North Dakota State Implementation Plan 

for 

Regional Haze 

A Plan for Implementing the Regional Haze Program Requirements 

of 

Section 308 of 40 CFR Part 51, Subpart P - Protection of Visibility

North Dakota Department of Health 

Adopted: February 24, 2010 

Division of Air Quality 

Air Pollution Control Program 

North Dakota Department of Health 

918 East Divide Avenue 

Bismarck, North Dakota 58501-1947 

Telephone 701-328-5188 

Terry Dwelle, M.D., M.P.H.T.M. 

State Health Officer 

Terry O’Clair, P.E. 

Director 

 
APPROVAL PAGE 


North Dakota State Implementation Plan for Regional Haze 


North Dakota Department of Health, Environmental Health Section, Division of 

Air Quality. 

Approval by the following North Dakota Department of Health Management 

Personnel: 

L. David Glatt, E., 

Environmental Hea 

Date 

i Date 

Adopted for the North Dakota Department of Health 

Terry e, M.D., M.P.H.T.M. Date 

Sta· Health Officer 

North Dakota Department ofHealth 

11 
iii 

Table of Contents 

 Page No.

Approval Page 

i Governor’s Submittal Letter 1 

ii Executive Summary 2 

1. Purpose/Legal Authority 3 

2. Overview 4 

 2.1 Introduction 4 

 2.2 Visibility Impairment 8 

 2.3 Description of North Dakota’s Class I Areas 8 

 2.4 Class I Areas in Other States Impacted by North Dakota Sources 9 

 2.5 Programs to Address Visibility Impairment 11 

 2.6 Reasonable Progress Toward the 2064 Visibility Goals 14 

3. Plan Development and Consultation 16 

 3.1 Consultation with Federal Land Managers (FLM) 16 

 3.1.1 FLM Comments Provided During 60 Day Comment Period 16 

 3.1.2 Response to FLM Comments 16 

 3.1.3 FLM Comments Provided on BART Portion of SIP in 2008 16 

 3.2 Consultation with EPA 17 

 3.3 Consultation with Other States 17 

 3.4 Regional Planning Consultation 18 

 3.5 Consultation with Tribes 18 

 3.6 Other Consultation 18 

4. Monitoring Strategy and Other Implementation Plan Requirements 19 

 4.1 RAVI Monitoring Strategy in Current North Dakota Long Term Strategy 19 

 4.2 Regional Haze Visibility Impairment Monitoring Strategy and Other 20 

 Implementation Plan Requirements 

 4.3 Overview of the IMPROVE Monitoring Network 25 

5. Baseline and Natural Visibility Conditions and Uniform Rate of Progress for 30 

 North Dakota Class I Areas 

 5.1 The Deciview 30 

 5.2 Baseline Visibility Conditions 30 

 5.3 Natural Visibility Conditions 33 

 5.4 Uniform Rate of Progress 35 

6. Sources of Visibility Impairment in North Dakota Class I Areas 38 

 6.1 Introduction 38 

 6.2 Emissions in North Dakota 38 

 6.3 Emissions from Other States and Canadian Provinces 42 
iv 

 Page

7. Best Available Retrofit Technology (BART) 56 

 7.1 Introduction 56 

7.1.1 Overview of Paragraph 51.308(e) of the Federal Regional Haze 56 

 Regulation - Best Available Retrofit Technology (BART) 

 Requirements for Regional Haze Visibility Impairment 

 7.1.2 Visibility-Impairing Pollutants of Concern 58 

 7.1.3 BART Identification Process 59 

 7.1.4 CALPUFF Screening Model Protocol 62 

 7.1.5 Screening Impact Threshold 62 

 7.2 BART-Eligible Sources in North Dakota 63 

 7.3 Determination of BART-Eligible Sources Subject to BART 65 

 7.3.1 Sources Subject to BART 65 

 7.3.2 Exclusion of Tesoro Mandan Petroleum Refinery 67 

 7.3.3 Exclusion of American Crystal Sugar Drayton Refinery 67 

7.3.4 Exclusion of Montana Dakota Utilities Heskett Unit No. 2 67 

 7.4 Determination of BART Requirements for Subject-to-BART Sources 68 

 7.4.1 Company BART Analyses 68 

 7.4.2 Department BART Determinations 69 

 7.4.3 Summary of Emission Reductions 77 

 7.5 Air Pollution Control Permits to Construct for Subject-to-BART Sources 77 

 7.5.1 Enforceable Emission Limits 78 

 7.5.2 Monitoring, Recordkeeping, and Reporting Requirements 78 

 7.5.3 Operating and Maintenance Requirements 79 

 7.5.4 Compliance Date 79 

8. Visibility Modeling 80 

 8.1 Introduction 80 

 8.2 Regional Haze Metrics 83 

 8.3 Projection of Future Visibility 86 

 8.4 WRAP Visibility Modeling Methodology 88 

 8.5 NDDoH Visibility Modeling Methodology 90 

 8.5.1 Hybrid Modeling System 95 

 8.5.2 CALMET Input 96 

 8.5.2.1 Meteorological Data 98 

 8.5.2.2 Geophysical Data 102 

 8.5.2.3 CALMET Control File settings 102 

 8.5.3 CALPUFF Input 103 

 8.5.3.1 Emissions Inventory 106 

 8.5.3.2 Boundary Conditions 110 

 8.5.3.3 Ozone Background 111 

 8.5.3.4 Ammonia Background 111 

 8.5.3.5 Receptors 112 

 8.5.3.6 CALPUFF Control File Settings 113 

 8.5.4 POSTUTIL Input 116 

 8.5.5 CALHAZE 118 

 8.5.6 Hybrid System Used to Adjust WRAP CMAQ Modeling Results 121 
v 

 Page

8.6 Modeling Process and Results 128 

 8.6.1 Hybrid CMAQ-CALPUFF Performance Evaluation 128 

 8.6.2 Results for Default EPA Methodology 135 

 8.6.2.1 Cumulative Results 135 

 8.6.2.2 Apportionment by Species 139 

 8.6.2.3 Apportionment by Source Group 147 

 8.6.2.4 Apportionment by Source Region 153 

 8.6.2.5 Conclusions 156 

 8.6.3 Weight of Evidence Options 157 

 8.6.3.1 Discounting the Impact of Canadian Source 158 

 Emissions 

 8.6.3.2 Discounting the Impact of All Sources Located 162 

 Outside of North Dakota 

 8.6.3.3 Use Default EPA Methodology with Zero North 164 

 Dakota Future Emissions 

 8.6.3.4 Base 20% Worst Days on Modeling Results Rather 167 

 Than IMPROVE Monitoring Data 

 8.6.3.5 Weight of Evidence Summary and Conclusions 168 

9. Reasonable Progress Goals 172 

 9.1 Introduction 173 

 9.2 Establish Baseline and Natural Conditions 173 

 9.3 Determine the Glide Path or Uniform Rate of Progress 173 

 9.4 Identify and Analyze the Measures Aimed at Achieving the 173 

 Uniform Rate of Progress 

 9.5 Additional Controls 177 

 9.5.1 Point Sources Contributing to Visibility Impairment in the 177 

 North Dakota Class I Areas 

 9.5.2 Agricultural Tillage Operations 188 

 9.5.3 Smoke Management for Agricultural, Forest Management 190 

 and Prescribed Burning 

 9.5.4 Reserved 190 

 9.5.5 Oil and Gas Exploration and Production 190 

 9.6 Visibility Modeling and Weight of Evidence 192 

 9.7 Establish Reasonable Progress Goals 195 

10. Long-Term Strategy 198 

 10.1 Long-Term Strategy Requirements 198 

 10.2 Consultation With Other States 198 

10.3 Demonstration of Inclusion of Measures to Obtain RPGs 199 

 Established for Class I Areas 

10.4 Documentation of the Technical Basis for Modeling, 199 

 Monitoring and Emissions Information 

10.5 Identification of Anthropogenic Sources of Visibility Impairment 200 

 
vi 

 Page

10.6 Seven Factors That Must be Considered in Developing the LTS 200 

 10.6.1 Emission Reductions Due to Ongoing Air Pollution 201 

 Control Programs 

 10.6.2 Measures to Mitigate the Impacts of Construction 202 

 Activities 

 10.6.3 Emission Limitations and Schedules for Compliance 205 

 10.6.4 Source Retirement and Replacement Schedules 205 

 10.6.5 Smoke Management Techniques for Agriculture and 205 

 Forest Management 

 10.6.6 Enforceability of Emission Limitations and Control 207 

 Measures 

10.6.7 The Anticipated Net Effect on Visibility Due to Projected 207 

 Changes in Point, Area and Mobile Source Emissions

10.7 Prevention of Significant Deterioration 208 

11. Commitment to Consultation, Progress Reports, Periodic Evaluations of 209 

 Plan Adequacy, and Future SIP Revisions 

 11.1 Future Consultation Commitments 209 

 11.1.1 FLM Consultation and Coordination 209 

 11.1.2 Tribal Consultation 210 

 11.1.3 Interstate Consultation and Coordination 210 

 11.2 Commitment to Progress Reports 211 

 11.3 Determination of Current Plan Adequacy 212 

 11.4 Commitment to Future SIP Revisions 213 

 11.5 Monitoring Strategy 214 

 11.6 Rules for Non-BART Point and Area Sources 215 

12. Public Participation and Review Process 216 

 12.1 Summary of Comments Received during Public Comment 216 

 Period/Hearing 

 12.2 Response to Public Comments 216 

 12.3 Revisions to the State Implementation Plan 216 

 12.4 Revisions to the BART Air Pollution Control Permits to Construct 217
vii 

List of Appendices 

Appendix A. BART Modeling Protocols and Analyses 

A.1 Protocol for BART-Related Visibility Impairment Modeling Analyses in North 

Dakota 

A.2 Montana-Dakota Utilities Heskett Station Unit 2

A.3 Notification of Subject-to-BART Letters to BART-Eligible Sources 

A.4 Coyote Station Permit to Construct 

A.5 WRAP Methodology for Determining Baseline Visibility Conditions 

Appendix B. Department BART Determinations for Subject-to-BART Sources in North Dakota 

B.1 Basin Electric Power Cooperative Leland Olds Station Units 1 and 2 

B.2 Great River Energy Coal Creek Station Units 1 and 2 

 

B.3 Great River Energy Stanton Station Unit 1 

B.4 Minnkota Power Cooperative Milton R. Young Station Units 1 and 2 

B.5 Best Available Retrofit Technology Selective Catalytic Reduction Technical 

Feasibility Analysis for North Dakota Lignite 

B.6 Selective Catalytic Reduction (SCR) Technical Feasibility for M.R. Young 

Station 

Appendix C. Company BART Analyses and Supporting Information 

C.1 Basin Electric Power Cooperative Leland Olds Station Units 1 and 2 

C.2 Great River Energy Coal Creek Station Units 1 and 2 

C.3 Great River Energy Stanton Station Unit 1 

 

C.4 Minnkota Power Cooperative Milton R. Young Station Units 1 and 2 

Appendix D. Air Pollution Control Permit to Construct for the Subject-to-BART Sources 

D.1 Basin Electric Power Cooperative Leland Olds Station Units 1 and 2 

D.2 Great River Energy Coal Creek Station Units 1 and 2 
viii 

D.3 Great River Energy Stanton Station Unit 1 

D.4 Minnkota Power Cooperative Milton R. Young Station Units 1 and 2 

Appendix E. Modeling Protocol for Regional Progress Goals in North Dakota, October 3, 2008 

Appendix F. Public Hearing Record 

F.1 Hearing Notice 

 

F.2 Press Release 

F.3 Affidavit of Publication 

F.4 Invoice of Publication 

F.5 Registration List of Attendees 

F.6 Hearing Transcript 

F.7 Certification of Hearing 

F.8 Response to Public Comments 

Appendix G. Legal Opinion of the Attorney General

Appendix H. NDAC Chapter 33-15-25 Regional Haze Requirements 

Appendix I. Four Factors Analyses 

 I.1 Supplementary Information for Four-Factor Analyses for Selected Individual 

 Facilities in North Dakota 

 I.2 Supplementary Information for Four Factors Analyses by WRAP States 

Appendix J. Plan Development and Consultation 

 J.1 Consultation with Federal Land Managers 

 J.1.1 FLM Comments Provided on BART Portion of SIP During 60-day 

 Consultation Period in 2008 

 J.1.2 NDDoH Response to FLM Comments on BART Portion of SIP in 2008 

 J.1.3 FLM Comments Provided During 60-Day Consultation Period 

 J.1.4 NDDoH Response to FLM Comments 
ix 

 J.2 Consultation with Other States 

 J.2.1 Minnesota September 19, 2007 Memorandum 

 J.2.1 NDDoH August 22, 2008 Letter of Response 

 J.3 Consultation with EPA Region 8 

 J.3.1 EPA Comments Provided on BART Portion of SIP During 60-Day FLM 

 Consultation Period in 2008 

 J.3.2 NDDoH Response to EPA Comments on BART Portion of SIP in 2008 

 

 J.4 Consultation with Tribes 

 
x 

List of Tables 

Table 2.1 - North Dakota Species Contribution (%) - 20% Worst Days 2000-2004 

Table 4.1 - IMPROVE Monitoring Sites in North Dakota 

Table 4.2 - Additional non-IMPROVE Monitors 

Table 5.1 - Baseline Visibility (Deciviews) 

Table 5.2 - EPA Default Natural Visibility Conditions (Deciviews) 

Table 5.3 - WRAP Calculated Natural Visibility Conditions (Deciviews) 

Table 5.4 - Improvement Necessary to Achieve Natural Conditions 

 (Deciviews) 

Table 6.1 - North Dakota 2002 Emissions Inventory (tons) 

Table 6.2 - North Dakota Point Source Emission Inventory 2007 

Table 6.3 - North Dakota 2018 Emission Inventory (tons) 

Table 6.4 - North Dakota Emission Inventory Planning Period Change 

Table 6.5 - Nearby States 2002 Emissions (tons) 

Table 6.6 - ND Sources Extinction Contribution 2000-2004 20% Worst Days 

Table 6.7 - Source Region Apportionment 20% Worst Days 

Table 6.8 - 2002 Canadian Emissions (tons) 

Table 6.9 - Saskatchewan Power Plants 2002 Emissions (tons) 

Table 7.1 - BART- Eligible Sources in North Dakota 

Table 7.2 - Individual BART-Eligible Source Visibility Impact On Class I Areas 

Table 7.3 - BART-Level Emissions Reductions from the 2000-2004 Sulfur Dioxide Average 

Table 7.4 - BART-Level Emissions Reductions from the 2000-2004 Nitrogen Oxides Average 

 

Table 8.1 - WRAP RMC Source Categories 

Table 8.2 - CMAQ-CALPUFF Area Source Categories 
xi 

Table 8.3 - CALPUFF System Versions Applicable For Regional Haze Modeling 

Table 8.4 - User-Defined and Non-IWAQM Settings for CALMET Control File 

Table 8.5 - Monthly Ammonia Background Concentrations 

Table 8.6 - User-Defined and Non-IWAQM Settings for CALPUFF Control File 

Table 8.7 - 3-Step Ammonia Limiting Method 

Table 8.8 - WRAP CMAQ RRF (Specific Day Option) 

Table 8.9 - Hybrid CMAQ-CALPUFF Performance Evaluation - Observed and Predicted 

Concentrations Year 2002 

Table 8.10 - Hybrid CMAQ-CALPUFF Performance Evaluation - Predicted to Observed 

Ratios 2002 

Table 8.11 - WRAP and NDDoH Visibility Modeling Results - Uniform Rate of Progress - 

Default EPA Methodology 

Table 8.12 - Summary of WRAP CMAQ Visibility Projections for Worst 20% Days at TRNP 

Table 8.13 - Summary of WRAP CMAQ Visibility Projections for Best 20% Days at TRNP 

Table 8.14 - Summary of WRAP CMAQ Visibility Projections for Worst 20% Days at LWA 

Table 8.15 - Summary of WRAP CMAQ Visibility Projections for Best 20% Days at LWA 

Table 8.16 - Hybrid Modeling Results - Total North Dakota Contribution to 20% Worst 

Days Predictions 

Table 8.17 - NDDoH Visibility Modeling Results 20% Worst Days - Weight of Evidence - 

Discounting Canadian Emissions 

Table 8.18 - NDDoH Visibility Modeling Results 20% Worst Days - Weight of Evidence - 

Discounting All Out-of-State Sources 

Table 8.19 - NDDoH Visibility Modeling Results 20% Worst Days - Weight of Evidence - 

Zero Future North Dakota Emissions 

Table 8.20 - NDDoH Visibility Modeling Results 20% Worst Days - Weight of Evidence 

Analysis Summary 

 

Table 9.1 - Baseline and Natural Visibility Conditions 

Table 9.2 - Visibility Improvement Required 
xii 

Table 9.3 - North Dakota Sources of Sulfate and Nitrates 2000-2004 

Table 9.4 - North Dakota Title V Sources Q/D Analysis 

Table 9.5 - Sources Evaluated for Additional Controls 

Table 9.6 - Remaining Sources Existing Conditions 

Table 9.7 - Control Options Evaluated 

Table 9.8 - Control Options Cost 

Table 9.9 - Visibility Improvement and Cost Effectiveness 

Table 9.10 - Remaining Useful Life 

Table 9.11 - NDDoH Visibility Modeling Results 20% Worst Days EPA Methodology and 

Weight of Evidence Analysis Summary 

Table 9.12 - Source Region Apportionment 20% Worst Days 

Table 9.13 - Projected Change in Emissions 2002-2018 

Table 9.14 - Reasonable Progress Goals 

Table 9.15 - Time Necessary to Achieve Natural Conditions 

Table 10.1 - Annual Average Emissions from Fire in North Dakota (2000-2004) 

Table 10.2 - North Dakota Anthropogenic Fire Contribution to the 20% Worst Days 

 
xiii 

List of Figures 

Figure 2.1 - Map of United States Class I Areas 

Figure 2.2 - Map of North Dakota Class I Areas 

Figure 2.3 - CENRAP PSAT Modeled W20% 2002 BEXT 

Figure 4.1 - Pictures of the IMPROVE Monitoring Site at Lostwood National Wilderness Area 

Figure 4.2 - IMPROVE Sample Modules 

Figure 4.3 - Comparison of Extinction (Mm-1), Deciview (dv), and Visual Range (km) 

Figure 5.1 - Monitoring Data for Worst 20% Visibility Days TRNP 

Figure 5.2 - Monitoring Data for Best 20% Visibility Days TRNP 

Figure 5.3 - Monitoring Data for Worst 20% Visibility Days LNWA 

Figure 5.4 - Monitoring Data for Best 20% Visibility Days LNWA 

Figure 5.5 - Uniform Rate of Progress 

Figure 5.6 - Glide slope for Worst 20% Visibility Days TRNP 

Figure 5.7 - Glide slope for Worst 20% Visibility Days LNWA 

Figure 6.1 - WRAP Source Region/Type Contributions to Sulfate on Worst 

20% Visibility Days TRNP 

Figure 6.2 - WRAP Source Region/Type Contributions to Nitrate on Worst 

20% Visibility Days TRNP 

Figure 6.3 - Potential Sources and Areas of Sulfur Oxide Emissions on Worst 20% Visibility 

Days 2000-2004 Baseline & 2018 PRPb - Class I Area - Theodore Roosevelt National Park 

Figure 6.4 - Potential Sources and Areas of Nitrogen Oxide Emissions on Worst 20% Visibility 

Days 2000-2004 Baseline & 2018 PRPb - Class I Area - Theodore Roosevelt National Park 

Figure 6.5 - Potential Sources and Areas of Organic Aerosol Emissions on Worst 20% Visibility 

Days 2000-2004 Baseline & 2018 PRPb - Class 1 Area - Theodore Roosevelt National Park 

Figure 6.6 - Potential Sources and Areas of Elemental Carbon Emissions on Worst 20% 

Visibility Days 2000-2004 Baseline & 2018 PRPb - Class 1 Area - Theodore Roosevelt National 

Park 
xiv 

Figure 6.7 - Potential Sources and Areas of Fine PM Emissions on Worst 20% Visibility Days 

2000-2004 Baseline & 2018 PRPb - Class 1 Area - Theodore Roosevelt National Park 

Figure 6.8 - Potential Sources and Areas of Coarse PM Emissions on Worst 20% Visibility Days 

2000-2004 Baseline & 2018 PRPb - Class 1 Area - Theodore Roosevelt National Park 

Figure 6.9 - WRAP Source Region/Type Contributions to Sulfate on Worst 20% Visibility Days 

LNWA 

Figure 6.10 - WRAP Source Region/Type Contributions to Nitrate on Worst 20% Visibility Days 

LNWA 

Figure 6.11 - Potential Sources of Sulfur Oxide Emissions on Worst 20% Visibility Days, 2000-

2004 Baseline & 2018 PRPb, Class I Area - Lostwood NWRW 

Figure 6.12 - Potential Sources of Nitrogen Oxides Emissions on Worst 20% Visibility Days, 

2000-2004 Baseline & 2018 PRPb, Class I Area - Lostwood NWRW 

Figure 6.13 - Potential Sources and Areas of Organic Aerosol Emissions on Worst 20% 

Visibility Days 2000-2004 Baseline & 2018 PRPb - Class 1 Area - Lostwood Wilderness Area 

Figure 6.14 - Potential Sources and Areas of Elemental Carbon Emissions on Worst 20% 

Visibility Days 2000-2004 Baseline & 2018 PRPb - Class 1 Area - Lostwood Wilderness Area 

Figure 6.15 - Potential Sources and Areas of Fine PM Emissions on Worst 20% Visibility Days 

2000-2004 Baseline & 2018 PRPb - Class 1 Area - Lostwood Wilderness Area 

Figure 6.16 - Potential Sources and Areas of Coarse PM Emissions on Worst 20% Visibility 

Days 2000-2004 Baseline & 2018 PRPb - Class 1 Area - Lostwood Wilderness Area 

Figure 6.17 - Sulphur Oxide (SOx) Emissions in Canada for 2002 

Figure 6.18 - Nitrogen Oxides (NOx) Emissions in Canada for 2002 

Figure 7.1 - BART-Eligible Sources and Class I Areas in North Dakota 

Figure 8.1- WRAP CMAQ Domain and NDDoH CALPUFF Domain 

Figure 8.2 - Larger Point Sources and PSD Class I Areas 

Figure 8.3 - IMPROVE 20% Worst Days - TRNP 2000 

Figure 8.4 - Hybrid Interfacing of CMAQ and CALPUFF Modeling Systems 

Figure 8.5 - CALPUFF 3-km Meteorological/Computational Grid 

Figure 8.6 - CALMET Surface / Upper Air Meteorological Stations 
xv 

Figure 8.7 - CALMET Precipitation Stations 

Figure 8.8 - NDDoH Domain - Locations of Larger Point Sources and 36-km Area Source Grid 

Figure 8.9 - NH3 Emissions Density for North Dakota Counties and Adjoining Canadian 

Provinces 

Figure 8.10 - Illustration of Visibility Improvement Using EPA Default Glide Path and US 

Source Adjusted Glide Path for Sulfate 

Figure 8.11 - Observed and Predicted Time Series TRNP NO3 2002 

Figure 8.12 - TRNP Uniform Rate of Progress - EPA Default Methodology 

Figure 8.13 - LWA Uniform Rate of Progress - EPA Default Methodology 

Figure 8.14 - IMPROVE 20% Worst Days - TRNP 2004 

Figure 8.15 - IMPROVE 20% Worst Days - LWA 2004 

Figure 8.16 - Hybrid Modeling Results - Source Group Contributions to 20% Worst Day 

SO4 at TRNP (Base and Future) 

Figure 8.17 - Hybrid Modeling Results - Source Group Contributions to 20% Worst Day 

SO4 at LWA (Base and Future) 

Figure 8.18 - Hybrid Modeling Results - Source Group Contributions to 20% Worst Day 

NO3 at TRNP (Base and Future) 

Figure 8.19 - Hybrid Modeling Results - Source Group Contributions to 20% Worst Day 

NO3 at LWA (Base and Future) 

Figure 8.20 - WRAP Modeling Results - Source Region Contributions to 20% Worst Day 

SO4 at TRNP (baseline) 

Figure 8.21 - WRAP Modeling Results - Source Region Contributions to 20% Worst Day 

NO3 at TRNP (baseline) 

Figure 8.22 - WRAP Modeling Results - Source Region Contributions to 20% Worst Day 

SO4 at LWA (baseline) 

Figure 8.23 - WRAP Modeling Results - Source Region Contributions to 20% Worst Day 

NO3 at LWA (baseline) 

Figure 8.24 - Uniform Rate of Progress - EPA Default Methodology and Canada Sources 

Discounted 
xvi 

Figure 8.25 - Uniform Rate of Progress - EPA Default Methodology and Non-ND Sources 

Discounted 

Figure 8.26 - TRNP Uniform Rate of Progress - EPA Default Methodology and NDDoH 

Weight of Evidence 

Figure 8.27 - LWA Uniform Rate of Progress - EPA Default Methodology and NDDoH 

Weight of Evidence 

Figure 9.1 - Sources and Areas of Potential Organic Carbon Emissions in Worst 20% Visibility 

Days - Theodore Roosevelt National Park 

Figure 9.2 - Sources and Areas of Potential Organic Carbon Emissions in Worst 20% Visibility 

Days - Lostwood Wilderness Area 

Figure 9.3 - TRNP Species Apportionment 20% Worst Days 

Figure 9.4 - LWA Species Apportionment 20% Worst Days 

 
xvii 

List of Acronyms 

AIRS Aerometric Information Retrieval System 

AQS EPA’s Air Quality System 

AVS Antelope Valley Station 

ASOFA Advanced separated overfire air 

BADL Badlands National Park, SD 

Bag Baghouse 

BART Best Available Retrofit Technology 

Bext Light extinction (typically measured in inverse megameters: 1/Mm or Mm-1)

BHP Brake Horsepower 

BOWA Boundary Waters Canoe Area Wilderness Area, MN

BRCA Bryce Canyon National Park, UT 

BRID Bridger Wilderness, WY 

Btu British thermal unit 

CAA Clean Air Act (42 United States Code Sections 7401, et seq) 

CABI Cabinet Mountains Wilderness Area, MT 

CALPUFF Multi-layer, multi-species, non-steadystate, puff, long range transport dispersion 

modeling system 

CAMx Comprehensive Air Quality Model with extensions 

CANY Canyonlands National Park, UT 

CEM Continuous emissions monitor 

CENRAP Central Regional Air Planning Association 

CFR Code of Federal Regulations 

CM Coarse mass (PM2.5 mass subtracted from PM10 mass) 

CMAQ Community Multiscale Air Quality model 

CTIC Conservation Technology Information Center 

D Distance in kilometers 

DGC Dakota Gasification Company 

DOA United States Department of Agriculture 

DOI United States Department of the Interior 

Dv deciview 

∆dv Change in deciviews 

EC Elemental carbon 

EDMS Emissions Data Management System 

EGU Electrical Generating Unit 

EPA United States Environmental Protection Agency 

ESP Electrostatic precipitator 

FGD Flue gas desulfurization 

FLM Federal Land Manager 

FM Fine mass (PM2.5 mass) 

FR Federal Register 

FS United States Forest Service (DOA) 

FWS United States Fish and Wildlife Service (DOI) 

GAMO Gates of the Mountains Wilderness Area, MT 

GCVTC Grand Canyon Visibility Transport Commission 

GPSP Great Plains Synfuels Plant 

GRSA Great Sand Dunes Wilderness Area, CO 
xviii 

HEGL Hercules - Glades Wilderness Area, MO 

Hp Horsepower 

IMPROVE Interagency Monitoring of Protected Visual Environments 

IPM Integrated Planning Model 

ISLE Isle Royale National Park, MI 

km Kilometers 

LADCO Lake Michigan Air Directors Consortium 

lb Pounds 

lb/106

 Btu Pounds per million British thermal units 

LEC Low Emission Combustion 

LOST Lostwood National Wildlife Refuge Wilderness Area, ND 

ln Natural logarithm 

LNB Low NOx burner 

LTPD Long Tons Per Day 

LTS Long Term Strategy 

LWA Lostwood National Wildlife Refuge Wilderness Area, ND 

MACT Maximum Achievable Control Technology 

MELA Medicine Lake National Wildlife Refuge Wilderness Area, MT 

MEVE Mesa Verda National Park, CO 

MI Michigan 

MING Mingo Wilderness Area, MO 

Mm Megameters 

MN Minnesota 

MOZI Mount Zirkel Wilderness Area, CO 

MPCA Minnesota Pollution Control Agency 

MT Montana 

MRPO Midwest Regional Planning Organization 

NAAQS National Ambient Air Quality Standards 

ND North Dakota 

NDAC North Dakota Administrative Code (state rules)

NDCC North Dakota Century Code (state laws) 

NDDoH North Dakota Department of Health 

NEI National Emissions Inventory 

NESHAP National Emission Standards for Hazardous Air Pollutants 

NH3 Ammonia 

NO3 Nitrate 

NOx Oxides of nitrogen or nitrogen oxides 

NOAB North Absaroka Wilderness, WY 

NPS National Park Service (DOI) 

NSPS New Source Performance Standard 

OC Organic carbon 

OFA Overfire air 

PM Particulate matter 

PMC Coarse particulate matter, PM10 – PM2.5

PMcoarse Coarse particulate matter, PM10 – PM2.5

PMF Fine particulate matter, PM2.5

PMfine Fine particulate matter, PM2.5

 
xix 

PM2.5 Fine particulate matter; particulate matter with an aerodynamic diameter less than 

or equal to a nominal 2.5 micrometers as measured by an EPA approved reference 

method 

PM10 Particulate matter with an aerodynamic diameter less than or equal to a nominal 

10 micrometers as measured by an EPA approved reference method 

POA Primary Organic Aerosol 

PSAT Particulate Matter Source Apportionment Technology 

PSD Prevention of Significant Deterioration 

Q Emission rate in tons per year 

RAVI Reasonably Attributable Visibility Impairment 

RPG Reasonable Progress Goal 

RHR Regional Haze Rule/Regulation 

ROMO Rocky Mountain National Park, CO 

SCR Selective catalytic reduction 

SENE Seney National Wildlife Refuge Wilderness Area, MI 

SD South Dakota 

SD Spray dryer 

SIP State Implementation Plan 

SMOKE Sparse Matrix Operator Kernel Emissions 

SMP Smoke Management Plan 

SNCR Selective non-catalytic reduction 

SO2 Sulfur dioxide 

SO4 Sulfate 

SOx Sulfur oxides 

SRU Sulfur recovery unit 

THRO Theodore Roosevelt National Park, ND 

TRNP Theodore Roosevelt National Park, ND 

TPY tons per year; also listed as tpy 

TSD Technical Support Document 

TSS WRAP Technical Support System 

UCR University of California at Riverside 

ULBE UL Bend National Wildlife Refuge Wilderness Area, MT 

URP Uniform rate of progress 

USC United States Code 

VIEWS Visibility Information Exchange Web System 

VISTAS Visibility Improvement State and Tribal Association of the Southeast 

VOC Volatile organic compounds 

VOYA Voyageurs National Park, MN 

VR Visual Range 

WEMI Weminuche Wilderness Area, CO 

WICA Wind Cave National Park, SD 

WRAP Western Regional Air Partnership 

WS Wet scrubber 

YELL Yellowstone National Park, MT & WY 

ZION Zion National Park, UT 
Enclosures 

C: 	 L. David Glatt, Chief, Environmental Health, ND Department of Health 

Terry O'Clair, Director, Division of Air Quality, ND Department of Health 

Gail Fallon, Environmental Protection Agency, Region 8 

38:47:56 

600 E Boulevard Ave. 


Bismarck! ND 58505-0001 


Phone: 701.328.2200 


Fax: 701.328.2205 


www.nd.gov 


- ..... State of-··~·· 

! 

I North Dakota 	

I 

f Office of the Governor 

John Hoeven 	 I 

Governor 	 I 

March 3, 2010 

Lisa P. Jackson, Administrator 

United States Environmental Protection Agency 

c/o Ms. Carol Rushin 

Acting Regional Administrator 

United States Environmental Protection Agency, Region 8 

1595 Wynkoop Street 

Denver, CO 80202-1129 

Re: North Dakota State Implementation Plan for Regional Haze 

Dear Administrator Jackson: 

The State of North Dakota is hereby submitting an amendment to the State 

Implementation Plan (SIP) to address the requirements for Regional Haze of Section 308 of 

40 CFR Part 51, Requirements for Preparation, Adoption, and Submittal ofImplementation 

Plans, Subpart P - Protection of Visibility. This SIP amendment was prepared by the North 

Dakota Department of Health, Air Quality Division. 

Seven steam electric generating units in North Dakota have been identified as being 

subject to the BART requirements of 40 CFR 51.308(e). The installation of BART on these 

sources will result in a reduction of 98,618 tons per year of sulfur dioxide emissions and a 

reduction of 21,137 tons per year of nitrogen oxides emissions from the 2000-2004 average 

emissions. These reductions will significantly improve visibility in North Dakota's Class I 

areas as well as those in surrounding states. 

With this submission, I am requesting the United States Environmental Protection 

Agency's approval of this SIP amendment. 

If you have any questions regarding this submittal, please contact Terry O'Clair, P.E., 

Director, Division ofAir Quality, North Dakota Department of Health, at 701-328-5178. 

Sincerely, I

I 

I 
2 

ii Executive Summary 

This document comprises the State of North Dakota’s State Implementation Plan (SIP) submittal 

to EPA to meet the requirements of Section 308 of the Regional Haze Regulation (40 CFR Part 

51, Subpart P, Section 51.308). Adoption of the North Dakota State Implementation Plan For 

Regional Haze amends the Implementation Plan for the Control of Air Pollution for the State of 

North Dakota. 

Section 1 describes the purpose of and legal authority of the SIP. Section 2 provides introductory 

and background information on the federal regional haze law and regulation, visibility 

impairment, a description of North Dakota’s Class I areas and reasonable progress towards the 

2064 visibility goals. Section 3 describes plan development and consultation with federal land 

managers, other states, the EPA, and stakeholders. Section 4 describes the North Dakota 

monitoring strategy and commitments for future monitoring. Section 5 describes baseline and 

natural visibility conditions for the North Dakota Class I areas and the uniform rate of progress 

for each Class I area. Section 6 describes the sources of visibility impairment at North Dakota=s 

Class I areas. Section 7 describes and provides the results of the Best Available Retrofit 

Technology (BART) process including the Air Pollution Control Permits to Construct issued to 

the seven power plant boilers subject to BART. Section 8 describes the CMAQ and CALPUFF 

modeling used in developing the SIP. Section 9 describes the process for determining the 

reasonable progress goals for North Dakota’s Class I areas and what they are. Section 10 

describes the long term strategy. Section 11 describes the commitments to future consultation, 

progress reports, periodic evaluations of SIP adequacy, and future SIP revisions. Section 12 

summarizes the public participation and review process and the revisions made subsequent to the 

public hearing for the SIP. Appendices at the end of this document provide additional 

information on BART and reasonable progress modeling protocols, company BART analyses, 

Department BART determinations, the BART Air Pollution Control Permits to Construct, FLM 

and EPA comments during the 60-day FLM comment period, the public hearing record, 

Department responses to FLM, EPA, and public comments, consultation with the FLMs, EPA and 

other states, the legal opinions of the Attorney General, and the State BART rule. 

The North Dakota BART determination process identified seven electrical generating units that 

are subject to the BART requirements. The installation of new control devices or modifications to 

existing control devices will reduce sulfur dioxide emission from point sources in the state by 

98,618 tons per year and nitrogen oxides emissions by 21,139 tons per year. The BART 

reductions must be implemented no later than five years after EPA approves this SIP. The 

anticipated date of implementation is 2013. These reductions are expected to make a significant 

improvement in visibility in the affected Class I areas. Total sulfur dioxide emissions in North 

Dakota are expected to decline by 105,729 tons per year (60%) and nitrogen oxides emissions by 

57,970 tons per year (25%) during this planning period. 

The 2018 reasonable progress goals for the twenty percent worst days in the North Dakota Class I 

areas have been established at 16.9 deciviews for each unit of Theodore Roosevelt National Park 

(TRNP) and 18.9 deciviews at Lostwood Wilderness Area (LWA). The analyses conducted by 

the North Dakota Department of Health (NDDoH) and the Western Regional Air Partnership 

(WRAP) indicates there will be no degradation during the 20% best days. 
3 

1. Purpose / Legal Authority 

The purpose of this submittal is to address the State Implementation Plan requirements for the 

State of North Dakota found in Paragraph 40 CFR 51.308, Regional Haze Program Requirements, 

of 40 CFR Part 51 Subpart P - Protection of Visibility. 

The North Dakota Department of Health (the Department), the agency designated to administer 

and coordinate a statewide program of air pollution control, has general legal authority under 

North Dakota Century Code Sections 23-25-03 and 28-32-02 to adopt and enforce rules for 

visibility protection including regional haze visibility impairment. 

The Department adopted rules in 1987 to implement Sections 40 CFR 51. 300 - 307 (NDAC 

Chapter 33-15-19 Visibility Protection, Effective date October 1, 1987) and in 2006 to implement 

Paragraph 40 CFR 51.308(e) (NDAC Chapter 33-15-25 Regional Haze Requirements, Effective 

Date January 1, 2007). 

It is the legal opinion of the North Dakota Attorney General that the State Implementation Plan 

(SIP) is legal, valid and the Air Pollution Control Permits to Construct for the BART sources, and 

the Coyote Station, included within the SIP in Appendix D and Appendix A.4 have the force and 

effect of law. A copy of the Attorney General opinion is contained in Appendix G. 

 
4 

2. Overview 

2.1 Introduction 

The Clean Air Act (CAA) defines the general concept of protecting visibility in each of the 156 

Mandatory Class I Federal Areas across the nation as shown in Figure 2.1. Section 169A from the 

1977 CAA set forth the following national visibility goal: 

“Congress hereby declares as a national goal the prevention of any future, and the 

remedying of any existing, impairment of visibility in mandatory Class I Federal areas 

which impairment results from man-made air pollution.” 

The federal visibility regulations (40 CFR Part 51, Subpart P - Visibility Protection Section 

51.300 - 309) detail a two-phased process to determine existing impairment in each of the Class I 

areas, how to remedy such impairment, and how to establish goals to restore visibility to “natural 

conditions” by the year 2064 in each of these areas. The federal regulations require states to 

prepare a SIP to: include a monitoring strategy, address existing impairment from major 

stationary facilities (Reasonably Attributable Visibility Impairment), prevent future impairment 

from proposed facilities, address Best Available Retrofit Technology (BART) for certain 

stationary sources, consider other major sources of visibility impairment, calculate baseline, 

current and natural visibility conditions, consult with the Federal Land Managers (FLMs) in the 

development or change to the SIP, develop a long-term strategy to address issues facing the state, 

set and achieve reasonable progress goals for each Class I area, and review the SIP every five 

years. 

EPA promulgated regulations to implement the statute in December, 1980. Following litigation, 

a court settlement divided visibility protection into two phases. 

Phase 1 of the visibility program, also known as Reasonably Attributable Visibility Impairment 

(RAVI), addresses impacts in Class I areas by establishing a process to evaluate source specific 

visibility impacts, or plume blight, from individual sources or small groups of sources. Part of 

that process relates to the evaluation of sources prior to construction through the Prevention of 

Significant Deterioration (PSD) permit program for major stationary sources. The plume blight 

part of the Phase 1 program also allows for the evaluation, and possible control, of reasonably 

attributable impairment from existing sources. North Dakota has developed, and EPA approved, 

a SIP for Phase 1 of the visibility program. The Phase 1 rule is NDAC 33-15-19, Visibility 

Protection. 

Section 169B was added to the Clean Air Act Amendments of 1990 to address regional haze. 

Since regional haze does not respect state and tribal boundaries, the amendments authorized EPA 

to establish visibility transport regions as a way to combat regional haze. 

Phase 2 of the visibility program addresses regional haze. This form of visibility impairment 

focuses on overall decreases in visual range, clarity, color, and ability to discern texture and 

details in Class I areas. The responsible air pollutants can be generated in the local vicinity or 
5 

transported by the wind often many hundreds or even thousands of miles from where they 

originated. For technical and legal reasons the second part of the visibility program was not 

implemented in regulation until 1999. 

In July 1999, the EPA finalized the Regional Haze Rule (RHR) requiring States to adopt State 

Implementation Plans to address this aspect of visibility impairment in the Class I areas. The rule 

was amended in July, 2005. Under the current rules the Regional Haze SIP was to be submitted 

to the EPA by December 17, 2007. 

The two key requirements of the regional haze program are: 

1. Improve visibility for the most impaired days, and 

2. Ensure no degradation in visibility for the least impaired days. 

Though the national visibility goals are to be ultimately achieved by the year 2064, the SIP seeks 

to meet the two requirements stated above by 2018, the first planning period established by the 

federal rule. 

Pursuant to the requirements of 51.308(a) and (b), the SIP is intended to meet the requirements 

of EPA=s Regional Haze rules that were adopted to comply with requirements set forth in 

Section 169B of the Clean Air Act. Elements of this SIP are to address: 

 

• The core regional haze program requirements pursuant to 40 CFR 51.308(d), 

 

• The Best Available Retrofit Technology (BART) requirements of 40 CFR 

51.308(e), 

• The requirements for comprehensive periodic revisions of regional haze SIPs of 

40 CFR 51.308(f), 

 

• The requirements for periodic reports describing progress towards the reasonable 

progress goals of 40 CFR 51.308(g), 

• The requirement for determination of the adequacy of the existing implementation 

plan of 40 CFR 51.308(h), and 

 

• The requirements for State and Federal Land Manager coordination of 40 CFR 

51.308(i). 

In addition, 40 CFR 51.308(c) of the original July 1999 regulation provided options for a 

regional planning process to allow states to develop a coordinated approach to regional haze. In 

March 1999, North Dakota became a member of the Western Regional Air Partnership (WRAP), 

the regional planning organization serving 13 western states, tribes and federal agencies. Section 

51.308(c) was deleted on July 6, 2005 when the BART Guidelines were added to the regional 

haze rule. 

 
6 

Figure 2.1 - Map of United States Class I Areas

 
Figure 2.2 – Map of North Dakota Class I Areas

7 
8 

2.2 Visibility Impairment 

Most visibility impairment occurs when pollution in the form of small particles scatters or 

absorbs light. Air pollutants come from a variety of natural and anthropogenic sources. Natural 

sources can include windblown dust and smoke from wildfires. Anthropogenic sources can 

include motor vehicles, electric utility and industrial fuel burning and manufacturing operations. 

More pollutants mean more absorption and scattering of light, which reduce the clarity and color 

of a scene. Some types of particles such as sulfates and nitrates, scatter more light, particularly 

during humid conditions. Other particles like elemental carbon from combustion processes are 

highly efficient at absorbing light. Commonly, the receptor is the human eye and the object may 

be a single viewing target or a scene. 

In the 156 Class I areas across the country, visual range has been substantially reduced by air 

pollution. In eastern parks, average visual range has decreased from 90 miles to 15-25 miles. In 

the West, visual range has decreased from an average of 140 miles to 35-90 miles. 

Some haze causing particles are directly emitted to the air. Others are formed when gases emitted 

to the air form particles as they are carried many miles from the source of the pollutants. Some 

haze-forming pollutants are also linked to human health problems and other environmental 

damage. Exposure to very small particles in the air has been linked with increased respiratory 

illness, decreased lung function and premature death. In addition, particles such as nitrates and 

sulfates contribute to acid deposition potentially making lakes, rivers and streams unsuitable for 

some forms of aquatic life and impacting flora in the ecosystem. These same acid particles can 

also erode materials such as paint, buildings or other natural and man-made structures. 

2.3 Description of North Dakota’s Class I Areas 

The Class I areas in North Dakota include: the Theodore Roosevelt National Park (TRNP) which 

consists of three separate, distinct units and the Lostwood National Wildlife Refuge Wilderness 

Area (LWA). The North Dakota Class I Areas are shown on Figure 2.1 and Figure 2.2.

Theodore Roosevelt National Park is located within Billings and McKenzie Counties in North 

Dakota. The colorful badlands and Little Missouri River of western North Dakota provide the 

scenic backdrop to the park which memorializes the 26th president for his enduring contributions 

to the conservation of our nation’s resources. The park contains 70,447 acres divided among 

three separate units: South Unit, Elkhorn Ranch and North Unit and is managed by the National 

Park Service. The park is comprised of badlands, open prairie and hardwood draws that provide 

habitat for a wide variety of wildlife species including bison, prairie dogs, elk, deer, big horn 

sheep and other wildlife. The Little Missouri River passes through the three units of the park. 

Lostwood National Wildlife Refuge Wilderness Area is located in Burke County in the 

northwestern part of the State. Created by an act of Congress in 1975, the wilderness covers an 

area of 5,577 acres. It is contained within Lostwood National Wildlife Refuge and is managed by 

the U.S. Fish and Wildlife Service. Lostwood National Wilderness Area is designated to preserve 
9 

a region well known for numerous lakes and mixed grass prairie. The wilderness ensures that the 

finest duck and waterfowl breeding region in North America remains wild and unimproved. 

2.4 Class I Areas in Other States Impacted by North Dakota Sources 

In accordance with 40 CFR 51.308, emissions sources within North Dakota have or may be 

reasonably expected to have impacts on the following Class I Areas: Boundary Waters Canoe 

Area Wilderness Area (BOWA) and Voyageurs National Park (VOYA) in Minnesota, Isle 

Royale National Park (ISLE) and Seney National Wildlife Refuge Wilderness Area (SENE) in 

Michigan, Medicine Lake National Wildlife Refuge Wilderness Area (MELA) and U. L. Bend 

National Wildlife Refuge Wilderness Area ((ULBE) in Montana, and Badlands National Park 

(BADL) and Wind Cave National Park (WICA) in South Dakota. As shown in Table 2.1 and 

Figure 2.1, sources in North Dakota have only a small impact on out-of-state Class I areas. For 

Class I areas that are more distant, the impact will be even smaller. Impacts from emission 

sources in North Dakota contribute 5 percent or more of the total 2002 extinction (Bext) in the 

above Class I areas except those in Michigan and BOWA. A 5 percent or larger contribution is 

considered a significant contribution. 

Table 2.1 

North Dakota 

Species Contribution (%) 

20% Worst Days 

2000-2004 

Class I Area Sulfate Nitrate OC EC PMF PMC Sea Salt 

TRNP 21 19 12 29 44 45 0 

LWA 18 13 23 35 28 32 0 

Badlands 8 10 2 4 3 3 0 

Wind Cave 8 8 1 2 4 3 0 

U.L. Bend 9 5 1 1 1 1 0 

Medicine Lake 11 7 9 15 17 16 0 

Gates of the Mountains < 1 < 1 < 1 < 1 < 1 < 1 0 

North Absaroka 1 1 < 1 < 1 < 1 < 1 0 

Voyageurs 6 9 3* 6* 15* 22* 0 

Boundary Waters* 3 10 2 4 10 7 0 

Isle Royale* 2 4 1 2 6 6 0 

Seney* 1 3 <1 <1 2 4 0 

Based on WRAP’s tracer analyses (SO4 and NO3) and weighted emissions potential (WEP) 

analyses unless otherwise noted. 

*Based on CENRAP data. 
10 

From CENRAP’s PSAT analysis, North Dakota’s contribution to total extinction (20% worst 

days in base year 2002) at the nearby Class I areas is shown in Figure 2.3. 

Figure 2.3 

 
11 

2.5 Programs to Address Visibility Impairment 

North Dakota and EPA have many existing emission control programs/rules to improve and 

protect visibility in Class I areas. 

 

North Dakota adopted and EPA approved a SIP for Phase 1 of the visibility program. This 

program addresses major source PSD permitting, source specific haze and plume blight aspects 

of visibility impairment. The Phase 1 rule is NDAC 33-15-19, Visibility Protection. It has an 

effective date of October 1, 1987. 

North Dakota adopted NDAC 33-15-25, Regional Haze Requirements in 2006 with an effective 

date of January 1, 2007. This rule implements the BART provisions of the federal RHR. 

North Dakota has several other emission control programs/rules that while not specifically 

written to address visibility impairment, do address visibility and work to improve and protect 

visibility in Class I areas. These include: 

NDAC Chapter 33-15-02, Ambient Air Quality Standards, Section 33-15-02-03. Air quality 

guidelines. This rule states in part: 

 “In keeping with the purpose of these ambient air quality standards, the quality should be 

such that: 

 4. Visibility will be protected. 

 7. Natural scenery will not be obscured.” 

NDAC Chapter 33-15-04, Open Burning Restrictions. Section 33-15-04-02. Permissible open 

burning. This rule states in part: 

 “2. The following conditions apply to all types of permissible burning listed in 

 subsection 1. 

 h. Except in an emergency, burning may not be conducted is such proximity 

 of any Class I area, as defined in chapter 33-15-15, that the ambient air of 

 such area is adversely impacted. 

 i. Except in an emergency, the visibility of any Class I area cannot be 

 adversely impacted as defined in chapter 33-15-19.” 

 

NDAC Chapter 33-15-15, Prevention of Significant Deterioration of Air Quality, requires that a 

visibility analysis be prepared in accordance with chapter 33-15-19 as a part of the requirements 

for a PSD permit to construct. 

NDAC Chapter 33-15-17. Restriction of Fugitive Emissions. Section 33-15-17-02 Restriction of 

fugitive particulate emissions. This rules states in part: “No person shall emit or cause to be 
12 

emitted into the ambient air from any source of fugitive emissions as specified in section 33-15-

17-01 any particulate matter which: 

 5. Would have an adverse impact on visibility, as defined in chapter 33-15-19, on 

 any federal class I area.” 

In addition to the above programs, the following emission control programs/rules, which do not 

specifically address visibility impairment, control the emission of pollutants that cause or 

contribute to visibility impairment: 

 NDAC Chapter 33-15-03 Restriction of Emission of Visible Air Contaminants 

 NDAC Chapter 33-15-05 Emissions of Particulate Matter Restricted 

 NDAC Chapter 33-15-06 Emissions of Sulfur Compounds Restricted 

 NDAC Chapter 33-15-07 Control of Organic Compounds Emissions 

 NDAC Chapter 33-15-08 Control of Air Pollution from Vehicles and Other Internal 

 Combustion Engines 

 NDAC Chapter 33-15-12 Standards of Performance for New Stationary Sources 

 NDAC Chapter 33-15-14 Designated Air Contaminant Sources, Permit to Construct, 

 Minor Source Permit to Operate, Title V Permit to Operate 

 NDAC Chapter 33-15-20 Control of Emissions from Oil and Gas Well Production 

 Facilities 

 NDAC Chapter 33-15-21 Acid Rain Program 

 NDAC Chapter 33-15-22 Emissions Standards for Hazardous Air Pollutants for 

 Source Categories 

It should be noted that unless specifically stated in the text, all references to existing rules or 

emission control programs are intended only to provide information about various aspects of the 

program described and are neither being submitted to EPA for approval nor being incorporated 

into the SIP as Federally enforceable measures if they haven’t previous been incorporated. 

This SIP is North Dakota’s comprehensive visibility plan which now contains both Phase 1 and 

Phase 2 visibility requirements. It addresses all aspects of North Dakota’s visibility improvement 

program. 

North Dakota is also setting emission limits as a part of this SIP for those sources subject to Best 

Available Retrofit Technology (BART) requirements of Phase 2 of the RHR which are described 

in detail in chapter 7 of this SIP. 

This SIP documents those programs, rules, processes and controls deemed appropriate as 

measures to reduce regional haze and protect good visibility in North Dakota toward meeting the 

2018 and 2064 goals established in the EPA RHR and CAA. 

 EPA has several existing emission control programs/rules which do not specifically address 

visibility impairment that will control the emission of pollutants that cause or contribute to 

visibility impairment which will impact North Dakota Class I areas. They include: 
13 

CAIR. CAIR will permanently cap emissions of SO2 and NOx from EGUs in the eastern United 

States by 2015. When fully implemented, CAIR as originally promulgated would have reduced 

SO2 emissions from EGUs in these states by more than 70%, and NOx emissions by more than 

60%, from 2003 levels. CAIR has been remanded with a replacement rule likely to take 2 years 

to finalize. Any emission reductions from a CAIR replacement rule are unknown at this time. 

When winds are from an easterly direction, North Dakota Class I areas will see some benefit 

from the CAIR reductions. 

NOx SIP Call. Phase I of the NOx SIP call applies to certain EGUs and large non-EGUs, 

including large industrial boilers and turbines, and cement kilns in the eastern United States. It is 

expected to reduce NOx emissions by 90% to mitigate ozone transport. When winds are from an 

easterly direction, North Dakota Class I areas will see some benefit. 

Heavy Duty Diesel (2007) Engine Standard (for on-road trucks and buses). The EPA set a PM 

emissions standard for new heavy-duty engines of 0.01 grams per brake-horsepower-hour(g/bhphr), to take full effect for diesel engines in the 2007 model year. This rule also includes standards 

for NOx and non-methane hydrocarbons (NMHC) of 0.20 g/bhp-hr and 0.14 g/bhp-hr, 

respectively. These NOx and NMHC standards will be phased in together between 2007 and 

2010, for diesel engines. Sulfur in diesel fuel must be lowered to enable modern pollution control 

technology to be effective on these trucks and buses. The EPA will require a 97 percent 

reduction in the sulfur content of highway diesel fuel from its current level of 500 parts per 

million (low sulfur diesel, or LSD) to 15 parts per million (ultra-low sulfur diesel, or ULSD). 

Tier 2 Tailpipe (On-road vehicles). The EPA mobile source rules include the Tier 2 fleet 

averaging program, modeled after the California LEV II standards. Manufacturers can produce 

vehicles with emissions ranging from relatively dirty to zero emissions, but the mix of vehicles a 

manufacturer sells each year must have average NOx emissions below a specified value. Tier 2 

standards became effective in the 2005 model year. 

