The world ' s leading sustainability consultancy Bake r Bo tt s, LL.P . 

# S02 Air Dispersion Modeling Report for Coleto Creek Power Station September 2015 ERM Project No. 0311696 www.erm.co m



# ~ ERMBaker Botts, L.L.P. 

# S0 2 A ir Dispersion Modeling Report for Coleto Creek Power Station September, 2015 ERM Project No. 0311696

Robert G. Fraser 

### Partner
- in
- Charge

Richard P. Ha m e l 

### Project Ma11ager

Environmental Resources Management One Beacon S tree t , 5th Floor Boston, MA 02108 T: 617-646-7800 F: 617
- 267
- 6447TABLE OF CONTENTS 1.0 fNffiOD U CTION 1 .1 PROJECT OVERVIEW 1 .2 0 VER VIEW OF METHODOLOGY 

### 2.0 FACILITY DESCRIPTION AND REGULATORY SETT ING 2.1 FACILITY LOCATION 2.2 S0 2 ATTAINMEN T STATUS 2.3 SO URCE PARAMETER S AND EMISSION RATES 3 .0 AIR DISPERSION MODELING ANALYSIS 1-1 1-1 

### 1-2 2-1 2-1 2-1 2-4 3-1 3 .1 MODEL SE LECTION AND APPLICATION 3-1 3 .2 THE1-HOURS02N AAQS 3-1 3 . 3 METEOROLOGICAL DATA 3-1 3.4 RECEPTOR GRID 3
- 3 3.5 GOOD ENGINEERING PRACTICE STACK HEIGHTANALYSIS 3
- 3 3.6 AMBIENT S0 2 BACKGROUND DATA FOR CUMULATIVE MODELING 3
- 5 

### 3.7 REVIEW OF NON -FA CILITY SOURCES FOR C UMULATIVE INVENTORY 

### 3
- 6 4.0 MODELING RESULTS 4.1 CONCL U S IONS 5.0 REFERENCES

ii 4-1 4-1LIST OF TABLES 

### Table 2-1 Cole to Creek Statiort Unit No. 1 -Stack Parameters Table 3-1 Table 3-2 

### Table 3-3 

### Table 3-4 Table 4-1 Characteristics ofthe Victoria Regional Airport Meteorological Data Summary ofColeto Creek Power Statio11 GEP Aualysis Compariso11 of S02 Emissious 11ear Coleto Creek and Monitor Seasonal Diurual S02 Couceutratious at Corpus Christi Monitor (pglm3) 

### 1-hour S0 2Modeling Results for Coleto Creek Power Station LIST OF FIGURES 

### Figure 1-1 Figure 2-1 Figure 2-2 

### Figure 3-1 Figure 3-2 

### Figure 3-3 

### Figure 3-4 Figure 

### 3-5 Figure 3-6 

### Figure 4-1 Coleto Creek Power Station Surrormdiugs and Land Us e Coleto Creek Power Statiou Site Piau Coleto Creek Power Statiou Local Topography Relative Location ofColeto Creek and Victoria Regional Airport Three-year Wind Rose (2 012-2014): Victoria Regional Airport Near-Field Model Receptors Far-Field Model Receptors Structures Iucluded in tire Coleto Creek GEP Analysis Relative Location of Coleto Creek Power Station and Corpus Christi Monitor Cole to Creek Power Station 1-ltour S02 Impact Contours

LIST OF APPENDICES APPENDIXA ELECTRONIC MODELING ARCHIVE

iii 

### 2-4 3-2 

### 3-4 3-5 3-6 

### 4-1
1-4 2-2 

### 2-3 3-8 

### 3-9 

### 3-10 3-11 

### 3-12 3-13

4-21.0 INTRODUCTION ERM Co nsulting & Engineering, Inc. (ERM), presents thi s air disp e rsion mod e lin g report to Ba ke r Botts, L.L.P (Baker Botts) demonstrating that ma ximum model-predicted S02 impacts from GOF Suez Coleto Creek Power Station (Coleto Creek) ar e in attaimnent with the 1-hour Su lfur Dioxide (S02) National Ambient Air Quality S tandard (NAAQS). This analysis was co ndu c te d in compliance with the 1-Hour S02 Data R e quir e ments Rule and applicab le EPA and TCEQ a ir qual ity modeling gu idance. The results o f this a n alysis co nfirm that the ambient air quality in Goliad Co un ty in the vicinity of Coleto Creek, currentl y undesignated for the 1- hour S02 NAAQS, is within the standard and s h ou ld be id e ntifi e d as "attainment" in the n ex t cycle of d es ignations. This modeling report describes the methodology that was us e d to evaluate potential impacts of S02 e mi ss ions from Co l eto Creek on ambient air quality. Co pi es of th e modeling files are pro vid e d in Appendix A, the Electronic Modeling Arch ive. 1.1 

### Project Overview TCEQ ha s reco mmended that EPA designate Goliad County as unclassifiable f attainment for the 1-hr S02 NAAQS based on existing amb ient air monitoring data. On March 20,2015, EPA n o tifi e d TCEQ that EPA would make an attainment det e rmination for Goliad County on July 2, 2016, based o n updated recommendations and supporting information submitted to EPA by Se ptembe r 16, 2015. Un lik e previous NAAQS attainment demonstrations, which have been based o n ex isting ambient air monitoring data, EPA has prop ose d to make 1-hour S02 NAAQS attainment determinations using ambient air monitoring data and/ or a ir dispersion modeling. In s itu ations where air mod eli ng is us ed to make this d e t e rmin a ti o n , the approach described in EPA ' s draft "Modeling Technical Assistance Document" (TA0) 1, which sets forth a significantly differ e nt tedtnical approach compared to co n ventional reg ulato ry m ode lin g prescribed by 40 CF R Part 51, Appe n dix W (EPA's 

