U.S. BUREAU OF LAND MANAGEMENT 

Miles City Field Office 

Dispersion Modeling Protocol for Ambient Air 

Quality Impact Assessment 

Supplement to Statewide Final Oil and Gas 

Environmental Impact Statement and 

Amendment of the Powder River and 

Billings Resource Management Plans 

Prepared By: ALL Consulting 

April 2006 
DISPERSION MODELING PROTOCOL 

FOR AMBIENT AIR QUALITY IMPACT ASSESSMENT 

Supplement to Statewide Final Oil and Gas Environmental Impact Statement and Amendment of 

the Powder River and Billings Resource Management Plans 

Prepared for 

U.S. BUREAU OF LAND MANAGEMENT 

Miles City Field Office 

111 Garryowen Road 

Miles City, MT 59301-0940 

Prepared by

ALL Consulting 

Tulsa, Oklahoma 

April, 2006 

i 
TABLE of CONTENTS 

1.0 INTRODUCTION ................................................................................................................................... 1 

1.1 Project Description............................................................................................................................... 3 

1.2 Study Tasks.......................................................................................................................................... 4 

2.0 OVERVIEW OF ASSESSMENT APPROACH ..................................................................................... 6 

3.0 AIR QUALITY MODELING ANALYSIS............................................................................................. 8

3.1 Model Selection and Computational Domain...................................................................................... 8 

3.2 Assessment Areas and Receptor Grids .............................................................................................. 18 

3.3 Proposed Emission Scenarios and Source Groupings ....................................................................... 17 

4.0 MODEL INPUT DATA ........................................................................................................................ 15 

4.1 Emissions Inventory Data .................................................................................................................. 15 

4.1.1 PRB CBNG Sources ................................................................................................................... 16 

4.1.2 Other Sources.............................................................................................................................. 17 

4.2 Meteorological Data........................................................................................................................... 17 

4.3 Ambient Air Quality and AQRV Data............................................................................................... 18 

4.3.1 Criteria Pollutants ....................................................................................................................... 20 

4.3.2 Chemical Species........................................................................................................................ 20 

5.0 ASSESSMENT AND REPORTING OF AIR QUALITY IMPACTS.................................................. 21 

5.1 Prevention of Significant Deterioration of Air Quality ..................................................................... 21 

5.2 Ambient Air Quality ......................................................................................................................... 22 

5.2.1 Criteria Pollutants ....................................................................................................................... 23 

5.2.2 Hazardous Air Pollutants ............................................................................................................ 24 

5.3 Air Quality Related Values................................................................................................................ 23 

5.3.1 Visibility ..................................................................................................................................... 23 

5.3.2 Acidic Deposition and Lake Chemistry...................................................................................... 24 

6.0 REFERENCES ...................................................................................................................................... 26 

APPENDIX A – STATE BY STATE COMPARISON OF AMBIENT AIR QUALITY STANDARDS 

APPENDIX B – ADDITIONAL EMISSIONS SOURCES FOR CUMULATIVE ANALYSES 

ii 
LIST OF TABLES 

4-1 CALMET User-defined Fields Not Specified in IWAQM Appendix A....................................18 

5-1 PSD Increments for Class I and Class II Areas.....................................................................21 

5-2 Applicable Ambient Air Quality Standards.............................................................................22 

LIST OF FIGURES 

1-1 Modeling Domain, Project Areas, Population Centers, and Sensitive Areas ..........................2 

3-1 Sensitive Area Receptor Locations.......................................................................................13 

4-1 Location of Meteorological Data Sources.............................................................................. 19 

B-1 EDF Emission Source Map....................................................................................B-1 

iii 
1.0 INTRODUCTION 

The Bureau of Land Management, Miles City Field Office (BLM) has identified a need to analyze the air 

impacts from additional CBNG development alternatives as evaluated within a Supplement to the Final 

Statewide Oil and Gas Environmental Impact Statement (SEIS) and Proposed Amendment of the Powder 

River (PRBO&G) and Billings Resource Management Plans (BLM, 2003). This document presents a 

protocol that describes methodologies for an air quality study to assess potential impacts on air quality 

and air quality related values (AQRVs) for coal bed natural gas (CBNG) development alternatives. The 

results of this analysis will update the air impacts for the SEIS being prepared by BLM. 

The purpose of this document is to describe how the study is to be conducted, in addition to providing an 

opportunity for reviewers to provide input to the proposed assessment methodologies before the 

assessment is initiated. Reviewers of this protocol are expected to include the BLM, Federal Land 

Managers (FLMs) of affected areas, United States Environmental Protection Agency (USEPA), Wyoming 

Department of Environmental Quality (WDEQ) and Montana Department of Environmental Quality 

(MDEQ), Northern Cheyenne Tribe, Crow Tribe, and Montana Board of Oil and Gas Conservation. The 

current version of this protocol (Revision 1, dated April 1, 2006) incorporates comments received from the 

review of the original document (dated February 2006). 

This assessment protocol is based primarily on the air quality modeling guidelines of the USEPA, 

guidelines of the National Park Service (NPS) and the United States Forest Service (USFS), and 

guidance documents of the WDEQ, and the MDEQ. 

The USEPA’s CALPUFF model was used in both the air quality assessment done for the original 

PRBO&G EIS (Argonne model, 2002), as well as the ongoing PRB Coal Review (ENSR model, 2005) 

sponsored by both the Wyoming and Montana BLM state offices. For this model, the established grid, 

receptors, and emission inventory will be used as a basis for conducting the proposed work. 

Meteorological data will be updated using 3 years of data (Years 2001, 2002, and 2003). The project 

domain to be modeled includes most of Wyoming and Montana, and portions of Utah, North Dakota, 

South Dakota, Idaho and Nebraska (Figure 1-1). Detailed meteorological data for the modeling domain 

will be determined by the mesoscale meteorological model (MM5) and CALMET meteorological models. 

The proposed assessment will use the CALPUFF modeling system for both near-field and far-field 

analyses of air impacts and AQRVs (visibility and acid deposition). 

The remainder of this protocol describes the air quality analysis in further detail and provides a list of 

tasks to be performed. Chapters 2.0 through 6.0 provide an overview of the assessment approach and 

proposed air quality model; describe model input data, including emission inventory data, meteorological 

data, background ambient air quality and AQRV data; describe modeling and post-processing of model 

output data; and reporting of the study’s results. 

SEIS Dispersion Modeling Protocol 1 BLM Miles City 
SEIS Dispersion Modeling Protocol 2 BLM Miles City 
1.1 Project Description 

This air quality study will assess the air impacts of additional SEIS alternatives from CBNG-related 

development in the PRB on Class I and sensitive Class II areas (Figure 1-1). Where data can be 

obtained, the assessment will update the 2002 base year from the ENSR Study to a new 2004 base year. 

Impacts and projected changes in impacts will be evaluated in comparison to current operations or the 

new 2004 base year. A new base year of 2004 was selected because it is the latest year that emissions 

data are expected to be available. The 2004 base year data will include updated emission sources from 

the ENSR Study, the Argonne Study, and a lawsuit filed with the U.S. District Court for Montana by the 

Environmental Defense Fund (Environmental Defense, 2004). Emission inventory source updates will 

include new or updated permit applications, new annual air emissions inventory submittals to states 

within the modeling domain, source emissions data from the Western Regional Air Partnership database, 

any revised USEPA emissions factors, and the use of reported actual emissions or representative actual 

emissions across all sources. 

The study will model the new 2004 base year and three predictive scenarios. The first predictive 

scenario will be a peak period assessment from implementation of the Preferred Alternative from the 

Final Statewide Oil and Gas Environmental Impact Statement. The second and third scenarios will 

consider the peak period assessment(s) from two Phased Development Alternatives. Separate periods 

(years) may be used for different pollutants. 

Following completion of the updated base year modeling (separate base year results using the 3 years of 

meteorological data and determined from a maximum impact consideration; i.e. base year results to be 

used for comparison against predictive model runs will be selected from the separate base year runs 

using each of the 3 years of meteorological data and selecting the year which shows the most reasonably 

conservative impacts within the study area) and the three predictive scenario analyses, a report will be 

prepared to document the results of the CALPUFF modeling. The report will include a comparison of the 

base year results to monitored data for 2004, a comparison of base year results to modeled air impacts 

and AQRVs for the predictive scenarios, and a comparison of all modeled air impacts to applicable state 

and federal standards and guideline values. These results will be presented showing numerical 

comparisons in tables and with maps of the near-field impacts (including the Crow and Northern 

Cheyenne Indian Reservations) showing the location(s) and corresponding concentration(s) of modeled 

impacts with respect to sensitive areas and geographic locations within the modeling domain. 

