MISSISSIPPI 

DEPARTMENT OF ENVIRONMENTAL QUALITY 

OFFICE OF POLLUTION CONTROL 

STATE IMPLEMENTATION PLAN (SIP) REVISION 

REGARDING FEDERAL REGIONAL HAZE PROGRAM REQUIREMENTS 

INCLUDING THE SIP NARRATIVE 

ADDRESSING VISIBILITY IMPROVEMENT 

IN FEDERAL CLASS I AREAS 

Adopted August 28, 2008
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

2

TABLE OF CONTENTS 

1.44 Introduction: State Implementation Plan (SIP) Revision Regarding requirements of 

Federal Clean Air Act Regional Haze Addressing Visibility in Federal Class I Areas. 

1.45 Notification of Public Hearing for the Regional Haze SIP Revision. 

3.21 Legal Authority for the Regional Haze SIP Revision. 

5.19 Control Strategy for the Regional Haze SIP Revision. 

6.23 Control Regulations for the Regional Haze SIP Revision. 

14.1.18 Health Effects of the Regional Haze SIP Revision. 

14.3.18 Economic Effects of the Regional Haze SIP Revision. 

14.5.18 Social Effects of the Regional Haze SIP Revision. 

14.6.18 Air Quality Effects of the Regional Haze SIP Revision. 

Appendix R Regional Haze SIP Revision Narrative. 
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

3

1.44 Introduction: State Implementation Plan (SIP) Revision Regarding Regional Haze 

Requirements of the Federal Clean Air Act Addressing Visibility in Federal Class I Areas. 

Regional haze is pollution that impairs visibility over a large region, including national 

parks, forests, and wilderness areas (many termed “Class I” areas). Regional haze is caused 

by sources and activities emitting fine particles and their precursors, often transported over 

large regions. Particles affect visibility through the scattering and absorption of light. 

Reducing fine particles in the atmosphere is an effective method of improving visibility. In 

the southeast, the most important sources of haze-forming emissions are coal-fired power 

plants, industrial boilers and other combustion sources, but mobile source emissions, area 

sources, fires, and wind blown dust also contribute. 

An easily understood measure of visibility to most people is visual range. Visual range is the 

greatest distance, in kilometers or miles, at which a dark object can be viewed against the 

sky. However, the most useful measure of visibility impairment is light extinction, which 

affects the clarity and color of objects being viewed. The measure used by the regional haze 

rule is the deciview (dv), calculated directly from light extinction using a logarithmic scale. 

The regional haze rule requires states to demonstrate reasonable progress toward meeting the 

national goal of a return to natural visibility conditions by 2064. The rule directs states with 

Class I areas to graphically show what would be a “uniform rate of progress”, also known as 

the “glide path”, toward natural conditions for each Class I area within the State. 

Mississippi does not have any Class I areas, but the Class I areas: the Breton National 

Wildlife Refuge (Breton) in Louisiana, Sipsey Wilderness Area (Sipsey) in Alabama, and 

Caney Creek Wilderness Area (Caney Creek) in Arkansas, are the closest to its state 

boundaries and the impact of sources in Mississippi to those Class I areas has been assessed. 

 The Area of Impact (AOI) analysis, developed by VISTAS, indicates that sources in 

Mississippi do not significantly contribute to visibility impairment for Sipsey, Caney Creek, 

or any other Class 1 area. Sources in Mississippi appear to contribute to visibility impact for 

Breton. The AOI emission contribution spreadsheets are further discussed in Section 7.5 and 

found in Appendix M. Since there are no Class I areas in Mississippi, “uniform rate of 

progress” (or “glide path”) toward natural conditions will not be presented. 

The Regional Haze SIP Narrative included in Appendix R of this SIP Revision contains 

summaries of the technical analyses that will be used by Mississippi Department of 

Environmental Quality (MDEQ) to support the regional haze state implementation plan 

pursuant to §§107(d)(3)(D) and (E) of the Clean Air Act, as amended. 
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

4

1.45 Notification of Public Hearing for Regional Haze SIP Revision.

Public participation on the Regional Haze SIP Revision was achieved by a public hearing 

held on Wednesday, July 16, 2008, at 1:30 p.m. in the Commission Hearing Room at the 

offices of the Mississippi Department of Environmental Quality, 515 E. Amite Street, 

Jackson, Mississippi in accordance with the information provided in the public notice and 

Mississippi Administrative Procedures Act. The notice for public hearing will be published 

consistent with procedures approved by EPA. 

The notice of public hearing was published on June 16, June 23, and June 30, 2008, in daily 

newspapers in the cities of Gulfport, Jackson, and Tupelo in the State of Mississippi. The 

notice of public hearing and the proposed SIP revision was made available for public review 

in the main branches of the public libraries in the above mentioned cities and at the offices of 

the Mississippi Department of Environmental Quality, 515 E. Amite Street, Jackson, 

Mississippi. This notice was also mailed to persons on the air pollution control regulation 

mailing list. 

The notice of public hearing follows this page. 
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

5

MISSISSIPPI COMMISSION ON ENVIRONMENTAL QUALITY 

NOTICE OF PROPOSED PLAN REVISION 

NOTICE OF PUBLIC HEARING 

PUBLIC NOTICE START DATE: June 16, 2008 

 PLEASE TAKE NOTE that the Mississippi Commission on Environmental Quality 

(“Commission”) is considering a Revision to the State Implementation Plan for Air Pollution 

Control (SIP Revision) and will conduct a public hearing to receive comments on the proposed SIP 

Revision. The proposed SIP Revision involves the implementation of federal regional haze 

regulations as promulgated by the U.S. Environmental Protection Agency (EPA). The proposed SIP 

Revision will be applicable statewide. 

I. Subject of the Proposed Action. 

 The SIP Revision involves the State of Mississippi’s plan for implementing federal regional 

haze regulations as promulgated by EPA. The SIP Revision addresses reasonable progress goals for 

visibility improvement in nearby Federal Class I areas and includes Best Available Retrofit 

Technology (BART) determinations for emission sources located in the State of Mississippi. A 

summary of comments previously received from the Federal Land Managers (FLMs) is included as 

an appendix to the proposed SIP Revision. 

II. Manner By Which the Public May Comment. 

 Copies of the proposed SIP Revision may be obtained by calling Ms. Maya Rao at 601-961-

5242 or Mr. Elliott Bickerstaff at 601-961-5176 or writing to Mississippi Department of 

Environmental Quality, Air Division, P. O. Box 2262, Jackson, Mississippi 39225. For those persons 

with internet access, a copy of the proposed SIP revision may be found on the Mississippi 

Department of Environmental Quality’s website at http://www.deq.state.ms.us. Also, copies of the 

proposed SIP Revision will be available for public review through Wednesday, July 16, 2008, in the 

main branch of public libraries in the cities of Gulfport, Jackson, and Tupelo in the State of 

Mississippi. The proposed SIP Revision may also be reviewed in the offices of the Mississippi 

Department of Environmental Quality, 515 E. Amite St., Jackson, Mississippi. For an appointment 

to review the proposed SIP Revision at the offices of MDEQ, contact Mr. Elliott Bickerstaff at (601) 

961-5176. 

 Members of the public may present verbal or written comments at the public hearing 

described below. Also, written statements regarding the proposed SIP Revision will be made part of 

the public hearing record if delivered by 5:00 p.m., Wednesday, July 16, 2008, to the attention of 

Ms. Maya Rao at the address shown above. 

III. Notice of Public Hearing. 

A public hearing regarding the proposed SIP Revision will be conducted. The hearing will 

be held on Wednesday, July 16, 2008, at 1:30 p.m. in the Commission Hearing Room (Room 104A) 

of the Mississippi Department of Environmental Quality Office Building at 515 E. Amite St., 

Jackson, Mississippi. 
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

6

IV. Additional Information. 

For additional information, please contact Ms. Maya Rao at 601-961-5242 or Mr. Elliott 

Bickerstaff at 601-961-5176. 

Regional Haze SIP Public Notice June 16 2008 
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

7

3.21 Legal Authority for the Regional Haze SIP Revision

No legislative actions are needed concerning this Regional Haze SIP revision. The State of 

Mississippi Air & Water Pollution Control Law, Section 49-17-1 to 49-17-43, Mississippi 

Code of 1972, gives the Commission on Environmental Quality the necessary legal authority 

to adopt and implement this Regional Haze SIP revision. State law (as of July 1, 2007) 

Mississippi Code Annotated, Section 49-17-13(1) designates the Commission as the State air 

pollution control agency for all purposes of the federal pollution control legislation and 

programs and to take all actions necessary thereto. 

Public participation on this Regional Haze SIP revision was achieved by a public hearing 

held on Wednesday, July 16, 2008, at 1:30 p.m. in the Commission Hearing Room at the 

offices of the Mississippi Department of Environmental Quality, 515 E. Amite Street, 

Jackson, Mississippi. 
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

8

5.19 Control Strategy for the Regional Haze SIP Revision

The SIP narrative in Appendix R addresses control strategies for improvement of visibility in 

Federal Class I areas. 
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

9

6.23 Control Regulations for the Regional Haze SIP Revision

The regional haze SIP Revision does not include any changes to state regulations. The 

regional haze SIP Revision is a non-regulatory action. The SIP Narrative in Appendix R 

references Federal requirements addressing visibility in Federal Class I areas. 
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

10

14.1.18 Health Effects of the Regional Haze SIP Revision

No adverse health effects are expected to be caused by this Regional Haze SIP 

revision. 
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

11

14.3.18 Economics Effects of the Regional Haze SIP Revision

No adverse economic effects due to this Regional Haze SIP revision are foreseen. 
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

12

14.5.18 Social Effects of the Regional Haze SIP Revision

No adverse social effects are foreseen as a result of this Regional Haze SIP revision. 
Regional Haze Final SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008 

13

14.6.18 Air Quality Effects of the Regional Haze SIP Revision

This Regional Haze SIP revision will not have any adverse air quality effects. 
Regional Haze Proposed SIP Revision Master Document 

State of Mississippi 

C. Simmons 

September 9, 2008

14

MISSISSIPPI DEPARTMENT OF ENVIRONMENTAL QUALITY 

OFFICE OF POLLUTION CONTROL 

STATE IMPLEMENTATION PLAN REVISION 

REGARDING REGIONAL HAZE PROGRAM REQUIREMENTS 

APPENDIX R 

SIP NARRATIVE 

ADDRESSING VISIBILITY IMPROVEMENT 

IN FEDERAL CLASS I AREAS 

Adopted August 28, 2008
 i 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Preface: This document contains summaries of the technical analyses that will be used by 

Mississippi Department of Environmental Quality (MDEQ) to support the regional haze state 

implementation plan pursuant to §§107(d)(3)(D) and (E) of the Clean Air Act, as amended. 
 ii 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

TABLE OF CONTENTS 

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

1.1 What is regional haze?.............................................................................................................. 1 

1.2 What are the requirements under the Clean Air Act for addressing regional haze?............. 1 

1.3 General overview of regional haze SIP requirements .......................................................... 2 

1.4 Class I areas near Mississippi ............................................................................................... 4 

1.5 State and Federal Land Manager (FLM) coordination ......................................................... 6 

2.0 ASSESSMENT OF BASELINE AND CURRENT CONDITIONS AND ESTIMATE OF 

NATURAL BACKGROUND CONDITIONS IN CLASS I AREAS ................................... 9 

3.0 GLIDEPATHS TO NATURAL CONDITIONS...................................................................... 9 

4.0 EMISSION INVENTORY IMPROVEMENTS....................................................................... 9 

4.1 Baseline Emissions Inventory............................................................................................... 9 

4.1.1 Stationary Point Sources ............................................................................................ 10 

4.1.2 Stationary Area Sources ............................................................................................. 11 

4.1.3 Off-Road Mobile Sources .......................................................................................... 12 

4.1.4 Highway Mobile Sources ........................................................................................... 12 

4.1.5 Biogenic Emission Sources........................................................................................ 13 

4.1.6 Summary of the Final 2002 (October 2007 version) Baseline Emissions Inventory. 13 

4.1.7 Emissions Inventory Improvements........................................................................... 14 

4.2 Assessment of Relative Contributions from Specific Pollutants and Sources Categories . 15 

5.0 REGIONAL HAZE MODELING METHODS AND INPUTS ............................................. 16 

5.1 Analysis Method................................................................................................................. 16 

5.2 Model Selection .................................................................................................................. 17 

5.2.1 Selection of Photochemical Grid Model .................................................................... 17 

5.2.2 Selection of Meteorological Model............................................................................ 18 

5.2.3 Selection of Emissions Processing System ................................................................ 20 

5.3 Selection of the Modeling Year.......................................................................................... 21 

5.4 Modeling Domains ............................................................................................................. 22 

5.4.1 Horizontal Modeling Domain .................................................................................... 22 

5.4.2 Vertical Modeling Domain......................................................................................... 24 

6.0 MODEL PERFORMANCE EVALUATION......................................................................... 25 

6.1 Modeling Performance Goals, and Criteria ........................................................................ 26 

6.2 VISTAS Domain-Wide Performance ................................................................................. 27 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

6.3 Performance in Nearby Class 1 Areas ................................................................................ 31 

7.0 LONG-TERM STRATEGY FOR CLASS I AREAS THAT ARE NEAR MISSISSIPPI..... 33 

7.1 Overview of the Long-Term Strategy Development Process............................................. 33 

7.2 Expected Visibility Results in 2018 for Class I Areas Neighboring Mississippi under 

existing and planned emissions controls (Base G2 Inventory) ........................................ 34 

7.2.1 Emission Controls Modeled and Requirements ......................................................... 34 

7.2.2 Point Source Controls (EGU and non-EGU) ............................................................. 37 

7.2.3 Area Source Controls ................................................................................................. 40 

7.2.4 Mobile Sources........................................................................................................... 40 

7.2.5 Non-Road ................................................................................................................... 41 

7.2.6 Conclusion.................................................................................................................. 41 

7.3 What Control Determinations Represent Best Available Retrofit Technology (BART) for 

Individual Sources? .......................................................................................................... 43

7.3.1 BART-Eligible Sources in Mississippi ...................................................................... 44 

7.3.2 Determination of Sources Subject to BART in Mississippi....................................... 45 

7.3.3 Determination of BART Requirements for Subject-to-BART Sources..................... 48 

7.4 Relative Contributions to Visibility Impairment: Pollutants, Source Categories, and 

Geographic Areas ............................................................................................................. 49

7.5 Relative Contributions to Visibility Impairment: Geographic Areas of Influence for 

Neighboring Class I Areas ............................................................................................... 52 

7.5.1 Back Trajectory Analyses .......................................................................................... 53 

7.5.2 Residence Time Plots ................................................................................................. 53 

7.5.3 SO2 Areas of Influence ............................................................................................... 54 

7.5.4 Emissions Sources within SO2 Areas of Influence .................................................... 55 

7.5.5 Specific Sources in the Areas of Influence ................................................................ 59 

7.6 Evaluating the Specific SO2 Emissions Sources................................................................. 61 

7.7 What Additional Emissions Controls Were Considered as part of the Long-Term Strategy 

for Visibility Improvement by 2018?............................................................................... 65 

7.8 Long Term Strategy Summary ........................................................................................... 65 

8.0 REASONABLE PROGRESS GOALS................................................................................... 66 

9.0 MONITORING STRATEGY................................................................................................. 66 

10.0 INTERSTATE CONSULTATION ...................................................................................... 66 

11.0 COMPREHENSIVE PERIODIC IMPLEMENTATION PLAN REVISIONS ................... 67 

12.0 DETERMINATION OF ADEQUACY OF THE EXISTING PLAN .................................. 69 
 iv 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

LIST OF APPENDICES 

Appendix A: VISTAS Memorandum of Understanding and Bylaws 

Appendix B: VISTAS Conceptual Description Document 

Appendix C: Modeling Analysis Protocol and Quality Assurance Project Plan 

Appendix D: Emissions Preparation and Results 

Appendix E: Air Quality and Meteorological Preparations and Results 

Appendix F: Meteorological Modeling Evaluation 

Appendix G: VISTAS Technical Support Document 

Appendix H: Mississippi APC-S-1 Regulations 

Appendix I: Data Access 

Appendix J: Consultation Process 

Appendix K: Recommended Improvements 

Appendix L: BART information 

Appendix M: Class 1 Area of Interest (AOI) Contribution Spreadsheets 

Appendix N: DuPont Reasonable Progress Information 

Appendix O: Regional Haze SIP Federal Land Managers Comments 
 v 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

EXECUTIVE SUMMARY 

Introduction 

Regional haze is pollution that impairs visibility over a large region, including national parks, 

forests, and wilderness areas (many termed “Class I” areas). Regional haze is caused by sources 

and activities emitting fine particles and their precursors, often transported over large regions. 

Particles affect visibility through the scattering and absorption of light. Reducing fine particles 

in the atmosphere is an effective method of improving visibility. In the southeast, the most 

important sources of haze-forming emissions are coal-fired power plants, industrial boilers and 

other combustion sources, but mobile source emissions, area sources, fires, and wind blown dust 

also contribute. 

An easily understood measure of visibility to most people is visual range. Visual range is the 

greatest distance, in kilometers or miles, at which a dark object can be viewed against the sky. 

However, the most useful measure of visibility impairment is light extinction, which affects the 

clarity and color of objects being viewed. The measure used by the regional haze rule is the 

deciview (dv), calculated directly from light extinction using a logarithmic scale. 

The regional haze rule requires states to demonstrate reasonable progress toward meeting the 

national goal of a return to natural visibility conditions by 2064. The rule directs states with 

Class I areas to graphically show what would be a “uniform rate of progress”, also known as the 

“glide path”, toward natural conditions for each Class I area within the State. 

No Class I Areas within the State Boundaries of Mississippi 

Mississippi does not have any Class I areas, but the Class I areas: the Breton National Wildlife 

Refuge (Breton) in Louisiana, Sipsey Wilderness Area (Sipsey) in Alabama, and Caney Creek 

Wilderness Area (Caney Creek) in Arkansas, are the closest to its state boundaries and the 

impact of sources in Mississippi to those Class I areas has been assessed. The Area of Impact 

(AOI) analysis, developed by VISTAS, indicates that sources in Mississippi do not significantly 

contribute to visibility impairment for Sipsey, Caney Creek, or any other Class 1 area. Sources 

in Mississippi appear to contribute to visibility impact for Breton. The AOI emission 

contribution spreadsheets are further discussed in Section 7.5 and found in Appendix M. Since 

there are no Class I areas in Mississippi, “uniform rate of progress” (or “glide path”) toward 

natural conditions will not be presented.

The Executive Summary Figure 1 below illustrates the location of these Class I areas that are 

nearest to Mississippi. 
 vi 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Executive Summary Figure 1. Class I Areas in States Surrounding Mississippi. 