### Guideliue 011 

### Air Quality Models) co uld be us e d. This approach would a l so m ee t the requirements of EPA's 1-Hour S02 Data R e quirements Rule (ORR). EP J\ distinguishes the approaches described in th e S02 Modeling TAD to" reflect a view that des i gnations are intended to address current actua l air quality (i. e ., m ode lin g simulates a monitor), and thus are unlike attainment planning modeling, wh ic h must provide assurances that attainment will occu r." EPA's proposed approach would utilize several distinctive tec hnical approaches, including but not limited to the following: • Simulating actual emissio ns and exhaust cond iti ons (e.g., te mperatu re and flowrate) on an hourl y basis reflecting actual operations for a spec ifi e d histori cal time period; • Representing actual stack heights, irrespectiv e of th e GEP regulations; • L imi ting modeled ambient air receptors to locations where monitoring co uld actually take p la ce by ex cluding waterways, roadways , railways, res trict e d access pr operty, and other

1 http ./ I l' p <l . t •ov I o agp sOOl/s ul f urdi ox id c l pdf s/S02 M o d e lingT AD .pdf
ERM 

### 1-1 COLETO CREEK/ 03116%- SEPTEMBER 2015locations that would conventio nally be considered "ambient air" for regulatory and permitting purposes; and • Simulating a three-year period of meteorological and backgro u nd m o n itoring data, concurrent with the actual operating conditions and emiss ions, to mee t EPA's objective that "mo deling simulates monitoring" in this co nt ext. Some of the above methodologies are specifically discussed in the Data Requirements Rule, while th e less commonly used modeling approaches such as plume depletion are not. ERM performed a cumu l ative modeling ana l ysis eva l uating the impacts on ambient a ir quality from S0 2 emissions at Co l eto C reek. In add iti on, although the approach for cons idering cum ulativ e a mbi ent impacts with other maj o r sources in the region is not specifically covered in the rule, ERM considered a ll ot h e r m ajor sources of S02 w ithin 50 ki lo m e te rs for in clusion in the modeling. As discussed in this report, ERM's approach to th e modeling analysis used those refinements directly addressed in the ru l e, i.e. th e us e of actual hourly emissions, ac tu al stack h eights, and seasonal diurna l ambient background concentratio n s. As s hown in thi s modeling report, m o d e l -p re dict ed S02impacts from Co l eto Creek emission s ources, w hen combined with amb i e nt air concentrations tak e n from a n earb y re presentative monitor, a.re 111J.lg/m3 (42 .4 ppb), well b e low the 1-hour SOz NAAQS of 196.5 J.lg/m 3 (75 ppb). The analyses s h ow that the re is no s ignific a nt impact to attainment of th e 2010 SOz NAA Q S in Go li ad County, or in any ot h er co un ty, from Co l e t o Creek. Th e a n a ly ses also s how that compliance of the SOz s tandard in Goliad Co un ty is not s ignificantly impacted by an y other S02 e mi ss ion sou rce. This first section of 

### this report describes th e modeling methodology that was followed. Sec ti on 2 provides a description of the fac ility and tl1e e missions included in tl1e modeling. Model se l ection and the m e thodology u sed in the mod e lin g a re described in Section 3. The modeling results are presented in Sectio n 4. References a rc provided in Section 5. 1.2 

### O verview of Metl10dologt} ERM's assessments we re conducted in a mann e r consi stent with United States Environmental P r otection Agency (EPA) and Texas Com mi ssion on Environmental Quality (TCEQ) air quality regulations and m ode ling guidelines, including the following EPA documents:
• Guideline 011 Air Qunlihj Models - 40 CFR Pa rt 51, Append ix W, Revised Nove m ber 9, 2005. • AERMOD flllpl e lllel/tntioll Guide, Revised Marc h 19, 2009; • "S0 2 NAAQS Designations Mode lin g Tec hni ca l Assistance Docume nt (Draft)," December 2013; • "S02 NAAQS Designations Monitori n g Technical Assistance Docume nt (Draft)," December 2013;

ERM 

### 1-2

**COLI O**  C REEK / 03 11 696 - SEPTEMBER 2015• " Data R e quir e m e nt s Rul e f o r th e 1-H o ur S ul f ur Di ox id e (S 0 2) Prim a ry Natio nal A mbi e n t Air Quality S tand a rd (NAA QS), " Pr e -publi ca ti o n Final rul e, Au g u s t 11 , 20 1 5 ); and • " Guid a n ce fo r 1- h o ur S 0 2 Nonattainm e nt Ar ea S IP Submi ss io n s," April 23, 20 14. As we ll as: • " Ai r Qu a li ty M o d e ling Guide lin es, APDG 6 23 2", TCEQ April , 2015. The s teps th at we re u nd e rtake n by ERM to co n d u ct the air d isp e rs i on m o d e lin g ana ly s es a r e s umm a rize d b e low: • C o mpil e d inf o rm a ti o n on the parame te rs a nd c harac te ristic s f o r th e m a in bo ile r s ta c k e mi s si o n s a t Co l e to C ree k ; • D eve lo p ed a co m p r e h en sive r ece pto r g rid to capt ure th e ma ximum o ff -si te i mp acts fro m Co leta Cre e k sou rc es us in g AE RMA P (v.11103); • Rev iewe d r eg iona l ambi en t b ac kg r o un d m o nito r s to d e te rmin e th e m os t ap pro priate a mbi e nt b ac kg r o un d co n ce ntrati o n d a ta fo r S0 2 to re pres ent so ur ces n o t ex plicitl y in cl u de d in the m o d e lin g run s; • De v e lop e d 3 yea rs (2012 -2014) of m e teo rol ogic al data usin g s urf ace o b se r v ations from Vic tori a Reg i o n a l Airp o rt in Victoria, TX with upp e r air data from Co rpu s C hristi Internati o nal /\irp o rt in C orpus Christi, TX u s in g th e most re ce nt ve rs io n (v . 15181) of AE RM ET, th e m e t eo r o log ical data pro cesso r f o r AE RMOD , and its tw o pr e pro ce s so rs: AERSURF ACE (v .13 01 6) and AE RMINU TE (v . 1 4 237) ; • R e vi ewed a ll m ajo r so ur ces o f