As an additional task, the report will include an assessment for an additional future period that includes a 

discussion of the air impacts from the proposed construction and implementation of the Tongue River 

Railroad and the Roundup Power Plant. The assessment of impacts for this future year will include any 

corresponding air impacts resulting from the three CBNG development alternatives and any cumulative 

air impacts from other modeled sources. For the Tongue River Railroad and the Roundup Power Plant, 

this analysis will be based on an evaluation of air impact data contained within the respective EISs 

prepared for these projects. For the three CBNG development scenarios, this analysis will be based on 

the modeled predictive year adjusted on the basis of the rate of development for each of the CBNG 

SEIS Dispersion Modeling Protocol 3 BLM Miles City 
development scenarios. 

1.2 Study Tasks 

The following tasks will be performed for this air quality study and AQRV impact assessment. 

• Update the emission inventory database used in the Argonne air model conducted for the 

Montana statewide Oil and Gas EIS (Argonne model) and the ENSR PRB Coal Review model 

(ENSR model) by revising/updating the emission rates, as needed. This may include new or 

updated emission sources to establish a new 2004 base year, new emissions sources from any 

portions of the states comprising the modeling domain, and updating project emissions estimates 

based upon current CBNG project assumptions and findings. When reported actual emissions 

are not available (i.e., some states do not collect actual emissions data for minor sources, only 

potential emissions may be available for some sources, and many permitted sources are never 

built or do not operate at full capacity), potential emissions will be converted to representative 

actual emissions (in such cases those sources will be modeled at 70 percent of their potential to 

emit). Emission sources outside of the modeling domain will not be included. 

• Update the base year modeled impacts by using 3 newer years of meteorological data (years 

2001, 2002, and 2003). These years represent the latest years for which basic MM5 data sets 

are available. The analysis will use actual emissions to model impacts for the three years 

separately. The year with the highest pollutant impacts (prioritized as PM10, visibility, then NOx) 

will be selected as the meteorological data for use to model the predictive scenarios in this study. 

• Evaluate source emission data for the list of 67 potential additional sources identified in the 

Environmental Defense Fund vs. Norton lawsuit. Include these new emissions sources as 

appropriate. (Note: An initial review has shown that at least some of these sources are outside of 

the modeling domain). 

• Assess the predicted cumulative air quality impacts of the base year sources and three modeled 

CBNG development alternatives (the original EIS Preferred Alternative and two Phased 

Development Alternatives) at Class I areas and specified Class II areas of concern. Include a 

comparison to ambient monitored data for the base year, the National Ambient Air Quality 

Standards (NAAQS), State Ambient Air Quality Standards (SAAQS), and PSD increments. 

• Assess the predicted cumulative air quality impacts of the base year sources and three modeled 

CBNG development alternatives (the original EIS Preferred Alternative and two Phased 

Development Alternatives) on visibility degradation and atmospheric deposition at Class I areas 

and specified Class II areas of concern, and on the acid neutralizing capacity (ANC) of identified 

lakes. 

SEIS Dispersion Modeling Protocol 4 BLM Miles City 
• Assess the estimated cumulative air impacts from construction of the Tongue River Railroad and 

the Roundup Power Plant and other modeled sources upon ambient air concentrations and on 

visibility degradation and atmospheric deposition at the Class I areas and specified Class II areas 

of concern, and on the ANC of identified lakes. The impacts for the two construction projects will 

be modeled separately and added to the cumulative impacts from other source groups. 

• Prepare a written report (Technical Support Document) of the study’s findings. 

SEIS Dispersion Modeling Protocol 5 BLM Miles City 
2.0 OVERVIEW OF ASSESSMENT APPROACH 

For this analysis, the CALPUFF modeling system will be used to estimate potential impacts on near-field 

and far-field air quality and far-field AQRVs that would result from air pollutant emissions associated with 

the base year emission sources, CBNG activities, and all other modeled sources. The CALPUFF 

modeling domain for this air quality study will be identical to that used in the original PRBO&G EIS 

analysis. The same receptor sets used in the ENSR model will be used for both far-field and near-field 

analyses, including the encompassed mandatory Class I areas (with the receptor sets recommended by 

the National Park Service), tribal-designated Class I areas, Class II areas of concern, and other sensitive 

areas within the modeling domain. 

This air quality study will include an updated base year emissions inventory database for the year 2004 to 

include updates of the ENSR Coal Study base year sources and updated emissions inventory databases 

from both the Argonne and ENSR analyses for the predictive scenarios. Any emission sources that are 

included in this study may be revised to represent actual emissions to assure consistent, comparative 

results. A representative background value for the criteria pollutants will be added to all modeled results 

to account for natural source, distance source, and other non-point source emissions. Further, this study 

will include as many of the emission sources from the list of 67 identified in a lawsuit filed by 

Environmental Defense for which data can be obtained and which are located within the modeling 

domain. 

Three years of meteorological data (years 2001, 2002, and 2003) will be analyzed to update the 

meteorological database for use in the CALPUFF modeling for the current study. 

The outputs from the air quality modeling will be used to assess potential impacts on near-field and farfield air quality and far-field AQRVs. Air quality impact assessments will be conducted: 

• By comparing air quality impacts resulting from the base year emissions alone. The results will be 

compared to 2004 ambient monitored concentrations and applicable NAAQS and SAAQS. 

• By comparing peak air quality impacts resulting from three SEIS alternative scenarios. The 

results will be compared to the applicable NAAQS and SAAQS, PSD increments, and the base 

year results. 

• By evaluating the air quality impacts resulting from the three SEIS alternative scenarios for an 

additional peak period that includes the development and implementation of both the Tongue 

River Railroad and the Roundup Power Plant. The results will be compared to the applicable 

NAAQS and SAAQS and the PSD increments. 

SEIS Dispersion Modeling Protocol 6 BLM Miles City 
Existing data and modeling results of any PSD increment studies affecting the project area will be 

presented, discussed, and compared to the PSD increments; however, there will be no new study of 

increment-consuming emissions or of expected increment consumption from this study. 

AQRVs to be evaluated will include visibility and acidic deposition. Visibility impacts will be assessed at 

the far-field receptors located in sensitive receptor areas by using the procedure provided by the FLMs’ 

Air Quality Related Values Workgroup (FLAG) (Method 2) and by the method specified by EPA’s Best 

Available Retrofit Technology (BART) guideline (Method 6), which is also used for tracking progress 

under the Regional Haze Rule. The FLAG procedure uses an assumed natural background visibility 

reference level and visibility parameter equations recommended by FLAG. Under the FLAG method, 

estimated visibility degradation will be compared to the established significance thresholds. Method 6 

results will be presented as consistent with the BART guideline. That is, the 98th percentile (or 8th highest 

day per year) for each year will be presented in addition to the number of days of impacts above 0.5 and 

1.0 change in deciviews and the maximum change in deciviews. The FLAG background will be used for 

both Method 2 and Method 6 assessments. Results of both analyses will be reported. 

Acidic deposition impacts will be assessed by predicted annual total deposition fluxes of sulfur and 

nitrogen compounds at several sensitive lakes. If the predicted acidic depositions values are above the 

deposition analysis thresholds (DAT) established by the FLM, then an additional analysis in terms of acid 

neutralizing capacity (ANC) will be conducted. The ANC results will be compared against threshold 

based on USFS recommended prediction methods (USFS 2000) and the total terrestrial deposition 

loading method in Fox et al. (1989). These lakes are provided in Section 5. 

SEIS Dispersion Modeling Protocol 7 BLM Miles City 
3.0 AIR QUALITY MODELING ANALYSIS 

An air quality modeling analysis will be conducted for the current proposed study to assess potential 

impacts on ambient air quality and AQRVs in the modeling domain from existing and projected sources to 

include proposed CBNG activities. The CALPUFF modeling system (Scire et al. 2000) was promulgated 

on April 15, 2003 and is EPA’s preferred/recommended model for long-range transport beyond 50 km. 

CALPUFF can also be used to assess impacts within 50 km. When appropriate, the modeling procedure 

will follow recommendations in the Interagency Workgroup on Air Quality Modeling (IWAQM) and FLAG 

documents for the assessment of both near-and far-field impacts. This analysis will use CALPUFF in the 

refined mode to address the air quality impacts of pollution transported over relatively long distances. 

The air quality modeling analysis will use the actual emission rates (or estimated actual emission rates) 

for all sources. In any situation where actual emissions data is not available, the analysis will estimate 

actual (70 percent of listed potential emission) emission estimates. The 70 percent factor is based upon 

discussions with the Wyoming DEQ concerning a representative emissions factor based upon permitted 

annual allowable emission rates. 