State Implementation Plan Requirements 

States are required to submit state implementation plans (SIPs) to the United States 

Environmental Protection Agency (USEPA) that set out each state’s plan for meeting the 

national goal of a return to natural visibility conditions by 2064 for states with Class I areas. The 

plan includes the states’ reasonable progress goals, expressed in deciviews, for visibility 

improvement at each affected Class I area for each 10-year period until 2064. Since Mississippi 

does not have any Class I areas, Reasonable Progress Goals are not presented. The reasonable 

progress goals for Class I areas near Mississippi are under the purview/scope of the states where 

the Class I areas reside. However, Mississippi has addressed the impact of sources in 

Mississippi on Class I areas in surrounding states and considered those impacts in the 

development of the long term strategy for Mississippi. 

The long-term strategy includes enforceable emissions limitations, compliance schedules, and 

other measures as necessary to help achieve the reasonable progress goals. States must also 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

consider ongoing control programs, measures to mitigate construction activities, source 

retirement and replacement schedules, smoke management programs for agriculture and forestry, 

and enforceability of specific measures. 

These plans will cover long-term strategies for visibility improvement between baseline 

conditions in 2000-2004 and 2018. States are required to evaluate progress toward reasonable 

progress goals every 5 years to assure that installed emissions controls are on track with 

emissions reduction forecasts in each SIP. 

Federal and State Control Requirements 

There are significant control programs being implemented between the baseline period and 2018. 

These programs will all reduce the particulate emissions that affect visibility in the Class I areas, 

and include: the Clean Air Interstate Rule (CAIR), the NOx SIP Call, consent agreement with 

Chevron, one-hour ozone SIPs submitted by Birmingham, Alabama and Baton Rouge, 

Louisiana, NOx RACT in 8-hour nonattainment area SIPs, heavy duty diesel (2007) engine 

standard (for on-road trucks and buses), Tier 2 tailpipe standards for on-road vehicles, large 

spark ignition and recreational vehicle rule, nonroad diesel rule, and various Federal Maximum 

Achievable Control Technology regulations (MACT). For more detailed explanation of these 

control programs see Section 7.2.1 – Emission Control Modeled and Requirements. Of these, 

the CAIR rule has the largest effect. It requires significant reductions of SO2 and NOx from 

Electric Generating Units (EGU) in a cap and trade program. Several large Electric Generating 

Units in South Mississippi are planning to install NOx and SO2 controls to reduce emissions. 

The regional haze rule also requires states to determine best available retrofit technology 

(BART) for certain facilities. There are fifteen (15) BART eligible Sources in Mississippi. 

Thirteen (13) of the BART-eligible sources were able to demonstrate that the facilities did not 

cause or contribute to visibility impairment, two are BART subject. BART analysis of one of the 

subject sources, Mississippi Phosphates in Pascagoula, Mississippi, found that no additional 

controls may be necessary. This facility is currently working on a construction application for 

planned modifications. As part of this process, they will address the BART requirements and 

submit their complete engineering analysis by the end of the year. The planned modifications 

will result in reduced emissions for Mississippi Phosphates. The other facility, Chevron 

Refinery in Pascagoula, Mississippi (Appendix L.10) is BART subject and there are significant 

emission reductions scheduled. Section 7.3.2 provides detail on how the BART eligible sources 

were able to demonstrate they were not subject to BART. 

Interstate Consultation 

The Regional Haze Rule requires interstate consultation between states. As part of VISTAS, 

MDEQ has consulted with other VISTAS states regarding the impact of Mississippi’s sources on 

Class I areas in VISTAS states. In addition, Mississippi borders the CENtral Regional Air 

Planning (CENRAP) Organization which contains Class I areas in Breton, Louisiana and Caney 

Creek, Arkansas. Mississippi has attended CENRAP meetings and, particularly, has consulted 

with Louisiana with regard to impact of Mississippi sources on Breton. Please refer to Section 

10 and Appendix J for details on consultation. 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

Conclusion 

The modeling analysis performed by Visibility Improvement State and Tribal Association of the 

Southeast (VISTAS) finds that sulfur dioxide (SO2) is the primary pollutant impacting visibility 

in the southeast. Executive Summary Figure 2 shows that emissions of SO2 from Mississippi 

sources are significantly less than those from surrounding states. Further, MDEQ is expecting 

significant emissions reductions by 2018. Section 7.2 addresses expected emission reductions 

from various sources resulting from existing federal measures and Section 7.6 addresses facilities 

reviewed for Reasonable Progress Goals. 

Executive Summary Figure 2. SO2 Emission Totals for Mississippi and Surrounding 

States, 2002 and 2018 (2018 emission totals may not reflect all emission reductions for each 

state). 

Since Mississippi does not have any Class I areas within the state boundaries, it is not in 

scope/purview of the state of Mississippi to set reasonable progress goals for any surrounding 

areas. However, there are significant emissions reductions expected from Mississippi sources 

that will help in attaining the reasonable progress goals for Class I areas in surrounding states.

2002 2002

2002

2002

2002

2018

2002

 2018

 2018

 2018

 2018

2018

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

AL FL MS TN AR LA

Tons per Year, SO2

2002

2018
 1 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

1.0 INTRODUCTION 

1.1 What is regional haze? 

Regional haze is pollution from disparate sources that impairs visibility over a large region, 

including national parks, forests, and wilderness areas (federal “Class I” areas). Regional haze is 

caused by sources and activities emitting fine particles and their precursors. Those emissions are 

often transported over large regions. 

Particles affect visibility through the scattering and absorption of light, and fine particles – 

particles similar in size to the wavelength of light – are most efficient, per unit of mass, at 

reducing visibility. Fine particles may either be emitted directly or formed from emissions of 

precursors, the most important of which are sulfur dioxides (SO2) and nitrogen oxides (NOx). 

Reducing fine particles in the atmosphere is generally considered to be an effective method of 

reducing regional haze, and thus improving visibility. Fine particles also adversely impact 

human health, especially respiratory and cardiovascular systems. The United States 

Environmental Protection Agency (USEPA) has set national ambient air quality standards for 

daily and annual levels of fine particles with diameter smaller than 2.5 μm (PM2.5). The most 

important sources of PM2.5 and its precursors are coal-fired power plants, industrial boilers and 

other combustion sources. Other significant contributors to PM2.5 and visibility impairment 

include mobile source emissions, area sources, fires, and wind blown dust. 

1.2 What are the requirements under the Clean Air Act for addressing 

regional haze? 

In Section 169A of the 1977 Amendments to the Clean Air Act (CAA), Congress set forth a 

program for protecting visibility in Federal Class I areas which calls for the “prevention of any 

future, and the remedying of any existing, impairment of visibility in mandatory Class I Federal 

areas which impairment results from manmade air pollution.” Congress adopted the visibility 

provisions to protect visibility in 156 national parks and wilderness areas. On December 2, 

1980, USEPA promulgated regulations to address visibility impairment (45 FR 80084). The 

1980 regulations were developed to address visibility impairment that is “reasonably 

attributable” to a single source or small group of sources. These regulations represented the first 

phase in addressing visibility impairment and deferred action on regional haze that emanates 

from a variety of sources until monitoring, modeling and scientific knowledge about the 

relationships between pollutants and visibility impairment improved. 

In the 1990 Amendments to the CAA, Congress added section 169B and called on USEPA to 

issue regional haze rules. The Regional Haze rule (RHR) that USEPA promulgated on July 1, 

1999 (64 FR 35713), revised the existing visibility regulations in order to integrate provisions 

addressing regional haze impairment and establish a comprehensive visibility protection program 

for Class I Federal areas. States are required to submit state implementation plans (SIPs) to 

USEPA that set out each states’ plan for complying with the regional haze rule, including 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

consultation and coordination with other states and with federal land managers. The timing of 

the SIP submittal is tied to USEPA’s promulgation of designations for the National Ambient Air 

Quality Standard (NAAQS) for fine particulate matter (PM2.5) at 40 CFR Part 81. States must 

submit a regional haze implementation plan to USEPA within three years after the date of 

designation. Because USEPA promulgated PM2.5 designation dates on December 17, 2004, 

regional haze SIPs must be submitted by December 17, 2007, which is also specified at 40 CFR 

51.308(b). 

The regional haze rule addressed the combined visibility effects of various pollution sources over 

a wide geographic region. This wide reaching pollution net meant that many states – even those 

without Class I Areas – would be required to participate in haze reduction efforts. USEPA 

designated five Regional Planning Organizations (RPO) to assist with the coordination and 

cooperation needed to address the visibility issue. Those states that make up the southeastern 

portion of the contiguous United States are known as VISTAS (Visibility Improvement – State 

and Tribal Association of the Southeast), and include the following states: Alabama, Florida, 

Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West 

Virginia. 

 

 Figure 1.2-1. Geographical Areas of Regional Planning Organizations. 

1.3 General overview of regional haze SIP requirements 

The regional haze rule (RHR) at 51.308(d) requires states to demonstrate reasonable progress 

toward meeting the national goal of a return to natural visibility conditions by 2064. As a guide 

for reasonable progress, the RHR directs states to graphically show what would be a “uniform 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

rate of progress” toward natural conditions for each mandatory Class I Federal area within the 

State and/or for each mandatory Class I Federal area located outside the State, which may be 

affected by emissions from sources within the State. States are to establish baseline visibility 

conditions for 2000-2004, natural background visibility conditions in 2064, and the rate of 

uniform progress between baseline and background conditions. The uniform rate of progress is 

also known as the “glidepath.” 

The RHR then requires States with Class 1 areas to establish reasonable progress goals (RPGs), 

expressed in deciviews, for visibility improvement at each affected Class I area covering each 

(approximately) 10-year period until 2064. The goals must provide for reasonable progress 

towards achieving natural visibility conditions, provide for 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 (see §51.308(d)(1)). 

In order to ensure that visibility goals are properly met and set, state implementation plans must 

include determinations, for each Class I area, of the baseline visibility conditions (expressed in 

deciviews) for the most impaired and least impaired days. SIPs must also contain supporting 

documentation for all required analyses used to calculate the degree of visibility impairment 

under natural visibility conditions for the most impaired and least impaired days (see 

§51.308(d)(2)). In addition, states must include 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 (see §51.308(d)(4)). 

This first set of reasonable progress goals must be met through measures contained in the state’s 

long-term strategy covering the period from the present until 2018. The long-term strategy 

includes enforceable emissions limitations, compliance schedules, and other measures as 

necessary to achieve the reasonable progress goals, including all controls required or expected 

under all federal and state regulations by 2009 and by 2018. During development of the longterm strategy, states are also required to consider specific factors such as the abovementioned 

ongoing control programs, measures to mitigate construction activities, source retirement and 

replacement schedules, smoke management programs for agriculture and forestry, and 

enforceability of specific measures (see §51.308(d)(3)). 

In addition, a specific component of each state’s first long-term strategy is dictated by the 

specific best available retrofit technology (BART) requirements in 40 CFR 51.308(e) of the 

RHR. The RHR at §51.308(e) requires states to include a determination of BART for each 

BART-eligible source in the State that emits any air pollutant, which may reasonably be 

anticipated to cause or contribute to any impairment of visibility in any mandatory Class I 

Federal area. Clean Air Act section 169A(b) defines BART-eligible sources as sources in 26 

specific source categories, in operation within a 15-year period prior to enactment of the 1977 

Clean Air Act Amendments, and has the potential to emit 250 tons a year of visibility-impairing 

pollution. States must determine BART according to five factors set out in section 169A(g)(7) of 

the Clean Air Act. Emission limitations representing BART and schedules for compliance with 

BART for each source subject to BART must be included in the long-term strategy. 
 4 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

State Implementation Plans for the first review period are due December 17, 2007. These plans 

will cover long-term strategies for visibility improvement between baseline conditions in 2000-

2004 and 2018. States are required to evaluate progress toward reasonable progress goals every 

5 years to assure that installed emissions controls are on track with emissions reduction forecasts 

in each SIP. The first interim review would be due to USEPA in December 2012. If emissions 

controls are not on track to meet SIP forecasts, then states may need to take action to assure 

emissions controls by 2018 will be consistent with the SIP or to revise the SIP to be consistent 

with the revised emissions forecast. The periodic review is addressed in more detail in section 

11. 

1.4 Class I areas near Mississippi 

Mississippi has no Class I areas within its borders: The Class I Areas that are closest to 

Mississippi are Breton National Wildlife Refuge in Louisiana, Sipsey Wilderness Area in 

Alabama and Caney Creek Wilderness Area in Arkansas. The Air Division of the Mississippi 

Department of Environment Quality (MDEQ) is responsible for developing the Regional Haze 

SIP. This SIP establishes a long-term strategy that will help achieve the reasonable progress 

goals set by the neighboring states within the first regional haze planning period. 
 5 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Figure 1.4-1. Class I Areas Near Mississippi. 

In developing this SIP, MDEQ has also considered that emission sources within Mississippi may 

affect visibility at some of the Class I areas in neighboring states. Through VISTAS, the 

southeastern states have worked together to assess state-by-state contributions to visibility 

impairment in Class I areas within the VISTAS region and those in neighboring regions. This 

technical work is discussed further in chapters 5, 6, and 7 below. Consultations to date between 

Mississippi and other states are summarized in chapter 10; consultations are ongoing. 

Congress considered several legislative bills to reduce sulfur dioxide and nitrogen oxides from 

electric generating utilities. In 2004, USEPA promulgated the Clean Air Interstate Rule (CAIR) 

to require emissions reductions for sulfur dioxide and nitrogen dioxide from electric generating 

utilities in 26 eastern states. The CAIR rule allows for interstate trading of emissions to find cost 

effective reductions. These reductions will improve visibility in Class I areas closest to 

Mississippi. 
 6 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

1.5 State and Federal Land Manager (FLM) coordination 

As required by 40 CFR §51.308(i), the regional haze SIP must include procedures for continuing 

consultation between the States and Federal Land Managers on the implementation of the 

visibility protection program, 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 any mandatory Class I Federal area. 

Successful implementation of a regional haze program will involve long-term regional 

coordination among States. VISTAS was formed in 2001 to address regional haze and visibility 

problems in the southeastern United States. Jurisdictions represented by VISTAS members 

include the Eastern Band of Cherokee Indians; the States of Alabama, Florida, Georgia, 

Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia; 

and the local air pollution control programs located in these States. A copy of the VISTAS 

Memorandum of Agreement and Bylaws, which Mississippi intends to reference as a guideline 

for consultation procedures, is enclosed as Appendix A. Additional consultation procedures 

with FLMs are described in Sections 11 and 12. 

The objectives of the VISTAS project are to establish natural background visibility conditions 

across the mandatory Class I Federal areas, identify current visibility impairment levels, analyze 

emission control levels that will achieve interim visibility goals, and provide adequate 

documentation to member agencies so that the states/tribes/local agencies can develop the 

regional haze State/Tribal Implementation Plans (SIP/TIP). Figure 1.5-1 shows the eighteen 

(18) mandatory Class I Federal areas in the VISTAS Region, where visibility is an important 

value. Table 1.5-1 lists these Class I areas. Mississippi is on the western Boundary of VISTAS. 

Two of the three closest Class I areas are in the Central Regional Air Planning Organization 

(CENRAP). In the technical analysis VISTAS considered these areas. Mississippi has also 

attended CENRAP meetings and been in consultation with Louisiana. 
 7 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Figure 1.5-1. Class I Areas in the VISTAS Region and Neighboring States. 
 8 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Mandatory Class I Federal Areas in the VISTAS Region and 

Neighboring States where Visibility is an Important Value 

Regulation Citation and 

State 

Area Name Acreage Federal 

Land 

Manager 

40 CFR §81.401 Alabama Sipsey Wilderness 24,922 USDA-FS 

Chassahowitzka Wilderness 23,360 USDIFWS 

Everglades National Park 1,397,42

9 

USDI-NPS 

40 CFR §81.407 Florida 

St. Marks Wilderness 17,745 USDIFWS 

Cohotta Wilderness 36,977 USDA-FS 

Okefenokee Wilderness 343,850 USDIFWS 

40 CFR §81.408 Georgia 

Wolf Island Wilderness 5,126 USDIFWS 

40 CFR §81.411 Kentucky Mammoth Cave National Park 51,303 USDI-NPS 

Great Smoky Mountains National Park 273,551 USDI-NPS 

Joyce Kilmer-Slickrock Wilderness 17,394 USDA-FS 

Linville Gorge Wilderness 12,002 USDA-FS 

Shining Rock Wilderness 18,483 USDA-FS 

40 CFR §81.422 North 

Carolina 

Swanquarter Wilderness 9,000 USDIFWS 

40 CFR §81.426 South 

Carolina 

Cape Romain Wilderness 28,000 USDIFWS 

Great Smoky Mountains National Park 40 CFR §81.428 Tennessee 241,207 USDI-NPS 

Joyce Kilmer-Slickrock Wilderness 17,394 USDA-FS 

40 CFR §81.433 Virginia James River Face Wilderness 8,886 USDA-FS 

Shenandoah National Park 190,535 USDI-NPS 

40 CFR §81.435 West Dolly Sods Wilderness 10,215 USDA-FS 

Virginia Otter Creek Wilderness 20,000 USDA-FS 

40 CFR §81.412 Louisiana Breton National Wildlife Refuge 

(CENRAP) 

5,000 USDIFWS 

40 CFR §81.404 Arkansas Caney Creek Wilderness (CENRAP) 14,460 USDA-FS 

Upper Buffalo Wilderness (CENRAP) 12,035 USDA-FS 

Table 1.5-1. Mandatory Class I Federal Areas in the VISTAS Region and nearby where 

Visibility is an Important Value. 
 9 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

A technical support document for the regional haze state implementation plans (Appendix G) 

was prepared cooperatively by VISTAS staff and states to characterize regional haze in the 

southeastern United States. The report includes a review of the science and situation, calculation 

of initial baseline visibility, review of monitoring data/data gaps, and recommendations for 

additional monitoring, initial emission inventory characterization and projections, and 

compliance with existing control programs. Source contributions to VISTAS and nearby 

mandatory Class I Federal areas are also assessed. 

2.0 ASSESSMENT OF BASELINE AND CURRENT CONDITIONS AND 

ESTIMATE OF NATURAL BACKGROUND CONDITIONS IN CLASS I 

AREAS 

The responsibility to assess the baseline and current conditions, determine natural background 

and the glidepath falls to the states that the Class I areas are within. Since there are no Class I 

areas in Mississippi, these items will not addressed. 

3.0 GLIDEPATHS TO NATURAL CONDITIONS 

The responsibility to assess the baseline and current conditions and determine natural 

background falls to the states that the Class I areas are within. Since there are no Class I areas in 

Mississippi, these items will not addressed. 

4.0 EMISSION INVENTORY IMPROVEMENTS 

4.1 Baseline Emissions Inventory 

The Regional Haze Rule at 51.308(d) (4) (v) requires a statewide emissions inventory of 

pollutants that are reasonably anticipated to cause or contribute to visibility impairment in any 

mandatory Class I area. An inventory was developed for the baseline year 2002 and projected 

to 2009 and 2018. The pollutants inventoried include volatile organic compounds (VOC), 

nitrogen oxides (NOx), fine particulate (PM2.5), coarse particulate (PM10), ammonia (NH4) and 

sulfur dioxide (SO2). The baseline emissions inventory for 2002 was developed for MS 

following the methods described in Appendix D. 

