TECHNICAL SUPPORT DOCUMENT

FOR

SO2 DESIGNATION RECOMMENDATIONS 

FOR ELECTRIC POWER FACILITY 

AREAS:

Newton Power Station, Hennepin Power Station, Marion 

Power Station, Joppa Steam Coal Power Plant, and 

Wood River Power Station

AQPSTR 15-04

Illinois Environmental Protection Agency

Bureau of Air

1021 North Grand Avenue, East

Springfield, Illinois 62794-9276

September 18, 2015
Table of Contents

List of Tables..................................................................................................................................................... 1

List of Figures ................................................................................................................................................... 2

1.0 Introduction/Background....................................................................................................................... 3

1.1 Consent Decree Designation Timeline ...................................................................................................... 5

1.2 Federal Guidance ....................................................................................................................................... 5

1.3 Illinois’ Five-Factor Analyses and Designation Recommendations.......................................................... 6

2.0 Illinois SO2 Monitoring Data Update................................................................................................... 7

3.0 Illinois Modeling Analyses....................................................................................................................... 9

3.1 Newton Power Station (Jasper County)................................................................................................. 9

3.1.1 Study Area .................................................................................................................................... 9

3.1.2 Model Setup and Execution ........................................................................................................ 10

3.1.2.1 Model Settings........................................................................................................................ 10

3.1.2.2 Auer’s Analysis....................................................................................................................... 10

3.1.2.3 Emissions................................................................................................................................ 12

3.1.2.4 Meteorology............................................................................................................................ 13

3.1.2.5 Receptor Network/Terrain ...................................................................................................... 15

3.1.2.6 Background SO2...................................................................................................................... 16

3.1.3 Summary of Results.................................................................................................................... 17

3.1.4 Designation Recommendation .................................................................................................... 18

3.2 Hennepin Power Station (Putnam County).......................................................................................... 19

3.2.1 Study Area .................................................................................................................................. 19

3.2.2 Model Setup and Execution ........................................................................................................ 20

3.2.2.1 Model Settings........................................................................................................................ 20

3.2.2.2 Auer’s Analysis....................................................................................................................... 20

3.2.2.3 Emissions................................................................................................................................ 22

3.2.2.4 Meteorology............................................................................................................................ 23

3.2.2.5 Receptor Network/Terrain ...................................................................................................... 25

3.2.2.6 Background SO2...................................................................................................................... 26

3.2.3 Summary of Results.................................................................................................................... 27

3.2.4 Designation Recommendation .................................................................................................... 28

3.3 Marion Power Station (Williamson County)........................................................................................ 29

3.3.1 Study Area .................................................................................................................................. 29
3.3.2 Model Setup and Execution ........................................................................................................ 29

3.3.2.1 Model Settings........................................................................................................................ 30

3.3.2.2 Auer’s Analysis....................................................................................................................... 30

3.3.2.3 Emissions................................................................................................................................ 31

3.3.2.4 Meteorology............................................................................................................................ 32

3.3.2.5 Receptor Network/Terrain ...................................................................................................... 34

3.3.2.6 Background SO2...................................................................................................................... 35

3.3.3 Summary of Results.................................................................................................................... 36

3.3.3 Designation Recommendation .................................................................................................... 37

3.4 Joppa Steam Coal Power Plant (Massac County)................................................................................ 38

3.4.1 Study Area .................................................................................................................................. 38

3.4.2 Model Setup and Execution ........................................................................................................ 39

3.4.2.1 Model Settings........................................................................................................................ 39

3.4.2.2 Auer’s Analysis....................................................................................................................... 39

3.4.2.3 Emissions................................................................................................................................ 41

3.4.2.4 Meteorology............................................................................................................................ 42

3.4.2.5 Receptor Network/Terrain ...................................................................................................... 44

3.4.2.6 Background SO2...................................................................................................................... 45

3.4.3 Summary of Results.................................................................................................................... 46

3.4.4 Designation Recommendation .................................................................................................... 47

3.5 Wood River Power Station (Madison County)..................................................................................... 48

3.5.1 Study Area .................................................................................................................................. 48

3.5.2 Model Setup and Execution ........................................................................................................ 49

3.5.2.1 Model Settings........................................................................................................................ 49

3.5.2.2 Auer’s Analysis....................................................................................................................... 49

3.5.2.3 Emissions................................................................................................................................ 51

3.5.2.4 Meteorology............................................................................................................................ 52

3.5.2.5 Receptor Network/Terrain ...................................................................................................... 54

3.5.2.6 Background SO2...................................................................................................................... 55

3.5.3 Summary of Results.................................................................................................................... 56

3.5.4 Designation Recommendation .................................................................................................... 57

4.0 Summary .................................................................................................................................................. 59

5.0 References................................................................................................................................................. 60
6.0 Appendices............................................................................................................................................... 61

Appendix A..................................................................................................................................................... 61

Appendix B..................................................................................................................................................... 71

Appendix C..................................................................................................................................................... 77
1

List of Tables

Table 1 Illinois Consent Decree Facilities and Reported 2012 Emissions 3

Table 2 Illinois 2012-2014 1-Hour SO2 Design Values (ppb) 7

Table 3 Auer’s Analysis Land Use Percentages by Category – Newton Study Area 12

Table 4 Modeled Facility Actual Emissions – Newton Study Area 13

Table 5 Maximum Predicted 99th Percentile 1-Hour SO2 Concentration - Newton Study Area 17

Table 6 Auer’s Analysis Land Use Percentages by Category – Hennepin Study Area 21

Table 7 Modeled Facility Actual Emissions – Hennepin Study Area 22

Table 8 Maximum Predicted 99th Percentile 1-Hour SO2 Concentration - Hennepin Study Area 27

Table 9 Auer’s Analysis Land Use Percentages by Category – Marion Study Area 31

Table 10 Modeled Facility Emissions – Marion Study Area 32

Table 11 Maximum Predicted 99th Percentile 1-Hour SO2 Concentration - Marion Study Area 36

Table 12 Auer’s Analysis Land Use Percentages by Category – Joppa Study Area 40

Table 13 Modeled Facility Actual Emissions – Joppa Study Area 41

Table 14 Maximum Predicted 99th Percentile 1-Hour SO2 Concentration - Joppa Study Area 46

Table 15 Auer’s Analysis Land Use Percentages by Category – Wood River Study Area 50

Table 16 Modeled Facility Actual Emissions – Wood River Study Area 51

Table 17 Maximum Predicted 99th Percentile 1-Hour SO2 Concentration - Wood River Study Area

56
2

List of Figures

Figure 1 Illinois SO2 Consent Decree Facilities 4

Figure 2 Illinois 1-hour SO2 Design Values 2012-2014 8

Figure 3 Newton Study Area (Jasper County) 9

Figure 4 Auer’s Analysis - Newton Study Area 11

Figure 5 Evansville, Indiana, Cumulative Annual Wind Rose 2012-2014 14

Figure 6 Receptor Grid - Newton Study Area 16

Figure 7 Maximum Predicted 99th Percentile 1-Hour SO2 Concentrations - Newton Study Area 18

Figure 8 Hennepin Study Area (Putnam County) 19

Figure 9 Auer’s Analysis - Hennepin Study Area 21

Figure 10 Rockford, Illinois, Cumulative Annual Wind Rose 2012-2014 24

Figure 11 Receptor Grid – Hennepin Study Area 26

Figure 12 Maximum Predicted 99th Percentile 1-Hour SO2 Concentrations - Hennepin Study Area

28

Figure 13 Marion Study Area (Williamson County) 29

Figure 14 Auer’s Analysis - Marion Study Area 30

Figure 15 Paducah, Kentucky, Cumulative Annual Wind Rose 2012-2014 33

Figure 16 Receptor Grid – Marion Study Area 35

Figure 17 Maximum Predicted 99th Percentile 1-Hour SO2 Concentrations - Marion Study Area

37

Figure 18 Joppa Study Area (Massac County) 38

Figure 19 Auer’s Analysis - Joppa Study Area 40

Figure 20 Paducah, Kentucky, Cumulative Annual Wind Rose 2012-2014 43

Figure 21 Receptor Grid – Joppa Study Area 45

Figure 22 Maximum Predicted 99th Percentile 1-Hour SO2 Concentrations - Joppa Study Area

47

Figure 23 Wood River Study Area (Madison County) 48

Figure 24 Auer’s Analysis – Wood River Study Area 50

Figure 25 St. Louis, Missouri, Cumulative Annual Wind Rose 2012-2014 53

Figure 26 Receptor Grid – Wood River Study Area 55

Figure 27 Maximum Predicted 99th Percentile 1-Hour SO2 Concentrations - Wood River Study Area

57

Figure 28 Proposed Nonattainment Area Boundary for the Wood River Study Area 58
3

1.0 Introduction/Background

On March 2, 2015, the U.S. District Court for the Northern District of California issued a court order 

accepting a consent decree between the U.S. Environmental Protection Agency (U.S. EPA), Sierra 

Club, and Natural Resources Defense Council resolving litigation concerning the deadline for U.S. 

EPA to complete area designations for the 2010 1-hour SO2 National Ambient Air Quality Standard 

(NAAQS). Per the court order, U.S. EPA will complete the area designations in three additional 

rounds: the first round by July 2, 2016, the second round by December 31, 2017, and the final round 

by December 31, 2020. For each round, U.S. EPA will identify additional areas as either 

nonattainment, unclassifiable/attainment, or unclassifiable.

For the first round of designations, U.S. EPA will designate two groups of areas: 1) areas with newly 

monitored violations of the 2010 SO2 standard, and 2) areas that contain stationary sources that 

according to U.S. EPA’s Air Markets Database either emitted more than 16,000 tons of SO2 in 2012 

or emitted more than 2,600 tons of SO2 and had an emission rate of 0.45 pounds of SO2 per million 

BTU (lbs/mmBTU) or higher in 2012 and that had not been announced for retirement as of March 2, 

2015. 

U.S. EPA identified five electric generating facilities in Illinois that meet the stationary source criteria 

established in the court’s order. These five facilities are listed in Table 1 and their locations are 

shown in Figure 1. This report provides Illinois’ area designation recommendations for each of these 

five facilities, and the technical justification for those recommendations. 

Table 1

Illinois Consent Decree Facilities and Reported 2012 Emissions 

State County Facility Name 2012 SO2

Emissions (tons)

2012 SO2

Emissions Rate 

(lbs/mmBTU)

Illinois Jasper Newton Power Station 16,519 0.590

Illinois Putnam Hennepin Power Station 5,906 0.501

Illinois Williamson Marion Power Station 5,850 0.489

Illinois Massac Joppa Steam Coal Power Plant 16,991 0.475

Illinois Madison Wood River Power Station 6,756 0.476
4

Figure 1
5

1.1 Consent Decree Designation Timeline

The court order stipulates a compressed timeline for states to submit updated recommendations to 

U.S. EPA, and for U.S. EPA to review this information and make final area designations. This 

timeline is as follows: 

 States submit updated recommendations based on 2012-2014 monitoring data and new actual 

emissions-based modeling to U.S. EPA by September 18, 2015.

 U.S. EPA notifies states of any intended modifications to their area designations (120-day 

letters) no later than March 2, 2016.

 U.S. EPA publishes public notice of state recommendations and the U.S. EPA’s intended 

modifications and initiates a 30-day public comment period on or about February 3, 2016

 The 30-day public comment period ends on or about March 4, 2016.

 States must respond to any modifications proposed by U.S. EPA on or about April 8, 2016.

 U.S. EPA finalizes the first round of SO2 area designations made under the court’s order, no 

later than July 2, 2016.

 

1.2 Federal Guidance

The Illinois Environmental Protection Agency (Illinois EPA) relied on guidance provided in a 

memorandum issued March 20, 2015, by Stephen D. Page, Director, Office of Air Quality Planning 

and Standards at U.S. EPA. This memorandum replaces the original designation guidance for the 

2010 SO2 NAAQS, which was issued on March 24, 2011. In this guidance, U.S. EPA recommends

that states analyze the following five factors when considering boundaries for the updated area 

designations: ambient air quality data or dispersion modeling, emissions and emissions-related data, 

meteorology, geography/topography, and jurisdictional boundaries. Due to the localized nature of 

SO2 impacts, U.S. EPA considers county boundaries as the logical starting point, or presumptive 

boundary, for determining SO2 nonattainment areas. However, U.S. EPA also provides states with 

the flexibility to designate nonattainment areas consisting of only a portion of a county when 

supported by an examination of the five factors and other information. When defining partial county 

boundaries, states are advised to use well-defined jurisdictional lines, such as geopolitical boundaries, 

immovable landmarks, and readily identifiable physical features. 

U.S. EPA will designate areas as being nonattainment, attainment, or unclassifiable. Section 

107(d)(1) of the Clean Air Act defines an area as nonattainment if it is violating the 1-hour SO2

NAAQS or if emission sources located within the area contribute to a violation in a nearby area. For 

an area to be designated as attainment, it must meet the 1-hour SO2 NAAQS and not contribute to a 

violation in a nearby area. Lastly, areas can be designated as unclassifiable when U.S. EPA cannot 

determine based on available information whether an area is or is not meeting the 1-hour SO2

NAAQS or whether the area is contributing to a violation in a nearby area. The air quality data used 
6

to make these determinations can come from either air monitoring networks or air dispersion 

modeling. 

Due to the short timeframe within which the first round of area designations under the court order 

must be completed, U.S. EPA anticipated that air dispersion modeling would be the most reliable 

source of information for determining designation boundaries. However, U.S. EPA expected that 

states would also review their latest available SO2 monitoring data from 2012-2014. U.S. EPA 

intends to also consider any certified SO2 monitoring that might be available for 2015 before the 120-

day letters are sent out. 

1.3 Illinois’ Five-Factor Analyses and Designation Recommendations 

Per the guidance issued by U.S. EPA, this report contains Illinois’ updated 1-hour SO2 air quality data 

for 2012-2014, along with air dispersion modeling analyses for the Newton Power Station, Hennepin 

Power Station, Marion Power Station, Joppa Steam Coal Power Plant, and Wood River Power 

Station. The air dispersion modeling for each of these facilities was conducted in accordance with the 

guidance provided in the December 2013 Modeling Technical Assistance Document (TAD). In order 

to ensure that the air dispersion modeling conducted for area designations better simulates a 

monitoring approach, the Modeling TAD specifically recommends the following procedures:

 Use of actual emissions as a model input for assessing violations to provide results that reflect 

current actual air quality.

 Use of three years of modeling results to calculate a simulated design value consistent with 

the approach used to calculate three-year design values for air monitoring sites for comparison 

to the NAAQS.

 Placement of receptors only in locations where a monitor could be located.

 Use of actual stack heights rather than adjusting stack height values based on the Good 

Engineering Practice stack height policy when modeling actual emissions.