For consistency, other CALPUFF model options and assumptions on background concentrations of 

chemical species to be used in this study will be based on those used in the ENSR and Argonne 

modeling studies when appropriate. For example, the ambient ratio method, which assumes a 

conversion rate of 75 percent, will be used for the oxides of nitrogen (NOX) to NO2 conversion rate, 

according to USEPA guidance (40 CFR 51, Appendix W). 

Concentrations of SO2, NO2, PM10, PM2.5, sulfur and nitrogen deposition, as well as visibility impairment 

(aerosol light extinction) will be predicted at selected receptor locations described in Section 3.2. 

Hazardous Air Pollutants (HAPs) concentrations will be predicted at the project near-field receptors to 

include receptor locations within the Northern Cheyenne and Crow reservations. 

NOX can be a major component of the emissions in the region. CALPUFF simulates the oxidation of NOX 

to nitrate and calculates the equilibrium between sulfate, nitrate, nitric acid, and ammonia to determine 

how much of the converted NOX is particulate nitrate and how much is gaseous nitric acid. 

The outputs from the modeling program will be hourly values of direct concentrations, which will be 

processed using CALPOST to compute 3-hour, 24-hour, and annual average direct concentration 

predictions. Visibility and deposition estimates will be daily values, and annual total sulfur and nitrogen 

deposition flux increments will be derived from the daily values. 

3.1 Model Selection and Computational Domain 

The CALPUFF modeling system has three main components: 

SEIS Dispersion Modeling Protocol 8 BLM Miles City 
• CALMET (Version 5.711 - the diagnostic three-dimensional meteorological model); 

• CALPUFF (Version 5.754 - the transport and dispersion mode); and 

• CALPOST (Version 5.6393 - the post-processor). 

The CALPUFF modeling system is designed to: 

• Treat time-varying point and area sources; 

• Model domains from tens of meters to hundreds of kilometers from a source; 

• Predict results for averaging times ranging form 1 hour to 1 year; 

• Be applied to inert pollutants and those subject to linear removal and chemical conversion 

mechanisms; and 

• Be applied to rough or complex terrain situations. 

CALPUFF is a lagrangian puff model with the capability to simulate regional-scale, long-range dispersion 

as well as local-scale, short-range dispersion (Scire et al. 2000a). 

The modeling domain for the current study will be identical to that used in the CALMET/CALPUFF 

modeling conducted for the PRBO&G EIS, which includes portions of Wyoming, Montana, North Dakota, 

South Dakota, Nebraska, Idaho, and Utah. The spatial extent of the domain is 840-km (east-west) x 720­

km (north-south). The design allows for 210 x 180 grid cells and a 4-km grid element size. That size 

domain requires the use of a Lambert Conformal Projection (LCP) grid system as follows: 

• Central reference LCP point (longitude, latitude) = (-105.0°, 44.0°); 

• Standard latitude parallels at 30° and 60°; and 

• Grid origin (SW Corner) offset from central reference point = (-420 kilometer [km], -360 km). 

The following CALPUFF options also will be selected: 

• Pasquil-Gifford (P-G) dispersion coefficients; 

• Transitional plume rise; 

• Stack tip downwash; 

SEIS Dispersion Modeling Protocol 9 BLM Miles City 
• Transition of horizontal dispersion to time-dependent (Heffter) growth rates; 

• Building downwash effects (based upon data availability); and 

• Chemical transformation based on the MESOPUFF II algorithms. 

3.2 Assessment Areas and Receptor Grids 

The modeling domain (Figure 1-1) for the near-field impact assessment extends at least 50 km in all 

directions beyond the boundaries of the air quality study area and (in most cases) beyond the Class I and 

sensitive Class II receptors of interest, as recommenced by FLAG guidance. Near-field receptor locations 

will be arranged to obtain the maximum estimated concentrations that result from the sources identified in 

this air quality study. These receptor locations will be in areas with high emission density, with additional 

receptors in populated areas (e.g., where populations exceed 200 or more) within the near-field modeling 

domain. The near-field receptor grid will be spaced at 1-km intervals. Near-field receptors that are within 

1 km of a source will be deleted from the receptor set. In addition, the placement of receptors within the 

Class I and sensitive Class II areas will follow the standard receptor sets recommended by the National 

Park Service when available. For those sensitive areas that are not contained in the NPS database of 

receptors, a receptor set will be developed within the sensitive area’s boundary and a grid spacing 

dependant on the spatial coverage of the sensitive area. The elevation of these receptors will be 

obtained by using Digital Elevation Model data for the 1:250,000 quads with 90-m horizontal resolution 

(USGS 2000). 

Each of the following Class I areas and specified Class II areas of concern are within the modeling 

domain and will be included in the analysis: 

• Badlands Wilderness Area (Class I, NPS); 

• Wind Cave National Park (Class I, NPS); 

• Bridger Wilderness Area (Class I, USFS); 

• Fitzpatrick Wilderness Area (Class I, USFS); 

• Washakie Wilderness Area (Class I, USFS); 

• North Abasaroka Wilderness Area (Class I, USFS); 

• Northern Cheyenne Reservation (Class I, Northern Cheyenne Tribal Council); 

• Devils Tower National Monument (Class II, NPS); 

SEIS Dispersion Modeling Protocol 10 BLM Miles City 
• Mount Rushmore National Memorial (Class II, NPS); 

• Jewel Cave National Monument (Class II, NPS); 

• Agate Fossil Beds National Monument (Class II, NPS), 

• Fort Laramie National Historic Site (Class II, NPS), 

• Black Elk Wilderness Area (Class II, USFS); 

• Soldier Creek Wilderness Area (Class II, USFS); 

• Cloud Peak Wilderness Area (Class II, USFS); 

• Yellowstone National Park (Class I, NPS); 

• Grand Teton National Park (Class I, NPS); 

• Teton Wilderness Area (Class II, USFS); 

• Absaroka-Beartooth Wilderness Area (Class II, USFS) 

• Bighorn Canyon National Recreation Area (Class II, NPS); 

• Popo Agie Wilderness Area (Class II, USFS); 

• Wind River Roadless Area (Class II, Shoshone and Arapaho Joint Tribal Business Council); 

• Crow Indian Reservation (Class II, Crow Tribal Council); and 

• Theodore Roosevelt National Park (Class I, NPS). 

In addition, for those Class I and sensitive Class II areas that are near the edge of the modeling domain 

modeled impacts at receptors within these areas might be associated with model inaccuracies and 

uncertainties due to puffs inability to recirculate. Therefore, estimates of potential impacts to these areas 

will be made by placing representative receptors no nearer than 25 km from the edge of the modeling 

domain. These areas include: 

• Bob Marshall Wilderness Area; 

• Gates of the Mountains Wilderness Area; 

• Lee Metcalf Wilderness Area, Spanish Peaks Unit; 

SEIS Dispersion Modeling Protocol 11 BLM Miles City 
• Lee Metcalf Wilderness Area, Taylor Hillgard Unit; 

• Red Rock Lakes Wilderness Area; 

• Jedediah Smith Wilderness Area; 

• Mount Naomi Wilderness Area; 

• Wellsville Mountain Wilderness Area; 

• U.L. Bend Wilderness Area; 

• Fort Peck Indian Reservation; 

• Scapegoat Wilderness Area; and 

• Ft. Belknap Wilderness Area. 

The locations of the above sensitive receptor areas as well as other sensitive areas within the modeling 

domain are shown in Figure 3-1. 

3.3 Proposed Emission Scenarios and Source Groupings 

In order to be able to easily evaluate impacts due to a specific scenario or scenarios, the air quality 

modeling for the current project will be designed so that source contributions for project sources and 

other emission source groups for each scenario can be readily separated. The modeled results will be 

reported for each group individually as well as for all sources combined. The source groups proposed for 

this study include: 

• Montana CBNG construction sources 

• Montana CBNG operational sources 

• Wyoming CBNG construction sources 

• Wyoming CBNG operational sources 

• EDF vs. Norton lawsuit sources 

• Montana conventional Oil & Gas sources 

• Wyoming conventional Oil & Gas sources 

SEIS Dispersion Modeling Protocol 12 BLM Miles City 
Figure 3-1: Sensitive Area Receptor Locations 

SEIS Dispersion Modeling Protocol 13 BLM Miles City 
• Power plants 

• Montana coal related sources 

• Wyoming coal related sources 

• Tongue River Railroad 

• Roundup Power Plant 

• Other sources (i.e., urban area sources, refineries, mining, mineral handling, and other non-coal 

or non-oil & gas sources, etc.) 