There are five different emission inventory source classifications: stationary point, stationary 

area, off-road mobile, on-road mobile, and biogenic sources. Stationary point sources are those 

sources that emit greater than 100 tons per year of any criteria pollutant, with data provided at 

the facility level. Electric generating utilities and industrial sources are the major categories for 

stationary point sources. Stationary area sources are those sources whose individual emissions 

are relatively small, but due to the large number of these sources, the collective emissions from 
 10 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

the source category could be significant (i.e., dry cleaners, service stations, agricultural sources, 

fire emissions, etc.). These types of emissions are estimated on a countywide level. Non-road 

(or off-road) mobile sources are equipment that can move but do not use the roadways, i.e., lawn 

mowers, construction equipment, railroad locomotives, aircraft, etc. The emissions from these 

sources, like stationary area sources, are estimated on a countywide level. On-road mobile 

sources are automobiles, trucks, and motorcycles that use the roadway system. The emissions 

from these sources are estimated by vehicle type and road type and are summed to the 

countywide level. Biogenic sources are the natural sources like trees, crops, grasses and natural 

decay of plants. The emissions from these sources are estimated on a countywide level. 

In addition to the various source classifications, there are also various types of emission 

inventories. The first is the actual base year inventory. This inventory is the base year emissions 

that correspond to the meteorological data used, which for this modeling effort is data from 

2002. These emissions are used for evaluating the air quality model performance. 

The second type of inventory is the typical base year inventory. This inventory is similar to the 

actual base year inventory, except that for sources whose emissions change significantly from 

year to year, a more typical emission value is used. In this modeling effort, typical emissions 

were developed for the electric generating units (EGUs) and the wildland fire emissions. The air 

quality modeling runs using the typical base year inventory provide results which are then used 

to calculate relative reduction factors for future years. These relative reduction factors for future 

years are then used to demonstrate reasonable progress toward visibility goals. 

Below is an overview of the inventories used for each source classification. More detailed 

discussion of the emissions inventory development is contained in Appendix D. 

4.1.1 Stationary Point Sources 

Point source emissions are emissions from individual sources having a fixed location. Generally, 

these sources must have permits to operate, and their emissions are inventoried on a regular 

schedule. Large sources emitting at least 100 tons per year (tpy) of a criteria pollutant, 10 tpy of 

a single hazardous air pollutant (HAP), or 25 tpy total HAP are inventoried annually. Smaller 

sources have been inventoried less frequently. The point source emissions data can be grouped 

as EGU sources and other industrial point sources, also called non-EGUs. 

Electric Generating Units

The actual base year inventory for the EGU sources used 2002 continuous emissions monitoring 

(CEM) data reported to the USEPA’s Acid Rain program or 2002 hourly emissions data 

provided by stakeholders. These data provide hourly emissions profiles for SO2 and NOx that can 

be used in air quality modeling. Emissions profiles are used to estimate emissions of other 

pollutants (volatile organic compounds, carbon monoxide, ammonia, fine particles, soil) based 

on measured emissions of SO2 and NOx. 

Emissions from EGU vary daily and seasonally as a function of variability in energy demand and 

utilization and outage schedules. To avoid anomalies in future year emissions created by relying 

on 2002 operations to represent future operations, a typical base year emissions inventory was 
 11 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

developed for EGUs. This approach is consistent with the USEPA’s modeling guidance. To 

develop a typical year 2002 emissions inventory for EGU sources, each unit’s average CEM heat 

input for 2000 through 2004 was divided by the 2002 actual heat input to generate a unit specific 

normalizing factor. This normalizing factor was then multiplied by the 2002 actual emissions. 

The heat inputs for the period 2000 through 2004 were used because the modeling current design 

values use monitored data from this same 5-year period. If a unit was shut down for an entire 

year during the 2000 through 2004 period, the average of the years the unit was operational was 

used. If a unit was shut down in 2002, but not permanently shutdown, the emissions and heat 

inputs from 2001 (or 2000) were used in the normalizing calculations. 

As part of the VISTAS air quality modeling, VISTAS, in cooperation with the other eastern 

RPOs, contracted with ICF Resources, L.L.C., to generate future year emission inventories for 

the electric generating sector of the contiguous United States using the Integrated Planning 

Model (IPM), Version 2.1.9. IPM is a dynamic linear optimization model that can be used to 

examine air pollution control policies for various pollutants throughout the contiguous United 

States for the entire electric power system. The dynamic nature of IPM enables projection of the 

behavior of the power system over a specified future period. Optimization logic in IPM 

determines the least-cost means of meeting electric generation and capacity requirements while 

complying with specified constraints including air pollution regulations, transmission 

bottlenecks, and plant-specific operational constraints. The versatility of IPM allows users to 

specify which constraints to exercise, and to populate IPM with their own datasets. 

The IPM modeling runs took into consideration CAIR implementation, resulting in future 

reduction of NOx and SO2 air emissions for several EGUs in Mississippi. The IPM model 

predicted the shut down of several gas/oil-fired EGU sources; however, those sources have no 

closure intentions. Therefore, these sources were re-integrated into the IPM model using 2002 

emission inventory data. 

Other Industrial Point Sources

For the non-EGU sources, the same inventory is used for both the actual and typical base year 

emissions inventories. The non-EGU category uses annual emissions as reported under the 

Consolidated Emissions Reporting Rule (CERR) for the year 2002. These emissions are 

temporally allocated to month, day, and hour using source category code (SCC)-based allocation 

factors. 

The general approach for assembling future year data was to use recently updated growth and 

control data consistent with USEPA’s CAIR analyses. This data was supplemented with statespecific growth factors and stakeholder input on growth assumptions. 

4.1.2 Stationary Area Sources 

Stationary area sources are sources whose individual emissions are relatively small, but due to 

the large number of these sources, the collective emissions could be significant (i.e., combustion 

of fuels for heating, structure fires, service stations, etc.). Emissions are estimated by 

multiplying an emission factor by some known indicator of collective activity, such as fuel 
 12 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

usage, number of households, or population. Stationary area source emissions are estimated at 

the countywide level. 

The actual base year inventory will serve as the typical base year inventory for all area source 

categories except for wildland fires. For wildland fires, a typical year inventory was used to 

avoid anomalies in wildfire activity in 2002 compared to longer term averages. Development of 

a typical year fire inventory provided the capability of using a comparable data set for both the 

base year and future years. Thus, fire emissions remain the same for air quality modeling in both 

the base and any future years. The VISTAS Fire Special Interest Work Group used State records 

to ratio the number of acres burned over a longer term period (three or more years, as available 

from state records) to 2002. Based on these ratios, the 2002 acreage was then scaled up or down 

to develop a typical year inventory. 

Future year emissions 

The VISTAS contractor generated future year emissions inventories for 2009 and 2018 for the 

regional haze modeling. Growth factors, supplied either by states or taken from the CAIR 

emission projections, were applied to project the controlled emissions to 2018. If no growth 

factor was available from either a state or the CAIR growth factor files, then the USEPA’s 

Economic Growth and Analysis System Version 5 growth factors were used. 

4.1.3 Off-Road Mobile Sources 

Off-road (or non-road) mobile sources are equipment that can move but do not use the roadways, 

such as construction equipment, aircraft, railroad locomotives, lawn and garden equipment, etc. 

For the majority of the non-road mobile sources, the emissions for 2002 were estimated using the 

USEPA’s NONROAD2005c model. For the three source categories not included in the 

NONROAD model, i.e., aircraft engines, railroad locomotives and commercial marine, more 

traditional methods of estimating the emissions were used. The same inventory is used for both 

the actual and typical base year emissions inventories. 

For the source categories estimated using the USEPA’s NONROAD model, the model growth 

assumptions were used to create the 2009 and 2018 future year inventories. The NONROAD 

model takes into consideration regulations affecting emissions from these source categories. For 

the commercial marine, railroad locomotives and the remaining airport emissions, the VISTAS 

contractor calculated the future growth in emissions using detailed inventory data (both before 

and after controls) for 1996 and 2010, obtained from the CAIR Technical Support Document. 

When available, state-specific growth factors were used. 

4.1.4 Highway Mobile Sources 

For onroad vehicles, the newest version of the MOBILE model, MOBILE6.2, was used. Key 

inputs for MOBILE include information on the age of vehicles on the roads, the average speeds 

on the roads, the mix of vehicles on the roads, any programs in place in an area to reduce 

emissions for motor vehicles (e.g., emissions inspection programs), and temperature. 
 13 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

The MOBILE model takes into consideration regulations that affect emissions from this source 

sector. The same MOBILE run is used to represent the actual and typical year emissions for 

onroad vehicles using input data reflective of 2002. The MOBILE model then is run for 2018 

inventory using input data reflective of that year. The 2002 vehicle miles traveled (VMT) and 

vehicle mix data were obtained from the Mississippi Department of Transportation (MDOT). 

4.1.5 Biogenic Emission Sources 

Biogenic emissions were prepared with the SMOKE-BEIS3 (Biogenic Emission Inventory 

System 3 version 0.9) preprocessor. SMOKE-BEIS3 is a modified version of the Urban Airshed 

Model (UAM)-BEIS3 model. Modifications include use of MM5 data, gridded land use data, 

and improved emissions characterization. The emission factors that are used in SMOKE-BEIS3 

are the same as the emission factors as in UAM-BEIS3. The basis for the gridded land use data 

used by BEIS3 is the county land use data in the Biogenic Emissions Landcover Database 

version 3 (BELD3) provided by the USEPA. A separate land classification scheme, based upon 

satellite (AVHRR, 1 km spatial resolution) and census information, aided in defining the forest, 

agriculture and urban portions of each county. 

4.1.6 Summary of the Final 2002 (October 2007 version) Baseline Emissions Inventory

Below is a summary of the 2002 baseline emission inventory for Mississippi. The complete 

inventory and discussion of the methodology is contained in Appendix D. The emissions 

summaries for other VISTAS states can also be found in Appendix D. 

 VOC NOx PM2.5 PM10 NH3 SO2

Point 43,852 104,661 11,044 21,106 1,359 103,389 

Area 131,808 4,200 50,401 343,377 58,721 771 

On-Road Mobile 86,811 110,672 2,089 2,828 3,549 4,566 

Non-Road Mobile 41,081 88,787 4,690 5,010 23 11,315 

Biogenics 1,544,646 20,305 0 0 0 0 

TOTAL 1,848,199 328,626 68,223 372,321 63,652 120,040 

Table 4.1. 2002 Emissions Inventory Summary for MS in tons. 
 14 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

4.1.7 Emissions Inventory Improvements 

Since the initial model performance evaluation, VISTAS has made several improvements to the 

emissions inventory which in turn improves model performance. These inventory improvements 

are detailed in the VISTAS emissions inventory report and Appendix D, and are summarized 

here: 

• For electric generating utilities, the Integrated Planning Model (IPM) was used to provide 

estimates of future year utility production and emissions. Continuous Emissions 

Monitoring data was used to define seasonal variability in production and emissions. For 

Base G2 emissions, states updated IPM model projections from 2005 with control data 

provided by utility companies in 2006 through winter 2007. 

• For on-road vehicle emissions, states and local agencies provided updated MOBILE 

model input and vehicle-miles-traveled data. 

• For ammonia emissions from agricultural sources, the Carnegie Mellon University 

ammonia model was used to improve annual and monthly estimates. 

• For fires, the VISTAS states provided fire activity data for 2002 for wildfires, prescribed 

fire, land clearing and agricultural burning and MACTEC developed a 2002 fire 

inventory. Where data allowed, Alpine Geophysics modeled fire events as point sources. 

In 2006,United States Forest Service and Fish and Wildlife Service provided projections 

of increased prescribed burning in 2009 and 2018; these data were incorporated in the 

Base G inventory for all states except Florida. 

• For non-road engines, the updated USEPA NONROAD2005 emissions model was used 

in Base G. 

• For commercial marine emissions in shipping lanes in the Gulf of Mexico and Atlantic 

Oceans, ENVIRON created gridded emissions for the VISTAS modeling domain using 

inventory data newly developed for USEPA by Corbett at University of Delaware. These 

emissions were incorporated in the Base G modeling. 

• Updated inventories from the neighboring RPOs, Mexico, and Canada were incorporated 

as available. 
 15 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

4.2 Assessment of Relative Contributions from Specific Pollutants and 

Sources Categories 

Ammonium sulfate is the largest contributor to visibility impairment for Class I in the 

southeastern United States, and reduction of SO2 emissions would be the most effective means of 

reducing ammonium sulfate. As illustrated in Figure 4.2-1, ninety-six (96) percent of SO2

emissions in the VISTAS states are attributable to electric generating facilities and industrial 

point sources. As shown in Table 4.1, eight-six (86) percent of SO2 emissions in Mississippi are 

attributable to electric generating facilities and industrial point sources. 

Figure 4.2-1. SO2 emissions in 2002 in the VISTAS States. 

VISTAS States SO2 Emissions - 2002 

Utilities

Industrial

On road

Non road

Other

Industrial: 20% Utilities: 76%

4.8 Million tons

VISTAS States SO2 Emissions - 2002 

Utilities

Industrial

On road

Non road

Other

Industrial: 20% Utilities: 76%

4.8 Million tons
 16 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

5.0 REGIONAL HAZE MODELING METHODS AND INPUTS 

Modeling for regional haze was performed by VISTAS for the ten southeastern states, including 

Mississippi. The sections below outline the methods and inputs used by VISTAS for the 

regional modeling. Additional details are provided in Appendices C. 

5.1 Analysis Method 

The modeling analysis is a complex technical evaluation that begins by selection of the modeling 

system. VISTAS decided to use the following modeling system: 

• Meteorological Model: The Pennsylvania State University/National Center for 

Atmospheric Research (PSU/NCAR) Mesoscale Meteorological Model (MM5) is a 

nonhydrostatic, prognostic meteorological model routinely used for urban- and regionalscale photochemical, fine particulate matter, and regional haze regulatory modeling 

studies. 

• Emissions Model: The Sparse Matrix Operator Kernel Emissions (SMOKE) modeling 

system is an emissions modeling system that generates hourly gridded speciated emission 

inputs of mobile, nonroad mobile, area, point, fire and biogenic emission sources for 

photochemical grid models. 

• Air Quality Model: USEPA’s Models-3/ Community Multiscale Air Quality (CMAQ), 

version 4.51 with SOAmods enhancement, modeling system is an ‘One-Atmosphere’ 

photochemical grid model capable of addressing ozone, particulate matter (PM), visibility 

and acid deposition at regional scale for periods up to one year. 

The USEPA Modeling Guidance recommends modeling an entire year or at a minimum several 

days in each quarter of a year to adequately represent the range of meteorological conditions that 

contribute to elevated levels of fine particulate matter. The year 2002 was selected by VISTAS 

as the modeling year for this demonstration. Meteorological inputs were developed for 2002 

using the meteorological model. Emission inventories were also developed for 2002 and 

processed through the emissions model. These inputs were used in the air quality model to 

predict fine particle mass and visibility. The model results for 2002 were compared with 

observed meteorological and air quality data to evaluate model performance. Several 

configurations of the meteorological and air quality model were evaluated to select a 

configuration that gave the best overall performance for the VISTAS region. 

Once model performance was deemed adequate, the current and future year emissions were 

processed through the emissions model. The air quality modeling results are used to determine a 

relative reduction in future visibility impairment, which is used to determine reasonable progress. 

The complete modeling protocol used for this analysis can be found in Appendix C. 
 17 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

5.2 Model Selection 

To ensure that a modeling study is defensible, care must be taken in the selection of the models 

to be used. The models selected must be scientifically appropriate for the intended application 

and be freely accessible to all stakeholders. Scientifically appropriate means that the models 

address important physical and chemical phenomena in sufficient detail, using peer-reviewed 

methods. Freely accessible means that model formulations and coding are freely available for 

review and that the models are available to stakeholders, and their consultants, for execution and 

verification at no or low cost. 

The following sections outline the criteria for selecting a modeling system that is both defensible 

and capable of meeting the study's goals. These criteria were used in selecting the modeling 

system used for this modeling demonstration. 

5.2.1 Selection of Photochemical Grid Model 

Criteria

For a photochemical grid model to qualify as a candidate for use in a regional haze SIP, a State 

needs to show that it meets the same several general criteria as a model for an attainment 

demonstration for a national ambient air quality standard (NAAQS): 

• The model has received a scientific peer review 

• The model can be demonstrated applicable to the problem on a theoretical basis 

• Data bases needed to perform the analysis are available and adequate 

• Available past appropriate performance evaluations have shown the model is not biased 

toward underestimates or overestimates 

• A protocol on methods and procedures to be followed has been established 

• The developer of the model must be willing to make the source code available to users 

for free or for a reasonable cost, and the model cannot otherwise be proprietary. 

Overview of CMAQ

The photochemical model selected for this study was CMAQ version 4.5. For more than a 

decade, the USEPA has been developing the Models-3 CMAQ modeling system with the 

overarching aim of producing a ‘One-Atmosphere’ air quality modeling system capable of 

addressing ozone, fine particulate matter, visibility and acid deposition within a common 

platform. The original justification for the Models-3 development emerged from the challenges 

posed by the 1990 CAAA and the USEPA’s desire to develop an advanced modeling framework 

for ‘holistic’ environmental modeling utilizing state-of-science representations of atmospheric 

processes in a high performance computing environment. The USEPA completed the initial 

stage of development with Models-3 and released the CMAQ model in mid-1999 as the initial 
 18 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

operating science model under the Models-3 framework. The most recent rendition is CMAQ 

version 4.5, which was released in September 2005. 

An advantage of choosing CMAQ as the atmospheric model is the ability to do one-atmospheric 

modeling. The same model configuration is being applied for the ozone and PM2.5 attainment 

demonstrations SIPs, as well as the regional haze SIP. A number of features in CMAQ’s 

theoretical formulation and technical implementation make the model well suited for annual PM 

modeling. 

VISTAS used Version 4.51 of the Community Multi-scale Air Quality (CMAQ) modeling 

system with an enhanced secondary organic aerosol (SOA) module (SOAmods). Initial CMAQ 

2002 simulations performed by VISTAS found that the model greatlyunderestimate Organic 

Mass Carbon (OMC) concentrations, especially in the summer (Morris et al., 2004b). A review 

of the CMAQ formulation found that it failed to treat Secondary Organic Aerosol (SOA) 

formation from sesquiterpenes and isoprene and also failed to account for polymerization of 

SOA so that it is no longer volatile and stays in the particle form. The standard versions of 

CMAQ V4.51 assume that SOA is volatile so that once an aerosol is formed it can evaporate 

from particle to gaseous form depending on atmospheric conditions (e.g., temperature and 

humidity). After a detailed literature review, VISTAS updated the CMAQ SOA module to 

include these missing processes and found that the updated CMAQ V4.5 SOAmods produced 

much better OMC model performance in the summer (Morris et al., 2006c). 

