South Carolina 

8-Hour Ozone Attainment Demonstration 

For the Portion of York County, South Carolina Within the 

Rock Hill-Fort Mill Area Transportation Study (RFATS) 

Metropolitan Planning Organization (MPO) 

Part of the

Charlotte-Gastonia-Rock Hill, NC-SC 

8-Hour Ozone Nonattainment Area 

Prepared by the 

South Carolina Department of Health and Environmental Control 

Bureau of Air Quality 

August 30, 2007 
TABLE OF CONTENTS 

RFATS MPO 8-HOUR OZONE ATTAINMENT DEMONSTRATION EXECUTIVE SUMMARY.......1

I. 8-hour Ozone National Ambient Air Quality Standards...........................................................................1

II. Modeling Protocol...................................................................................................................................1

III. Conceptual Description of Ozone Formation ........................................................................................1

IV. Attainment Demonstration Methods and Inputs....................................................................................2

V. Model Performance Evaluation...............................................................................................................3

VI. Attainment Demonstration.....................................................................................................................3

VII. Attainment of the 8-hour Ozone NAAQS by 2009...............................................................................3

SECTION I. SOUTH CAROLINA AIR QUALITY IMPLEMENTATION PLAN .........................................5

A. Introduction to 8-Hour Ozone NAAQS ..................................................................................................5

 1. Ground-Level (Tropospheric) Ozone...............................................................................................5

 2. Health Concerns...............................................................................................................................5

 3. National Ambient Air Quality Standards (NAAQS) .......................................................................6

 4. 8-Hour Ozone NAAQS....................................................................................................................6

B. Nonattainment Area Designations and Classifications ...........................................................................6

 1. Area Designations............................................................................................................................6

 2. Nonattainment Area Boundaries......................................................................................................7

 3. Nonattainment Area Classifications.................................................................................................7

C. 8-hour Ozone Designations for South Carolina .......................................................................................8

D. Charlotte-Gastonia-Rock Hill, NC-SC Metropolitan Statistical Area ....................................................9

 1. Charlotte-Gastonia-Rock Hill, NC-SC Metropolitan Statistical Area .............................................9

 2. Monitors in the Charlotte-Gastonia-Rock Hill, NC-SC MSA .........................................................9

 3. 2001-2003 Design Values for Monitors Located in the MSA .......................................................10
E. Charlotte-Gastonia-Rock Hill, NC-SC Area .........................................................................................11

 1. Metrolina Area...............................................................................................................................11

 2. Metrolina Nonattainment Area Boundaries ...................................................................................11

 3. Metrolina Nonattainment Area Classification ...............................................................................11

F. Conceptual Description of Ozone Formation in the Metrolina Area.....................................................11

G. Clean Air Act Requirements .................................................................................................................15

 1. Section 172(c) - Nonattainment Plan Provisions...........................................................................15

 2. Section 182(a) - Plan Submissions and Requirements for Marginal Areas ...................................15

 3. Section 182(b) - Additional Plan Submissions and Requirements for Moderate Areas ................15

SECTION II. ATTAINMENT DEMONSTRATION METHODS AND INPUTS...................................16

A. Analysis Method ...................................................................................................................................16

B. Model Selection.....................................................................................................................................17

 1. Selection of Photochemical Grid Model........................................................................................17

 a. Criteria .......................................................................................................................................17

 b. Overview of CMAQ ..................................................................................................................17

 2. Selection of Meteorological Model................................................................................................18

 a. Criteria .......................................................................................................................................18

 b. Overview of MM5.....................................................................................................................18

 3. Selection of Emissions Processing System....................................................................................19

 a. Criteria .......................................................................................................................................19

 b. Overview of SMOKE ................................................................................................................19

C. Episode Selection ..................................................................................................................................20

 1. Overview of USEPA Guidance on Ozone .....................................................................................20

 2. Episode Selection...........................................................................................................................20

D. Modeling Domains................................................................................................................................21
 1. Horizontal Modeling Domain ........................................................................................................21

 2. Vertical Modeling Domain ............................................................................................................23

E. Emission Inventory................................................................................................................................24

 1. Stationary Point Sources ................................................................................................................25

 a. Electric Generating Units...........................................................................................................25

 b. Other Point Sources...................................................................................................................26

 2. Stationary Area Sources.................................................................................................................26

 3. Nonroad Mobile Sources ...............................................................................................................27

 4. Highway Mobile Sources...............................................................................................................27

 5. Biogenic Emission Sources............................................................................................................28

SECTION III. MODEL PERFORMANCE EVALUATION ....................................................................29

A. Domain-Wide Performance ..................................................................................................................30

 1. Spatial Plots ...................................................................................................................................31

 2. Scatter Plots ...................................................................................................................................39

 a. North Carolina Scatter Plots ......................................................................................................39

 b. South Carolina Scatter Plots......................................................................................................41

 3. Time Series Plots ...........................................................................................................................43

 4. Domain-Wide Summary ................................................................................................................44

B. Area and Monitor Statistics...................................................................................................................45

SECTION IV. CONTROLS APPLIED .....................................................................................................47

A. Federal Control Measures .....................................................................................................................47

 1. Tier 2 Vehicle Standards................................................................................................................47

 2. Heavy-Duty Gasoline and Diesel Highway Vehicles Standards ...................................................47

 3. Large Nonroad Diesel Engines Rule..............................................................................................47
 4. Nonroad Spark-Ignition Engines and Recreational Engines Standard...........................................47

 5. NOx SIP Call in Surrounding States..............................................................................................48

 6. Clean Air Interstate Rule................................................................................................................48

B. State Control Measures .........................................................................................................................48

 1. New Source Review Regulations...................................................................................................48

 a. South Carolina Air Pollution Control Regulation R. 61-62, Definitions and General .................

 Requirements, Section II - Permit Requirements .....................................................................49

 b. South Carolina Air Pollution Control Regulation R. 61-62.5, Standard No. 7, Prevention of .....

 Significant Deterioration..........................................................................................................49

 c. South Carolina Air Pollution Control Regulation R. 61-62.5, No. 7.1 - Nonattainment New ......

 Source Review ..........................................................................................................................49

 2. NOx Regulations ............................................................................................................................49

 a. South Carolina Air Pollution Control Regulation R. 61-62.5, Standard No. 2 - Ambient Air ......

 Quality Standards.....................................................................................................................49

 b. South Carolina Air Pollution Control Regulation R. 61-62.5, Standard No. 5.2 - Control of ......

 Oxides of Nitrogen (NOx).........................................................................................................49

 c. South Carolina Air Pollution Control Regulation R. 61-62.96 - Nitrogen Oxides (NOx) Budget .

 Trading Program......................................................................................................................50

 d. South Carolina Air Pollution Control Regulation R. 61-62.99 - Nitrogen Oxides Budget ...........

 Program Requirements for Stationary Sources Not in the Trading Program..........................50

 e. South Carolina Air Pollution Control Regulation R. 61-62.2 - Prohibition of Open Burning ..50

 3. VOC Regulations: South Carolina Air Pollution Control Regulation R. 61-62.5, Standard No. 5 - 

Volatile Organic Compounds.........................................................................................................50

 4. Other State Control Measures........................................................................................................50

 a. Clean Air Interstate Rule (CAIR) ..............................................................................................50

 b. Permitting Requirements Involving Emission Offsets - Conditions for Approval....................51
 5. Emissions Inventory: South Carolina Regulation R. 61-62.1, Definitions and General 

 Requirements, Section III - Emissions Inventory........................................................................53

 6. Reasonably Available Control Measures (RACM)........................................................................53

 a. Reasonably Available Control Technology (RACT).................................................................53

 b. Early Action Compacts..............................................................................................................53

 c. Take a Break from the Exhaust..................................................................................................54

 d. Overall RACM Conclusions......................................................................................................55

SECTION V. ATTAINMENT DEMONSTRATION ...............................................................................56

A. Attainment Test Introduction ................................................................................................................56

B. Attainment Test Results ........................................................................................................................57

C. Supporting Weight of Evidence ............................................................................................................57

 1. Alternative DVF Calculation .........................................................................................................58

 2. Additional Air Quality Modeling Metrics......................................................................................59

 3. Air Quality Modeling Results From Other Studies........................................................................59

 4. Positive Trends in Observed Air Quality and Additional Emissions Reductions..........................60

 5. Local Measures Not Modeled........................................................................................................63

D. Unmonitored Area Attainment Analysis...............................................................................................63

E. Data Access ...........................................................................................................................................64

SECTION VI. MODERATE NONATTAINMENT AREA REQUIREMENTS......................................65

A. Clean Air Act (CAA), as amended (42 U.S.C. 7401, et seq.)...............................................................65

 1. CAA Section 172(c) - Nonattainment Plan Provisions..................................................................65

 2. CAA Section 182 - Plan Submissions and Requirements..............................................................66

 a. CAA Section 182(a) - Marginal Areas ......................................................................................66

 b. CAA Section 182(b) - Moderate Areas .....................................................................................66
 c. CAA Section 182(f) - NOx Requirements..................................................................................67

B. South Carolina Air Quality Implementation Plan (SIP) Provisions .....................................................67

 1. RACM/RACT Requirements.........................................................................................................67

 a. RACM........................................................................................................................................67

 b. RACT ........................................................................................................................................69

 2. Reasonable Further Progress..........................................................................................................70

 3. Actual Emissions Inventory...........................................................................................................73

 4. Emissions Inventory Statement......................................................................................................73

 5. Periodic Emissions Inventory ........................................................................................................73

 6. Permit Program Requirements.......................................................................................................73

 7. Gasoline Vapor Recovery ..............................................................................................................74

 8. Inspection and Maintenance Program............................................................................................74

 9. Other Measures ..............................................................................................................................75

 a. NOx SIP Call..............................................................................................................................75

 b. 8-hour Ozone Early Action Compact Regulations....................................................................76

 c. Clean Air Interstate Rule ...........................................................................................................77

 d. Regulation R. 61.62.2, Prohibition of Open Burning................................................................77

 e. Regulation R. 61-62.5, Standard 5.2, Control of Oxides of Nitrogen........................................78

 10. Compliance with Section 110(a)(2) .............................................................................................78

 11. Equivalent Techniques.................................................................................................................78

 12. Contingency Measures.................................................................................................................78

SECTION VII. MOTOR VEHICLE EMISSION BUDGET.....................................................................80

A. Transportation Conformity....................................................................................................................80

 1. Memorandum of Agreement..........................................................................................................80

 2. Conformity Interagency Consultation - York County/RFATS MPO ............................................81
 3. RFATS - CMAQ Projects..............................................................................................................81

B. Highway Mobile Source VOC Insignificance.......................................................................................82

C. Motor Vehicle Emission Budgets..........................................................................................................83
LIST OF FIGURES 

Figure I-1: 8-hour ozone nonattainment boundaries for South Carolina .....................................................9

Figure I-2: Monitors in the Charlotte-Gastonia-Rock Hill, NC-SC MSA .................................................10

Figure I-3: Location of electric generating facilities in and near the Metrolina nonattainment area.........13

Figure I-4: 2002 NOx emissions for the Metrolina nonattainment area and neighboring counties...........14

Figure II-1: The MM5 horizontal domain is the outer most, blue grid,......................................................22

Figure II-2: A more detailed view of the 12-km grid over the VISTAS region. ........................................23

Figure III-1: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour (bottom) 

ozone concentrations for May 25, 2002......................................................................................................32

Figure III-2: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour (bottom) 

ozone concentrations for June 3, 2002........................................................................................................33

Figure III-3: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour (bottom) 

ozone concentrations for June 12, 2002......................................................................................................34

Figure III-4: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour (bottom) 

ozone concentrations for July 3, 2002 ........................................................................................................35

Figure III-5: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour (bottom) 

ozone concentrations for July 17, 2002. .....................................................................................................36

Figure III-6: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour (bottom) 

ozone concentrations for August 2, 2002....................................................................................................37

Figure III-7: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour (bottom) 

ozone concentrations for August 10, 2002..................................................................................................38

Figure III-8: 8-hour ozone scatter plot for North Carolina 12-km grid for June 2002. .............................39

Figure III-9: 8-hour ozone scatter plots for North Carolina 12-km grid for July 2002..............................40

Figure III-10: 8-hour ozone scatter plots for North Carolina 12-km grid for August 2002.......................40

Figure III-11: 8-hour ozone scatter plots for South Carolina 12-km grid for June 2002...........................41
Figure III-12: 8-hour ozone scatter plots for South Carolina 12-km grid for July 2002............................42

Figure III-13: 8-hour ozone scatter plots for South Carolina 12-km grid for August 2002.......................42

Figure III-14: Time series plot of model predicted versus mean 8-hour observed for North Carolina 

monitors for June 2002. ..............................................................................................................................43

Figure III-15: Time series plot of model predicted versus mean 8-hour observed for North Carolina 

monitors for July 2002................................................................................................................................44

Figure III-16: Times series plot of model predicted versus mean 8-hour observed for North Carolina 

monitors for August 2002 ...........................................................................................................................44

Figure V-1: Location and size of the Duke Energy facilities located in the vicinity of the Metrolina 

nonattainment area......................................................................................................................................62
LIST OF TABLES 

Executive Summary Table 1: Attainment Test Results ...............................................................................3

Table I-1: Subpart 2 Classifications and Attainment Dates.........................................................................8

Table I-2: 2001-2003 Design Values.........................................................................................................10

Table II-1: Vertical Layer Definition for MM5 and CMAQ .....................................................................24

Table III-1: 12-km Domain Model Statistics for 8-Hour Ozone ...............................................................31

Table III-2: Metrolina Nonattainment Area Monitor Statistics .................................................................45

Table V-1: Attainment Test Results...........................................................................................................57

Table V-2: 5-Year Average Alternative Attainment Test Results for 2009 ..............................................58

Table V-3: Metrolina DVFs Based on EAC Modeling..............................................................................60

Table V-4: Metrolina DVFs Based on USEPA’s CAIR Modeling............................................................60

Table V-5: Design Values (ppm) for the North Carolina Monitors in the Metrolina Area .......................61

Table V-6: Utility NOx Emission Reductions since 2006 Ozone Season..................................................62

Table VI-1: York County Nonattainment Area 2002 Baseline VOC Emissions (tons/day)......................72

Table VI-2: York County Nonattainment Area 2008 Projected VOC Emissions (tons/day) ....................72

Table VI-3: York County Nonattainment Area 15% RFP Analysis..........................................................72

Table VII-1: 2009 Highway Mobile Source NOx Emissions York County Nonattainment Area.............83

Table VII-2: York County South Carolina NOx MVEB for 2009 ............................................................83
1 

LIST OF APPENDICES 

Appendix A: Correspondence and Guidance Documents

Appendix B: Inspection and Maintenance Program 

Appendix C: Historic Air Quality Data 

Appendix D: Modeling Protocol 

Appendix E: Emissions Inventory Summary 

Appendix F1: Point Source Emissions Inventory Documentation 

Appendix F2: Area and Nonroad Emissions Inventory Documentation 

Appendix F3: On-road Mobile Source Emissions Inventory 

Appendix G: Quality Assurance of the Emissions Inventories 

Appendix H: Emissions Modeling Deviation from Defaults 

Appendix I: Meteorological Model Performance 

Appendix J: Model Performance Evaluation 

Appendix K: Modeling Results 

Appendix L: Attainment Test 

Appendix M: Adopted State Measures 

Appendix N: Grid Resolution Journal Article 

Appendix O: Reasonable Further Progress 

Appendix P: Contingency Measures Documentation 

Appendix Q: Supporting Documentation from VISTAS 

Appendix R: Reasonably Available Control Technology

Appendix S: RFATS Transportation Conformity 
1 

SOUTH CAROLINA AIR QUALITY IMPLEMENTATION PLAN 

RFATS MPO 8-HOUR OZONE ATTAINMENT DEMONSTRATION EXECUTIVE SUMMARY 

I. 8-hour Ozone National Ambient Air Quality Standards

 On April 30, 2004, the United States Environmental Protection Agency (EPA) designated and 

classified that portion of York County, South Carolina within the Rock Hill Fort Mill Area Transportation 

Study (RFATS) Metropolitan Planning Organization (MPO) as a moderate nonattainment area for the 8-

hour ozone National Ambient Air Quality Standards (NAAQS) as part of the Charlotte-Gastonia-Rock Hill,

NC-SC nonattainment area. As a result of this designation, the South Carolina Department of Health and 

Environmental Control (SCDHEC or Department) is required to amend the South Carolina Air Quality 

Implementation Plan, also known as the State Implementation Plan, or SIP, in accordance with the 

requirements of the Clean Air Act (CAA), as amended (42 U.S.C. 7401, et seq.). States involved in a 

multi-State ozone nonattainment area must work together to perform the appropriate modeling analyses to 

identify control measures that will enable the area to achieve attainment as expeditiously as practicable. 

Each State is responsible for its portion of the control program and will be held accountable for controls 

identified for implementation within its State boundaries. 

II. Modeling Protocol 

 The modeling protocol contains an overview of the models and model configurations that were 

chosen for use in future year attainment demonstrations. Because the Charlotte-Gastonia-Rock Hill area 

has been classified moderate nonattainment with a required attainment date set for June 15, 2010, the 

future year emission inventory for 2009 is used for attainment demonstrations. Using USEPA’s guidance

on ozone episode selection, 2002 is meteorologically well-suited for demonstrating future year attainment 

because 2002 exhibited the most number of days (38) exceeding the 0.08 ppm ozone standard and 

because 2002 had numerous (13) and a wide variety (several different types of scenarios) of high ozone

episodes. 

 The models that were chosen include the Mesoscale Meteorological Model (MM5), the Sparse 

Matrix Operator Kernel Emissions (SMOKE) modeling system, and the Community Multiscale Air 

Quality (CMAQ) model. MM5 and SMOKE outputs will provide the meteorological and emissions data 

that will be input into the CMAQ model. After completion of all CMAQ model runs, the final output 

undergoes operational and diagnostic evaluations to determine model performance. While there are 

limitations in each of the three chosen models, each model is considered the best available for its intended 

use. 

 The modeling protocol also provides in-depth discussion on inventories of point source, area source, 

on-road, non-road and biogenic source emission rates. The development and implementation of quality 

assurance (QA) and quality control (QC) strategies is the most important step in developing these 

inventories. QA and QC strategies are described in addition to the process of developing emission control 

strategies that may be applied to demonstrate compliance. 

III. Conceptual Description of Ozone Formation 

 To fully understand the complexity of the ozone formation across North and South Carolina, one 

must first examine the interactions between the biogenic and anthropogenic emissions sources within 

North and South Carolina and throughout the surrounding region, as well as the geographical orientation, 
2 

topography, and the meteorological patterns that develop over each of the Carolinas on a typical 

summertime day. All of these interacting components play a pivotal role in the day-to-day air quality

response across the state. On a few select days each summer and often occurring together in episodes,

these components work together to produce 8-hour ozone concentrations in excess of the NAAQS. The 

frequency and duration of these high ozone episodes in an individual summer season are significantly 

impacted by global scale meteorological patterns and climate deviations (see Appendix D for details). 

IV. Attainment Demonstration Methods and Inputs 

 The attainment modeling for the Charlotte-Gastonia-Rock Hill, NC-SC nonattainment area was 

performed in conjunction with the regional haze modeling being done by the Southeast Regional Planning

Organization, Visibility Improvement State and Tribal Association of the Southeast (VISTAS) and the 

fine particulate matter (PM2.5) and ozone modeling being done by the Association of Southeastern 

Integrated Planning (ASIP). 

 Attainment for the Charlotte-Gastonia-Rock Hill, NC-SC nonattainment area was demonstrated 

through the use of a modeling system consisting of the USEPA’s Models-3/Community Multiscale Air 

Quality (CMAQ) modeling system, the Pennsylvania State University/National Center for Atmospheric 

Research (PSU/NCAR) Mesoscale Meteorological Model (MM5), and the Sparse Matrix Operator Kernel 

Emissions (SMOKE) modeling system. The CMAQ modeling system is a "one-atmosphere" 

photochemical air quality modeling system capable of addressing ozone, fine particulate matter, visibility, 

and acid deposition. The MM5 modeling system is a three-dimensional, limited-area, primitive equation, 

prognostic meteorological model that accurately replicates important meteorological phenomena that are

used as inputs for the CMAQ air quality model. The SMOKE model is principally an emission 

processing system that converts emissions inventory data into formatted emission files that are used as 

inputs for the CMAQ air quality model. 

 Base year 2002 was chosen to process the typical emissions through the SMOKE emissions model, 

which corresponds to the same year as the historic meteorology used in the air quality model. Since the 

mandatory attainment date for the Charlotte-Gastonia-Rock Hill, NC-SC area is June 15, 2010, a future 

year of 2009 was chosen as the modeled attainment year. A comparison of the air quality modeling 

results between these two years is used to determine a relative reduction in future ozone, which is used in 

the attainment demonstration. A key step in attainment demonstration modeling is the selection of 

episodes to model. For this attainment demonstration, criteria set out in the USEPA’s Guidance on the 

Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, 

and Regional Haze ("Attainment Guidance") were used to select the episodes that were used in the 

attainment modeling for the Charlotte-Gastonia-Rock Hill, NC-SC area. The 2002 peak ozone season was 

chosen to model as this episode covers several criteria listed in the USEPA Attainment Guidance, 

including the modeling of weekends and a sufficient number of days to ensure a robust modeled 

attainment test. Modeling the 2002 peak ozone season will also accomplish the goal of encompassing a 

myriad of meteorological conditions that influence tropospheric ozone formation. A detailed discussion 

of the configuration and description of CMAQ, MM5, and SMOKE, as well as a discussion of the episode 

selection process can be found in the Modeling Protocol (Appendix D). 

 Another consideration for the attainment modeling was an appropriate domain for which to model. 

The CMAQ model was run in one-way nested grid mode, which allowed the larger outer domains to feed 

concentration data to the inner nested domain. A high resolution 12-km grid covering the entire VISTAS 

region was chosen as the horizontal domain modeling domain for this attainment modeling. The vertical

structure of the modeling is primarily defined by the MM5 34 layer terrain following coordinate system

that extends from the surface to the 100 mb layer. The vertical domain in the CMAQ air quality modeling 

was reduced to 19 layers using a layer-averaging scheme, reducing the computational cost of the 
3 

simulations with only a minor effect on model performance. 

V. Model Performance Evaluation 

 Overall, the SCDHEC believes that the model performance is well within the limits of acceptable 

performance established in the USEPA’s. Attainment Guidance For the most part, mean normalized bias 

and mean normalized gross error fall within the recommended limits for good model performance. The 

model appears to do a good job of capturing ozone concentrations through various episode ramp-up and 

clean-out cycles. There are some instances of under and over predictions. However, in most instances,

the model does well in simulating the afternoon ozone peak throughout the Carolinas and produces results 

reliable enough for use as meteorological inputs in the Metrolina Area attainment demonstration CMAQ 

modeling. 

VI. Attainment Demonstration 

 The attainment demonstration is based on relative reductions of ozone rather than absolute modeling 

results and is only applied at grid cells near the monitors. Reviewing the modeling results of how the 

predicted ozone decreases in the future years and how widespread the reductions are play an important 

role for the State in determining if additional controls should be considered. 

 The air quality modeling is used in a relative sense by determining what relative reduction in ozone 

occurred between the baseline year (2002) and the attainment year (2009). Table 1 lists the attainment 

test results for the Charlotte-Gastonia-Rock Hill, NC-SC area. The first two columns are the monitoring 

site and the county in which the site is located. The next three columns are the modeling base year design 

value (DVB), the relative response factor (RRF) and the future design value (DVF). According to the 

USEPA’s Attainment Guidance, areas with future design values between 0.082 and 0.087 ppm need to 

provide additional weight of evidence that the area will attain the 8-hour ozone NAAQS. Weight of 

evidence to demonstrate attainment is not required for the monitor in York County. 