Large Spark Ignition and Recreational Vehicle Rule. The EPA has adopted new standards for 

emissions of NOx, hydrocarbons, and carbon monoxide from several groups of previously 

unregulated nonroad engines. Included in these are large industrial spark-ignition engines and 

recreational vehicles. Nonroad spark-ignition engines are those powered by gasoline, liquid 

propane gas, or compressed natural gas rated over 19 kilowatts (kW) (25 horsepower). These 

engines are used in commercial and industrial applications, including forklifts, electric 

generators, airport baggage transport vehicles, and a variety of farm and construction 

applications. Nonroad recreational vehicles include snowmobiles, off-highway motorcycles, and 

all-terrain-vehicles. These rules were initially effective in 2004 and will be fully phased-in by 

2012. 

Nonroad Diesel Rule. This rule sets standards that will reduce emissions by more than 90 percent 

from nonroad diesel equipment, and reduce sulfur levels by 99 percent from current levels in 

nonroad diesel fuel starting in 2007. This step will apply to most nonroad diesel fuel in 2010 and 

to fuel used in locomotives and marine vessels in 2012. 
14 

Industrial Boiler/Process Heater MACTs. The EPA issued final rules to substantially reduce

emissions of toxic air pollutants from industrial, commercial and institutional boilers and process 

heaters. These rules reduce emissions of a number of toxic air pollutants, including hydrogen 

chloride, manganese, lead, arsenic and mercury by 2009. This rule also reduces emissions of SO2

and PM in conjunction with the toxic air pollutant reductions. The applied Maximum Achievable 

Control Technology (MACT) control efficiencies were 4 percent for SO2 and 40 percent for 

PM10 and PM2.5. The EPA’s industrial boiler MACT rules were vacated on June 8, 2007, 

however it is believed that by 2018 the USEPA will have re-promulgated a boiler MACT rule; 

however, the emission reductions may change from those of the vacated rule. 

Combustion Turbine and Reciprocating Internal Combustion Engines MACTs. The EPA MACT 

regulations for Gas Turbines and stationary Reciprocating Internal Combustion will have NOx

co-benefit effects. 

VOC 2-, 4-, 7-, and 10-year MACT Standards. Various point source MACTs and associated 

emission reductions have been implemented by EPA. 

2.6 Reasonable Progress Toward the 2064 Visibility Goals 

Section 51.308(d) contains the core requirements for the regional haze SIP. The requirements for 

reasonable progress goals (RPG) are found in 51.308(d)(1) which reads: 

“Reasonable progress goals. For each mandatory Class I Federal area located within the 

State, the State must establish goals (expressed in deciviews) that provide for reasonable 

progress towards achieving natural visibility conditions. The reasonable progress goals 

must provide for an improvement in visibility for the most impaired days over the period 

of the implementation plan and ensure no degradation in visibility for the least impaired 

days over the same period.” 

The reasonable progress goals are interim goals that represent incremental visibility 

improvement over time for the most-impaired (20% worst) days and no degradation in visibility 

for the least-impaired (20% best) days. The first regional haze plan that States must submit to 

EPA needs to include RPGs for the year 2018, also known as the “2018 milestone year”. The 

State has the flexibility in establishing different RPGs for each Class I area. In establishing the 

RPG, the State must consider four factors: 

• the costs of compliance; 

• the time necessary for compliance; 

• the energy and non-air quality environmental impacts of compliance; and 

• the remaining useful life of any potentially affected sources. 

States must demonstrate how these factors were taken into consideration in selecting the RPG for 

each Class I area. 
15 

The North Dakota Department of Health has worked with the Western Regional Air Partnership 

(WRAP) and with the WRAP’s ongoing modeling program as well as implemented our own 

modeling program to establish and refine RPGs for 2018 for the North Dakota Class I areas. This 

process is described in detail in sections 8 and 9.

The RPGs for each North Dakota Class I area established for 2018 are found in section 9. 

Required BART controls will be installed and become operational as expeditiously as 

practicable, but no later than five years after this SIP is approved by EPA. The controls are 

expected to be operational in 2013 - 2014. 

The technical analyses described in this SIP demonstrate that emissions both inside and outside 

of North Dakota have an appreciable impact on the State’s Class I areas. This includes emissions 

from neighboring states as well as international emissions from Canada, especially from the 

provinces of Alberta and Saskatchewan. Emission controls from many sources outside of North 

Dakota will not be fully defined during this round of the Regional Haze SIP process, 

necessitating consideration of outside controls and further interstate and possibly tribal 

consultation in the reasonable progress process to establish refined reasonable progress goals. 

The EPA, through the Department of State, will have to work with Canada and its provinces to 

reduce visibility impairing pollutants that impact North Dakota and other states’ Class I areas. 

Until SIP controls including BART and other programs outside of North Dakota are defined, 

modeled and analyzed, North Dakota cannot fully determine progress toward the 2018 goal or 

the 2064 goal. North Dakota will make its best attempt at demonstrating progress toward the 

goals based on addressing sources within its control. 

 
16 

3. Plan Development and Consultation

The State is required by Section 51.308(d) (3) (i) of the EPA Regional Haze Rule to consult with 

other states to develop coordinated emission management strategies for Class I areas in those 

states North Dakota’s emissions impact or those states whose emissions impact North Dakota’s 

Class I areas and by Section 51.308(i) to consult with the federal land managers of the Class I 

areas in our state and the Class I areas in other states that emissions from North Dakota impact. 

3.1 Consultation with Federal Land Managers 

The North Dakota Department of Health consults with the FLMs as a part of the WRAP and as 

needed directly with the National Park Service and U.S. Fish and Wildlife Service in Denver, 

CO. They have reviewed and commented on North Dakota’s BART modeling protocol and draft 

BART determinations submitted by the BART sources. 

The National Park Service, the U.S. Fish and Wildlife Service, and the U.S. Forest Service 

(federal land manager of Boundary Waters Canoe Area Wilderness in Minnesota) were each 

furnished copies of the draft SIP for review and comment as part of the required 60 day FLM 

comment period (Section 51.308(i)(2)). Continuing consultation with the three FLM’s in the 

future as required by 40 CFR 51,308(i)(4) is addressed in Section 11.1.1. 

3.1.1 FLM Comments Provided During 60 Day Comment Period 

A draft was provided to the FLMs in August 2009 for their 60-day consultation period. The 

FLM comments are included in Appendix J. 

3.1.2 Response to FLM Comments 

The Department’s responses to the FLM’s comments are included in Appendix J. 

3.1.3 FLM Comments Provided on BART Portion of SIP in 2008

The Department had originally planned to submit the BART portion of the regional haze SIP 

separately from the Reasonable Progress portion of the SIP. The BART portion (which is now 

Section 7) was submitted to the FLMs in June of 2008 as part of the required 60-day FLM 

comment period. 

Comments that were received from the FLMs in August of 2008 are attached in Appendix J.1.1 

and discussed further in Section 7. They have been reviewed and considered by the Department 

and included as appropriate in Section 7 of this current SIP. The Department’s responses to the 

FLM comments are attached in Appendix J.1.2. 
17 

3.2 Consultation with EPA Region 8 

The North Dakota Department of Health has consulted with EPA as a part of the WRAP and as 

needed directly with Air Program staff of the EPA Region 8 office in Denver, CO in developing 

this SIP. EPA has reviewed and commented on the State BART modeling protocol, the BART 

Air Pollution Control Permit to Construct template and the draft BART determinations submitted 

by the BART sources. 

In June of 2008, the Department submitted the BART portion of the SIP to EPA Region 8 at the 

same time it was submitted to the FLMs as discussed in Section 3.1.3. Comments were received 

from EPA and are attached as Appendix J.3.1. The Department’s responses to the EPA 

comments are attached as Appendix J.3.2. 

EPA was also provided a copy for comment of the draft SIP at the time it was provided to the 

FLMs as a part of the FLM 60 day comment period. The Department considered the EPA 

comments and made appropriate revisions to the SIP.

The Department also consulted with EPA Region 8 concerning Class I areas in Montana as they 

are preparing a federal implementation plan for Montana. 

3.3 Consultation with Other States 

The North Dakota Department of Health has consulted with our neighboring states of South 

Dakota and Montana through the WRAP and as needed individually. We also participated in 

monthly teleconferences from 2004 through 2008 with Minnesota and Michigan, the states 

containing the four northern Class I areas (Boundary Waters Canoe Wilderness Area and 

Voyageurs National Park in Minnesota, Isle Royale National Park and Seney National Wildlife 

Refuge Wilderness Area in Michigan), and other states in CENRAP and LADCO. We also 

individually consulted as needed with Minnesota, our neighbor directly to the east. 

As a result of the consultations, Minnesota sent a memorandum dated September 19, 2007 to 

North Dakota and other states impacting Minnesota’s Class I areas. Minnesota requested a 

response documenting these consultations have taken place to the satisfaction of North Dakota or 

detailing areas where additional consultation should occur. In those states Minnesota has 

identified as additional contribution states, they asked those states to respond with their 

agreement or disagreement with Minnesota’s determination of contributing states and the 

additional control strategies that will be evaluated. Minnesota’s memorandum and the NDDoH 

letter of response dated August 22, 2008 are attached in Appendix J.2. 

These states were notified of the availability of the draft SIP at the time it was sent to the FLMs. 

 
18 

3.4 Regional Planning Consultation 

The North Dakota Department of Health became a member of the Western Regional Air 

Partnership (WRAP) in March of 1999. WRAP is one of five regional planning organizations 

representing 13 western states, tribes in those states, federal agencies including EPA and FLMs, 

environmental organizations, industry, academics, and other stakeholders. Department staff has 

participated and continues to participate in many WRAP committees and workgroups including 

the Air Managers Committee, the Initiatives Oversight Committee, the Technical Oversight 

Committee, the Emissions Forum, the Stationary Sources Joint Forum, the Technical Analysis 

Forum, the Implementation Workgroup, and the BART Workgroup. Membership in the WRAP 

and participation in its many committees, forums and workgroups allows consultation with the 

many organizations WRAP represents. 

3.5 Consultation with Tribes 

The Department notified the tribes in North Dakota of the public hearing and comment period on 

the draft RH SIP. The Department also notified the WRAP Tribal Caucus Coordinator of its 

intent to draft a SIP to address regional haze and provided a list of contacts within the 

Department (see Appendix J.4). 

3.6 Other Consultation 

The Department has monthly teleconferences with the Subject-to-BART sources in North 

Dakota and has quarterly meetings with the Lignite Energy Council, an organization representing 

lignite coal mines and users within the State. 

 
19 

4. Monitoring Strategy and Other Implementation Plan 

Requirements 

Part 40 CFR 51.305 and 51.308(d)(4) of the Federal Regional Haze Rule requires states to have a 

monitoring strategy in the SIP for addressing reasonably attributable visibility impairment 

(RAVI) and regional haze visibility impairment in the federal Class I areas within the State. The 

monitoring strategy required by 40 CFR 51.305 is discussed in Section 4.1. The monitoring 

strategy required by 40 CFR 51.308(d)(4) is summarized in Section 4.2 and is made a part of this 

RH SIP. 

4.1 RAVI Monitoring Strategy in Current North Dakota Long Term 

Strategy 

The RAVI monitoring strategy required by 40 CFR 51.305 was first included in the long term 

strategy section of North Dakota’s first visibility protection SIP dated October 1, 1987 as Section 

6.10. The visibility monitoring strategy was replaced on March 1, 1994 with Section 6.12. It was 

again replaced on January 1, 1996 with Section 6.13 of the SIP which is the present RAVI 

monitoring strategy. Section 6.13 is: 

 

 Air Quality Surveillance 

In April 1994, Section 6.12 of the SIP was submitted to EPA indicating visibility 

monitoring was not necessary due to a lack of visibility impairment and a database 

indicating stable conditions. In late 1994 and early 1995, there has been a resurgence of 

activity in the oil fields of Western North Dakota. The purpose of Section 6.13 is to 

withdraw Section 6.12 and identify current activities regarding visibility monitoring. 

An increase in oil drilling activities in 1995 has prompted the Park Service to revisit the 

idea of establishing visibility monitoring sites at the Class I areas in North Dakota. The 

Department has met with the Park Service to discuss arrangements for financing visibility 

monitoring. The Department has offered to use funds from an environmental trust that 

was established through deposits from penalties collected on several enforcement cases. 

Theodore Roosevelt National Park (TRNP) Service officials were receptive and have 

transmitted requests to their offices in Denver. Plans currently call for the Department 

and the Park Service to enter into a memorandum of understanding to proceed with 

establishing visibility monitoring at TRNP. 

The Federal Land Managers installed IMPROVE monitors in Theodore Roosevelt National Park 

South Unit and Lostwood National Wildlife Refuge Wilderness Area in December of 1999. 

The Department also worked with the National Park Service to install a webcam at the South 

Unit of TRNP using funds from the environmental trust as included in Section 6.13. The webcam 

became operational in August of 2002. It can be accessed on the internet at: 
20 

http://www.nature.nps.gov/air/WebCams/parks/throcam/throcam.cfm. In addition to the webcam 

picture, current conditions for ozone, sulfur dioxide, fine particulate matter (PM2.5) and weather 

have been added and can be observed. 

4.2 Regional Haze Visibility Impairment Monitoring Strategy and 

Other Implementation Plan Requirements 

Section 51.308(d)(4) requires that the State must submit with the implementation plan a 

monitoring strategy for measuring, characterizing, and reporting of regional haze visibility 

impairment that is representative of all mandatory Class I Federal areas within the State. This 

monitoring strategy must be coordinated with the monitoring strategy required in section 51.305 

for reasonably attributable visibility impairment. Compliance with this requirement may be met 

through participation in the Interagency Monitoring of Protected Visual Environments 

(IMPROVE) network. The IMPROVE monitoring program is discussed in section 4.3.

The state of North Dakota will depend on the Interagency Monitoring of PROtected Visual 

Environments (IMPROVE) monitoring program to collect and report aerosol monitoring data for 

long-term reasonable progress tracking as specified in the Regional Haze Rule (RHR). Because 

the RHR is a long-term tracking program with an implementation period nominally set for 60 

years, the state expects that the IMPROVE program will provide data based on the following 

goals: 

1. Maintain a stable configuration of the individual monitors and sampling sites, and 

stability in network operations for the purpose of continuity in tracking reasonable 

progress trends; 

2. Assure sufficient data capture at each site of all visibility-impairing species; 

3. Comply with EPA quality control and assurance requirements; and 

4. Prepare and disseminate periodic reports on IMPROVE program operations. 

The state of North Dakota is relying on the IMPROVE program to meet these monitoring 

operation and data collection goals, with the fundamental assumption that network data 

collection operations will not change, or if changed, will remain directly comparable to those 

operated by the IMPROVE program during the 2000-2004 RHR baseline period. Technical 

analyses and reasonable progress goals in this implementation plan for Regional Haze are based 

on data from these sites. As such, the State asks that the IMPROVE program identify potential 

issues affecting RHR implementation trends and/or notify the State before changes in the 

IMPROVE program affecting a RHR tracking site are made. 

Further, the state of North Dakota notes that the human resources to operate these monitors are 

provided by Federal Land Management agencies. Beyond that in-kind contribution, resources 

for operation and sample analysis of a complete and representative monitoring network of these 

long-term reasonable progress tracking sites by the IMPROVE program are a collaborative 

responsibility of the EPA, states, tribes, and FLMs and the IMPROVE program steering 

committee. The state of North Dakota will collaborate with the EPA, FLMs, other states, tribes, 
21 

and the IMPROVE committee to assure adequate and representative data collection and reporting 

by the IMPROVE program. North Dakota will consult with the FLMs if IMPROVE monitoring 

budget changes will threaten Class I area monitoring within North Dakota, or in Class I areas 

affected by emissions from North Dakota. 

Section 51.308(d)(4)(i) requires that the implementation plan must also provide for the 

following: 

 

(i) The establishment of any additional monitoring sites or equipment needed to assess 

whether reasonable progress goals to address regional haze for all mandatory Class 

I Federal areas within the State are being achieved. 

The state of North Dakota depends on the following IMPROVE program-operated monitors 

listed in Table 4.1 for tracking RHR reasonable progress. 

Table 4.1 

IMPROVE Monitoring Sites in North Dakota 

IMPROVE 

Monitoring Site 

Class I Area Sponsor Start Date Elevation 

MSL 

LOST1 Lostwood National 

Wilderness Area 

US Fish and 

Wildlife Service 

12/1999 696 m 

2283 ft 

THRO1 Theodore Roosevelt 

National Park-South 

Unit, North Unit, 

Elkhorn Ranch Unit 

National Park 

Service 

12/1999 862 m 

2828 ft 

Note that the THRO1 IMPROVE monitor is located at the Painted Canyon Overlook in the 

South Unit of Theodore Roosevelt National Park. The THRO1 IMPROVE monitor also serves 

and is representative of haze conditions in the separate North Unit and the separate Elkhorn 

Ranch Unit of the Park. The monitor was sited at the existing monitoring site at the Painted 

Canyon Overlook in December 1999 by the federal agencies running the IMPROVE program. 

Site selection followed criteria in the Improve Particulate Monitoring Network Procedures for 

Site Selection, February 24, 1999, to be representative of the Park’s three units. The existing site 

at the Painted Canyon Overlook met all the siting criteria including that all areas represented by 

the site should be within 100 km of a current or potential site. The northern boundary of the 

North Unit is approximately 80 km away from the site and the Elkhorn Ranch Unit is 

approximately 45 km away. 

The state of North Dakota will also operate additional non-IMPROVE monitors that may be used 

in the future evaluations of Class I area visibility. These may include PM2.5 speciation or Federal 

Reference Methods, monitoring systems for SO2, NOx, ozone, continuous PM2.5, continuous 

PM10, and meteorological monitors for wind speed, wind direction, ambient temperature, 

ambient pressure, relative humidity, solar radiation, and precipitation. Monitors presently 

operating are listed in Table 4.2. 
22 

Table 4.2 

Additional non-IMPROVE Monitors 

Monitoring Site Parameter 

Sampling &Analysis 

Method 

Operating 

Schedule 

Lostwood National Wildlife Refuge 

AQS#: 38-013-0004 

Co-located with the LOST1 IMPROVE 

site. 

Sulfur Dioxide Instrumental Pulsed Florescent Continuous

Nitrogen Dioxide Instrumental Chemiluminescence Continuous

Ozone Instrumental Ultra Violet Continuous 

PM2.5 PM2.5 SCC W/No Correction 

TEOM Gravimetric 400 Celsius 

Continuous 

PM10 PM10 TEOM Gravimetric 500

Celsius 

Continuous 

Wind Speed Elec. or Mach Avg. Level 1 Continuous 

Wind Direction Elec. or Mach Avg. Level 1 Continuous 

Ambient 

Temperature 

Elec. or Mach Avg. Continuous 

Delta 

Temperature 

Elec. or Mach Avg. Continuous 

Ambient 

Pressure 

Barometric Pressure Transducer Continuous 

Solar Radiation Pyranometer Continuous 

Relative 

Humidity 

Hydgroscopic Plastic Film Continuous 

Theodore Roosevelt National Park 

North Unit 

AQS# 38-053-0002 

Sulfur 

 Dioxide 

Instrumental Pulsed Florescent Continuous 

Nitrogen Dioxide Instrumental Chemiluminescence Continuous

Ozone Instrumental Ultra Violet Continuous 

PM2.5 PM2.5 SCC W/No Correction 

TEOM Gravimetric 400 Celsius 

Continuous 

PM10 PM10 TEOM Gravimetric 500

Celsius 

Continuous 

Wind Speed Elec. or Mach Avg. Level 1 Continuous 

Wind Direction Elec. or Mach Avg. Level 1 Continuous

Ambient 

Temperature 

Elec. or Mach Avg. Continuous

Ambient 

Pressure 

Barometric Pressure Transducer Continuous

Relative 

Humidity 

Hydroscopic Plastic Film Continuous

Theodore Roosevelt National Park 

South Unit 

Co-located with the THRO1 IMPROVE 

Site. 

Sulfur 

Dioxide 

Instrumental Pulsed Florescent Continuous 

Ozone Instrumental Ultra Violet Continuous 

PM2.5 PM2.5 SCC W/ No Correction 

TEOM Gravimetric 500 Celsius 

Continuous 

Wind Speed Elec. or Mach Avg. Level 1 Continuous 

Wind Direction Elec. or Mach Avg. Level 1 Continuous 

Ambient 

Temperature 

Elec. or Mach Avg. Continuous 

Relative 

Humidity 

Hydroscopic Plastic Film Continuous 

Solar Radiation Pyranometer Continuous 

Precipitation Recording Weighting Continuous 
23 

It should be noted that the two IMPROVE monitors located at the Theodore Roosevelt National 

Park South Unit and the Lostwood National Wilderness Area have complete data for the period 

2000 through 2004 and are relied upon in this Regional Haze SIP to establish the baseline 

deciview conditions. 

In addition, the National Park Service monitors dry deposition at the Theodore Roosevelt 

National Park South Unit monitoring site. The dry deposition is analyzed for SO4, NO3, HNO3, 

NH4, and SO2 weekly. 

Section 51.308(d)(4)(ii) requires that the implementation plan must also provide for the 

following: 

 

(ii) Procedures by which monitoring data and other information are used in 

determining the contribution of emissions from within the State to regional haze 

visibility impairment at mandatory Class I Federal areas both within and outside 

the State. 

The state of North Dakota will use data reported by the IMPROVE program as part of the 

regional technical support analysis tools found at the Visibility Information Exchange Web 

System (VIEWS), as well as other analysis tools that are available from EPA, FLMs and other 

states and tribes. The state of North Dakota will participate in any ongoing regional analysis 

activities to collectively assess and verify the progress toward reasonable progress goals, also 

supporting interstate consultation as the RHR is implemented, and collaborate with EPA, states, 

tribes, and FLMs to ensure the continued operation of existing technical support analysis tools 

and systems developed by WRAP. If the WRAP systems disappear, North Dakota will develop 

or contract for other technical support analysis tools and systems as necessary. 

The state of North Dakota may conduct additional analyses as needed. 

Section 51.308(d)(4)(iv) requires that the implementation plan must also provide for the 

following: 

(iv) The implementation plan must provide for the reporting of all visibility monitoring 

data to the Administrator at least annually for each mandatory Class I Federal area 

in the State. To the extent possible, the State should report visibility monitoring 

data electronically. 

The state of North Dakota will depend on the routine timely reporting of haze monitoring data by 

the IMPROVE program for the reasonable progress tracking sites to the EPA air quality data 

system and VIEWS. The state of North Dakota will collaborate with EPA, states, tribes, and 

FLMs to ensure the continued operation of existing WRAP technical support analysis tools and 

systems. 

The additional non-IMPROVE monitoring is conducted and the data collected and reported in 

accordance with EPA guidance. It is reported through electronic data transfer techniques 

quarterly. 
24 

Section 51.308(d)(4)(v) requires that the implementation plan must also provide for the 

following: 

(v) A statewide inventory of emissions of pollutants that are reasonably anticipated to 

cause or contribute to visibility impairment in any mandatory Class I Federal area. 

The inventory must include emissions for a baseline year, emissions for the most 

recent year for which data are available, and estimates of future projected 

emissions. The State must also include a commitment to update the inventory 

periodically. 

The state of North Dakota has prepared a statewide inventory of emissions that can reasonably 

be expected to cause or contribute to visibility impairment in Federal Class I Areas. Section 6 of 

this plan summarizes the emissions by pollutant and source category. 

The state of North Dakota commits to updating statewide emissions inventories periodically and 

submitting data to the EPA NEI system. The updates will be used for state tracking of emission 

changes, trends, and evaluation of whether reasonable progress goals are being achieved and 

other regional analyses. The inventories will be updated every one to three years on the same 

schedule as the every three-year reporting required by EPA’s Consolidated Emissions Reporting 

Rule and the Air Emissions Reporting Requirements Rule. The Air Emissions Reporting 

Requirements Rule will completely replace the Consolidated Emissions Reporting Rule after the 

2008 emission inventory data submittal which is due to June 1, 2010. 

As a member of the WRAP, North Dakota will continue to use the WRAP-sponsored Emissions 

Data Management System (EDMS) and Fire Emissions Tracking System (FETS) to store and 

access emission inventory data for the region as long as they are maintained and available. If 

they are not available, North Dakota stores its data in house. North Dakota will continue to 

conduct its own modeling to simulate the air quality impacts of emissions for haze and other 

related air quality planning purposes. The state of North Dakota will collaborate with EPA, 

states, tribes and FLMs to ensure the continued operation of existing WRAP technical support 

analysis tools and systems. 

Section 51.308(d)(4)(vi) requires that the implementation plan must also provide for the 

following: 

(vi) Other elements, including reporting, recordkeeping, and other measures, 

necessary to assess and report on visibility. 

The state of North Dakota will track data related to RHR haze plan implementation for sources 

for which the state has regulatory authority, and will depend on the IMPROVE program for 

monitoring data. To ensure the availability of data and analyses to report on visibility conditions 

and progress toward Class I area visibility goals, the state of North Dakota will collaborate with 

EPA, states, tribes and FLMs to ensure the continued operation of the IMPROVE program and 

the existing WRAP-sponsored technical support analysis tools and systems for emissions 

inventory data. 
4.3 Overview of the IMPROVE Monitoring Network 

In the mid

program was established to measure visibility impairment in mandatory Class I Federal areas 

throughout the United States. The monitoring sites are operated and maintained through a formal 

cooperative relationship between the EPA, Na

Service, Bureau of Land Management, NOAA and U.S. Forest Service. In 1991, several 

additional organizations joined the effort: National Association of Clean Air Agencies, Western 

States Air Resources Council (WES

(MARAMA) and Northeast States for Coordinated Air Use Management (NESCAUM). 

The objectives of the IMPROVE program include establishing the current visibility and aerosol 

conditions in mandatory Class

sources responsible for existing human

trends for assessing progress towards the national visibility goals; and supporting the 

requirements of

visibility

Lostwood National Wilderness Area, and Figure 4.2 shows the four separate module

sampling the different pollutant species.

 

Overview of the IMPROVE Monitoring Network 

In the mid-1980’s, the Interagency Monitoring of PROtected Visual

program was established to measure visibility impairment in mandatory Class I Federal areas 

throughout the United States. The monitoring sites are operated and maintained through a formal 

cooperative relationship between the EPA, Na

Service, Bureau of Land Management, NOAA and U.S. Forest Service. In 1991, several 

additional organizations joined the effort: National Association of Clean Air Agencies, Western 

States Air Resources Council (WES

(MARAMA) and Northeast States for Coordinated Air Use Management (NESCAUM). 

The objectives of the IMPROVE program include establishing the current visibility and aerosol 

conditions in mandatory Class

sources responsible for existing human

trends for assessing progress towards the national visibility goals; and supporting the 

requirements of the Regional Haze Rule by providing regional haze monitoring representing all 

visibility-protected Federal Class I areas where practical. Figure 4.1 shows the IMPROVE site at 

Lostwood National Wilderness Area, and Figure 4.2 shows the four separate module

sampling the different pollutant species.

 

 

Overview of the IMPROVE Monitoring Network 

s, the Interagency Monitoring of PROtected Visual

program was established to measure visibility impairment in mandatory Class I Federal areas 

throughout the United States. The monitoring sites are operated and maintained through a formal 

cooperative relationship between the EPA, Na

Service, Bureau of Land Management, NOAA and U.S. Forest Service. In 1991, several 

additional organizations joined the effort: National Association of Clean Air Agencies, Western 

States Air Resources Council (WES

(MARAMA) and Northeast States for Coordinated Air Use Management (NESCAUM). 

The objectives of the IMPROVE program include establishing the current visibility and aerosol 

conditions in mandatory Class I Federal areas; identifying the chemical species and emission 

sources responsible for existing human

trends for assessing progress towards the national visibility goals; and supporting the 

the Regional Haze Rule by providing regional haze monitoring representing all 

protected Federal Class I areas where practical. Figure 4.1 shows the IMPROVE site at 

Lostwood National Wilderness Area, and Figure 4.2 shows the four separate module

sampling the different pollutant species.

Pictures of the 

Lostwood National Wilderness Area

 

Overview of the IMPROVE Monitoring Network 

s, the Interagency Monitoring of PROtected Visual

program was established to measure visibility impairment in mandatory Class I Federal areas 

throughout the United States. The monitoring sites are operated and maintained through a formal 

cooperative relationship between the EPA, Na

Service, Bureau of Land Management, NOAA and U.S. Forest Service. In 1991, several 

additional organizations joined the effort: National Association of Clean Air Agencies, Western 

States Air Resources Council (WESTAR), Mid

(MARAMA) and Northeast States for Coordinated Air Use Management (NESCAUM). 

The objectives of the IMPROVE program include establishing the current visibility and aerosol 

I Federal areas; identifying the chemical species and emission 

sources responsible for existing human-made visibility impairment; documenting long

trends for assessing progress towards the national visibility goals; and supporting the 

the Regional Haze Rule by providing regional haze monitoring representing all 

protected Federal Class I areas where practical. Figure 4.1 shows the IMPROVE site at 

Lostwood National Wilderness Area, and Figure 4.2 shows the four separate module

sampling the different pollutant species.

Pictures of the IMPROVE Monitoring Site

Lostwood National Wilderness Area

 

 

25 

Overview of the IMPROVE Monitoring Network 

s, the Interagency Monitoring of PROtected Visual

program was established to measure visibility impairment in mandatory Class I Federal areas 

throughout the United States. The monitoring sites are operated and maintained through a formal 

cooperative relationship between the EPA, National Park Service, U.S. Fish and Wildlife 

Service, Bureau of Land Management, NOAA and U.S. Forest Service. In 1991, several 

additional organizations joined the effort: National Association of Clean Air Agencies, Western 

TAR), Mid-Atlantic Regional Air Management Association 

(MARAMA) and Northeast States for Coordinated Air Use Management (NESCAUM). 

The objectives of the IMPROVE program include establishing the current visibility and aerosol 

I Federal areas; identifying the chemical species and emission 

made visibility impairment; documenting long

trends for assessing progress towards the national visibility goals; and supporting the 

the Regional Haze Rule by providing regional haze monitoring representing all 

protected Federal Class I areas where practical. Figure 4.1 shows the IMPROVE site at 

Lostwood National Wilderness Area, and Figure 4.2 shows the four separate module

Figure 4.1

IMPROVE Monitoring Site

Lostwood National Wilderness Area

 

 Exterior

Overview of the IMPROVE Monitoring Network 

s, the Interagency Monitoring of PROtected Visual

program was established to measure visibility impairment in mandatory Class I Federal areas 

throughout the United States. The monitoring sites are operated and maintained through a formal 

tional Park Service, U.S. Fish and Wildlife 

Service, Bureau of Land Management, NOAA and U.S. Forest Service. In 1991, several 

additional organizations joined the effort: National Association of Clean Air Agencies, Western 

Atlantic Regional Air Management Association 

(MARAMA) and Northeast States for Coordinated Air Use Management (NESCAUM). 

The objectives of the IMPROVE program include establishing the current visibility and aerosol 

I Federal areas; identifying the chemical species and emission 

made visibility impairment; documenting long

trends for assessing progress towards the national visibility goals; and supporting the 

the Regional Haze Rule by providing regional haze monitoring representing all 

protected Federal Class I areas where practical. Figure 4.1 shows the IMPROVE site at 

Lostwood National Wilderness Area, and Figure 4.2 shows the four separate module

Figure 4.1

IMPROVE Monitoring Site

Lostwood National Wilderness Area

Exterior

Overview of the IMPROVE Monitoring Network 

s, the Interagency Monitoring of PROtected Visual Environments (IMPROVE) 

program was established to measure visibility impairment in mandatory Class I Federal areas 

throughout the United States. The monitoring sites are operated and maintained through a formal 

tional Park Service, U.S. Fish and Wildlife 

Service, Bureau of Land Management, NOAA and U.S. Forest Service. In 1991, several 

additional organizations joined the effort: National Association of Clean Air Agencies, Western 

Atlantic Regional Air Management Association 

(MARAMA) and Northeast States for Coordinated Air Use Management (NESCAUM). 

The objectives of the IMPROVE program include establishing the current visibility and aerosol 

I Federal areas; identifying the chemical species and emission 

made visibility impairment; documenting long

trends for assessing progress towards the national visibility goals; and supporting the 

the Regional Haze Rule by providing regional haze monitoring representing all 

protected Federal Class I areas where practical. Figure 4.1 shows the IMPROVE site at 

Lostwood National Wilderness Area, and Figure 4.2 shows the four separate module

IMPROVE Monitoring Site at 

Lostwood National Wilderness Area

Environments (IMPROVE) 

program was established to measure visibility impairment in mandatory Class I Federal areas 

throughout the United States. The monitoring sites are operated and maintained through a formal 

tional Park Service, U.S. Fish and Wildlife 

Service, Bureau of Land Management, NOAA and U.S. Forest Service. In 1991, several 

additional organizations joined the effort: National Association of Clean Air Agencies, Western 

Atlantic Regional Air Management Association 

(MARAMA) and Northeast States for Coordinated Air Use Management (NESCAUM). 

The objectives of the IMPROVE program include establishing the current visibility and aerosol 

I Federal areas; identifying the chemical species and emission 

made visibility impairment; documenting longtrends for assessing progress towards the national visibility goals; and supporting the 

the Regional Haze Rule by providing regional haze monitoring representing all 

protected Federal Class I areas where practical. Figure 4.1 shows the IMPROVE site at 

Lostwood National Wilderness Area, and Figure 4.2 shows the four separate modules used for 

at 

Environments (IMPROVE) 

program was established to measure visibility impairment in mandatory Class I Federal areas 

throughout the United States. The monitoring sites are operated and maintained through a formal 

tional Park Service, U.S. Fish and Wildlife 

Service, Bureau of Land Management, NOAA and U.S. Forest Service. In 1991, several 

additional organizations joined the effort: National Association of Clean Air Agencies, Western 

Atlantic Regional Air Management Association 

The objectives of the IMPROVE program include establishing the current visibility and aerosol 

I Federal areas; identifying the chemical species and emission 

-term 

trends for assessing progress towards the national visibility goals; and supporting the 

the Regional Haze Rule by providing regional haze monitoring representing all 

protected Federal Class I areas where practical. Figure 4.1 shows the IMPROVE site at 

s used for 

at 
26 

 Interior 

 

 
27 

The IMPROVE sampler consists of four separate modules for measuring regional haze 

Figure 4.2 

IMPROVE Sampler Module 

The data collected at the IMPROVE monitoring sites are used by land managers, industry 

planners, scientists, public interest groups and air quality regulators to better understand and 

protect the visual air quality resource in Class I areas. Most importantly, the IMPROVE Program 

scientifically documents the visual air quality of the wilderness areas and national parks. 

The IMPROVE program has developed methods for estimating light extinction from speciated 

aerosol and relative humidity data. The three most common metrics used to describe visibility 

impairment are: 

Extinction (bext) – Extinction is a measure of the fraction of light lost per unit length 

along a sight path due to scattering and absorption by gases and particles, expressed in 

inverse Megameters (Mm-1). This metric is useful for representing the contribution of 

each aerosol species to visibility impairment and can be practically thought of as the units 

of light lost in a million meter distance. 

Visual Range (VR) – Visual range is the greatest distance a large black object can be 

seen on the horizon, expressed in kilometers (km) or miles (mi). 
28 

Deciview (dv) – This is the metric used for tracking regional haze in the RHR. The 

deciview index was designed to be linear with respect to human perception of visibility. 

A one deciview change is approximately equivalent to a 10% change in extinction, 

whether visibility is good or poor. A one deciview change in visibility is generally 

considered to be the minimum change the average person can detect with the naked eye. 

See Section 5.1 for additional information. 

For reference, Figure 4.3 compares bext in Mm-1, deciviews (dv) which are unitless, and visual 

range in kilometers (km). 

Figure 4.3 

Comparison of Extinction (Mm-1), Deciview (dv), and Visual Range (km) 

The IMPROVE network estimates light extinction based upon the measured mass of various 

contributing aerosol species. EPA’s 2003 guidance for calculating light extinction is based on the 

original protocol defined by the IMPROVE program in 1988. For further information, see: 

http://vista.cira.colostate.edu/improve/Publications/GuidanceDocs/guidancedocs.htm. 

In December 2005, the IMPROVE Steering Committee voted to adopt a revised algorithm for 

use by IMPROVE as an alternative to the original approach. 

The choice between use of the default or the revised equation for calculating the visibility 

metrics for each Class I area is made by the state in which the Class I area is located. North 

Dakota has chosen to use the revised equation. The revised algorithm for estimating light 

extinction is calculated as recommended for use by the IMPROVE steering committee using the 

following equations: 

bext ≈ 2.2×fs (RH)×[Small Amm. Sulfate] + 4.8×f L (RH)×[Large Amm. Sulfate] 

 +2.4×fs (RH) × [Small Amm. Nitrate] + 5.1×f L (RH) × [Large Amm. Nitrate] 

 +2.8× [Small Particulate Organic Matter] + 6.1× [Large Particulate Organic 

 Matter] 

 +10× [Elemental Carbon] 

 +1× [Fine Soil] 

 +1.7×fss (RH) × [Sea Salt] 

 +0.6× [Coarse Mass] 

 +0.33× [NO2 (ppb)] 

 +Rayleigh Scattering (Site Specific) 

 
29 

 Where: 

 bext = light extinction in units of inverse megameters (Mm-1), 

 fS(RH) = function of relative humidity for small size fraction, 

 fL(RH) = function of relative humidity for large size fraction, 

 fSS(RH) = function of relative humidity for sea salt, and 

 all species concentrations are provided in μg/m3. 

 

The revised algorithm splits ammonium sulfate ((NH4)2SO4), ammonium nitrate (NH4NO3) and 

total particulate organic matter (POM =1.8 × organic carbon) concentrations into small and large 

size fractions. The equations for ammonium sulfate are: 

[Large (NH4)2SO4] = [Total (NH4)2SO4]

2 ÷ 20, for [Total (NH4)2SO4] < 20 μg/m3

 

[Large (NH4)2SO4] = [Total (NH4)2SO4], for [Total (NH4)2SO4] ≥ 20μg/m3

[Small (NH4)2SO4] = [Total (NH4)2SO4] – [Large (NH4)2SO4] 

Similar equations are used to apportion total ammonium nitrate and total particulate organic 

matter concentrations into small and large size fractions. 

Light extinction is converted to deciview using the following relationship: 

 dv = 10 × ln(bext/10) 

Where: 

 dv = deciview, 

 bext = light extinction in units of inverse megameters (Mm-1). 

 
30 

5. Baseline and Natural Visibility Conditions and Uniform Rate 

of Progress for North Dakota Class I Areas 

5.1 The Deciview 

The Clean Air Act (Section 169A(a)(1)) states “Congress hereby declares as a national goal the 

prevention of any future, and remedying of any existing impairment of visibility in mandatory 

Class I Federal areas which impairment results from man-made air pollution.” In order to 

achieve this goal, all man-made pollution must be eliminated such that natural conditions 

(visibility) are restored. Natural conditions include naturally occurring phenomena that reduce 

visibility as measured in terms of light extinction, visual range, contrast, or coloration (40 CFR 

51.301). The State is required to develop a SIP that contains measures that make reasonable 

progress toward the national goal of no man-made visibility impairment. 

The primary metric for assessing baseline conditions, natural conditions and the rate of progress 

is the deciview. A deciview is a haze index derived from calculated light extinction, such that 

uniform changes in haziness correspond to uniform incremental changes in perception across the 

entire range of conditions, from pristine to highly impaired. The deciview index is calculated 

based on the following equation: 

Deciview haze index = 10 ln (bext/10 Mm-1) 

Where: bext = the atmospheric light extinction coefficient expressed in inverse megameters 

(Mm-1) 

The deciview scale is zero for pristine conditions and increases as visibility degrades. Each one 

deciview change represents a perceptible or small just-noticeable change in visual air quality or 

haziness to the average person under most circumstances when viewing scenes in Class I areas 

regardless of background visibility conditions. This is approximately a 10% change in the light 

extinction (Mm-1) reading. 

In order to determine the rate of progress of visibility improvement, the baseline conditions and 

natural conditions must be determined for each Class I area. The baseline visibility conditions 

are calculated from IMPROVE data for the years 2000-2004. Natural visibility conditions are 

determined by estimating the natural concentrations of visibility impairing pollutants that existed 

prior to man’s influence. These concentrations are then used to calculate light extinction and the 

deciview metric. 

5.2 Baseline Visibility Conditions 

The Class I Federal Areas in North Dakota are the North Unit, South Unit and Elkhorn Ranch 

Unit of Theodore Roosevelt National Park and the Lostwood Wilderness Area. Although 

IMPROVE monitoring data is not available for the North Unit and Elkhorn Ranch Units of 
31 

TRNP, the Department considers monitoring data from the South Unit to be representative of 

conditions at the other two units. See Section 4.2 for a discussion of the representativeness of the 

monitor in the South Unit for the other two units of TRNP. Since the monitoring is 

representative, we only refer to the TRNP although there are three distinct separate areas. 

Baseline visibility is the average of the IMPROVE monitoring data for 2000 through 2004. 

Baseline visibility is calculated for both the 20 percent best and 20 percent worst days. The 

monitoring data from the IMPROVE sites as plotted by WRAP and displayed on their TSS 

website are shown in Figures 5.1 - 5.4. 

Figure 5.1 

Figure 5.2 

 

Figure 5.3 
32 

Figure 5.3

Figure 5.4 

 
33 

Based on the IMPROVE data, the baseline visibility conditions in the North Dakota Class I areas 

are shown in Table 5.1. 

Table 5.1 

Baseline Visibility (Deciviews) 

Year 

TRNP LWA 

20%

Best Days 

20%

Worst Days 

20%

Best Days 

20%

Worst Days 

2000 8.2 18.1 9.1 19.7 

2001 7.8 18.0 8.2 20.6 

2002 7.8 17.0 7.9 18.8 

2003 7.5 18.4 7.9 18.6 

2004 7.5 17.5 7.9 20.2 

Baseline (avg.) 7.8 17.8 8.2 19.6 

Note: Figures 5.1-5.4 and Table 5.1 are based on the revised IMPROVE Algorithm. The source 

of the figures and data is the WRAP TSS website. A description of the WRAP methodology is 

found in Appendix A.5. 

5.3 Natural Visibility Conditions 

EPA has prepared “Guidance for Estimating Natural Visibility Conditions Under the Regional 

Haze Program” (EPA-454/B-03-005, Sept. 2003) to aid states in estimating natural visibility 

conditions. Natural visibility conditions represent the long-term degree of visibility that is 

estimated to exist in a given Class I area in the absence of man-made impairment. Natural 

visibility conditions are not constant, but vary with changing natural processes such as fire, 

windblown dust, volcanic activity and biogenic emissions. EPA has developed a default 

approach which will satisfy the requirements for the initial SIP which addresses regional haze. 

The default approach defines two separate regions of the United States (1) The East, which 

consists of all states east of the Mississippi River, and up to one tier of states west of the 

Mississippi; and (2) the West, including the regions of the Mountain and Pacific time zones. 

States that are near the boundary between East and West are free to choose which set of natural 

visibility values are more appropriate and adopt those values. North Dakota is considered to be 

in the West Region; however, it is one of those states that are on the boundary of East and West. 

Appendix B of EPA guidance document provides the default natural extinction values 

(deciviews) for both the best and worst days. The values for the North Dakota Class I areas are 

shown in Table 5.2. 

 
34 

Table 5.2 

EPA Default Natural Visibility Conditions (Deciviews) 

Area Best Days Worst Days 

TRNP 2.19 7.31 

LWA 2.21 7.33 

These natural visibility condition values were calculated based on an IMPROVE algorithm 

which has since been modified. The new IMPROVE equation accounts for the effect of particle 

size distribution on light extinction efficiency of sulfate, nitrate and organic carbon. The mass 

multiplier for organic carbon is increased from 1.4 to 1.8. New terms were added to the equation 

to account for light extinction by sea salt and light absorption by gaseous nitrogen dioxide. Site 

specific values are used for Rayleigh scattering to account for variations in elevation and 

temperature. Separate relative humidity enhancement factors are used for small and large size 

distributions of ammonium sulfate, ammonium nitrate and sea salt. 

The WRAP calculated the natural background visibility conditions consistent with EPA’s 

guidance using the revised IMPROVE equation. The results of that calculation are shown in 

Table 5.3. 

Table 5.3 

WRAP Calculated Natural Visibility Conditions (Deciviews) 

Area Best Days Worst Days 

TRNP 3.0 7.8 

LWA 2.9 8.0 

The values in Table 5.3 have been established as the natural background values for North Dakota 

and are used to establish the uniform rate of progress. The improvement necessary to achieve 

natural conditions is shown in Table 5.4. 
35 

Table 5.4 

Improvement Necessary To Achieve Natural Conditions

(Deciviews) 

Area 

Baseline 

Best Days 

Natural 

Best Days 

Improvement

Required 

Baseline 

Worst Days 

Natural 

Worst Days 

Improvement

Required 

TRNP 7.8 3.0 4.8 17.8 7.8 10.0 

LWA 8.2 2.9 5.3 19.6 8.0 11.6 

5.4 Uniform Rate of Progress 

The uniform rate of progress to achieve natural conditions in any Class I Federal area is 

calculated as the difference between baseline condition for the 20% worst days and natural 

condition for the 20% worst days divided by 60 years (2004-2064). Mathematically it is 

determined by the following equation: 

URP = [Baseline Condition - Natural Condition] ) 60 yrs dv/yr 

By multiplying the uniform rate of progress by 14 years in the first planning period (10 years 

thereafter), the progress needed by 2018 to be on the path to achieving natural conditions can be 

calculated as shown in Figure 5.5. 

Figure 5.5 

 

∆ dv = Baseline conditions minus natural conditions 
36 

Based on the above data, the uniform rate of progress is calculated as follows: 

 Theodore Roosevelt National Park 

 URP = (17.8 – 7.8)(14/60) dv 

 URP = 2.3 dv 

 Lostwood Wilderness Area 

 URP = (19.6 – 8.0)(14/60) dv 

 URP = 2.7 dv 

The uniform rate of progress for the Theodore Roosevelt National Park and Lostwood 

Wilderness Area for the first planning period is shown graphically in Figures 5.5 and 5.6. For 

the best days, the State must ensure that no degradation occurs over the same planning period. 

Figure 5.6 

 
37 

Figure 5.7 

 
38 

6. Sources of Visibility Impairment in North Dakota Class I 

Areas 

6.1 Introduction 

40 CFR 51.308(d)(4)(v) requires a statewide inventory of emissions of pollutants that are 

reasonably anticipated to cause or contribute to visibility impairment in any mandatory Class I 

Federal Area be included in the SIP. Emissions within North Dakota are both naturally 

occurring and man-made. Naturally occurring emissions include wildfires, windblown dust and 

others. In North Dakota, the primary sources of anthropogenic emissions include electric utility 

steam generating units (EGUs), energy production and processing sources, agricultural 

production and processing sources, prescribed burning and fugitive dust sources. The North 

Dakota inventory includes emissions of sulfur dioxide (SO2), nitrogen oxides (NOx), fine 

particulate matter (PMF), coarse particulate matter (PMC), organic carbon (OC), volatile organic 

compounds (VOC), elemental carbon (EC) and ammonia (NH3). 

6.2 Emissions in North Dakota 

The most recent complete inventory of all emission categories is from 2002. The point source 

data was compiled by the State while the rest of the inventory was prepared by the WRAP and its 

contractors with input from the state (Case Plan 02d – see Section 9 for a discussion of this case 

plan). A summary of the inventory is shown in Table 6.1. The WRAP Oil and Gas inventory for 

sulfur dioxide was adjusted to include sulfur dioxide emissions from flaring and lease use of sour 

gas at well sites (WRAP did not include flaring and lease use emissions). The adjustment was 

based on hydrogen sulfide data for the combusted gas, which is compiled by the Health 

Department, and the amount of gas flared or used onsite which is compiled by the North Dakota 

Oil and Gas Division. 

 
39 

Table 6.1 

North Dakota 2002 Emissions Inventory (tons) 

Point All Fire Biogenic Area 

Area 

O&G 

OnRoad 

Mobile 

OffRoad 

Mobile 

Road 

Dust 

Fugitive

Dust 

SO2 157,069 540 0 5,557 4,958 812 7,246 3 26 NOx 87,438 1,774 44,569 10,833 4,631 24,746 55,502 3 40 OC 262 3,657 0 1,466 0 231 1,034 201 1,989 EC 29 510 0 262 0 272 3,625 15 135 PMF 2,002 821 0 1,617 0 0 0 3,086 36,354 PMC 565 503 0 199 0 141 0 28,711 172,066 NH3 518 812 0 118,398 0 732 33 0 0 VOC 2,086 3,849 233,561 60,455 7,740 12,814 13,515 0 0 CO 11,944 60,735 67,769 21,933 36 211,842 95,869 0 0 Total 261,912 73,200 345,898 220,719 17,365 251,590 176,825 32,020 210,610 
40 

A complete emissions inventory is not available for a more recent year. However, more recent 

data for point source emissions are available for 2007. Those data are shown in Table 6.2. 

Table 6.2 

North Dakota Point Source Emissions Inventory 2007 

SO2 NOx OC EC PMF PMC NH3 VOC CO 

Point Sources 147,998 82,185 526 31 655 2,749 6,446 4,579 15,897 

WRAP has developed a future inventory for North Dakota for the year 2018. The PRP18b 

emissions inventory for North Dakota is shown in Table 6.3. Again, sulfur dioxide emissions for 

the Area Oil and Gas inventory were increased by the Department to include emissions from 

flaring and lease use of sour gas. The PRP18b emissions inventory also included the proposed 

Gascoyne 500 coal-fired power plant. The Permit to Construct application for this facility has 

been withdrawn. The sulfur dioxide and nitrogen oxides emissions for this plant were removed 

from the inventory by the Department. The Department does not expect any additional coalfired power plants to be constructed in North Dakota before 2018. 

The Department does not agree with WRAP’s estimate of nitrogen oxides emissions from the 

Area Oil and Gas industry for 2018. WRAP has predicted that 2018 NOx emissions would be 

4.5 times greater than 2002 emissions. The Department discussed this estimate with the Oil and 

Gas Division of the North Dakota Industrial Commission. It was the opinion of the Oil and Gas 

Division that most of the Bakken formation development will be over by 2018 and drilling rig 

activities are expected to settle back to the same ratio as production (i.e., 2-2.5 times the 2002 

levels). Based on discussions with the Oil and Gas Division, it is believed that an increase of 2 – 

2.5 times the 2002 emission rate is appropriate for 2018. In subsequent discussions with WRAP, 

representatives of WRAP admitted that 2018 estimates of NOx emissions related to oil and gas 

activity in North Dakota may have been overstated. The inventory in Table 6.3 represents a 2.5 

times increase for Area Oil and Gas sources. 

The Department also disagrees with WRAP’s estimate of PMF and PMC emissions for 2018. As 

explained in Section 9.5.2, agricultural conservation tillage practices, which reduce emissions, 

are expected to increase by 2018. Since agricultural activities and farm land are the major 

sources of fugitive and windblown PMF and PMC emissions, it is expected these emissions will 

decrease. Even though a decrease is expected, the emissions of PMF and PMC shown in Table 

6.3 were not adjusted by the Department. 

In future Regional Haze SIP reviews, the Department will use the most current, refined 

emissions inventories available.
41 

Table 6.3 

North Dakota 2018 Emission Inventory (tons) 

Point All Fire Biogenic Area 

Area 

O&G 

OnRoad 

Mobile 

OffRoad 

Mobile 

Road 

Dust 

Fugitive 

Dust 

SO2 59,560 337 0 5,995 4,200 81 276 3 30 NOx 62,383 1,073 44,569 12,456 11,577 4,906 34,557 3 41 OC 248 2,647 0 1,387 0 151 457 193 2,041 EC 32 449 0 267 0 48 1,363 14 139 PMF 2,086 404 0 1,647 0 0 0 2,956 37,999 PMC 2,349 460 0 216 0 111 0 27,478 184,063 NH3 462 379 0 118,493 0 739 47 0 VOC 2,418 2,346 233,561 69,597 17,968 3,487 8,357 0 0 CO 17,477 41,604 67,769 21,474 172 90,152 102,471 0 0 Total 147,015 49,699 345,898 231,532 33,917 99,675 147,528 30,648 224,314 
42 

The change in emissions during the planning period (2002-2018) is shown in Table 6.4. 

Table 6.4 

North Dakota Emission Inventory Planning Period Change 

2002 

(TPY) 

2018 

(TPY) 

Change 

(TPY) 

Change 

(%) 

SO2 176,211 70,482 -105,729 -60.0 

NOx 229,536 171,566 -57,970 -25.3 

OC 8,840 7,126 -1,714 -19.4 

EC 4,847 2,312 -2,535 -52.3 

PMF 61,519 62,731 1,212 2.0 

PMC 360,936 373,429 12,493 3.5 

NH3 120,493 120,120 -373 -0.3 

VOC 334,020 337,735 3,715 1.1 

CO 470,129 341,118 -129,011 -27.4 

6.3 Emissions from Other States and Canadian Provinces 

The visibility in the Class I areas in North Dakota is influenced by emissions from surrounding 

states, Canada and sources outside WRAP’s modeling domain. The three contiguous states to 

North Dakota are Montana, South Dakota and Minnesota. The 2002 emissions from the 

respective states are shown in Table 6.5. 

 
43 

Table 6.5 

Nearby States 2002 Emissions (tons) 

Montanaa

South Dakotaa Minnesotab

Northa

Dakota 

SO2 51,923 22,725 160,000 176,211 

NOx 243,142 146,822 485,000 229,536 

OC 48,088 9,166 8,840 

EC 11,873 4,703 4,847 

PMF 77,239 82,414 169,000 61,519 

PMC 621,276 615,354 610,000 360,936 

NH3 66,229 120,406 179,000 120,493 

VOC 1,181,318 518,981 366,000 334,020 

CO 1,639,949 509,702 

 

470,129 

a

Source - WRAP TSS (Case Plan 02d) 

b

Source - Minnesota Draft Haze SIP 

North Dakota’s contribution to visibility impairment in TRNP and LWA is generally small (see 

Table 6.6). Sulfates and nitrates, as discussed further in Section 8, are the primary pollutants of 

concern in these Class I areas. In-state sources contribute 21 percent or less of sulfate or nitrate 

during the 20 percent worst baseline days at TRNP or LWA. It should be noted in Table 6.6 the 

sulfate and nitrate values are based on WRAP regional modeling using the CAMx – PSAT source 

apportionment total, while the analyses of weighted emissions potential for organic carbon (OC), 

elemental carbon (EC), and particulate matter (PM) are based on emissions and residence time, 

not modeling. 

