Fine Particulate Matter (PM2.5) NAAQS

State Implementation Plan

For

The Tennessee Portion of the

Chattanooga, Tennessee-Georgia PM2.5 Nonattainment Area

Prepared by:

Chattanooga-Hamilton County Air Pollution Control Bureau

6125 Preservation Drive

Chattanooga, Tennessee 37416-3638

September 28, 2009
Page i

TABLE OF CONTENTS

List of Tables ................................................................................................................................ iii

List of Figures................................................................................................................................ iv

List of Appendices...........................................................................................................................v

Acknowledgements........................................................................................................................ vi

Executive Summary.........................................................................................................................1

1.0 Introduction.............................................................................................................................2

1.1 Fine Particulate Matter PM2.5.........................................................................................2

1.2 PM2.5 National Ambient Air Quality Standard ..............................................................3

1.3 Chattanooga, Tennessee-Georgia PM2.5 Nonattainment Area.......................................3

1.4 State Implementation Plan Requirements for PM2.5 Nonattainment Areas...................9

2.0 Attainment Modeling............................................................................................................10

2.1 Emissions Inventory.....................................................................................................10

2.1.1 2002 Emissions Inventory Development...........................................................11

2.1.2 Controls Applied................................................................................................15

2.1.3 2009 Emissions Inventory Development...........................................................17

2.2 Model Selection ...........................................................................................................22

2.2.1 Selection of Photochemical Grid Model............................................................23

2.2.2 Selection of Meteorological Model ...................................................................24

2.2.3 Selection of Emissions Processing System........................................................25

2.2.4 Selection of Modeling Year...............................................................................27

2.3 Modeling Domains.......................................................................................................28

2.4 Boundary Conditions...................................................................................................32

2.5 Initial Conditions .........................................................................................................32

2.6 Model Performance Evaluation ...................................................................................32

3.0 Attainment Demonstration....................................................................................................34

3.1 Speciated Modeled Attainment Test............................................................................34

3.2 Attainment Test Results...............................................................................................35

3.3 Supplemental Analyses/Weight of Evidence...............................................................36
Page ii

3.3.1 Emissions Reductions Not Modeled..................................................................37

3.3.2 Status of Modeled Emissions Reductions..........................................................43

3.3.3 Status of Attainment for Surrounding Counties.................................................43

4.0 PM2.5 RACT/RACM.............................................................................................................44

4.1 Permitted Stationary Sources.......................................................................................45

4.1.1 Local Regulations ..............................................................................................46

4.1.2 Sensitivity Modeling..........................................................................................47

4.2 Gasoline Dispensing Facilities.....................................................................................49

4.3 On-Road Mobile Sources.............................................................................................49

4.4 Non-Road and Stationary Internal Combustion Engines.............................................49

4.5 Open Burning...............................................................................................................50

4.6 Home Heating with Wood ...........................................................................................50

5.0 Motor Vehicle Emissions Budgets........................................................................................51

5.1 Transportation Conformity ..........................................................................................51

5.2 Transportation Budget for Hamilton County...............................................................51

5.3 Pollutants to Be Considered.........................................................................................51

5.3.1 Sulfur Dioxide (SO2)..........................................................................................51

5.3.2 Nitrogen Oxides (NOX)......................................................................................51

5.3.3 Volatile Organic Compounds (VOCs)...............................................................52

5.3.4 Ammonia............................................................................................................52

5.3.5 Road and Construction Dust..............................................................................52

6.0 Contingency Measures..........................................................................................................53

7.0 Reasonable Further Progress.................................................................................................54
Page iii

LIST OF TABLES

Table 1-1 Annual PM2.5 Design Values.......................................................................................4

Table 1-2 Components of Speciated PM2.5 Monitored at the Siskin Drive/UTC Site .................6

Table 2-1 Summary Emissions Inventory for 2002 for Hamilton County, Tennessee ..............12

Table 2-2 Summary Emissions Inventory for 2002 for Catoosa County, Georgia ....................12

Table 2-3 Summary Emissions Inventory for 2002 for Walker County, Georgia .....................13

Table 2-4 Summary Emissions Inventory for 2002 for Jackson County, Alabama...................13

Table 2-5 PM2.5 Emissions for 2002 by Emission Source Category..........................................14

Table 2-6 Sulfur Dioxide (SO2) Emissions for 2002 by Emission Source Category.................14

Table 2-7 Nitrogen Oxides (NOX) Emissions for 2002 by Emission Source Category.............14

Table 2-8 Ammonia Emissions for 2002 by Emission Source Category...................................15

Table 2-9 Summary Emissions Inventory for 2009 for Hamilton County, Tennessee ..............19

Table 2-10 Summary Emissions Inventory for 2009 for Catoosa County, Georgia ....................19

Table 2-11 Summary Emissions Inventory for 2009 for Walker County, Georgia .....................20

Table 2-12 Summary Emissions Inventory for 2009 for Jackson County, Alabama...................20

Table 2-13 PM2.5 Emissions for 2009 by Emission Source Category..........................................21

Table 2-14 Sulfur Dioxide (SO2) Emissions for 2009 by Emission Source Category.................21

Table 2-15 Nitrogen Oxides (NOX) Emissions for 2009 by Emission Source Category.............21

Table 2-16 Ammonia Emissions for 2009 by Emission Source Category...................................22

Table 2-17 Vertical Layer Definition for MM5 and CMAQ .......................................................31

Table 2-18 MFE and MFB for the Siskin Drive/UTC FRM (470654002) ..................................33

Table 3-1 2009 Quarterly Mean and Annual PM2.5 Design Values...........................................36

Table 3-2 2009 Modeled Species and PM2.5 Annual Design Values.........................................36

Table 3-3 Surrounding Area 2009 Modeled Annual PM2.5 Design Values ...............................43

Table 4-1 Maximum PM2.5 Concentration Reductions from Sensitivity Modeling...................48
Page iv

LIST OF FIGURES

Figure 1-1 Locations of Federal Reference Monitors in the Chattanooga, TennesseeGeorgia PM2.5 Nonattainment Area..............................................................................5

Figure 1-2 Continuous PM2.5 Monitor Frontal Passage Trace .......................................................8

Figure 2-1 MM5 Horizontal Domain (Blue) with Nested CMAQ 36-km Domain .....................29

Figure 2-2 ASIP/VISTAS Region 12-km Grid ............................................................................30

Figure 3-1 Hamilton County Emissions of PM2.5.........................................................................39

Figure 3-2 Hamilton County Emissions of PM10 .........................................................................39

Figure 3-3 Hamilton County Emissions of Sulfur Dioxide (SO2)................................................40

Figure 3-4 Hamilton County Emissions of Nitrogen Oxides (NOX)............................................40

Figure 3-5 Hamilton County Emissions of Toluene.....................................................................41

Figure 3-6 Hamilton County Emissions of Xylenes.....................................................................41

Figure 3-7 Hamilton County Emissions of Ammonia..................................................................42
Page v

LIST OF APPENDICES

Appendix 1 PM2.5 Conceptual Description

Appendix 2 Draft Documentation of the Base G2 and Best & Final 2002 Base Year, 2009 and 

2018 Emission Inventories for VISTAS

Appendix 3 Methodology for Augmenting State/Local/Tribal 1999 Point Source Emissions 

Inventories with PM10 and PM2.5 Emissions for the 1999 National Emissions 

Inventory

Appendix 4 VISTAS/ASIP Technical Support Documents

Appendix 5 Modeling Protocol for Association for Southeastern Integrated Planning (ASIP)

Appendix 6 Application of GEOS CHEM for 2002 Boundary Conditions for CMAQ 

Modeling of the VISTAS Region

Appendix 7 Local Area Modeling Performance

Appendix 8 Hamilton County SMAT Process

Appendix 9 Letter from Bowater Newsprint – Calhoun Operations

Appendix 10 Chattanooga-Hamilton County Air Pollution Control Industrial Point Source 

Emissions

Appendix 11 EPA NEI PM2.5 Document

Appendix 12 RACT Industrial Point Source Review

Appendix 13 House Heating Fuel – 2000 U.S. Census

Appendix 14 Planning Assumptions for Development of 2009 CHCNGA TPO TransCAD 

Model 2009 Emissions Results

Appendix 15 NOX Insignificance Demonstration
Page vi

ACKNOWLEDGEMENTS: VISTAS CONTRACTORS

VISTAS Technical Coordinator, Pat Brewer, NOX Insignificance Evaluation

Air Resource Specialists: Monitoring Data Analysis

Alpine Geophysics: Emissions AND Air Quality Modeling, Technical Advisor for Emissions 

Inventory

Atmospheric Research and Analysis, Inc.: Operation of continuous monitors - Millbrook, NC

Baron Applied Meteorology: Meteorological Modeling

Desert Research Institute: Carbon Source Attribution including sample filter preparation, 

sample analysis using Gas Chromatography and Mass Spectrometry, source attribution using 

Chemical Mass Balance analyses and Positive Matrix Factorization

Earth Tech, Inc: BART Modeling, CALPUFF Training

ENVIRON: Emissions and Air Quality Modeling

Georgia Institute of Technology: Emissions and Air Quality modeling sensitivities

Harvard University: GEOS-Chem global model

ICF Consulting: Integrated Planning Model for future electric utility generation

MACTEC: 2002, 2009, and 2018 Emissions Inventory and Projections, CALPUFF training

E.H. Pechan and Associates: 2002 Mobile Inventory

Research Triangle Institute: Chemical Analysis of Monitoring Samples

System Applications International: Meteorological Characterization 

Tennessee Valley Authority: Operation of continuous monitors at Great Smoky Mountain 

National Park and preparation of final project report and draft manuscript 

TRC, Inc: BART Modeling

University of California, Riverside: Emissions and Air Quality Modeling

Woods Hole: Analysis of Carbon 14 isotope in carbon samples as part of carbon source 

attribution project
C-HCAPCB -1- PM 2.5 SIP

EXECUTIVE SUMMARY

On January 5, 2005, the United States Environmental Protection Agency (EPA) published the 

fine particulate matter (PM2.5) nonattainment designation for the Chattanooga, TennesseeGeorgia area. This area consists of Hamilton County in Tennessee, Catoosa and Walker 

Counties in Georgia, and the portion of Jackson County in Alabama that is described as U.S.

Census 2000 block group identifier 01–071-9503–1. Between 2001 and 2003, air quality 

monitoring within this area indicated that the annual average PM2.5 concentrations (design 

values) exceeded the 15.0 μg/m3 National Ambient Air Quality Standard (NAAQS). The 

Chattanooga-Hamilton County Air Pollution Control Bureau, the Tennessee Division of Air 

Pollution Control, the Georgia Air Protection Branch, and the Alabama Department of 

Environmental Management have collaborated to develop a PM2.5 NAAQS State Implementation 

Plan (SIP) for each jurisdiction. This document contains the SIP for the Hamilton County, 

Tennessee portion of the nonattainment area.

Air quality modeling conducted for Hamilton County by the Association for Southeastern 

Integrated Planning (ASIP) indicates that the nonattainment area will attain the annual NAAQS 

in 2009. The model results are based upon projected 2002-2009 emissions reductions from 

sources within the area and are supported by downward trends in actual emissions. Hamilton 

County expects to attain the PM2.5 NAAQS based upon implementation of Federal and regional 

measures. The 2009 modeled PM2.5 design values are provided below.

2009 Modeled Annual PM2.5 Design Values

Federal Reference Monitor PM2.5 Design Value (μg/m3)

Siskin Drive/UTC (470654002) 13.6

Maxwell Road/East Ridge (470650031) 14.4

Soddy-Daisy High School (470651011) 12.3

Walker County, Georgia (132950002) 13.9

As required by the EPA Clean Air Fine Particle Implementation Rule, sources of PM2.5 and its 

precursors within Hamilton County were evaluated to verify that they were meeting at least 

reasonably available control measures (RACM) levels of emission controls. This evaluation and 

the results of sensitivity modeling that was performed indicate that no additional reductions are 

available from local sources that would result in advancement of the attainment date to earlier 

than 2009.
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1.0 INTRODUCTION

1.1 Fine Particulate Matter (PM2.5)

Fine particulate matter, also known as fine particles and PM2.5, refers to airborne particles less 

than or equal to 2.5 micrometers (μm) in diameter. Fine particles are treated as though they are a 

single pollutant, but they come from many different sources and are composed of many different 

compounds. PM2.5 exposure adversely affects human health, especially respiratory and 

cardiovascular systems. Individuals particularly sensitive to PM2.5 exposure include children, 

people with heart and lung disease, and older adults.

