## Air Dispersion Modeling Guidelines

For Oklahoma Air Quality Permits

Prepared by the Engineering S ection of the Permitting Unit Air Quality Division Oklahoma Department of Environmental Quality

January 2008

This publication is issued by the Oklahoma Department of En vironmental Quality as authorized by Steven A. Thompson, Executive Director. Copies have not been printed but are available through the agency web site. Two printout copies have been deposited with the Publications Clearinghouse of the Oklahoma Department of Libraries.

### Table of Contents

1. INTRODUCTION.......................................................................................... 1

1.1 What is Air Dispersion Modeling ............................................................ 1

1.2 State and Federal Regulations Requiring Modeling.............................. 1

1.3 Levels of Modeling .................................................................................... 2

1.3.1 Screen Modeling........................................................................................ 2

1.3.2 Refined Modeling...................................................................................... 2

1.4 Acceptable Models .................................................................................... 2

1.4.1 SCREEN3 .................................................................................................. 2

1.4.2 AERMOD .................................................................................................. 3

1.4.3 CALPUFF.................................................................................................. 3

1.4.4 Scheffe Tables............................................................................................ 3

1.5 Modeling Protocol..................................................................................... 3

2. MODELING ANALYSIS............................................................................... 4

2.1 Source Type ............................................................................................... 4

2.1.1 Point Source............................................................................................... 4

2.1.2 Area Source ............................................................................................... 4

2.1.3 Fugitive Source.......................................................................................... 4

2.1.4 Volume Source .......................................................................................... 4

2.1.5 Road Emissions ......................................................................................... 5 2.1.5.1 Guidance ................................................................................ 5

2.1.6 Open Pits.................................................................................................... 6

2.1.7 Pseudo-Point Sources................................................................................ 7

2.1.8 Flares ........................................................................................................ 7

2.1.9 Building Vents and Open Doors .............................................................. 82.2 Screening Procedures ............................................................................... 8

2.2.1 Emission Rate............................................................................................ 8

2.2.2 Terrain ....................................................................................................... 8

2.2.3 GEP Stack Height ..................................................................................... 8

2.2.4 Building Downwash .................................................................................. 9

2.2.5 Rural/Urban Classification ...................................................................... 9 2.2.5.1 Land Use ................................................................................ 9 2.2.5.2 Population Density............................................................... 10

2.3 Refined Analysis...................................................................................... 10

2.3.1 Emission Rate.......................................................................................... 10

2.3.2 Terrain ..................................................................................................... 10

2.3.3 Met Data .................................................................................................. 11 2.3.3.1 Selection of Surface Character istics for Met Data Proc 11

2.3.4 Nearby Sources........................................................................................ 14

2.3.5 Background Monitoring......................................................................... 15

2.3.6 GEP Stack Height ................................................................................... 15

2.3.7 Receptor Grids ........................................................................................ 15

2.3.8 NO 2 Modeling.......................................................................................... 16

2.3.9 PM 10 Modeling Guidance....................................................................... 16

2.3.10 Ozone Modeling Guidance-Sheffe Tables............................................. 17

2.3.11 Deposition ................................................................................................ 17

3. STATE REQUIRED MODELI NG ............................................................... 17

3.1 TAC Modeling......................................................................................... 17

3.2 SO 2 Modeling........................................................................................... 18

3.3 TV (Major Source/Modification) Modeling ......................................... 18

4. PSD MODE LING ....................................................................................... 194.1 Significant Impact Analysis ................................................................... 19

4.2 Increment Analysis ................................................................................. 19

4.3 NAAQS Analysis ..................................................................................... 21

4.4 Visibility Analysis.................................................................................... 21

4.4.1 Class II Area Impact Analysis ............................................................... 21

4.4.2 Class I Areas Impact Vi sibility Analysis............................................... 21

APPENDIX A POINT SOURCE MODEL INPUT DATA (E MISSIONS) ............A-1

APPENDIX B FLARE CALCULA TION DERIVA TION......................................B-1

APPENDIX C MODELING PROTOCOL SUBMISSION OUTLINE...................C-1

APPENDIX D FINAL SUBM ISSION OU TLINE ................................................D-1Oklahoma Modeling Guidance Document Page 1 

### 1. Introduction This is a guidance document on air dispersion modeling developed by the Air Quality Division (AQD) of the Oklahoma Department of E nvironmental Quality. The guidance provides assistance to applicants in demonstrating co mpliance with modeling requirements. These requirements protect the public’s health, general welfare, physic al property, and the natural environment.

Air dispersion modeling analyses may be require d with an Air Quality permit application under Oklahoma Administrative Code (OAC) 252, Ch apter 100, Subchapters 8, 31, and 42. This guidance clarifies existing practices, aids the m odeler in developing an acceptable analysis, and assists AQD personnel in expedi ting the review process.

This document relies on mode ling guidance contained in the Guideline On Air Quality Models as codified in 40 CFR Part 51, Appe ndix W, as well as guidance is sued by the EPA Office of Air Quality Planning and Standards (OAQPS) and EPA Region VI.

The remainder of Sections 1 and 2 address general modeling concepts. Sections 3 and 4 address specific issues in modeling toxic air contam inates (TAC), per OAC 252:100-42, and modeling compliance with the National Ambient Air Quality Standards (NAAQS) and Increment consumption for Title V/Part 70, New Source Re view (NSR), and Prevention of Significant Deterioration (PSD) permit applications. Appe ndix A contains a table of point source model input data (emissions) requirements for PSD a nd NSR compliance demonstrations. Appendix B provides a derivation for flare m odeling guidance. Appendix C c ontains a checklist for modeling protocol submission. Ap pendix D contains a checklist for final modeling data submittal.

1.1 What is Air Dispersion Modeling Air dispersion modeling is a method of predicting th e ambient impact of one or more stationary sources of air pollutants. The algorithms used in the models are based both on the known physics of atmospheric processes an d on empirical data. The results of an analysis are used by AQD staff to determine if a new or existing sour ce of air pollutants can comply with state and federal maximum ambient concentration limits. The models are used to predict the highest concentrations expected from a source. For that reason, the models are designed to be conservative, i.e., over-predict ambient impacts. Because the models may over-predict the impact in an analysis, a modeled prediction alone does not mean that there will be a condition of air pollution. This pred iction is a flag indicati ng potential air quality vi olations. AQD staff may require that the source perform more comple x modeling or change physical or operational parameters of the source to reduce ambient impacts. If modeling continues to predict a violation, the AQD may require the source to conduct monitoring.

1.2 State and Federal Regulations Requiring Modeling Various state and federal regulations require modeling. The Oklahom a Administrative Code, Title 252, Chapter 100 (OAC 252:100) codifies air regulations for the AQD. OAC 252:100-8 regulates major sources. Both the federal PSD and NSR construction permit programs and the federal Title V/Part 70 permit program are incorp orated in Subchapter 8. These programs require modeling to demonstrate compliance with a nd to protect the NAAQS and Increment.Oklahoma Modeling Guidance Document Page 2 OAC 252:100-31 regulates emissions of sulfur (S) compounds from stationary sources in Oklahoma. This subchapter also limits th e ambient concentrations of hydrogen sulfide (H 2 S) from new and exiting sources and sulfur dioxide (SO 2 ) from existing sources and new petroleum and natural gas process f acility with equipment s ubject OAC 252:100-31-26(a)(1).

OAC 252:100-42 regulates emissions and impacts of TAC and Areas of Concern (AOC). This subchapter provides the methodology for deve loping and promulgating Maximum Acceptable Ambient Concentrations (MAAC) for individual TA C. TAC and associated MAAC are listed in Appendix O of OAC 252:100. After an AOC has been designated modeling may be required as part of the compliance strategy for the AOC.

1.3 Levels of Modeling

1.3.1 Screen Modeling Screening modeling analyses provide conservativ e estimates of source impacts with a minimum of input. For the EPA model, SCREEN3, worst- case meteorological conditions with respect to Pasquill-Gifford stability classes are used to evaluate maximum ground level concentrations. Screening programs are generally limited in their ability to evaluate terrain impacts and downwash effects from multiple buildings. However, for relatively simple sources, such as a single source with little to no elevated terrain and few downwas h structures, these models will provide conservative estimate s of downwind concentrations.

1.3.2 Refined Modeling Refined modeling requires more detailed and pr ecise input data and utilizes more complex models in order to provide more accurate estim ates of ground level co ncentrations. Refined modeling may be required if the sc reening analysis results indicate that predicted concentrations from the evaluated sources could exceed a standard or a guideline. Refined modeling may also be requested if it is determined that a scr eening analysis will not adequately address the modeling scenario. It is usua lly the applicant’s responsibilit y to perform refined modeling.

1.4 Acceptable Models In general, AQD defers to the Guideline on Air Quality Models , 40 CFR Part 51, Appendix W on the issue of acceptable models. This document provides guidance on appropriate model applications. The document is updated as EPA approves new models. However, AQD reserves the option to evaluate the use of unapproved models on a case-by-case basis. Depending on circumstance, this evaluation may require concur rence by EPA Region VI a nd/or public review. The following models may be used as is appropriate.

1.4.1 SCREEN3 SCREEN3 is the primary single-s ource screening model available from EPA. The model may be used for point, area, volume, and flare sources. EPA is currently working on a beta version of the code for AERSCREEN which will be released as soon as possible. AERSCREEN is the screening model for AERMOD and will replac e use of SCREEN3. The model will produce estimates of regulatory design conc entrations without the need fo r meteorological data and is designed to produce concentrations that are equal to or greate r than the estimates produced by AERMOD with a fully developed set of meteorological and terrain data.Oklahoma Modeling Guidance Document Page 3 1.4.2 AERMOD As of December 9, 2006, the AERMOD modeling sy stem, a steady-state plume dispersion model for assessment of pollutant concentrations from a variety of sources, has become the primary model used for refined modeling. AERMOD inco rporates air dispersi on based on planetary boundary layer turbulence structur e and scaling concepts, includi ng treatment of both surface and elevated sources, and both simple and complex terrain. There are two input data processors of the regulatory AERMOD modeling system: AE RMET, a meteorological data preprocessor that incorporates planetary boundary layer turbulence struct ure and scaling concepts, and AERMAP, a terrain data preprocessor that inco rporates complex terrain using USGS Digital Elevation Data. The model code and supporti ng documents are not static but evolve to accommodate the best available science. Be sure to check the EPA SCRAM website often for updates.

1.4.3 CALPUFF CALPUFF is a multi-layer, multi-species non- steady-state puff dispersion model. The CALPUFF model should be used for long-range imp acts (greater than 50 km ), visibility (light extinction), and acid deposition in Class I areas. CALPUFF modeling is generally required for PSD source impacts on Class I areas.

1.4.4 Scheffe Tables The Scheffe Tables are a screening method fo r predicting 1-hour ozone impacts from VOC dominated sources. Richard Sche ffe developed the Scheffe Tables through use of the Reactive Plume Model (RPM). Since promulgation of the 8-hour standard, use of the Scheffe Tables has become questionable. Until EPA publishes guidel ines for compliance for individual sources, large sources will be included in available photoc hemical modeling datasets and will be modeled with the Comprehensive Air Quality Model with extensions (CAMx) to assess impacts and demonstrate compliance with the standard.

