Redesignation Demonstration 

and 

Maintenance Plan 

for 

The Charlotte-Gastonia-Rock Hill, NC-SC 

1997 8-Hour Ozone Nonattainment Area 

Prepared by 

North Carolina Department of Environment and Natural Resources 

Division of Air Quality 

November 2, 2011 
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Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area i 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Preface: This document contains the technical support for North Carolina’s Division of Air 

Quality to request the Charlotte-Gastonia-Rock Hill 1997 8-hour ozone nonattainment area be 

redesignated as attainment for the 1997 8-hour ozone national ambient air quality standard 

pursuant to §§107(d)(3)(D) and (E) of the Clean Air Act, as amended. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area ii 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

EXECUTIVE SUMMARY 

Introduction 

Ozone is formed by a complex set of chemical reactions involving volatile organic compounds 

(VOCs), nitrogen oxides (NOx) and to a lesser extent carbon monoxide. These gases are 

generated by utilities, combustion processes, certain industrial processes and even by natural 

sources such as trees. Tailpipe emissions from mobile sources (vehicles) are also significant 

sources of these pollutants. Even the emissions from such sources as boat engines, lawn mowers 

and construction equipment contribute to the formation of ozone. Ozone formation is promoted 

by strong sunlight, warm temperatures and light winds and is hence a problem predominantly 

during the hot summer months. 

The 1997 8-hour ozone national ambient air quality standard (NAAQS) is 0.08 parts per million 

(ppm). An exceedance of the 1997 8-hour ozone NAAQS occurs when a monitor measures 

ozone above 0.084 ppm on average for an eight-hour period. A violation of this NAAQS occurs 

when the average of the annual fourth highest daily maximum 8-hour ozone values over three 

consecutive years is greater than or equal to 0.085 ppm. This three-year average is termed the 

“design value” for the monitor. The design value for a nonattainment area is the highest monitor 

design value in the area. 

Charlotte-Gastonia-Rock Hill Nonattainment Designation 

The area surrounding Charlotte-Gastonia-Rock Hill, North Carolina-South Carolina, called the 

Metrolina area, was designated nonattainment for the 1997 8-hour ozone NAAQS on April 30, 

2004 (69 Federal Register 23858). The Metrolina nonattainment area includes the North 

Carolina counties of Cabarrus, Gaston, Lincoln, Mecklenburg, Rowan and Union; Coddle Creek 

and Davidson Townships in Iredell County, North Carolina; and the Rock Hill Metropolitan 

Planning Organization boundary in York County, South Carolina. The nonattainment 

designation was an action taken by the U. S. Environmental Protection Agency (USEPA) under 

Section 107(d) of the Clean Air Act (CAA). The CAA requires that some area be designated as 

nonattainment if a monitor is found to be in violation of a NAAQS. The USEPA took 

designation action in 2004 based on the ambient data from 2001-2003. At that time, the design 

value for the Metrolina area was 0.100 ppm. 

Current Air Quality 

There are currently seven ozone monitors located throughout the Metrolina nonattainment area 

and one monitor located in York County, South Carolina, just outside of the nonattainment area. 

The latest design value for the nonattainment area is 0.082 ppm based on the data from 2008-
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area iii 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

2010, and is therefore in attainment of the 1997 8-hour ozone NAAQS, and the area is eligible to 

be considered for redesignation to attainment. 

Maintenance Plan Requirements 

The State of North Carolina has implemented permanent and enforceable reductions in ozone 

precursor emissions in the North Carolina portion of the Metrolina nonattainment area. These 

actions include implementing the on-board diagnostic vehicle inspection and maintenance 

program that began on July 1, 2002, and an open burning ban during ozone action days. In 

addition, there have been several State rules that have resulted in reductions in emissions within 

and surrounding the nonattainment area. These State actions include the NOx SIP Call, the 

Clean Smokestacks Act legislation, and heavy-duty engine stop-gap rule for model years 2005 

and 2006. Finally, several actions at the Federal level by the USEPA have resulted in lower 

emissions throughout the eastern portion of the country. These Federal actions include the Tier 2 

engine standards for light and medium duty vehicles, heavy-duty engine standards, the low sulfur 

gasoline and diesel requirements, and off-road engine standards. 

This combination of State and Federal actions have resulted in cleaner air in the Metrolina area, 

and the anticipated future benefits from these programs are expected to result in continued 

maintenance of the 1997 8-hour ozone NAAQS in this region. A baseline year emissions 

inventory for NOx and VOC’s was developed for 2010, since the design value for the 2008-2010 

period showed attainment of the 1997 8-hour ozone NAAQS. Future year emissions inventories 

were also developed for the interim years 2013, 2016, 2019, and a final year emission inventory 

was developed for 2022. The future year emissions were lower than the 2010 emissions in all 

cases. This demonstrates that the Metrolina area is expected to maintain the 1997 8-hour ozone 

NAAQS through 2022, since in no future year are the emissions expected to be greater than they 

were in the baseline year. The area is also in compliance with Section 110 and Part D 

requirements of the CAA. 

Conclusion and Request for Redesignation 

Based on the information above and criteria established in Section 107(d)(3)(E) of the CAA, 

North Carolina is requesting that the USEPA redesignate the Charlotte-Gastonia-Rock Hill 

nonattainment area to attainment. The monitoring data clearly shows that the region has attained 

the 1997 8-hour ozone standard, and the maintenance demonstration shows that the future 

emission inventories are expected to be lower than the attainment year inventory through the 

implementation of the various control measures discussed above. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area iv 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

TABLE OF CONTENTS 

EXECUTIVE SUMMARY ............................................................................................................ ii

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

1.1 WHAT IS TROPOSPHERIC OZONE? .............................................................................. 1

1.2 CLEAN AIR ACT OF 1990 ................................................................................................ 1

1.3 CHARLOTTE-GASTONIA-ROCK HILL AIR QUALITY HISTORY ............................ 1

1.4 CLEAN AIR ACT REDESIGNATION CRITERIA ........................................................... 3

2.0 AIR QUALITY ......................................................................................................................... 4

2.1 HISTORIC AIR QUALITY (2001 – 2007) ......................................................................... 4

2.2 RECENT AIR QUALITY VALUES (2008 –2010) ............................................................ 6

2.3 PERMANENT AND ENFORCEABLE EMISSIONS REDUCTIONS ............................. 7

3.0 MAINTENANCE PLAN ........................................................................................................ 14

3.1 CONCEPT OF NORTH CAROLINA'S MAINTENANCE PLAN .................................. 14

3.2 FOUNDATION CONTROL PROGRAM ......................................................................... 15

3.2.1 Federal Control Measures ........................................................................................... 15

3.2.2 State Control Measures ................................................................................................ 18

3.2.3 Additional Programs Supporting Maintenance ........................................................... 22

3.3 EMISSIONS INVENTORIES AND MAINTENANCE DEMONSTRATION ............... 24

3.3.1 Theory of Approach .................................................................................................... 24