 
44 

Table 6.6 

ND Sources Extinction Contribution 

2000-2004 

20% Worst Days 

Class I Area 

Pollutant 

Species 

Extinction 

(Mm-1) 

Species Contribution 

To 

Total Extinction 

(%) 

ND Sources 

Contribution To 

Species Extinction 

(%) a

TRNP Sulfate 

Nitrate 

OC 

EC 

PMF 

PMC 

Sea Salt 

17.53 

13.74 

10.82 

2.75 

0.9 

4.82 

0.07 

35 

27 

21 

5 

2 

10 

0 

21 

19 

12 

29 

44 

45 

0 

LWA Sulfate 

Nitrate 

OC 

EC 

PMF 

PMC 

Sea Salt 

21.4 

22.94 

11.05 

2.84 

0.62 

3.93 

0.26 

34 

36 

18 

5 

1 

6 

0 

18 

13 

23 

35 

28 

32 

0 

a North Dakota contribution for sulfate and nitrate based on WRAP’s tracer analysis and OC, 

EC, PMF, PMC and Sea Salt contribution based on WRAP’s weighted emissions potential 

analysis. 

In general, sources within Canada and sources outside WRAP’s modeling domain are bigger 

contributors to regional haze in TRNP and LWA than North Dakota sources. 

The influence of sources outside of North Dakota on TRNP and LWA for the 2000-2004 period 

can be seen in Figures 6.1-6.16 and Table 6.7. These figures and data were obtained from the 

WRAP TSS website. Figures 6.3, 6.4, 6.9 and 6.10 are based on WRAP’s tracer analysis study 

which is considered a more rigorous analysis than the weighted emissions potential analysis 

(Figures 6.5 – 6.8 and 6.11 – 6.16). The Department does not agree with the WRAP’s estimate 

of nitrogen oxides emissions from the oil and gas source category for 2018 (see Section 6.2). 

The Department believes WRAP has overestimated the 2018 nitrogen oxides emissions. 

Therefore, Figures 6.4 and 6.12 overestimate the percentage of oil and gas nitrogen oxides 

contribution for 2018. 

 
Figure 6.1

Figure 6.2

45 
Figure 6.3

Figure 6.4

46 
Figure 6.

Figure 6.

47 

5 

6 
Figure 6.

Figure 6.

48 

7 

8 
Figure 6.

Figure 6.

49 

9 

10 
Figure 6.11

Figure 6.12

50 
Figure 6.

Figure 6.

51 

13 

14 
Figure 6.

Figure 6.

52 

15 

16 
53 

Table 6.7 

Source Region Apportionment 20% Worst Days 

Contributing 

Area 

Class I Area 

TRNP LWA 

SO4 NO3 SO4 NO3

North Dakota 21.1% 19.1% 17.9% 13.0% 

Canada 28.3% 31.8% 45.9% 44.6% 

Outside Domain 32.6% 17.9% 20.2% 14.0% 

Montana 3.1% 15.0% 2.4% 9.3% 

CENRAP 4.9% 2.5% 5.3% 5.1% 

Other 10.5% 13.7% 8.3% 14.0% 

The primary Canadian provinces which influence visibility in the Class I areas of North Dakota 

are Saskatchewan, Alberta, Manitoba and British Columbia. Emissions from these provinces in 

2002, as reported in WRAP’s TSS website, totaled more than one million tons of sulfur dioxide, 

1.4 million tons of nitrogen oxides and 2 million tons of particulate matter as shown in Table 6.8. 

Table 6.8 

2002 Canadian Emissions (tons) 

 SO2 NOx PMC PMF 

Saskatchewan 126,528 292,539 364,739 78,108 

Manitoba 398,806 142,685 144,928 25,403 

Alberta 433,394 752,966 503,835 807,738 

British Columbia 101,990 214,914 64,545 39,695 

The location of sulfur dioxide and nitrogen oxides emissions, as reported by Environment 

Canada, are shown in Figures 6.17 and 6.18. As can be seen, the heaviest concentration of 

emissions of sulfur dioxide and nitrogen oxides are northwest, in the prevailing wind direction of 

North Dakota’s Class I areas, especially the Lostwood Wilderness Area. 

 
54 

Figure 6.17 

 
55 

Figure 6.18 

Three major coal-fired electric utility steam generating plants within Saskatchewan are located 

just north of the U.S./Canada border within 250 km of the Lostwood Wilderness Area. During 

2002, emissions from these plants totaled nearly 110,000 tons of sulfur dioxide and 38,000 tons 

of nitrogen oxides as shown in Table 6.9. The Boundary Dam plant, which has the largest 

amount of emissions, is located within 60 kilometers of LWA. 

Table 6.9 

Saskatchewan Power Plants 2002 Emissions (tons) 

Plant SO2 NOx PMC PMF 

Boundary Dam 47,338 18,950 7,444 2.996 

Shand 15,146 6,463 40 17 

Poplar River 47,107 12,864 337 136 

 
56 

7. Best Available Retrofit Technology (BART) 

7.1 Introduction 

7.1.1 Overview of Paragraph 51.308(e) of the Federal Regional Haze 

Regulation - Best Available Retrofit Technology (BART) Requirements 

for Regional Haze Visibility Impairment 

The requirements for Best Available Retrofit Technology (BART) are found in Section 

51.308(e) of the federal regional haze regulation. 

Paragraph (e) has six subparagraphs which identify the requirements as follows: 

1. 51.308(e)(1) - BART for individual sources; 

2. 51.308(e)(2) and (3) - An emissions trading program, or other alternative measure, rather 

than to require sources subject to BART to install, operate, and maintain BART; 

3. 51.308(e)(4) - Participation in the EPA administered Clean Air Interstate Rule (CAIR) 

trading programs for sulfur dioxide and nitrogen oxides; 

4. 51.308(e)(5) - Status of BART-eligible sources after a state has met the requirements for 

BART; and 

5. 51.308(e)(6) - An exemption from BART requirements for BART-eligible sources. 

Section 51.308(e) requires the State to submit an implementation plan containing emission 

limitations representing BART and schedules for compliance with BART for each BARTeligible source that may reasonably be anticipated to cause or contribute to any impairment of 

visibility in any mandatory Class I Federal area, unless the State demonstrates that an emissions 

trading program or other alternative measures will achieve greater reasonable progress toward 

natural visibility conditions, or the State participates in a Clean Air Interstate Rule (CAIR) 

trading program. 

 

The Department has decided not to develop an emissions trading program or other alternate 

measures and is not eligible to participate in the CAIR program. Therefore only Sections 

308(e)(1), (5), and (6) apply in North Dakota. 

Each state implementation plan must contain two elements related to BART. 

The first, found in Section 308(e)(1)(i), is the requirement that the State submit a list of the 

BART-eligible sources in the State. 

 

The second requirement is detailed in Section 308 (e)(1)(ii) and requires the State to determine 

and include in the plan BART emission reductions for each BART-eligible source in the State 

which may reasonably be anticipated to cause or contribute to any impairment of visibility in any 

mandatory Class I area. 
57 

BART must be determined for each visibility-impairing pollutant that is emitted by a BARTeligible source which may reasonably be anticipated to cause or contribute to regional haze. The 

definition for BART 51.301 reads: 

Best Available Retrofit Technology (BART) means an emission limitation based on the 

degree of reduction achievable through the application of the best system of continuous 

emission reduction for each pollutant which is emitted by an existing stationary facility. 

The emission limitation must be established, on a case-by-case basis, taking into 

consideration the technology available, the costs of compliance, the energy and the non 

air quality environmental impacts of compliance, any pollution control equipment in use 

or in existence at the source, the remaining useful life of the source, and the degree of 

improvement in visibility which may reasonably be anticipated to result from the use of 

such technology. 

Visibility-impairing pollutants include sulfur dioxide (SO2), nitrogen oxides (NOx), particulate 

matter (PM10 and PM2.5) volatile organic compounds (VOC), and ammonia (NH3). 

In developing source specific emission limits for BART, the State must take into consideration 

the control technology available and a number of specific factors: 

• The costs of compliance; 

• The energy and non-air environmental impacts of compliance; 

• Any existing pollution control technology in use at the source; 

• The remaining useful life of the source; and 

• The degree of improvement in visibility which may reasonably be anticipated 

from the use of such technology. 

The State has the discretion as to how much weight will be given to each of the factors. 

EPA issued final guidance for the determination of BART on July 6, 2005 as 40 CFR Part 51 

Appendix Y - Guidelines for BART Determinations Under the Regional Haze Rule (BART 

guideline). 

The SIP for source-specific BART (51.308(e)(1)) must contain the requirement that each source 

subject to BART install and operate BART as expeditiously as practicable, but in no event later 

than five years after approval of the implementation plan revision by EPA. 

The SIP must contain procedures to ensure control equipment is properly maintained and 

operated in the BART requirements (51.308(e)(1)(v)). 

Paragraph 51.308(e)(5) provides that after a State has met the requirements for source-specific 

BART, BART-eligible sources will be subject to the core requirements of Section 51.308(d) in 

the same manner as other sources. This would include enforceable emissions limitations, 

compliance schedules and other measures as necessary to achieve the reasonable progress goals 

set out in the long-term strategy to attain natural conditions by 2064. 
58 

Paragraph 51.308(e)(6) provides that even where a BART-eligible source may reasonably be 

anticipated to cause or contribute to visibility impairment, section 169A(c) of the Clean Air Act 

allows for the exemption of any source from the BART requirements if it can be demonstrated 

that the source, by itself or in combination with other sources, is not reasonably anticipated to 

cause or contribute to significant visibility impairment. Significant impairment 51.301 is defined 

as: 

“Significant impairment means, for purposes of Section 51.303, visibility impairment 

which, in the judgement of the Administrator, interferes with the management, 

protection, preservation, or enjoyment of the visitor’s visual experience of the mandatory 

Class I Federal area. This determination must be made on a case-by-case basis taking into 

account the geographic extent, intensity, duration, frequency and time of the visibility 

impairment, and how these factors correlate with (1) times of visitor use of the mandatory 

Class I Federal area, and (2) the frequency and timing of natural conditions that reduce 

visibility.” 

EPA believes that the question of whether a source can be reasonably anticipated to cause or 

contribute to significant visibility impairment requires an analysis of the cumulative effects of 

emission sources on a region. Regional modeling will be one appropriate method to determine 

whether a source could qualify for a BART exemption. If a significant cumulative impact is 

demonstrated from the sources across the relevant regional modeling domain, then any BARTeligible source in the region would most likely be found to be reasonably anticipated to cause or 

contribute to significant visibility impairment. 

A source may apply to EPA for an exemption from the BART requirement. The EPA will grant 

or deny an application after providing notice and opportunity for a public hearing. Any 

exemption granted by EPA must have the concurrence from all affected Federal Land Managers. 

The requirements for an exemption are found in Section 51.303. The authority to grant an 

exemption is reserved to EPA and will not be delegated to a state. 

7.1.2 Visibility-Impairing Pollutants of Concern 

For both BART applicability and degree of visibility improvement analyses, the BART guideline 

specifies that only primary emissions need to be considered. These primary emissions include 

SO2, NOx, and direct particulate matter (PM) emissions specified as either coarse (PM10 minus 

PM2.5) or fine (PM2.5). If this distinction in size of PM emissions cannot be made, it would be 

appropriate to consider all PM10 emissions as PM2.5. 

The BART guideline also discusses volatile organic compounds (VOC) or ammonia (NH3) 

emissions as possibly impacting visibility. For the BART-eligible sources identified in North 

Dakota, these emissions (and associated visibility impacts) are negligible, and therefore the 

Department will not require inclusion of VOC or ammonia species in BART-related visibility 

analyses. 
59 

7.1.3 BART Identification Process 

The first step in preparing the RH BART SIP is to develop a list of all BART-eligible sources 

within the State. 

 

The regional haze rule contains the following definitions in Section 51.301: 

 BART-eligible source means an existing stationary facility as defined in this section. 

Existing stationary facility means any of the following stationary sources of air 

pollutants, including any reconstructed source, which was not in operation prior to 

August 7, 1962, and was in existence on August 7, 1977, and has the potential to emit 

250 tons per year or more of any air pollutant. In determining potential to emit, fugitive 

emissions, to the extent quantifiable, must be counted. 

(1) Fossil-fuel fired steam electric plants of more than 250 million British thermal 

units per hour heat input, 

 (2) Coal cleaning plants (thermal dryers), 

 (3) Kraft pulp mills, 

 (4) Portland cement plants, 

 (5) Primary zinc smelters, 

 (6) Iron and steel mill plants, 

 (7) Primary aluminum ore reduction plants, 

 (8) Primary copper smelters, 

(9) Municipal incinerators capable of charging more than 250 tons 

 of refuse per day, 

 (10) Hydrofluoric, sulfuric, and nitric acid plants, 

 (11) Petroleum refineries, 

 (12) Lime plants, 

 (13) Phosphate rock processing plants, 

 (14) Coke oven batteries, 

 (15) Sulfur recovery plants, 

 (16) Carbon black plants (furnace process), 

 (17) Primary lead smelters, 

 (18) Fuel conversion plants, 

 (19) Sintering plants, 

 (20) Secondary metal production facilities, 

 (21) Chemical process plants, 

(22) Fossil-fuel boilers of more than 250 million British thermal units per hour heat 

input, 

(23) Petroleum storage and transfer facilities with a capacity exceeding 300,000 

barrels, 

 (24) Taconite ore processing facilities, 

 (25) Glass fiber processing plants, and 

 (26) Charcoal production facilities. 
60 

The following three steps identify the key elements in the definition of existing stationary facility 

and other related definitions that should be considered when determining whether a source is a 

BART-eligible source. 

STEP 1. IDENTIFY EMISSION UNITS IN THE 26 BART LISTED SOURCE 

CATEGORIES. 

Listed Source Categories - The facility must fall within one of the 26 listed categories in the 

definition of existing stationary facility. These are the same categories that are included in the 

definitions of major source under PSD. PSD guidance documents and case history can be used 

to answer any questions related to the 26 categories. 

Aggregated Unit Applicability - the definition for existing stationary facility includes stationary 

sources. Stationary source is defined as: 

Stationary source means any building, structure, facility, or installation which emits or 

may emit any air pollutant. 

Building, structure, or facility are defined as: 

Building, structure, or facility means all of the pollutant-emitting activities which belong 

to the same industrial grouping, are located on one or more contiguous or adjacent 

properties, and are under the control of the same person (or persons under common 

control). Pollutant-emitting activities must be considered as part of the same industrial 

grouping if they belong to the same Major Group (i.e., which have the same two-digit 

code) as described in the Standard Industrial Classification Manual, 1972 as amended by 

the 1977 Supplement (U.S. Government Printing Office stock numbers 4101-0066 and 

003-005-00176-0 respectively). 

Installation is defined as: 

Installation means an identifiable piece of process equipment. 

The above definitions have been interpreted by EPA to mean that all of the units within the 

source that meet the BART criteria should be aggregated together to determine if the source is 

BART-eligible. 

STEP 2. IDENTIFY THE STARTUP DATES OF THE EMISSION UNITS. 

Date of Operation/Construction/Reconstruction - BART review is limited to units that were 

constructed during a 15-year window between 1962 and 1977. There are several nuances in the 

definition of existing stationary facility that must be considered when determining if a unit falls 

within this 15-year window. The unit must not have been in operation prior to August 7, 1962. 

In operation is defined as: 
61 

In operation means engaged in activity related to the primary design function of the 

source. 

The date that the unit is permitted is not important to meet this test because the focus is on actual 

operation of the unit. 

In addition, the unit must have been in existence as of August 7, 1977. In existence is defined as: 

In existence means that the owner or operator has obtained all necessary preconstruction 

approvals or permits required by Federal, State, or local air pollution emissions and air 

quality laws or regulations and either has (1) begun, or caused to begin, a continuous 

program of physical on-site construction of the facility or (2) entered into binding 

agreements or contractual obligations, which cannot be canceled or modified without 

substantial loss to the owner or operator, to undertake a program of construction of the 

facility to be completed in a reasonable time. 

The actual date a unit begins operation may not be important to meet this test. For example, a 

unit that did not begin operation until 1983 may still be considered BART-eligible if the unit had 

all the necessary preconstruction approvals or permits and had begun, or caused to begin, a 

continuous program of physical on-site construction of the facility, or entered into binding 

agreements or contractual obligations, which cannot be canceled or modified without substantial 

loss prior to August 7, 1977. 

STEP 3. COMPARE THE POTENTIAL TOTAL EMISSIONS FOR EACH 

POLLUTANT FROM THE EMISSION UNITS TO THE 250 TON PER 

YEAR CUT OFF. 

Potential Emissions - The emission units that meet the source category and date of construction 

or operation requirements must then be aggregated together to determine if the combined 

emission units have the potential to emit 250 tons per year of any air pollutant. 

Potential to emit is defined as: 

Potential to emit means the maximum capacity of a stationary source to emit a pollutant 

under its physical and operational design. Any physical or operational limitation on the 

capacity of the source to emit a pollutant including air pollution control equipment and 

restrictions on hours of operation or on the type or amount of material combusted, 

stored, or processed, shall be treated as part of its design if the limitation or the effect it 

would have on emissions is federally enforceable. Secondary emissions do not count in 

determining the potential to emit of a stationary source. 

Applicability for BART is determined on a pollutant-by-pollutant basis. The total 

emissions for each pollutant from all the units at the source remaining after step 2 above 

is compared to the 250 ton per year cut off. 
62 

Pollutants to be considered include the visibility-impairing pollutants, SO2, NOx, PM2.5

and PM10, VOC, and NH3. 

Fugitive emissions, to the extent quantifiable, must be counted. Fugitive emissions are defined 

as: 

Fugitive Emissions means those emissions which could not reasonably pass through a 

stack, chimney, vent, or other functionally equivalent opening. 

As noted in the definition for Potential to emit, secondary emissions do not count in determining 

the potential to emit of a stationary source. Secondary emissions are defined as: 

Secondary emissions means emissions which occur as a result of the construction or 

operation of an existing stationary facility but do not come from the existing stationary 

facility. Secondary emissions may include, but are not limited to, emissions from ships 

or trains coming to or from the existing stationary facility. 

A SOURCE THAT PASSES ALL THREE STEPS IS A BART-ELIGIBLE SOURCE. 

7.1.4 CALPUFF Screening Model Protocol 

The Department has established a protocol for BART-related dispersion modeling applicable to 

BART-eligible sources in North Dakota. The protocol uses the CALPUFF model and conforms 

to the requirements of Appendix Y to Part 51- Guidelines for BART Determinations Under the 

Regional Haze Rule. It follows recommendations for long range transport of Appendix W to Part 

51 - The Guideline on Air Quality Models and EPA’s Interagency Workgroup on Air Quality 

Modeling (IWAQM) Phase 2 Summary Report and Recommendations for Modeling Long Range 

Transport Impacts. The protocol was reviewed by EPA and Federal Land Manager 

meteorologists in Denver, CO prior to finalizing. 

The protocol, “Protocol for BART-Related Visibility Impairment Modeling Analyses in North 

Dakota, November 2005”, is included as Appendix A.1. Both BART applicability and degree of 

visibility improvement analyses were conducted following this protocol. 

7.1.5 Screening Impact Threshold 

In general, to determine which BART-eligible sources must apply BART, single facility 

modeling results for PSD Class I areas are compared with a visibility threshold, expressed in 

deciviews. The Department will follow recommendations in the July 6, 2005 BART guideline 

which states: 

“A single source that is responsible for a 1.0 deciview change or more should be 

considered to “cause” visibility impairment; a source that causes less than a 1.0 deciview 

change may still “contribute” to visibility impairment and thus be subject to BART .... As 
63 

a general matter, any threshold that you use for determining whether a source 

“contributes” to visibility impairment should not be higher than 0.5 deciviews.” 

As a practical matter, the NDDH sees no reason to distinguish among BART-eligible sources 

which “cause” visibility impairment versus those sources which “contribute” to visibility 

impairment in PSD Class I areas. Therefore, the Department will generally use one threshold to 

determine which BART-eligible sources must apply BART. 

The Department, in accordance with the BART guidelines, used a contribution threshold of 0.5 

deciview for determining which sources were subject to BART. The BART guidelines provide 

States the discretion to set a threshold below 0.5 deciviews if “the location of a large number of 

BART-eligible sources within the State and proximity to a Class I area justifies this approach.” 

This decision was based on several factors: 

- It equates to the 5 percent extinction threshold for new sources under the PSD New 

Source Review rules, 

- It is consistent with the threshold selected by other States in the West (all selected 0.5 

dv), 

- It represents the limit of perceptible change 

There are only a few major point sources in North Dakota affecting the Class I areas and they are 

mostly 100 or more miles away, downwind in the prevailing wind direction. BART screening 

modeling indicates the visibility impact to either be much greater than 1.0 deciview or 0.5 

deciview or less (See Section 7.3.1.), and there was no clear rationale or justification for 

selecting a lower level. 

The Department therefore has established 0.5 deciview as the threshold to determine which 

BART-eligible sources must apply BART and included it in the State rules. Definition 2 of 

NDAC Section 33-15-25-01, Definitions, is: 

“Contributes to visibility impairment” means a change in visibility impairment in a Class 

I federal area of five-tenths deciviews or more (24-hour average) above the average 

natural visibility baseline. A source exceeds the threshold when the ninety-eighth 

percentile of the modeling results based on any one year of the three years of 

meteorological data modeled exceeds five-tenths deciviews. 

7.2 BART - Eligible Sources in North Dakota 

The ten BART-eligible sources in the State of North Dakota and their locations are listed in 

Table 7.1. The locations of the BART-eligible sources with respect to Class I areas in North 

Dakota are illustrated in Figure 7.1. 

 
64 

1

2

3

4

6 5

0 100 200 300 400 km

 Key

 1 Leland Olds Station/

 Stanton Station

 2 Milton R Young Station

 3 Heskett Station/

 Mandan Refinery

 4 Coal Creek Station

 5 ACS Drayton

 6 ACS Drayton (modeled)

BART-Eligible Source

Lostwood

Wilderness Area

TRNP South Unit

TRNP North Unit

TRNP Elkhorn Ranch Unit

PSD Class I Area

 Bismarck

NDDH

Modeling

Domain

Table 7.1 

BART-Eligible Sources in North Dakota 

Source and Unit Location 

American Crystal Sugar Company Main Boiler and Lime Kiln Drayton, Pembina County 

Basin Electric Power Cooperative Leland Olds Station Unit 1 Stanton, Mercer County 

Basin Electric Power Cooperative Leland Olds Station Unit 2 Stanton, Mercer County 

Great River Energy Coal Creek Station Unit 1 Falkirk, McLean County 

Great River Energy Coal Creek Station Unit 2 Falkirk, McLean County 

Great River Energy Stanton Station Unit 1 Stanton, Mercer County 

Minnkota Power Cooperative Milton R. Young Station Unit 1 Center, Oliver County 

Minnkota Power Cooperative Milton R. Young Station Unit 2 Center, Oliver County 

MDU Resources Group, Inc. R. M. Heskett Station Unit 2 Mandan, Morton County 

Tesoro Petroleum Corporation 

Mandan Refinery Carbon Monoxide Furnace 

Mandan, Morton County 

 

Figure 7.1 

BART-Eligible Sources and Class I Areas in North Dakota 
65 

The BART-eligible sources were identified using the methodology in the Guidelines for BART 

Determinations Under the Regional Haze Rule, 40 CFR Part 51, Appendix Y, and summarized in 

7.1.3. 

Eight of the BART-eligible sources are fossil-fuel fired steam electric plants of more than 250 

million British thermal units per hour heat input. One is a fossil-fuel fired boiler of more than 

250 million British thermal units per hour heat input and a lime plant (the main boiler and the 

lime kiln at the American Crystal Sugar Company sugar beet processing plant at Drayton) and 

one is a process unit at a petroleum refinery (the carbon monoxide furnace at the Tesoro 

Petroleum Corporation refinery at Mandan). 

7.3 Determination of BART-Eligible Sources Subject to BART 

7.3.1 Sources Subject to BART 

The modeled visibility impact of each of the ten BART-eligible sources listed in Table 7.1 on the 

Class I areas in North Dakota is shown in Table 7.2. The maximum 24-hour 98th percentile 

deciview represents the result for the worst year of the three years modeled (2000-2002). 

The visibility impact of each BART-eligible source is considered significant if the projected 

change in the maximum 24-hour impact at a Class I area compared against natural conditions is 

equal to or greater than 0.5 deciviews. The source is then subject to BART. If the impact is less 

than 0.5 deciviews, the source is exempt from BART. 

The modeling to determine if each BART-eligible source has a significant impact on visibility 

was performed by the Department using the CALPUFF model following EPA’s Interagency 

Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report and 

Recommendations for Modeling Long Range Transport Impacts specified in the Guidelines for 

BART Determinations Under the Regional Haze Rule, 40 CFR Part 51, Appendix Y. The 

modeling protocol is included in Appendix A as Appendix A.1. 

After completion of the subject-to-BART screening modeling, the eight subject-to-BART 

sources were notified they were subject-to-BART by letters dated November 30, 2005. These 

letters are attached as Appendix A.3. 

The Department was contacted by Montana Dakota Utilities who requested approval to do a 

more refined CALPUFF screening analysis considering that the Department’s results were 

slightly above the 0.5 deciview cutoff. MDU submitted a refined analysis in May 2006. This 

analysis is attached in Appendix A.2 and is discussed in 7.3.4 below. 

 
66 

Table 7.2 

Individual BART-Eligible Source Visibility Impact on Class I Areas 

Source and Unit Class I Area 

Maximum 24 Hour 

98th Percentile 

Visibility Impact 

Value Deciview 

Subject to BART or 

Exempt 

American Crystal 

Sugar Company Main 

Boiler and Lime Kiln 

Lostwood 

TRNP South Unit 

TRNP North Unit 

TRNP Elk. Ranch 

Unit 

0.04 

0.04 

0.04 

0.04 

Exempt 

Basin Electric Power 

Cooperative Leland 

Olds Station Unit 1 

and Unit 2 

Lostwood 

TRNP South Unit 

TRNP North Unit 

TRNP Elk. Ranch 

Unit 

5.42 

6.22 

5.32 

4.49 

Subject to BART 

Great River Energy 

Coal Creek Station 

Unit 1 and Unit 2 

Lostwood 

TRNP South Unit 

TRNP North Unit 

TRNP Elk. Ranch 

Unit 

4.04 

4.48 

3.56 

3.04 

Subject to BART 

Great River Energy 

Stanton Station Unit 1 

Lostwood 

TRNP South Unit 

TRNP North Unit 

TRNP Elk. Ranch 

Unit 

1.35 

1.68 

1.54 

1.43 

Subject to BART 

Minnkota Power 

Cooperative Milton R. 

Young Station Unit 1 

and Unit 2 

Lostwood 

TRNP South Unit 

TRNP North Unit 

TRNP Elk. Ranch 

Unit 

4.88 

6.69 

5.58 

6.10 

Subject to BART 

MDU Resources 

Group, Inc. R. M. 

Heskett Station Unit 2 

Lostwood 

TRNP 

0.231

0.281

Exempt 

Tesoro Petroleum 

Corporation Mandan 

Refinery Carbon 

Monoxide Furnace 

Lostwood 

TRNP South Unit 

TRNP North Unit 

TRNP Elk. Ranch 

Unit 

0.04 

0.05 

0.04 

0.04 

Exempt 

1

 MDU BART Screening Results (12/09) 

 
67 

Detailed descriptions of the seven subject-to-BART sources can be found in the Department 

BART Determinations in Appendix B and in the Company BART Analyses in Appendix C. 

7.3.2 Exclusion of Tesoro Mandan Petroleum Refinery

The Department single-source modeling for the Tesoro Petroleum Corporation Mandan Refinery 

Carbon Monoxide Furnace predicted the highest maximum 24 hour 98th percentile visibility 

impact value to be 0.05 deciviews at Theodore Roosevelt National Park South Unit. This is a 

factor of 10 less than the 0.5 deciview threshold for determining whether a BART-eligible source 

causes or contributes to visibility impairment. Therefore, the unit is exempt and not subject to 

BART. 

7.3.3 Exclusion of American Crystal Sugar Drayton Refinery 

The Department single-source modeling for the American Crystal Sugar Company Drayton Plant 

Main Boiler and Lime Kiln predicted the highest maximum 24 hour 98th percentile visibility 

impact value to be 0.04 deciview at all four Class I areas. This is more than a factor of 10 less 

than the 0.5 deciview threshold for determining whether a BART-eligible source causes or 

contributes to visibility impairment. Therefore, the unit is exempt and not subject to BART. 

As shown in Figure 7.1, the American Crystal Sugar Company Drayton Plant is located outside 

the Department’s modeling domain. Even if the domain was extended eastward to incorporate 

the Drayton plant, the plant is located about 400 kilometers from the nearest North Dakota Class 

I area (Lostwood Wilderness Area), and this distance is beyond the accepted range of CALPUFF 

(about 300 kilometers). For modeling purposes, therefore, the Department repositioned the 

Drayton plant about 100 kilometers to the west, to create a virtual source located just inside the 

east boundary of the current modeling domain (represented by the “ACS Drayton (modeled)” 

source in Figure 7.1). This adjustment provided a source-receptor distance more consistent with 

the documented limits of CALPUFF, and should ensure results are conservative. 

In addition, the Minnesota Pollution Control Agency modeled the American Crystal Sugar 

Company Drayton plant and found similar impact levels at the Class I areas in Minnesota, 

Voyagers National Park which is about 300 kilometers from the plant and Boundary Waters 

Canoe Area Wilderness which is about 350 kilometers from the plant. 

7.3.4 Exclusion of Montana Dakota Utilities Heskett Unit No. 2 

The Department single-source modeling for the Montana Dakota Utilities R.M. Heskett Station 

Unit 2 located near Mandan predicted the highest maximum 24 hour 98th percentile visibility 

impact value to be 0.82 deciview at the Theodore Roosevelt National Park South Unit, and 0.54 

deciview at the North Unit, 0.61 deciview at the Elkhorn Ranch Unit and 0.58 deciview at Lost 

wood National Wilderness Area. Because these values were slightly above the threshold of 0.5 

deciviews, Montana Dakota Utilities hired a consultant, ENSR Corporation, to perform a refined 
68 

CALPUFF modeling analysis. The ENSR analysis submitted June 9, 2006 is included as 

Appendix A.2. 

The ENSR analysis made three refinements to the analysis performed by the Department: 

- A 1 km grid size was used instead of 3 km, 

- Particulate matter emissions were speciated into several components that have different 

light scattering potential, and 

- The annual average background visibility was used instead of the annual 20 percent best 

day’s background visibility (as per an EPA court settlement agreement). 

The results of the refined ENSR analysis predicted the highest maximum 24 hour 98th percentile 

visibility impact value to be 0.436 deciviews at Lostwood National Wilderness area in 2001. 

The Department had originally reviewed the ENSR analysis and found it acceptable. 

Additionally, MDU has committed to reduce the potential sulfur dioxide emissions from Heskett 

Unit 2 by a minimum of 70 percent within five years of EPA approval of this SIP. This would 

have reduced sulfur dioxide emissions to 1,847 tons per year from the 2000-2004 emissions of 

2,400 tons per year, a 553 tons per year reduction. The Department had determined that Heskett 

Unit 2 was not subject to BART. See the Department’s letter of May 8, 2007 in Appendix A.3. 

The FLMs and EPA have expressed concerns about the modeling that was conducted. MDU 

agreed to remodel using a revised modeling protocol approved by EPA. The Department 

reassessed the determination to exclude Heskett Station Unit 2 following review of the revised 

modeling. That reassessment shows that Heskett Unit 2 is not subject to the BART 

requirements. The results of the analysis using the protocol as approved by EPA indicated the 

highest maximum 24-hour 98th percentile visibility impact value to be 0.28 deciviews at TRNP 

and 0.23 deciviews at LWA. Based upon the refined analysis and the reassessment analysis, 

Heskett Unit 2 is exempt from the BART requirements. 

7.4 Determination of BART Requirements for Subject-to-BART 

Sources 

7.4.1 Company BART Analyses 

The Department met individually with the seven subject-to-BART sources in December 2005 

and requested they complete and submit BART analyses within nine months of the notification 

letters dated November 30, 2005 or by September 1, 2006. The nine month time was required by 

NDAC 33-15-25-02.1. This was agreed to by the seven sources. They were required to address 

BART for sulfur dioxide, nitrogen oxides, fine particulates and condensable particulates. 

The Department also requested the sources follow requirements of Appendix Y to Part 51 - 

Guidelines for BART Determinations Under the Regional Haze Rule in conducting their 

analyses. 
69 

The seven BART analyses were submitted in final form in late 2007 to early 2008. The final 

company BART analyses are attached as Appendix C. 

7.4.2 Department BART Determinations 

The Department has reviewed the company BART determinations and conducted its own 

determinations for each source. The BART determinations followed the methodology of Section 

IV of Appendix Y to Part 51 - Guidelines for BART Determinations Under the Regional Haze 

Rule. This includes identifying the best system of continuous emission reduction taking into 

account: 

1. The available retrofit control options, 

2. Any pollution control equipment in use at the source (which affects the availability of 

options and their impacts), 

3. The costs of compliance with control options, 

4. The remaining useful life of the facility, 

5. The energy and non-air quality environmental impacts of control options, and 

6. The visibility impacts analysis. 

A case-by-case top down BART analysis using the five basic steps was followed. The five steps 

are: 

STEP 1 - Identify all available retrofit technologies, 

STEP 2 - Eliminate technically infeasible options, 

STEP 3 - Evaluate control effectiveness of remaining technologies, 

STEP 4 - Evaluate impacts and document the results, and 

STEP 5 - Evaluate Visibility impacts. 

The Department BART determinations are included as Appendix B. Each BART determination 

includes a source description including the major boiler units and the minor sources such as 

auxiliary boilers, emergency generators, coal/materials handling dust controls, and coal storage 

piles; the site characteristics; BART evaluations for the major and minor sources; and a permit to 

construct description. 

As detailed in Appendix B, Department BART determinations included an evaluation of 

visibility impacts. Single-source modeling was conducted by the companies to determine the 

degree of visibility improvement associated with various control options for individual units. 

This modeling was based on EPA guidance for BART determinations1

. The Department asked 

companies to provide a 90th percentile 24-hr visibility modeling result (delta-deciview) along 

with the 98th percentile 24-hr value referenced in the guidance, because the 90th percentile would 

 

1

Federal Register, 2005. EPA Regional Haze Regulations and Guidelines for Best 

Available Retrofit Technology (BART) Determinations; Final Rule. Federal Register, July 6, 

2005, Vol.70, No. 128, p. 39103-39172. 
70 

be more consistent with the average of 20% worst days metric utilized for assessing visibility 

improvement progress under the Regional Haze Rule. 

Single-source visibility modeling as provided by the affected companies was reviewed by the 

Department, and results related to visibility improvement were considered in Department BART 

determinations. Because the Department had concerns regarding the viability of single-source 

modeling in representing actual visibility improvement, however, modeling was given less 

weight than other factors in the BART determination process. 

Though single-source modeling is specified in the BART guidance for determining degree of 

visibility improvement, it is clear that this modeling overstates the real single-source visibility 

impact, given the complexity of multiple-source emissions and chemistry actually affecting 

visibility impairment in Class I areas. As suggested by the logarithmic relationship between 

deciview and light extinction (Section 5.1), an observer’s perception of visibility change is 

affected by the total loading of visibility-affecting species in the atmosphere. The observer’s 

perception of visibility change, due to a reduction (or increase) in visibility-affecting emissions 

from one source, depends on cumulative visibility impact due to all sources. For example, a unit 

reduction in visibility-affecting emissions (from one source) will have only half the visual impact 

on the observer (delta-deciview) if total light extinction is 80 Mm-1 compared to the impact if 

total light extinction is 40 Mm-1. By excluding the impact of all other sources, therefore, singlesource modeling is overstating the perceived (delta-deciview) change in visibility. Based on 

Department experience, single-source modeling results (delta-deciview) tend to be five to seven 

times larger than results obtained for the same source when it is combined with all other sources 

in a cumulative analysis. 

It is because of this anomaly that the Department has been very cautious in the interpretation of 

single-source modeling results, and has focused BART determinations on factors other than 

visibility modeling. In some instances, as discussed in Appendix B, the Department has 

conducted supplemental cumulative modeling to more realistically assess the visibility impact of 

emissions reductions associated with optional control strategies for individual sources. 

Cumulative modeling is consistent with the procedure for determining status with respect to 

uniform rate of progress goals, which is discussed in Section 8. 

BART determinations were made for sulfur dioxide, nitrogen oxides, filterable particulate 

matter, and condensable particulate matter for all seven sources. A summary of the BART 

determinations for the main boilers by pollutant follows. 

Sulfur Dioxide

Three of the seven sources have existing sulfur dioxide removal equipment. Great River Energy 

Coal Creek Station Unit 1and Unit 2 and Minnkota Power Cooperative Milton R. Young Station 

Unit 2 are equipped with wet limestone scrubbers. The existing scrubbers at the Coal Creek 

Station employ a bypass for flue gas heat and achieve a 68 percent sulfur dioxide reduction. The 

lime/fly ash wet scrubber at Milton R. Young Unit 2 achieves a 65 percent sulfur dioxide 

reduction. 
71 

Great River Energy Coal Creek Station Unit 1 and Unit 2 - The BART selected by the 

Department for Unit 1 and Unit 2 is a 95 percent reduction efficiency or a limit of 0.15 pounds 

per million Btu of heat input on a 30-day rolling average basis to be achieved by modifying the 

existing wet scrubbers and the adding of a new coal dryer serving both units. Unit 1 and Unit 2 

emissions may be averaged provided the average does not exceed the limit. 

Minnkota Power Cooperative Milton R. Young Station Unit 2 - The BART for sulfur dioxide 

selected by the Department for Unit 2 is a 95 percent reduction efficiency or limit of 0.15 pounds 

per million Btu of heat input on a 30-day rolling average basis to be achieved by modifying the 

existing wet scrubber. The Consent Decree for Minnkota requires a minimum of 90 percent 

reduction of sulfur dioxide at Unit 2. The 90 percent reduction requirement will apply when 

Minnkota chooses to comply with the 0.15 lb/106

 Btu limit. The 90 percent reduction 

requirement is included in the BART permit. 

Minnkota Power Cooperative Milton R. Young Station Unit 1 - Unit 1 has no existing sulfur 

dioxide removal equipment. The BART selected by the Department for Unit 1 is a 95 percent 

reduction efficiency on a 30-day rolling average basis to be achieved by the installation of a new 

wet scrubber. The EPA/State Consent Decree states that if Minnkota installs a wet scrubber, they 

must comply with a 95 percent reduction requirement with no alternative pounds per million Btu 

of heat input limit. 

Basin Electric Power Cooperative Leland Olds Station Unit 1 and Unit 2 - Unit 1 and Unit 2 

have no existing sulfur dioxide removal equipment. The BART selected by the Department for 

Unit 1 and for Unit 2 is a 95 percent reduction efficiency or a limit of 0.15 pounds per million 

Btu of heat input on a 30-day rolling average basis to be achieved by the installation of new wet 

scrubbing system. 

Great River Energy Stanton Station Unit 1 - Unit 1 has no existing sulfur dioxide removal 

equipment. Unit 1 burns either lignite coal or subbituminous coal. Because these coals have 

different average sulfur contents, Btu contents and chemical characteristics, the Department will 

issue BART limits appropriate to each coal. The BART selected by the Department for Unit 1 is 

a 90 percent reduction on a 30-day rolling average basis burning either coal or a limit of 0.24 

pounds per million Btu of heat input on a 30-day rolling average basis when burning only lignite 

coal, a limit of 0.16 pounds per million Btu of heat input on a 30-day rolling average basis when 

burning subbituminous coal, and weighted average emission limit when burning a combination 

of lignite and subbituminous coal. 

The sulfur dioxide emissions before and after BART control, the BART controls, and the sulfur 

dioxide emission limits for each of the seven sources are summarized in Table 7.3. 

 
72 

Table 7.3 

BART-Level Emissions Reductions From the 2000-2004 

Sulfur Dioxide Average 

Source and 

 Unit 

2000-2004 

Average 

Emissions 

Tons per 

Year 

Baseline 

Level of 

Control 

% Reduction 

BART Level 

of Control 

% 

Reduction* 

Control 

Device 

Emissions 

after Controls 

Tons per 

Year** 

Emission 

Reduction 

Tons per 

Year** 

Emission 

Limit 

Basin Electric 

Power 

Cooperative 

Leland Olds 

Station Unit 1 

16,666 0% 95% New Wet 

Scrubber 

1,376 15,290 95% reduction 

or 0.15 lb/106

Btu 30 day 

rolling average 

Basin Electric 

Power 

Cooperative 

Leland Olds 

Station Unit 2 

30,828 0% 95% New Wet 

Scrubber 

2,530 28,298 95% reduction 

or 0.15 lb/106

Btu 30 day 

rolling average 

Great River 

Energy Coal 

Creek Station 

Unit 1 

14,086 68% 95% Modified 

Existing Wet 

Scrubber and 

Coal Dryer 

3,781 10,305 95% reduction 

or 0.15 lb/106

Btu 30 day 

rolling average 

Great River 

Energy Coal 

Creek Station 

Unit 2 

12,407 68% 95% Modified 

Existing Wet 

Scrubber and 

Coal Dryer 

3,621 8,786 95% reduction 

or 0.15 lb/106

Btu 30 day 

rolling average 

Great River 

Energy 

Stanton 

Station Unit 1 

8,312 0% 90% New Spray 

Dryer and 

Fabric Filter 

1,179 7,133 90% reduction 

or 0.24 lb/106

Btu (lignite) or 

0.16 lb/106

 

Btu (PRB) 30 

day rolling 

average 

Minnkota 

Power 

Cooperative 

Milton R. 

Young Station 

Unit 1 

20,148 0% 95% New Wet 

Scrubber 

1,007 19,141 95% reduction 

30 day rolling 

average 

Minnkota 

Power 

Cooperative 

Milton R. 

Young Station 

Unit 2 

12,404 65% 95% Modified 

Existing Wet 

Scrubber 

2,739 9,665 95% 

reduction; or 

90% reduction 

and 0.15 lb/106

Btu 30 day 

rolling average 

Total 114,851 ---- ---- ---- 16,233 98,618 ---- 

*Based on the two year baseline emission rate for BART. 

** Based on the average 2000-2004 operating rate and emission rates. 

Nitrogen Oxides

There are many different technologies available for controlling nitrogen oxides emissions from 

coal fired boilers. The technical feasibility for a particular technology is dependent on the type 

and size of the boiler and the type of coal being combusted. The types of boiler used at the seven 

BART sources in the state are cyclone (3), tangentially-fired pulverized coal (2), and wall-fired 

pulverized coal (2). The types of coal burned in the state are lignite coal with varying 
73 

characteristics from several different mines near the plants and subbituminous coal from the 

Powder River Basin (PRB) in Wyoming and Montana. 

The nitrogen oxides control technologies that are applicable to a particular boiler are listed in the 

Company BART Analyses in Appendix C and in the Department BART Determinations in 

Appendix B. 

One technology, selective catalytic reduction (SCR), has one of the highest nitrogen oxides 

removal rates (in the range of 90 percent) and has been commercially installed on many different 

types of boilers burning different types of coal. However, it has never been installed on any type 

of boiler burning North Dakota lignite. The only pilot scale testing conducted on North Dakota 

lignite failed after two months. The seven BART sources determined SCR is not technically 

feasible for installation on boilers in North Dakota burning lignite coal. The Department agrees 

that high dust SCR is not technically feasible; however, low dust and tail end SCR are 

considered technically feasible. A detailed discussion on the technical feasibility of SCR is 

provided in Appendix B.5. The BART for nitrogen oxides for each source follows: 

Basin Electric Power Cooperative Leland Olds Station Unit 1 - This unit is a wall-fired 

pulverized coal boiler combusting primarily lignite coal (80-100%) and PRB subbituminous coal 

(20-0%). The existing nitrogen oxides control equipment is low NOx burners installed in 1995. 

The BART selected by the Department is a limit of 0.19 pounds per million Btu of heat input on 

a 30-day rolling average basis. This limit is to be achieved by the installation of selective 

noncatalytic reduction (SNCR) and basic separated overfire air (SOFA). 

Basin Electric Power Cooperative Leland Olds Station Unit 2 - This unit is a cyclone boiler 

combusting primarily lignite coal (80-100%) and PRB subbituminous coal (20-0%). The unit 

has no existing nitrogen oxides control equipment. The BART selected by the Department is a 

limit of 0.35 pounds per million Btu of heat input on a 30-day rolling average basis. This limit is 

to be achieved by the installation of selective noncatalytic reduction (SNCR) and advanced 

separated overfire air (ASOFA). 

Great River Energy Coal Creek Station Unit 1 and Unit 2 - Unit 1 and Unit 2 are identical 

tangentially-fired pulverized coal boilers combusting lignite coal. The existing nitrogen oxides 

control equipment is low NOx burners (LNB) and separated overfire air (SOFA). The BART 

selected by the Department for each unit is a limit of 0.17 pounds per million Btu of heat input 

on a 30-day rolling average basis. This limit is to be achieved by the use of the existing low NOx

burners (LNB) and modified/additional separated overfire air (SOFA). 

Great River Energy Stanton Station Unit 1 - Unit 1 is a wall-fired pulverized coal boiler 

combusting PRB subbituminous coal and lignite coal. The existing nitrogen oxides control 

equipment is low NOx burners. The BART selected by the Department is a limit of 0.29 pounds 

per million Btu of heat input on a 30-day rolling average basis when burning only lignite coal, a 

limit of 0.23 pounds per million Btu of heat input on a 30-day rolling average basis when 

burning subbituminous coal, and a weighted average emission limit when burning a combination 

of lignite and subbituminous coal. These limits are to be achieved by the installation of low NOx

burners (LNB), overfire air (OFA), and selective noncatalytic reduction (SNCR). 
74 

Minnkota Power Cooperative Milton R. Young Station Unit 1 and Unit 2 - Unit 1 and Unit 2 are 

both cyclone boilers burning lignite coal. The units have no existing nitrogen oxides control 

equipment. The BART selected by the Department for Unit 1 is a limit of 0.36 pounds per 

million Btu of heat input on a 30-day rolling average basis and for Unit 2 is a limit of 0.35 

pounds per million Btu of heat input on a 30-day rolling average basis. These limits will be 

achieved by the installation of selective noncatalytic reduction (SNCR) and advanced separated 

overfire air (ASOFA). These limits do not apply during startup. During startup, NOx emissions 

from Unit 1 shall not exceed 2070.1 pounds per hour on a 24-hour rolling average basis and 

3995.6 pounds per hour from Unit 2 on a 24-hour rolling average basis. 

The nitrogen oxides emissions before and after BART control, the BART controls, and the 

nitrogen oxide emission limits for each of the seven sources are summarized in Table 7.4. 

Table 7.4 

BART-Level Emissions Reductions From the 2000-2004 

Nitrogen Oxides Average 

Source and 

Unit 

2000-2004 

Average 

Emissions 

Tons per 

Year 

Baseline Level 

of Control 

% Reduction 

BART Level 

of Control 

% Reduction* Control 

Device 

Emissions 

after Controls 

Tons per 

Year** 

Emission 

Reduction 

Tons per 

Year** 

Emission Limit 

Basin Electric 

Power 

Cooperative 

Leland Olds 

Station Unit 1 

2,501 0% 42% SOFA and 

SNCR 

1,744 757 0.19 lb/106 Btu 

30 day rolling 

average 

Basin Electric 

Power 

Cooperative 

Leland Olds 

Station Unit 2 

10,422 0% 54.5% ASOFA and 

SNCR 

5,904 4,518 0.35 lb/106 Btu 

30 day rolling 

average 

Great River 

Energy Coal 

Creek Station 

Unit 1 

5,116 0% 30% SOFA 4,285 831 0.17 lb/106 Btu 

30 day rolling 

average 

Great River 

Energy Coal 

Creek Station 

Unit 2 

5,391 0% 30% SOFA 4,104 1,287 0.17 lb/106 Btu 

30 day rolling 

average 

Great River 

Energy Stanton 

Station Unit 1 

2,048 0% 45% LNB, Overfire 

Air and SNCR 

1,425 623 0.29 lb/106 Btu 

lignite coal 0.23 

lb/106 Btu PRB 

coal 30 day 

rolling average 

Minnkota Power 

Cooperative 

Milton R. Young 

Station Unit 1 

8.665 0% 58.1% ASOFA and 

SNCR 

3,857 4,808 0.36 lb/106 Btu 

30 day rolling 

average 

Minnkota Power 

Cooperative 

Milton R. Young 

Station Unit 2 

14,705 0% 58.0% ASOFA and 

SNCR 

6,392 8,313 0.35 lb/106 Btu 

30 day rolling 

average 

Total 48,848 ---- ---- ---- 27,711 21,137 ---- 

*Based on the two year baseline emission rate for BART. 

** Based on the average 2000-2004 average operating rate. 
75 

Filterable Particulate Matter

Filterable particulate matter is solid and liquid (non-condensable) matter that is captured in the 

front half of EPA test method five, the standard test method for determining particulate 

emissions from boilers. 

The existing control devices for filterable particulate matter on all seven boilers are dry 

electrostatic precipitators (ESPs) with control efficiencies of 99+ percent. Each unit has an 

existing particulate emission limit of 0.1 pounds per million Btu of heat input. 

Recent test results submitted to the Department show the actual emissions from the seven units 

average 0.03 to 0.05 pounds per million Btu of heat input with occasional values approaching 

0.07 pounds per million Btu of heat input. 

Upgrading or replacing existing ESPs could reduce the particulate emission rates to 0.013 to 

0.015 pounds per million Btu of heat input. However, the BART analyses conducted by the 

sources indicate the cost effectiveness in dollars per ton is unreasonable and there is very little 

benefit to visibility in the federal Class I areas.

The existing particulate emissions from all seven boilers are very low, ranging from 74 tons per 

year, 2000-2004 average, at Stanton Station Unit 1 to 589 tons per year, 2000-2004 average, at 

Coal Creek Station Unit 2. The BART screening modeling indicates the maximum visibility 

impact improvement from reducing actual existing emissions levels of approximately 0.03 

pounds per million Btu of heat input to 0.015 pounds per million Btu of heat input at any Class I 

area from any of the seven sources was 0.037 deciviews 98th percentile or less. Detailed 

particulate emissions data and modeling visibility impact improvement data for each source can 

be found in the Department BART determinations in Appendix B. 

The Department has determined that the BART for filterable particulate matter for all seven 

sources is no additional controls and allowable particulate emission rate of 0.1 pounds per 

million Btu of heat input be reduced to 0.07 pounds per million Btu of heat input for five of the 

seven units. The Minnkota Power Cooperative Milton R. Young Station Unit 1 and Unit 2 are 

subject to an EPA/State consent decree for New Source Review violations. The consent decree 

requires filterable particulate emissions not to exceed 0.030 pounds per million Btu of heat input. 

Therefore 0.030 pounds per million Btu of heat input will be the BART limit for these two units. 

Condensable Particulate Matter (PM10)

Condensable particulate matter is made up of both organic and inorganic substances. Organic 

condensable particulate matter will be made up of organic substances, such as volatile organic 

compounds, which are in a gaseous state through the air pollution control devices but will 

eventually turn to a solid or liquid state. The primary inorganic substance expected from the 

boiler is sulfuric acid mist, with lesser amounts of hydrogen fluoride and ammonium sulfate. 
76 

Since sulfuric acid mist is the largest component of condensable particulate matter, controlling it 

will control most of the condensable particulate matter. The options for controlling sulfuric acid 

mist are the same options for controlling sulfur dioxide. These include wet and dry scrubbers. 

Three of the sources have existing wet scrubbers that will be upgraded. Three of the remaining 

four units will be equipped with new wet scrubbers and one with a dry scrubber/baghouse 

system. These technologies will achieve greater than 40-60 percent reduction of sulfuric acid 

mist emissions. Changes that would provide additional reductions are economically infeasible 

considering the minimal improvement in visibility that could be achieved. 

The control of volatile organic compounds at power plants is generally achieved through good 

combustion practices. The Department is not aware of any BACT determination at a power plant 

that resulted in any control technology being used. BACT has been found to be good 

combustion practices which are already in use since it minimizes the amount of fuel to generate 

electricity. 

EPA document AP-42, Compilation of Air Pollutant Emission Factors, indicates the emission 

rate of condensable particulate matter could be expected to be 0.02 pounds per million Btu. This 

emission rate is less than the current emissions of filterable particulate matter and the emissions 

of filterable particulate matter were determined to have a negligible impact on visibility. 

Having considered all the factors, the Department has determined that BART for condensable 

particulate matter is represented by good sulfur dioxide control and good combustion control. 

Since the primary constituent of condensable particulate matter is sulfuric acid mist which is 

controlled proportionately to the sulfur dioxide controlled, the BART limit for sulfur dioxide can 

act as a surrogate for condensable particulate matter along with a requirement for good 

combustion practices. 

BART Modifications Description

A summary description of the BART modifications proposed at each of the seven subject-toBART sources follows: 

Basin Electric Power Cooperative Leland Olds Station Unit 1 and Unit 2 - A wet scrubbing 

system will be installed to remove sulfur dioxide from the flue gas of each unit. Nitrogen oxides 

emissions from Unit 1 will be controlled by basic separated overfire air (SOFA) and selective 

noncatalytic reduction (SNCR). Nitrogen oxides from Unit 2 will be controlled by advanced 

separated overfire air (ASOFA) and selective noncatalytic reduction (SNCR). 

Great River Energy Coal Creek Station Unit 1 and Unit 2 - Sulfur dioxide emissions will be 

controlled by the installation of a coal drying system; the installation of trays or new liquid 

distribution rings (LDRs) and high flow mist eliminators (MEs) in the existing wet scrubbers; the 

elimination of the bypass of the wet scrubbers and the modification of the existing stacks for wet 

operating conditions. Nitrogen oxides emissions will be controlled by the installation of an 

additional level of separated overfire air (SOFA) in each boiler. 
77 

Great River Energy Stanton Station Unit 1 - Sulfur dioxide emissions will be controlled by the 

installation of a spray dryer and fabric filter system (dry scrubber). Nitrogen oxides emissions 

will be controlled by the installation of low-NOx burners plus overfire air plus selective 

noncatalytic reduction (SNCR) technology. 