1.5 Modeling Protocol A modeling protocol is required prior to performing any refined modeling analysis for PSD and NSR applications. For PSD/NSR applications, th e AQD requests that the protocol be available for review prior to pre-application meetings. The applicant should allow one to two weeks for review. If the applicant proposes to use an unapproved model, four to six weeks should be allowed for examination. Upon review, the a pplicant will receive wr itten notification of acceptance of the modeling approach as well as guidance on any outstanding issues. However, the applicant should be aware that an approved modeling prot ocol does not n ecessarily limit the extent of the modeling that will be required to demonstrate compliance with the applicable standards. A general outline for a complete mode ling protocol is available in Appendix C. The outline identifies the expected format and content of the submission.Oklahoma Modeling Guidance Document Page 4 

### 2. Modeling Analysis

2.1 Source Type

2.1.1 Point Source This is the most common type of source to be modeled. Emissions from point sources are released to the atmosphere through well-defined stacks, chimneys, or vent s. Point sources are usually buoyant and have an upw ard velocity. The following stack parameters are needed to model point sources: emissions, insi de diameter, height above ground level, velocity or flow rate, and temperature. Other paramete rs relating to neighboring struct ures (height, width, length, and location with respect to the stack) may also be needed to include effects from building downwash.

2.1.2 Area Source The area source algorithms are used to model lo w level or ground level releases with no plume rise (e.g., storage piles, slag dumps, and lagoons). The area source may be used to specify a rectangular-shaped area source with arbitrary orientation, an irregu larly-shaped polygon of up to 20 sides, a circular-shaped area source (modeled as an equal-area polygo n of up to 20 sides).

Area sources use an emission rate per unit area instead of total emissions. Emissions for area sources should be the annual average emissions. The total emissions are divided by the total area in square meters. Detailed guidance for area sources is contained in the User's Guide for the AMS/EPA Regulatory Model - AERMOD (EPA-454/B-03-001, 9/2004).

Caution : A 10:1 aspect ratio of length to width must be maintained when developing rectangular areas sources. If this ratio is to be exceeded , the area should be subd ivided accordingly to achieve the target aspect ratio.

Note: AERMOD has not implemented plume meander for area sources. Please refer to the AERMOD Implementation Guide (October 19, 2007) for guidance concerning this issue.

2.1.3 Fugitive Sources Fugitive dust usually refers to dust put into the air by the wind blowing over roads, fields, or piles. Reentrained dust is put in to the air by vehicles traveling over dirt roads or dusty areas. Fugitive emissions include emissions that are no t captured and vented through a stack but that are vented to the atmosphere through general build ing vents. These types of fugitive sources can be modeled as line, area, or volume sources. Fugitive sources modeled as “area” sources must have a significant degree of m echanically generated turbulence (e.g., sand and gravel operations, haul roads).

2.1.4 Volume Source The volume source algorithms are used to model re leases from a variety of industrial sources, such as building roof monitors, multiple vents, and conveyor belts. The following parameters are needed to characterize volume sour ces: emission rate, release height (h e ), and initial horizontal ( σ Yo ) and vertical dimensions ( σ Zo ).Oklahoma Modeling Guidance Document Page 5 The release height is the center of the volume above ground. Determination of the initial horizontal and vertical dimensions (initial sigmas) are based on th e geometry and location of the source. The actual height, widt h, and depth of the release are used to calculate the initial horizontal and vertical dispersi on parameters. Guidance for deve loping the initial sigmas is contained in Table 3-1 of the User's Guide for the AMS/EPA Regulatory Model - AERMOD (EPA-454/B-03-001, 9/2004) a nd is reproduced below.

The base of the volume source must be square. If the source is not square, model the source as a series of adjacent volume sour ces. For relatively uniform sour ces, determine the “Equivalent Square” by taking the square root of the area of the length and width of the volume base.

Table 3-1. Summary of Suggested Proce dures for Estimating Initial Lateral Dimensions and Initial Vertical Dimensions for Volume and Line Sources Type of Source Procedure for Obtaining Initial Dimension Initial Lateral Dimension ( σ Yo

) Single Volume Source σ Yo = length of side divided by 4.3 Line Source Represented by Adjacent Volume Sources σ Yo = length of side divided by 2.15

Line Source Represented by Separated Volume Sources σ Yo = center to center distance divided by 2.15

Initial Vertical Dimension ( σ Zo

) Surface-based Source (h e ~0) σ Zo = vertical dimension of source divided by 2.15 Elevated Source (h e >0) on or adjacent to a Building σ Zo = building height divided by 2.15

Elevated Source (h e >0) not on or adjacent to a building σ Zo = vertical dimension of source divided by 4.3

2.1.5 Road Emissions The AQD may require fugitive dust from road emissi ons to be modeled. If modeling is required, the emissions should be modeled as a volume source.

2.1.5.1 Guidance The following is some guidance concerning modeling of road emissions.

• Do not include road emissions in permit mo deling analyses for short-term averaging periods - periods less than annual.

• Do not include road emissions in permit mode ling analyses for an annual averaging period if they will not be generated in association with the transport, storage, or transfer of materials (raw, intermediate, and waste), includi ng sand, gravel, caliche, or other road-base aggregates at the facility.Oklahoma Modeling Guidance Document Page 6 Volume Source Characterization: Follow the eight steps described in the following paragraphs: Step 1: Determine the adjusted width of the road. The adjusted width is the actual width of the road plus 6 meters. The additional wi dth represents turbul ence caused by the vehicle as it moves al ong the road. This width will repr esent a side of the base of the volume. Step 2: Determine the number of volume sources, N. Divide the length of the road by the adjusted width. The result is the maximum number of volume sources that could be used to represent the road. Step 3: Determine the height of the volume. The he ight will be equal to twice the height of the vehicle generating the emissions ; rounded to the nearest meter. Step 4: Determine the initial horizontal sigma for each volume.

• If the road is represente d by a single volume, divide the adjusted width by 4.3.

• If the road is represented by adjacent volumes, divide the adjusted width by 2.15.

• If the road is represented by alterna ting volumes, divide twice the adjusted width, measured from the center point of the first volume to the center point of the next represented volume, by 2.15. Start with the volume nearest to the property line. This representati on is often used for long roads. Step 5: Determine the initial vertical sigma. Divide the height of the volume determined in Step 3 by 2.15. Step 6: Determine the release point. Divide the hei ght of the volume by two. This point is in the center of the volume. Step 7: Determine the emission rate for each volume used to calculate the initial horizontal sigma in Step 4. Divide the total emissi on rate equally among the individual volumes used to represent the road, unless there is a known spatial variation in emissions. Step 8: Determine the UTM coordinate for the release points. The release point location is in the center of each of the base of the volume. This location must be at least one meter from the nearest receptor. (TNRCC 1999)

2.1.6 Open Pits The open pit source option is used to model particulate emissions from open pits, such as surface coal mines and rock quarries. The open pit sour ce option uses an effective area for modeling pit emissions, based on meteorological conditions, and then utilizes the numerical integration area source algorithm to model the impact of emi ssions from the effective area sources. The AERMOD model accepts rectangular pits with an optional rotation angle sp ecified relative to a north-south orientation. The rotation angle is specified relative to the vertex used to define the source location (e.g., the southw est corner). Open pit sour ces have no plume rise. The parameters needed are the open pit emission rate, the average release height, the lengths of the sides of the open pit, th e volume of the open pit, and the orie ntation angle in degrees from the north. Please note the following:

• As with the area source, an emi ssion rate per unit area is used.

• The release height parameter cannot exceed the effective de pth of the pit, which is calculated by the model based on the length, width and volume of the pit.

• A release height of 0.0 indicates emissions that are released from the base of the pit.Oklahoma Modeling Guidance Document Page 7 • The length-to-width aspect ratio for ope n pit should be less than 10 to 1.

• Unlike the area source, the open pit cannot be subdivided. Characterize irregularly shaped pit areas by a rectangular shape of equal area.

2.1.7 Pseudo-Point Sources Fugitive sources and non-standard stacks (stacks or vents with rain caps, and stacks or vents that release emissions horizontally) may be modeled as pseudo-point sources. Nonstandard point sources may have buoyancy or momentum and the modeling parameters used should provide representative impacts. Please refer to the AERMOD Implementation Guide (October 19, 2007) for guidance concerning this issue. Tilted stacks can take into acc ount the vertical velocity of the plume using trigonometric factors where appropriate.

2.1.8 Flares Flares are handled similarly to point sources; howev er, the heat release is used to calculate plume rise and effective stack diameter. For scr eening purposes, the flare option in SCREEN3 is acceptable. A flare option is not available in AE RMOD. Therefore, in refined modeling, it is necessary to compute equivalent emission parame ters to account for the buoyancy of the plume. There are several assumptions made in the SCR EEN3 flare option, which form the basis of the equivalent parameter approach. The following parameters are assumed in SCREEN3:

An ambient temperature of 293 K, 55% of the heat lost due to radiation, a plume rise calculated from the top of the flam e, assuming that the flame is bent 45 degrees from the vertical, an effective stack ex it velocity of 20 meters per second, and an effective stack exit temperature of 1,273 K.

The stack height and inside diameter are adju sted to account for the flame height and the buoyancy of the plume by the following equations:

478

. 0 00128

. 0

c actual equiv Q H H + = (Eq. 1)

c equiv Q x D 4 10 758

. 1
− = (Eq. 2)

Where: H equiv = equivalent height of the flare, m H actual = actual height of the stack from the ground, m Q c = flared gas heat release, Btu/hr D equiv = equivalent diameter of the flare, m

The derivation for the equations is available in Appendix B. Th e selection of effective stack parameters could influence the building downwash estimates. Therefore, if building downwash is of a concern then more realistic stack paramete rs should be evaluated. For this circumstance, please seek individua l guidance from AQD.Oklahoma Modeling Guidance Document Page 8 2.1.9 Building Vents and Open Doors Vents with a vertical discharge and no impediment to flow may be modeled as point sources. Horizontal vents or stacks with rain caps s hould be modeled as pseudo-point sources. Open doors may be modeled as pseudo-point sources with a stack height of two thirds ( 2⁄3 ) the total height of the opening. The stack height may be adjusted based on the release height within the building. Please seek specific guidance from the AQD.

2.2 Screening Procedures 2.2.1 Emission Rate The maximum short-term emission rate should be used to demonstrate compliance with all short term averaging rates. Model emission input data for point sources has been defined by EPA in 40 CFR Part 51, Appendix W, Tables 8-1 and 8-2 and is reproduced in Appendix A.

Note : For equipment that may run under a variety of conditions that affect emission rates and dispersion modeling estimates, a series of screen ing analyses should be run to determine the worst-case impact. For example, turbines should be evaluated at varying loads and temperatures to determine the worst-case scenarios.

2.2.2 Terrain If the terrain within five kilome ters of the stack rises to more than 20% of th e shortest, nonfugitive, on-site stack being modeled, then the te rrain feature elevations should be included for the receptor grid. Terrain should be included in all refined modeling.

2.2.3 Met Data When conducting screening using AERMOD, use th e most recent (at least 2001-2005) Integrated Hourly Surface (ISH) data from the National Clim atic Data Center (NCDC) and Upper Air (UA) data from the Forecast System Laboratories (FSL) without incorporating data from the Oklahoma Mesonet. However, in corporation of Oklahoma Mesone t data will be required for refined modeling.

