98 SAN J <\C I Nl O BlVD
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# BAKER BOlT S LL. P. SUIIE 1500 AUSTIN IEXAS 78 701·4078 TH • I 512.322 2500 FAX •15123???501

**Bol erBon~**  com Sep tembe r 17 , 2015

Ms. Janet G. McCabe Assistant Administrator, Office of Air and Radiati on U.S. E nvironmental Protection Agency ll eadquarters 1200 P ennsy lvania A ve nu e, N. W. Mail Code 6101A Washington , DC 20460 Dear M s . McCa be: AUSTIN l ONDON B[ljJNG MOSCOW SPUSSftS NEWYOPY DAllAS PAlONTO DUBAI R IO DE jANE I PO HONG KONG PIY ,\l)ll HOUSTON WASHINGTON

Derek McDonold TEL 5 123222667 FAX : 51232283 42 dere k mcdonold@bokerbott$ com

This l e tter i s sub mitted o n behalf of Major Oak Power , LL C (Major Oak) t o support the designation or the area surrounding the Twin Oaks P owe r Station in Robert so n Co unty, Texas as attainme nt fo r the ational A mbient Air Qualit y Standard (NAA Q S) for s ulfur di o xide (S 0 2 ) se t in 20 I 0 at 75 part s per bill i o n (e qual to 196 micr og ram s per cubic meter



### (~ **))** as a 1-h o ur average. We submit thi s int o rmati o n in res po n se t o th e requ es t r o und in yo ur letter dated March 2 0, 20 1 5, t o th e ll o n orabh.: Br yan W. ' haw. C hairman. Tc
. 'l:as C o mmi ss i o n o n E n v ir o nmental Quality (TCEQ). Th i s info rm ati o n s upports th e

**TCI s**  co ntinu t: d reco mmendati on that th e a r

ea be de s i g nated as uncl ass itiablc/attainment for the 1-h o ur

**SO ~**  AAQS based primaril y on the latest m o nit o rin g data and seco ndaril y o n so urce m o delin g conducted by the TCEQ
. Maj o r Oak ow ns the Twin Oaks P owe r Stat i on. The Twin Oaks plant in c lud es tw o 175- megawatt s team elect ri c ge n e ratin g circulatin g fluidi ze d bed (CFB) unit s fu e led primari l y by li gn it e from an adja ce nt mine. The de s i g n of the fluidized be d bo ilers prov ide s inherent control o r 

## so2 e mi ss i o ns. Maj o r Oak maintains that the area s urrounding o ur facility must b e de s i g nated as attainment or unclass ifiabl e /attainment for S0 2• B o th of these o ptions are avai l able to EPA under the Clean A ir Act and we are awa re or no evidence that the air near our facilit y exceed s th e primary S02 NAAQS. None of' th e regu lato ry m on itor s in Texas arc s howin g vio l ation s of the S0 2 AAQS, including one in nearby McCiennan Co unt y, Texa s . A n attainment o r unclas s ifiab l e designation i s clearly appropriate in the se circumstances
.

## BAKER BOTTS ,,p Ms . Jane t G. McCabe 

### - 2
- September 

### 17, 20 15

The T CEQ's un c la ss ifiabl e/attainm e nt re co mmendati o n for Robe rt so n County i s a l so s upported by di spers i on model in g an a l ysis co ndu cted by the TCEQ
. As docum ented in the State o f Texa s' September 

### 20 15 s ubmittal to EPA , 

# I the predi cted maximum 

# so2 de s i g n va lu e associated w ith actual S0 2 emissions fr o m o ur plant and n ea rb y so urces i s o nl y I 

### 00 J.l g/m 3 , wh i ch i s approx imatel y 

### 50% of the S02 stand ard o f 

### 196 f.lg/ m 3

. Imp ortant l y, this air qualityprotective re s ult was rea c hed de spite including in th e m o del S02 em i ss i o ns fro m the Oak Grove power p l ant 

### 2 1 kilometers away . 

### 1 6 J.lg/m 3 background S0 2 l eve l s as m eas ur ed at the nearb y ambi e nt monit o rin g stati o n in M cC i e nnan Co unt y, and the inh e rentl y co n serva tive nature of th e dispers i o n m ode lin g analysis which tend s to ove rprcd ict ambient air co ncentrati o n s. Additional detail s o n th e m o deling approach arc as fo ll ows :
• T he atmo spheric di spersion m odelin g perf o rmed by th e TCEQ was exec uted 111 acco rdan ce w ith th e guidance in the E P A draft docu m ent,

**··so~** AAQ De s i g nati o n s M ode lin g Technica l Ass i stan ce Document,
.. dated De cembe r 

### 2013. The Am e rican M eteorolog i ca l Soc i ety / Envi ro nm ental Pro tection Agency Reg ul atory Model (AE RM OD) was u se d in acco rd an ce wi th th e gu idan ce. Three yea rs of recen t rep r ese ntati ve met eo ro l og i ca l data 

### (20 12 to 

### 20 14 ) we re u se d. The meteorol og ical data were co llect ed at the n eares t Nationa l Weath e r Se rvi ce stations. The su rfa ce dat a were collected in Co ll ege St a ti o n. Texas (S tati o n o. 