Minnkota Power Cooperative Milton R. Young Station Unit 1 and Unit 2 - Sulfur dioxide 

emissions will be controlled by the installation of a new wet scrubber on Unit 1 and by 

upgrading the existing wet scrubber on Unit 2. Nitrogen oxides emissions from both units will 

be reduced using advanced separated overfire air (ASOFA) and selective noncatalytic reduction 

(SNCR). 

The control technology to be installed on each source unit is described in more detail in the 

company BART determinations in Appendix C and the Department BART determinations in 

Appendix B. 

7.4.3 Summary of Emission Reductions 

BART for the BART-eligible sources in the State of North Dakota that are significant 

contributors to visibility impairment in a Class I area are shown in Tables 7.3 and 7.4 for sulfur 

dioxide and nitrogen oxides. BART is the emission limit for each pollutant based on the degree 

of reduction achievable through the application of the best system of continuous emission 

reduction, taking into consideration the technology available, the costs of compliance, the energy 

and the non-air quality environmental impacts of compliance, any pollution control equipment in 

use or in existence at the source, the remaining useful life of the source, and the degree of 

improvement in visibility which may reasonably be anticipated to result from the use of such 

technology. The Department BART determination analysis for each BART-eligible source is 

included in Appendix B. 

 

The application of BART to all BART-eligible sources provides an estimated emission reduction 

from the 2000-2004 average baseline emissions of 98,618 tons per year of sulfur dioxide and 

21,137 tons per year of nitrogen oxides. These reductions are shown in Tables 7.3 and 7.4 for 

each source and in total. 

BART for each BART-eligible source was determined using the methodology in the Guidelines 

for BART Determinations Under the Regional Haze Rule. 40 CFR Part 51, Appendix Y. 

7.5 Air Pollution Control Permit to Construct for Subject-to-BART 

Sources 

Section V of Appendix Y to Part 51 - Guidelines for BART Determinations Under the Regional 

Haze Rule requires the State establish enforceable emission limits that reflect the BART 

determinations and require compliance within a given period of time. In particular, the State 

must establish an enforceable emission limit for each subject emission unit at the source and for 

each pollutant subject to review that is emitted from the source. The Department worked closely 
78 

with the staff of the EPA Region 8 Air Programs office to ensure the permit template contents 

and language were acceptable to meet the requirements of Section V. 

The emission limits, monitoring, recordkeeping and reporting requirements specified in the 

Department BART determination for each subject-to-BART source are included in a federally 

enforceable Air Pollution Control Permit to Construct that will be issued by the Department to 

the owner/operator of the facility before the SIP is submitted to EPA. The permits are issued by 

the Department under existing authority pursuant to NDAC Chapter 33-15-14 and Chapter 33-

15-25. 

There are four Permits to Construct, one for both Unit 1 and Unit 2 at the Basin Electric Power 

Cooperative Leland Olds Station, one for both Unit 1 and Unit 2 at the Great River Energy Coal 

Creek Station, one for Unit 1 at the Great River Energy Stanton Station, and one for Unit 1 and 

Unit 2 at the Minnkota Power Cooperative Milton R. Young Station. The four permits are 

included in Appendix D. 

7.5.1 Enforceable Emission Limits 

Enforceable emission limits that reflect the BART determinations are included in each Air 

Pollution Control Permit to Construct as permit condition II.A.1. Conditions for sulfur dioxide 

are in II.A.1.a., nitrogen oxides in II.A.1.b., and filterable (non-condensable) particulate matter in

II.A.1.c. Each Air Pollution Control Permit to Construct is incorporated as a part of this 

Regional Haze SIP. 

As required by Section V of Appendix Y, the limitations for sulfur dioxide and nitrogen oxides 

specify an averaging time of a 30-day rolling average, and contain a definition of “boiler 

operating day” which is any 24-hour period between 12:00 midnight and the following midnight 

during which any fuel is combusted at any time at the steam generating unit. 

7.5.2 Monitoring, Recordkeeping, and Reporting Requirements 

Monitoring, recordkeeping, and reporting requirements have been included in each Air Pollution 

Control Permit to Construct. The owner/operator is required to conduct monitoring, 

recordkeeping and reporting as required by NDAC Chapter 33-15-14-06, Title V Permit to 

Operate and NDAC 33-15-21, Acid Rain Program (40 CFR 72, 75, and 76). The conditions in 

each source’s existing Title V operating permit will be revised as necessary to cover the new 

BART emissions limits as they are included these permits. Monitoring requirements are found in 

permit condition II. A. 4, recordkeeping requirements are found in II.A.5, and reporting 

requirements are found in II. A. 6. 

 
79 

7.5.3 Operating and Maintenance Requirements 

Item 51.308(e)(1)(v) of the EPA BART rule requires that each source subject to BART maintain 

the control equipment and establish procedures to ensure such equipment is properly operated. 

This requirement is also included in the state rules at NDAC 33-15-25-02.3. 

Each Air Pollution Control Permit to Construct has condition II. B. 4 which requires that the 

owner shall at all times, including periods of startup, shutdown, and malfunction, maintain and 

operate the BART unit(s) and all other emission units including associated air pollution 

equipment and fugitive dust suppression operations in a manner consistent with good air 

pollution control practices for minimizing emissions. 

7.5.4 Compliance Date 

The Department is requiring that each source subject to BART shall install and operate BART as 

expeditiously as practicable but in no event later than five years after approval of the 

implementation plan revision by EPA as required by Section V of Appendix Y to 40 CFR Part 

51 and Item 51.308(e)(1)(iv) of the EPA BART Rule. This requirement is also included in the 

State rule as NDAC 33-15-25-02.2. 

This requirement is included as Condition II.A.2 in the Air Pollution Control Permit to Construct 

issued for each source subject to BART. When this implementation plan is approved by EPA, a 

Title V operating permit will be issued for each source incorporating the conditions of the 

Permits to Construct. 
80 

8. Visibility Modeling 

8.1 Introduction

Computer modeling to determine progress with respect to visibility improvement goals was 

conducted in support of this North Dakota Regional Haze SIP. The Regional Haze Rule2 (Rule) 

specifies that modeling must be applied to demonstrate reasonable progress toward the goal of 

achieving natural visibility conditions in each PSD Class I area by 2064. As discussed in Section 

5.4, the uniform rate of progress defines the visibility improvement which would be needed for 

each planning period to achieve natural visibility conditions by 2064. The first planning period 

begins at the end of the baseline (2004) and terminates in 2018. The visibility improvement 

progress needed by 2018 (or 2018 target) is determined by interpolating from the uniform rate of 

progress glide path, as illustrated in Figure 5.5. 

Modeling analyses completed in support of the North Dakota SIP and discussed here address the 

first planning period, and the 2018 target. These analyses assume that the 2018 goal for each 

Class I area is the uniform rate of progress (glide path) target for 2018. The Regional Haze Rule, 

however, gives states the option of establishing reasonable progress goals which are 

independent of the uniform rate of progress. The reasonable progress goals established by a state 

for 2018 will not necessarily equal the uniform rate of progress target for 2018 (see Section 10). 

To demonstrate reasonable progress with respect to visibility goals for the first planning period, 

the Rule specifies that visibility on the 20 percent worst (most impaired) days must improve, 

while visibility on the 20 percent best (least impaired) days must not deteriorate, between the 

base period (2000-2004) and 2018. Computer modeling was used to project future visibility, 

accounting for proposed BART controls and other visibility-affecting emissions 

increases/decreases. Modeling was applied in a relative sense. Baseline and projected future 

emission inventories were modeled to develop a future/baseline prediction ratio (relative 

response factor). The ratio was then applied to baseline monitoring data for visibility-affecting 

species to project future visibility. 

The Western Regional Air Partnership (WRAP) regional planning organization has established a 

Regional Modeling Center (RMC) to assist member states, including North Dakota, with 

modeling to determine status with respect to the 2018 goals. The RMC has applied a chemically 

sophisticated grid model (CMAQ), on a regional basis, to project future visibility in Class I areas 

in the WRAP region3

. The RMC has developed comprehensive base period and future period 

visibility-affecting emission inventories to use with CMAQ, and has performed numerous studies 

 

2 40 CFR 51.308

3

 Tonnesen, G., R. Morris, Z. Adelman, et. al., 2006. 2006 Report for the Western 

Regional Air Partnership (WRAP) Regional Modeling Center (RMC). Western Regional Air 

Partnership, Denver, CO 80202. 
81 

using base period model and monitoring data to evaluate CMAQ performance4. Finally, the 

RMC has applied CMAQ to project 2018 visibility for each Class I area in the WRAP region, 

including the Theodore Roosevelt National Park and Lostwood Wilderness Class I areas in North 

Dakota. 

To supplement work done by the WRAP RMC, the North Dakota Department of Health 

(NDDoH) has conducted further modeling analysis to address 2018 visibility goals for North 

Dakota Class I areas. Though the NDDoH utilized WRAP RMC results in assessing progress 

with respect to visibility goals in North Dakota Class I areas, the NDDoH also recognized it 

would have to develop further modeling capability for visibility projection in order to address 

weight of evidence issues not included in WRAP modeling, such as discounting the impact of 

international sources. In addition, the NDDoH had concerns regarding the spatial resolution of 

the WRAP CMAQ simulations, particularly for large point sources. 

The RMC is applying CMAQ on a national basis using a grid resolution of 36 km, with no 

plume-in-grid treatment. This means that emissions from point sources are immediately mixed 

uniformly throughout a 36 km (square) grid cell volume, which may overstate the dilution of the 

plume, and the speed of chemical reactions for species contained in the plume. This may be 

problematic, especially for sources located relatively near Class I areas. Consequently, the 

contribution of visibility-affecting species from these sources may be misrepresented for both 

base period and future period modeling. This limitation in treatment of point sources is 

recognized in CMAQ documentation5. 

The NDDoH utilized a hybrid modeling approach for determining status with respect to the 

visibility goals. This approach involved nesting the local NDDoH CALPUFF domain within the 

WRAP National CMAQ domain, and applying the Lagrangian CALPUFF model in a 

retrospective sense to more realistically define plume geometry for local point sources. To 

implement the nesting, hourly output concentrations from WRAP CMAQ were used to set hourly 

boundary conditions for CALPUFF. The use of CMAQ output to set CALPUFF boundary 

conditions has been suggested by Escoffier-Czaja and Scire6

. Location of the NDDoH 

CALPUFF domain within the National CMAQ domain is illustrated in Figure 8.1. 

Given limitations in the CALPUFF chemistry for other species, the NDDoH hybrid modeling 

system was used for simulation of SO2-SO4-NOX-HNO3-NO3 chemistry and transport, and thus 

sulfate (SO4) and nitrate (NO3) predictions, only. Results for all other visibility-affecting 

 

4

 See WRAP RMC web site at http://pah.cert.ucr.edu/aqm/308/

5

 EPA, 1999. Science Algorithms of the EPA Models-3 Community Multiscale Air 

Quality (CMAQ) Modeling System. Office of Research and Development, Washington DC 

20460. 

6

 Escoffier-Czaja, C., and J. Scire, 2005. Comments on the Computation of Nitrate Using 

the Ammonia Limiting Method in CALPUFF. Appendix A, Draft Protocol for the Application 

of the CALPUFF Model for Analyses of Best Available Retrofit Technology (BART), VISTAS. 
82 

Figure 8.1 

WRAP CMAQ Domain and NDDoH CALPUFF Domain
83 

species, including organic carbon mass (OMC), elemental carbon (EC), fine particulate (Soil), 

and coarse particulate (CM), were obtained directly from the CMAQ output for the grid cell 

containing each subject Class I area IMPROVE monitor. CMAQ output was combined with 

CALPUFF results for sulfate and nitrate in order to perform necessary light extinction 

calculations. In this way, the NDDoH benefits from the sophistication of the RMC approach for 

other particulate components, which reflect a very small percentage of emissions from the local 

point sources of concern. 

WRAP and NDDoH protocols for modeling visibility progress goals generally adhere to EPA 

Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality 

Goals for Ozone, PM2.5, and Regional Haze7

. An evaluation of modeling system performance 

was conducted first. Then baseline (2000-2004) and future (2018) emission scenarios were 

modeled in order to develop relative response factors (RRFs). Finally, RRFs were applied to 

baseline IMPROVE monitoring data to project future visibility in North Dakota Class I areas. 

Class I areas in North Dakota include the three units of Theodore Roosevelt National Park 

(TRNP), and the Lostwood Wilderness Area (LWA). IMPROVE monitors are located at the 

TRNP South Unit and LWA, only. Therefore, these two Class I areas were the focus of the 

modeling analyses. Locations of North Dakota Class I areas, IMPROVE monitor sites, and 

larger visibility-affecting sources are depicted in Figure 8.2. 

While this presentation (Section 8) addresses both WRAP and NDDoH visibility modeling 

analyses, focus is on the NDDoH modeling as WRAP procedures are extensively documented 

elsewhere. The WRAP protocol for regional haze visibility modeling is summarized in 2006 

Report for the Western Regional Air Partnership (WRAP) Regional Modeling Center (RMC)8. 

The NDDoH protocol for regional haze progress goal modeling is attached as Appendix E to this 

document. 

8.2 Regional Haze Metrics 

To address progress in visibility improvement, modeling is used to provide mass concentrations 

of visibility-affecting species. These concentrations are translated into light extinction using the 

IMPROVE algorithm. Finally, light extinction is converted to deciviews to accommodate 

comparison with visibility goals. Use of the deciview metric to assess baseline visibility, natural 

visibility, and improvement in visibility was discussed in Section 5. 

Calculation of light extinction from visibility-affecting aerosol concentrations for the WRAP 

 

7

 EPA, 2007. Guidance on the Use of Models and Other Analyses for Demonstrating 

Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze. Publication No. EPA 

454/B-07-002, Office of Air Quality Planning and Standards, Research Triangle Park, NC 

27711. 

8

 See supra note 3. 
84 

Figure 8.2 

Larger Point Sources and PSD Class I Areas 

3

5 1

6

7 2

9

10

11

12 1314

4

8

0 100 200 300 

 Point Source Ke 1 Coal Creek Station 2 Leland Olds Station Stanton Station 3 Milton R Young Sta 4 Heskett Station 5 Antelope Valley Sta Great Plains Synfue 6 Coyote Station 7 Little Knife Gas Pla 8 Tioga Gas Plant 9 Colstrip Station10 Celp Boiler11 Lewis & Clark Stati12 Poplar River Station13 Boundary Dam Sta14 Shand Station 

LostwoodWilderness Area

TRNP South Unit

TRNP North Unit

TRNP Elkhorn Ranch Unit

PSD Class I Area

 Bismarck

NDDModeDom

IMPROVE Monitor Site
85 

RMC and NDDoH regional haze analyses is based on the “new” IMPROVE algorithm9. This 

new system was seen to reduce bias associated with use of the “old” IMPROVE algorithm, and 

was adopted as an alternative by the IMPROVE Steering Committee in December 2005. The 

new algorithm splits ammonium sulfate, ammonium nitrate, and organic mass concentrations 

into two fractions: small and large. The new algorithm for light extinction is: 

bext = 2.2 x fs(RH) x [small amm. sulfate] + 4.8 x fL(RH) x [large amm. sulfate] 

+ 2.4 x fs(RH) x [small amm. nitrate] + 5.1 x fL(RH) x [large amm. nitrate] 

+ 2.8 x [small organic mass] + 6.1 x [large organic mass] 

+ 10.0 x [elemental carbon] 

+ 1.0 x [fine soil] 

+ 1.7 x fss(RH) x [sea salt] 

+ 0.6 x [coarse mass] 

+ Rayleigh scattering (site-specific) 

+ 0.33 x [NO2 (ppb)] 

where 

bext = light extinction in units of inverse megameters (Mm-1), 

fs(RH) = function of relative humidity for small size fraction, 

 fL(RH) = function of relative humidity for large size fraction, 

fss(RH) = function of relative humidity for sea salt, 

all species concentrations (with exception of NO2) are provided in ug/m3

, 

amm. sulfate / amm. nitrate means ammonium sulfate / ammonium nitrate. 

Apportionment of total sulfate concentrations into small and large size fractions is defined: 

 [large amm. sulfate] = [total amm. sulfate]2 , for [total amm. sulfate] < 20 ug/m3 

 20 ug/m3 

[large amm. sulfate] = [total amm. sulfate], for [total amm. sulfate] > 20 ug/m3 

[small amm. sulfate] = [total amm. sulfate] - [large amm. sulfate] 

Similar equations are used to apportion total ammonium nitrate and total organic matter 

concentrations into small and large size fractions.

A solution for the NO2 term in the extinction algorithm is problematic as the IMPROVE network 

does not include NO2 sampling. However, WRAP and the NDDoH have determined that the 

NO2 term has very little impact on total light extinction. A review of observational NO2 data 

from an NDDoH monitoring site in Theodore Roosevelt National Park revealed that readings 

were less than the minimum detectable level of 2.0 ppb more than 80% of the time in 2002. 

 

9

 IMPROVE, 2005. New IMPROVE algorithm for estimating light extinction approved 

for use. The IMPROVE Newsletter, Volume 14, Number 4. Air Resource Specialists, Inc., Fort 

Collins, CO 80525. 
86 

Accordingly, both WRAP and the NDDoH have omitted the NO2 term in analyses for future 

visibility. 

The IMPROVE network does include sampling for sea salt. But monitored values are very low 

in North Dakota Class I areas. Further, the WRAP RMC found that the CMAQ model was not a 

reliable predictor for sea salt. Therefore, WRAP has omitted sea salt as a modeled species, and 

both WRAP and the NDDoH are assuming a relative response factor of 1.0. 

Light extinction is converted to deciview using the following relationship: 

dv = 10 x ln(bext / 10) 

where 

dv = deciview, 

bext = light extinction in units of inverse megameters (Mm-1). 

Visibility goals are generally expressed as deciviews. 

8.3 Projection of Future Visibility 

Methodology for WRAP and NDDoH projection of future visibility is based on EPA Guidance 

on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for 

Ozone, PM2.5, and Regional Haze10. The guidance proposes a relative modeling approach to 

project future (2018) visibility, in order to determine compliance status with respect to visibility 

goals at Class I areas. Implementation of the relative modeling approach relies on relative 

response factors (RRFs) which represent the modeled impact of the future (visibility affecting) 

source emissions inventory divided by the modeled impact of the baseline source inventory at 

Class I areas. These RRFs are applied to baseline IMPROVE monitoring data to project future 

visibility for each Class I area. 

Per the Regional Haze Rule, projection of future visibility is needed for the 20% worst and 20% 

best visibility days at each Class I area. The 20% worst days and 20% best days are determined 

from Class I area IMPROVE monitoring data for each year for the 5-year baseline period 2000-

2004. Because IMPROVE sampling occurs once every three days, the maximum number of 

monitored days per year would be 122, and the maximum number of 20% worst or best days per 

year would be 24. 

According to the EPA guidance, worst-day RRFs are developed by comparing the future average 

predicted mass concentration for 20% worst days to the baseline average predicted mass 

concentration for 20% worst days, for each visibility affecting species. The 20% worst modeled 

days are temporally consistent with the worst monitored days, which requires that modeling is 

 

10 See supra note 7. 
87 

based on 2000-2004 meteorological data (i.e., meteorological data used for modeling represents 

the same period as baseline monitoring), if all five years are modeled11. For each visibility 

affecting species (SO4, NO3, OMC, EC, Soil, CM), a single RRF is developed for each Class I 

area. The RRF is calculated by dividing the predicted future concentration averaged over all 

worst days by the predicted baseline concentration averaged over all worst days. Then, future 

concentrations for each species are projected by multiplying the RRF by the observed species 

concentration on each of the baseline worst days. The same process is used to develop best-day 

RRFs, and project best-day concentrations. 

The RRF approach can be expressed mathematically: 

 _ _ 

X

i,j

of = Xi,job (RRFi

) = Xi,j

ob (Xipf /Xipb) 

 

where 

 Xi,j

of represents projected observed future concentration for species i on day j (each of 

20% worst days for each baseline year), 

 Xi,j

ob represents observed baseline (IMPROVE data) concentration for species i on day j 

(each of 20% worst days for each baseline year), 

 _ 

X

i

pf represents average predicted future concentration for species i (average of 20% 

worst days), 

 _ 

X

i

pb represents average predicted baseline concentration for species i (average of 20% 

worst days), 

 

 RRFi

 represents the relative response factor for species i. 

The same system is applied to project 20% best day concentrations. 

The set of projected future worst-day concentrations (including all species above) is converted to 

light extinction through application of the IMPROVE equation (Section 8.2) for each day, then 

daily light extinction is converted to deciview for each day. Finally, projected daily deciview is 

averaged over all worst-case days for each year, then averaged over all years to produce the 

single future value needed to address visibility goals for each Class I area. This procedure is 

repeated for projected future best-day concentrations. 

Both the WRAP RMC and the NDDoH followed this general methodology for projecting future 

visibility-affecting species concentrations, and subsequently, worst day and best day future 

deciview. 

 

11 Because of the resource demands of the CMAQ model, the WRAP RMC limited their 

visibility modeling analysis to the use of 2002 meteorology, only. Consequently, the NDDoH 

analysis was likewise limited to 2002 meteorology. The RRFs developed from modeling based 

on 2002 meteorology were then applied to all five years of monitoring data for future projection. 
88 

8.4 WRAP Visibility Modeling Methodology 

The Western Regional Air Partnership (WRAP) is a Regional Planning Organization (RPO) 

representing the western states, including North Dakota. WRAP is one of five RPOs which 

together cover all states in the country. These RPOs are responsible for assisting states in the 

development of State Implementation Plans (SIPs) and Tribal Implementation Plans (TIPs) to 

address requirements of the Regional Haze Rule, and to assist with other air quality issues. 

WRAP has established a Regional Modeling Center (RMC) to conduct visibility modeling and 

provide technical modeling guidance to support regional haze SIPs and TIPs for western states. 

This RMC reflects a consortium of technical expertise from University of California Riverside, 

University of North Carolina, and ENVIRON International Corporation. With funding from the 

western states, the RMC conducted an extensive modeling effort to project future visibility for 

each Class I area in the western United States, including the Class I areas in North Dakota. 

WRAP RMC visibility modeling methodology is largely described in Final Report for the 

Western Regional Air Partnership (WRAP) Regional Modeling Center (RMC) for the Project 

Period March 1, 2004 through February 28, 200512 and 2006 Report for the Western Regional 

Air Partnership (WRAP) Regional Modeling Center (RMC)13. Specific documentation for most 

recent baseline and future modeling cases is provided in 2002 Planning Simulation Version D14

and 2018 Preliminary Reasonable Progress Simulation Version A15, respectively. These and 

other resources can be obtained from the WRAP web site at http://pah.cert.ucr.edu/rmc. 

Primary modeling tools used by the WRAP RMC include: 

• the Fifth-Generation Pennsylvania State University/National Center for Atmospheric 

Research (PSU/NCAR) Mesoscale Model (MM5) meteorological modeling system, 

• the Sparse Matrix Operator Kernel Emissions (SMOKE) emissions modeling system, 

• the Community Multiscale Air Quality (CMAQ) air quality modeling system, and 

 

 

12 Tonnesen, G., R. Morris, Z. Adelman, et. al., 2005. Final Report for the Western 

Regional Air Partnership (WRAP) Regional Modeling Center (RMC) for the Project Period 

March 1, 2004, through February 28, 2005. Western Regional Air Partnership, Denver, CO 

80202. 

 

13 See supra note 3. 

 

14 WRAP, 2008. 2002 Planning Simulation Version D. Western Regional Air 

Partnership, Denver, CO 80202. 

 

15 WRAP, 2008. 2018 Preliminary Reasonable Progress Simulation Version A. Western 

Regional Air Partnership, Denver, CO 80202. 
89 

• the PM Source Apportionment Technology extension (PSAT) of the Comprehensive Air 

Quality Model (CAMx). 

The modeling domain established by the RMC includes all of the contiguous United States, and 

parts of Mexico and Canada (see Figure 8.1). The RMC used the MM5 model to develop the 

meteorological fields necessary for execution of CMAQ and PSAT within the domain. Grid cell 

size was specified as 36 kilometers in the horizontal direction, and vertical structure was defined 

by 19 layers of varying depth. Because of resource and time constraints (primarily related to 

CMAQ and PSAT), preparation of meteorological data was limited to Year 2002 of the baseline 

period. 

Emissions inventory development for WRAP RMC visibility modeling relied primarily on the 

EPA National Emissions Inventory (NEI), and information collected from states and other RPOs. 

County emissions data for visibility affecting species, as well as all other species necessary to 

execute the chemistry in CMAQ and PSAT, were collected and processed into the format 

required by SMOKE. Then SMOKE was executed to apportion emissions to the appropriate grid 

cell and vertical layer within the modeling domain, on an hourly basis. Where appropriate, 

temporal emissions patterns were applied during the execution of SMOKE. All source 

categories shown in Table 8.1 were accounted for in the processing of emissions data in 

SMOKE. 

 

Table 8.1 

WRAP RMC Source Categories

 

Source Category 

Stationary Point Sources 

Stationary Area Sources 

On-Road Mobile 

Off-Road Mobile 

Biogenic 

Oil & Gas 

Offshore Platforms 

Offshore Shipping 

Road Dust 

Fugitive Dust 

Wind-Blown Dust 

Wild Fires 

Natural Fires 

Anthropogenic Fires 

Agricultural Ammonia 

The WRAP RMC has included three basic emissions cases in their visibility modeling, for 

performance evaluation and the development of relative response factors. 

• Case BASE02b reflects year 2002 emissions which are concurrent with the year 2002 

meteorology. WRAP used this case for performance evaluations. 

• Case PLAN02d reflects a composite interpretation of emissions for the 2000-2004 period. 

WRAP used this case for the baseline period to generate relative response factors. 
90 

• Case PRP18a (Preliminary Reasonable Progress 2018 Scenario A) reflects projected year 

2018 emissions. Case PRP18a represents base period emissions projected to 2018, 

accounting for estimates of the effect of BART controls, and assuming other growth and 

control factors. WRAP used this case for the future period to generate relative response 

factors. 

Note that WRAP recently completed modeling for an updated Case PRP18b future emissions 

scenario, as discussed in Section 6. Because NDDoH visibility modeling was initiated and 

largely completed well before the WRAP PRP18b emissions inventory and modeling results 

were available, however, Case PRP18b is not included in the visibility modeling results 

discussed in this SIP. For North Dakota sources, Case PRP18b reflects only a slight decrease in 

emissions relative to Case PRP18a. Therefore, results and conclusions of the visibility analyses 

reported here would not be meaningfully changed with the use of Case PRP18b emissions. 

To define boundary conditions for the WRAP modeling domain, species concentrations for the 

perimeter of the domain were derived from the global GEOS-CHEM model. 

Before beginning production modeling for development of RRFs, the WRAP RMC conducted 

extensive performance evaluations for both CMAQ and CAMx/PSAT. These performance 

evaluations were used to refine emissions inventories and other input conditions. CMAQ was 

subsequently applied to baseline (PLAN02d) and future (PRP18a) emissions inventories to 

generate RRFs and project future visibility in Class I areas. Development of RRFs and 

projection of future visibility followed default EPA methodology16, as outlined in Section 8.3. 

Finally, PSAT was applied to assess source and species attribution for projected visibility 

impacts. 

Results of WRAP RMC modeling for North Dakota Class I areas are reviewed in Section 8.6.2. 

 

8.5 NDDoH Visibility Modeling Methodology 

In support of the North Dakota Regional Haze SIP, the North Dakota Department of Health 

(NDDoH) conducted refined progress goal visibility modeling to supplement and update the 

modeling conducted by WRAP RMC. The NDDoH developed an in-house modeling capability 

to address weight of evidence issues, and concerns regarding the resolution of the WRAP 

CMAQ simulations, particularly as applied to large point sources located near Class I areas. As 

discussed in Section 8.4, WRAP RMC modeling focused on the default EPA methodology for 

regional haze17, and did not address weight of evidence issues such as discounting the effect of 

 

16 See supra note 7. 

17 See supra note 7. 

 
91 

international source emissions. The RMC applied CMAQ on a regional basis using a grid 

resolution of 36 km, with no plume-in-grid treatment. 

The NDDoH regional haze modeling constitutes a hybrid approach as it involved nesting the 

local NDDoH CALPUFF domain within the WRAP National CMAQ domain, and applying the 

Lagrangian CALPUFF model in a retrospective sense to more realistically define plume-receptor 

geometry for local point sources. To implement the nesting, hourly output concentrations from 

WRAP CMAQ modeling were used to set hourly boundary conditions for CALPUFF. CMAQ 

output used to set CALPUFF boundary conditions reflects corresponding WRAP cases for 

baseline and future emission inventories. 

The hybrid modeling approach was used for simulation of SO2-SO4-NOX-HNO3-NO3 chemistry 

and transport and, thus, sulfate and nitrate predictions, only. RRFs and projected future 

concentrations for other visibility affecting species, including organic carbon (OMC), elemental 

carbon (EC), fine particulate (Soil), and coarse mass (CM), were taken directly from the WRAP 

RMC results for North Dakota Class I areas. The deferral to WRAP CMAQ results for these 

species is based on limitations in the CALPUFF chemistry, and the fact that larger point sources 

located relatively near North Dakota Class I areas, where CMAQ resolution is a concern, are 

primarily emitters of SO2 and NOX. Further, IMPROVE measurements at North Dakota Class I 

areas indicate that sulfate and nitrate are primary contributors to light extinction on most worstcase days. Individual species contribution to light extinction for worst-case days at Theodore 

Roosevelt National Park is illustrated in Figure 8.3. Therefore, weight of evidence assessments 

should be most affected by changes in sulfate and nitrate concentrations. 

The NDDoH used the hybrid modeling system in a supportive sense to add value to the original 

WRAP CMAQ modeling results for sulfate and nitrate. The hybrid system was used to adjust 

WRAP CMAQ results in order to offset coarseness in the CMAQ resolution for large local point 

sources, and in order to discount the effect of international (Canadian) sources. Procedures for 

adjusting WRAP CMAQ results are discussed in Section 8.5.6. 

For hybrid modeling, the NDDoH used the State’s point source inventory for SO2 and NOX, and 

has imported WRAP RMC data for all other source categories (and for point source SO4 and 

NO3) to apportion emissions within the CALPUFF domain. WRAP used the SMOKE emissions 

model18 to develop the emissions inventory for CMAQ. The NDDoH has obtained and 

processed WRAP SMOKE output to define area source emissions for the CALPUFF domain. 

The CALPUFF area source emissions inventory includes the species SO2, SO4, NOX, and NO3. 

In addition, primary SO4 and NO3 emissions data were extracted from the SMOKE inventory for 

point sources, and apportioned to the CALPUFF domain as area sources. WRAP CMAQ source 

categories included in the CALPUFF emissions inventory are outlined in Table 8.2. Note that 

WRAP SMOKE output did not contain all four species for some source categories. 

 

18 University of North Carolina, 2007. SMOKE User’s Manual. The Institute for the 

Environment, University of North Carolina. 
92 

Figure 8.3 

IMPROVE 20% Worst Days – TRNP 2000 

0%

10%20%30%40%50%60%70%80%90%

100%

1 15 19 29 9 12 16 11 19 22 17 5 9 19 23 26 23 1 1 1 1 2 2 2 3 4 4 5 8 8 8 8 8 11 

Contribution to Extinction 
93 

Table 8.2 

 CMAQ-CALPUFF Area Source Categories

Source Category Species Included

All Fires 

Biogenics 

Fugitive Dust 

On-Road Mobile 

Off-Road Mobile 

Road Dust 

Oil & Gas 

Conventional Area 

Point 

SO2, NOX, SO4, NO3

NOX

SO4, NO3

SO2, NOX, SO4

SO2, NOX, SO4, NO3

SO4, NO3

SO2, NOX

SO2, NOX, SO4, NO3

SO4, NO3

The interfacing of CMAQ and CALPUFF modeling systems for the NDDoH hybrid approach is 

illustrated in the flow diagram in Figure 8.4. Necessary software for processing input data and 

projecting future visibility has been developed by the NDDoH. 

To confirm effectiveness of the hybrid CMAQ-CALPUFF modeling system, the NDDoH 

conducted a performance evaluation prior to commencing production modeling. The evaluation 

focused on performance of the hybrid system for sulfate and nitrate concentrations, and 

prompted changes to some model inputs to improve performance relative to observations. 

CMAQ performance evaluations conducted by WRAP RMC for OMC, EC, Soil, and CM 

species are also relevant. The NDDoH Performance evaluation is discussed in Section 8.6.1. 

The NDDoH has obtained CMAQ emissions input data (SMOKE output) and hourly 

concentration output files from the WRAP RMC. CMAQ data used to set CALPUFF boundary 

conditions and develop the CALPUFF area source inventory will be based on WRAP cases 

BASE02b, PLAN02d, and PRP18a, for performance evaluation, baseline case, and future case 

modeling, respectively. These WRAP scenarios are described as follows. 

• Case BASE02b reflects CMAQ modeling using year 2002 emissions with year 2002 

meteorology. The NDDoH used this case for performance evaluations. 

• Case PLAN02d reflects CMAQ modeling using composite 2000-2004 emissions with 2002 

meteorology. The NDDoH used this case for the base period to generate relative response 

factors. 

• Case PRP18a (Preliminary Reasonable Progress 2018 Scenario A) reflects CMAQ modeling 

using projected year 2018 emissions with 2002 meteorology. Case PRP18a represents base 

period emissions projected to 2018, accounting for estimates of the effect of BART controls, 

and assuming other growth and control factors. The NDDH used this case for the future 

period to generate relative response factors. 
94 

SMOKE

Emissions

Processor

Emissions

Data

CMAQ

Model

Emissions

Processor

(SMOKE2PUFF)

CALPUFF 

Domain

Area Emissions

(SO2, NOX, SO4, NO3)

Hourly

Predicted

Conc.

Conc.

Processor

(CMAQ2PUFF)

Boundary

Conditions

(SO2, NOX, HNO3,

SO4, NO3)

C

Pro

(CMAQ

CALPUFF

Domain

Pt Emissions

(SO2,NOX)

CALPUFF

Model

24-hr

Predicted Conc.

(SO4, NO3)

Visibility

Calculation

Predi

(OMC, 

NDDH

Database

Figure 8.4 

Hybrid Interfacing of CMAQ and CALPUFF Modeling Systems 
95 

Again, WRAP recently completed modeling for an updated Case PRP18b future emissions 

scenario, as discussed in Section 6. Because NDDoH visibility modeling was initiated and 

largely completed well before the WRAP PRP18b emissions inventory and modeling results 

were available, however, Case PRP18b is not included in the visibility modeling results 

discussed in this SIP. For North Dakota sources, Case PRP18b reflects only a slight decrease in 

emissions relative to Case PRP18a. Therefore, results and conclusions of the visibility analyses 

reported here, although conservative, would not be meaningfully changed with the use of Case 

PRP18b emissions. 

The modeling system, emissions inventory, other model inputs, and procedures for the NDDoH 

regional haze modeling analysis are discussed in following Sections 8.5.1 through 8.5.6. A 

detailed, step-by-step outline of NDDoH visibility modeling procedure is also provided in 

Appendix E of this report. 

Results of the NDDoH hybrid visibility modeling for North Dakota Class I areas are reviewed in 

Section 8.6. 

8.5.1 Hybrid Modeling System 

For sulfate and nitrate predictions, the NDDoH applied the CALPUFF model, using regional 

WRAP CMAQ output concentrations to set boundary conditions for the CALPUFF domain. The 

CALPUFF computer modeling system includes the CALMET meteorological model19, the 

CALPUFF dispersion/chemistry model20, and the POSTUTIL and CALPOST post processing 

programs. POSTUTIL implements the ammonia limiting method, which provides an adjustment 

to avoid overstating available ammonia for NOx to NO3 conversion chemistry in CALPUFF. In 

the NDDoH implementation of the CALPUFF system for production visibility modeling, the 

CALPOST processor was replaced with CALHAZE, a module which directly processes relative 

response factors and projects future visibility, using hourly output from CALPUFF (POSTUTIL) 

baseline and future model runs. 

With the exception of CALHAZE (developed by NDDoH), CALPUFF and associated software 

was developed and is maintained by TRC Corporation (previously by Earth Tech, Inc.). The 

versions of CALPUFF and associated programs which the NDDoH utilized for regional haze 

modeling are summarized in Table 8.3. 

 

19 Earth Tech, Inc., 2000. A User’s Guide for the Calmet Meteorological Model. Earth 

Tech, Inc., Concord, MA 01742. 

 

20 Earth Tech, Inc., 2000. A User’s Guide for the Calpuff Dispersion Model. Earth Tech, 

Inc., Concord, MA 01742. 
96 

 Table 8.3 

 CALPUFF System Versions 

 Applicable For Regional Haze Modeling

Program Version Level 

CALMET 5.8 70623 

CALPUFF 5.8 70623 

POSTUTIL 1.56 70627 

The meteorological/computational modeling domain used by the NDDoH for CALPUFF 

visibility modeling is illustrated in Figure 8.5. Dimensions of the domain are 639 kilometers 

east-west by 459 kilometers north-south, with a horizontal grid cell size of 3 kilometers. In the 

vertical, the domain is defined by twelve vertical layers. The domain is sized and positioned to 

encompass all large visibility-affecting point sources located within 250 km of North Dakota 

Class I areas. Because the domain is relatively large for CALPUFF modeling, all location 

coordinates are based on the Lambert Conformal map projection to mitigate distortions due to 

the earth’s curvature. 

8.5.2 CALMET Input 

Input requirements for the CALMET model include various meteorological and geophysical data 

sets, and a control input file with appropriate settings. Required meteorological data include 

surface, upper-air, and precipitation observations, and mesoscale model output data fields. 

Geophysical input data include terrain elevation and land-use data. Though CALMET may be 

run with mesoscale model meteorological data, alone (i.e., no observations), the EPA modeling 

guideline21 recommends “blending” observations with the mesoscale model fields. Therefore, 

the NDDoH included surface and upper-air observations in a blended approach. 

Because WRAP RMC modeling was limited to the single year 2002 meteorology due to resource 

limitations, the NDDoH hybrid approach was necessarily limited to the same single year of 

meteorology. 

 

21 CFR, 2005. EPA Guideline on Air Quality Models. 40 CFR (Code of Federal 

Regulations) Part 51, Appendix W. 
97 

Figure 8.5 

CALPUFF 3-km Meteorological/Computational Grid 

North Dakota

Montana

Canada

South Dakota

459 km

639 km
98 

8.5.2.1 Meteorological Data 

8.5.2.1.1 Mesoscale Model Data 

NDDoH mesoscale model wind fields used with CALMET are based on the National Center for 

Environmental Predictions (NCEP) Rapid Update Cycle (RUC) forecast model. Mesoscale 

model fields in the MM5.DAT format required by CALMET were developed by a contractor22. 

The contractor obtained and archived RUC hourly initial analyses from NCEP for years 2000 

through 2002. Resolution of these initial analyses was 40 km. The contractor used the ARPS 

Data Assimilation System (ADAS) to enhance resolution to 10 km, and converted the resultant 

hourly wind fields to the MM5.DAT format recognized by CALMET. The domain of these 

hourly wind fields is consistent with the CALMET/CALPUFF domain used by NDDoH (Section 

8.5.1). 

In the process of model performance evaluation, the NDDoH also tested the hybrid modeling 

system with the 2002 36-km MM5 data set prepared by the WRAP RMC for CMAQ modeling. 

Hybrid model performance was similar using either MM5 or RUC mesoscale data. 

8.5.2.1.2 Surface Observations 

Concurrent surface observations for 2002 were obtained in surface hourly abbreviated format 

from the National Climatic Data Center (NCDC). Data were obtained for 40 ASOS and manual 

stations located within or near the NDDoH CALMET/CALPUFF domain. The ASOS/manual 

observations reflect data from stations operated by the National Weather Service, Federal 

Aviation Administration, U.S. Air Force, and Environment Canada. Locations of these stations 

are shown in Figure 8.6. 

To compensate for well-documented deficiencies in ASOS cloud data above 12,000 feet, 

NDDoH also obtained concurrent GOES ASOS satellite cloud data for all selected surface 

stations. The satellite hourly observations included cloud amount (sky cover) and cloud height 

(ceiling height) data above 12,000 feet, and were therefore used to supplement the ASOS 

observations. 

NDDoH prepared custom software to merge the ASOS and satellite data. Earth Tech utility 

software was then used to quality assure merged data, and convert to the format required by 

CALMET (SURF.DAT). Standard methods were applied to provide substitutions for missing 

 

22WindLogics, 2004. RUC Analysis-Based CALMET Meteorological Data for the State 

of North Dakota. WindLogics, Inc., St. Paul, MN 55108. 
99 

Figure 8.6 

CALMET Surface / Upper Air Meteorological Stations

BIS

FAR

DVL RDRGFK

DIK

JMS

MIB

MOT ISN

N60

GGW

GDV

MLS

BIL

SDY

OLF

JDN

HON

RAP

ABR

PIR

2WX MBG

SHR

GCC

YBR

YEN

YQR

YWG

Surface Station

Surface + Upper-air Station
100 

data.23,24 The occurrence of missing data elements in the surface observations was generally 

very limited, and within the tolerances suggested by EPA. 

8.5.2.1.3 Upper-Air Observations 

Upper-air observations for 2002 were obtained from NOAA’s Earth Systems Research 

Laboratories (ESRL) in Boulder, Colorado. Upper-air sounding files were downloaded from the 

website (www.fsl.noaa.gov) in the original FSL format, which is accepted for CALMET input as 

the option “NCDC CD-ROM”. Data were obtained for six upper-air stations (NWS) located 

within or near the NDDoH CALMET/CALPUFF domain. Locations of these stations are also 

shown in Figure 8.6. 

Processing of the upper-air data for CALMET input involved using Earth Tech utility software, 

running custom software written by NDDoH staff, and manual editing of data files. The main 

Earth Tech program quality checked the upper-air data files, output error messages to identify 

problems in the data to be corrected by the user, and converted the data to the format required by 

CALMET. The NDDoH custom software performed additional quality checks, and, combined 

with manual editing of data files, corrected additional errors or problems in the data and filled in 

for missing data when necessary. Substitutions for missing data generally followed standard 

EPA guidance. 22,23 Upper-air soundings were processed up to the 500-mb level to accommodate 

mixing heights up to 4000 meters above ground level at Rapid City, South Dakota. In addition, 

the main Earth Tech processing program had to be modified slightly (corrected) to correctly read 

longitude for Glasgow, Montana. 

 

8.5.2.1.4 Precipitation Data 

Hourly precipitation data for 2002 were obtained from NCDC in TD-3240 format. Data were 

included for 93 NWS hourly recording stations located within or near the NDDoH 

CALMET/CALPUFF modeling domain. Location of these stations is shown in Figure 8.7. 

Earth Tech utility software was employed to quality assure the TD-3240 data, and process it into 

the format required by CALMET (PRECIP.DAT). No substitutions were made for missing data, 

because CALMET substitutes internally from the nearest available station, and the station 

resolution was relatively good (Figure 8.7). 

 

23Atkinson, D., and R. F. Lee, 1992. Procedures for Substituting Values for Missing 

NWS Meteorological Data for Use in Regulatory Air Quality Models. 

24 EPA, 1987. On-Site Meteorological Program Guidance for Regulatory Modeling 

Application. Office of Air Quality Planning and Standards, Research Triangle Park, NC 27711. 
101 

Figure 8.7 

CALMET Precipitation Stations
102 

8.5.2.2 Geophysical Data 

CALMET requires specification of terrain elevation, and parameters related to the land-use 

profile, for each grid cell in the modeling domain. The NDDoH derived terrain elevations from 

United States Geological Survey (USGS) GTOPO30 data sets for North America central and 

mountain zones. Land-use profiles were derived from the USGS Global Data Set for North 

America. 

Using CALMET utility software, all gridded terrain and land-use data were processed into the 

single geophysical file (GEO.DAT) required by CALMET. NDDoH assumed default values 

relating surface roughness length, albedo, Bowen ratio, soil heat flux, and leaf area index to landuse type. 

8.5.2.3 CALMET Control File Settings 

CALMET control file settings used for processing year 2002 meteorological data for visibility 

analyses are generally consistent with guidance from the Interagency Workgroup on Air Quality 

Modeling (IWAQM)25. To the extent applicable, the settings are also consistent with the North 

Dakota alternative protocol for PSD Class I increment analyses26

. 

IWAQM recommendations for CALMET control file variable settings fall into two categories. 

IWAQM-defined variables are those for which IWAQM provides a default value as a general 

recommendation for all analyses. User-defined variables are those where IWAQM recognizes 

the input value will need to be tailored for a given application, and default values are therefore 

not provided. 

For visibility analyses, the NDDoH has established appropriate settings for user-defined 

variables, and has determined the need to adjust a limited number of IWAQM-defined variables 

from recommended values, as discussed below. The CALMET control file user-defined settings, 

as well as the IWAQM-defined settings which have been adjusted by NDDoH, are summarized 

in Table 8.4. IWAQM-defined settings adjusted by NDDoH have a shaded background in the 

Table. 

 

25 EPA, 1998. IWAQM Phase 2 Summary Report and Recommendations for Modeling 

Long Range Transport Impacts. Publication No. EPA-454/R-98-019, Office of Air Quality 

Planning and Standards, Research Triangle Park, NC 27711. 

26 NDDoH, 2005. A Proposed Alternative Air Quality Modeling Protocol to Examine the 

Status of Attainment of PSD Class I Increment. North Dakota Department of Health, Bismarck, 

ND 58506. 

 
103 

Most of the user-defined settings are intuitive, related to parameterization of the meteorological 

grid used with CALMET, as previously discussed. The remaining user-defined variables, 

(RMAX1, RMAX2, RMAX3, TERRAD, R1, R2) control the influence of mesoscale model data, 

station observations, and terrain features in development of the final wind field. Settings for 

these variables are based on the NDDoH alternative protocol for PSD Class I increment analyses. 

NDDoH settings for IWAQM-defined variables are consistent with IWAQM recommendations, 

with limited exceptions as established in the alternative protocol for PSD Class I increment 

analyses. Because the use of mesoscale meteorological data is now being generally 

recommended for long-range modeling analyses, the IPROG variable has been changed from 0 

to 14, which reflects use of MM5 format data (in this case RUC data) as the initial guess wind 

field. The ZUPWND setting has been changed for consistency with default values in recent 

versions of CALMET (the IWAQM setting reflected defaults for an older version of CALMET). 

Based on visual feedback testing, IWAQM settings for variables related to spatial averaging of 

mixing heights, MNMDAV and ILEVZI, were adjusted to provide averaging over a larger area. 

Because the NDDoH CALMET/CALPUFF modeling domain extends into the western part of 

the upper Great Plains, maximum mixing height settings (ZIMAX/ZIMAXW) were increased 

from 3000 to 4000 meters to be consistent with maximum mixing heights reported for this 

region.27 Note that the CALMET BIAS factors have no effect when mesoscale data are used as 

the initial guess wind field. 

8.5.3 CALPUFF Input

Along with the CALMET-processed meteorological data, CALPUFF input requirements for 

NDDoH hybrid visibility modeling include emissions and stack data, background ozone data, 

background ammonia data, receptor locations, boundary conditions, and input control file 

settings. These CALPUFF input requirements are discussed here. 

 

27Holzworth, 1972. Mixing Heights, Wind Speeds, and Potential for Urban Air Pollution 

Throughout the Contiguous United States. EPA Publication No. AP-101, Office of Air 

Programs. 
104 

Table 8.4 

 User-Defined and Non-IWAQM Settings 

 for CALMET Control File* 

Variable Description Value

NSSTA No. of surface stations 40 

NUSTA No. of upper-air stations 5 

NPSTA No. of precipitation stations 93 

IBTZ Base time zone 7 

PMAP Map projection 

(LCC=Lambert Conformal Conic) 

LCC 

FEAST False easting at origin 0.0 

FNORTH False northing at origin 0.0 

RLAT0 Origin latitude of projection 44.0N 

RLON0 Central meridian of projection 102.0W 

XLAT1 Latitude of 1st standard parallel for projection 46.0N 

XLAT2 Latitude of 2nd standard parallel for projection 48.5N 

DATUM Datum-region for output coordinates NWS-27 

NX No. of X grid cells 213 

NY No. of Y grid cells 153 

DGRIDM Grid spacing (km) 3.0 

XORIGKM Southwest grid cell X coordinate -380 

YORIGKM Southwest grid cell Y coordinate 140 

NZ No. vertical layers 12 

ZFACE Cell face heights (m) 0.,20.,50.,90.,140.,200.,

270.,370.,500.,1000., 

1700.,2500.,4200. 

NOOBS No observation mode (0 = no) 0 

IPROG Use MM5.DAT file as initial guess wind field 

(14=yes) 

14 
105 

Variable Description Value

RMAX1 Max. radius of influence of surface observation 

(km) 

100 

RMAX2 Max. radius of influence of upper-air observation 

(km) 

200 

RMAX3 Max. radius of influence over water (km) 200 

TERRAD Radius of influence of terrain features (km) 10 

R1 Distance from a surface observation station at 

which the wind observation and the first guess field 

are equally weighted (km) 

10 

R2 Distance from an upper-air observation station at 

which the wind observation and the first guess field 

are equally weighted (km) 

10 

ISURFT Surface station number used for the surface 

temperature for the diagnostic wind field module 

(Bismarck) 

17 

IUPT Upper-air station number used to compute the 

domain-scale temperature lapse rate for the 

diagnostic wind field module (Bismarck) 

1 

ZUPWND Bottom and top of layer through which the domainscale winds are computed (m) 1.,2500. 

MNMDAV Max. search distance (in grid cells) for spatial 

averaging of mixing ht. and temperature 

7 

ILEVZI Layer of winds used in upwind averaging of 

mixing heights 

3 

ZIMAX Maximum over land mixing height (m) 4000. 

ZIMAXW Maximum over water mixing height (m) 4000. 

*Shaded background indicates IWAQM-defined setting adjusted by NDDoH 
106 

8.5.3.1 Emissions Inventory 

The emissions inventory utilized in the NDDoH hybrid visibility modeling analysis accounted 

for all SO2-SO4-NOX-HNO3-NO3 emission sources located within and outside of the NDDoH 

CALPUFF domain. The impact of emission sources located outside of the domain was 

accounted for using the boundary condition feature of CALPUFF, with WRAP CMAQ output 

concentrations used to set appropriate boundary concentrations. Within the CALPUFF domain, 

all SO2-SO4-NOX-NO3 emissions were configured as conventional point and area sources. 

Note that HNO3 is not directly emitted by any visibility affecting source. However, HNO3 is an 

important component of nitrate chemistry (both CMAQ and CALPUFF), and is provided as an 

output species in CMAQ. Therefore, HNO3 is included as a boundary concentration for 

CALPUFF boundary conditions, but it is not directly emitted by any of the visibility affecting 

sources configured within the CALPUFF domain. 

For SO2-SO4-NOX-NO3 sources located within the NDDoH CALPUFF domain and within the 

North Dakota border, stack data for point sources, including stack operating parameters and SO2

and NOX emission rates, were obtained from an internal Department database. Point source data 

were reviewed by NDDoH to confirm viability of all stack parameters, and emission rates were 

updated, if necessary, to reflect values representative of the 2000-2004 period. 

For SO2 and NOX point sources located within the NDDoH CALPUFF domain, but outside of 

North Dakota (South Dakota, Montana, Canada), the NDDoH obtained appropriate stack 

parameters and emission rates from governing agencies representing these jurisdictions. Most 

Montana data was obtained directly from the facility operators. Data representing the 2000-2004 

period were requested. Data were reviewed by NDDoH to confirm viability of all stack 

parameters. 

Note that the size threshold for configuring visibility-affecting sources as point versus area is 

generally connected to the availability of point source data in the National Emissions Inventory 

(NEI). All point sources included in the NEI (and located within the NDDoH CALPUFF 

domain) were configured as point sources for the visibility analysis. The exception is oil and gas 

related SO2 sources for which the NDDoH maintains a separate database. These oil and gas 

related sources, though not included in the NEI, were also configured as point sources for the 

visibility analysis. 

The location of larger visibility-affecting point sources within the CALPUFF domain is depicted 

in Figure 8.8. 

All remaining SO2-SO4-NOX-NO3 sources located within the NDDoH CALPUFF domain, but 

not included in the North Dakota or adjoining jurisdiction’s point source inventories, were 

configured as 36-kilometer area sources using a predefined grid structure in CALPUFF. The 

area-source grid is illustrated in Figure 8.8. Emission rates for the CALPUFF area source grid 

were developed using WRAP CMAQ input (SMOKE output) for the CMAQ grid cells located 

within the NDDoH CALPUFF domain. The NDDoH obtained the SMOKE output data from 

WRAP RMC. Because the location and orientation of the CMAQ and CALPUFF grids are not 
107 

Figure 8.8 

NDDoH Domain - Locations of Larger Point Sources and 36-km Area Source 

3

5 1

6

7 2

9

10

11

12 1314

4

8

North Dakota

Montana

Canada

South Dakota

  1 Co 2 Le Sta 3 Mi 4 He 5 An Gr 6 Co 7 Lit 8 Tio 9 Co10 Ce11 Le12 Po13 Bo

PSD Class I Area 14 Sh
108 

consistent, software was developed by NDDoH to accurately apportion emissions from 36-

kilometer CMAQ grid cells to the 36-kilometer CALPUFF area source grid. 

Based on availability in WRAP SMOKE output, the CALPUFF area source emissions inventory 

included the source categories and species summarized in Table 8.2 . Note that SMOKE output 

did not include all four species (SO2-SO4-NOX-NO3) for some source categories. Although 

NDDoH developed a conventional point source inventory for SO2 and NOX, the NDDoH 

database did not include primary SO4 and NO3 emissions for point sources. Therefore, SO4 and 

NO3 emissions for the point source category were obtained from WRAP SMOKE output, and 

these components of point source emissions were configured as area sources in CALPUFF. 