The dispersion modeling simulations evaluated the emission impacts of each of the five power plants, 

together with the impacts of those nearby sources and background sources contributing to ambient 

SO2 levels in each modeling domain. The combined modeled impacts of these sources determined 

whether the NAAQS would be met. On this basis, a designation recommendation was developed for 

each of the study areas, with the remaining four “factors” and facility-specific information ultimately

contributing to a final recommendation and boundary determination.
7

2.0 Illinois SO2 Monitoring Data Update

Pursuant to the Consent Decree court order, U.S. EPA will first review the latest available air quality 

data to determine if any new areas of the country have monitored violations of the 2010 1-hour SO2

standard. Table 2 shows the most recent three consecutive years of quality assured air monitoring 

data in Illinois for 2012 through 2014, along with the resulting design values. The design value is 

defined as the three-year average of the annual 99th percentile daily maximum 1-hour SO2

concentrations collected at each monitor (which is generally the fourth highest daily maximum 1-hour 

concentration, averaged over three consecutive years). Since Illinois EPA’s original SO2 area 

designations were submitted to U.S. EPA in 2011, based on 2008-2010 air quality data, there has 

been a significant improvement in air quality statewide. At the end of 2010, four monitors were 

violating the 2010 1-hour SO2 standard. By the end of 2014, there was only one monitor violating the 

2010 1-hour SO2 standard. This last violating monitor is located in the Pekin SO2 Nonattainment 

Area in Tazewell County (see Figure 2) and is currently being addressed through a rulemaking 

proposed by the Illinois EPA. Therefore, based on the latest available 2012-2014 air quality data, 

there are no new areas in the State of Illinois with monitored violations of the 2010 1-hour SO2

standard. 

Table 2

Illinois 2012-2014 1-Hour SO2 Design Values (ppb)

AQS Code County Site Annual 99th Percentiles Design 

2012 2013 2014 Value

170191001 Champaign Bondville 14 14 15 14

170310076 Cook Chicago - Com Ed 17 10 15 14

170311601 Cook Lemont 108 73 16 66

170314201 Cook Northbrook 17 10 12 13

170990007 La Salle Oglesby 6 9 10 8

171150013 Macon Decatur 38 33 38 36

171170002 Macoupin Nilwood 8 7 10 8

171191010 Madison South Roxana 17 23 18 19

171193007 Madison Wood River WTP 30 29 30 30

171430024 Peoria Peoria 44 32 38 38

171570001 Randolph Houston 24 11 12 16

171630010 St. Clair East St. Louis 24 19 25 23

171670006 Sangamon Springfield 15 12 21 16

171790004 Tazewell Pekin 245 195 190 210

171850001 Wabash Mount Carmel 89 55 53 66
8

Figure 2
9

3.0 Illinois Modeling Analyses

3.1 Newton Power Station (Jasper County)

The Newton area contains a stationary source that satisfies both of the conditions (only one or 

the other required to qualify) of the March 2, 2015, Consent Decree between U.S. EPA, Sierra Club, 

and the NRDC. Newton Power Station emitted greater than 16,000 tons (16,519) tons per year of 

SO2 in 2012 and it also had an emission rate that exceeds 0.45 lbs/mmBtu (0.590) in 2012. 

3.1.1 Study Area

The Newton Power Station (Illinois Power Generating Company), located in southeastern Illinois 

in the southwestern portion of Jasper County, is one of the five plants subject to the March 2015 SO2

Consent Decree. It is approximately seven miles southwest of the city of Newton in a rural area 

bounded on the east and south by Newton Lake (see Figure 3). For the air quality impact analysis, 

the determination of the extent of the study area (i.e., receptor grid) is based primarily on three key 

considerations. First, the location of the SO2 emission sources/facilities considered for modeling;

second, the extent of significant concentration gradients of nearby sources; and third, sufficient 

receptor coverage and density to adequately capture and resolve model predicted maximum SO2

concentrations.

Figure 3 Newton Study Area (Jasper County)
10

3.1.2 Model Setup and Execution

Beginning in 2005, the American Meteorological Society/Environmental Protection Agency 

Regulatory Model (AERMOD) has been U.S. EPA’s preferred model for near-field (out to 50 km) 

dispersion modeling applications in the United States. The AERMOD model itself is one part of a 

modeling system that includes companion pre-processing programs that prepare other inputs into the 

model. The model is capable of evaluating air quality impacts for averaging times that vary from 1-

hour to a year and from multiple emissions sources and types, while also incorporating the influences 

of complex terrain, varying land use, and meteorology. The model is designed to account for

planetary boundary layer turbulence structure and to effectively handle scaling concepts. Plume

downwash induced by structures is also addressed in the model via the BPIP-PRIME algorithm. 

3.1.2.1 Model Settings

For the Newton Study Area, as with all of the study areas, the AERMOD dispersion model was 

run exclusively in the regulatory default mode.. The AERMOD modeling system includes the 

following programs, with the latest publicly available versions indicated in parentheses:

- AERMOD (15181)

- BPIP-PRIME (04274)

- AERMET (15181), AERMINUTE (14337)

- AERMAP (11103)

- AERSURFACE (13016)

This software is downloadable from U.S. EPA’s Transfer Technology Network (TTN) website. 

3.1.2.2 Auer’s Analysis 

An important first step in establishing the model settings for the Newton Study Area was 

determining if the sources within the study area are located within a rural or urban dispersion regime. 

Generally, urban areas cause higher rates of dispersion because of increased turbulence and buoyancy 

caused by higher surface roughness (tall buildings) and enhanced thermal buoyancy from urban heat 

island effects. U. S. EPA guidance allows the use of the Auer’s land use scheme within three 

kilometers of a source to determine the predominant dispersion regime. Essentially, if the percentage 

of land use types that are characteristic of an urban environment, such as light to heavy industrial, 

compact residential-single family or multi-family etc., is equal to or greater than 50% of the area 

within the three-kilometer radius circle, then the area should be classified (and modeled) as urban. If 

otherwise, the model can be run in rural mode. Recent versions of AERMOD do allow some 

flexibility to mix and match sources as rural or urban instead of an either/or approach, as select
11

subsets of sources can be flagged to be run with the AERMOD URBANOPT option on, while leaving 

other sources in Rural mode. 

The three-kilometer ring for the Newton Study Area is centered on the main stack at the Newton 

Power Station. The data source for land cover is the 2011 National Land Cover Database (NLCD), 

with a data cell size (raster) of 30 meters by 30 meters. The results of the Auer’s analysis for the 

Newton Study Area are presented in Figure 4 and Table 3. 

Figure 4

Auer’s Analysis - Newton Study Area
12

Table 3

Auer’s Analysis Land Use Percentages by Category - Newton Study Area

The Auer’s analysis indicates the study area is approximately 98.2% rural and 1.8% urban;

therefore the rural option applies to all emissions sources in the modeling domain.

3.1.2.3 Emissions

U. S. EPA guidance for developing designation recommendations based upon modeling specifies 

the use of actual emissions (as opposed to allowable) as input to produce results that reflect the 

existing air quality in a study area. U.S. EPA recommends using the most recent three years of actual 

emissions since they would best represent the emissions that would simulate the impacts of a threeyear monitoring dataset for determining compliance with the NAAQS. In this application, actual 

emissions were used from the years 2012-2014. 

In using actual emissions, U. S. EPA suggests that the best achievable characterization of the 

three-year hourly emissions profile be developed from continuous emissions monitoring systems

(CEMS) data or from other means as described in the SO2 NAAQS Designations Modeling TAD. If 

CEMS data are not available, then detailed throughput, operating schedules, and exhaust information 

is a next best option to create temporally varying emission profiles. AERMOD is equipped with two 

keyword functions, HOUREMIS and EMISFACT, which allow flexibility in terms of modeling 

variable emissions, depending on the depth of data on-hand. The HOUREMIS function allows the 

incorporation of hourly varying emissions, stack exit temperatures, and stack exit velocities into a

NLCD Value NLCD 2011 Description Auer's Code Auer's Class Cell Count Percentage Totals

23 Developed, Medium Intensity R2/R3 306 0.97%

24 Developed, High Intensity I1/I2/C1 253 0.81%

11 Open Water A5 6,370 20.29%

21 Developed, Open Space A1/R4 1,024 3.26%

22 Developed, Low Intensity R1 390 1.24%

31 Barren Land (Rock/Sand/Clay) A3 157 0.50%

41 Deciduous Forest A4 8,345 26.58%

42 Evergreen Forest A4 0 0.00%

43 Mixed Forest A4 0 0.00%

52 Shrub/Scrub A4 6 0.02%

71 Grassland/Herbaceous A3 1,001 3.19%

81 Pasture/Hay A3 2,546 8.11%

82 Cultivated Crops A2 10,997 35.03%

90 Wood Wetlands A4 0 0.00%

95 Emergent Herbaceous Wetlands A3 2 0.01%

Analysis based on 30 meter by 30 meter raster cells extracted for each area. Total 31,397 100.00% 100.00%

Rural

1.78%

98.22%

Newton 3 km Ring

Urban

Newton Study Area Auer's Analysis
13

single model-ready file. The keyword function EMISFACT can be used alone if there is insufficient 

information to determine hourly emissions, but enough information to approximate somewhat longer 

timeframe characterizations. EMISFACT allows the model to multiply a constant emissions rate by 

an emissions factor which can vary in a way that provides for a reasonable profile of seasonal, daily, 

day of week, and even hour of day characterization of emissions.

Determining which sources to model in the Newton Study Area included compiling a list of SO2

sources within a ten-kilometer radius of the Newton Power Station from the Illinois EPA statewide

inventory database, and also evaluating the potential for sources beyond 10 km to cause a significant 

concentration gradient within the Newton Study Area. The Newton Power Station is the only SO2

source within the ten-kilometer study area, and there are no sources beyond ten kilometers that 

Illinois EPA considers to have the potential to cause significant gradient impacts within the study 

area. Actual emissions for the years 2012-2014 are provided in Table 4.

Table 4 Modeled Facility Actual Emissions - Newton Study Area

Company I.D. Facility Name

SO2 Emissions (tons per year)

2012 2013 2014

079808AAA Newton Power Station 16,533.83 16,144.5 16,372.76

Total Emissions All Facilities 16,533.83 16,144.5 16,372.76

Hourly varying 2012-2014 CEMS data, coupled with hourly-specific exit temperatures and exit 

velocities, were provided by Illinois Power Generating Company for use in the dispersion modeling. 

See Appendix A for the full emissions inventory and stack parameters, including the substitution 

methods employed for addressing missing or erroneous data fields. For the Newton Study Area, the 

HOUREMIS factor was applied to the two point sources modeled. The EMISFACT keyword was 

not deemed necessary for representing this facility’s emissions. The hourly emissions file is included 

with this submittal and can be found on the DVD representing Appendix C.

3.1.2.4 Meteorology

The SO2 TAD recommends using the three most recent years of meteorology for modeling

applicable to the SO2 area designations process. In this case, data for meteorological years 2012-

2014 were available. This time period aligns with the three years of hourly emissions data input into 

the model. This temporal linking of emissions and meteorology in the model provides the best 

approximation of the real-world impacts which would occur during that time should a monitor have 

been present.

The selection of a representative meteorological station for each of the study areas was based on 

proximity, similarity of terrain/surface roughness, and climatological consistency. Central Illinois and 

central Indiana share similar topography, climate, and land use. For the Newton Study Area, National 

Climatic Data Center National Weather Service (NWS) surface meteorology from Evansville, Indiana 
14

(WBAN No. 93817, 123 km to the southeast), and coincident upper air observations from Lincoln, 

Illinois (WBAN No. 04833, 164 km to the northwest), were selected as best representative of 

meteorological conditions within the study area (EVV/ILX).

The three-year surface wind rose for Evansville, Indiana, is depicted in Figure 5. The frequency 

and magnitude of wind speed and direction are defined in terms of where the wind is blowing from, 

parsed out in twelve 30-degree wind sectors. The predominant wind direction during the three-year 

time period represented in the modeling is from the southwest, occurring approximately 11.3% of the

time. The highest percentage wind speed range, occurring 25.3% of the time, was in the 3.6 – 5.7 m/s

range.

Figure 5 

Evansville, Indiana, Cumulative Annual Wind Rose

2012-2014

WRPLOT View - Lakes Environmental Software

WIND ROSE PLOT:

Station #93817 - EVANSVILLE/DRESS REGIONAL ARP, IN 

COMMENTS:

Direction Wind is blowing from.

COMPANY NAME:

MODELER:

DATE:

8/31/2015

PROJECT NO.:

NORTH

SOUTH

WEST EAST

3%

6%

9%

12%

15%

WIND SPEED 

(m/s)

 >= 11.1

 8.8 - 11.1

 5.7 - 8.8

 3.6 - 5.7

 2.1 - 3.6

 0.5 - 2.1

Calms: 2.05%

TOTAL COUNT:

26201 hrs.

CALM WINDS:

2.05%

DATA PERIOD:

Start Date: 1/1/2012 - 00:00

End Date: 12/31/2014 - 23:00

AVG. WIND SPEED:

3.23 m/s

DISPLAY:

 Wind Speed

Direction (blowing from)
15

Meteorological data from the above surface and upper air stations were used in generating 

AERMOD-ready files with the AERMET processor, a part of the AERMOD software suite. The 

output meteorological data created by the AERMET processor is suitable for being applied with 

AERMOD input files for AERMOD modeling runs.

The methodology and settings performed in the processing of the raw meteorological data into 

AERMOD-ready format followed the guidelines set forth in the draft guidance, Regional 

Meteorological Data Processing Protocol, U.S. EPA Region 5 and States (February 1, 2013). Surface 

characteristics such as Albedo, Bowen Ratio, and Surface Roughness (Zo) were developed using 

AERSURFACE, an AERMET companion preprocessor.

The surface meteorological wind field data is input to AERMET from two separate sources. 

Hourly surface meteorological data records are read by AERMET and include all the necessary 

elements for meteorological data processing. However, wind data taken at hourly intervals may not 

always portray wind conditions for the entire hour, which can be variable in nature compared to more 

stable meteorological data categories not prone to wide ranging changes. Indeed, wind data that 

portrays calm conditions for the hour is not usable for modeling proposes and must be passed over by 

AERMOD when modeling is being performed. In order to better represent actual wind conditions at 

the meteorological tower, wind data of one minute duration was provided from the same instrument

tower, but in a different formatted file to be processed by a separate preprocessor, AERMINUTE. 

This data is subsequently integrated into the AERMET processing to produce final hourly wind 

records of AERMOD-ready meteorological data that approach actual conditions and reduce the 

frequency of reported calm wind conditions. This allows AERMOD to apply more hours of 

meteorology to modeled inputs, and therefore produce more concentration data output. As a guard 

against excessively high concentrations that could be produced in very light wind conditions, Illinois 

EPA set a minimum threshold of 0.5 m/s in processing meteorological data for use in AERMOD. In

setting this threshold, no wind speeds lower than this value would be used for determining 

concentrations. This threshold was specifically applied to the one minute wind data.

The AERMOD-ready “.sfc” and “.pfl” meteorological data files are included in this submittal via 

the DVD representing Appendix C. 

3.1.2.5 Receptor Network/Terrain 

The receptor grid for Newton was designed to be of sufficient density and size to capture all 

relevant concentration gradients from modeled sources and to adequately resolve the maximum 

predicted SO2 design value concentration. In the case of the Newton Study Area, the Newton Power 

Station was the only source modeled. Thus, the receptor grid includes fine to coarse spacing in a 

Cartesian grid network extending outward in all directions from the facility fenceline. Receptor 

spacing was approximately:
16

 50 meters along the fenceline

 100 meters from the fenceline out to 5.0 kilometers

 500 meters from 5.0 kilometers out to 8.0 kilometers

The Newton Study Area receptor grid is presented in Figure 6. A total of 12,165 receptors

comprised the network, covering the southwestern section of Jasper County and small portions of 

Effingham and Clay counties. The terrain in the study area is best described as flat to gently rolling. 

To account for terrain changes, the AERMAP terrain program was used to specify terrain elevations 

and hill scale height for all the receptors. The source of the elevation data incorporated into the 

model is from the USGS National Elevation Database (NED).