**~** w ithin 50 kil o m e te rs of Co l e ta C re e k f o r p oss ibl e inclu s i o n in th e c umulati v e m o d e lin g a n a l ys is u s in g the 2011 Na ti o n a l Emi ss io n In ve nto r y Data b ase 2 , b ase d o n g uidanc e includ e d in th e S 0 2 Mo deling T A D . • Condu c te d a n a ir di s p e rs ion mod e lin g a n a l ys is u s in g th e most r ece nt ve r s io n o f EPA 's r e gulatory di s p e r s io n mo del, AERMOD (v . 1 5 1 8 1) and 3 y ears (2012- 20 1 4 ) o f ac tual e missi o n s d a ta fro m Co le ta Cree k, c on s is te nt with th e methodolo gy d e sc rib e d in the S02 Data R e quir e m e n ts Rul e and S02 Mo d e lin g TA D. • Summ a ri ze d th e res ults a nd compar e d th e m with the 1 -hour S02 N A AQS to d e t e rmine a r eco mm e n de d a tta inm e nt d es ignati o n f o r th e v ic injty o f Col e ta C ree k.

2 http :/ / w ww.c p a. g o v I tln c h il'l / n c t /20 11 invc ntorv . html
E RM 

### 1-3 CO LET O CREE K / 03 11 696 - SEPTEMBER 201 5

### Fig ur e 1
- 1

ERM 

### Col e to Cre ek Powe r Station S u rro uudiu gs a nd Lau d U se

GOF Suez Coleto Creek Station Fann in. TX 

# \v ERM


### 1-4 COLETOC REEK /03116% -SEPTEMBER 20152.0 FACILITY DESCRIPTION AND REG UL ATORY SETTING 2.1 

### Fac ilittj Location The Coleta Creek Power Station is located in th e town of Fannin, Texas. The station is locate d about 2 miles northeast of downtown Fannin. The site is accessed by FM 2987 off US. Route 59. The station is approximately 90 m iles southeast of San Antonio, Texas and 65 miles north of Corpus Christi, Texas. Approximate site coordinates are 28.713° North Latitude, 97.214° West Longitude. The Universal Transverse Mercator (''UTM") coordinates of the facility a re 674,410 Eas ting and 3,177,477 Northing (using North American Datum of 1983- NAD83) in UTM Zone 14. The base elevation of the facility is 106' (32.309m) above sea lev e l. A full scale site plan of Coleta Creek is shown in Figure 2.1, and Figure 2.2 shows th e site location marked on a United States Geological Survey ("USGS") 7.5-minute topographic map. 2.2 S0 2 Attainment S tatus In July 2013, EPA issued a ru l e designating 29 counties or partia l counties as non-attainment for 1-hour S02 . However, the vast majority of the country was not designated by EPA at that tim e. None of th e counties surrounding Coleta Creek, including Goliad, the county in which Co leta Creek is located, h ave been des ignated as attainment or non-attainment for the 1-hour S02 NAAQS.

ERM 

### 2-1 COU:"TO CREEK/ 0311696- SEPTEMBER 2015:::: 

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# ... 1 : 38 . 500 L ocal Topography Around Coleto Creek Station GO F Suez Coleto Cree k Stahon F aM i n . TX 

# ~ ERM

CO L F.TO C RE£ K / 03 11 6 96 - SEPTEMBER 2 01 52.3 

### Source Para m eters a u d Emissio n Rates For this 1-hour S02 NAAQS modeling demonstration, the only signif icant source of S02 emissions at the facility was Unit No.1. Per the 1-hour S02 Data Requ ir ements Rule and S02 Modeling TAD, the most recent 3 years of actual e miss i ons data, a long with the actua l stack h e ight of Unit No.1, were used in the modeling. The following provides a description of all Coleta Creek S02 emission sou r ces. Table 2-1 summarizes the characteristics of Coleta Creek Unit #1. The actual emissions data used in the modeling are described below: • Unit No. 1(Source 

### 10: CC_01). This un it is a coal fired utility boi ler that produces steam for the generation of e lectric ity. For this unit, three years (2012-2014) of actua l hourly emissions, stack temperature, and exhaust flow rate data were input into the model. These data were prov i d ed by GDF Suez bas e d on CEMS data collected at the site. As per the 1-hour S02 Data Requirements Ru l e, the act u al height of the stack was represented in the mode l. Othe r sources a t the s ite include emergency engines and fire pumps. These sources are used exclusively in emergency si tu ations except for approximately one hourjweek testing and were excluded from the modeling. T h e exclusion of the eme r gency engines from the 1-hour S02 modeling is based on US EPA guida n ce provided in the Mar ch 1, 2011 memorandum, "Additional C l arif i cation Regarding Application of Appendix W Mode l ing Guidance for the 1
- hour N02 National Amb ient Air Qual ity S t andard" for intermittent sources such as emergency generators. In the memo, US EPA states the following: 

### "Given the implications of th e probabilisticfonn of th e 1-hour N02 

### NAA QS discussed above, we are co ncemed that assumi11g continuous ope ration of iut ermitt e11t e miss ions would effectively impose an additional l eve l of stringenC1J beyond that level intended by the standard itself As a result, we feel it wou ld be inappropriate to impleme11t the 1-lwur N0 2 standard in such a mann er and recommend that compliance demonstrationsfor the 1-hour N0 2

### NAAQS be based 011 

### emiss ion scenarios that can logically be assumed to be relatively continuous or which occur frequently enough to cont ribute significa ntly to the annual distribution of daily maximum 1-hour concentrations . " While the memorand u m addresses the 1-hour N02 NAAQS, the form of the S02 Standard is nearly identical and the same reaso ning is common ly appl ied to the b·eatment of inte r mittent sources in 1-hou r S02NAAQS modeling. Therefore the engines were not included in the modeling demonstration. 