PM2.5 can be liquid, solid, or can have a solid core surrounded by liquid. PM2.5 can include 

material produced by combustion, photochemical reactions, and can contain salt from sea spray

and soil like particles. Particles are distinguished based on the method of formation. Primary 

particles are particles directly emitted into the atmosphere and retain the same chemical 

composition as when they were released. Secondary particles are those formed through chemical 

reactions involving atmospheric oxygen, water vapor, hydroxyl radical, nitrates, sulfur dioxide 

(SO2), nitrogen oxides (NOX), and organic gases from natural and anthropogenic sources. PM2.5

can therefore be composed of varying amount of different species, including:

 Sulfates

 Nitrates (usually found in the form of ammonium nitrate)

 Ammonium

 Hydrogen ion

 Particle bound water

 Elemental carbon

 Organic compounds

o Primary organic species (from cooking and combustion)

o Secondary organic compounds

 Crustal material (includes calcium, aluminum, silicon, magnesium, and iron)

 Sea salt (generally only found at coastal monitoring sites)

 Transitional metals

 Potassium (generally from wood burning or cooking)

The most significant sources of PM2.5 and its precursors are coal-fired power plants, industrial 

boilers, and other combustion sources. These emissions are often transported over large 

distances. Other sources of PM2.5 emissions include mobile sources, area sources, biogenic 

sources, fires, wind blown dust, and oceans.
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A variety of meteorological and geographic factors influences the concentration levels of fine 

particles, including both the regional and local distribution of urbanized areas, primary and 

precursor emissions sources, and natural features such as oceans and forests. Since PM2.5

concentrations can exceed the National Ambient Air Quality Standards (NAAQS) at any time of 

the year, the United States Environmental Protection Agency (EPA) mandates the year round 

monitoring of the pollutant throughout the country (40 CFR 58, App. D).

1.2 PM2.5 National Ambient Air Quality Standard

In July 1997, the EPA established both annual and 24-hour fine particulate primary (healthbased) and secondary NAAQS for annual and 24-hour fine particulate. The secondary PM2.5

standards, established for the protection of public welfare and the environment, were established 

at the same levels as the primary standards. After review, the EPA revised the 24-hour standard 

in October 2006, but the annual standard remained the same. The 24-hour standard (as revised in 

2006) is met when the 3-year average of a monitoring site's annual 98th percentile value is 35 

micrograms per cubic meter (μg/m3) or less. The annual standard is met when the 3-year average 

of a monitoring site's annual mean concentration is 15.0μg/m3or less. The 3-year averages at 

each monitoring site (of annual means or 98th percentiles) are called design values. The design 

value for an entire area is the single highest design value among the monitoring sites located in 

the area.

Since the 1977 amendments to the Clean Air Act (CAA), areas of the country that violated the 

ambient standard for a particular pollutant were formally designated as nonattainment for that 

pollutant. This formal designation concept was retained in the 1990 Amendments (CAAA). 

With the implementation of the PM2.5 standard, areas designated nonattainment under Section 

172 of the CAAA (Subpart 1) have five years from designation to attain the standard.

1.3 Chattanooga, Tennessee-Georgia PM2.5 Nonattainment Area

The EPA does not plan to designate geographic areas as attainment or nonattainment for the 

2006 24-hour PM2.5 standard until December 2008 or later. Therefore, this State Implementation 

Plan (SIP) does not address attainment and/or nonattainment issues with the 24-hour standard.

On January 5, 2005, EPA published the annual PM2.5 nonattainment designation for the 

Chattanooga, Tennessee-Georgia area. This area consists of Hamilton County in Tennessee, 

Catoosa and Walker Counties in Georgia, and the portion of Jackson County in Alabama that is 

described as U.S. Census 2000 block group identifier 01–071-9503–1. Although Jackson 

County is not contiguous to the rest of the nonattainment area, a coal-fired power plant located in 

this census tract is a major contributor to the PM2.5 problem. The effective date of the 

nonattainment designation was April 5, 2005, and was based on air quality monitoring for the 

years 2001, 2002, and 2003.

Four PM2.5 federal reference monitors are located in the nonattainment area – three in Hamilton 

County and one in Walker County. Federal reference monitors (FRM) collect samples that are 

used to determine if an area is in attainment with the PM2.5 NAAQS. A list of the monitors and 
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associated design values is provided below in Table 1-1. The FRM located at Soddy-Daisy High 

School is at the most rural site of the three Hamilton County FRMs and has always shown 

attainment. The other three monitors show exceedances of the annual standard for the 2001-

2003 averaging period, which is the period the EPA used in the designation of the nonattainment 

area. The locations of the four FRMs in the nonattainment area are shown in Figure 1-1, which 

follows.

Table 1-1. Annual PM2.5 Design Values

Federal Reference Monitor

PM2.5 Design Value (μg/m3)

2001-2003* 2002-2004 2003-2005 2004-2006

Siskin Drive/UTC (470654002) 15.2 14.7 15.0 15.1

Maxwell Road/East Ridge (470650031) 16.1 15.7 16.1 15.5

Soddy-Daisy High School (470651011) 14.1 13.8 13.8 13.5

Walker County, Georgia (132950002) 15.5 15.2 15.8 15.2

*Averaging period used by the EPA in the nonattainment area designation
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Figure 1-1. Locations of Federal Reference Monitors in the

Chattanooga, Tennessee-Georgia PM2.5 Nonattainment Area
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As mentioned in Section 1.1 of this document, PM2.5 is composed of many species from varying 

sources. In order to fully understand the nature of the problem in Hamilton County and to 

ascertain an appropriate response, the PM2.5 components must be determined. Fine particulate

speciation monitors are collocated with the FRMs at the Siskin Drive/UTC and Walker County, 

Georgia, sites. The speciation monitor located at the Siskin Drive/UTC site is part of the EPA 

Speciation Trends Network (STN). Speciation monitors provide concentrations of total PM2.5, 

ammonium, potassium, sodium, nitrates, sulfates, elemental carbon, organic carbon, and fortyseven metals. Major components of PM2.5 from the Siskin Drive/UTC speciation monitor are 

shown below in Table 1-2.

Table 1-2. Components of Speciated PM2.5 Monitored at the Siskin Drive/UTC Site

Year

Concentration (μg/m3)

Total 

PM2.5

Organic 

Carbon Sulfates Nitrates Ammonium Elemental Carbon

2002 16.90 5.34 4.99 0.95 1.65 0.66

2003 17.55 5.46 5.11 1.26 1.85 0.75

2004 15.26 4.40 4.85 1.18 1.63 0.65

2005 17.84 4.94 5.39 1.10 1.88 0.68

Air emissions from both regional and local sources contribute to the nonattainment problem in 

Hamilton County. The two major components of the speciated total PM2.5 are organic carbon 

and sulfates. Organic carbon makes up approximately thirty percent of the speciated PM2.5. The

organic carbon is composed of both primary PM2.5, such as direct emissions from engines, and 

secondary PM2.5 that results from atmospheric reactions of precursors. The organic carbon from 

diesel engines includes unburned fuel and engine lubrication oil. Many diesel engines vent 

crankcase emissions to the atmosphere. Two cycle engines have lubricating oil mixed with their 

fuel resulting in emissions of unburned lubricating oil. Aromatic compounds, biogenic 

compounds, and organic products of incomplete combustion are examples of secondary PM2.5

precursors. Aromatic compounds include toluene, xylenes, and trimethylbenzenes that are 

emitted from industrial sources and form secondary organic aerosols. Biogenic compounds 

include terpenes and sesquiterpenes that are emitted by trees and other vegetation. As shown by

the EPA’s Biogenic Emission Inventory System (BEIS3.09) model, organic carbon from 

biogenic precursors accounts for a significant portion of the organic carbon in the nonattainment 

area between March and December. Forest fires, prescribed burning, and home heating with 

wood are all sources of organic products of incomplete combustion. Prescribed burns in 

Hamilton County are normally conducted in the spring and fall. Significant home heating in this 

area is performed for five months of the year.

Sulfates are formed from atmospheric reactions of SO2 and also make up approximately thirty 

percent of the total PM2.5 at the monitor. Some of these reactions also involve ammonia. The 

primary sources of SO2 in Hamilton County include industrial combustion equipment and mobile 

sources. Most industrial sources in Hamilton County use natural gas as the primary fuel. Since 
C-HCAPCB -7- PM 2.5 SIP

natural gas contains a negligible amount of sulfur, minimal SO2 emissions result from its 

combustion. When natural gas is curtailed, some industrial sources use fuel oil as a backup. 

Number 2 fuel oil typically contains no more than 0.2% sulfur, but Number 6 fuel oil could 

contain up to two percent sulfur. There is also some industrial use of coal as a fuel in Hamilton 

County. The combustion of Number 2 and Number 6 fuel oils and coal results in increasingly 

higher levels of SO2 emissions than those from natural gas. However, the SO2 emissions from 

combined industrial and mobile sources within Hamilton County are significantly less than those 

from regional coal-fired electric utilities, none of which are located in the county. In 2002, the 

combined SO2 emissions from all sources within Hamilton County were less than ten percent of 

the SO2 emissions from the TVA Widows Creek Fossil Plant in Jackson County, Alabama, 

which is the closest of four regional coal-fired power plants located within 75 miles of the 

county.

Nitrates, which make up less than ten percent of the speciated PM2.5, are formed from 

atmospheric reactions of NOX with ammonia. Combustion processes are the primary source of 

NOX emissions both inside and outside the county. These processes include on-road mobile 

sources; non-road mobile sources; space heating; industrial processes; forest fires; and burning of 

vegetation. Regional coal-fired electric generation plants located outside the county also 

contribute NOX emissions.

The ammonia that reacts with NOX and SO2 to form ammonium nitrate and ammonium sulfate, 

respectively, is produced primarily from automobile catalysts, sewage treatment, and agriculture 

sources both locally and regionally. Elemental carbon, or soot, makes up a small portion of the 

total PM2.5 and is usually formed by incomplete combustion of fuels such as gasoline or diesel 

fuel.

Once PM2.5 is emitted to or formed in the atmosphere, it may remain suspended for weeks, but is 

eventually removed by either dry or wet deposition. The concentration in the air is dependent on 

wind and weather conditions. If there is no wind, the PM2.5 remains in the vicinity, and the 

concentration continues to rise until reaching a state of equilibrium in which the rate of 

deposition is equal to the rate of development of fine particulate. When weather fronts pass 

through the Hamilton County area, monitored increases in PM2.5 are observed followed by rapid 

decreases with the frontal passage. One example of this phenomenon is charted in Figure 1-2, 

which follows. The profile is for a day during which the National Oceanic and Atmospheric 

Administration weather records for February 13, 2007, indicate the passage of a front between 

10:53 AM and 11:53 AM. The characteristic rapid drop in PM2.5 is shown beginning at that time 

by the green line labeled RIV, which is the output of a continuous PM2.5 monitor located at the 

Siskin Drive/UTC site.
C-HCAPCB -8- PM 2.5 SIP

Figure 1-2. Continuous PM2.5 Monitor Frontal Passage Trace

A study performed for the Visibility Improvement State and Tribal Association of the Southeast 

(VISTAS), Characterization of Meteorology and its Relationship to Fine Particulate Mass and 

Visibility in the VISTAS Region, was completed on December 8, 2006. The analysis was 

conducted over the VISTAS sites and included specific information for Hamilton County. The 

study showed that high PM2.5 concentrations in the area are associated with the following:

 Moderate temperatures

 Low surface or aloft wind speeds

 South surface winds

 East aloft winds

 Stable atmospheric conditions

 Very high PM2.5 concentrations on the previous day

A local surface wind study using Chattanooga/Lovell Field data conducted by the Southern 

Regional Climate Center showed calm winds 26.27% of the time with a mean wind of 6.28 

knots. The most common direction for surface winds was from the south. This study used wind 

data from 1984 through 1992.

