## Ameren Labadie Plant Labadie, Missouri Evaluation of Compliance with the 1-hour NAAQS for S0 2 

## September 3, 2015

Conducted by: Steven Klajka , P.E., BCEE Wingra Engineering, S.C. Madison, WisconsinEvaluation of Complian c e with the !-hour NAAQSfor S0 2 S e

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1. Introduction Wingra Engineering , S.C. was hired by Sierra Club to conduct an air modeling impact analysis to help the U.S. Environmental Protection Agency (USEPA) and state and local air agencies identify facilities that are likely causing exceedances of the 1

- hour sulfur dioxide (S0 2 ) national ambient air quality standard (NAAQS). This document describes the results and procedures for an evaluation conducted for the Ameren Labadie Plant located in Labadie, Missouri.
To ensure the modeling analysis reflected the cumulative concentration of S0 2 emissions, it included emi s sions from the following additional sources of S0 2 emissions located within 50 kilometers of the Ameren Labadie Plant:

• Purina Animal Nutrition Center- Gray Summit, Missouri • N.B. West Contracting Company Inc.NC- Pacific, Missouri
The dispersion modeling ana l ysis predicted ambient air concentrations for comparison with the 1- hour S0 2 NAAQS. The modeling was performed using the most recent version of AERMOD , AERMET, and AERMINUTE, with data provided to Sierra Club by regulatory air agencies or obtained through other publicly-available sources as documented below. The analysis was conducted in adherence to all available USEP A guidance for eva luating source impacts on attainment of the 1

- hour S02 NAAQS via aeria l dispersion modeling, including the AERMOD Implementation Guide; USEP A's Applicability of Appendix W Modeling Guidance for the 1-hour S02 National Ambient Air Quality Standard, August 23, 2010; modeling guidance promulgated by US EPA in Appendix W to 40 CFR Part 51 ; USEPA's March 2011 Modeling Guidance for S0 2 NAAQS Designations; 1 and USEPA ' s December 2013 S02 NAAQS Designations Technical As s i stance Document ?


### 2

. Compliance with the 1

- hour S 0 2 NAAQS


### 2.1 1

- ho u r S0 2 NAAQS
The 1-hour S0 2 NAAQS takes the form of a three-year average of the 99th percentile of t he annual di s tribution of daily maximum 1-hour concentrations , which cannot exceed 75 parts pe r billion (ppb)

. 3 Compliance with this standard was verified using USEPA' s AERMOD air dispersion model, which produces air concentrations in units of Jlg/m 3

. The 1-hour S0 2 NAAQS of 75 ppb equa l s 196

. 2 Jl g/ m 3

, and this is the value used for determining whether modeled impacts exceed the

1 h ttp: / / www.epa . gov/sc ramOO l/s o2

_ modeling__guidance

. btm 2 ht tp: //www . e pa.gov / oaqp s OO l / sulfurdioltide / pdf s/S02ModelingT AD.pdf 3 USEPA , Applicability of Appendix W Modeling Guidance for the !-hour S0 2 National Ambient Air Quality Standard , A u gus t 2 3 ,2 010.Evaluatio n of C

o mplian ce with the /-h o ur NAA QS fo r S O z Septe m ber 3, 2015 Page3 NAAQS. 4 The 99 1 h percentile of the annual distribution of daily maximum 1 -hour co nc e ntrati o n s corresponds to the fourth-highest value at each r ecep tor for a given year . 

### 2.2 Modeling Re s u lt s Model results for all so urce s included in the S0 2 ana lysis are s ummari zed in T ab le 1. Re s ults are provided fo r Labadie alone and for a ll sources combined.
Model i ng resu lts for Ameren Labadie Pl ant and the ot h er two faci liti es are summarize d in Table 1

. It was determined that based on eithe r current a llo wab le emissio n s or measured actua l emiss ion s, the Am eren Labadie Plant is es timated to create downwind S0 2 concentratio n s which exceed the 1

- hour NAAQS

. More sp ecifica ll y, the modeling re su lts presented in T ab le l , show exceedances of the NAAQS by the plant 's allowable and actual emissions. " Allowable " is the peak emission r ate from eac h unit as approved by the curre nt a ir quality operation permit for the facility. "Actua l " arc the measured e missions for each hour b etween J anuary 1 , 2012 and December 31,2014 as taken from USEPAAir 