The configuration used for this modeling demonstration, as well as a more detailed description of 

the CMAQ model, can be found in Section 1.3.3.3 of the Technical Support Document 

(Appendix G). 

5.2.2 Selection of Meteorological Model 

Criteria

Meteorological models, either through objective, diagnostic, or prognostic analysis, extend 

available information about the state of the atmosphere to the grid upon which photochemical 

grid modeling is to be carried out. The criteria for selecting a meteorological model are based on 

both the models ability to accurately replicate important meteorological phenomena in the region 

of study, and the model's ability to interface with the rest of the modeling systems -- particularly 

the photochemical grid model. With these issues in mind, the following criteria were established 

for the meteorological model to be used in this study: 

• Non-Hydrostatic Formulation 

• Reasonably current, peer reviewed formulation 

• Simulates Cloud Physics 

• Publicly available on no or low cost 

• Output available in I/O API format 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

• Supports Four Dimensional Data Assimilation (FDDA) 

• Enhanced treatment of Planetary Boundary Layer heights for AQ modeling 

Overview of MM5

The non-hydrostatic MM5 model is a three-dimensional, limited-area, primitive equation, 

prognostic model that has been used widely in regional air quality model applications. The basic 

model has been under continuous development, improvement, testing and open peer-review for 

more than 20 years and has been used worldwide by hundreds of scientists for a variety of 

mesoscale studies. 

MM5 uses a terrain-following non-dimensionalized pressure, or "sigma", vertical coordinate 

similar to that used in many operational and research models. In the non-hydrostatic MM5, the 

sigma levels are defined according to the initial hydrostatically-balanced reference state so that 

the sigma levels are also time-invariant. The gridded meteorological fields produced by MM5 

are directly compatible with the input requirements of ‘one atmosphere’ air-quality models using 

this coordinate. MM5 fields can be easily used in other regional air quality models with different 

coordinate systems by performing a vertical interpolation, followed by a mass-conservation readjustment. 

Distinct planetary boundary layer (PBL) parameterizations are available for air-quality 

applications, both of which represent sub-grid-scale turbulent fluxes of heat, moisture and 

momentum. One scheme uses a first-order eddy diffusivity formulation for stable and neutral 

environments and a modified first-order scheme for unstable regimes. The other scheme uses a 

prognostic equation for the second-order turbulent kinetic energy, while diagnosing the other key 

boundary layer terms. 

Initial and lateral boundary conditions are specified for real-data cases from mesoscale threedimensional analyses performed at 12-hour intervals on the outermost grid mesh selected by the 

user. Surface fields are analyzed at three-hour intervals. A Cressman-based technique is used to 

analyze standard surface and radiosonde observations, using the National Meteorological 

Center's spectral analysis, as a first guess. The lateral boundary data are introduced using a 

relaxation technique applied in the outermost five rows and columns of the coarsest grid domain. 

MM5 modeling system in regulatory air quality application studies have been widely reported in 

the literature (e.g., Emery et al., 1999; Tesche et al., 2000, 2003) and many have involved 

comparisons with other prognostic models such as the Regional Atmospheric Modeling System 

(RAMS) and the Systems Application International Mesoscale Model. The MM5 enjoys a far 

richer application history in regulatory modeling studies compared with RAMS or other models. 

Furthermore, in evaluations of these models in over 60 recent regional scale air quality 

application studies since 1995, it has generally been found that the MM5 model tends to produce 

somewhat better photochemical model inputs than alternative models. 

The configuration used for this modeling demonstration, as well as a more detailed description of 

the MM5 model, can be found in the meteorological modeling protocol (Appendix E). 
 20 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

5.2.3 Selection of Emissions Processing System 

Criteria

The principal criterion for an emissions processing system is that it accurately prepares 

emissions files in a format suitable for the photochemical grid model being used. The following 

list includes clarification of this criterion and additional desirable criteria for effective use of the 

system. 

• File System Compatibility with the I/O API 

• File Portability 

• Ability to grid emissions on a Lambert Conformal projection 

• Report Capability 

• Graphical Analysis Capability 

• MOBILE6 Mobile Source Emissions 

• Biogenic Emissions Inventory System version 3 (BEIS-3) 

• Ability to process emissions for the proposed domain in a reasonable amount of time. 

• Ability to process control strategies 

• No or low cost for acquisition and maintenance 

• Expandable to support other species and mechanisms 

Overview of SMOKE

The SMOKE Emissions Processing System Prototype was originally developed at the Microcomputing Center of North Carolina. As with most ‘emissions models’, SMOKE is principally 

an emission processing system and not a true emissions modeling system in which emissions 

estimates are simulated from ‘first principles’. This means that, with the exception of mobile 

and biogenic sources, its purpose is to provide an efficient, modern tool for converting emissions 

inventory data into the formatted emission files required by an air quality simulation model. For 

mobile sources, SMOKE actually simulates emissions rates based on input mobile-source 

activity data, emission factors and outputs from transportation travel-demand models. 

 

SMOKE was originally designed to allow emissions data processing methods to utilize emergent 

high-performance-computing as applied to sparse-matrix algorithms. Indeed, SMOKE is the 

fastest emissions processing tool currently available to the air quality modeling community. The 

sparse matrix approach utilized throughout SMOKE permits both rapid and flexible processing 

of emissions data. The processing is rapid because SMOKE utilizes a series of matrix 

calculations instead of less efficient algorithms used in previous systems. The processing is 

flexible because the processing steps of temporal projection, controls, chemical speciation, 

temporal allocation, and spatial allocation have been separated into independent operations 
 21 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

wherever possible. The results from these steps are merged together at a final stage of 

processing. 

 

SMOKE contains a number of major features that make it an attractive component of the 

modeling system. The model supports a variety of input formats from other emissions 

processing systems and models. It supports both gridded and county total land use scheme for 

biogenic emissions modeling. SMOKE can accommodate emissions files from up to 10 

countries and any pollutant can be processed by the system. 

For additional information about the SMOKE model please refer to Modeling Protocol 

(Appendix C). 

5.3 Selection of the Modeling Year 

A crucial step to SIP modeling is the selection of the period of time to model to represent current 

air quality conditions and to project changes in air quality in response to changes in emissions. 

The year 2002 was selected as the base year for several reasons. 

The USEPA’s April 2007 Guidance on the use of Models and Other Analyses for Demonstrating 

Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze identifies specific goals 

to consider when selecting one or more episodes for use in demonstrating reasonable progress in 

attaining the regional haze air quality goals. The USEPA recommends that episode selection 

derive from three principal criteria: 

• Simulate a variety of meteorological conditions; 

• Model time periods in which observed concentrations are close to the appropriate baseline 

design value or visibility impairment; 

• Model periods for which extensive air quality/meteorological data bases exist; and 

• Model a sufficient number of days so that the modeled attainment test applied at each 

monitor violating the NAAQS is based on multiple days. 

For regional haze modeling, the guidance goes further by suggesting that the preferred approach 

is to model a full, representative year. Moreover, the required RRF values should be based on 

model results averaged over the 20% worst and 20% best visibility days determined for each 

Class I are based on monitoring data from the 2000 – 2004 baseline period. 

The USEPA also lists several other considerations to bear in mind when choosing potential 

regional haze episodes including: (a) choose periods which have already been modeled, (b) 

choose periods which are drawn from the years upon which the current design values are based, 

(c) include weekend days among those chosen, and (d) choose modeling periods that meet as 

many episode selection criteria as possible in the maximum number of nonattainment or Class I 

areas as possible. Finally, the USEPA explicitly recommended in its 2007 guidance to use 2002 

as the baseline inventory year. 
 22 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

VISTAS adopted a logical, stepwise approach in implementing the USEPA guidance in order to 

identify the most preferable, representative year for regional haze modeling. 

These steps include the following: 

Representativeness of Meteorological Conditions: The VISTAS meteorological 

contractor (BAMS) identified important meteorological characteristics and data sets in 

the VISTAS region directly relevant to the evaluation of candidate annual modeling 

episodes. 

Initial Episode Typing: At the time of selection in 2003, meteorological and air quality 

data were available for 2002 for model inputs and model performance evaluation. 

VISTAS used Classification and Regression Tree Analyses to evaluate visibility 

conditions for 2000, 2001, and 2002, the candidate modeling years. The year 2002 was 

found to be representative of conditions in the other two years. Subsequently, these 

analyses were repeated with the meteorological and air quality monitoring data for 2000 

to 2004 to evaluate how well the 2002 modeling year represented the full 2000-2004 

baseline period. This analysis confirmed that visbility and PM2.5 mass in 2002 were 

representative of the five-year baseline period for the VISTAS Class I areas. This 

analysis is discussed in more detail in the project report in Appendix B. 

Data Availability: In parallel with the CART analysis, episode characterization analyses, 

collaborative investigations by VISTAS states intensively studied the availability of 

PM2.5, meteorological, and emissions data and representativeness of alternative Baseline 

modeling periods from a regulatory standpoint. Additionally, 2002 was the year that 

USEPA was requiring states to provide emissions inventory data for the Comprehensive 

Emissions Reporting Rule, it made sense to use 2002 as the modeling year to take 

advantage of the 2002 inventory. 

Years to be used by other RPOs: VISTAS also considered what years other RPO would 

be modeling, and several had already chosen calendar year 2002 as the modeling year. 

After a lengthy process of integrated studies, the episode selection process culminated in the 

selection of calendar year 2002 (1 January through 31 December) as the most current, 

representative, and pragmatic choice for VISTAS regional haze modeling. All of the USEPA 

criteria for regional haze episode selection were directly considered in this process together with 

many other considerations (e.g., timing of new emissions or aerometric data deliveries by the 

USEPA or the states to the modeling teams). 

5.4 Modeling Domains 

5.4.1 Horizontal Modeling Domain 

The USEPA’s modeling guidance recommends a 12-km modeling grid resolution for PM2.5 

modeling while a 36-km grid is considered acceptable for regional haze. For the VISTAS 

modeling, a coarse 36-km grid resolution was used for modeling the entire United States and a 

finer 12-km grid was used to model the eastern United States. 
 23 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

The CMAQ model was run in one-way nested grid mode. This allowed the larger outer domains 

to feed concentration data to the inner nested domain. One-way nesting is believed to be 

appropriate for the generally stagnant conditions experienced during ozone episodes. Two-way 

nesting was not considered due to numerical and computational uncertainty associated with the 

technique. 

The horizontal coarse grid modeling domain boundaries were determined through a national 

effort to develop a common grid projection and boundary. A smaller 12-km grid, modeling 

domain was selected in an attempt to balance location of areas of interest, such as ozone and fine 

particulate matter nonattainment areas, as well as Class 1 and wilderness areas for regional haze. 

Processing time was also a factor in choosing a smaller 12-km grid, modeling domain. 

The coarse 36-km horizontal grid domain covers the continental United States. This domain was 

used as the outer grid domain for MM5 modeling with the CMAQ domain nested within the 

MM5 domain. Figure 5.4.1-1 shows the MM5 horizontal domain as the outer most, blue grid 

with the CMAQ 36-km domain nested in the MM5 domain. 

Figure 5.4.1-1. The MM5 horizontal domain is the outer most, blue grid, with the CMAQ 

36-km domain nested in the MM5 domain. 
 24 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

To achieve finer spatial resolution in the VISTAS states, a one-way nested high resolution 

(12-km grid resolution) was used. Figure 5.4.1-2 shows the 12-km grid, modeling domain for 

the VISTAS region. This is the modeling domain for which the reasonable progress goals will 

be assessed. 

Figure 5.4.1-2. A more detailed view of the 12-km grid over the VISTAS region. 

5.4.2 Vertical Modeling Domain 

The CMAQ vertical structure is primarily defined by the vertical grid used in the MM5 

modeling. The MM5 model employed a terrain following coordinate system defined by 

pressure, using 34 layers that extend from the surface to the 100 mb. A layer-averaging scheme 

was used to generate 19 vertical layers for CMAQ to reduce the computational cost of the 

CMAQ simulations. The effects of layer averaging were evaluated in conjunction with the 

VISTAS modeling effort and was found to have a relatively minor effect on the model 

performance metrics when both the 34 layer and a 19 layer CMAQ models were compared to 

ambient monitoring data. 

 
 25 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

6.0 MODEL PERFORMANCE EVALUATION 

The initial modeling effort focused on evaluating previous regional air quality modeling 

applications and testing candidate model configurations for the SMOKE emissions and CMAQ 

model for the VISTAS 36-km and 12-km modeling domains. This effort resulted in a report 

recommending the model configuration for the annual emissions and air quality modeling, which 

is included as part of the VISTAS Emissions and Air Quality Modeling Protocol. The evaluation 

of the meteorological modeling configuration can be found in Appendix F, with a summary of 

the final meteorological and air quality modeling configuration in the modeling protocol 

contained in Appendix E and Appendix C, respectively. 

Air quality model performance for the 2002 modeling year was initially tested in 2004 using an 

early version of the VISTAS emissions inventory. In keeping with the one-atmosphere objective 

of the CMAQ modeling platform, model performance was evaluated based on measured ozone, 

fine particles, and acid deposition in the Air Quality System (AQS), IMPROVE, Speciated 

Trends Network (STN), Southeastern Aerosol Research and Characterization (SEARCH), 

National Acid Deposition Program (NADP) and Clean Air Status and Trends Network 

(CASTNet) monitoring networks (Figure 6.0-1). An examination of the results is summarized in 

Appendix B. 

Figure 6.0-1. Monitoring Networks used for VISTAS 2002 model performance evaluation 

and their location within the VISTAS 12km domain. 
 26 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

6.1 Modeling Performance Goals, and Criteria 

In 2004, VISTAS established model performance goals and criteria for components of fine 

particle mass (Table 6.1-1) based on previous model performance for ozone and fine particles. 

The USEPA modeling guidance for fine particulate matter at the time noted that PM models 

might not be able to achieve the same level of performance as ozone models. VISTAS’ 

evaluation considered several statistical performance measures and displays. Fractional bias and 

mean fractional error were selected as the most appropriate metrics to summarize model 

performance; other metrics were also calculated and are included for IMPROVE monitors in the 

full model performance evaluation (Appendix F). 

Fractional Bias Mean Fractional 

Error 

Comment 

<15 percent <35 percent Goal for PM model performance based on ozone 

model performance, considered excellent performance 

<30 percent <50 percent Goal for PM model performance, considered good 

performance 

<60 percent <75 percent Criteria for PM model performance, considered 

average performance. Exceeding this level of 

performance indicates fundamental concerns with the 

modeling system and triggers diagnostic evaluation. 

Table 6.1-1. Established model performance goals and criteria for the component species of 

fine particle mass. 

Several graphic displays of model performance were prepared including: 

1. Scatter plots of predicted and observed concentrations and deposition by species, 

monitoring network, and month 

2. Time series plots of predicted and observed concentrations and deposition by species, 

monitoring site, and month 

3. Spatially average time series plots 

4. Time series plots of monthly fractional bias and error for a species, region, and network 

5. Performance goal plots (“soccer plots”) that summarize model performance by species, 

region, season 

6. Concentration performance plots (“bugle plots”) that display fractional bias or error as a 

function of concentration by species, region, monitoring network, and month 

The “soccer plots” and “bugle plots” are relatively new tools in model performance evaluations, 

and have recently been included as model performance evaluation displays in the USEPA’s 

modeling guidance for Ozone, PM2.5, and Regional Haze (2007). Both “soccer plots” and 

“bugle plots” allow for convenient way to examine model performance with respect to set goals 

and criteria. The bugle plots have the added benefit of adjusting the goals and criteria to 

consider the concentration of the species. Analysis of “bugle plots” generally suggests that 

greater emphasis should be placed on performance of those components with the greatest 

contribution to PM mass and visibility impairment (e.g. sulfate and organic carbon) and that 
 27 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

greater bias and error could be accepted for components with smaller contributions to total PM 

mass (e.g. elemental carbon, nitrate, and soil). 

6.2 VISTAS Domain-Wide Performance 

Further discussion of model performance in this document will focus on the comparison of 

observational data from the IMPROVE monitors and model output data from the 2002 VISTAS 

BaseG2-Actual annual air quality modeling. Focus is limited to the IMPROVE monitoring 

network as these sites are the locations used in projecting attainment visibility improvement 

goals in the Class I areas. 

The evaluation will primarily focus on the air quality model’s performance with respect to 

individual components of fine particulate matter (PM2.5), as good model performance of the 

component species will dictate good model performance of total or reconstituted fine particulate 

matter. Model performance of the total fine particulate matter and the resulting total light 

extinction will also be provided as a means to discuss the overall model performance for this 

Implementation Plan. 

In our analyses, mean fractional bias (error) is used in lieu of mean bias (error), to prevent low 

observations and model predictions from skewing the metrics. A full list of model performance 

statistics is found in Appendix G. The soccer and bugle plots for the all of the VISTAS 

IMPROVE monitors are included here for summary purposes. Plots have been developed for the 

average monthly concentrations and the performance statistics for all of the most significant light 

scattering component species (Sulfate, Nitrate, and Organic Carbon) for the 20% best days and 

20% worst days. 

The soccer plots of monthly concentrations (Figures. 6.2-1 and 6.2-2) show that values for 

nitrate generally fall outside of criteria performance thresholds. Sulfates and organic carbon 

generally fall within goal thresholds, with a couple of months falling just outside the goal 

thresholds but well within the criteria thresholds. Figure 6.2-3 contains separate soccer plots for 

each season. The seasonal plots emphasize poorer nitrate performance in the summer (does not 

even appear on the plots provided because performance is off scale with other constituents), 

when observed nitrate is quite low and predicted nitrate is even lower. When concentration is 

factored into performance criteria, nitrate performance improves with respect to MFB and MFE 

(Figures 6.2-4 and 6.2-5). 

Additionally, performance assessed at the “one atmosphere” level was also deemed acceptable 

for ozone and particulate matter at various monitoring sites (STN, FRM, CASTNet, etc.). 

Overall, VISTAS found the Base G2 modeling results to be representative and acceptable for use 

in modeling projection for ozone, particulate matter, and regional haze.
 28 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Figure 6.2-1. Soccer plot depicting both the mean fractional error and fractional bias for 

component concentration for all VISTAS sites based on Base G2 results. Each point 

represents a monthly value as compared to the model performance criteria (red box) and 

modeling performance goals (green box). 

Figure 6.2-2. A zoomed view of the soccer plot depicting both the mean fractional error and 

fractional bias for component concentration for all VISTAS sites based on Base G2 results. 

Each point represents a monthly value as compared to the model performance criteria (red 

box) and modeling performance goals (green box). 
 29 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Figure 6.2-3. Seasonal soccer plots based on Base G1 results for all VISTAS IMPROVE 

monitors. 
 30 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Figure 6.2-4. Bugle plot of the mean fraction bias for particulate matter and its component 

concentrations for all VISTAS sites based on Base G2 results. Each point represents a 

monthly mean fraction bias value as compared to the model performance criteria (red 

lines) and modeling performance goals (green lines). 