2.2.4 GEP Stack Height Good Engineering Practice (GEP) st ack height is the minimum stac k height needed to prevent the stack exhaust plume from being entrained in the wake of nearby obstr uctions. If a proposed stack is below the GEP height, then the plume entrainment mu st be taken into account by modifying certain dispersion parameters used in air dispersion models. However, if the stack height equals or exceeds the calc ulated GEP stack height, then the stack height is considered the GEP stack height. Plume entrainment within th e wake of nearby obstruc tions is unlikely and need not be considered when modeling stacks at the GEP stack height. The GEP stack height limitation set forth in OAC 252: 100-8-1.5 applies in all cases.Oklahoma Modeling Guidance Document Page 9 2.2.5 Building Downwash When one or more structures interrupt the wi nd flow, an area of turbulence called building downwash is created. Pollutants emitted from a fa irly low level (e.g., a roof, vent or short stack) can be caught in this tu rbulence, affecting their dispersion. Modeling that includes calculations for building downwash gives a more accurate re presentation of pollutant impact than does modeling that omits consider ation of downwash affects.

A building is any physical obstruction to airflow at the modeled facility. A structure is a building or group of buildings determined to be important in downwash considerations. The dominant downwash structure is the structure that renders th e highest GEP recommended stack height. If a stack is at GEP or higher, then downwash is not a factor. GEP stack height is calculated according to the following equation.

L h H 5

. 1 + =
where: H = Recommended stack height. h = The distance from the highest point on a tier or building to ground level. L = The lesser of the height or projecte d width for a particular tier or structure.

SCREEN3 calculates the maximum projected widt h as the greatest crosswind distance between two points in a building or structure. There ar e methods of determining the downwash structures and in fact the dominant downwash structure; how ever, if multiple downwash structures exist, the BPIP-Prime program should be us ed in conjunction with AERMOD.

2.2.6 Rural/Urban Classification Dispersing plumes encounter more turbulence in ur ban areas than in rural areas, due to building wakes as well as the somewhat warmer temperat ures in urban areas. For any given set of meteorological conditions, the urban plume dispersion coefficients s hould be larger than the rural plume dispersion coefficients. The higher coefficients cause an urban plume to spread more rapidly than a rural plume, and hence the ma ximum ground-level concen tration of an urban plume occurs closer to the emission source th an it does for a rural plume. (Beychok 1994)

All models allow for the selection of urban or rural dispersion coefficients. Determination of the applicability of urban or rura l dispersion is based on land use or population density. The land use method is preferred.

2.2.6.1 Land Use Circumscribe a 3 km radius circle about the sour ce. If Auer land use ty pes I1, I2, C1, R2, and R3 account for 50 percent or more of the area, sele ct the urban option. Ot herwise, use the rural option.Oklahoma Modeling Guidance Document Page 10 Auer Land Use Categories I1, I2, C1, & R2 (Auer 1978) Type Use and Structure Vegetation I1 Heavy Industrial Major chemical, steel and fabr ication industries; generally 3-5 story buildings, flat roofs Grass and tree growth extremely rare; <5% vegetation I2 Light-moderate industrial Rail yards, truck depots, ware houses, industrial parks, minor fabrications; generally 1-3 story buildings, flat roofs Very limited grass, trees almost totally absent; <5% vegetation C1 Commercial Office and apartment buildings, hotels;>10 story heights, flat roofs Limited grass and trees; <15% vegetation

R2 Compact Residential Single, some multiple, family dwelling with close spacing; generally <2 story, pitched r oof structures; garages (via alley), no driveways Limited lawn sizes and shade trees; <30% vegetation

2.2.6.2 Population Density Compute the average population density per square kilometer within the ar ea as defined above. If the density is greater than 750 people/km use th e urban option. Otherwis e, use the rural option.

2.3 Refined Analysis 2.3.1 Emission Rate The maximum short-term emission rate should be used to demonstrate compliance with all short term averaging rates. Model emission input data for point sources has been defined by EPA in 40 CFR Part 51, Appendix W, Tables 8-1 and 8-2 and is reproduced in Appendix A.

Note : For equipment that may run under a variety of conditions that may affect emission rates and dispersion modeling estimates, a series of scr eening analyses should be run to determine the worst-case impact. For example, turbines should be evaluated at varying loads and temperatures to determine the worst-case impact scenario.

2.3.2 Terrain Terrain data should be included in all refined modeling analyses. Terrain data is available from United States Geological Survey (USGS) as Digi tal Elevation Modeling (DEM) data. These data are generally available in two resolutions: 1-degree DEM maps a nd 7.5-minute maps (referred to as quadrangles). The 7.5-minute quadrangles ar e freely available in the new Spatial Data Transfer Standard (SDTS) format and will need to be converted to the DEM format. The 7.5-minute DEM data are the preferred source for elevation data. AQD can provide DEM data via email for small modeling domains. AQD will only accept 1 degree DEM data for use with coarse grids with receptor spacing of 1 km and great er, without a specific demonstration or determination that another reso lution is more appropriate.Oklahoma Modeling Guidance Document Page 11 The 7.5-minute DEM are based on Universal Transv erse Mercator (UTM) coordinates and use a 30 meter spacing. Interpolation of receptor and source heights from the DEM data should be based on the current guidance co ntained in Section 4.4 of the User’s Guide for the AERMOD Terrain Preprocessor (AERMAP) (EPA-454/B-03-0003, 10/2004). AERMAP uses a distance weighted bilinear interpolation method.

Oklahoma has three UTM zones (zones 13, 14, and 15). If the modeling domain crosses a UTM zone, source and receptor coordinates will need to be translated to a common zone. The UTM coordinates on the DEM data may not be consis tent with those on paper maps. Though most maps and DEM data in Oklahoma are based on the 1927 North American Datum (NAD27), the applicant must check for consistency. Theref ore, the datum on which source coordinates and elevation data are based on must be reported in the application. In some areas multiple DEM data may be available for download from US GS, only level 2 DEM files may be used.

The Army Corps of Engineers has developed a c onversion program, which will translate data to a common zone and will also convert from one datum to another. The program is called Corpscon and may be obtained from the AQD.

Note: Digital elevation data obtained originally in the SDTS format may be used if obtained from the USGS after June 1, 2001. All earlier da ta in the SDTS format contains a positional error that may impact modeling.

2.3.3 Met Data AQD is now requiring use of 2001-2005 Oklahoma Me sonet data, as on-sit e data, with NCDC ISH data, and FSL UA data, with all refined ai r dispersion modeling. AQD is incorporating use of the Oklahoma Mesonet data to help preven t adverse environmental impacts and to promote the use of good science by use of more recent, more accurate, and more representative data. Oklahoma Mesonet data was provided to the AQD courtesy of the Oklahoma Mesonet, a cooperative venture between Oklahoma State Univer sity (OSU) and the Univ ersity of Oklahoma (OU) and supported by the taxpayers of Oklaho ma. The Oklahoma Mesonet is a world-class network of meteorological monitoring stations. The Mesonet is unique in its capability to measure a large variety of meteorol ogical conditions at so many sites across an area as large as Oklahoma. Standard Mesonet data includes: air temperature and relative humidity at one and a half meters, wind speed, wind direction, and th e standard deviation of wind speed and wind direction at ten meters, the wind speed at two mete rs, the air temperature at nine meters, rainfall, barometric pressure, solar radiation, soil temp eratures, and calibrated soil moisture and temperatures. At each site, these variables ar e continuously measured and packaged into 5- minute observations. The observations were then converted into hourly averages. These hourly averages were processed by the AQD into a format that was able to be processed by AERMET. Soil measurements were not included in the fina l data sets developed for use by AERMET. Some of the variables are not used by AERMET at this time but were incorporated into the data sets in hopes that they could be used in the future.Oklahoma Modeling Guidance Document Page 12 The National Weather Service operates 14 automa ted weather stations in Oklahoma. These stations usually take atmospheric measurem ents once every hour. The Oklahoma Mesonet consists of at least one stati on in each of Oklahoma’s 77 coun ties and measures the variables once every five minutes providing more frequent and more localized information. Data from the Oklahoma Mesonet will help make more accurate forecasts of ambient impacts from stationary sources located in Oklahoma. A table of th e current Oklahoma Mesonet sites is shown in Appendix E.

The data obtained from the Oklahoma Mesonet came in hourly data files that contained all of the standard data from all of the sites for that hour. The first part of formatting the data was to create a single file for each of the Mesonet sites that cont ained all of the data from that site. This was done using a Pearl script. Next, the data from each site was imported into Microsoft Excel and formatted. Formatting the data in Excel was prim arily done using Visual Basic. The individual tasks performed on the Mesone t data are listed below:

1. Import Mesonet data set into Excel (Dat a not imported: WMAX, TS10, TB10, TS05, TB05, TS30, & WVEC). 2. Change all missing value codes to -9 99 (Missing Values: -995,-996,-997,-998,-999). 3. Change the format of the year from YYYY to YY. 4. Calculate the precipitation fo r each hour. Mesonet precipitati on data is the hourly sum of precipitation during the day. To determine th e hourly precipitation, the difference between that hour and the previous hour was determined unless that hour was the first hour of the day. 5. Convert time from minutes to hours by dividing the minutes by 60. 6. Change pressure from hPa (mb) to dPa (mb x 10). 7. Resize all columns to a fixed width of 8. 8. Format the variables to the correct number of significant digits as floating point numbers. TAIR, WSPD, WSSD, WDSD, TA9M, & WS2M each were established with one significant digit. PRES, R ELH & WDIR each established with zero significant digits. PRCP was established with 2 significant digits. 9. Arrange all the columns in the correct order (single and multi-level variables). 10. Sort the columns by year, month, day and then hour. 11. Replace all solar radiation values of -1 with zero.

After the data was formatted, the data was eval uated for missing data. The hour(s) for which the data was/were missing was determined and then replacement values were calculated and inserted, if applicable. All missi ng data was documented so that if there were some issues for a particular hour it could be dete rmined if it was due to data substitution. The files documenting missing data in the Mesonet data sets are avai lable for review upon request. When a single hour of Mesonet observations was missing, the value(s) for that hour was/were interpolated by taking the average of the previous hour and the follo wing hour. If more than one hour of Mesonet observations were missing, those hours were not ch anged. AERMET should be set to run so that NWS data is used when on-site data is missing so that the most complete data set can be used when conducting the modeling.Oklahoma Modeling Guidance Document Page 13 Processed Oklahoma Mesonet data should be co mbined with NCDC ISH data and FSL UA rawinsonde observation (RAOB) da ta using AERMET to produce the surface and profile files used by AERMOD. NCDC ISH data sites and UA rawinsode data sites were assigned to each Mesonet site. Generally the closest ISH or UA s ite was chosen. However, when there were two or more sites that were about the same di stance from a Mesonet site, climate regions, topography, meteorology, and other factors we re taken into account when designating the applicable ISH or UA data site for the correspo nding Mesonet data site. The ISH data sites were reviewed for completeness and if there was a sign ificant amount of missing data then those sites were not considered when assigning them to Mes onet data sites. All UA data was reviewed for missing data, if there was missing data it was replaced using data from a site with similar thermodynamic profiles. Each UA site was assigned a primary and a secondary UA site. When there was a sounding missing from the data it wa s replaced with a sounding from the primary UA data site. If a sounding was not available fr om the primary UA data site, then a sounding from the secondary UA site was used.