Executive Summary Table 1: Attainment Test Results

2009 

Monitoring Site County 

DVB (ppm) 

5-year weighted 

2000-2004 RRF DVF 

(ppm) 

Arrowood Mecklenburg 0.0847 0.892 0.075 

County Line Mecklenburg 0.0973 0.874 0.085 

Crouse Lincoln 0.0907 0.868 0.078 

Enochville Rowan 0.0970 0.870 0.084 

Garinger (Plaza) Mecklenburg 0.0953 0.883 0.084 

Monroe Union 0.0870 0.884 0.076 

Rockwell Rowan 0.0973 0.862 0.083 

York York, SC* 0.0830 0.861 0.071 

*Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC

nonattainment area 

VII. Attainment of the 8-hour Ozone NAAQS by 2009 

 The SCDHEC believes that the modeling attainment demonstration, in conjunction with the weight 

of evidence analyses, provides the necessary evidence that the Charlotte-Gastonia-Rock Hill, NC-SC 

nonattainment area will attain the NAAQS by the prescribed attainment date. 
4 

 The North Carolina Division of Air Quality (NCDAQ) and South Carolina Department of Health and 

Environmental Control (SCDHEC) provided strong weight of evidence that the Charlotte-Gastonia-Rock 

Hill, NC-SC nonattainment area will attain the 8-hour ozone NAAQS by 2009. This weight of evidence 

included looking at alternative methods to calculate the future design values, additional metrics of air 

quality modeling results, air quality modeling results from other studies, positive trends in observed air 

quality and additional emissions reductions, and additional measures that were not included in the air

quality modeling. 
5 

SECTION I. SOUTH CAROLINA AIR QUALITY IMPLEMENTATION PLAN

 On April 30, 2004, the United States Environmental Protection Agency (EPA) designated and 

classified that portion of York County, South Carolina within the Rock Hill Fort Mill Area Transportation 

Study (RFATS) Metropolitan Planning Organization (MPO) as a moderate nonattainment area for the 8-

hour ozone National Ambient Air Quality Standards (NAAQS) as part of the Charlotte-Gastonia-Rock Hill 

nonattainment area. As a result of this designation, the South Carolina Department of Health and 

Environmental Control (SCDHEC or Department) is required to amend the South Carolina Air Quality 

Implementation Plan, also known as the State Implementation Plan, or SIP, in accordance with the 

requirements of Title I, Part D - Plan Requirements for Nonattainment Areas, Subpart 1, Section 172, and 

Subpart 2, Section 182 of the Clean Air Act (CAA), as amended (42 U.S.C. 7401, et seq.). States involved 

in a multi-State ozone nonattainment area must work together to perform the appropriate modeling 

analyses to identify control measures that will enable the area to achieve attainment as expeditiously as 

practicable. Each State is responsible for its portion of the control program and will be held accountable 

for controls identified for implementation within its State boundaries. 

 

A. Introduction to 8-Hour Ozone NAAQS

 1. Ground-Level (Tropospheric) Ozone 

 Ozone is a colorless gas that occurs naturally in the atmosphere and can be found in the air we 

breathe. Ozone is composed of three atoms of oxygen (O3), one more than the common oxygen molecule 

(O2) we need to breathe to sustain life. The additional oxygen atom makes ozone extremely reactive. 

Ozone in the Earth's upper atmosphere, known as stratospheric ozone, shields the Earth from the harmful 

effects of the sun's ultraviolet rays. Ozone found in the atmosphere closer to the Earth's surface 

(tropospheric ozone) is considered a harmful air pollutant due to its adverse impacts on human health and 

welfare. 

 Tropospheric ozone is commonly referred to as ground-level ozone and sometimes called smog. 

Ozone is not emitted directly by the combustion of fuels. Ozone is formed in the atmosphere by the 

reaction of volatile organic compounds (VOC) and oxides of nitrogen (NOx) in the presence of sunlight. 

These air pollutants, often referred to as ozone precursors, are emitted by many types of pollution sources, 

including on-road and off-road motor vehicles and engines, power plants and industrial facilities, and

smaller sources, collectively referred to as area sources. Ozone is predominately a summertime air 

pollutant. Changing weather patterns contribute to yearly differences in ozone concentrations from region 

to region. Ozone and the pollutants that form ozone also can be transported into an area from pollution 

sources found hundreds of miles upwind. 

 2. Health Concerns 

 During the hot summer months, ground-level ozone reaches unhealthy levels in several parts of the 

country. Ozone has been associated with increased hospitalizations and emergency room visits, school 

absences, and reduced activity and productivity. Even at relatively low levels, breathing ozone can trigger 

a variety of health problems. Ozone can irritate the respiratory system, causing coughing, throat 

irritation, an uncomfortable sensation in the chest, and/or pain when breathing deeply. Ozone can worsen 

asthma and possibly other respiratory diseases, such as bronchitis and emphysema. When ozone levels are 

high, more people with asthma have attacks that require a doctor's attention or the use of additional 

medication. Ozone can reduce lung function and make it more difficult to breathe deeply, and breathing 

may become more rapid and shallow than normal, thereby limiting a person's normal activity. In 

addition, breathing ozone can inflame and damage the lining of the lungs, which may lead to permanent 

changes in lung tissue, irreversible reductions in lung function, and a lower quality of life if the 
6 

inflammation occurs repeatedly over a long time period (months, years, a lifetime). People who are 

particularly susceptible to the effects of ozone include children and adults who are active outdoors, people 

with respiratory disease, such as asthma, and people with unusual sensitivity to ozone. 

 3. National Ambient Air Quality Standards (NAAQS)

 The CAA requires the USEPA to set NAAQS for pollutants considered harmful to public health and 

the environment. National primary and secondary ambient air quality standards under Section 109 of the 

CAA are set forth in Title 40 of the Code of Federal Regulations, part 50. NAAQS are subject to revision, 

and additional primary and secondary standards may be promulgated as the USEPA deems necessary to 

protect the public health and welfare. The USEPA has promulgated primary and secondary NAAQS for 

carbon monoxide, lead, nitrogen dioxide, particulate matter, sulfur oxides, and ground level ozone. The 

USEPA calls these pollutants "criteria" air pollutants because it regulates them by developing human 

health-based and/or environmentally-based criteria (science-based guidelines) for setting permissible 

levels. For each pollutant, a health-based or "primary" standard has been set to protect public health in 

general, and a welfare-based or "secondary" standard has been set to protect quality of life and the 

environment. Primary standards set limits to protect public health, including the health of "sensitive" 

populations such as asthmatics, children, and the elderly. Secondary standards set limits to protect public 

welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and 

buildings. 

 4. 8-Hour Ozone NAAQS 

 In 1997, the USEPA revised the NAAQS for ground-level ozone, setting the standard at 0.08 parts 

per million (ppm) averaged over an 8-hour period. At each ozone monitoring site, hourly average 

concentrations are recorded in parts per million (ppm). Running 8-hour averages are computed from the

hourly ozone concentration data for each hour of the year. The daily maximum 8-hour concentration for a 

given calendar day is the highest of the 24 possible 8-hour average concentrations computed for that day. 

The standard-related summary statistic is the three-year average of the annual fourth-highest daily 

maximum 8-hour average ozone concentrations. The three-year average is computed using the three most 

recent, consecutive calendar years of monitoring data. This three-year average annual fourth-highest 

daily maximum 8-hour average ozone concentration is also the air quality design value for the monitoring 

site. A violation of the 8-hour ozone NAAQS occurs when the computed design value is greater than or 

equal to 0.085 ppm. 

B. Nonattainment Area Designations and Classifications 

 1. Area Designations 

 On February 8, 1979, the USEPA promulgated the 0.12 parts per million (ppm) 1-hour ozone 

standards, (44 Federal Register 8202). On July 18, 1997, the USEPA promulgated a revised ozone 

standard of 0.08 ppm, measured over an 8-hour period [i.e., the 8-hour standard (62 FR 38856)]. Upon 

promulgation of a new or revised NAAQS, the CAA requires the USEPA to designate areas as attaining 

or not attaining that NAAQS. On April 30, 2004, the USEPA announced and promulgated designations, 

classifications, and boundaries for every area in the United States with respect to the 8-hour ozone 

NAAQS (69 FR 23857). 

 The 8-hour ground-level ozone NAAQS design values were calculated for each ozone monitor in the 

United States. The USEPA area designations were generally based on air quality monitoring data 

collected from 2001 to 2003. The highest monitor design value in an area was used to determine its 

designation. The CAA then specifies requirements for areas based on whether such areas are or are not
7 

attaining the NAAQS. 

 2. Nonattainment Area Boundaries 

 The CAA defines a nonattainment area as an area that is violating an ambient standard or is 

contributing to a nearby area that is violating the standard. Once it is determined that a monitor is

recording a violation, the next step is to determine if there are any nearby areas that are contributing to the 

violation and include them in the designated nonattainment area. When evaluating the air quality factors 

for individual areas, the USEPA took into account its view that, in most cases, data recorded by an ozone 

air quality monitor represents air quality throughout the area in which the monitor is located. The USEPA 

used the county as the basic jurisdictional unit in determining the extent of the area reflected by the ozone 

monitor data. As a result, if an ozone monitor was violating the standard based on the 2001–2003 data, 

the USEPA designated the entire county as nonattainment. The actual size of the nonattainment area may 

be larger or smaller, depending on air quality-related technical factors contained in the USEPA guidance 

on determining nonattainment area boundaries for the 8-hour ozone standard. 

 Section 107(d)(4) of the CAA established the Consolidated Metropolitan Statistical Area (CMSA) or 

Metropolitan Statistical Area (MSA) as the presumptive boundary for areas designated nonattainment in 

1991 for violating the ozone NAAQS. Once a CMSA, MSA, or single county area was determined to 

contain a monitor that was violating the standard, the USEPA and the State considered several factors,

including emissions, population density, traffic congestion, commercial development, industrial 

development, meteorological conditions, and pollution transport in establishing the nonattainment area

boundaries. It is necessary to evaluate all counties in and around an area containing a monitor that is 

violating the standard to justify including counties outside the CMSA or MSA or excluding counties in 

the CMSA or MSA. In some cases, in considering these factors as well as information and 

recommendations provided by the State, the USEPA determined that only part of a county was 

contributing to the nearby nonattainment area. 

 3. Nonattainment Area Classifications 

 Title I, part D of the CAA contains two sets of provisions that address planning and control 

requirements for nonattainment areas. Subpart 1 (which is referred to as "basic" nonattainment) contains 

general, less prescriptive, requirements for nonattainment areas for any pollutant governed by a NAAQS, 

including ozone. Subpart 2 (which is referred to as "classified" nonattainment) provides more specific 

requirements for ozone nonattainment areas. 

 An area designated nonattainment for the 8-hour ozone NAAQS with a 1-hour design value less than 

0.121 ppm at the time of designation is subject to the requirements of Subpart 1 and is covered under 

Section 172(a)(1) of the CAA. These "basic" nonattainment areas have five years from designation to 

attain the standard. The USEPA has provided flexibility for areas that have entered into a compact and 

take early action to achieve emissions reductions necessary to attain the 8-hour ozone standard. This

action defers the effective date of the nonattainment designation for these areas and establishes 

regulations governing future actions with respect to these areas. The USEPA has also promulgated 

deferral of the effective date of the nonattainment designation for Early Action Compact areas. 

 8-hour ozone nonattainment areas with 1-hour design values of 0.121 ppm or greater at the time of 

designation are subject to the provisions of Subpart 2 and are classified in accordance with Section 181 of 

the CAA as marginal, moderate, serious, severe, or extreme depending on the area's 8-hour design value. 

Nonattainment areas with more serious ozone pollution, as differentiated by these area classifications, are 

subject to more control requirements as prescribed in Section 182 of the CAA. These prescribed 

requirements are designed to bring areas into attainment by their specified attainment dates, which are 
8 

also based upon the area's classification. (See Table I-1: "Subpart 2 Classifications and Attainment 

Dates.") 

Table I-1: Subpart 2 Classifications and Attainment Dates 

Classification Design Value Range (ppm) Attainment Date 

Marginal 0.085 up to 0.092 June 15, 2007 

Moderate 0.092 up to 0.107 June 15, 2010 

Serious 0.107 up to 0.120 June 15, 2013 

Severe 15 0.120 up to 0.127 June 15, 2019 

Severe 17 0.127 up to 0.187 June 15, 2021 

Extreme 0.187 and above June 15, 2024 

C. 8-hour Ozone Designations for South Carolina 

 On April 15, 2004, the USEPA promulgated 8-hour ozone designations and classifications for all of 

the counties in South Carolina based on the design values calculated from air quality monitoring data 

collected during the 2001, 2002, and 2003 ozone seasons. Almost all of South Carolina was designated 

unclassifiable/attainment for the 8-hour ozone standard; however, the following three areas of South 

Carolina were designated nonattainment: 

 1. Greenville-Spartanburg-Anderson Area: This nonattainment area includes the entirety of 

Greenville, Spartanburg, and Anderson Counties. The Greenville-Spartanburg-Anderson Area was 

designated a Subpart 1 nonattainment area. The Greenville-Spartanburg-Anderson Area has opted to 

enter into an Early Action Compact and take early action to achieve emissions reductions necessary to 

attain the 8-hour ozone standard. The USEPA has promulgated deferral of the effective date of the 

nonattainment designation for the Greenville-Spartanburg-Anderson Area. 

 2. Columbia Area: This nonattainment area includes the portions of Richland and Lexington 

counties within the borders of the Columbia Area Transportation Study (COATS) Metropolitan Planning 

Organization (MPO). The Columbia Area was designated a Subpart 1 nonattainment area. The Columbia 

Area has opted to enter into an Early Action Compact and take early action to achieve emissions 

reductions necessary to attain the 8-hour ozone standard. The USEPA has promulgated deferral of the 

effective date of the nonattainment designation for the Columbia Area. 

 3. Charlotte-Gastonia-Rock Hill, NC-SC Area: The Charlotte-Gastonia-Rock Hill, NC-SC 

nonattainment area includes that portion of York County, South Carolina within the Rock Hill Fort Mill

Area Transportation Study (RFATS) Metropolitan Planning Organization (MPO). The CharlotteGastonia-Rock Hill, NC-SC Area (also referred to as the Metrolina area) is classified as a Subpart 2 

moderate nonattainment area. 

 Figure I-1, 8-hour ozone nonattainment boundaries for South Carolina, outlines the majority of the 

State that was designated attainment/unclassifiable and highlights the corresponding boundaries of the

three areas designated nonattainment. 
9 

Figure I-1: 8-hour ozone nonattainment boundaries for South Carolina 

D. Charlotte-Gastonia-Rock Hill, NC-SC Metropolitan Statistical Area 

1. Charlotte-Gastonia-Rock Hill, NC-SC Metropolitan Statistical Area 

 The Charlotte-Gastonia-Rock Hill, NC-SC Metropolitan Statistical Area (MSA), as defined by the 

Federal Office of Management and Budget (OMB) on June 30, 1999, consists of Cabarrus, Gaston, 

Lincoln, Mecklenburg, Rowan, and Union Counties in NC; and York County in SC. MSA boundaries are 

based on city and county populations in urbanized areas, with "outlying counties" being included in the 

MSA contingent upon their commuting patterns into the central counties. Under OMB standards, the 

county (or counties) that contains the largest city becomes the "central county" (counties), along with any 

adjacent counties that have at least 50 percent of their populations in the urbanized area surrounding the 

largest city. The MSA are named according to the populations of the largest central cities. As noted

previously, the CMSA or MSA is the USEPA presumptive boundary for areas designated nonattainment 

for violating the ozone NAAQS. 

 2. Monitors in the Charlotte-Gastonia-Rock Hill, NC-SC MSA 

 Figure I-2: "Monitors in the Charlotte-Gastonia-Rock Hill, NC-SC MSA" displays where monitors 

are located in the Charlotte-Gastonia-Rock Hill, NC-SC MSA. There are no ozone monitors located in 

either Cabarrus County or Gaston County in NC. The historic air quality data for the monitors in the 

Charlotte-Gastonia-Rock Hill, NC-SC MSA is listed in Appendix C. 
10 

Figure I-2: Monitors in the Charlotte-Gastonia-Rock Hill, NC-SC MSA 

 3. 2001-2003 Design Values for Monitors Located in the MSA 

 Table I-2: "2001-2003 Design Values" lists the annual fourth-highest daily maximum 8-hour 

average ozone concentration and calculated design values for all of the monitors within the CharlotteGastonia-Rock Hill, NC-SC MSA. 

Table I-2: 2001-2003 Design Values 

4

th Highest 8-hour Ozone Value 

Monitor County 

2001 2002 2003 

2001-2003 

Design Value 

Crouse Lincoln 0.094 0.095 0.089 0.092 

County Line Mecklenburg 0.099 0.107 0.088 0.098 

Garinger (Plaza) Mecklenburg 0.099 0.103 0.086 0.096 

Arrowood Mecklenburg 0.086 0.094 0.073 0.084 

Enochville Rowan 0.103 0.108 0.087 0.099 

Rockwell Rowan 0.097 0.106 0.098 0.100 

Monroe Union 0.081 0.100 0.083 0.088 

York York, SC* 0.080 0.096 0.076 0.084 

Values shown in bold represent violations of the 8-hour ozone NAAQS 

*Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC

nonattainment area 
11 

E. Charlotte-Gastonia-Rock Hill, NC-SC Area 

 1. Metrolina Area 

 The USEPA designated and classified ozone nonattainment areas according to the calculated 2001-

2003 design values listed in Table I-2: "2001-2003 Design Values." An area referred to as the CharlotteGastonia-Rock Hill, North Carolina-South Carolina (Metrolina) Area was designated a nonattainment 

area for the 8-hour ozone standard. 

 2. Metrolina Nonattainment Area Boundaries 

 The USEPA considered several factors, including emissions, population density, traffic congestion, 

commercial development, industrial development, meteorological conditions, and pollution transport, in

evaluating all counties in and around the MSA to establish the nonattainment area boundaries. The entire 

North Carolina portion of the MSA, which includes Cabarrus, Gaston, Lincoln, Mecklenburg, Rowan and 

Union Counties, was designated to be part of the Metrolina nonattainment area. Two North Carolina areas 

outside of the MSA, Coddle Creek Township and Davidson Township in Iredell County, were determined 

to be contributing to violating monitors and are included in the Metrolina nonattainment area. Although 

the monitor in York County, South Carolina during that time was below the 8-hour ozone standard of 

0.085 parts per million (ppm), the USEPA determined that a portion of York County contributed to 

violating monitors in nearby North Carolina. That portion of York County, South Carolina, which is 

situated within the Rock Hill Fort Mill Area Transportation Study (RFATS) Metropolitan Planning 

Organization (MPO) was designated as a partial county nonattainment area and included in the Metrolina

nonattainment area. (It should be noted that the York County ozone monitor is located outside of the 

designated nonattainment area boundary.) 

 3. Metrolina Nonattainment Area Classification 

 The USEPA resolved that the Metrolina nonattainment area classification should be based on the 

highest 8-hour ozone design value calculated for any of the monitors located within the boundaries of the 

designated nonattainment area. In reviewing the data analysis reflected in Table I-2: "2001-2003 Design 

Values," the highest regional design value was 0.100 ppm. 

 In accordance with the classification criteria summarized in Table I-1: "Subpart 2 Classifications and 

Attainment Dates," the USEPA classified the Metrolina area as a Subpart 2, moderate nonattainment area. 

 The Metrolina nonattainment area must demonstrate attainment of the 8-hour ozone NAAQS by no 

later than June 15, 2010. 

F. Conceptual Description of Ozone Formation in the Metrolina Area 

 The full conceptual description of ozone formation in North Carolina and the Metrolina 

nonattainment area is discussed in Appendix D. This section will focus on the conceptual description of 

ozone formation in the Metrolina area. 

 As stated earlier, ozone forms through the reaction of NOx and VOC emissions. Due to generally 

warm and moist climate of the Carolinas, vegetation abounds in many forms. The emissions from natural

sources, such as vegetation, are referred to as biogenic emissions and account for approximately 90% of 

the total VOC emissions in the Carolinas. This results in the Carolinas being a NOx-limited environment, 

which means that reductions in NOx emissions will have the greatest impact on reducing ozone formation 
12 

in the Carolinas, including the Metrolina area. 

 North Carolina’s most populous metropolitan regions are located in the central portions or the 

Piedmont of the state. The three largest cities (Charlotte, Greensboro, and Raleigh) form a partial 

crescent extending from the southwest to the northeast. This combination of metropolitan regions is often 

referred to as the Piedmont Crescent. A network of interstate and intrastate highways interconnects these 

three largest cities and further extends into adjoining states (such as South Carolina) in a general 

southwest to northeast pattern. The mobile-based NOx emissions follow these highway networks with the 

highest emissions occurring in or near the city centers. The industrial point sources with both 

anthropogenic NOx and VOC emissions are also generally located in close proximity to the cities and the 

major road networks. Finally, North Carolina’s largest NOx point sources are electric generating 

facilities, which are spatially scattered around state but are most heavily concentrated near the Piedmont 

Crescent. Figure I-3 displays the location of the electric generating facilities in and near the Metrolina 

nonattainment area. 
13 

Figure I-3: Location of electric generating facilities in and near the Metrolina 

nonattainment area 

 By combining each of the major emission source categories (biogenic source VOC emissions and 

mobile sources (highway and non-road) and electric generating facilities NOx emissions), the highest 

concentrations of precursor pollutants for ozone formation are focused throughout the Piedmont Crescent, 

which includes the Metrolina area. Therefore, the greatest potential for ozone formation, with the right 

weather conditions, is also in this central portion of North Carolina. 

 Figure I-4 displays the breakdown of man-made NOx emissions in and near the Metrolina 

nonattainment area. This figure shows that in the Metrolina area, including the counties that neighbor the 

nonattainment area, point source and highway mobile source NOx emissions account for over three 

quarters on the NOx emissions. The majority of the point source NOx emissions come from the electric 

generating facilities. Therefore, these sources that most impact ozone formation in the Metrolina region 

are highway mobile sources and electric generating facilities. 
14 

Figure I-4: 2002 NOx emissions for the Metrolina nonattainment area and neighboring counties 

 In addition to the emissions, meteorology plays an important role in ozone formation as well. 

Almost all high ozone episodes occurring in the Southeastern United States will have some common 

meteorological characteristics, including warm temperatures, lower relative humidity, little or no 

precipitation, and relatively light winds. These conditions are nearly universally indicative of regional 

high-pressure patterns causing large-scale sinking (subsiding) air at various levels of the atmosphere. The 

differences in the position, strength, and movement of these high pressure areas, along with differences in 

various mid-to-upper level wind patterns, allow staff to discern five meteorological scenarios, or 

“regimes”, in which high ozone episodes are likely to occur in the Carolinas. These meteorological 

regimes are discussed in detail in Appendix D.

 The regional transport of ozone into the Metrolina area also contributes to the high ozone values 

observed in the Metrolina area. Just outside the borders of the Carolinas is a collection of large 

metropolitan regions. These metropolitan regions have similar emissions profiles and frequencies of high 

ozone concentrations leading to exceedances of the 8-hour ozone NAAQS. It is reasonable to conclude 

that precursor pollutants, as well as formed ozone, can be transported from any of these larger 

metropolitan regions into the Carolinas with an appropriate wind flow orientation from one or more of 

these regions. In recognition of the effects of regional transport of ozone, the USEPA has promulgated 

two rules to help reduce the effects of transported pollutants; the NOx SIP Call Rule and the Clean Air 

Interstate Rule. 