3.3.2 Emission Inventories ................................................................................................... 25

3.3.3 Summary of Emissions ............................................................................................... 29

3.3.4 Maintenance Demonstration ....................................................................................... 30

3.4 CONTINGENCY PLAN ................................................................................................... 32

3.4.1 Overview ..................................................................................................................... 32

3.4.2 Primary and Secondary Triggers ................................................................................ 33

3.4.3 Action Resulting From Trigger Activation ................................................................. 33

3.4.4 Tracking Program for Ongoing Maintenance ............................................................. 34

4.0 MOTOR VEHICLE EMISSIONS BUDGET FOR CONFORMITY .................................... 35

4.1 TRANSPORTATION CONFORMITY ............................................................................ 35

4.2 SAFETY MARGIN ........................................................................................................... 35

4.3 MOTOR VEHICLE EMISSION BUDGETS .................................................................... 36

5.0 STATE IMPLEMENTATION PLAN APPROVAL .............................................................. 40

5.1 INTRODUCTION ............................................................................................................. 40

5.2 EVIDENCE OF COMPLIANCE ...................................................................................... 40

6.0 STATE COMPLIANCE WITH CLEAN AIR ACT REQUIREMENTS............................... 43

7.0 CONCLUSION ....................................................................................................................... 44
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area v 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

LIST OF APPENDICES 

APPENDIX A: CORRESPONDENCE AND GUIDANCE DOCUMENTS 

APPENDIX B.1: POINT SOURCE INVENTORY DOCUMENTATION 

APPENDIX B.2: AREA SOURCE INVENTORY DOCUMENTATION 

APPENDIX B.3: ON-ROAD MOBILE SOURCE INVENTORY DOCUMENTATION 

APPENDIX B.4: NONROAD MOBILE SOURCE INVENTORY DOCUMENTATION 

APPENDIX C: HEARING REPORT, COMMENTS RECEIVED AND RESPONSES 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area vi 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

LIST OF ACRONYMS 

Acronym Definition 

oF Degrees Fahrenheit 

CAA Clean Air Act 

CERR Consolidated Emissions Reporting Rule 

CFR Code of Federal Regulations 

CO Carbon Monoxide 

E-GAS 5.0 Economic Growth Analysis System version 5.0 

FR Federal Register 

HC Hydrocarbons 

I/M Inspection and Maintenance 

MVEB Motor Vehicle Emission Budget 

NAAQS National Ambient Air Quality Standard 

NCDAQ North Carolina Division of Air Quality 

NCDENR North Carolina Department of Natural Resources 

NCDOT North Carolina Department of Transportation 

NOx Nitrogen Oxides 

PM Particulate Matter 

ppm Parts per million 

QA Quality Assure 

SIP State Implementation Plan 

SUV Sports Utility Vehicle 

TIP Transportation Improvement Program 

USEPA U.S. Environmental Protection Agency 

VMT Vehicle Miles Traveled 

VOC Volatile Organic Compounds 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 1 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

1.0 INTRODUCTION 

1.1 WHAT IS TROPOSPHERIC OZONE? 

Ozone, a strong chemical oxidant, adversely impacts human health through effects on respiratory 

function and can also damage forests and crops. Ozone is not emitted directly by the utilities, 

industrial sources or motor vehicles but instead, is formed in the lower atmosphere, the 

troposphere, by a complex series of chemical reactions involving nitrogen oxides (NOx), 

resulting from the utilities, combustion processes and motor vehicles, and reactive volatile 

organic compounds (VOCs). VOCs include many industrial solvents, toluene, xylene and 

hexane as well as the various hydrocarbons (HC) that are evaporated from the gasoline used by 

motor vehicles or emitted through the tailpipe following combustion. 

Ozone formation is promoted by strong sunlight, warm temperatures, and light winds. High 

concentrations tend to be a problem in the eastern United States only during the hot summer 

months when these conditions frequently occur. Therefore, the U. S. Environmental Protection 

Agency (USEPA) mandates seasonal monitoring of ambient ozone concentrations in North 

Carolina from April 1 through October 31 (40 CFR 58 App. D, 2.5). 

In 1997, the USEPA revised the primary (health) and secondary (welfare) national ambient air 

quality standards (NAAQS) for ozone by establishing 1997 8-hour standards. An exceedance of 

the 1997 8-hour ozone NAAQS occurs when a monitor measures ozone above 0.084 parts per 

million (ppm) on average for an eight-hour period. A violation of this NAAQS occurs when the 

average of the annual fourth highest daily maximum 8-hour ozone values over three consecutive 

years is greater than or equal to 0.085 ppm. This three-year average is termed the “design value” 

for the monitor. The design value for a nonattainment area is the highest monitor’s design value 

in the area. 

1.2 CLEAN AIR ACT OF 1990 

Since the 1977 amendments to the Clean Air Act (CAA), areas of the country that had not 

attained the ambient standard for a particular pollutant were formally designated as 

nonattainment for that pollutant. This formal designation concept was retained in the 1990 CAA 

Amendments. 

1.3 CHARLOTTE-GASTONIA-ROCK HILL AIR QUALITY HISTORY 

On April 15, 2004, the USEPA designated the Charlotte-Gastonia-Rock Hill, North CarolinaSouth Carolina area (referred to as the Metrolina area) as “moderate” nonattainment for the 1997 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 2 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

8-hour ozone standard (Figure 1-1) based on the ambient data from 2001-2003. At that time, the 

design value for the Metrolina area was 0.100 ppm. The Metrolina nonattainment area includes 

the North Carolina counties of Cabarrus, Gaston, Lincoln, Mecklenburg, Rowan and Union; 

Coddle Creek and Davidson Townships in Iredell County, North Carolina; and the Rock Hill 

Metropolitan Planning Organization boundary in York County, South Carolina. The official 

designation and classification was published in the Federal Register (FR) on April 30, 2004 (69 

FR 23858). The designation became effective on June 15, 2004. Prior to the implementation of 

the 1997 8-hour ozone standard, Gaston and Mecklenburg Counties had been maintenance for 

the 1-hour ozone standard. 

Figure 1-1. USEPA Designated 1997 8-hour Ozone Nonattainment Areas in North 

Carolina 

There are currently seven ozone monitors located throughout the Metrolina nonattainment area 

and one monitor located in York County, South Carolina, just outside of the nonattainment area. 

The North Carolina Division of Air Quality (NCDAQ) operates four of the monitors in the 

Metrolina area, the Mecklenburg County Air Quality (MCAQ) operates three of the monitors in 

the Mecklenburg County, and South Carolina Department of Health and Environmental Control 

(SCDHEC) operates the York County monitor. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 3 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

In 2009, all but one monitor, County Line located in Mecklenburg County, came into attainment 

of the 1997 8-hour ozone NAAQS. With the completion of the 2010 ozone season, this monitor 

attained the standard as well. The 2008-2010 design value for Metrolina nonattainment area is 

0.082 ppm. 