2.3.4 Selection of Surface Characterist ics for Met Data Processing When using AERMET to prepare the meteorologi cal data for AERMOD, you must input three surface characteristics: Albedo, Bowen Ratio, a nd Surface Roughness Le ngth. These values should be determined using the AERSURFACE tool version 08009. Th e guidelines in the AERSURFACE User’s Guide (EPA-454/B-08-001, 1/2008) should be followed when using the AERSURFACE tool. For facilities wanting to us e different surface characteristics and or met data, site-specific surface analysis, sensitivity analysis, and/or meteorological data may be required. The following are AQD’s guidance on sp ecific prompts from the AERSURFACE tool:

• “Enter the type of coordinate used to define the center of the study area. ‘UTM’ for Universal Transverse Mercator coordinates; ‘LATLON’ for Latitude and Longitude coordinates. (Note: User responses are not case-sensitive.)”

The user should enter “LATLON” for this question. The user will then be prompted to enter the Latitude (in decimal degrees) and then the Longitude (in decimal degrees), using a negative number for west longitude. The user must al so specify the horizontal reference datum (NAD83 or NAD27). The user should use the latitude and longitude of the a pplicable Mesonet data site as shown in Appendix E. The latitude and longitude for each site is based on the NAD83 horizontal reference datum.

• “Enter the radius (in km) of the study area used for surface roughness (0.1 – 5.0 km). The recommended default value is 1 km.”

The user should enter the default value. If a ra dius other than the recommended default value of 1km is used, it should be documented and justif ied in a modeling protoc ol prior to conducting the modeling.

• “Do you want to define the surface r oughness length for multiple sectors?”

The user should enter “N” for this question. Wh en determining the surface characteristics for each Mesonet site the applicant should only define one sector.Oklahoma Modeling Guidance Document Page 14 • “Define the temporal resolution of surf ace characteristic outputs (ANNUAL, SEASONAL or MONTHLY). ... Enter 'A' for ANNUAL, 'S' for SEASO NAL, or 'M' for MONTHLY:”

The user should enter “S” for this question. The temporal resolu tion of the surface characteristics for each Mesonet site shoul d only be determined on a seasonal basis.

• “Does the site experience continuous s now cover for most of the winter?”

The user should enter “N” for this question due intermittent snowfall in Oklahoma.

• “Is this site at an airport?”

The user should enter “N” for this question.

• “Is this site in an arid region?”

The user should enter “N” for this question.

• “Characterize the surface moistu re condition at the site rela tive to climatological normals, to be applied for all periods. Enter ‘A’ fo r Average, ‘W’ for Wet, or ‘D’ for Dry.”

The user should run the program three times one for each of the surface mo isture conditions (A, W, & D). Then based on the information in Appendix F assign the correct Bowen Ratio based on season and condition to the correct temporal period. To determine the surface moisture conditions for each Oklahoma Mesonet site duri ng each season, percent of normal precipitation graphs for each season were reviewed for the full five years of met data. Based on the precipitation data each site was marked as wet or dr y, if applicable. If the data indicated average conditions the period for that site was left blank. Appendix F also contains the most recent land use determination and the call signs of the ISH data sites and the UA data sites to be used with each Mesonet data site.

After the applicant determines the surface characte ristics to use for the applicable Mesonet site, the applicant should submit all AE RSURFACE (.dat) and (.log) f iles with either the modeling protocol or the modeling submittal.

2.3.5 Nearby Sources Existing nearby sources are requi red to be included in PSD and NSR NAAQS and Increment analyses. The AQD allows the use of a modified “10-D Rule” to narrow th e list of sources to only those that have the potential to significantly impact the m odeling domain. The “10-D Rule” eliminates sources from the modeling review when the source’s emissions (TPY) are less than 10 times the distance (in kilometers) from the modele d facility. These sources are designated as background sources and should not be modeled. Stated differen tly, any minor source (100 TPY or less), which is 10 km or more from the source in questi on, may be excluded.Oklahoma Modeling Guidance Document Page 15 Upon request, the AQD will pr ovide a list of sources within a defined ra dius from a facility that should be included in a modeling review. The list will include stack parameters as reported annually in emission inventories an d potential emissions. If required, actual emissions for use in more refined increment consumption modeling will be provided at a later date. All sources and emissions provided to the appli cant by AQD should be included in the modeling analysis. For large inventories, the AQD may reque st that the applicant provide some assistance in obtaining potential and actual emissions for some of the sources to be modeled. This may require the applicant to review permits and permit applications for the sources. Permits usually are available from the AQD in electronic format. The applican t should submit with the application a final list of sources included in the modeling analysis.

2.3.5 Background Monitoring Background concentrations must be added to PS D and NSR NAAQS analyses. If the modeled impacts from the facility are less than the mon itoring de minims levels, ambient monitoring data from the appropriate monitoring sites should be obt ained and used by the a pplicant. Monitoring data should be obtained from the EPA air data web site: http://www.epa.gov/ air/data/index.html

. Concurrence of the AQD should be obtaine d on the appropriate monitor location and concentrations. If a monitoring de minimis le vel is exceeded, the app licant should provide justification for use of existing monito ring based on the guida nce provided in the Ambient Monitoring Guidelines for Prevention of Significant Deterioration (PSD) (EPA-450/4-87-007, 5/1987). If the facility is un able to meet the guidelines pr ovided, pre-construction ambient monitoring to determine the background concentra tions may be required depending on the size and location of the area where the de minimis level is exceeded. Post construction ambient monitoring may also be required or used to show compliance with the NAAQS.

Background concentrations should be based on the monitoring data av ailable for the most recent complete year of data. Background concentrations for short term standards should be based on the highest second highest (H2H) value, except for PM 10 24-hour standard which should be based on the highest fourth highest (H4H) value from the most recent three years of data. Background concentrations for annual standards should be based on the annual mean value, except for PM 10 which should be based on the average of the annual mean from the most recent three years of data.

2.3.6 GEP Stack Height The Good Engineering Practice (GEP) stack hei ght limitation of OAC 252:100-8-1.5 applies in all cases. The Building Parameter Input Progr am Plume Rise Model Enhancements (BPIPPRIME) should be used for AERMOD.

2.3.7 Receptor Grids 100 meter spacing is usually sufficient for mo st purposes except preliminary coarse-grid modeling. While Cartesian Grids ar e preferred, polar grids will be acceptable so long as the receptor distances do not exceed grid spacing requirements. Before a final receptor grid formation may be established, concentrations modeled on an initial coarse grid should be evaluated. Areas of maximum c oncentration should be establishe d and a fine grid (100 meter spacing) should be used uniformly throughout th ose areas and extending to 1 kilometer beyondOklahoma Modeling Guidance Document Page 16 the areas of maximum concentration. It is the applicant’s responsibility to demonstrate that the grid is sufficiently compact to identify the maximum concentration for each averaging period.

The receptor grid used should extend far enough to determine the maximum impact from all of the sources at the facility and al l nearby facilities. The receptor grid for each modeling analysis is different due to the local meteorology, te rrain, and source makeup. The draft New Source Review Workshop Manual Prevention of Signifi cant Deterioration and Nonattainment Area Permitting (EPA, 10/1990).NSR workshop manual indi cates that in general a grid extending out to 10 km will be “adequate to identify areas of maximum concentration. However, the total number of receptors will vary based on the sp ecific air quality analysis performed.” Appendix W to 40 CFR Part 51 indicates that maximum impacts occur on calm days as the plumes encounter hills at or near the same height as the stacks. Terrain surrounding a facility should be evaluated to determine if there are hills in the area and should be extended to include them. For modeling in which a significant im pact level (SIL) is exceeded and a radius of impact (ROI) is defined, a fine grid (100 meter spacing) shoul d usually extend at least 1 kilometer beyond the ROI. The domain for the receptor grid s hould follow the guidan ce in Section 2.2.1 of User’s Guide for the AERMOD Terrain Preprocessor (AERMAP) (EPA-454/B-03-0003, 10/2004).

Removal of receptors outside the radius of impact or at which a significa nt impact level occurs when modeling the NAAQS or increment for a proj ect is not acceptable. Since the NAAQS and Increment analyses include sources which were not included in the significant impact level analyses, modeling using a receptor grid whic h only includes those receptors at which a significant impact occurs may not ensure that th e maximum impact from the "facility" or from other surrounding sources is determined. If th e NAAQS or increment is violated, then the facility can show that the modifi cation does not have a significant impact at those receptors and a permit may be issued for that modification. If ther e is a “potential” exceedance of a standard in a particular area, whether it is due to the facility or not, AQD can use the modeling to determine the potential causes of the potential exceedance and can take measures to mitigate or alleviate those issues.

2.3.8 NO 2 Modeling Section 5.2.4 of Appendix W, 40 CFR Part 51, imp lements a tiered screening approach to obtain annual average estimates of NO 2 from point sources for PSD and NSR analyses. Use of Tier I (conversion of all NO X to NO 2 ) and Tier II (Use of the ambi ent ratio method (ARM)) of this multi-tiered approach are approved by AQD for all NO 2 modeling. Use of a Ti er III analysis by an applicant should be appr oved by AQD prior to modeling submittal and may require EPA approval.

2.3.9 PM 10 Modeling Guidance The determination of PM 10 design values is briefly discus sed Appendix W, 40 CFR Part 51 and is explained in the PM 10 SIP Development Guideline (EPA-450/2-86-001, 1986). Until incorporation of the new PM 10-2.5 , and PM 2.5 standards, the modeled de sign concentration for the PM 10 24-hour NAAQS is the highest sixth high (H6H) concentration over a 5-year period at any receptor. The MULTYEAR keyword in the cont rol (CO) pathway in the AERMOD model can be used to obtain the H6H concentration in 5 ye ars. The modeled design concentration for the PM 10 annual NAAQS is the 5-year average of th e highest annual average concentrations.Oklahoma Modeling Guidance Document Page 17 However, compliance with the PM 10 24-hour Increment are based on the Highest Second Highest (H2H) value and compliance with the PM 10 Annual Increment is based on the highest annual
average.

2.3.10 Ozone Modeling Guidance-Sheffe Tables Previously, under guidance from EPA, AQD has cons ervatively required the use of the Scheffe tables to evaluate ozone impacts from PSD s ources with VOC emissions greater than 100 tons per year. The Scheffe tables are a tabular result of photoche mical modeling conducted with the Reactive Plume Model, and VOC speciation assu mptions for both rural and urban areas. The tables are used as a conser vative screening analysis.

Since promulgation of the 8-hour standard use of the Scheffe Tables has become questionable. Until EPA publishes guidelines for compliance for individual sources, large sources will be included in available photochemi cal modeling datasets and will be modeled with CAMx to assess impacts and demonstrate compliance with th e standard. However, an applicant may be required to conduct more extensive modeling using models such as the CAMx, or the Community Multiscale Air Quality Modeling System (CMAQ) , which are acceptable for determining ozone impacts.

2.3.11 Deposition The Addendum to the User's Guide For The AMS/EPA Regulatory Model – AERMOD (EPA454/B-03-001, 10/2004) explains th e deposition algorithms and specifies the source parameters for use of deposition. All additio nal data used for an air disper sion analysis that incorporates deposition should be provided to and approved by AQD.