Appendix 1 provides further conceptual information on ambient PM2.5 concentrations in 

Hamilton County.
C-HCAPCB -9- PM 2.5 SIP

1.4 State Implementation Plan Requirements for PM2.5 Nonattainment Areas

The April 5, 2007, EPA Clean Air Fine Particle Implementation Rule (PM2.5 Implementation 

Rule) requires that a State Implementation Plan (SIP) be developed and submitted to the EPA no 

later than three years from the date of nonattainment designation. A SIP documents how and 

when an area will be brought into attainment with a national air quality standard. There are 

several required elements in the PM2.5 SIP. These include an emissions inventory, a modeled 

attainment demonstration, an analysis of reasonably available control technologies (RACT) and 

reasonably available control measures (RACM), and the adoption of the RACT/RACM levels of 

emission controls if the addition of those controls could move up the attainment date by a year.

The PM2.5 Implementation Rule establishes a hierarchy of precursor pollutants for PM2.5: SO2 is 

always considered a precursor, NOX is presumptively a precursor, and VOCs and ammonia are 

presumed not to be precursors. The rule allows States to exempt NOX by demonstrating that 

NOX emissions are not a significant contributor to an area’s PM2.5 nonattainment problem and 

that the area is not a source of a PM2.5 transport problem. 

The rule also requires that contingency measures be included in the SIP for areas designated 

nonattainment for PM2.5. The contingency measures are to be implemented in the event the 

nonattainment area does not meet attainment by the date specified in the SIP.
C-HCAPCB -10- PM 2.5 SIP

2.0 ATTAINMENT MODELING

In 2001, the southeastern states formed the Visibility Improvement State and Tribal Association 

of the Southeast (VISTAS) to address compliance with the Regional Haze Rule that was 

published in 1999 (64 FR 35714). The member states are Alabama, Florida, Georgia, Kentucky, 

Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia. VISTAS 

found that the modeling requirements for the Regional Haze Rule were similar to the 

requirements for the modeled attainment demonstration for PM2.5 nonattainment areas. The 

member states formed a new organization, the Association for Southeastern Integrated Planning 

(ASIP), in order to conduct modeled attainment demonstrations for the PM2.5 nonattainment 

areas. VISTAS and ASIP used the same emissions inventory and model.

As required by the EPA’s April 2007 Guidance on the Use of Models and Other Analyses for 

Demonstrating Attainment Goals for Ozone, PM2.5, and Regional Haze (Attainment Modeling 

Guidance), modeling data files are archived and will be maintained by Tennessee Division of Air 

Pollution Control at 615-532-0554.

2.1 Emissions Inventory

An emissions inventory is a comprehensive quantification of all emissions in a region that cause 

or contribute to a nonattainment area failing to meet an air standard. In modeled attainment 

demonstrations, the emission inventory is developed for a past year so that emissions can be 

quantified as accurately as possible. For the annual PM2.5 standard, the EPA provided guidance 

for selecting the past (base) year. The base year was recommended to be 2002 as per a 

November 18, 2002, letter titled “2002 Base Year Emission Inventory SIP Planning: 8-hr Ozone, 

PM2.5, and Regional Haze Programs” signed by Lydia N. Wegman. Both National Emission 

Inventory (NEI) data and monitored PM2.5 values were available for the 2002 base year.

VISTAS developed a regional emissions inventory, which included input from each member 

state air agency as well as input from the local agencies in Davidson County, TN, Hamilton 

County, TN, Shelby County, TN, Knox County, TN, Jefferson County, AL, Jefferson County, 

KY, Buncombe County, NC, Forsyth County, NC and Mecklenburg County, NC. A detailed

discussion of the inventory development is provided in the Documentation of the Base G 2002 

Base Year, 2009 and 2018 Emission Inventories for VISTAS located in Appendix 2.

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

sources (including stationary area sources), off-road and on-road mobile sources, and biogenic 

sources. In Hamilton County, stationary point sources have a fixed location and require permits 

to operate unless they have been defined as “insignificant activities” in the local air pollution 

control regulations. Industrial sources make up the bulk of stationary point sources in the 

county, and their emissions are inventoried annually. Electric generating units (EGUs) are the 

single largest contributor to PM2.5 from point source emissions in the region. No EGUs are 

located in Hamilton County.

Area sources in Hamilton County include stationary area sources, fires, animal husbandry, and 

paved and unpaved roads. Stationary area sources are those sources whose individual emissions 
C-HCAPCB -11- PM 2.5 SIP

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

the source category could be significant. For example, dry cleaners and service stations are 

stationary area sources found in Hamilton County.

Non-road (or off-road) mobile sources are equipment that move but do not use the roadways, 

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

On-road mobile sources are automobiles, buses, trucks, and motorcycles that use the roadway

system. Emissions from on-road sources are estimated by vehicle type and road type. Biogenic 

sources are natural sources like trees, crops, grasses, and the natural decay of plants. Emissions 

from non-road, on-road, and biogenic sources are estimated county wide.

2.1.1 2002 Emissions Inventory Development

The starting point of the 2002 emissions inventory was EPA’s 1999 NEI. Several agencies 

provided more recent inventories. Selected large ammonia sources were updated, 2002 

continuous emissions monitoring based SO2 and NOX emissions were added for electric utilities, 

emissions of PM2.5 and PM10 (particulate matter less than or equal to 10 μm in diameter) were 

added if not in the submittal, and quality assurance/quality control checks were performed.

The “Base G” emissions inventory was released in August 2006 and, where appropriate, 

incorporated 2002 NEI submittals (including Hamilton County’s NEI submittal). However it 

was still necessary, in finalizing the inventory, to augment stationary point source emissions in 

accordance with Appendix C of EPA’s Documentation of the Final 1999 National Emissions 

Inventory (Version 3) for Criteria Pollutants and Ammonia – Point Sources, which can be found 

in Appendix 3. For EGUs, normalization factors were developed for producing a 2002 typical 

year inventory. The normalization factor is derived by averaging the 2000 to 2004 heat input 

and then dividing the result by the actual 2002 heat input. If the unit did not operate all five 

years, then the average heat input was only calculated for the years it operated. The final version 

of the emissions inventory is Base G4, which was used for the modeled attainment 

demonstration.

Stationary area source emissions, which were submitted to comply with the Consolidated 

Emissions Reporting Rule (CERR), were obtained from the EPA. The emissions were evaluated 

and missing data added. A “typical” fire year inventory was developed covering wildfires, 

prescribed burning, agricultural fires, and land clearing fires. Ammonia emissions from 

livestock and fertilizers were calculated using Version 3.6 of the Carnegie Mellon University

ammonia model. Paved and unpaved road emissions were estimated using EPA approved 

methodology.

Most non-road emissions were estimated using the EPA’s NONROAD2005c model. Aircraft 

engines, railroad locomotives, and commercial marine emissions were not included in the 

NONROAD model and were estimated separately. These “other non-road” emissions were 

based on emissions estimates developed for the EPA’s 1999 NEI Version 2. Mobile6.2 was used 

to estimate emissions from on-road mobile sources. Biogenic emissions were estimated using 

the BEIS3.09 model. Tables 2-1 through 2-8 summarize the emissions inventory used in the 
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2002 model. This data reflects best data available with some data from modeling, some 

calculated and some CEM data.

Table 2-1. Summary Emissions Inventory for 2002 for Hamilton County, Tennessee

Table 2-2. Summary Emissions Inventory for 2002 for Catoosa County, Georgia
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Table 2-3. Summary Emissions Inventory for 2002 for Walker County, Georgia

Table 2-4. Summary Emissions Inventory for 2002 for Jackson County, Alabama
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Table 2-5. PM2.5 Emissions for 2002 by Emission Source Category

County

PM2.5 Emissions (tons)

Point Area Non-road On-road Total

Hamilton, TN 567 1,000 292 183 2,042

Catoosa, GA 0 675 37 37 750

Walker, GA 2 920 19 29 970

Jackson, AL 963 1,209 88 41 2,301

Total 1,532 3,804 437 291 6,064

Table 2-6. Sulfur Dioxide (SO2) Emissions for 2002 by Emission Source Category

County

Sulfur Dioxide (SO2) Emissions (tons)

Point Area Non-road On-road Total

Hamilton, TN 1,721 507 539 461 3,228

Catoosa, GA 0 272 51 92 415

Walker, GA 203 761 21 71 1,056

Jackson, AL 45,357 576 167 99 46,199

Total 47,281 2,115 778 723 50,898

Table 2-7. Nitrogen Oxides (NOX) Emissions for 2002 by Emission Source Category

County

Nitrogen Oxides (NOX) Emissions (tons)

Point Area Non-road On-road Total

Hamilton, TN 2,856 639 6,428 11,610 21,532

Catoosa, GA 0 162 671 2,377 3,211

Walker, GA 46 384 269 1,699 2,398

Jackson, AL 26,862 310 1,418 2,195 30,785

Total 29,763 1,495 8,787 17,881 57,926
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Table 2-8. Ammonia Emissions for 2002 by Emission Source Category

County

Ammonia Emissions (tons)

Point Area Non-road On-road Total

Hamilton, TN 17 172 2.1 357 549

Catoosa, GA 0 468 0.2 74 542

Walker, GA 0 763 0.3 56 819

Jackson, AL 2 1,280 0.6 77 1,361

Total 20 2,684 3.2 563 3,270

2.1.2 Controls Applied

Several control measures already in place or being implemented over the next few years will 

reduce stationary point, highway mobile, and non-road mobile sources emissions. The Federal 

control measures that have impacts on air quality in Hamilton County were incorporated into the 

Base G4 emissions inventory and are discussed in the following sections.

Tier 2 Vehicle Standards

Federal Tier 2 vehicle standards will require all passenger vehicles in a manufacturer’s fleet, 

including light-duty trucks and sport utility vehicles (SUVs), to meet an average standard of 0.07 

grams of NOX per mile. Implementation began in 2004, and was to be completely phased in by

2007. The Tier 2 standards will also cover passenger vehicles over 8,500 pounds gross vehicle 

weight rating (the larger pickup trucks and SUVs), which are not covered by the current Tier 1 

regulations. For these vehicles, the standards will be phased in beginning in 2008, with full 

compliance in 2009. The new standards require vehicles to be seventy-seven percent to ninetyfive percent cleaner than those on the road today. The Tier 2 rule also reduced the sulfur content 

of gasoline to thirty parts per million (ppm) starting in January of 2006. Most gasoline sold in 

Hamilton County prior to January 2006 had a sulfur content of about 300 ppm. Sulfur occurs 

naturally in gasoline, but interferes with the operation of catalytic converters on vehicles 

resulting in higher NOX emissions. Lower-sulfur gasoline is necessary to achieve the Tier 2 

vehicle emission standards.

Heavy-Duty Diesel Highway Vehicles Standards

New EPA standards designed to reduce NOX and volatile organic compound (VOC) emissions 

from heavy-duty gasoline and diesel highway vehicles began to take effect in 2004. A second 

phase of standards and testing procedures, which began in 2007, will reduce particulate matter 

emissions from heavy-duty highway engines and will also reduce highway diesel fuel sulfur 

content to fifteen ppm since the sulfur damages the particulate filters that are required to meet the 

new standard. The total program is expected to achieve a ninety percent reduction in particulate 
C-HCAPCB -16- PM 2.5 SIP

matter emissions and a ninety-five percent reduction in NOX emissions for these new engines 

using low-sulfur diesel fuel, compared to existing engines using higher-sulfur content diesel fuel.

Large Non-road Diesel Engines Rule

In May 2004, the EPA promulgated new rules for large non-road diesel engines, such as those 

used in construction, agricultural, and industrial equipment, to be phased in between 2008 and 

2014. The non-road diesel rules also reduce the allowable sulfur in non-road diesel fuel by over 

ninety-nine percent. Non-road diesel fuel currently averages 3,400 ppm sulfur. The rule limits 

non-road diesel sulfur content to 500 ppm in 2006 and 15 ppm in 2010. The combined engine 

and fuel rules would reduce NOX and particulate matter emissions from large non-road diesel 

engines by over ninety percent, compared to current engines using higher-sulfur content diesel

fuel.

Non-road Spark-Ignition Engines and Recreational Engines Standard

The new standard, effective in July 2003, regulates emissions of NOX, hydrocarbons, and carbon 

monoxide for groups of previously unregulated non-road engines. The new standard will apply 

to all new engines sold in the United States and imported after these standards began and will 

apply to large spark-ignition engines (forklifts and airport ground service equipment), 

recreational vehicles (off-highway motorcycles and all-terrain-vehicles), and recreational marine 

diesel engines. The regulation varies based upon the type of engine or vehicle.

