                                       
                                       
                          Technical Support Document
                                       
           For the Proposed Approval of the Nonattainment Plan for 
                   the Alton, Illinois SO2 Nonattainment Area
                                       
Summary

The Environmental Protection Agency (EPA) is proposing to approve the State Implementation Plan (SIP) for attaining the 1-hour sulfur dioxide (SO2) primary national ambient air quality standard (NAAQS) for the Alton, Illinois SO2 nonattainment area.  The SIP includes an attainment demonstration and other elements required under the Clean Air Act (CAA).  Based on the modeling analysis described in this technical support document, EPA is proposing to determine that the SIP provides for attainment of the 2010 1-hour primary SO2 NAAQS in the Alton, Illinois SO2 nonattainment area.

Background

On June 22, 2010, EPA published a new 1-hour primary SO2 NAAQS of 75 parts per billion (ppb), which is met at an ambient air quality monitoring site when the 3-year average of the annual 99th percentile of daily maximum 1-hour average concentrations does not exceed 75 ppb, as determined in accordance with Appendix T of 40 CFR part 50.  See 75 FR 35520, codified at 40 CFR 50.17(a)-(b).  On June 30, 2016, EPA released "Round 2" of its SO2 designations, designating four areas of the country as nonattainment for the 2010 SO2 NAAQS, including the Alton area within the State of Illinois.  See 81 FR 45039, codified at 40 CFR part 81.  Section 191 of the CAA directs states to submit SIPs for areas designated as nonattainment for the SO2 NAAQS to EPA within 18 months of the effective date of the designation.  These SIPs are required by CAA section 192 to demonstrate that their respective areas will attain the NAAQS as expeditiously as practicable, but no later than 5 years from the effective date of designation. 

Illinois submitted to EPA on December 31, 2018, a SIP for attaining the 1-hour SO2 primary NAAQS for the Alton Township nonattainment area in Madison County.  This plan includes Illinois' attainment demonstration and other elements required under the CAA.  In addition to an attainment demonstration, the plan addresses other provisions including the requirement for meeting reasonable further progress (RFP) toward attainment of the NAAQS, reasonably available control measures and reasonably available control technology (RACM/RACT), base-year and projection-year emissions inventories, enforceable emission limitations and control measures, nonattainment new source review (NNSR), and contingency measures.  EPA is proposing to approve Illinois' submission as a SIP revision for attaining the 2010 1-hour primary SO2 NAAQS in the Alton township nonattainment area, finding that Illinois has adequately demonstrated that the plan provisions provide for attainment of NAAQS in the nonattainment area and that the plan meets the other applicable requirements under the CAA.

Introduction

To support the SIP for bringing the Alton area into attainment of the 2010 SO2 NAAQS, EPA conducted a modeling demonstration of the Alton area that contains an assessment of the air quality impacts that would be allowable under enforceable emission limits or their allowable potential to emit for Ameren-Sioux Power Center in Missouri and the LMF stack at Alton Steel, and the maximum uncontrolled emissions from other units at Alton Steel and at GBC Metals, Olin Corporation, National Maintenance & Repair, Alton Water treatment Facility, Conco-Philips Hartford Plant, Alton Memorial Hospital, St. Anthony's Hospital, St. Claire's Hospital, the Charles E. Mahoney Plant, and WRB Refinery.

The analysis was conducted in accordance with EPA's modeling requirements to support attainment demonstrations, which are specified by regulation in Appendix W of 40 CFR Part 51 (Guideline on Air Quality Models), as referenced by 40 CFR 51.112.  The remainder of this technical support document describes the model and modeling parameters used in the analysis, as well as EPA's modeling results and conclusions.

Analysis

Basis of Modeling Analysis

The modeling analysis conducted by EPA to support the Illinois Alton SO2 SIP was adapted from the modeling analysis conducted by the state to support its 2018 Nonattainment SIP submittal. EPA's supplemental modeling was done to correct deficiencies found in Illinois's modeling which predominantly was done by updating the emissions data relied upon in the model and correcting the source characterization. Illinois did not consider the updated limit at the Sioux facility which was necessary to model attainment in the area. EPA updated the emissions data at Sioux in the supplemental model as well as corrected any other deficiencies in the emissions data such as modeling all sources at GEP height which otherwise could unduly cause reduced concentrations. EPA used Illinois' receptor grid, meteorological surface and upper air stations, model settings, and some source parameters to develop the modeling demonstration.  However, the following components of the Illinois modeling analysis were modified in EPA's analysis: 
 The AERMOD version was updated from version 18081 to version 21112.
 Stack parameters were updated to current operating conditions.
 Emission rates were adjusted for the Ameren-Sioux facility to account for longer-term average limits.

Model Selection and Modeling Components

Appendix W notes that AERMOD is EPA's preferred near-field dispersion modeling system.  The AERMOD modeling system contains the following components:
 AERMOD: the dispersion model
 AERMAP: the terrain processor for AERMOD
 AERMET: the meteorological data processor for AERMOD
 BPIPPRIME: the building input processor 
 AERMINUTE: a pre-processor to AERMET incorporating 1-minute automated surface observation system (ASOS) wind data 
 AERSURFACE: the surface characteristics processor for AERMET
 AERSCREEN: a screening version of AERMOD

EPA used AERMOD version 21112, the most recent version of AERMOD, in the modeling analysis.  A discussion of the individual components will be referenced in the corresponding discussion that follows, as appropriate.  

Modeling Parameter: Rural or Urban Dispersion
EPA's recommended procedure for characterizing an area by prevalent land use is based on evaluating the dispersion environment within 3 kilometers of the facility.  Illinois centered its land use analysis around the Alton Steel facility because it is the source of SO2 emissions in the nonattainment area that was primarily responsible for causing a NAAQS violation. According to Appendix W, rural dispersion coefficients are to be used in the dispersion modeling analysis if more than 50% of the area within a 3-kilometer radius of the facility is classified as rural. Conversely, if more than 50% of the area is urban, urban dispersion coefficients should be used in the modeling analysis. 
 
The recommended methodology for making the rural/urban determination for a study area is outlined in Section 7.2.3 (c, d, e) of 40 CFR Part 51 Appendix W, as well as in the AERMOD Implementation Guide (p. 19-21). Illinois chose to perform an Auer land use analysis to determine the suitability for rural or urban classification for the Alton area. The Auer analysis was conducted using the 2011 National Land Cover Data (NLCD) database. Illinois used GIS software to analyze the percentages of urban and rural land cover per Auer's classification scheme. The Auer analysis determined that the area immediately surrounding the Alton Steel facility was 73% rural and thus best classified as a rural dispersion area. Illinois did not conduct a population density analysis for this area. 

EPA concurs with Illinois's determination that the area is best characterized as a rural dispersion area and applied the rural option in AERMOD for all emission sources in the modeling domain.

Modeling Parameter: Area of Analysis (Receptor Grid)

EPA believes that a reasonable first step towards characterization of air quality in the Alton area is to determine the extent of the area of analysis, i.e., receptor grid.  Considerations presented in Appendix W include but are not limited to the location of the SO2 emission sources or facilities considered for modeling, the extent of significant concentration gradients of nearby sources, and sufficient receptor coverage and density to adequately capture and resolve the model predicted maximum SO2 concentrations.  

For the Alton area modeling analysis, a uniform Cartesian receptor grid was used with receptor spacing of 100 meters throughout the modeled domain.  The receptor network contained 607 receptors and covers an approximately 3.4 kilometers by 1.7 kilometers area over the entire Alton nonattainment area.  The nonattainment area and receptor grid are bounded by East Broadway to the north, Cpl. Chris Belchik Memorial Expressway to the west, the Wood River to the east, and the Wood River Township boundary to the south.  A fence line receptor grid with 50-meter spacing was included around the perimeter of the Alton Steel facility.  Figure 1 shows the area of analysis as well as the receptor grid.  Consistent with Appendix W, receptors for the purposes of this modeling analysis were placed only in areas that are considered ambient air.  Receptors were excluded over Alton Steel which is considered non-ambient air relative to its own emissions.  Furthermore, while the area inside the fenceline of the Alton Steel facility is considered ambient air relative to emissions from Sioux, the modeling indicates that impacts within Alton Steel's fenceline from Sioux emissions would not result in NAAQS violations given the increasing distance away from the Sioux facility. The impacts of the area's geography and topography, as well as the model results, are discussed below.