A series of separate emissions scenarios representing base year emissions and projections of emissions 

for three alternative scenarios will be developed and modeled. For the predictive scenarios, RFFAs will 

be developed for each source group except for the two “other” groups and the “EDF vs. Norton” source 

group. These RFFAs may be represented by factional increases (i.e., CBNG, conventional O&G, and 

coal related activities) and/or by specific increases in individual sources (i.e., power plants, coal mine 

operations, etc.). 

Results generated by the CALPUFF modeling system, in concert with other natural resource information, 

are used to interpret potential air quality impacts resulting from implementing various proposed CBNG 

scenarios. The model's greatest value is its use in identifying potential maximum impact areas for the 

scenarios. Generated results should not be considered an absolute measure against verifiable 

standards, nor by themselves provide the answer as to the effects of implementing a given scenario. 

Modeled results represent estimates of the air impacts to a project area’s cumulative development history 

and the areas natural resiliency and variability. 

SEIS Dispersion Modeling Protocol 14 BLM Miles City 
4.0 MODEL INPUT DATA

The modeling effort will use a single model (i.e., CALPUFF) to evaluate impacts and changes in impacts 

to air quality and AQRVs resulting from increased development to include CBNG activities in the PRB. 

The air quality analyses will assess impacts from CBNG and other development activity for the base year, 

and will assess the maximum impacts for three predicted CBNG development scenarios (SEIS 

Alternatives). 

4.1 Emissions Inventory Data 

The base year and projected future emissions will be actual reported emissions or estimated actual 

emissions based upon appropriate USEPA emission factors, equations, data, and best available control 

technology (BACT) for anticipated levels of construction and operational activities. Actual emissions from 

sources, both existing and projected, will be based on guidance from the USEPA and state 

environmental agencies. 

The emissions scenarios represent a key component of conducting the air quality analyses. The following 

emissions scenarios will be analyzed for their potential impacts. 

1. Base Year Scenario. A base year emissions database representative of year 2004 operations will 

be developed. The base year scenario will include emissions sources from the ENSR model. 

Emission sources from the Argonne model after converting that data from potential emissions to 

representative actual emissions. Source emissions data from the Western Regional Air 

Partnership database, where those data can be updated from 2002 to 2004. In addition, any of 

the list of 67 additional emission sources identified in an Environmental Defense Fund vs. Norton 

lawsuit (see Appendix B) will be included where actual emissions data for those sources can be 

determined and they are located within the modeling domain. 

2. SEIS Alternative Assessments. The project’s second task is to model three projected SEIS 

emissions scenarios. The first of these scenarios represents the CBNG development for the 

original EIS Preferred Alternative. The second and third scenarios represent the scenarios for two 

Phased CBNG development Alternatives. 

3. Additional Cumulative Impacts Assessment. The third task is an assessment of a future year that 

represents the cumulative impacts considering the three CBNG development scenarios 

addressed above plus the development and implementation of the Tongue River Railroad and the 

Roundup Power Plant. The Tongue River Railroad and the Roundup Power Plant will each be 

modeled as a separate source group. Their individual and/or combined impacts will then be 

considered relative to the cumulative impacts of the CBNG scenarios. Emission rates will be 

based on data presented in the respective EISs for the two development projects. 

SEIS Dispersion Modeling Protocol 15 BLM Miles City 
4.1.1 PRB CBNG Sources 

4.1.1.1 Construction-related Emissions 

Estimates of construction-related actual emissions will focus on emissions of particulate matter (PM) with 

aerodynamic diameters equal to or less than 10 microns (PM10) and less than 2.5 microns (PM2.5). 

Fugitive PM emissions from the construction of well site facilities and roads will be computed on the basis 

of USEPA emission factors for construction activity, along with state permitting guidance for estimating 

emissions. Emissions of road dust generated from construction vehicles will be estimated by using the 

USEPA unpaved road emission factor equation (USEPA 2003a), work done by the Western Regional Air 

Partnership (WRAP) on fugitive road dust emissions, and anticipated volume of project traffic. Fugitive 

dust emissions from construction equipment and vehicles will be computed by using applicable USEPA 

emission factors (USEPA 2003a) and estimated usage levels of construction equipment and vehicles. 

Construction site emissions will be treated as area sources. Exhaust emissions and road dust emissions 

also will be treated similarly because exact locations of roads to be built are not known. Vehicle traffic 

emissions from secondary population growth are not included in this analysis. 

4.1.1.2 Operational Emissions 

For the operational phase, emissions of pollutants (nitrogen dioxide [NO2], sulfur dioxide [SO2], PM10, and 

HAPs will be estimated for compressors (including booster compressors, field compressors, and pipeline 

compressors), other equipment, road traffic, and road-maintenance activities. Emission estimates for 

HAPs will be made for benzene, n-hexane, toluene, ethylbenzene, xylene, and formaldehyde. Where not 

directly provided, the HAP emission rates will be developed from the emission rates for NOX and adjusted 

by an emission rate factor. 

Emission rates will be computed on the basis of the emission factors and the anticipated level of 

operational activities (number of projected wells, load factors, and hours of operation per year). The 

emissions for compressors will be estimated for short- and long-term modeling analyses, assuming that 

compressor engines will be operating continuously at load factors of 100 percent for short-term and 70 

percent for long-term. Although emissions from some minor sources, such as CBNG development, may 

be temporary at specific sites, the emissions estimate will include an expected level of such activity (and 

emissions) for the base year and for predicted scenarios. State air permitting agencies will be contacted 

for updated emission rates as needed in this analysis. 

Emissions of road dust from vehicles traveling on access roads will be estimated by using the USEPA 

unpaved road emission factor equation (USEPA 2003a), the work done by the WRAP on fugitive road 

dust emissions, and anticipated volume of project traffic. Fugitive dust emissions from access-road 

maintenance activities will be estimated on the basis of the USEPA emissions for construction activity 

(USEPA 2000a) and the anticipated level of road-maintenance activity. 

SEIS Dispersion Modeling Protocol 16 BLM Miles City 
4.1.2 Other Sources 

An updated emissions inventory database for both the new base year and for any predicted scenario 

year modeling will be prepared. The emissions inventory database from the ENSR model will be revised 

as necessary to update it to the 2004 base year, any recent new source additions, and to remove any 

duplication with other inventory sources. Further, the list of 67 additional emission sources identified in 

the lawsuit filed following a review of the Argonne Study will be included where actual emissions data can 

be determined and where emission sources are located within the modeling domain. As described in 

Section 4.1.1, emissions inventory data (including stack parameters) for proposed sources will be 

prepared on the basis of the current engineering design estimates. 

Emissions inventory data for sources projected to be in operation in a future year(s) will be obtained from 

state environmental departments and/or from appropriate project EISs. Only sources with state-approved 

air permit applications will be included. These data sets will be reviewed to ensure that no source is 

counted more than once. 

Any revision or updating of data in the existing Argonne or ENSR emissions inventory databases that 

becomes necessary because of changes in design or operation (including facility shutdowns), or because 

more appropriate emission factors have become available, will be performed. 

4.2 Meteorological Data 

Hourly three-dimensional meteorological data fields for three years (2001, 2002, and 2003) will be used 

in this analysis. The meteorological database will be developed using a 4- by 4-km grid resolution. This 

modeling analysis will examine all three individual year data sets. As determined in the baseline year 

modeling, the meteorological year resulting in the highest impacts of PM10, visibility, and NOX (in that 

priority) will be selected as the meteorological data for use in this study. 

CALMET, one of the three main components of the CALPUFF modeling system, includes a diagnostic 

wind model that combines surface and upper-air meteorological data with diagnostic effects of terrain and 

other factors in order to generate three-dimensional wind fields (Scire et al. 2000b). It also includes other 

interpolation algorithms that generate three-dimensional temperature, pressure, and other meteorological 

variables and two-dimensional precipitation fields. For areas with complex terrain and sparse wind 

observations, a diagnostic wind model cannot accurately depict the complex flow fields by using surface 

observation data alone. In those situations, CALMET defines the synoptic-scale flow features by using 

the output from a coarse grid (12- or 36-km) resolution simulation of a prognostic meteorological model 

(e.g., Penn State/NCAR MM5 and then better characterizes the local wind variations at a finer scale (e.g., 

4 km) by using its diagnostic wind algorithms and local surface observations. 