Figure 6 Receptor Grid – Newton Study Area

3.1.2.6 Background SO2 

The regional SO2 sources not explicitly modeled in AERMOD were characterized as background 

contributors to SO2 in the study area and represented via background monitoring data. U.S. EPA

recommends inclusion into the model data from the nearest representative background SO2 monitor 

operated by federal, state, local, or tribal organizations. The Nilwood, Illinois, monitor was selected 

for the Newton study area. The Nilwood monitor is located approximately 142 kilometers northwest 
17

of the study area in rural Macoupin County. The monitor, operated and maintained by Illinois EPA, 

has hourly SO2 concentrations which have been validated for the three years modeled in this analysis 

(2012-2014). 

For this modeling application, Illinois EPA incorporated temporally-varying background 1-hour 

concentrations developed from the Nilwood, Illinois, monitor. The values developed for input into 

AERMOD are based on the 99th percentile monitored concentrations and vary by season and hour.

The seasons are characterized as: Winter (Dec-Jan-Feb), Spring (Mar-Apr-May), Summer (Jun-JulAug), and Fall (Sep-Oct-Nov). The second highest value for each hour of the day (24 values) by 

season was averaged for the years 2012-2014 to derive 96 distinct 1-hour SO2 background 

concentration values, in total for the four seasons. The latest version of AERMOD allows inclusion 

of these hourly varying background values directly into the AERMOD runstream file via the 

SEASONHR keyword. For model results reported here, the maximum impacts include the 

contribution from background SO2 in the modeled design value. A table of the background SO2

hourly varying values by season is provided in Appendix B.

3.1.3 Summary of Results

The AERMOD simulation for the Newton Study Area included two stacks, nine structures, one

fenceline, and 12,165 receptors. The model simulated the years 2012-2014, combining emissions, 

meteorology, terrain, and background SO2 levels into the model to calculate a maximum 99th

percentile 1-hour SO2 concentration for each receptor in the grid. The results presented in Table 5 

report the magnitude and geographic location of the highest predicted concentration.

Table 5 

Maximum Predicted 99th Percentile 1-Hour SO2 Concentration

Newton Study Area

Averaging Period Data 

Period

Receptor Location 

(Meters)

SO2 Concentration

(μg/m3)

East North Modeled NAAQS

99th Percentile 1-

Hour Average 2012-2014 390400 4314200 138.89 196.23*

* Equivalent to the 75 ppb standard

The maximum predicted 99th percentile 1-hour average concentration within the modeling domain is 

138.89 μg/m3, or 53.0 ppb. The maximum occurred within the dense 100-meter grid approximately 

3.85 km northeast of the Newton Power station main stack. The colored contour map of maximum 

99th percentile concentrations presented in Figure 7 depicts the maximum predicted concentration for 

each receptor in the study area and indicates the location of the overall predicted maximum.
18

Figure 7 

Maximum Predicted 99th Percentile 1-Hour SO2 Concentrations - Newton Study Area

3.1.4 Designation Recommendation

Based on the modeling results, the extent of the study area, and consideration of other SO2 sources in 

the multi-county area, Illinois EPA recommends that Jasper County be designated as attainment for 

the 1-hour SO2 standard. 
19

3.2 Hennepin Power Station (Putnam County)

The area near the city of Hennepin in Putnam County contains a stationary source that satisfies 

one of the conditions (only one or the other required to qualify) of the March 2, 2015, Consent 

Decree between U. S.EPA, Sierra Club, and the NRDC. A source exists that emitted less than the 

16,000 tons (5,906) tons per year of SO2 in 2012, but had an emission rate that exceeds 0.45 

lbs/mmBtu (0.501) in 2012. 

3.2.1 Study Area

The town of Hennepin, Illinois, is located in north-central Illinois in the northwestern portion of 

Putnam County. The Hennepin Power Station (Dynegy) is one of the five plants subject to the SO2

Consent Decree. As depicted in Figure 8, the plant operates approximately 5.6 kilometers northnortheast of the town of Hennepin in a rural area bounded on the north by the Illinois River. For the 

air quality impact analysis, the determination of the size and extent of the study area (i.e., receptor 

grid) is based primarily on three key considerations: 1) the location of the SO2 emission 

sources/facilities to be included in the modeling; 2) the location and extent of significant 

concentration gradients to be generated by SO2 emission sources; and, 3) sufficient receptor coverage

and density to adequately capture and resolve model predicted maximum SO2 concentrations within 

the study area. 

Figure 8 Hennepin Study Area (Putnam County)
20

3.2.2 Model Setup and Execution

As described in Section 3.1.2, AERMOD was used for the designation recommendation 

modeling. AERMOD is the dispersion modeling component of a much broader modeling system that 

includes multiple companion pre-processing programs that prepare other inputs into the model (BPIPPRIME, AERMET, AERMINUTE, AERMAP, and AERSURFACE).

3.2.2.1 Model Settings

The latest version of AERMOD (version 15181) was run in the standard regulatory default 

mode.

3.2.2.2 Auer’s Analysis 

The Auer’s discussion and analysis discussed in Section 3.1.1.1 was similarly applied to the 

Hennepin Study Area. The Auer’s analysis is a methodology for determining if the sources within 

the study area are located within a rural or urban dispersion regime. 

The three-kilometer ring applied in the Auer’s analysis for the Hennepin Study Area is centered 

on the main stack at the Hennepin Power Station. The data source for land cover was the 2011 

National Land Cover Database (NLCD), with a data cell size of 30 meters by 30 meters. The results 

of the Auer’s analysis are presented in Figure 9 and Table 6. 
21

Figure 9

Auer’s Analysis – Hennepin Study Area

Table 6

Auer’s Analysis Land Use Percentages by Category – Hennepin Study Area

NLCD Value NLCD 2011 Description Auer's Code Auer's Class Cell Count Percentage Totals

23 Developed, Medium Intensity R2/R3 417 1.33%

24 Developed, High Intensity I1/I2/C1 166 0.53%

11 Open Water A5 7,222 23.01%

21 Developed, Open Space A1/R4 738 2.35%

22 Developed, Low Intensity R1 1,338 4.26%

31 Barren Land (Rock/Sand/Clay) A3 338 1.08%

41 Deciduous Forest A4 4,063 12.94%

42 Evergreen Forest A4 0 0.00%

43 Mixed Forest A4 0 0.00%

52 Shrub/Scrub A4 48 0.15%

71 Grassland/Herbaceous A3 1,797 5.72%

81 Pasture/Hay A3 141 0.45%

82 Cultivated Crops A2 8,861 28.23%

90 Wood Wetlands A4 5,302 16.89%

95 Emergent Herbaceous Wetlands A3 962 3.06%

Grand Totals: 31,393 100.00%

Hennepin 3 km Ring

Urban 1.86%

Rural 98.14%

Analysis based on 30 meter by 30 meter raster cells extracted for each area.

S O2 NAA Modeling Auer's Analysis - NLCD 2011
22

The Auer’s analysis indicates the study area is approximately 98.1% rural and 1.9% urban; 

therefore the rural option was applied to all emissions sources in the modeling domain.

3.2.2.3 Emissions

U. S. EPA guidance for the modeling of emissions for designation recommendations allows for 

use of actual emissions as input (as opposed to allowable) into the model to produce results that 

reflect the current existing air quality in a study area. U.S. EPA recommends using the most recent 3 

years of actual emissions since they would best represent the emissions that would simulate the 

impacts of a 3-year monitoring dataset for determining compliance with the NAAQS. In this 

application, actual emissions were used from the most recent available years (2012-2014).

The determination of sources to model in the Hennepin Study Area consisted of compiling a list 

from the state inventory database of SO2 sources within a 10 km radius of the Hennepin Power 

Station, while also evaluating the potential for sources beyond 10 km to cause a significant 

concentration gradient within the area. In the case of Hennepin, four facilities were identified within 

this area with SO2 emissions (refer to Figure 8). The four facilities were considered to have a 

potential impact in the near-field where maximum concentrations are expected. There were no 

sources beyond 10 km that Illinois EPA considers to have the potential to cause significant gradient 

impacts within the study area. The facilities and their modeled actual SO2 tonnages for 2012-2014 

are presented in Table 7.

Table 7

Modeled Facility Actual Emissions - Hennepin Study Area

Company I.D. Facility Name

SO2 Emissions (tons per year)

2012 2013 2014

155010AAA Hennepin Power Station 5,911.25 4,274.35 3,965.36

155801AAC Washington Mills 890.20 929.43 1,035.01

155801AAJ Advanced Asphalt 13.63 13.62 5.46

155010AAJ Marquis Energy 8.56 9.30 4.05

Total Emissions All Facilities 6823.64 5226.70 5009.88

Emissions profiles for the Hennepin inventory were developed using a combination of the 

AERMOD keywords HOUREMIS and EMISFACT. Illinois EPA used hourly varying 2012-2014 

CEMS SO2 emissions data provided by the Hennepin Power Station together with hourly-specific exit 

temperatures and exit velocities. For Washington Mills, hourly varying emissions, temperatures, and 

exit velocities were obtained for the largest emitting furnace stack (99.9% of the facility emissions). 

For the two smaller emitting units, Washington Mills provided operating information that allowed 

Illinois EPA to construct an hourly varying emissions rate coupled with constant temperature and exit 
23

velocity values. An hourly profile was developed for Advanced Asphalt’s sources based on company 

reported seasonal throughput. A combination of seasonal emissions factors (EMISFACT) and an 

hourly emissions profile was used for Marquis Energy sources. Please reference Appendix A for the 

full emissions inventory and stack parameters, including the substitution methods employed for 

addressing missing or erroneous data fields. For the Hennepin Study Area, a total of 12 point sources 

were modeled. The HOUREMIS factor was applied to the seven point sources modeled and 

EMISFACT to four sources. One source was modeled with a conservative constant hourly emission 

rate for the three-year period. The hourly emissions file is included in this submittal via the DVD 

representing Appendix C.

3.2.2.4 Meteorology

The SO2 TAD recommends using the three most recent years of meteorology for use in the SO2

Phase II Designation modeling. For the Hennepin Study Area, the National Climatic Data Center 

National Weather Service (NWS) surface meteorology from Rockford, Illinois (WBAN No. 94822, 

111 km to the north), and coincident upper air observations from Davenport, Iowa (WBAN No. 

94982, 110 km to the northwest), were selected as best representative of meteorological conditions 

within the study area.

The three-year surface wind rose for Rockford, Illinois, is depicted in Figure 10. The frequency 

and magnitude of wind speed and direction are defined in terms of where the wind is blowing from, 

parsed out in twelve 30-degree wind sectors. The predominant wind direction during the three-year 

time period used in the modeling is from the south, occurring approximately 12.8% of the time. The 

highest percentage wind speed range, occurring 31.4% of the time, was in the 3.6 – 5.7 m/s range.
24

Figure 10

Rockford, Illinois, Cumulative Annual Wind Rose

2012-2014

Meteorological data from the above surface and upper air stations were used in generating 

AERMOD-ready files with the AERMET processor, a part of the AERMOD software suite. The 

output meteorological data created by the AERMET processor is suitable for being applied with 

AERMOD input files for AERMOD modeling runs. The methodology and settings performed in the 

processing of the raw meteorological data into AERMOD-ready format followed the same procedure 

as in the Newton Study Area. Please refer to Section 3.1.2.4 for more details on the meteorological 

input procedure utilized. The Hennepin Study Area AERMOD-ready “.sfc” and “.pfl”

meteorological electronic files are included in this submittal via the DVD representing Appendix C. 

WRPLOT View - Lakes Environmental Software

WIND ROSE PLOT:

Station #94822 - ROCKFORD/GREATER ROCKFORD ARP, IL 

COMMENTS:

Direction Wind is blowing from.

COMPANY NAME:

MODELER:

DATE:

9/1/2015

PROJECT NO.:

NORTH

SOUTH

WEST EAST

3%

6%

9%

12%

15%

WIND SPEED 

(m/s)

 >= 11.1

 8.8 - 11.1

 5.7 - 8.8

 3.6 - 5.7

 2.1 - 3.6

 0.5 - 2.1

Calms: 0.57%

TOTAL COUNT:

26295 hrs.

CALM WINDS:

0.57%

DATA PERIOD:

Start Date: 1/1/2012 - 00:00

End Date: 12/31/2014 - 23:00

AVG. WIND SPEED:

4.20 m/s

DISPLAY:

 Wind Speed Direction (blowing from)
25

3.2.2.5 Receptor Network/Terrain 

The receptor grid for Hennepin was designed to be of sufficient density and size to capture all 

relevant concentration gradients from modeled sources and to adequately resolve the maximum 

predicted SO2 design value concentration. In the case of the Hennepin Study Area, three of the four 

facilities (Hennepin Power Station/Washington Mills/Advance Asphalt) are located nearly adjacent to 

one another along the Illinois River. The fourth facility, Marquis Energy, is located roughly three 

kilometers to the south-southwest of the other facilities. Therefore, to ensure adequate capture of 

predicted maximums the receptor grid’s dense 100-meter spacing was extended outward from each 

fenceline to a distance of at least 3 kilometers from each facility. The study area receptor spacing 

was approximately:

 50 meters along the fenceline (four facilities)

 100 meters from the fenceline out to a distance of approximately 4.0 kilometers

 500 meters from 4.0 kilometers out to a distance of approximately 8.0 kilometers

 1,000 meters from 8.0 kilometers out to a distance of approximately 11 kilometers

The Hennepin Study Area receptor grid is presented in Figure 11. The receptor network, 

consisting of 13,430 receptors, covers the northern two-thirds of Putnam County and the southeast

portion of Bureau County. The study area terrain is best characterized as flat to gently rolling. To 

account for terrain changes, the AERMAP terrain program was used to generate terrain elevations 

and hill height scales for all the receptors. The source of the elevation data incorporated into the 

model is from the USGS National Elevation Database (NED).
26

Figure 11

Receptor Grid – Hennepin Study Area

3.2.2.6 Background SO2 

The regional sources not explicitly modeled in AERMOD, but best characterized as background 

contributors to SO2 near or in the study area, are addressed via background monitoring data. U.S. 

EPA recommends inclusion into the model data from the nearest representative background SO2

monitor operated by state, local, or tribal organizations. The Oglesby, Illinois, monitor was selected 

for the Hennepin study area. The Oglesby monitor is located approximately 23 km east of the study 

area in western LaSalle County in the town of Oglesby. The monitor, operated and maintained by 

Illinois EPA, has validated hourly SO2 concentrations for the three years modeled in this analysis 

(2012-2014). 

For this modeling application, Illinois EPA employed temporally-varying background 1-hour 

concentrations developed from the Oglesby, Illinois, monitor. The values developed for input into 

AERMOD for background SO2 are based on the 99th percentile monitored concentrations vary by 

season and hour in the same method as described in the previously discussed study area. The seasons 

are characterized as: Winter (Dec-Jan-Feb), Spring (Mar-Apr-May), Summer (Jun-Jul-Aug), and Fall 

(Sep-Oct-Nov). The second highest value for each hour of the day (24 values) by season was 

averaged for 2012-2014 to derive 96 distinct 1-hour SO2 concentrations background values total for 
27

the four seasons. For model results reported here, the maximum impacts include the contribution 

from background SO2 into the modeled design value. A table of the background SO2 seasonally and 

hourly varying values utilized in the Hennepin Study Area modeling is provided in Appendix B. 