### Tab l e 2 -1 

### Co le t a Creek P ower Stati ou Uuit No . 1 

### - Stack Par ameters Descriptio11 Model Stack Height Exit Exit Velocity Stack Source Temperature Diameter 

### <ft> 

## I (m) (F) 

## I (K) (/f/sec) 

## I (mfs) (ft.) 

## I (tn) Unit 1 Boiler 1 CC

_ Ol 409 1124.66 

### -- 

# I
-- 

## --- 

# I

-- 20.0 1 6.1o 1. Exit temperature and exit velocity varied on an hourly basis based on actual emissions data.

ERM 

### 2 -4 COLETO CREEK I 03 11 696 · SEPTEMBER 20153.0 AIR DI S PER SION MODELING ANALY S IS ERM conducte d th e modeling analysis for Co le to Creek to quantify a mbi e nt impacts of S02 re lative to the 1-hour NAAQ5 following the p ropose d approach describe d in the 502 Modeling TAD. 3.1 Mod e l Selectio n and Application The l atest version of U5EPA's AERMOD m ode l (v.15181) was us ed for p re dicting ambient impacts f o r 1-h o ur S02. Regu l a t ory defau lt o ptio ns w e re used in th e ana l ysis. Mode l predicted impacts w e re co mbin e d with a n ambient background co nc e ntrati on a nd compare d to the 1-hour S02 NAAQS to d e te rmine th e recomme nd ed attainme nt status of th e ar ea in the vicinity of the faci li ty. 3.2 Th e 1 -Ti o u r 

### 50 2 NAAQS This study focuses on the ma ximum m ode l -predic te d 1-hour 502 impa cts of Coleta Creek and co mpar es th e m to t h e 1- h o ur S02 NAAQS. Th e new s tandard ca m e into e ff ec t in August, 2010. The fo rm of th e sta nd a rd is the 99th p erce ntil e o f th e 3-yea r ave r age 1-ho ur daily ma x imum concen trati o n , a n d th e stan dard was set to 75 ppb (196.5

**~Lg/m ).**  3.3 M eteorologic al Dat a Guidance for reg ul ato ry air quality m ode lin g re co mmends th e u se of one year of o n- s ite meteorologica l data o r f iv e years of re pr ese ntativ e off -sit e meteorologi ca l data. The 502 Modeling TAD h o w eve r, specifi es that three ye ars of m eteoro lo g ical data co n c urrent to the actual e mi ss i o n s data b e ing input into the mod e l b e us e d. S ince o n- si te data a re not avail abl e for the C o le ta C reek site, meteorologica l dat a ava il ab le from the Na ti ona l Wea th e r Service (NW5) were u sed in thi s ana lysis. T hree yea rs (20 1 2-2014 } of surface observations f r o m the NW5 tower at Vi cto r ia Regional Ai r port in Victori a, TX (WBAN No. 12912) a n d co n curre nt upp e r ai r data from Co r pus Christ i, TX (WBAN No. 12924) we re processed wi th the mos t recen t vers ion of J\ERM ET (v.15 1 81) th e meteoro logical pr ep r ocesso r for AER MOD , a lo n g with th e two pr e-processors to AERMET : A ERSURFACE (v. 1 30 1 6) and AE RMI NUTE (v.14237). AERMET was app li e d to create the two m eteo r ologica l data f il es re quired f o r input to AERMOD. AE RM ET req uir es specifica tion of s ite c har acte ri stics including s urfa ce r o ughness 

### (zo), albe d o (r), and Bo w e n r atio 

### (B o ). Th ese param e te rs were d eve loped ac co rding to th e g uidan ce provided by EPA in th e AER MOD Impl e m e ntati o n G uid e (AIG) (E PA, 2008a) u s in g AE R SU RF ACE. T h e a rea w ithin 1 km o f th e fa c il ity wa s brok e n into 12 sec tors o f 30 d eg rees eac h to analy ze th e s urface cha r ac te ri s ti cs in e ac h 3 0 degree arc a r o und th e m ain s tac k. AERMET u ses th e surface c haracte ri s ti cs in th e sec tor f r o m which th e w ind app ro a c h es th e stack as p a rt of the meteo r o l ogica l data p rocessing fo r each h ou r .

ERM 

### 3-1 COl RTO CREEK/ 0311696 ·SEPTEMBER 2015In AERSURFACE, th e various l and cover categories are linked to a set o f seasonal su rface characte ristics. As s u ch, AERSURFACE requ ires specification of the seasona l category for each month of the year. The fo llowing five seasona l categories are offered by AERSURFACE: 1. M i ds u mmer with lush vegetation; 2. Autumn with unharvested cropland; 3. Late autumn after frost and harvest , or winter with no snow; 4. Winter w ith co ntinuous snow on ground; and 5. Transitiona l spring with partial green cove rage or short annuals. The AERSURFACE r un was performed us ing the monthly temporal resolution option. The seaso n s were b r oken down as follows: • January, December: Winter with no snow. • February, March , Apri l : Tr ans itiona l spring. • May, Jun e, July, August, September: Midsummer • October, November: Autumn The p r ecipitati on was assigned to each month in each of the 3 years based on an analysis of 30 years of precipitation at Vic to ria Regiona l A irport: If a given month had monthly rainf a ll totals lower t h an th e 30th perce n tile of a ll yea rs, the month was ass i gned"dry" for the purpose o f Bowe n Ratio calc ul ations. If it had mo n t hl y r ainfa ll above the 70th perce n t ile, is was ass i gned "we t " . O th erw i se, the mon th was ass ig n ed" Av e rage". Additiona ll y, 1-m inute ASOS wind da t a, co ll ec te d at the V ic to r ia Regio n al Airport meteorologica l towe r, were processed using th e AERMINUTE p re - processor for AERMET. The data characteristics of Vic toria Airport a re shown in Table 3
- 1. F i gure 3- 1 shows the relative location of V ictoria Airport and Coleto Creek, and Figure 3
- 2 shows the 3
- year wind rose for Victo ria Ai rport. 