The large spark-ignition engines contribute to ozone formation and ambient carbon monoxide

and particulate matter levels in urban areas. Tier 1 of this standard was implemented in 2004 and 

Tier 2 started in 2007. Like the large spark-ignition, recreational vehicles contribute to ozone 

formation and ambient carbon monoxide and particulate matter levels. For the model year 2006 

off-highway motorcycles and all-terrain-vehicles, the new exhaust emissions standard was 

phased-in by fifty percent and for model years 2007 and late, by one hundred percent. 

Recreational marine diesel engines over thirty-seven kilowatts are used in yachts, cruisers, and 

other types of pleasure craft. Recreational marine engines contribute to ozone formation and 

particulate matter levels, especially in marinas. Depending on the size of the engine, the 

standard began phasing-in in 2006. When all of the non-road spark-ignition engines and 

recreational engines standards are fully implemented, an overall seventy-two percent reduction in 

emissions of hydrocarbons, eighty percent reduction in NOX emissions, and fifty-six percent

reduction in carbon monoxide emissions are expected by 2020. These controls will help reduce 

ambient concentrations of ozone, carbon monoxide, and PM2.5.

NOX SIP Call

In October 1998, the EPA made a finding of significant contribution of NOX emissions from 

certain states and published a rule that set ozone season NOX budgets for the purpose of reducing 

regional transport of ozone (63 FR 57356). This rule, referred to as the “NOX SIP Call,” called 

for ozone season controls to be put on utility and industrial boilers, as well as internal 

combustion engines in twenty-two states in the eastern United States. A NOX emissions budget 
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was set for each state, and the states were required to develop rules that would allow the state to 

meet their budget. The emission budgets were to be met by the beginning of 2004. The NOX

SIP Call resulted in regional reductions pf PM2.5 and PM2.5 precursors that reduced PM2.5 in this 

nonattainment area. 

Clean Air Interstate Rule

On May 12, 2005, the EPA promulgated the “Rule to Reduce Interstate Transport of Fine 

Particulate Matter and Ozone (Clean Air Interstate Rule); Revisions to Acid Rain Program; 

Revisions to the NOX SIP Call,” referred to as CAIR. This rule established the requirement for

States to adopt rules limiting NOX and SO2 emissions and a model rule for the states to use in 

developing their rules. The purpose of the CAIR is to reduce interstate transport of precursors to 

fine particulate and ozone. The CAIR applies to certain large fossil-fuel fired boilers and 

turbines that serve electricity generators.

This rule provides annual state caps for NOX and SO2 in two phases, with the Phase I caps for 

NOX and SO2 starting in 2009 and 2010, respectively. Phase II caps become effective in 2015. 

The EPA is allowing the caps to be met through a cap and trade program if a state chooses to 

participate in the program. When fully implemented, the CAIR will reduce SO2 emissions in the 

eastern United States by over seventy percent and NOX emissions by over sixty percent from 

2003 levels.

Though the rule was remanded to EPA by the U.S. Court of Appeals for the District of 

Columbia, TVA is continuing to operate their controls set forth in the CAIR rule pending a new 

rule being developed. These controls have resulted in regional reductions of both nitrates and 

sulfates in the area.

2.1.3 2009 Emissions Inventory Development

A regional emissions inventory was developed for the 2009 modeling. Projections for EGUs, 

non-EGU point sources, area sources, non-road, and on-road mobile sources were used to 

produce a 2009 emission inventory. Future EGU emissions were estimated using the EPA 

Integrated Planning Model, which is used to examine air pollution control policies for various 

pollutants for the entire electric power system throughout the contiguous United States. The 

general approach for future year non-EGU point source emissions projections was to use growth 

and control data consistent with the data used in EPA’s Clean Air Interstate Rule analysis, and 

supplement these data with stakeholder input. The following activities were performed for nonEGU point sources.

 Obtained, reviewed, and applied the most current growth factors developed by EPA

 Obtained, reviewed and applied any state-specific, or sector specific growth factors 

submitted by stakeholders

 Obtained and incorporated information on sources that shutdown after 2002 and set their 

emissions to zero in the projection inventories
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 Obtained, reviewed, and applied control assumptions for programs that are presently 

adopted and controls that have future compliance dates. Since the modeling dealt with 

controls that are presently required to be operated and controls that will be operated in a 

future year as the future year modeling was conducted for 2009 and 2018.

For area source categories, except fires, VISTAS/ASIP generated future emissions were based on 

the 2002 inventory year. Growth factors supplied by the states or the CAIR emission projections 

were applied to project the controlled emissions to the appropriate year. In some cases, the 

EPA’s Economic Growth and Analysis System Version 5 growth factors were used if no growth 

factor was available from either the states or the CAIR growth factor files. For fires, the 

“typical” year inventory developed in 2002 was used.

For source categories with emissions estimated using the EPA’s NONROAD model, the model 

growth assumptions were used to create the 2009 future year inventory. The NONROAD model 

takes into consideration regulations affecting emissions from these categories. For the 

commercial marine, railroad locomotives, and airport emissions, VISTAS 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.

MOBILE6.2, which takes into consideration regulations that affect emissions from this source 

category, was used to estimate emissions for on-road mobile source emissions in the 2009 

inventory. The vehicle miles traveled (VMT) input from the MOBILE6.2 2002 base year 

inventory provided the basis for the initial 2009 VMT input. The 2009 VMT estimate assumed a 

linear growth rate for each state, county, and vehicle type as derived from the VMT data 

assembled by the EPA for their most recent heavy-duty diesel rulemaking. In the final 2009 

VMT input estimate for MOBILE6.2, several states provided independent forecast data to either 

replace or augment the forecast data based on the heavy-duty diesel rule. Tables 2-9 through 

2-16 summarize the emissions inventory that was used for the 2009 model.
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Table 2-9. Summary Emissions Inventory for 2009 for Hamilton County, Tennessee

Table 2-10. Summary Emissions Inventory for 2009 for Catoosa County, Georgia
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Table 2-11. Summary Emissions Inventory for 2009 for Walker County, Georgia

Table 2-12. Summary Emissions Inventory for 2009 for Jackson County, Alabama
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Table 2-13. PM2.5 Emissions for 2009 by Emission Source Category

County

PM2.5 Emissions (tons)

Point Area Non-road On-road Total

Hamilton, TN 504 1,073 243 131 1,951

Catoosa, GA 0 731 33 27 792

Walker, GA 1 988 15 21 1,025

Jackson, AL 1,156 1,252 70 30 2,507

Total 1,661 4,044 360 209 6,274

Table 2-14. Sulfur Dioxide (SO2) Emissions for 2009 by Emission Source Category

County

Sulfur Dioxide (SO2) Emissions (tons)

Point Area Non-road On-road Total

Hamilton, TN 1,700 541 223 54 2,517

Catoosa, GA 0 273 9 11 292

Walker, GA 195 762 4 8 969

Jackson, AL 46,578 532 79 12 47,200

Total 48,473 2,107 314 85 50,978

Table 2-15. Nitrogen Oxides (NOX) Emissions for 2009 by Emission Source Category

County

Nitrogen Oxides (NOX) Emissions (tons)

Point Area Non-road On-road Total

Hamilton, TN 2,949 645 5,602 7,514 16,710

Catoosa, GA 0 169 584 1,621 2,374

Walker, GA 46 398 200 1,194 1,838

Jackson, AL 5,663 317 1,287 1,437 8,704

Total 29,764 1,495 8,786 17,881 57,926
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Table 2-16. Ammonia Emissions for 2009 by Emission Source Category

County

Ammonia Emissions (tons)

Point Area Non-road On-road Total

Hamilton, TN 17 173 2.4 415 608

Catoosa, GA 0 521 0.3 87 608

Walker, GA 0 844 0.3 66 910

Jackson, AL 8 1,408 0.6 88 1,504

Total 25 2,944 3.6 656 3,629

2.2 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 models were selected by ASIP for use in PM2.5 modeling.

 Air Quality Model: The EPA’s Models-3/Community Multiscale Air Quality (CMAQ) 

modeling system is a “one-atmosphere” photochemical grid model capable of addressing 

ozone, particulate matter, visibility, and acid deposition at regional scale for periods up to 

one year.

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

Atmospheric Research Mesoscale Meteorological Model (MM5) is a nonhydrostatic, 

prognostic meteorological model routinely used for urban-scale and regional-scale 

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, non-road mobile, area, point, fire and biogenic emission sources for 

photochemical grid models.

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 attainment demonstration.
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2.2.1 Selection of Photochemical Grid Model

Criteria

For a photochemical grid model to qualify as a candidate for use in a SIP, a State needs to show 

that it meets the following general criteria for a NAAQS attainment demonstration.

 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. During the course of 

the modeling, VISTAS updated the secondary organic aerosol module in CMAQ to include 

important processes missing in the standard CMAQ model. Secondary organic aerosol module 

improvements are detailed in Section 1.3.3.3.1 of the Technical Support Document for VISTAS

Emissions and Air Quality Modeling to Support Fine Particulate State Implementation Plans

(Technical Support Document for VISTAS), which can be found in Appendix 4. For more than 

a decade, the EPA 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 EPA’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 EPA completed the initial stage 

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

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

version 4.4, which was released in October 2004.

Another reason for choosing CMAQ as the atmospheric model is the ability to do oneatmospheric modeling. Since the same modeling exercise is required for the ozone and PM2.5

attainment demonstrations SIPs, as well as the regional haze SIP, having a model that can handle 

both ozone and particulate matter is essential. A number of features in the theoretical 

formulation and technical implementation of CMAQ make the model well suited for annual 

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

the CMAQ model, can be found in the VISTAS Modeling Protocol (Appendix 5).

2.2.2 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 air quality 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 at no or low cost

 Output available in I/O API format

 Supports four dimensional data assimilation

 Enhanced treatment of planetary boundary layer heights for air quality modeling
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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 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. 

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

the MM5 model, can be found in the modeling protocol (Appendix 5).

2.2.3 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
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 Graphical analysis capability

 MOBILE6 mobile source emissions

 Biogenic Emissions Inventory System (BEIS3) model

 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 Sparse Matrix Operator Kernel Emissions (SMOKE) Processing System Prototype was 

originally developed at the Micro-computing 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 traveldemand 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 

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 the modeling protocol (Appendix 5).
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2.2.4 Selection of 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 Attainment Modeling Guidance 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 EPA recommends that episode selection derive from the following four

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

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

monitor violating the NAAQS is based on multiple days

VISTAS adopted a logical, stepwise approach in implementing the Attainment Modeling 

Guidance in order to identify the most preferable, representative modeling year. This approach 

included the following steps.

 Representativeness of Meteorological Conditions: The VISTAS 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 (CART) analyses to evaluate the 

candidate modeling years. The year 2002 was found to be representative of conditions in 

the other 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 visibility

and PM2.5 concentrations in 2002 were representative of the five-year baseline period. 

This analysis is discussed in more detail in Appendix 5.

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

collaborative investigations by VISTAS states (e.g., North Carolina Department of Air 

Quality, Georgia Department of Natural Resources, and Florida Department of 

Environmental Protection) 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 the EPA was requiring 

states to provide emissions inventory data for the Comprehensive Emissions Reporting 

Rule, it was appropriate to use 2002 as the modeling year to take advantage of the 2002 

inventory.
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 Years to be used by other Regional Planning Organizations: VISTAS also considered 

what years other regional planning organizations 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 (January 1 through December 31) as the most current, 

representative, and pragmatic choice for modeling. All of the EPA criteria for model year 

selection were directly considered in this process together with many other considerations (e.g., 

timing of new emissions or aerometric data deliveries by the EPA or the states to the modeling 

teams).

2.3 Modeling Domains

Horizontal Modeling Domain

The CMAQ model was run in the 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 or near stagnant conditions experienced in the region. 

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. Since this national modeling domain 

was used in the VISTAS regional haze modeling, it was used for the attainment demonstration as 

well. 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 2-1 shows the MM5 horizontal domain as the outer most, blue grid with 

the CMAQ 36-km domain nested in the MM5 domain.
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Figure 2-1. MM5 Horizontal Domain (Blue) with Nested CMAQ 36-km Domain

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

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

VISTAS region. This is the modeling domain for which the attainment test results are based. 