Based on testing during the performance evaluation, and on consultation with Joe Scire 

(TRC)28,29, area sources in CALPUFF were configured for best model performance, and to be 

more consistent with the grid cell treatment in CMAQ. This involved proper settings for the 

CALPUFF “release height” and “initial sigma z” input parameters for area sources. 

Emission rates used for both point and area sources reflect total actual tons per year. CALPUFF 

apportions these total emissions, on a temporal basis, equally to each hour of the year. The 

NDDoH tested the use of temporal profiles to vary emission rates on a seasonal, monthly, or 

hourly basis, but found that such adjustments made little difference in the hybrid model 

performance evaluation (see Section 8.6.1). For example, North Dakota electrical generating 

stations (EGUs) were modeled using an annual profile of actual hourly emissions for SO2 and 

NOX, and results (compared to default total tons per year modeling) were unchanged for most of 

the metrics included in the comparison. The NDDoH attributes this finding to the fact that the 

characterization of model output used for developing RRFs is the average of the 20 percent 

worst or best day predictions, and this longer-term average was also the focus of the performance 

evaluation. Using the average of 20 percent of the days in a year serves to dampen out 

differences attributable to shorter-term temporal variations in emissions. 

To address hybrid model performance and the development of RRFs, the NDDoH prepared 

separate emissions inventories for base period, future period, and performance evaluation 

scenarios. SMOKE data used to apportion area source emissions was based on WRAP cases 

BASE02b, PLAN02d, and PRP18a for performance evaluation, base period, and future period 

modeling, respectively. These WRAP cases are described as follows. 

• Case BASE02b reflects use of year 2002 emissions with year 2002 meteorology. NDDoH 

used this case for performance evaluations. 

• Case PLAN02d reflects use of composite 2000-2004 emissions with 2002 meteorology. 

NDDH used this case for base period modeling to generate relative response factors. 

 

28 TRC, 2008. Telephone consultation with Joe Scire, May 29, 2008. Joe Scire, TRC 

Corporation, Lowell, MA 01854. 

 

29 Joe Scire previously affiliated with Earth Tech, Inc. 
109 

• Case PRP18a (Preliminary Reasonable Progress 2018 Scenario A) reflects use of projected 

year 2018 emissions with 2002 meteorology. Case PRP18a represents base period emissions 

projected to 2018, accounting for estimates of the effect of BART controls, and assuming 

other growth and control factors. NDDoH used this case for future period modeling to 

generate relative response factors. 

To complete emission inventories for the three modeling scenarios, the NDDoH developed point 

source inventories (SO2 and NOX) consistent with the WRAP cases. For EGUs, the inventory 

for performance evaluation was based on actual emissions for 2002, while the base period 

inventory assumed the five-year average of 2000-2004 actual emissions. The future period 

inventory for EGUs included emission reductions consistent with BART controls (see Section 

6.2), but remained consistent with base period emissions for non-BART facilities. The possible 

addition of new EGUs was also accounted for in the future inventory (e.g., the potential 

“Gascoyne 500” EGU was added to the future inventory). 

For point sources other than EGUs (reflecting generally small sources), the source inventory for 

performance evaluation was based on 2002 actual emissions, and the inventory for base period 

and future period modeling was relatively consistent with that used for the performance 

evaluation. For non-EGU point sources, little change in the emissions inventory is expected 

between base and future periods. Emissions increases associated with new sources will be no 

greater (and likely less) than emissions decreases associated with retiring sources. 

When considering weight of evidence options in the NDDoH hybrid visibility modeling analysis, 

emissions inventories as described above were adjusted to eliminate sources. For example, when 

exercising the option to discount the impact of international sources, all Canadian sources of 

visibility affecting emissions (SO2-SO4-NOX-NO3) were eliminated from the base and future 

period inventories (see Section 8.6.3.1). Weight of evidence assumptions are discussed in 

Section 8.6.3. 

In developing its emission inventories for hybrid modeling using the default EPA methodology, 

as well as weight of evidence options, the NDDoH adjusted WRAP future period emissions 

(PRP18a) for NOX associated with oil and gas related sources. The total North Dakota oil and 

gas NOX emissions estimated by WRAP for the future inventory was about 4.5 times higher than 

the total estimate for the baseline inventory. Based on recent projections from the North Dakota 

Department of Mineral Resources, oil and gas activity in 2018 is expected to be about 2 to 2.5 

times higher than the 2002 level.30 Moreover, in a subsequent telephone consultation, WRAP 

representatives admitted that 2018 estimates of NOX related to oil and gas activity in North 

Dakota may have been overstated31. Therefore, the NDDoH applied a constant correction to 

WRAP future oil and gas NOX emissions for all area sources in North Dakota, such that total 

2018 emissions are 2.5 times higher than total baseline emissions for oil and gas related NOX. 

 

30 ND Department of Mineral Resources, 2008. December 2, 2008 Electronic 

Communication from Lynn Helms to Terry O’Clair. 

 

31 WRAP, 2008. December 12, 2008 Telephone Communication between representatives 

of WRAP and NDDoH. 
110 

The NDDoH also had concerns regarding WRAP estimates of future Soil (fine particulate) 

emissions. Because the NDDoH is not directly modeling the Soil species, this concern was 

related to the RRF developed by WRAP for North Dakota Class I areas. The Soil RRFs applied 

by WRAP are 1.13 for TRNP and 1.11 for LWA. Both values imply some significant increase in 

future Soil emissions (or precursors). Given recent increases in the practice of conservation 

tillage farming in North Dakota and adjoining states, and recent decreases in the existence of 

summer fallow (retiring a portion of cultivated land for one growing season), an increase in Soil 

emissions between the baseline and 2018 seems unlikely, with a decrease probable. This issue is 

discussed in more detail in Section 9.5.2. The NDDoH addressed the Soil inconsistency by 

adjusting the TRNP and LWA RRFs to 1.0 to implement the default EPA methodology, as well 

as weight of evidence options. This value is probably still conservative, but more in line with 

current and predicted future farming practices than RRFs developed by WRAP. 

 

8.5.3.2 Boundary Conditions

Boundary conditions account for the additive impact of all emission sources located outside of 

the CALPUFF domain. Out-of-domain source emissions generally constitute a large component 

of total predicted concentrations for sulfate and nitrate species. 

The NDDoH is using the boundary condition feature of CALPUFF to effectively nest the 

CALPUFF domain within the WRAP CMAQ domain to facilitate its hybrid modeling approach. 

The use of CMAQ output to set CALPUFF boundary conditions has been suggested by 

Escoffier-Czaja and Scire32. Location of the NDDoH CALPUFF domain within the WRAP 

CMAQ domain was illustrated in Figure 8.1. 

To implement the feature in CALPUFF, a supplemental boundary condition data file must be 

provided as part of the CALPUFF input conditions. In this file, the user provides the length and 

location of boundary segments which follow the perimeter of the Calpuff domain. For each 

segment, the concentration of each species being modeled is provided, and an air mass depth is 

assigned. Species concentrations for boundary segments can be updated as frequently as hourly. 

For NDDoH hybrid visibility modeling, the length of boundary segments was set to match the 

resolution of the CALPUFF meteorological/computational grid, which is 3 kilometers. 

Accordingly, a boundary segment was placed adjacent to each computational grid cell along the 

perimeter of the domain. Boundary segment hourly concentrations for SO2-SO4-NOX-HNO3-

NO3 species were taken from CMAQ hourly output concentration files provided by WRAP 

RMC. For each segment, concentrations from the 36-km CMAQ grid cell containing the largest 

part of the segment were utilized. A constant air mass depth of 3000 meters was assumed for all 

boundary segments. (Though air mass depth of 1000-2000 meters is nominally suggested in 

 

32 See supra note 6. 

 
111 

guidance for CALPUFF boundary conditions33, the NDDoH found the use of 3000 meters 

provided better agreement with observations in performance evaluations.) 

Separate boundary condition files were prepared for cases BASE02b, PLAN02d, and PRP18a for 

performance evaluation, baseline, and future hybrid modeling, respectively. 

8.5.3.3 Ozone Background 

CALPUFF utilizes background ozone values in its chemistry module. The model accepts either 

a single constant background ozone value, or an input file of hourly ozone values commensurate 

with the period of meteorological data. The NDDoH uses the hourly ozone file option with 

CALPUFF, and would regard this as the appropriate implementation for visibility modeling (this 

is also the IWAQM default option). The hourly ozone file was constructed using year 2002 

hourly ozone data obtained from four NDDoH monitoring sites located within the corridor of 

primary plume transport between major electric generating stations and Theodore Roosevelt 

National Park (TRNP). These monitoring sites include Hannover, Beulah, Dunn Center and 

TRNP South Unit. As indicated in Section 8.5.3.6, a constant ozone background value (30 ppb) 

is also provided in the CALPUFF control file, so that it can be substituted when the hourly value 

is missing. This value represents the approximate annual average for North Dakota ozone 

monitoring sites. 

8.5.3.4 Ammonia Background 

The need for ammonia background concentrations in CALPUFF is also related to chemistry 

processing. CALPUFF accepts either a single annual value, or twelve monthly averages from a 

single site. To achieve a more realistic seasonal progression of sulfate and nitrate predictions, 

the NDDoH used monthly average ammonia background values for CALPUFF hybrid visibility 

modeling input (note that temporal ammonia resolution is improved to hourly in the POSTUTIL 

processing step described in Section 8.5.4). 

Monthly average ammonia concentrations suitable for visibility modeling in North Dakota are 

provided in Table 8.5. These values were derived from data collected at the State’s ammonia 

monitor located near Beulah. Hourly monitor data from years 2001-2002 (data not available for 

year 2000) were filtered to eliminate data from wind directions associated with sources causing a 

local bias, then remaining data were processed to produce the monthly averages. The Table 8.5 

values should be generally representative of background ammonia concentrations in western 

North Dakota. 

 

33 See supra note 6. 

 
112 

Table 8.5 

 Monthly Ammonia Background Concentrations*

Month Value (ppb)

Jan 

Feb 

Mar 

Apr 

May 

Jun 

1.22 

1.23 

1.60 

1.94 

2.29 

1.63 

Jul 

Aug 

Sep 

Oct 

Nov 

Dec 

1.65 

1.69 

0.98 

1.04 

1.37 

1.06 

 * Data reflect NDDoH Beulah monitoring site. 

8.5.3.5 Receptors

Receptors for NDDoH visibility progress goal modeling are located at the TRNP and Lostwood 

NWA IMPROVE monitoring sites. In its guidance for regional haze modeling34, EPA 

recommends including nearby receptors or grid cells in order to provide spatial averaging of the 

design concentration. Use of a spatial average addresses possible “migration” of the predicted 

peak, and some uncertainties in the formulation of the model and model inputs. Therefore, the 

NDDoH used a 3 by 3 receptor grid (9 receptors) which is centered on the IMPROVE site, at 

each Class I area. Receptor spacing in the grid is 5 kilometers. Receptor elevation was set to the 

ground elevation of the IMPROVE monitor site for all 9 receptors in the grid. 

Recognizing that visibility is not necessarily a “ground level” concept, the NDDoH also tested 

the effect of elevated or “flag pole” receptors. A sensitivity test was conducted using a flag pole 

elevation of 18 meters, which is one-half the height of the surface layer used in WRAP CMAQ 

modeling. Results of this test showed a negligible difference compared to predictions for ground 

level receptors. 

 

 

 

34 See supra note 7. 

 
113 

8.5.3.6 CALPUFF Control File Settings 

CALPUFF control file settings used for NDDoH hybrid visibility analyses are generally 

consistent with IWAQM guidance35. To the extent applicable, the settings are also consistent 

with the North Dakota alternative protocol for PSD Class I increment analyses36. 

IWAQM recommendations for CALPUFF control file settings fall into two categories. 

IWAQM-defined variables are those for which IWAQM provides a default value as a general 

recommendation for all analyses. User-defined variables are those where IWAQM recognizes 

the input value will need to be tailored for a given application, and default values are therefore 

not provided. 

For visibility analyses, the NDDoH has established appropriate settings for user-defined 

variables, and has determined the need to adjust a limited number of IWAQM-defined variables 

from recommended values, as discussed below. The CALPUFF control file user-defined 

settings, as well as the IWAQM-defined settings which have been adjusted by NDDoH, are 

summarized in Table 8.6. IWAQM-defined settings adjusted by NDDoH have a shaded 

background in the table. 

Most of the user-defined settings are intuitive, involving variables related to defining the 

meteorological/computational grid, variables related to the Lambert map projection, and the use 

of default values for dry and wet deposition parameterization. The variable IRESPLIT was set 

such that puffs are eligible for splitting on any hour of the day. 

NDDoH settings for IWAQM-defined variables are equivalent to IWAQM recommendations, 

with exception of settings for a limited number of variables related to puff splitting, dispersion, 

and mixing height. Variable MSPLIT was set to allow puff splitting, as this option is generally 

recommended when modeling source-receptor distances of 200 km or more. Based on 

performance testing of the CALPUFF model for PSD Class I increment modeling37, the NDDoH 

used adjusted settings for dispersion-related variables MDISP and MPDF, and for variables 

IVEG and ROLDMAX, as these adjustments provided better model performance. NDDoH 

settings for MDISP and MPDF, reflecting the use of micrometeorological variables in 

calculating dispersion, are also more consistent with dispersion treatment in the local-scale 

model AERMOD38. Values for background ozone and ammonia (variables BCKO3 and 

 

35 See supra note 20 

 

36 See supra note 21. 

37 See supra note 21. 

38 EPA, 2004. User’s Guide for the AMS/EPA Regulatory Model – AERMOD. 

Publication No. EPA-454/B-03-001, Office of Air Quality Planning and Standards, Research 

Triangle Park, NC 27701. 

 
114 

Table 8.6 

 User-Defined and Non-IWAQM Settings 

 for CALPUFF Control File*

Variable Description Value 

IBTZ Base time zone 7 

NSPEC Number of chemical species 5 

NSE Number of chemical species emitted 4 

MSPLIT Allow puff splitting (1=yes) 1 

MDISP Method used to compute dispersion coefficients 2 

MPDF PDF used for dispersion under convective 

conditions (1=yes) 

1 

PMAP Map projection 

(LCC=Lambert Conformal Conic) 

LCC 

FEAST False easting at origin 0.0 

FNORTH False northing at origin 0.0 

RLAT0 Origin latitude of projection 44.0N 

RLON0 Central meridian of projection 102.0W 

XLAT1 Latitude of 1st standard parallel for projection 46.0N 

XLAT2 Latitude of 2nd standard parallel for projection 48.5N 

DATUM Datum-region for output coordinates NWS-27 

NX No. of X grid cells 213 

NY No. of Y grid cells 153 

NZ No. vertical layers 12 

DGRIDM Grid spacing (km) 3.0 

ZFACE Cell face heights (m) 0.,20.,50.,90.,140.,200

.,270.,370.,500.,1000., 

1700.,2500.,4200. 

XORIGKM Southwest grid cell X coordinate -380 

YORIGKM Southwest grid cell Y coordinate 140 
115 

Variable Description Value 

IBCOMP Southwest X-index of computational grid 1 

JBCOMP Southwest Y-index of computational grid 1 

IECOMP Northeast X-index of computational grid 213 

JECOMP Northeast Y-index of computational grid 153 

Dry Gas Dep. Chemical parameters of gaseous deposition 

species 

Model defaults 

Dry Part. Dep. Chemical parameters of particulate deposition 

species 

Model defaults 

IVEG Vegetative state in unirrigated areas (2=active 

and stressed vegetation) 

2 

Wet Dep. Wet deposition parameters Model defaults 

BCKO3 Monthly ozone background concentration (ppb) 30.0** 

BCKNH3 Monthly ammonia background concentration 

(ppb) 

Table 8.5 

XMAXZI Maximum mixing height 4000. 

IRESPLIT Hours when puff is eligible for vertical split hours 1-24 

ROLDMAX Vertical puff split allowed only when the ratio of 

last hour’s mixing height to max. mixing height 

experienced by the puff is smaller than this value 

0.33 

NSPLITH Number of puffs that result when a puff is split 

horizontally 

5 

SYSPLITH Minimum sigma-y (grid cell units) of puff before 

it may split horizontally 

1.0 

SHSPLITH Minimum puff elongation rate (SYSPLITH/hr) 

due to wind shear, before it may split horizontally

2.0 

CNSPLITH Minimum concentration (g/m3

) in puff before it 

may split horizontally 

1.0E-07 

NREC Number of discrete receptors 18 

* Shaded background indicates IWAQM-defined setting adjusted by NDDoH 

**Use same value for each month. 
116 

BCKNH3, respectively) were set to be consistent with local monitoring data. Maximum mixing 

height (XMAXZI) was set to 4000 meters for consistency with CALMET settings. 

8.5.4 POSTUTIL Input

Because CALPUFF allows the full amount of the specified background concentration of 

ammonia to be available to each puff for forming nitrate, the same ammonia may be used 

multiple times, resulting in an overestimate of nitrate formation. The POSTUTIL processor 

provides repartitioning of total nitrate at the receptor location to adjust for over-counting of 

ammonia in the CALPUFF chemistry. This repartitioning in POSTUTIL is commonly referred 

to as the ammonia limiting method39. The repartitioning process in POSTUTIL generates a 

modified hourly concentration file in the same format as the input CALPUFF hourly 

concentration file. Species HNO3 and NO3, only, are modified in the repartitioning process. 

Concentrations for all other species remain unchanged. 

To implement the ammonia limiting method, POSTUTIL requires an input control file, the 

hourly concentration output file from CALPUFF, and (optionally) an hourly file of ammonia 

background concentrations. Among other intuitive input assignments (file names and carryover 

of settings from CALPUFF), the POSTUTIL input control file specifies the setting for the 

MNITRATE parameter, which is related to the method of nitrate repartitioning. The control file 

also provides the source and temporal resolution for ammonia background concentrations to be 

used in nitrate repartitioning. POSTUTIL provides for the use of annual, monthly, or hourly 

ammonia background concentrations from a single site. By allowing use of hourly ammonia 

background, POSTUTIL improves on the maximum temporal resolution available in CALPUFF 

(monthly). 

The POSTUTIL processor also accommodates the 3-step ammonia limiting method, which is 

used to determine the contribution of a subgroup of sources (from the complete source inventory) 

to total nitrate formation. Effectively, the 3-step method allows consideration of the effect of 

excluded sources on the model chemistry (e.g., excluded sources still “use up” some of the 

available ammonia). The MNITRATE parameter is used to control processing for each step of 

the 3-step sequence. The 3-step ammonia limiting method requires three separate executions of 

POSTUTIL. Input/output for the 3 steps, along with appropriate MNITRATE settings, is 

outlined in Table 8.7. 

 

39 Escoffier-Czaja, C., and J. Scire, 2002. The Effects of Ammonia Limitation on Nitrate 

Aerosol Formation and Visibility Impacts in Class I Areas. Earth Tech, Inc., Extended Abstract. 

12th Joint Conference on the Applications of Air Pollution Meteorology with the Air and Waste 

Management Association, American Meteorological Society, J5.13. 
117 

 Table 8.7 

 3-Step Ammonia Limiting Method

Step MNITRATE 

Setting 

Description 

1 1 Using CALPUFF hourly concentration file for entire source 

inventory as input, repartitioning is performed based on 

entire source inventory. Modified hourly concentration file 

is created (affects HNO3 and NO3 species). 

2 0 Using Step 1 modified hourly file as input, new species 

names are assigned to HNO3 and NO3 (HNO3ALL and 

NO3ALL). Hourly concentration file containing only

renamed species is created. 

3 2 Using both CALPUFF new hourly concentration file for 

source group (subset of entire source inventory in Step 1) 

and Step 2 hourly concentration output file (HNO3ALL and 

NO3ALL species representing entire source inventory), 

repartitioning is performed based on the source group 

contribution to the entire source inventory. Modified hourly 

concentration file is created (affects HNO3 and NO3 species). 

 

The NDDoH utilized POSTUTIL and the ammonia limiting method in its hybrid modeling 

analysis. The NDDoH developed an hourly ammonia background concentration file to use with 

POSTUTIL repartitioning. To create the hourly file, observed hourly ammonia concentrations 

were obtained from the State’s Beulah monitoring site (the only ammonia site in North Dakota) 

for the three-year period 2001-2003. Hourly data for the three years were filtered to eliminate 

data from wind directions associated with sources causing a local bias. Then the three years 

were averaged together, on a temporally consistent basis, to produce a single hourly file 

considered representative of 2002, and appropriate for use with 2002 meteorological data 

modeling. Years 2001 and 2003 were incorporated in an averaging scheme because year 2002 

contained missing periods of hourly data, and some additional data were lost due to filtering as 

described above. Finally, smoothing was applied to the resultant hourly data set, in the form of a 

24-hour running average, to dampen the effect of discontinuities in the ammonia data. 

The resultant background hourly ammonia file was tested during the performance evaluation of 

the hybrid modeling system (Section 8.6.1). While the adjusted Beulah data provided good 

modeled comparisons with TRNP observed nitrate, the LWA nitrate observations were 

consistently under predicted. The NDDoH found that agreement with LWA nitrate observations 

was significantly improved if hourly values in the ammonia file are approximately doubled. 

Moreover, the NDDoH found empirical evidence (discussed below) that ammonia levels in the 

vicinity of LWA would be typically higher than ammonia levels at TRNP. Therefore, the 
118 

NDDoH applied the original hourly ammonia file (above) for all POSTUTIL processing 

associated with TRNP, and doubled the hourly ammonia profile for all POSTUTIL processing 

associated with LWA. 

In addition to performance evaluation results, there is empirical support for the assumption of 

higher ammonia background at LWA than at TRNP and Beulah. Figure 8.9 provides an 

illustration of ammonia emissions density (tons/year/square mile) for North Dakota counties and 

adjoining Canadian provinces. These data were obtained from the WRAP RMC 2004/2005 

report40, and represent ammonia input conditions for CMAQ modeling. As shown in the figure, 

the TRNP and LWA IMPROVE sites, and the Beulah monitoring site, are all located in counties 

with the lowest ammonia emissions density (0.000-0.001 tons/year/square mile). However, the 

proximity of the LWA site is such that prevailing local winds (northwest and southeast wind 

direction) will likely direct higher density ammonia emissions from Saskatchewan (0.075-0.25 

tons/year/square mile) and Ward county (0.005-0.025 tons/year/square mile) toward the LWA 

site. 

For comparing predicted visibility progress with respect to the default (EPA) glide path, the 

NDDoH applied the basic ammonia limiting method, presented as Step 1 in Table 8.7. In order 

to determine progress in the context of weight of evidence arguments, such as discounting the 

effect of Canadian emissions, it was necessary to apply the 3-step ammonia limiting method 

(Section 8.6.3). 

POSTUTIL output was subsequently processed with the NDDoH CALHAZE program to project 

future visibility (Section 8.5.5). 

8.5.5 CALHAZE 

The NDDoH has developed a software system to generate relative response factors (RRFs) from 

WRAP CMAQ and NDDoH CALPUFF (POSTUTIL) hourly concentration output files for 

baseline and future scenarios, project future concentrations of visibility affecting aerosols by 

applying RRFs to baseline IMPROVE data, and convert projected future concentrations to 

visibility (deciview). This system is informally known as CALHAZE. CALHAZE represents 

the final step in the NDDoH hybrid visibility modeling sequence (CALMET-CALPUFFPOSTUTIL-CALHAZE). Effectively, CALHAZE replaces CALPOST. 

CALHAZE accesses NDDoH CALPUFF (POSTUTIL) hourly concentration files for baseline 

and future scenarios to generate 20 percent worst/best day RRFs for sulfate and nitrate. 

CALHAZE accesses WRAP CMAQ hourly concentration files (provided by WRAP RMC) for 

baseline and future scenarios to generate 20 percent worst/best day RRFs for all other visibility 

 

40 Tonnesen, G., R. Morris, Z. Adelman, et. al., 2005. Final Report for the Western 

Regional Air Partnership (WRAP) Regional Modeling Center (RMC) for the Project Period 

March 1, 2004, through February 28, 2005, Appendices A Through E. Western Regional Air 

Partnership, Denver, CO 80202. 
119 

Figure 8.9 

NH3 Emissions Density for North Dakota Counties and Adjoining Canadian Pro

LWA IMPROVE Site

TRNP IMPROVE Site

Beulah Monitoring Site 

Saskatchewan Manitoba

*From WRAP RMC 2004 report 

Ward
120 

affecting species. RRFs are applied to IMPROVE baseline monitoring (2000-2004) data files, 

obtained from the WRAP TSS (Technical Support System) internet site 

(http://vista.cira.colostate.edu/tss/), to project future concentrations of each visibility affecting 

species for each worst/best day for each year. Next, CALHAZE applies the new IMPROVE 

algorithm to calculate light extinction (using projected future concentrations) for each worst/best 

day for each year. Finally, deciview is calculated for each worst/best day, and averaged across 

all worst/best days and all years. CALHAZE repeats this procedure for each Class I area. 

CALHAZE incorporates the default EPA methodology to calculate RRFs and future deciview 

(Section 8.3). 

Input files required by CALHAZE, as applied by NDDoH, are summarized: 

1) WRAP CMAQ hourly concentration output file for baseline scenario (2002), 

2) WRAP CMAQ hourly concentration output file for future scenario (2018), 

3) NDDoH CALPUFF (POSTUTIL) hourly concentration output file for baseline scenario 

(2002 results for both TRNP and LWA receptors), 

4) NDDoH CALPUFF (POSTUTIL) hourly concentration output file for future scenario (2018 

results for both TRNP and LWA receptors), 

5) IMPROVE daily baseline monitoring data for TRNP (2000-2004), 

6) IMPROVE daily baseline monitoring data for LWA (2000-2004). 

CMAQ hourly concentrations are taken from the grid cell containing the North Dakota Class I 

area. Note that all additional parameters necessary for calculating light extinction, via the new 

IMPROVE algorithm, are provided in the IMPROVE baseline monitoring data files. This 

includes function of relative humidity for sea salt and small and large size fractions, and the 

Rayleigh scattering coefficient. Consistent with WRAP RMC conclusions addressing the 

viability of CMAQ coarse mass predictions, CALHAZE forces a RRF of 1.0 for the coarse mass 

species. As discussed in Section 8.2, a constant RRF of 1.0 is also applied for sea salt. 

As an option, the CALHAZE system also accepts a control input file which allows the user to set 

RRF for each species, and set the visibility target (in deciviews), for each Class I area. Use of 

this feature was necessary when applying the normalization procedure described in Section 8.5.6. 

The NDDoH has applied the CALHAZE software to complete the hybrid modeling procedure 

and visibility projections for North Dakota Class I areas. To address quality assurance issues 

with respect to the CALHAZE system, the NDDoH has successfully cross-checked CALHAZE 

output with data on the TSS internet site. For example, the worst-day RRFs generated by 

CALHAZE for elemental carbon, organic mass, fine soil, and coarse mass for North Dakota 

Class I areas agree exactly with the corresponding values obtained from the TSS site. 
121 

8.5.6 Hybrid System Used to Adjust WRAP CMAQ Modeling Results 

Based on performance testing of direct hybrid model predictions (operational evaluation), as 

conducted by NDDoH (see Section 8.6.1), the hybrid CMAQ-CALPUFF modeling system 

performed well in replicating observed concentrations of SO4 and NO3. However, performance 

regarding sensitivity to changes in NOX emissions (diagnostic evaluation) was not good, with the 

hybrid modeling system significantly overstating future case nitrate formation compared to 

predictions obtained by WRAP using CMAQ alone. The NDDoH concluded this anomaly is an 

artifact of the chemistry in CALPUFF, and acknowledges that CMAQ chemistry is superior. 

For this reason, the NDDoH chose not to accept direct hybrid modeling system results to 

independently address progress with respect to regional haze goals. Rather, the NDDoH used the 

hybrid modeling system in a supportive sense to add value to the original WRAP CMAQ 

modeling results. The hybrid system was used to provide a “correction” to WRAP CMAQ 

results in order to offset coarseness in the CMAQ spatial resolution for large, local point sources. 

Similarly, the hybrid system was applied to adjust WRAP CMAQ results in order to discount the 

effect of international (Canadian) sources. (WRAP did not provide regional haze modeling 

results which discount the impact of international sources, a modeling interpretation which had 

been requested by EPA and others, and which the NDDoH wanted to include in its weight of 

evidence discussion.) 

8.5.6.1 Adjusting WRAP CMAQ Modeling Results for Local Point Sources 

To address the concern regarding spatial resolution of the WRAP CMAQ simulations for local 

point sources, the NDDoH concluded that the hybrid modeling system could be used in an 

indirect manner to apply a reasonable and conceptually simple “correction” to the WRAP 

CMAQ RRFs (relative response factors) for sulfate and nitrate. Given that CALPUFF has the 

capability of treating point sources as well as area sources, all point sources within the NDDoH 

CALPUFF domain can be allocated (converted) to area sources, or more specifically to a 36-km 

area source grid, in order to emulate the coarse treatment of point sources in CMAQ. Then a 

correction factor can be established which adjusts the WRAP CMAQ prediction based on the 

predicted difference between point sources treated as conventional point sources and point 

sources treated as area sources (i.e., CMAQ emulation) with the hybrid model. This adjustment 

can be expressed 

  	
 





	

 8  1

where 

 is the adjusted average concentration (sulfate or nitrate) for 20% worst days. Note 

 that both WRAP and NDDoH were consistent in basing 20% worst days on IMPROVE 

 monitoring data (2002), 
122 

	
 is the average concentration for 20% worst days obtained by WRAP using 

 CMAQ, 


 is the average concentration for 20% worst days predicted by the hybrid 

 model when point sources (within the NDDoH CALPUFF domain) are treated as 

 conventional point sources, 


	 is the average concentration for 20% worst days predicted by the hybrid 

 model when point sources (within the NDDoH CALPUFF domain) are allocated as 

 36-km area sources. 

The ratio 
 / 
	 in the equation is effectively a correction factor to address the 

coarse resolution of local point sources in CMAQ. Equation 8-1 can be thought of as an 

emulation of the result CMAQ would have produced had the plume-in-grid feature been 

deployed for local point sources (WRAP did not deploy CMAQ plume-in-grid for regional haze 

modeling). The Equation 8-1 adjustment involves modifying only the point source component of 

the hybrid model emissions inventory. Boundary conditions and sources originally treated as 

area sources (Section 8.5.3.1) remain equivalent in HybridPt and HybridArea emissions 

inventories. 

Equation 8-1 is applicable for both baseline and future period modeling. Recall that the RRF for 

each species is defined41

, 

   

 !"



where  is the future 20% worst day average concentration and  !" is the baseline 

20% worst day average concentration. Therefore, if the future period implementation of 

Equation 8-1 is divided by the baseline period implementation of Equation 8-1, it follows that the 

adjustment for CMAQ treatment of point sources can be specified in terms of RRF, 

  	
 





	 8  2

where 

 is the adjusted relative response factor ultimately used by NDDoH to project 

 future concentrations of sulfate and nitrate, 

	
 is the relative response factor obtained by WRAP using CMAQ, 

 

41 See supra note 7. 
123 

 


 is the relative response factor produced by the hybrid model when point 

 sources (within NDDoH CALPUFF domain) are treated as conventional point sources, 


	 is the relative response factor produced by the hybrid model when point

 sources (within NDDoH CALPUFF domain) are allocated as 36-km area sources. 

Thus, Equation 8-2 was used by NDDoH to implement the adjustment for WRAP CMAQ 

treatment of point sources. The adjustment was utilized for 20% best days as well as 20% worst 

days, and was applied for each Class I area in North Dakota. It was applied directly to the RRFs 

from WRAP CMAQ modeling (specific day option42), which are shown in Table 8.8. 

Table 8.8 

 WRAP CMAQ RRF 

 (Specific Day Option)

TRNP 

 Worst Day 

TRNP 

 Best Day 

LWA 

 Worst Day 

LWA 

 Best Day 

SO4 0.92 1.02 0.91 1.02 

NO3 0.92 0.93 0.96 0.89 

OMC 1.01 1.01 1.05 1.01 

EC 0.72 0.78 0.73 0.74 

Soil 1.13 1.08 1.11 0.96 

CM 1.00 1.00 1.00 1.00 

 

To develop the HybridArea CALPUFF input files, all point source emissions were allocated to 

the CALPUFF 36-km area source grid, which is discussed in Section 8.5.3.1 and shown in 

Figure 8.8. The CALPUFF “effective height” (plume height) and “initial sigma z” area source 

input parameters were used to assign point source emissions to discrete vertical “layers” which 

are consistent with the WRAP CMAQ layers. Effective height is based on stack height plus 

plume rise as calculated externally. 

 

42 In addition to the EPA-recommended specific day option for generating RRFs, WRAP 

also generated RRFs and projected future visibility based on monthly and quarterly weighting. 

The NDDoH used the specific day option exclusively in hybrid visibility modeling. 
124 

To complete emulation of the WRAP CMAQ 36-km grid resolution, receptor treatment was also 

addressed in the HybridArea input files. Effective “receptor” resolution in WRAP CMAQ is 

limited to the average concentration in the 36-km surface grid cell volume containing the Class I 

area IMPROVE site. To emulate WRAP CMAQ in HybridArea input files, the NDDoH 

averaged across a uniform receptor grid which filled the CALPUFF area-source 36-km grid cell 

containing each IMPROVE site (Figure 8.8). Receptors were spaced at 3 km for a total of 12 x 

12 or 144 discrete receptors for each Class I area. Note that this type of receptor averaging was 

only applied in CALPUFF runs for CMAQ emulation (HybridArea), and not in runs for 

conventional point source treatment (HybridPt) or performance evaluation. 

Given that the NDDoH hybrid modeling was limited to sulfate and nitrate species (and 

precursors), the Equation 8.2 adjustment was also limited to sulfate and nitrate species. The 

RRFs for all other light affecting species were taken directly from WRAP CMAQ modeling, as 

shown in Table 8.8. Therefore, it is likely that the correction for CMAQ resolution of point 

sources, in terms of the total projected future light extinction, is somewhat understated. 

However, the primary contributors to light extinction from the local point sources of concern in 

North Dakota are sulfate and nitrate. 

The Equation 8.2 adjustment as applied by NDDoH also accounted for the WRAP overestimate 

of future oil and gas related NOX emissions in North Dakota, as discussed in Section 8.5.3.1. 

This error affected the future period modeling only. Therefore, the HybridArea input file 

(CMAQ emulation) for the future period included WRAP estimated NOX emissions for oil and 

gas, while the HybridPt input file for the future period included the NDDoH corrected future 

NOX emissions for oil and gas. (The base period NOX emissions in both cases were based on 

WRAP estimates for 2002.) This accounting for the WRAP error in future oil and gas NOX

emissions was not expected to make a significant difference in results. 

When applying the Equation 8.2 adjustment, the NDDoH found the ratio 
 to 


	 to be consistently less than 1.0, providing a resultant  which was 

significantly lower than the WRAP CMAQ RRF, with subsequently lower projected future 

concentrations and greater projected visibility improvement than predicted by WRAP. This 

expected response is related primarily to the resolution of modeling systems as applied to local 

point sources. When local point sources are treated as conventional point sources, the higher 

density point-source plumes cause higher predictions at the IMPROVE monitor site (for both 

baseline and future periods) such that the future reduction in emissions from local point sources 

may cause a relatively large impact compared to the more static contribution of all other sources 

(area and boundary). When local point sources are configured as 36-km area sources, the 

associated diluted plumes cause lower predictions compared to the contribution of all other 

sources (other area and boundary), such that the future reduction in emissions may be 

overwhelmed by the more static contribution of other sources. 

8.5.6.2 Discounting the Impact of Canadian Sources 

In the process of analyzing progress with respect to visibility goals, it was necessary for the 

NDDoH to address the impact of Canadian sources north of the International border. This 
125 

interpretation of modeling results was requested by EPA and others, and was an important 

element of the NDDoH weight of evidence discussion (see Section 8.6.3). No specific guidance 

is provided for this type of analysis. The method used by NDDoH was to eliminate Canadian 

sources from the baseline and future emissions inventories used to develop RRFs, and to develop 

a modified glide path which discounts the effect of Canadian sources. This approach is similar 

to methods proposed by CENRAP43 and others. 

Again, the NDDoH implemented its procedure for discounting Canadian sources in terms of an 

adjustment to WRAP CMAQ modeling results. If Canadian sources are eliminated from 

baseline and future emissions inventories for conventional point sources, Equation 8-2 becomes 

  	
 


$


	 8  3

where 


$ represents the resultant relative response factor after eliminating 

 Canadian sources from the conventional point source baseline and future emissions 

 inventories used with the hybrid modeling system. 

Equation 8-3 was used by the NDDoH to develop adjusted RRFs for sulfate and nitrate. Note 

that with the implementation of Equation 8-3, the adjustment to discount the impact of Canadian 

sources is effectively “added on” to the adjustment for WRAP CMAQ point source resolution. 

To complete the illustration, the impact of Canadian sources must also be discounted from the 

glide path used to assess progress with respect to visibility goals. In this case, the NDDoH 

applied the hybrid modeling system exclusively to estimate the baseline starting point (deciview) 

of the modified glide path. The estimation process involved adjusting the IMPROVE baseline 

concentration for each worst-case day for the five-year period 2000-2004, in order to 

approximate the daily observations without the impact of Canadian sources. The estimation 

procedure for each worst-case day can be expressed 

&
    &
 

' 

'

 8  4

where 

&
   is the estimated sulfate or nitrate concentration for one worst case day of 

 IMPROVE monitoring data for all non-Canadian sources (plus natural background), 

 

 

43 CENRAP, 2007. CENRAP Policy Oversight Group (POG) - Summary of PM Source 

Apportionment Modeling and 2018 Projection Approaches. Power Point presentation, Joint 

Workgroup Meeting, Kansas City, Missouri, March 7, 2007. 
126 

&
 is the original IMPROVE observed sulfate or nitrate concentration for the worst 

 case day, 

' 

 is the average prediction for 20% worst days when hybrid model is applied 

 for non-Canadian sources only (Year 2002 baseline emissions inventory), 

' is the average prediction for 20% worst days when hybrid model is applied for 

 the entire source inventory (Year 2002 baseline emissions inventory). 

Using the adjusted worst day observations for sulfate and nitrate, along with the original 

IMPROVE worst day observations for all other visibility-affecting species, light extinction and 

deciview were calculated for each 20% worst day of the 2000-2004 period. Finally, the five-year 

average deciview was calculated to set the starting point for the “Canadian sources discounted” 

glide path for 20% worst days. 

The NDDoH next considered the end point (2064) of the modified glide path. When adjusting 

baseline and future emissions inventories to exclude Canadian sources, the intent of NDDoH was 

to eliminate the impact of non-natural sources only, leaving the contribution of all other nonCanadian sources plus natural sources. Therefore, an adjustment was made to CALPUFF 

boundary conditions (baseline and future) to eliminate the contribution of Canadian source 

emissions, while retaining the impact of natural Canadian sources of sulfate and nitrate. This 

adjustment is described in Section 8.6.3.1. And recall that the NDDoH adjustment does not 

affect the impact of all other visibility-affecting species on the glide path. As such, the NDDoH 

concluded that it was not necessary or appropriate to change the end point (default natural 

conditions) of the modified glide path. 

A modified glide path is illustrated in Figure 8.10, for a hypothetical case where Canadian source 

emissions contribute about one-half of total visibility degradation. 

Using the modified glide path, the NDDoH applied RRFs generated using Equation 8-3 to the 

adjusted starting point to estimate visibility improvement progress by 2018 (see Section 8.6.3.1). 

As expected, visibility improvement increased significantly when Canadian sources were 

discounted. Canadian source emissions were discounted only for 20% worst days, as the impact 

of Canadian sources was not problematic in meeting visibility goals for best days. 
127 

Figure 8.10 

Illustration of Visibility Improvement Using EPA Default Glide Path 

and Canadian Sources Discounted Glide Path

2004 2024 2044 

Year

048

12162024

Deciview EPA Default Glide Path

Canadian Sources Discounted Glide Path

2018 Projection -61% of goal achieved

2018 Projection -124% of goal achieved
128 

8.6 Modeling Process and Results 

The NDDoH hybrid modeling system was applied to adjust WRAP CMAQ results, using input 

conditions and procedures as described in Section 8.5. A performance evaluation was conducted 

first to ensure that selected inputs were producing viable results relative to observed 

concentrations of sulfate and nitrate. (Note that the performance evaluation was based on 

predictions taken directly from hybrid model output, rather than adjusted WRAP CMAQ output 

described in Section 8.5.6.) Next, the hybrid modeling system was executed in default 

production mode to determine progress with respect to the glide path and URP target based on 

default EPA methodology. Finally, the hybrid modeling system was applied to test several 

weight of evidence scenarios. NDDoH hybrid results and WRAP CMAQ results were compared 

for the default EPA methodology. 

8.6.1 Hybrid CMAQ-CALPUFF Performance Evaluation 

The NDDoH conducted a limited operational evaluation to assess performance of the hybrid 

CMAQ-CALPUFF modeling system. The focus of the evaluation was to assess performance in 

reproducing observed concentrations of sulfate and nitrate at IMPROVE monitoring sites in 

North Dakota. These sites include the Theodore Roosevelt National Park South Unit (TRNP) 

and the Lostwood Wilderness Area (LWA). Alternative input options which might improve 

performance were also explored. To the extent applicable, the performance evaluation followed 

EPA guidance for Regional Haze modeling analyses44. 

An emissions inventory for the performance evaluation was developed by NDDoH. WRAP 

CMAQ hourly concentration output (SO2-SO4-NOX-HNO3-NO3) for Case BASE02B was used 

to set hourly boundary conditions for CALPUFF. The emissions inventory (SO2-NOX) for the 

point source category was developed using data from the NDDoH emissions database for 2002, 

and sources were configured as conventional point sources in CALPUFF. This inventory 

included point sources located in adjacent parts of South Dakota, Montana, and Canada, which 

are included in the NDDoH CALPUFF domain (see Figure 8.5). This inventory also included 

SO2 emissions associated with oil and gas production facilities (treaters and flares) in North 

Dakota, which did not appear to be accounted for in the WRAP inventory for BASE02B. 

Emission rates for the point source inventory reflect actual emissions for Year 2002. 

All other source categories (see Table 8.2) were treated as area sources in CALPUFF, and the 

emissions inventory (SO2-SO4-NOX-NO3) for these categories was based on WRAP CMAQ 

input (SMOKE output) for all sources other than point sources. Software was prepared and 

implemented to apportion the gridded SMOKE output emissions for BASE02B into a 36-km 

area source grid structure developed for the NDDoH CALPUFF domain (Figure 8.8), on a 

consistent spatial basis. Emission rates for this area source inventory reflect annual averages for 

the SMOKE data. 

 

44 See supra note 7. 
129 

The CALPUFF modeling system (CALMET-CALPUFF-POSTUTIL-CALPOST) was applied 

for SO2-SO4-NOX-NO3 source inventories and boundary conditions as described above. All 

other input conditions were consistent with the description of the hybrid modeling system in 

Section 8.5. Single receptors were placed at the TRNP and LWA IMPROVE sites. Monthly 

average ammonia data were utilized from the Beulah monitoring site in both CALPUFF and 

POSTUTIL. 

After initial application of CALPUFF for the performance evaluation, it was concluded that 

certain scientifically-defensible adjustments to CALPUFF input conditions may improve 

performance for the hybrid modeling system, and should be investigated. Thus, the performance 

evaluation evolved into a suite of tests which are described below. 

1) Test 1 - Calpuff executed with default input conditions, as outlined above. Air mass depth 

for boundary conditions was set to 2000 meters. 

2) Test 2 - CALPUFF as in Test 1, but using CEMS 2002 hourly emissions data (SO2, NOX) for 

point sources, where available. 

3) Test 3 - CALPUFF as in Test 1, but using WRAP MM5 12 km 2002 mesoscale data in 

CALMET, rather than the default NDDoH RUC 2002 mesoscale data. 

4) Test 4 - CALPUFF as in Test 1, but increasing air mass depth for boundary conditions from 

2000 to 3000 meters. 

5) Test 5 - CALPUFF as in Test 1, but with addition of SO4 and NO3 emissions from point 

sources. (Previous tests excluded this component, because SO4 and NO3 emissions are not 

included in the NDDoH point source inventory. For Test 5, an SO4-NO3 emissions inventory 

was derived from SMOKE gridded output for the point source category, and configured as 

area sources for CALPUFF.) 

6) Test 6 - CALPUFF as in Tests 4 and 5 (air mass depth = 3000 meters, SO4 and NO3

emissions from point sources included), but area sources configured as 4 separate groups to 

account for varying release heights of different source types, and Beulah hourly profile used 

for background NH3 in POSTUTIL. (Area sources were configured as a single CALPUFF 

group in previous tests.) 

7) Test 7 - CALPUFF as in Test 6, but Beulah hourly NH3 profile doubled for LWA. 

Results of the performance evaluation are summarized in Tables 8.9 and 8.10. Table 8.9 

compares predicted NO3 and SO4 concentrations to observed concentrations for both IMPROVE 

sites, while Table 8.10 provides predicted-to-observed ratios. Note that both tables include a 

column labeled “CMAQ only”, which provides the original WRAP CMAQ results for Case 

BASE02B. 
130 

Table 8.9 

Hybrid CMAQ-CALPUFF Performance Evaluation 

Observed and Predicted Concentrations Year 2002 (ug/m3) 

Test 1 Test 2 Test 3 Test 4 Test 5 Test 6 Tes

TRSU NO3 98th Percentile Day 2.03 2.11 2.11 2.20 1.96 2.11 2.06 2.0

 90th Percentile Day 1.21 1.50 1.46 1.55 1.43 1.47 1.21 1.2

 Avg 20% Worst Days 1.42 1.59 1.59 1.65 1.56 1.59 1.41 1.4

 Annual Average 0.50 0.71 0.71 0.73 0.70 0.71 0.53 0.5

TRSU SO4 98th Percentile Day 3.29 2.57 2.57 2.47 2.53 2.57 2.58 2.5

 90th Percentile Day 1.88 1.72 1.72 1.66 1.77 1.72 1.79 1.7

 Avg 20% Worst Days 2.43 1.96 1.97 1.83 1.96 1.98 1.99 1.9

 Annual Average 1.03 0.90 0.90 0.86 0.90 0.91 0.91 0.9

Lostwood NO3 98th Percentile Day 3.65 1.91 1.91 2.01 1.94 1.85 2.15 2.7

 90th Percentile Day 1.95 1.48 1.50 1.56 1.47 1.44 1.13 1.7

 Avg 20% Worst Days 2.33 1.55 1.55 1.61 1.52 1.50 1.30 2.0

 Annual Average 0.79 0.70 0.70 0.73 0.69 0.67 0.47 0.8

Lostwood SO4 98th Percentile Day 3.10 2.91 2.90 2.74 2.88 3.11 3.12 3.1

 90th Percentile Day 2.22 2.06 2.03 1.90 2.07 2.19 2.21 2.2

 Avg 20% Worst Days 2.49 2.21 2.21 2.09 2.22 2.35 2.36 2.3

 Annual Average 1.18 1.07 1.07 1.03 1.08 1.15 1.17 1.1

* Test 1 - Calpuff run with default BART screening protocol + full emissions inventory + boundary conditions

 Test 2 - Calpuff as in Test 1 but using CEMS hrly emissions (SO2, NOX) where available Test 3 - Calpuff as in Test 1 but using WRAP MM5 12km mesoscale data (in CALMET) Test 4 - Calpuff as in Test 1 but assuming boundary air mass depth as 3000 m rather than 2000 m Test 5 - Calpuff as in Test 1 but with addition of NO3 and SO4 emissions from point sources Test 6 - Calpuff as in Test 1 but assuming boundary air mass depth as 3000 m (Test 4) and with  addition of NO3 and SO4 emissions from point sources (Test 5). Area sources configured as 4 groups and Beulah hourly profile used for backgound NH3.  Test 7 - Calpuff as in Test 6 but Beulah hourly NH3 profile doubled for Lostwood

Observed 

Hybrid CMAQ-CALPUFF Predicted*
131 

Table 8.10 

Hybrid CMAQ-CALPUFF Performance Evaluation 

Predicted to Observed Ratios 2002 

Test 1 Test 2 Test 3 Test 4 Test 5 Test 6 Test 7

TRSU NO3 98th Percentile Day 1.04 1.04 1.08 0.97 1.04 1.01 1.01  90th Percentile Day 1.24 1.21 1.28 1.18 1.21 1.00 1.00  Avg 20% Worst Days 1.12 1.12 1.16 1.10 1.12 0.99 0.99  Annual Average 1.42 1.42 1.46 1.40 1.42 1.06 1.06 TRSU SO4 98th Percentile Day 0.78 0.78 0.75 0.77 0.78 0.78 0.78  90th Percentile Day 0.91 0.91 0.88 0.94 0.91 0.95 0.95  Avg 20% Worst Days 0.81 0.81 0.75 0.81 0.81 0.82 0.82  Annual Average 0.87 0.87 0.83 0.87 0.88 0.88 0.88 Lostwood NO3 98th Percentile Day 0.52 0.52 0.55 0.53 0.51 0.59 0.75  90th Percentile Day 0.76 0.77 0.80 0.75 0.74 0.58 0.90  Avg 20% Worst Days 0.67 0.67 0.69 0.65 0.64 0.56 0.87  Annual Average 0.89 0.89 0.92 0.87 0.85 0.59 1.01 Lostwood SO4 98th Percentile Day 0.94 0.94 0.88 0.93 1.00 1.01 1.01  90th Percentile Day 0.93 0.91 0.86 0.93 0.99 1.00 1.00  Avg 20% Worst Days 0.89 0.89 0.84 0.89 0.94 0.95 0.95  Annual Average 0.91 0.91 0.87 0.92 0.97 0.99 0.99 * Test 1 - Calpuff run with default BART screening protocol + full emissions inventory + boundary conditions Test 2 - Calpuff as in Test 1 but using CEMS hrly emissions (SO2, NOX) where available Test 3 - Calpuff as in Test 1 but using WRAP MM5 12km mesoscale data (in CALMET) Test 4 - Calpuff as in Test 1 but assuming boundary air mass depth as 3000 m rather than 2000 m Test 5 - Calpuff as in Test 1 but with addition of NO3 and SO4 emissions from point sources Test 6 - Calpuff as in Test 1 but assuming boundary air mass depth as 3000 m (Test 4) and with  addition of NO3 and SO4 emissions from point sources (Test 5). Area sources configured as 4 groups and Beulah hourly profile used for backgound NH3.  Test 7 - Calpuff as in Test 6 but Beulah hourly NH3 profile doubled for Lostwood

Hybrid CMAQ-CALPUFF*

Test 1 Test 2 Test 3 Test 4 Test 5 Test 6 Test 7

TRSU NO3 98th Percentile Day 1.04 1.04 1.08 0.97 1.04 1.01 1.01  90th Percentile Day 1.24 1.21 1.28 1.18 1.21 1.00 1.00  Avg 20% Worst Days 1.12 1.12 1.16 1.10 1.12 0.99 0.99  Annual Average 1.42 1.42 1.46 1.40 1.42 1.06 1.06 TRSU SO4 98th Percentile Day 0.78 0.78 0.75 0.77 0.78 0.78 0.78  90th Percentile Day 0.91 0.91 0.88 0.94 0.91 0.95 0.95  Avg 20% Worst Days 0.81 0.81 0.75 0.81 0.81 0.82 0.82  Annual Average 0.87 0.87 0.83 0.87 0.88 0.88 0.88 Lostwood NO3 98th Percentile Day 0.52 0.52 0.55 0.53 0.51 0.59 0.75  90th Percentile Day 0.76 0.77 0.80 0.75 0.74 0.58 0.90  Avg 20% Worst Days 0.67 0.67 0.69 0.65 0.64 0.56 0.87  Annual Average 0.89 0.89 0.92 0.87 0.85 0.59 1.01 Lostwood SO4 98th Percentile Day 0.94 0.94 0.88 0.93 1.00 1.01 1.01  90th Percentile Day 0.93 0.91 0.86 0.93 0.99 1.00 1.00  Avg 20% Worst Days 0.89 0.89 0.84 0.89 0.94 0.95 0.95  Annual Average 0.91 0.91 0.87 0.92 0.97 0.99 0.99 * Test 1 - Calpuff run with default BART screening protocol + full emissions inventory + boundary conditions Test 2 - Calpuff as in Test 1 but using CEMS hrly emissions (SO2, NOX) where available Test 3 - Calpuff as in Test 1 but using WRAP MM5 12km mesoscale data (in CALMET) Test 4 - Calpuff as in Test 1 but assuming boundary air mass depth as 3000 m rather than 2000 m Test 5 - Calpuff as in Test 1 but with addition of NO3 and SO4 emissions from point sources Test 6 - Calpuff as in Test 1 but assuming boundary air mass depth as 3000 m (Test 4) and with  addition of NO3 and SO4 emissions from point sources (Test 5). Area sources configured as 4 groups and Beulah hourly profile used for backgound NH3.  Test 7 - Calpuff as in Test 6 but Beulah hourly NH3 profile doubled for Lostwood

Hybrid CMAQ-CALPUFF*
132 

As shown in Tables 8.9 and 8.10, the primary metrics selected to measure performance for this 

evaluation are 90th percentile day concentration (24-hour average), average of 20% worst days 

concentration, and annual average concentration. The first two metrics were selected for 

consistency with the time scale that applies to regional haze modeling, i.e., average of the 20% 

worst or 20% best days. The third metric, annual average concentration, is a measure of the 

model’s ability to accurately conserve total annual mass. The comparison between predicted and 

observed concentrations for the first two metrics is unpaired in time. 

Also shown in Tables 8.9 and 8.10 is the 98th percentile day prediction (24-hour average). This

metric was included for completeness at the request of EPA. The 98th percentile prediction has 

relevance as the primary metric used in BART single-source modeling. 

Results in Tables 8.9 and 8.10 indicate that the hybrid modeling system performed well, in 

general. Even for the initial Test 1, predictions were well within a factor of two of observations. 