### Market s Program Data. 5
Air qua li ty impacts in Missouri are based on a background concentrat i on of23.5

**gl .**  This is the 2011-13 design value for Monroe County , Missouri

- the lowest measured background co nce ntration in the s ta t e . This is the most recently available design val ue . See Section 

### 5 for further discussion of the background concentra tion s u sed for this analys is.
Table 1

- S 0 2 Modeling R es ult s for Ameren Labadie Plant Modeling Analysis
99th Percentile ! -ho ur Daily Maximum

**gl )**  Co mplies with Emission R a te s Facility Impact Background T otal NAAQS NAA QS ?

Allowab le Labadie 2,559.7 23.5 2,583.2 196.2 No

Acrual Labadie 212

.2 23.5 235 .7 196.2 No Act ual All 212.2 23.5 235

. 7 1 96.2 No

4 The ppb to

**~glm 3**  c on version is round in the so urc e co d e to AERMOD v. 14134, s ubroutine Modules. The conversion calcu lation is 75/ 0 .3823 

### = 1 96.2

**glm •**  s http: //ampd.e pa. gov/ ampd/E valuat io n of Co m p lia nce wit h t

he /

- hour NAA QS fo r S 0 1 S e

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The e mi ssions u sed for th e modeling analysis are s umm a ri zed in Tabl e 2

. 

### Table 2

- Modeled S0 1 

### Emissions 6
Stack Unit



### lD lD SOl Bl S02 B2 S03 B3 S04 B4 Stack Total A ll Units Allowable Emissions 1-hour Average (lb slhr) 29 , 678.4 29,678.4 29 , 3 1 3.6 29,3 1 3.6 1 17 , 984

. 0
B as ed on the modeling res ults , Table 3 provide s th e e mission r eductions from current allowable r a t es necessary to achieve c ompliance with the 1-hour NAAQS. This assumes a one-hour averaging p e riod for the emi s sion rate and that the emi s sion rate is binding at all time s . However , given the c on s ervative aspects of this modeling protocol , it is extreme ly likely that this l imit i s too high to protect t h e NAAQS. For exa mp le, s tartup o r shutdown periods were n ot eva lu ate d. During these periods, decrea s ed ga s ve l oc it ie s and temperatures may l ead to greate r ambient impacts at gro u n d lev e l. Further, the hypoth e tical emiss i on limita tion in Table 3 would allow Am eren Labadie Pl ant to c on s ume the entire N AA QS , leaving little to no room for any other source ofS0 2 in the area. No m ar gi n of safety ha s b e en in c luded in the hypoth e tical emis s i on limi tation.



### Table 3

- Required Emission Reductions from A m ere n Labadie Plant for Comp l ian ce with the 1- hourNAA QS for S01 Ac ceptable Impact Required Required Required (NAAQS

- Background) Total Facility Tota l Faci l ity 99th Percentile R e duction Bas e d on Tota l Facility 1 -hour Average E mi s sion Rate 1-hour Dail l Max Allowable Emi ss ions ( l bslhr) Emi ss ion Rate ( Jl g/ m ) (% ) ( lb s/ mmbtu ) 172.7 93 % 7 , 960

. 2 0.43 Predicted exceedances of the !-hour NAAQS for S 0 2 bas ed on allowab le em i ssions extend throughout the region to a maximum distance of 50 ki l omete r s. F i g ure 1 s hows the extent ofNAAQS violations based on allowa bl e emi ss ion s from the A.meren L abadie Plant. Figur e 2 s hows the e xte nt o f N AAQS violation s base d o n actua l hourly emi ss ion s from all s ourc e s .