VISTAS conducted a study to determine if using a finer grid resolution provided different 

modeling results. Since the EPA attainment test uses the modeling results to determine the 

relative reductions in PM2.5, it was determined that effectively the same attainment test results 

are obtained from 12-km grid modeling or 4-km grid modeling. Since 4-km grid modeling takes 

significantly more time and resources to run, the ASIP decided to use the VISTAS 12-km grid 

modeling results for this attainment demonstration. This is in accordance with the Attainment 

Modeling Guidance. According to EPA, “areas without strong gradients in primary particulate 

matter will likely have little benefit from fine scale resolution.” Primary particulate matter is not 

a significant contributor to this area’s nonattainment problem as shown in the monitored data.
C-HCAPCB -30- PM 2.5 SIP

Figure 2-2. ASIP/VISTAS Region 12-km Grid

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 thirty-four layers that extend from the surface to 100 mb. Table 2-17, which 

follows, lists the layer definitions for both MM5 and for CMAQ. A layer-averaging scheme is 

adopted 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 were found 

to have a relatively minor effect on the model performance metrics when both the thirty-four 

layer and nineteen layer CMAQ models were compared to ambient monitoring data.
C-HCAPCB -31- PM 2.5 SIP

Table 2-17. Vertical Layer Definition for MM5 and CMAQ

MM5 Layers CMAQ Layers

Layer Sigma Pressure

(mb)

Height

(m)

Depth

(m) Layer Sigma Pressure(mb)

Height

(m)

Depth

(m)

34 0.000 100 14,662 1,841 19 0.000 100 14,662 6,536

33 0.050 145 12,822 1,466 – 0.050 145 – –

32 0.100 190 11,356 1,228 – 0.100 190 – –

31 0.150 235 10,127 1,062 – 0.150 235 – –

30 0.200 280 9,066 939 – 0.200 280 – –

29 0.250 325 8,127 843 18 0.250 325 8,127 2,966

28 0.300 370 7,284 767 – 0.300 370 – –

27 0.350 415 6,517 704 – 0.350 415 – –

26 0.400 460 5,812 652 – 0.400 460 – –

25 0.450 505 5,160 607 17 0.450 505 5,160 1,712

24 0.500 550 4,553 569 – 0.500 550 – –

23 0.550 595 3,984 536 – 0.550 595 – –

22 0.600 640 3,448 506 16 0.600 640 3,448 986

21 0.650 685 2,942 480 – 0.650 685 – –

20 0.700 730 2,462 367 15 0.700 730 2,462 633

19 0.740 766 2,095 266 – 0.740 766 – –

18 0.770 793 1,828 259 14 0.770 793 1,828 428

17 0.800 820 1,569 169 – 0.800 820 – –

16 0.820 838 1,400 166 13 0.820 838 1,400 329

15 0.840 856 1,235 163 – 0.840 856 – –

14 0.860 874 1,071 160 12 0.860 874 1,071 160

13 0.880 892 911 158 11 0.880 892 911 158

12 0.900 910 753 78 10 0.900 910 753 155

11 0.910 919 675 77 – 0.910 919 – –

10 0.920 928 598 77 9 0.920 928 598 153

9 0.930 937 521 76 – 0.930 937 – –

8 0.940 946 445 76 8 0.940 946 445 76

7 0.950 955 369 75 7 0.950 955 369 75

6 0.960 964 294 74 6 0.960 964 294 74

5 0.970 973 220 74 5 0.970 973 220 74

4 0.980 982 146 37 4 0.980 982 146 37

3 0.985 986.5 109 37 3 0.985 986.5 109 37

2 0.990 991 73 36 2 0.990 991 73 36

1 0.995 995.5 36 36 1 0.995 995.5 36 36

0 1.000 1,000 0 0 0 1.000 1,000 0 0
C-HCAPCB -32- PM 2.5 SIP

2.4 Boundary Conditions

The GEOS-CHEM global chemical transport model, which is managed and supported by the 

Atmospheric Chemistry Modeling Group at Harvard University, was used to develop the 

boundary conditions of the modeling domain. Appendix 6 contains a report titled Application of 

GEOS CHEM for 2002 Boundary Conditions for CMAQ Modeling of the VISTAS Region by Ivar 

Tombach dated October 5, 2007, which details the process.

The following three full-year 2002 simulations were run.

 A baseline simulation with best estimates of 2002 emissions

 A background simulation modified from the baseline by shutting off U.S. anthropogenic 

emissions which included fuel, industrial, and agricultural sources but not biomass 

burning

 A natural simulation modified by shutting off anthropogenic emissions worldwide.

Three dimensional concentration fields with three-hour temporal resolution were archived from 

each simulation to serve as boundary conditions for CMAQ. A model performance evaluation 

was conducted through comparisons of the baseline simulation to Interagency Monitoring of 

Protected Visual Environments (IMPROVE) and Clean Air Status and Trends Network 

(CASTNET) observations in the United States.

2.5 Initial Conditions

CMAQ default initial concentrations were used with a spin up period of approximately fifteen 

days to eliminate any significant influence of the initial conditions.

2.6 Model Performance Evaluation

A model performance evaluation was accomplished for VISTAS as part of the Regional Haze 

SIP process. A detailed evaluation of the model performance is included in Section 7.0 of the

modeling protocol (Appendix 5), in Chapter 3 and Appendix B of the Technical Support 

Document for ASIP Emissions and Air Quality Modeling to Support Fine Particulate State 

Implementation Plans (Appendix 4) and in the Technical Support Document for VISTAS 

(Appendix 4). ASIP, as discussed previously, utilized the modeling for regional haze to also 

demonstrate that the area will attain the PM2.5 standard by the end of 2009 as required.

Though there are no EPA designated metrics, there are metrics that have been used in several 

studies. Appendix B of the Attainment Modeling Guidance provides examples of the metrics 

and the goals and criteria for their use in other modeling studies. The following metrics and 

performance measures are presented to demonstrate adequate model performance.
C-HCAPCB -33- PM 2.5 SIP

Mean fractional bias (MFB) and mean fractional error (MFE) are the performance metrics used 

for the evaluation. The goal for MFB is within thirty percent. The goal for the MFE is less than 

or equal to fifty percent. The criterion for the MFB is within ± sixty percent.

As stated in Appendix B of the Attainment Modeling Guidance,

“. . .proposed to use asymptotically approaching and criteria when data are greater 

than 2.5 μm, approaching +200% MFE and ±200% MFB for extreme small model 

and observed data (formula of logarithmic MFB and MFE are proposed). Based 

on combined modeling studies ... for more abundant conditions MFE and MFB 

are typical in the range of:

Sulfates: MFE = 30% – 77% MFB = –45% – +51% (> 2 μg/m3)

Nitrates: MFE = 55% – 125% MFB = +3% – +82% (> 1 μg/m3)

Organic carbon: MFE = 35% – 95% MFB = –70% – +35% (> 1.5 μg/m3)

Elemental carbon: MFE = 50% – 95% MFB = –45% – +50% (> 0.5 μg/m3)

PM2.5: MFE = 50% – 85% MFB = –55% – +60% (> 5 μg/m3)”

Bugle plots and time series plots for each of the components of particulate matter show MFE and 

MFB. The bugle plots are shaped as shown because the goal and criteria lines are adjusted based 

on the average concentration of the observed species. The bugle plots and time series plots are 

located in Appendix 7 entitled Local Area Model Performance.

Modeling some components resulted in better model performance than others. Elemental 

carbon, sulfates, and ammonium all met the criteria for both MFB and MFE. Nitrates did not 

meet fractional bias criteria at low concentrations. Organic carbon met the criteria but did not 

meet the goal. Though not all values are in the desired range, the performance at the Siskin 

Drive/UTC FRM (470654002) in Hamilton County, which is critical for the modeled attainment 

demonstration, is satisfactory. Table 2-18 shows the MFEs and MFBs for the Siskin Drive FRM.

Table 2-18. MFE and MFB for the Siskin Drive/UTC FRM (470654002)

Pollutant Mean Fractional Error (MFE) Mean Fractional Bias (MFB)

Sulfates 37.55% –17.00%

Nitrates 118.07% –86.17%

Organic Carbon 59.81% –55.52%

Elemental Carbon 40.15% –23.46%

PM2.5 40.63% –31.56%
C-HCAPCB -34- PM 2.5 SIP

3.0 ATTAINMENT DEMONSTRATION

An attainment demonstration consists of analyses that estimate whether selected emissions 

reductions will result in ambient concentrations that meet the NAAQS and an identified set of 

control measures which will result in the required emissions reductions. The necessary emission 

reductions for both of these attainment demonstration components may be determined by relying 

on results obtained with air quality models.

Section 3.0 of the Attainment Modeling Guidance recommends applying both a modeled 

attainment test and a subsequent screening test (or unmonitored area analysis) to the air quality

modeling results to determine if the annual PM2.5 NAAQS will be met. Additional technical or 

corroboratory analyses may also be used as part of a “supplemental analysis” or a more stringent 

“weight of evidence” determination to supplement the modeled attainment test and to further 

support a demonstration of attainment of the NAAQS.

3.1 Speciated Modeled Attainment Test

The purpose of a modeling assessment is to determine if control strategies currently being 

implemented and proposed control strategies will lead to attainment of the annual PM2.5 NAAQS 

by the attainment year of 2009. The modeling is applied in a relative sense, similar to the 8-hour 

ozone attainment test. However, the PM2.5 attainment test is more complicated and reflects the 

fact that PM2.5 is a mixture. In the test, ambient PM2.5 is divided into major components, with a 

separate relative response factor (RRF) and future design value (DVF) calculated for each of the 

PM2.5 components. Since the attainment test is calculated on a per species basis, the attainment 

test for PM2.5 is referred to as the Speciated Modeled Attainment Test (SMAT). In its entirety, 

SMAT consists of four basic steps.

First, the observed quarterly mean PM2.5 and quarterly mean composition for each monitor is 

calculated. This is achieved by multiplying the monitored quarterly mean concentration of PM2.5 

from FRMs by the monitored fractional composition of PM2.5 species for each quarter [e.g., 

(20% sulfate) × (15.0 μg/m3PM2.5 mass) = 3.0 μg/m3sulfate mass)]. The monitored quarterly 

mean concentration of PM2.5 from FRMs are the five-year baseline design values that are the 

result of averaging the three current design values that straddle the modeling base year. The 

fractional composition of PM2.5 species is derived from speciation monitoring site data that has 

been processed by the “sulfate, adjusted nitrate, derived water, inferred carbonaceous material 

balance approach,” or SANDWICH method, so that speciation and FRM masses are equivalent. 

The mean composition derived from the SANDWICH method includes the percent of PM2.5 that 

can be attributed to sulfates, nitrates, organic carbon, elemental carbon, other primary inorganic 

particulate matter (or crustal material), ammonium, and particle bound water. Data from the 

STN monitor at the Siskin Drive/UTC site was used in conjunction with all four FRMs in the 

nonattainment area.

The second step is to use model results to derive component specific RRFs for each monitor for 

each quarter. The RRF is the ratio of the model’s future projections to the baseline current 

projections for each component.
C-HCAPCB -35- PM 2.5 SIP

For the third step, the component specific RRFs are applied to the observed air quality 

concentrations to project quarterly species estimates. For each quarter, the current quarterly 

mean component concentrations from the first step are multiplied by the component-specific 

RRFs obtained in the second step. This leads to an estimated future quarterly mean 

concentration for each component.

The fourth step sums the quarterly components to get a quarterly mean PM2.5 value. These 

quarterly mean values are then averaged to produce a future year annual average PM2.5 estimate, 

or DVF, for each FRM site. This final value is then compared to the NAAQS (15.0 μg/m3) to 

determine if attainment is reached. Documentation of the SMAT methodology and results are 

detailed in Sections 8.2 through 8.2.2 of the Modeling Protocol, which can be found in Appendix 

5, and in the Hamilton County SMAT Process, which can be found in Appendix 8.

3.2 Attainment Test Results

The 2008 annual average data and the three-year average data is as follows for all of the PM2.5

FRM monitors in this nonattainment area. 

The area monitors show that the annual average concentrations currently are at a level that 

demonstrates attainment. The 2008 annual average concentrations are 12.7 micrograms per 

cubic meter at the Siskin Drive/UTC site (470654002), 12.9 micrograms per cubic meter at the 

Soddy-Daisy site (470651011), 13.9 micrograms per cubic meter at the East Ridge site 

(470650031), and 12.5 micrograms per cubic meter at the Walker County, Georgia site 

(1329540002).