The wet deposition option should not be used fo r regulatory modeling analysis. Wet deposition is not a guideline feature of AERMOD. Per EP A guidance, dry gas deposition is not usually required for PM 10 evaluations because of negligible sett ling velocities. However, AQD reserves the right to request a dry depos ition evaluation for any PM emi ssions, but most specifically for TAC.


### 3. State Required Modeling

3.1 TAC Modeling The AQD as part of the compliance strategy for an AOC may require owners or operators of applicable stationary sources within an AOC to perform ambient air modeling for the TAC of concern to demonstrate compliance with the ap plicable MAAC established per OAC 252:100-42. All applications of air quality modeling shall be based on the applicable models, databases, and other requirements specified in Appendix W of 40 CFR Part 51. Modification or substitution of approved models will be considered on a case-by-case basis. Owners or operators of facilities located in an AOC shall not be required to demonstrate compliance with the TAC MAAC within the boundaries of their facilities.Oklahoma Modeling Guidance Document Page 18 3.2 SO 2 Modeling Subchapter 31 controls emissi ons of sulfur compounds from stationary sources. Per OAC 252:100-31-7(a) emissions of SO 2 from any existing facility or any new petroleum and natural gas process facility with equipment subject to OAC 252:100-31-26(a)(1) shall not impact existing ambient air concentrations of SO 2 at any given point by more than:

Concentrations Averaging periods μ g/m 3 ppmv 5-minute 1,300 0.50 1-hour 1,200 0.46 3-hour 650 0.25 24-hour 130 0.05 Annual 80 0.03

Per OAC 252:100-31-7(b) emissions of hydrogen sulfide (H 2 S)from any new or existing source shall not result in a 24-hour aver age ambient air concentration H 2 S at any given point of 0.2 ppmv or greater.

Facilities with emissions of SO 2 and/or H 2 S are required to show compliance with the ambient standards using EPA approved atmospheric disper sion models. Facilities must demonstrate compliance with the ambient air standards taking into account emissions from all the sources at the facility. Per OAC 252:100-31(c) the ambien t standards do not apply to ambient air concentrations or impacts occurring on the prope rty from which such emission occurs, providing such property, from the emission point to the poin t of any such concentration, is controlled by the person responsible for such emission.

3.3 TV (Major Source/Modification) Modeling Criteria pollutant modeling to demonstrate NAAQS and Increment compliance may be required of any new major source or modification to an existing major source with a net increase of 100 TPY of a single criteria pollutant. NAAQS modeling should be conducted by evaluating the total source impact with an appropriate monitored background concentration added. Concurrence from the AQD should be obtained on which m onitor will provide adequate background concentrations. Increment modeling should be c onducted by evaluating the total source impact of increment consuming sources. Temporary s ources of emissions are not required to be included in the modeling analyses as long as they do not impact a Class I area or an area where an applicable increment is known to be violated.

Note : If modeling demonstrates that the sour ce will exceed PSD monitoring thresholds, postconstruction monitoring though not specifically requi red under the Title V/Part 70 regulations may be required under the general authorizations of the DEQ. This decision will be made on a case-by-case basis and will depend on the extent of the impact area as well as the extent to which the NAAQS or Increment are threatened by the source.Oklahoma Modeling Guidance Document Page 19 

### 4. PSD Modeling A checklist for PSD modeling submittals is available in Appendix D.

4.1 Significant Impact Level (SIL) Analysis A significant impact analysis is the first level of m odeling performed in a PSD evaluation. For each applicable pollutant, the analysis must incl ude all stack emissions and quantifiable fugitive emissions resulting from the proposed source. For a proposed modification, the determination includes contemporaneous emissions increases and decreases, with emissions decreases input as negative emissions in the model. The EPA allows for the exclusion of te mporary emissions such as those associated with construction. The applican t is required to compare results to the SIL as defined in 40 CFR Part 51.165(b)(2). If the hi ghest modeled concentration over five years of meteorological data or the Highest First High (H1H) is less than or equal to the SIL, then the demonstration is complete. Per EPA guidance, the source is not cons idered to cause or contribute to an exceedance of the NAAQS or consum e increment if the modeled impact is at or below the SIL. If the highest modeled concentra tion is greater than the SIL, the applicant is required to perform additional refined modeling or reduce the impact to below the SIL. If the modeled impacts remain above the SIL, a ROI is defined. The ROI extends from the center of the proposed facility to the farthest receptor that shows an impact at or above the significance levels.

4.2 Increment Analysis For compliance with the Increment, the design co ncentration for the short term standards (3-hour and 24-hour) is based on the H2H and the highest annual average for the a nnual standards. The AQD maintains a record of county/area baseline dates; however, a database of increment consumers is not available. Upon request, the AQD will provide the applic ant with a list of sources within the ROI plus fifty kilometers. Th e list will include stack parameters as reported annually in emission inventories and potential emissions. Increm ent consuming sources will be indicated in the list. When there are a larg e number of increment consuming sources, the AQD may request assistance from the applicant in dete rmining actual emissions. The applicant should always submit a list of sources included in the modeling analysis with the application.

A Tiered approach is taken to wards modeling increment consumi ng sources. For Tier 1, the increment consuming sources should be modeled us ing their potential emissions. If the applicant is unable to show compliance with the incremen ts using potential emissions, the next tier would be used. For Tier II, actual emi ssions may be used to show comp liance with the Increment. The applicant should make a separate request for actual emissions fr om sources. Actual emissions are generally based on actual ope rating hours, production rates, an d types of materials stored, processed, or combusted and will be determined based on a two year average. For short term increments, if no hourly data exists for a particul ar source then actual em issions should be based on potential emissions. EPA has recently propo sed guidance on calculation of actual emissions which will be incorporated as soon as it becomes final.Oklahoma Modeling Guidance Document Page 20 If the proposed site is within 50 kilometers of another state, th e applicant must obtain a list of sources to be evaluated from that state. If the ROI extends into another state, the applicant must confirm whether a baseline has been set in that regi on or not. If a baseline date has been set, the applicant must follow the guidance provided by that state for the evaluation of increment consumption within that state.

The following excerpt is taken directly from the draft New Source Review Workshop Manual Prevention of Significant Deterioration a nd Nonattainment Area Permitting (EPA, 10/1990).

“For a PSD increment analysis, an estimate of the amount of increment consumed by existing point sources generally is based on in creases in actual emissions occurring since the minor source baseline date. The exception, of course, is for major stationary sources whose actual emissions have increased (as a resu lt of construction) before the minor source baseline date but on or after the major source baseline date. For any increment-consuming (or increment-expanding) emissions unit, the actual emissions limit

, operating level , and operating factor may all be determined from source records and other information (e.g., state emission files), when available, refl ecting actual source opera tion. For the annual averaging period, the ch ange in the actual emissions rate should be calculated as the difference between:

• the current average actual emissions rate , and

• the average actual emissions rate as of the minor source baseline date (or major source baseline date for ma jor stationary sources).

In each case, the average rate is calculated as the average over the previous 2-year period (unless the permitting agency determines that a different time period is more representative of normal source operation). For each short- term averaging period (24 hours and less), the change in the actual emissions rate for the particular averaging period is calculated as the difference between:

• the current maximum actual emissions rate , and

• the maximum actual emissions rate as of the minor source baseline date (or major source baseline date fo r applicable major st ationary sources undergoing construction before the minor source baseline date).

In each case, the maximum rate is the highest occurrence for that averaging period during the previous 2 years of operation.”

If an exceedance of the increment is identified and the applicant has a significant impact on that receptor, the situation must be rectified. Th e AQD cannot issue a permit that violates the increment.Oklahoma Modeling Guidance Document Page 21 4.3 NAAQS Analysis Upon request, the AQD will provide the applicant with a list of sources with in the ROI plus fifty kilometers. The list will include stack paramete rs as reported annually in emission inventories and potential emissions. All sources and emissi ons provided to the applicant by AQD should be included in the modeling analysis. For large inve ntories, the AQD may request that the applicant provide some assistance in obtaini ng potential emissions for some of the sources to be modeled. This may require the applicant to review permits and permit applications for the sources. Permits may be available from the AQD electronically. Th e applicant should submit with the application a list of sources included in the modeling analysis.

If the proposed site is within 50 kilometers of another state, th e applicant must obtain a list of sources to be evaluated from that state. If the radius of impact extends into another state, the applicant must follow the guidance provided by that state for the evaluation of the NAAQS within that state.

Compliance with short term NAAQS (3-hour, 8- hour, and 24-hour) is based on the H2H for all pollutants except for PM 10 . Compliance with the annual sta ndard is based on the highest annual average concentration, except for PM 10 . For PM 10 , compliance with the NAAQS 24-hours average is based on the H6H over fi ve years of data and complian ce with the annual standard is based on the five year average of the annual average concentrations.

4.4 Visibility Analyses Visibility impact analyses are required for th e area around the affected source and may be required for any Class I areas near the affect ed source. The current EPA guidance document Workbook for Plume Visual Impact Screening and Analysis (Revised) (EPA 454/R-92-023, 10/1992) describes how to evaluate plume visual impacts including use of the visual impact screening model (VISCREEN). VISCREEN can be applied in two successive screening modes without the need for extensive input. If screening calculations using VISCREEN demonstrate that during the worst case meteorological conditions a plume is imperceptible then it will not cause an adverse impact on visibility. To dete rmine if a plume is perceptible, the impacts are compared to the screening criteria. If impacts exceed the screening criteri a, further analysis may be required. The screening criteria are a change in relative sensitivity ( ∆ E) value of 2.0 and a green absolute contrast value of 0.05.

4.4.1 Class II Area Impact Analysis VISCREEN should be used to address the visibility impacts of a source or modification within a Class II area. There are three levels of visibility analyses the first level is using the emissions and the default parameters defined by the program . The second level is where the user selects certain variables to get a more realistic view of the predicted impacts. The third level is a comprehensive analysis using PLUVUE.

Since VISCREEN was developed to over predict impacts and EPA’s guidance was developed mainly for Class I areas, AQD was concerned that the low screenin g levels would cause applicants to be required to perf orm Level 3 analyses for Class II ar eas. In an effort to prevent potentially time consuming effort s which would not lead to a r eal improvement in air quality,Oklahoma Modeling Guidance Document Page 22 AQD has determined that the Class II levels s hould be approximately three times the Class I screening levels. Therefore, wh en comparing visibility impacts in a Class II area the following levels should be used: a ∆ E value of 6.0 and a green absolute c ontrast value of 0.15. If a Level 1 and Level 2 analysis exceeds these levels a comprehensive analysis should be performed.

There are some sensitive areas located in Class II ar eas. If your facility is located within 40 km of one of these sensitive areas, the boundaries of the sensitive area s hould be used in the visibility analysis. The sensitive areas include but are not limited to the following areas:

Sensitive Area Nearest Town Tall Grass Prairie Preserve Pearson, OK Great Salt Plains State Park Jet, OK Lake Optima Wildlife Refuge Hardesty, OK Rita Blanca National Grassland Felt, OK Black Kettle National Grassland Strong City, OK Arbuckle’s Lake Recrea tional Area Sulfur, OK Tishomingo Wildlife Refuge Tishomingo, OK Deep Fork Wildlife Refuge Okmulgee, OK Ouachita National Forest Big Cedar, OK McCurtain County Wildlife Refuge Hochatown, OK Little River Wildlife Refuge Idabel, OK

Notes: When using VISCREEN and there are no se nsitive receptors located within 40 km of the facility; The distance from the source to the ob server and the distance from the source to the closest Class I area boundary should be set equal to each other and can arbitrarily be set to 1 km; and The distance from the source to farthest Class I area boundary may be arbitrarily established as 10 km. NO 2 emissions can be estimated using the ambient ratio method.