1.4 CLEAN AIR ACT REDESIGNATION CRITERIA 

Section 107(d)(3)(E) of the CAA, as amended, states an area can be redesignated to attainment if 

the following conditions are met: 

1. The USEPA has determined that the NAAQS have been attained. For ozone, the areas 

must show that the average of the fourth highest 8-hour ozone values from three (3) 

complete, consecutive calendar years of quality-assured air quality monitoring data must 

be below 0.085 ppm. 

2. The applicable implementation plan has been fully approved by the USEPA under section 

110(k). 

3. The USEPA has determined that the improvement in air quality is due to permanent and 

enforceable reductions in emissions. To demonstrate this, the State should estimate the 

percent reduction (from the year used to determine the design value for designation and 

classification) achieved from Federal, State, and local measures. 

4. The State has met all applicable requirements for the area under section 110 and Part D. 

5. The USEPA has fully approved a maintenance plan, including a contingency plan, for the 

areas under section 175A. 

In the sections to follow, the NCDAQ will provide the technical data necessary to show that the 

Charlotte-Gastonia-Rock Hill nonattainment area has attained and is expected to maintain the 

1997 8-hour ozone standard, and has met the requirements for redesignation set forth above. 

This document discusses the North Carolina portion of the nonattainment area. The SCDHEC 

have developed a maintenance plan for the South Carolina portion of the nonattainment area 

which is available upon request. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 4 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

2.0 AIR QUALITY 

2.1 HISTORIC AIR QUALITY (2001 – 2007) 

The NCDAQ and MCAQ have collected ambient monitoring data for the Metrolina area since 

the late seventies. At the time of the 1997 8-hour ozone designations, there were seven ozone 

monitors throughout the Metrolina nonattainment area and one monitor located in York County, 

South Carolina just outside of the nonattainment area (Figure 2-1). These monitors were 

installed in accordance with the Code of Federal Regulations (CFR) 40 CFR 58. 

Figure 2-1. Ozone Monitor Locations in the Metrolina Nonattainment Area 

Tables 2-1 and 2-2 below show the air quality data and corresponding design values for the 

monitors in the Metrolina region, respectively, from 2001 to 2009. As you can see from 

Table 2-2, most of the monitors near and downwind of Charlotte were in violation of the 1997 

8-hour ozone NAAQS for much of this period. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 5 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 2-1 Metrolina Area’s Historic 4th Highest 8-hour Ozone Values(2001-2009) 

Monitor 4th

 Highest 8-hour Ozone Values (ppm) 

2001 2002 2003 2004 2005 2006 2007 2008 2009 

Crouse 

AIRS ID #37-109-0004 

Lincoln County 

0.094 0.095 0.089 0.074 0.082 0.082 0.085 0.079 0.065

Garinger 

AIRS ID #37-119-0041 

Mecklenburg County 

0.099 0.103 0.086 0.085 0.088 0.091 0.093 0.085 0.069

Arrowood 

AIRS ID #37-119-1005 

Mecklenburg County 

0.086 0.094 0.073 0.077 0.085 0.078 0.087 0.073 0.068

County Line 

AIRS ID #37-119-1009 

Mecklenburg County 

0.099 0.107 0.088 0.083 0.090 0.093 0.096 0.093 0.071

Rockwell 

AIRS ID #37-159-0021 

Rowan County 

0.097 0.106 0.098 0.080 0.086 0.085 0.096 0.084 0.071

Enochville 

AIRS ID #37-159-0022 

Rowan County 

0.103 0.108 0.087 0.080 0.088 0.089 0.095 0.082 0.073

Monroe 

AIRS ID #37-179-0003 

Union County 

0.081 0.100 0.083 0.074 0.082 0.080 0.082 0.080 0.067

York 

AIRS ID #45-091-0006 

York County 

0.080 0.096 0.076 0.071 0.079 0.078 0.080 0.075 0.062
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 6 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 2-2 Metrolina Area’s Historic Design Values (2001 - 2009) 

Monitor Design Value (ppm) 

01-03 02-04 03-05 04-06 05-07 06-08 07-09 

Crouse 

AIRS ID #37-109-0004 

Lincoln County 

0.092 0.086 0.081 0.079 0.083 0.082 0.076 

Garinger 

AIRS ID #37-119-0041 

Mecklenburg County 

0.096 0.091 0.086 0.088 0.090 0.089 0.082 

Arrowood 

AIRS ID #37-119-1005 

Mecklenburg County 

0.084 0.081 0.078 0.080 0.083 0.079 0.076 

County Line 

AIRS ID #37-119-1009 

Mecklenburg County 

0.098 0.092 0.087 0.088 0.093 0.094 0.086 

Rockwell 

AIRS ID #37-159-0021 

Rowan County 

0.100 0.094 0.088 0.083 0.089 0.088 0.083 

Enochville 

AIRS ID #37-159-0022 

Rowan County 

0.099 0.091 0.085 0.085 0.090 0.088 0.083 

Monroe 

AIRS ID #37-179-0003 

Union County 

0.088 0.085 0.079 0.078 0.081 0.080 0.076 

York 

AIRS ID #45-091-0006 

York County 

0.084 0.081 0.075 0.076 0.079 0.077 0.072 

 Note: Bolded values represent violations of the 1997 8-hour ozone standard. 

2.2 RECENT AIR QUALITY VALUES (2008 –2010) 

The most recent three years of ozone monitoring data (2008-2010) for the Charlotte-GastoniaRock Hill nonattainment area demonstrate compliance with the 1997 8-hour ozone NAAQS. 

Table 2-3 is a summary of the fourth highest 8-hour average ozone concentration at the monitors 

in the Metrolina region for 2008-2010 and the design value. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 7 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 2-3 Metrolina Area’s Current Air Quality Data (2008 -2010) 

Monitor Year 4th

 Highest 8-hour 

ozone values (ppm) 

Design Value (ppm) 

2008-2010 

Crouse 

AIRS ID #37-109-0004 

Lincoln County 

2008 0.079 

2009 0.065 0.072 

2010 0.072 

Garinger 

AIRS ID #37-119-0041 

Mecklenburg County 

2008 0.085 

2009 0.069 0.078 

2010 0.082 

Arrowood 

AIRS ID #37-119-1005 

Mecklenburg County 

2008 0.073 

2009 0.068 0.073 

2010 0.078 

County Line 

AIRS ID #37-119-1009 

Mecklenburg County 

2008 0.093 

2009 0.071 0.082 

2010 0.082 

Rockwell 

AIRS ID #37-159-0021 

Rowan County 

2008 0.084 

2009 0.071 0.077 

2010 0.077 

Enochville 

AIRS ID #37-159-0022 

Rowan County 

2008 0.082 

2009 0.073 0.077 

2010 0.078 

Monroe 

AIRS ID #37-179-0003 

Union County 

2008 0.080 

2009 0.067 0.072 

2010 0.071 

York 

AIRS ID #45-091-0006 

York County 

2008 0.075 

2009 0.062 0.067 

2010 0.066 

The 2010 8-hour ozone monitoring data for the Metorlina area has been fully quality assured and 

was officially submitted to the USEPA in March 2011. 