In most cases, the hybrid system predictions were closer to observations than predictions from 

CMAQ, alone. Table 8.10 illustrates that the hybrid system slightly over-predicted observations 

for TRNP NO3, and slightly under-predicted, otherwise. 

A comparison of results for Tests 1 through 5 reveals very little difference in predictions. The 

implication is that the input changes reflected in Tests 2 through 5 did not add significant value 

to the hybrid model’s ability to accurately reproduce observations. The increased temporal 

resolution obtained by using the CEMS hourly emissions for applicable point sources (Test 2) 

provided no consistent improvement. Test 3 results suggest that the NDDoH RUC mesoscale 

data is consistent with the WRAP MM5 mesoscale data. Test 4 results indicate that Calpuff is 

not very sensitive to boundary air mass depth. Even the addition of point source NO3 and SO4

emissions in Test 5 achieved no meaningful improvement in predictions, suggesting that sources 

configured as area sources in CALPUFF may have only a small contribution to the total 

prediction. 

While the operational evaluation to compare predictions with observations was being conducted, 

the NDDoH also undertook a preliminary diagnostic evaluation45 to assess the response of the 

hybrid modeling system to changes in NOX and SO2 emissions. In response to significant 

reductions in both SO2 and NOX emissions, the NDDoH found that the hybrid system responded 

reasonably well with correspondingly lower SO4 predictions, but seemed to overstate NO3

predictions for the reduced emission scenario. In fact, NO3 concentrations actually increased 

under some assumptions, possibly an overreaction to the newly freed ammonia in the reduced 

SO2 emissions scenario (SO2 preferentially scavenges ammonia in the CALPUFF chemistry). 

This behavior was not as obvious in the WRAP CMAQ results for baseline versus future 

predictions. 

 

45 See supra note 7. 
133 

To address the problematic NO3 response, the NDDoH discussed the issue with Joe Scire 

(TRC)46, a recognized CALPUFF expert in the regulatory modeling community. Mr. Scire 

indicated that TRC testing has shown that the NO3 response may improve if hourly background 

ammonia is used rather than monthly average values. Also, Mr. Scire provided some insight on 

configuring area sources in CALPUFF to be more consistent with the area source treatment in 

CMAQ. This involves proper settings for the CALPUFF “release height” and “initial sigma z” 

input parameters for area sources. The NDDoH retested after incorporating Mr. Scire’s 

suggestions, i.e., using hourly ammonia background and reconfigured area sources. Although 

the NO3 response improved, predicted reductions were still not consistent with CMAQ. 

As a result of the initial diagnostic performance testing, the NDDoH concluded that the use of 

hourly ammonia background concentrations is preferable to the use of monthly averages, and 

that CALPUFF inputs for area sources should be reconfigured. Additional operational 

evaluation tests (Tests 6 and 7) were thus conducted to determine how these changes would 

affect the comparison with observations. Test 6 was conducted by first assuming a boundary air 

mass depth of 3000 meters (Test 4) and accounting for NO3 and SO4 emissions from point 

sources (Test 5). Then area sources were configured as suggested by Scire, including the use of 

4 area source groups to account for varying release heights for different source categories (as 

opposed to one group in Tests 1-5). Finally, Test 6 included use of the Beulah hourly ammonia 

profile in POSTUTIL. 

Results of Test 6, as shown in Tables 8.9 and 8.10, indicate significantly improved performance 

with respect to TRNP NO3, but worse performance for LWA NO3. Results for SO4 were not 

significantly affected. This tendency for conflicting results for TRNP and LWA NO3 was also 

exhibited in Tests 1 through 5, and led the NDDoH to conclude that the Beulah data may not be 

representative of ammonia background for both TRNP and LWA. Moreover, the actual 

ammonia background affecting LWA may be significantly higher than the background affecting 

TRNP. 

In Test 7, the NDDoH found that observational agreement for LWA NO3 can be vastly improved 

if the ammonia hourly backgound values are approximately doubled (for LWA only). All other 

conditions for Test 7, including the ammonia background for TRNP, remain the same as in Test 

6. NO3 predictions for Test 7 in Tables 8.9 and 8.10 now show good agreement with 

observations at both TRNP and LWA. 

Finally, the NDDoH developed time series plots (consistent with Test 1 assumptions) to compare 

temporal patterns of predictions with observations for year 2002. In Figure 8.11, daily model 

predictions for nitrate at TRNP are compared with IMPROVE observations for 2002 (note that 

observations are only available for every third day). Time series for both NDDoH hybrid 

predictions and WRAP CMAQ predictions are included. As shown in the figure, both modeling 

systems appear to reproduce the general seasonal pattern of nitrate observations, with 

significantly lower concentrations in the summer. When compared with observations, the overall 

magnitude of predictions for the hybrid modeling system appears better, as CMAQ seems to 

under predict in the summer (many daily values very close to 0.0) and over predict otherwise. 

 

46 See supra note 28. 
134 

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Conc. (ug/m3)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Conc. (ug/m3)

NDDoH Hybrid Predicted

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

01/02/0201/16/0201/30/0202/13/0202/27/0203/13/0203/27/0204/10/0204/24/0205/08/0205/22/0206/05/0206/19/0207/03/0207/17/0207/31/0208/14/0208/28/0209/11/0209/25/0210/09/0210/23/0211/06/0211/20/0212/04/0212/18/02

Conc. (ug/m3)

Date

WRAP CMAQ Predicted
135 

CMAQ, however, may be more effective in reproducing some of the peak observed 

concentrations (paired in time). 

In summary, the NDDoH concluded that the hybrid modeling system performs effectively, and 

may be used to adjust WRAP CMAQ modeling results. Further, agreement with sulfate and 

nitrate observations would be optimized using the following input conditions with the hybrid 

system: 

• use RUC mesoscale data for CALMET, 

• use boundary air mass depth of 3000 meters, 

• include SO4 and NO3 emissions from point sources, 

• configure area sources as four groups, 

• use Beulah hourly background ammonia for TRNP, and 

• use double Beulah hourly background ammonia for LWA. 

8.6.2 Results for Default EPA Methodology 

8.6.2.1 Cumulative Results 

The NDDoH hybrid modeling system was applied to adjust WRAP CMAQ results, using input 

conditions and procedures consistent with optimal model performance, and described in Section 

8.5. Hybrid modeling for the default EPA methodology included the entire emissions inventory. 

NDDoH projections for 2018 visibility are compared here with WRAP RMC projections for 

2018 visibility, based on default EPA methodology. 

Results of WRAP CMAQ and NDDoH hybrid visibility modeling for the default EPA scenario 

are summarized in Table 8.11. The table includes visibility projections for North Dakota Class I 

areas for 20% worst monitored days and 20% best monitored days. The table includes deciview 

values for baseline conditions, natural conditions, and the 2018 uniform rate of progress (URP) 

target. WRAP and NDDoH projections provided in the table include the absolute visibility 

projection in deciviews, and the percentage of the visibility target achieved by the projection. 

Note that the URP target and projected percentage of target are not included for best days, 

because the Regional Haze Rule specifies the URP target only for worst days. The requirement 

for best days is simply that the visibility projection for 2018 is no higher than the baseline 

monitored value. 
136 

Table 8.11 

WRAP and NDDoH Visibility Modeling Results 

Uniform Rate of Progress – Default EPA Methodology 

Class I 

Area 

20%

Worst/Best 

Days 

2000-2004 

Baseline 

Conditions 

(dv) 

2064 

Natural 

Conditions 

(dv) 

2018 

URP 

Target 

(dv) 

WRAP 

2018 

Projected 

Visibility 

(dv) 

WRAP 

2018 

Projected 

Percent of 

Target 

NDD

20

Proje

Visib

(d

Theodore 

Roosevelt 

National Park

Worst 17.80 7.8 15.47 17.24 24.0 16

Best 7.76 3.04 ----- 7.67 ----- 7.6

Lostwood 

Wilderness 

Area 

Worst 19.57 8.0 16.87 19.12 16.7 18

Best 8.19 2.92 ----- 8.06 ----- 8.
137 

Figure 8.12 

TRNP Uniform Rate of Progress – EPA Default Methodology

2004 2024 2044 

Year

68

1012141618

Deciview

Predicted Progress to 2018

WRAP - 1NDDH - 2

All Sources Glide Path

1

2

2018
138 

Figure 8.13 

LWA Uniform Rate of Progress – EPA Default Methodology 

2004 2024 2044 

Year

68

101214161820

Deciview

Predicted Progress to 2018

WRAP - 1NDDH - 2

All Sources Glide Path

1

2

2018
139 

As shown in Table 8.11, the NDDoH projections for 20% worst days indicate greater progress 

with respect to the 2018 goals than the WRAP projections, but both sets of projections fall well 

short of the URP targets. The WRAP projection constitutes 24.0 percent of the visibility goal at 

Theodore Roosevelt National Park (TRNP), while the NDDoH projection is 37.1 percent of the 

goal at that Class I area. For Lostwood Wilderness Area (LWA), WRAP projects 16.7 percent of 

the URP goal while the NDDoH projects that 26.3 percent of the goal will be achieved. 

On the 20% best monitored days, both WRAP and NDDoH predictions in Table 8.11 illustrate 

that 2018 visibility will be better than baseline monitored values for both TRNP and LWA Class 

I areas. The WRAP 2018 projection of 7.67 deciviews and the NDDoH 2018 projection of 7.63 

deciviews compare favorably with the baseline value of 7.76 deciviews for TRNP. At the LWA 

Class I area, the WRAP 2018 prediction of 8.06 deciviews and the NDDoH prediction of 8.10 

deciviews both fall below the baseline value of 8.19 deciviews. Thus, requirements of the 

Regional Haze rule for the 20% best days will be satisfied. 

Worst-day results of WRAP and NDDoH visibility modeling for the EPA default scenario are 

graphically interpreted with respect to the uniform rate of progress in Figure 8.12 and Figure 

8.13 for TRNP and LWA, respectively. The “all sources” glide paths in Figures 8.12 and 8.13 

originate with the monitored baseline deciview value in 2004, and terminate with the natural 

background deciview value in 2064. Using the same point of origination, the projected visibility 

progress is plotted against the glide path in each figure. 

Figures 8.12 and 8.13 illustrate how NDDoH hybrid modeling projects better visibility 

improvement to 2018 than WRAP CMAQ modeling for both Class I areas. The figures also 

illustrate how far WRAP and NDDoH projections are from meeting the 2018 URP targets for 

20% worst day visibility. 

8.6.2.2 Apportionment by Species 

The contribution of individual visibility-affecting species to total observed and projected light 

extinction for 20% worst/best days is discussed here. According to the IMPROVE algorithm, 

light affecting species include sulfate (SO4), nitrate (NO3), organic carbon (OMC), elemental 

carbon (EC), fine soil (Soil), coarse material (CM), and sea salt (SS). An additional component 

of light extinction which is included in the IMPROVE algorithm is Rayleigh scattering (Ray), 

which was also addressed in the projection of future visibility. 

IMPROVE speciated monitoring data for 20% worst days at TRNP and LWA are summarized in 

the bar charts of Figures 8.14 and 8.15, respectively. The figures provide the percentage 

contribution of each visibility-affecting species, as well as Rayleigh scattering, to each 20% 

worst visibility day in baseline year 2004. The worst days are identified by month and day of the 

month at the bottom of the charts. 

As seen in Figures 8.14 and 8.15, most of the 20% worst day light extinction at North Dakota 

Class I areas is dominated by sulfate and nitrate contributions. Rayleigh scattering is also a 

significant component, but otherwise the contribution of other visibility-affecting species (OMC, 
140 

Figure 8.14 

IMPROVE 20% Worst Days – TRNP 2004 

0%

10%20%30%40%50%60%70%80%90%

100%

19 31 3 6 15 24 4 18 21 11 17 23 1 16 19 18 18 21 27 30 1

1 1 2 2 2 2 3 4 5 7 7 7 8 8 8 9 10 10 10 10 1

Contribution to Extinction 
141 

Figure 8.15 

IMPROVE 20% Worst Days – LWA 2004

0%

10%20%30%40%50%60%70%80%90%

100%

1 13 16 19 3 24 27 4 13 22 14 17 23 16 9 18 27 30 14 26 8 1 1 1 1 2 2 2 3 3 3 7 7 7 8 9 9 10 10 11 11 1

Contribution to Extinction 
142 

Table 8.12 

Summary of WRAP CMAQ Visibility Projections 

for Worst 20% Days at TRNP 

 

Monitored

2000-04 

Baseline 

Conditions

2064 

Natural 

Conditions

2018 

Uniform 

Rate of 

Progress 

Target

2018 

Projected 

Visibility 

Conditions

Baseline to 

2018 

Change In 

Statewide 

Emissions

Baseline to 

2018 

Change In 

Upwind 

Weighted 

Emissions2

Baseline to 

2018 

Change In 

Anthropo

genic 

Upwind 

Weighted 

Emissions2

(Mm-1) (Mm-1) (Mm-1)1(Mm-1) (tons / %) (%) (%)

-97,376

-57%

-37,211

-16%

 -1,692

-19%

-2,451

-51%

1,212

2%

12,744

4%

Sea Salt30.07 0.24 0.11

Total Light 

Extinction 61.62 22.14 48.41 58.26

Deciview 17.8 7.8 15.47 17.24

WRAP TSS

1) 2018 Uniform Rate of Progress Target for Best 20% Days is not defined.

2) Results based on Weighted Emissions Potential analysis using the 2000-04 Baseline (plan02d) & 

 2018 PRP (prp18a) emissions scenarios.

3) Visibility projections not available due to model performance issues.

Class I Area Visibility Summary: Theodore Roosevelt NP, ND

Visibility Conditions: Worst 20% Days

RRF Calculation Method: Specific Days (EPA)

Emissions Scenarios: 2000-04 Baseline (plan02d) & 2018 PRP 

(prp18a)

Estimated Projected

27% 36%

Sulfate 17.53 1 12.23 15.94 -21%

3.92 8.95 10.94 -3%

-21%

Nitrate 13.74 1.04 9.85 12.5

-8%

Elemental 

Carbon 2.75 0.32 2.13 1.98 -28% -44%

Organic 

Carbon 10.82

Fine Soil 0.9 0.97 0.91

Coarse 

Material3

4.82 3.66 4.54

Not Applicable

1.02 5% 10%

Not 

Applicable

4% 13%
143 

Table 8.13 

Summary of WRAP CMAQ Visibility Projections for Best 20% Days at 

TRNP 

 

Monitored

2000-04 

Baseline 

Conditions

2064 

Natural 

Conditions

2018 

Uniform 

Rate of 

Progress 

Target

2018 

Projected 

Visibility 

Conditions

Baseline to 

2018 

Change In 

Statewide 

Emissions

Baseline to 

2018 

Change In 

Upwind 

Weighted 

Emissions2

Baseline to 

2018 

Change In 

Anthropo

genic 

Upwind 

Weighted 

Emissions2

(Mm-1) (Mm-1) (Mm-1)1(Mm-1) (tons / %) (%) (%)

-97,376

-57%

-37,211

-16%

 -1,692

-19%

-2,451

-51%

1,212

3%

12,744

6%

Sea Salt3

0.03 0.03

Not 

Applicable

Total Light 

Extinction 21.86 13.57

Not 

Applicable 21.67

Deciview 7.76 3.04

Not 

Applicable 7.67

WRAP TSS

1) 2018 Uniform Rate of Progress Target for Best 20% Days is not defined.

2) Results based on Weighted Emissions Potential analysis using the 2000-04 Baseline (plan02d) & 

 2018 PRP (prp18a) emissions scenarios.

3) Visibility projections not available due to model performance issues.

Projected

Sulfate 3.82 0.44

Not 

Applicable

Class I Area Visibility Summary: Theodore Roosevelt NP, ND

Visibility Conditions: Best 20% Days

RRF Calculation Method: Specific Days (EPA)

Emissions Scenarios: 2000-04 Baseline (plan02d) & 2018 PRP 

(prp18a)

Estimated

3.88 -9% -9%

Nitrate 1.52 0.31

Not 

Applicable 1.41 37% 49%

0.1

Not 

Applicable 0.73 -28% -42%

-4% -8%

18%

Fine Soil 0.4 0.21

Not 

Applicable

1.99

0.72

Not 

Applicable

Organic 

Carbon 1.98 0.74

Not 

Applicable

Not 

Applicable

6%

Elemental 

Carbon 0.93

Not Applicable

0.43 6% 13%

Coarse 

Material32.19
144 

Table 8.14 

Summary of WRAP CMAQ Visibility Projections 

for Worst 20% Days at LWA 

Monitored

2000-04 

Baseline 

Conditions

2064 

Natural 

Conditions

2018 

Uniform 

Rate of 

Progress 

Target

2018 

Projected 

Visibility 

Conditions

Baseline to 

2018 

Change In 

Statewide 

Emissions

Baseline to 

2018 

Change In 

Upwind 

Weighted 

Emissions2

Baseline to 

2018 

Change In 

Anthropo

genic 

Upwind 

Weighted 

Emissions2

(Mm-1) (Mm-1) (Mm-1)1(Mm-1) (tons / %) (%) (%)

-97,376

-57%

-37,211

-16%

 -1,692

-19%

-2,451

-51%

1,212

2%

12,744

4%

Sea Salt30.26 0.52 0.32

Total Light 

Extinction 74.05 22.52 55.93 70.78

Deciview 19.57 8 16.87 19.12

WRAP TSS

1) 2018 Uniform Rate of Progress Target for Best 20% Days is not defined.

2) Results based on Weighted Emissions Potential analysis using the 2000-04 Baseline (plan02d) & 

 2018 PRP (prp18a) emissions scenarios.

3) Visibility projections not available due to model performance issues.

Class I Area Visibility Summary: Lostwood NWRW, ND

Visibility Conditions: Worst 20% Days

RRF Calculation Method: Specific Days (EPA)

Emissions Scenarios: 2000-04 Baseline (plan02d) & 2018 PRP 

(prp18a)

Estimated Projected

-9%

Nitrate 22.94 1.1 15.56 21.94 -16% -19%

Sulfate 21.4

3.79 9.07

1.05 14.61 19.21 -9%

11.68 -7% -11%

Elemental 

Carbon 2.84 0.36 2.21 2.07 -32% -40%

Organic 

Carbon 11.05

Coarse 

Material3

3.93 3.74 3.89

Fine Soil 0.62 0.95 0.7

Not Applicable

0.69 -14% -19%

Not 

Applicable

-3% -5%
145 

Table 8.15 

Summary of WRAP CMAQ Visibility Projections 

for Best 20% Days at LWA 

Monitored

2000-04 

Baseline 

Conditions

2064 

Natural 

Conditions

2018 

Uniform 

Rate of 

Progress 

Target

2018 

Projected 

Visibility 

Conditions

Baseline to 

2018 

Change In 

Statewide 

Emissions

Baseline to 

2018 

Change In 

Upwind 

Weighted 

Emissions2

Baseline to 

2018 

Change In 

Anthropo

genic 

Upwind 

Weighted 

Emissions2

(Mm-1) (Mm-1) (Mm-1)1(Mm-1) (tons / %) (%) (%)

-97,376

-57%

-37,211

-16%

 -1,692

-19%

-2,451

-51%

1,212

3%

12,744

6%

Sea Salt3

0.03 0.03

Not 

Applicable

Total Light 

Extinction 22.89 13.4

Not 

Applicable 22.58

Deciview 8.19 2.92

Not 

Applicable 8.06

WRAP TSS

1) 2018 Uniform Rate of Progress Target for Best 20% Days is not defined.

2) Results based on Weighted Emissions Potential analysis using the 2000-04 Baseline (plan02d) & 

 2018 PRP (prp18a) emissions scenarios.

3) Visibility projections not available due to model performance issues.

Projected

Sulfate 4.39 0.42

Not 

Applicable

Class I Area Visibility Summary: Lostwood NWRW, ND

Visibility Conditions: Best 20% Days

RRF Calculation Method: Specific Days (EPA)

Emissions Scenarios: 2000-04 Baseline (plan02d) & 2018 PRP 

(prp18a)

Estimated

4.47 -1% -1%

Nitrate 1.86 0.34

Not 

Applicable 1.65 -16% -19%

0.1

Not 

Applicable 0.52 -31% -38%

-8% -12%

-10%

Fine Soil 0.34 0.22

Not 

Applicable

2.27

0.63

Not 

Applicable

Organic 

Carbon 2.26 0.66

Not 

Applicable

Not 

Applicable

-6%

Elemental 

Carbon 0.71

Not Applicable

0.33 -20% -25%

Coarse 

Material32.31
146 

EC, Soil, CC, and SS) is generally very small. The exception is worst days in late July and 

August, where organic carbon replaces sulfate and nitrate as the dominate contributor to 

extinction. This pattern was similar in other years of IMPROVE baseline data (2000-2003). A 

possible explanation is that fugitives associated with agricultural burning, prescribed burning 

within Class I areas, and wild fires may be the largest contributors to light extinction during late 

July and August, while emissions from conventional large point sources are the largest 

contributors during the remainder of the year. 

WRAP CMAQ modeling results for the default EPA methodology were used to review the 

contribution of individual visibility-affecting species to projected light extinction for 20% 

worst/best days (NDDoH hybrid modeling did not include all species). Summaries of WRAP 

CMAQ modeling results including 2018 projections for individual species are provided in Tables 

8.12 through 8.15. Tables 8.12 and 8.13 provide speciated summaries (averages) of 20% worst 

and best days, respectively, for TRNP. Tables 8.14 and 8.15 address speciated summaries of 

20% worst and best days, respectively, for LWA. The tables include light extinction values for 

baseline conditions, natural conditions, 2018 uniform rate of progress target, and 2018 projected 

visibility conditions for each visibility-affecting species. Values for total light extinction and 

deciview are provided as well (note these values are consistent with results in Table 8.11). Note 

that 2018 projected values are not provided for CM and SS species, due to model performance 

issues. For these species, WRAP (and NDDoH) assumed an RRF of 1.0, and set the 2018 

projection equal to the monitored baseline value. 

In reviewing the 20% worst day summaries for TRNP and LWA in Tables 8.12 and 8.14, 

respectively, sulfate and nitrate are found to be the largest contributors to light extinction. This 

is true for both baseline monitored conditions and for future (2018) projected conditions. 

Because of its dominance in the late summer months, organic carbon is also a major overall 

contributor to 20% worst day light extinction for both baseline monitored and future projected 

conditions. As discussed previously, WRAP modeling results for 20% worst days (summarized 

in Tables 8.12 and 8.14) indicate the total light extinction URP target will not be achieved at 

either TRNP or LWA. Further, results for individual species indicate the URP species-specific 

target will be met only for elemental carbon and sea salt. 

The 20% best day summaries for TRNP and LWA are reported in Tables 8.13 and 8.15, 

respectively. With exception of sea salt, all species appear to be significant contributors to light 

extinction on 20% best days. Sulfate is the largest contributor at both TRNP and LWA. As 

shown in the tables, the 2018 projected light extinction is lower than the baseline light extinction 

for both Class I areas. Thus, Regional Haze Rule requirements for 20% best days will be 

satisfied at TRNP and LWA for the first planning period. 

Note that the WRAP projected emissions values for nitrate (NOX) in Tables 8.12 through 8.15 

are not consistent with the levels used by NDDoH in hybrid modeling. The NDDoH adjusted the 

WRAP NOX emissions associated with oil and gas activity, as described in Section 8.5.3.1. 

 
147 

8.6.2.3 Apportionment by Source Group 

As established in Section 8.6.2.2, sulfate and nitrate are the primary contributors to 20% worst 

day visibility in North Dakota Class I areas. In its hybrid modeling analysis, the NDDoH tracked 

the contribution of source groups to the total predicted sulfate and nitrate concentration for 20% 

worst days, in order to enhance the interpretation of modeling results. Contributions are 

available for the following source groups: 

• North Dakota electrical generating units (EGU), 

• all other point sources within the CALPUFF domain, 

• all sources modeled as area sources within the CALPUFF domain, 

• North Dakota oil and gas related sources (O&G), and

• boundary conditions representing the impact of all sources located outside of the CALPUFF 

domain. 

Focus is on the ND EGU and boundary condition groups because of their relatively small and 

large contributions, respectively. O&G contributions are available for sulfate, only. 

Contributions of the above source groups to 20% worst day average predictions, based on 

NDDoH hybrid modeling, are illustrated in Figures 8.16 through 8.19. Predictions for the base 

period (2000-2004) are compared with predictions for the future period (2018) in the figures. 

Contributions for sulfate at TRNP are compared in Figure 8.16. Figure 8.17 provides 

contributions for sulfate at LWA. Source group contributions for nitrate at TRNP are illustrated 

in Figure 8.18. Finally, Figure 8.19 addresses contributions for nitrate at LWA. Source group 

contributions in the figures reflect the percent of the total average predicted concentration for 

20% worst days. 

As consistently shown in Figures 8.16 through 8.19, the contribution of North Dakota EGUs to 

total sulfate and total nitrate is relatively small, while the contribution of boundary conditions is 

relatively large. This is true for both baseline and future projections. For sulfate, boundary 

conditions contributed no less than two-thirds of the total at North Dakota Class I areas. For 

nitrate, the boundary condition contribution was no less than 59 percent. The contribution of 

North Dakota EGUs to sulfate was no more than 21 percent, and to nitrate was no more than 6 

percent, at North Dakota Class I areas. 

As shown in Figures 8.16 and 8.17, the reduced impact from North Dakota EGUs due to BART 

controls is apparent. The projected future contribution of North Dakota EGUs to sulfate is less 

than one-half the baseline contribution for both TRNP and LWA. The difference for other 

source groups is less pronounced, although an exception would be area sources at LWA, where 

the baseline contribution of 4.0 percent is reduced to 2.4 percent in 2018. In comparing future 

with baseline contributions in Figures 8.16 and 8.17, it appears the contribution of boundary 
148 

Figure 8.16 

Hybrid Modeling Results 

Source Group Contributions to 20% Worst Day SO4 at TRNP (Base & Futu

ND EGU21.2%

Other Point5.8%

Area5.5%

ND O&G

Boundary 0.9%66.6%

2000-2004

ND EGU9.1%

Boundary78.9%

2018
149 

Figure 8.17 

Hybrid Modeling Results 

Source Group Contributions to 20% Worst Day SO4 at LWA (Base & Futu

ND EGU12.4%

Other Point9.1%

Area4.0%

ND O&G0.9%

Boundary73.6%

2000-2004

ND EGU5.3%

Boundary81.7%

2018
150 

Figure 8.18 

Hybrid Modeling Results 

Source Group Contributions to 20% Worst Day NO3 at TRNP (Base & Futu

ND EGU6.3%

Other Point6.3%

Area28.4%

Boundary59.0%

2000-2004

ND EGU5.2%

Boundary59.0%

2018
151 

Figure 8.19 

Hybrid Modeling Results 

Source Group Contributions to 20% Worst Day NO3 at LWA (Base & Futu

ND EGU4.4%

Other Point9.1%

Area26.4%

Boundary60.1%

2000-2004

ND EGU4.8%

Boundary58.8%

2018
152 

conditions is increasing as the contribution of North Dakota EGUs decreases in the future (other 

source groups remain relatively stable). 

In Figures 8.18 and 8.19, the difference between future and baseline contributions for nitrate is 

less apparent than for sulfate. Percentage contributions for nitrate remained relatively stable 

from baseline to future for both Class I areas. Reduction in NOX emissions due to BART 

controls was less than BART reductions for SO2, but the NOX reduction was still significant. 

This lack of response to future BART reductions in NOX may be linked to the CALPUFF 

chemistry, and the tendency observed in the performance evaluation (Section 8.6.1) for NO3

production to overreact to newly freed ammonia from the lower production of SO4. 

NDDoH hybrid modeling results were further refined in order to extract the contribution of all 

North Dakota sources to total predicted sulfate and nitrate concentrations for 20% worst days. 

This additional source group includes all North Dakota EGUs, all North Dakota point sources 

other than EGUs, and all North Dakota emissions modeled as area sources. Because the NDDoH 

CALPUFF domain excludes the far eastern part of North Dakota, some adjustments in inventory 

and procedure were necessary to estimate the contribution of this source group. 

Contributions of the North Dakota only source group to total sulfate and nitrate are summarized 

in Table 8.16. Percentage contributions are provided for baseline and future predicted 

concentrations at both North Dakota Class I areas. As shown in the table, contributions from 

North Dakota sources are relatively small and comprise no more than 29 percent of the total 

prediction for 20% worst days. Significant reduction in future sulfate concentrations due to 

BART controls on North Dakota EGUs is again apparent. 

Table 8.16 

Hybrid Modeling Results 

Total North Dakota Contribution to 20% Worst Days Predictions 

Class I Area Baseline Percent 2018 Percent 

SO4

TRNP 27.3 15.0 

LWA 17.6 9.7 

NO3

TRNP 29.0 28.6 

LWA 26.4 28.7 
153 

The relatively small contributions of North Dakota EGUs (and North Dakota sources in general) 

and the relatively large contributions of boundary conditions to 20% worst day visibility in North 

Dakota Class I areas, as observed in Figures 8.16 through 8.19, and Table 8.16, translates to 

restricted options for meeting visibility progress goals. These results indicate that most of the 

visibility impact on the 20% worst days in North Dakota Class I areas is due to impact from 

sources located outside of the State, and beyond the jurisdiction of the NDDoH. From additional 

hybrid modeling, the NDDoH found that even with all future North Dakota SO2 and NOX

emissions reduced to zero, North Dakota Class I areas would not achieve the 2018 uniform rate 

of progress target (see Section 8.6.3). 

Weight of evidence perspectives which address the contributions of sources located outside of 

North Dakota to worst day visibility at TRNP and LWA are discussed in Section 8.6.3. 

8.6.2.4 Apportionment by Source Region 

Visibility modeling conducted by WRAP RMC for North Dakota Class I areas included sourceregion attribution for all western states, central US, eastern US, Mexico, and Canada. In 

addition, WRAP also tracked the contribution of sources located outside of the CMAQ domain 

which includes the contiguous United States, southern Canada, and northern Mexico. 

Results of the WRAP attribution analysis are summarized in the bar charts of Figures 8.20 

through 8.23. These charts provide source-region contributions to baseline (PLAN02c) predicted 

concentrations of sulfate and nitrate for the 20% worst days. Figures 8.20 and 8.21 provide 

source region contributions for sulfate and nitrate, respectively, at TRNP. Figures 8.22 and 8.23 

provide the corresponding contributions at LWA. Along with the bars labeled with familiar 

abbreviations for western states, the figures also include contributions with the following labels: 

CAN – Canada, 

CEN – Central US (CENWRAP), 

EUS – Eastern US, 

MEX – Mexico, 

PO – Pacific Offshore, and 

OD – Outside WRAP US-Canada-Mexico Modeling Domain. 

The bar charts used in Figures 8.20 through 8.23 were obtained from the WRAP TSS web site. 

Note that the values in the charts actually reflect WRAP case PLAN02c, which is a predecessor 

to the updated PLAN02d. The differences between PLAN02c and PLAN02d, however, are not 

significant enough to affect conclusions regarding these charts. 

In reviewing the bar charts of Figures 8.20 and 8.22, it is seen that emissions from North Dakota, 

Canada, and from outside the WRAP US-Canada-Mexico modeling domain (Figure 8.1) 

dominate total sulfate concentrations at North Dakota Class I areas on the 20% worst visibility 

days. The contribution of sources located outside the WRAP domain is larger than the 
Source Region Contributions to 20% Worst Day SO

Source Region Contributions to 20% Worst Day NO

Source Region Contributions to 20% Worst Day SO

Figure 

WRAP Modeling Results

Figure 

WRAP Modeling Results

Source Region Contributions to 20% Worst Day NO

154 

Figure 8.20

WRAP Modeling Results

Source Region Contributions to 20% Worst Day SO

Figure 8.21

WRAP Modeling Results

Source Region Contributions to 20% Worst Day NO

WRAP Modeling Results

Source Region Contributions to 20% Worst Day SO

WRAP Modeling Results

Source Region Contributions to 20% Worst Day NO

4 at TRNP (baseline)

3 at TRNP (baseline)
Source Region Contributions to 20% Worst Day SO

Source Region Contributions to 20% Worst Day NO

Source Region Contributions to 20% Worst Day SO

Figure 

WRAP Modeling 

Figure 

WRAP Modeling Results

Source Region Contributions to 20% Worst Day NO

155 

Figure 8.22

WRAP Modeling Results

Source Region Contributions to 20% Worst Day SO

Figure 8.23

WRAP Modeling Results

Source Region Contributions to 20% Worst Day NO

Results

Source Region Contributions to 20% Worst Day SO

WRAP Modeling Results

Source Region Contributions to 20% Worst Day NO

4 at LWA (baseline)

3 at LWA (baseline)
156 

contribution from North Dakota sources at both Class I areas, and the contribution of Canadian 

emissions is significantly larger than the contribution from North Dakota sources at both Class I 

areas. 

From Figures 8.21 and 8.23, one observes a similar pattern of dominant source-region 

contributors for 20% worst day nitrate concentrations, except that Montana becomes a dominate 

contributor in addition to North Dakota, Canada, and sources located outside of the WRAP 

domain. The overall dominance of Canadian emissions is even greater for nitrate than for 

sulfate, and at LWA the contribution to 20% worst day nitrate concentrations from Canadian 

sources is more than three times the contribution from North Dakota sources. 

These source-region apportionment results illustrate that most of the contributions to 20% worst 

day nitrate and sulfate (species with the greatest effect on visibility impairment) at North Dakota 

Class I areas come from sources located outside of the state. Again, these sources are beyond the 

jurisdiction of the NDDoH, which poses a dilemma when seeking solutions for achieving 

visibility goals. This issue was addressed in the NDDoH weight of evidence interpretations 

which are discussed in Section 8.6.3. 

8.6.2.5 Conclusions 

Visibility progress modeling was conducted by WRAP and NDDoH using the default EPA 

methodology. This modeling was based on preliminary estimates of the effect of BART 

controls, and other growth and control factors. Results have been discussed in terms of general 

status with respect to the uniform rate of progress for North Dakota Class I areas, and in terms of 

apportionment by species, source group, and source region. Based on these modeling results, the 

following conclusions apply. 

1) The uniform rate of progress goal for 2018 for 20% worst days will not be achieved at either 

TRNP or LWA. Therefore, weight of evidence arguments were addressed (see Section 

8.6.3). 

2) The Regional Haze Rule requirement for 2018 for 20% best days will be achieved at both 

TRNP and LWA. 

3) NDDoH hybrid modeling (adjusted WRAP CMAQ) predicted better progress with respect to 

the 20% worst day uniform rate of progress goals than did WRAP modeling, at both TRNP 

and LWA. 

4) Apportionment modeling results indicate the contribution of sources located outside of North 

Dakota is much greater than the contribution of in-state sources to 20% worst day visibility at 

TRNP and LWA (both baseline and 2018). 

5) Though the addition of proposed BART controls substantially decreases the visibility impact 

of North Dakota EGUs, these EGUs comprise only a small component of total 20% worst 

day impact at TRNP and LWA. However, on certain worst days when meteorology favors 
157 

transport of North Dakota EGU emissions to TRNP or LWA, proposed BART reductions 

alone will significantly improve visibility. 

6) Of the visibility affecting aerosols, sulfate and nitrate are primary contributors to 20% worst 

day visibility at North Dakota Class I areas. 

7) The primary source-region contributors to 20% worst day visibility at TRNP and LWA are 

Canada, sources located outside of the WRAP modeling domain, North Dakota, and Montana 

(in that order). 

8) When implemented as an adjustment to WRAP CMAQ modeling results, the NDDoH hybrid 

modeling approach is not critically tied to the parameterized CALPUFF chemistry. 

8.6.3 Weight of Evidence Options 

WRAP and NDDoH visibility modeling based on the default EPA methodology and glide path 

has been reviewed, with results as discussed in Section 8.6.2. Because projected 2018 visibility 

did not meet uniform rate of progress goals for 20% worst days in North Dakota Class I areas, 

the NDDoH pursued alternative or supplemental modeling approaches, which are discussed here. 

The Regional Haze Rule specifies that the State Implementation Plan may be based, in part, on 

evidence apart from modeling using the default EPA methodology. For example, the analysis 

could logically be modified to discount the impact of visibility-affecting emission sources over 

which the NDDoH has no jurisdiction. 

These supplemental analyses are defined in the Rule as “weight of evidence” options. The 

following supplemental modeling analyses were conducted by NDDoH in the assessment of 

visibility progress goals. 

1) Discounted the impact of international (in this case, Canadian) source visibility-affecting 

emissions on North Dakota Class I areas. 

2) Discounted the impact of visibility-affecting emissions from all sources located outside of 

North Dakota, on North Dakota Class I areas. 

3) Used the complete emissions inventory for the default EPA method, but zeroed out future 

SO2 and NOX emissions from all sources located in North Dakota (i.e., assumed 100 percent 

future control of all SO2 and NOX emissions in North Dakota), to determine progress with 

respect to the default glide path for North Dakota Class I Areas. 

4) Based 20% worst visibility days for determining RRFs on baseline model results 

(CALPUFF) rather than IMPROVE monitoring data. This may be justified because neither 

CMAQ nor CALPUFF perform well on a “paired-in-time” basis. The resultant RRFs were 

still applied to 20% worst days based on IMPROVE monitoring to project future visibility. 

 
158 

Procedures and results for these supplemental, weight of evidence analyses are discussed in 

Sections 8.6.3.1 through 8.6.3.4. 

8.6.3.1 Discounting the Impact of Canadian Source Emissions 

The procedure used by the NDDoH to discount the impact of Canadian source emissions in the 

projection of future visibility at North Dakota Class I areas is consistent with the methodology 

described in Section 8.5.6.2. To discount the impact of Canadian source emissions on visibility 

projections, Canadian sources were removed from the baseline and future emissions inventories 

used with the hybrid modeling system to develop RRFs, and the URP glide path was adjusted by 

subtracting the impact of Canadian emissions from the baseline starting value. This weight of 

evidence analysis was applied for 20% worst days, only. The adjusted glide path is compared 

with the default glide path in Figure 8.24 for TRNP and LWA. 

Because the NDDoH hybrid modeling addresses S and N species only, the discounting of 

Canadian source impact was limited to sulfate and nitrate, only. The RRFs and projected future 

contribution to light extinction of other visibility affecting species remained unchanged from the 

default EPA methodology (i.e., included Canadian emissions). As sulfate and nitrate are the 

primary contributors to light extinction at North Dakota Class I areas on the 20% worst days (see 

Section 8.6.2.2), this limitation should not significantly impact conclusions based on this weight 

of evidence analysis. 

Note that once the glide path has been adjusted, the URP 2018 target value changes along with 

the baseline starting value (the adjusted glide path terminates at the same natural background 

value in 2064). Therefore, it is no longer meaningful to compare the 2018 projected progress 

with the absolute deciview target from the default EPA methodology (Table 8.11). Instead, for 

this weight of evidence scenario and others, 2018 progress is expressed as a percentage of the 

target rather than as a specific deciview value. 

The NDDoH procedure used to discount the impact of Canadian source emissions is outlined as 

follows. 

1) Canadian sources located within the NDDoH CALPUFF domain were eliminated from the 

HybridPt baseline and future emissions inventories to be used in Equation 8-3. 

2) CALPUFF hourly boundary conditions (baseline and future HybridPt) were adjusted to 

eliminate the contribution of Canadian (anthropogenic) source emissions (leaving only the 

contribution of natural background) for 3-km boundary segments located in Canada (see 

Figure 8.5). The fixed adjustment factor utilized represents the ratio of species-specific 

natural background light extinction to species-specific baseline monitored light extinction for 

the 20% worst day average, at each Class I area. The adjustment was applied to all boundary 

species (SO2, SO4, NOX, HNO3, and NO3). The SO4 ratio was used for scaling SO4 and SO2

species. The NO3 ratio was used for scaling NO3, HNO3, and NOX species. 

 
159 

3) Hybrid modeling was applied to prepare a revised glide path and 2018 target using Equation 

8-4 with the revised baseline emissions inventories (non-Canadian sources only) from Steps 

1 and 2, for each Class I area. The 3-step ammonia limiting method was applied to refine 

NO3 concentrations for non-Canadian sources. 

4) Hybrid modeling was applied to project future visibility using Equation 8-3 with the revised 

baseline and future emissions inventories (non-Canadian sources only) from Steps 1 and 2, 

for each Class I area. The 3-step ammonia limiting method was applied to refine NO3

concentrations for non-Canadian sources. 

5) The projected future deciview value was compared with the revised glide path 2018 target 

deciview value to calculate the percent of the 2018 target achieved, at each Class I area. 

Results of the weight of evidence analysis for discounting the impact of Canadian source 

emissions are summarized in Table 8.17 and illustrated in Figure 8.24. Uniform rate of progress 

illustrations in Figure 8.24 are provided for both TRNP and LWA Class I areas. For comparison, 

the table and figure also include previous WRAP and NDDoH results for the complete emissions 

inventory and default EPA methodology from Table 8.11. WRAP results for the default EPA 

methodology are labeled Scenario 1 and NDDoH results for the default EPA methodology are 

labeled Scenario 2. They are compared with the weight of evidence entry which is identified as 

Scenario 3. For each scenario, the table provides percentage progress with respect to the 2018 

target. 

 
160 

Table 8.17 

NDDoH Visibility Modeling Results 20% Worst Days 

Weight of Evidence – Discounting Canadian Emissions

Projected

Scenario Description Class I Area Percent of

2018 Target

 WRAP CMAQ TRNP 24.0

1 Default EPA Methodology

LWA 16.7

 NDDoH Hybrid TRNP 38.1

2 Default EPA Methodology

LWA 26.7

 NDDoH Hybrid TRNP 50.0

3 Canada Sources Discounted

LWA 40.2

As shown in Table 8.17 and Figure 8.24, progress with respect to the 2018 target is significantly 

improved when Canadian sources are discounted. The projected percent of the 2018 target with 

Canadian sources discounted is more than double the percentage obtained by WRAP for the 

default EPA methodology, and about 50 percent greater than the percentage obtained by NDDoH 

for the default EPA methodology, at both Class I areas. Though progress is significantly 
161 

Figure 8.24 

Uniform Rate of Progress 

EPA Default Methodology and Canadian Sources Discounted 

2004 2024 2044 2064

Year

6

8

10

12

14

16

18

20

Deciview

Predicted Progress to 2018

WRAP - Scenario 1

NDDoH - Scenarios 2,3

LWA

Al Sources Glide Path

Canadian Sources Discounted Glide Path

1

2

3

2018

2004 2024 2044 2064

Year

6

8

10

12

14

16

18

Deciview

Predicted Progress to 2018

WRAP - Scenario 1

NDDoH - Scenarios 2,3

TRNP

Al Sources Glide Path

Canadian Sources Discounted Glide Path

1

2

3

2018
162 

improved under this scenario, the potential for greater improvement was limited because the 

contribution of US sources located outside of the hybrid model domain is very large (with little 

emissions reduction in the future), and the scenario could only address the discounted impact of 

SO4 and NO3.

8.6.3.2 Discounting the Impact of All Sources Located Outside of North Dakota 

Because discounting the impact of Canadian emissions did not provide compliance with glide 

path targets, the NDDoH pursued other weight of evidence options. The next logical test after 

discounting Canadian emissions was to discount the visibility-affecting impact of all sources 

located outside of the jurisdiction of the NDDoH. Therefore, this new analysis discounted all 

contributions to North Dakota Class I areas, except for the impact of North Dakota sources and 

natural background. To discount the impact of all sources located outside of North Dakota on 

visibility projections, these sources were removed from the baseline and future emissions 

inventories used with the hybrid modeling system to develop RRFs, and the URP glide path was 

adjusted by subtracting the impact of these sources from the baseline starting value. This weight 

of evidence analysis was applied for 20% worst days, only. The adjusted glide path is compared 

with the default glide path in Figure 8.25 for TRNP and LWA. 

Since the CALPUFF domain used by the NDDoH for hybrid visibility modeling excludes the 

extreme eastern part of North Dakota, area emissions for the easternmost column of the area 

source grid (see Figure 8.8) were adjusted upward to account for the impact of eastern North 

Dakota sources. Specifically, WRAP CMAQ (SMOKE) emissions for all grid cells located 

between the eastern edge of the CALPUFF domain and the eastern North Dakota border were 

added to the easternmost column of the CALPUFF area source grid. This addition was 

performed on a row by row basis. Because eastern North Dakota visibility affecting sources are 

relatively small and distant from TRNP and LWA Class I areas, this adjustment should have 

minimal impact on modeling results. 

Because the NDDoH hybrid modeling addresses S and N species only, the discounting of out-ofstate source impact was limited to sulfate and nitrate, only. The RRFs and projected future 

contribution to light extinction of other visibility affecting species remained unchanged from the 

default EPA methodology (i.e., included complete emissions inventory). As sulfate and nitrate 

are the primary contributors to light extinction at North Dakota Class I areas on most of the 20% 

worst days (see Section 8.6.2.2), this limitation should not significantly impact conclusions based 

on this weight of evidence analysis. 

The procedure used by NDDoH to discount the impact of all sources located outside of North 

Dakota is similar to the 5-step procedure used to discount Canadian emissions, as outlined in 

Section 8.6.3.1., except that variables representing North Dakota sources replaced variables 

representing US sources in Equations 8.3 and 8.4. The procedure for discounting the impact of 

all out-of-state sources is outlined below. 

1) All out-of-state sources located within the NDDoH CALPUFF domain were eliminated from 

the HybridPt baseline and future emissions inventories to be used in Equation 8-3. 
163 

2) As discussed above, emissions from all sources located outside of CALPUFF domain, but 

inside North Dakota, were added to easternmost column of CALPUFF area source grid. 

3) CALPUFF hourly boundary conditions (baseline and future HybridPt) were scaled to 

eliminate the contribution of all out-of-state source emissions (leaving only the contribution 

of natural background) for all boundary segments. Scaling was based on the inverse distance 

squared weighted average of natural-to-baseline (2002) ratio from seven nearby IMPROVE 

monitoring locations. The ratio was obtained for the 20% worst day average SO4 and NO3

natural and baseline extinction for Theodore Roosevelt NP, Lostwood NWA, Medicine Lake 

NWA, UL Bend, Badlands NP, Wind Cave, and Voyageurs NP IMPROVE sites. The 

average SO4 ratio was used for scaling SO4 and SO2 species. The average NO3 ratio was 

used for scaling NO3, HNO3, and NOX species. 

4) Hybrid modeling was applied to prepare a revised glide path and 2018 target using Equation 

8-4 with the revised baseline emissions inventories from Steps 1 and 2, for each Class I area 

(equation variables for North Dakota sources replaced variables for US sources). The 3-step 

ammonia limiting method was applied to determine NO3 concentrations for North Dakota 

sources. 

5) Hybrid modeling was applied to project future visibility using Equation 8-3 with the revised 

baseline and future emissions inventories from Steps 1 and 2, for each Class I area (equation 

variables for North Dakota sources replaced variables for US sources). The 3-step ammonia 

limiting method was applied to determine NO3 concentrations for US sources. 

6) The projected future deciview value was compared with the revised glide path 2018 target 

deciview value to calculate the percent of the 2018 target achieved, at each Class I area. 

Results of the weight of evidence analysis for discounting the impact of all sources located 

outside of North Dakota are summarized in Table 8.18 and illustrated in Figure 8.25. Uniform 

rate of progress illustrations in Figure 8.25 are provided for both TRNP and LWA Class I areas. 

For comparison, the table and figure also include previous WRAP and NDDoH results for the 

complete emissions inventory with default EPA methodology from Table 8.11. WRAP results 

for the default EPA methodology are labeled Scenario 1 and NDDoH results for the default EPA 

methodology are labeled Scenario 2. They are compared with the new weight of evidence entry 

which is identified as Scenario 4. For each scenario, the table provides percentage progress with 

respect to the 2018 target. 

As shown in Table 8.18 and Figure 8.25, progress with respect to the 2018 target is significantly 

improved after discounting the impact of all sources located outside of North Dakota, but 

projections do not meet the revised glide path targets. Also, the improvement is notably better at 

TRNP than at LWA. A likely explanation is that the location of BART sources in North Dakota, 

combined with prevailing meteorology, favors visibility improvement at TRNP compared with 

improvement at LWA (i.e., when there are no out of state influences). 
164 

Table 8.18 

NDDoH Visibility Modeling Results 20% Worst Days 

Weight of Evidence – Discounting All Out-of-State Sources 

Projected

Scenario Description Class I Area Percent of

2018 Target

 WRAP CMAQ TRNP 24.0

1 Default EPA Methodology

LWA 16.7

 NDDoH Hybrid TRNP 38.1

2 Default EPA Methodology

LWA 26.7

 NDDoH Hybrid TRNP 83.9

4 All Sources Other Than ND Discounted

LWA 59.6

8.6.3.3 Use Default EPA Methodology with Zero North Dakota Future Emissions 

The NDDoH next examined a “what if” scenario to see what would happen if all North Dakota 

sources were controlled to the hypothetical maximum degree and simply emitted no SO2, SO4, 

NOX, or NO3 in the future case. The concept here was to determine if the 2018 URP targets for 

the default EPA methodology for 20% worst days could be achieved even under maximum 

(albeit unrealistic) control conditions for North Dakota sources. Hybrid modeling for the 

baseline case (HybridPt in Equation 8-3) included the complete emissions inventory as used for 

the NDDoH EPA methodology analysis. Future case modeling (HybridPt in Equation 8-3) 

included the complete emissions inventory as applied by NDDoH for EPA methodology, except 

that all emissions for sources located in North Dakota were reset to zero. For this scenario, the 

glide path remains consistent with the default EPA methodology scenario. 

Procedure for this new scenario followed the default EPA methodology, as discussed in Section 

8.5. The only change was in the future case emissions inventory, where the emission rates for all 

North Dakota point and area sources were reset to zero. Note that because extreme eastern North 

Dakota is not included in the NDDoH CALPUFF domain, it was not possible to model the effect 

of zero future emissions from that part of the state. However, because visibility-affecting 

sources in extreme eastern North Dakota are relatively small and distant from the Class I areas
165 

Figure 8.25 

Uniform Rate of Progress 

EPA Default Methodology and Non-ND Sources Discounted 

2004 2024 2044 2064

Year

6

8

10

12

14

16

18

Deciview

Predicted Progress to 2018

WRAP - Scenario 1

NDDoH - Scenarios 2,4

TRNP

Al Sources Glide Path

ND Sources Glide Path

1

2

4

2018

2004 2024 2044 2064

Year

6

8

10

12

14

16

18

20

Deciview

Predicted Progress to 2018

WRAP - Scenario 1

NDDoH - Scenarios 2,4

LWA

Al Sources Glide Path

ND Sources Glide Path

1

2

4

2018
166 

which are both located in the western part of the state, this limitation should not detract from 

conclusions established regarding the analysis. 

Results of the weight of evidence analysis involving zero future emissions for North Dakota 

visibility affecting sources are summarized in Table 8.19. For comparison, the table also 

includes previous WRAP and NDDoH results for the complete emissions inventory with default 

EPA methodology from Table 8.11. WRAP results for the default EPA methodology are labeled 

Scenario 1 and NDDoH results for the default EPA methodology are labeled Scenario 2. They 

are compared with the new weight of evidence entry which is identified as Scenario 5. For each 

scenario, the table provides percentage progress with respect to the 2018 target. 

As illustrated in Table 8.19, even with all future North Dakota SO2, SO4, NOX, and NO3

emissions set to zero, the URP 20% worst day targets for 2018 are not achieved at North Dakota 

Class I areas. This result is consistent with earlier conclusions in this report that most of the 

visibility affecting impact on TRNP and LWA is coming from sources located outside of North 

Dakota. The implication of this weight of evidence test is that compliance with 20% worst day 

URP targets at North Dakota Class I areas cannot be achieved without significant additional 

emissions reductions from visibility affecting sources located outside of North Dakota. 

Table 8.19 

NDDoH Visibility Modeling Results 20% Worst Days 

Weight of Evidence – Zero Future North Dakota Emissions 

Projected

Scenario Description Class I Area Percent of

2018 Target

 WRAP CMAQ TRNP 24.0

1 Default EPA Methodology

LWA 16.7

 NDDoH Hybrid TRNP 38.1

2 Default EPA Methodology

LWA 26.7

 NDDoH Hybrid TRNP 83.8

5 Base Emissions Inv = Default

 Future Emissions Inv = All ND LWA 72.6

S and N Emissions set to zero
167 

As indicated previously, the NDDoH CALPUFF visibility modeling was limited to the 

contribution of SO2, SO4, NOX, and NO3 species, only. Even if the effect of zeroing out all other 

visibility affecting species could have been accounted for, it is unlikely that 2018 URP targets for 

North Dakota Class I areas could have been achieved under this weight of evidence scenario. 

 

8.6.3.4 Base 20% Worst Days on Modeling Results Rather than IMPROVE 

 Monitoring Data 

Though both models perform well when predicting maximum concentrations over a period of 

time, CMAQ and CALPUFF are less reliable when performance tests are based on predictions 

paired with concurrent observations. But the reliance of the Regional Haze Rule on the 20% 

worst/best monitored days to track visibility progress implies that the modeling system must 

demonstrate some skill on a temporal basis. To address possible temporal performance 

limitations in the NDDoH hybrid modeling system, visibility projection results based on the 20% 

worst monitored days were compared with results based on the 20% worst modeled days for the 

baseline case. The following procedure was used to develop results based on worst modeled 

days. 

1) The hybrid modeling system was executed for the baseline case, using the emissions 

inventory for the default EPA methodology, and the entire year of 2002 meteorological data. 

2) Daily modeling results for the baseline case were ranked in order to determine the 20% worst 

days (73 days) for visibility at both Class I areas (TRNP and LWA). 

3) The hybrid modeling system was executed for the future (2018) case, using the emissions 

inventory for the default EPA methodology, and the 20% worst days determined for the 

baseline case in Step 2. 

4) Relative response factors (RRFs) were developed from the modeling results for baseline and 

future cases in Steps 1 and 3, respectively. 

5) RRFs were applied to IMPROVE baseline monitoring data for original 20% worst days to 

project future visibility. 

This procedure provided deciview improvement predictions which were very similar to the 

original improvement predictions obtained through modeling the 20% worst IMPROVE days. 