 
Figure 1: Receptor Grid for the Alton, IL Area of Analysis.


Figure 2: Model domain boundary and Cartesian receptor grid for the Alton, IL modeling analysis.  

Modeling Parameter: Source Characterization

EPA characterized the sources within the area of analysis in accordance with practices outlined as acceptable in Appendix W.  Specifically, EPA used adjusted stack heights to comply with GEP stack heights,  limits proposed in the SIP, limits already incorporated in Missouri's SIP, or maximum uncontrolled emissions when modeling the area of analysis.  All modeled stacks met GEP height requirements.  EPA also characterized the sources' building layouts and locations, as well as the stack parameters, e.g., exit temperature, exit velocity, location, and diameter.  Modeling parameters used in the modeling analysis are summarized in Table 4 and in Table A-1 within Appendix A at the end of this document.  

In EPA's supplemental modeling run, Sioux's emissions from Boilers 1 and 2 were treated as merged for a combined emission rate.  EPA's stack height regulations restrict the circumstances under which plume merging is creditable. Under 40 CFR 51.100(hh), plume merging is defined to be a prohibited dispersion technique except, in the case of merging occurring after July 8, 1985, for cases in which such merging is part of a change in operation at the facility that includes the installation of pollution controls and is accompanied by a net reduction in the allowable emissions of a pollutant. (See 40 CFR 51.100(hh)(2)(B)).  The stack height regulations also note that this exclusion from the definition of dispersion techniques shall apply only to the emission limitation for the pollutant affected by such change in operation.  To reduce its SO2 emissions, Sioux began operation of flue gas desulfurization of the emissions from Boilers 1 and 2 on November 15, 2010, and October 26, 2010, respectively.  The construction of the new stack to vent the emissions from these units was part of the same project as installation of flue gas desulfurization equipment.  Although Missouri did not adjust Sioux's SIP emission limit to reflect the reduction of allowable emissions until several years after the installation of the pollution controls, the merging accompanied the installation of controls and may also be considered to accompany a net reduction in allowable emissions because the initial request for credit for merging was accompanied by a limit that required the net emission reduction that the Sioux control project achieved. 

Figure 3: The current stack configuration at the Ameren-Sioux Power Center. 

Modeling Parameter: Emissions 

EPA included all stationary sources potentially presenting a significant concentration gradient within a 10 kilometer radius of the Alton Steel facility in its modeling analysis, as well as the Sioux facility which is 13 kilometers away.  The facilities modeled were the Ameren Missouri-Sioux Energy Center in Missouri, Alton Steel, GBC Metals, Wieland Group (formerly known as Olin Corporation), National Maintenance & Repair, Alton Water treatment Facility, Conoco-Philips Hartford Plant, Alton Memorial Hospital, St. Anthony's Hospital, St. Claire's Hospital, the Charles E. Mahoney Plant, and WRB Refinery. The Wood River power plant was not included in the modeling analysis because all units with SO2 emissions have been permanently and enforceably shut down.  EPA believes that the area of analysis adequately represents the area where maximum concentrations of SO2 are expected and adequately includes the sources which might contribute to those concentrations.  No other sources were determined by EPA to have the potential to cause significant concentration gradient impacts within the area of analysis.  

EPA modeled all sources using limits proposed in the SIP, limits already incorporated into Illinois' and Missouri's SIPs, or the maximum uncontrolled emission rates for sources for which limits are not proposed for the SIP.  

As explained in the SIP, the SIP includes a new limit for Alton Steel based on the construction of a new stack to replace the previous method of dispersion at the facility. The facilities in EPA's area of analysis and their associated emission rates are summarized in Table 2, and the limits and/or modeled emission rates are discussed in more detail below.  


Table 2: SO2 Emissions Based on Allowable and Proposed Emissions in the Area of Analysis
                                     Unit
                     Modeled SO2 Emissions Rate (lbs/hr)*
                    Emission Rate Enforceability Mechanism
                                  Alton Steel
LMF Stack

11.20
Limits are included in the SIP regulatory text, as 1-hour limits.
EAF Baghouse #1
35.30
Maximum uncontrolled emissions. 
EAF Baghouse #2
35.30

14-inch Rolling Mill
Reheat Furnace
0.20

Caster
0.10

                           Ameren-Sioux Power Center
Boiler 1, Boiler 2 (combined)
10,301.669 *
24-hour block average SIP limit
                        National Maintenance and Repair
Cleaver Brooks Boiler
Stack 1
10.00
Maximum uncontrolled emissions. 
Cleaver Brooks Boiler
Stack 2
10.00

                                  GBC Metals
Ascast Furnaces
(ASC1 & ASC2) +
DC Casting Units #1/4
0.20
Maximum uncontrolled emissions.
DC Casting Unit #2
0.10

DC Casting Unit #5
0.10

DC Casting Unit #3
0.10

Induction Form
Stations & Mix Muller
+ Low Profile turbine
0.003

Slab Heating Furnace
SF-1
0.19

Slab Heating Furnace
SF-2
0.019

Slab Heating Furnace
SF-3
0.019

Strip Anneal #4 (SA-
4)
0.028

Strip Anneal #5 (SA-
5)
0.0071

Strip Anneal #6 (SA-
6)
0.0071

Strip Anneal #3 (SA-
3)
0.0056

Strip Anneal #7 (SA-
7)
0.0048

                               Olin Corporation
Package Boiler
(B-4)
0.39
Maximum uncontrolled emissions.
Package Boiler
(B-3)
0.39

Package Boiler
(B-2)
0.39

Package Boiler
(B-1)
0.39

Package Boiler
(B-5)
0.39

Package Boiler
(B-6)
0.39

Rotary Retort
3.36

                        Alton Water Treatment Facility
2000 KW Emergency
Generator
0.0027
Maximum uncontrolled emissions.
                    Conoco Philips Hartford Lubricant Plant
Main Boiler Stack
0.019
Maximum uncontrolled emissions.
                            Alton Memorial Hospital
3 Boilers
0.061
Maximum uncontrolled emissions.
                            St. Anthony's Hospital
Boilers 1, 2, 3, and 4
Stack
0.038
Maximum uncontrolled emissions.
                             St. Clare's Hospital
D-B Boiler #7428
(Stack 0002)
0.022
Maximum uncontrolled emissions.
D-B Boiler #7429
(Stack 0003)
0.022

D-B Boiler #7430
(Stack 0004)
0.022

                              Charles E. Mahoney
Drum Asphalt Mixer
Stack
17.90
Maximum uncontrolled emissions.
Drum Dryer Asphalt
Plant Stack
17.90

Asphalt Heaters and
Boilers Stack
2.80

                                      WRB
CR-1 ULD HCU
STK12-4
58.62
Maximum uncontrolled emissions.  
DU-1 Primary Heater
South F-301 STK5-2
7.49