4.4.2 Class I Area Impact Analysis Sources seeking PSD permits in the state of Ok lahoma may be required to perform an impact analysis on a Class I area. Contact information for the federal land managers (FLM) for a Class I area may be obtained from the AQD. There is one Class I area in the state of Oklahoma: The Wichita Mountain Wildlife Preserve managed by th e U.S. Fish and Wildlife Service (FWS). Two Class I areas are located in the state of Arkans as (these areas may require evaluations from sources locating in eastern Oklahoma): The Ca ney Creek Wilderness Preserve and The Upper Buffalo Wilderness Preserve managed by the Fore st Service (FS). Another Class I area is located in the state of Missouri (this area may require evaluations from sources locating in northeastern Oklahoma): The He rcules-Glade Wilderness Pr eserve managed by the FS. Visibility analyses for Class I areas located more than 50 km from a facility must be performed using CALPUFF.

The National Parks Service (NPS) - Air Resource s Division, FWS - Air Quality Branch and FS - Air Quality Program have produ ced a guidance document entitled Federal Land Managers’ Air Quality Related Values Work group (Flag) Phase I Report (December 2000). The guidance set forth in this document is followed in PSD review for Class I area impacts. This document may be obtained electronically from the AQD or the participating agencies.Appendix AOklahoma Modeling Guidance DocumentA-1Point Source Model Input Data For NAAQS Compliance in PSD Demonstrations40 CFR Part 51, Appendix W, Table 8-2Averaging TimeEmission Limit X(#/MMBTU)1Operating Level X(MMBTU/hr)1Operating factor(e.g., hr/yr, hr/day)Proposed Major New or Modified SourceAnnual & QuarterlyMaximum allowable emissionlimit or federally enforceablepermit limit.Design capacity or federallyenforceable permit condition.Continuous operation(i.e., 8,760 hours).2Short term (≤24 hours)Maximum allowable emissionlimit or federally enforceablepermit limit.Design capacity or federallyenforceable permit condition.3Continuous operation (i.e., allhours of each time period underconsideration) (forall hours of themeteorological data base).2Nearby Source(s)4, 6Annual & QuarterlyMaximum allowable emissionlimit or federally enforceablepermit limit.5Actual or design capacity(whichever is greater), or federallyenforceable permit condition.Actual operating factor averagedover the most recent 2 years.7, 8Short term (≤24 hours)Maximum allowable emissionlimit or federally enforceablepermit limit.5Actual or design capacity(whichever is greater), or federallyenforceable permit condition.3Continuous operation (i.e., allhours of each time period underconsideration) (forall hours of themeteorological data base).2Other Source(s)6, 9Annual & QuarterlyMaximum allowable emissionlimit or federally enforceablepermit limit.5Annual level when actuallyoperating, averaged over the mostrecent 2 years.7Actual operating factor averagedover the most recent 2 years.7, 8Short term (≤24 hours)Maximum allowable emissionlimit or federally enforceablepermit limit.5Annual level when actuallyoperating, averaged over the mostrecent 2 years.7Continuous operation (i.e., allhours of each time period underconsideration) (forall hours of themeteorological data base).21Terminology applicable to fuel burning sources; analogous terminology (e.g., #/throughput) may beused for other types of sources.2If operation does not occur forall hours of the time period of consideration (e.g., 3 or 24hours) and the source operation isconstrained by a federally enforceable permit condition, an appropriate adjustment to the modeled emission rate may be made (e.g.,Appendix AOklahoma Modeling Guidance DocumentA-2if operation is only 8:00 a.m. to 4:00 p.m. each day, only thesehours will be modeled with emissions from the source.) Modeledemissions should not be averagedacross non-operating time periods.3Operating levels such as 50 percent and75 percent of capacity should be modeled todetermine the load causing the highestconcentration.4Includes existing facility to which modification is proposed ifthe emissions from the existingfacility will not be affectedby themodification. Otherwise use the sameparameters as for major modification.5See paragraph 9.2.3(c)6See paragraph 9.2.3(d)7Unless it is determined that this period is not representative.8For those permitted sources not yet in operation or that have not established an appropriate factor, continuous operation (i.e., 8,760hours) should be used.9Generally, the ambient impacts from non-nearby background sources can be represented byair quality data unless adequate datadoes not exist.

### Appendix B

Oklahoma Modeling Guidance Document B-1 Flare Calculation Derivation

An American Petroleum Institute (API) publica tion (API 1969) provides a correlation for flame length as a function of the flared gas heat rel ease. This equation was republished and modified for a flame tilted at a 45 ° angle from the vertical in Fundamentals of Stack Gas Dispersion (Beychok 1994). The resulting equation provides th e vertical height of a flare stack flame.

478

. 0 00128

. 0

c fv Q H = (Eq. 1)

Where: H fv = flare stack flame vert ical height vector, m Q c = flared gas heat release, Btu/hr

The equivalent height is then found by summing the height of the flare with the vertical height vector of the flame.

478

. 0 00128

. 0

c actual equiv Q H H + = (Eq. 2)

Where: H equiv = The equivalent hei ght of the flare, m H actual = The actual height of the stack from the ground, m

The total plume rise is derived from the initia l vertical velocity momentum and the initial buoyancy momentum. The buoyancy momentum is e ssentially a measure of the sensible heat emissions from the stack. However, the AERMOD program does not allow the user to directly input the heat release. The flux parameter is in stead calculated from th e temperature differential between the stack and ambient air. This is a probl em for a flare analysis because the heat release is diminished due to radiant heat losses. Ther efore, an equivalent diameter is chosen, which when combined with the temperature assumption will force the program to calculate a buoyancy flux that accounts for the radiant heat loss. This equivalent diameter is back calculated from the Briggs’ buoyancy flux parameter, which is de rived from the sensible heat emissions.

The Briggs’ buoyancy flux parameter may be expr essed by the following equivalent expressions, with the reasonable assumption that combusted stack gas has essentially the same molecular weight and specific heat as ambient air. 

## ( )

s a s s T T T d gv F 4 2 2

−

= (Eq. 3)

and 

## ( )

a a a T cp

gQ F ρ π 1 = (Eq. 4)

Where: g = 9.807 m/sec 2

v s = stack exit velocity, m/sec d = stack exit diameter, m

### Appendix B

Oklahoma Modeling Guidance Document B-2 Q = stack sensible heat emission, cal/sec
cp a = specific heat of ambient air, cal/(g- ° C)
ρ a = ambient air density, g/m 3
T a1 = ambient air temperature, K T a2 = ambient air temperature, °C T s = stack gas temperature, K F = buoyancy flux parameter, m 4 /sec 3

Since g and π are constants and since cp a , T a , and ρ a are essentially constants, it may be inferred that the buoyancy flux parameter is a measure of th e sensible heat emissions from the stack. So, assuming an average annual temperature of 68 ° F or 20 ° C, the equation 4 may be restated as follows: 

# ( ) ( ) cal/sec 10 686

. 3 5 Q x F − = (Eq. 5) and 

# ( ) ( ) BTU/hr 10 580

. 2 6 Q x F − = (Eq. 6)

where: F = buoyancy flux parameter, m 4 /sec 3

Because 55% of the heat is assumed to be lost du e to radiation, equation 6 is adjusted specifically for flares. 

# ( ) ( ) BTU/hr 10 161

. 1 6 Q x F − = (Eq. 7)

The equivalent diameter may now be found as a function of Q by setting equal equations 7 and 3 and solving for the radius (r). 

## ( ) BTU/hr 10 758

. 1 4 Q x D equiv − = (Eq. 8)

where: D equiv = the equivalent diameter of the flare, m

The above guidance is consistent with guidance i ssued by the Ohio EPA. It differs from EPA Region V and Louisiana DEQ guidance with the inclusion of the stack height adjustment; however, this adjustment is made within the SCREEN3 flare option and is appropriate for the AERMOD point source option. It differs from Texas guidance w ith the inclusion of the stack height adjustment and an ambient temperatur e assumption. Texas gui dance is based on an ambient temperature of 35 ° C. Because the ambient temperatur e is important in both the heat release calculation and the equivalent diameter cal culation, care should be exercised in modeling specific events. Rather than using the standa rd guidance above, specific events should be modeled with equivalent parameters based on the actual ambient conditions.

### Appendix C

Oklahoma Modeling Guidance Document C-1 Modeling Protocol Submission Outline

1. Project Overview 1.1. Discussion of Plant Processes 1.2. References to Regulatory Applicability 2. Emission Sources 2.1. Source Description 2.2. Location of Emissions 2.3. Pollutants 3. Impact Assessment Tools and Techniques 3.1. Description of Models to Be Used 3.1.1. Version 3.1.2. Circumstance of use, i.e., SCREEN3 for initial toxic MAAC screening 3.2. Discussion on Use of Ratio method 3.3. Discussion on Merging Stacks 3.4. For PSD Analysis 3.4.1. Discussion on Use of “10 D Rule” 3.4.2. Discussion on method relied upon fo r Ozone impact assessment 3.4.3. Discussion on Use of Visibility Screening Tools for Class I Areas 4. Area Maps and Facility Plot Plans (if available) 4.1. Clearly Marked Scale 4.2. Property Lines 4.3. Fence Lines 4.4. Downwash Structures 4.5. True-north Arrow 4.6. UTM Coordinates for Vertical and Horizontal Borders 4.7. Reference UTM Coordinates and Locations of All Emission Points 4.8. Identification of Sensitive Receptors a nd Nearest Residents (Area Map Only) 4.9. For NAAQS Analysis Identific ation of Any State/Local/On- site Ambient Air Monitoring Sites Used for Background Concentrations 4.10. For PSD Applications, identification of PSD Class I areas within 300 km (186.4 miles) or within 10D of emissions. 4.11. Provide an Accompanying List of Structures with UTM Locations, Heights, and Model Labels or ID Numbers 5. Modeling Emission Inventory 5.1. On-Site Sources 5.1.1. Assumptions 5.1.2. Table of Source Input Data (if available) 5.2. Discussion of Methodology for Obtaini ng Off-property Modeling Parameters 6. Air Quality Monitoring Data For NAAQS Compliance 6.1. Discussion on the Issue of Pre-construction Monitoring 6.2. Proposed Monitoring Sites 6.3. Discussion on How Concentrations will be Adjusted for Background Sources Specifically Modeled. 7. Land Use

### Appendix C

Oklahoma Modeling Guidance Document C-2 7.1. Auer Land-use Analysis 7.2. Copy of USGS map (if used in analysis) 8. Receptor Grid 8.1. Discussion on Grid Type 8.2. Discussion on Receptor Placement 8.3. Diagram of Each Grid Type w/Labels 9. Meteorological Data 9.1. Surface Station 9.2. Upper-air Station 9.3. Period of Record 10. Discussion on Method of Evaluation Additional Impacts Analysis (PSD) 11. Class I Area Impacts Analysis (PSD) 11.1. Discussion of Method of Analysis 11.2. AQRV of concern