Typical differences were less than five percent of the original predicted values at both Class I 

areas. Therefore, the NDDoH did not pursue this approach for any of the visibility modeling 

documented in this report (i.e., all modeling was based on the 20% worst/best IMPROVE days). 
168 

8.6.3.5 Weight of Evidence Summary and Conclusions 

Results of the weight of evidence modeling analyses are summarized in Table 8.20, and in the 

illustrations of Figures 8.26 and 8.27. For comparison, the table and figures include results from 

all weight of evidence analyses, as well as previous WRAP and NDDoH results for the complete 

emissions inventory and default EPA methodology from Table 8.11. Scenarios are labeled as 

previously noted. For each scenario, the table provides percentage progress with respect to the 

2018 target for 20% worst days at both North Dakota Class I areas. Figure 8.26 illustrates 

progress with respect to the URP glide path at TRNP for all scenarios, and Figure 8.27 illustrates 

progress with respect to the URP glide path at LWA for all scenarios. 

Conclusions based on weight of evidence modeling analyses follow. 

1) Compliance with 20% worst day URP 2018 targets at North Dakota Class I areas cannot be 

achieved through additional emissions reductions from North Dakota sources, alone. It will 

require significant additional visibility affecting emissions reductions from other western 

states, Canada, and from sources located outside of the WRAP CMAQ modeling domain. 

2) A visibility progress analysis methodology which discounts the impact of International 

(Canadian) visibility affecting source emissions on 20% worst days is plausible, and was 

developed and implemented by the NDDoH. Using similar methodology, the NDDoH was 

able to also develop and implement a procedure to discount the impact of all sources located 

outside of North Dakota on 20% worst days. 

3) After discounting the impact of Canadian sources, significantly greater progress (50 percent 

greater) was demonstrated, relative to URP 2018 targets for North Dakota Class I areas, than 

modeling with the entire emissions inventory. But 20% worst day targets were still not 

achieved. 

4) After discounting the impact of all sources located outside of North Dakota, even greater 

progress was demonstrated, relative to URP 2018 targets for North Dakota Class I areas, than 

modeling with Canadian sources discounted. However, 20% worst day targets were still not 

achieved. 

5) After zeroing out all future SO2 and NOX emissions in North Dakota under default EPA 

methodology (emulating a 100 percent, unrealistic control of all sources), compliance with 

20% worst day targets was still not achieved at North Dakota Class I areas. 

6) Basing 20% worst days on baseline model results rather than IMPROVE monitoring data 

made no meaningful difference in future visibility projections. 
169 

Table 8.20 

NDDoH Visibility Modeling Results 20% Worst Days 

Weight of Evidence Analysis Summary 

Projected

Scenario Description Class I Area Percent of

2018 Target

 WRAP CMAQ TRNP 24.0

1 Default EPA Methodology

LWA 16.7

 NDDoH Hybrid TRNP 38.1

2 Default EPA Methodology

LWA 26.7

 NDDoH Hybrid TRNP 50.0

3 Canada Sources Discounted

LWA 40.2

 NDDoH Hybrid TRNP 83.9

4 All Sources Other Than ND Discounted

LWA 59.6

 NDDoH Hybrid TRNP 83.8

5 Base Emissions Inv = Default

 Future Emissions Inv = All ND LWA 72.6

SO2

 and NOX Emissions set to zero
170 

Figure 8.26 

TRNP Uniform Rate of Progress 

EPA Default Methodology and NDDoH Weight of Evidence 

2004 2024 2044 

Year

68

1012141618

Deciview

Predicted Progress to 2018

WRAP - Scenario 1NDDoH - Scenarios 2,3,4Zero Future ND - Scenari

All Sources Glide Path Canadian Sources Discounted Glide Path ND Sources Glide Path

1

2

5

3

4

2018
171 

Figure 8.27 

LWA Uniform Rate of Progress 

EPA Default Methodology and NDDoH Weight of Evidence

2004 2024 2044 

Year

68

101214161820

Deciview

Predicted Progress to 2018

WRAP - Scenario 1NDDH - Scenarios 2,3,4Zero Future ND - Scenari

All Sources Glide Path Canadian Sources Discounted Glide Path ND Sources Glide Path

1

2

5

3

4

2018
172 

9. Reasonable Progress Goals 

9.1 Introduction 

The Regional Haze Rule states that for each mandatory Class I Federal area located within the 

State and in each mandatory Class I Federal area located outside the State which may be affected 

by emissions from within the State, the State must establish reasonable progress goals for each 

area. For out-of-state Class I areas that are affected by in-state emissions, the State must consult 

with the affected state regarding the reasonable progress goals for those Class I areas. The 

reasonable progress goals (expressed in deciviews) must provide for reasonable progress towards 

achieving natural visibility conditions including improvement in visibility for the most impaired 

days (20% worst days) and ensuring no degradation in visibility for the least impaired days (20% 

cleanest days) over the planning period. 

The EPA has published guidance1

 for setting reasonable progress goals. The basic steps include: 

1. Establish Baseline and Natural Visibility Conditions 

2. Determine the Glidepath, or Uniform Rate of Progress 

3. Identify and Analyze the Measures Aimed at Achieving the Uniform Rate of Progress 

a. Identify the key pollutants and sources and/or source categories that are 

contributing to visibility impairment at each Class I area. The sources of 

impairment for the most impaired and least impaired days may differ. 

b. Identify the control measures and associated emission reductions that are expected 

to result from compliance with existing rules and other available measurements 

for the sources and source categories that contribute significantly to visibility 

impairment. 

c. Determine what additional control measures would be reasonable based on the 

statutory factors and other relevant factors for the sources and/or source 

categories you have identified. 

d. Estimate through the use of air quality models the improvement in visibility that 

would result from implementation of the control measures you have found to be 

reasonable and compare this to the uniform rate of progress. 

4. Establish the Reasonable Progress Goal 

 

1

 U.S. EPA 2007; Guidance for Setting Reasonable Progress Goals under the 

Regional Haze Rule: U.S. Environmental Protection Agency, Office of Air Quality Planning and 

Standards, Research Triangle Park, NC, June 1, 2007.
173 

9.2 Establish Baseline and Natural Visibility Conditions 

The baseline visibility conditions are established in Section 5.3 while the natural visibility 

conditions are addressed in Section 5.4. The following table summarizes the results for North 

Dakota’s Class I Federal areas. 

 

Table 9.1 

Baseline and Natural Visibility Conditions 

Area

Baseline (dv) Natural Conditions (dv)

20% Best 20% Worst 20% Best 20% Worst

TRNP 7.8 17.8 3.0 7.8 

LWA 8.2 19.6 2.9 8.0 

9.3 Determine the Glide Path or Uniform Rate of Progress 

The uniform rate of progress necessary to achieve natural conditions is addressed in Section 5.4. 

The results of that analysis are as follows: 

Table 9.2 

 Visibility Improvement Required 

Area 

Total Improvement 

Required (dv) 

20% Worst Days 

2018 

Target Improvement (dv) 

20% Worst Days 

TRNP 10.0 2.3 

LWA 11.6 2.7 

9.4 Identify and Analyze the Measures Aimed at Achieving the 

Uniform Rate of Progress 

A. Identify key pollutants and sources contributing to visibility impairment in each Class I 

area. 

The key pollutants contributing to visibility degradation in North Dakota’s Class I areas 

are sulfur dioxide and nitrogen oxides which form sulfates and nitrates (see analysis in 

Section 8.7.2.2). For sulfates, the contributing sources are primarily point sources in 

Canada, sources outside WRAP’s modeling domain and point sources in North Dakota. 
For nitrates, point/area/mobile sources in Canada, North Dakota, Montana and sources 

outside of WRAP

Section 6.3 and Section 

19% of the nitrate at TRNP during the 20% worst days of the baseline

02c)

nitrate for the same period.

Organic carbon (primary organic aerosols) is the next largest contributor to extinction in 

the Class I areas of North Dakota. Organic carbon contributes 17.5% of the total 

extinction at TRNP and 14

seen in Figures 9.1 and 9.2, m

from the “natural fire” source category or from the “fugitive dust” categor

cannot be controlled

Section

decrease 54% by 2018.

For nitrates, point/area/mobile sources in Canada, North Dakota, Montana and sources 

outside of WRAP

Section 6.3 and Section 

19% of the nitrate at TRNP during the 20% worst days of the baseline

02c). At LWA, North Dakota sources contributed 18% of

nitrate for the same period.

Organic carbon (primary organic aerosols) is the next largest contributor to extinction in 

the Class I areas of North Dakota. Organic carbon contributes 17.5% of the total 

extinction at TRNP and 14

seen in Figures 9.1 and 9.2, m

from the “natural fire” source category or from the “fugitive dust” categor

cannot be controlled

Sections 9.5.2

decrease 54% by 2018.

For nitrates, point/area/mobile sources in Canada, North Dakota, Montana and sources 

outside of WRAP’s modeling domain area are the primar

Section 6.3 and Section 

19% of the nitrate at TRNP during the 20% worst days of the baseline

. At LWA, North Dakota sources contributed 18% of

nitrate for the same period.

Organic carbon (primary organic aerosols) is the next largest contributor to extinction in 

the Class I areas of North Dakota. Organic carbon contributes 17.5% of the total 

extinction at TRNP and 14

seen in Figures 9.1 and 9.2, m

from the “natural fire” source category or from the “fugitive dust” categor

cannot be controlled and will vary year to year in each state

9.5.2 and 10.6.2

decrease 54% by 2018.

For nitrates, point/area/mobile sources in Canada, North Dakota, Montana and sources 

s modeling domain area are the primar

Section 6.3 and Section 8). North Dakota sources contributed 21% of the sulfate and 

19% of the nitrate at TRNP during the 20% worst days of the baseline

. At LWA, North Dakota sources contributed 18% of

nitrate for the same period.

Organic carbon (primary organic aerosols) is the next largest contributor to extinction in 

the Class I areas of North Dakota. Organic carbon contributes 17.5% of the total 

extinction at TRNP and 14.9% at LWA

seen in Figures 9.1 and 9.2, much of the organic carbon 

from the “natural fire” source category or from the “fugitive dust” categor

and will vary year to year in each state

and 10.6.2. Off-road mobile sources o

174 

For nitrates, point/area/mobile sources in Canada, North Dakota, Montana and sources 

s modeling domain area are the primar

North Dakota sources contributed 21% of the sulfate and 

19% of the nitrate at TRNP during the 20% worst days of the baseline

. At LWA, North Dakota sources contributed 18% of

Organic carbon (primary organic aerosols) is the next largest contributor to extinction in 

the Class I areas of North Dakota. Organic carbon contributes 17.5% of the total 

.9% at LWA during the 

uch of the organic carbon 

from the “natural fire” source category or from the “fugitive dust” categor

and will vary year to year in each state

road mobile sources o

Figure 9.1

For nitrates, point/area/mobile sources in Canada, North Dakota, Montana and sources 

s modeling domain area are the primary contributors (see analysis in 

North Dakota sources contributed 21% of the sulfate and 

19% of the nitrate at TRNP during the 20% worst days of the baseline

. At LWA, North Dakota sources contributed 18% of

Organic carbon (primary organic aerosols) is the next largest contributor to extinction in 

the Class I areas of North Dakota. Organic carbon contributes 17.5% of the total 

during the baseline 

uch of the organic carbon emissions in North Dakota are 

from the “natural fire” source category or from the “fugitive dust” categor

and will vary year to year in each state. Fugitive

road mobile sources of organic carbon are expected to 

Figure 9.1

For nitrates, point/area/mobile sources in Canada, North Dakota, Montana and sources 

y contributors (see analysis in 

North Dakota sources contributed 21% of the sulfate and 

19% of the nitrate at TRNP during the 20% worst days of the baseline (WRAP Case Plan 

. At LWA, North Dakota sources contributed 18% of the sulfate and 13% of the 

Organic carbon (primary organic aerosols) is the next largest contributor to extinction in 

the Class I areas of North Dakota. Organic carbon contributes 17.5% of the total 

baseline 20% worst days

emissions in North Dakota are 

from the “natural fire” source category or from the “fugitive dust” categor

. Fugitive dust is addressed in 

organic carbon are expected to 

For nitrates, point/area/mobile sources in Canada, North Dakota, Montana and sources 

y contributors (see analysis in 

North Dakota sources contributed 21% of the sulfate and 

(WRAP Case Plan 

the sulfate and 13% of the 

Organic carbon (primary organic aerosols) is the next largest contributor to extinction in 

the Class I areas of North Dakota. Organic carbon contributes 17.5% of the total 

20% worst days. As can be 

emissions in North Dakota are 

from the “natural fire” source category or from the “fugitive dust” category. Natural fire 

dust is addressed in 

organic carbon are expected to 

For nitrates, point/area/mobile sources in Canada, North Dakota, Montana and sources 

y contributors (see analysis in 

North Dakota sources contributed 21% of the sulfate and 

(WRAP Case Plan 

the sulfate and 13% of the 

Organic carbon (primary organic aerosols) is the next largest contributor to extinction in 

the Class I areas of North Dakota. Organic carbon contributes 17.5% of the total 

As can be 

emissions in North Dakota are 

. Natural fire 

dust is addressed in 

organic carbon are expected to 
With regard to 

concentration in the Class I areas

Area

TRNP

LWA

North Dakota sources only contribute 21% of the total sulfate concentration in TRNP and 

19% of the total nitrate concentration during the 20% worst days. At LWA, North 

With regard to 

concentration in the Class I areas

Area Source

TRNP Point

Anthropogenic Fire

Mobile

Natural Fire & Biogenic

Area

LWA Point

Anthropogenic Fire

Mobile

Natural Fire & Biogenic

Area

North Dakota sources only contribute 21% of the total sulfate concentration in TRNP and 

19% of the total nitrate concentration during the 20% worst days. At LWA, North 

With regard to the contribution of North Dakota sources to the 

concentration in the Class I areas

Source

Point

Anthropogenic Fire

Mobile

Natural Fire & Biogenic

Point

Anthropogenic Fire

Mobile

Natural Fire & Biogenic

North Dakota sources only contribute 21% of the total sulfate concentration in TRNP and 

19% of the total nitrate concentration during the 20% worst days. At LWA, North 

Figure 9.2

the contribution of North Dakota sources to the 

concentration in the Class I areas, the sources in North Dakota are:

North Dakota Sources

Sulfate and Nitrates

Contribution

Anthropogenic Fire

Natural Fire & Biogenic

Anthropogenic Fire

Natural Fire & Biogenic

North Dakota sources only contribute 21% of the total sulfate concentration in TRNP and 

19% of the total nitrate concentration during the 20% worst days. At LWA, North 

175 

Figure 9.2

the contribution of North Dakota sources to the 

, the sources in North Dakota are:

Table 9.3

North Dakota Sources

of 

Sulfate and Nitrates

2000-2004

In-State 

Sulfate 

Contribution

(μg/m3) 

0.3148 

0.0002 

0.0151 

0.0002 

0.0071 

0.3797 

< 0.0001 

0.0216 

0.0004 

0.0089 

North Dakota sources only contribute 21% of the total sulfate concentration in TRNP and 

19% of the total nitrate concentration during the 20% worst days. At LWA, North 

the contribution of North Dakota sources to the 

, the sources in North Dakota are:

Table 9.3

North Dakota Sources

Sulfate and Nitrates

2004

In-State

Nitrate

Contribution

(μg/m3)

0.1587

0.0003

0.1038

0.0389

0.0233

0.1760

< 0.0001

0.1197

0.0362

0.0334

North Dakota sources only contribute 21% of the total sulfate concentration in TRNP and 

19% of the total nitrate concentration during the 20% worst days. At LWA, North 

the contribution of North Dakota sources to the sulfate

, the sources in North Dakota are:

State

Contribution

)

Percent of Total

In-State Contribution

Sulfate

98 

< 1

4 

< 1

2 

0.0001

92 

< 1

5 

< 1

2 

North Dakota sources only contribute 21% of the total sulfate concentration in TRNP and 

19% of the total nitrate concentration during the 20% worst days. At LWA, North 

sulfates and nitrate

Percent of Total

State Contribution

Sulfate Nitrate

49

< 1

32

12

7

48

< 1

33

10

9

North Dakota sources only contribute 21% of the total sulfate concentration in TRNP and 

19% of the total nitrate concentration during the 20% worst days. At LWA, North 

and nitrates

Percent of Total

State Contribution

Nitrate

1

1

North Dakota sources only contribute 21% of the total sulfate concentration in TRNP and 

19% of the total nitrate concentration during the 20% worst days. At LWA, North 
176 

Dakota sources contribute 18% of the total sulfate and 13% of the total nitrate (see Table 

2.1). Although mobile sources are a significant contributor to North Dakota’s emissions 

that form nitrates, mobile sources in North Dakota only contribute 6% of the total nitrate 

concentration in TRNP and 4% in LWA during the 20% worst days (WRAP Case Plan 

02c). Nitrogen oxides emissions from mobile sources are expected to decline by 51% by 

2018 (see Table 6.1 and 6.3). Based on the above results, efforts to reduce sulfates and 

nitrates are primarily directed towards point sources of sulfur dioxide and nitrogen oxides 

emissions. 

B. Identify the Control Measures and Associated Emission Reductions from Existing Rules 

See Section 10. The WRAP has estimated that the “on-the-books” controls will reduce 

emissions of nitrogen oxides by approximately 28,000 tons per year, sulfur dioxide 1,700 

tons per year, elemental carbon 2,700 tons per year, and fine particulate matter by 900 

tons per year. Coarse particulate matter is expected to increase by 18,000 tons primarily 

due to fugitive dust. These “on the books” controls include: 

• Tier 1 light-duty vehicle standards, beginning MY 1996; 

• National Low Emission Vehicle (NLEV) standards, beginning MY 2001; 

• Tier 2 light-duty vehicle standards beginning MY 2005, with low sulfur gasoline 

beginning summer 2004; 

• Heavy-duty vehicle standards beginning MY 2004; 

• Heavy-duty vehicle standards beginning MY 2007, with low sulfur diesel 

beginning summer 2006; 

• Emission standards for new nonroad spark-ignition engines below 25 hp; 

• Phase 2 emission standards for new spark-ignition hand-held engines below 25 

hp; 

• Phase 2 emission standards for new spark-ignition nonhand-held engines below 

25 hp; 

• Emission standards for new gasoline spark-ignition marine engines; 

• Tier 1 emission standards for new nonroad compression-ignition engines above 

50 hp; 

• Tier 1 and Tier 2 emission standards for new nonroad compression-ignition 

engines below 50 hp including recreational marine engines; 

• Tier 2 and Tier 3 standards for new nonroad compression-ignition engines of 50 

hp and greater not including recreational marine engines greater than 50 hp; and 

• Tier 4 emissions standards for new nonroad compression-ignition engines above 

50 hp, and reduced nonroad diesel fuel sulfur levels. 

Modeling by the WRAP indicates these “on-the-books” rules will improve visibility by 

0.1 deciviews in the 20% worst day at TRNP and 0.2 deciviews at LWA. 

C. Determine What Additional Control Measures Would be Reasonable Based on the 

Statutory Factors and Other Relevant Factors 

See Section 9.5 and 9.6. 
177 

D. Estimate Through the Use of Air Quality Models the Improvement in Visibility that 

Would Result From the Implementation of the Control Measures Found to be Reasonable 

See Section 9.5. 

E. Establish the Reasonable Progress Goals 

See Section 9.7. 

9.5 Additional Controls

9.5.1 Point Sources Contributing to Visibility Impairment in the North 

Dakota Class I Areas 

In determining reasonable progress goals for any Class I Federal area, 40 CFR 

51.308(d)(1)(i)(A) requires a state to consider the costs of compliance, the time necessary for 

compliance, the energy and non-air quality environmental impacts of compliance, and the 

remaining useful life of any potentially affected sources, and include a demonstration showing 

how these factors were taken into consideration in selecting the goal. 

In determining the cost of compliance for individual sources or source categories potentially 

subject to emission limitations, the following steps are suggested: 

A. Identify the emission units to be controlled. 

B. Identify the design parameters for emission controls, and 

C. Develop cost estimates based upon those design parameters. 

The Guidance for Setting Progress Goals under the Regional Haze Program states “it is not 

necessary for you to reassess the reasonable progress factors for sources subject to BART for 

which you have already completed a BART analysis.” 

Cost of Compliance 

Step 1: Identify Emission Units to be Controlled

The Department has identified sulfur dioxide and nitrogen oxides as the primary pollutants that 

are emitted by stationary point sources that contribute most of the visibility impairment. 

Particulate emissions from stationary sources have very little impact on visibility in North 

Dakota (see Figures 6.5 and 6.6) and represent only 1% of the total PM emissions in 2002 (see 

Table 6.1). Therefore, PM emissions from point sources were not evaluated under this section. 
178 

Under BART, it was determined that no additional controls were required for the largest sources 

of PM, the electric utility steam generating units. Primary sulfuric acid mist emissions are also a 

very small contributor to visibility impairment. The sources that were subject to BART, the 

largest emitters of sulfuric acid mist, were evaluated for emissions of this pollutant. Because of 

the small impact of sulfuric acid mist on visibility, sulfuric acid mist was not included in the 

reasonable progress analysis. 

To identify point sources in North Dakota that potentially affect visibility in Class I Federal 

areas, the list of sources subject to Title V permitting requirements was established as the starting 

point. This represents more than 99% of the sulfur dioxide emissions from all point sources in 

North Dakota that have an operating permit (Title 5 or Minor Source Operating Permit) and 

greater than 98% of the nitrogen oxides emissions based on 2007 data. The sources subject to 

BART were also eliminated from the list as suggested by EPA guidance. The Department has 

included all controls on BART sources that have a reasonable cost. Any controls rejected under 

BART would also be rejected under the four factors for determining reasonable progress. 

Although sources were excluded from this analysis, all sources, including sources subject to 

BART, will be reviewed during future planning periods. 

To further evaluate the list of sources, the actual emissions from the source were compared to the 

distance the source is located from the nearest Class I Federal area. The Department has 

determined from previous BART modeling that particulate matter emissions from point sources 

have a very small contribution to visibility impairment in the Class I areas. Therefore, only 

emissions of nitrogen oxides and sulfur dioxide were evaluated in this comparison. The 

Department initially used the average of the 2000-2004 emission rate for this analysis. The 

emission rate (Q) in tons per year was divided by the distance (D), in kilometers, to the nearest 

Class I area. A value of Q/D greater than 10 was chosen as a point for further evaluation of 

those sources. A Q/D of greater than 10 was chosen based on the FLM’s proposed FLAG 

guidance amendments initial screening criteria for sources that may affect air quality related 

values. In addition, EPA in the preamble to the BART Guideline states, “Our analyses of 

visibility impacts from model plants provide a useful example of the type of analyses that might 

be used to exempt categories of sources from BART. Based on our model plant analysis, EPA 

believes that a State could reasonably choose to exempt sources that emit less than 500 tons per 

year of NOx or SO2 (or combined NOx and SO2), as long as they are located more than 50 

kilometers from any Class I area; and sources that emit less than 1000 tons per year of NOx or 

SO2 (or combined NOx and SO2) that are located more than 100 kilometers from any Class I 

area.” EPA’s criteria is equivalent to a Q/D of 10. For all sources, except EGUs, the total SO2

and NOx emissions from the facility were used and no distinction was made for individual units. 

EGU’s were separated by units because they can act as standalone facilities while other process 

units cannot. 

 
179 

Table 9.4 

 North Dakota Title V Sources Q/D Analysis 

Permittee Plant

SO2 + NOx

2000-2004 

Average 

(tons)

Nearest 

Class I Area

Distance 

to Nearest 

Class I Area 

(km)

Nearest 

Q/D 

(tons/km)

ADM Corn Processing Walhalla Ethanol Plant 287 Lostwood 324 0.9 

ADM Processing Velva Facility 45 Lostwood 125 0.4 

Alliance Pipeline Fairmount Comp. Station 58 Voyageurs 327 0.2 

Alliance Pipeline Towner Comp. Station 57 Lostwood 120 0.5 

Alliance Pipeline Wimbledon Comp. Station 60 Lostwood 335 0.2 

American Crystal Sugar Co. Drayton Sugarbeet Plant 1,109 Voyageurs 294 3.8 

American Crystal Sugar Co. Hillsboro Sugarbeet Plant 1,085 Voyageurs 315 3.4 

Basin Electric AVS Unit 1 13,864 TRNP/NU 107 129.6 

Basin Electric AVS Unit 2 12,796 TRNP/NU 107 119.6 

Bear Paw Energy Alexander Comp. Station 139 TRNP/NU 36 3.9 

Bear Paw Energy Fort Buford Comp. Station 42 TRNP/NU 44 1.0 

Bear Paw Energy Grasslands Gas Plant 748 TRNP/NU 38 19.7 

Bear Paw Energy Lignite Gas Plant 463 Lostwood 15 30.9 

Bear Paw Energy Tree Top Comp. Station 54 TRNP/SU 17 3.2 

Cargill Corn Milling Wahpeton Facility 109 Voyageurs 320 0.3 

Cargill, Inc. West Fargo Plant 56 Voyageurs 311 0.2

Cavalier AFS CAFS Power Plant 234 Lostwood 280 0.8 

City of Fargo Landfill 9 Voyageurs 309 <0.1 

City of Minot Landfill 1 Lostwood 80 <0.1 

CNH America, LLC Fargo Plant 1 Voyageurs 310 <0.1 

Continental Resources Medicine Pole Hills 58 TRNP/SU 94 0.6 

Dakota Gasification Co. Great Plains Synfuels 10,802 TRNP/NU 107 101.0 

DMI Industries Fargo Plant 2 Voyageurs 321 <0.1 

Grand Forks AFB Heating Plant 9 Voyageurs 342 < 0.1

Hebron Brick Company Hebron Brick Plant 30 TRNP/SU 97 0.3 

Health Care Fargo Incinerator 4 Voyageurs 313 <0.1 

Hess Corporation Hawkeye Comp. Station 116 Lostwood 53 2.2 

Hess Corporation Tioga Gas Plant 3,655 Lostwood 35 104.4 

Hillsboro MEU Hillsboro 1 Voyageurs 318 <0.1 

Idahoan Foods Grand Forks Plant 104 Voyageurs 316 0.3 

J.R. Simplot Grand Forks Plant 53 Voyageurs 317 0.2
180 

Permittee Plant

SO2 + NOx

2000-2004 

Average 

(tons)

Nearest 

Class I Area

Distance 

to Nearest 

Class I Area 

(km)

Nearest 

Q/D 

(tons/km)

Jahner Sanitation Landfill 1 Voyageurs 340 <0.1 

Kaneb Pipeline Co. Jamestown Plant 1 TRNP/SU 351 <0.1 

LM Glasfiber Grand Forks Plant 1 Voyageurs 325 <0.1

Minn-Dak Farmers Coop Wahpeton Facility 601 Voyageurs 319 1.9 

Minot AFB Heating Plant 24 Lostwood 79 0.3 

MDU Company Heskett Plant Unit 1 1,269 TRNP/SU 182 7.0 

MDU Company Heskett Plant Unit 2 3,411 TRNP/SU 182 18.7 

Mor Tech Fab Williston Plant 1 TRNP/NU 60 <0.1 

Nordic Fiberglass Devils Lake Plant 1 TRNP/NU 335 <0.1 

NDSU Heating Plant 500 Voyageurs 310 1.6 

Northern Border Pipeline Comp. Station No. 4 188 TRNP/NU 18 10.4 

Northern Border Pipeline Comp. Station No. 5 104 TRNP/NU 56 1.9 

Northern Border Pipeline Comp. Station No. 6 101 TRNP/SU 116 0.9 

Northern Border Pipeline Comp. Station No. 7 104 TRNP/SU 190 0.5 

Northern Border Pipeline Comp. Station No. 8 108 TRNP/SU 282 0.4 

Northern Sun ADM Enderlin Facility 105 Voyageurs 335 0.3 

Otter Tail Power Company Coyote Station 27,804 TRNP/NU 112 248.3 

Petro-Hunt Little Knife Gas Plant 422 TRNP/NU 39 10.8 

Red Trail Energy Richardton Ethanol Plant 329 TRNP/SU 74 4.4 

Tesoro Mandan Refinery 5,757 TRNP/SU 182 31.6 

UND Heating Plant 868 Voyageurs 318 2.7 

Whiting Oil & Gas Wabek Station 73 Lostwood 71 1.0 

WBI Pipeline Company Dickinson Comp. Station 137 TRNP/SU 39 3.5 

WBI Pipeline Company Glen Ullin Comp. Station 67 TRNP/SU 116 0.6 

Wil Rich, Inc. Wahpeton Plant 1 Voyageurs 317 <0.1 

The Northern Border Pipeline Company Compressor Station No. 4 is powered by a natural gas 

turbine. In 2005, Northern Border replaced this turbine with a lower emitting turbine. From 

2006-2008, the average nitrogen oxides plus sulfur dioxide emissions were 118 tons per year for 

a Q/D of 6.6. Because of the installation of the lower emitting turbine, this facility was 

eliminated from consideration of additional controls during this planning period. 

The Tesoro Refining and Marketing Company’s Mandan Refinery is subject to a Consent Decree 

which requires substantial emissions reductions. Since the baseline period, Tesoro has installed 

a wet scrubber and wet ESP to control sulfur dioxide emissions from the catalytic cracking unit, 
181 

installed new lower emitting furnaces at the alkylation unit and are installing low NOx burners in 

the boilers. From 2006-2008, the total sulfur dioxide and nitrogen oxides emissions from the 

facility averaged 1,438 tons per year for a Q/D of 7.9. This ratio is expected to decline 

significantly when the modifications to the boilers are brought on-line. Because of these 

changes, this facility was not considered for additional controls during this planning period. 

Since the baseline period, Bear Paw Energy has been injecting the acid gas into deep wells at 

their Grasslands and Lignite Gas Plants. This injection eliminates all sulfur dioxide emissions 

except for those emissions due to a malfunction of the injection equipment. When a malfunction 

occurs, the acid gas goes to a flare which will emit sulfur dioxide. In 2007, total emissions of 

sulfur dioxide and nitrogen oxides (including malfunctions) from the Grasslands Gas Plant were 

274 tons for a Q/D of 9.8. Without malfunction emissions, the total was 52 tons for a Q/D of 

1.4. At the Lignite Gas Plant, the 2007 total sulfur dioxide and nitrogen oxides emissions 

(including malfunctions) were 121 tons for a Q/D of 8.1. Without malfunction emissions, the 

total was 48 tons for a Q/D of 3.2. These malfunctions are generally unplanned, short durationepisodes (a few hours) with very high SO2 emission rates that vary from year-to-year. 

Controlling emissions during these malfunctions is not feasible and the acid gas is flared to 

prevent the release of high concentrations of hydrogen sulfide. These two sources were 

eliminated based on their change to acid gas injection which greatly reduces sulfur dioxide 

emissions. The requirement to inject their acid gas is included in the Title V Permit to Operate 

for each facility. 

Petro Hunt’s Little Knife Gas Plant emissions include those emissions associated with 

malfunctions. If the malfunction emissions are eliminated, the average sulfur dioxide and 

nitrogen oxides emission rate for 2000-2004 is 337.7 tons for a Q/D of 8.7. The Little Knife Gas 

Plant has seen reduced operations recently due to a decline in gas volume. New oil wells that are 

being drilled are generally producing from the Bakken formation which contains sweet natural 

gas. In 2008, SO2 plus NOx emissions (including malfunctions) totaled 295 tons for a Q/D of 

7.6. Because of the small amount of emissions and the expected decline in the future, the Little 

Knife Gas Plant was eliminated from consideration for additional control during this planning 

period. 

All of the facilities that were eliminated from consideration for additional air pollution controls 

will be considered and reviewed again during future planning periods. 

After review of the sources in Table 9.4, the following sources in Table 9.5 were considered for 

additional controls during this planning period: 

 
182 

Table 9.5 

Sources Evaluated for Additional Control 

Source Owner Unit Type Capacity

Antelope Valley Station Basin Electric Power Coop. 1 EGU 435 MWe 

Antelope Valley Station Basin Electric Power Coop. 2 EGU 435 MWe 

Coyote Station OtterTail Power Co. Main Boiler EGU 450 MWe 

Great Plains Synfuels Plant Dakota Gasification Co. Boilers A, B & S Industrial Boilers 763 x 106 

Btu/hr each 

Tioga Gas Plant Hess Corp. 3 Sulfur Recovery Unit 225 LTPD 

Tioga Gas Plant Hess Corp. C1-A to F Compressor Engines 1920-2350 

BHp each 

Step 2: Identify the Design Parameters for Emission Controls

All of the source units identified for possible additional air pollutant control are equipped with 

varying degrees of air pollution control equipment, as shown in Table 9.6. 

Table 9.6 

Remaining Sources Existing Conditions 

Source Pollutant 

Control 

Equipment 

Currenta

Emission Rate 

Currenta

Control 

Efficiency 

(%) 

AVS 1 SO2 

NOx 

Spray Dryer 

OFA 

0.36 lb/106 Btu 

0.37 lb/106 Btu 

77 

-- 

AVS 2 SO2 

NOx 

Spray Dryer 

OFA 

0.38 lb/106

 Btu 

0.34 lb/106

 Btu 

76 

-- 

Coyote SO2 

NOx 

Spray Dryer 

None 

0.71 lb/106 Btu 

0.68 lb/106 Btu 

66 

-- 

Tioga Gas Plant 

SRU 

Engines 

SO2 

NOx 

3 Stage Claus 

+4 bed Cold Bed 

Absorber 

None 

1097 tpy 

1353 

98.8 

-- 

GPSP - Boilers SO2 

NOx 

Wet Scrubber 

None 

2169 tpy 

0.5 lb/106 Btub

96-97 

-- 

 a Based on 2005-2007 data 

 b Based on 2007 data 
183 

Work is currently underway to increase the efficiency of the spray dryers at AVS I and II. This 

work is being done because of an expected increase in the sulfur content of the coal used at the 

facilities. The increase in efficiency is expected to approach 90% which the Department 

considers the limit of spray dryer efficiency. Even though the efficiency will be increased, no 

reduction in emissions is expected because of the higher sulfur coal. Because upgrades of the 

spray dryers are already in progress, this option was not considered at AVS I or II during this 

planning period. At the Coyote Station, upgrades to the spray dryer would require a detailed 

engineering analysis to determine if improvements are possible. For this planning period, 

replacing the spray dryer is evaluated. Any upgrades to the spray dryer (if possible) will produce 

less emissions reductions and less visibility improvement when compared to a new wet scrubber. 

This source will also be reevaluated during future planning periods to determine if additional 

controls are reasonable. 

The boilers at the Great Plains Synfuels Plant (GPSP) are equipped with an ammonia reagent wet 

scrubbing system followed by a wet electrostatic precipitator. This system is achieving 96-97% 

removal of sulfur dioxide from the flue gas. This removal efficiency is comparable to BACT or 

BART for industrial boilers of this size. Therefore, sulfur dioxide controls for these boilers were 

not evaluated further during this planning period. 

The following control options were reviewed for possible implementation at the remaining 

sources: 

Table 9.7 

Control Options Evaluated 

Source Pollutant 

Control 

Considered 

Estimated 

Control Efficiency 

(%) 

AVS 1 and 2 SO2 New Wet Scrubber 95 

NOx LNB 

SNCR 

SCR w/Reheat 

30-75 

30-75 

40-90c

Coyote SO2 New Wet Scrubber 95 

NOx ASOFA 

SNCR 

ASOFA + SNCR 

SCR w/Reheat 

40 

30 

50-60 

40-90c 

Tioga Gas Plant 

SRU 

1920 BHp 

Engines 

SO2 Tail Gas Cleanup 99.8-99.98a

NOx SCR 

Engine Remanufacture 

Air-Fuel Ratio Controller 

Ignition Timing Retard 

80-90c

80-90 

10-40 

15-30 

2350 BHp Engines NOx SCR 33-67 

GPSP – Boilers NOx SNCRb

SCRb

30-40 

40-90c 
184 

aOverall efficiency of the sulfur recovery unit and tail gas cleanup unit. BACT determinations 

range from 99.8% for existing units to 99.98% for new units. 

b

The Department has concerns whether SCR and SNCR are technically feasible for the GPSP 

(see DGC’s comments in Appendix I). 

c

The Department considers 90% efficiency reasonable for new installations and 80% reasonable 

for retrofits. 

Step 3: Develop Cost Estimates Based on the Design Parameters

The available control options were evaluated by WRAP’s contractor EC/R Incorporated. The 

report on this evaluation is found in Appendix I.1. The cost for the wet scrubber at the Coyote 

Station was adjusted to represent the gross capacity of the facility (450 MWe vs 427 MWe) 

which is larger than EC/R evaluated. Also, the removal efficiency for a new wet scrubber was 

adjusted from 90% to 95%. The costs associated with the various control technologies are 

shown in Table 9.8. 

The cost effectiveness ($/ton) for new scrubbers at AVS I & II and Coyote Station is higher than 

at the BART sources that are not equipped with scrubbers. Because AVS and Coyote Station are 

already equipped with spray dryers, the cost effectiveness is higher because less sulfur dioxide 

will be removed than at the unit without a scrubber. The following control options were found to 

have an excessive cost effectiveness: 

AVS 1 & 2 – Wet scrubber; SCR w/reheat; and LNB + SCR w/reheat 

Coyote – SCR w/reheat and ASOFA + SCR w/reheat 

Tioga Gas Plant – Tail Gas Cleanup 

DGC – SNCR and SCR 

The SRU at the Tioga Gas Plant is currently operating at less than 45% of its rated capacity. It is 

expected that the amount of sulfur recovered and emissions from the tail gas incinerator will 

continue to decline due to a decline in sour gas production in the area the Tioga Gas Plant serves. 

Most new gas produced comes from the Bakken formation which is sweet gas. 

The Department has concerns whether SCR or SNCR can be successfully applied at the GPSP 

(see DGC comments in Appendix I). Pilot scale testing may be necessary to determine the 

technical feasibility of SCR or SNCR for the boilers which produce a flue gas with a high carbon 

dioxide and sulfur concentration. 

Therefore, these control technologies were not evaluated further. 

For the most efficient control options for which the cost effectiveness (as described in Table 9.8) 

was considered reasonable on a $/ton basis, the 2018 projected emissions were modeled by the 

NDDoH to determine the source-specific improvement in visibility. Cumulative modeling was 

conducted using the procedures (default EPA methodology), hybrid modeling system, and 

baseline and future (2018) emissions inventories as described in Section 8.5. The 
185 

Table 9.8 

Control Options Cost 

Source Unit Pollutant Control Technology 

Total 

Annualized Cost 

($) 

Control 

Efficiency 

(%) 

Em

Re

AVS 1 SO2

NOx

New Wet Scrubber LNB SNCR LNB+SNCR SCR w/reheat1

LNB + SCR w/reheat 

32,170,000 

2,280,000 8,960,000 

11,240,000 

44-63.2 million 

46.3-65.5 million 

95 51 40 65 80 90 

AVS 2 SO2

NOx

New Wet Scrubber LNB SNCR LNB+SNCR SCR w/reheat1

LNB + SCR w/reheat 

32,170,00 2,280,000 8,960,000 

11,240,000 

44-63.2 million 

46.3-65.5 million 

95 51 40 65 80 90 

Coyote 1 SO2

NOx

New Wet Scrubber ASOFA1

SNCR ASOFA & SNCR1

SCR w/reheat1

ASOFA + SCR w/reheat 

33,280,000 

1,284,000 8,520,000 

11,245,000 

45.3-65.1 million 46.6-66.4 million 

95 40 40 55 80 90 

Tioga Gas Plant3 SRU 

1920 Hp Engines 2350 Hp Engines 

SO2

NOx

Tail Gas Clean Up2

Air Fuel Ratio Controller Ignition Timing Retard LEC Retrofit SCR SCR 

5,800,000 

260,000 140,000 560,000 

1,600,000 

500,000 

99.8 

25 22 85 80 50 

DGC Boilers (each) SNCR 

SCR 

1,690,000 5,505,000 

30 80 

Notes: A) The Department does not consider high dust SCR to be technically feasible for North Dakota lignite (see BART a

uncertainties associated with designing an SCR system because of the high sodium and potassium submicron aerosolthe air pollution control equipment, dictates the use of the high end of the SCR cost range. 

B) Replacement of the compressor engines with electric motors is not technically feasible since the compressor cylind

integral part of the engines crankshaft. 

1Based on BART cost estimate for Leland Olds Unit 2 and Minnkota 1 & 2 shared cost estimate. 2Based on an overall efficiency of the SRU and tail gas cleanup unit of 99.8%. 3Reductions are the total for all engines with the specified horsepower rating.
future emissions inventory was modified to reflect the control technology for each candidate 

source (A VS 1 EGU, A VS 2 EGU, Coyote EGU, and Tioga Gas Plant), and modeling was 

conducted using the revised future inventory for one source at a time. The reasonable progress 

goals in 40 CFR 51.308(d)(1) requires improvement in the most impaired days. The most 

impaired days are defined in 40 CFR 51.301 as the average visibility impairment for the twenty 

percent days with the highest amount of visibility impairment. Therefore, modeling addressed 

the 20% worst days for both TRNP and L W A Class I areas. The results for each candidate 

source were compared with the results using the unmodified future emissions inventory (Table 

8.11) to determine the additional visibility improvement due to the tested control technology. 

Modeled visibility improvement, for each candidate sourceltechnology, is provided in Table 9.9. 

The single source controlled emissions (modeled tons per year) and annualized cost effectiveness 

(dollars per deciview) are also reported in the table. Reported visibility improvement (in 

deciviews) reflects the higher value for either TRNP or L W A. Note that visibility improvement 

reported for Coyote represents the total for both S02 and NOx control technologies, and the 

improvement reported for the Tioga Gas Plant represents the total for all 1920 and 2350 

horsepower engines. As shown in the table, predicted visibility improvement is very marginal 

for all candidate sources/technologies, and consequently cost per deciview is very high . .' 

Table 9.9 


Visibility Improvement and Cost Effectiveness 


, Visibility Visibility I I I Improvement Improvement .

I Emissions (%\*",. I Control (dv)* I 

Source Pollutant (TPY) TRNP LWA 

AVSI 

Technolo~ TRNP LWA 

0.01 0.05 

AVS2 

NO. LNB+SNCR 2358 0.005 0.03

0.01 0.Q3 0.05 

Coyote 

NOlL LNB+SNCR 2144 0.005

S02 Wet Scrubber 1,924 0.02 0.04 0.11 0.20 I

ASOFA+SNCR 5,871 


TiogaG.P. 


1920 BHp Engines i NO. 


NO. 

0.26 

. 2350 BHp Engines NO. 

LEC Retrofit 268 0 0.05 0

SCR 33

Cost 


Effectiveness 


($fdv)** 

1,124,000,000 

1,124,000,000 

1,113,000,000 

21,200,000 

*The less efficient technologies evaluated would provide less improvement. 


**Based on the maximum visibility improvement (per source) at any Class I area in North 


Dakota. 


* * *Improvement (%) from baseline conditions. 


Time Necessary for Compliance 

Up to 6.5 years after SIP approval is necessary to achieve compliance (see EC/R report in 

Appendix 1.1). Additional time may be necessary if normal maintenance outages do not coincide 

with the projected schedule. It is anticipated that all required changes could be implemented by 

2018 depending on the date of approval of this SIP. It is not anticipated that any of the 

remaining sources will be retired prior to 2018. 

186 
187 

Energy and Non-Air Impacts 

All of the control technologies for the various sources will consume energy (see EC/R report in 

Appendix I.1). In the case of the Antelope Valley Station and the Coyote Station, this would 

mean less electricity available for sale. The enhancement of the sulfur dioxide scrubbing system 

at the Coyote Station would increase the amount of solid waste generated (ash/CaSO4) which 

must be handled and properly disposed. However, there are no non-air impacts identified that 

would preclude additional reductions of SO2 or NOx from the facilities. 

Remaining Useful Life of the Source 

The following table lists the expected remaining useful life of the remaining sources. 

Table 9.10 

Remaining Useful Life 

Source Unit

Startup 

Date

Estimated 

Remaining 

Useful Life 

(yrs)

AVS Unit 1 

Unit 2 

1983 

1985 

20-40 

20-40 

Coyote Unit 1 1981 20-40 

Tioga Gas Plant Engines 1954 5-40 

The engines at the Tioga Gas Plant are now 55 years old. Engines D and F have recently been 

refurbished. It is expected that the other engines could be refurbished which will extend their 

remaining useful life an indefinite period. Other than the engines at the Tioga Gas Plant, the 

remaining useful life of the affected sources would not preclude additional air pollution controls. 

 
188 

Reasonable Progress Goals - Required Controls for Point Sources 

EPA has stated in their Guidance for Setting Reasonable Progress Goals Under the Regional 

Haze Program (June 1, 2007) “in assessing additional emissions reduction strategies for source 

categories or individual, large scale sources, simple cost effectiveness based on a dollar-per-ton 

calculation may not be as meaningful as a dollar per deciview calculation.” It has been 

determined that requiring additional controls, beyond BART, on existing point sources will not 

substantially improve visibility in the Class I Federal Areas. The maximum combined 

improvement based on the Department’s cumulative modeling for the average of the 20% worst 

days is 0.11 deciviews at LWA and 0.03 deciviews at TRNP for the most efficient control 

options for each source that is cost effective. This amounts to a 0.17% improvement at TRNP 

over the baseline condition for the most impaired days and 0.56% improvement at LWA. Other 

less efficient control technology options would provide substantially less visibility improvement 

in the Class I areas. The total capital cost to achieve this improvement is approximately 243 

million dollars with an annualized cost of approximately 68 million dollars. Based on the data in 

Tables 9.8 and 9.9, the cost effectiveness is over 618 million dollars per deciview of 

improvement at LWA and 2.3 billion dollars per deciview at TRNP. For all sources evaluated 

individually and cumulatively, the cost ($/dv) is considered excessive. Therefore, no additional 

controls are proposed for these non-BART sources during this planning period. However, 

conditions at the plants and control technologies may change in the future. Therefore, all of 

these sources will be reevaluated during future planning periods. 

9.5.2 Agricultural Tillage Operations 

North Dakota has approximately 38 million acres of farm and ranch land or approximately 86% 

of the State’s area. Working the land can contribute significant amounts of fugitive and 

windblown dust. The WRAP has estimated that emission sources in North Dakota put more than 

420,000 tons of particulate matter into the atmosphere in 2002. Fugitive dust from agricultural 

activities and windblown dust from farm fields were a major contributor to these emissions. 

Although there was a large amount of particulate matter emissions, the effect on visibility in the 

North Dakota Class I areas was small, but not insignificant, as shown in Figures 9.1 and 9.2 from 

the WRAP’s TSS. At TRNP, coarse mass and soil (fine mass) combined to contribute 

approximately 11% of the total extinction during the 20% worst days of the baseline period. At 

the Lostwood Wilderness Area, approximately 7% of the total extinction was due to coarse mass 

and soil. North Dakota sources contributed approximately 45 percent of the PMF and PMC at 

TRNP and approximately 30 percent at LWA during the 20 percent worst days in 2000-2004 

(based on WRAP’s weighted emissions potential analysis). 

 
189 

Figure 9.2 

TRNP Species Apportionment 

20% Worst Days 

Figure 9.3 

 LWA Species Apportionment 

20% Worst Days 

The practice of conservation tillage is becoming more popular in North Dakota. The 

Conservation Technology Information Center (CTIC) in West Lafayette, Indiana specifies that 

30 percent or more of crop residue must be left after planting to qualify as a conservation tillage 

system. Some specific types of conservation tillage include Minimum Tillage, Zone Tillage, Notill, Ridge-till, Mulch-till, Reduced-till, Strip-till, Rotational Tillage and Crop Residue 

Management. According to the Crop Residue Management survey conducted by the CTIC, total 

conservation tillage in North Dakota increased from 28% to 39% of total planted acres from 

1998 to 2004. In general, conservation tillage practices are used more in the western part of the 
190 

State (near the Class I areas) than in the eastern part of the State due to the more arid conditions, 

thinner topsoil and the types of crops grown. In 2006, 77% of the crop acreage in Williams 

County in Western North Dakota was planted using conservation tillage practices versus 28% in 

Sargent County (southeastern North Dakota). It is expected that conservation tillage practices 

will increase over the planning period. Higher fuel, equipment and labor costs will entice 

farmers to reduce tillage. Other added benefits include better soil moisture storage and 

eventually less fertilizer usage. Additionally, conservation tillage practices, such as No-till 

farming, help sequester carbon which can be sold as carbon credits. As carbon dioxide controls 

are instituted, the money earned by farmers for carbon sequestration will also provide an 

incentive for conservation tillage practices. 

Given the small contribution of coarse mass and soil to total extinction and that conservation 

tillage practices are increasing, the Department concludes there is no need to implement controls 

on farming practices. As outlined earlier, free market incentives should increase conservation 

tillage which will reduce emissions. The trend of increased conservation tillage practices from 

1998-2004 is expected to continue during the planning period. 

Sources in this category are subject to NDAC 33-15-17-02.6 which requires agricultural 

activities be managed in a manner as to minimize dust from becoming airborne. The Department 

will reevaluate the source category in future planning periods to determine if additional controls 

are required. 

9.5.3 Smoke Management for Agricultural, Forest Management and 

 Prescribed Burning 

It has been determined that no additional rules or controls for smoke management are required 

(see Section 10.6.5). The worst short-term visibility degradation that occurs in the Class I areas 

is caused by prescribed burning conducted by the Federal Land Managers. In 2005, the entire 

LWA (5,577 acres) was burned by the FLM. In addition, 3,579 acres in the immediately 

adjacent Lostwood Wildlife Refuge were burned on 7 different days. Although the State of 

North Dakota recognizes the position of the FLMs that prescribed burning is necessary to 

maintain a healthy ecosystem, it must also be recognized that the actions of the FLMs that affect 

visibility in the Class I areas must be considered when evaluating controls for others that use 

prescribed burning (e.g., farming, road maintenance, etc). No additional smoke management 

requirements are proposed in this planning period. However, the Department will reevaluate this 

source category during future planning periods to determine if additional regulation is required. 

9.5.4 Reserved

9.5.5 Oil and Gas Exploration and Production 

Oil and natural gas production in North Dakota is generally limited to the western one-third of 

the State. In September 2009, there were 4,348 operating wells that produced approximately 

238,000 barrels of oil per day. This is in contrast to states like Wyoming that has approximately 
191 

45,000 producing oil and gas wells and Colorado which has approximately 40,000 active wells. 

The primary difference is that North Dakota does not have any coal bed methane (CBM) wells. 

The lack of CBM wells means there are much fewer pumps, compressors and gas processing 

plants needed even though North Dakota produces more oil than either of these states. The 

baseline SO2 and NOx emissions from area oil and gas sources are estimated at less than 5000 

tons per year of each pollutant (see Table 6.1). 

North Dakota’s oil production is highly dependent on the price of oil. Several peaks in 

production (i.e. 1996 and 1983) have been achieved only for production to drop severely (i.e. 

42% from 1983 to 2003) and then increase as the price of oil increases. Several projections have 

been made regarding the amount of oil that will be produced in the future, the number of wells 

that will be producing and the number of drilling rigs that will operate in the State. All of these 

projections are highly speculative because of the volatility of oil prices. The price of North 

Dakota crude oil reached a high of approximately $127 per barrel in 2008 and dropped to as low 

as $25 per barrel in 2009. The number of drilling rigs also dropped dramatically from a high of 

92 in November 2008 to 35 in May 2009. WRAP has projected a 4-5 fold increase in NOx

emissions from oil and gas activities by 2018. Although emissions may increase this amount 

during the planning period, the North Dakota Oil and Gas Division of the State Industrial 

Commission believes that emissions will decrease by 2018 to a level that is 2.0 to 2.5 times the 

baseline emission rate. The Oil and Gas Division believes that activity associated with the major 

oil producing formation (Bakken formation) will be decreasing by 2018 with a peak during this 

planning period. However, any estimate of future activity is suspect because the future of oil 

prices is unknown. Because current estimates of future oil and gas activity, and emissions from 

that activity, are very questionable, the Independent Petroleum Association of Mountain States 

(IPAMS) is sponsoring development of a third, or Phase III, inventory of emissions from the 

Williston Basin in North Dakota. This inventory is not complete and available for this planning 

period. Because of the serious flaws in the Phase I and Phase II inventories, the Department 

believes that the Phase III inventory is necessary for any planning activities for oil and gas 

emissions in North Dakota. 

A Q/D type analysis does not work well for oil exploration or production facilities. These 

individual facilities generally have very low sulfur dioxide and nitrogen oxides emissions. 

However, when the facilities emissions are aggregated, there may be significant impact on 

visibility in a Class I area. The Q/D analysis in 9.5.1 included the larger compressor stations and 

natural gas processing plants (sources subject to Title V). North Dakota also permits minor oil 

and gas sources including small compressor stations (greater than 500 Hp), natural gas 

processing plants and tank batteries. The Q/D analysis indicates that only the larger facilities 

(i.e. larger Title V sources) have a significant impact on visibility in North Dakota Class I areas. 

Sulfur dioxide emissions from future oil and gas activities are not a concern because most new 

oil and gas production is from the Bakken formation which contains sweet (negligible sulfur 

content) oil and gas. In addition, engines will be required by Federal rule to use ultra low sulfur 

gasoline and diesel fuel. Nitrogen oxides emissions are the primary concern. These will 

emanate from vehicles, drilling rig engines, glycol dehydrators, flares, compressor engines, and 

other combustion sources. Stationary engines are subject to a number of New Source 

Performance Standards (NSPS) and Maximum Achievable Control Technology (MACT) 

standards which will help limit NOx emissions. The EPA has also promulgated a 1-hour 
192 

NAAQS for NO2. North Dakota had a 1-hour NO2 AAQS set at 100 ppb until December of 

1994. The new NAAQS is slightly more stringent than the former SAAQS for NO2. The 

Department’s experience indicates that oil and gas facilities will have to limit NOx emissions 

through the use of control devices such as catalytic convertors on engines or low NOx burners at 

heater/treaters or glycol dehydration unit boilers. Particulate emissions from oil and 

development and production are not expected to change appreciably from the baseline emission 

rate. Emissions from the production site are mostly from development of the well pad which is 

of short duration. Vehicle traffic would be the only other significant source of particulate matter 

emissions. Once the well is developed, these emissions should decrease substantially. 