### Tab le 3 -1 Ch ara c teristics ofth e Vic t o ria Regio nal Ai rpo rt Meteoro l ogica l Dat a Dista11ce from Coleto Creek Statio11 20.1 miles Average Wi11d Speed 4.37m/s Perce11t Calm Hours 2.29% Da t a Comp lete 11 ess 98.75%
A ll fil es associa ted w i th t he me teo ro logica l data p r ocessing are i ncl u ded in Appendix A: T h e Elec tr o ni c Model in g Arch j ve.

ER!vl 

### 3
- 2 COLETO CR!iEK / 0311696 ·SEPTEMBER 20153.4 

### R eceptor G rid A co m p r e h e nsi ve Ca rtes ian r ece pto r g ri d ex te n d in g o ut to app r ox im a te ly 20 kilo m e te rs ( k m) f r om Co l e to Cree k was u se d in th e AER MOD m o delin g a n a l ys i s to a s s ess m ax imum g r o und
l eve ll
- h o ur S0 2 co n ce ntr a tions. T h e S02 Mo d e lin g TA D s ta t es that the r ece pto r gr id mu s t b e s uff icie nt to determin e a mbi e nt air quality in th e vicini ty o f the so urce b e in g s tudi e d. Th e 20
- k il o m e te r re c e pto r g ri d is mo r e th a n s u ff icie n t to r eso lv e th e ma ximum 1-ho ur S0 2 impacts, a nd it clea rl y illu s trat es dec reasing S0 2 co n ce n tration g radi e n ts in r e lation to th e p l a nt in a ll di rections o u t to t h e edge of the g ri d The Ca rtesi an r ece pto r g rid co nsiste d of th e f o ll o win g rece pto r sp acin g : • 5 0-m e te r s pac in g a lo ng th e fa c ility f e nce line; 

### • 100-meter s p ac in g ex tendin g fro m th e fen ce line t o 3 kilo m e t e rs; • 200 -me te r spac ing ex t e nding from 3 to 5 kil o m e te rs; • 500 -me te r s p ac ing exte ndin g f r o m 5 to 1 0 kil o m e te r s; a n d • 1,000-me te r s p ac in g ex te nd in g fro m 10 to 20 kil o m e te rs. Th e a b o v e recepto r d a t a wa s u se d with o u t m o dificati o n in th e m o d e ling. Pe r th e S 0 2 Mod e lin g TAD, a number of r ecep to rs loca t e d ove r th e Co l e to C ree k R ese rvo ir c ould h ave b ee n exclud e d fr o m the m o d e lin g do m a in becau se a m b ie nt m o nito r s co uld n o t re a so nabl y be pl ace d at th ese loca ti o n s, but th es e r ece pto rs w er e r e ta in e d in thi s an a l ys is as a m eas ur e o f co n se r v atism. Te rrain e le vations fr o m National Ele v a ti o n Data ("N ED " ) fr o m USGS were proces s e d using th e m os t rece nt version o f A ERMAP (v.11103 ) to d e v e lop th e rece pto r te rrain e l e v a ti o ns re quire d b y AE RM O D. N ED data fil es co ntain pro fil es o f te rrain e l e v a ti o ns, which in co njun c tion with rece pto r loc ations are u se d to ge ne rat e r ecep to r he i g ht sca l es. T h e h e i g ht sca l e is th e te rrain e l

ev ati o n in the v icini ty o f a re ce ptor th a t h as th e g r ea tes t influ e n ce o n di s p e rs i o n a t that loca ti o n a nd is u sed fo r m ode l computa ti o n s in co mpl ex te rr a in a r e a s. T h e nea r- f ie ld (w ithin 5 kil o m e t e r s ) a nd far
- fi e ld (full 20 km g rid) rece pto r grid s ar e s h o wn in Fi g ures 3-3 and 3-4, res p ec tiv e l y . 3.5 

### Good Engin ee rin g Practi ce S ta ck H e iglzt Aunlys is Goo d e n gine erin g prac ti ce (" G E P " ) s tac k h e i g ht is d e fin e d as the s tack h e i g ht n ecess ary to e n s ur e that emission s fro m th e stack d o n o t res ult in excess iv e concentrati o n s o f any air p o llu ta nt as a re sult o f atmospheric downwa s h , wake s , o r e ddy e ff ec ts creat e d by the sour ce, n e arby s tructures, or te rrain f e ature s. A GE P s ta c k h e i g ht a n a l ys i s was p e rf o rm e d f o r th e U nit 1 stac k u s ing th e Buildin g Pro fil e Inpu t Prog ra m (BPIP) in acco rdan ce w ith USEPA ' s g u id e lin es (USEPA 1 985). P e r th e g uide lines, th e ph ysica l GE P height, (H cEP) , is d e te rmin e d fro m th e dim e n s i o ns o f a ll build in gs which are w ithin the re gion o f infl u e n ce using th e f o ll o win g e qu a tion s , d e pending on th e co nstruction data o f th e stack:

ERiv1 

### 3-3 COLETO CREEK / 03116% ·SEPTEMBER 2015(1) Fo r s ta c ks in ex i s te nce on Janua ry 12, 1 979 and f o r w hi c h the ow n e r o r o p e ra tor had ob tained all app licable pe rmi ts or app r ova ls req uire d , I I

cFr = 2.5H, provided the owne r o r operator pr o du ces ev id e n ce that thi s equa ti on was actually reli ed on in es tablishing an em is s i on limitati o n ; 

### (2) Fo r a ll o th e r s ta c ks: H e m ' = H + 1.5L wh e re: I I = h e ight of the structure within SL of th e s ta c k w hi c h maximizes Hc E r; and L = l esse r dime n s ion (heig ht or proj ec te d w idth ) of the s tru ct ure. Fo r a s qu at s tructure, i.e., height l ess than proj ec t e d width, the f o rmula r e du ces to: 

### H cEr 

### = 2.5H ln th e a b se n ce o f influ e ncing structures, a " default" GE P stac k h eig ht is c r e ditable up to 65 m e t e rs (213 feet). A s ummar y o f th e GEP stack height analyses is prese nt ed in Ta bl e 3 -2 . As d esc ri bed in the S02 Mode lin g TAD, when modeling actual e mi ss ions in o rd e r to d e te rmin e the attainment status o f th e fa c ility when co mpared to the 1-hour S02 NAAQS, th e full height of a ll s tacks is a ll owed in th e m ode ling r egardless of thei r GEP Fo rmula H e ights . T h e refo re, th e s ta ck was model ed with its actua l s ta c k h e i g ht in th e analysis. The h e ights and locatio n s of a ll stru c tur es includ ed in th e GEP analys is, as w e ll as the main stack, a re s h own in Fi g ure 3-5 . 