 In additional to regional transport, recirculated pollution around the Metrolina area affects high 

ozone events. Winds in the lower and middle atmosphere can shift around in a variety of directions. In 

the most frequent scenarios, winds transition from one direction to another in a clockwise fashion during 

the extent of the complete synoptic cycle or scenario. This clockwise shifting of the winds is a key 

characteristic of eastward-moving high pressure systems in the Northern Hemisphere. In a large 

recirculation pattern, plume(s) of precursor pollutants and formed ozone may leave the Metrolina area one 

day, travel across multiple regions, then return to the very air shed from where it started within a matter of 

days. Throughout the journey of air parcels in this type pattern, precursor pollutants and ozone are 

constantly being exchanged and added to the air parcels from each source sector and metropolitan region 

along the way, irrespective of any geo-political boundaries. In such smaller scale recirculation patterns, 

precursor pollutants and ozone from two neighboring metropolitan regions can exchange back and forth 

over a series of days, especially as a strong area of high-pressure moves from west to east across the

region. 

 To summarize the conceptual description of ozone formation in the Metrolina area, various 

Point

25%

Area

4% Nonroad M obile

17%

Highway M obile

54%
15 

meteorological regimes in conjunction with biogenic VOC emissions and man-made NOx emissions can 

result in high ozone values in the Metrolina area. Reductions in highway mobile source and electric 

generating facility NOx emissions in and near the Metrolina area will have the greatest impact on reducing 

ozone formation. 

G. Clean Air Act Requirements 

 Sections 172(c), 182(a), and 182(b) of the Clean Air Act (CAA), as amended (42 U.S.C. 7401, et 

seq.), prescribe the requirements for ozone nonattainment areas. All designated nonattainment areas must 

comply with the general requirements mandated by Section 172(c) of the CAA. As a Subpart 2, moderate 

ozone nonattainment area, the Metrolina area must also meet the additional requirements prescribed by 

Section 182 of the CAA. Each State in which all or part of a moderate nonattainment area is located shall 

make the submissions described under Section 182(a) (relating to marginal nonattainment areas) and shall 

also submit the revisions to the applicable implementation plan described under Section 182(b) with 

respect to moderate nonattainment areas. These requirements are listed below and are discussed in more 

details in Section VI of this attainment SIP. 

 1. Section 172(c) - Nonattainment Plan Provisions

 a. Reasonably available control measures (RACM) 

 b. Reasonable further progress (RFP) 

 c. Actual emissions inventory and periodic emissions inventory 

 d. New source review (NSR) / Attainment Demonstration 

 e. Permit requirements for new and modified sources 

 f. Other measures as may be necessary to provide attainment by specified attainment date 

 g. Compliance with Section 110(a)(2) 

 h. Equivalent techniques 

 i. Contingency measures 

 2. Section 182(a) - Plan Submissions and Requirements for Marginal Areas 

 a. Actual emissions inventory in accordance with 172(c)(3) 

 b. Corrections to SIP 

 i. Reasonably available control technology (RACT) 

 ii. Motor vehicle inspection and maintenance (I/M) 

 iii. Permit programs 

 c. Periodic emissions inventory 

 i. General emission inventory every three years until area is redesignated to attainment 

 ii. Annual emissions statement for sources emitting 25 tons per year or greater of VOC or 

 NOx

 3. Section 182(b) - Additional Plan Submissions and Requirements for Moderate Areas 

 a. Reasonable further progress 

 b. Reasonable available control technology 

 c. Gasoline vapor recovery 

 d. Motor vehicle I/M 

 e. Offset requirements of at least 1.15 to 1. 
16 

SECTION II. ATTAINMENT DEMONSTRATION METHODS AND INPUTS 

 The attainment modeling for the Metrolina nonattainment area was performed in conjunction with 

the regional haze modeling being done by the Southeast Regional Planning Organization, Visibility 

Improvement State and Tribal Association of the Southeast (VISTAS) and the fine particulate matter 

(PM2.5) and ozone modeling being done by the Association of Southeastern Integrated Planning (ASIP). 

VISTAS and ASIP are run by the ten Southeast states (Alabama, Florida, Georgia, Kentucky, Mississippi,

North Carolina, South Carolina, Tennessee, Virginia and West Virginia). Since the regional haze 

modeling uses annual simulations and includes an intermediate year that is the attainment year required 

for the Metrolina nonattainment area, the NCDAQ and the SCDHEC decided to use the this modeling for 

our ozone attainment demonstration. The sections below outline the methods and inputs used by 

VISTAS/ASIP for this regional modeling. 

A. Analysis Method 

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

system. VISTAS decided to use the following modeling system: 

 1. Air Quality Model: the USEPA’s Models-3/Community Multiscale Air Quality (CMAQ) 

modeling system is a ‘One-Atmosphere’ photochemical grid model capable of addressing ozone, 

particulate matter (PM), visibility and acid deposition at regional scale for periods up to one year. 

 2. Meteorological Model: The Pennsylvania State University/National Center for Atmospheric 

Research (PSU/NCAR) Mesoscale Meteorological Model (MM5) is a nonhydrostatic, prognostic 

meteorological model routinely used for urban- and regional-scale photochemical, fine particulate matter, 

and regional haze regulatory modeling studies. 

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

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

mobile, nonroad mobile, area, point, fire and biogenic emission sources for photochemical grid models.

 Additionally, a historical year is selected to model that represent typical meteorological conditions in 

the Southeast when high ozone, PM2.5 and poor visibility are observed throughout the Region. Once the 

historical year is selected, meteorological inputs are developed using the meteorological model. Emission 

inventories are also developed for the historical year and processed through the emissions model. These 

inputs are used in the air quality model to predict ozone, PM2.5 and visibility, with the results compared to 

the historic data. The model performance is evaluated by comparing the modeled predicted data to the 

historic air quality data. 

 Once model performance is deemed adequate, typical baseline and future year emissions are 

processed through the emissions model. For this demonstration, the baseline year was 2002, which 

corresponds with the same year as the historic meteorology used in the modeling. The attainment future 

year the NCDAQ and the SCDHEC are using for this demonstration is 2009, since the mandatory 

attainment date for the Metrolina area is June 15, 2010. Since this attainment date is set prior to the 

completion of the 2010 ozone season, the attainment of the NAAQS would have to be met by the end of 

the 2009 ozone season. These 2002 baseline and 2009 future typical emissions are processed through the 

air quality model with the meteorological inputs. The air quality modeling results are used to determine a 

relative reduction in future ozone, which is used in the attainment demonstration. 

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

B. Model Selection 

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

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

accessible to all stakeholders. Scientifically appropriate means that the models address important 

physical and chemical phenomena in sufficient detail using peer-reviewed methods. Freely accessible 

means that model formulations and coding are freely available for review and that the models are 

available to stakeholders and their consultants for execution and verification at no or low cost. 

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

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

this modeling attainment demonstration. 

 1. Selection of Photochemical Grid Model 

 a. Criteria 

 For a photochemical grid model to qualify as a candidate for use in an attainment demonstration of 

the 8-hour ozone NAAQS, a State needs to show that it meets several general criteria: 

 • The model has received a scientific peer review; 

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

 • Databases needed to perform the analysis are available and adequate; 

 • 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; and 

 • 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. 

 b. Overview of CMAQ 

 The photochemical model selected for this study was CMAQ version 4.4. For more than a decade, 

the USEPA has been developing the Models-3 CMAQ modeling system with the overarching aim of 

producing a ‘One-Atmosphere’ air quality modeling system capable of addressing ozone, fine particulate

matter, visibility, and acid deposition within a common platform. The original justification for the 

Models-3 development emerged from the challenges posed by the 1990 CAAA and the USEPA’s desire 

to develop an advanced modeling framework for ‘holistic’ environmental modeling utilizing state-ofscience representations of atmospheric processes in a high performance computing environment. The 

USEPA completed the initial stage of development with Models-3 and released the CMAQ model in mid 

1999 as the initial 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 one-atmospheric 

modeling. Since the SCDHEC will be using the same modeling exercise for the ozone attainment 

demonstration SIP 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 CMAQ’s theoretical formulation and technical

implementation make the model well suited for annual particulate matter modeling. 

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

CMAQ model, can be found in the Modeling Protocol (Appendix D). 
18 

 2. Selection of Meteorological Model 

 a. 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 the model’s ability to both 

accurately replicate important meteorological phenomena in the region of study and interface with the rest 

of the modeling systems--particularly the photochemical grid model. With these issues in mind, the 

following criteria were established for the meteorological model to be used in this study: 

 • Non-Hydrostatic Formulation 

 • Reasonably current, peer reviewed formulation 

 • Simulates Cloud Physics 

 • Public availability at no or low cost 

 • Output available in I/O API format 

 • Supports Four Dimensional Data Assimilation (FDDA) 

 • Enhanced treatment of Planetary Boundary Layer heights for air quality modeling 

 b. 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 modeling 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 the same coordinate system. 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 adjustment. 

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

both of which represent sub-grid-scale turbulent fluxes of heat, moisture, and momentum. One scheme 

uses a first-order eddy diffusivity formulation for stable and neutral environments and a modified firstorder 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. 

 Results of detailed performance evaluations of the MM5 modeling system in regulatory air quality 

application studies have been widely reported in the literature (e.g., Emery et al., 1999; Tesche et al., 

2000, 2003), and many have involved comparisons with other prognostic models such as the Regional 

Atmospheric Modeling System (RAMS) and the Systems Application International Mesoscale Model. 
19 

The MM5 enjoys a far richer application history in regulatory modeling studies compared with RAMS or 

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

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

somewhat better photochemical model inputs than alternative models. 

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

MM5 model, can be found in the Modeling Protocol (Appendix D). 

 3. Selection of Emissions Processing System 

 a. Criteria 

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

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

clarification of this criterion and additional desirable criteria for effective use of the system. 

 • File System Compatibility with the I/O API 

 • File Portability 

 • Ability to grid emissions on a Lambert Conformal projection 

 • Report Capability 

 • Graphical Analysis Capability 

 • MOBILE6 Mobile Source Emissions 

 • Biogenic Emissions Inventory System version 2 (BEIS-3) 

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

 • Ability to process control strategies 

 • No or low cost for acquisition and maintenance

 • Expandable to support other species and mechanisms 

 b. Overview of SMOKE 

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

emission processing system and not a true emissions modeling system in which emissions estimates are 

simulated from ‘first principles’. This means that, with the exception of mobile and biogenic sources, its 

purpose is to provide an efficient, modern tool for converting emissions inventory data into the formatted 

emission files required by an air quality simulation model. For mobile sources, SMOKE actually 

simulates emissions rates based on input mobile-source activity data, emission factors and outputs from 

transportation travel-demand models. 

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

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

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

approach utilized throughout SMOKE permits both rapid and flexible processing of emissions data. The 

processing is rapid because SMOKE utilizes a series of matrix calculations instead of less efficient 

algorithms used in previous systems. The processing is flexible because the processing steps of temporal 

projection, controls, chemical speciation, temporal allocation, and spatial allocation have been separated 

into independent operations 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 
20 

models. It supports both gridded and county total land use schemes 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 D). 

C. Episode Selection 

 A crucial step to SIP modeling is the selection of episodes to model. Several considerations need to

be weighed before settling on not only which days to model, but how many days are modeled for each 

episode. This section details the guidance and process by which episodes were selected for the 8-hour

Ozone SIP modeling package. 

 1. Overview of USEPA Guidance on Ozone 

 The USEPA’s Attainment Guidance on 8-hour ozone modeling sets out specific criteria for the 

selection of episodes to model for attainment of the 8-hour ozone NAAQS. First, episodes should include 

days encompassing a variety of meteorological conditions, including varying wind directions, for days 

exceeding 0.084 ppm. Additionally, episodes should be selected that contain days close to (within ± 

0.010 ppm) the current design value (DVC). Episodes should also be chosen around days for which there

are extensive air quality and meteorology measurements, including measurements aloft, measurements of 

indicator species and/or precursor measurements. Finally, a sufficient number of days should be selected 

to ensure robust attainment tests at violating monitoring sites. 

 The USEPA also suggests a set of secondary criteria, in addition to the primary criteria, that may be

used in the selection of episodes. This set of criteria allows states to give preference to previously 

modeled episodes. This is a very valuable consideration, as the USEPA points out, since it can save 

modeling resources and effort. Additional considerations include selecting episodes maximizing the 

number of days and sites observing a violation, selecting episodes that include weekends, and, when 

considering regional scale modeling, selecting episodes that meet primary and secondary criteria in other 

nonattainment areas. Using these criteria laid out by the USEPA, the data available was systematically 

examined to determine the best episodes for modeling. 

 2. Episode Selection 

 With the advances in computing and storage technologies, and with the aid provided by regional 

modeling efforts, the NCDAQ and the SCDHEC intend to move toward the modeling of the peak ozone 

season for the 8-hour ozone attainment demonstration SIP. By modeling the peak season, several criteria 

are covered, including the modeling of weekends and a sufficient number of days to ensure a robust 

modeled attainment test. Modeling the peak ozone season will also accomplish the goal of encompassing

a myriad of meteorological conditions that influence tropospheric ozone formation. 

 Efforts were made to determine an appropriate period to model. The selection process started with 

an examination of the 8-hour ozone maxima for the 1997 through 2004 seasons to determine which 

season may yield the most days to be included for study. Following the second primary criteria, the 

number of days each monitoring site observed a value within 0.010 ppm of the design value was tabulated 

using the recently suggested 5-year weighted average (the average of the three 3-year design values in the 

five year period centered on the base year). 

 It was found that, overall, 2002 had the most days within 0.010 ppm of the design values, and 
21 

generally had the most exceedance days for the individual monitoring sites. When 2002 was not the 

highest year, it was generally either the second or third highest for either design value convention. Since 

2002 was the base year for the VISTAS modeling as well, choosing the 2002 ozone season for the 

episode allowed the use of the VISTAS ASIP modeling for the attainment demonstration for ozone. 

 The months of May through September 2002 were typical of the meteorology one would expect for 

an active ozone season, namely warmer and drier than average. Temperatures were 1 to 2 oF warmer than

average across the state and throughout the Mid-Atlantic States, and the precipitation values were 4-6

inches below normal for most of the Carolinas. The dry conditions were also present for much of the 

coastal Mid-Atlantic States. The warmer and drier conditions led to lower soil moisture throughout much 

of the East coast, which reduced the evaporation of moisture into the air and decreased dew point 

temperatures. With less available moisture in the atmosphere, cloud cover was decreased, which led to

more sunlight, increased photochemistry, and higher levels of ozone across the region. 

 Additionally, the episode classification further verifies that the 2002 ozone season is a representative 

year for use in attainment demonstration modeling. The 2002 ozone season encompasses six of the 

region’s typical meteorological scenarios: eastern stacked highs, frontal approaches, Canadian highs, 

modified Canadian highs, progressive continental highs and the subcategory of tropical influence. Thus, 

the 2002 season provides an excellent case to evaluate various control strategies for maintaining the 

NAAQS for ozone. 

 For these reasons, the 2002 ozone season was selected as the episode to model for the attainment 

demonstration. Further details of the episode selection process, episode classification procedures, and 

episode classifications for the 2002 ozone season can be found in the Modeling Protocol (Appendix D). 

D. Modeling Domains 

 1. Horizontal Modeling Domain 

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

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

generally stagnant conditions experienced during Metrolina ozone episodes. Two-way nesting was not 

considered due to numerical and computational uncertainty associated with the technique. 

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

develop a common grid projection and boundary. 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 II-1 shows the MM5 horizontal domain as the outer most, blue grid with the CMAQ 36-

km domain nested in the MM5 domain. 
22 

Figure II-1: The MM5 horizontal domain is the outer most, blue grid, with the CMAQ 36-km 

domain nested in the MM5 domain. 

 To achieve finer spatial resolution in the VISTAS states, a one-way nested high resolution (12 km 

grid resolution) was used. Figure II-2 shows the 12-km grid modeling domain for the VISTAS region. 

This is the modeling domain on which the attainment test results are based. A study was performed to 

determine if using a finer grid resolution provided different modeling results. Since the USEPA’s 

attainment test uses the modeling results to determine the relative reductions in ozone between the base 

year and the future year, it was determined that essentially the same attainment test results are obtained 

from either 12-km grid modeling or 4-km grid modeling. Since 4-km grid modeling takes significantly 

more time and resources to run, it was decided that the VISTAS 12-km grid modeling results for this 

attainment demonstration would be used. A copy of a journal article describing the results of the grid 

resolution study can be found in Appendix N. 
23 

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

 2. Vertical Modeling Domain 

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

The MM5 model employed a terrain following coordinate system defined by pressure, using 34 layers 

that extend from the surface to the 100 mb layer. Table II-1 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 effect of layer averaging was evaluated in conjunction with the VISTAS 

modeling effort. It was found that layer averaging had a relatively minor effect on the model performance 

metrics when both the 34 layer and a 19 layer CMAQ models were compared to ambient monitoring data. 

A discussion of the modeling sensitivity for this layer averaging can be found in Section 9.1 of the 

VISTAS Model Performance Evaluation and Model Sensitivity Tests for Three Phase I Episodes report 

dated September 7, 2004. 
24 

Table II-1: Vertical Layer Definition for MM5 and CMAQ 

MM5 Simulation CMAQ 19 Layers 

Layer Sigma Pressure 

(mb) 

Height 

(m) 

Depth 

(m) Layer Sigma Pressure (mb) 

Height 

(m) 

Depth 

(m) 

34 0.000 100 14662 1841 19 0.000 100 14662 6536 

33 0.050 145 12822 1466 0.050 145 

32 0.100 190 11356 1228 0.100 190 

31 0.150 235 10127 1062 0.150 235 

30 0.200 280 9066 939 0.200 280 

29 0.250 325 8127 843 18 0.250 325 8127 2966 

28 0.300 370 7284 767 0.300 370 

27 0.350 415 6517 704 0.350 415 

26 0.400 460 5812 652 0.400 460 

25 0.450 505 5160 607 17 0.450 505 5160 1712 

24 0.500 550 4553 569 0.500 550 

23 0.550 595 3984 536 0.550 595 

22 0.600 640 3448 506 16 0.600 640 3448 986 

21 0.650 685 2942 480 0.650 685 

20 0.700 730 2462 367 15 0.700 730 2462 633 

19 0.740 766 2095 266 0.740 766 

18 0.770 793 1828 259 14 0.770 793 1828 428 

17 0.800 820 1569 169 0.800 820 

16 0.820 838 1400 166 13 0.820 838 1400 329 

15 0.840 856 1235 163 0.840 856 

14 0.860 874 1071 160 12 0.860 874 1071 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 1000 0 0 0 1.000 1000 0 0 

E. Emission Inventory 

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

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

that emit greater than a specified tonnage per year and the data is provided at the facility level. Stationary 
25 

area sources are those sources whose emissions are relatively small but due to the large number of these 

sources, the collective emissions could be significant (e.g., dry cleaners, service stations, etc.). These 

types of emissions are estimated on the county level. Off-road mobile sources include equipment (e.g., 

lawn mowers, construction equipment, railroad locomotives, aircraft, etc.) that can move, but do not use 

the roadways. The emissions from these sources, like stationary area sources, are estimated on the county 

level. On-road mobile sources are automobiles, trucks, and motorcycles that use the roadway system. 

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

county level. Biogenic sources are the natural sources like trees, crops, grasses, and natural decay of 

plants. The emissions from these sources are estimated on a county level. 

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

The first is the actual base year inventory. This inventory is the base year emissions that correspond to 

the meteorological data. For this modeling effort, the base year is 2002. These emissions are used for 

evaluating the air quality model performance. 

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

actual base year. However, for sources that may have significant changes from year-to-year, a more 

typical emission value is used. In this modeling effort, typical emissions were developed for electric 

generating units (EGUs) and wildland fire emissions. The air quality modeling results using these 

emissions are used in calculating the relative response factors used in the attainment demonstration test. 

The future year base inventory is an inventory developed for some future year for which attainment of the 

ozone standard is needed. For this modeling project, the future year inventory will be 2009, the last

complete year for which the standard must be attained. It is the future base year inventory to which 

control strategies and sensitivities are applied to determine what controls beyond those measures already 

included in the future year base inventory, to which source classifications must be made in order to attain 

and maintain the ozone standard. 

 In the sections that follow, a synopsis of the inventories used for each source classifications are 

discussed. Detailed discussions of the emissions inventory development can be found in Appendix F, and 

emission summaries by county for the Metrolina nonattainment area and for the State are in Appendix E.

 1. Stationary Point Sources 

 Point source emissions are those emissions from larger individual sources having a fixed location. 

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

schedule. Large sources having emissions of 100 tons per year (tpy) of a criteria pollutant, 10 tpy of a 

single hazardous air pollutant (HAP), or 25 tpy total HAP are inventoried regularly. Smaller sources have 

not been inventoried and are included in the area source inventory. The point source emissions data can 

be grouped into the EGU sources and the other point sources (e.g., non-EGUs). 

 a. Electric Generating Units 

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

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

stakeholders. This data provides hourly emissions profiles that can be used in the modeling of these large 

sources of NOx and helps to provide more accurate modeling of these sources. 

 Since the NOx emissions from EGU sources are a significant part of the emissions inventory, a 

typical base year emissions inventory was developed for these sources to avoid anomalies in emissions 

due to variability in meteorology and economic and outage factors in 2002. This approach is consistent 

with the USEPA’s modeling guidance. To develop a typical year 2002 emissions inventory for EGU 
26 

sources, the average CEM heat input for 2000 through 2004 was divided by the 2002 actual heat input for 

each unit to generate a unit specific normalizing factor. This normalizing factor was then multiplied by 

the 2002 actual emissions. The heat inputs for the period 2000 through 2004 were used since the 

modeling current design values use monitoring data from this same five-year period. If a unit was 

shutdown for an entire year during the 2000 through 2004 period, the average of the years the unit was

operational was used. If a unit was shutdown temporarily in 2002, the emissions and heat inputs for 2001 

(or 2000) were used in the normalizing calculations. 

 As part of the VISTAS modeling, VISTAS and the Midwest Regional Planning Organization 

contracted with ICF Resources, L.L.C., to generate the future year emission inventory for the electric

generating sector of the contiguous United States using the Integrated Planning Model (IPM). IPM is a

dynamic linear optimization model that can be used to examine air pollution control policies for various 

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

nature of IPM enables the projection of the behavior of the power system over a specified future period. 

The optimization logic determines the least-cost means of meeting electric generation and capacity 

requirements while complying with specified constraints including air pollution regulations, transmission 

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

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

 The IPM modeling runs took into consideration the USEPA’s Clean Air Interstate Rule (CAIR) 

implementation and North Carolina’s Clean Smokestacks Act compliance plans for Duke Power and 

Progress Energy. 

 b. Other Point Sources 

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

emissions inventories. The non-EGU category will use annual emissions as reported for the Consolidated 

Emissions Reporting Rule (CERR) for the year 2002. These emissions were temporally allocated to 

month, day, and hour using source category code (SCC) based allocation factors using the SMOKE 

emissions model. 

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

data consistent with the USEPA’s analyses. This data was supplemented with state specific growth 

factors and stakeholder input on growth assumptions. 

 2. Stationary Area Sources 

 Stationary area sources include sources whose emissions are relatively small but, due to their large 

numbers, whose collective emissions could be significant (e.g., combustion of fuels for heating, structure 

fires, service stations, etc.). Emissions are estimated by multiplying an emission factor by some known 

indicator of collective activity, such as fuel usage, number of households, or population. Stationary area 

source emissions are estimated on the county level.

 The area source 2002 base year inventory for South Carolina was developed by the VISTAS/ASIP 

contractor. The VISTAS/ASIP contractor used the 2002 CERR as the basis for the area source inventory. 