The Step 1 wind field for the project domain will be developed by using three years of MM5 data 

available at 36-km resolution for 2001 and 2003 and at 12-km resolution for 2002 combined with 4-km 

terrain and landuse data as depicted throughout the modeling domain. The terrain and landuse data will 

SEIS Dispersion Modeling Protocol 17 BLM Miles City 
be developed from USGS 1:250,000 DEM and 1:250,000 Composite Theme Grid (CTG) files. Additional 

surface and upper-air meteorological data collected from sites in the modeling domain will be used in the 

production of the Step 2 wind field. Precipitation data and other meteorological input data (i.e. hourly 

CASTNET meteorological data) will then incorporated into the final output of CALMET that will be used to 

drive the CALPUFF model. Figure 4-1 depicts the location of the meteorological data sources used as 

input data to the CALMET model . 

Table 4-1 presents the preliminary user-defined parameters that define the CALMET domain and the 

weighting values to be used in developing the CALMET fields. These input parameters may be changed 

during the course of the modeling. Any input parameter changes will be identified and justified in the 

report. 

Table 4-1 Preliminary CALMET User-defined Fields Not Specified in IWAQM Appendix A 

Variable Description Value 

NX Number of east-west grid cells 210 

NY Number of north-south grid cells 180 

DGRIDKM Meteorology grid spacing (km) 4 

NZ Number of vertical layers of input meteorology 12 

ZFACE Vertical cell face heights (meters [m]) 0.,20.,40.,80.,120.,180.,260.,400. 

,600.,800.,1200.,2000.,3000. 

IEXTRP Extrapolation of surface winds to upper layers -4 

RMAX1 Maximum surface over-land extrapolation radius (km) 20 

RMAX2 Maximum aloft over-land extrapolation radius (km) 50 

RMAX3 Maximum over-water extrapolation radius (km) 500 

TERRAD Radius of influence of terrain features (km) 10 

R1 Relative weight at surface of Step 1 field and 

observations 

10 

R2 Relative weight aloft of Step 1 field and observations 25 

IPROG Gridded initial prognostic wind field – MM5 data 14 

RMIN Minimum radius of influence for wind field 

interpolation 0.1 

IKINE Wind field representations OFF 

4.3 Ambient Air Quality and AQRV Data 

The existing ambient air quality levels, visibility, wet nitrogen (N) and sulfur (S) deposition, and lake 

chemistry parameters in and around the study area are described in several recently published EISs for 

proposed activities in the modeling domain (e.g., BLM 1999; EIC 2000). The most recent, available, and 

representative ambient concentrations of criteria pollutants monitored within the project area will be used 

to define background air quality levels for this study. 

SEIS Dispersion Modeling Protocol 18 BLM Miles City 
Figure 4-1 Location of Meteorological Data Stations 

SEIS Dispersion Modeling Protocol 19 BLM Miles City 
The background data will be used in the current study to establish total impacts for criteria pollutants 

based on the long-term (annual average) and short-term (24-hour and less) maximum (or H2H) 

concentrations consistent with applicable standards for the region. These data will also be utilized for 

comparison with baseline modeled impacts. 

The data selected for use in this analysis are further described in the following sections. Additional data 

on ambient air quality, visibility, and atmospheric deposition that have become available since the 

preparation of the PRBO&G EIS will be obtained and evaluated. 

4.3.1 Criteria Pollutants 

For the 2004 base year, the analysis will compare modeled concentrations to the most recent monitored 

data available. The technical analysis will be based upon monitored air quality data, actual emissions 

estimates, or estimates of actual data for 2004. Every attempt will be made to include the most recent, 

accurate, and site-specific data in this analysis. 

A new NAAQS for PM2.5 was promulgated by the EPA on July 18, 1997. As both permitted and actual 

data is not always available for this pollutant, this study proposes to use a ratio of PM10 to PM2.5 to 

supplement any missing PM2.5 emissions data. This ratio will be based upon the nearest available 

monitored data that exists for both pollutants. 

4.3.2 Chemical Species 

For use in the empirical chemical transformation algorithm of the CALPUFF model, concurrent hourly 

ozone data from representative EPA Airs and CASTNET monitoring sites within the modeling domain will 

be used to create a time and spatially varying ozone database to be used as input to CALPUFF. In the 

absence of hourly data, a regional representative background ozone concentration value will be used. 

This value will be calculated based on monthly averages of all available representative hourly data within 

the modeling domain. Some of those ozone monitoring sites include Yellowstone National Park; 

Pinedale, Wyoming; Centennial, Wyoming; and Theodore Roosevelt National Park. Data from the 

WDEQ’s ozone monitoring site at Thunder Basin and other WDEQ ozone monitoring sites, if available, 

will also be considered in developing the hourly database file and the monthly background ozone values 

to be used in the model. 

This study will use an NH3 background concentration of 5 ppb. The use of this value is consistent with 

the Coal Study and is more conservative than the 2 ppb value suggested by the North Dakota 

Department of Health for BART modeling assessments. Valid new data from within the modeling domain 

will be included in defining the background ambient air quality and AQRV levels for this analysis. 

SEIS Dispersion Modeling Protocol 20 BLM Miles City 
5.0 ASSESSMENT AND REPORTING OF AIR QUALITY IMPACTS 

To evaluate the significance of predicted air quality impacts, the results of air quality modeling and postprocessing will be compared with applicable standards and criteria and reported as described in the 

following subsections. As noted in Section 3, modeled results must be interpreted in consideration of all 

applicable limitations. Modeled results should be used in concert with other data to further identify 

concerns or propose further investigations. 

5.1 Prevention of Significant Deterioration of Air Quality 

The potential air quality concentration impacts predicted at the Class I and Class II areas that result from 

the contributions from identified sources will be compared with the allowable increments under the PSD 

air quality regulation. This comparison to the PSD Class I and II increments does not represent a 

regulatory PSD increment consumption analysis. 

The allowable PSD increments for Class I and Class II areas are given in Table 5-1. 

Table 5-1 PSD Increments for Class I and Class II Areas 

PSD Class Pollutant 

Allowable Increment (μg/m3) 

Annual Arithmetic Mean 24-hour Maximum 3-hour Maximum 

Class I NO2 2.5 - -

SO2 2 5 25 

PM10 4 8 -

Class II NO2 25 - -

SO2 20 91 512 

PM10 17 30 -

This study will investigate and report on the current status of formal PSD Increment consumption studies 

affecting the project area. Protection of the PSD Class I areas is the sole responsibility of the states, 

under USEPA oversight. This will not be a formal increment consumption study, rather it will be a 

reporting of such studies both historical and on-going. Due to implementation of the Regional Haze 

BART rule, there will likely be large reductions in PSD increment consumption. The mandated emission 

reductions of SO2, NOx, and PM10 associated with this rule will be implemented in the 2013-2015 time 

frame, which is generally consistent with the time period of interest on this study of CBNG development. 

Due to these pending emission reductions and other on-going increment studies within the modeling 

domain, this study will not include a PSD increment consumption analysis. Results of the investigation 

into the status of on-going PSD increment studies will be included in the project report. 

SEIS Dispersion Modeling Protocol 21 BLM Miles City 
5.2 Ambient Air Quality 

5.2.1 Criteria Pollutants 

The total potential concentrations (source criteria pollutant concentrations plus ambient background 

values) will be estimated at project area receptors and compared with applicable health- and welfarerelated NAAQS and SAAQS. 

The NAAQS and SAAQS for the states, parts of which are located within the modeling domain (Figure 1­

1) are established for NO2, SO2, PM10, PM2.5, O3, CO, and lead (Pb). Given the insignificant levels of 

potential volatile organic compounds and Pb emissions from project sources, neither the O3 nor the Pb 

standard will be addressed in this analysis. 

All modeled result comparisons will be presented in tabular form and contoured plots in the project report. 

Where possible and for pollutants whose modeled impact is near or above a national or state standard, 

the report will present the modeled results as contoured plots that depict not only the maximum impact 

but also the spatial extent of the pollutant’s impact. 

New NAAQS for O3 and PM2.5 were promulgated by the USEPA on February 27, 2001. The procedures 

for implementing these standards have been established by USEPA. However, the states are still in the 

process of determining how to implement them. There are no non-attainment areas for ozone or for PM2.5 

within the modeling domain. The existing PM10 standard remains applicable throughout the United States 

(U.S.), including the states within the modeling domain, and will be used for comparison and to maintain 

consistency with the original PRBO&G EIS. The NAAQS addressed in this study are listed in Table 5-2. 

A comprehensive list of the AAQS for each state in the modeling domain, and how they compare to the 

NAAQS, is presented in Appendix B. 