### Appendix D

Oklahoma Modeling Guidance Document D-1 Final Submission Outline

12. Project Overview 12.1. Discussion of Plant Processes 12.2. References to Regulatory Applicability 13. Emission Sources 13.1. Source Description 13.2. Location of Emissions 13.3. Table of Emissions by Source and Pollutants 14. Impact Assessment Tools and Techniques 14.1. Description of Models Used 14.1.1. Version 14.1.2. Circumstance of use, i.e., SCREEN3 for initial toxic MAAC screening 14.2. Discussion on Use of Ratio method 14.3. Discussion on Collocating Sources 14.4. For PSD Analysis 14.4.1. Discussion on Use of “10 D Rule” 14.4.2. Discussion on method relied upon fo r Ozone impact assessment 14.4.3. Discussion on Use of Visibility Screening Tools for Class I Areas 15. Area Maps and Facility Plot Plans 15.1. Clearly Marked Scale 15.2. Property Lines 15.3. Fence Lines 15.4. Downwash Structures 15.5. True-north Arrow 15.6. UTM Coordinates for Vertical and Horizontal Borders 15.7. Reference UTM Coordinates and Locations of All Emission Points 15.8. Identification of Sensitive Receptors a nd Nearest Residents (Area Map Only) 15.9. Identification of Any State/Local/On-sit e Ambient Air Monitoring Sites Used for Background Concentrations 15.10. For PSD Applications, identification of PSD Class I areas within 300 km (186.4 miles) or within 10D of emissions. 15.11. Provide an Accompanying List of Structures with UTM Locations, Heights, and Model Labels or ID Numbers 16. Air Quality Monitoring Data 16.1. Discussion on the Issue of Pre-construction Monitoring 16.2. Summary Information for Monitoring Sites 16.2.1. Year of Observation 16.2.2. Location 16.2.3. First, Second, and Fourth High Concentrations 16.2.4. Annual Arithmetic Mean Concentration 16.3. Discussion on How Concentrations will be Adjusted for Background Sources Specifically Modeled. 17. Modeling Emission Inventory 17.1. On-Site Sources

### Appendix D

Oklahoma Modeling Guidance Document D-2 17.1.1. Assumptions 17.1.2. Table of Source Input Data 17.2. Background Sources for NAAQS and Increment Modeling 17.2.1. Discussion of Methodology for Obtaini ng Off-property Modeling Parameters 17.2.2. “10 D Rule” Table 17.2.2.1. All Sources Within 50 km 17.2.2.2. UTM Coordinates 17.2.2.3. Distance from Significant Impact Radius 17.2.2.4. Total Emissions 17.2.3. Table of Source Modeling Parameters 18. Land Use 18.1. Auer Land-use Analysis 18.2. Copy of USGS map (if used in analysis) 19. Receptor Grid 19.1. Terrain 19.1.1. Discussion on Terrain for Individual Receptors 19.1.2. For PSD Applications Attach Contour Plots 19.2. Design 19.2.1. Discussion on Grid Type 19.2.2. Diagram of Each Grid Type w/Labels 20. Meteorological Data 20.1. Surface Station 20.2. Upper-air Station 20.3. Period of Record 21. Modeling Results 21.1. Summary Table for Each Pollutant 21.1.1. Listing Standard, (NAAQS, Increment, or MAAC) 21.1.2. Listing Monitored Background Concentrations 21.2. For Each Standard, Receptor Grid Plots w/Appropriate Concentration 21.3. For PSD Applications, Area Plot w/Concentration Contour Plot 22. Additional Impacts Analysis (PSD) 22.1. Discussion on Method of Evaluation 22.2. Evaluation Results on Growth, Soils and Vegetation 23. Class I Area Impacts Analysis (PSD) 23.1. Discussion of Method of Analysis 23.2. Results of Analysis on effect on AQRV 24. Attached Disks of All Model Input and Output files

### Appendix E – Mesonet Site Information

Oklahoma Modeling Guidance Document E-1

Station Identifiers Elev. # ID Name CITY County Lat. Long. (m) 110 ACME Acme Rush Springs Grady 34.8083 -98.0233 397 1 ADAX Ada Ada Pontotoc 34.7985 -96.6691 295 2 ALTU Altus Altus Jackson 34.5872 -99.3381 416 116 ALV2 Alva Alva Woods 36.7082 -98.7097 439

4 ANTL Antlers Antlers Pushmataha 34.2244 -95.7006 179 111 APAC Apache Apache Caddo 34.9142 -98.2922 440 126 ARD2 Ardmore Ardmore Carter 34.1926 -97.0857 266

6 ARNE Arnett Arnett Ellis 36.0720 -99.9031 719 8 BEAV Beaver Beaver Beav er 36.8025 -100.5300 758 9 BESS Bessie Bessie Washita 35.4019 -99.0585 511 10 BIXB Bixby Bixby Tulsa 35.9631 -95.8662 184 11 BLAC Blackwell Blackwell Kay 36.7544 -97.2545 304 12 BOIS Boise City Boise City Cimarron 36.6926 -102.4970 1267 13 BOWL Bowlegs Bowlegs Seminole 35.1716 -96.6312 281 14 BREC Breckinridge Breckinridge Garfield 36.4120 -97.6939 352 15 BRIS Bristow Bristow Creek 35.7805 -96.3540 239 124 BROK Broken Bow Broken Bow McCurtain 34.0433 -94.6244 113

16 BUFF Buffalo Buffalo Harper 36.8313 -99.6410 559 17 BURB Burbank Burbank Osage 36.6346 -96.8105 301 18 BURN Burneyville Burneyville Love 33.8938 -97.2692 228 19 BUTL Butler Butler Custer 35.5915 -99.2706 520 20 BYAR Byars Byars Garvin 34.8497 -97.0033 345 21 CALV Calvin Calvin Hughes 34.9924 -96.3342 234 22 CAMA Camargo Camargo Dewey 36.0287 -99.3465 589 23 CENT Centrahoma Centrahoma Coal 34.6090 -96.3331 208 24 CHAN Chandler Sparks Lincoln 35.6528 -96.8041 291 25 CHER Cherokee Cherokee Alfalfa 36.7481 -98.3627 362 26 CHEY Cheyenne Cheyenne Roger Mills 35.5462 -99.7279 694 27 CHIC Chickasha Chickasha Grady 35.0324 -97.9145 328 29 CLAY Clayton Clayton Pushmataha 34.6566 -95.3260 186 30 CLOU Cloudy Cloudy Pushmataha 34.2232 -95.2487 221 122 CLRM Claremore Claremore Rogers 36.3211 -95.6462 207

31 COOK Cookson Marble City Cherokee 35.6800 -94.8490 299 32 COPA Copan Copan Washington 36.9099 -95.8855 250 33 DURA Durant Durant Bryan 33.9208 -96.3203 197 34 ELRE El Reno El Reno Canadian 35.5485 -98.0365 419 35 ERIC Erick Erick Beckham 35.2049 -99.8034 603 36 EUFA Eufaula Eufaula McIntosh 35.3032 -95.6571 200 37 FAIR Fairview Fairview Major 36.2635 -98.4977 405 38 FORA Foraker Foraker Osage 36.8405 -96.4278 330 39 FREE Freedom Freedom Woodward 36.7256 -99.1423 530 40 FTCB Fort Cobb Fort Cobb Caddo 35.1489 -98.4661 422 41 GOOD Goodwell Goodwell Texas 36.6018 -101.6010 997 117 GRA2 Grandfield Grandfield Tillman 34.2392 -98.7444 341 43 GUTH Guthrie Guthrie Logan 35.8489 -97.4798 330 44 HASK Haskell Haskell Muskogee 35.7480 -95.6405 183

### Appendix E – Mesonet Site Information

Oklahoma Modeling Guidance Document E-2

Station Identifiers Elev. # ID Name CITY County Lat. Long. (m) 113 HECT Hectorville Hectorville Okmulgee 35.8416 -96.0024 243 45 HINT Hinton Hinton Caddo 35.4844 -98.4815 493 46 HOBA Hobart Hobart Kiowa 34.9897 -99.0528 478 47 HOLL Hollis Gould Harmon 34.6855 -99.8333 497 48 HOOK Hooker Hooker Texas 36.8552 -101.225 912 49 HUGO Hugo Hugo Choctaw 34.0308 -95.5401 175 50 IDAB Idabel Idabel McCurtain 33.8301 -94.8803 110 120 INOL Inola Inola Rogers 36.1425 -95.4507 190

51 JAYX Jay Jay Delaware 36.4821 -94.7829 304 52 KENT Kenton Kenton Cimarron 36.8294 -102.8780 1322 53 KETC Ketchum Ranch Velma Stephens 34.5289 -97.7648 341 54 KING Kingfisher Kingfisher Kingfisher 35.8805 -97.9112 319 55 LAHO Lahoma Lahoma Major 36.3844 -98.1114 396 56 LANE Lane Lane Atoka 34.3088 -95.9972 181 57 MADI Madill Lebanon Marshall 34.0358 -96.9439 232 58 MANG Mangum Mangum Greer 34.8359 -99.4240 460 59 MARE Marena Coyle Payne 36.0643 -97.2127 327 61 MAYR May Ranch Freedom Woods 36.9871 -99.0111 555 62 MCAL McAlester McAlester Pittsburg 34.8823 -95.7810 230 63 MEDF Medford Medford Grant 36.7924 -97.7458 332 64 MEDI Medicine Park Med. Park Comanche 34.7292 -98.5694 487 65 MIAM Miami Miami Ottawa 36.8883 -94.8444 247 66 MINC Minco Minco Grady 35.2723 -97.9555 430 125 MRSH Marshall Marshall Logan 36.1169 -97.6069 311

67 MTHE Mt Herman Smithville McCurtain 34.3107 -94.8228 285 68 NEWK Newkirk Newkirk Kay 36.8981 -96.9104 366 109 NINN Ninnekah Ninnekah Grady 34.9677 -97.9520 356

70 NOWA Nowata Delaware Nowata 36.7437 -95.6080 206 121 NRMN Norman Norman Cleveland 35.2361 -97.4649 357

71 OILT Oilton Oilton Creek 36.0313 -96.4975 255 72 OKEM Okemah Okemah Okfuskee 35.4317 -96.2627 263 73 OKMU Okmulgee Morris Okmulgee 35.5821 -95.9147 205 74 PAUL Pauls Valley Pauls Valley Garvin 34.7155 -97.2292 291 75 PAWN Pawnee Pawnee Pawnee 36.3611 -96.7699 283 76 PERK Perkins Perkins Payne 35.9987 -97.0483 292 118 PORT Porter Clarksville Wagoner 35.8257 -95.5598 193

77 PRYO Pryor Adair Mayes 36.3691 -95.2714 201 78 PUTN Putnam Putnam Dewey 35.8990 -98.9604 589 79 REDR Red Rock Red Rock Noble 36.3559 -97.1531 293 80 RETR Retrop Willow Washita 35.1228 -99.3600 538 81 RING Ringling Ringling Jefferson 34.1937 -97.5881 283 82 SALL Sallisaw Sallisaw Sequoyah 35.4382 -94.7981 157 83 SEIL Seiling Seiling Woodward 36.1903 -99.0403 545 84 SHAW Shawnee Shawnee Pottawatomie 35.3649 -96.9482 328 85 SKIA Skiatook Skiatook Osage 36.4153 -96.0371 282 86 SLAP Slapout Slapout Beaver 36.5975 -100.2620 774