### Table 3-2 

### S t munary of Cole to Cr eek Station GEP A nalysis Emissiou Stack Coutrolliug Btlildi, gs 

### I Bttildi"g Proj ected GEP Fonnllla H e ight So ttr u ( m) S tructtlr es He ig lt t ( m) Width (m) Height (m) CC

_Ol 124.66 U nit 1 Ge nerator Bldg. 85.04 68.73 188.13

ERM 

### 3-4 CO I. E TO C REEK / 03 11 696- SEPTEMBER 20 1 53.6 Ambie11t SOz Ba c kgrou11d Datafor Cumula t ive Modeliug It was assumed after initial modeling that model-predicte d impacts from Co le ta Creek would excee d th e 1-hour

**S~** Sign if ica nt Impa ct Level (S IL) of 7.9 J.lg/m 3 . As a result, ambient background data from the closest, m os t re pr ese ntativ e S02 monitor to Co l eta C reek was downloaded from the EPA AirData ambient mon i to rin g website 3. A rev iew of th e data showed that th e most rep resen tativ e m o nito r for us e in th e modeling is th e Tuloso Corpus Christi monitor locate d at 9860 La Branch in Corpus C hri sti (Mon itor 10# 48-355 -0026). This monito r is so m e what co n servative for u se in this ana lys is , be in g s ite d mu c h cl ose r to industri a l ac ti vity than Co l e ta C reek is to o th e r sources of S02 . To conf irm that the m o n i tor did not unde rstate the background in the vicinity of Cole ta Creek, th e EPA 2011 National Emi ss i ons Inv e ntory was re vi e w e d for 50 2 e mi ss ions n e ar the fac ili ty a nd t he monito r . Tab le 3-3 shows the results. Th e tab l e s h o ws that th e monito r had ove r 300 to n s of S02 e mis s i o n s w ithin 10 km and nearly 1000 tons within 25 km, while Co l eta Cree k h ad on l y 2.5 to n s ofS02e mi ss io n s with in 25 kilometers. Despite th e co n se r vatism o f the monitor, it wa s used for thi s m o d e ling analysis. Table 3-3 Comparison of S 0 2 Emissio n s n ear Cole to Cr eek aud Monitor S it e SO z 

### tpy (NEI 2011 ) witlri11 : 0-10 km 10
- 25 km 25
-5 0km Co le t o Cree k 0.0 2.5 482.1 Co rpu s C hr isti Monitor 322.7 623.6 60.7 EPA g uid ance a ll ows s imul ation of background va lu es that va ry by season and hour of day that co uld s imul a te a lower value than the 99th p e rce nti l e. The m ode lin g was pe r formed with a set of seaso n a l diu rn al values dev e loped using th e me tl1 odo logy d esc ri bed in th e USEPA Ma rch 1 s t , 2011 C l a rifi cati o n Me m o randum for 1-hour N02 M o d e lin g. T h o u g h tlUs m e morandum primaril y addresses N02 mod e ling, page 20 de sc rib es the process f o r deve loping seaso nal diurna l backgro und va lu es for S02 as we U. Th e loca ti o n o f th e se lec t e d a mbi en t m o nitor re lative to Co l e to C reek is s hown in Figure 3
- 6. The seaso na l diurn a l va lu e s used are show n in Table 3-4.

3 ht tps ://ofmext .epd.gov/AQD t\I RS/agd mrs. h tml
ERM 

### 3-5 COLETO CREEK I 0311696 -SEPTEMBE R 2015

### Table 3-4 Seaso u a l D i u rual 

### 50 2 

### Couce u tratious at Corp u s C h risti Mo u itor 

### ( p

fY' m 3 ) 

### Hortr 1 

### Wiuter Spri11g Summer Fall 1 3.53 1 . 46 1.40 3 .42 2 3 .37 1.52 1.49 4 . 14 3 2.92 1.57 1.34 2 . 91 <I 3.95 1.81 1.48 3 . 23 5 3.26 1.69 1.26 4 . 45 6 3.39 1.87 1 . 39 3 . 33 7 3 .42 1.52 1.63 3.52 8 3.8 1 1 .99 ' 1. 77 3.68 9 3.65 1 .99 1.4 3 3.43 10 4.12 2.32 1 .55 2.98 11 4 .96 2.82 2 .02 4.09 12 5.57 2.80 2 .7 1 4.85 1 3 5.87 3.07 2.59 4 . 42 14 4.74 3.00 3.25 4 . 10 15 4 . 96 4.87 3 . 35 4 . 65 16 5.18 4.33 -1 . 58 5.().1 17 6.59 3.92 3 . 18 3 . 89 1 8 4.71 3.72 2.9-1 4 . 19 19 4.18 219 2.-11 4.61 20 8.05 2.17 3. 2-1 5.58 21 5 .34 2.06 1 . 84 3.64 22 4.80 3 .26 1 . 61 3 .38 23 4 . 63 1 .72 1.64 2 . 92 2 4 3.8 1 1 .94 1. 63 3 . 22 1. Hours in AERMOD are define d as h o u r-ending . 3.7 