2.3 PERMANENT AND ENFORCEABLE EMISSIONS REDUCTIONS 

There are several State and Federal measures that have been enacted in recent years that are 

resulting in permanent and enforceable emissions reductions. A list of those measures that 

contributed to the permanent and enforceable emission reductions are listed below and are more 

fully described in Section 3.2. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 8 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

The federal measures that have been implemented include: 

• Tier 2 vehicle standards: Began implementation in 2004 and requires all passenger 

vehicles in the manufactures fleet to meet an average standard of 0.07 grams of NOx 

per mile. Additionally, in January 2006 the sulfur content of gasoline was required to 

be on average 30 ppm which assists in lowering the NOx emissions. Most gasoline 

sold in North Carolina prior to January 2006 had a sulfur content of about 300 ppm. 

These emission reductions are federally enforceable. 

• Heavy-duty gasoline and diesel highway vehicle standards: Began to take effect in 

2004 and is designed to reduce NOx and VOC emissions. These emission reductions 

are federally enforceable. 

• Nonroad spark-ignition engines and recreational engines standards: Tier 1 of this 

standard was implemented in 2004 and Tier 2 started in 2007. These standards 

reduce NOx, HC and carbon monoxide emissions. These emission reductions are 

federally enforceable. 

• Large nonroad diesel engine standards: Promulgated in 2004, this rule is being phased 

in between 2008 through 2014. This rule will also reduce the sulfur content in the 

nonroad diesel fuel. When fully implemented, this rule will reduce NOx, VOC, 

particulate matter and carbon monoxide. These emission reductions are federally 

enforceable. 

The state measures that have been implemented include: 

• Clean Air Bill: This State legislation expanded the inspection and maintenance (I/M) 

program from 9 counties to 48. It was phased-in in the Metrolina nonattainment area 

from July 1, 2002 through January 1, 2004. This program reduces NOx, VOC and 

carbon monoxide emissions. The rule for the I/M program was submitted to the 

USEPA for adoption into the SIP in August 2002 and was federally approved in 

October 2002. Therefore, these emission reductions are both state and federally 

enforceable. 

• Open burning ban: This regulation prohibits open burning of man-made materials 

throughout the State. Additionally, this regulation prohibits open burning of yard 

waste in areas that the NCDAQ forecasts air quality action days. The open burning 

regulation reduces NOx and VOC emissions, as well as CO and fine particulate 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 9 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

matter. This rule was submitted to the USEPA for adoption into the SIP in March 

2006, however, the USEPA has not yet approved the adoption of this rule into the 

SIP. These emission reductions are currently state enforceable, however, once the 

USEPA has federally approved the rule into the SIP, these emission reductions will 

be federally enforceable as well. 

• NOx State Implementation Plan (SIP) Call rule: This rule was predicted to reduce 

summertime NOx emissions from power plants and other industries by 68%. These 

emission reductions are state and federally enforceable. 

• Clean Smokestacks Act: This State law requires coal-fired power plants to reduce 

annual NOx emissions by 77% by 2009 and to reduce annual sulfur dioxide emissions 

by 49% by 2009 and 73% by 2013. This law set a NOx emissions cap of 56,000 

tons/year for 2009 and sulfur dioxide emissions caps of 250,000 tons/year and 

130,000 tons/year for 2009 and 2013, respectively. The public utilities cannot meet 

these emission caps by purchasing emission credits. In 2009, the power plants 

subject to this law had combined NOx emissions of 37,691 tons/year, well below the 

56,000 tons/year cap. This law was submitted to the USEPA for adoption into the 

SIP in August 2009, however, the USEPA has not yet approved it into the SIP. These 

emission reductions are currently state enforceable, however, once the USEPA has 

federally approved the law into the SIP, these emission reductions will be federally 

enforceable as well. 

• Diesel Retrofits: As part of the North Carolina Mobile Source Emission Reduction 

Grants program, a number of cities, counties and school districts have installed Diesel 

Oxidation Catalysts (DOCs) or Diesel Particulate Filters (DPFs) on their diesel 

equipment. The vehicles that have been retrofitted include schools buses, as well as 

county fleet trucks for solid waste pickup. These types of filters are designed to 

remove particulate matter, and when used with ultra low sulfur diesel fuel, NOx and 

VOC emissions are also reduced. Even though these emission reductions are 

voluntary and not enforceable, they are still considered permanent reductions. 

• Diesel Emissions Reduction Act (DERA): DERA provides new diesel emissions 

reduction grant authority for the USEPA. This funding is used to achieve significant 

reductions in diesel emissions that improve air quality and protect public health. The 

DERA funds that the NCDAQ have received have been used to retrofit, repower, or 

replace existing diesel engines from on-road and nonroad mobile source 

vehicles/equipment. This program will reduce particulate matter, NOx, and VOC 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 10 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

emissions. Even though these emission reductions are voluntary and not enforceable, 

they are still considered permanent reductions. 

Local Program measures that have been implemented include: 

• Open Burning Prohibition: The MCAQ prohibits open burning of any kind year 

round. This prohibition is more stringent than the State’s open burning rule and 

therefore enhances this control measure’s overall benefit to the region. The open 

burning rule reduces NOx and VOC emissions as well as CO and fine particulate 

matter. 

• Diesel Engine Emission Reductions: The MCAQ has also received DERA funding as 

well as American Recovery and Reinvestment Act (ARRA) and Congestion 

Mitigation and Air Quality Improvement (CMAQ) funding. These funds have been 

used to retrofit, repower or replace existing diesel engines from on-road and nonroad 

mobile source vehicles/equipment. This program will reduce particulate matter, NOx 

and VOC emissions. Even though these emission reductions are voluntary and not 

enforceable, they are still considered permanent reductions. 

A recent review of the NOx emissions in the USEPA’s Clean Air Markets database shows a 

reduction in over 88,000 tons of NOx from the reporting sources between 2002 and 2010. 

Table 2-4 presents the annual emissions for the North Carolina sources in the USEPA Clean Air 

Markets database. 

Table 2-4. NOx Emissions from NC Sources in USEPA’s Clean Air Markets Database 

Year Annual NOx Emissions from NC 

Sources (Tons) 

2002 145,706 

2003 135,879 

2004 124,079 

2005 114,300 

2006 108,584 

2007 64,770 

2008 61,669 

2009 44,506 

2010 57,305 

Table 2-5 displays the NOx emission reductions, as the result of the NOx SIP call rule, from 

North Carolina power plants in the Metrolina nonattainment area, as well as the power plants 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 11 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

located directly north and west of the Metrolina region that may impact the nonattainment area. 