3.2.3 Summary of Results

The AERMOD simulation for the Hennepin Study Area evaluated seven stacks, 90 structures, four

fencelines, and 13,429 receptors. The model simulated the years 2012-2014, combining emissions, 

meteorology, terrain, and background SO2 levels into the model to calculate a predicted maximum 

99th percentile 1-hour SO2 concentration for each receptor in the grid. The results presented in Table 8

report the magnitude and geographic location of the highest predicted concentration.

Table 8

Maximum Predicted 99th Percentile 1-Hour SO2 Concentration

Hennepin Study Area

Averaging Period Data 

Period

Receptor Location 

(Meters)

SO2 Concentration

(μg/m3)

East North Modeled NAAQS

99th Percentile 1-

Hour Average 2012-2014 311600 4570200 94.56 196.23*

* Equivalent to the 75 ppb standard

The maximum predicted 99th percentile 1-hour average concentration within the modeling domain is 

94.56 μg/m3, or 36.1 ppb. The maximum occurred within the dense 100-meter grid at an elevated 

location 7.2 km southeast of the Hennepin Power Station. The highest predicted concentration in the 

near-field from the power plant was 89.59 μg/m3, located about two kilometers east-southeast of the 

Hennepin Power Station and just east of the Advanced Asphalt facility. The colored contour map 

illustrated in Figure 12 provides a color-coded maximum predicted concentration for each receptor in 

the study area and indicates the location of the predicted maximum.
28

Figure 12

Maximum Predicted 99th Percentile 1-Hour SO2 - Hennepin Study Area

3.2.4 Designation Recommendation

Based on the Illinois EPA’s modeling results, the extent of the study area, and consideration of other 

SO2 sources in the multi-county area, Illinois EPA recommends that Putnam and Bureau Counties be 

designated as attainment for the 1-hour SO2 standard.
29

3.3 Marion Power Station (Williamson County)

The area south of the city of Marion in Williamson County contains a stationary source that 

satisfies one of the conditions (only one or the other required to qualify) of the March 2, 2015,

Consent Decree between U.S. EPA, Sierra Club, and the NRDC. The Marion Power Station emitted

less than the 16,000 tons (5,850) tons per year of SO2, but had an emission rate that exceeds 0.45 

lbs/mmBtu (0.489) in 2012. 

3.3.1 Study Area

The town of Marion, Illinois, is located in southern Illinois in the central portion of Williamson

County. The Marion Power Station (Southern Illinois Power Cooperative or SIPCO) is one of the five 

plants subject to SO2 Consent Decree. As depicted in Figure 13, the plant operates approximately 11

kilometers south-southwest of town in a rural area bounded on the east side by the Lake of Egypt, and 

a golf course on the southeast. The determination of the size and extent of the study area (i.e. 

receptor grid) was based on the same considerations assessed in the previous study areas. 

Figure 13 Marion Study Area (Williamson County)

3.3.2 Model Setup and Execution

As described in Section 3.1.2, AERMOD was used for the designation recommendation 

modeling. AERMOD is the dispersion modeling component of a much broader modeling system that 
30

includes multiple companion pre-processing programs that prepare other inputs into the model (BPIPPRIME, AERMET, AERMINUTE, AERMAP, and AERSURFACE).

3.3.2.1 Model Settings

The latest version of AERMOD (version 15181) was run in the standard regulatory default 

mode.

3.3.2.2 Auer’s Analysis 

The Auer’s discussion and analysis discussed in Section 3.1.1.1 was similarly applied to the 

Marion Study Area. The Auer’s analysis is a methodology for determining if the sources within the 

study area are located within a rural or urban dispersion regime. 

The three-kilometer ring applied in the Auer’s analysis for the Marion Study Area was centered 

on the Marion Power Station. The data source for land cover was the 2011 National Land Cover 

Database (NLCD), with a data cell size of 30-meters by 30-meters. The results of the Auer’s analysis 

are presented in Figure 14 and Table 9. 

Figure 14

Auer’s Analysis - Marion Study Area
31

Table 9

Auer’s Analysis Land Use Percentages by Category – Marion Study Area

The Auer’s analysis indicates the study area is approximately 98.5% rural and 1.5% urban; 

therefore the rural option applies to all emissions sources in the modeling domain.

3.3.2.3 Emissions

The determination of sources to model in the Marion Study Area consisted of compiling a list 

from the state inventory database of SO2 sources within a ten-kilometer radius of the Marion Power 

Station, while also evaluating the potential for sources beyond ten kilometers to cause a significant 

concentration gradient within the area. In the case of Marion, there were two facilities identified 

within the ten-kilometer area with SO2 emissions. The Marion Power Station, located 11 kilometers

south-southwest of the city of Marion, and the United States (U.S.) Penitentiary, located 

approximately six kilometers northwest of the power station. The two facilities were considered to 

have a potential impact in the near-field where maximum concentrations are expected. There were no 

sources beyond ten kilometers that Illinois EPA considers to have the potential to cause significant 

gradient impacts within the study area. The facility and their modeled tons per year 2012-2014 are 

presented in Table 10. 

NLCD Value NLCD 2011 Description Auer's Code Auer's Class Cell Count Percentage Totals

23 Developed, Medium Intensity R2/R3 388 1.24%

24 Developed, High Intensity I1/I2/C1 96 0.31%

11 Open Water A5 4,735 15.08%

21 Developed, Open Space A1/R4 1,684 5.36%

22 Developed, Low Intensity R1 2,549 8.12%

31 Barren Land (Rock/Sand/Clay) A3 57 0.18%

41 Deciduous Forest A4 10,349 32.95%

42 Evergreen Forest A4 562 1.79%

43 Mixed Forest A4 0 0.00%

52 Shrub/Scrub A4 0 0.00%

71 Grassland/Herbaceous A3 254 0.81%

81 Pasture/Hay A3 9,744 31.02%

82 Cultivated Crops A2 991 3.16%

90 Wood Wetlands A4 0 0.00%

95 Emergent Herbaceous Wetlands A3 0 0.00%

Grand Totals: 31,409 100.00%

Marion 3 km Ring

Urban

Analysis based on 30 meter by 30 meter raster cells extracted for each area.

Rural

1.54%

98.46%

SO2 NAA Modeling Auer's Analysis - NLCD 2011
32

Table 10

Modeled Facility Emissions – Marion Study Area

Company I.D. Facility Name

SO2 Emissions (tons per year)

2012 2013 2014

199856AAC Marion Power Station (SIPCO) 5512.11 5512.11 5512.11

155801AAC United States Penitentiary 0.18 0.18 0.18

Total Emissions All Facilities 5512.29 5512.29 5512.29

The four Marion Power Station stacks were modeled at maximum actuals expected from the 

source. The other facility in the modeling, United States Penitentiary, had no detailed hourly 

throughput or operating schedule data available, thus the conservative worst-case year emissions were 

applied to each year and spread uniformly throughout every hour. Please reference Appendix A for 

the full emissions inventory and stack parameters. For the Marion Study Area, a total of eight point 

sources were modeled. The hourly emissions file is included in this submittal via the DVD 

representing Appendix C.

3.3.2.4 Meteorology

The SO2 TAD recommends using the three most recent years of meteorology for use in the SO2

Phase II Designation modeling. 

The selection of a representative meteorological station for each of the study areas was based on 

proximity, similarity of terrain/surface roughness, and climatological consistency. For the Marion

Study Area, National Climatic Data Center National Weather Service (NWS) surface meteorology 

from Paducah, Kentucky (WBAN No. 3816, 64 km to the southeast), and coincident upper air 

observations from Nashville, Tennessee (WBAN No. 13897, 260 km to the southeast), was selected 

as best representative of meteorological conditions within the study area (PAH/NAS). 

The three-year surface wind rose for Paducah, Kentucky, is depicted in Figure 15. The 

frequency and magnitude of wind speed and direction are defined in terms of where the wind is 

blowing from, parsed out in twelve 30-degree wind sectors. The predominant wind direction during 

the three-year time period used in the modeling is from the southwest, occurring approximately 

11.4% of the time. The highest percentage wind speed range, occurring 32.9% of the time, was in the 

2.1 – 3.6 m/s range.
33

Figure 15

Paducah, Kentucky, Cumulative Annual Wind Rose

2012-2014

Meteorological data from the above surface and upper air stations was used in generating 

AERMOD-ready files with the AERMET processor, a part of the AERMOD software suite. The 

output meteorological data created by the AERMET processor is considered suitable for being 

applied in AERMOD for regulatory modeling applications. The methodology and settings performed 

in the processing of the raw meteorological data into AERMOD-ready format followed the same 

procedure as in the Newton Study Area. Please refer to Section 3.1.2.4 for more details on the

development procedure utilized for the meteorological inputs. The Marion Study Area AERMODWRPLOT View - Lakes Environmental Software

WIND ROSE PLOT:

Station #3816 - PADUCAH/WSO AIRPORT, KY 

COMMENTS:

Direction Wind is blowing from.

COMPANY NAME:

MODELER:

DATE:

9/4/2015

PROJECT NO.:

NORTH

SOUTH

WEST EAST

3%

6%

9%

12%

15%

WIND SPEED 

(m/s)

 >= 11.1

 8.8 - 11.1

 5.7 - 8.8

 3.6 - 5.7

 2.1 - 3.6

 0.5 - 2.1

Calms: 1.79%

TOTAL COUNT:

26241 hrs.

CALM WINDS:

1.79%

DATA PERIOD:

Start Date: 1/1/2012 - 00:00

End Date: 12/31/2014 - 23:00

AVG. WIND SPEED:

3.24 m/s

DISPLAY:

 Wind Speed

Direction (blowing from)
34

ready “.sfc” and “.pfl” meteorological electronic files are included in this submittal via the DVD 

representing Appendix C. 

3.3.2.5 Receptor Network/Terrain 

The receptor grid for Marion was designed to be of sufficient density and size to capture all 

relevant concentration gradients from modeled sources and to adequately resolve the maximum 

predicted SO2 design value concentration. The terrain to the south of the Marion Power Station 

contains forested, complex terrain, thus the receptor grid was extended a sufficient distance to ensure 

the maximums were captured. The receptor grid’s dense 100-meter spacing, using a Cartesian 

gridding method, was extended outward from each fenceline to at least five kilometers distance from 

each facility (extent may vary slightly by direction). The study area receptor spacing was 

approximately:

 50 meters along the fenceline (two facilities)

 100 meters from the fenceline out to approximately 5.0 kilometers

 500 meters from 5.0 kilometers out to approximately 8.0 kilometers

 1,000 meters from 8.0 kilometers out to approximately 10 kilometers

The Marion Study Area receptor grid is presented in Figure 16. The receptor count totaled 

25,118 receptors, covering central and south-central Williamson County, the northeast corner of 

Union County, and the northwest and north-central part of Johnson County. The terrain in the study 

area is best characterized as complex to gently rolling (south to north). To account for terrain 

changes, the AERMAP terrain program was used to develop terrain and hill scale height for all the 

receptors. The source of the elevation data incorporated into the model is from the USGS National 

Elevation Database (NED). 
35

Figure 16

Receptor Grid – Marion Study Area

3.3.2.6 Background SO2 

The regional sources not explicitly modeled in AERMOD, but best characterized as background 

contributors to SO2 near or in the study area, are addressed via background monitoring data. U.S. 

EPA recommends inclusion into the model data from the nearest representative background SO2

monitor operated by state, local, or tribal organizations. The Houston, Illinois, monitor was selected 

for the Marion study area. The Houston monitor is located approximately 94 kilometers northwest of 

the study area in northern Randolph County in the small town of Houston. The monitor, operated and 

maintained by Illinois EPA, has validated hourly SO2 concentrations for the three years modeled in 

this analysis (2012-2014). 

For this modeling application, Illinois EPA incorporated temporally-varying background 1-hour 

concentrations developed from the Houston, Illinois, monitor. The values developed for inputs are 

based on the 99th percentile monitored concentrations and vary by hour and season in the same 

manner as discussed previously for the other study areas. Modeled concentrations include the 
36

contribution of the background values. A table of the background SO2 seasonally and hourly varying 

values utilized in the Marion Study Area modeling is provided in Appendix B. 

3.3.3 Summary of Results

The AERMOD simulation for the Marion Study Area comprised eight stacks, 37 structures, two

fencelines, and 25,118 receptors. The model simulated 2012-2014, while taking into account 

maximum actual emissions expected from the source, combining such emissions, meteorology, 

terrain, and background SO2 levels into the model to calculate a maximum 99th percentile 1-hour SO2

concentration for each receptor in the grid. The results presented in Table 11 report the magnitude 

and geographic location of the highest predicted concentration.

Table 11

Maximum Predicted 99th Percentile 1-Hour SO2 Concentration

Marion Study Area

Averaging Period Data 

Period

Receptor Location 

(Meters)

SO2 Concentration

(μg/m3)

East North Modeled NAAQS

99th Percentile 1-

Hour Average 2012-2014 327200 4166200 194.48 196.32*

* Equivalent to the 75 ppb standard

The maximum predicted 99th percentile 1-hour average concentration within the modeling domain is 

194.48 μg/m3, or 74.3 ppb. The maximum occurred within the dense 100-meter grid 1.2 km northnorthwest of the Marion Power Station. The color coded contour map in Figure 17 depicts maximum 

predicted concentrations for each receptor in the study area and indicates the location of the predicted 

maximum.
37

Figure 17

Maximum Predicted 99th Percentile 1-Hour SO2 Concentrations - Marion Study Area

3.3.3 Designation Recommendation

Based on the modeling results, the extent of the study area, and consideration of other SO2 sources in 

the multi-county area, Illinois EPA recommends that Williamson County be designated attainment

for the 1-hour SO2 standard.
38

3.4 Joppa Steam Coal Power Plant (Massac County)

The area west of the town of Joppa in Massac County contains a stationary source that satisfies 

one of the conditions (only one or the other required to qualify) of the March 2, 2015, Consent 

Decree between U.S. EPA, Sierra Club, and the NRDC. The Joppa Power Station emitted greater 

than the 16,000 tons (16,991) tons per year of SO2, and had an emission rate that exceeds 0.45 

lb/mmBtu (0.475) in 2012. 

3.4.1 Study Area

The town of Joppa, Illinois, is located in southern Illinois in the western portion of Massac

County. The Joppa Power Station is one of the five plants subject to the SO2 Consent Decree. As 

depicted in Figure 18, the plant is located approximately 1.0 kilometer west-northwest of town in a 

rural area bounded on the south by the Ohio River. The size and extent of the study area (i.e. receptor 

grid) was based on the same considerations described for previous study areas. 

Figure 18

Joppa Study Area (Massac County)
39

3.4.2 Model Setup and Execution

As described in Section 3.1.2, AERMOD was used for the designation recommendation 

modeling. AERMOD is the dispersion modeling component of a much broader modeling system that 

includes multiple companion pre-processing programs that prepare other inputs into the model (BPIPPRIME, AERMET, AERMINUTE, AERMAP, and AERSURFACE).

3.4.2.1 Model Settings

The latest version of AERMOD (version 15181) was run in its standard regulatory default mode.

3.4.2.2 Auer’s Analysis 

The Auer’s discussion and analysis discussed in Section 3.1.1.1 was similarly applied to the 

Joppa Study Area. The Auer’s analysis is a methodology for determining if the sources within the 

study area are located within a rural or urban dispersion regime. 

