The modeling analysis

performed by IDNR utilized actual emission rates from 2009 through 2010 for the following sources:

Grain Processing Corpo ration (GPC); Muscatine Power and Water (MPW); Monsanto; MidAmerican

Energy (Louisa Generating Station); and Central Iowa Power Corporation (CIPCO). IDNR used a default

background concentration typically used for modeling conducted in the new source revie w program

permit applications . The results of the modeling analysis predict that exceedances of the 1

- hr 2010 SO 2

NAAQS extend over an area substantially smaller than the presumptive count y

- wide boundary proposed

by EPA . This revised area includes 3 of the 6 SO2 emissions sources that were included in EPA’s

original county

- wide presumptive boundary , and is consistent with IDNR’s contribution conclusions from

its windrose analysis for those sources

. Figure 5 contains the results of the IDN R modeling showing the

extent of the predicted exceedances and its proposed nonattainment boundary within Muscatine County.

EPA is not prepared to conclude on the basis of IDNR’s refined dispersion modeling, that sources or areas

excluded based upon IDNR’s m odeling are or are not contributing to violation s of the SO2 NAAQS

.

E P A is not y e t reaching a conclusion concerning areas excluded from the initial nonattainment boundary

and will address these areas in a future final designations action

.18 Figure 5 . IDNR Proposed Nonattainment Boundary (highlighted in green)

Co n c l u sion

The a ir qu a li t y monitor in Mus ca tine C oun t y sh o ws a viol a tion of the 20 1 0 S O 2 NAAQ S , b a s e d on

2009

- 2011 a ir qu a li t y d a t a . As a r e sult

, Mus ca tine C oun t y or some po r tion of Mus ca tine C oun t y m u st be

d e si g n a t e d a s non a tt a in m e nt. B a s e d upon the c on s id era tion of a ll the r e l e v a nt a nd a v a il a ble in f o r m a tion,

a s d e s cr ib e d a bov e , E P A b e li e v e s that the technical analysis prepared and submitted by IDNR to respond

to EPA’s preliminary nonattainment area proposal presents a reasonable and technically supported

alternative initial nonattainment boundary. IDNR’s technical analysis examined several factors,

including monitoring data, meteorological data, and proximity and magnitude of emis sions.

Additionally, IDNR demonstrated through windrose analysis which sources are known to be impacting

the violating monitor and should be included in the nonattainment area. The windrose analysis also

provide d supporting information to exclude from the initial nonattainment area several SO 2 sources

,19 which will be further analyzed in subsequent designations action s

, in the northern and eastern portion of

Muscatine County, including Gerdau Steel, SSAB and CIPCO.

EPA finds the windrose analysis performed by IDNR supports a smaller initial boundary, excluding

those sources within Muscatine County that we are not yet prepared to conclude are contribut ing to the

violating monitor on days exceeding the standard

. Based upon the consideration of all r elevant and

available information, as described above, EPA is finalizing the initial SO 2 nonattainment area boundary

proposed by IDNR that is described in Table 4 above.