There are four facilities located within the North Carolina portion of the Metrolina nonattainment 

area located in Gaston, Lincoln and Rowan Counties. The facility west of the Metrolina region 

is Cliffside, located in Cleveland County and the facility north of the Metrolina region is 

Marshall located in Catawba County. This data is also from the USEPA Clean Air Markets 

Division’s database and represents the second and third quarters of the year (April through 

September), the period during which ozone levels are the highest. It is clearly demonstrated that 

the emissions from these facilities have significantly decreased during the ozone season since 

2002, with almost 10,000 tons of NOx reduction in the 2010 ozone season compared to 2002. 

The NOx SIP Call emission reductions are permanent and enforceable. 

Table 2-5. April – September NOx Emissions for Utilities Near Metrolina Area (tons/period) 

Facility County 2002 2003 2004 2005 2006 2007 2008 2009 2010 

Allen Gaston 5,011 3,643 4,002 3,589 3,001 3,053 3,082 2,188 2,925 

Riverbend Gaston 2,556 2,703 1,844 1,379 1,417 1,296 1,256 304 1,063 

Lincoln Lincoln 44 20 50 20 52 81 33 6 40 

Buck Rowan 1,084 1,468 1,089 1,286 1,262 870 832 197 783 

Marshall Catawba 9,283 9,101 8,243 7,558 6,370 7,253 7,151 4,481 4,861 

Cliffside Cleveland 1,944 2,149 1,738 1,782 1,540 1,311 1,173 561 357 

Total ----- 19,922 19,084 16,966 15,614 13,642 13,864 13,527 7,737 10,029 

A couple of measures to consider in determining how all of the emissions reductions have 

impacted air quality is whether the relationship of exceedance days or the maximum 4th highest 

ozone value with respect to high temperature days has changed over this time period. 

Temperature is one of the key meteorological factors that determines the ozone production 

potential of a given day. In North Carolina, many exceedances occur when the maximum daily 

temperature is 90 degrees Fahrenheit (oF) or greater. Figure 2-2 shows the relationship of 

exceedance days to high temperature days from 2000 through 2010 for the Metrolina region 

monitors. The relationship between the maximum 4th highest ozone value to high temperature 

days from 2000 through 2010 is displayed in Figure 2-3. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 12 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Figure 2-2. Relationship between high temperature days and number of exceedance days 

in the Metrolina area 

Figure 2-3. Relationship between high temperature days and maximum 4th highest ozone 

value in the Metrolina Area 

It is important to see how the ozone levels have changed over the last decade in response to 

lower NOx emissions in the State. The worst summer in terms of the number of exceedance 

days and observed 4th highest ozone concentrations was 2002, with 36 exceedance days in the 

Metrolina region and a maximum 4th highest concentration of 0.108 ppm. That summer there 

were 49 days when the temperature was 90 oF or greater in the Metrolina region. The next 

highest number of exceedance days occurred in 2007 with 25 days and 74 days with 

temperatures at or above 90 °F, yet the maximum 4th highest concentration was significantly 

lower than 2002 at 0.096 ppm. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 13 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

The most compelling evidence that the reduction in ozone concentrations is due to emission 

reductions and not just good weather conditions is the summer of 2010. In 2010, the Metrolina 

area experienced the hottest summer over the last decade with 86 days at or above 90 °F. 

However, the Metrolina area only observed four exceedance days and the maximum 4th highest 

concentration was only 0.082 ppm. North Carolina believes that these matrices clearly indicate a 

real and significant progress in the reduction of ozone concentrations in the Metrolina region due 

to the real, permanent and enforceable reductions in NOx emissions in the State. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 14 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

3.0 MAINTENANCE PLAN 

3.1 CONCEPT OF NORTH CAROLINA'S MAINTENANCE PLAN 

The State's plan for maintaining compliance with the ambient air quality standard for the 1997 

8-hour ozone in the Charlotte-Gastonia-Rock Hill nonattainment area consists of three major 

parts: a foundation control program, a maintenance demonstration, and a contingency plan. The 

foundation control program consists of the current Federal and State control measures already in 

effect, as well as the future benefits of the federal Clean Air Interstate Rule (CAIR), Federal 

Transport Rule (FTR), cleaner engine programs, and low sulfur gasoline and low sulfur diesel 

fuel programs. Although North Carolina did not rely on the emission reductions from CAIR or 

the FTR for maintenance of the 1997 8-hour ozone standard, these regulations will result in 

additional reductions in NOx emissions regionally. 

The NCDAQ has implemented programs and submitted rules and laws to be adopted into the 

SIP. Once these rules and laws have been approved into the SIP by the USEPA, these programs 

will remain enforceable and are hereby submitted as the plan to ensure that maintenance of the 

1997 8-hour ozone standard will continue. Sources are prohibited from reducing emission 

controls (anti-backsliding), for controls due to rules or laws that have been submitted to the 

USEPA for adoption into the SIP, following the redesignation of the area unless such a change is 

first approved by the USEPA as a revision to the North Carolina SIP that is consistent with 

Section 110(l) of the Clean Air Act. 

For the maintenance demonstration, the base year of 2010 was chosen since it is a year that falls 

within the attaining design value period of 2008-2010. The interim years chosen were: 2013, 

2016, and 2019 since the USEPA recommends three-year increments for interim years. The final 

year of the maintenance demonstration is 2022, since the CAA requires maintenance for at least 

ten years after redesignation. The maintenance demonstration consists of a comparison between 

the 2010 baseline emissions inventory and the projected emissions inventories (for 2013, 2016, 

2019 and 2022), which consider economic and population growth. The comparison shows that 

the total emissions in each of the interim years and the final year is estimated to be lower than in 

the base year, which demonstrates maintenance of the 1997 8-hour ozone standard. The 

reductions in emissions are due to the foundation control programs outlined below. 

The North Carolina contingency plan involves tracking and triggering mechanisms to determine 

when contingency measures are needed and a process of implementing appropriate control 

measures. The primary trigger of the contingency plan will be a violation of the ambient air 

quality standard for 1997 8-hour ozone standard. The secondary trigger will be a monitored air 

quality pattern that suggests an actual 1997 8-hour ozone NAAQS violation may be imminent. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 15 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

The SCDHEC has developed a maintenance plan for the South Carolina portion of the 

nonattainment area. A copy of the South Carolina redesignation demonstration and maintenance 

plan is available upon request. 

3.2 FOUNDATION CONTROL PROGRAM 

The main element of the maintenance plan is the foundation control program. The foundation 

control program contains the controls necessary to maintain the ambient air quality standards. 

The purpose of the foundation control program is to prevent the ambient air quality standards 

from being violated and thereby eliminate the need for more costly controls being imposed on 

industry and the general public. Each component of the State's foundation control program is 

essential in demonstrating maintenance of the air quality standards. 

The foundation control program consists of Federal and State measures. The Federal measures 

include the cleaner fuel programs and the federal highway motor vehicle and off-road equipment 

control program. State measures include the I/M program, the NOx SIP Call rule, the Clean 

Smokestacks Act, heavy duty diesel engine gap filling requirements and an open burning 

regulation. All of these programs have already been implemented or are in the process of being 

implemented. 