The three-kilometer ring applied in the Auer’s analysis for the Marion Study Area is centered on 

the Marion Power Station. The data source for land cover was the 2011 National Land Cover 

Database (NLCD), with a data cell size of 30-meters by 30-meters. The results of the Auer’s analysis 

are presented in Figure 19 and Table 12. 
40

Figure 19

Auer’s Analysis - Joppa Study Area

Table 12

Auer’s Analysis Land Use Percentages by Category – Joppa Study Area

NLCD Value NLCD 2011 Description Auer's Code Auer's Class Cell Count Percentage Totals

23 Developed, Medium Intensity R2/R3 825 2.63%

24 Developed, High Intensity I1/I2/C1 427 1.36%

11 Open Water A5 7,189 22.89%

21 Developed, Open Space A1/R4 1,756 5.59%

22 Developed, Low Intensity R1 1,196 3.81%

31 Barren Land (Rock/Sand/Clay) A3 163 0.52%

41 Deciduous Forest A4 6,400 20.38%

42 Evergreen Forest A4 0 0.00%

43 Mixed Forest A4 0 0.00%

52 Shrub/Scrub A4 0 0.00%

71 Grassland/Herbaceous A3 0 0.00%

81 Pasture/Hay A3 7,677 24.44%

82 Cultivated Crops A2 3,623 11.53%

90 Wood Wetlands A4 1,963 6.25%

95 Emergent Herbaceous Wetlands A3 191 0.61%

Grand Totals: 31,409 100.00%

3.99%

96.01%

SO2 NAA Modeling Auer's Analysis - NLCD 2011 Joppa 3 km Ring

Urban

Analysis based on 30 meter by 30 meter raster cells extracted for each area.

Rural
41

The Auer’s analysis indicates the study area is approximately 96% rural and 4% urban; therefore 

the rural option applies to all emissions sources in the modeling domain.

3.4.2.3 Emissions

As discussed in previous sections, the most recent three years of actual emissions were used to 

best represent the emissions that would simulate the air quality for a three-year monitoring dataset in 

determining compliance with the NAAQS. In this application, actual emissions were used from the 

most recently available years (2012-2014). 

Determining sources to model in the Joppa Study Area consisted of compiling a list from the 

state inventory database of SO2 sources within a ten-kilometer radius of the Joppa Power Station, 

while also evaluating the potential for sources beyond ten kilometers to cause a significant 

concentration gradient within the area. In the case of the Joppa Study Area, there were six facilities 

identified within the ten-kilometer area with SO2 emissions. The Joppa Power Station, Lafarge 

Midwest International, Inc. Trunkline Gas Company, and Midwest Electric Power are all located 

within a short distance from each other. The Honeywell International Inc. and the Tennessee Valley 

Authority (TVA) Shawnee Power Plant (Kentucky) are located approximately ten kilometers

southeast of the other facilities. These six facilities were considered to have a potential impact in the 

study area where maximum concentrations are expected. There were no sources beyond ten 

kilometers that Illinois EPA considers to have the potential to cause significant concentration gradient 

impacts within the study area. The facilities and associated annual actual emission tonnages (2012-

2014) are listed in Table 13. 

Table 13

Modeled Facility Actual Emissions – Joppa Study Area

Company I.D. Facility Name

SO2 Emissions (tons per year)

2012 2013 2014

127855AAC Joppa PS (Electric Energy Inc.) 17,007.07 16,557.74 18,229.24

127855AAA Lafarge Midwest Inc. 552.60 553.28 491.65

127899AAA Midwest Electric Power Inc. (MEPI) 5.68 0.00 0.00

127855AAB Trunkline Gas Company 0.866 0.866 0.866

127854AAD Honeywell International Inc. 162.51 58.73 143.15

2114500006 TVA – Shawnee Power Plant 27,114.87 27,210.73 29,734.54

Total Emissions All Facilities 44,843.60 44,381.46 48,599.45

Emissions profiles for the Joppa inventory were developed using the AERMOD keyword 

HOUREMIS and from applying a direct worst-case actual year for one of the facilities. Illinois EPA

used hourly varying 2012-2014 CEMS SO2 emissions data provided by the Joppa Power Station for 
42

its boiler stacks, along with hourly-specific exit temperatures and exit velocities. For Lafarge, the 

emissions from the two cement kiln stacks constitute 99.9% of the facility emissions, therefore those 

two sources were modeled with company provided hourly varying emissions, temperature, and exit 

velocity. MEPI provided hourly varying emissions for their operating units/stacks for the three-year 

period. Trunkline’s emissions were constructed from contained in the company’s Annual Emissions

Reports, including yearly emissions data and seasonal throughput. Seasonal emissions were averaged 

over the three years, multiplied by a scalar (via EMISFACT keyword in AERMOD), and then applied 

to the three-year modeling period. Nearly all of Honeywell’s facility SO2 emissions (99.9%) exhaust 

from the waste incinerator unit. A three-year hourly profile was constructed for the three years based 

on seasonal throughput. CEMS data obtained via U.S. EPA’s CAMD database was used to construct 

hourly emissions rates for the TVA-Shawnee Boiler Stacks. For all sources in the Joppa inventory 

that lacked CEMS data, Illinois EPA used a constant value for exit temperature and exit velocity for 

each hour of the modeled period. These constant values were obtained either from the Illinois EPA

database or from company-provided emission report submittals. Please reference Appendix A for the 

full emissions inventory and stack parameters, including the substitution methods employed for 

addressing missing or erroneous data fields for CEMS data. For the Joppa Study Area, a total of 17

point source stacks were modeled. AERMOD’s HOUREMIS keyword was applied to 12 of the point 

sources. The EMISFACT keyword was applied to the remaining five sources. The hourly emissions 

file is included in this submittal via the DVD representing Appendix C.

3.4.2.4 Meteorology

The SO2 TAD recommends using the three most recent years of meteorology for use in SO2 area 

designations modeling. 

The selection of a representative meteorological station for each of the study areas was based on 

proximity, similarity of terrain/surface roughness, and climatological consistency. For the Joppa

Study Area, the National Climatic Data Center National Weather Service (NWS) surface meteorology 

from Paducah, Kentucky (WBAN No. 3816, 18 km to the southeast), and coincident upper air 

observations from Nashville, Tennessee (WBAN No. 13897, 228 km to the southeast), were selected 

as best representative of meteorological conditions within the study area (PAH/NAS). 

The three-year surface wind rose for Paducah, Kentucky, is depicted in Figure 20. The 

frequency and magnitude of wind speed and direction are defined in terms of where the wind is 

blowing from, parsed out in twelve 30-degree wind sectors. The predominant wind direction during 

the three-year time period used for the modeling is from the southwest, occurring approximately 

11.4% of the time. The highest percentage wind speed range, occurring 32.9% of the time, was in the 

2.1 – 3.6 m/s range.
43

Figure 20

Paducah, Kentucky, Cumulative Annual Wind Rose

2012-2014

Meteorological data from the above surface and upper air stations were used in generating 

AERMOD-ready files with the AERMET processor, a part of the AERMOD software suite. The 

output meteorological data created by the AERMET processor is considered suitable for use in

AERMOD in regulatory modeling applications. The methodology and settings invoked in processing 

the raw meteorological data into AERMOD-ready format followed the same procedure as in the 

Newton Study Area. Please refer to Section 3.1.2.4 for more details on the development procedure 

WRPLOT View - Lakes Environmental Software

WIND ROSE PLOT:

Station #3816 - PADUCAH/WSO AIRPORT, KY 

COMMENTS:

Direction Wind is blowing from.

COMPANY NAME:

MODELER:

DATE:

9/4/2015

PROJECT NO.:

NORTH

SOUTH

WEST EAST

3%

6%

9%

12%

15%

WIND SPEED 

(m/s)

 >= 11.1

 8.8 - 11.1

 5.7 - 8.8

 3.6 - 5.7

 2.1 - 3.6

 0.5 - 2.1

Calms: 1.79%

TOTAL COUNT:

26241 hrs.

CALM WINDS:

1.79%

DATA PERIOD:

Start Date: 1/1/2012 - 00:00

End Date: 12/31/2014 - 23:00

AVG. WIND SPEED:

3.24 m/s

DISPLAY:

 Wind Speed

Direction (blowing from)
44

utilized for the meteorological inputs. The Joppa Study Area AERMOD-ready “.sfc” and “.pfl” 

meteorological files are included in this submittal via the DVD representing Appendix C. 

3.4.2.5 Receptor Network/Terrain 

The receptor grid for the Joppa Study Area was designed to be of sufficient density and size to 

capture all relevant concentration gradients from modeled sources and to adequately resolve the 

maximum predicted SO2 design value concentration. The receptor grid’s dense 100-meter spacing 

was created in two distinct sections, one that surrounds the grouping of sources around the Joppa 

Power Station, and another that captures the impacts around the Honeywell/TVA plants. In general, 

the fine 100-meter Cartesian grid was extended outward from each fenceline to at least three

kilometers distance from each facility (extent may vary slightly by direction). The entire study area 

receptor spacing was approximately:

 50 meters spacing along the fenceline (six facilities)

 100 meters out to approximately 3.0 kilometers

 500 meters from 3.0 kilometers out to approximately 8.0 kilometers

 1,000 meters from 8.0 kilometers out to approximately 12 kilometers

The Joppa Study Area receptor grid is presented in Figure 21. The receptor network contained

25,649 receptors, covering northwestern Massac County in Illinois, the northeastern portion of 

Ballard County in Kentucky, and the northwestern portion of McCracken County in Kentucky. The 

terrain in the study area is best characterized as flat to gently rolling and is bisected west-to east 

through its central part by the Ohio River. To account for terrain changes, the AERMAP terrain 

program was used to generate elevations and hill height for all receptors. The source of the elevation 

data is the USGS National Elevation Database (NED).
45

Figure 21

Receptor Grid – Joppa Study Area

3.4.2.6 Background SO2 

The regional sources not explicitly modeled in AERMOD, but best characterized as background 

contributors to SO2 near or in the study area, are addressed via background monitoring data. U.S. 

EPA recommends inclusion in the model of data from the nearest representative background SO2

monitor operated by state, local, or tribal organizations. The Paducah, Kentucky, monitor was 

selected for the Joppa study area. The Paducah monitor is located approximately 18 kilometers 

southeast of the study area in north-central McCracken County in the city of Paducah, Kentucky. The 

monitor, operated and maintained by the Kentucky Division of Air Quality (KDAQ), has validated 

hourly SO2 concentrations for the three years modeled in this analysis (2012-2014). 

For this modeling application, Illinois EPA incorporated temporally-varying background 1-hour 

concentrations developed from the Paducah, Kentucky, monitor. The values developed for inputs 

into AERMOD for background are based on the 99th percentile monitored concentrations that vary by 
46

season and hour in the same manner as in the previously discussed study areas. For modeled design 

value impacts for comparison to the standard reported here, the maximum impacts include the 

contribution of background. A table of the background SO2 seasonally and hourly varying values 

utilized in the Joppa Study Area modeling is provided in Appendix B. 

3.4.3 Summary of Results

The AERMOD simulation for the Joppa Study Area comprised 18 stacks, 127 structures, six

fencelines, and 25,649 receptors. The model simulated 2012-2014, combining emissions, 

meteorology, terrain, and background SO2 levels into the model to calculate a maximum 99th

percentile 1-hour SO2 concentration for each receptor in the grid. The results presented in Table 14

report the magnitude and geographic location of the highest predicted concentration.

Table 14

Maximum Predicted 99th Percentile 1-Hour SO2 Concentration

Joppa Study Area

Averaging Period Data 

Period

Receptor Location 

(Meters)

SO2 Concentration

(μg/m3)

East North Modeled NAAQS

99th Percentile 1-

Hour Average 2012-2014 332800 4121600 168.29 196.23*

* Equivalent to the 75 ppb standard

The maximum predicted 99th percentile 1-hour average concentration within the modeling domain is 

168.29 μg/m3, or 64.2 ppb. This maximum occurred within the dense 100-meter grid approximately 

2.9 km northwest of the Joppa Power Station main stacks and 0.4 km northwest of the Lafarge 

northern fenceline. The colored contour map of maximum 99th percentile concentrations presented in 

Figure 22 depicts maximum predicted concentration for each receptor in the study area and indicates 

the location of the predicted maximum. 
47

Figure 22

Maximum Predicted 99th Percentile 1-Hour SO2 Concentrations – Joppa Study Area

3.4.4 Designation Recommendation

Based on the modeling results, the extent of the study area, and consideration of other SO2 sources in 

the study area, Illinois EPA recommends that Massac County be designated as attainment for the 1-

hour SO2 standard.
48

3.5 Wood River Power Station (Madison County)

Wood River in Madison County, Illinois, contains a stationary source that satisfies one of the 

conditions (only one or the other required to qualify) of the March 2, 2015, Consent Decree between 

U.S. EPA, Sierra Club, and the NRDC. The Wood River Power Station emitted less than 16,000 tons 

(6,756) tons per year of SO2, but had an emission rate that exceeds 0.45 lbs/mmBtu (0.476) in 2012. 

3.5.1 Study Area

The city of Wood River is part of the St. Louis Metropolitan Statistical Area (MSA) and is 

located northeast of the urban core east of the Mississippi River in Illinois. The Wood River Power 

Station is one of the five plants subject to the SO2 Consent Decree. As depicted in Figure 23, the 

plant is located along the Mississippi River in western Madison County in a community with 

residential, commercial, and industrial areas. The size and extent of the study area (i.e., receptor grid) 

were based on the same considerations described previously for other study areas. 

Figure 23

Wood River Study Area (Madison County)
49

3.5.2 Model Setup and Execution

As described in Section 3.1.2, AERMOD was used for the designation recommendation 

modeling. AERMOD is the dispersion modeling component of a much broader modeling system that 

includes multiple companion pre-processing programs that prepare other inputs into the model (BPIPPRIME, AERMET, AERMINUTE, AERMAP, and AERSURFACE).

3.5.2.1 Model Settings

The latest version of AERMOD (version 15181) was run in the standard regulatory default 

mode.

3.5.2.2 Auer’s Analysis 

The Auer’s discussion and analysis in Section 3.1.1.1 similarly apply to the Wood River Study 

Area. The Auer’s analysis is a methodology for determining if the sources within the study area are 

located within a rural or urban dispersion regime. 

The three-kilometer ring applied in the Auer’s analysis for the Wood River Study Area was 

centered on the Wood River Power Station. The data source for land cover was the 2011 National 

Land Cover Database (NLCD), with a raster data cell size of 30 meters by 30 meters. The results of 

the Auer’s analysis are presented in Figure 24 and Table 15. The Auer’s analysis indicates the study 

area is approximately 80.1% rural and 19.9% urban; therefore the rural option applies to all emissions 

sources in the modeling domain.
50

Figure 24

Auer’s Analysis – Wood River Study Area

Table 15

Auer’s Analysis Land Use Percentages by Category – Wood River Study Area

NLCD Value NLCD 2011 Description Auer's Code Auer's Class Cell Count Percentage Totals

23 Developed, Medium Intensity R2/R3 3,562 11.34%

24 Developed, High Intensity I1/I2/C1 2,683 8.54%

11 Open Water A5 5,379 17.13%

21 Developed, Open Space A1/R4 2,644 8.42%

22 Developed, Low Intensity R1 4,090 13.02%

31 Barren Land (Rock/Sand/Clay) A3 81 26.00%

41 Deciduous Forest A4 5,825 1.67%

42 Evergreen Forest A4 0 0.00%

43 Mixed Forest A4 6 0.00%

52 Shrub/Scrub A4 69 0.22%

71 Grassland/Herbaceous A3 45 0.14%

81 Pasture/Hay A3 216 0.69%

82 Cultivated Crops A2 6,989 22.25%

90 Wood Wetlands A4 4,699 14.96%

95 Emergent Herbaceous Wetlands A3 421 1.34%

Analysis based on 30 meter by 30 meter raster cells extracted for each area. Grand Totals: 31,409 100.00%

19.88%

80.12%

S O2 NAA Modeling Auer's Analysis - NLCD 2011 Wood River 3 km Ring

Urban

Rural
51

3.5.2.3 Emissions 

The most recent three years of actual emissions were used to represent the emissions that would 

simulate the impacts of a three-year monitoring dataset for determining compliance with the NAAQS. 