The sources estimated by the contractor include emissions from animal husbandry, wildland fires, and 

particulate matter from paved and unpaved roads. For the other states within the modeling domain, the

state supplied data or the CERR data for 2002 was used. 

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

categories except for wildland fires. For this source category, development of a typical year fire 
27 

inventory provided the capability of using a comparable data set for both the base year and future years. 

Thus, fire emissions would remain the same for air quality modeling in both the base and any future 

years. The VISTAS Fire Special Interest Work Group was consulted and decided that State-level ratios 

of acres over a longer term record (three or more years) developed for each fire type relative to 2002

would be used. The 2002 acreage was then scaled up or down based on these ratios to develop a typical

year inventory. 

 For categories other than wildland fires, the VISTAS/ASIP contractor generated the future base year 

emissions inventory used in the attainment demonstration modeling. Growth factors supplied from the 

states or the USEPA’s emission projections were applied to project the controlled emissions to the 

appropriate year. In some cases, USEPA’s Economic Growth and Analysis System Version 5 growth 

factors were used if no growth factor was available from either the states or the growth factor files.

 3. Nonroad Mobile Sources 

 Nonroad mobile sources include equipment that can move but do not use the roadways, such as 

construction equipment, aircraft, railroad locomotives, lawn and garden equipment, etc. For the majority 

of the nonroad mobile sources, the emissions were estimated using the USEPA’s NONROAD2005c 

model. For the three source categories not included in the NONROAD model (aircraft engines, railroad 

locomotives, and commercial marine engines), more traditional methods of estimating the emissions were

used. The same inventory will be used for both the actual and typical base year emissions inventories for 

the nonroad mobile sources. 

 For the source categories estimated using the USEPA’s NONROAD model, the model was used to 

create a future base year inventory. The NONROAD model takes into consideration rules that are in 

effect that could impact the emissions from these source categories. For the commercial marine, railroad, 

and airport emissions, the VISTAS/ASIP contractor calculated the future base year emissions using 

detailed inventory data (both before and after controls) for 1996 and 2010 obtained from the USEPA’s 

Clean Air Interstate Rule Technical Support Document. When available, state specific growth factors 

were used. 

 4. Highway Mobile Sources 

The attainment modeling for the Charlotte-Gastonia-Rock Hill, North Carolina-South Carolina 

nonattainment area (referred to as the Metrolina area) was performed in conjunction with the regional 

haze modeling being done by the Southeast Regional Planning Organization, Visibility Improvement 

State and Tribal Association of the Southeast (VISTAS) and the fine particulate matter (PM2.5) and ozone 

modeling being done by the Association of Southeastern Integrated Planning (ASIP). VISTAS and ASIP 

are run by the ten Southeast states (Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina,

South Carolina, Tennessee, Virginia and West Virginia). 

The South Carolina transportation partners involved in attainment demonstration State 

Implementation Plan (SIP) and motor vehicle emission budget development included: USEPA Region 4, 

South Carolina Department of Transportation (SCDOT), Federal Highway Administration (FHWA), 

Federal Transit Administration (FTA), South Carolina Department of Health and Environmental Control 

(SCDHEC), and the Rock Hill-Fort Mill Area Transportation Study (RFATS) Metropolitan Planning 

Organization (MPO). The Charlotte Department of Transportation (CDOT) was consulted for speeds and 

VMT data derived from the Metrolina travel demand model (TDM). Refer to Appendix F.3 for more 

detailed information. 

 In order to accurately model the mobile source emissions in the Metrolina nonattainment area, the 
28 

newest version of the MOBILE model, MOBILE6.2, was used. Key inputs for the MOBILE model 

include information on the age of vehicles on the roads, the average speed on the roads, the mix of 

vehicles on the roads, any control technologies in place in an area to reduce emissions for motor vehicles 

(e.g., emissions inspection programs), and temperature. 

 The MOBILE model takes into consideration rules that are in effect that impact the emissions from 

this source sector. For highway mobile sources, the actual and typical year emissions were the same and 

the MOBILE model was run using input data reflective of 2002. The same model then is run for the 

future year emissions inventory using input data reflective of 2009. The 2002 and 2009 vehicle miles 

traveled (VMT) are based on data provided by the South Carolina Department of Transportation 

(SCDOT). 

 5. Biogenic Emission Sources 

 Biogenic emissions were prepared with the SMOKE-BEIS3 (Biogenic Emission Inventory System 3 

version 0.9) preprocessor. SMOKE-BEIS3 is basically the Urban Airshed Model (UAM)-BEIS3 model, 

but also includes modifications to use MM5 data, gridded land use data, and science updates. The 

emission factors that are used in SMOKE-BEIS3 are the same as the emission factors in UAM-BEIS3. 

 The basis for the gridded land use data used by BEIS3 is the county land use data in the Biogenic 

Emissions Landcover Database version 3 (BELD3) provided by the USEPA. A separate land 

classification scheme, based upon satellite (AVHRR, 1 km spatial resolution) and census information, 

aided in defining the forest, agriculture, and urban portions of each county. 
29 

SECTION III. MODEL PERFORMANCE EVALUATION 

 There are many accepted methodologies for evaluating the performance of any air quality model. 

This section, however, will focus primarily on the methods and techniques recommended by the USEPA 

for evaluating the performance of air quality models. Before the air quality model can be fully evaluated, 

a comprehensive understanding of the performance of the meteorological model being used for its inputs

is essential. This evaluation should be specifically designed to identify potential biases and errors that 

may be passed directly from the meteorological model into the air quality model. The meteorological 

modeling evaluation is fully documented in Appendix I and is briefly summarized in the next few 

paragraphs. 

 Generally speaking, the meteorological modeling performance was quite good at both the 36-km and 

12-km grid resolutions. Synoptic features were accurately predicted and the meteorological model 

showed considerable skill in replicating all important atmospheric variables (e.g., temperature, mixing 

ratio, relative humidity, wind speed and direction, cloud cover, and precipitation) necessary to drive the 

CMAQ air quality model. Performance statistics show that the meteorological modeling results fell 

within expected and acceptable ranges of error during the majority of the 2002 modeled year. 

 The meteorological modeling performance for North and South Carolina was very similar to the 

performance for the VISTAS/ASIP region for the 12-km modeling domain. As before, large-scale 

meteorological patterns were accurately predicted. The meteorological model demonstrated substantial 

skill throughout the entire 2002 modeling year, and was especially skillful during the summertime (core 

ozone) season from May through September. 

 For the North Carolina portion of the 12km modeling domain (which includes York County, SC), the 

temperature bias was near zero in May, June, and August. July had a slight negative temperature bias 

near –0.25 Kelvin (K), and September had a negative temperature bias of –0.1 K. The mixing ratio bias

was near 0 gram/kilogram (g/kg) in May through July and then fell to –0.2 g/kg in August and to -0.6 in 

September. The relative humidity bias generally hovered around ± 3% throughout the summer. Cloud 

coverage bias peaked near 10% in July and was biased less than 5% during the other summertime months. 

Wind direction was the most erratic of the measurements. The direction bias throughout North Carolina

was more pronounced than for the full 12-km domain, being more negative May through July, and more 

positive in August and September. When considering all wind measurements, the wind speed was 0.8 to 

1.0 meters per second (m/s) too strong. When omitting calm observations, the bias falls to 0.2 to 0.5 m/s. 

Additionally, the meteorological model noticeably overestimated the amount of summertime precipitation

across both Carolinas. However, it was reasonably accurate in reproducing the spatial coverage of 

measurable precipitation. 

 Overall, excess wind speeds, increased relative humidity, more daytime cloud cover, and 

precipitation overestimations will likely contribute to slight under predictions of the daily maximum peak 

ozone concentration in the CMAQ air quality model. Based on the comprehensive VISTAS & NCDAQ 

evaluation of the 2002 VISTAS MM5 results, the SCDHEC believes that the meteorological model 

performance is adequate for this modeling exercise for the York County, SC portion of the Metrolina 8-

hour Nonattainment Area, and should produce credible inputs for CMAQ air quality modeling for the 

Metrolina Area attainment demonstration. 

 Following the meteorological modeling performance evaluation, the next step in the modeling 

process was to verify the actual air quality model’s performance in terms of its ability to predict the ozone 

in the right locations and at the right levels. To do this, the actual base year model predictions were 

compared to the ambient data observed in the historical season (2002). The methodology in this type of 

verification involved a combination of statistical and graphical evaluations, with the goal of determining 
30 

if the air quality model appears to be reproducing ozone trends in the right locations for the right reasons. 

If this goal is met, then the model can reasonably be used as a predictive tool in evaluating various control 

strategies and their effects on ozone. 

 The key statistical measures used to evaluate CMAQ air quality model performance for the 

Metrolina Area attainment demonstration are as follows: 

 1. Comparison of modeled mean of ozone to the observed mean of ozone. This metric is an 

evaluation of how, on average across the modeling period, the model compares to the observed values. 

 2. Bias in the model, calculated by taking the difference between the modeled mean and the 

observed mean. 

 3. Normalized bias, calculated by taking the bias for each observation/prediction pair, and then 

dividing by the number of pairs that are used in the calculations. The USEPA recommends that 

normalized bias fall between ± 5 – 15 percent. 

 4. Gross error. For the entire modeling domain, gross error for all pairs above 60 parts per 

billion (ppb) of ozone was calculated. For the Metrolina nonattainment area, the gross error was 

calculated on the daily 8-hour ozone maximums. The USEPA’s Attainment Guidance suggests that gross 

error can be interpreted as precision of the model. This metric is typically used to compare various 

modeling applications. USEPA recommends that the gross error of all pairs >60 ppb be less than 30-35 

percent. 

 These statistics will be presented in the sections that follow for the entire 12-km VISTAS/ASIP 

modeling domain, then, specifically, for the Metrolina nonattainment area. 

 In addition to statistical methods, model performance was evaluated by reviewing spatial and time 

series plots of the modeled versus observed data. These graphical plots aided in gaining a better 

understanding of how the model performed across the entire modeling domain. 

 Only the model performance evaluation for the 12-km grid domain will be discussed in the 

subsections to follow. For the full model performance evaluation for both the 36-km and 12-km grid 

domains, please refer to Appendix J. 

A. Domain-Wide Performance 

 As a first-line screening of overall CMAQ model performance, 8-hour ozone statistical metrics were 

calculated for the 12-km domain for the VISTAS/ASIP states, North Carolina, and South Carolina 

(presented in Table III-1). The mean normalized bias was well within the recommended ± 5 - 15 percent

for the entire "core ozone" season (May through September). The individual monthly statistics for 

August and September in North and South Carolina, however, showed a mean normalized bias slightly 

outside the suggested range. This suggests an under prediction of ozone by the model toward the end of 

the summer. However, the SCDHEC does not believe this slight under prediction for August and 

September impacts the overall modeling results. The mean normalized gross error was significantly 

below the 30-35 percent range at the 60 ppb threshold for all regions across the domain. 
31 

Table III-1: 12-km Domain Model Statistics for 8-Hour Ozone 

Region/Month Modeled 

Mean (ppb) 

Observed 

Mean (ppb) 

Mean Bias 

(ppb) 

Mean 

Normalized 

Bias (%) 

Mean 

Normalized 

Gross Error 

(%) 

ASIP States combined 

May 61.26 67.69 -6.44 -8.96 12.47 

June 62.62 70.99 -8.37 -11.37 14.02 

July 62.73 70.85 -8.12 -10.90 14.74 

August 61.33 72.57 -11.24 -14.92 16.98 

September 60.81 71.98 -11.17 -14.98 17.07 

Mean (May-September) 61.75 70.82 -9.07 -12.23 15.06

North Carolina 

May 64.06 69.05 -5 -6.86 10.76 

June 62.21 71.82 -9.62 -13.03 14.47 

July 62.94 72.10 -9.16 -12.09 14.63 

August 60.60 73.92 -13.33 -17.40 18.34 

September 57.90 69.37 -11.46 -16.11 17.68 

Mean (May-September) 61.54 71.25 -9.71 -13.10 15.18

South Carolina 

May 63.87 67.71 -3.85 -5.31 9.66 

June 61.95 70.92 -8.97 -12.10 13.52 

July 60.89 70.24 -9.35 -12.73 14.75 

August 59.77 71.39 -11.62 -16.03 16.64 

September 61.18 72.62 -11.44 -15.22 16.32 

Mean (May-September) 61.53 70.58 -9.05 -12.28 14.18

 1. Spatial Plots 

 Overall, the model performed well with the spatial extent of higher ozone concentrations. There is, 

however, a slight under-prediction of the ozone in the model, most notably in the 1-hour ozone plots. As 

expected, higher ozone concentrations are seen in the urban areas. In general, the SCDHEC believes the 

model does an acceptable job capturing the spatial distribution and concentrations of ozone in the 

Metrolina area. Appendix J shows all of the domain-wide spatial plots of modeled 1-hour and 8-hour 

maximum ozone with the observations, overlaid for the days used in the relative response factor (RRF) 

calculations. Only representative days are displayed below in Figure III-1 through Figure III-7. 
32 

Figure III-1: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour 

(bottom) ozone concentrations for May 25, 2002. 
33 

 

Figure III-2: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour 

(bottom) ozone concentrations for June 3, 2002. 
34 

 

Figure III-3: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour 

(bottom) ozone concentrations for June 12, 2002. 
35 

Figure III-4: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour 

(bottom) ozone concentrations for July 3, 2002. 
36 

Figure III-5: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour 

(bottom) ozone concentrations for July 17, 2002. 
37 

Figure III-6: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour 

(bottom) ozone concentrations for August 2, 2002. 
38 

Figure III-7: Spatial plots for modeled predicted and observed peak 1-hour (top) and 8-hour 

(bottom) ozone concentrations for August 10, 2002. 
39 

 2. Scatter Plots 

 The SCDHEC and the NCDAQ are most concerned about how the model performed for North and 

South Carolina, primary to the entire 12-km VISTAS/ASIP domain. For this reason, the scatter plots 

below are for the Carolinas only, with the domain-wide scatter plots found in Appendix J. The model 

performance scatter plots of "model-predicted" versus "observed" for 1-hour and 8-hour ozone have been

compiled for each month used in the attainment test (May through September of 2002). Only the 8-hour 

ozone scatter plots for the three months (June through August), in which the majority of the modeled days 

used in the relative response factor, are shown. Although there are some outliers, the overall model 

performance was good for the 2002 ozone season, with the majority of the points falling within 

acceptable limits. 

 a. North Carolina Scatter Plots 

 Since the majority of the Metrolina Area is in North Carolina, scatter plots for the North Carolina 

domain are shown first, in Figure III-8 through Figure III-10 below. These scatter plots show 8-hour 

ozone for June, July, and August for all of the monitoring sites in North Carolina only (York, SC 

omitted). The 1-hour ozone scatter plots and the remaining 8-hour ozone scatter plots for North Carolina 

can be found in Appendix J. Overall, for the North Carolina monitoring sites the model performance is

good. Although there are some days where over-predictions and under-predictions are observed, in 

general most days fall within acceptable ranges of the 1:1 line. 

Figure III-8: 8-hour ozone scatter plot for North Carolina 12-km grid for June 2002. 
40 

Figure III-9: 8-hour ozone scatter plots for North Carolina 12-km grid for July 2002. 

Figure III-10: 8-hour ozone scatter plots for North Carolina 12-km grid for August 2002. 
41 

 

 b. South Carolina Scatter Plots 

 Figure III-11 through Figure III-13 display the scatter plots for 8-hour ozone for June, July and 

August for all of the monitoring sites in South Carolina (even though the York County, SC portion of the 

Metrolina Area is evaluated in most cases as a part of North Carolina proper). The 1-hour ozone scatter 

plots and the remaining 8-hour ozone scatter plots can be found in Appendix J. Overall, the model 

performance is good for the South Carolina monitoring sites, including York. Again, although there are 

some days where over-predictions and under-predictions are observed, in general most days fall within 

acceptable ranges of the 1:1 line. 

Figure III-11: 8-hour ozone scatter plots for South Carolina 12-km grid for June 2002. 
42 

 

Figure III-12: 8-hour ozone scatter plots for South Carolina 12-km grid for July 2002. 

Figure III-13: 8-hour ozone scatter plots for South Carolina 12-km grid for August 2002. 

 
43 

 3. Time Series Plots 

 Following are 8-hour time series plots from the 12-km domain for the North Carolina monitors for 

June through August. The time series presents the observed values [displayed as black asterisks (*)] and 

the predicted values (displayed as green lines) by month. The 1-hour and 8-hour ozone time series plots 

for the ASIP region, North Carolina, and South Carolina (including York) can be found in Appendix J. 

 The model predicts the overall diurnal pattern well; however, it tends to under-predict peak values 

and over-predict minimum values. In particular the last few days of August shows the model not 

handling the prediction of the absolute value of ozone well. Overall, the model is within acceptable 

tolerances for model performance. 

Figure III-14: Time series plot of model predicted versus mean 8-hour observed for North 

Carolina monitors for June 2002. 
44 

 

Figure III-15: Time series plot of model predicted versus mean 8-hour observed for North 

Carolina monitors for July 2002. 

Figure III-16: Times series plot of model predicted versus mean 8-hour observed for North 

Carolina monitors for August 2002 

 

 4. Domain-Wide Summary 

 Overall, the SCDHEC believes that the VISTAS/ASIP CMAQ model performance across the 
45 

domain and throughout the ozone season is good. For the most part, mean normalized bias and mean 

normalized gross error fall within the recommended limits for good model performance. The model 

seems to do a good job capturing ozone concentrations through various episode ramp-up and clean-out 

cycles. There are some instances of under- and over-predictions, but, as the scatter plots show, most of 

the time, the model does well simulating the afternoon ozone peak throughout the Carolinas. The 

SCDHEC believes that the model performance is well within the limits of acceptable performance 

established in the USEPA’s Attainment Guidance and produces results reliable enough for use in the 

Metrolina Area attainment demonstration. 

B. Area and Monitor Statistics 

 Table III-2 displays the model performance statistics comparing the modeled 8-hour ozone mean and 

the observed 8-hour ozone mean at each monitor in the Metrolina area, as well as the combined statistics 

for all of the monitors in the Metrolina area. The statistics represent the May through September ("core 

ozone season") time period. 

Table III-2: Metrolina Nonattainment Area Monitor Statistics 

Monitor Modeled Mean 

(ppb) 

Observed 

Mean (ppb) 

Mean Bias 

(ppb) 

Mean 

Normalized 

Bias (%) 

Mean 

Normalized 

Gross Error 

(%) 

Metrolina Area 65.25 73.00 -7.875 -10.152 13.289 

Crouse 69.0 73.0 -4.0 -5.330 9.868 

County Line 67.0 74.0 -7.0 -8.807 11.885 

Garinger (Plaza) 63.0 73.0 -11.0 -14.470 16.125 

Arrowood 67.0 72.0 -5.0 -5.837 12.249 

Enochville 65.0 75.0 -9.0 -11.790 13.710 

Rockwell 65.0 73.0 -9.0 -10.989 13.322 

Monroe 62.0 72.0 -10.0 -13.097 14.958 

York County, SC* 64.0 72.0 -8.0 -10.898 14.197 

*Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC

nonattainment area 

 The USEPA recommends that the combined mean normalized bias fall within ± 5-15 percent and the 

combined mean normalized gross error not exceed the 30-35 percent range. For a specific monitor, it is 

recommended that the mean normalized bias fall within ± 20 percent. The table above shows the 

VISTAS/ASIP CMAQ modeling demonstrated that the mean bias, mean normalized bias, and mean 

normalized gross error were all within recommended and accepted ranges. 

 A slight under-prediction of 8-hour ozone was also observed at this more refined level of analysis 

and was similar to what was seen at the larger state and VISTAS/ASIP region levels. Individual monthly 

statistics are not presented here due to the very limited number of modeled and observed data pairs at only 

the eight Metrolina Area ozone monitoring sites. Whole season statistics are more representative of how 

this air quality modeling will be applied in the modeled attainment test discussed in Appendix L. Across 

the whole season, the Metrolina Area as a whole, as well as the individual ozone monitoring sites, showed 

a mean normalized bias within the suggested ± 5-15 percent range. Additionally, mean normalized gross 
46 

error fell within the suggested 30-35 percent range given a 60 ppb threshold. 
47 

SECTION IV. CONTROLS APPLIED 

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

stationary point, highway mobile, and nonroad mobile sources emissions. The Federal and State control

measures were modeled for all of the future years and are discussed in the sections below. 

A. Federal Control Measures 

 1. 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 should 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 77% to 95% cleaner than those on the road today. The Tier 2 rule also reduced the sulfur 

content of gasoline to 30 ppm starting in January of 2006. Most gasoline sold in South Carolina 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. 

 2. Heavy-Duty Gasoline and Diesel Highway Vehicles Standards 

 New USEPA standards designed to reduce NOx and VOC emissions from heavy-duty gasoline and 

diesel highway vehicles commenced implementation in 2004. A second phase of standards and testing 

procedures, which begins in 2007, is reducing particulate matter from heavy-duty highway engines and 

has reduced highway diesel fuel sulfur content to 15 ppm. The total program for these new engines using 

low sulfur diesel is expected to achieve a 90% reduction in particulate matter (PM) emissions and a 95% 

reduction in NOx emissions (as compared to existing engines using higher-content sulfur diesel). 

 3. Large Nonroad Diesel Engines Rule 

 In May 2004, the USEPA promulgated new rules for large nonroad diesel engines (such as those 

used in construction, agricultural, and industrial equipment) to be phased in between 2008 and 2014. The 

nonroad diesel rules also reduce the allowable sulfur in nonroad diesel fuel by over 99%. Nonroad diesel 

fuel currently averages about 3,400 ppm sulfur. The rule limits nonroad diesel sulfur content to 500 ppm 

in 2006 and 15 ppm in 2010. The combined engine and fuel rules would reduce NOx and PM emissions 

from large nonroad diesel engines by over 90% (as compared to current nonroad engines using highercontent sulfur diesel). 

 4. Nonroad Spark-Ignition Engines and Recreational Engines Standard 

 The new standard, effective in July 2003, regulates NOx, HC, and CO for groups of previously 

unregulated nonroad engines. The new standard will apply to all new engines imported into or sold 

within the United States after these standards begin and will apply to large spark-ignition engines 

(forklifts and airport ground service equipment), recreational vehicles (off-highway motorcycles and allterrain-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 CO and PM levels in 
48 

urban areas. Tier 1 of this standard was implemented in 2004, and Tier 2 is scheduled to start in 2007. 

Like the large spark-ignition, recreational vehicles contribute to ozone formation and ambient CO and PM 

levels. For all model-year 2006 off-highway motorcycles and all-terrain-vehicles, the new exhaust 

emissions standard was phased-in at 50%; for model years 2007 and later, the standard will be phased-in 

at 100%. Recreational marine diesel engines over 37 kilowatts (used in yachts, cruisers, and other types 

of pleasure craft) contribute to ozone formation and PM levels, especially in marinas. For certain 

recreational marine diesel engine sizes, the standard began to be phased-in in 2006. 

 When all of the nonroad spark-ignition engines and recreational engines standards are fully 

implemented, overall reductions of 72% in HC, 80% in NOx, and 56% in CO emissions are expected by 

2020. These controls will help reduce ambient concentrations of ozone, CO, and fine PM. 

 5. NOx SIP Call in Surrounding States 

 In October 1998, the USEPA 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 22 states in 

the Eastern United States. A NOx emissions budget was set for each state, and the states were required to 

develop rules that would allow their respective states to meet their budgets. A NOx trading program was 

established, allowing sources to buy credits to meet their NOx budgets as opposed to actually installing 

controls. The emission budgets were to be met by the beginning of 2004. Even with the trading program, 

the amount of ozone season NOx emissions has decreased significantly in and around North and South 

Carolina. 