### R ev iew of No n- Fac ili ty S o urcesfo r Cumula tive Iu ve u to 1 · y Sec t ion 4.1 of th e S02 Mode ling TAD di sc u sses t h e c rit e r ia for t he add i ti o n of ma j o r SO z sources in th e reg i on fo r cum ul a ti ve mode lin g p u rposes w hen det e rm ining th e reco mm e n ded atta inm e nt status of the area sur r ound in g a facil ity as d esc ribe d in the 1-hour S02 Data R

e q u ire me nts Rul e. The TAD describes sources that shou ld be includ e d in the model in g as those ex p ect e d to hav e an impact on the air q u ality in th e vicinity of th e source be in g studied, in th is case Co l e ta Creek. Additional l y, the TAD states that exce pt in cases where numerous smaller so u r ces are close together in th e s tu dy area , cons i d e ration of sources to in clude sho ul d beg in at sources with emissions in excess of th e th res h o ld se l ec t ed in th e Data Requirements Rule (2000 tpy). The 2011 EPA Nationa l Emissions Inven tories (NE I ) was r ev iewe d to deter min e can d i da te maj o r so urc es. For t h e p urpose of this study, a ll majo r so u r ces of S02 w ithin 50 kilomete rs of Co leta Creek that had at l east 2000 tons of S02 e m issions w e r e conside r ed for incl u sio n in the mod e ling. No f ac ili ties with in 50 k il ometers we r e fou n d to h ave e mitte d at leas t 2000 t ons of

ERM 

### 3-6 COLETO CRE.EK / 031 1696 · SEPTEMBER 2015S02 in 2011. In fact, the only source with greater than 100 tons of S02 within 50 miles of Coleto Creek was Seadrift Co k e LP, located 46.6 km away in Seadrift, TX, with 410 tons. Seadrift Coke was not exp l icit l y includ ed in the mod e lin g for the following reaso ns: • Seadrift Coke had em issions far low e r than that o f the 502 Data Requ ireme nts Rule threshold. • The March

**~1 ,**  2011 EPA clarification m e morandum for modeling N02 and 50 2 4 states that" .. Even accounting for som e te rrain influences o n the l ocation and g r ad ie nts of maximum 1-hour concentrations, th ese considerations suggest that the emphasis on determining which nearby sourc es to includ e in the mod e lin g analysis s hould focus on the area withjn about 10 k il ometers of the project location in m ost cases ... " Seadrift Coke is more than 4 times that distance from Co l e to Creek. • The relativ e l ocations of th e faciliti es: Wind blowing from Coleto C ree k to Seadrift Coke is on a b e aring of 118 degrees, while wind b lowing from Seadrift Coke to Coleto would b e on a bearing of 298 degrees. A re vi e w of the 3 years of wind data {2012-2014} used in the modeling shows that the wind blows between the two fac il ities only about 7 percent of th e tim e, and of that 7 percent on ly a total of 6 hours out o f the 3 years of data had sufficient wind speed (12.9 m / s} to ca r ry a plume from one facility to the othe r in one hour. • The concent r ation gradient from Co l e t o C r eek impacts drops sharp l y to th e east of the facility (See F i gure 4-1), such that the impacts f r om Coleto Creek would n ot be expected to inte ra ct with those from Seadrif t Coke. • The Co rpus Christi ambient monito r was shown to be conse rvativ e in Sectio n 3.6 Therefore, no ot h e r facilities were explici tl y includ e d in the modeling, but instead a conservative ambi e nt concentration from th e Corpus Christi monitor was added to the impacts from Coleto C r eek to represent other sources in the area.

• http ://www .epa.gov / sc ram001 / guidance/ clarifi ca ti o n / Ad d iti o naJ_ Clari!ications

_ AppcndixW

_ Hourly-N02- NAAQS_FlNAL

_03-01-20ll . pdf

ERM 

### 3-7 CO LETO C R!lEK / 0311696 • SEPTE..v!BER 2015

### F i g u re 3 -1**sf~~~** AntoniO

ERM 

### Rel ative Loca ti ort ofCole t o C r

eek aud V i c toria R e gioual Airport

l egend



# * Coleto Creek Station 

### A Meteoro l og ica l Towe r



### 3-8 Relative Loca ti on of Coleto Creek Station and Meteoro logical Site GDF Suez . Coleto Creek Station Fannin, TX 

# \j ERM

COLETO CREEK/ 031 1696- SEPTEMBER 2015

### Figur e 3-2 Thre e-year Wind Rose (2012-2014): Victoria Regioual Airport

**ll>O~P\.OT** 3- Year W i nd Rose : V Ic t o ria Reg i onal Airport 2012-2014



### l-

**~>IIS** Resullan l V ec101 11 5dog 32% NORTH

' ; soUT H

D ATA PERIOO Stan Date : 1 ' 1 12012- 00 : 00 End Date : 12131 120 14 • 23:00 CO!.'PANY tiA>.I E ERM UOOEL£R R. Hamel 

# ·--

**------------------~---- ---**  C ALMWWOS JOTAI. COUIIT 2 . 2 9% 25976 hrs . AVG WINO SPEED Q.\TE 4 . 37 m!S 8 / 10 / 2015 WRPtOT Votw L.._, Enwonmoroat Sol!wolt

ERM 

### 3-9 DSP'-'Y Wind Spe ed Dlrecllon ( blow i ng f r om )



# J EAST

WINO SPE ED fin' S ) • ,. II 1 0 • 8.80·11 10 • 5.70 8.80 • 360-570 

### D 210 -J. 6o 

### D ono-210 Calms 2 29'•



# ~ ERM PROJECT NO

COLEW C REE K / 031 16%- SEPTEM BER 2015

### Figure 3
- 3

EHM 20 15 

### Ne ar-Fie ld Model Receptors

Legend

o Risk Receptors
* Unit



### 3-10 Near F ield ( 5 km) Receptors used in Coleto C reek GDF Suez Cole to Cree k Station Fannin, TX 

# \_, ERM

COLETO CREEK I 031 1 696 •

**S~ IB**  **ER**

### Figur e 3-4

ERM 2015 

### Far-Field Model R eceptors

3-11 GDF Suez Coleto Creek Station Fann in. TX 

# \v ERM CQ LJ , - ro CREEK / 0311696 -SEPTE MB ER

### Figure 

### 3-5 Structures I11cluded 

### i11 t lt e Co l eto Creek GEP A naly s i s PROJECT TillE: Buildings Includ ed In the Coleto Creek GEP Analys is

0 on 

### "' 

## :::: - ..,

0 on v 

### :::: - ;;;

COIAMHITS.