6 A ll owa bl e e mi ss ion s are base d o n the 4. 8 lb s/ mmbtu li mi tati o n in Title V Pennit to Op e rat e N o . OP20ll

- 020 i s su ed byEvaluati o n of C

o mplian ce w ith th e 1-hour NAA QS f or S0 1 Se

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2

. 3 Conservative Modelin g Assumptions A dispersion modeling ana lysis requires the selection of numerous parameters which affect the predicted concentrations. For the enclo s ed analy s is , several parameters were selected which underpredict facility impacts. A ss umptions used in this modeling analysis which likely under

- estimate concentrations include the following:

• Allowable emissions are based on a l imitation with an averaging period which is greater than the 1

- bour average used for the S0 2 air quality standard. Emissions and impacts during any 1

- hour period may be higher than assumed for the modeling analysis

.
• No consideration of facility operation at less than 100% load. Stack parameters such as exit flow rate and temperature are typically lower at less than full l oad , reducing pollutant di sper s ion and increas ing predicted air quality impacts.

• No consideration of building or structure downwash. Th e se downwash effects typically increase predicted concentrations near the facility.

• Except for Purina Animal Nutrition Center and N.B. W e st Contracting, no consideration of other off-site sources. These other off

- site sources of S0 2 will increase the predicted impactS.Evaluation of Compliance with the 1-hour NAAQSfor S0 1 Se

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emb e r 3, 2015 Page6

§ :;: N ., ·c-- ' ...,_



### 1-hour 802 Concentrations (ug per cubic meter)
- All colored areas exceed the NAAQS.

I 

### 196 400 800 1200 1600 Figure I -R egional View of Impacts Due to Allowab le Emissions from Ameren Labadie PlantEvaluation of Compliance with the 1-hour NAAQSfor S0 1 September 3, 2015 Page 7

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0 "' Ameren Laba clie Plant

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### ' GGJOOO 1-hour average S02 concentrations (ug per cubic meter)
- All colored areas exceed the NAAQS. 

### ' 

### 196 225 

### Figure 2

- Re g ional V iew of Impact s Du e to Actual Em iss ion sfrom All SourcesEvaluation of Compliance with the 1-hour NAAQS for S0 2 September 3 , 2015 Pag e 8


### 3. Modeling Methodology
3.1 Air Dispersion Model
The modeling analysis used USEPA's AERMOD program, v. 14134. AERMOD, as available from the Support Center for Regulatory Atmospheric Modeling (SCRAM) website, was used in conjunction with a third-party modeling software program, 

### AERMOD View, sold by Lakes Environmental Software.
3.2 

### Control Options
The AERMOD model was run with the following control options:
• 1-hour average air concentrations
• Regulatory defaults
• Flagpo le receptors To reflect a representative inhalation l eve l , a flagpole height of 1.5 meters was used for a ll modeled receptors. This parameter was added to the receptor file when running AERMAP, as described in Section 4.4.
An evaluation was conducted to determine if the modeled facility was loc ated in a rural or urban setting using USEPA's methodology outlined in Section 7.2.3 of the Guideline on Air Quality Mode l s. 7 For urban sources, the URBAN OPT option is used in conjunction with the urban population from an appropriate nearby city and a default surface roughness of 1.0 meter. Methods described in Section 4.1 were used to determine whether rural or urban dispersion coefficients were appropriate for the modeling analysis.
3.3 

### Output Options
The AERMOD analysis was based on three years of recent meteorologica l data. The modeling analyses used one run with three years of sequentia l meteorological data from 2012-2014. Consistent with USEPA's Modeling Guidance for S02 NAAQS Designations, AERMOD provided a table of fourth -hi gh 1-hour S0 2 impacts concentrations consistent with the form of the 1-hour S0 2 NAAQS. 8
Please refer to Table 1 for the modeling results.

7 US EPA , Revi s i on to the Guide line on Air Quality Models: Adopti o n of a Preferred General Purpose (Flat and Complex Te rrain) Dispersion Model and Other Revisions, Appendix W to 40 CFR Part 51 , November 9 , 2005

. 8 U S EPA, Area Designations for th e 2010 Revi s ed Primary Sulfur Dioxide Nationa l Ambient Air Quality Standards , Atta c hm e nt 3 , March 2 4 , 2011 , pp. 24-26.Evaluati o n of Complian ce with the 1-hour NAAQSfo r S0 2 September 3, 2015 Pag e 9