Figure 6.2-5. Bugle plot of mean fraction error for particulate matter and its component 

species for all VISTAS sites based on Base G2 results. Each point represents a monthly 

mean fraction bias value as compared to the model performance criteria (red lines) and 

modeling performance goals (green lines). 
 31 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

6.3 Performance in Nearby Class 1 Areas 

The following section provides stack bar charts (Figures 6.3.1 and 6.3.2) for closest Class 1 

areas, Breton and Sipsey, comparing observed fine particulate matter composition and modeled 

fine particulate matter composition for the 20% worst days. 

The stacked bar chart allows a side by side comparison of each day’s observed and modeled 

compositional and total light extinction. Within each bar the color codes are: 

• Yellow = light extinction due to sulfates (bextSO4) 

• Red = light extinction due to nitrates (bextNO3) 

• Green = light extinction due to organic carbon (bextOC) 

• Black = light extinction due to elemental (bextEC) 

• Brown = light extinction due to soil (bextSoil) 

• Grey = light extinction due to coarse mass (bextCM) 

The components are presented in the same order for both the observed (left hand bar) and 

modeled bar (right hand bar), so it easy to identify days when the predicted light extinction for 

the component differs from the observed. The total height of the bar provides the total 

reconstructed particulate matter light extinction value. 

Overall, model performance is good. Both the modeled and observed values demonstrate that 

sulfates are the largest contributor to visibility impairment. The model does significantly 

underestimate the observed values on a number of days. Since Breton is near the southern 

boundary of the modeling domain, there is significant uncertainty when the winds are from a 

southerly direction. This also indicates that Breton may experience significant influence from 

international emissions that are difficult to quantify or control. 

Section 3.5 of the Technical Support Document found in Appendix G discusses the model 

performance in the various Class 1 areas more completely. 
 32 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Figure 6.3.1 Model Performance 20% Haziest Days in 2002 - Breton, LA 

Observations (left) vs Modeled Base G2a (right) 

Figure 6.3.2 Model Performance 20% Haziest Days in 2002 - Sispey, AL

Observations (left) vs Modeled Base G2a (right) 

0

20

40

60

80

100

120

140

160

180

44 47 74 125 143 179 194 197 200 206 215 239 248 251 254 257 260 263 272 281 284 287 305 311 _ Avg

Julian Day in Worst 20% group

bEXT (1/Mm)

bCM

bSOIL

bEC

bOC

bNO3

bSO4

0

50

100

150

200

250

300

350

80 122 131 143 152 155 161 185 188 191 215 218 221 224 251 254 260 263 284 296 338 341 _ _ _ Avg

Julian Day in Worst 20% group

bEXT (1/Mm)

bCM

bSOIL

bEC

bOC

bNO3

bSO4
 33 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

7.0 LONG-TERM STRATEGY FOR CLASS I AREAS THAT ARE NEAR 

MISSISSIPPI 

As stated in section 1.3 above, the regional haze rule requires States to establish reasonable 

progress goals, expressed in deciviews, for visibility improvement at each affected Class I area 

covering each (approximately) 10-year period until 2064. This first set of reasonable progress 

goals must be met through measures contained in the state’s long-term strategy covering the 

period from the baseline until 2018. This section discusses development of Mississippi’s longterm strategy. 

7.1 Overview of the Long-Term Strategy Development Process 

The monitored data and modeling analyses cited in sections 2 and 5 above establish that for the 

VISTAS region, the key contributors to regional haze in the 2000-2004 baseline timeframe were 

large stationary sources of sulfur dioxide emissions. Keeping that key conclusion in mind, this 

section addresses the following questions: 

a. Assuming implementation of existing federal and state air regulatory requirements in 

Mississippi and the VISTAS region, how much visibility improvement, compared to 

the glidepath, would MDEQ expect to see at Class I areas near Mississippi between 

now and 2018? 

b. What additional emission controls represent BART in Mississippi? 

c. What pollutants and source categories would the greatest visibility benefits be 

realized between the baseline and 2018? 

d. In what geographic locations are the emissions which have the greatest impact on 

visibility in specific Class I areas? 

e. What types of emissions sources does MDEQ find in those geographic locations? 

f. Which specific individual sources in those geographic locations have the greatest 

visibility impacts at a given Class I area? 

g. What additional emission controls represent reasonable progress for those specific 

sources? 
 34 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

7.2 Expected Visibility Results in 2018 for Class I Areas Neighboring 

Mississippi under existing and planned emissions controls (Base G2 

Inventory) 

There are significant emissions control programs being implemented between the baseline period 

and 2018. These programs are described in more detail below. 

PURPOSE 

The purpose of the section is to outline the State’s strategy for complying with the Long-term 

Strategy requirements of our Regional Haze SIP under 40 CFR 51.308(d)(3), and the 

requirements for establishing best available retrofit technology (BART) controls under 40 CFR 

51.308(e). 

The MDEQ long term strategy contains the following components: 

I. Inventory of all controls required or expected under all federal and state regulations 

by 2009 and 2018. 

II. Discussion of emissions sensitivity model runs to help determine which pollutants 

and source categories are contributing the most to visibility impairment at Class I 

areas (runs conducted by Georgia Institute of Technology). 

III. Examination of SO2 Area of Influence (AOIs) projections for neighboring Class I 

areas to determine which specific sources are most likely to be impairing visibility at 

specific Class I areas. 

IV. Using the results of the four factor analyses, identification of control determinations 

for specific sources. 

V. Identification of BART-eligible sources. 

VI. BART exemption modeling for BART-eligible sources. 

VII. BART determinations for sources subject to BART. 

VIII. Modeling demonstration of visibility improvement after inclusion of BART and 

reasonable progress control determinations. 

7.2.1 Emission Controls Modeled and Requirements 

CAIR. Utility projections are based on the Integrated Planning Model® (IPM®). CAIR will 

permanently cap emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) in the eastern 

United States. CAIR achieves large reductions of SO2 and/or NOx emissions across 28 eastern 

states and the District of Columbia. When fully implemented, CAIR will reduce SO2 emissions 

in these states by over seventy (70) percent and NOx emissions by over sixty (60) percent from 

2003 levels. 

 

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. Those states affected by the 

NOx SIP call in the VISTAS region have developed rules for the control of NOx emissions that 
 35 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

have been approved by the USEPA. The NOx SIP Call has resulted in a sixty-eight (68) percent 

reduction in NOx emissions from large stationary combustion sources. For this analysis, the 

emissions for NOx SIP call-affected sources were capped at 2007 levels, and carried forward the 

capped levels for the 2009 and 2018 future year inventories. Mississippi was not subject to the 

NOx SIP call; however, states north and east of Mississippi are subject and the resulting emission 

reductions should improve conditions at Class I areas throughout the Southeast. 

Consent Agreements (Tampa Electric Company, Virginia Electric Power Company, Gulf Power 

Crist 7, Chevron Pascagoula Refinery).

• The settlement requires Tampa Electric Company (TECO) to pay a $3.5 million 

civil penalty. Under the agreement, TECO will install permanent emissionscontrol equipment to meet stringent pollution limits; implement a series of interim 

pollution-reduction measures to reduce emissions while the permanent controls 

are designed and installed; and retire pollution emission allowances that TECO or 

others could use, or sell to others, to emit additional pollution into the 

environment. The settlement also requires the company to spend between $10 and 

$11 million on environmentally beneficial projects in the region designed to 

mitigate the impact of emissions from the company's plants. 

• Virginia Electric and Power Co. (VEPCO) agreed to spend $1.2 billion between 

now and 2013 to eliminate 237,000 tons of sulfur dioxide (SO2) and nitrogen 

oxides (NOx) emissions each year from eight coal-fired electricity generating 

plants in Virginia and West Virginia. 

• The 2002 agreement calls for Gulf Power to upgrade its operation to cut nitrogen 

oxide emission rates by sixty-one (61) percent at its Crist generating plant by 

2007 with major reductions beginning in early 2005. The Crist plant is a 

significant source of nitrogen oxide emissions in the Pensacola area. 

• Under a 2005 settlement agreement, Chevron Refinery Pascagoula was required 

to significantly reduce emissions, particularly of Sulfur Dioxide and Nitrogen 

Oxides. Emissions of other pollutants will be reduced to lesser extents. The major 

emissions points with reductions are two sulfur recovery units, the FCC 

regenerator, flares, and several boilers and heaters. The Chevron consent decree 

will result in emission reductions of 2900 lbs/hr of SO2, 960 lbs/hr of NOx, and 

40 lbs/hr of PM10 with a modeled visibility improvement of 2.99dv at Breton. All 

of the reductions are to be in place by the end of 2011. Greater details of the 

consent decree and the emissions reductions can be found in the BART analysis, 

appendix L.10.

One-hour ozone SIP 

New SIPs have been submitted to the USEPA to demonstrate attainment of the one-hour 

ozone National Ambient Air Quality Standard (NAAQS) for areas in neighboring states.

One-hour ozone SIPs Atlanta (Federal Register: June 15, 2005 (Volume 70, Number 114)) / 

Birmingham (March 12, 2004 (Volume 69, Number 49))/ Northern Kentucky (Federal 

Register: September 16, 2004 (Volume 69, Number 179)). The purpose of a state 
 36 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

implementation plan (SIP) is to demonstrate attainment or maintenance of the 1-hour ozone 

National Ambient Air Quality Standard (NAAQS). States must determine which Clean Air 

Act requirements are applicable to their area and submit plans to USEPA for public comment 

and approval. 

Heavy Duty Diesel (2007) Engine Standard (for onroad trucks and buses).

USEPA set a PM emissions standard for new heavy-duty engines of 0.01 grams per brakehorsepower-hour (g/bhp-hr), to take full effect for diesels in the 2007 model year. 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. USEPA will 

require a ninety-seven (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 (Onroad vehicles). 

USEPA mobile 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, 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. 

USEPA has adopted new standards for emissions of oxides of nitrogen (NOx), hydrocarbons 

(HC), and carbon monoxide (CO) 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-terrainvehicles. 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 ninety (90) percent from 

nonroad diesel equipment, and reduce sulfur levels by ninety-nine (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. 

(http://www.epa.gov/nonroad-diesel/) 

Industrial Boiler / Process Heater / Reciprocating Internal Combustion Engines (RICE) 

Maximum Achievable Control Technology (MACT) standards. The USEPA issued final 

rules to substantially reduce emissions of toxic air pollutants from industrial, commercial and 
 37 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

institutional boilers, process heaters and stationary RICE. 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 sulfur dioxide and particulate matter in 

conjunction with the toxic air pollutant reductions. The applied MACT control efficiencies 

were four (4) percent for SO2 and forty (40) percent for PM10 and PM2.5. The USEPA’s 

industrial boiler MACT rules were vacated on June 8, 2007. However, the USEPA is 

required under the Clean Air Act to issue revised boiler MACT rules. These rules are 

scheduled to be proposed in 2009 and final in 2010. As such, it is likely that by 2018 MACT 

controls will be required for industrial boilers. Therefore, the VISTAS States decided to 

include control assumptions for industrial boilers due to MACT. 

Combustion Turbine MACT. 

The projection inventories do not include the NOx co-benefit effects of the MACT 

regulations for Gas Turbines or stationary Reciprocating Internal Combustion Engines 

(RICE), which USEPA estimates to be small compared to the overall inventory.

VOC 2-, 4-, 7-, and 10-year MACT Standards. 

Volatile Organic Chemical (VOC) 2-, 4-, 7-, and 10-year MACT Standards. The point 

source MACTs and associated emission reductions were designed from Federal Register 

(FR) notices and discussions with USEPA’s Emission Standards Division (ESD) staff. 

MDEQ did not apply reductions for MACT standards with an initial compliance date of 2001 

or earlier, assuming that the effects of these controls are already accounted for in the 2002 

inventories supplied by the States. 

7.2.2 Point Source Controls (EGU and non-EGU) 

Different approaches were used for the EGU and the non-EGU sectors of the point source 

inventory: 

• For the EGUs, the State relied primarily on the Integrated Planning Model® (IPM®) to 

project future generation as well as to calculate the impact of the future emission control 

program CAIR. The IPM results were adjusted based on state and local agency 

knowledge of planned emission controls at specific EGUs. 

• For non-EGUs, MDEQ used recently updated growth and control data consistent with the 

data used in USEPA’s CAIR analyses, and supplemented these data with available state 

and local agency input and updated fuel use forecast data for the U.S. Department of 

Energy. 

 

For both sectors, MDEQ generated 2009 and 2018 inventories for a control scenario which 

accounts for post-2002 emission reductions from promulgated and proposed federal, state, local, 

and site-specific control programs as of July 1, 2004. 
 38 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

7.2.2.1 Electric Generating Units (EGU)

State and local agencies specified a number of changes to the IPM results to better reflect current 

information on when and where future controls would occur. These changes to the IPM results 

primarily involved state and local agency addition or subtraction of future emission controls 

based on the best available data from state rules, enforcement agreements, compliance plans, 

permits, and discussions/commitments from individual companies. 

Mississippi approved the use of emissions projections from Mississippi Power for its facilities 

rather than the IPM outputs. These projections included the addition of NOx and SO2 controls at 

Plant Watson in Gulfport and Plant Daniel in Escatapwa. The Emissions for South Mississippi 

Electric Power Association were also revised to include greater SO2 control. Several of 

Entergy’s units were proposed to be shut down by the IPM. There are no plans to remove the 

units in question from operation so the emissions were put back into the inventory at 2002 

emission levels. 

The following bar charts show expected decreases in emissions of SO2 and NOx across the 

VISTAS states from 2002 through 2018. Note that for SO2 emissions in particular, which are the 

largest contributors to haze, emissions from electric generating facilities are expected to decrease 

dramatically (70 percent) between 2002 and 2018. However, even after implementation of 

CAIR, EGU emissions are projected to remain the largest contributor to haze, comprising more 

than half of remaining SO2 emissions in most states. 

7.2.2.2 Non-Electric Generating Units (Non-EGU)

The general approach for assembling future year data was to use recently updated growth and 

control data consistent with the data used in USEPA’s CAIR analyses, supplement these data 

with available stakeholder input, and provide the results for stakeholder review to ensure 

credibility.

MACTEC (MACTEC, 2006) used the same control programs for both the 2009 and 2018 nonEGU point inventory. Two control scenarios were developed: on-the-books (OTB) controls and 

on-the-way (OTW) controls. The OTB control scenario accounts for post-2002 emission 

reductions from recently promulgated federal, state, local, and site-specific control programs. 

The OTW control scenario accounts for proposed (but not final) control programs that are 

reasonably anticipated to result in post-2002 emission reductions. 

Maximum achievable control technology (MACT) requirements were also applied, as 

documented in the report entitled Control Packet Development and Data Sources, dated July 14, 

2004. The point source MACTs and associated emission reductions were designed from Federal 

Register (FR) notices and discussions with USEPA’s Emission Standards Division (ESD) staff. 

MDEQ did not apply reductions for MACT standards with an initial compliance date of 2001 or 

earlier, assuming that the effects of these controls are already accounted for in the 2002 

inventories supplied by the States. Emission reductions were applied only for MACT standards 

with an initial compliance date of 2002 or greater. 
 39 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

The final Phase II NOx SIP call rule was finalized on April 21, 2004. States had until April 21, 

2005, to submit SIPs meeting the Phase II NOx budget requirements. The Phase II rule applies to 

large internal combustion (IC) engines, which are primarily used in pipeline transmission service 

at compressor stations. MDEQ identified affected units using the same methodology as was used 

by USEPA in the proposed Phase II rule (i.e., a large IC engine is one that emitted, on average, 

more than 1 ton per day during 2002). The final rule reflects a control level of eighty-two (82) 

percent for natural gas-fired IC engines and ninety (90) percent for diesel or dual fuel categories. 

Several state and local agencies provided more specific information on the anticipated controls at 

the compressor stations. This information was used instead of the default approach used by 

USEPA in the proposed Phase II rule. 

A summary of Non-EGU point source control programs included in 2009/2018 

projection inventories include: 

• Atlanta / Northern Kentucky / Birmingham 1-hr SIPs 

• Industrial Boiler/Process Heater/RICE MACT. The applied MACT control efficiencies 

were four (4) percent for SO2 and forty (40) percent for PM10 and PM2.5 to account for 

the co-benefit from installation of acid gas scrubbers and other control equipment to 

reduce HAPs.

• NOx SIP Call (Phase I- except where States have adopted Phase II already) Phase I of the 

NOx SIP call applies to certain large non-EGUs, including large industrial boilers and 

turbines, and cement kilns. States in the VISTAS region affected by the NOx SIP call 

have developed rules for the control of NOx emissions that have been approved by 

USEPA. 

• Petroleum Refinery Initiative (October 1, 2003 notice; Mississippi & West Virginia). 

This initiative addresses the most significant Clean Air Act compliance concerns 

affecting the petroleum refinery industry. Since December 2000, 17 global refinery 

settlements have been reached with refiners representing nearly seventy-seven (77) 

percent of domestic refining capacity. Three refineries in the VISTAS region are affected 

by two October 2003 Clean Air Act settlements under the USEPA Petroleum Refinery 

Initiative. The refineries are: (1) the Chevron refinery in Pascagoula, Mississippi; (2) the 

Ergon refinery in Vicksburg, Mississippi; and (3) the Ergon refinery in Newell, West 

Virginia. The emission reductions required by the Consent decree for Chevron are 

significant and addressed to a greater degree in Appendix L.10. 

• Reasonable Further Progress three (3) percent plans where in place for one-hour ozone 

plans (Metropolitan Washington, DC, and Atlanta, Georgia). 
 40 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

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

emission reductions were designed from Federal Register (FR) notices and discussions 

with USEPA’s ESD staff. MDEQ did not apply reductions for MACT standards with an 

initial compliance date of 2001 or earlier, assuming that the effects of these controls are 

already accounted for in the 2002 inventories supplied by the States. 

• Combustion Turbine MACT. The projection inventories do not include the NOx cobenefit effects of the MACT regulations for Gas Turbines or stationary Reciprocating 

Internal Combustion Engines, which USEPA estimates to be small compared to the 

overall inventory. 

• NOx SIP Call (Phase II – remaining states & IC engines). 

For more information on the development of point source inventories, see Appendix D. 

7.2.3 Area Source Controls 

Controls (including control efficiency, rule effectiveness and rule penetration) provided by the 

States or originally developed for use in estimating projected emissions for USEPA’s Heavy 

Duty Diesel (HDD) rulemaking emission projections and used in the CAIR projections were 

used to calculate controlled emissions. 

The controls obtained by MACTEC (MACTEC, 2006) for the HDD rulemaking were controls 

for the years 2007, 2020, and 2030. Since MACTEC was preparing 2009 and 2018 projections, 

control values for intermediate years were prepared using a straight-line interpolation of control 

level between 2007 and 2020. State submitted controls had precedence over the U.S. EPA 

developed controls. For more information on the development of area source inventories, see 

Appendix D. 