 6. Clean Air Interstate Rule 

 On May 12, 2005, the USEPA 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 the emissions of NOx and sulfur dioxide (SO2) and established 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: (1) any stationary, fossil-fuel-fired boiler or stationary, 

fossil-fuel-fired combustion turbine serving at any time, since the start-up of a unit’s combustion 

chamber, a generator with nameplate capacity of more than 25 MWe producing electricity for sale; and 

(2) for a unit that qualifies as a cogeneration unit during the 12-month period starting on the date that the 

unit first produces electricity and continues to qualify as a cogeneration unit, a cogeneration unit serving 

at any time a generator with nameplate capacity of more than 25 MWe and supplying in any calendar year

more than one-third of the unit’s potential electric output capacity or 219,000 MWh, whichever is greater, 

to any utility power distribution system for sale. This rule provide 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 USEPA is allowing the caps to be met through a cap and trade program if

a state so chooses to participate in the program. 

B. State Control Measures 

1. New Source Review Regulations 
49 

 On December 31, 2002, the USEPA finalized revisions governing the New Source Review (NSR) 

program. The major NSR program is a preconstruction review and permitting program applicable to new 

or modified major stationary sources of air pollutants. In areas not meeting health-based NAAWS, the 

program is referred to as the Prevention of Significant Deterioration (PSD) program. Collectively, these 

programs are commonly referred to as the major NSR program. 

 In accordance with USEPA’s final rule revisions, state agency programs must adopt and submit 

revisions to their SIPs to include the minimum program elements outline in the final rules. States may 

choose to adopt provisions that differ from the final rules; however, to be approvable under the SIP, the 

state must show that the regulations is at least as stringent as USEPA’s amendments. 

 After a lengthy stakeholder process, SCDHEC submitted revisions to the Legislature in January 2005 

to comply with the USEPA requirements. The revisions adopted by SCDHEC differ from the federal 

revisions in several key respects and have the effect of being more stringent than the federal rules. These 

revisions were approved by the General Assembly and became state-effective upon publication in the 

State Register on June 24, 2005. The final regulations promulgated amendments to regulations R. 61-

62.1, Definitions and General Requirements, and R. 61-62.5, Standard No. 7, Prevention of Significant 

Deterioration, and also promulgated a new regulation, R. 61-62.5, Standard No. 7.1, Nonattainment New 

Source Review. 

 a. South Carolina Air Pollution Control Regulation R. 61-62, Definitions and General 

Requirements, Section II - Permit Requirements

 This regulation implements a program for the minor new source review permitting program, which 

enhances the State’s prevention of significant deterioration of air quality initiatives. 

 b. South Carolina Air Pollution Control Regulation R. 61-62.5, Standard No. 7, 

Prevention of Significant Deterioration

 This regulation implements a program for the prevention of significant deterioration of air quality for 

sources located in or whose construction is proposed in an unclassifiable/attainment area of the State. 

 c. South Carolina Air Pollution Control Regulation R. 61-62.5, No. 7.1 - Nonattainment 

New Source Review 

 This regulation implements a program whereby sources located in or whose construction is proposed 

in nonattainment areas are subject to the requirements of R. 61-62.5, Standard No. 7.1 

 2. NOx Regulations 

 These regulations specify the requirements for controlling NOx and for demonstrating compliance 

with NOx limitations and the NOx SIP Call. 

 a. South Carolina Air Pollution Control Regulation R. 61-62.5, Standard No. 2 - Ambient 

Air Quality Standards

 This regulation contains the State of South Carolina ambient air quality standards, which have 

recently been amended to include the 8-hour ozone standards. 

 b. South Carolina Air Pollution Control Regulation R. 61-62.5, Standard No. 5.2 - Control 

of Oxides of Nitrogen (NOx) 
50 

 This regulation contains the NOx control standards applicable to affected stationary sources that emit 

or have the potential to emit NOx generated from fuel combustion. 

 c. South Carolina Air Pollution Control Regulation R. 61-62.96 - Nitrogen Oxides (NOx) 

Budget Trading Program

 On October 27, 1998, the USEPA finalized a Nitrogen Oxides (NOx) State Implementation Plan 

(SIP) Call Rule. The NOx SIP Call was designed to reduce the regional transport of ground-level ozone 

through reductions in NOx from electric-generating unit (EGU) rouces and from some non-EGU sources. 

The rule requires that, beginning in 2004, NOx reductions must occur during ground-level ozone season in 

states whose NOx emissions have been identified as contributing to 1-hour ozone standard nonattainment 

in “downwind” states. The rule also requires states to identify pollution-reduction measures and develop 

a plan to achieve these reductions. 

 Each state subject to the NOx SIP Call regulation has a NOx budet that the state allocates to 

applicable sources. The budget is based on cost-effective reductions in emissions that can be achieved by 

the affected sources. South Carolina’s state trading program budget, as specified in R. 61-62.96, Nitrogen 

Oxides (NOx) Budget Trading Program, is 19,678 tons. The NOx SIP Call regulation will be repealed 

after 2009 upon implementation of the Clean Air Interstate Rule. 

 d. South Carolina Air Pollution Control Regulation R. 61-62.99 - Nitrogen Oxides Budget 

Program Requirements for Stationary Sources Not in the Trading Program 

 This regulation details requirements for controlling NOx emissions from cement manufacturing. 

 e. South Carolina Air Pollution Control Regulation R. 61-62.2 - Prohibition of Open 

Burning

 The revision of R. 61-62.2, Prohibition of Open Burning, includes a ban of certain open burning 

during the ozone season for additional control of NOx emissions. 

 3. VOC Regulations: South Carolina Air Pollution Control Regulation R. 61-62.5, Standard 

No. 5 - Volatile Organic Compounds

 This regulation contains requirements for controlling VOCs. 

 4. Other State Control Measures 

 a. Clean Air Interstate Rule (CAIR) 

 On March 10, 2005, the USEPA finalized the Clean Air Interstate Rule, also referred to as CAIR. 

On May 12, 2005, CAIR was published in the Federal Register. CAIR affectes 28 states and the District 

of Columbia, whose emissions of sulfur dioxide (SO2) and/or NOx produced by EGU sources and some 

non-EGU sources contribute significantly to the nonattainment of the National Ambient Air Quality 

Standards (NAAQS) for fine particles (PM2.5) and/or 8-hour ozone in downwind states. (SO2 and NOx are 

both precursors to ground-level ozone formation, and NOx is also a precursor to PM2.5 formation.) The 

USEPA has determined that EGU sources in South Carolina are affecting the nonattainment of ozone and 

PM2.5 standards in downwind states. CAIR is a cap-and-trade program for NOx and SO2 emissions from 

affected facilities and has two phases of implementation. The caps for the phases are as follows: 
51 

 Phase I, which begins in 2009 for NOx (annual and ozone season) and 2010 for SO2 

 CAIR NOx annual cap = 32,662 tons (T) 

 CAIR EGU SO2 annual cap = 57,271 T 

 CAIR NOx ozone season cap = 15,249 T 

 Phase II, which begins in 2015 for both pollutants

 CAIR NOx annual cap = 27,219 T 

 CAIR EGU SO2 annual cap = 40,089 T 

 CAIR NOx ozone season cap = 12,707 T 

 CAIR was due for submission to the USEPA for approval on September 11, 2006. South Carolina is 

one of many states that did not meet this deadline because of a lengthy regulatory process. SCDHEC is

working closely with USEPA Region IV toward implementation of the state’s rule. SCDHEC has 

adopted the federal CAIR with modifications in areas where the state has flexibility. A Notice of Drafting 

was published in the State Register on July 22, 2005; a second Notice of Drafting was published in the

State Register on February 24, 2006. The initial approval to proceed with the proposed regulation was 

given by the SCDHEC Board on September 14, 2006. The Notice of Proposed Rule was first published 

in the State Register on October 27, 2006. A public hearing before the SCDHEC Board was held on 

January 11, 2007. On January 22, 2007, the proposed regulation was submitted to the South Carolina 

Legislature for approval. On March 8, 2007, SCDHEC submitted a request to USEPA Region 4 for 

parallel processing. South Carolina’s CAIR was state-effective upon publication in the State Register on 

June 22, 2007. A final state-version of CAIR was submitted to the USEPA on August 16, 2007. 

 b. Permitting Requirements Involving Emission Offsets - Conditions for Approval 

 If SCDHEC finds that the major stationary source or major modification would be constructed in an 

area designated in 40 CFR 81.341 as nonattainment for a pollutant for which the stationary source or 

modification is major, approval may be granted only if the following conditions are met: 

 (A) The major stationary source or major modification is required to meet an emission limitation 

which specifies the lowest achievable emission rate (LAER) for such source. 

 (B) The applicant must certify that all existing major sources owned or operated by the applicant (or

any entity controlling, controlled by, or under common control with the applicant) in the same State as the 

proposed source are in compliance with all applicable emission limitations and standards under the Clean 

Air Act (or are in compliance with an expeditious schedule which is Federally-enforceable or contained in 

a court decree). 

 (C) The owner or operator of the proposed new major stationary source or major modification will 

obtain sufficient emission reductions of the nonattainment pollutant from other sources. Emission 

reductions shall be in effect and enforceable prior to the date the new source or modification commences 

operation. The emission reductions shall be obtained in accordance with the following provisions: 

 (1) Where the permitted emissions limit allows greater emissions than the potential to emit of 

the source, emissions offset credit will be allowed only for control below this potential; 

 

 (2) For an existing fuel combustion source, credit shall be based on the allowable emissions for 

the type of fuel being burned at the time the application to construct is filed. If the existing source 

commits to switch to a cleaner fuel at some future date, emissions offset credit based on the allowable (or 

actual) emissions for the fuels involved is not acceptable, unless the permit is conditioned to require the 
52 

use of a specified alternative control measure which would achieve the same degree of emissions 

reduction should the source switch back to a dirtier fuel at some later date. 

 (3) (a) Emissions reductions achieved by shutting down an existing source or curtailing 

production or operating hours below baseline levels may be generally credited if such reductions are 

permanent, quantifiable, federally enforceable, occurred on or after the date of the most recent emissions 

inventory, and if the area has an EPA-approved attainment plan. 

 

 (b) Such reductions may be credited if the shutdown or curtailment occurred on or after the 

date the new source permit application is filed, or, if the applicant can establish that the proposed new 

source is a replacement for the shutdown or curtailed source, and the cutoff date provision of paragraph 

(d)(C)(iii)(a) of Standard 7.1 are observed. 

 (4) No emissions credit may be allowed for replacing one hydrocarbon compound with another 

of lesser reactivity, except for those compounds listed in Table 1 of EPA's "Recommended Policy on 

Control of Volatile Organic Compounds" (42 FR 35314, July 8, 1977); 

 (5) All emission reductions claimed as offset credit shall be federally enforceable; 

 (6) Location of offsetting emissions. Emission offsets shall be obtained from sources currently 

operating within the same designated nonattainment area as the new or modified stationary source. 

Emission offsets may be obtained from another nonattainment area with the Department's approval only 

if: 

 (a) The other area has an equal or higher nonattainment classification than the area in 

which the proposed source is located; and, 

 (b) Emissions from the other area contribute to a violation of the NAAQS in the 

nonattainment area in which the source is located. 

 (7) Emission offsetting ratios. Emission offsets shall be required in nonattainment areas in 

accordance with the following provisions: 

 (a) Emissions for carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), 

lead (Pb), particulate matter (PM10 and PM2.5) nonattainment areas shall be offset at a ratio greater than 

one to one. 

 (b) Emissions for ozone nonattainment areas shall be offset for volatile organic compounds 

(VOCs) and nitrogen oxides (NOx) in accordance with the following table: 

 (8) Credit for an emissions reduction can be claimed to the extent that the Department has not 

relied on it in issuing any permit under regulations approved pursuant to 40 CFR part 51 subpart I or the 

Department has not relied on it in demonstrating attainment or reasonable further progress. 
53 

 (9) Decreases in actual emissions resulting from the installation of add-on control technology or 

application of pollution prevention measures that were relied upon in designating an emissions unit as a 

Clean Unit or a project as a PCP cannot be used as offsets. 

 (10) Decreases in actual emissions occurring at a Clean Unit cannot be used as offsets, except as 

provided in paragraphs (f)(8) and (g)(10) of Regulation 61-62.5, St. No. 7.1. Similarly, decreases in actual 

emissions occurring at a PCP cannot be used as offsets, except as provided in paragraph (h)(6)(iv) of 

Regulation 61-62.5, St. No. 7.1. 

 (11) The total tonnage of increased emissions, in tons per year, resulting from a major 

modification that must be offset in accordance with section 173 of the Clean Air Act shall be determined 

by summing the difference between the allowable emissions after the modification (as defined by 

paragraph (b)(3) of Regulation 61-62.5, St. No. 7.1) and the actual emissions before the modification (as 

defined in paragraph (c)(1) of Regulation 61-62.5, St. No. 7.1) for each emissions unit. 

 (D) The emission offsets must provide a positive net air quality benefit in the affected area as 

determined by 40 CFR 51, Appendix S, Emission Offset Interpretative Ruling. 

 (E) Alternative Sites Analysis. An analysis of alternative sites, sizes, production processes, and 

environmental control techniques for such proposed source demonstrates that benefits of the proposed 

source significantly outweigh the environmental and social costs imposed as a result of its location, 

construction, or modification shall be required. 

 5. Emissions Inventory: South Carolina Regulation R. 61-62.1, Definitions and General 

Requirements, Section III - Emissions Inventory 

 This regulation requires the submittal of emissions inventory information by affected sources. 

 6. Reasonably Available Control Measures (RACM) 

 Reasonably Available Control Measures is a broadly defined term referring to technologies and other 

measures that can be used to control pollution; includes Reasonably Available Control Technology (see 

Appendix R - RACT SIP) and other measures. 

 EPA's final 8-hour ozone implementation rule in 40 CFR 51.912(d), pursuant to section 172(c)(1) of 

the CAA, requires the attainment demonstration SIP submittal to include "a SIP revision demonstrating 

that it has adopted all RACM necessary to demonstrate attainment as expeditiously as practicable and to 

meet any RFP requirements." In addition, EPA's RACM policy indicates that areas should consider all 

candidate measures that are potentially available, including any that have been suggested for the 

particular nonattainment area. Although areas should consider all available measures, areas need only to 

adopt measures if they are both economically and technologically feasible and will contribute to timely 

attainment or are necessary for RFP. Measures that might be available but would not advance attainment 

or contribute to RFP need not be considered RACM. 

 a. Reasonably Available Control Technology (RACT)

 The case-by-case RACT analysis for existing sources located in the ozone nonattainment area with 

the potential to emit greater than 100 tons per year of NOx and/or VOC is found in Appendix R - RACT 

SIP. In the York County portion of the nonattainment area, there are no VOC sources subject to CTGs. 

 b. Early Action Compacts 
54 

 On August 22, 2002, DHEC published a Notice of Drafting in the State Register announcing its 

intent to pursue Early Action Compacts (EAC) for the 8-hour ozone standard. Through the EAC process, 

local, state, and EPA officials commit to working together to develop and implement plans that will 

reduce ozone pollution so that areas are attaining the 8-hour ozone standard earlier than would be required 

by the Clean Air Act. Only areas that are attaining the 1-hour ozone standard are eligible to participate in 

the EAC process. The compact requires these areas to attain the 8-hour ozone standard by December 31,

2007, a date that is sooner than would otherwise be required through the traditional nonattainment 

designation process. 

 At the end of 2002, 45 of South Carolina's 46 counties, SCDHEC, and USEPA Region 4 had signed 

compacts to implement ozone reduction strategies earlier than federally required. Statewide stakeholder 

groups involving local and federal governments, industry, environmental groups, and other interested 

parties have worked together to plan and implement strategies for ozone pollution prevention throughout 

the state. Plans involve mobile source pollution reduction, outreach actions, and point source prevention, 

which provide flexibility and foster "homegrown" solutions. 

 The most important reasons for moving forward in this proactive manner are the public health 

benefits realized by meeting the new standard sooner than required and also the deferral of the effective 

date of a nonattainment designation. 

 As part of this process, the EAC stakeholders developed statewide regulations aimed at achieving 

additional reductions in ozone precursors. One new regulation that was developed as part of this process 

was South Carolina Air Pollution Control Regulation R. 61-62.5, Standard 5.2, Control of Oxides of 

Nitrogen (NOx). This is a broad-based regulation that applies statewide to new and existing stationary 

sources that emit NOx from fuel combustion and have not undergone a best available control technology 

(BACT) analysis for NOx. For new sources, the regulation requires the installation of control technology 

that is based on BACT standards found in the RACT/BACT/LAER clearinghouse. For existing sources, 

the regulation only applies when an applicable unit replaces their burner. At this point, they will be 

required to replace their burner with a low NOx burner or equivalent technology capable of achieving a 30 

percent reduction from uncontrolled levels. 

 Also, as part of the EAC process, South Carolina Air Pollution Control Regulation R. 61-62.2, 

Prohibition of Open Burning, was revised by deleting the exception for the burning of household trash, 

revising the exception for the burning of construction waste, and revising the exception for fires set for 

the purpose of firefighter training. The burning of household trash presents health and environmental 

concerns for many communities. The smoke generated from these activities is a nuisance to some and a 

health threat to others with asthma or other respiratory problems. With respect to the exception for the 

burning of construction waste, the regulation was revised to allow only residential construction waste to 

be burned outside the ozone season, and this will only be allowed if it meets the provisions of the 

regulation. Finally, the exception for the purpose of firefighter training was revised to ensure that

minimum health, environmental, and safety concerns are addressed. 

 These regulations were approved by the SCDHEC Board in January 2004, and, in accordance with 

South Carolina law, they were subsequently submitted to the Legislature for approval. The South 

Carolina General Assembly approved the regulations, and the rules were published and became effective 

upon publication in the State Register on June 25, 2004. In accordance with the EAC process, SCDHEC 

incorporated the statewide regulations and the local early action plans into the agency's Early Action SIP 

revision and submitted it to the USEPA in December 2004, for review and approval. 

 c. Take a Break from the Exhaust 
55 

 Take a break from the exhaust (TABFTE) is an alternative commute initiative that uses a competitive 

model in which points are assigned/ awarded for each action that is done to minimize air pollution. A

computer program is used by participants to report their actions and to record their daily points. The webbased program is available to state and local government, industry, and the public. The program tracks 

and calculates vehicle miles, determines emission reductions, is free and requires no additional 

equipment. 

 TABFTE was started by the SCDHEC Bureau of Air Quality in 2001 and is still being used by the 

bureau staff. In 2003, it was awarded the Governor's Pollution Prevention Award and became Internet 

accessible. The program was expanded to other state agencies in 2004. The primary benefits of TABFTE

are reduced emissions from mobile sources and increased awareness of the impact of mobile sources on 

air quality; it also encourages participants to take voluntary actions to help improve air quality. 

 d. Overall RACM Conclusions 

 A number of emissions controls programs have been implemented in South Carolina since the Clean 

Air Act Amendments of 1990, and substantial further emissions reductions will occur in the State as well 

as the Metrolina area in 2007. SCDHEC intends to continue to investigate and, where appropriate, adopt 

additional measures that would reduce emissions of ozone precursors even further. Such measures may 

help the State in the future as it moves towards attainment of the eight-hour ozone NAAQS. The source

categories emitting the vast preponderance of ozone precursor emissions in the State are already subject 

to control requirements. South Carolina has adopted all of the above RACM and have since determined 

that there are no additional technologically and economically feasible control measures that would result 

in South Carolina attaining the one-hour ozone NAAQS earlier than 2007. 
56 

SECTION V. ATTAINMENT DEMONSTRATION 

A. Attainment Test Introduction 

 The modeled attainment test is the practice of using air quality modeling results for baseline and 

future years to determine if an area is expected to attain the NAAQS. For the 8-hour ozone NAAQS, the

baseline and future model estimates are used in a "relative" rather than an "absolute" sense. Specifically, 

the ratio of the air quality model’s future to current predictions is calculated at each ozone monitoring 

site. These monitoring site-specific ratios are called relative response factors (RRFs). Future ozone 

design values (DVFs) are then estimated at each monitor by multiplying the monitor-specific baseline 

ozone design value (DVB) by the modeled RRF for each monitor. If all of the predicted monitor-specific 

DVFs in a given area are less than or equal to 0.084 ppm, the attainment test is passed and the area is said 

to demonstrate attainment. Equation V-1 presents the modeled attainment test, applied at monitoring site 

"x" as described in Section 4.0 of the USEPA’s Attainment Guidance. 

 Equation V-1 (Future Design Values): 

 (DVF) = (RRF) x (DVB) 

Where: 

 (DVB) = the baseline design value monitored at site "x" in ppm 

 = the average of the three design value periods which include the baseline 

inventory year (i.e., the average of the 2000-2002, 2001-2003, and 2002-2004 design value periods for the 

2002 baseline inventory year). 

 (RRF) = the ratio of the future 8-hr daily maximum concentration predicted "nearby" a 

monitor (averaged over each day of the episode) to the current 8-hr daily maximum concentration 

predicted "nearby" the monitor (averaged over each day of the episode). 

 (DVF) = the estimated future design value in ppm. 

 It is important to consider an array of cells "nearby" a monitor rather than focusing on the individual 

cell containing the monitor. This allows for variations in the model performance where the peak ozone

concentration occurs in a nearby grid cell rather than in the grid cell that contains the monitor. 

 The RRF is calculated by taking the ratio of the mean future year modeling 8-hour ozone daily 

maximum (averaged over all of the episode days) to the mean current year modeling 8-hour ozone daily 

maximum "near" the monitor (averaged over all of the episode days) (Equation V-2). 

 Equation V-2 (Relative Response Factors): 

 RRF = (mean future yr. 8-hr daily max "near" monitor "x")

 (mean current yr. 8-hr daily max "near" monitor "x") 

 The DVB, for purposes of the modeled attainment test, is defined in the USEPA’s Attainment 

Guidance as the average of the three design value periods that straddle the baseline inventory year (i.e., 
57 

the average of the 2000-2002, 2001-2003, and 2002-2004 design value periods for a 2002 baseline 

inventory year). 

B. Attainment Test Results 

 As stated above, the attainment test is not based on absolute modeling results but, rather, relative 

reductions of ozone and is only applied at the monitors. However, reviewing the modeling results of how 

the predicted ozone decreases in the future years and how widespread the reductions are plays an import 

role for the State in determining if additional controls should be considered. The modeling results for 

each day used in the RRF calculations are available in Appendix K. Additionally, discussions about how 

this modeling demonstration meets the screening test for areas away from the monitoring sites and 

additional matrices performed to support the attainment test results are in Appendix L. 

 The USEPA states that future design values (DVFs) that fall below 0.082 ppm demonstrate 

attainment whereby little weight of evidence is needed. For monitors with DVFs between 0.082 ppm and 

0.087 ppm, weight of evidence must be submitted that supports a demonstration of attainment. DVFs 

greater than 0.085 ppm fail the attainment test. 

 Table V-1 lists the attainment test results for the Metrolina nonattainment area. The first column is 

the monitoring site, followed by the base year design value discussed in Section V.A. The next series of 

columns are the calculated RRF and the resulting DVF for the 2009 attainment year. Monitors with 

DVFs that fall in the additional weight of evidence requirement appear in bold. 