DU-1 Secondary
Heater North F-302
STK5-1
13.56

SMR Heater STK12-8
28.48

RAU Debutanizer
Heater STK5-5
4.24

CAU RO Still Heater
STK5-4
5.88

Catalytic Cracking
Unit No. 2 (Wet Gas
Scrubber) STK6-3B
78.23

HCF Furnace STK12-
3
5.52

HCNHT Furnace
STK12-1
0.024

Alky HM-1 Heater
STK6-5
2.32

Alky HM-2 Heater
STK6-6
6.13

Boiler 15 STK12-15
22.29

Boiler 17 STK12-17
43.34

Boiler 18 STK6-9
15.42

HDU-1 Charge Heater
STK13-1
4.167

HDU-2 Charge Heater
STK12-14
5.01

CR-3 Stabilizer
Reboiler H-2 STK12-
9
1.95

CR-3 Regen Heater
H-3 STK12-10
1.57

CR-3 Charge Heater
H-4 STK12-11
11.14

CR-3 First
Interreactor Heater H-
5 STK12-13
9.60

CR-3 Second
Interreactor Heater H-
6 STK12-12
5.26

DHT Charge Heater
STK12-5
6.69

F-200 F-202 F-203 F-
204 F-205 STK5-3
45.51

SRU North Oxidizer
STK3-1
22.90

SRU South Oxidizer
STK3-2
22.90

Distilling Flare FLR1-
1
0.63

Aromatic North Flare
FLR13-1
1.67

Aromatic South Flare
FLR13-2
0.96

North Property Flare
FLR1-2
19.39

Boiler 4 STK9-1
11.29

Boiler 5 STK9-3
9.00

DCU Charge Heater
H-20 STK10-2
12.04

Catalytic Cracking
Unit No. 1 (Wet Gas
Scrubber) STK6-2B
78.23

Alky Flare FLR6-1
2.02

VF-4 Charge Heater
H-28 STK9-6
1.71

DCU Preheater H-36
STK10-3
1.64

DU-4 Charge Heater
      H-24 STK9-5
8.16

HP-1 Flare FLR12-2
0.0079

HP-1 Heater STK12-6
0.34

ULD H-4 Reboiler
STK12-2
4.64

SZorb Heater STK13-
3
4.64

Distilling West Flare
FLR10-1
0.15

SZU Stack (0716)
4.20

Benzene Extraction
Unit Heater H-3
STK6-4
15.48

Lubes Flare FLR12-1
0.48

VOC Flare (West)
FLR4-1 
0.81

VOC Flare (East)
FLR4-2
0.81

Coker North Flare
FLR1-3
0.18

VF-5 Heater/H350H4
STK1-1 
24.76

Coker North
Heater/H351H2
STK1-2
20.43

Coker North
Heater/H351H1
STK1-3
20.43

DCNH
Heater/H353H3
STK1-4
1.24

SRU-F Oxidizer
STK3-3
50.09

SRU-E Oxidizer
STK3-4 
50.09

ULD-2 H-1 Process
Heater STK6-7
1.98

ULD-2 H-2 Process 
Heater STK6-8
3.41

HP-2 Flare FLR7-1
0.15

HP-2 Heater STK7-1
78.94

NHT Charge Heater
H-21 STK10-1
1.03

CR-1 Regen Vent
STK12-18
9.33

CR-3 Regen Vent
STK 12-19
9.25

Barge Loading Flare
0.0079

* For any units with longer-term average limits, Table 2 shows the 1-hour emission rate for modeling purposes that was used in EPA's modeling analysis.

An important aspect of an attainment plan is that the emission limits that provide for attainment be quantifiable, fully enforceable, replicable, and accountable.  See General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990, 57 Fed. Reg. 13498, 13567-78 (April 16, 1992).  The SIP analysis relies on limits for Ameren-Sioux which are expressed as 24-hour block limits.  Therefore, part of the Alton SIP must address the use of these longer-term average limits, both with respect to the general suitability of using such limits for demonstrating attainment and with respect to whether the particular limits included in the plan have been suitably demonstrated to provide for attainment.  The first subsection that follows addresses the enforceability of the limits in the plan, and the second subsection that follows addresses in particular the 24-hour block average limits.

      1.  Enforceability
The change to Alton Steel's LMF exhaust configuration from the four downward-angled vents to a single 70-foot high, three-foot diameter stack with an unobstructed (no rain cap), vertically directed exhaust was mandated in Illinois Construction Permit #18020009, which is being incorporated into Illinois' SIP in the present action. This permitting action provides the federal enforceability supporting this portion of the attainment demonstration element of the revised SIP.  As required by the construction permit, the SO2 emissions of this furnace shall not exceed 0.10 pound/ton of steel produced, 11.20 pounds/hour and 37.50 tons/year.  EPA considers these emission limits and source configuration requirements, specified in Construction Permit Number #18020009, to be suitably enforceable. The facility must submit annual compliance certifications to ensure that the facility is meetings its SIP limits.  Additionally, the facility must submit a semi-annual Monitoring Report to the Illinois EPA, Air Compliance Section, summarizing required monitoring done and identifying all instances of deviation from the permit.  Stack testing must be done to verify the margin of compliance with the SO2 limit. 

For Sioux, EPA has approved a more stringent facility wide 24-hour block limit submitted by Missouri that is aimed at reducing the facility's allowable emissions to levels that will allow the Alton nonattainment area to be modeled in attainment.  Sioux will be subject to the more restrictive limit of 7,342 lbs of SO2/hour averaged over a 24-hour block period.  Being a large coal fired EGU, the Sioux facility is required to monitor its release of SO2 via CEMS for other reasons such as the acid rain program and the Cross-State Air Pollution Rule (CSAPR).  This requirement also provides for a means to measure compliance at the source to ensure that the facility does not exceed its permanent and enforceable limit.  To demonstrate compliance, Ameren must calculate the calendar day 24-hour block average emission for each unit subject to the facility wide emission limit.  Unit level emission rates will then be summed together to determine a facility wide emission rate.  Only valid operating hours will be included in the calculations for the daily emission rates.  Valid operating hours include only hours that meet the primary equipment hourly operating requirements of 40 CFR 75.10(d). For example, if the source only meets 40 CFR 75.10(d) operational requirements for one hour in a particular 24-hour block period, the compliance with the emissions limit would be calculated by the total emissions divided by the one hour of operation that meets 40 CFR 75.10(d). Therefore, any day with at least one hour that meets operational requirements will have a calculated block average that will be used to demonstrate compliance with the emissions limit. Hours when the units are experiencing startup, shutdown, or malfunction conditions will be used for the calculation if they meet the primary equipment hourly operating requirements of 40 CFR 75.10(d). 

      2.  Longer-Term Average Limits  
      
As noted above, while Illinois considered only the 1-hour average limits it adopted for Alton Steel, EPA also considered the updated 24-hour block limit approved into the Missouri SIP for the Sioux facility.  Therefore, the hypothetical critical emissions value to which Sioux's 24-hour block average limit would be comparably stringent, and that is used in the attainment modeling for the area, would reflect an upward adjustment from the 7,342 lbs/hour averaged over a 24-hour block period..  EPA conducted a site-specific analysis of variability at Ameren-Sioux using 2016-2020 CEMS data from EPA's Clean Air Markets Division's MySQL database, which was the most up to date information available at the time of analysis.  EPA employed the method detailed in our 2014 guidance and used the historic 1-hour 99th percentile of SO2 emissions against the 99th percentile 24-hour block average to derive an appropriate adjustment factor.  EPA determined that the adjustment factor for the Sioux facility is 0.7127 and that it would be appropriate to apply this adjustment factor to Sioux's long term averaging limit in order to estimate an appropriate 1-hour emission rate to be used in the modeling.  After applying the adjustment factor, EPA determined that a reasonable emission rate used in the modeling would be 10,301.669 lbs/hour.  EPA has determined that an emission rate limit of 10,301.669 lbs/hour is protective of the standard.  As such, EPA determines that Sioux's updated limit of 7,342 lbs/hour will provide for attainment in the nonattainment area. The Sioux 24-hour block limit and adjusted 1-hour emission rates are shown below in Table 3.

Table 3: Ameren-Sioux 24-hour block limit and Comparably Stringent 1-Hour Emission Rates
                                   Units(s)
                         24-Hour Block Emission Limit
                               Adjustment Factor
              Modeled Comparably Stringent 1-Hour Emission Rate 
                          Ameren-Sioux Energy Center
                         Boiler 1, Boiler 2 (combined)
                                 7,342 lbs/hr
                        0.7127 on a facility wide basis
                               10,301.669 lbs/hr

EPA believes that the 24-hour block average limit for Sioux is a suitable alternative to establishing a 1-hour average emission limits for these sources.  Based on guidance from the 2014 U.S. EPA's SO2 NAAQS Designations Modeling Technical Assistance Document, a ratio of 1-hour to 24-hour block average 99th percentile SO2 emission rates in lbs/hr were calculated using data collected from 2016  -  2020.  This resulted in an adjustment factor of 2,007 lbs/hr / 2,816 lbs/hr = 0.7127.  EPA proposes to find that the adjustment factors of 0.7127 for Sioux is appropriate.  When the longer-term limits were divided by these adjustment factors, they resulted in modeled 1-hour emission rates that are equal to or more stringent than the 1-hour average emission rates represented by the CEV that would otherwise have been necessary to provide for attainment.  While the longer-term average limits allow occasions in which hourly emissions may be higher than the level that would be allowed with the 1-hour limits, the longer-term average limits compensate by requiring average emissions to be lower than the level that would otherwise have been required by a 1-hour average limit that would be represented by the CEV.  As described in the notice of proposed rulemaking and explained in more detail in EPA's April 2014 guidance for SO2 nonattainment plans, EPA finds that appropriately set longer-term average limits provide a reasonable basis by which nonattainment plans may provide for attainment.  