Three-year annual averages (Design Value) for 2006-2008 are as follows:

Federal Reference Monitor

2008

Annual

2006-2008

Average

Siskin Drive/UTC (470654002) 12.7 14.2

East Ridge (470650031) 12.3 13.8

Soddy-Daisy (470651011) 11.4 12.9

Walker County, Georgia (132950002) 12.5 *

*Incomplete Data for 2007

 The 2009 future design values for the four FRM sites in the nonattainment area are provided in 

Tables 3-1 and 3-2, which follow. Since the 2009 design value at each site is less than the 

annual PM2.5 NAAQS of 15.0 μg/m3, the area has passed the attainment test portion of the 

attainment demonstration.
C-HCAPCB -36- PM 2.5 SIP

Table 3-1. 2009 Quarterly Mean and Annual PM2.5 Design Values

Federal Reference Monitor

PM2.5 Design Value (μg/m3)

Quarter

1st 2nd 3rd 4th Annual

Siskin Drive/UTC (470654002) 12.2 13.7 15.3 13.0 13.6

Maxwell Road/East Ridge (470650031) 13.8 14.8 15.6 13.4 14.4

Soddy-Daisy High School (470651011) 12.2 13.2 14.7 9.3 12.3

Walker County, Georgia (132950002) 12.6 14.9 16.0 12.2 13.9

Table 3-2. 2009 Modeled Species and Annual PM2.5 Design Values

Federal Reference 

Monitor

Modeled Concentrations (μg/m3)*

Average 

Crustal 

Material

Average 

Elemental 

Carbon

Average 

Organic 

Carbon

Average 

Sulfates

Average 

Nitrates

Average 

Ammonium

Average 

Particle 

Bound 

Water

Blank 

Filter 

Mass

PM2.5

Design 

Value

Siskin Drive/UTC 

(470654002) 0.970 0.498 5.230 3.845 0.178 1.207 1.135 0.5 13.6

Maxwell Road/East 

Ridge (470650031) 1.023 0.522 5.614 4.068 0.190 1.277 1.201 0.5 14.4

Soddy-Daisy High 

School (470651011) 0.902 0.448 4.795 3.458 0.146 1.080 1.020 0.5 12.3

Walker County, 

Georgia (132950002) 0.978 0.509 5.446 3.914 0.188 1.230 1.153 0.5 13.9

*Passively collected mass, or the mass of the blank filter, has a constant value of 0.5 μg/m3for each FRM.

3.3 Supplemental Analyses/Weight of Evidence

The Attainment Modeling Guidance asserts that all attainment demonstrations should be 

accompanied by supplemental analysis that further supports the modeling conclusions. This 

supplemental analysis can include additional analyses of air quality, emissions, and 

meteorological data and may consider modeling outputs other than the results of the attainment 

test. If the attainment test results fall short of the standard, the results of corroboratory analyses 

may be used in a weight of evidence determination to show that attainment is likely despite 

modeled results, which may be inconclusive.
C-HCAPCB -37- PM 2.5 SIP

The Attainment Modeling Guidance defines the guideline for supplemental analysis/weight of 

evidence for the annual PM2.5 standard as follows:

 Sites with a DVF less than 14.5 μg/m3should submit basic supplemental analysis to 

confirm the outcome of the model attainment test.

 Sites with a DVF between 14.5 μg/m3and 15.5 μg/m3should submit a weight of 

evidence demonstration to aggregate supplemental analysis to support the model 

attainment demonstration.

 Sites with a DVF greater than or equal to 15.5 μg/m3should consider additional control 

measures to ensure attainment, as more qualitative analysis is unlikely to support a 

conclusion differing from the outcome of the modeled attainment test.

All monitoring sites in the nonattainment area have DVFs lower than 14.5 μg/m3. Therefore, the 

following section is a supplemental analysis to corroborate modeling results, rather than a weight 

of evidence analysis to show attainment.

3.3.1 Emissions Reductions Not Modeled

Electric Utilities

Georgia Rules for Air Quality Control Chapter 391-3-1 Rule (sss) “Multipollutant Control of 

Electric Steam Generating Units” requires additional SO2 reductions that were not included in 

the 2009 Emissions Inventory for the attainment model. By June 1, 2009, the Bowen Plant Unit 

2 must operate selective catalytic reduction and flue gas desulfurization. The changes will result 

in 19,328 tons reduction in SO2 emissions between June and December 2009.

Bowater Newsprint – Calhoun Operations

Bowater Newsprint – Calhoun Operations (Bowater) is a paper manufacturing plant located 

thirty miles from the Maxwell Road/East Ridge monitoring site. This source is not in the 

nonattainment area and the permits for this source are not within the jurisdiction of the 

Chattanooga-Hamilton County Air Pollution Control Bureau. The facility provided the State of 

Tennessee with updated emissions that contained weight of evidence information showing 

emissions reductions near this nonattainment area that were less than the modeled emissions. In 

an October 31, 2007, letter (Appendix 9) from Bowater’s Director of Environmental Affairs, Mr. 

J.W. O’Grady, the company reports the SO2 emissions were overestimated in the 2009 emissions 

inventory used in the ASIP model. The error was due to overestimates of coal sulfur content by 

approximately thirty-four percent and future coal firing by approximately sixteen percent. The 

ASIP modeling showed that the emissions of SO2 were 5,379 tons in 2009. In their letter, 

Bowater indicates that using the correct coal sulfur content and future coal firing would lower 

the SO2 emissions used as model input by forty percent.

In addition to the correction of SO2 emissions input, Bowater provided clarification of the 

company’s seasonal coal-firing rates. The ASIP model inventories assumed that SO2 emissions 
C-HCAPCB -38- PM 2.5 SIP

were equally distributed throughout the year. The company’s boilers are used primarily to heat 

river water. During the summer months when the river is warmer, monthly coal usage is almost 

half that of the winter months. According to the Georgia Institute of Technology sensitivity 

modeling, which will be detailed in Section 4.1.2 of this document, the conversion of non-EGU 

sources’ SO2 emissions to sulfates is ten times higher in the summer than the winter. Thus 

Bowater’s actual fuel use profile, with less coal burning in the summer results in decreased 

sulfates.

3.3.2 Status of Modeled Emissions Reductions

Fuel Changes

On-road and non-road diesel fuel and gasoline will contain far less sulfur in 2009 than in 2002. 

Despite expected growth of on-road and non-road vehicle uses, federal fuel sulfur reductions 

result in SO2 emission reductions of 317 tons per year from non-road vehicles and 402 tons per 

year from on-road mobile sources. As of November 21, 2007, three of the four fuel terminals for 

diesel fuel in Hamilton County stock only ultra-low sulfur diesel fuel. The local sulfur levels in 

gasoline are about 30 ppm at this time.

One hundred eighty-five diesel school buses are operated by a contractor in the Chattanooga

urban area. One hundred eighty-two of these were built in 2007, and the remaining three were 

built in 2008. All of these buses are equipped with diesel particulate filters. The contractor 

reported, in November 2007, that they had not experienced any difficulties with the performance 

of the school buses. The City of Chattanooga also operates diesel-powered garbage trucks that 

were all built in 2007. They too report no problems with the diesel particulate filters.

Industrial Sources

Hamilton County sources make up a small portion of the sources in the modeling domain. 

Emissions of PM2.5 and precursors have continued to decrease. Traditional heavy manufacturing 

industries continue their long term decrease in Hamilton County. In this jurisdiction, there were 

243 industrial point sources in 1999. Of these, twenty-two were Title V major sources and 

eighty-eight were synthetic minor sources. Today there are 207 industrial point sources, which 

include nineteen Title V sources and seventy-five synthetic minor sources. Industrial source 

emissions for the period have trended downward as well. Figures 3-1 through 3-7, which follow,

chart these emissions trends as reported in the Chattanooga-Hamilton County Air Pollution 

Control Bureau emissions inventories between 1999 and 2007. Individual industrial point source 

emissions from the inventories are provided in Appendix 10. Emissions of PM2.5 were not 

inventoried prior to 2002. With greater availability of emission factors, the PM2.5 emissions 

inventory has improved.
C-HCAPCB -39- PM 2.5 SIP

PM2.5 EMISSIONS

0

50

100

150

200

2003 2005 2007

Year

T

o

ns

Figure 3-1. Hamilton County Emissions of PM2.5

PM10 EMISSIONS

0

200

400

600

800

1000

1200

1400

1600

1999 2001 2003 2005 2007

Year

T

o

ns

Figure 3-2. Hamilton County Emissions of PM10
C-HCAPCB -40- PM 2.5 SIP

SULFUR DIOXIDE (SO2) EMISSIONS

0

1000

2000

3000

4000

5000

1999 2001 2003 2005 2007

Year

T

o

ns

Figure 3-3. Hamilton County Emissions of Sulfur Dioxide (SO2)

NITROGEN OXIDES (NOX) EMISSIONS

0

1000

2000

3000

4000

5000

1999 2001 2003 2005 2007

Year

T

o

ns

Figure 3-4. Hamilton County Emissions of Nitrogen Oxides (NOX)
C-HCAPCB -41- PM 2.5 SIP

TOLUENE EMISSIONS

0

10

20

30

40

50

60

70

1999 2001 2003 2005 2007

Year

T

o

ns

Figure 3-5. Hamilton County Emissions of Toluene

XYLENES EMISSIONS

0

20

40

60

80

100

1999 2001 2003 2005 2007

Year

T

o

ns

Figure 3-6. Hamilton County Emissions of Xylenes
C-HCAPCB -42- PM 2.5 SIP

AMMONIA EMISSIONS

0

5

10

15

20

25

30

35

1999 2001 2003 2005 2007

Years

T

o

ns

Figure 3-7. Hamilton County Emissions of Ammonia

Electric Utilities

The CAIR is in place, and electric utilities are complying with the rule. Georgia Rules for Air 

Quality Control Chapter 391-3-1 Rule (sss) “Multipollutant Control of Electric Steam 

Generating Units” has been adopted. Under this rule, the Hammond Plant near Rome, Georgia is 

required to have desulfurization equipment installed and operating by December 31, 2008. The 

Bowen Plant in Bartow County is required to have operational desulfurization equipment 

installed and operating on Units 3 and 4 by December 31, 2008. The combined SO2 emissions

from the two plants are estimated to be reduced by 92,104 tons per year by the end of 2008. A

wind from 184° carries the emissions from the Hammond Plant directly to the Maxwell 

Road/East Ridge monitor (470650031). A wind from 161° carries emissions from the Bowen 

plant to the Maxwell Road/East Ridge Monitor (470650031).

Miscellaneous Sources

In 2005, a seasonal open burning ban was put in place in Hamilton County. One small city has 

closed its air curtain destructor, and the City of Chattanooga no longer burns brush in their air 

curtain destructor. The air curtain destructor is maintained for use only for major storm brush 

cleanup as allowed by Federal rules. Citizen open burning has also decreased. For example, in 

1994, there were 7,131 open burning permits issued in Hamilton County. For the 2006-2007 

burning season, 5,510 permits were issued. Decreased open burning is known to reduce 

elemental carbon, organic carbon, and direct PM2.5 emissions.
C-HCAPCB -43- PM 2.5 SIP

Chattanooga has continued to encourage bicycle use. Both the City and major employers have 

installed bicycle racks in the downtown area. All Chattanooga Regional Transportation 

Authority mainline buses are equipped with bike racks. Approximately three thousand riders use 

the bike racks on the buses.

3.3.3 Status of Attainment for Surrounding Counties

In addition to the modeling results for the nonattainment area, all monitors in the counties 

surrounding this nonattainment area also show attainment in 2009. Table 3-3 lists the 2009 

DVFs for FRMs located in counties that surround Hamilton County.