7.2.4 Mobile Sources 

The assumptions used for the 2002 initial base year inventory vary across the VISTAS region, 

but our presumption is that these data accurately reflected each State’s situation as it existed in 

2002. If a State had no plans to change program requirements between 2002 and 2018, VISTAS 

proposed to maintain the 2002 program descriptions without change. However, if a State planned 

changes, information on those plans was requested and used to develop the 2018 inventory. 

For more information on the development of mobile source inventories, see Appendix D. 
 41 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

7.2.5 Non-Road 

Using the 2002 base year emissions inventory for aircraft, locomotives, and commercial marine 

vessels (CMV) prepared as described earlier in this document, corresponding emission 

projections for 2009 and 2018 were developed. Detailed inventory data (both before and after 

controls) for these same emission sources for 1996, 2010, 2015, and 2020 were obtained from 

the USEPA's CAIR Technical Support Document. Using these data, combined growth and 

control factors for the period 2002-2009 and 2002-2018 were estimated using straight-line 

interpolation between 1996 and 2010 (for 2009) and 2015 and 2020 (for 2018). This is done at 

the State-county-SCC-pollutant level of detail. According to USEPA documentation, the CAIR 

baseline emissions include the impacts of the Tier 4 (T4) non-road diesel rulemaking, which 

implements a low sulfur fuel requirement that affects both future CMV and locomotive 

emissions. For more information on the development of non-road source inventories, see 

Appendix D. 

7.2.6 Conclusion 

In conclusion of this discussion on source sector controls, Figures 7.2.6-1 and 7.2.6-2 depict 

pollutant totals for NOx and SO2 for the various sectors by state for 2002, 2009, and 2018 

modeling. Due to emissions control requirements already in place, both SO2 and NOx emissions 

will be significantly lower in 2018 than in 2002. This will result in significant visibility 

improvement in 2018 over 2002. 

Figure 7.2.6-1. Base G2 Annual SO2 emissions for 2002, 2009, and 2018 in the VISTAS 

states.

West Virginia

Alabama

Florida

Kentucky

Georgia

Mississippi

South Carolina

North Carolina

Tennessee

Virginia

100

200

300

400

500

600

700

Annual SO2 (Thousand Tons)

Miscellaneous

Nonroad

Onroad

Industrial

Other Fuel Combustion

EGU

2002

2009

2018

West Virginia

Alabama

Florida

Kentucky

Georgia

Mississippi

South Carolina

North Carolina

Tennessee

Virginia

100

200

300

400

500

600

700

Annual SO2 (Thousand Tons)

Miscellaneous

Nonroad

Onroad

Industrial

Other Fuel Combustion

EGU

2002

2009

2018

Alabama

Florida

Kentucky

Georgia

Mississippi

South Carolina

North Carolina

Tennessee

Virginia

100

200

300

400

500

600

700

Annual SO2 (Thousand Tons)

Miscellaneous

Nonroad

Onroad

Industrial

Other Fuel Combustion

EGU

Miscellaneous

Nonroad

Onroad

Industrial

Other Fuel Combustion

EGU

2002

2009

2018
 42 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Figure 7.2.6-2. Base G2 Annual NOx emissions in 2002, 2009, and 2018 in the VISTAS 

States. 

Summary of Final Emissions Inventories for 2009 and 2018

Table 7.2.6-1 is a summary of the 2009 final emission inventory for Mississippi. The complete 

inventory and discussion of the methodology is contained in Appendix D. 

VOC NOx PM2.5 PM10 NH3 SO2

Point 38,151 92,409 13,976 24,202 1,001 102,143 

Area 124,997 4,249 51,661 356,324 63,708 753 

On-Road Mobile 51,600 69,952 1,491 2,250 3,995 532 

Non-Road Mobile 36,197 80,567 3,985 4,270 25 7,191 

Biogenics 1,544,646 20,304 

TOTAL 1,795,571 267,482 71,113 387,046 68,729 110,619 

Table 7.2.6-1. Mississippi 2009 Emissions Inventory Summary in tons. 

0

100

200

300

400

500

600

700

800

900

1,000

Alabama

Florida

Georgia

Kentucky

Mississippi

North Carolina

South Carolina

Tennessee

Virginia

West Virginia

Annual NOx (Thousand Tons)

Miscellaneous

Nonroad Onroad

Industrial Other Fuel Combustion EGU

2002

2009

2018

0

100

200

300

400

500

600

700

800

900

1,000

Alabama

Florida

Georgia

Kentucky

Mississippi

North Carolina

South Carolina

Tennessee

Virginia

West Virginia

Annual NOx (Thousand Tons)

Miscellaneous

Nonroad Onroad

Industrial Other Fuel Combustion EGU

Miscellaneous

Nonroad Onroad

Industrial Other Fuel Combustion EGU

2002

2009

2018
 43 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Table 7.2.6-2 is a summary of the 2018 final emission inventory for Mississippi. The complete 

inventory and discussion of the methodology is contained in Appendix D. 

VOC NOx PM2.5 PM10 NH3 SO2

Point 46,452 71,804 17,172 30,046 1,591 54,367 

Area 140,134 4,483 53,222 375,495 69,910 746 

On-Road Mobile 31,306 30,259 810 1,607 4,520 435 

Non-Road Mobile 28,842 68,252 3,203 3,452 29 6,683 

Biogenics 1,544,646 20,305 

TOTAL 1,791,381 195,103 75,008 410,600 76,050 62,186 

Table 7.2.6-2. Mississippi 2018 Emissions Inventory Summary in tons. 

7.3 What Control Determinations Represent Best Available Retrofit 

Technology (BART) for Individual Sources? 

Section 169A of the CAA directs States to assess certain large, older emission sources for 

additional controls in order to address visibility impacts. States are directed to conduct BART 

determinations for such sources in specific source categories, and which contribute to visibility 

impairment in Class I areas. The 1999 regional haze rule includes the BART requirement, and 

directs States to include BART in their regional haze SIPs. On July 6, 2005, USEPA published a 

revised final rule, including Appendix Y to 40 CFR Part 51, the Guidelines for BART 

Determinations Under the Regional Haze Rule (hereinafter referred to as the “BART 

Guidelines”) that provides direction to states on determining which of these sources should be 

subject to BART, and how to determine BART for each source. 

A BART-eligible source is one which has the potential to emit 250 tons or more of a visibilityimpairing air pollutant, was put in place between August 7, 1962 and August 7, 1977, and whose 

operations fall within one or more of 26 specifically listed source categories. Under the CAA, 

BART is required for any BART-eligible source that a State determines ‘‘emits any air pollutant 

which may reasonably be anticipated to cause or contribute to any impairment of visibility in any 

such area.’’ 

For those sources subject to BART, Section 169A(g)(7) of the CAA requires that States must 

consider the following factors in making BART determinations: (1) the costs of compliance, (2) 

the energy and non-air quality environmental impacts of compliance, (3) any existing pollution 

control technology in use at the source, (4) the remaining useful life of the source, and (5) the 

degree of improvement in visibility which may reasonably be anticipated to result from the use 

of such technology. 
 44 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

7.3.1 BART-Eligible Sources in Mississippi 

Table 7.3.1-1 is a list of facilities with BART-eligible sources in Mississippi. See Appendix L 

for a detailed description of each BART-eligible emission unit. 

Facility Name City, County 

Chevron Products Company, Pascagoula Refinery Pascagoula, Jackson County 

Entergy Mississippi Inc, Baxter Wilson Plant Vicksburg, Warren County 

Entergy Mississippi Inc, Gerald Andrus Plant Greenville, Washington County 

Georgia Pacific Corp, Monticello Mill Monticello, Lawrence County 

Greenwood Utilities, Henderson Station Greenwood, Leflore County 

Holcim US Inc Artesia, Lowndes County 

International Paper Company, Vicksburg Mill Vicksburg, Warren County 

Terra Mississippi Nitrogen Inc Yazoo City, Yazoo County 

Mississippi Phosphates Corporation Pascagoula, Jackson County 

Mississippi Power Company, Chevron Cogenerating 

Plant 

Pascagoula, Jackson County 

Mississippi Power Company, Plant Jack Watson Gulfport. Harrison County 

Mississippi Power Company, Plant Victor J Daniel Ecatawpa, Jackson County 

Pursue Energy Corp, Thomasville Gas Plant Thomasville, Rankin County 

South Mississippi Electric Power Association, 

Moselle Plant 

Moselle, Jones County 

South Mississippi Electric Power Association, R D 

Morrow Plant 

Purvis, Lamar County 

Table 7.3.1-1. BART-eligible sources in Mississippi.

The BART-eligible sources were identified using the methodology in the BART Guidelines: 

• One or more emissions units at the facility fit within one of the 26 categories listed in the 

BART Guidelines; 

• The emission unit(s) were in existence on August 7, 1977 and began operation at some 

point on or after August 7, 1962; and 

• The limited potential emissions from all emission units identified in the previous two 

bullets emission units were greater than 250 tons or more per year of any of these 

visibility-impairing pollutants: SO2, NOx, and PM10. 
 45 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

The BART Guidelines recommend addressing these visibility-impairing pollutants: SO2, NOx, 

and particulate matter, and suggest that States use their best judgment in determining whether to 

address VOC or ammonia emissions. MDEQ addressed SO2 and NOx, and used particulate 

matter less than 10 microns in diameter (PM10) as an indicator for particulate matter to identify 

BART-eligible units, as the BART Guidelines recommend. VISTAS modeling demonstrated 

that VOCs are not significant emissions for this planning period. Point-source impacts from 

VOC emissions are below a significance level that the emissions will not be evaluated. VISTAS 

modeled several large ammonia sources whose potential emissions exceeded 250 tons per year 

and demonstrated an impact on visibility at Class I areas. However, Mississippi doesn’t have 

any large point sources of ammonia near Class I areas. For these reasons, MDEQ did not 

evaluate emissions of VOCs and ammonia in BART determinations. 

7.3.2 Determination of Sources Subject to BART in Mississippi 

Under the BART Guidelines, MDEQ may consider exempting some sources from BART if 

MDEQ finds that the emissions do not cause or contribute to visibility impairment in a Class I 

area. In accordance with the BART guidelines, MDEQ chose to perform source-specific 

analyses to determine which sources cause or contribute to visibility impairment using the 

CALPUFF model. The CALPUFF modeling protocol used for determining which facilities are 

subject to BART is included in Appendix L. A contribution threshold of 0.5 deciviews was used 

for determining which sources were subject to BART. This is the level suggested in the BART 

guidelines and the threshold used by the surrounding states with the Class 1 areas that sources in 

Mississippi could impact. A complete discussion of the suitability of the 0.5 deciview threshold 

can be found in Appendix L. 

Mississippi’s BART-eligible sources were screened to determine subjectivity in three different 

ways. Ten performed and submitted exemption modeling analysis. Two had the exemption 

analysis performed by TRC under VISTAS Contract. Three were exempted based on the model 

plant provision (Option 2 in the Guidelines). 

For the facilities that performed modeling for exemption, the IMPROVE (Interagency 

Monitoring of Protected Visual Environments) equation was used to determine the impact of a 

facility’s emissions on visibility at Class 1 areas. This equation determines light extinction (bext) 

in inverse megameters. Originally, the IMPROVE equation was set forth in “Guidance for 

Estimating Natural Visibility Conditions Under the Regional Haze Program”, EPA-454/B-03-

005, September 2003. In 2005, the IMPROVE Steering Committee made recommendations for a 

refined equation that modifies the terms of the original equation to account for the most recent data. . 

Among other improvements, the new equation allows for the use of site specific Raleigh 

Scattering factors and sea-salt values. Raleigh Scattering is the light scattering effect that the 

molecules exert and is greater at sea level. Sea-salt also has a light scattering effect and is 

important at coastal sites, such at Breton. There were no sea-salt values available for Breton, so 

the values for St. Marks, a gulf coastal site in Florida, were used. 
 46 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

The choice between use of the old or the new equation for calculating the visibility metrics for each 

Class I area is made by the state in which the Class I area is located. Mississippi allowed the use of 

the new IMPROVE equation in performing the screening analysis. The states of Alabama, 

Arkansas, and Louisiana whose Class 1 areas were potentially impacted also allowed the use of 

the new IMPROVE equation. However, since the old IMPROVE equation was considered the 

default, gave more conservative results, and the new IMPROVE equation required additional 

processing to implement, only three facilities (Mississippi Power- Plant Watson, Mississippi 

Power-Plant Daniel, and Mississippi Power-Chevron Cogeneration Station) used the new 

IMPROVE equation for the screening analysis. Appendix L.12 discusses the IMPROVE 

Equation in greater detail. 

Three facilities used the Model Plant rule as given in Part III, Option 2 of the BART Guidelines 

to be exempted. The model plant criteria for exemption states that potential emissions of SO2 or 

NOx or SO2 + NOx should be less than 500 tons for facilities greater than 50 kilometers (km) 

from the nearest class I area or potential emissions should be less than 1000 tons for facilities 

greater than 100 km from the nearest class I area. The model plant criteria proposed by the EPA 

does not consider the contribution from PM. Logic to appropriately include PM in the model 

plant exemption process was developed by Jim Boylan of Georgia DNR. This rationale 

determines a “PM factor” to relate primary PM to secondary sulfate PM from SO2. The three 

facilities that were exempted based on the model plant rule are South Mississippi Electric Power 

Association (SMEPA)-Moselle Plant, SMEPA- R D Morrow Plant, and Terra Mississippi 

Nitrogen. Further detail on this exemption process is found in Appendices L.8 and L.9. 

Thirteen of the fifteen sources were able to demonstrate exemption. Results of these 

demonstrations are summarized in Table 7.3.2-1. Additional details are available in Appendix L. 

Facilities found to be subject to BART completed a BART analysis. 

Seven (7) of the BART eligible sources are EGUs subject to CAIR. USEPA has determined that, 

as a whole, the CAIR cap-and-trade program improves visibility more than implementing BART 

for individual sources in states affected by CAIR. A State that opts to participate in the CAIR 

program under part 96 AAA-EEE need not require affected BART-eligible EGUs to install, 

operate, and maintain BART for SO2 or NOx emissions. Since Mississippi is participating in 

CAIR and accepts USEPA’s overall finding that CAIR “substitutes” for BART for NOx and SO2, 

Mississippi’s EGUs were allowed to submit BART exemption modeling demonstrations for PM 

emissions only. All EGUs demonstrated that each facility’s emissions do not contribute to 

visibility impairment in any Class I area. 
 47 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Facility Name Class I area Results/ 

Impact 

Chevron Products Company, Pascagoula 

Refinery 

Breton National Wildlife Refuge Subject 

3.89dv 

Mississippi Phosphates Corporation Breton National Wildlife Refuge Subject 

0.81dv 

Entergy Mississippi Inc, Baxter Wilson 

Plant 

Breton National Wildlife Refuge Exempt 

0.35dv 

Entergy Mississippi Inc, Gerald Andrus 

Plant 

Caney Creek Wilderness Area Exempt 

0.27dv 

Georgia Pacific Corp, Monticello Mill Breton National Wildlife Refuge Exempt 

0.33dv 

Greenwood Utilities, Henderson Station Sipsey Wilderness Area Exempt 

0.22dv 

Holcim US Inc Sipsey Wilderness Area Exempt 

0.34dv 

International Paper Company, Vicksburg 

Mill 

Breton National Wildlife Refuge Exempt 

0.32 

Mississippi Power Company, Chevron 

Cogenerating Plant 

Breton National Wildlife Refuge Exempt 

0.02dv 

Mississippi Power Company, Plant Jack 

Watson 

Breton National Wildlife Refuge Exempt 

0.42dv 

Mississippi Power Company, Plant Victor J 

Daniel 

Breton National Wildlife Refuge Exempt 

0.23dv 

Pursue Energy Corp, Thomasville Gas 

Plant 

Breton National Wildlife Refuge Exempt 

0.17dv 

Terra Mississippi Nitrogen Inc Sipsey Wilderness Area Exempt 

(model plant) 

South Mississippi Electric Power 

Association, Moselle Plant 

Breton National Wildlife Refuge Exempt 

(model plant) 

South Mississippi Electric Power 

Association, R D Morrow Plant 

Breton National Wildlife Refuge Exempt 

(model plant) 

Table 7.3.2-1. BART Exemption Modeling Results. 
 48 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

7.3.3 Determination of BART Requirements for Subject-to-BART Sources 

After the Screening analysis, two sources were determined to be “subject to BART” and were 

required to perform an engineering analysis containing their evaluation of potential BART 

options and proposed BART determinations. The two (2) “subject to BART” facilities are the 

Chevron Pascagoula Refinery in Pascagoula, Mississippi and Mississippi Phosphates in 

Pascagoula, Mississippi. 

The modeled visibility impact resulting from Chevron Refinery’s emissions was 3.89dv, which 

exceeds the threshold of 0.5 dv. Chevron has significant emissions reductions planned due to 

permitted projects that are currently or will soon be underway and an enforcement consent 

decree issued June 7, 2005. This will result in emission reductions of 2900 lbs/hr of SO2, 960 

lbs/hr, of NOx and 40 lbs/hr of PM10 with a modeled visibility improvement of 2.99dv at 

Breton. See Table 7.3.3-1 below for a detailed account of the units, involved in Chevron’s 

consent decree, that contribute to 96% of the SO2 emissions for Chevron’s BART-eligible 

sources. Further reductions would be very costly without significant visibility improvement. 

Mississippi has determined that the emissions controls and resulting reductions from the consent 

decree constitute BART. The Complete BART analysis for Chevron can be found in appendix 

L.10. 