### 4. Modellnputs
4.1 Geographica l I np ut s The "ground floor " of all air dispersion modeling analyses i s establishing a coord i nate system for identifying the geographical location of emis s ion sources and receptors
. These geographical l ocations are used to detennine local c haracteristics (such as land use and e levation), and also to ascertain source to receptor distances and relationships.
The Universa l Tran sverse Mercator (UTM) NAD83 coordinate system was used for identifying the easting (x) and northing (y) coordinates of the modeled sources and receptors. Stack locations were obtained from facil i ty permits and prior modeling files provided by the state regulatory age nc y. T he s tack locations were then verified using aerial photographs.
The facility was evaluated to determine if it shou ld be modeled using the rural or urban dispersion coefficient option in AERMOD. A Geographic Inf ormation System (G IS ) was u sed to determine whether rura l or urban dispersion coefficients app l y to a s it e. Land us e within a three-ki l ometer radius circle surrounding the faci lity was considered. USEPA guidance states that urban dispersion coefficients are used if more than 50% ofthe area within 3 kilometers has urban l and uses. Otherwise, rural dispersion coefficients are appropriate. 9
USEPA ' s AERSURFA CE v. 13016 was used to develop the meteorological data fo r the modeling analysis. This model was also used to evaluate s urrounding land use w ithin 3 kilometers. Based on the output from the AERSURFACE, app r oximately 5.5% of sWTounding land use aro und the mode led faci li ty was of urban land u se types includin g Type 21 -Low Intensity Residential, Type 22

- High Intensity R es id entia l and Type 23

- Commercia l 

### I Industrial 

### I Transportation.
This is l ess than the 50 % value considere d appropriate for the use of urban d i spe rs ion coefficients. Based on the AERSURFACE analys i s , it was concluded that the rural option would be used for the modeling summarized in this report
. Please refer to Sect i on 4.5.3 for a discu ssion of the AERSURFACE analysis.

9 USEPA , Revision to the Guideline on Air Quality Model s: Adoption of a Preferred General Purpo se (Flat and Complex Te rrain) Dispersion Model and Other Revisions, Appendix W t o 40 CF R Part 51 , November 9 , 2005 , Section 7.2.3.Evaluation of Complianc e with th e 1

- hour NAAQSfor S0 2 September 3, 2015 Pa ge 10


### 4.2 Emission Rates and Source Parameters
The modeling analysis considered S0 2 emissions from the Labadie, and the other two facilities. Other off-site sources were not considered. Concentrations were predicted for the scenarios shown in Tables 1 and 2: 1) allowab l e emissions based on the current permit issued by the regulatory agency, and 2) actual hourly emissions measured at the Ameren Labadie Plant each hour between January 1 , 2012 and Decemb er 31 , 2014 as taken from VSEPAAir Mark e ts Program Data. 10 Actual emissions for Purina Animal Nutrition Center and N.B. West Contracting were reported to Missouri DNR for 20 13.
Stack parameters and emissions used for the modeling analysis are summarized in Table 4.
The above s tack parameters and emissions were obtained from regulatory agency documents and databases identified in Section 2.2. The analysis was conducted based on 100% operating load using maximum exhaust flow rates and temperatures. Operation at less than full capacity loads was not considered. This assumption tends to under-predict impacts since stack parameters such as exit flow rate and temperature are typically lower at less than full load , reducing pollutant dispersion and increasing predicted air quality impacts

. Stack location , height and diameter were verified u s ing aerial photographs, and flue gas flow rate and temperature were verified using combustion calculat ion s .