Table 3-3. Surrounding Area 2009 Modeled Annual PM2.5 Design Values

Federal Reference Monitor PM2.5 Design Value (μg/m3)

DeKalb County, Alabama (010491003) 13.3

Madison County, Alabama (010890014) 12.8

Floyd County, Georgia (131150005) 14.0

McMinn County, Tennessee (471071002) 13.2
C-HCAPCB -44- PM 2.5 SIP

4.0 PM2.5 RACT/RACM

The PM2.5 Implementation Rule (40 CFR 51.1010) requires that “For each PM2.5 nonattainment 

area, the state shall submit with the attainment demonstration a SIP revision demonstrating that it 

has adopted all reasonably available control measures (including RACT for stationary sources) 

necessary to demonstrate attainment as expeditiously as practical and to meet any reasonable 

further progress requirements. The SIP revision shall contain the list of potential measures 

considered by the state and information and analysis sufficient to support the state’s judgment 

that it has adopted all RACM including RACT.” RACM can apply to industrial sources, mobile 

sources, open burning, heating, etc. RACT is a subset of RACM that applies to industrial 

sources, and it is defined as “the lowest emissions limitation that a particular source is capable of 

meeting by the application of control technology that is reasonably available considering 

technological and economic feasibility.” The PM2.5 Implementation Rule further states, “In 

determining whether a particular emission reduction measure or set of measures must be adopted 

as RACM under Section 172(c)(1) of the Act, the state must consider the cumulative impact of 

implementing the available measures. Potential measures that are reasonably available

considering technical and economic feasibility must be adopted as RACM if, considered 

collectively, they would advance the attainment date by one year or more.”

Speciated data from the STN monitor at the Siskin Drive/UTC site was used help identify

principle sources of emissions of PM2.5 and its precursors to be considered for emission controls 

or reductions. According to this monitoring data, other primary particulate matter and elemental 

carbon each make up less than five percent of the total PM2.5 mass. Existing local regulations 

already address the primary local sources of elemental carbon – on-road mobile sources, 

industrial boilers, process heaters, and open burning. Additional regulation of local sources of 

direct PM2.5 emissions is unlikely to result in a measurable reduction of PM2.5 due to their small 

contribution to the total, the emission and opacity limitations that are in place for all permitted 

stationary sources of particulate matter emissions in Hamilton County, and the uncertainty of 

some of the PM2.5 emission factors. The EPA has determined that their emission factors for 

PM2.5 from natural gas combustion are overestimated. As a result, the EPA reduced such 

emissions in the 2002 NEI by about ninety-five percent. Documentation to support this 

reduction is found in Appendix 11.

Monitoring data reveals that sulfates are one of the largest components of PM2.5 in this area. 

Depending on the specific year, sulfates account for twenty-five percent to thirty-two percent of 

the total PM2.5 mass. As stated previously, sulfates are pollutants caused by SO2 emissions, 

primarily from coal-fired power plants outside of Hamilton County. In 2002, combined SO2

emissions from all sources within Hamilton County were 3,222 tons per year compared to 44,206 

tons per year from the TVA Widows Creek Fossil Plant in Jackson County, Alabama, which is 

the closest of four regional coal-fired power plants located within 75 miles of the county. 

Primary local sources of SO2 emissions are motor vehicles (both on-road and non-road) and 

industrial boilers that use a fuel other than natural gas. Ultra-low sulfur transportation fuels are 

being phased in for both on-road and non-road vehicles. The primary fuel that is used by most 

industrial combustion sources in Hamilton County is natural gas, which contains a negligible 

amount of sulfur.
C-HCAPCB -45- PM 2.5 SIP

Organic carbon is also one of the largest components of PM2.5 in this area. The portion of PM2.5

that is organic carbon ranges from twenty-eight percent to thirty-two percent. Organic carbon is 

produced from condensation of high molecular-weight VOCs; reactions in the atmosphere of 

toluene, xylenes, and trimethylbenzenes that form secondary organic aerosols; atmospheric 

reactions of biogenic compounds; open burning; home heating with wood; on-road and non-road 

vehicles; and stationary internal combustion engines.

Approximately 24 tons of high molecular-weight VOCs are emitted annually in the county, all of 

which are generated by one Title V industrial source. Scrubbers, demisters, and electrostatic 

precipitators are used to control these emissions to RACT levels in accordance with Section 

4-41, Rule 26 of the Chattanooga-Hamilton County Air Pollution Control Ordinance (the 

Ordinance). There are currently 34 tons per year of toluene and 41 tons per year of xylenes 

emitted annually from permitted industrial sources in Hamilton County. These emissions are 

regulated under Section 4-41, Rule 25 of the Ordinance, which requires BACT for VOCs. No 

emissions of trimethylbenzenes are reported in the local emissions inventory. Reactive biogenic 

emissions from the nonattainment area and the surrounding counties were estimated by the EPA 

BEIS3.09 model to be 94,358 tons per year in 2002. Reactive biogenic VOCs produced in the 

nonattainment area alone in 2002 totaled 13,141 tons per year.

Nitrates are generated in the atmosphere from NOX, which is a product of combustion. Nitrates 

constitute between six percent and eight percent of the monitored PM2.5. Seventy-three industrial 

sources emit NOX within Hamilton County. Only two of these have NOX emissions that are 

greater than one hundred tons per year. An additional twenty sources have NOX emissions 

greater than twenty tons per year but less than one hundred tons per year. All other sources have 

NOX emissions of less than twenty tons per year. The largest industrial NOX source is a cement 

kiln that is subject to and meeting the NOX RACT requirements of the NOX SIP call. These 

requirements are in effect for the entire year rather than just applying during the ozone season.

Ammonia emissions are the source of the ammonium component of the PM2.5 total mass. Onroad mobile sources are the largest contributor to ammonia emissions in Hamilton County. 

Current emissions of ammonia from permitted stationary sources in the county are inventoried at 

17 tons per year.

4.1. Permitted Stationary Sources

Section 4-8 of the Ordinance requires that all stationary sources that emit regulated air pollutants 

above insignificant levels be permitted. There are 207 permitted stationary sources in Hamilton 

County. Nineteen of these are Title V sources, seventy-five are synthetic minor sources, and 113

area minor sources. Title V sources have potential emissions of greater than one hundred tons 

per year of particulate matter, SO2, NOX, VOCs, or carbon monoxide; twenty-five tons per year 

of all hazardous air pollutants (HAPs) combined; or ten tons per year of any individual HAP. 

Synthetic minor sources have accepted federally enforceable permit conditions that limit their 

emissions to below the Title V applicability thresholds. Semi-annual compliance reports and 

annual compliance certifications are required to be submitted by all Title V sources. In addition, 

most synthetic minor sources and several minor sources are required to submit periodic reports 

showing compliance with permit requirements.
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The permitting process that each source goes through requires an analysis of the pollutant 

emissions and emission controls. In addition, all permitted sources are evaluated annually for 

compliance with all applicable regulations. This evaluation consists of an on-site inspection and 

review of required records and reports. Sources inspections are also conducted in conjunction 

with complaint investigations and routine patrols. A total of seven staff members maintain 

certification to perform visible emission evaluations.

4.1.1 Local Regulations

The Ordinance includes rules that regulate emissions from both new and existing stationary 

sources. The following Federal rules and standards have been incorporated by reference in the 

Ordinance.

 Federal New Source Performance Standards are adopted by reference into the Ordinance. 

They provide for emissions control based on the installation date of specific components.

 National Emissions Standards for Hazardous Air Pollutants were promulgated as required 

by the 1990 Clean Air Act Amendments and are also adopted by reference into the 

Ordinance. These standards have resulted in reductions of both particulate matter 

emissions and emissions of certain aromatic compounds, such as toluene and xylenes, 

which react in the atmosphere to produce secondary organic aerosols. Some standards 

use particulate matter as a surrogate for certain HAPs.

Hamilton County was a nonattainment area for total suspended particulate matter (TSP) and for 

the one-hour ozone standard. The community came into attainment for TSP in 1979 and for the 

one-hour ozone standard in 1989. The area has successfully completed the requirements of an 

Early Action Compact for the eight-hour ozone standard. As a result, the area is being 

designated as an attainment area for this standard. In addition, the largest source of NOX

emissions in the nonattainment was subject to the NOX SIP call.

These earlier nonattainment experiences and the Early Action Compact resulted in the adoption 

of rules that have significantly reduced direct PM2.5 emissions, emissions of VOCs that result in 

secondary organic aerosols, and emissions that result from fuel combustion. Various local rules 

and regulations were adopted to bring the area into attainment with the TSP, one-hour ozone, and 

eight-hour ozone standards. Local rules and regulations of the Ordinance that are in effect 

include the following.

 Section 4-8(e)(2) requires best available control technology (BACT) for sources of 

particulate emissions that impact the former nonattainment area and that were constructed 

or modified after September 16, 1980.

 Section 4-41, Rule 2 regulates emissions of NOX.

 Section 4-41, Rule 3 regulates the opacity of visible emissions.

 Section 4-41, Rule 4 limits fuel sulfur content.
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 Section 4-41, Rule 6 regulates and restricts open burning. This includes a county-wide 

ban on open burning during ozone season.

 Section 4-41, Rule 8 regulates particulate matter emissions from fuel burning equipment.

 Section 4-41, Rule 10 regulates particulate matter emissions from process equipment.

 Section 4-41, Rule 11 regulates handling, processing, and storing of material in the open 

air and requires that measures be taken to prevent particulate matter from becoming 

airborne. This includes particulate matter emissions from roads, parking areas, open 

fields, etc.

 Section 4-41, Rule 13 regulates emissions of SO2.

 Section 4-41, Rule 25 regulates emissions of VOCs such as toluene and xylenes that react 

in the atmosphere to form secondary organic aerosols. Rule 25.3 requires BACT or 

lowest achievable emission rate (LAER) levels of emissions control, depending on 

potential emission rates, for sources of VOC emissions that were constructed or modified 

after December 26, 1979. Rule 25.10 requires gasoline dispensing facilities to utilize 

Stage 1 vapor recovery. 180 gasoline dispensing facilities in Hamilton County are 

subject to this requirement. The use of Stage 1 vapor recovery minimizes fugitive 

emissions of gasoline. Although toluene and xylenes combined comprise only about 1.7 

percent by weight of gasoline emissions, the large quantity of gasoline dispensed contains 

a considerable amount of these compounds.

 Section 4-41, Rule 26 requires RACT for sources of particulate matter emissions that 

were in existence before 1978. Three coal-fired boilers at one industrial source in 

Hamilton County comply with this rule by the use of baghouses to control particulate 

matter emissions and the use of continuous opacity monitors.

 Section 4-41, Rule 27 requires BACT or “reasonable and proper emissions limitations,” 

depending on potential emission rates, for sources of particulate matter emissions that 

were constructed or modified after August 29, 1995.

4.1.2 Sensitivity Modeling

The Georgia Institute of Technology conducted sensitivity modeling for each of the ASIP states. 

Seasonal sensitivities were determined from modeled PM2.5 concentration responses to uniform 

emission reductions throughout Tennessee. Sensitivities were determined for emissions of NOX

from point sources, SO2 from non-EGU sources, and PM2.5 from point sources for both summer 

and winter seasons. Since these sensitivities are for statewide reductions in emissions and are 

not county specific, the theoretical maximum reductions in PM2.5 concentrations that could be 

realized in Hamilton County are arrived at by applying the sensitivities to the statewide 

emissions of each pollutant and assuming that all of these emissions are concentrated in 

Hamilton County. The resulting absolute maximum reductions that result from completely 

eliminating all emissions of each specified pollutant, in turn, from Hamilton County are small, 

ranging from PM2.5 concentration reductions of 0.0554 μg/m3for NOX point source emissions to 

0.249 μg/m3for SO2 non-EGU source emissions. These calculated PM2.5 concentration 

reductions for Hamilton County are given below in Table 4-1.
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Table 4-1. Maximum PM2.5 Concentration Reductions from Sensitivity Modeling

Pollutant

Emissions (tons/day)

Season

Sensitivity

(ng/m3)/ 

(ton/day)

PM2.5 Reduction from 

Total Elimination of 

Each Pollutant

Hamilton 

County

Tennessee 

(Statewide)

NOX from 

point sources 7.501

275.6 Summer -0.174 0.0479 μg/m3

577.8 Winter -0.0958 0.0554 μg/m3

SO2 from nonEGU sources 8.786

230.5 Summer -1.08 0.249 μg/m3

226.7 Winter -0.0958 0.0217 μg/m3

PM2.5 from 

point sources 1.899

29.8 Summer -5.25 0.157 μg/m3

31.7 Winter -3.51 0.111 μg/m3

Even though potential PM2.5 reductions that are available from local sources are insufficient to 

bring the area into attainment before 2009, a further review was conducted as described in the 

PM2.5 Implementation Rule (page 20612): “A state must consider RACT and RACM for all its 

nonattainment areas. However EPA believes that if the state projects that an area will attain the 

standard within 5 years of designation as a result of existing measures (i.e. projected to have a 

design value of 14.5 or lower), then the state may conduct a limited RACT and RACM analysis 

that does not involve additional air quality modeling. A limited analysis of this type would 

involve reasonably available measures, the estimate of potential emissions reductions, and the 

time needed to implement these measures.”