ERM 20 1 5 

# Ma **chi,.Sho~** 

# D

H gt. • 28'

Fabrbtlon ___...?. Building

**~** HgL • 106'

6741 350
SOURCES 1 Unit I Stocl<

**Hg ~;**  409'

11ECEPTORS: 7644 

# /

6741 400 UTM E ast !m ) COW'AHYW.ME . ERM MOOELER R. Hamel SCALE · 0 DATE 8/1112015


### 3-12 1 :1. 500 0.05 km 

# '"'- G e11<1 11101 Bldg . Tltr I HgL • 100' Tltr 2 Hg1 . • 202' Tltr 3 H gt • 263 '



# ~ ERM PROJECT NO

COLt"TO CREE K I 03 11 696 • SEPTB IBER

### Figure 3-6

ERM 2015 

### R e lati ve Locatiotr ofCol e ta Cree k S tation and Corpu s Chri s ti Monitor

Coleto Creek S tation 

### ¢ 502 Monttor



### 3-13 R elative Locat ion of Coleto Creek St a ti on and Corpus Christi S<n Monitor 

# \._, GOF Suez Cole to Creek Station Fannm . TX ERM

COLCIO CREEK I 0311696 • SF.PTEMBER

### 4.0 MODELING RESULTS 

### The modeling res ults are shown in Table 4-1 below. The m ode led design value rep rese nts th e mod e l ed 3
- ye ar average of th e 99th p e rcen til e, maximum daily 1-hour ave ra ge impac t for Coleto Creek, which is th e n added to th e amb i ent background co n ce ntr a tion and the total impact compared to the NAAQS to d e monstrate attainment. Contours of th e pr e di c ted impacts , as well as th e l ocation of the maximum predicted impac t of 111.0 JJ.g/ m 3, are s hown in Figure 4-1. Th e table s hows that model predicted impac ts from Cole to Creek, when modeled using th e most rec e nt three years of actual e missions data and added to a repr ese ntativ e ambient b ac kground concentra tion, ar e b e low th e le vel of the 1-hour S0 2 NAAQS. 

### Table 4-1 1-hour S0 2 

### Modeliug R es ults for Co l eta Creek Statio u Co l e t a Cree k Coleta Creek 1- llr . S 0 2 B e l ow Source a 11d O nl y B ackgro un d NAAQS NAAQS? Coleto Creek Sta ti on 106.8 

### 11g/m3 111.0 

### 11g/m3 196.5 

### 11g/m3 Yes (40.8 ppb) (42.4 ppb) (75 ppb) 

### 4.1 

### Conclusions The air disp e rsion modeling performed as de sc ribed in 

### this report confirms that the 

### SOz e mi ss io n s from Co l eto Creek Power Station, w h en adde d t o conservative ambient background concen tra tion , resu lt in m aximum predicted impacts below the 1-hour S02 Nationa l Ambient Air 

### Quality Standard. Th e re for e, an attainment designation for Goliad County and th e 

### surro unding area i s r ec ommend e d.

ERM 

### 4-1 C OI.IITO CREEK/ 0311696- SEPTEMBER 2015

### Figure 4-1

E.RM 

### Coleta C r eek St atiou l- lwur S0 2 

### Impact Contours



# + M ax. Predict ed Impact 

### [:::::J Fence Line Impac t Co ntour s


### 4-2 AERMOD Pred i cted 1-hou r S0 2 I mpact Contours GO F S uez Coleto Crll1lk Station Fanni n . TX 

# "-' ERM

COLETO CREEK I 03 11 696 ·SEPTEMBER 20155.0 REFERENCES U.S. Environmental Protection Agency. (USEPA 2005) Guideline on Air Quality Models (GA QM , 40CFR Appe ndix W) , November, 2005 U.S. Enviro nm ental Protection Agency. (USEPJ\ 2009) AERMOD Impl e m e ntation Guide, AE RMOD Implem e ntation Wo rk g r ou p . Ma rch 19, 2009. U.S. Envir o nm e nta l Protection Agency. (USEPA 2011) USEPA mem o e ntitl ed" Additi ona l C larificati o n R ega rdin g Ap plication of Appe ndi x W Modeling Guidance for the 1-hour N0 2 National Ambient A ir Quality Standard", USEPA, Office of Air Quality Pl a nnin g and Standards, Ra l e ig h, NC. March 1 , 2011. U.S. Environmental Protection Agency. (USEPA 2014) "S02 NAAQS Des i g nations Modeling Tec hnical Ass is ta nce Document (Draft)," December 20 1 3; U.S. Environmental Protection A genc y. (USEPA 2014)

**"S~** NAAQS D es ignations Mo nito rin g Tec hnical Ass ista n ce Doc ument (Draft)," December 2013; U.S. Environmental Protection Agency. (USEPA 2014) "Data R e quirem e nts Rule for the 1
- Hour Sulfur Dioxide (S02) Primary Nationa l Ambient Air Qua lity Standard (NAAQS)," Final rule, Augus t 11, 2015; U.S. Environmental Prot ec tion Agency. (USEPA 2014) "Guidance for 1-hour S0 2 No nattainm e nt A rea S IP S ubmissions," Ap ril 23, 20 1 4; and Texas Commission on Environme ntal Quality (fCEQ 2015) "Air Qu a li ty Mode ling Guidelines, APDG 6232", A pril , 20 1 5.

# Appendix A Electronic Modeling Archive