The WRAP, through its contractor EC/R Incorporated, has prepared an analysis of the four 

factors for reasonable progress for oil and gas exploration and production operations (see 

Appendix I.2, Section 4). Given the small amount of baseline emissions and the uncertainty of 

the projection of future emissions, the Department proposes no additional controls for oil and gas 

exploration and production facilities at this time. The Department will continue to track oil and 

gas emissions and will take into consideration the Phase III inventory when it is available. 

During the mid planning period review, the Department will review oil and gas emissions and 

take action if necessary. Oil and gas emissions will also be addressed during subsequent 

planning periods. 

9.6 Visibility Modeling and Weight of Evidence 

As detailed in Section 8, modeling has been conducted by both WRAP and the NDDoH to 

estimate visibility improvement resulting from implementation of BART and other reasonable 

control measures. Modeling addressed TRNP and LWA Class I areas in North Dakota. 

Visibility improvement modeling accounted for the cumulative effect of BART controls, and 

other growth and control factors. Modeling was initially conducted using the default EPA 

methodology, and results were compared with the default EPA uniform rate of progress (URP). 

Because results based on the default EPA methodology did not achieve compliance with default 

URP targets for 2018, additional modeling was conducted by the NDDoH for various weight of 

evidence options. 

Supplemental weight of evidence modeling analyses conducted by the NDDoH, which have a 

bearing on the selection of reasonable progress goals, include the following. 

1) Discounted the impact of international (in this case, Canadian) source visibility-affecting 

emissions on North Dakota Class I areas. 

2) Discounted the impact of visibility-affecting emissions from all sources located outside 

of North Dakota, on North Dakota Class I areas. 

3) Used the complete emissions inventory for the default EPA method, but zeroed out future 

SO2 and NOX emissions from all sources located in North Dakota (i.e., assumed 100 

percent future control of all SO2 and NOX emissions in North Dakota), to determine 

progress with respect to the default glide path for North Dakota Class I areas. 
193 

4) Conducted modeling to determine the incremental visibility improvement, and cost 

effectiveness ($/dv), of enhanced control technology at AVS generating station, Coyote 

generating station, and Tioga Gas Plant (Section 9.5.1). 

Modeling results for the default EPA methodology and weight of evidence analyses are 

summarized in Table 9.11. In the table, Scenarios 1 and 2 represent the implementation of 

default EPA methodology by WRAP and NDDoH, respectively. Scenarios 3, 4, and 5 reflect the 

first three NDDoH weight of evidence analyses outlined above. Results for the fourth weight of 

evidence analysis (above) were provided in Table 9.9. Results in Table 9.11 are presented as the 

projected percent of the 2018 target. 

From results of visibility modeling based on standard EPA methodology, and results of the 

weight of evidence analyses, the following conclusions are applicable to the establishment of 

reasonable progress goals for North Dakota Class I areas. 

1) The uniform rate of progress goal for 2018 for 20% worst days will not be achieved at 

either TRNP or LWA. 

2) Apportionment modeling results indicate the contribution of sources located outside of 

North Dakota is much greater than the contribution of in-state sources to 20% worst day 

visibility at TRNP and LWA (both baseline and 2018). 

3) Though the addition of proposed BART controls substantially decreases the visibility 

impact of North Dakota EGUs, these EGUs comprise only a small component of total 

20% worst day impact at TRNP and LWA. 

Table 9.11 

NDDoH Visibility Modeling Results 20% Worst Days 

EPA Methodology and Weight of Evidence Analysis Summary 

Scenario Description Class I Area 

Projected 

Percent of 

2018 Target 

1 WRAP CMAQ 

Default EPA Methodology 

TRNP 

LWA 

24.0 

16.7 

2 NDDoH Hybrid 

Default EPA Methodology 

TRNP 

LWA 

38.1 

26.7 

3 NDDoH Hybrid 

Canada Sources Discounted 

TRNP 

LWA 

50.0 

40.2 

4 NDDoH Hybrid 

All Sources Other Than ND Discounted 

TRNP 

LWA 

83.9 

59.6 
194 

Scenario Description Class I Area 

Projected 

Percent of 

2018 Target 

5 NDDoH Hybrid 

Base Emission Inv = Default 

Future Emissions Inv = All ND 

SO2 and NOx Emissions set to zero 

TRNP 

LWA 

83.8 

72.6 

4) Compliance with 20% worst day URP 2018 targets at North Dakota Class I areas cannot 

be achieved through additional emissions reductions from North Dakota sources, alone. 

It will require significant additional visibility affecting emissions reductions from 

Canada, other western states and from sources located outside of the WRAP CMAQ 

modeling domain. 

5) After discounting the impact of Canadian sources, significantly greater progress (50 

percent greater) was demonstrated, relative to URP 2018 targets for North Dakota Class I 

areas, than modeling with the entire emissions inventory but the 20% worst day targets 

were still not achieved. 

6) After discounting the impact of all sources located outside of North Dakota, even greater 

progress was demonstrated, relative to URP 2018 targets for North Dakota Class I areas, 

than modeling with Canadian sources discounted. However, 20% worst day targets were 

still not achieved. 

7) After zeroing out all future SO2 and NOX emissions in North Dakota under default EPA 

methodology (emulating a 100 percent, unrealistic control of all sources), compliance 

with 20% worst day targets was still not achieved at North Dakota Class I areas. 

8) The use of enhanced control technology at AVS generating station, Coyote generating 

station, and Tioga Gas Plant provides minimal incremental improvement in 2018 

visibility (Table 9.9), and does not meaningfully change status with respect to 2018 

visibility goals. 

Given these conclusions based on modeling, it appears most of the visibility impact at North 

Dakota Class I areas is due to emissions from sources located outside the jurisdiction of the 

NDDoH. But regardless of the extent to which visibility-affecting sources located outside of 

North Dakota are discounted, compliance with URP targets cannot be achieved. Further, the use 

of enhanced control technology on additional candidate sources (Item 8, above) within 

jurisdiction of the NDDoH does not provide a meaningful improvement in terms of 2018 URP 

visibility goals. It is not realistic to expect significant additional controls (beyond BART or 

other current controls) will be implemented in states or Canadian provinces apart from North 

Dakota before 2018. From a modeling perspective, therefore, setting reasonable progress goals 

for 20% worst days to be consistent with 2018 modeling results for the default EPA 

methodology (Table 9.11) would seem most realistic. 
195 

9.7 Establish Reasonable Progress Goals 

As indicated in Section 8, control of emissions from North Dakota sources has only a small 

effect on visibility conditions in the North Dakota Class I areas. The source apportionment 

(based on WRAP modeling) for the 20% worst days in the Class I areas indicates that sources 

outside of North Dakota contribute from 79-87% of the sulfate or nitrate which cause the greatest 

visibility impairment in the North Dakota Class I areas. The source region apportionment 

provided by WRAP is presented in Table 9.12 for the North Dakota Class I areas. Note that the 

WRAP modeled contributions for North Dakota sources in Table 9.12 are somewhat smaller than 

the contributions based on NDDoH modeling in Table 8.16. This is because the NDDoH 

approach incorporated a more realistic representation of point source plumes, resulting in higher 

predictions for North Dakota sources (and greater visibility improvement). 

Table 9.12 

Source Region Apportionment 20% Worst Days

Contributing 

Area 

Class I Area 

TRNP LWA 

SO4 NO3 SO4 NO3

North Dakota 21.1% 19.1% 17.9% 13.0% 

Canada 28.3% 31.8% 45.9% 44.6% 

Outside Domain 32.6% 17.9% 20.2% 14.0% 

Montana 3.1% 15.0% 2.4% 9.3% 

CENRAP 4.9% 2.5% 5.3% 5.1% 

Other 10.5% 13.7% 8.3% 14.0% 

An analysis was conducted to determine if the uniform rate of progress could be achieved in the 

North Dakota Class I areas by controlling sulfur dioxide and nitrogen oxides emissions from instate sources (see Section 8.7.3.3). The results indicate the uniform rate of progress cannot be 

achieved by reductions in North Dakota alone. If all sulfur dioxide and nitrogen oxides 

emissions in North Dakota were completely controlled (zero emissions), only 72.6% of the 

uniform rate of progress for the 20% worst days would be achieved at LWA and only 83.8% at 

TRNP. Significant reductions of emissions from sources outside of North Dakota will be 

required in order to meet the uniform rate of progress for this planning period. 

North Dakota can only require emission controls for sources within its boundaries. Because of 

the large contribution to visibility impairment from sources outside of North Dakota, any 

estimate of reasonable progress on a deciview basis is tenuous at best. Any increase in emissions 

from sources external to North Dakota could offset any improvement from the reduction of 

emissions at in-state sources. By 2018, North Dakota BART controls plus other regulatory 

requirements are expected to reduce in-state SO2 emissions by more than 60% and NOx

emissions by more than 25%. Table 9.13 shows the projected change in emissions for North 

Dakota as well as surrounding states and Canada. 

 
196 

Table 9.13 

Projected Change in Emissions 

2002-2018 

(%) 

South 

Dakota Montana Minnesota Canada 

North 

Dakota 

SO2 -35.7 -11.8 -28.8 -6.8 -60.0 

NOx -17.9 -26.0 -39.4 -0.8 -25.3 

OC -6.1 -3.3 -5.3 22.7 -19.4 

EC -51.1 -16.6 -28.9 75.2 -52.3 

PMF 2.2 7.5 -1.3 34.8 2.0 

PMC 4.2 8.8 -4.4 33.8 3.5 

NH3 0.3 1.2 33.9 -31.9 -0.3 

VOC -0.5 -0.6 2.9 -1.2 1.1 

CO -17.0 -15.9 -20.8 -11.7 -27.4 

Note: Based on WRAP’s Case Plans 02d and PRP18b. 

The reasonable progress goals based on the Department’s hybrid modeling approach in Table 

9.14 are established. The analyses conducted indicate there will be no degradation in the 20% 

best days. The Department’s modeling results show that visibility in the 20% best days will 

improve 0.14 deciviews at TRNP and 0.09 deciviews at LWA. 

Table 9.14 

Reasonable Progress Goals

Class I Area 

Baseline Visibility 

20% Worst Days 

(dv) 

2018 RPGa

20% Worst Days 

(dv) 

2018 RPGb

20% Worst Days 

(dv)

TRNP 17.8 16.9 17.2 

LWA 19.6 18.9 19.1 

a

 Based on Department’s hybrid modeling approach. 

b

 Based on WRAP’s modeling approach. 

40 CFR 51.308(d)(1)(ii) requires the State to provide for public review an assessment of the 

number of years it would take to attain natural conditions if visibility improvement continues at 

the rate of progress selected by the State as reasonable. Achieving natural conditions will require 

the elimination of all anthropogenic sources of emissions. Given current technology, achieving 

natural conditions is an impossibility. Any estimate of the number of years necessary to achieve 
197 

natural visibility conditions would require assumptions about future energy sources, technology 

improvements for sources of emissions, and every facet of human behavior that causes visibility 

impairing emissions. The elimination of all SO2 and NOx emissions in North Dakota will not 

achieve the uniform rate of progress for this, or any future planning period. Any estimate of the 

number of years to achieve natural conditions is questionable because of the influence of out-ofstate sources. The number of years required to achieve natural conditions based on the proposed 

reasonable goals are as follows: 

Table 9.15 

Time Necessary to Achieve Natural Conditions

Class I Area 

Baseline 

Visibility 

Natural 

Visibility 

Improvement 

Rate this 

Planning 

Period 

Years to Natural

Conditionsa 

20% Worst 

Days 

(dv) 

20% Worst 

Days 

(dv) 

20% Worst 

Days 

(dv/yr) 

20% Worst 

Days 

TRNP 17.8 7.8 0.06429 156 

LWA 19.6 8.0 0.05000 232 

aBased on the Department’s hybrid modeling approach.

If the most efficient cost effective control options evaluated for Coyote Station, Antelope Valley 

Station and the Tioga Gas Plant were implemented, the number of years to reach natural 

conditions would be 151 years at the three units of TRNP and 201 years at LWA. Implementing 

additional controls at these sources will not significantly affect current visibility conditions or the 

amount of time necessary to achieve natural conditions. 

 
198 

10. Long -Term Strategy 

10.1 Long -Term Strategy Requirements 

40 CFR 51.308(d)(3) contains the requirements for the long-term strategy for regional haze. 

Each State listed in §51.300(b)(3) must submit a long-term strategy that addresses regional haze 

visibility impairment for each mandatory Class I Federal area within the State and for each 

mandatory Class I Federal area located outside the State which may be affected by emissions 

from the State. The long-term strategy must include enforceable emissions limitations, 

compliance schedules, and other measures as necessary to achieve the reasonable progress goals 

established by States having mandatory Class I areas. In establishing its LTS for regional haze, 

the State must meet requirements of §51.308(d)(3)(i) through (3)(v). 

10.2 Consultation With Other States 

40 CFR 51.308(d)(3)(i) requires “Where the State has emissions that are reasonably anticipated 

to contribute to visibility impairment in any mandatory Class I Federal area located in another 

State or States, the State must consult with the other State(s) in order to develop coordinated 

emission management strategies. The State must consult with any other State having emissions 

that are reasonably anticipated to contribute to visibility impairment in any mandatory Class I 

Federal area within the State.” 

North Dakota emissions are reasonably anticipated to contribute to visibility impairment in 

mandatory Class I Federal areas in Minnesota (Boundary Waters Canoe Area Wilderness Area 

and Voyageurs National Park), Montana (Medicine Lake National Wildlife Refuge Wilderness 

Area and U.L. Bend National Wildlife Refuge Wilderness Area), and South Dakota (Badlands 

National Park and Wind Cave National Park). Reasonably anticipated to contribute is considered 

to be a contribution of more than 5 percent to the total extinction (Bext) in the Class I area. North 

Dakota emissions impacts on Michigan Class I areas (Isle Royal National Park and Seney 

National Wildlife Refuge Wilderness Area) are small or less than 5 percent of the extinction 

(Bext). North Dakota emissions impacts on other more distant Class I areas are considered 

minimal. See the discussion in Section 2.4. 

The NDDoH has consulted with Minnesota and Michigan as a part of the Northern Class I Areas 

consultation group and Minnesota individually. As a result of the consultations, Minnesota sent 

a memorandum dated September 19, 2007 to North Dakota and other states impacting Minnesota 

Class I areas. Minnesota requested a response documenting these consultations have taken place 

to the satisfaction of North Dakota or detailing areas where additional consultation should occur. 

In those states Minnesota has identified as additional contribution states, they asked such states 

to respond with their agreement or disagreement with Minnesota’s determination of contributing 

states and the additional control strategies that will be evaluated. Minnesota’s memorandum and 

the NDDoH letter of response dated August 22, 2008 are attached in Appendix J.2. 
199 

The NDDoH has consulted with Montana and South Dakota through the WRAP which we are 

members and as needed individually. Additionally the NDDoH has consulted with EPA Region 8 

in Denver concerning the Montana Class I areas as they are preparing a FIP at the request of the 

State. 

Minnesota, Montana and South Dakota are the only states that have emissions that are 

reasonably anticipated to contribute to visibility impairment in the North Dakota Class I Federal 

areas. 

Consultation is further addressed in Section 3, Plan Development and Consultation. 

10.3 Demonstration of Inclusion of Measures to Obtain RPGs in Class 

I Areas 

40 CFR 51.308(d)(3)(ii) requires “Where other States cause or contribute to impairment in a 

mandatory Class I Federal area, the State must demonstrate that it has included in its 

implementation plan all measures necessary to obtain its share of the emission reductions needed 

to meet the progress goal for the area. If the State has participated in a regional planning process, 

the State must ensure it has included all measures needed to achieve its apportionment of 

emission reduction obligations agreed upon through that process.” 

The control measures and emission limits incorporated in this SIP for the seven electrical 

generating units subject to BART combined with Federal mobile source and other rules will 

reduce North Dakota sulfur dioxide emissions by 60 percent, nitrogen oxide emissions by 25 

percent, organic carbon emissions by 19 percent and elemental carbon emissions by 52 percent. 

These percent reductions compare favorably with the uniform rate of progress first planning 

period required overall reduction by 2018 of approximately 23.3 percent (14 years ÷ 60 years x 

100 = 23.3 percent). In addition, existing State smoke management and fugitive dust control 

rules will adequately control emissions from agricultural and forest burning and construction 

activities. North Dakota has met and included in this SIP all measures needed to achieve its 

apportionment of emission obligations agreed upon by the members of WRAP. These emission 

reductions will provide North Dakota’s share of emission reductions needed for Class I Federal 

areas in Minnesota, Michigan, Montana and South Dakota. 

10.4 Documentation of the Technical Basis for Modeling, Monitoring 

and Emissions Information 

40 CFR 51.308(d)(3)(iii) requires “The State must document the technical basis, including 

modeling, monitoring and emissions information, on which the State is relying to determine its 

apportionment of emission reduction obligations necessary for achieving reasonable progress in 

each mandatory Class I Federal area it affects. The State may meet this requirement by relying 

on technical analyses developed by the regional planning organization and approved by all State 

participants. The State must identify the baseline emissions inventory on which its strategies are 
200 

based. The baseline emissions inventory year is presumed to be the most recent year of the 

consolidated periodic emissions inventory.” 

North Dakota is a member of the Western Regional Air Partnership (WRAP) regional planning 

organization and relied on the modeling, monitoring and emissions information and technical 

analyses developed by WRAP. 

The NDDoH relied on the use of CALPUFF for single source BART screening modeling, 

WRAP CMAQ and PSAT modeling, and its own hybrid CALPUFF modeling in its cumulative 

impact analyses. The BART modeling conformed to the requirements of the BART guidelines 

and is described in Section 7. The WRAP CMAQ and PSAT modeling and the NDDoH hybrid 

CALPUFF modeling conformed with EPA modeling guidelines and are described in Section 8. 

The NDDOH relied on IMPROVE monitoring data as available on the WRAP TSS website and 

discussed in Section 4. 

The NDDoH used the WRAP Plan02d emissions inventory for the baseline emissions year 2002 

which reflects a composite interpretation of emissions for the base 2000-2004 period; and the 

WRAP CMAQ PRP18a (Preliminary Reasonable Progress 2018 Scenario A) emissions 

inventory which reflects projected year 2018 emissions. Case PRP18a represents base period 

emissions projected to 2018, accounting for estimates of the effect of BART controls, and 

assuming other growth and control factors. The Plan02d and PRP18a emissions inventories were 

used in modeling and are discussed further in Section 8. A later Case PRP18b emissions 

inventory was prepared by WRAP and included in Section 6, Sources of Visibility Impairment in 

North Dakota Class I Areas. 

10.5 Identification of Anthropogenic Sources of Visibility Impairment 

40 CFR 51.308(d)(3)(iv) requires “The State must identify all anthropogenic sources of visibility 

impairment considered by the State in developing its long-term strategy. The State should 

consider major and minor stationary sources, mobile sources and area sources.” 

The anthropogenic sources of visibility impairment are identified in Section, 6 Sources of 

Visibility Impairment in North Dakota Class I Areas. 

10.6 Seven Factors That Must be Considered in Developing the LTS 

40 CFR 51.308(d)(3)(v) requires “The State must consider, at a minimum, the following factors 

in developing its long-term strategy: 

(A) Emission reductions due to ongoing air pollution control programs, including measures to 

address reasonably attributable visibility impairment; 
201 

(B) Measures to mitigate the impacts of construction activities; 

(C) Emissions limitations and schedules for compliance to achieve the reasonable progress 

 goal; 

(D) Source Retirement and Replacement schedules; 

(E) Smoke management techniques for agriculture and forestry management purposes 

including plans as currently exist within the State for these purposes; 

(F) Enforceability of emissions limitations and control measures; and 

(G) The anticipated net effect on visibility due to projected changes in point, area, and mobile 

source emissions over the period addressed by the long-term strategy.” 

10.6.1 Emission Reductions Due to Ongoing Air Pollution Control 

 Programs 

10.6.1.1 In-Place Programs 

40 CFR 51.308(d)(3)(v)(A) requires an assessment of emission reductions due to ongoing air 

pollution control programs. Programs that are in place which will assist in reducing emissions 

and help achieve reasonable progress toward the national visibility goal include: 

- Minor Source Permit to Construct Program (NDAC 33-15-14-02) 

- Prevention of Significant Deterioration Program (NDAC 33-15-15) 

- New Source Performance Standards (NDAC 33-15-12) 

- Emission Standards for Hazardous Air Pollutants (NDAC 33-15-13) 

- Emission Standards for Hazardous Air Pollutants for Source Categories (NDAC 33-15-

 22) 

- Oil and Gas Production Facilities Rules (NDAC 33-15-21) 

- Open Burning Requirements (NDAC 33-15-04) 

- Fugitive Dust Control Requirements (NDAC 33-15-17) 

- Control of Sulfur Dioxide from Point Sources (NDAC 33-15-06) 

- Control of Particulate Matter (NDAC 33-15-05) 

- Control Requirements for Organic Compounds Sources (NDAC 33-15-07) 

- Heavy Duty Diesel Engine Standard (2007) 

- Tier 2 Tailpipe Standards 

- Large Spark Ignitor and Recreational Vehicle Rule

- Nonroad Diesel Rule 

- Industrial Boiler MACT 

- Combustion Turbine and Reciprocating Internal Combustion Engines NSPS and MACT 

 Standards 

The Federal programs are described in more detail in Section 2.5. 
202 

Some MACT standards have been vacated; however, it is expected that revised versions of these 

standards will be promulgated by EPA during the planning period. The Department will 

continue to operate a PSD program and take delegation of NSPS standards and major source 

MACT standards for source categories located in North Dakota. As older sources are replaced, 

the new applicable rules should reduce emissions. 

North Dakota has implemented a reasonably attributable visibility impact (RAVI) protection 

program since 1987. The rules implementing this program are found in NDAC 33-15-19, 

Visibility Protection. The control strategy and monitoring strategy are found in Chapters 3 and 6 

of the State Implementation Plan. The existing RAVI program, with the existing permitting and 

emissions rules listed above is compatible with those needed for regional haze and no revisions 

are needed or planned at this time. The NDDoH will address the periodic review and revision 

requirements of the long-term RAVI strategy as required by 40 CFR 51.306(c) and coordinate 

them with the regional haze LTS periodic progress reports required by 40 CFR 51.308(g). 

10.6.1.2 Coyote Station

Once reductions are achieved from the BART sources, the Coyote Station will be the largest 

point source of NOx emissions in North Dakota. The analysis in Section 9.5.1 indicates that 

additional controls on the Coyote Station are not reasonable at this time; however, the State, 

through recent discussions with Otter Tail Power Company, has reached an agreement whereby 

Otter Tail has committed to reduce NOx emissions at the station. Otter Tail Power Company has 

indicated they will install equipment by July 1, 2018 in order to reduce NOx emissions to 0.50 

lb/106 Btu. This represents a 35% decrease from the 2008 emission rate of 0.77 lb/106 Btu and 

26% from the baseline emission rate evaluated in Section 9.5.1. The reductions are expected to 

be achieved by installing separated over fire air. This will reduce annual NOx emissions by 

4,213 tons from the 2000-2004 baseline, a 32% decrease. The mechanism/requirement for 

reducing NOx emissions is included in a Permit to Construct found in Appendix A. Although 

there will be NOx reductions at this facility, it will be reevaluated during future planning periods 

to determine if additional emissions reductions are required. 

10.6.1.3 Heskett Station Unit 2 – Reserved 

10.6.2 Measures to Mitigate the Impacts of Construction Activities 

40 CFR 51.308(d)(3)(v)(B) requires the consideration of measures to mitigate the impacts of 

construction activities. North Dakota regulates fugitive emissions by rule (NDAC 33-15-17). 

This rule states: 

“No person shall cause or permit fugitive emissions from any source whatsoever, 

including a building, its appurtenances, or a road, to be used, constructed, altered, 

repaired, or demolished; or activities such as loading, unloading, storing, handling, or 

transporting of material without taking reasonable precautions to prevent such emissions 

from causing air pollution as defined in section 33-15-01-04.” 
203 

NDAC 33-15-17-02 also states in part: 

“No person shall emit or cause to be emitted into the ambient air from any source of 

fugitive emissions as specified in section 33-15-17-01 any particulate matter which: 

2. Exceed the ambient air quality standards of chapter 33-15-02 at or beyond the 

property line of the source. 

3. Exceed the prevention of significant deterioration of air quality increments of 

chapter 33-15-15 at or beyond the property line of the source for sources subject to 

chapter 33-15-15. 

4. Exceed the restrictions on the emission of visible air contaminants of chapter 33-15-

03, at or beyond the property line of the source. 

5. Would have an adverse impact on visibility, as defined in chapter 33-15-19, on any 

class 1 federal area.” 

The Department requires permits for asphalt concrete plants and rock, sand and gravel plants 

which are generally associated with major construction projects. The Department requires 

notification of the relocation of asphalt plants in order to track the emissions from these facilities. 

The Federal Class I areas in North Dakota are located in the western part of the State, generally 

away from the major population centers. These population centers are 40 - 500 km away from 

the Class I areas. Any construction in these areas should have little effect on visibility in the 

Class I areas because of the transport distance and prevailing winds will generally move the 

fugitive emissions in the opposite direction. Any impacts on visibility in a Class I area due to 

construction activities would most likely be associated with energy development including oil 

and gas well pad construction, compressor station construction and gas processing plant 

construction. Owners of sources subject to permitting requirements, including the above energy 

facilities, are subjected to fugitive dust control requirements included in the permit issued for the 

construction of the facility. In addition, all sources are subject to the requirements of NDAC 33-

15-17. NDAC 33-15-17-03 lists the measures which are considered reasonable precautions for 

abating and preventing fugitive dust. These include: 

1. Unpaved roads and unpaved parking areas. Abatement and preventive measures include 

but shall not be limited to frequent watering, addition of dust palliatives, detouring, 

paving, closure, speed control, or other means such as surface treatment with penetration 

chemicals (ligninsulfonates, oil, water, cutbacks, etc.) or methods of equal or greater 

effectiveness in reducing the air contaminant produced. 

2. Demolition, wrecking and explosive detonation activities; earth and construction material 

moving, mining, and excavation activities. 
204 

a. Abatement and preventive fugitive particulate control measures include, but are 

not limited to: 

 (1) Wetting down, including prewatering. 

 (2) Landscaping and replanting with native vegetation. 

 (3) Covering, shielding or enclosing the area. 

 (4) Paving, temporary or permanent. 

 (5) Treating, the use of dust palliatives and chemical stabilization. 

 (6) Detouring. 

 (7) Restricting the speed of vehicles on sites. 

 (8) Preventing the deposit of dirt and mud on improved streets and roads. 

 (9) Minimizing topsoil disturbance and reclaiming as soon as possible. 

b. Sequential blasting be employed whenever or wherever feasible to reduce the 

amounts of particulate matter. 

c. Such dust control strategies as revegetation, delay of topsoil disturbance until 

necessary, or surface compaction and sealing, be applied. 

d. Haulage equipment be washed or wetted down, treated, or covered when 

necessary to minimize the amount of dust becoming airborne in transit and in 

loading. 

e. Stockpile of materials be treated to prevent blowing or the material be contained 

in silos or other suitable enclosures. 

f. Waste disposal sites be so operated and constructed as to prevent particulate 

matter from becoming airborne. 

g. All conveyors, transfer points, crushers, screens, and dryers be so constructed, 

protected, or treated as to prevent particulate matter from becoming airborne. 

h. These measures also be used during period when actual construction work is not 

being conducted, such as on weekends and holidays. 

The construction of oil well pads are normally a one or two-day undertaking. The emissions are 

generally ground level emissions and do not travel very far. In general, compressor stations and 

gas plant construction are subject to the Permit to Construct program. These permits and rules 
205 

will assure that construction activities will not adversely affect visibility in any Federal Class I 

area. 

Emissions from construction activities including construction of oil well pads, compressor 

stations and gas plants will be reevaluated in future Regional Haze SIP planning periods since 

this has the potential to be a growing source category. 

10.6.3 Emissions Limitations and Schedules for Compliance 

40 CFR 51.308(d)(3)(v)(C) requires the State to consider emissions limitations and schedules for 

compliance to achieve the reasonable progress goal in developing its LTS. 

Emissions limitations and schedules for the seven BART sources are found in Section 7, Best 

Available Retrofit Technology (BART). They are included in the Air Pollution Control Permit 

to Construct for each source. The permits found in Appendix D are incorporated as part of this 

SIP. 

10.6.4 Source Retirement and Replacement Schedules

40 CFR 51.308(d)(3)(v)(D) requires the State consider any source retirement and replacement 

schedules in developing its LTS. The Department is not aware of any anticipated major source 

retirements or replacements. Replacement of existing facilities will be managed in conformance 

with the existing State Implementation Plan including the Prevention of Significant Deterioration 

program. 

The 2018 modeling conducted by WRAP included three new power plants to be located in the 

State. It is now unlikely that two of these plants will be built. Thus the modeling results for 

2018 are probably conservative. Construction of new power plants or replacement of existing 

plants prior to 2018 is unlikely. 

10.6.5 Smoke Management Techniques for Agriculture and Forest 

Management 

40 CFR 51.308(d)(3)(v)(E) requires the State to consider smoke management techniques for 

agriculture and forestry management purposes including plans as currently exist within the State 

for these purposes in developing its LTS. North Dakota has an area of approximately 68,994 

square miles (44.16 million acres). Of this total, 26.5 million acres is crop land, 10.98 million 

acres is pasture/rangeland and 236,000 acres is woodland/forest with the five State forests 

comprising 13,300 acres. The North Dakota State Implementation Plan contains rules which 

govern prescribed burning on crop land, pasture/rangeland or woodland. NDAC 33-15-04-02.2 

lists the conditions that apply to any prescribed burning including: 
206 

c. Care must be used to minimize the amount of dirt on the material being burned and 

the material must be dry enough to burn cleanly. 

d. Oils, rubber, and other materials that produce unreasonable amounts of air 

contaminants may not be burned. 

e. The burning may be conducted only when meteorological conditions favor smoke 

dispersion and air mixing. 

h. Except in an emergency, burning may not be conducted in such proximity of any 

class 1 area, as defined in chapter 33-15-15, that the ambient air of such area is 

adversely impacted. 

i. Except in an emergency, the visibility of any class 1 area cannot be adversely 

impacted as defined in chapter 33-15-19. 

j. Burning activities must be attended and supervised at all times burning is in 

progress. 

Fires purposely set to woodland/forest or rangeland for the management of the land or game 

must be in accordance with practices recommended by State and Federal agencies and must be 

approved in advance by the Department (NDAC 33-15-04-02.1.e). Although agricultural crop 

burning does not require advanced approval by the Department, most of this burning takes place 

in the eastern two thirds of State away from the Class I areas in North Dakota. In general, 

prevailing winds carry the smoke from crop land burning away from the North Dakota Class I 

areas. For 2000-2004 (Case Plan 02d), the WRAP has estimated the annual emissions from fire 

in North Dakota as shown in Table 10.1. 

Table 10.1 

Annual Average Emissions from Fire (2000-2004) 

Source 

PMfine

(tpy) 

PMcoarse

(tpy) 

NOx 

(tpy) 

SO2

(tpy) 

Organic 

Carbon 

(tpy) 

Elemental 

Carbon 

(tpy) 

Natural 225 441 773 250 2,214 424 

Anthropogenic 596 62 1001 290 1,443 86 

Total 821 503 1774 540 3,657 510 

Based on the source apportionment analyses conducted by the WRAP, anthropogenic fire 

emissions in North Dakota contribute less than 1% of the total emissions of any of the pollutant 

species listed above during the 20% worst visibility days for either Lostwood Wilderness Area or 

Theodore Roosevelt National Park as shown in Table 10.2. The contribution of anthropogenic 

fire is expected to decrease by 2018. As indicated earlier, open burning is subject to regulation 

under NDAC 33-15-04 which specifically prohibits burning that will adversely affect visibility in 

any Class I area. The Department has determined that the current smoke management rules are 
207 

sufficient to achieve reasonable progress toward the national visibility goal. However, the 

smoke management rules will be reevaluated during future planning periods. 

Table 10.2 

North Dakota Anthropogenic Fire Contribution to the 20% Worst Days

Class I Area Pollutant 

Contribution 

2000-2004 

(%) 

Contribution 

2018 

(%) 

TRNP SOx

NOx

POA 

EC 

PMF 

PMC 

0.013 

0.019 

0.364 

0.067 

0.04 

0.001 

0.004 

0.006 

0.112 

0.024 

0.013 

0 

LWA SOx

NOx

POA 

EC 

PMF 

PMC 

0.008 

0.024 

0.823 

0.13 

0.049 

0.001 

0.002 

0.007 

0.252 

0.046 

0.015 

0 

10.6.6 Enforceability of Emission Limitations and Control Measures 

40 CFR 51.308(d)(3)(v)(F) requires the State must consider the enforceability of emission 

limitations and control measures in developing its LTS. The BART emission limits and control 

measures will be included in a BART Air Pollution Control Permit to Construct that is issued to 

each BART source and are incorporated into this SIP. The Permit to Construct program is 

established in the State Air Pollution Control Rules (NDAC 33-15-14-02). The program is also 

approved into the State Implementation Plan. The BART permits are included in Appendix D of 

this SIP. Other ongoing programs are already included in the State rules. Future NSPS and 

MACT rules for major sources will be adopted into the State Rules and delegation will be 

requested from EPA. 

10.6.7 The Anticipated Net Effect on Visibility Due to Projected Changes 

in Point, Area and Mobile Source Emissions 

40 CFR 51.308(d)(3)(v)(G) requires the State consider the anticipated net effect on visibility due 

to projected changes in point, area, and mobile source emissions over the period addressed by the 

long-term strategy in developing its LTS. The anticipated net effect on visibility due to projected 

changes in emissions from 2004 to 2018 is discussed in Section 8, Visibility Modeling. 
208 

10.7 Prevention of Significant Deterioration 

In North Dakota, new and modified existing major stationary sources triggering significance 

thresholds are analyzed under the Prevention of Significant Deterioration (PSD) permitting 

program. The PSD program rules are found in NDAC Chapter 33-15-15 and have been 

approved as a part of the North Dakota SIP by EPA. The PSD permitting program is an integral 

part of North Dakota’s long-term strategy for meeting its regional haze goals. 

Among other things, the PSD permit program is designed to protect air quality and visibility in 

Class I areas by requiring best available control technology (BACT) and involving the public in 

permit decisions. The PSD permitting process requires a technical air quality analysis and 

additional analyses to assess the potential impacts of emissions on soils, vegetation and visibility. 

The cumulative impacts of emissions subject to the PSD program will be evaluated to ensure 

there is no degradation from baseline conditions on the 20 percent worst days and the 20 percent 

best days. 

Therefore, North Dakota’s current PSD program ensures that visibility at the Class I areas will 

not be impacted by growth in stationary sources. 

 
209 

11. Commitment to Consultation, Progress Reports, Periodic 

 Evaluations of Plan Adequacy, and Future SIP Revisions 

11.1 Future Consultation Commitments 

11.1.1 FLM Consultation and Coordination 

40 CFR 51.308(i) contains the requirements for State and Federal Land Manger consultation and 

coordination. §51.308(i) reads “What are the requirements for State and Federal Land Manager 

coordination? 

(1) By November 29, 1999, the State must identify in writing to the Federal Land Managers 

the title of the official to which the Federal Land Manager of any mandatory Class I 

Federal area can submit any recommendations on the implementation of this subpart 

including, but not limited to: 

 (i) Identification of impairment of visibility in any mandatory Class I Federal area(s); 

 and 

(ii) Identification of elements for inclusion in the visibility monitoring strategy 

required by § 51.305 and this section. 

(2) The State must provide the Federal Land Manager with an opportunity for consultation, 

in person and at least 60 days prior to holding any public hearing on an implementation 

plan (or plan revision) for regional haze required by this subpart. This consultation must 

include the opportunity for the affected Federal Land Managers to discuss their: 

(i) Assessment of impairment of visibility in any mandatory Class I Federal area; and 

(ii) Recommendations on the development of the reasonable progress goal and on the 

development and implementation of strategies to address visibility impairment. 

(3) In developing any implementation plan (or plan revision), the State must include a 

description of how it addressed any comments provided by the Federal Land Managers. 

(4) The plan (or plan revision) must provide procedures for continuing consultation between 

the State and Federal Land Manager on the implementation of the visibility protection 

program required by this subpart, including development and review of implementation 

plan revisions and 5-year progress reports, and on the implementation of other programs 

having the potential to contribute to impairment of visibility in mandatory Class I Federal 

areas.” 
210 

North Dakota commits to coordinate and consult with the Federal Land Managers as required in 

§51.308(i)(1) through (4). 

11.1.2 Tribal Consultation 

North Dakota will continue to remain in contact with those Tribes which may reasonably be 

anticipated to cause or contribute to visibility impairment in North Dakota mandatory Class I 

Federal area(s). For those Tribes that adopted a RH TIP, North Dakota will consult with them 

directly. For those Tribes without a RH TIP, North Dakota will consult with both the Tribe and 

EPA. Documentation of the consultations will be maintained. 

 

11.1.3 Interstate Consultation and Coordination 

40 CFR 51.308(d)(1)(iv) and 40 CFR 51.308(d)(3)(i) contain the requirements for interstate 

consultation and coordination. §(d)(1)(iv) reads: 

“In developing each reasonable progress goal, the State must consult with those States 

which may reasonably be anticipated to cause or contribute to visibility impairment in the 

mandatory Class I Federal area. In any situation in which the State cannot agree with 

another such State or group of States that a goal provides for reasonable progress, the 

State must describe in its submittal the actions taken to resolve the disagreement. In 

reviewing the State’s implementation plan submittal, the Administrator will take this 

information into account in determining whether the State’s goal for visibility 

improvement provides for reasonable progress towards natural visibility conditions.” 

§(d)(3)(i) reads: 

 

“Where the State has emissions that are reasonably anticipated to contribute to visibility 

impairment in any mandatory Class I Federal area located in another State or States, the 

State must consult with the other State(s) in order to develop coordinated emission 

management strategies. The State must consult with any other State having emissions that 

are reasonably anticipated to contribute to visibility impairment in any mandatory Class I 

Federal area within the State.” 

In accordance with 40 CFR 51.308(d)(1)(iv) and 51.308(d)(3)(i), North Dakota commits to 

continue consultation with Minnesota, Montana, and South Dakota, and any other state which 

may reasonably be anticipated to cause or contribute to visibility impairment in federal Class I 

areas located within North Dakota. North Dakota will also continue consultation with Michigan, 

Minnesota, Montana, and South Dakota and any other state for which North Dakota’s emissions 

may reasonably be anticipated to cause or contribute to visibility impairment in those state’s 

federal Class I areas. 

With reference to the established or updated goals for reasonable progress, should disagreement 

arise between another state or group of states, North Dakota will describe the actions taken to 

resolve the disagreement in future RH SIP revisions for EPA’s consideration. With reference to 
211 

assessing or updating long-term strategies, North Dakota commits to coordinate its emission 

management strategies with affected states and will continue to include in its future RH SIP 

revisions all measures necessary to obtain its share of emissions reductions for meeting progress 

goals. 

11.2 Commitment to Progress Reports 

Requirements for the State to submit periodic progress reports are found in 40 CFR 51.308(g) 

which reads “Requirements for periodic reports describing progress towards the reasonable 

progress goals. Each State identified in §51.300(b)(3) must submit a report to the Administrator 

every five years evaluating progress towards the reasonable progress goal for each mandatory 

Class I Federal area located within the State and in each mandatory Class I Federal area located 

outside the State which may be affected by emissions from within the State. The first progress 

report is due 5 years from the submittal of the initial implementation plan addressing paragraphs 

(d) and (e) of this section. The progress reports must be in the form of implementation plan 

revisions that comply with the procedural requirements of §51.102 and §51.103. Periodic 

progress reports must contain at a minimum the following elements: 

(1) A description of the status of implementation of all measures included in the 

implementation plan for achieving reasonable progress goals for mandatory Class I 

Federal areas both within and outside the State. 

(2) A summary of the emissions reductions achieved throughout the State through 

implementation of the measures described in paragraph (g)(1) of this section. 

(3) For each mandatory Class I Federal area within the State, the State must assess the 

following visibility conditions and changes, with values for most impaired and least 

impaired days expressed in terms of 5-year averages of these annual values. 

(i) The current visibility conditions for the most impaired and least impaired days; 

(ii) The difference between current visibility conditions for the most impaired and 

least impaired days and baseline visibility conditions; 

(iii) The change in visibility impairment for the most impaired and least impaired days 

over the past 5 years; 

(4) An analysis tracking the change over the past 5 years in emissions of pollutants 

contributing to visibility impairment from all sources and activities within the State. 

Emissions changes should be identified by type of source or activity. The analysis must 

be based on the most recent updated emissions inventory, with estimates projected 

forward as necessary and appropriate, to account for emissions changes during the 

applicable 5-year period. 
212 

(5) An assessment of any significant changes in anthropogenic emissions within or outside 

the State that have occurred over the past 5 years that have limited or impeded progress in 

reducing pollutant emissions and improving visibility. 

(6) An assessment of whether current implementation plan elements and strategies are 

sufficient to enable the State, or other States with mandatory Federal Class I areas 

affected by emissions from the State, to meet all established reasonable progress goals. 

(7) A review of the State’s visibility monitoring strategy and any modifications to the 

strategy as necessary.” 

In accordance with the requirements listed in 40 CFR 51.308(g) of the federal regional haze rule, 

North Dakota commits to submitting periodic progress reports to EPA every five years following 

the initial submittal of the SIP. The periodic progress reports will address at a minimum all the 

elements of §51.308(g). The periodic progress reports will be in the form of implementation plan 

revisions that comply with the procedural requirements of 40 CFR 51.102 and 51.103.

11.3 Determination of Current Plan Adequacy 

Based on the findings of the 5-year periodic progress report, 40 CFR 51.308(h) requires a State 

to make a determination of adequacy of the existing implementation plan. §51.308(h) reads 

“Determination of the adequacy of existing implementation plan. At the same time the State is 

required to submit any 5-year progress report to EPA in accordance with paragraph (g) of this 

section, the State must also take one of the following actions based upon the information 

presented in the progress report: 

(1) If the State determines that the existing implementation plan requires no further 

substantive revision at this time in order to achieve established visibility goals for 

visibility improvement and emissions reductions, the State must provide to the 

Administrator a negative declaration that further revision of the existing implementation 

plan is not needed at this time. 

 

(2) If the State determines that the implementation plan is or may be inadequate to ensure 

reasonable progress due to emissions from sources in another State(s) which participated 

in a regional planning process, the State must provide notification to the Administrator 

and the other State(s) which participated in the regional planning process with the States. 

The State must also collaborate with the other State(s) through the regional planning 

process for the purpose of developing additional strategies to address the plan’s 

deficiencies. 

(3) Where the State determines that the implementation plan is or may be inadequate to 

ensure reasonable progress due to emissions from sources in another country, the State 

shall provide notification, along with available information, to the Administrator. 

 
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(4) Where the State determines that the implementation plan is or may be inadequate to 

ensure reasonable progress due to emissions from sources within the State, the State shall 

revise its implementation plan to address the plan’s deficiencies within one year.” 

 

North Dakota commits, in accordance with 40 CFR 51.308(h), to make a determination of the 

adequacy of the existing implementation plan at the same time a five-year periodic progress 

report is due. 

Should North Dakota determine that the implementation plan is or may be inadequate to ensure 

reasonable progress due to emissions from sources in another State or States, North Dakota will 

provide notification to the Administrator and the other State(s) and collaborate with the other 

States(s) through the regional planning process for the purpose of developing additional 

strategies to address the plan’s deficiencies as required by §51.308(h)(2). In the event that no 

regional planning organizations or process exists, North Dakota will work directly with the other 

State(s). 

Should North Dakota determine that the current implementation plan is or may be inadequate 

due to emissions from within the State itself, North Dakota will develop additional strategies to 

address the plan deficiencies and revise the implementation plan within one year, as required by 

§51.308(h)(4). 

Should North Dakota determine that the implementation plan is or may be inadequate to ensure 

reasonable progress due to emissions from sources in another country, the State will provide 

notification, along with available information, to the Administrator as required by §51.308(h)(3). 

Should North Dakota determine that the existing implementation plan requires no further 

substantive revision in order to achieve established goals for visibility improvement and 

emissions reductions, North Dakota will provide the Administrator a negative declaration that 

further revision of the existing implementation plan is not needed as required by §51.308(h)(1). 

In addition, North Dakota commits to revise the implementation plan, including the reasonable 

progress goals, once RH SIPs from neighboring states become available and are approved by 

EPA, or if the unexpected or unforeseen occurs. This would include, but not be limited to, 

projected future emissions reductions that do not occur, are distributed differently over an 

alternate geographic area, or are found to be incorrect or flawed. These revisions will be made 

within one year as required by §51.308(h)(4). North Dakota also commits to accelerate this 

revision schedule if the present RH SIP is found to be significantly flawed and the 2018 

reasonable progress goals cannot be reasonably attained. 

11.4 Commitment to Future SIP Revisions 

In addition to a SIP revision made for periodic progress reports as addressed in Section 11.2 and 

plan inadequacy as addressed in Section 11.3, 40 CFR 51.308(f) requires a State to revise and 

submit its regional haze implementation plan to EPA by July 31, 2018, and every ten years 

thereafter. 40 CFR 51.308(f) reads “Requirements for comprehensive periodic revisions of 
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implementation plans for regional haze. Each State identified in §51.300(b)(3) must revise and 

submit its regional haze implementation plan revision to EPA by July 31, 2018 and every ten 

years thereafter. In each plan revision, the State must evaluate and reassess all of the elements 

required in paragraph (d) of this section, taking into account improvements in monitoring data 

collection and analysis techniques, control technologies, and other relevant factors. In evaluating 

and reassessing these elements, the State must address the following: 

(1) Current visibility conditions for the most impaired and least impaired days, and actual 

progress made towards natural conditions during the previous implementation period. 

The period for calculating current visibility conditions is the most recent five year period 

preceding the required date of the implementation plan submittal for which data are 

available. Current visibility conditions must be calculated based on the annual average 

level of visibility impairment for the most and least impaired days for each of these five 

years. Current visibility conditions are the average of these annual values. 

(2) The effectiveness of the long-term strategy for achieving reasonable progress goals over 

the prior implementation period(s); and 

(3) Affirmation of, or revision to, the reasonable progress goal in accordance with the 

procedures set forth in paragraph (d)(1) of this section. If the State established a 

reasonable progress goal for the prior period which provided a slower rate of progress 

than that needed to attain natural conditions by the year 2064, the State must evaluate and 

determine the reasonableness, based on the factors in paragraph (d)(1)(i)(A) of this 

section, of additional measures that could be adopted to achieve the degree of visibility 

improvement projected by the analysis contained in the first implementation plan 

described in paragraph (d)(1)(i)(B) of this section.” 

In accordance with the requirements of section 51.308 (d) and (f) of the regional haze rule, North 

Dakota commits to revising and submitting its regional haze SIP by July 31, 2018 and every ten 

years thereafter addressing current visibility conditions, effectiveness of the long-term strategy 

and affirming or revising the reasonable progress goal for each mandatory Class I Federal area in 

North Dakota.

11.5 Monitoring Strategy 

North Dakota commits to review and reevaluate the adequacy of and revise as necessary the 

existing RAVI monitoring strategy required by Section 51.305 and the existing regional haze 

monitoring strategy required by Section 51.308(d)(4) as a minimum, concurrently with the 5-

year periodic progress reports and the 10-year plan revisions which start July 31, 2018 and every 

ten years thereafter. North Dakota will coordinate all reviews, reevaluations and revisions to 

both monitoring strategies with each other and will consult and coordinate any revisions with 

EPA and FLMs. The monitoring strategies are discussed further in Section 4 of this plan.

 
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11.6 Rules for Non-BART Point and Area Sources

The Department adopted rules in 1987 to implement Phase 1 of the federal visibility program 

which is Section 40 CFR 51.300 – 307 (NDAC Chapter 33-15-19 Visibility Protection, effective 

date October 1, 1987) and in 2006 to implement the BART portion of Phase 2 which is 

Paragraph 40 CFR 51.308(e) (NDAC Chapter 33-15-23 Regional Haze Requirements, effective 

date January 1, 2007). For a more detailed description of Phase 1 and Phase 2 of the federal 

visibility program see Section 2. 

As a result of addressing the core requirements of the federal visibility program which are found 

in 40 CFR 51.308(d), the Department has determined it will be necessary to clarify its legal 

authority to address emissions which adversely impact visibility in the Class I areas from nonBART and area sources which may in the future be found to be reasonably controllable and 

reduced (see Section 9). 

The Department commits to develop and adopt any necessary rules to clarify its legal authority 

to control and reduce emissions from non-BART and area sources that adversely impact Class I 

areas as expeditiously as possible but no later than December 31, 2012. 

 
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12. Public Participation and Review Process 

The Public Hearing Record is Appendix F. Included are the Hearing Notice (F.1), Press Release 

(F.2), Affidavit of Publication (F.3), Invoice of Publication (F.4), Registration List of Attendees 

(F.5), Hearing Transcript (F.6), Certification of Hearing (F.7), and Response to Public 

Comments (F.8). 

12.1 Summary of Comments Received during Public Comment 

 Period/Hearing 

The written comments and oral comments received during the 30 day public comment period and 

public hearing are included in Appendix F.6 as a part of the Hearing Transcript and Response to 

Comments. 

Written comments were received from the U.S. Environmental Protection Agency Region 8 in 

Denver CO; The U.S. Department of the Interior National Park Service in Denver CO; the 

National Parks Conservation Association in Chicago IL on behalf of the National Parks 

Conservation Association, the Dakota Resource Council, the Friends of the Boundary Waters 

Wilderness, the Plains Justice and the Dakotah Chapter of the Sierra Club; Basin Electric Power 

Cooperative in Bismarck ND; Great River Energy in Maple Grove MN; and Bob Paine of 

AECOM Environment on behalf of Basin Electric Power Cooperative, Great River Energy, and 

Minnkota Power Cooperative, Inc. 

In addition, the Department received 31 nearly identical emails from various individuals. 

Mr. Jim Kambeitz presented oral testimony at the public hearing and submitted written 

comments that reiterated his oral comments. 

12.2 Response to Public Comments 

The Department’s responses to the comments received during the 30 day public comment period 

and public hearing are included in Appendix F.8. 

12.3 Revisions to the State Implementation Plan 

The Department made the following revisions to Regional Haze State Implementation Plan based 

on its review of the comments received during the 30 public comment period and public hearing: 

• Page ii – An Approval Page was added. 

• Section 4.2 – A discussion on the representativeness of the IMPROVE monitor at the 

South Unit of the Theodore Roosevelt National Park for the North Unit and Elkhorn 

Ranch Unit was added. 
217 

• Section 5.2 – A reference to the discussion in Section 4.2 on the representativeness of the 

IMPROVE monitor in the South Unit of TRNP was added. 

• Section 5.2 – A reference was added for the WRAP methodology for determining 

baseline conditions under Table 5.1. 

• Section 7.3.4 - Exclusion of Montana Dakota Utilities Heskett Unit No. 2 was updated. 

• Section 8.6.1 – Performance evaluation expanded to include results for the 98th percentile 

metric. 

• Section 8.6.2.5 – Per EPA suggestion, conclusions modified to acknowledge that BART 

emissions reductions from ND sources can significantly improve visibility under some 

meteorological conditions. 

• Table 9.4 – MDU Heskett Unit No. 2 was added. 

• Table 9.9 – Table was modified to add additional information. 

• Section 9.5.1 – Reasonable Progress Goals – Required Controls for Point Sources – A 

sentence was added regarding the percent improvement in visibility for the control 

options evaluated. 

• Section 9.5.4 – The section was relocated to Section 10.6.1.2 and updated. 

• Section 9.5.5 – The section was updated to discuss PM emissions and Q/D for oil wells. 

• Section 9.7 – The section was updated to indicate that the Reasonable Progress Goals are 

based on the Department’s hybrid modeling. 

• Section 10.6.1.2 – The section was added to address emissions reductions from the 

Coyote Station. 

• Section 10.6.5 – The section was updated to indicate the North Dakota smoke 

management rules will be reevaluated during future planning periods. 

• Section 11.6 – The section was updated. 

• Section 12 – Each item is now addressed as the 30 day public comment period and 

hearing has been completed. 

• Appendix A.5 – A new appendix was added to address the WRAP methodology for 

determining baseline visibility conditions. 

• Appendix F.9 – The section was deleted as it was not required. 

• Appendix I.2 – A new appendix was added to provide supplementary information for the 

four factor analysis by the WRAP states. 

• Several spelling, grammatical and typographical corrections were made throughout the 

document. 

12.4 Revisions to the BART Air Pollution Control Permits to Construct 

The Department made the following revisions to BART Air Pollution Control Permits to 

Construct based on its review of the comments received during the 30 day public comment 

period and public hearing: 

• The definition of 30 day rolling average was modified to match the NSPS Subpart Da 

language in all the BART permits. 

• Condition II.A.2 was changed from “BART” to “Regional Haze” in the Stanton, Leland 

Olds and Minnkota permits. 
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• The location of the CEM was added to Condition II.A.3 in the Stanton permit. The 

condition was also changed to specify that emissions from Unit 1 and Unit 10 must be 

measured separately. 

• Condition II.A.1.c was revised to include a procedure for demonstrating compliance if a 

startup is less than 24 hours in the Minnkota permit. 

• Condition II.A.2 was changed from “Data” to “Date” in the Coyote permit. 

• Condition II.A.4.a was changed from “94%” to “95%” in the Coal Creek permit. 

• Condition II.A.1.a of the Coyote permit was amended to specify that EUI 1 is the main 

boiler. 

• In Condition II.B.4 of the Coyote permit, Unit 1 was changed to EUI 1. 

• In Condition II.A.5.e of the Coyote permit, “Condition II.5” was changed to “Condition 

II.A.5.” 

• In Condition II.A.5.b of the Minnkota, Coal Creek, Leland Olds and Stanton permits, 

“Condition II.5.a” was changed to “Condition II.A.5.a.”