3.2.1 Federal Control Measures 

Tier 2 Vehicle Standards 

Federal Tier 2 vehicle standards 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, with full compliance required by 

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

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

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

compliance required by 2009. The new standards require vehicles to be 77% to 95% cleaner. 

The Tier 2 rule also reduced the sulfur content of gasoline to 30 ppm starting in January of 2006. 

Most gasoline sold in North Carolina prior to January 2006 had a sulfur content of about 300 

ppm. Sulfur occurs naturally in gasoline and interferes with the operation of catalytic converters 

on vehicles, which results in higher NOx emissions. Lower-sulfur gasoline is necessary to 

achieve the Tier 2 vehicle emission standards. These emission reductions are federally 

enforceable. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 16 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

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 began to take effect in 2004. A second phase of standards and 

testing procedures, began in 2007 and will reduce particulate matter from heavy-duty highway 

engines, and reduce highway diesel fuel sulfur content to 15 ppm since the sulfur damages 

emission control devices. The total program is expected to achieve a 90% reduction in 

particulate matter (PM) emissions and a 95% reduction in NOx emissions for these new engines 

using low sulfur diesel, compared to engines using higher-content sulfur diesel. These emission 

reductions are federally enforceable. 

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%. Prior to the fuel standard change, nonroad diesel fuel averaged about 3,400 ppm sulfur. 

The rule limits nonroad diesel sulfur content to 500 ppm by 2006 and 15 ppm by 2010. The 

combined engine and fuel rules is expected to reduce NOx and particulate matter emissions from 

large nonroad diesel engines by over 90%, compared to nonroad engines using higher-content 

sulfur diesel. These emission reductions are federally enforceable.

Nonroad Spark-Ignition Engines and Recreational Engines Standard

The nonroad spark-ignition and recreational engine standards, effective in July 2003, regulates 

NOx, hydrocarbons and carbon monoxide for groups of previously unregulated nonroad engines. 

These engine standards apply to all new engines sold in the United States and imported after 

these standards began and applies to large spark-ignition engines (forklifts and airport ground 

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

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

vehicle. 

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

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

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

formation and ambient carbon monoxide and particulate matter levels. For the off-highway 

motorcycles and all-terrain-vehicles, the exhaust emissions standard was phased-in. Fifty percent 

of model year 2006 engines had to meet the standard and for model years 2007 and later, all 

engines must meet the standard. Recreational marine diesel engines over 37 kilowatts are used 

in yachts, cruisers, and other types of pleasure craft. Recreational marine engines contribute to 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 17 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

ozone formation and particulate matter levels, especially in marinas. Depending on the size of 

the engine, the standard began phasing-in in 2006. 

When all of the nonroad spark-ignition and recreational engine standards are fully implemented, 

an overall 72% reduction in hydrocarbons, 80% reduction in NOx, and 56% reduction in carbon 

monoxide emissions are expected by 2020. These controls will help reduce ambient 

concentrations of ozone, carbon monoxide, and fine particulate matter. These emission 

reductions are federally enforceable. 

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 (May to September) NOx budgets for the 

purpose of reducing regional transport of ozone (63 FR 57356). This rule, referred to as the NOx 

SIP Call, required 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 assure that each 

state met its budget. A NOx trading program was established, allowing sources to buy credits to 

meet their NOx budget 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 Carolina. These emission 

reductions are federally enforceable. 

Clean Air Interstate Rule and Federal Transport 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 and a model rule for the 

states to use in developing their rules. The purpose of the CAIR is to reduce interstate transport 

of precursors of fine particulate and ozone. 

This rule provides annual state caps for NOx and sulfur dioxide for large fossil-fuel-fired electric 

generating units in two phases, with the Phase I caps for NOx and sulfur dioxide 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. These emission reductions are federally enforceable. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 18 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Due to court challenges of CAIR in 2008, the USEPA will be making changes to the program, 

however, the existing CAIR rules will remain in place until the USEPA promulgates changes to 

the program. The FTR will replace the CAIR rule and is expected to be promulgated summer of 

2011. The control requirements for the FTR are expected to be as stringent as the CAIR 

program. Although North Carolina did not rely on the emission reductions from CAIR or the 

FTR for maintenance of the 1997 8-hour ozone standard, these regulations will result in 

additional reductions in NOx emissions regionally. These new emission reductions will be 

federally enforceable. 

3.2.2 State Control Measures 

North Carolina has adopted a number or regulations, legislation and voluntary programs to 

address pollution issues across the State. These are summarized below. 

Clean Air Bill

The 1999 Clean Air Bill expanded the vehicle emissions I/M program in North Carolina from 9 

counties to 48 counties, between July 1, 2002 through January 1, 2006 (Figure 3-1). Vehicles are 

tested using the onboard diagnostic system (OBDII), an improved method of testing, which 

ensures proper emission system operation for vehicles and light trucks during their lifetime by 

monitoring emission-related components and systems for malfunction and/or deterioration. An 

important aspect of OBDII is its ability to notify the driver of malfunction and/or deterioration 

by illuminating the "check engine light". If the vehicle is taken to a repair shop in a timely 

fashion, it can be properly repaired before any significant and prolonged emission increase 

occurs. The previously used tailpipe test (i.e., idle test) did not measure NOx emissions; it only 

tested for VOC and carbon monoxide emissions. By utilizing the OBDII test method, the NOx 

emissions as well as other pollutants from motor vehicles are reduced. The effective dates for 

the counties in the North Carolina portion of the Metrolina nonattainment area are listed below. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 19 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Figure 3-1. North Carolina’s NOx Inspection & Maintenance (I/M) Phase-In Map 

County Date County Date 

Cabarrus July 1, 2002 Mecklenburg July 1, 2002 

Gaston July 1, 2002 Rowan July 1, 2003 

Iredell July 1, 2003 Union July 1, 2002 

Lincoln January 1, 2004 

The rule for the I/M program was submitted to the USEPA for adoption into the SIP in August 

2002 and was federally approved in October 2002. Therefore, these emission reductions are both 

state and federally enforceable. The expected NOx and VOC emission benefits for the base year 

2010 and the final year 2022 are listed in Table 3-1 below. The expected NOx and VOC 

emission benefits for the interim years are expected to be along the same as those seen in 2010 

and 2022. 