 

Max Daily Averages (2001-

2003) 

Future Planned 

Emissions / Consent 

Decree 

 NOx SO2 VOC NOx SO2 VOC 

BART Eligible 

Unit lb/hr lb/hr lb/hr lb/hr lb/hr lb/hr Controls 

F-1603/FCC 

Regenerator 374.000 841.000 111.000 80.000 60.000 99.000 NOx reducing catalyst 

F-2101/Boiler No.1 86.000 4.300 1.800 0.000 0.000 0.000 

F-2102/Boiler No.2 82.000 4.300 1.700 0.000 0.000 0.000 

F-2103/Boiler No.3 84.000 4.600 1.800 0.000 0.000 0.000 

Boilers being replaced by 

ULNB boilers 

F-2745/SRU 2 

w/Thermal 

Oxidizer 2.300 870.000 0.400 2.300 36.000 0.360 

F-2765/SRU 3 

w/Thermal 

Oxidizer 10.500 730.000 1.400 10.500 36.000 1.360 

SCOT tail gas treatment 

systems 

F-3801/Flare No. 1 8.700 110.800 3.900 0.690 0.003 0.007 

F-3801/Flare No. 2 15.600 213.800 7.000 0.690 0.003 0.007 

F-3801/Flare No. 3 7.300 174.200 3.300 0.690 0.003 0.007 

F-3801/Flare No. 4 4.100 63.300 1.800 0.690 0.003 0.007 

Flare gas recovery 

system 

F-6101/6102 

Crude Unit No.2 

Heaters 282.000 16.400 5.300 28.160 16.410 5.350 

ULNB will be installed 

Total Reductions* NOx 832.78 SO2 2884.28 VOC 33.30 

*This table represents 96% of the SO2 emissions from BART-eligible units 

Table 7.3.3-1. Major BART-eligible Units Involved in the Consent Decree 
 49 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

The modeled visibility impact resulting from Mississippi Phosphate’s emissions was 0.81dv, 

which exceeds the threshold of 0.5 dv. The primary emissions at Mississippi Phosphates are SO2

from the facility’s two Sulfuric Acid Plants. The existing control equipment on the Acid Plants 

are a Dual Absorption System and Acid-Mist demisters. This results in emissions of 4 lbs SO2

per ton of Sulfuric Acid. The BART analysis finds that there may be available alternatives that 

are technically feasible at the facility and could further reduce emissions. However, Mississippi 

Phosphates is planning to modify the acid plants at the facility over the next several years. 

Mississippi Phosphates is currently in the design phase for the new units which will include 

better emission controls for the acid plants. They are planning to perform a combined BART 

and BACT analysis to determine the appropriate future controls at the facility. This will take 

several months to complete and several more months to evaluate and issue permits. Mississippi 

will submit a supplemental SIP with the control determination one year after the initial Regional 

Haze SIP submittal. The complete BART Analysis and accompanying details for Mississippi 

Phosphates can be found in appendix L.11. 

7.4 Relative Contributions to Visibility Impairment: Pollutants, Source 

Categories, and Geographic Areas 

An important step toward determining the long term strategy measures is to identify the key 

pollutants contributing to visibility impairment at each Class I area. To understand the relative 

benefit of further reducing emissions from different pollutants, source sectors, and geographic 

areas, VISTAS engaged the Georgia Institute of Technology to perform emission sensitivity 

model runs using CMAQ. Emissions sensitivities were initially performed for three episodes 

representing winter and summer conditions: Jan 2002, July 2001, and July 2002. These runs 

used the initial 2018 projections inventory and considered thirty (30) percent reductions from 

specific pollutants, source categories, and geographic areas. A thirty (30) percent emission 

reduction was chosen for the sensitivity runs because it is large enough to obtain results and 

represents a reasonable expectation of reductions from various source categories. Emissions 

sensitivities were repeated using the 2009 Base D projection inventory and two month-long 

episodes from 2002: Jun 1-Jul 10 and Nov 19 – Dec 19. Emissions in 2009 were reduced by 

thirty (30) percent for each pollutant sensitivity run. The pollutant contributions that were 

evaluated were: 

• SO2 from EGU sources in each VISTAS state, other RPOs in the VISTAS 12 km grid, 

and Boundary Conditions from outside the 12 km domain. 

• SO2 from non-EGU point sources in each VISTAS state, other RPOs, and Boundary 

Conditions 

• NOx from ground level (on-road plus non-road plus area) sources in each VISTAS state 

and other RPOs 

• NOx from point (EGU plus non-EGU) sources in each VISTAS state and other RPOs 

• NH3 from all sources in VISTAS and other RPOs 

• Volatile Organic Compounds from anthropogenic and biogenic sources in the 12 km 

modeling domain 

• Primary Carbon from all ground level sources in each VISTAS state and other RPOs 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

• Primary Carbon from all point sources in each VISTAS state and other RPOs 

• Primary Carbon from all fires in each VISTAS state and other RPOs 

Results are shown in Figures 7.4-1 through 7.4-3 below for a thirty percent reduction in 

emissions for each of the three Class I areas near Mississippi. Responses for twenty (20) percent 

worst days were calculated by averaging the responses of the twenty (20) percent worst days that 

were modeled in the two episodes for Sipsey and Caney Creek. Complete data was not available 

to determine the 20 percent worst days for Breton so chart depicts the response to the full 

summer episode. 

Figure 7.4-1. CMAQ projections of visibility responses on to 30 percent reductions from 

the 2009 Base D inventory for visibility-reducing pollutants in different source categories 

and geographic areas. 
 51 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

Figure 7.4-2. CMAQ projections of visibility responses on 20 percent worst days at Sipsey, 

AL to 30 percent reductions from the 2009 Base D inventory for visibility-reducing 

pollutants in different source categories and geographic areas. 

Figure 7.4-3. CMAQ projections of visibility responses on 20 percent worst days at Caney 

Creek, AR to 30 percent reductions from the 2009 Base D inventory for visibility-reducing 

pollutants in different source categories and geographic areas. 
 52 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

As Figures 7.4-1 through 7.4-3 illustrate, the greatest visibility benefits for these Class I areas 

are projected to result from reducing SO2 from EGUs. Additionally, smaller benefits are 

projected from SO2 emission reductions from non-utility, industrial point sources. The pattern of 

relative SO2 contributions from non-EGUs among the various VISTAS states is similar to the 

pattern of relative SO2 contributions from EGUs. 

Figures 7.4-1 through 7.4-3 also indicate that Mississippi has minor impacts on all three (3) 

neighboring Class I sites. Mississippi has more significant impacts on Breton than Sipsey or 

Caney Creek. The Area of Impacts analysis in Section 7.5.4 further illustrates Mississippi’s 

impact on the neighboring Class I areas. 

Because ammonium nitrate is a small contributor to PM2.5 mass and visibility impairment on the 

twenty (20) percent worst days, the benefits of reducing NOx and NH3 emissions in Mississippi 

are small. 

VOCs do contribute to visibility impairment, but as shown in the Figures 7.4-1 through 7.4-3

above, this contribution is from biogenic sources such as vegetative emissions. Controlling 

anthropogenic sources of VOC emissions has little if any visibility benefit at the Class I areas. 

Reducing primary carbon from point sources, ground level sources or fires are projected to have 

small to no visibility benefit. This is consistent with the monitoring data that shows that most of 

measured organic carbon is secondary in origin and primary carbon is only a small fraction of the 

total measured carbon (Appendix B). Reducing carbon from fires was not found to be effective 

because there was little fire activity at these sites on the days modeled in the sensitivity analyses. 

The results indicate that sulfate is the dominant contributor to visibility impairment on the twenty 

(20) percent worst days at all sites, and that ammonium nitrate may be important for sites where 

the twenty (20) percent worst days occur in the winter. MDEQ concludes that reducing SO2

emissions from EGU and non-EGU point sources would have the greatest visibility benefits. 

Contributions from outside the VISTAS 12-km modeling domain are more important for the 

coastal Class I areas. These results are consistent with the CMAQ model results indicating that 

contributions from international emissions to visibility impairment at VISTAS Class I areas are 

greater closer to the boundaries of the modeling domain (see summary in section 7.3). 

7.5 Relative Contributions to Visibility Impairment: Geographic Areas of 

Influence for Neighboring Class I Areas 

Once it was determined that SO2 emission reductions from EGU and non-EGU point sources in 

the VISTAS states would be the most effective sources to control to improve visibility at 

neighboring Class I areas, the next step was to identify the specific geographic areas that most 

likely influence visibility in each Class I area, and then to identify the major SO2 point sources 

located in those geographic areas. Mississippi, along with the other VISTAS states, developed 

an Area of Influence (AoI) for each Class I area to represent the geographic area containing 

sources that would likely have the greatest impact on visibility at that Class I area. All SO2 point 

sources within these Areas of Influence were identified and ranked by their 2018 emissions. 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

Mississippi used this AoI analysis to determine the sources that need to be evaluated to meet the 

reasonable progress goals for neighboring Class 1 areas. The following sections contain an 

overview of the steps in the Area of Influence analyses. 

7.5.1 Back Trajectory Analyses 

The first step was to generate meteorological back trajectories for IMPROVE monitoring sites in 

neighboring Class I areas for the 2000-2004 baseline period. Back trajectory analyses use 

interpolated measured or modeled meteorological fields to estimate the most likely central path 

of air masses that arrive at a receptor at a given time. The method essentially follows a parcel of 

air backward in hourly steps for a specified length of time. Figure 7.5.1 is an example of a back 

trajectory analysis for Breton for the twenty (20) percent worst days in 2002. 

Figure 7.5.1. Example back trajectories for 20 percent worst visibility days in 2002 for 

Breton. 

Trajectories were started at 100 meters and 500 meters above the surface and run backward from 

the site for 72-hours. These individual back trajectories for twenty (20) percent worst days in 

2002 were also useful in evaluating model performance for individual days at the Class I areas. 

7.5.2 Residence Time Plots 

The next step was to plot residence time for each Class I area using five years of back trajectories 

for the twenty (20) percent worst visibility days in 2000-2004. Residence time is the frequency 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

that winds pass over a specific geographic area on the path to a Class I area. Separate residence 

time plots were generated using trajectories with 100m start height. As illustrated in Figure 

7.5.2, winds influencing Breton on the twenty (20) percent worst days come from several 

directions with no single predominant wind direction influencing the twenty (20) percent worst 

visibility days. 

Figure 7.5.2. Example residence time plot for 20 percent worst visibility days in 2000-2004 

for Breton, Louisiana. Based on trajectories with 100m start height. 

7.5.3 SO2 Areas of Influence 

The next step was to develop sulfate extinction weighted residence time plots to define the 

geographic area with highest probability of influencing the receptor on the twenty (20) percent 

worst days in 2000-2004 that were dominated by sulfate. Each back trajectory was weighted by 

sulfate extinction for that day. This allows us to focus on the twenty (20) percent worst days that 

are influenced by sulfate and place less importance on days influenced by organic carbon from 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

fires. Sulfate-weighted back trajectories for the twenty (20) percent worst days were combined 

for 5 years of data. The resulting sulfate extinction-weighted residence time plots were used to 

define the geographic Area of Influence for sources of SO2 emissions. In Figure 7.5.3 the area 

representing ten (10) percent or greater residence time is outlined in red and the area representing 

five (5) percent or greater residence time is outlined in gray. The VISTAS states focused their 

analyses on the Area of Influence defined by five (5) percent or greater sulfate extinctionweighted residence time. 

Figure 7.5.3. Example SO2 Area of Influence plot for sulfate extinction weighted residence 

time for 20 percent worst visibility days in 2000-2004 for Breton, Louisiana. Based on 

trajectories with 100m start height. 

7.5.4 Emissions Sources within SO2 Areas of Influence 

Residence time plots were then combined with geographically-gridded emission data based on 

the 2002 baseline and 2018 BaseG emissions inventories. Plots were generated for the Areas of 

Influence (AOI) defined by trajectories with 100m and 500 m start heights. As a way of 

incorporating the effects of transport, deposition, and chemical transformation of point source 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

emissions along the path of the trajectories, these data were weighted by 1/d, where d was 

calculated as the distance, in kilometers, between the center of the grid cell in which a source is 

located and the center of the grid cell in which the IMPROVE monitor is located. The distanceweighted point source SO2 emissions are then combined with the gridded extinction-weighted 

back-trajectory residence times at a spatial resolution of 36-km. 

The final step was to combine the residence times and gridded emissions data in plots and data 

sets. The distance weighted (1/d) gridded point source SO2 emissions were multiplied by the 

total extinction-weighted back-trajectory residence times on a grid cell by grid cell basis. These 

results were then normalized by the domain-wide total and displayed as a percentage. The 

analysis was done using both the 2002 and 2018 base year inventories. 

Figures 7.5.4-1 through 7.5.4-3 illustrate 2018 distance weighted gridded emissions sulfate 

extinction weighted residence time plots for Breton, Sipsey and Caney Creek. For Breton, the 

Area of Influence only includes sources in south Mississippi, primarily, in coastal counties. The 

AOI plots for Sipsey and Caney Creek do not indicate any sources in Mississippi. By examining 

these maps, the focus narrows to only working with sources in south Mississippi with potential 

impacts on Breton. 

These analyses are serving as the basis for consultation among the VISTAS states. 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

Figure 7.5.4-1. Breton, Louisiana 2018 SO2 distance weighted emissions * SO4 extinctionweighted residence time plots. 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

Figure 7.5.4-2. 2018 SO2 distance weighted emissions * SO4 extinction-weighted residence 

time plot for Sipsey, Alabama. 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

Figure 7.5.4-3. 2018 SO2 distance weighted emissions * SO4 extinction-weighted residence 

time plot for Caney Creek, Arkansas. 

7.5.5 Specific Sources in the Areas of Influence 

The next step in the analysis was to review the emissions inventories to determine the specific 

sources found to have the greatest impact on visibility at Breton. Lists of SO2 point sources 

within the Areas of Influence for each Class I areas were developed using the most current 

(BaseG) VISTAS 2002 base year and 2018 future year emissions. For this purpose the Area of 

Influence was defined as the counties with maximum sulfate extinction weighted residence time 

greater than 5. For SO2 sources within each Area of Influence, the following attributes were 

defined for each individual unit: 

• State, county, and source (plant), and industry identification codes 

• SO2 emissions for 2002 and 2018 

• 2018 control efficiency 

• Distance to Class I areas (defined by centroid of the Class I area) 

• Emissions divided by distance (Q/d), a metric that accounts for the dispersion of 

emissions over distance 

• Maximum sulfate extinction weighted residence time (RTmax) 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

Looking specifically at the Breton Class I area, MDEQ multiplied the RTMax by Q/d, added the 

RTMax * Q/d terms for all facilities, and then divided this term for each unit by that for all sources 

to get a percent (%) contribution. Table 7.5.5-1 shows this approach for Mississippi facilities 

and limited data. The complete spreadsheet can be found in Appendix M. The percent 

contribution is based on all facilities in all states in the 2018 inventory. 

After developing the percent contribution values, MDEQ used a one percent (1%) per unit cut 

point to determine the facilities and units to further analyze. MDEQ chose to adopt 1% as the 

contribution threshold used to consider a source for a four factor analysis of reasonable further 

controls based on the precedence established in other Federal programs as follows: 

• The BART rule specified that a maximum impact of 0.5 dv is an acceptable threshold for 

establishing significance. This threshold is representative of a 5 percent change in extinction. 

• The NOx SIP call established a significance level for 126 petitions (the level at which a 

state’s contribution to another state’s ozone was considered significant) at 4 parts per billion. 

This threshold is representative of approximately 3.75 percent of the 1 hour ozone standard 

of 125 parts per billion, which was the standard at the time. 

• The CAIR rule established a PM contribution threshold of 0.2 μg/m3 as significant. This 

threshold represents 1.3 percent of the Annual PM2.5 standard of 15 μg/m3. 

• The NAAQS assign significant impact levels for human health standards based on a sources’ 

contribution to air quality. These significance levels represent a percentage of the NAAQS. 

Those facilities able to demonstrate that a new or modified sources’ contribution is less than 

a particular significance level is relieved of further modeling. MDEQ examined all the 

averaging periods for the criteria pollutants and determined that the 1 percent threshold 

contribution chosen for reasonable further progress was as stringent as any significant impact 

level, the most restrictive being NO2 at 1 μg/m3 or 1 percent. (NO2 NAAQS 100 μg/m3) 

Based on the above, a 1% threshold is reasonable to determine emissions units to be further 

evaluated to help meet the Reasonable Progress Goals. It is also the threshold that surrounding 

VISTAS states have adopted. 

Table 7.5.5-1 lists the significant facilities and units that may impact Breton. The units that meet 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

a 1.0 % contribution test are highlighted in yellow in Table 7.5.5-1. As can be seen in Table 

7.5.5-1, the 1.0 % contribution test yields only a few sources that need to be examined further.

Facility Point 

ID 

SO2 

(tons) 

Dist Q/d RT 

Max** 

Qd* 

RTmax 

% cont 

Mississippi Power Company, Plant Watson 004 7,640 148.07 51.60 28.09 1449.31 5.4%

DuPont DeLisle Facility 024 1,645 137.98 11.92 28.09 334.80 1.2%

DuPont DeLisle Facility 025 1,627 137.98 11.79 28.09 331.21 1.2%

Mississippi Phosphates Corporation 006 918 140.83 6.52 28.09 183.02 0.7%

Mississippi Phosphates Corporation 008 786 140.83 5.58 28.09 156.83 0.6%

Mississippi Power Company, Plant Watson 005 759 148.07 5.13 28.09 144.03 0.5%

Mississippi Power Company, Plant Daniel 002 847 169.42 5.00 28.09 140.45 0.5%

Mississippi Power Company, Plant Daniel 001 799 169.42 4.71 28.09 132.42 0.5%

Chevron Pascagoula Refinery 017 262.8 123.85 2.12 28.09 59.60 0.2%

Chevron Pascagoula Refinery 052 157 123.85 1.27 28.09 35.61 0.1%

Chevron Pascagoula Refinery 051 157 123.85 1.27 28.09 35.61 0.1%

Holcim Inc, Artesia 002 3,991 475.57 8.39 8.93 74.93 0.3%

Pursue Energy Corporation, Thomasville G 001 3,303 346.74 9.53 6.44 61.35 0.2%

Choctaw Generation LLP, Red Hills Genera 001A 3,758 473.82 7.93 7.27 57.66 0.2%

Georgia Pacific Corporation, Monticello 002 1,765 291.74 6.05 6.72 40.65 0.2%

Georgia Pacific Corporation, Monticello 001 1,652 291.74 5.66 6.72 38.06 0.1%

CII Carbon LLC 001 670 230.26 2.91 11.24 32.72 0.1%

SMEPA , Plant Morrow 001 670 234.48 2.86 11.24 32.12 0.1%

SMEPA, Plant Morrow 002 670 234.48 2.86 11.24 32.12 0.1%

Table 7.5.5-1. Percent Contributions to Breton 

7.6 Evaluating the Specific SO2 Emissions Sources 

Mississippi used the Area of Impact (AOI) analysis described in the preceding sections to 

determine sources that need further evaluation to help meet reasonable progress goals. The 

sources identified by the Area of Impact analysis will be evaluated to determine if there are 

reasonable controls that can be applied to meet the reasonable progress goals for the impacted 

Class 1 area. The neighboring state of Alabama uses the same methodology. Louisiana is in a 

different planning organization and used different methods to for reasonable progress 

determinations; however, as noted in the Section 10, Mississippi and Louisiana have met several 

times and there were no issues with the AOI methodology. 

The Regional Haze Rule states that the cost of controls, time necessary for compliance, energy 

and non-air environmental impacts, and the remaining useful life of any potentially affected 

sources should be considered in setting the reasonable progress goals. 

From Table 7.5.5-1, there are only two facilities that meet the 1.0 % test and need to be evaluated 

for reasonable progress. Those facilities are: 

• Mississippi Power Company, Plant Watson, Harrison County, and 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

• DuPont Delisle Facility, Harrison County. 