10 http: //ampd.epa.gov / ampd/EvaluationofCompliancewiththe1-hourNAAQSforS01September3.2015Page11Table4-FacilityStackParametersandEmissions11FacilityStackSOlDescriptionBoilerlXCoord.[m)688352.17YCoord.[m]4270445.59BaseElevation[m]149.66ReleaseHeight[m]213.36GasExitTemperature[°K]443.065GasExitVelocity[m/s]34.72InsideDiameter[m)6.248AllowableEmissionRate[g/s]3,739ActualEmissionRate[g/s]-FacilityVolumeSourceDescriptionXCoord.[m]YCoord.[m]BaseElevation[m]ReleaseHeight[m]SideLength[m]BuildingHeight[m]InitialLateralDimension(m]InitialVerticalDimension[m]ActualEmissionRate(g/s)LabadieS02S03Boiler2Boiler3688387.01688435.474270400.44270332.33149.66149.66213.36213.36442.49433.20435.55834.5176.2486.2483,7393,693--PurinaEU10Boiler689107.654262863.717251.524-1.164.650.0409N.B.WestS04EOlEP5NB2Boiler4GeneratorDryerHeater688439.28688439.28695174.86695174.864270327.434270327.434262540.034262540.03149.66149.66159159213.369.147.622.74441.708866.483376.15298.1534.9467.1125.5260.0016.2480.3050.9140.2443,693- ---0.0023080.01160.01759N.B.WestEP17N.B.WestDragSlatConveyor695196.754262475.0715951.524-1.164.650.0738511StackparametersobtainedfromMissouriDNRmodelingfile:AmerenMissouriLabadieFacilityHourlyEmissionsFileRun12-1420kmmultitierrecgridincludingInteractivesources.Evaluation of Compliance with the 1-hour NAAQSfor S0 2 S e

ptember 3 , 2015 Pag e 12


### 4.3 Building Dimensions
This modeling analysis did not address the effects of downwash and this may under-predict impacts. 

### 4.4 Receptors
For Ameren Labadie Plant, three receptor grids were emp lo yed:
1. A 1 00-meter Cartesian receptor grid centered on Ameren Labadie Plant and ext ending out 5 ki l ometers. 2. A 500-meter Cartesian receptor grid centered on Ameren Labadie Plant and extending out 10 kilometers. 3. A 1 ,000 -meter Cartesian receptor grid centered on Ameren Labadie Plant and extending out 50 kilometers. 50 kilometers is the maximum distance accepted by USEPA for the use of the AERMOD di spersion model. 12
A flagpole height of 1.5 meters was used for a ll these receptors. Elevations from stacks and receptors were obtained from Nationa l Elevation Dataset (NED) GeoTiff data. GeoTiff is a binary file that includes data descriptors and geo-referencing information necessary for extracting terrain elevations. These elevations were extracted from 1 arc-second (30 meter) resolution NED files. The USEP A software program AERMAP v. 11103 is used for these tasks. 

### 4.5 Meteorological Data
To improve the accuracy of the modeling analysis , recent meteorological data for the 2012-2014 period were prepared using the USEPA's program AERMET which creates the model-ready surface and profi le data files r equired by AERMOD. Required data inputs to AERMET included surface meteorological measurements, twice -daily soundings of upper air measurements, and the rnicrometeorological parameters surface roughness, a lbed o, and Bowen ratio. One-minute ASOS data were available so USEPA methods were used to reduce calm and missing hour s. 13 The USEPA softwa r e program AERMINUTE v. 14237 is used for these tasks.
This section discusses how the meteorological data was prepared for use in the 1-hour S0 2 NAAQS modeling analyses. The USEPA software program AERMET v. 14134 is used for these tasks.

12 US E PA, Revi s ion to the Guideline on Air Quality Mode l s: Adoption of a Preferred Gen e ral Purpose (Flat and Compl ex Te rrain) Dispersion Model and Other Revis i ons, Appendix W to 40 CFR Part 51 , Section A.l.(l) , November 9 , 2005. 13 U S EP A, Area Designations for the 2010 Revised Primary S ul fur Dioxide National Ambient Air Quality Standards, Attachment 3 , March 24 , 2011 , p . 19

.Evaluation of Complianc e with the 1

- hour NAAQSfor S02 Sept e mb e r 3, 2015 Pa ge 13


### 4.5.1 Surface Meteorology
Surface meteorology was obtained for Spirit of St. Louis Airport located near the Ameren Labadie Plant. Integrated Surface Hourly (ISH) data for the 2012

- 2014 period were obtained from the National C limatic Data Center (NCDC). The ISH surface data was processed through AERMET Stage 1, which performs data extraction and quality control checks.