Table 3-1 NOx and VOC Emission Benefits From I/M Program (tons/day) 

County 2010 2022 

NOx VOC NOx VOC 

Cabarrus 0.61 0.31 0.42 0.32 

Gaston 0.64 0.32 0.33 0.24 

Iredell* 0.38 0.25 0.25 0.24 

Lincoln 0.24 0.14 0.17 0.13 

Mecklenburg 3.31 1.48 1.79 1.11 

Rowan 0.54 0.27 0.34 0.23 

Union 0.56 0.32 0.41 0.33 

Total 6.28 3.09 3.71 2.60 

* Nonattainment portion of county 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 20 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

NOx SIP Call Rule

In response to the USEPA’s NOx SIP call, North Carolina adopted rules to control the emissions 

of NOx from large stationary combustion sources. These rules cover (1) fossil fuel-fired 

stationary boilers, combustion turbines, and combined cycle systems serving a generator with a 

nameplate capacity greater than 25 megawatts and selling any amount of electricity, (2) fossil 

fuel-fired stationary boilers, combustion turbines, and combined cycle systems having a 

maximum design heat input greater than 250 million British thermal units per hour, and 

(3) reciprocating stationary internal combustion engines rated at equal or greater than 2400 brake 

horsepower (3000 brake horsepower for diesel engines and 4400 brake horsepower for dual fuel 

engines). As part of the NOx SIP call, the USEPA rules established a NOx budget for sources in 

North Carolina and other states. North Carolina has a Phase II budget (i.e., emissions allowance) 

of 165,022 tons of NOx per ozone season. 

North Carolina’s NOx SIP Call rule was predicted to reduce summertime NOx emissions from 

power plants and other industries by 68% by 2006. In October 2000, the North Carolina 

Environmental Management Commission (EMC) adopted rules requiring the reductions. 

In 2009, the NOx SIP Call program was replaced with the CAIR, a cap-and-trade program that 

will achieve reductions of emissions of sulfur dioxide and NOx in the eastern United States. 

NOx sources that were regulated under the NOx SIP Call are now regulated under the CAIR 

program. North Carolina adopted the CAIR rules in 2006 (amended in 2008). North Carolina’s 

CAIR rules set annual sulfur dioxide allowances as well as both ozone season and annual NOx 

allowances for coal-fired electric generating units and other large combustion sources. These 

regulations are due to a Federal program and thus are both state and federally enforceable. 

Due to the Court challenges of CAIR in 2008, the USEPA will be making changes to this 

program soon. However, the existing CAIR rules will remain in place until the USEPA 

promulgates changes to the program. 

Clean Smokestacks Act

In June 2002, the North Carolina General Assembly enacted the North Carolina Clean 

Smokestacks Act, which requires coal-fired power plants in North Carolina to reduce annual 

NOx emissions by 78% by 2009. These power plants must also reduce annual sulfur dioxide 

emissions by 49% by 2009 and 74% by 2013. This State law set a NOx emission cap for 2009 of 

56,000 tons/year and a sulfur dioxide emissions cap of 250,000 tons/year and 130,000 tons/year 

for 2009 and 2013, respectively. It is significant to note that these emissions caps set in this 

legislation cannot be met by purchasing credits from sources outside of North Carolina, but 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 21 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

rather must be real emission reductions at the power plants subject to the legislation. In 2009, 

the power plants subject to this law had combined NOx emissions of 37, 691 tons/year, well 

below the 56,000 tons/year cap. 

With requiring year-round NOx controls and not allowing the purchase of NOx credits to meet 

the caps, the Clean Smokestacks Act reduces NOx emissions beyond the requirements of the 

NOx SIP Call Rule. One of the first state laws of its kind in the nation, it provides a model for 

other states in controlling multiple air pollutants from older coal-fired power plants. This law 

was submitted to the USEPA for adoption into the SIP in August 2009, however, the USEPA has 

not yet approved it into the SIP. These emission reductions are currently state enforceable, 

however, once the USEPA has federally approved the law into the SIP, these emission reductions 

will be federally enforceable as well. 

Open Burning Bans

The North Carolina open burning regulation prohibits the burning of man-made materials 

statewide. In June 2004, the EMC approved revisions to the open burning regulation banning 

open burning of yard waste and land clearing debris on forecasted Code Orange or higher "air 

quality action days," for those counties that the NCDAQ or local air programs forecast ozone or 

fine particulate matter. The following counties in the Metrolina area are subject to this rule: 

Cabarrus, Gaston, Southern Iredell, Lincoln, Mecklenburg, Rowan and Union. 

The open burning regulation reduces particulate matter, sulfur dioxide, carbon monoxide, NOx, 

and VOC emissions. The estimated emission reductions for the base year and the final year of 

the maintenance plan are presented in Table 3-2. For a full explanation of how these emission 

reductions were estimated, please refer to Appendix B.2, the Area Source Emissions Inventory 

Documentation. 

Table 3-2 Estimated NOx and VOC Emission Reductions from Open Burning Regulation 

(tons/day) 

County 2010 2022 

NOx VOC NOx VOC 

Cabarrus 0.14 0.15 0.25 0.28 

Gaston 0.13 0.15 0.24 0.27 

Iredell 0.07 0.08 0.13 0.15 

Lincoln 0.13 0.15 0.24 0.27 

Mecklenburg 0.10 0.11 0.18 0.20 

Rowan 0.17 0.19 0.30 0.34 

Union 0.27 0.30 0.49 0.55 

Total 1.01 1.13 1.83 2.06 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 22 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

The open burning rule was submitted to the USEPA for adoption into the SIP in March 2006, 

however, the USEPA has not yet approved the adoption of this rule into the SIP. These emission 

reductions are currently state enforceable, however, once the USEPA has federally approved the 

rule into the SIP, these emission reductions will be federally enforceable as well. 

Idle Reduction Regulation

The EMC adopted the Heavy-Duty Vehicle Idling Restrictions rule to reduce unnecessary idling 

of heavy-duty trucks on July 9, 2009 and the rule became effective on July 10, 2010. This rule is 

state enforceable and generally prevents any person who operates a heavy-duty vehicle to cause, 

let, permit, suffer or allow idling for a period of time in excess of 5 consecutive minutes in any 

60 minute period. The expected emission reductions from this regulation were not included in 

the mobile source emissions estimated for this maintenance plan because the MOVES model 

does not incorporate such a program. 

Prevention of Significant Deterioration 

All new major sources of VOCs and NOx will be evaluated under the prevention of significant 

deterioration program and are required to use best available control technology. These emission 

reductions are state enforceable. 

3.2.3 Local Program Control Measures 

The MCAQ operates a state certified local air pollution program pursuant to North Carolina 

General Statue 143-215.122 and administers SIP rules throughout Mecklenburg County, 

including incorporated areas. The MCAQ prohibits open burning of any kind year round. This 

prohibition is more stringent than the State’s open burning rule and therefore enhances this 

control measure’s overall benefit to the region. 

3.2.4 Additional Programs Supporting Maintenance 

Air Awareness Program

The North Carolina Air Awareness Program is a public outreach and education program of the 

NCDAQ. The goal of the program is to reduce air pollution though voluntary actions by 

individuals and organizations. The program seeks to educate individuals about (1) the sources of 

air pollution; (2) the health effects of air pollution and how these effects can be mitigated by 

modification of outdoor activities on ozone action days; and (3) simple "action tips", such as 

carpooling, vehicle maintenance, and energy conservation, that reduce individual contributions 

to air pollution. One of the major program components is the year round daily air quality 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 23 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

forecast. The NCDAQ produces the 8-hour ozone forecasts and corresponding air quality index 

for the Metrolina forecast area from May 1 through September 30 of each year. 