Table 5-2 Applicable Ambient Air Quality Standards 

 Annual

2 24-Hour3 8-Hour3 3-Hour3 1-Hour3 

Pollutant (μg/m3) (ppmv) (μg/m3) (ppmv) (μg/m3) (ppmv) (μg/m3) (ppmv) (μg/m3) (ppmv) 

NO2 100 0.05 565 0.304 

SO2 60 0.024,5 260 0.104,5 1,300 0.50 1,300 0.504 

PM10 506 1507 --- 

PM2.5 156 358 --- 

CO 

10,000 9 26,000 

40,000 

234 

35 

ppmv=parts per million, by volume 

1 

NAAQS unless otherwise noted. 2 

Annual arithmetic mean not to be exceeded, unless otherwise noted. 3

 Not to be exceeded more than once per year, unless otherwise noted. 4 

Montana SAAQS (more stringent than NAAQS). 5 

Wyoming SAAQS (more stringent than NAAQS). 6 

Expected annual arithmetic mean averaged over a 3-year period. 7 th

 Annual 99 percentile concentration averaged over a 3-year period 8 th

 Annual 98 percentile concentration averaged over a 3-year period. 

SEIS Dispersion Modeling Protocol 22 BLM Miles City 
5.2.2 Hazardous Air Pollutants 

The study will assess emissions of critical hazardous air pollutants that were modeled in the earlier 

Argonne and ENSR Studies. These include benzene, ethyl benzene, formaldehyde, n-hexane, toluene 

and xylene. Emissions of these HAPs from oil and gas operations will be made based on the emission 

rate of nitrogen oxides and a comparative emission rate using AP-42 factors. 

The study will model both 1-hour and annual impacts of hazardous air pollutants in the project area. 

Since the greatest modeled HAPs impacts are expected to occur at the near-field receptors, only those 

receptors and the Northern Cheyenne and Crow Indian Reservations will be analyzed in this study. 

Results of the 1-hour modeled impacts for benzene, ethyl benzene, formaldehyde, n-hexane, toluene and 

xylene will be compared to the Reference Exposure Levels (RELs) (EPA 2005). Impacts for chronic and 

carcinogenic risks will be analyzed on the same grid for the same HAPs. Results will also be compared 

to the non-carcinogenic Reference Concentrations for Chronic Inhalation Exposure (RfCs) and the 

carcinogenic risk assessment will be provided for those HAPs with a carcinogenic risk factor (benzene 

and formaldehyde). 

Since neither the EPA nor the states in the project area have established ambient HAP standards, the 

above assessments will be provided for information purposes only. 

5.3 Air Quality Related Values 

5.3.1 Visibility 

Estimated maximum visibility degradation at the Class I areas and specified Class II areas of concern 

due to the contributions from the modeled sources will be processed to obtain visibility impairment in 

terms of a change in percent extinction or dv. The predicted visibility impairment will be compared with 

the threshold (10 percent of the reference background visibility, or 1.0 dv, for the impairment attributable 

to the cumulative sources). A comparison to 5 percent impact (0.5 dv) will also be included in the project 

report. 

Two separate post-processing visibility analyses will be used to depict the baseline impact and the 

projected impact at the Class I areas and specified Class II areas of concern. The first method is the 

standard “FLAG method” (Method 2), as proposed by FLAG (2000). The “FLAG” method will use two 

slight refinements: (1) RHMAX will be set equal to 95 in CALPOST as opposed to 98 and (2) the EPA 

f(RH) values will be used as opposed to the FLAG f(RH) values. In recent Method 2 applications the 

FLM has accepted these two modifications. The second method (Method 6) is more widely implemented 

for visibility analyses under EPA’s BART guideline and is consistent with the same approach that is 

applied to visibility analyses under the final regional haze rule. 

Method 2 will use FLAG recommended speciated monthly hygroscopic and non-hygroscopic 

SEIS Dispersion Modeling Protocol 23 BLM Miles City 
concentrations that are used to describe the background air quality for each Class I area. Method 2 uses 

hourly relative humidity from the CALMET files to determine the hourly f(RH) value. These hourly f(RH) 

values are used to increase the scattering efficiency of the hygroscopic component (i.e. ammonium 

sulfate and/or nitrate) of the background speciated monthly concentrations and thus generate monthly 

background extinction values for each Class I area. The same procedure is used to calculate the hourly 

modeled extinction values that correspond to the hourly modeled CALPUFF concentrations and the same 

hourly f(RH) values. CALPOST then calculates each day’s 24-hour average maximum percent change in 

extinction and change in deciviews over all the receptors for each Class I area. 

Method 2 has established a recommended procedure for identifying and evaluating potential visibility 

impairment primarily in mandatory federal Class I Areas. According to the FLAG procedure, predicted 

changes in visibility in terms of percent change in extinction (or change in deciviews [dv]; a 10 percent 

change in extinction corresponds to 1.0 dv) due to emissions from proposed sources would be computed, 

and compared to FLAG specified seasonal natural background reference visibility levels, and the 

resulting percent change in extinction (or change in dv) would be compared with FLAG-prescribed 

threshold levels for impact assessment. Estimated natural background visibility reference levels and 

associated parameter values will be taken from the FLAG document. 

Method 6 will also use FLAG recommended speciated monthly hygroscopic and non-hygroscopic 

concentrations that are used to describe the background air quality for each Class I area. Unlike Method 

2 however, Method 6 takes monthly site specific monthly f(RH) values. These monthly f(RH) values are 

used to in the same manner as the hourly f(RH) values used for Method 2. Site-specific, monthly relative 

humidity adjustment factors will be taken from Table A-3 in Appendix A in the “Guidance for Tracking 

Progress Under the Regional Haze Rule” document. This method is consistent with EPA’s methodology 

in modeling of BART-eligible sources. For the BART Method 6 approach, the top 2% (7 days each year) 

are discarded as being outlier days and the 98th percentile predicted visibility extinction impact is used as 

indicative of a source's effects on visibility in Class I areas. 

This study will provide an analysis of both Methods 2 and 6 as described above. For Method 2, results 

will be presented in terms of number of days when modeled percent change in extinction is greater than 

both 5 and 10 percent, along with the maximum modeled change in extinction for each year and Class I 

and Class II area of concern. For Method 6, results will be presented in terms of number of days when 

modeled change in deciviews is greater than both 0.5 and 1.0 deciviews, along with the maximum 

modeled and 8th highest change in deciviews for each year and Class I and Class II area of concern. 

5.3.2 Acidic Deposition and Lake Chemistry 

Estimated annual wet, dry, and total (wet plus dry) deposition fluxes of total sulfur and nitrogen 

compounds due to the contributions from the modeled sources, will be used to estimate the total sulfur 

and nitrogen deposition fluxes at the following lakes: 

SEIS Dispersion Modeling Protocol 24 BLM Miles City 
• Black Joe Lake, Class I Bridger Wilderness Area; 

• Deep Lake, Class I Bridger Wilderness Area; 

• Hobbs Lake, Class I Bridger Wilderness Area; 

• Upper Frozen Lake, Class I Bridger Wilderness Area; 

• Florence Lake, Class II Cloud Peak Wilderness Area; 

• Emerald Lake, Class II Cloud Peak Wilderness Area; 

• Ross Lake, Class I Fitzpatrick Wilderness Area; and 

• Lower Saddlebag Lake, Class II Popo Agie Wilderness Area. 

The study will perform an additional analysis in terms of the acid neutralizing capacity (ANC) for each of 

these lakes. An estimation of potential changes in ANC at several specified sensitive lake receptors will 

be made by following the procedure developed by the USFS Rocky Mountain Region (2000). The 

POSTUTIL program will be used to sum all wet and dry fluxes of SO2, SO4, NO3, HNO3, and dry NOx. 

The total nitrogen and sulfur deposition will then be computed from the summed fluxes. Predicted 

changes in ANC will be compared with the threshold (10 percent change in ANC for lakes with 

background ANC values greater than 25 micro equivalents per liter (μeq/l), and no more than a 1 μeq/l 

change in ANC for lakes with background ANC values equal to or less than 25 μeq/l). 

All modeled acidic deposition results will be presented in tabular form or some other appropriate format in 

the project report. 

SEIS Dispersion Modeling Protocol 25 BLM Miles City 
6.0 REFERENCES 

Argonne National Laboratory (Argonne model). 2002. Technical Support Document Air Quality Impact 

Assessment for the Montana Final Statewide Oil and Gas EIS and Proposed Amendment of the 

Powder River and Billings Resource Management Plans. Bureau of Land Management Montana 

and Wyoming State Offices. December 2002. 

Bureau of Land Management (BLM). 2003. Final Statewide Oil and Gas Environmental Impact Statement 

and Proposed Amendment of the Powder River and Billings Resource Management Plans. Miles 

City Field Office and Billings Field Office. January 2003. 