### 4.5

. 2 Upper Air Data Upper-air data are collected by a "weather balloon" that is released twice per day at selected l ocations. As the balloon is released , it rises through the atmosphere, and radios the data back to the surface

. The measuring and tran s mitting device is known as either a radiosonde, or rawindsonde. Data collected and radioed back include: air pressure , height, temperature, dew point, wind speed, and wind direction. The upper air data were processed through AERMET Stage l, which performs data extraction and quality contro l checks.
For Ameren Labadie Plant, the concurrent 2012

- 2014 upper air data from twice-daily radiosonde measurements obtained at the most representative location were used. This location was the Lincoln, Illinois measurement station. These data are in Forecast Systems Laboratory (FSL) format and were downloaded in ASCII text format from NOAA's FSL website. 14 All reporting levels were downloaded and processed with AERMET. 

### 4.5.3 AERSURFACE
AERSURF ACE is a program that extracts surface roughness, albedo , and daytime Bowen ratio for an area s urrounding a given location. AERSURFACE uses land use and land cover (LULC) data in the U.S. Geological Survey's 1992 National Land Cover Dataset to e xtract the necessary micrometeorological data. LULC data was used for processing meteorological data sets used as input to AERMOD.
AERSURFACE v. 13016 was used to develop surface roughness, albedo , and daytime Bowen ratio values in a region s urrounding the meteorological data collection site

. AERSURF ACE was used to develop surface roughness in a one kilometer radius surrounding the data collection site. Bowen ratio and albedo was developed for a 10 kilometer by 10 kilometer area centered on the meteorological data collection site. The s e micrometeorological data were processed for seasonal periods using 30-degree sectors. Seasona l moisture conditions were considered average with winter months having no continuous snow cover .

14 Ava il a ble at: http ://es rl.noaa.g o v / raob s/E v aluation of Compliance with th e 1-hour NAAQSfor S02 S e

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e mb e r 3, 2 015 Pag e 14


### 4.5.4 Data Review Missing meteorologica l data were not filled as the data file met USEPA's 90% data completeness requirement. 15 The AERMOD output file shows there were 0.42% missing data.
To confirm the representativeness of the airport meteorological data, the surface characteristics of the airport data collection site and the modeled source location were compared. Since the Spirit of St. Louis Airport is located close to Ameren Labadie Plant, this meteorological data set was considered appropriate for this modeling analysis. 16 Additionally, this weather station provided high quality surface measurements for the most recent 3

- year time, and had similar land use, surface characteristics , terrain features and climate

. 

### 5. Background 80 2 

### Concentrations Background concentrations were determined consistent with U8EPA's Modeling Guidance for 80 2 NAAQ8 Designations. 1 7• 1 8 To preserve the form of the 1-hour S0 2 standard , based on the 99th percentile of the annua l distribution of daily maximum 1-hour concentrations averaged across the number of years modeled , the background fourth -hi ghest daily maximum 1-hour S0 2 concentration was added to the modeled fourth -hi ghest daily maximum 1-hour 80 2 concentration. 19 Background concentrations were based on the 2011-13 design value measured by the ambient monitors l ocated in Missouri. 2 0


### 6. Reporting
All files from the programs used for this modeling analysis are available to regulatory agencies. These include analyses prepared with AERSURFACE , AERMET , AERMAP , and AERMOD.

1 5 USEPA , M e teorological Monitoring Guidance for Regulatory Modeling Appli c ations , EPA -454/R-99-05, February 2000 , Section 5. 3.2, pp. 5 -4 to 5-5. 1 6 USE PA, AERMOD Impl e mentation Guide , March 19 , 2009 , pp. 3 -4. 1 7 U S EP A , Area De s ignations for the 2 010 R e vi s ed Primary Sulfur Dioxide Nati o nal Ambi e nt Air Quality Standards , Attachment 3, Marc h 2 4, 2 011 , pp. 20-23. 1 8 U S E P A , S0 2 NAAQS De s i gn ations Modeling Te c hnical As s istance Document , Dec. 2013, s ection 8

. 1 , pp 27- 28. 1 9 US E PA, Appli c ability of App endix W Modeling Guidance for the 1-h o ur S 0 2 National Ambient Air Quality Standard , Au g u s t 23 , 2 010 , p . 3. 20 http : //ww w . epa.gov / airtrend s / va lue s .html