### Appendix E – Mesonet Site Information

Oklahoma Modeling Guidance Document E-3

Station Identifiers Elev. # ID Name CITY County Lat. Long. (m) 87 SPEN Spencer Spencer Oklahoma 35.5421 -97.3415 373 88 STIG Stigler Stigler Haskell 35.2653 -95.1812 173 89 STIL Stillwater Stillwater Payne 36.1209 -97.0953 272 90 STUA Stuart Stuart Pittsburg 34.8764 -96.0698 256 91 SULP Sulphur Sulphur Murray 34.5661 -96.9505 320 92 TAHL Tahlequah Tahlequah Cherokee 35.9724 -94.9867 290 93 TALI Talihina Talihina LeFlore 34.7107 -95.0115 204 94 TIPT Tipton Tipton Tillman 34.4397 -99.1376 387 95 TISH Tishomingo Tishomingo Johnston 34.3326 -96.6790 268 115 VANO Vanoss Vanoss Pontotoc 34.7915 -96.8438 320

97 VINI Vinita Centralia Craig 36.7754 -95.2209 236 98 WALT Walters Walters Cotton 34.3647 -98.3203 308 99 WASH Washington Washington McClain 34.9822 -97.5211 345 100 WATO Watonga Watonga Blaine 35.8419 -98.5262 517 101 WAUR Waurika Waurika Jefferson 34.1678 -97.9882 283 102 WEAT Weatherford Weatherford Custer 35.5083 -98.7751 538 103 WEBB Webbers Falls Webbers Falls Muskogee 35.4730 -95.1321 145 104 WEST Westville Westville Adair 36.0110 -94.6450 348 105 WILB Wilburton Wilburton Latimer 34.9009 -95.3481 199 106 WIST Wister Wister LeFlore 34.9843 -94.6878 143 107 WOOD Woodward Woodward Woodward 36.4233 -99.4168 625 108 WYNO Wynona Wynona Osage 36.5181 -96.3422 269

### Appendix F – ISH and FLS Sites for each Mesonet Site & Surface Moisture Conditions for each Season

Oklahoma Modeling Guidance Document F-1

STID UAS SFCS W N 0 1 S P 0 1 S M 0 1 F L 0 1 W N 0 2 S P 0 2 S M 0 2 F L 0 2 W N 0 3 S P 0 3 S M 0 3 F L 0 3 W N 0 4 S P 0 4 S M 0 4 F L 0 4 W N 0 5 S P 0 5 S M 0 5 F L 0 5
ACME OUN KLAW D D D
ADAX OUN KMLC D D
ALTU OUN KFDR D D D
ALV2 OUN KP28 W W D W D
ANTL FWD KPRX D D
APAC OUN KLAW D D D
ARD2 FWD K1FO W W D D
ARNE AMA KGAG W D D W D W D
BEAV DDC KLBL W D W W D D
BESS OUN KCSM D D D
BIXB OUN KRVS D D D
BLAC OUN KPNC D D
BOIS AMA KDHT D D D D D W D D
BOWL OUN KTIK D D
BREC OUN KGOK D D D
BRIS OUN KRVS D D
BROK SHV KTXK D D
BUFF DDC KGAG W D W D W D
BURB OUN KPNC D D
BURN FWD K1FO W W D D
BUTL OUN KCSM W D D D
BYAR OUN KOUN W D D
CALV OUN KMLC D D
CAMA OUN KCSM W D D D D
CENT OUN KMLC D D
CHAN OUN KSWO D D
CHER OUN KP28 D D
CHEY AMA KCSM W D D D D
CHIC OUN KOUN D D D
CLAY OUN KMLC D D
CLOU SHV KPRX D D D
CLRM OUN KTUL D D D
COOK SGF KMKO D D D
COPA SGF KBVO D D
DURA FWD K1FO W D D D
ELRE OUN KOKC D D D
ERIC AMA KCSM W D D D
EUFA OUN KMLC D D D
FAIR OUN KCSM W D D D

### Appendix F – ISH and FLS Sites for each Mesonet Site & Surface Moisture Conditions for each Season

Oklahoma Modeling Guidance Document F-2

STID UAS SFCS W N 0 1 S P 0 1 S M 0 1 F L 0 1 W N 0 2 S P 0 2 S M 0 2 F L 0 2 W N 0 3 S P 0 3 S M 0 3 F L 0 3 W N 0 4 S P 0 4 S M 0 4 F L 0 4 W N 0 5 S P 0 5 S M 0 5 F L 0 5
FORA OUN KBVO D D
FREE DDC KGAG W D D W D W D
FTCB OUN KHBR D D D
GOOD AMA KLBL D D W W D D
GRA2 OUN KFDR D D D D
GUTH OUN KGOK D D
HASK OUN KMKO D D D
HECT OUN KRVS D D D
HINT OUN KCSM D D D
HOBA OUN KHBR D D D
HOLL AMA KCDS D D D
HOOK DDC KLBL W D D W W D D
HUGO SHV KPRX D D D
IDAB SHV KPRX D D
INOL SGF KTUL D D D
JAYX SGF KSLG D D D
KENT AMA KCAO W D D D D W W D D
KETC OUN KLAW W D W D D
KING OUN KPWA D D D
LAHO OUN KGOK W D D D
LANE FWD KMLC D D
MADI FWD K1FO W D D
MANG OUN KHBR D D D
MARE OUN KSWO D D
MAYR DDC KP28 W W D W D
MCAL OUN KMLC D D
MEDF OUN KPNC D D D
MEDI OUN KLAW D D D
MIAM SGF KJLN D D D
MINC OUN KOKC D D D
MRSH OUN KGOK D D
MTHE SHV KMWT D D
NEWK OUN KPNC D D
NINN OUN KOUN D D D
NOWA SGF KBVO D D D
NRMN OUN KOUN D D
OILT OUN KRVS D D
OKEM OUN KRVS D D
OKMU OUN KRVS D D D

### Appendix F – ISH and FLS Sites for each Mesonet Site & Surface Moisture Conditions for each Season

Oklahoma Modeling Guidance Document F-3

STID UAS SFCS W N 0 1 S P 0 1 S M 0 1 F L 0 1 W N 0 2 S P 0 2 S M 0 2 F L 0 2 W N 0 3 S P 0 3 S M 0 3 F L 0 3 W N 0 4 S P 0 4 S M 0 4 F L 0 4 W N 0 5 S P 0 5 S M 0 5 F L 0 5
PAUL OUN K1FO W D D
PAWN OUN KSWO D D
PERK OUN KSWO D D
PORT OUN KMKO D D D
PRYO SGF KTUL D D D
PUTN OUN KCSM W D D D
REDR OUN KSWO D D
RETR OUN KHBR D D D
RING FWD K1FO W D W D D
SALL LZK KFSM D D D
SEIL OUN KGAG W D D W D W D
SHAW OUN KTIK D D
SKIA OUN KTUL D D
SLAP DDC KGAG W D W D D
SPEN OUN KTIK D D
STIG LZK KFSM D D D
STIL OUN KSWO D D
STUA OUN KMLC D D
SULP OUN K1FO W W D D
TAHL SGF KMKO D D D
TALI LZK KMLC D D
TIPT OUN KFDR D D D D
TISH FWD K1FO W D D
VANO OUN KOUN D D
VINI SGF KBVO D D D
WALT OUN KLAW D D D
WASH OUN KOUN D D
WATO OUN KPWA D D D
WAUR FWD KSPS W D W D D
WEAT OUN KCSM W D D D
WEBB OUN KFSM D D D
WEST SGF KSLG D D D
WILB OUN KMLC D D
WIST LZK KFSM D D
WOOD DDC KGAG W D D W D W D
WYNO OUN KBVO D D STID – Mesonet Station ID; UAS - Upper Air Station Call Identifier; SFCS - ISH Surface Station Call Identifier; WN - Winter; SP - Spring ; SM - Summer; FL - Fall; D – Dry; W - Wet. If no value is assigned to the time period th en it is considered av erage surface moisture.

### References

Oklahoma Modeling Guidance Document R-1 American Petroleum Institute (API). 1969. Gu ide for pressure relief and depressurizing systems. API RP 521, First Edition.

Auer, A. H. 1978. Correlation of Land Use and C over with Meteorological Anomalies, Journal of Applied Meteorology, 17:636-643.

Beychok, Milton R. 1994. Fundamentals of Stack Gas Dispersion. 3rd ed. Irvine, California: Milton Beychok

Davies, M. J. E., and D. M. Leahey. 1984. Obse rvation of Plume Rise from Sour Gas Flares. Atmospheric Environment Volume 18, No. 5: 917-922.

Koerber, Michael, Regional Meteorologist, EPA Re gion V. Letter to Regions I-IV, VI-X, 28 July 1986.

Louisiana Department of Environmental Quality (LDEQ). 1999. Air Quality Modeling Procedures. Baton Rouge , Louisiana: LDEQ

Ohio Environmental Protection Agency (Ohi o EPA). Air Dispersion Modeling Guidance, Engineering Guide No. 69. Columbus, Ohio: Ohio EPA.

Scheffe, Richard D. 1988. VOC/NO X Point Source Screening Tables, draft.

Texas Natural Resource Conservation Co mmission (TNRCC). 1999. Air Quality Modeling Guidelines. Austin, Texas: TNRCC.

United States Environmental Protection Agen cy (EPA). 1990. Draft New Source Review Workshop Manual. Research Triang le Park, North Carolina: EPA

### Index

Oklahoma Modeling Guidance Document I-1 

### 1

10-D Rule 15



### A

AERMAP 12 AERMET 3 AERMOD 3 AERSCREEN 3 Appendix A 1 Appendix W 2 Area Source 5 ARM 17 Auer Land Use 11



### B

BPIP-Prime 10



### C

CALPUFF 3 CAMx 3 Class I 23 Class II 22



### D

DEM 11, 12 Deposition 18 Doors 9 downwash 2, 5, 9, 10



### F

Flares 8, 1 Fugitive Source 5



### G

GEP 9, 16



### H

hydrogen sulfide 2



### I

Increment 20 ISC3 8, 18 ISC-PRIME 16



### L

Land Use 10 

### M

MAAC 2, 18 Mesonet 13 Met Data 9, 12 Monitoring 16



### N

NAAQS 1, 2, 19, 20, 22 NO 2 17 NWS 13



### O

Open pit 7 Ozone 18



### P

Pasquill Gifford 2 plume rise 8, 1 PM 10 17 Point Source 5 Population Density 11 PSD 1, 3, 16, 18, 19, 20 Pseudo-Point Sources 8



### R

rain caps 8, 9 Receptor 16 Refined 2, 11 Region VI 1, 2 release height 5, 6, 7 Road Emissions 6 RPM 3 Rural 10



### S

Scheffe Tables 3 SCREEN3 2, 3, 8, 10, 2 Sensitive Area 23 SIL 20 SO 2 19



### T

TAC 2, 18 terrain 2, 9 Terrain 11 Texas 6, 2 Tilted stacks 8 Title V 1 TV 19

### Index

Oklahoma Modeling Guidance Document I-2 

### U

Urban 10 USGS 11, 12 UTM 7, 12 

### V

Vents 9 VISCREEN 23 Visibility 22 Volume Source 5, 7