Table V-1: Attainment Test Results

2009 

Monitoring Site County 

DVB (ppm) 

5-year weighted 

2000-2004 RRF DVF 

(ppm) 

Arrowood Mecklenburg 0.0847 0.892 0.075 

County Line Mecklenburg 0.0973 0.874 0.085 

Crouse Lincoln 0.0907 0.868 0.078 

Enochville Rowan 0.0970 0.870 0.084 

Garinger (Plaza) Mecklenburg 0.0953 0.883 0.084 

Monroe Union 0.0870 0.884 0.076 

Rockwell Rowan 0.0973 0.862 0.083 

York York, SC* 0.0830 0.861 0.071 

*Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC

nonattainment area. 

C. Supporting Weight of Evidence 

 As part of the weight of evidence determination, the following analyses will be evaluated: 

alternative DVF calculations, additional metrics of air quality modeling results, air quality modeling

results from other studies, positive trends in observed air quality and additional emissions reductions, and 

local measures that were not modeled. The weight of evidence determination is a supplement to the 

modeled attainment test and further supports that the area will attain the NAAQS for 8-hour ozone by 

June 15, 2010. 

 The SCDHEC believes that the weight of evidence provided in the sections below is strong evidence 
58 

that the Metrolina nonattainment area will attain the 8-hour ozone NAAQS by 2009. 

 1. Alternative DVF Calculation 

 The USEPA recommends calculating the DVB by averaging the three design value periods that 

straddle the baseline inventory year. This methodology results in a center weighting of annual 4th highest 

ozone concentrations around the baseline inventory year because the three design value periods averaged 

contain overlapping data. A weighted DVB can be significantly affected by an abnormally hot/dry or 

cool/wet year, if the year happens to be the center weighted year. 

 To minimize potential impacts of any abnormal meteorological conditions while still considering 

ozone conditions across a 5-year span, the NCDAQ and the SCDHEC prefer an alternative DVB 

calculation that does not weigh any of the years more than another but is the straight average of annual 

4th highest ozone concentrations for the 5-year span centered on the baseline inventory year. 

 This preferred DVB calculation is applied to the remainder of the modeled attainment test equations 

and the resulting DVFs are shown in Table V-2 at each monitoring site in the Metrolina region. 

Table V-2: 5-Year Average Alternative Attainment Test Results for 2009 

Monitoring Site County 

DVB 

5-Year Straight 

Average 

2000-2004 

(ppm) 

RRF DVF 

(ppm) 

Arrowood Mecklenburg 0.0834 0.892 0.074 

County Line Mecklenburg 0.0956 0.874 0.083 

Crouse Lincoln 0.0892 0.868 0.077 

Enochville Rowan 0.0944 0.870 0.082 

Garinger (Plaza) Mecklenburg 0.0938 0.883 0.082 

Monroe Union 0.0846 0.884 0.074 

Rockwell Rowan 0.0946 0.862 0.081 

York York, SC* 0.0798 0.861 0.068 

*Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC

nonattainment area. 

 The alternative DVFs are slightly lower at each monitoring site compared to the attainment test 

DVFs. These differences were expected as 2002 was an abnormally hot and dry year throughout the 

Southeast, resulting in ozone concentrations that were higher than normal and that were much higher than 

in the surrounding years of 2000, 2001, 2003, and 2004. Thus, the USEPA recommended DVB 

calculation weighted these abnormally-high air quality conditions several times more than in the straight 

average alternative DVB calculations. The NCDAQ and the SCDHEC firmly believe that the straight 

five-year average approach to the DVB calculation is more appropriate and minimizes dramatic 

fluctuations in meteorological and air quality conditions from year to year. 

 While none of the monitoring sites in the Metrolina region had DVF values at or above 0.085 ppm 
59 

using the straight average alternative DVB calculation, there are still three monitors that have DVFs that 

fall between 0.082 and 0.087 ppm. This continues to indicate that some additional weight of evidence 

should be included to demonstrate attainment. 

 2. Additional Air Quality Modeling Metrics 

 A series of five additional air quality modeling outputs or metrics is recommended to provide 

assurance the modeled attainment demonstration indicates attainment. These metrics look at the relative 

change between the baseline and future years modeling and help to demonstrate how widespread the 

improvement in air quality is expected in the future. These metrics include: 

 • The relative change in surface grid-hours greater than 0.084ppm. This is the number of grid cells

in a Metrolina region with predicted hourly 8-hour ozone concentrations greater than 0.084 ppm. The 

relative change is the percent reduction from the baseline year to the future year. 

 • The relative change in the number of grid cells with predicted 8-hour daily maximums greater than 

0.084 ppm. This metric uses the modeled daily maximum 8-hour ozone concentrations greater than 0.084 

ppm. The relative change is the percent reduction from the baseline year to the future year. 

 • The relative change in the sum of hourly predictions greater than 0.084 ppm. This metric is the 

sum of all grid cells with predicted hourly 8-hour ozone concentrations greater than 0.084 ppm. The 

relative change is the percent reduction from the baseline year to the future year. 

 • The relative change in the sum of the predicted 8-hour daily maximums greater than 0.084 ppm. 

This metric uses the modeled daily maximum 8-hour ozone concentrations greater than 0.084 ppm. The 

relative change is the percent reduction from the baseline year to the future year. 

 • The change in the Air Quality Index (AQI) counts. The AQI counts metric is a count of the 

number of grid cells with predicted maximum 8-hour ozone concentrations sorted within each of the color 

codes as defined by the USEPA’s AQI. 

 The USEPA recommended that these metrics should indicate a reduction in ozone of 80% or more in 

order to provide weight of evidence that an area would attain the ozone NAAQS. The additional air 

quality modeling metric analyses demonstrated reductions of greater than 85% for all metrics in the 2009 

attainment year for modeled days above the NAAQS in the Metrolina nonattainment area. A full 

discussion of the metrics and the results can be found in Appendix L. 

 3. Air Quality Modeling Results From Other Studies 

 Another recommended weight of evidence analysis is to review other air quality modeling results 

that included the Metrolina nonattainment area to determine how other modeling results compare to the 

attainment demonstration. There are two air quality modeling studies for which results are available for 

the Metrolina area. 

 The first is the Early Action Compact (EAC) modeling that the NCDAQ and the SCDHEC 

performed for the EAC areas within North and South Carolina. Since the modeling domain for this 

analysis covered the majority of North and South Carolina, including the Metrolina nonattainment area,

the modeling results can be easily compared to the attainment demonstration. Although there are some 

differences between the two modeling exercises, the modeling results for 2012 show all of the monitors

well below the 8-hour ozone NAAQS, with the highest monitor having a DVF of 0.081 ppm. 
60 

Table V-3: Metrolina DVFs Based on EAC Modeling 

2012 

Monitoring Site County DVB 

(ppm) RRF DVF 

(ppm) 

Arrowood Mecklenburg 0.092 0.848 0.078 

County Line Mecklenburg 0.101 0.802 0.081 

Crouse Lincoln 0.092 0.826 0.076 

Enochville Rowan 0.099 0.818 0.081 

Garinger (Plaza) Mecklenburg 0.098 0.816 0.080 

Monroe Union 0.088 0.795 0.070 

Rockwell Rowan 0.100 0.800 0.080 

York York, SC* 0.086 0.844 0.073 

*Represents only that portion of the county that is located in the 

Charlotte-Gastonia-Rock Hill, NC-SC nonattainment area. 

 Another air quality modeling exercise that contained results for the Metrolina nonattainment area is 

the USEPA’s modeling for the Clean Air Interstate Rule (CAIR). The Technical Support Document for 

the final , dated March 2005, provided modeling results with and without the implementation for the . 

These modeling results are listed in the table below. 

Table V-4: Metrolina DVFs Based on USEPA’s Modeling 

DVF (ppb) County DVB 

(ppb) 2010 Base 2010 

Lincoln 92.3 76.1 74.5 

Mecklenburg 100.3 82.5 81.4 

Rowan 99.7 81.3 80.1 

Union 87.7 71.9 71.1 

York, SC* 83.3 70.0 68.5 

*Represents only that portion of the county that is located in the 

Charlotte-Gastonia-Rock Hill, NC-SC nonattainment area. 

 The USEPA’s modeling results predicts that the Metrolina nonattainment area should be below the 

8-hour ozone standard by 2010. Although this is one year later than the attainment year for the Metrolina 

area, the USEPA’s 2010 DVFs are 2 to 4 ppb lower than the DVFs predicted in the attainment 

demonstration and support weight of evidence that the Metrolina area will attain the 8-hour ozone 

standard by its attainment year of 2009. 

 4. Positive Trends in Observed Air Quality and Additional Emissions Reductions 

 Since the 8-hour ozone designation for the Metrolina area, the 8-hour ozone design values have 

improved significantly. The 2001-2003 design value period had values as high as 0.100 ppm, and six out 

of the seven North Carolina monitors in the area were violating the NAAQS. Each year since, the design 

values have decreased and/or the number of violating monitors in the region has decreased. For the latest 

design value period, 2004-2006, the highest violating monitor has a value of 88 ppb, with only three 

monitors exceeding the NAAQS (See Table V-5). 
61 

Table V-5: Design Values (ppm) for the North Carolina Monitors in the Metrolina Area

Monitoring Site County 2001-2003 2002-2004 2003-2005 2004-2006 

Arrowood Mecklenburg 0.084 0.081 0.078 0.080 

County Line Mecklenburg 0.098 0.092 0.087 0.088 

Crouse Lincoln 0.092 0.086 0.081 0.079 

Enochville Rowan 0.099 0.091 0.085 0.085 

Garinger (Plaza) Mecklenburg 0.096 0.091 0.086 0.088 

Monroe Union 0.088 0.085 0.079 0.078 

Rockwell Rowan 0.100 0.094 0.088 0.083 

York York, SC* 0.084 0.081 0.075 0.076 

*Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC

nonattainment area. 

 The current ozone design values are very close to the predicted attainment year design values, 

however, there are still significant nitrogen oxides (NOx) emission reductions that are expected between 

now and the attainment year. Although most of these expected NOx emission reductions have been 

included in the attainment demonstration modeling, it does not appear the model is responsive enough to 

expected emission reductions. 

 As mentioned in earlier in the narrative, the Metrolina area is a NOx-limited area, and the major 

sources of NOx emissions in the region comes from mobile sources and electric generating facilities. 

Reduction of emissions from these two source sectors can significantly influence the ozone formation in 

this region. The NCDAQ and the SCDHEC have estimated that there will be approximately 7.6 tons per 

day of NOx emissions reduced each year from the mobile sector. These reductions are the result of 

Federal motor vehicle and equipment standards for both highway vehicles and off-road equipment. 

 Another source of NOx emission reductions that are expected to occur between now and the 

attainment year are from the electric generating facilities located in and near the Metrolina nonattainment 

area. Several of the Duke Energy units are still expected to have controls installed over the next two 

years. Figure V-1 displays the location and size of the Duke Energy facilities located in the vicinity of the 

Metrolina nonattainment area. Table 5.3.4-2 lists the units that are in and around the Metrolina area and 

shows the year the controls are expected to come on line and the estimated amount of NOx emissions 
62 

reductions for the ozone season. 

Figure V-1: Location and size of the Duke Energy facilities located in the vicinity of the 

Metrolina nonattainment area 

Table V-6: Utility NOx Emission Reductions since 2006 Ozone Season 

Facility County Technology Operational Date Ozone Season Reductions 

(tons/season) 

Allen Steam Station 

 Unit 2 

 Unit 3 

Gaston SNCR 

SNCR 

Spring 2007 

Fall 2007 

~300 

Buck Steam Station 

 Units 3 & 4 

 Units 5 & 6 

Rowan Low NOx Burners 

SNCR 

Spring 2007 

Fall 2006 

~350 

Riverbend 

 Unit 4 

 Unit 5 

 Unit 6 

 Unit 7 

Gaston 

SNCR 

SNCR & Burners 

SNCR & Burners 

SNCR 

Spring 2007 

Spring 2007 

Fall 2006 

Fall 2006 

~325 
63 

Marshall Steam Station 

 Unit 2 

 Unit 3 

 Unit 4 

Catawba SNCR 

SCR 

SNCR 

Spring 2007 

Fall 2008 

Fall 2006 

~2,300 

Total expected reduction = 3,275 tons/ozone season 

 SNCR = Selective Non-Catalytic Reduction 

 SCR = Selective Catalytic Reduction 

 The combination of the mobile source and utility NOx emission reductions that are expected in the 

Metrolina area after the end of the 2006 ozone season and before the beginning of the attainment year 

2009 is significant. Since the 2004-2006 design values are just above the standard, the additional NOx

emission reductions in the area should ensure that the Metrolina area will attain the NAAQS by the 

prescribed attainment year. 

 5. Local Measures Not Modeled 

 A significant source of NOx emission reductions that has not been included in the modeling is the 

addition of a SCR unit at Marshall Unit 3. This SCR unit should be installed the fall of 2008 and will be 

operational before the beginning of 2009. 

 In addition to the Marshall NOx emission reductions, the Metrolina area has a number of groups that 

are working towards decreasing emissions. These are voluntary measures that, although not accounting 

for large emission reductions, are reductions nonetheless. A few of the known measures that are under

way in the Metrolina area include: I-77 High Occupancy Vehicle (HOV) lanes in Mecklenburg County, 

truckstop electrification in Rowan County, express bus routes, pedestrian walkway and bikeway projects, 

idle reduction policies, and biodiesel use and diesel retrofit projects. Discussions of these measures can 

be found in Appendix L. 

D. Unmonitored Area Attainment Analysis 

 The modeled attainment test does not address future air quality at locations where there is not an 

ozone monitor nearby. To guard against the possibility that air quality levels could exceed the standard in 

areas with limited monitoring, Section 3.4 of the Attainment Guidance suggest that additional review is 

“necessary, particularly in nonattainment areas where the ozone or PM2.5 monitoring network just meets 

or minimally exceeds the size of the network required to report data to Air Quality System (AQS).” This 

review is intended to ensure that a control strategy leads to reductions in ozone at other locations that 

could have baseline (and future) design values exceeding the NAAQS were a monitor deployed there. 

The test is called an “unmonitored area analysis”. The purpose of the analysis is to use a combination of 

model output and ambient data to identify areas that might exceed the NAAQS if monitors were located 

there. 

 NCDAQ and SCDHEC believe that the density of their monitoring network relieves the necessity of 

applying this additional analysis. With an average of one monitor per 3,077 km2, this is one of the 

densest statewide ozone monitoring networks in the nation. Additionally, the monitor density across the 

Metrolina nonattainment area is more than twice that of the statewide monitor density (on average a 

monitor every 1,278 km2

). 

 The Modeled Attainment Test Software (MATS) tool has been developed by the USEPA to spatially 

interpolate data, adjust the spatial fields based on model output gradients, and multiply the fields by 

model calculated RRFs for analysis of unmonitored areas. However, this tool has just recently been 

released with documentation (June 2007), and neither the NCDAQ nor the SCDHEC has had sufficient 
64 

time to review documentation and fully understand the output from this tool, nor has the tool been peer 

reviewed. The NCDAQ and the SCDHEC ares committed to evaluate the MATS tool output and any 

peer review comments that are submitted to determine if additional monitoring or further NOx controls 

may be needed to ensure attainment of the NAAQS throughout the Metrolina region. 

Refer to Appendix L for a complete discussion of this topic. 

E. Data Access 

 The modeling input and output files are very large and it would not be reasonable to submit all of 

these files with the SIP attainment demonstration. These include all files used to process the emissions, 

meteorology, and air quality models and any other files used to develop the modeling. To request access 

to these files, please contact the Bureau of Air Quality at 803-898-4123. 
65 

SECTION VI. MODERATE NONATTAINMENT AREA REQUIREMENTS 

A. Clean Air Act (CAA), as amended (42 U.S.C. 7401, et seq.) 

 Sections 172(c), 182(a), and 182(b) of the CAA prescribe the requirements for ozone nonattainment 

areas. Any State with a designated nonattainment area must promulgate amendments to their SIP to 

address the requirements mandated by Section 172(c) of the CAA. As a Subpart 2, moderate ozone 

nonattainment area, the Metrolina area must meet the additional requirements prescribed by Section 182

of the CAA. Each State in which all or part of a Moderate Nonattainment Area is located shall make the 

submissions prescribed under Section 182(a) relating to Marginal Nonattainment Areas and shall also 

submit the revisions to the applicable implementation plan described under Section 182(b) with respect to 

Moderate Nonattainment Areas. The requirements are listed below, and the SCDHEC's activities in 

promulgating amendments to the South Carolina Air Quality Implementation Plan (SIP) to comply with 

these mandates are discussed in more detail in the various parts of this section. 

 1. CAA Section 172(c) - Nonattainment Plan Provisions 

 Any State with a designated nonattainment area must promulgate amendments to its SIP to address 

the requirements mandated by Section 172(c) of the CAA. The SIP provisions (including plan items) 

required to be submitted under this part shall comply with each of the following: 

 (1) RACM - Implementation of all reasonably available control measures (RACM) as 

expeditiously as practicable [including such reductions in emissions from existing sources in the area as 

may be obtained through the adoption, at a minimum, of reasonably available control technology 

(RACT)] and provide for attainment of the national primary ambient air quality standards. 

 (2) RFP - Require reasonable further progress (RFP). 

 (3) Inventory - Include a comprehensive, accurate, current inventory of actual emissions from 

all sources of the relevant pollutant or pollutants in the nonattainment area, including such periodic

revisions as the USEPA may determine necessary to assure that the requirements are met. 

 

 (4) New Source Review (NSR): Identification and quantification - Identify and quantify the 

emissions, if any, of any such pollutant or pollutants that will be allowed from the construction and 

operation of major new or modified stationary sources in the nonattainment area. Demonstrate to the 

satisfaction of the USEPA that the emissions quantified for this purpose will be consistent with the 

achievement of reasonable further progress and will not interfere with attainment of the applicable 

NAAQS by the applicable attainment date. 

 (5) Permits for new and modified major stationary sources - Require permits for the 

construction and operation of new or modified major stationary sources anywhere in the nonattainment 

area. 

 (6) Other measures - Include enforceable emission limitations, and other such control 

measures, means, techniques (including economic incentives such as fees, marketable permits, and 

auctions of emission rights), and schedules and timetables for compliance determined necessary or 

appropriate to provide for attainment of such standard in the nonattainment area by the applicable 

attainment date. 

 (7) Compliance with Section 110(a)(2) of the CAA. 
66 

 (8) Equivalent techniques - Upon application by any State, the USEPA may allow the use of 

equivalent modeling, emission inventory, and planning procedures unless the USEPA determines that the 

proposed techniques are, in the aggregate, less effective than the methods specified by the USEPA. 

 (9) Contingency measures - Provide for the implementation of specific measures to be 

undertaken if the area fails to make reasonable further progress or to attain the NAAQS by the applicable 

attainment date. Such measures shall be included in the plan revision as contingency measures to take 

effect in any such case without further action by the State or the USEPA. 

 2. CAA Section 182 - Plan Submissions and Requirements 

 Each State in which all or part of a Moderate Nonattainment Area is located shall make the 

submissions prescribed under Section 182(a) relating to Marginal Nonattainment Areas and shall also 

submit the revisions to the SIP described under Section 182(b) with respect to Moderate Nonattainment 

Areas. 

 a. CAA Section 182(a) - Marginal Areas 

Each State in which a nonattainment area is located shall submit to the USEPA the SIP revisions 

(including the plan items) described under Section 182(a) of the CAA. 

 

 (1) Inventory - Submit a comprehensive, accurate, current inventory of actual emissions 

from all sources. 

 (2) Corrections to the SIP - Submit a revision to the SIP that meets the following 

requirements: 

 (A) Reasonably available control technology (RACT) corrections - Submit, within 6 

months of the date of classification, a revision that includes such provisions to correct requirements in (or 

add requirements to) the SIP concerning RACT. 

 (B) Motor vehicle inspection and maintenance (I/M) program. 

 (C) Permit programs - Provisions to require permits for the construction and 

operation of each new or modified major stationary source (with respect to ozone) to be located in the

area. 

 (3) Periodic inventory 

 (A) General requirement - Submit a revised inventory every three years until the area 

is redesignated to attainment. 

 (B) Emissions statements - Require that the owner or operator of each stationary 

source of oxides of nitrogen or volatile organic compounds provide the State with an annual statement 

showing the actual emissions of oxides of nitrogen and volatile organic compounds from that source. The 

statement shall contain a certification that the information contained in the statement is accurate to the 

best knowledge of the individual certifying the statement. The State may waive the annual emissions 

inventory submittal requirement for any class or category of stationary sources that emit less than 25 tons 

per year of VOCs or NOx. 

 b. CAA Section 182(b) - Moderate Areas 
67 

 As a Subpart 2, moderate ozone nonattainment area, the Metrolina area must also meet the additional 

requirements prescribed by Section 182(b) of the CAA. 

 (1) RFP - Provide for volatile organic compound emission reductions, within 6 years, of at 

least 15 percent from baseline emissions, accounting for any growth in emissions. Provide for such 

specific annual reductions in emissions of VOCs and NOx as necessary to attain the NAAQS for ozone. 

 (2) RACT - Require the implementation of reasonably available control technology with 

respect to all VOC sources in the area covered by any CTG issued by the USEPA and all other major 

stationary sources of VOCs that are located in the area. There are no VOC sources subject to CTGs 

located in York County portion of the nonattainment area. 

 (3) Gasoline vapor recovery - Section 182(b)(3) of the CAA requires moderate and above 

ozone nonattainment areas to implement Stage II vapor recovery programs. However, Section 202(a)(6) 

of the CAA states that the Section 182(b)(3) Stage II requirement shall not apply in moderate areas after 

onboard refueling vapor recovery (ORVR) rules are promulgated. The USEPA promulgated the ORVR 

regulations on April 16, 1994. Because of the USEPA’s promulgation of ORVR and York County not 

already having Stage II vapor recovery in place, that portion of York County that is located in the 

Charlotte-Gastonia-Rock Hill, NC-SC nonattainment area is not required to implement Stage II vapor 

recovery requirements. 

 (4) Motor vehicle inspection and maintenance - Provide for a vehicle inspection and 

maintenance program. 

 (5) General offset requirement - The ratio of total emission reductions of VOCs to total 

increased emissions of such air pollutant shall be at least 1.15 to 1. 

 c. CAA Section 182(f) - NOx Requirements 

 (1) The plan provisions required under this Subpart for major stationary sources of volatile 

organic compounds shall also apply to major stationary sources [as defined in Section 302 and 

Subsections (c), (d), and (e) of this Section] of oxides of nitrogen. 

B. South Carolina Air Quality Implementation Plan (SIP) Provisions 

 1. RACM/RACT Requirements 

 Section 172(c)(1) of the CAA requires an amendment to the SIP to provide for the implementation of 

all reasonably available control measures (RACM) to demonstrate attainment as expeditiously as 

practicable [including such reductions in emissions from existing sources in the area as may be obtained 

through the adoption, at a minimum, of reasonably available control technology (RACT)] and provide for

attainment of the national primary ambient air quality standards. Sensitivity analysis has demonstrated 

that VOC reductions have very little impact on ozone in South Carolina. The SCDHEC has determined 

that the entire state is NOx-limited and that the control program for reducing ozone should be focused on 

NOx emission reductions. The overwhelming abundance of biogenic VOC emissions makes the majority 

of North and South Carolina, including the Metrolina area, a NOx -limited environment for the formation 

of ozone. 

 a. RACM 
68 

 In August of 2006, stakeholders involved in supporting South Carolina's "Cleaner Air Sooner" effort 

convened in Columbia to share and exchange ideas and information about their local strategies. It was

appropriate that this "first of its kind" meeting was held in the state, since South Carolina, with forty-five 

of its forty-six counties participating, leads the nation in the number of local areas that are committed to 

implementing emission reduction measures. The EAC Summit was coordinated by SCDHEC staff with 

input from stakeholders for the purpose of offering the local leadership a stage to highlight their activities. 