Modeling Parameter: Meteorology and Surface Characteristics

As noted in Appendix W, the selection of data should be based on spatial and climatological (temporal) representativeness.  The representativeness of the data is based on 1) the proximity of the meteorological monitoring site to the area under consideration, 2) the complexity of terrain, 3) the exposure of the meteorological site, and 4) the period of time during which data are collected.  Sources of meteorological data are primarily from National Weather Service (NWS) stations.

For the Alton area of analysis, surface meteorology from St. Louis, Missouri (WBAN No. 13994, 28 kilometers to the southwest) and upper air observations from Lincoln, Illinois (WBAN No. 4833, 157 km to the northeast) were selected as best representative of meteorological conditions within the area of analysis (Figure 4) due to proximity, similar terrain, and availability of recently collected data.  EPA used meteorology data from 2012 - 2016, which was processed by the Illinois EPA and included in their 2018 submittal.  EPA only seeks to correct the deficiencies found in the emissions data and source characterization in Illinois's modeling and the meteorological data processing done by Illinois was determined to be adequate. Additionally, meteorological conditions including prevailing winds at the St. Louis Lambert International Airport are similar between the five-year period of 2012  -  2016 and 2016  -  2020.  Illinois used AERMET version 16216 to process the meteorological data and included the use of 1-minute averaged Automated Surface Observing System (ASOS) wind data which was processed using AERMINUTE version 15272.  Illinois used AERSURFACE version 13016 with 1992 Land Use Land Cover data to estimate the surface characteristics of the area of analysis.  Illinois estimated values for 12 spatial sectors out to 1 km at a monthly temporal resolution for moisture conditions.  These estimated values for the 12 sectors include albedo (the fraction of solar energy reflected from the earth back into space), the Bowen ratio (the method generally used to calculate heat lost or heat gained in a substance), and the surface roughness length (sometimes referred to as "Zo").  In the figure below generated by EPA, the location of the St. Louis station is shown relative to the Alton area of analysis.

                                       
Figure 4: Alton Area of Analysis, the St. Louis Lambert International Airport (KSTL) surface station and the Lincoln, IL (ILX) upper air station.

Illinois used meteorological data from the above surface and upper air stations in generating AERMOD-ready files with the AERMET processor.  The output meteorological data created by the AERMET processor is suitable for being applied with AERMOD input files for AERMOD modeling runs.  Illinois followed the methodology and settings presented in Appendix W in the processing of the raw meteorological data into an AERMOD-ready format and used AERSURFACE to best represent surface characteristics. EPA used the meteorological data processed by Illinois in our supplemental modeling to keep the analysis consistent with Illinois's 2018 submittal.    

Hourly surface meteorological data records are read by AERMET and include all the necessary elements for 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.  Hourly wind data may also be overly prone to indicate calm conditions, which are not modeled by AERMOD.  In order to better represent actual wind conditions at the meteorological tower, 1-minute rolling averaged (2-minute averaged wind data reported every minute) wind data was provided from the same instrument tower, but in a different formatted file to be processed by a separate preprocessor, AERMINUTE.  These data were subsequently integrated into the AERMET processing to produce final hourly wind records of AERMOD-ready meteorological data that better estimate actual hourly average conditions and that are less prone to over-report calm wind conditions.  This allows AERMOD to apply more hours of meteorology to modeled inputs, and therefore produce a more complete set of concentration estimates.  A minimum threshold of 0.5 meters per second was set in processing meteorological data for use in AERMOD.  This approach is consistent with a March 2013 EPA memo titled, "Use of ASOS meteorological data in AERMOD dispersion Modeling."  In setting this threshold, no wind speeds lower than this value would be used for determining concentrations.  This threshold was specifically applied to the 1-minute wind data.  

As seen in Figure 5 below, the predominate wind direction at the St. Louis Lambert International Airport (KSTL) is from the south based on the 2012  -  2016 period, with secondary predominate winds coming from the west-northwest.  


Figure 5: Wind rose for the St. Louis Lambert International Airport (KSTL) surface station for the years 2012  -  2016.  

Modeling Parameter: Geography and Terrain

To account for terrain changes, the AERMAP (version 11103) terrain processor within AERMOD was used by Illinois to specify terrain elevations for all the receptors.  The source of the elevation data incorporated into the model was the 1 arc-second National Elevation Database (NED) from USGS.  EPA used this information in our supplemental modeling.

Modeling Parameter: Background Concentrations of SO2

Section 2.6.1.2 of the August 23, 2010 clarification memo on "Applicability of Appendix W Modeling Guidance for the 1-hour SO2 National Ambient Air Quality Standard" recommends a "first-tier" approach for characterizing background concentrations based on monitored design values.  However, as the "first-tier" approach can be overly conservative in many cases, EPA's March 1, 2011 memo, "Additional Clarification Regarding Application of Appendix W Modeling Guidance for the 1-hour NO2 Ambient Air Quality Standard" provides a temporally varying approach based on the 99[th] percentile monitored concentrations by hour of day and season or month.  For the Alton area modeling analysis, hourly SO2 data from 2014  -  2016 at the East St. Louis, IL monitor (AQS ID: 17-163-0010, coordinates: 38.61203 -90.16048), which is approximately 30 kilometers south of Alton Steel facility, was used to generate season by hour-of-day concentrations.  The monitor avoids double counting the explicitly modeled sources by being upwind of the area of analysis. The predominant wind direction in the Alton area is primarily southerly (as demonstrated by the wind rose in Figure 5 above), as such the East St. Louis monitor is unlikely to measure the emissions released by the modeled SO2 sources.  The season by hour-of-day background concentrations for this area of analysis were determined by EPA to range from 6.81 to 27.4 ppb, with an average value of 14.94 ppb, and these values were incorporated into the final AERMOD results.  Background concentrations for the East St. Louis, IL monitor were not updated for this analysis in order to keep the analysis consistent with Illinois' 2018 demonstration and the meteorological data used in this analysis. 


Figure 6: Location of the East St. Louis monitor (AQS ID 17-163-0010) in relation to modeled sources within the Alton modeling analysis.


Summary of Modeling Results

The AERMOD modeling parameters are summarized below in Table 4.
Table 4: AERMOD Modeling Parameters for the Alton Area of Analysis
                            Alton Area of Analysis
                                AERMOD Version
                                     21112
                          Dispersion Characteristics
                       Regulatory Default options, Rural
                                Modeled Stacks
                                      100
                              Modeled Structures
                                      18
                              Modeled Fencelines
                                 128 receptors
                                Total Receptors
                                      607
                               Meteorology Years
                                 2012  -  2016
                          Surface Meteorology Station
                St. Louis Lambert International Airport (KSTL)
                         Upper Air Meteorology Station
                                 Lincoln (ILX)
           Methodology for Calculating Background SO2 Concentration
           Hourly 2014 - 2016 data from East St. Louis, IL monitor 
                               AQS: 17-163-0010
                    Calculated Background SO2 Concentration
                               6.8  -  27.4 ppb 

The results presented below in Table 5 show the magnitude and geographic location of the highest predicted modeled concentration based on allowable and proposed emissions specified in the SIP. 