Seventeen permitted sources in Hamilton County emit greater than 10 tons per year of TSP, as 

reported in the local emissions inventory for 2007. Based on available emission factors, two 

sources emit greater than 10 tons per year of direct PM2.5. Nineteen sources emit greater than 10 

tons per year of NOX. Ten sources emit greater than 10 tons per year of SO2. Thirteen sources 

emit more than 40 tons per year of TSP, NOX, and SO2 combined. The permits of each of these 

thirteen sources were examined in detail and were all found to require at least RACT levels of 

emissions control. The results of this review are given in Appendix 12. This review and the 

results of the sensitivity modeling indicate that no additional reductions are available from local 

permitted stationary sources that would result in attainment in 2008 rather than 2009.
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4.2 Gasoline Dispensing Facilities

180 gasoline dispensing facilities are permitted in Hamilton County. Stage 1 vapor recovery 

became a requirement in the county in 2005. Each dispensing facility receives an annual 

inspection. Stage 1 vapor recovery results in a reduction of fugitive aromatic compound 

emissions of toluene and xylenes of approximately 20 tons per year. The use of Stage 1 vapor 

recover is a RACT level of emissions control. No additional reductions of aromatic compound 

emissions from gasoline dispensing facilities are practical.

4.3 On-Road Mobile Sources

Automobiles and light trucks registered in Hamilton County are subject to annual inspection and 

maintenance requirements of Tennessee State Rule 1200-3-29. This rule requires a successful 

vehicle inspection prior to registration renewal for 1975 model year and newer vehicles. 

Inspection and maintenance of on-road mobile sources results in reductions in fugitive emissions 

of aromatic compounds, emissions of VOCs from incomplete combustion, and NOX emissions. 

The resulting reduction in emissions of aromatic compounds, such as toluene and xylenes, is 

approximately 20 tons per year. The existing inspection and maintenance program constitutes 

RACM for on-road mobile sources. No additional emissions reductions from on-road mobile 

sources are planned.

Highway vehicles in Hamilton County emit 352 tons of ammonia per year. Ammonia is 

produced by vehicle catalytic converters, which are regulated at the federal level. The preamble 

of the PM2.5 Implementation Rule states, “The NARSTO Fine Particulate Assessment indicates 

that reducing ammonia emissions where sulfates concentrations are high may reduce PM2.5 mass 

concentrations, but may also increase the acidity of particles and precipitation.” Based on the 

high sulfates in this area and previous experience with acid rain, reductions of ammonia 

emissions are not practical.

4.4 Non-Road and Stationary Internal Combustion Engines

Non-road and stationary internal combustion engines result in organic carbon and other primary

particulate matter. This category of engines includes a wide variety of non-road diesel engines 

without controls, railroad and barge diesel engines, two cycle engines where lubricating oil is 

mixed with gasoline, and numerous small gasoline engines. All of these engines are regulated at 

the federal level. However, state and local governments could institute voluntary programs to 

retrofit after market controls on existing non-road sources.

A previous retrofit program had resulted in the installation of 105 diesel oxidation catalysts on 

local school buses. This program was completed in approximately three years. About one year 

was required to contract and install the catalysts. It is unlikely that another retrofit program 

generating sufficient reductions could be instituted in time to result in early attainment.

Section 4-41, Rule 2 of the Ordinance limits industrial process NOX emissions to 300 ppm. 

Because many stationary internal combustion engines cannot meet this requirement, their use is 
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limited. The Ordinance does allow for the use of stationary internal combustion engines to 

power emergency generators. No emissions reductions beyond federal requirements for nonroad internal combustions engines are planned.

4.5 Open Burning

Open burning is regulated by Section 4-41, Rule 6 of the Ordinance. This rule requires open 

burning permits, bans open burning from May 1 through September 30, and prohibits the burning 

of brush cleared for road building and trash in Hamilton County. In addition, open burning is 

only allowed within the City of Chattanooga if no alternative is available. The City of 

Chattanooga provides a brush pickup service, and the collected brush is chipped. Existing 

restrictions constitute RACM for open burning and will remain in effect.

4.6 Home Heating with Wood

Information from the 2000 US Census (Appendix 13) showed that 2.2% of the households in 

twenty counties in and around the nonattainment area used wood as the primary heating fuel. 

Within Hamilton County, only 712 households, or 0.6% of the total number, heat primarily with 

wood.

Heating requirements are typically designated in degree days. According to the American Gas 

Association, a degree day accrues for every degree the average outside temperature is below 

65°F during a 24-hour period. June, July, August, and September require no heating in this area. 

In Chattanooga, 3,384 degree days comprise the design heating requirements. This compares 

with design heating requirements of 6,282 degree days in Chicago and 7,966 degree days in 

Minneapolis.

The Federal New Source Performance Standards for Residential Wood Heaters (40 CFR Part 60 

Subpart AAA) applies to residential wood heaters manufactured after July 1, 1988, and sold after 

July 1, 1990. In the last seventeen years, it would be expected that a considerable portion of 

wood burning stoves have been replaced and that new stoves have been installed in new 

construction. Replacing remaining older stoves would result in some particulate matter and 

VOC emissions reductions. Particulate matter emission factors are 83 pounds per ton for 

conventional stoves and from 26.6 to 28 pounds per ton for stoves manufactured in accordance 

with Subpart AAA. VOC emission factors are 28 pounds per ton and 17.2 pounds per ton for 

conventional stoves and Subpart AAA compliant stoves, respectively.

The small portion of households using wood heating, the mild local climate, and the normal 

purchases of Subpart AAA compliant wood burning stoves in the nonattainment area indicate 

that accelerated replacement of the remaining older stoves will not be able to advance the 

attainment date. No short term efforts to upgrade or further regulate home heating are planned.
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5.0 MOTOR VEHICLE EMISSIONS BUDGETS

5.1 Transportation Conformity

The purpose of transportation conformity is to ensure that Federal Transportation actions 

occurring in nonattainment and maintenance areas do not hinder the area from attaining and 

maintaining the NAAQS. This means that the level of emissions estimated for the 

Transportation Improvement Program and Long Range Transportation Plan must not exceed the 

motor vehicle emission budgets (MVEB) defined in this attainment demonstration. The MVEB 

for Hamilton County was developed through consultation with the Interagency Consultation 

Partners and the Chattanooga Hamilton County North Georgia Transportation Planning 

Organization. Georgia and Alabama are addressing transportation budgets for their portions of 

the nonattainment area.

5.2 Transportation Budget for Hamilton County

The budget was developed following the 2005 EPA Guidance for Creating On-Road Mobile 

Source Emission Inventories for PM2.5. Mobile source inventories were developed using the 

latest planning assumptions, the most recent recalibrated travel demand model, and EPA’s latest 

motor vehicle model, Mobile 6.2.03. Average annual activity and meteorology was used in 

modeling. Planning Assumptions for Development of 2009 CHCNGA TPO TransCAD Model 

2009 Emissions Results are contained in Appendix 14. The transportation budget for PM2.5 is 

125.56 tons per year for Hamilton County.

5.3 Pollutants to Be Considered

5.3.1 Sulfur Dioxide (SO2)

The PM2.5 Implementation Rule provides that SO2 must be addressed as a significant PM2.5 

precursor, and sources of SO2 emissions must be evaluated for control measures. The rule 

further states that sulfur oxides are mostly emitted from fossil fuel combustion with a smaller 

portion of emissions from other industrial processes. According to the EPA, SO2 emissions from 

motor vehicles would not require a budget due to the current de minimis levels of those 

emissions from on-road vehicles and further considering the projected decline in SO2 emissions 

from vehicles due to low-sulfur gasoline and low-sulfur diesel fuel. Hamilton County agrees 

with the EPA, and therefore no motor vehicle budget was developed for SO2 on-road mobile 

sources.

5.3.2 Nitrogen Oxides (NOX)

The PM2.5 Implementation Rule provides that NOX be addressed as a significant PM2.5 precursor 

unless demonstrated otherwise by the State. The insignificance demonstration for NOX as a 

PM2.5 precursor is found in Appendix 15. Modeling for seventy percent and one hundred percent 

reductions of NOX shows minimal changes in PM2.5.
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5.3.3 Volatile Organic Compounds (VOCs)

The PM2.5 Implementation Rule explains that the State is not required to address VOCs as a 

PM2.5 attainment plan precursor unless the State or EPA provides an appropriate technical 

demonstration for a specific area showing that VOC emissions from sources in the State 

significantly contribute to PM2.5 concentrations in a given nonattainment area. No demonstration 

is being submitted.

5.3.4 Ammonia

The EPA’s policy on ammonia presumes that ammonia is not a PM2.5 attainment plan precursor. 

The State is not required to address ammonia unless the State or EPA provides an appropriate 

technical demonstration showing that ammonia emissions from sources in the State significantly 

contribute to PM2.5 concentrations in the nonattainment area. No demonstration is being 

submitted.

5.3.5 Road and Construction Dust

The PM2.5 Implementation Rule states that crustal material is only a minor part of PM2.5 annual 

average concentrations, and that construction dust will not be significant in all areas. 

Construction dust is not a significant concern in Hamilton County. The temperate climate and 

few unpaved roads in this primarily urban county leave little opportunity for road or construction 

dust to become significant contributors to PM2.5. In addition, regular rainfall removes dust from 

paved roads and helps keep unpaved roads from becoming a source of significant PM2.5 crustal 

material. No demonstration is being submitted.
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6.0 CONTINGENCY MEASURES

The PM2.5 Implementation Rule requires contingency measures that would take effect in the 

event a nonattainment area fails to meet the PM2.5 NAAQS. These contingency measures must 

be fully adopted rules or control measures that are ready to be implemented quickly upon failure 

of an area to meet the standard by the attainment date.

There are no available contingency measures in Hamilton County that can result in significant 

PM2.5 reductions from industrial sources as indicated by Table 4-1 in Section 4.1.2 of this 

document. The table shows that elimination of all of the industrial emissions in the county will 

have little effect on the PM2.5 concentration.

Georgia Rules for Air Quality Control Chapter 391-3-1 Rule (sss) “Multipollutant Control of 

Electric Steam Generating Units” requires additional power plant SO2 emission reductions after 

the end of 2008. Bowen Plant Unit 1 is required to be equipped with flue gas desulfurization by 

June 1, 2010. The SO2 emissions reductions expected from this unit are 33,135 tons per year or 

19,328 tons reduction in the last seven months of 2010. These reductions were not modeled for 

2009. The reductions are not required to demonstrate attainment of the annual PM2.5 standard, 

but constitute contingency measures.
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7.0 REASONABLE FURTHER PROGRESS

Clean Air Act §172(c)(2) requires plans for nonattainment areas to require “reasonable further 

progress,’’ (RFP) as defined in CAA §171(1). The Act requires nonattainment areas to make 

“such annual incremental reductions in emissions of the relevant air pollutant as are required by

this part or may reasonably be required by the Administrator for the purpose of ensuring 

attainment of the applicable national ambient air quality standard by the applicable date.” In 

general terms, the goal of RFP is to allow areas to achieve generally linear progress toward 

attainment. The RFP requirements were included in the CAA to assure steady progress toward 

attaining air quality standards, as opposed to deferring implementation of all measures until the 

end date by which the standard is to be attained.

40 CFR §51.1009 states that, consistent with CAA §172(c)(2), SIPs for PM2.5 nonattainment 

areas must demonstrate reasonable further progress as provided in §51.1009(b) through (h). 

Paragraph (b) of that section states that “if the State submits to EPA an attainment demonstration 

and State implementation plan for an area which demonstrates that it will attain the PM NAAQS 

within five years of the date of designation, the State is not required to submit a separate RFP 

plan. Compliance with the emission reduction measures in the attainment demonstration and 

State implementation plan will meet the requirements for achieving reasonable further progress 

for the area.” Consistent with the provisions of §51.1009(b), Hamilton County has submitted a 

SIP that demonstrates that the Hamilton County portion of the nonattainment area will attain the 

annual PM2.5 NAAQS within five years of designation. Therefore, no additional provisions for 

RFP are required. Compliance with the emission reduction measures in this attainment 

demonstration and SIP will meet the requirements for achieving reasonable further progress for 

the Hamilton County, Tennessee area.