This sharing of ideas and local strategies served as an opportunity to connect EAC contacts and develop a 

network of peers for sharing information on positive strategies. To re-emphasize the importance of this 

work in South Carolina, USEPA Assistant Administrator Bill Wehrum addressed the attendees as the 

keynote speaker. Items on the agenda for the EAC Summit included: Energy Conservation; Diesel 

Retrofits; Land Use Planning; Alternative Fuels; Commuting Options; Innovative Education and 

Outreach; Health Impacts/Lifestyle; Finding the Funding; and Commuting Options (to Multi-Modal 

Transportation). 

 SEQL (Sustainable Environment for Quality of Life) is a special USEPA Region 4 bi-state project 

involving the Charlotte-Mecklenburg area of North Carolina and the Catawba region of South Carolina, 

which includes Chester, Union, Lancaster, and York counties. The Centralina and Catawba Regional 

Councils of Government (COGs) have been instrumental in involving other local government 

organizations, state agencies and the public in SEQL. Due to these areas experiencing strong and 

sustained population growth, they face many challenges in maintaining good air quality and in contending 

with nonattainment for the eight-hour ozone NAAQS in some areas. 

 As part of the SCDHEC's involvement in SEQL, the Bureau of Air Quality partnered with the 

Catawba Regional COG to develop model ordinances, examples of best management practices, and 

program guidance documents to assist local governments in implementing programs such as tree planting,

bike trails, and parking with green spaces to address environmental concerns. The Model Ordinances are 

posted on the SCDHEC's Web site as well as a link to the SEQL Web site. The Centralina and Catawba 

Regional COGs continue to work together to address air quality and other environmental concerns and are 

now developing a regional vision that will represent what residents, local jurisdictions, and private sector 

leaders want the region to be. 

 The following emission reduction measures impacting mobile sources are planned or have been 

implemented in York County: 

 • York County gas can exchange in 2004. Catawba Regional Council of Government 

(COG), Rock Hill Clean and Green, York County Government, City of Rock Hill, Palmetto State Clean 

Fuels Coalition, and Sustainable Environment for Quality of Life (SEQL) collaborated with the SCDHEC 

on the event. A total of 110 old cans were turned in. 

 • South Carolina has two current school bus retrofit projects, a Santee Cooper Supplemental 

Environmental Project (SEP) project that involves installation of diesel particulate filters, and a Clean 

School Bus USA grant involving installations of diesel oxidation catalysts, crankcase ventilation systems, 

and anti-idling hardware. The nonattainment portion of York County is a priority area for both projects. 

 • Breathe Better anti-idling program is being implemented at Rosewood Elementary School 

in Rock Hill. Additionally, the Catawba Regional Council of Governments, the South Carolina Energy 

Office, and the Museum of York County have provided matching funds for a two-year implementation of 

this Idle Reduction Program in York County Schools through Congestion Mitigation and Air Quality 

(CMAQ) funding. 

 • Additional emission reducing projects to receive CMAQ funds include signal controller 
69 

upgrades, intersection improvements, and bike/pedestrian projects. 

 • York Technical College has received a grant to retrofit nonroad equipment with diesel 

oxidation catalysts. The catalysts will be installed on 50 vehicles, including backhoes, bulldozers, motor 

graders, and others from the fleets of the City of Rock Hill, the South Carolina Department of 

Transportation, and Chester County. 

 • Where no transit has been available, Dial-a-Ride service will start in the City of Rock Hill 

(expanded from York County.) 

 • RFATS is participating in the Charlotte Region HOV lane study for I-77. 

 • A lawn mower exchange was held in York County in April 2007. 

 • RFATS is studying transit alternatives to connect downtown Rock Hill and Uptown 

Charlotte (Rock Hill-York County-Charlotte Transit Study.) 

 • Duke Energy launched a pilot program to subsidize public transportation costs for 

Charlotte area employees as part of the company's commitment to the environment and its ongoing efforts 

to help reduce ozone related emissions. Beginning September 1 and running through December 31 of 

2006, the pilot program provided subsidies and incentives around bus transit, carpools and vanpools for 

full time and part time employees who work at the following Duke Energy locations: Catawba Nuclear 

Station (York, S.C.), Customer Contact Center (University Research Park), McGuire Nuclear Station 

(Huntersville, N.C.), and uptown Charlotte. 

 • EnviroFlash has been configured and activated for South Carolina's Catawba region. The 

Catawba region will include York, Chester, and Lancaster counties. By including York County in the 

Catawba region, the SCDHEC will take over duties from North Carolina with regard to ground-level 

ozone forecasting for the county. The SCDHEC believes that the resources in South Carolina are 

available to provide York County with an accurate and reliable forecast during the ground-level ozone 

season. 

 The SCDHEC has initiated a program to continue the statewide focus on air quality that began with 

the Early Action Compact process. Staff are assigned to all counties of the state to work with local 

governments, businesses, and citizens to continue working to maintain and improve air quality. The 

SCDHEC, with its York County partners, will continue to seek opportunities that offer emission 

reductions that may be needed to show maintenance of the 8-hour ozone standard. 

 b. RACT 

 In accordance with 40 CFR Part 51, Subpart X - §51.912 pertaining to moderate nonattainment areas 

under the 8-hour ozone NAAQS, the State is required to submit to the USEPA an amendment to the SIP 

that includes the identification and implementation of reasonably available control technology (RACT).

The SIP amendment must meet the NOx and VOC RACT requirements in Sections 172(c)(1), 182 

(a)(2)(A), 182(b)(2), and 182(f) of the CAA. The State must implement all reductions in emissions from 

existing sources in the nonattainment area as may be obtained through the adoption of RACT that will 

provide for attainment of the NAAQS as expeditiously as practicable. The CAA requires that RACT be 

applied to major stationary sources of NOx and VOCs located in ozone nonattainment areas. A major 

source is considered any source with the potential to emit 100 tons per year or more of NOx or VOCs. 

 As defined by the USEPA in 40 CFR Section 51.100 - Definitions: Reasonably Available Control 

Technology (RACT) means devices, systems, process modifications, or other apparatus or techniques that
70 

are reasonably available taking into account (1) the necessity of imposing such controls in order to attain 

and maintain a national ambient air quality standard; (2) the social, environmental, and economic impact 

of such controls; and (3) alternative means of providing for attainment and maintenance of such standard. 

 RACT requirements are typically prescribed by State and local rules and regulations but may also be 

made on a case-by-case basis. In performing a RACT analysis, the State must look at available controls 

to conclude whether they are reasonably available for a specific source or source category. RACT 

requires that sources adopt controls that are reasonably available, thus they may not be the most stringent 

controls that have been adopted for other similar sources. The fact that another similar source has such 

controls in place does not mean that such a control is reasonably available for all other similar sources. 

 The SCDHEC has determined that there are no CTG (Control Technology Guidance) sources located 

within the nonattainment portion of York County. The SCDHEC has identified three affected major nonCTG sources within the ozone nonattainment portion of York County subject to RACT requirements and 

has approached these facilities to conduct a RACT analysis: 

 (1) Bowater, Inc. (Title V permit # 2440-0005); 

 (2) Cytec Carbon Fibers, LLC (Title V permit # 2440-0097); and 

 (3) Georgia Pacific Wood Products, LLC (Title V permit # 2440-0026). 

 The above facilities determined their RACT applicability based on "top down" procedures 

established for prevention of significant deterioration (PSD) and nonattainment new source review 

(NSR). A report of each facility's applicability determination that was prepared and submitted to the

SCDHEC for review is contained in Appendix Q. The SCDHEC concurred with the reports' conclusions 

that installation of additional emission control devices would not be economically feasible, thus only

work practice revisions will be utilized for RACT at these facilities. Georgia Pacific Wood Products,

LLC, however, will comply with maximum achievable control technology (MACT) requirements in 

accordance with 40 CFR 63, Subpart DDDD, whereby MACT is at least as stringent as RACT. 

 Any new sources with the potential to emit 100 tons per year or more of NOx or VOCs will be 

covered under the requirements of South Carolina Air Pollution Control Regulation R. 61-62.5, Standard

No. 7.1, Nonattainment New Source Review (NSR). 

On June 8, 2007, the USEPA published a final notice of reconsideration (72 FR 31727), Phase 2 of 

the Final Rule To Implement the 8-Hour Ozone National Ambient Air Quality Standard—Notice of 

Reconsideration. In this notice, the USEPA states that it has determined that EGU sources complying 

with rules implementing the Clean Air Interstate Rule (CAIR) requirements meet ozone NOx RACT 

requirements in states where all required emissions reductions are achieved from EGUs only. The 

USEPA does not believe that requiring source-specific RACT controls on EGUs in nonattainment areas 

will reduce total NOX emissions from EGU sources covered by the below the levels that would be 

achieved under the alone. 

 The SCDHEC amended South Carolina Air Pollution Control Regulation 61-62.72, Acid Rain; South 

Carolina Air Pollution Control Regulation 61-62.96, Nitrogen Oxides (NOx) Budget Trading Program 

General Provisions, and the SIP to ensure compliance with the provisions of the , which was published in 

the Federal Register on May 12, 2005. On June 22, 2007, the South Carolina State Register (State 

Register) promulgated the full text of the noted revisions, which became effective upon the date of 

publication. The South Carolina Legislature approved the amendments on May 27, 2007. 

 2. Reasonable Further Progress 
71 

 Section 182(b)(1) of the CAA mandates a 15 percent VOC emission reduction, accounting for 

growth, in the first 6 years after the baseline year (2002) for moderate and above ozone nonattainment

areas. Thus, for the York County nonattainment area, a reasonable further progress (RFP) analysis 

between 2002 and 2008 is required. 

 The methodology the SCDHEC used to calculate the RFP target levels of VOC emissions is based 

on the method developed in the CAA while taking into account the restrictions on creditable emissions 

and the need to use the 2002 inventory as a baseline. The CAA specifies four types of measures that are 

not creditable toward the 15 percent RFP requirement: 

 1. Any measure relating to motor vehicle exhaust or evaporative emissions promulgated by the 

USEPA by January 1, 1990. 

 2. Regulations concerning Reid Vapor Pressure (RVP) promulgated after 1990 or required 

under Section 211(h) of the CAA. 

 3. Measures required under Section 182(a)(2)(A) of the CAA to correct deficiencies in the SIP 

regarding VOC RACT regulations required prior to enactment of the CAA Amendments of 1990. 

 4. State regulations submitted to correct deficiencies in existing or required I/M programs. 

 These four types of measures were all expected to result in a decrease in emissions between 1990 

and 1996. Of these four types of measures, RACT and I/M program corrections did not apply to South 

Carolina because the State was in attainment for all standards at that time, and the 1990 RVP 

requirements were completely in place by 1996 and therefore are already accounted for in the 2002 

baseline. As a result, they would produce no additional reductions between 2002 and 2008 or later 

milestone years. 

 However, the pre-1990 Federal Motor Vehicle Control Program (FMVCP) will continue to provide 

additional benefits during the first two decades of the 21st century as remaining vehicles meeting pre1990 standards are removed from the vehicle fleet. Because these benefits are not creditable for RFP 

purposes, in order to calculate the target level of emissions for future RFP milestone years, the SCDHEC 

first calculated the reductions that would occur over these future years as a result of the pre-1990 

FMVCP. Consistent with the requirements of Sections 182(b)(1)(C) and (D) and 182(c)(2)(B) of the 

CAA, the SCDHEC used the process described in Method 1 below to account for non-creditable 

reductions in calculating RFP targets for the 2008 milestone year. The SCDHEC did not have VOC 

RACT regulations in the York County nonattainment area prior to the enactment of the 1990 CAA, thus 

only the on-road mobile source sector required an estimation of non-creditable emissions. 

 Method 1: For areas that must meet a 15 percent VOC reduction requirement by 2008: 

 (A) Estimate the actual anthropogenic base year VOC inventory in 2002 with all 2002 

control programs in place for all sources. 

 (B) Using the same highway vehicle activity inputs used to calculate the actual 2002 

inventory, run the appropriate motor vehicle emissions model for 2002 and for 2008 with all post-1990 

CAA measures turned off. Any other local inputs for vehicle I/M programs should be set according to the 

program that was required to be in place in 1990. Fuel RVP should be set at 9.0 or 7.8 depending on the 

RVP required in the local area as a result of fuel RVP regulations promulgated in June, 1990. 

 (C) Calculate the difference between the 2002 and 2008 VOC emission factors calculated 
72 

in Step B and multiply by 2002 vehicle miles traveled (VMT). The result is the VOC emissions 

reductions that will occur between 2002 and 2008 without the benefits of any post-1990 CAA measures. 

These are the non-creditable reductions that occur over this period. 

 (D) Subtract the non-creditable reductions calculated in Step C from the actual 

anthropogenic 2002 inventory estimated in Step A. This adjusted VOC inventory is the basis for 

calculating the target level of emissions in 2008. 

 (E) Reduce the adjusted VOC inventory calculated in Step D by 15 percent. The result is 

the target level of VOC emissions in 2008 in order to meet the 2008 RFP requirement. The actual 

projected 2008 inventory for all sources with all control measures in place, including projected 2008 

growth in activity, must be at or lower than this target level of emissions. 

 The 2002 baseline VOC emissions for the York County nonattainment area are presented in Table 

VI-1. 

Table VI-1: York County Nonattainment Area 2002 Baseline VOC Emissions (tons/day) 

 Point Area Nonroad Highway 

Mobile Total 

York* 7.29 7.48 3.19 6.84 24.80 

*Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC

nonattainment area. 

 The 2008 VOC emission estimates are included in Table VI-2. 

Table VI-2: York County Nonattainment Area 2008 Projected VOC Emissions (tons/day) 

 Point Area Nonroad Highway 

Mobile Total 

York* 3.60 7.90 2.40 3.94 17.84 

*Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC

nonattainment area. 

 Table VI-3 provides the summary 15% RFP analysis showing the projected 2008 VOC emissions for 

the area, 17.84 tons/day, are well below the target level of emissions, 20.23 tons/day, as calculated using 

Method 1. See Appendix O for detailed modeling data. 

Table VI-3: York County* Nonattainment Area 15% RFP Analysis 

York County 15% RFP Analysis VOC 

(tons/day) Step from Method 1 

Total 2002 Base year anthropogenic VOC 

emissions 24.80 Step A 

Non-creditable VOC reductions 1.00 Step C 

2002 base year minus the non-creditable emissions 23.80 Step D 
73 

2008 target level of VOC emissions 20.23 Step E 

2008 projected VOC emissions 17.84 Projection < Target RFP goal met 

*Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC

nonattainment area. 

 The SCDHEC must show continued progress from 2008 through the attainment date (June 15, 2010). 

To do so, the SCDHEC calculated the expected benefits from the fleet turnover for the on-road and offroad mobile sectors. In 2009 and 2010, the SCDHEC expects approximately 0.73 tons per day of NOx

emissions reductions from this fleet turnover. The SCDHEC did not calculate future expected VOC 

emissions reductions in 2009 and 2010 since the area is NOx-limited, but additional VOC emission 

reductions are expected from the fleet turnover of the on-road mobile sector. The SCDHEC believes 

these additional reductions demonstrate continued reasonable further progress toward attainment beyond

2008. 

 3. Actual Emissions Inventory 

 Section 182(a)(1) and Section 172(c)(3) of the CAA require the development of a comprehensive, 

accurate current inventory of actual emissions from all sources of VOC and NOx in the nonattainment 

area. Such inventory was due two years after designation of the 8-hour ozone nonattainment areas, or by 

June 15, 2006. The SCDHEC met this requirement through the submission of the 2002 emission 

inventories under the Consolidated Emission Reporting Rule (CERR) for that portion of York County 

within the nonattainment area. The SCDHEC submitted statewide emissions inventories for point, area, 

nonroad mobile, and highway mobile sources. 

 The final 2002 emission inventories used in the attainment demonstration (found in "Appendix E - 

Emission Inventory Summary") will go through the public hearing process as part of the full attainment

demonstration, which will include any updates or revisions that are necessary since the CERR submittal. 

 4. Emissions Inventory Statement 

 Section 182(a)(3)(B) requires the SIP to contain a requirement for all owners or operators of 

stationary sources located in the nonattainment area and emit either VOC or NOx to submit a statement of 

actual emissions annually. The State may waive the requirement for sources that emit less than 25 tons 

per year of NOx or VOC emissions. 

 5. Periodic Emissions Inventory 

 Section 172(c)(3) and 182(a)(3)(A) of the CAA require periodic inventory submissions. 

Specifically, Section 182(a)(3)(A) requires the inventory be submitted every three years until the area is 

redesignated to attainment. The SCDHEC plans to meet this requirement through the CERR submittal. 

As such, the SCDHEC will submit the 2005 emissions inventory on or before June 1, 2007. 

 6. Permit Program Requirements 

 It is required per Sections 172(c)(5) and 182(a)(2)(C) of the CAA that there be a permit program 

consistent with the requirements of Section 173. In addition, an offset requirement of 1.15 to 1 is 

required per Section 182(b)(5). The SCDHEC submitted the regulations for the nonattainment new 

source review (NSR) contained in Regulation R. 61-62.5, Standard No. 7.1, Nonattainment New Source 

Review on July 1, 2005, to the USEPA for review and approval. These regulations adopted the new offset 
74 

requirement. Furthermore, the SCDHEC submitted amendments to Regulation R. 61-62.5, Standard No. 

7, Prevention of Significant Deterioration (PSD) permitting regulations to the USEPA for approval on 

July 1, 2005. The SCDHEC believes that the "prevention of significant deterioration" requirement of 

Section 110(a)(2)(D)(i) is met by the adoption and submittal of the NSR and PSD regulations since PSD 

and NSR are applicable to major sources in South Carolina. The SCDHEC believes it has satisfied the 

permit program requirements for a moderate nonattainment area. 

 

 7. Gasoline Vapor Recovery 

 Section 182(b)(3) of the CAA requires moderate and above ozone nonattainment areas to implement 

Stage II vapor recovery programs. However, Section 202(a)(6) of the CAA states that the Section 

182(b)(3) Stage II requirement shall not apply in moderate areas after onboard refueling vapor recovery 

(ORVR) rules are promulgated. The USEPA promulgated the ORVR regulations on April 16, 1994. 

Therefore, 8-hour ozone moderate areas designated in 2004 are not subject to the Stage II vapor recovery 

program requirements. The attainment plan and contingency plan contained in this submittal addresses 

the necessary controls to attain the 8-hour standard in the Metrolina region. 

 8. Inspection and Maintenance (I/M) Program 

 The USEPA initially recommended the development of an On-Board Diagnostics (OBD) program 

for the Rock Hill-Fort Mill Area Transportation Study (RFATS) Metropolitan Planning Organization 

(MPO) portion of the Charlotte-Gastonia-Rock Hill, NC-SC moderate nonattainment area. The SCDHEC 

examined the feasibility and impact of implementing an I/M program for the nonattainment portion of 

York County that would have affected only 55,700 vehicles. Emissions modeling indicated that an OBDII 

program, if implemented in the nonattainment area, would only reduce NOx emissions by about 87 tons 

annually and volatile organic compounds emissions by about 63 tons annually, or approximately 49 tons 

and 37 tons, respectively, during the ozone season. The SCDHEC approached several contractors to 

develop and implement an OBDII I/M program in the area but was unable to find a contractor who would 

undertake the expenses involved in running an I/M program of this size. The SCDHEC found that it was 

not economically feasible to proceed with implementation of an I/M program in South Carolina, and 

proceeded to petition the USEPA for a waiver of this moderate nonattainment area requirement. 

 Based upon correspondence between the SCDHEC and the USEPA Region 4 after their consultation 

with the USEPA's Office of Transportation and Air Quality and the Office of General Counsel, the 

USEPA concurred that the I/M requirement for moderate areas is not applicable to York County, SC. On 

November 23, 2005, the USEPA Region 4 notified the SCDHEC that the CAA requirement to implement 

an Inspection and Maintenance (I/M) program was not applicable to the York County, South Carolina 

RFATS MPO moderate nonattainment area. The correspondence from USEPA Region 4 stated: 

 "Even though a portion of York County was designated as part of the Charlotte moderate 8-hour 

ozone nonattainment area, applicability of the I/M regulations to areas outside the Ozone Transport 

Region is based on the population of the urbanized area as defined by the 1990 census. As defined by the 

1990 census (see enclosed map), the Rock Hill and Charlotte urbanized areas are distinct and are not 

contiguous. Although the Charlotte urbanized portion of the MSA is contiguous to the North 

Carolina/South Carolina border, it does not extend into South Carolina. The Rock Hill urbanized area is 

totally contained within South Carolina and does not touch the State line. Therefore, the applicability 

level of a 1990 census population of 200,000 or more in an urbanized area (40 CFR 51.350(a)(1)) applies 

to each of the two urbanized areas separately. Since the Rock Hill urbanized area has a population less 

than 200,000, the I/M requirement in Section 182(b)(4) of the CAA is not applicable to York County." 

 See "Appendix R - I/M Supporting Documents" for copies of the following correspondence between 
75 

the SCDHEC and the USEPA Region 4 relating to the I/M requirement for the nonattainment portion of 

York County. 

 October 26, 2004 (SCDHEC BAQ to USEPA Region 4) 

 December 27, 2004 (EPA Region 4 to SCDHEC BAQ) 

 August 26, 2005 (SCDHEC to USEPA Region 4) 

 October 3, 2005 (EPA Region 4 to SCDHEC) 

 November 23, 2005 (EPA Region 4 to SCDHEC) 

 "Appendix R - I/M Supporting Documents" also includes a copy of the SCDHEC comments on the 

proposed rulemaking amendments to the vehicle I/M programs requirements to address the 8-hour 

NAAQS for Ozone dated February 7, 2005. 

 9. Other Measures 

 The SCDHEC evaluated the expected emission reductions through the implementation of Federal 

and State programs and regulations. Many of the NOx stationary point sources have already been or will

be controlled upon implementation of the NOx SIP call and SIP initiatives. In addition, the South 

Carolina Air Pollution Control Regulations and Standards has been amended with the addition of a new 

Regulation 61-62.5, Standard No. 5.2 - Control of Oxides of Nitrogen, and a revision of Regulation 61-

62.2 - Prohibition of Open Burning, for additional control of NOx emissions. 

 a. NOx SIP Call 

 On October 27, 1998, the USEPA finalized a Nitrogen Oxides (NOx) State Implementation Plan 

(SIP) Call Rule. The NOx SIP Call was designed to reduce the regional transport of ground-level ozone 

through reductions in NOx from electric generating unit (EGU) sources and from some non-EGU sources. 

The rule requires that, beginning in 2004, NOx reductions must occur during ground-level ozone season in 

states whose NOx emissions have been identified as contributing to 1-hour ozone standard nonattainment 

in "downwind" states. The rule also requires states to identify pollution-reduction measures and develop 

a plan to achieve these reductions. 

 A draft SIP revision was submitted to the USEPA on October 30, 2000. The SCDHEC Board 

(Board) granted initial approval on December 14, 2000. A public hearing was conducted before the 

Board on April 12, 2001, at which time the Board instructed staff to provide an additional 30-day 

comment period. A second notice of proposed regulations was published in the State Register on April 

27, 2001. Final Board approval was granted on June 14, 2001. Legislative review was required and the

final regulation was published in the State Register on May 24, 2002, as document number 2593. The 

draft SIP revision was submitted to the USEPA on July 30, 2001 for parallel processing. On April 10, 

2002, the USEPA published the proposed approval of the plan in the Federal Register (67 FR 17317). 

Final USEPA approval was published in the Federal Register on June 28, 2002. 