Table 5: Maximum Predicted 99th Percentile 1-Hour SO2 Concentration in the Alton Area of Analysis Based on Allowable and Maximum Uncontrolled Emissions
                        99th Percentile 
1-Hour Average
                          Receptor Location (meters)
           SO2 Concentration (micrograms per cubic meter, μg/m[3])
                                       
                             UTM Easting/Latitude
                            UTM Northing/Longitude
                        Modeled (including background)
                                     NAAQS
                    Updated Limits on Sioux and Alton Steel
                                  746,457.70
                                 4,307,329.50
                                     196.2
                                    196.4*
*Equivalent to the 2010 SO2 NAAQS set at 75 ppb

EPA's modeling indicates that the highest predicted 3-year average 99[th] percentile 1-hour average concentration within the chosen modeling domain is 196.2 micrograms per cubic meter (μg/m[3]), or 74.9 ppb with the updated emission limits at Sioux and Alton Steel.  This maximum concentration resulted from modeling all units in the nonattainment area at maximum permitted levels based on the proposed emission limits included in the SIP, already incorporated into Missouri's SIP, maximum uncontrolled emissions, and newly adjusted 1-hour emission rate to which the longer-term limit would be comparably stringent to at Ameren-Sioux, and the background concentration previously described.  Figures 7 and 8 below indicate that the predicted values occurred at the western edge of the receptor grid.

                                       
Figure 7: Maximum predicted 99[th] percentile 1-Hour SO2 concentrations in the Alton area of analysis based on allowable and max uncontrolled emissions.


Figure 8: Maximum predicted 99[th] percentile 1-Hour SO2 concentrations in the Alton area of analysis and modeling domain based on allowable and max uncontrolled emissions.

Conclusion

For a modeling analysis to show attainment of the 2010 SO2 NAAQS, the design value based upon modeled allowable and proposed emissions at the area of maximum ambient SO2 concentration must be equal to or less than 75 ppb for the 1-hour standard.  EPA's modeling for the Alton area showed a design value of 74.9 ppb (196.2 μg/m[3]).  This resulted from modeling all sources in the nonattainment area at maximum levels based on limits incorporated into the proposed emission limits to be included in the SIP, maximum uncontrolled emissions, newly adjusted 1-hour emission rate to which the longer-term limit would be comparably stringent for the Ameren Missouri-Sioux Energy Center, and the background concentration previously described.  Therefore, EPA proposes to conclude that this SIP provides for attainment in the Alton nonattainment area.


Appendix A  -  Modeling Parameters

Table A-1: Point source modeling parameters (all sources modeled as vertical releases)
                                      ID
                                     Desc
                                 Emission Rate
                                    Height
                                  GEP Height
                                   Exit Temp
                                   Exit Vel
                                     Diam
                                      X1
                                      Y1
                                   Base Elev
                                       