.1999. Wyodak Coalbed Methane Project Draft Environmental Impact Statement. Buffalo Field 

Office. May 1999. 

. 1983. Riley Ridge Natural Gas Project Draft Environmental Impact Statement, Sublette, Lincoln 

and Sweetwater Counties, Wyoming, Cheyenne, Wyoming. 

Bullock, O.R. 1993. A Workstation Concept for the Production of Dynamically-Constrained Meteorological 

Characterization for Use in Air-Quality Modeling, a preprint to the Ninth International Conference 

on Interactive Information and Processing Systems for Meteorology, Oceanography, and 

Hydrology, January 17-22, 1993, Anaheim, California. American Meteorological Society, Boston, 

Massachusetts. pp. 9-14. 

ENSR Corporation (ENSR model). 2005. Task 1A Report for the Powder River Basin Coal Review 

Current Air Quality Conditions, prepared for Bureau of Land Management Casper Field Office, 

Wyoming State Office, and Miles City Field Office. September 2005. 

ENVIRON International Corporation (EIC). 2000. Air Quality Technical Support Document for the Powder 

River Basin Expansion Project Dakota, Minnesota, and Eastern Railway Corporation New Railway 

Retrofit Project (Preliminary Draft), prepared for Burns and McDonnell, Kansas City, Missouri. 

May 2000. 

Environmental Defense, et al vs. Norton, et al. 2004. Cause No. CV-04-64-Blgs-RWA, filed in the United 

States District Court for the District of Montana Billings Division. Billings, Montana. August 2004. 

FLAG. 2000. Federal Land Managers’ Air Quality Related Values Workgroup (FLAG) Phase I Report. 

December 2000. 

Fox, D. G., A. M. Bartuska, J. G. Byrne, E. Cowling, R. Fisher, G. E. Likens, S. E. Lindberg, 

R. A. Linthurst, J. Messer, and P. S. Nichols. 1989. A Screening Procedure to Evaluate Air 

SEIS Dispersion Modeling Protocol 26 BLM Miles City 
Pollution Effects on Class I Wilderness Areas. General Technical Report RM-168. U.S. 

Department of Agriculture, Forest Service Rocky Mountain Forest and Range Experiment Station, 

Fort Collins, Colorado. 

McVehil-Monnett Associates, Inc. 1999. Horse Creek Coal Lease Application Cumulative Air Quality 

Impact Analysis. Technical Reference Document prepared for U.S. Bureau of Land Management, 

Casper, Wyoming. December 1999. 

Scire, J. S., D. S. Strimitis, and R. J. Yamartino. 2000a. A User’s Guide for the CALPUFF Disperion 

Model (Version 5.0). Earth Tech, Inc., Concord, Massachusetts. October 1999. 

Scire, J. S., F. R. Robe, M. E. Fernau, and R. J. Yamartino. 2000b. A User’s Guide for the CALMET 

Meteorological Model (Version 5.0). Earth Tech, Inc. Concord, Massachusetts. September 1999. 

U.S. Environmental Protection Agency (USEPA). 2005. Technology Transfer Network, Air Toxics 

Website. Accessed via the Internet at http://www.epa.gov/ttn/atw. 

2003a. Compilation of Air Pollutant Emission Factors, AP-42, Fifth Edition, Volume I: Stationary 

Point and Area Sources. Section 13.2.1, Paved Roads. December 2003. 

. 2003b. Guidance for Tracking Progress under the Regional Haze Rule, EPA-454/B-03-004. 

September 2003. 

. 2000a. Compilation of Air Pollutant Emission Factors, AP-42, Fifth Edition, Volume I: Stationary 

Point and Area Sources. Accessed via the Internet at http://www.epa.gov/chief/ap42.html. July 

2000. 

. 1998. Interagency Workgroup on Air Quality Modeling (IWAQM) Phase II Summary Report: 

Recommendations for Modeling Long-Range Transport Impacts, EPA-454/R-98 

019. Research Triangle Park, North Carolina. 

U.S. Forest Service (USFS). 2000. Rocky Mountain Region. Screening Methodology for Calculating ANC 

Change to High Elevation Lakes. December 2000. 

U.S. Geological Survey (USGS). 2000a. USGS Digital Elevation Model Data. Accessed via the Internet at 

http://edcwww.cr.usgs.gov/glis/hyper/guide/usgs_dem. July 10, 2000. 

. 2000b. USGS Land Use and Land Cover Data. Accessed via the Internet at 

http://edc.usgs.gov/glis/hyper/guide/1_250_lulc. November 2, 2000. 

Wyoming Department of Environmental Quality (WDEQ). 2000. Wyoming’s Air Quality: Ambient Air 

Monitoring Data – 1999. Cheyenne, Wyoming. 

SEIS Dispersion Modeling Protocol 27 BLM Miles City 
APPENDIX A 

STATE BY STATE COMPARISON OF AMBIENT AIR QUALITY STANDARDS

SEIS Dispersion Modeling Protocol BLM Miles City 
Pollutant 

Averaging Period National ND SD NE WY UT ID 

PM10 Annual 50 μg/m3 same as 

NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

24-hour 150 μg/m3, maximum 

average concentration, no more than one exceedance per year 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

PM2.5 Annual 15 μg/m3, 3-year 

average of annual arithmetic mean 

15 ug/m**3, annual arithmetic mean 

same as NAAQS 

24-Hour 35 μg/m3, 98th 

percentile of the 24-hour values determined for each year. 3-year average of the 98th percentile values. 

35 ug/m**3, 98th percentile 24-hour average 

same as NAAQS 

SO2 Annual 0.03 ppm (80 μg/m3), 

annual arithmetic mean not to be exceeded in any calendar year. 

0.023 ppm (60 μg/m3), 

arithmetic mean 

same as NAAQS 

same as NAAQS 

60 ug/m**3, arithmetic mean 

same as NAAQS 

same as NAAQS 

24-hour 0.14 ppm (365 μg/m3), 

not to be exceeded more than once in any calendar year 

0.099 ppm (260 μg/m3), 

maximum average concentration 

same as NAAQS 

same as NAAQS 

260 ug/m**3, maximum concentration not to be eceeded more than once per year 

same as NAAQS 

same as NAAQS 

3-hour 0.5 ppm (1300 μg/m3), 

not to be exceeded more than once in any calendar year (Secondary Standard) 

0.273 ppm (715 μg/m3), 

maximum average concentration 

same as NAAQS 

same as NAAQS 

1300 ug/m**3 (0.50 ppm), maximum concentration not to be exceeded more than once per year. 

same as NAAQS 

same as NAAQS 

SEIS Dispersion Modeling Protocol 

A1 BLM Miles City 
Pollutant 

Averaging Period National ND SD NE WY UT ID 

SO2 (cont.) 

1-hour 

H2S* 3-month 0.02 ppm (28 

mg/m3), 

maximum arithmetic mean concentration 

same as NAAQS 

same as NAAQS 

same as NAAQS 

24-hour 0.10 ppm same as 

NAAQS 

same as NAAQS 

same as NAAQS 

1-hour 0.05 ppm 0.20 ppm same as 

NAAQS 

same as NAAQS 

same as NAAQS 

1/2 hour 70 ug/m**3, not 

to be exceeded more than twice per year 

1/2 hour 40 ug/m**3, not 

to be exceeded more than twice in any five consecutive days 

instantaneous 10 ppm (14 

mg/m3), 

same as NAAQS 

same as NAAQS 

same as NAAQS 

CO 8-hour 10 mg/m**3 (9 ppm), 

maximum concentration not to be exceeded more than once per year 

8 ppm (10 mg/m3), maximum concentration not to be exceeded more than once per year 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

1-hour 35 ppm (40 mg/m3), 

maximum concentration not to be exceeded more than once per year 

same as National AAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

SEIS Dispersion Modeling Protocol 

A2 BLM 
Pollutant 

Averaging Period National ND SD NE WY UT ID 

Ozone (O3)* 

8-hour 0.08 ppm (157 μg/m3), 

average of 4th highest maximum daily 8-hour average, over 3 consecutive years. 