 Each state subject to the NOx SIP Call regulation has a NOx budget that the state allocates to 

applicable sources. The budget is NOx-based on cost-effective reductions in emissions that can be 

achieved by the affected sources. South Carolina's state trading program budget, as specified in 

Regulation 61-62.92, Nitrogen Oxides (NOx) Budget Trading Program, is 19,678 tons. The NOx SIP Call 

regulation will be repealed after 2009 upon implementation of the Clean Air Interstate Rule. 
76 

 b. 8-hour Ozone Early Action Compact Regulations

 On August 22, 2002, the SCDHEC published a Notice of Drafting in the State Register announcing 

its intent to pursue Early Action Compacts (EAC) for the 8-hour ozone standard. Through the EAC 

process, local, state, and USEPA officials committed to work together to develop and implement plans 

that will reduce ozone pollution so that areas are attaining the 8-hour ozone standard earlier than would be 

required by the Clean Air Act. Only areas that are attaining the 1-hour ozone standard are eligible to 

participate in the EAC process. The compact requires these areas to attain the 8-hour ozone standard by 

December 31, 2007, a date that is sooner than would otherwise be required through the traditional 

nonattainment designation process. 

 At the end of 2002, 45 of South Carolina's 46 counties, the SCDHEC, and the USEPA Region 4 had 

signed compacts to implement ozone reduction strategies earlier than federally required. Statewide 

stakeholder groups involving local and federal governments, industry, environmental groups, and other 

interested parties have worked together to plan and implement strategies for ozone pollution prevention 

throughout the state. Plans involve mobile source pollution reduction, outreach actions, and point source 

prevention, which provide flexibility and foster local solutions to local problems. In 2002, York County 

elected to participate in the 8-hour Ozone EAC process. However, due to an area of York County (Rock 

Hill-Fort Mill Area Transportation Study Metropolitan Planning Organization, also known as RFATS 

MPO) being included in the Charlotte-Gastonia-Rock Hill, NC-SC nonattainment area, that portion of the

county designated as nonattainment was no longer eligible to participate even though York County was 

designated attainment for the 1-hour ozone standard. York County officials have continued working with 

stakeholders to implement emission reduction measures and submit EAC progress reports every 6 

months. 

 As part of this process, the EAC stakeholders developed statewide regulations aimed at achieving 

additional reductions in ozone precursors. One new regulation that was developed as part of this process 

was Regulation 61-62.5, Standard 5.2, Control of Oxides of Nitrogen (NOx). This is a broad-based 

regulation that applies statewide to new and existing stationary sources that emit NOx from fuel 

combustion and have not undergone a best available control technology (BACT) analysis for NOx. For 

new sources, the regulation requires the installation of control technology that is based on BACT 

standards found in the RACT/BACT/LAER clearinghouse. For existing sources, the regulation only 

applies when an applicable unit replaces its burner. At this point, they will be required to replace their 

burner with a low NOx burner or equivalent technology capable of achieving a 30 percent reduction from 

uncontrolled levels. 

 Also, as part of the EAC process, Regulation 61-62.2, Prohibition of Open Burning, was revised by 

deleting the exception for the burning of household trash, revising the exception for the burning of 

construction waste, and revising the exception for fires set for the purpose of firefighter training. The 

burning of household trash presents health and environmental concerns for many communities. The 

smoke generated from these activities is a nuisance to some and a health threat to others with asthma or 

other respiratory problems. With respect to the exception for the burning of construction waste, the 

regulation was revised to allow only residential construction waste to be burned outside the ozone season, 

and this will only be allowed if it meets the provisions of the regulation. Finally, the exception for the 

purpose of firefighter training was revised to ensure that minimum health, environmental, and safety 

concerns are addressed. 

 These regulations were approved by the Board in January 2004, and, in accordance with South 

Carolina law, they were subsequently submitted to the Legislature for approval. The South Carolina 

General Assembly approved the regulations, and the rules were published and became effective upon 
77 

publication in the State Register on June 25, 2004. Statewide NOx reductions from the Control of NOx

regulation are estimated at 3,357 tons a year. Statewide reductions resulting from the revisions to the 

Prohibition of Open Burning regulation are estimated at 147 tons of NOx and 698 tons of VOC per ozone 

season. 

 c. Clean Air Interstate Rule 

 On March 10, 2005 the USEPA finalized the Clean Air Interstate Rule, also referred to as CAIR. On 

May 12, 2005, CAIR was published in the Federal Register. 

 CAIR affects 28 states and the District of Columbia, whose emissions of sulfur dioxide (SO2) and/or 

NOx produced by EGU sources and some non-EGU sources contribute significantly to the nonattainment 

of the National Ambient Air Quality Standards (NAAQS) for fine particles (PM2.5) and/or 8-hour ozone in 

downwind states. (SO2 and NOx are both precursors to ground-level ozone formation, and NOx is also a 

precursor to PM2.5 formation.) The USEPA has determined that EGU sources in South Carolina are 

affecting the nonattainment of ozone and PM2.5 standards in downwind states. CAIR is a cap-and-trade 

program for NOx and SO2 emissions from affected facilities and has two phases of implementation. The 

caps for the phases are as follows: 

 Phase I, which begins in 2009 for NOx (annual and ozone season) and 2010 for SO2 

 CAIR NOx annual cap = 32,662 tons (T) 

 CAIR EGU SO2 annual cap = 57,271 T 

 CAIR NOx ozone season cap = 15,249 T 

 Phase II, which begins in 2015 for both pollutants 

 CAIR NOx annual cap = 27,219 T 

 CAIR EGU SO2 annual cap = 40,089 T 

 CAIR NOx ozone season cap = 12,707 T 

 was due for submission to the USEPA for approval on September 11, 2006. South Carolina is one 

of many states that did not meet this deadline because of a lengthy regulatory process. The SCDHEC is

working closely with USEPA Region 4 toward implementation of the State's rule. The SCDHEC has 

adopted the federal with modifications in areas where the state has flexibility. A Notice of Drafting was 

published in the State Register on July 22, 2005; a second Notice of Drafting was published in the State 

Register on February 24, 2006. The initial approval to proceed with the proposed regulation was given by 

the SCDHEC Board on September 14, 2006. The Notice of Proposed Rule was first published in the 

State Register on October 27, 2006. A public hearing before the SCDHEC Board was held on January 

11, 2007. On January 22, 2007, the proposed regulation was submitted to the South Carolina Legislature 

for approval. In March of 2007, the SCDHEC submitted a request to the USEPA Region 4 for parallel 

processing. The SCDHEC anticipates the proposed regulation to become state-efffective upon 

publication in the State Register in mid-Summer 2007. South Carolina is working with the USEPA to 

complete the parallel processing at this time. 

 d. Regulation R. 61.62.2, Prohibition of Open Burning

 On June 24, 2004, the Department revised its existing regulation regarding open burning activities to

reduce emissions of ozone precursor pollutants. Among the revisions were elimination of the exception

for burning household trash, modification of the exception of burning of construction waste, and 

modification to the exception for fires set for firefighter training. Based on the Department’s 1999 

emissions inventory, residential burning of household waste generates 2,379 tons of NOx and 11,896 tons 

of VOCs in the state annually. As for the ban on the burning of construction waste, the data indicates that 
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the ban on residential construction waste alone will result in annual reductions of 147 tons of NOx and 

625 tons of PM. Information on the amount of reductions to be expected from the ban on the burning of

commercial construction waste is not available, but it is clear that substantial reductions in NOx and 

VOCs will occur statewide starting in 2004 as a direct result of the elimination of this activity as well. 

Regarding the burning of construction waste, the Department revised this provision to allow only 

residential construction waste to be burned and only under the following conditions: the burning must 

take place outside of ozone season (not during April 1 through October 30 in South Carolina), the burning 

must be conducted at least 500 feet from any occupied structure, and the burning must be only of “clean” 

waste. Further, the exception for the purpose of firefighter training has been revised to ensure that

minimum health, environmental and safety concerns are addressed. The Department intends to do a 

review of permanent firefighter training facilities and will evaluate nonpermanent sites and require 

Department approval prior to a burn. Finally, in accordance with South Carolina Air Pollution Control

Regulation 61-62.2, Section II.C., the Department reserves the right to restrict open burning on forecasted 

code orange and higher air quality ozone action days for York County. 

 e. Regulation R. 61-62.5, Standard 5.2, Control of Oxides of Nitrogen

 On June 24, 2004, South Carolina adopted Air Pollution Control Regulation R.61-62.5, Standard No. 

5.2, Control of Oxides of Nitrogen to ensure areas attain and maintain the 8-hour ozone standard. This 

regulation requires Best Available Control Technology (BACT)-level controls on all stationary sources 

that emits or have the potential to emit NOx. Many of these sources would not otherwise be required to 

control their NOx emissions. For example, under the Clean Air Act requirements, the preconstruction 

review program referred to as New Source Review (NSR) only applies to larger sources (generally those 

with potential emissions greater than 100 tons per year or more). For sources with emissions below these 

levels, there are generally no controls for NOx required. 

 This newly-developed regulation applies state-wide to new and existing stationary sources of NOx

emissions. Larger sources that have undergone a BACT review for NOx are exempt from the regulation; 

however, larger sources that have taken limits to opt out of a Prevention for Significant Deterioration 

(PSD) review will still be required to comply with this regulation which covers sources ranging from 

boilers and turbines to fluidized bed combustors and lime kilns. For existing sources, the regulation only 

applies when an applicable unit replaces their burner. At this point, they will be required to replace their 

burner with a low burner or equivalent technology capable of achieving a 30% reduction from 

uncontrolled levels. 

 10. Compliance with Section 110(a)(2) 

 Section 172(c)(7) requires nonattainment SIPs to meet the applicable provisions of Section 

110(a)(2). The NCDAQ and the SCDHEC - BAQ have reviewed the requirements of Section 110(a)(2) 

and have concluded that the prior rule submittals, along with this attainment demonstration plan, address 

the relevant requirements. 

 11. Equivalent Techniques 

 The SCDHEC believes that the procedures for modeling, emissions inventory and planning follow 

USEPA guidance and is not requesting approval for equivalent techniques, as allowed under Section 

172(c)(8) of the CAA. 

 12. Contingency Measures 
79 

 Section 172(c)(9) requires that the nonattainment SIPs contain specific measures that would take 

effect upon a State's failure to attain the ozone standard in a given area, without further action by the State 

or the USEPA. Guidance from the USEPA indicates that the measures should be approximately three 

percent of the baseline emissions, so that reasonable progress level of reduction could be expected to

occur in the year following the failure to attain. The SCDHEC elected to adopt NOx-only contingency 

measures since the area is NOx-limited. The contingency plan consists of Federal and State measures. 

The Federal measures result from the fleet turnover of the light and heavy-duty engine standards from the 

on-road mobile sector and the nonroad engine standards. These measures are already adopted and the 

fleet turnover will occur without further action by either the State or the USEPA. The fleet turnover will 

result in approximately 0.11 tons/day NOx emission reductions, or about 2.2% of the base emissions. The 

analysis of these emission reductions is included in Appendix P. 

 The State anticipates additional reductions from local measures implemented by the Rock Hill-Fort 

Mill Area Transportation Study (RFATS) Metropolitan Planning Organization (MPO). SC has been 

determined to be NOx limited, the SCDHEC will encourage the RFATS Interagency Partners to fund 

future CMAQ projects that will result in the most reduced NOx emissions. There is no easy way to 

estimate the amount of reductions that would be achieved through Congestion Mitigation and Air Quality

(CMAQ) projects. 
80 

SECTION VII. MOTOR VEHICLE EMISSION BUDGET 

A. 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 8-hour 

ozone standard. The level of emissions estimated by the Rock Hill-Fort Mill Area Transportation Study

Metropolitan Planning Organization (also known as RFATS) for the Transportation Implementation Plan 

(TIP) and Long Range Transportation Plan (LRTP) must not exceed the motor vehicle emission budget 

(MVEB) as defined in this attainment demonstration.

 1. Memorandum of Agreement 

 On September 27, 1996, a Memorandum of Agreement (MOA), negotiated between the South 

Carolina Department of Health and Environmental Control (SCDHEC) and the South Carolina 

Department of Transportation (SCDOT), was published in the South Carolina State Register. The 

purpose of the MOA was to formally incorporate the applicable provisions of the transportation 

conformity review process in accordance with the requirements of the CAA as promulgated by the 

USEPA on November 24, 1993 (58 FR 62188) in 40 CFR Part 51 Subpart T, as amended August 7, 1995 

(60 FR 40098), and November 14, 1995 (60 FR 57179). Under those authorities, no department, agency, 

or instrumentality of the Federal government shall engage in, support in any way or provide financial 

assistance for, license or permit, or approve any activity that does not conform to the South Carolina Air 

Quality Implementation Plan (SIP). The transportation conformity rule requires Federal agencies to 

determine, prior to taking any action on transportation plans, programs, and projects, that such action will 

conform to the SIP to maintain the National Ambient Air Quality Standards (NAAQS). The 

transportation conformity regulation applies only to areas that are designated nonattainment or 

maintenance for any of the criteria pollutants (ozone, carbon monoxide, fine particulate matter, sulfur 

dioxide, nitrogen dioxide, or lead). 

 On August 15, 1997 (62 FR 43780), April 10, 2000 (65 FR 18911), and August 6, 2002 (67 FR 

50808), the USEPA promulgated amendments to the transportation conformity rule to streamline and 

clarify the criteria and procedures for determining the conformity of transportation plans, programs, and 

projects. The State was required by 40 CFR Part 51 Subpart T Section 51.390 to amend the SIP by 

specifically removing any previously applicable implementation plan transportation conformity 

requirements and submitting a revision to the SIP that addresses all requirements of 40 CFR Part 93 

Subpart A. A Notice of General Public Interest was published on August 25, 2000. This SIP revision 

was delayed by the time-consuming task of gathering the necessary signatures for a MOA. A staffconducted public hearing was held on the proposed revision on September 22, 2003. The SIP amendment 

was published as final in the State Register on October 24, 2003, and subsequently submitted to the 

USEPA for final approval on November 14, 2003. The USEPA published approval of the SIP revision in 

the Federal Register (69 FR 4245) on January 29, 2004. 

 In accordance with these requirements, the SCDHEC incorporated into the SIP a new MOA to 

implement Section 176 of the Clean Air Act (CAA), as amended (42 U.S.C. 7401, et seq.), the related 

requirements of 23 U.S.C. 109(j), and regulations under 40 Code of Federal Regulations (CFR) Part 93, 

Subpart A. The parties to this MOA are as follows: each of the South Carolina Metropolitan Planning 

Organizations (MPOs), the SCDHEC, the SCDOT, the Federal Highway Administration South Carolina 

Division Office (FHWA), the Federal Transit Administration (FTA), the USEPA Region 4 (USEPA), and 

local publicly-owned transit agencies not represented by aforementioned MPOs in nonattainment and 

maintenance areas. The “South Carolina Criteria and Interagency Consultation Procedures for the 

Determination of the Conformity of Transportation Plans, Programs, and Projects” provides for 
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interagency consultation, resolution of conflicts, and public consultation procedures. The parties to this 

MOA agreed to conduct transportation conformity determinations in accordance with the provisions of 40

CFR Part 93 Subpart A. 

 The SIP amendment consisted of the following documents: 

 1: South Carolina Transportation Conformity Memorandum of Agreement as endorsed by all 

 parties. 

 2: South Carolina State Register “Notice of Amendment to the South Carolina Air Quality 

 Implementation Plan” - Published on October 24, 2003. 

 3: Notice of Public Hearing published in the State Register on August 22, 2003. 

 4: Copy of the verbatim transcript of the September 22, 2003, Public Hearing. 

 5: South Carolina’s Legal Authority (Excerpt from the USEPA-approved SIP). 

 2. Conformity Interagency Consultation - York County/RFATS MPO 

 On April 15, 2004, the USEPA issued designations and classifications based on the severity of the 8-

hour ozone NAAQS in each state with an effective date of June 15, 2004. This included the RFATS 

MPO boundary for the York County area along with contiguous portions of North Carolina. In making 

the boundary and classification determinations, the USEPA utilized 8-hour ozone monitoring data from 

the 2001-2003 calendar years. Although the monitor in York County during that time was below the 8-

hour ozone standard of 0.085 parts per million (ppm), the USEPA determined that a portion of York 

County contributed to violating monitors in nearby North Carolina. The nonattainment area was 

classified under Subpart 2 of the Clean Air Act as being a “moderate” nonattainment area for ozone. This 

was decided based upon a monitored ozone value of 0.100 ppm in Rowan County, North Carolina. 

 As a minimum requirement, no later than June 15, 2005, the RFATS area was required to 

demonstrate transportation conformity to ensure that all projects utilizing federal funds do not have an 

adverse impact on the area’s air quality. Transportation Conformity consultation procedures as outlined 

in the South Carolina Transportation Conformity Memorandum of Agreement and endorsed by all parties 

enabled the nonattainment area to immediately begin the process. The York County Interagency 

Consultation process, which included representatives from the RFATS, the SCDHEC, the SC Department 

of Transportation, the USEPA Region 4, the SC Division Office of Federal Highways, the Federal Transit

Authority, the City of Rock Hill, and York County, was initiated on May 14, 2004, and is ongoing. 

Specific information regarding this process is included in Appendix F3 Section 4.1. 

 3. RFATS - CMAQ Projects 

 The Congestion Mitigation and Air Quality Improvement Program (CMAQ) was created by the 

Intermodal Surface Transportation Equity Act (ISTEA) in 1991, was reauthorized by the Transportation 

Equity Act for the Twenty-First Century (TEA-21), and was subsequently reauthorized by the Safe 

Accountable, Flexible Efficient Transportation Equity Act - a Legacy for Users (SAFETEA-LU). The 

CMAQ program provides funding for projects designed to help achieve and maintain the NAAQS. South 

Carolina receives an annual minimum apportionment, which in 2006 was a little over $10 million. A 

mandatory portion of that, nearly $2 million, was required to be used in the Rock Hill nonattainment area. 

To be eligible for the mandatory funding, projects must advance air quality goals. New roads or lanes

that would potentially increase traffic are not eligible for CMAQ funding. A variety of eligible project 
82 

types include traffic control signalization, traffic flow improvements, alternative fuel programs, transit 

projects, carpooling programs, and bicycle and pedestrian projects. 

 The RFATS MPO announced its approved list of CMAQ projects for the funding years 2004 through 

2006 at a press conference on January 26, 2007. The York County interagency consultation group, which

includes the RFATS MPO, the SCDHEC, the SCDOT, USEPA Region 4, the FHWA, and the FTA, has 

been meeting for several years to address transportation conformity and the attainment SIP. This group 

approved the methodology used in determining air quality benefits for the selected projects. All RFATSsponsored CMAQ projects are included in the RFATS 2030 Long Range Transportation Plan. The 

project list includes signalization improvements, turn lanes, bicycle paths, a hybrid trolley, alternative fuel 

vehicles, and an idle reduction and awareness program for schools. Of the ten projects on the list, seven 

are fully-funded. Project sponsors include the City of Rock Hill, RFATS, RFATS Congestion 

Management System, SCDOT District 4, York County, and the Catawba Regional Council of 

Governments (COG). Local matches were provided by the City of York, the City of Rock Hill, York 

County, the Catawba COG, the SC Energy Office, the Rock Hill School District, and the Museum of 

York County. Emissions reductions over the lifetimes of the currently-funded projects are estimated at 

1,999 tons of VOCs, 8,659 tons of CO, and 1,678 tons of NOx. Matching funding for the three additional 

projects will need to be identified before they can proceed. These projects, when funded, will produce 

additional reductions of 61 tons of VOCs, 266 tons of CO, and 52 tons of NOx. 

B. Highway Mobile Source VOC Insignificance 

 Section 93.109(k), in the Transportation Conformity Rule Amendments for the new 8-hour ozone 

and fine particulate matter NAAQS, addresses areas with insignificant motor vehicle emissions. The rule 

suggests that such a finding would be based on a number of factors, including the percentage of motor 

vehicle emissions in the context of the total SIP inventory, the current state of air quality as determined by 

monitoring data for that NAAQS, the absence of SIP motor vehicle control measures, and historical 

trends and future projections of the growth of motor vehicle emissions. Although there is a vehicle 

control measure (inspection and maintenance) program in place in the North Carolina counties of the 

Metrolina area, it was established for additional reductions in NOx emissions. There are incidental VOC 

emissions reductions as a result of this program; however, it is not believed the reduction of VOC 

emissions has resulted in decreased ozone levels. 

 The SCDHEC has examined the NCDAQ’s study to determine sources of VOC emissions and their 

contribution to ozone formation in the Metrolina area. Due to the generally warm and moist climate of

the Carolinas, vegetation abounds in many forms, and forested lands naturally cover much of each state. 

The NCDAQ has found that, as a result, the biogenic sector is the most abundant source of VOC 

emissions in the Carolinas, accounting for approximately 90% of the total VOC emissions. The 

overwhelming abundance of biogenic VOC emissions makes the majority of North and South Carolina, 

including the Metrolina area, a NOx-limited environment for the formation of ozone. 

 Additionally, the SCDHEC has reviewed a number of modeling sensitivity runs performed by the 

NCDAQ that were designed to determine the impact of highway mobile source VOCs on ozone formation 

in the Metrolina area. The results of these sensitivities indicate no change in future ozone concentrations 

in the Metrolina area when highway mobile VOC emissions are significantly changed (e.g., 50% 

decrease). These sensitivities are discussed in more detail in Appendix F.3. 

 The SCDHEC agrees with the NCDAQ findings that highway mobile VOCs are insignificant 

contributors to ozone formation in the Metrolina nonattainment area. Emission estimates indicate 

highway mobile VOC is a small percentage of the total VOC emissions inventory. Highway mobile VOC 

emissions are projected to decrease in the future, notwithstanding VMT increases. Emission sensitivity 
83 

modeling indicates no change in future ozone concentrations when VOC emissions are significantly 

changed. For these reasons, neither the NCDAQ nor the SCDHEC will be setting MVEB for VOC for 

the Metrolina nonattainment area. The SCDHEC consulted with its interagency transportation partners 

prior to reaching this conclusion. Both agencies will revisit the setting of MVEB for VOC if there is any 

future indication that the Metrolina area has become VOC-sensitive for ozone formation. 

As a result of the finding of VOC insignificance, the SCDHEC will not be establishing a VOC budget for

the 2008 Reasonable Further Progress determination nor the 2009 attainment demonstration. 

C. Motor Vehicle Emission Budgets 

 The MVEB will be set for the attainment year 2009. By the time the MVEB is found adequate or 

approved by the USEPA, the next transportation conformity regional emissions analysis should be for 

years 2009 and beyond. Therefore, an MVEB will not be set for the baseline year 2002. 

 Although emissions are usually expressed in terms of tons per day, the MVEBs will be set in terms 

of kilograms (kg) per day. The reason for the change is because the MOBILE model generates emission 

factors in grams per mile. In past conformity exercises, there have been some issues with conversion to 

tons per day, as well as concerns with how MVEBs were rounded to the hundredth place. Setting the 

MVEB in kilograms per day will avoid these issues in future conformity determinations. During the 

development of the MVEB, the interagency partners for the York County nonattainment area were 

consulted. 

Table VII-1 shows the York County on-road mobile NOx emissions expressed in tons per day and the 

corresponding kilograms per day values for 2009. 

Table VII-1: 2009 Highway Mobile Source NOx Emissions York County Nonattainment Area 

County 2009 

 Tons/day Kg/day 

York* 8.01 7,266 

*Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC

nonattainment area. 

 Upon the USEPA’s affirmative adequacy finding for the partial county MVEB, as shown in Table 

VII-2, it will become the applicable MVEB for the nonattainment portion of York County. 

Table VII-2: York County South Carolina NOx MVEB for 2009 

County MVEB (Kilograms/day) 

York* 7,266 

*Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC

nonattainment area.