                                       
                                     [g/s]
                                      [m]
                                      [m]
                                      [K]
                                     [m/s]
                                      [m]
                                      [m]
                                      [m]
                                      [m]
0027AS1
EAF BH1 (Alton Steel)
                                                                         4.4477
                                                                          30.48
                                                                         116.76
                                                                        394.260
                                                                          9.459
                                                                          7.376
                                                                    747,898.46 
                                                                  4,307,951.71 
                                                                         133.39
0027AS2
EAF BH2 (Alton Steel)
                                                                         4.4477
                                                                          30.48
                                                                         116.93
                                                                        394.260
                                                                          9.459
                                                                          7.376
                                                                    747,956.48 
                                                                  4,307,951.71 
                                                                         133.23
0052AS
New LMF BH Stack (Alton Steel)
                                                                         1.4112
                                                                          21.34
                                                                         115.96
                                                                        408.150
                                                                         46.211
                                                                          0.914
                                                                    747,874.06 
                                                                  4,307,836.75 
                                                                         134.20
0031AS
14 inch rolling mill reheat furnace (Alton Steel)
                                                                         0.0252
                                                                          32.31
                                                                          65.00
                                                                        366.480
                                                                          0.727
                                                                          4.877
                                                                    747,645.22 
                                                                  4,307,691.38 
                                                                         131.80
0099AS
CASTER (Alton Steel)
                                                                         0.0126
                                                                          19.81
                                                                         117.98
                                                                        294.260
                                                                          0.001
                                                                          9.000
                                                                    747,849.10 
                                                                  4,307,673.65 
                                                                         132.18
0002NM
Cleaver Brooks Boiler (Stack 1 of 2) - NM
                                                                         1.2600
                                                                          10.36
                                                                          65.00
                                                                        505.370
                                                                          7.115
                                                                          0.610
                                                                    750,915.14 
                                                                  4,300,903.33 
                                                                         122.96
0004NM
Cleaver Brooks Boiler (Stack 2 of 2) - NM
                                                                         1.2600
                                                                          10.36
                                                                          65.00
                                                                        505.370
                                                                          7.115
                                                                          0.610
                                                                    750,918.74 
                                                                  4,300,902.96 
                                                                         122.96
0001GBC
Ascast furnces (ASC1 & ASC2) + DC Casting Untis 1 & 4 (GBC Metals)
                                                                         0.0252
                                                                          12.50
                                                                          65.00
                                                                        372.039
                                                                         11.000
                                                                          0.640
                                                                    750,127.86 
                                                                  4,306,278.30 
                                                                         131.31
0002GBC
DC Casting Unit #2 (GBC Metals)
                                                                         0.0126
                                                                           9.75
                                                                          65.00
                                                                        327.590
                                                                          1.553
                                                                          0.762
                                                                    750,205.90 
                                                                  4,306,131.67 
                                                                         131.71
0003GBC
DC Casting Unit #5 (GBC Metals)
                                                                         0.0126
                                                                           9.75
                                                                          65.00
                                                                        322.000
                                                                         19.154
                                                                          1.372
                                                                    750,198.95 
                                                                  4,306,129.19 
                                                                         131.80
0054GBC
DC Casting Unit #3 (GBC Metals)
                                                                         0.0126
                                                                           6.09
                                                                          65.00
                                                                        355.370
                                                                         19.160
                                                                          0.396
                                                                    750,154.69 
                                                                  4,306,167.86 
                                                                         131.83
0006GBC
Induction Form Stations & Mix Muller + Low Profile turbine - GBC
                                                                         0.0004
                                                                          12.50
                                                                          65.00
                                                                        372.039
                                                                         11.000
                                                                          0.640
                                                                    750,074.19 
                                                                  4,306,258.69 
                                                                         131.77
0011GBC
Slab Heating Furnace SF-1 (GBC)
                                                                         0.0235
                                                                          18.59
                                                                          65.00
                                                                        413.150
                                                                          1.966
                                                                          1.524
                                                                    750,235.45 
                                                                  4,306,239.12 
                                                                         132.24
0052GBC
Slab Heating Furnace SF-2 (GBC)
                                                                         0.0024
                                                                          24.08
                                                                          65.00
                                                                        755.370
                                                                          1.958
                                                                          1.067
                                                                    750,254.17 
                                                                  4,306,226.00 
                                                                         132.20
0053GBC
Slab Heating Furnace SF-3 (GBC)
                                                                         0.0024
                                                                          17.98
                                                                          65.00
                                                                        755.370
                                                                         12.139
                                                                          1.067
                                                                    750,257.31 
                                                                  4,306,224.78 
                                                                         132.19
0017GBC
Strip Anneal #4 (SA-4) (GBC)
                                                                         0.0035
                                                                          27.43
                                                                          65.00
                                                                        449.820
                                                                         12.610
                                                                          0.488
                                                                    750,149.48 
                                                                  4,308,387.19 
                                                                         133.53
0050GBC
Strip Anneal #5 (SA-5) (GBC)
                                                                         0.0009
                                                                          27.43
                                                                          65.00
                                                                        505.370
                                                                         16.469
                                                                          0.427
                                                                    750,150.53 
                                                                  4,308,372.55 
                                                                         133.45
0051GBC
Strip Anneal #6 (SA-6) (GBC)
                                                                         0.0009
                                                                          33.53
                                                                          65.00
                                                                        577.590
                                                                         19.160
                                                                          0.396
                                                                    750,206.13 
                                                                  4,308,389.28 
                                                                         133.40
0029GBC
Strip Anneal #3 (SA-3) (GBC)
                                                                         0.0007
                                                                          30.48
                                                                          68.74
                                                                        449.820
                                                                         19.148
                                                                          0.396
                                                                    750,437.95 
                                                                  4,308,327.09 
                                                                         132.64
0030GBC
Strip Anneal #7 (SA-7) (GBC)
                                                                         0.0006
                                                                          27.13
                                                                          65.00
                                                                        533.150
                                                                         11.797
                                                                          0.457
                                                                    750,221.00 
                                                                  4,308,335.00 
                                                                         132.96
0079OL
Package Boiler (B-4) (Olin Corporation)
                                                                         0.0063
                                                                          10.67
                                                                          65.00
                                                                        477.590
                                                                         25.872
                                                                          0.610
                                                                    750,886.19 
                                                                  4,308,613.48 
                                                                         133.45
0090OL
Package Boiler (B-3) (Olin Corporation)
                                                                         0.0063
                                                                          10.67
                                                                          65.00
                                                                        477.590
                                                                         25.872
                                                                          0.610
                                                                    750,890.30 
                                                                  4,308,618.32 
                                                                         133.50
0091OL
Package Boiler (B-2) (Olin Corporation)
                                                                         0.0063
                                                                          10.67
                                                                          65.00
                                                                        477.590
                                                                         25.870
                                                                          0.610
                                                                    750,891.24 
                                                                  4,308,612.33 
                                                                         133.42
0092OL
Package Boiler (B-1) (Olin Corporation)
                                                                         0.0063
                                                                          10.67
                                                                          65.00
                                                                        477.590
                                                                         25.870
                                                                          0.610
                                                                    750,887.96 
                                                                  4,308,608.43 
                                                                         133.39
0093OL
Package Boiler (B-5) (Olin Corporation)
                                                                         0.0063
                                                                          10.67
                                                                          65.00
                                                                        477.590
                                                                         25.870
                                                                          0.610
                                                                    750,882.86 
                                                                  4,308,609.52 
                                                                         133.41
0283OL
Package Boiler (B-6) (Olin Corporation)
                                                                         0.0063
                                                                          10.67
                                                                          65.00
                                                                        477.590
                                                                         25.870
                                                                          0.610
                                                                    750,905.84 
                                                                  4,308,625.03 
                                                                         133.44
0385OL
Rotary Retort (Olin Corporation)
                                                                         0.0533
                                                                           4.88
                                                                          68.82
                                                                        322.040
                                                                          8.118
                                                                          0.509
                                                                    750,504.03 
                                                                  4,308,263.85 
                                                                         132.56
0001ATF
2000 KW Emergency Generator (Alton Water Treamment Facility)
                                                                         0.0003
                                                                           6.71
                                                                          65.00
                                                                        477.590
                                                                         25.936
                                                                          0.204
                                                                    742,582.80 
                                                                  4,309,460.30 
                                                                         153.21
0026CPH
Main Boiler Stack (EP-1) (Conoco Philips Hartford Lubricant Plant)
                                                                         0.0024
                                                                          10.36
                                                                          65.00
                                                                        460.930
                                                                          5.010
                                                                          0.155
                                                                    752,210.97 
                                                                  4,299,870.14 
                                                                         131.83
SX12
Sx boilers 1-2 combined 2019-20 data 100% load - GEP Height
                                                                     1,297.9885
                                                                         145.41
                                                                         145.41
                                                                        322.754
                                                                         16.324
                                                                         10.174
                                                                    735,084.35 
                                                                  4,310,804.39 
                                                                         141.43
0002AM
3 Boilers (Alton Memorial Hospital)
                                                                         0.0077
                                                                          27.13
                                                                          65.00
                                                                        472.040
                                                                          7.350
                                                                          0.914
                                                                    746,447.48 
                                                                  4,309,537.98 
                                                                         156.68
0004ANTH
Boilers 1, 2, 3, and 4 stack (St. Anthony's Hospital)
                                                                         0.0048
                                                                          19.51
                                                                          65.00
                                                                        477.590
                                                                          1.790
                                                                          0.710
                                                                    745,096.49 
                                                                  4,310,363.44 
                                                                         175.88
0002SC
D-B Boiler #7428 (Stack 0002) (St. Clare's Hospital)
                                                                         0.0028
                                                                          13.41
                                                                          66.19
                                                                        616.483
                                                                          5.424
                                                                          0.762
                                                                    745,400.67 
                                                                  4,308,374.84 