In this application, actual emissions were used from the 2012-2014. 

Determining the sources to model in the Wood River Study Area consisted of compiling a list 

from the state inventory database of SO2 sources within a 10 km radius of the Wood River Power 

Station, while also evaluating the potential for sources beyond 10 km to cause a significant 

concentration gradient within the area. In the case of the Wood River Study Area, there were five

facilities (see Figure 23) identified and included in the modeling within the 10 km area with actual 

SO2 emissions greater than 0.5 tons per year in one of the three years evaluated. They are the Wood 

River Power Station, WRB Refining Inc. (formerly named ConocoPhillips), Alton Steel, Inc., Christ 

Brothers Products LLC, and National Maintenance and Repair facilities. The Ameren UE Sioux 

Power Plant, located just west of Portage Des Sioux, Missouri, was also included in the modeling due 

to its tall stacks and high annual emissions. It is located approximately 18 kilometers west-northwest 

of the center of the study area. There were seven additional facilities examined in the Wood River 

Study Area. All reported actual emissions of less than half a ton per year in any of the years 2012-

2014, thus they are not explicitly modeled and their impacts are considered to be represented by 

existing background monitoring. In summary, six facilities were considered to have a potential 

significant impact gradient impact in the study area where maximum concentrations are expected. 

Each facility and its modeled actual emissions for 2012-2014 are presented in Table 16. 

Table 16

Modeled Facility Actual Emissions – Wood River Study Area

Company I.D. Facility Name

SO2 Emissions (tons per year)

2012 2013 2014

119020AAE Wood River Power Station 6,719.49 7,662.27 7,034.66

119090AAA WRB Refining LLC 1,966.48 1,203.08 1,103.42

119010AAE Alton Steel, Inc. 42.75 38.00 39.35

119097AAB Christ Brothers Products 7.20 7.20 7.20

1190801AAE National Maintenance and Repair 3.93 3.93 3.93

183-0001 Ameren Missouri Sioux Power 

Station 2,658.45 2,799.27 1,483.75

Total Emissions All Facilities 11,398.30 11,713.75 9,672.31

Emissions profiles for the Wood River inventory were developed using AERMOD keyword 

HOUREMIS, EMISFACT, and, in some instances when lacking sufficient info to construct hourly 

profiles, conservatively applying the worst-case actual year to each of the three years. Illinois EPA

used hourly varying 2012-2014 CEMS SO2 emissions data provided by the Wood River Power 

Station for its boiler stacks in the dispersion modeling, including temporally varying exit temperature 
52

and exit velocity. For the Units 1-3 stack, a conservative worst-case emissions year was applied to all 

three years. WRB Refining provided three years of hourly varying emissions, temperature, and exit 

velocity for their operating units/stacks for the modeling period. For Alton Steel, operating schedule 

and yearly emissions provided by the company for the Electric Arc Furnace (EAF) and Ladle 

Metallurgy Furnace (LMF) exhaust emissions allowed Illinois EPA to construct a three-year 

emissions profile. For the two other sources at the facility, a conservative worst-case emissions year 

was applied to all three years. The worst-case emissions year was applied for the entire simulation 

for Christ Brothers and National Maintenance and Repair. Hourly CEMS SO2 emissions data were

used for the Ameren Sioux Power Plant. In instances where seasonal throughput was available, 

emissions were allocated appropriately via the EMISFACT keyword in AERMOD and applied to the 

three-year period. For sources lacking hourly varying temperature or exit velocity, replacement 

values were obtained either from the Illinois EPA database or from company-provided emission 

reports. Please reference Appendix A for the full emissions inventory and stack parameters, 

including the substitution methods implemented for addressing missing or erroneous data fields

within the CEMS data. For the Wood River Study Area, a total of 82 point source stacks were 

modeled. AERMOD’s HOUREMIS keyword was applied to 75 of the point sources, while the 

remaining seven point sources received either worst-case emissions uniformly applied for the entire 

simulation period, or utilized EMISFACT to make seasonal adjustments to emissions. The electronic 

hourly emissions file is included in this submittal via the DVD located in Appendix C.

3.5.2.4 Meteorology

The SO2 TAD recommends using the three most recent years of meteorology for use in the SO2

Phase II Designation modeling. 

The selection of a representative meteorological station for each of the study areas was based on 

proximity, similarity of terrain/surface roughness, and climatological consistency. For the Wood 

River Study Area, the National Climatic Data Center National Weather Service (NWS) surface 

meteorology from St. Louis, Missouri (WBAN No. 13994, 27 km to the southwest), and coincident 

upper air observations from Lincoln, Illinois (WBAN No. 4833, 158 km to the northeast), were

selected as best representative of meteorological conditions within the study area (STL/ILX). 

The three-year surface wind rose for St. Louis, Missouri, is depicted in Figure 25. The frequency 

and magnitude of wind speed and direction are defined in terms of where the wind is blowing from, 

parsed out in twelve 30-degree wind sectors. The most predominant wind direction during the threeyear time period used in the modeling is from the southeast to southwest, occurring approximately 

9.6% of the time. The highest percentage wind speed range, occurring 33.8% of the time, was in the 

3.6 – 5.7 m/s range.
53

Figure 25

St. Louis, Missouri, Cumulative Annual Wind Rose

2012-2014

Meteorological data from the above surface and upper air stations were used in generating 

AERMOD-ready files with the AERMET processor, a part of the AERMOD software suite. The 

output meteorological data created by the AERMET processor is considered suitable for being 

applied in AERMOD for regulatory modeling applications. The methodology and settings performed 

WRPLOT View - Lakes Environmental Software

WIND ROSE PLOT:

Station #13994 - ST LOUIS/LAMBERT INT'L ARPT, MO 

COMMENTS:

Direction Wind is blowing from.

COMPANY NAME:

MODELER:

DATE:

9/5/2015

PROJECT NO.:

NORTH

SOUTH

WEST EAST

2%

4%

6%

8%

10%

WIND SPEED 

(m/s)

 >= 11.1

 8.8 - 11.1

 5.7 - 8.8

 3.6 - 5.7

 2.1 - 3.6

 0.5 - 2.1

Calms: 0.67%

TOTAL COUNT:

26292 hrs.

CALM WINDS:

0.67%

DATA PERIOD:

Start Date: 1/1/2012 - 00:00

End Date: 12/31/2014 - 23:00

AVG. WIND SPEED:

4.05 m/s

DISPLAY:

 Wind Speed

Direction (blowing from)
54

in the processing of the raw meteorological data into AERMOD-ready format followed the same 

procedure as in the Newton Study Area. Please refer to Section 3.1.2.4 for more details on the 

development procedure utilized for the meteorological inputs. The Wood River Study Area 

AERMOD-ready “.sfc” and “.pfl” meteorological electronic files are included in this submittal via 

DVD located in Appendix C. 

3.5.2.5 Receptor Network/Terrain 

The receptor grid for the Wood River Study Area was designed to be of sufficient density and 

size to capture all relevant concentration gradients from modeled sources and to adequately resolve 

the maximum predicted SO2 design value concentration. The receptor grid’s dense 100-meter spacing 

was created in two distinct sections, one that surrounds the grouping of sources around the Wood 

River Power Station, and another that captures the impacts around the WRB Refining facility. In 

general, the fine 100-meter Cartesian grid was extended outward from each fenceline in the vicinity 

of the Power Station sources by at least two kilometers distance from each facility (extent may vary 

slightly by direction) and by at least one kilometer from the smaller facilities south of WRB Refining. 

The entire study area receptor spacing was approximately:

 50 meters along the fenceline (six facilities)

 100 meters from the fenceline out to 1.0 to 2.0 kilometers

 500 meters from 1.0 to 2.0 kilometers out to 9.0 kilometers

The Wood River Study Area receptor grid is presented in Figure 26. The receptor count totaled 

11,746 receptors, covering extreme west-central Madison County in Illinois, and eastern edges of St. 

Louis and St. Charles Counties in Missouri. The terrain in the study area is best characterized as flat 

to gently rolling and is bisected northeast to southeast western extent by the Mississippi River. To 

account for terrain changes, the AERMAP terrain program was used to develop terrain and hill scale 

height for all the receptors. The source of the elevation data incorporated into the model is from the 

USGS National Elevation Database (NED). 
55

Figure 26

Receptor Grid – Wood River Study Area

3.5.2.6 Background SO2 

The regional sources not explicitly modeled in AERMOD, but best characterized as background 

contributors to SO2 near or in the study area, are addressed via background monitoring data. U.S. 

EPA recommends inclusion into the model data from the nearest representative background SO2

monitor operated by state, local, or tribal organizations. The East St. Louis, Illinois monitor was 

selected for the Wood River Study area. The East St. Louis monitor is located approximately 28

kilometers south of the study area in northwestern St. Clair County and is ideally suited to 

characterize contributions from background sources in semi-urbanized environment of the St. Louis 

MSA area. The monitor, operated and maintained by Illinois EPA, has validated hourly SO2

concentrations for the three years modeled in this analysis (2012-2014). 

For this modeling application, Illinois EPA employed temporally-varying background 1-hour 

concentrations developed from the East St. Louis, Illinois, monitor. The values developed for inputs 
56

into AERMOD for background are based on the 99th percentile monitored concentrations vary by 

season and hour in the same manner as in the previously discussed study areas. For modeled design 

value impacts for comparison to the standard reported here, the maximum impacts include the 

contribution of background. A table of the background SO2 seasonally and hourly varying values 

utilized in the Wood River Study Area modeling is provided in Appendix B. 

3.5.3 Summary of Results

The AERMOD simulation for the Wood River Study Area comprised 82 stacks, 527 structures, 10

fencelines, and 11,746 receptors. The model simulated 2012-2014, combining emissions, 

meteorology, terrain, and background SO2 levels into the model to calculate a maximum 99th

percentile 1-hour SO2 concentration for each receptor in the grid. The results presented in Table 14 

report the magnitude and geographic location of the highest predicted concentration.

Table 17

Maximum Predicted 99th Percentile 1-Hour SO2 Concentration

Wood River Study Area

Averaging Period Data 

Period

Receptor Location 

(Meters)

SO2 Concentration

(μg/m3)

East North Modeled NAAQS

99th Percentile 1-

Hour Average 2012-2014 748051 4307978 456.50 196.23*

* Equivalent to the 75 ppb standard

The maximum predicted 99th percentile 1-hour average concentration within the modeling domain is 

460.50 μg/m3, or 174.2 ppb. The maximum occurred within the dense 100-meter grid approximately 

2.5 kilometers northwest of the Wood River Power Station main stacks. The maximum occurred on 

the north fenceline of Alton Steel, Inc. The colored contour map of maximum 99th percentile 

concentrations presented in Figure 27 depicts maximum predicted concentration for each receptor in 

the study area and indicates the location of the predicted maximum. 
57

Figure 27

Maximum Predicted 99th Percentile 1-Hour SO2 Concentrations - Wood River Study Area

3.5.4 Designation Recommendation

The modeling results indicate there are 14 receptors along and near (within 100 meters) of the north 

fenceline of the Alton Steel facility predicted to exceed the 99th percentile 1-hour SO2 standard. 

Culpability modeling analyses indicate that four SO2 stacks at Alton Steel related to their LMF

process are causing these violations. These four stacks point down toward the ground at a 45 degree 

angle from the south side of the LMF baghouse structure and are heavily influenced by downwash 

from the Electric Furnace Shop building. Due to the “hotspot” nature of the modeled violations and 

their close proximity to the Alton Steel facility, Illinois EPA recommends that a portion of Madison 

County be designated as nonattainment for the 2010 1-hour SO2 NAAQS – specifically, that 

portion of southern Alton Township that is east of the Corporal Belchik Memorial Expressway, south 

of East Broadway Street and Illinois Route 3, and north of Illinois Route 143, as shown in Figure 28. 
58

Per U.S. EPA’s guidance, this area contains both the violating receptors and the emission sources 

causing or contributing to nonattainment. Illinois EPA also recommends that all of Wood River 

Township and that portion of Chouteau Township north of the Cahokia Diversion Channel be 

designated as attainment. Lastly, the Illinois EPA recommends that the remainder of Madison 

County be designated as unclassifiable due to the presence of additional large SO2 emitting facilities 

in other parts of the county that will likely need to be addressed later by the Illinois EPA in 

accordance with the Data Requirements Rule (DRR).

Figure 28

Proposed Nonattainment Area Boundary for the Wood River Study Area
59

4.0 Summary

The Illinois EPA has conducted a five factor analysis that relies heavily upon the results of dispersion 

modeling to support recommendations for 1-hour SO2 NAAQS area designations under the March, 

2015, consent decree between U.S. EPA, Sierra Club, and the Natural Resources Defense Council. 

That analysis specifically addressed five power plants in Illinois: Newton Power Station (Jasper 

County), Hennepin Power Station (Putnam County), Joppa Steam Coal Power Plant (Massac 

County), Marion Power Station (Williamson County) and Wood River Power Station (Madison 

County). 

With the exception of Madison County, the Illinois EPA is recommending attainment for the 

presumptive area boundary (countywide) in which the power plant is located. In the case of the 

Hennepin Power Station, the Illinois EPA is also recommending attainment status for all of Bureau 

County, which is located across the Illinois River from the power plant. Modeled concentrations in 

Bureau County were well below the NAAQS, and the aggregate contribution of all SO2-emitting 

sources in Bureau County is less than five tons per year (actual emissions, based upon Illinois EPA’s 

ICEMAN 2011 database). 

Modeling conducted for the Wood River Power Station (Madison County) has yielded sub-county 

area recommendations for attainment, nonattainment, and unclassifiable. There is a small area in 

Alton Township (south of East Broadway and adjacent to the Alton Steel, Inc. facility) where

modeled impacts exceed the NAAQS. This area is recommended for nonattainment; however, the 

Agency fully expects that corrective measures will be taken that will enable a modeling 

demonstration of compliance with the NAAQS by January 15, 2016. Wood River Township contains 

the Wood River Power Station, and this area along with that portion of Chouteau Township north of 

the Cahokia Diversion Channel is recommended for attainment. All other portions of Madison 

County are recommended as unclassifiable.
60

5.0 References

 Auer, Jr., A.H. (1978). Correlation of Land Use and Cover with Meteorological Anomalies. Journal 

of Applied Meteorology, 17(5), 636-643.

U.S. EPA (December 2013). SO2 NAAQS Designations Modeling Technical Assistance Document

http://www3.epa.gov/airquality/sulfurdioxide/pdfs/SO2ModelingTAD.pdf

U.S. EPA (August 2015). AERMOD Implementation Guide

http://www3.epa.gov/ttn/scram/7thconf/aermod/aermod_implmtn_guide_3August2015.pdf

U.S. EPA (November 2004). User’s Guide for the AERMOD Meteorological Preprocessor 

U.S. EPA (March 2015). Updated Guidance for Area Designations for the 2010 Primary Sulfur 

Dioxide National Ambient Air Quality Standard. From: Stephen D. Page To: Regional Air Division 

Directors, Regions 1 – 10.