Mississippi Power Company, Plant Watson

Mississippi Power Company, Plant Watson is a coal fired Electricity Generating Facility. Plant 

Watson is subject to the Clean Air Interstate Rule (CAIR) which requires significant reductions 

of NOx and SO2 in the eastern United States. The CAIR results in reductions of over seventy (70) 

percent for SO2 emissions and by over sixty (60) percent NOx emissions from 2003 levels. The 

CAIR is a cap and trade program that does not require specific emissions reductions from any 

specific facilities, but the utility companies will have to reduce emissions from a significant 

number of EGU’s to meet the emissions cap. Plant Watson has two Coal fired units. Controls 

for NOx and SO2 are proposed for unit 5 which is the larger unit with more emissions. This will 

result in significant emissions reductions from this facility. The facility being subject to CAIR is 

deemed sufficient for reasonable progress. 

To further support EGUs subject to CAIR is sufficient for reasonable progress, a discussion in 

the CAIR rule highlighted below (70 FR 25197) addresses the reasonable progress factors of cost 

and time necessary for compliance for these EGUs, and provide the necessary support for a 

State's four factor reasonable progress analysis that must accompany a State’s assertion that 

CAIR is sufficient for reasonable progress for subject EGU’s during the first planning period. 

From past experience in examining multi-pollutant emissions trading programs for SO2 and 

NOX, EPA recognized that the air pollution control retrofits that result from a program to 

achieve highly cost-effective reductions are quite significant and can not be immediately 

installed. Such retrofits require a large pool of specialized labor resources, in particular, 

boilermakers, the availability of which will be a major limiting factor in the amount and timing of 

reductions 

Also, EPA recognized that the regulated industry will need to secure large amounts of capital to 

meet the control requirements while managing an already large debt load, and is facing other 

large capital requirements to improve the transmission system. Furthermore, allowing pollution 

control retrofits to be installed over time enables the industry to take advantage of planned 

outages at power plants (unplanned outages can lead to lost revenue) and to enable project 

management to learn from early installations how to deal with some of the engineering 

challenges that will exist, especially for the smaller units that often present space limitations 

Based on these and other considerations, EPA determined in the NPR that the earliest reasonable 

deadline for compliance with the final highly cost-effective control levels for reducing emissions 

was 2015 (taking into consideration the existing bank of title IV SO2 allowances). First, the 

Agency confirmed that the levels of SO2 and NOX emissions it believed were reasonable to set as 

annual emissions caps for 2015 lead to highly cost-effective controls for the CAIR region. 

Once EPA determined the 2015 emissions reductions levels, the Agency determined a proposed 

first (interim) phase control level that would commence January 1, 2010, the earliest the Agency 

believed initial pollution controls could be fully operational (in today's final action, the first NOX 

control phase commences in 2009 instead of in 2010, as explained in detail in section IV.C). The 

first phase would be the initial step on the slope of emissions reductions (the glide-path) leading 

to the final (second) control phase to commence in 2015. The EPA determined the first phase 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

based on the feasibility of installing the necessary emission control retrofits, as described in 

section IV.C. 

Although EPA's primary cost-effectiveness determination is for the 2015 emissions reductions 

levels, the Agency also evaluated the cost effectiveness of the first phase control levels to ensure 

that they were also highly cost effective. Throughout this preamble section, EPA reports both the 

2015 and 2010 (and 2009 for NOX) cost-effectiveness results, although the first phase levels were 

determined based on feasibility rather than cost effectiveness. The 2015 emissions reductions 

include the 2010 (and 2009 for NOX) emissions reductions as a subset of the more stringent 

requirements that EPA is imposing in the second phase. 

Conclusion

It is Mississippi’s determination that Mississippi Power, Plant Watson being subject to CAIR and 

participating in the CAIR trading program meets the reasonable progress requirements of the 

Regional Haze Rule. 

DuPont DeLisle Facility

DuPont DeLisle Facility is a Titanium Dioxide pigment plant located in DeLisle, Mississippi. 

The facility has two 209 MM BTU/hr coal fired process boilers that are of concern. The four 

factors listed in the Regional Haze Rule (40 CFR 51.308(d)(1)(i)(A)) will be applied to potential 

SO2 controls for these units. Dupont has submitted a document (see appendix N) that addresses 

the potential controls and cost. Potential controls for SO2 reduction would include switching to a 

lower sulfur fuel, and post combustion scrubbers. The facility is currently permitted to burn 3% 

sulfur coal but uses 2.5% sulfur coal. Dupont evaluated switching to 1.05%, 1.5% and 2.0% 

sulfur coal and using spray dry absorbers and sodium wet scrubbers in conjunction with lower 

sulfur fuel. 

Cost of Controls

Compared to the current coal used, the SO2 reduction would be 998 TPY with an incremental 

cost effectiveness vs Baseline of $738/ton SO2 removed for the 2.0% coal; and the SO2 reduction 

would be 1996 TPY with an incremental cost effectiveness vs Baseline of $527/ton SO2 removed 

for the 1.5% coal. The 1.05% sulfur coal would not be an option due to adverse impacts on the 

facilities recently upgraded electrostatic precipitators. In addition, significant testing and 

evaluation would need to be conducted to determine if any of the lower sulfur coal could be 

utilized and the boilers be able to meet the Subpart DDDDD Boiler MACT standards. 

The additional SO2 reduction of using a scrubber in conjunction with a lower sulfur fuel 

compared to using the lower sulfur coal (1.5%) ranged from 2700 to 2900 TPY with a cost of 

$3000 to $4000/ton. 

Time Necessary for Compliance

Options utilizing lower sulfur coal would require time for finding and evaluating alternative coal 

supplies that not only provide lower sulfur levels, but also that can provide required combustion 

performance and compliance with the Subpart DDDDD Boiler MACT regulations. In addition, 
 64 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

as noted above, the effects of lower sulfur coal use on the performance of the hot side ESP and 

resultant emissions and opacity impact need to be assessed. The evaluation of the coal type and 

sources necessary to meet the lower sulfur standards and securing necessary contracts will take 

several years. It is likely that conversion to alternative coal would not be possible prior to 2013. 

Options utilizing scrubbing would require extended time for compliance due to the need for 

detailed design and project implementation as well as capital planning. The high level of 

emissions control system installations in the future planning period in response to CAIR and 

BART will put a significant strain on resource availability and costs. Therefore, if scrubbing 

was required, it is likely that compliance would not be attainable until the 2013 time frame. 

Energy and Non-Air Environmental Impacts

Use of lower sulfur alone coal would not entail any significant changes to energy use or non-air 

quality environmental impacts. 

Use of a spray dry scrubber would require use of lime as the reagent. Solid waste disposal would 

increase over the current coal ash-only condition by the quantity of calcium sulfate formed in the 

scrubber. This can be estimated based on removal percent and expected calcium/sulfur 

stoichiometric ratio. Costs for that disposal are included within the estimated O&M cost 

estimates. As indicated above, the additional waste would be dry, so it would likely be disposed 

of in a landfill. Additional purchased electricity would be required for operation of the scrubber 

and baghouse, including, for example, lime transport, slurry preparation and injection, baghouse 

pulse air, ash and spent sorbent handling, and increased fan power to compensate for increased 

flue gas pressure drop. Water would also be consumed for slurry preparation. 

Use of a sodium wet scrubber would require use of caustic as the reagent. Liquid waste disposal 

would increase for disposal of the scrubber blowdown stream. The existing plant waste water 

treatment facility does not have adequate capacity for that waste stream directly, but some form 

of neutralization and oxidation would be required prior to transfer to the waste treatment system. 

Costs for that disposal are included within the estimated O&M cost estimates. Additional 

purchased electricity would be required for operation of the scrubber, including, for example, 

liquid pumping power and increased fan power to compensate for increased flue gas pressure 

drop. Water would also be consumed for the scrubber solution. 

The use of scrubbers would also result in increased energy use. Increased purchased electricity 

would result in increased emissions of SO2, NOx, CO2, and other emissions from the electric 

utility generators providing that power, which could in fact, be units that themselves impact 

Breton with their SO2 and NOx emissions. 

Remaining Useful Life

There is no indication that these units are near the end of their useful life. 

Conclusion
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

Given the potential impact that the DuPont DeLisle plant has on Breton, Mississippi has 

determined that SO2 reductions are in order to help meet the Reasonable Progress Goals for 

Breton. DuPont is currently working with Mississippi to determine the level of reduction that is 

reasonable during this planning period. Mississippi will make the final determinations, issue a 

permit and submit a supplemental SIP within one year of the initial Regional Haze SIP submittal 

to EPA. 

7.7 What Additional Emissions Controls Were Considered as part of the 

Long-Term Strategy for Visibility Improvement by 2018? 

Class 1 areas are sensitive visibility receptors and Section 308(d)(3)(v) of the regional haze rule 

lists several factors that could impact visibility to be addressed in each SIP. These factors 

include the role of fire at Class I areas and status of state planning for smoke management, the 

role of dust and fine soil at Class I areas and status of state plans to mitigate emissions from 

construction activities and the role of NH3 and potential benefits if emissions from agricultural 

sources were mitigated. 

Since there are no Class I areas in Mississippi and the Class I area that is closest and of greatest 

concern, Breton, is over 45 km offshore, these factors will have little impact. As can be seen in 

Figures 7.4-1 through 7.4-3, elemental carbon (sources include agriculture, prescribed wildland 

fires, and wildfires) is a relatively minor contributor to visibility impairment at the Class I areas 

surrounding Mississippi. Mississippi has drafted but not finalized a Smoke Management Plan. 

Under current smoke management practices, the Mississippi Forestry Commission, in 

conjunction with the Mississippi Department of Environmental Quality, issues burning permits 

based on daily weather forecasts. A permit is required for any fire set for a recognized 

agricultural or forestry purpose. 

Mississippi has no particular provisions to mitigate dust emissions from construction activities. 

However, there are nuisance provisions in state regulations that would apply if construction or 

other activities were generating significant emissions. Given the distance of the closest Class 1 

area to Mississippi, this would provide adequate control from these activities. 

7.8 Long Term Strategy Summary 

For this first planning period, the emissions controls from existing federal standards, such as 

CAIR and the Heavy Duty Diesel Rule, will be significant and result in significant reductions of 

visibility impairing pollutants from sources in Mississippi. There are two facilities in Mississippi 

that were identified by BART or the reasonable progress analysis that appear to need additional 

controls. Evaluations are still underway for these facilities. The appropriate determinations will 

be made for these sources over the next year and a supplemental SIP will be submitted within a 

year of the initial SIP submittal. 

In the future, the impacts of new sources will need to be addressed. This will be done as part of 

the permitting process. The appropriate FLM for class 1 areas within 300km of a source 
 66 

Mississippi Regional Haze SIP Narrative, August 28, 2008 

requiring new source review will be contacted and coordinated with to address visibility impacts 

on the Class 1 area.

8.0 REASONABLE PROGRESS GOALS 

Since there are no Class 1 areas in Mississippi, there are no reasonable progress goals for 

Mississippi to set. The goals for the Class 1 areas in neighboring states will be set by those 

states. Mississippi has worked collaboratively with all of the VISTAS states by meetings, 

conference calls and sharing Regional Haze SIP Pre-hearing Drafts. Because the state of 

Mississippi has no Class I areas in Mississippi, MDEQ worked with neighboring states on 

emissions contributions to Class I areas in neighboring states. Mississippi is in agreement with 

the Reasonable Progress Goals for the Class I areas in the neighboring states. 

9.0 MONITORING STRATEGY 

The State Implementation Plan is to be accompanied by a strategy for monitoring regional haze 

visibility impairment. Specifically, the Regional Haze Rule states at 40 CFR 51.308(d)(4): 

“(4) Monitoring strategy and other implementation plan requirements. 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. There are no Class 1 areas in Mississippi; therefore, no monitoring 

strategy is necessary. 

10.0 INTERSTATE CONSULTATION 

The VISTAS states have jointly developed the technical analyses to define the visibility 

improvement by 2018 under existing federal and state regulations compared to the uniform rate 

of progress, SO2 Areas of Influence for each Class I area, and methods to prioritize contributions 

from individual sources within the Areas of Influence. The states collectively accept the 

conclusions of these analyses. 

In December 2006 the VISTAS State Air Directors held their first formal consultation meeting to 

review the Base G modeling results and the SO2 Areas of Influence analyses. The Air Directors 

agreed to look at reasonable control measures for sources on the lists for the SO2 Areas of 

Influence. Each state would consider sources within their state and would identify sources in 

neighboring states that each state would like to have that neighboring state consider. States 
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acknowledged that the review process would differ among states since some Class I areas are 

projected to see visibility improvements near the uniform rate of progress while most Class I 

areas are projected to have greater improvements than uniform rate of progress. 

In January 2007, the States of Alabama, Florida, Louisiana, and Mississippi had a meeting to 

discuss the Breton Class 1 area. Since Louisiana is not part of VISTAS, this was the first 

meeting between all of the States surrounding Breton. The purpose was to better understand the 

conditions at Breton. There were no formal decisions made at the meeting. 

 In May 2007 the VISTAS State Air Directors met for their second formal interstate consultation. 

States shared their lists of sources in their state and neighboring states for each Class I area. The 

State Air Directors also shared their criteria for listing sources and their plans for further 

interstate consultation. 

In June 2007, there was a VISTAS meeting between the VISTAS states, USEPA, and the Federal 

Land Managers to discuss the expectations the various states, USEPA, and the FLMs with regard 

to the Class 1 areas and the Implementation Plans. Louisiana also attended this meeting. 

In October 2007, there was a consultation conference call that was called by Louisiana to 

Discuss Breton. The surrounding states, USEPA, and FLMs were on the call. 

The MDEQ has evaluated the impact of Mississippi sources on Class I areas in neighboring 

states and determined that there are no additional reasonable control measures that should be 

implemented to mitigate impacts in Class I areas in neighboring states. The MDEQ has consulted 

with the responsible states regarding its evaluation showing no cost-effective controls available 

for those units contributing at least one (1) percent to visibility impairment at Class I areas. 

Consultation documents may be found in Appendix J. 

11.0 COMPREHENSIVE PERIODIC IMPLEMENTATION PLAN 

REVISIONS 

40 CFR section 51.308(f) requires the regional haze implementation plan and submit a plan 

revision to USEPA by July 31, 2018 and every ten years thereafter. In accordance with the 

requirements listed in Section 51.308(f) of the federal rule for regional haze, Mississippi 

commits to revising and submitting this regional haze implementation plan by July 31, 2018 and 

every ten years thereafter. 

In addition, Section 51.308(g) requires periodic reports evaluating progress towards the 

reasonable progress goals established for each mandatory Class I area. In accordance with the 

requirements listed in Section 51.308(g) of the federal rule for regional haze, the MDEQ 

commits to submitting a report on reasonable progress to USEPA every five years following the 

initial submittal of the SIP. The report will be in the form of a SIP revision. The reasonable 

progress report will evaluate the progress made towards the reasonable progress goal for each 
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mandatory Class I area located outside Mississippi which may be affected by emissions from 

within Mississippi. 

The requirements listed in 51.308(g) include the following: 

1. Description of the status of implementation; 

2. Summary of emission reductions achieved thus far, including especially the status of 

implementation of the CAIR compliance plans for EGUs compared to the control 

assumed in the modeling. [The MDEQ recognizes that the 2018 projections of EGU 

controls from the IPM runs represent one solution to how the CAIR requirements will be 

met. By the time of the first periodic report, the MDEQ anticipates that the actual 

compliance strategy for the various utility companies will be much more defined. An 

assessment of those actual compliance plans will be done for the first periodic report.] 

3. Assessment of changes in visibility conditions at each class I area (current vs. baseline), 

expressed as 5-year averages of annual values for twenty (20) percent best and worst 

days; 

4. Analysis of emission changes over the 5-year period, identified by source or activity; 

5. Analysis of any siginificant changes in or out of the State which have impeded progress; 

6. Assessment of the sufficiency of the implementation plan to meet RPGs; 

7. Review and any modifications to our visibility monitoring plan. 

All requirements listed in 51.308(g) shall be addressed in the progress report. 

Since there are no Class 1 areas in Mississippi, also commits to ongoing consultation with the 

FLMs throughout the implementation process, including annual discussion of the 

implementation process and the most recent IMPROVE monitoring data and VIEWS data. 

There are several technical improvements that are recommended in the emissions inventory and 

air quality models that are used to support regulatory decisions for regional haze. These 

improvements recommended, as funding is available, to support the next long term strategy. The 

following is an overall summary; Appendix K contains a fuller discussion of possible technical 

improvements. 

First and foremost, continued improvements are needed in the integrated one-atmosphere air 

quality models that are used to project air quality responses to emissions reductions. As our 

understanding of partitioning between gaseous and aerosol phases improves, this understanding 

needs to be reflected in the models. Improvements can also be made in how the models handle 

individual pollutants. Sulfate performance for the CMAQ regional air quality model is good 

overall. However sulfate deposition is frequently overestimated in the models, particularly in the 

summer months. At the coastal sites, when winds are blowing from the Gulf of Mexico or 

Atlantic Ocean, CMAQ underestimates measured sulfate at the monitors. CMAQ’s processes 

also should be reviewed for sulfate formation over water. Nitrate is overestimated by the model 

in the winter and underestimated in the summer, although summer monitored values of nitrate 

are very low. Additional improvements in seasonal allocation of ammonia emissions would 

improve model estimates of ammonium nitrate formation. Organic carbon is generally 

underestimated in the summer months. Improvements are needed in the characterization of both 

primary carbon emissions and formation of secondary organic carbon. 
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Mississippi Regional Haze SIP Narrative, August 28, 2008 

Other improvements needed include better tools for organic carbon source apportionment, and 

more consistent measurement techniques between rural and urban monitoring networks. To 

improve our understanding of the contribution of fire from natural forest fires, prescribed 

burning, land clearing, and agricultural burning, states need improved record keeping. 

Additional improvements to international emissions inventory are also needed, to improve our 

understanding of boundary conditions for our modeling domain and of the contributions from 

international emissions to pollutant concentrations at the VISTAS Class I areas. 

12.0 DETERMINATION OF ADEQUACY OF THE EXISTING PLAN 

Depending on the findings of the five-year progress report, Mississippi commits to taking one of 

the actions listed in 40 CFR section 51.308(h). The findings of the five-year progress report will 

determine which action is appropriate and necessary. There are four options listed in the rule, 

but since there are no Class 1 areas in Mississippi, only the two listed below potentially apply. 

List of Possible Actions from 40 CFR section 51.308(h) 

1) MDEQ determines that the existing SIP requires no further substantive revision in order 

to achieve established goals MDEQ provides to the Administrator a negative declaration 

that further revision of the SIP is not needed at this time. 

2) MDEQ determines that the existing SIP is inadequate to ensure reasonable progress due 

to emissions within the state. MDEQ will revise its SIP to address the plan’s deficiencies 

within one year. 

Since there are no Class 1 areas in Mississippi, the determination of adequacy will have to be 

done in consultation with the States that the Class 1 areas are in and the FLMs.