                                                                         146.27
0003SC
D-B Boiler #7429 (Stack 0003) (St. Clare's Hospital)
                                                                         0.0028
                                                                          13.41
                                                                          66.39
                                                                        616.483
                                                                          5.424
                                                                          0.762
                                                                    745,405.48 
                                                                  4,308,373.24 
                                                                         146.07
0004SC
D-B Boiler #7430 (Stack 0004) (St. Clare's Hospital)
                                                                         0.0028
                                                                          13.41
                                                                          66.49
                                                                        616.483
                                                                          5.424
                                                                          0.762
                                                                    745,409.53 
                                                                  4,308,372.26 
                                                                         145.97
0004CHM
Drum Asphalt Mixer Stack (Charles E. Mahoney)
                                                                         2.2554
                                                                           7.62
                                                                          65.00
                                                                        419.260
                                                                         20.220
                                                                          1.219
                                                                    749,514.00 
                                                                  4,309,867.90 
                                                                         132.75
0005CHM
Drum Dryer Asphalt Plant Stack (Charles E. Mahoney)
                                                                         2.2554
                                                                           7.62
                                                                          65.00
                                                                        419.260
                                                                         20.220
                                                                          1.219
                                                                    749,431.35 
                                                                  4,309,859.00 
                                                                         132.63
0007CHM
Asphalt Heaters and Boilers Stack (Charles E. Mahoney)
                                                                         0.3528
                                                                           3.05
                                                                          65.00
                                                                        449.820
                                                                         21.310
                                                                          0.305
                                                                    749,520.31 
                                                                  4,309,905.72 
                                                                         133.06
0004WRB
CR-1 ULD HCU STK12-4 (WRB)
                                                                         7.3860
                                                                          65.00
                                                                          65.00
                                                                        608.150
                                                                         14.810
                                                                          4.572
                                                                    754,868.40 
                                                                  4,302,624.00 
                                                                         134.41
0018WRB
DU-1 Primary Heater South F-301 STK5-2 (WRB)
                                                                         0.9437
                                                                          45.72
                                                                          96.68
                                                                        339.000
                                                                          3.280
                                                                          2.591
                                                                    754,326.10 
                                                                  4,303,076.20 
                                                                         134.76
0019WRB
DU-1 Secondary Heater North F-302 STK5-1 (WRB)
                                                                         1.7085
                                                                          56.39
                                                                         100.48
                                                                        432.000
                                                                          8.240
                                                                          2.438
                                                                    754,325.60 
                                                                  4,303,099.10 
                                                                         134.81
0020WRB
SMR Heater STK12-8 (WRB)
                                                                         3.5884
                                                                          60.96
                                                                         133.70
                                                                        672.000
                                                                         14.140
                                                                          3.658
                                                                    754,872.30 
                                                                  4,302,749.40 
                                                                         134.54
0024WRB
RAU Debutanizer Heater STK5-5 (WRB)
                                                                         0.5342
                                                                          22.86
                                                                         100.78
                                                                        727.000
                                                                         11.720
                                                                          1.524
                                                                    754,469.50 
                                                                  4,302,942.70 
                                                                         134.51
0027WRB
CAU RO Still Heater STK5-4 (WRB)
                                                                         0.7409
                                                                          25.91
                                                                         100.73
                                                                        700.000
                                                                          7.880
                                                                          2.195
                                                                    754,467.40 
                                                                  4,302,962.50 
                                                                         134.56
0043WRB
Catalytic Cracking Unit No. 2 (Wet Gas Scrubber) STK6-3B
                                                                         9.8568
                                                                          53.34
                                                                         133.36
                                                                        579.000
                                                                          8.260
                                                                          3.353
                                                                    754,847.70 
                                                                  4,302,894.50 
                                                                         134.88
0050WRB
HCF Furnace STK12-3 (WRB)
                                                                         0.6955
                                                                          54.56
                                                                          65.00
                                                                        605.000
                                                                         11.230
                                                                          1.920
                                                                    754,723.80 
                                                                  4,302,515.50 
                                                                         134.20
0056WRB
HCNHT Furnace STK12-1 (WRB)
                                                                         0.0025
                                                                          32.61
                                                                          65.00
                                                                        488.000
                                                                          5.820
                                                                          1.219
                                                                    754,574.80 
                                                                  4,302,695.20 
                                                                         133.99
0060WRB
Alky HM-1 Heater STK6-5 (WRB)
                                                                         0.2923
                                                                          28.96
                                                                          65.00
                                                                        533.000
                                                                          3.170
                                                                          2.286
                                                                    755,121.20 
                                                                  4,302,814.40 
                                                                         134.80
0061WRB
Alky HM-2 Heater STK6-6 (WRB)
                                                                         0.7724
                                                                          46.02
                                                                         159.01
                                                                        700.000
                                                                         17.350
                                                                          1.753
                                                                    754,929.00 
                                                                  4,303,042.40 
                                                                         135.08
0068WRB
Boiler 15 STK12-15 (WRB)
                                                                         2.8085
                                                                          40.23
                                                                         133.72
                                                                        491.000
                                                                         20.110
                                                                          2.134
                                                                    754,858.70 
                                                                  4,302,776.00 
                                                                         134.52
0070WRB
Boiler 17 STK12-17 (WRB)
                                                                         5.4607
                                                                          45.72
                                                                         133.65
                                                                        431.000
                                                                         17.510
                                                                          3.048
                                                                    754,901.20 
                                                                  4,302,783.60 
                                                                         134.59
0071WRB
Boiler 18 STK6-9 (WRB)
                                                                         1.9429
                                                                          30.48
                                                                         133.59
                                                                        435.000
                                                                         15.720
                                                                          1.890
                                                                    754,919.20 
                                                                  4,302,807.80 
                                                                         134.65
0073WRB
HDU-1 Charge Heater STK13-1 (WRB)
                                                                         0.5254
                                                                          45.72
                                                                          65.00
                                                                        694.000
                                                                         10.080
                                                                          1.524
                                                                    755,216.70 
                                                                  4,302,586.90 
                                                                         134.40
0076WRB
HDU-2 Charge Heater STK12-14 (WRB)
                                                                         0.6312
                                                                          45.72
                                                                          65.00
                                                                        755.000
                                                                         10.260
                                                                          1.768
                                                                    755,021.10 
                                                                  4,302,529.40 
                                                                         134.47
0077WRB
CR-3 Stabilizer Reboiler H-2 STK12-9 (WRB)
                                                                         0.2457
                                                                          45.72
                                                                          65.00
                                                                        783.000
                                                                          2.270
                                                                          2.377
                                                                    755,013.20 
                                                                  4,302,579.70 
                                                                         134.66
0078WRB
CR-3 Regen Heater H-3 STK12-10 (WRB)
                                                                         0.1978
                                                                          45.72
                                                                          65.00
                                                                        922.000
                                                                          2.410
                                                                          2.377
                                                                    755,014.40 
                                                                  4,302,581.60 
                                                                         134.67
0079WRB
CR-3 Charge Heater H-4 STK12-11 (WRB)
                                                                         1.4036
                                                                          45.72
                                                                          65.00
                                                                        700.000
                                                                         11.980
                                                                          2.377
                                                                    755,018.30 
                                                                  4,302,570.40 
                                                                         134.63
0080WRB
CR-3 First Interreactor Heater H-5 STK12-13 (WRB)
                                                                         1.2096
                                                                          45.72
                                                                          65.00
                                                                        672.000
                                                                          9.750
                                                                          2.377
                                                                    755,018.70 
                                                                  4,302,546.80 
                                                                         134.54
0081WRB
CR-3 Second lnterreactor Heater H-6 STK12-12 (WRB)
                                                                         0.6627
                                                                          45.72
                                                                          65.00
                                                                        672.000
                                                                          5.440
                                                                          2.377
                                                                    755,018.60 
                                                                  4,302,558.00 
                                                                         134.59
0083WRB
DHT Charge Heater STK12-5 (WRB)
                                                                         0.8429
                                                                          45.72
                                                                          65.00
                                                                        839.000
                                                                         18.310
                                                                          1.615
                                                                    755,017.50 
                                                                  4,302,643.50 
                                                                         134.74
0120WRB
F-200 F-202 F-203 F-204 F-205 STK5-3 (WRB)
                                                                         5.7342
                                                                          82.74
                                                                          82.74
                                                                        472.000
                                                                         10.620
                                                                          4.267
                                                                    754,414.80 
                                                                  4,303,015.80 
                                                                         134.80
0128WRB
SRU North Oxidizer STK3-1 (WRB)
                                                                         2.8854
                                                                          38.10
                                                                          65.00
                                                                        792.000
                                                                          1.760
                                                                          2.195
                                                                    752,927.80 
                                                                  4,303,076.40 
                                                                         130.48
0144WRB
SRU South Oxidizer STK3-2 (WRB)
                                                                         2.8854
                                                                          38.10
                                                                          65.00
                                                                        792.000
                                                                          1.760
                                                                          2.195
                                                                    752,928.10 
                                                                  4,303,070.40 
                                                                         130.47
0621WRB
Distilling Flare FLR1-1 (WRB)
                                                                         0.0794
                                                                          55.21
                                                                          65.00
                                                                      1,255.000
                                                                         20.000
                                                                          0.866
                                                                    754,277.40 
                                                                  4,303,296.20 
                                                                         134.46
0623WRB
Arom North Flare Aromatic FLR13-1 (WRB)
                                                                         0.2104
                                                                          61.93
                                                                          65.00
                                                                      1,255.000
                                                                         20.000
                                                                          0.430
                                                                    755,265.80 
                                                                  4,302,634.50 
                                                                         134.51
0624WRB
Arom South Flare FLR13-2 (WRB)
                                                                         0.1210
                                                                          63.63
                                                                          65.00
                                                                      1,255.000
                                                                         20.000
                                                                          1.040
                                                                    755,267.00 
                                                                  4,302,549.20 
                                                                         134.49
0625WRB
North Property Flare FLR1-2 (WRB)
                                                                         2.4431
                                                                          65.48