4th highest daily maximum 8-hour average must be less than or equal to 0.08 ppm, in accordance with national standard 

same as NAAQS 

Ozone (O3)* 

1-hour 0.12 ppm (235 μg/m3), 

not to be exceeded more than once per year 

0.12 ppm (235 μg/m3), 

maximum concentration not to be exceeded more than once per year 

same as NAAQS 

same as NAAQS 

0.12 ppm (235 ug/m**3), not to be exceeded more than once per year 

same as NAAQS 

same as NAAQS 

NO2 Annual 0.053 ppm (100 

ug/m**3) Annual arithmetic mean 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

1-hour 

Lead* calendar 

quarter 

1.5 μg/m3, not to be 

exceeded in any quarter of any calendar year 

1.5 μg/m3 , maximum arithmetic mean 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

same as NAAQS 

90-day average 

* H2S, Ozone, and Lead are not being modeled for this study, and are included in this table for com

SEIS Dispersion Modeling Protocol 

A3 BLM 
APPENDIX B 

ADDITIONAL EMISSIONS SOURCES FOR CUMULATIVE ANALYSES

SEIS Dispersion Modeling Protocol BLM Miles City 
Figure B-1 (After Environmental Defense Fund letter containing scoping comments on the Supplemental EIS

SEIS Dispersion Modeling Protocol B-1 BLM Miles City 
1 

2 3 4 5 6 7 8 9 

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 

Number In 

Figure B-1 Facility Name 

NOX 

(TPY) 

PM10 

(TPY) 

SO2 

(TPY) 

Aldila Corp 81.73 14.49 3.71 Black Butte Coal Co_ Black Butte Mine U2 2,627 U2 

Blue Mountain Energy - Deserado Mine NA3 NA3 NA3 

Bridger Coal Company - Jim Bridger Mine 208 664 12 

Bonanza Power Plant 5,700 138 1,135 

Church & Dwight Company Incorporated 5.1 99.3 U2 

Coal Creek Station 12,862 1,992 49,743 

Colstrip Power Plant 827 32.4 1,262 

Clear Creek Storage 43 U2

 U

2 

Colorado Interstate Co Laramie Comp Stn 31 U2

 U

2 

Colorado Interstate Gas Rawlins Comp 817 U2

 U

2 

Connell Resources Inc Camilletti Pit U2

 U

2 1.8 

DOE BLM 1.7 U2 24 D.G. Huskins Construction Co. CT-1229 9 12.9 0.2 D.G. Huskins Construction Co. CT-1230 32.4 23.7 59.6 

Elam Const Incorporated Davenport Pit U2

 U

2 1.72 

Exxon - Shute Creek I 109 U2 1,447 

FMC Wyoming Corp _ Soda Ash Plant 1,095 168 265 Frontier Refining Incorporated 390 220 1,409 General Chemical Soda Ash Plant 3,608 1,035 4,761 

Great River Energy Stanton Station 3,172 137 9,784 

Holly Sugar Corporation 98.2 224 213 

Jonah Gas Gathering CT-1422 40.6 U2

 U

2 

Jonah Gas Gathering CT-1423 60.4 U2

 U

2 

SEIS Dispersion Modeling Protocol B-2 BLM Miles City 
Number In NOX PM10 SO2 

Figure B-1 Facility Name (TPY) (TPY) (TPY) 

25 Kern River Gas Trans. _ Muddy Creek 62.6 U2

 U

2 

26 Kn Energy Inc - Sand Draw Station 36.5 U2

 U

2 

27 Leland Olds Power Plant 12,955 491 50,107 28 Louisiana Land & Explor._lost Cabin 7.8 U2 1,383 29 Louisiana Pacific Carbon CT-1122 BLM 28.7 U2

 U

2 

30 Milton R Young Station 22,098 550 41,344 31 Mountain Cement Co, CT-1137 636.4 30.7 72.3 32 Northwest Pipeline 790 3.17 1.86 33 Presidio Oil CT-1128 BLM 33.9 U2

 U

2 

34 Questar Gas Mgmt Company Pwfc Northside 1 4.14 U2

 U

2 

35 Questar Gas Mgmt Co Pwfc Southside 2 38.5 0.1 U2 36 Questar Gas Mangement- CT-1295 BLM 99.85 U2

 U

2 

37 R.M. Heskett Station Omitted6 Omitted6 Omitted6 38 S F Phosphates, Inc. 68.4 28.2 1,460 39 Solvay Minerals, Inc 1,376 194 89.7 40 South And Jones BLM 1.6 94 U2 41 SRTV BLM 2.48 2.79 U2 42 Tri State Generation Craig Power Plant 16,761 378 10,662 43 Twentymile Coal Co U2 364 U2 44 TotalFinaELF's TG Soda Ash BLM 173 26.2 U2 45 Umetco Minerals Corporation U2 22.4 U2 46 Western Gas Resources Inc Sand Wash Station U2

 U

2

 U

2 

47 Western Mobile Northern Steamboat S Pit U2 23.05 U2 48 Williams Field Service - Permit CT-1306 31.89 U2

 U

2 

SEIS Dispersion Modeling Protocol B-3 BLM Miles City 
Number In 

Figure B-1 Facility Name 

NOX 

(TPY) 

PM10 

(TPY) 

SO2 

(TPY) 

49 Williams Field Services (CT 1177) 32.86 U2

 U

2 

50 Williams Field Svcs_Opal Plant 882 U2

 U

2 

51 Williams Field Services _ Echo Springs 195 U2

 U

2 

52 Wyoming Lime Producers 249 77.2 3.7 53 Atlantic Rim CBM Project NA3 NA3 NA3 54 Bitter Creek Pipeline’s Symons Central Compressor NA3 NA3 NA3 55 Bitter Creek Pipeline’s Consul 27 Compressor NA3 NA3 NA3 56 Basin Creek 100 MW power plant NA3 NA3 NA3 57 Glacier International’s 160 MW power plant NA3 NA3 NA3 58 

Great Northern/Kiewit’s 500 MW Eastern Montana coal-fired power plant NA3 NA3 NA3 

59 Natrona County International Airport 0.7 22.8 0.2 60 Nelson Refining System’s 73.6 4.4 60.2 61 Two new coal mines planned for Otter Creek NA3 NA3 NA3 62 Puron Corporation’s Coal Conversion Plant NA3 NA3 NA3 63 Seneca Coal Company’s Seneca II mine NA3 50 NA3 64 Texaco USA’s Stagecoach Draw Oil and Gas 16.13 U2

 U

2 

65 Tongue River Railroad NA3 NA3 NA3 66 Union Pacific Resource’s Champlin Gas Plant 200.73 U2

 U

2 

67 Wold Trona Company’s Soda Ash plant 155 111 33.3 

?? Question Marks as shown on this table are from the original EDF scoping comment letter. SEIS Dispersion Modeling Protocol B-4 BLM Miles City 
Note 

1. Facilities identified by BLM in the emission inventory of the “Desolation Flats Natural Gas Exploration and Develo

Technical Support Documents for Ambient Air Quality Impacts Analysis,” Rawlings and Rock Springs Field Offices, 2003), and also within 300 km of one or more of the 15 Class I areas listed by BLM as affected by emissions from the 

Project. See Plaintiffs' Exhibits V-1 (Desolation Flats DEIS, Chp 4) and V-2 ("Technical Support Document," Append

Sources). 2. U means unreported on EPA's AIRS website. 3. NA means not available. 4. Facilities and emissions reported by EPA in the US EPA's AIRS Data website at <http://www.epa.gov/air/data/>. Oclick on "Reports and Maps," then "Select geographic area," then in the "Select a state" section, click on "Montana," ostate. Click "Go." Then click on "Facility Emissions." Select "NOx", "PM10" or "SO2" under "Pollutant Emitted". 5. Reasonably Foreseeable Future Sources as idenitified by BLM in proposed RMP. 66 Fed. Reg. 33975 (June 26, 200

Exhibit W. 6. Emissions for the Heskett Station are omitted because source is more than 300 KM from a Class I Area. 7. Facilities identified by Montana BLM in the emission inventory of the "Air Quality Technical Report, Badger Hills Assessment," Miles City District Office, at 31 (February 2004) as within the 300 km zone of impact of the air pollution more of the Class I areas listed in the Plaintiffs' Amended Complaint. See id., at 5. BLM evaluated these sources for inSee id., at 24. See Plaintiffs' Exhibit X. 8. Facilities identified by WY DEQ as permitted after the baseline dates for PM10, SO2, and NOx, as noted in the May Report, 37 NSR Report,” Air Quality Division, Wyoming Department of Environmental Quality (Attached to May 19Olson, Wyoming DEQ, to Dan Heilig, Executive Director, Wyoming Outdoor Council). See Plaintiffs' Exhibit T. 9. Facilities identified as reasonably foreseeable future sources in BLM’s Montana “Statewide Draft Oil and Gas EnvirStatement and Amendment of the Powder River and Billings Resource Management Plans,” at MIN-33 (January 2002Doc. 1. 

SEIS Dispersion Modeling Protocol B-5 BLM Miles City