U.S. EPA Region 5 and States (August 2014). Regional Meteorological Data Processing Protocol

United States District Court for the Northern District of California San Francisco Division (March 

2, 2015). Final Court Order “Consent Decree”

http://www3.epa.gov/airquality/sulfurdioxide/designations/pdfs/201503FinalCourtOrder.pdf

U.S. EPA (August 2015) Data Requirements Rule for the 2010 1-Hour Sulfur Dioxide Primary 

National Ambient Air Quality Standard
61

6.0 Appendices

Appendix A

Emission Inventories for the Study Areas
62

Newton Study Area Emission Inventory

AERMOD Source 

Description 

Receptor Location 

(Meters)

Stack 

Height

Temperature/Exit 

Velocity

Stack 

Diameter

Emissions 

Profile

Source ID East North (m) (K/m/s) (m)

0003 Unit 1 Stack 

(Newton PS) 389291.7 4310518.4 161.54 See Hourly File 5.49 A

0012 Unit 2 Stack 

(Newton PS) 389333.4 4310458.9 161.54 See Hourly File 7.32 A

A: CEMS Data, hourly varying emissions, temperature, exit velocity

In hours with mass emissions, but no temperature/flow rates, the following constants were used (based on Annual 

Emission Report data/Illinois EPA ICEMAN database):

0003: Exit temperature = 325.93 deg. K, Exit velocity = 24.87 m/s

0012: Exit temperature = 431.48 deg. K, Exit velocity = 23.08 m/s
63

Hennepin Study Area Emission Inventory

AERMOD

Source Description 

Receptor Location 

(Meters)

Stack 

Height

Temperature/Exit 

Velocity

Stack 

Diameter

Emissions 

Profile

Source ID East North (m) (K/m/s) (m) (g/s)

0001 Units #1 & 2 

(Hennepin PS) 306166.52 4575006.81 84.43 See Hourly File 4.40 A

0001AA

Drum Mix Asphalt 

Plant

(Advanced Asphalt)

307876.16 4574736.14 10.67 See Hourly File 1.37 B

0002AA

Asphalt Tank 

Heaters/Boilers

(Advanced Asphalt)

307859.69 4574716.20 4.57 See Hourly File 1.13 B

0004HE RTO Stack 

(Marquis Energy) 305795.48 4572111.48 39.62 See Hourly File 1.68 B

0010WM

Silicone Carbide 

Baghouse Furnace 

(Wash Mills)

307362.24 4574653.98 32.92 See Hourly File 2.44 C

0014WM Sulfurox Boiler Stack 

(Wash Mills) 307450.02 4574642.25 5.18 See Hourly File 0.305 D

0018WM

Product Dryer 

Combustion

(Wash Mills)

307305.83 4574293.85 8.23 See Hourly File 0.85 D

0001HE Boiler East Stack 

(Marquis Energy) 305737.18 4572069.79 24.38 449.82/13.71 1.52 E

0016HE Boiler West Stack 

(Marquis Energy) 305727.08 4572070.01 24.38 449.82/13.71 1.52 E

0011HE Loadout Flare 

(Marquis Energy) 305698.09 4572090.90 9.14 668.71/20.53 0.43 E

0017HE Boiler No. 3 Stack 

(Marquis Energy) 305729.23 4572094.94 24.38 470.37/19.14 1.52 E

0005 Heating Boiler Stack 

(Hennepin PS) 306155.92 4574977.64 47.24 644.26/15.69 0.61 5.29E-04

A: CEMS Data, hourly varying emissions, temperature, exit velocity

B: Hourly Profile of Emissions based on seasonal operation/throughput from Annual Emissions Reports

C: Hourly emissions profile based on data provided by company

D: Hourly emissions profile based on yearly/monthly operation and throughput, provided by company

E: Use EMISFACT, seasonal emissions averaged over 2012-2014, multiply by scalar per season

* In hours with mass emissions, but no temperature/flow rates, the following constants were used (based on Annual 

Emission Report data/Illinois EPA ICEMAN database):

0001: Exit temperature = 325.93 deg. K, Exit velocity = 24.87 m/s

0001AA: Exit temperature = 427.64 deg. K, Exit velocity = 20.32 m/s

0002AA: Exit temperature = 455.97 deg. K, Exit velocity = 8.195 m/s

0004HE: Exit temperature = 466.48 deg. K, Exit velocity = 18.60 m/s

0010WM: Exit temperature = 754.32 deg. K, Exit velocity = 16.71 m/s

0014WM: Exit temperature = 355.37 deg. K, Exit velocity = 40.45 m/s

0018WM: Exit temperature = 355.37 deg. K, Exit velocity = 11.87 m/s
64

Marion Study Area Emission Inventory

AERMOD

Source Description 

Receptor Location 

(Meters)

Stack 

Height

Temperature/Exit 

Velocity

Stack 

Diameter

Emissions 

Profile

Source ID East North (m) (K/m/s) (m) (g/s)

0003 Unit No. 4

(Marion PS)

327601.09 4165324.96 121.92 324.82/15.17 4.40 A

90.72

0011 Turbine No. 5 

(Marion PS)

326901.44 4165425.60 17.07 590.37/22.85 1.37 A

7.430976

0012 Turbine No. 6 

(Marion PS)

326839.03 4165425.94 17.07 590.37/22.85 1.13 A

7.430976

0013 CFB Boiler Unit

(Marion PS) 327700.40 4165369.62 59.13 392.04/12.22 1.68 A52.983

0008USP Boiler No. 1

(U.S. Penitentiary) 324736.94 4170242.33 14.33 460.93/6.83 2.44 B0.00128 

0009USP Boiler No. 2

(U.S. Penitentiary) 324734.73 4170239.55 13.41 460.93/33.80 0.305 B0.00128

0010USP Boiler No. 3

(U.S. Penitentiary) 324733.35 4170242.39 14.33 460.93/6.83 0.85 B0.00128

0011USP Boiler No. 3

(U.S. Penitentiary) 324725.90 4170243.57 14.33 460.93/21.45 1.52 B0.00128

A: Maximum actuals

B: Hourly emissions profile based on reported actuals per Annual Emissions Reports, modeling assumed 365-52-24-7 

operation
65

Joppa Study Area Emission Inventory

AERMOD Source 

Description 

Receptor Location 

(Meters)

Stack 

Height

Temperature/Exit 

Velocity

Stack 

Diameter

Emissions 

Profile

Source ID East North (m) (K/m/s) (m) (g/s)

0001 Boiler Units No. 1 

& 2 (Joppa PS) 335066.99 4119612.77 152.4 See Hourly File 5.49 A

0001MP Turbine CT-01

(MEPI)

334437.92 4120723.30 17.07 See Hourly File 4.51 B

0002 Boiler Units No. 3 

& 4 (Joppa PS) 335109.60 4119719.05 152.4 See Hourly File 5.49 A

0002MP Turbine CT-02

(MEPI)

334424.15 4120699.46 16.26 See Hourly File 4.51 B

0003 Boiler Units No. 3 

& 4 (Joppa PS) 335153.93 4119837.40 152.40 See Hourly File 5.49 A

0004MP Turbine CT-04

(MEPI)

334374.85 4120613.27 14.02 See Hourly File 3.35 B

0005MP Turbine CT-05

(MEPI)

334401.35 4120598.14 14.02 See Hourly File 3.35 B

0052LF Kiln No. 2

(Lafarge)

332959.00 4120523.60 76.20 See Hourly File 2.59 B

0062HW

Waste Gas 

Incinerator

(Honeywell)

344072.90 4115307.26 47.24 See Hourly File 2.13 C

0066LF Kiln No. 1

(Lafarge)

332967.00 4120560.10 45.72 See Hourly File 3.66 B

TVA_EAST Boiler 1-5 Stack

(TVA-Shawnee)

342378.96 4113169.92 242.93 See Hourly File 8.50 D

TVA_WEST Boiler 6-50 Stack

(TVA-Shawnee)

342059.04 4113372.78 242.93 See Hourly File 8.50 D

0001TG Engine 5801 

(Trunkline Gas) 334536.69 4121295.99 12.80 677.59/25.87 0.61 E

0002TG Engine 5802 

(Trunkline Gas) 334545.24 4121295.73 12.80 677.59/25.87 0.61 E

0003TG Engine 5803 

(Trunkline Gas) 334554.06 4121295.41 12.80 677.59/25.87 0.61 E

0005TG Engine 5805 

(Trunkline Gas) 334571.88 4121294.89 13.41 660.93/19.60 0.76 E

0006TG Engine 5806 

(Trunkline Gas) 334580.63 41211294.64 13.41 660.93/19.60 0.76 E

0007TG Engine 5807 

(Trunkline Gas) 334560.99 4121462.88 14.94 677.59/13.98 1.98 E

A: CEMS Data, hourly varying emissions, temperature, exit velocity

B: Hourly varying emissions, temperature, exit velocity profile based on data provided by company

C: Hourly Profile of Emissions based on seasonal operation/throughput from Annual Emissions Reports (AER’s)

D: CEMS Data, hourly varying emissions obtained from U.S. EPA Air Market Program Data (CAMD)/SO2 NAAQS 

Modeling Data made available from U. S. EPA specifically for modeling 

E: Use EMISFACT, seasonal emissions averaged over 2012-2014, multiply by scalar per season

* In hours with mass emissions, but no temperature/flow rates, the following constants were used (based on Annual 

Emission Report data/Illinois EPA Database):
66

0052LF and 0066LF: Exit temperature = 325.93 deg. K, Exit velocity = 24.87 m/s - modulated hourly exit velocity for 

each year’s average around the constant based on flow rate changes per CAMD.

TVA_WEST: Exit temperature = 422.09 deg. K, Exit velocity = 29.814 m/s (from KDAQ) – modulated hourly exit 

velocity for each year’s average around the constant based on flow rate changes per CAMD.

TVA_EAST: Exit temperature = 429.87 deg. K, Exit velocity = 29.639 m/s (from KDAQ) – modulated hourly exit 

velocity for each year’s average around the constant based on flow rate changes per CAMD.
67

Wood River Study Area Emission Inventory

AERMOD

Source Description 

Receptor Location 

(Meters)

Stack 

Height

Temperature/

Exit Velocity

Stack 

Diameter

Emissions 

Profile

Source ID East North (m) (K/m/s) (m) (g/s)

0001 Unit 5 Stack (WR 

PS) 748683.76 4305506.89 106.68 See Hourly File 4.57 A

0001PS Boiler 1 Stack 

(Ameren Sioux PS) 735067.23 4310829.84 151.33 See Hourly File*

7.19 B

0002PS Boiler 2 Stack 

(Ameren Sioux PS) 735065.64 4310820.32 151.33 See Hourly File*

7.19 B

0003 Unit 4 Stack 

(WR PS) 748666.89 4305531.27 76.20 See Hourly File 5.18 A

0004WRB CR-1 ULD HCU 

STK12-4 (WRB) 754868.40 4302624.00 106.68 See Hourly File 4.57 C

0018WRB DU-1 Prim Htr South 

STK5-2 (WRB) 454326.10 4303076.20 45.72 See Hourly File 2.59 C

0019WRB DU-1 Secondary Htr 

STK5-1 (WRB) 754325.60 4303099.10 56.39 See Hourly File 2.44 C

0020WRB SMR Htr STK12-8 

(WRB) 754872.30 4302749.40 60.96 See Hourly File 3.66 C

0024WRB RAU Debutanizer 

Htr STK5-5 (WRB) 754469.50 4302942.70 22.86 See Hourly File 1.52 C

0027AS1

EAF Baghouse Vent 

1

(Alton Steel)

747898.46 4307951.71 30.48 See Hourly File 7.38 D

0027AS2

EAF Baghouse Vent 

2

(Alton Steel)

747956.48 4607951.71 30.48 See Hourly File 7.38 D

0027WRB CAU RO Still Heater 

STK5-4 (WRB) 754467.40 4302962.50 25.91 See Hourly File 2.20 C

0043WRB

Catalytic Cracking 

Unit 2

(WRB)

454847.70 4302894.50 53.34 See Hourly File 3.35 C

0050WRB HCF Furnace 

STK12-3 (WRB) 754723.80 4302515.50 54.56 See Hourly File 1.92 C

0052AS1 LMF Baghouse Vent 

1 (Alton Steel) 747874.75 4307823.77 15.24 See Hourly File 1.06 D

0052AS2 LMF Baghouse Vent 

2 (Alton Steel) 747878.53 4307823.77 15.24 See Hourly File 1.06 D

0052AS3 LMF Baghouse Vent 

3 (Alton Steel) 747883.19 4307823.77 15.24 See Hourly File 1.06 D

0052AS4 LMF Baghouse Vent 

4 (Alton Steel) 747886.84 4307823.77 15.24 See Hourly File 1.06 D

0056WRB HCNHT Furnace 

STK12-1 (WRB) 754574.80 4302695.20 32.61 See Hourly File 1.22 C

0060WRB Alky HM-1 Heater 

STK6-5 (WRB) 755121.20 4302814.40 28.96 See Hourly File 2.29 C

0061WRB Alky HM-2 Heater 

STK6-6 (WRB) 754829.00 4303042.40 46.02 See Hourly File 1.75 C

0068WRB Boiler 15 STK12-15 

(WRB) 754858.70 4302776.00 40.23 See Hourly File 2.13 C

0069WRB Blr16 STK12-16 754874.40 4302776.80 40.23 See Hourly File 2.13 C

0070WRB Boiler 17 STK12-17 754901.20 4302783.60 45.72 See Hourly File 3.05 C
68

(WRB)

0071WRB Boiler 18 STK6

-9

(WRB) 754919.20 4302807.80 30.48 See Hourly File 1.89

C

0073WRB

HDU-1 Charge 

Heater STK13-1 

(WRB)

755216.70 4302586.90 45.72 See Hourly File 1.52C

0076WRB

HDU-2 Charge 

Heater STK12-14 

(WRB)

755021.10 4302529.40 45.72 See Hourly File 1.77C

0077WRB

CR-3 Stabilizer Re-

boiler H-2 STK12-9 

(WRB)

755013.20 4302579.70 45.72 See Hourly File 2.38C

0078WRB

CR-3 Regen Heater H-3 STK12-10 

(WRB)

755014.40 4302581.60 45.72 See Hourly File 2.38C

0079WRB

CR-3 Charge Heater H-4 STK12-11 

(WRB)

755018.30 4302570.40 45.72 See Hourly File 2.38C

0080WRB

CR-3 First 

Interreactor Heater H-5 STK12-13 

(WRB)

755018.70 4302546.80 45.72 See Hourly File 2.38C

0081WRB

CR-3 Second 

lnterreactor Heater H-6 STK12-12 

(WRB)

755018.60 4302558.00 45.72 See Hourly File 2.38C

0083WRB DHT Charge Heater 

STK12-5 (WRB) 755017.50 4302643.50 45.72 See Hourly File 1.62

C

0120WRB

F-200 F-202 F-203 F-

204 F-205 STK5-3

(WRB)

754414.80 4303015.80 95.10 See Hourly File 4.27C

0124WRB

VF-1 North/South 

Heater STK6-1

(WRB)

754718.50 4303087.60 56.39 See Hourly File 2.07C

0128WRB SRU North Oxidizer 

STK3-1 (WRB) 752927.80 47303076.40 38.10 See Hourly File 2.20

C

0144WRB SRU South Oxidizer 

STK3-2 (WRB) 752928.10 4303070.40 38.10 See Hourly File 2.20

C

0621WRB Distilling Flare 

FLR1-1 (WRB) 754277.40 4303296.20 55.21 See Hourly File 0.65

C

0623WRB

Arom North Flare 

Aromatic FLR13-1 

(WRB)