                                                                          65.00
                                                                      1,255.000
                                                                         20.000
                                                                          2.200
                                                                    754,485.40 
                                                                  4,303,321.20 
                                                                         134.55
0628WRB
Boiler 4 STK9-1 (WRB)
                                                                         1.4225
                                                                          22.86
                                                                          65.00
                                                                        672.000
                                                                         29.420
                                                                          1.219
                                                                    752,782.10 
                                                                  4,302,397.30 
                                                                         131.10
0629WRB
Boiler 5 STK9-3 (WRB)
                                                                         1.1340
                                                                          22.86
                                                                          65.00
                                                                        427.000
                                                                          3.240
                                                                          2.134
                                                                    752,762.93 
                                                                  4,302,362.97 
                                                                         131.10
0633WRB
DCU Charge Heater H-20 STK10-2 (WRB)
                                                                         1.5170
                                                                          54.86
                                                                         105.45
                                                                        533.000
                                                                         14.560
                                                                          1.524
                                                                    753,183.30 
                                                                  4,302,406.70 
                                                                         130.20
0643WRB
Catalytic Cracking Unit No. 1 (Wet Gas Scrubber) STK6-2B
                                                                         9.8568
                                                                          53.34
                                                                         133.29
                                                                        352.590
                                                                         10.170
                                                                          3.353
                                                                    754,863.70 
                                                                  4,302,894.50 
                                                                         134.95
0685WRB
Alky Flare FLR6-1 (WRB)
                                                                         0.2545
                                                                          66.77
                                                                         158.74
                                                                      1,255.000
                                                                         20.000
                                                                          2.220
                                                                    755,034.60 
                                                                  4,303,080.00 
                                                                         135.35
0702WRB
VF-4 Charge Heater H-28 STK9-6 (WRB)
                                                                         0.2155
                                                                          54.86
                                                                         105.25
                                                                        466.000
                                                                          7.040
                                                                          7.930
                                                                    753,053.00 
                                                                  4,302,387.20 
                                                                         130.34
0703WRB
DCU Preheater H-36 STK10-3 (WRB)
                                                                         0.2066
                                                                          54.86
                                                                         105.47
                                                                        644.000
                                                                          6.620
                                                                          7.570
                                                                    753,193.20 
                                                                  4,302,396.10 
                                                                         130.18
0704WRB
DU-4 Charge Heater H-24 STK9-5 (WRB)
                                                                         1.0281
                                                                          54.86
                                                                         104.04
                                                                        560.000
                                                                         14.720
                                                                         37.720
                                                                    753,050.90 
                                                                  4,302,412.20 
                                                                         130.40
0706WRB
HP-1 Flare FLR12-2 (WRB)
                                                                         0.0013
                                                                          43.09
                                                                          65.00
                                                                      1,273.000
                                                                         20.000
                                                                          0.942
                                                                    755,193.80 
                                                                  4,302,792.10 
                                                                         134.71
0709WRB
HP-1 Heater STK12-6 (WRB)
                                                                         0.0428
                                                                          38.71
                                                                          65.00
                                                                        455.000
                                                                         18.260
                                                                          2.286
                                                                    755,193.00 
                                                                  4,302,792.10 
                                                                         134.71
0711WRB
ULD H-4 Reboiler STK12-2 (WRB)
                                                                         0.5846
                                                                          39.78
                                                                          65.00
                                                                        677.000
                                                                          8.010
                                                                          1.798
                                                                    755,038.00 
                                                                  4,302,710.50 
                                                                         134.79
0712WRB
SZorb Heater STK13-3 (WRB)
                                                                         0.5846
                                                                          45.72
                                                                          65.00
                                                                        652.070
                                                                          4.090
                                                                          2.896
                                                                    755,218.20 
                                                                  4,302,666.40 
                                                                         134.47
0715WRB
Distilling West Flare FLR10-1 (WRB)
                                                                         0.0189
                                                                          61.55
                                                                          65.00
                                                                      1,273.000
                                                                         20.000
                                                                          0.384
                                                                    753,646.00 
                                                                  4,302,545.40 
                                                                         130.13
0716WRB
SZU Stack (0716) (WRB)
                                                                         0.5292
                                                                          13.49
                                                                          65.00
                                                                        324.960
                                                                          3.700
                                                                          0.610
                                                                    755,240.90 
                                                                  4,302,682.20 
                                                                         134.50
0717WRB
Benzene Extraction Unit Heater H-3 STK6-4 (WRB)
                                                                         1.9504
                                                                          56.39
                                                                         133.21
                                                                        516.000
                                                                          7.720
                                                                          2.957
                                                                    754,922.50 
                                                                  4,302,928.90 
                                                                         135.03
0718WRB
Lubes Flare FLR12-1 (WRB)
                                                                         0.0605
                                                                          48.79
                                                                          65.00
                                                                      1,273.000
                                                                         20.000
                                                                          0.396
                                                                    754,609.60 
                                                                  4,302,495.50 
                                                                         134.22
0724WRB
VOC Flare (West) FLR4-1 (WRB)
                                                                         0.1021
                                                                          10.82
                                                                          65.00
                                                                      1,255.372
                                                                         20.000
                                                                          0.427
                                                                    753,427.00 
                                                                  4,303,072.60 
                                                                         130.92
0725WRB
VOC Flare (East) FLR4-2 (WRB)
                                                                         0.1021
                                                                          10.82
                                                                          65.00
                                                                      1,255.372
                                                                         20.000
                                                                          0.427
                                                                    753,440.50 
                                                                  4,303,073.00 
                                                                         130.92
0726WRB
Coker North Flare FLR1-3 (WRB)
                                                                         0.0227
                                                                          60.96
                                                                          65.00
                                                                      1,255.372
                                                                         20.000
                                                                          0.387
                                                                    754,946.10 
                                                                  4,303,683.30 
                                                                         134.29
0727WRB
VF-5 Heater/H350H4 STK1-1 (WRB Refining)
                                                                         3.1197
                                                                          60.96
                                                                         158.49
                                                                        477.590
                                                                         12.210
                                                                          3.048
                                                                    754,936.80 
                                                                  4,303,458.30 
                                                                         135.60
0728WRB
Coker North Heater/H351H2 STK1-2 (WRB)
                                                                         2.5741
                                                                          64.01
                                                                         158.49
                                                                        477.590
                                                                          9.300
                                                                          3.048
                                                                    754,952.70 
                                                                  4,303,304.10 
                                                                         135.60
0729WRB
Coker North Heater/H351H1 STK1-3 (WRB)
                                                                         2.5741
                                                                          64.01
                                                                         158.49
                                                                        477.590
                                                                          9.360
                                                                          3.048
                                                                    754,985.20 
                                                                  4,303,304.90 
                                                                         135.60
0730WRB
DCNH Heater/H353H3 STK1-4 (WRB)
                                                                         0.1562
                                                                          24.38
                                                                         158.84
                                                                        477.590
                                                                         22.140
                                                                          0.640
                                                                    754,903.70 
                                                                  4,303,543.30 
                                                                         135.25
0731WRB
SRU-F Oxidizer STK3-3 (WRB)
                                                                         6.3112
                                                                          60.66
                                                                          65.00
                                                                        477.590
                                                                          8.340
                                                                          1.219
                                                                    752,913.10 
                                                                  4,303,020.00 
                                                                         130.50
0732WRB
SRU-E Oxidizer STK3-4 (WRB)
                                                                         6.3112
                                                                          60.66
                                                                          65.00
                                                                        477.590
                                                                          8.340
                                                                          1.219
                                                                    753,001.50 
                                                                  4,303,022.90 
                                                                         130.40
0735WRB
HP-2 Flare FLR7-1 (WRB)
                                                                         0.0189
                                                                          43.09
                                                                          65.00
                                                                      1,255.372
                                                                         20.000
                                                                          0.942
                                                                    755,262.00 
                                                                  4,302,919.70 
                                                                         134.73
0736WRB
HP-2 Heater STK7-1 (WRB)
                                                                         9.9463
                                                                          39.62
                                                                          65.00
                                                                        418.410
                                                                          4.740
                                                                          3.841
                                                                    755,262.90 
                                                                  4,302,919.70 
                                                                         134.73
0739WRB
NHT Charge Heater H-21 STK10-1 (WRB)
                                                                         0.1298
                                                                          30.48
                                                                         105.45
                                                                        446.180
                                                                          0.850
                                                                          1.372
                                                                    753,160.30 
                                                                  4,302,411.90 
                                                                         130.20
0900WRB
CR-1 Regen Vent STK12-18 (WRB)
                                                                         1.1756
                                                                          17.68
                                                                          65.00
                                                                        320.870
                                                                         13.690
                                                                          0.152
                                                                    754,883.68 
                                                                  4,302,607.56 
                                                                         134.51
0901WRB
CR-3 Regen Vent STK 12-19 (WRB)
                                                                         1.1655
                                                                           9.14
                                                                          65.00
                                                                        320.870
                                                                         38.020
                                                                          0.091
                                                                    755,029.45 
                                                                  4,302,593.48 
                                                                         134.69
FLR_MVC
Barge Loading Flare (WRB Refining)
                                                                         0.0010
                                                                          12.19
                                                                          65.00
                                                                      1,273.000
                                                                         20.000
                                                                          1.219
                                                                    751,375.17 
                                                                  4,302,867.10 
                                                                         127.59
0733WRB
ULD-2 H-1 Process Heater STK6-7 (WRB)
                                                                         0.2495
                                                                          34.14
                                                                         133.06
                                                                        640.000
                                                                          5.270
                                                                          1.372
                                                                    754,950.20 
                                                                  4,302,958.96 
                                                                         135.18
0734WRB
ULD-2 H-2 Process Heater STK6-8 (WRB)
                                                                         0.4297
                                                                          45.72
                                                                         133.04
                                                                        477.590
                                                                          6.590
                                                                          1.219
                                                                    754,959.53 
                                                                  4,302,969.74 
                                                                         135.20