### 03904) and th e upp er air data we re co ll ected at Fort Wo rth, T exas (S tati o n o. 

### 03990). AERMET wa s u se d to process the data a l ong with represe ntative albedo, B owe n r a ti o, and su rface roug hne ss va lues determined with AERSURFACE.
• The only s ign i ficant sources of S0 2 emissions a t th e faci lit y are tw o s ta c k s se r v icin g th e two C FB boil e rs . Th e two stacks were modeled wi th actua l s ta c k p ara m ete rs ( i. e . , s tack h e i g ht. s ta c k ex it diam ete r , s tack exit ve l oci ty, and s tack ex it temp e rature)
. Nearby s tru ctures were accoun t ed fo r and downwash parameters were det e rmin ed with th e u se of th e EPA prog ram BPIP-PRM. Actua l h o urly S0 2 emission rates, as reported to EPA's Acid Rain Prog ram databa se were u sed in the m odeling.
• The T " in Oaks fa c ility i s l oca ted in a rural se lling with n o o th er sign ifi cant l oca l so ur ces o f SO:!
. T h e neare s t s ignificant source o f S0 2 em i ss i ons. th e Oak Grove Steam E l ectric Station (Oak Grove), i s l ocated approx imat e l y 

### 2 1 kilom eters from th e Twin Oaks facilit y . Actual h our l y S0 2 emissions fo r Oak Grove
. as reported to E PA · s Acid Rain Prog r am databa se, were included in the modeling.
• A represen tative background concentra ti on o f S 0 2 was added to th e resu lt ant maximum m odeled co n centra ti o n . The backg ro und co n cen trat i o n data was

1 Memorandum from D ani e l Menendez t o David Brymer, Subject: Modeling Analysis of Sulfur Di ox id e for Major Oak P ower, LLC
- Twin Oaks ( RN 100226570) (Jun e 5, 2015).

## BAKER BOTTS II f> 

### Ms. Janet G. McCabe 

### .., 

## - .) 

## - Septe mb e r 17 , 20 1 5

collected at the EPA Acro m et ri c Inf ormat i on R etri eva l System (A IR S) monitor l ocated in Waco , Texas. The receptor gr id consisted of a Cartes i an g rid of recepto r s w ith 

### I 00-meter spacing alo n g the Twin Oaks fe n ce line out to o ne kil ometer, a Ca rt esia n gr id o f receptors with a spa c ing of 50 0 m ete rs l oca ted o ut to five kil o meter s, and anot h er Cartesian grid of recepto r s with a spacing of o ne ki l o m eter located out to fifty kilometers. R ece pt o r elevations were de te rmin ed with the u se of th e E PA program AERMAP. The recept o r grid and elevations that were u se d are consis tent wi th E PA guidance.
• Associated modelin g file and the TCEQ ' s umrmlr) m ode ling memorandum are attache d. The se modeling methodologie s utili ze d by the TCEQ are al so consistent where app li cab l e with the guidance provi ded by the draft December 2013 EPA document referenced above and EPA ' s · 'G uideline on Air Quality M odels ,' · published as Appendix W to 40 CFR Part 

### 5 1. Notably, th e facility i s al ready wel l - con tro ll ed for 

### S0 2• 

### as it was made sub ject to federal Best Available Cont r o l Techno l ogy review when permi tt ed. Thro u g h a comb in ation of the p l ant's CFB technology and lim estone injection, the plant i s able to cont ro l S0 2 

### emissions below federal PSD permi t limits to m eet S0 2 

### emi ss ion budgets and regulatory limits under the C rossState A ir Pollution Rule as applicable at this time Compliance with permit and reg ulatory limits is co ntinu o u sl y d e m o nstr ate d thro ugh a con tinu ous em i ss i o n s monitoring syste m. We d o not be li eve that it would be reasonable to require additio n a l po s t-combustion S0 2 

### emission controls for the plant. Major Oak appreciates your conside ratio n of thi s inf o rm at i o n. B ased on EPA · s respon ses to prior FO I A reques t s, we understand tha t EPA h as n o so u rce mod e lin g inf o rm at i o n that s u ggest s th at the Twin Oak s plant causes or co ntributes to an exceedance of the 

### S0 2 

### NAAQS. If any suc h in fo rmati o n i s s u b mitt ed to E PA, we respe ctfully reque s t the op portunity to re view it and provide o ur view s o n the m ode l ing approach. If you wou ld lik e to di sc uss further. please do n ot h es it ate to co ntac t Eddy Young. E nvironmental Supervisor at Twin Oak s. at 254.746.55 78 or eddv. voung ({Moncstargcn.com. o r me. Since re l y,

D e rek McDonald Attachments

## BAKER BOTTS tiP M s . Janet G. McCabe 

### - 4 - September 17 , 20 15

cc: R on Cu rry, Regiona l Admini strator , E PA Region 6 Gu y D o naldson , Chief. A ir Pl anni n g Section. E P A Reg i on 6 Br yan W. Shaw, Ph.D. , P.E. , Cha irman , Texas C o mmission o n E nvironm en tal Quality Eddy Y ou ng , Environmental S upervi so r , Twin Oaks