755265.80 4302634.50 61.93 See Hourly File 0.32C

0624WRB Arom South Flare 

FLR13-2 (WRB) 755267.00 4302549.20 63.63 See Hourly File 0.78

C

0625WRB North Property Flare 

FLR1-2 (WRB) 754485.40 4303321.20 65.48 See Hourly File 1.64

C

0628WRB Boiler 4 STK9

-1

(WRB) 752782.10 4302397.30 22.86 See Hourly File 1.22

C

0629WRB Boiler 5 STK9

-3

(WRB) 752762.93 4302362.97 22.86 See Hourly File 2.13

C

0633WRB

DCU Charge Heater H-20 STK10-2 

(WRB)

753183.30 4302406.70 54.86 See Hourly File 1.52C
69

AERMOD

Source Description 

Receptor Location 

(Meters)

Stack 

Height

Temperature/

Exit Velocity

Stack 

Diameter

Emissions 

Profile

Source ID East North (m) (K/m/s) (m) (g/s)

0643WRB

Catalytic Cracking 

Unit No. 1 STK6-2B

(WRB)

754863.70 4302894.50 53.34 See Hourly File 3.35 C

0685WRB Alky Flare FLR6-1 

(WRB) 755034.60 4303080.00 66.77 See Hourly File 1.62 C

0702WRB VF-4 Charge Heater 

H-28 STK9-6 (WRB) 753053.00 4302387.20 54.86 See Hourly File 1.37 C

0703WRB DCU Preheater H-36 

STK10-3 (WRB) 753193.20 4302396.10 54.86 See Hourly File 1.83 C

0704WRB DU-4 Charge Heater 

H-24 STK9-5 (WRB) 753050.90 4302412.20 54.86 See Hourly File 2.59 C

0705WRB Heat Medium Furnace 

H-35 STK9-4 (WRB) 752802.50 4302398.30 45.72 See Hourly File 1.83 C

0706WRB HP-1 Flare FLR12-2 

(WRB) 755193.80 4302792.10 43.09 See Hourly File 0.94 C

0709WRB HP-1 Heater STK12-6 

(WRB) 755193.00 4302792.10 38.71 See Hourly File 2.29 C

0711WRB ULD H-4 Re-boiler 

STK12-2 (WRB) 755038.00 4302710.50 39.78 See Hourly File 1.80 C

0712WRB SZorb Heater STK13-

3 (WRB) 755218.20 4302666.40 45.72 See Hourly File 2.90 C

0715WRB Distilling West Flare 

FLR10-1 (WRB) 753646.00 4302545.40 61.55 See Hourly File 0.38 C

0716WRB SZU Stack (0716)

(WRB) 755240.90 4302682.20 13.49 See Hourly File 0.61 C

0717WRB

Benzene Extraction 

Unit Heater H-3 

STK6-4 (WRB)

754922.50 4302928.90 56.39 See Hourly File 2.96 C

0718WRB Lubes Flare FLR12-1 

(WRB) 754609.60 4302495.50 48.79 See Hourly File 0.40 C

0724WRB VOC Flare (West) 

FLR4-1 (WRB) 753427.00 4303072.60 10.82 See Hourly File 0.43 C

0725WRB VOC Flare (East) 

FLR4-2 (WRB) 753440.50 4303073.00 10.82 See Hourly File 0.43 C

0726WRB Coker North Flare 

FLR1-3 (WRB) 754946.10 4303683.30 60.96 See Hourly File 0.39 C

0727WRB

VF-5 Heater/H350H4 

STK1-1 (WRB 

Refining)

754936.80 4303458.30 60.96 See Hourly File 3.05 C

0728WRB

Coker North 

Heater/H351H2 

STK1-2 (WRB)

754952.70 4303304.10 64.01 See Hourly File 3.05 C

0729WRB

Coker North 

Heater/H351H1 

STK1-3 (WRB)

754985.20 4303304.90 64.01 See Hourly File 3.05 C

0730WRB

DCNH 

Heater/H353H3 

STK1-4 (WRB)

754903.70 4303543.30 24.38 See Hourly File 0.64 C

0731WRB SRUF Oxdizr STK3-3 752913.10 4303020.00 60.66 See Hourly File 1.22 C
70

0732WRB SRU-E Oxidizer 

STK3-4 (WRB) 753001.50 4303022.90 60.66 See Hourly File 1.22 C

0735WRB HP-2 Flare FLR7-1 

(WRB) 755262.00 4302919.70 43.09 See Hourly File 0.94 C

0736WRB HP-2 Heater STK7-1

(WRB) 755262.90 4302919.70 39.62 See Hourly File 3.84 C

0739WRB

NHT Charge Heater 

H-21 STK10-1 

(WRB)

753160.30 4302411.90 30.48 See Hourly File 1.37 C

0900WRB CR-1 Regen Vent 

STK12-18 (WRB) 754883.68 4302607.56 17.68 See Hourly File 0.15 C

0901WRB CR-3 Regen Vent 

STK 12-19 (WRB) 755029.45 4302593.48 9.14 See Hourly File 0.09 C

0902WRB Misc Unit (WRB) 754669.60 4303047.00 19.81 See Hourly File 1.22 C

0903WRB STK6_2 754647.80 4303005.50 19.81 See Hourly File 1.13 C

FLR_MVC Barge Loading Flare 

(WRB Refining) 751375.17 4302867.10 12.19 See Hourly File 1.22 C

0031AS

14 inch rolling mill 

reheat furnace (Alton 

Steel)

747645.22 4307691.38 32.31 366.48/0.73 4.88 E

0.0076

0099AS Caster (Alton Steel) 747849.10 4307673.65 19.81 294.26/0.001 9.00 E

8.0E-04

0001CB Drum Mix Asphalt 

Stack (CBP)

755684.51 4299821.86 9.75 394.82/16.34 1.25 F

0003CB Asphalt Tank Heaters 

and Boilers (CBP) 755700.20 4299839.80 9.45 486.48/11.05 1.04 F

0002NM Cleaver Brooks boiler 

Stack 1 of 2 (NM) 750915.14 4300903.33 10.36 505.37/7.12 0.61 F

0004NM Cleaver Brooks boiler 

Stack 2 of 2 (NM) 750918.74 4300902.96 10.36 505.37/7.12 0.61 F

A: CEMS Data, hourly varying emissions, temperature, exit velocity provided by company.

B: CEMS Data for emissions, constant temperature, varying exit velocity based on Emissions modeling Clearinghouse 

State-Level Hourly Sulfur Dioxide Data- flow modulation around a constant. 

http://www.epa.gov/ttn/chief/emch/index.html

C: Hourly varying emissions, temperature, exit velocity based on data provided by company

D: Uniformly distributed hourly emissions based on company provided daily operating schedule per year, used constant 

for temperature/exit velocity profile based on Illinois EPA Database/AER data provided by company

E: Distribute worst-case actual Annual Emissions year, to all 3years, applied uniformly for each hour

F: Use worst-case Annual Emissions year 2012-2014 for all 3 years, apply EMISFACT seasonally, and multiply by scalar 

per season.

* In hours with mass emissions, but no temperature/flow rates, the following constants were used (based on Annual 

Emission Report data/Illinois EPA ICEMAN database):

0001: Exit temperature = 416.48 deg. K, Exit velocity = 19.798 m/s

0003: Exit temperature = 394.26 deg. K, Exit velocity = 8.511 m/s

0001PS: Exit temperature = 330.37 deg. K, Exit velocity = 16.62 m/s – modulated hourly exit velocity for each year’s 

average around the constant based on flow rate changes per U.S EPA SO2 NAAQS CAMD derived inventory.

0003PS: Exit temperature = 330.37 deg. K, Exit velocity = 16.62 m/s – modulated hourly exit velocity for each year’s 

average around the constant based on flow rate changes per U.S EPA SO2 NAAQS CAMD derived inventory.
71

Appendix B

Background SO2 Data for Modeling
72

Nilwood*, Illinois Monitor

Season* and Hourly Varying Background SO2

Newton Study Area

Hour of Day

SO2 Concentration (μg/m3)

Winter Spring Summer Fall

1 7.77 4.01 3.84 4.62

2 7.50 4.19 5.32 4.80

3 8.55 4.25 3.93 5.67

4 7.68 5.06 5.58 4.80

5 7.59 4.10 4.80 5.67

6 7.50 4.45 6.02 5.50

7 7.24 4.89 7.33 5.58

8 7.15 8.11 8.64 5.76

9 8.81 10.91 10.03 8.73

10 12.13 11.60 12.04 9.51

11 15.36 13.44 11.43 13.79

12 13.00 12.30 10.91 15.53

13 13.96 10.47 8.29 15.01

14 13.61 8.73 8.64 12.56

15 11.95 7.59 8.38 10.38

16 11.60 9.07 6.19 9.95

17 11.52 7.42 7.68 9.07

18 10.30 6.46 6.72 8.38

19 7.50 6.46 4.89 6.63

20 9.86 3.84 4.89 5.41

21 9.07 4.62 5.06 5.50

22 6.63 4.10 4.01 5.76

23 7.24 3.58 3.32 5.41

24 7.59 3.66 4.97 5.15

* Monitor Latitude/Longitude Coordinates: (+39.396075 –89.80974)

** Seasons defined as: Winter (Dec, Jan, Feb), Spring (Mar, Apr, May), Summer (Jun, Jul, Aug), Fall (Sep, Oct, Nov)
73

Oglesby*, Illinois Monitor

Season** and Hourly Varying Background SO2

Hennepin Study Area

Hour of Day

SO2 Concentration (μg/m3)

Winter Spring Summer Fall

1 5.85 7.07 4.54 4.62

2 6.11 7.33 5.06 4.62

3 4.45 6.02 3.49 3.66

4 5.15 6.19 2.70 4.36

5 6.19 4.97 2.09 6.46

6 6.28 6.89 2.44 6.89

7 5.58 6.54 4.80 5.06

8 6.63 9.42 7.59 4.36

9 8.55 11.17 9.34 5.58

10 10.64 11.60 9.16 6.98

11 10.47 12.39 10.64 10.56

12 12.83 12.30 8.20 9.25

13 14.31 9.16 7.59 9.16

14 14.92 9.51 6.72 9.42

15 11.52 8.90 7.33 7.85

16 10.38 6.54 6.72 8.03

17 11.08 7.15 7.68 7.94

18 8.81 7.24 6.89 7.07

19 8.64 8.64 7.15 5.67

20 6.98 8.20 4.80 7.33

21 7.94 9.16 4.80 5.50

22 6.37 9.34 5.67 5.58

23 6.02 7.94 4.71 4.54

24 5.76 6.72 4.62 4.80

* Monitor Latitude/Longitude Coordinates: (+41.29301 -89.04942)

** Seasons defined as: Winter (Dec, Jan, Feb), Spring (Mar, Apr, May), Summer (Jun, Jul, Aug), Fall (Sep, Oct, Nov)
74

Houston*, Illinois Monitor

Season** and Hourly Varying Background SO2

Marion Study Area

Hour of Day

SO2 Concentration (μg/m3)

Winter Spring Summer Fall

1 5.76 6.46 4.71 5.41

2 6.46 7.42 5.76 6.37

3 7.50 7.38 4.71 6.63

4 10.12 7.33 4.45 5.93

5 9.86 6.98 4.62 6.81

6 12.65 8.03 4.80 7.77

7 10.73 8.73 7.24 7.68

8 13.00 11.26 9.51 10.82

9 13.96 14.13 17.01 10.03

10 14.48 19.81 20.94 19.54

11 19.28 18.41 27.05 17.28

12 19.37 22.51 32.81 21.03

13 18.58 15.44 26.87 19.72

14 24.61 13.61 16.49 20.94

15 26.87 11.43 17.01 13.18

16 18.06 15.79 16.23 16.23

17 16.14 15.36 14.83 12.91

18 15.09 12.83 8.99 10.30

19 12.48 8.46 8.38 9.34

20 10.38 9.07 5.41 8.81

21 7.68 6.63 3.75 9.07

22 9.69 6.19 5.32 8.38

23 11.17 7.24 3.58 5.06

24 7.50 7.24 3.93 4.89

* Monitor Latitude/Longitude Coordinates: (+38.17628 -89.78846)

** Seasons defined as: Winter (Dec, Jan, Feb), Spring (Mar, Apr, May), Summer (Jun, Jul, Aug), Fall (Sep, Oct, Nov)
75

Paducah*, Kentucky Monitor

Season** and Hourly Varying Background SO2

Joppa Study Area

Hour of Day

SO2 Concentration (μg/m3)

Winter Spring Summer Fall

1 11.34 7.85 6.11 5.24

2 13.09 10.47 3.49 4.36

3 12.22 5.24 3.49 6.11

4 15.71 7.85 2.62 4.36

5 13.08 7.85 3.49 5.24

6 10.47 5.24 5.24 5.24

7 8.73 5.24 6.98 6.98

8 10.47 9.60 10.47 11.34

9 11.34 10.47 17.45 12.22

10 17.45 13.09 16.58 17.45

11 18.32 31.41 14.83 25.30

12 19.20 24.43 28.79 21.81

13 27.05 27.92 29.67 28.79

14 32.28 17.45 21.81 24.43

15 20.94 13.09 24.43 34.03

16 21.81 16.58 20.94 27.92

17 25.30 17.45 23.56 20.94

18 27.92 12.22 19.20 16.58

19 13.96 9.60 18.32 8.73

20 13.96 5.24 13.09 6.11

21 9.60 2.62 6.98 6.11

22 10.47 3.49 5.24 6.98

23 10.47 5.24 4.36 6.11

24 9.60 6.11 5.24 5.24

* Monitor Latitude/Longitude Coordinates: (+37.05822 -88.57251)

** Seasons defined as: Winter (Dec, Jan, Feb), Spring (Mar, Apr, May), Summer (Jun, Jul, Aug), Fall (Sep, Oct, Nov)
76

East St. Louis*, Illinois Monitor

Season** and Hourly Varying Background SO2

Wood River Study Area

Hour of Day

SO2 Concentration (μg/m3)

Winter Spring Summer Fall

1 22.60 16.14 13.70 10.73

2 19.11 13.00 14.48 10.12

3 12.39 14.83 13.61 14.57

4 13.44 17.54 19.28 10.38

5 10.56 24.17 18.41 11.69

6 16.05 15.88 13.79 9.51

7 18.15 19.81 15.27 10.91

8 26.26 18.24 27.48 24.34

9 18.41 23.03 34.81 22.69

10 23.91 18.50 31.50 39.09

11 29.67 27.48 26.61 28.27

12 23.65 19.63 19.37 23.47

13 31.76 16.40 26.26 18.85

14 25.74 17.10 19.89 23.38

15 21.20 15.18 12.65 18.35

16 21.55 12.39 13.370 15.71

17 18.50 18.50 11.60 19.20

18 20.77 15.53 12.74 24.87

19 14.83 13.26 10.30 15.09

20 10.12 13.61 9.07 9.60

21 8.90 11.95 12.39 6.81

22 11.69 9.86 10.12 10.03

23 13.70 10.30 11.26 9.07

24 28.36 13.79 9.51 10.82

* Monitor Latitude/Longitude Coordinates: (+38.61203 -90.16048)

** Seasons defined as: Winter (Dec, Jan, Feb), Spring (Mar, Apr, May), Summer (Jun, Jul, Aug), Fall (Sep, Oct, Nov)
77

Appendix C

Model Input/Output Files for the Study Areas

DVD Media