Transportation Conformity 

The NCDAQ will work closely with the North Carolina Department of Transportation (NCDOT) 

and local transportation agencies to assure that Transportation Improvement Programs (TIPs) in 

the nonattainment area are consistent with and conform to the State's air quality program, 

including the SIP, and meet the Federal requirements on conformity. This conformity review 

shall be performed for all federally funded and all other major projects contained in TIPs, 

regardless of source of funding. Technical analysis of transportation plans, programs, and 

projects for conformity will be done cooperatively by the Statewide Planning Branch of the 

NCDOT and the NCDAQ. In the event that the NCDAQ disagrees with the NCDOT on a 

conformity determination or issue, the NCDAQ and the NCDOT will present the issue to the 

Governor for resolution. Additionally, the State will prepare NOx and VOC emissions analyses 

in the ozone conformity determinations. 

The public and interested parties are given an early and reasonable opportunity to comment on 

transportation plans, programs, projects and proposed conformity determinations in accordance 

with procedures adopted by metropolitan planning organizations pursuant to the requirements of 

the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (and 

any updated transportation legislation), as well as any updated transportation legislation, and the 

CAA as amended. 

Mobile Source Emission Reduction Grants

As part of the North Carolina Mobile Source Emission Reduction Grants program, a number of 

cities, counties and school districts have installed Diesel Oxidation Catalysts (DOCs) or Diesel 

Particulate Filters (DPFs) on their diesel equipment. The vehicles that have been retrofitted 

include schools buses, as well as county fleet trucks for solid waste pickup. Although these 

types of filters are designed to remove fine particulate matter, when used with ultra low sulfur 

diesel fuel, NOx and VOC emissions are also reduced. 

The Diesel Emissions Reduction Act (DERA) provides new diesel emissions reduction grant 

authority for the USEPA. This funding is used to achieve significant reductions in diesel 

emissions that improve air quality and protect public health. In response to DERA, the USEPA 

created grant and funding programs under the National Clean Diesel Campaign to build on the 

success of its regulatory and voluntary efforts to reduce emissions from diesel engines. The 

DERA funds, as well as the American Recovery and Reinvestment Act (ARRA) funding that the 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 24 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

NCDAQ have received have been used to retrofit, repower, or replace existing diesel engines 

from on-road and nonroad mobile source vehicles/equipment. Additionally, the MCAQ has 

received DERA, ARRA and CMAQ funding that have been used to retrofit, repower, or replace 

existing diesel engines from on-road and nonroad mobile source vehicles/equipment. 

3.3 EMISSIONS INVENTORIES AND MAINTENANCE DEMONSTRATION 

3.3.1 Theory of Approach 

There are two basic approaches used to demonstrate continued maintenance. The first is the 

comparison of a projected emissions inventory with a baseline emissions inventory. The second 

approach involves complex analysis using gridded photochemical modeling. The approach used 

by the NCDAQ is the comparison of emissions inventories for the years 2010 and 2022. 

For the maintenance demonstration, the base year of 2010 was chosen since it is a year that falls 

within the attaining design value period of 2008-2010. The maintenance demonstration is made 

by comparing the 2010 baseline summer day emissions inventory to the 2022 projected summer 

day emissions inventory. The baseline summer day emissions inventory represents an emission 

level for a period when the ambient air quality standard was not violated, 2008-2010. If the 

projected emissions remain at or below the baseline emissions, continued maintenance is 

demonstrated and it then follows, if the projected emissions remain at or below the baseline 

emissions, then the ambient air quality standard should not be violated in the future. In addition 

to comparing the final year of the plan, all of the interim years are compared to the 2010 baseline 

to demonstrate that these years are also expected to show continued maintenance of the 1997 

8-hour ozone standard. 

The emissions inventories are comprised of four major types of sources: point, area, on-road 

mobile and nonroad mobile. The projected summer day emission inventories have been 

estimated using projected rates of growth in population, traffic, economic activity, and other 

parameters. Naturally occurring, or biogenic, emissions are not included in the emissions 

inventory comparison, as these emissions are outside the State’s span of control. 

The SCDHEC has developed a maintenance plan for the South Carolina portion of the 

nonattainment area. A copy of the South Carolina redesignation demonstration and maintenance 

plan is available upon request. A summary of the emissions for the nonattainment portion of 

York County, South Carolina is included in Section 3.3.3. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 25 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

3.3.2 Emission Inventories 

There are four different man-made emission inventory source classifications: (1) stationary point, 

(2) area, (3) on-road mobile and (4). nonroad mobile sources. 

Point sources are those stationary sources that require an air permit to operate. In general, these 

sources have a potential to emit more than 5 tons per year of a criteria pollutant or its precursors 

from a single facility. The source emissions are tabulated from data collected by direct on-site 

measurements of emissions or mass balance calculations utilizing emission factors from the 

USEPA’s AP-42 or stack test results. There are usually several emission sources for each 

facility. Emission data is collected for each point source at a facility and the data is entered into 

an in-house database system. For the projected years’ inventory, point sources are adjusted by 

growth factors based on Standard Industrial Classification codes generated using growth patterns 

obtained from County Business Patterns. For the electric generating utility sources, the 

estimated projected future year emissions were based on information provided by the utility 

company. For the sources that report to the USEPA’s Clean Air Markets Division, the actual 

2010 average summer day emissions were used. For the other Title V sources, the 2009 data was 

used which was the latest data available. For the small sources that only report emissions every 

5 years, the most recently reported data was used and assumed to be equivalent to 2009 

emissions since these sources do not vary much from year to year. The 2009 emissions data was 

grown to 2010 using the USEPA’s EGAS model. The NCDAQ believes the estimated 2010 

emissions are representative of what was emitted in 2010. 

For detailed discussion on how the point sources emission inventory was developed, see 

Appendix B.1. A summary of the point source emissions are presented in Table 3-3 and 

Table 3-4. The emissions are presented in a ton per summer day basis. 

Table 3-3. Point Source NOx Emissions (tons per day)

County 2010 2013 2016 2019 2022 

Cabarrus 0.90 0.95 1.01 1.11 1.16 

Gaston 23.48 8.58 7.75 7.92 6.02 

Iredell* 3.28 3.54 3.79 4.04 4.28 

Lincoln 0.59 0.65 0.68 0.74 0.81 

Mecklenburg 1.35 1.39 1.48 1.58 1.68 

Rowan 7.04 3.38 2.87 3.07 3.32 

Union 0.33 0.35 0.38 0.40 0.44 

Total 36.97 18.84 17.96 18.86 17.71 

*Iredell County emissions for nonattainment area only 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 26 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 3-4 Point Source VOC Emissions (tons per day)

County 2010 2013 2016 2019 2022 

Cabarrus 1.14 1.25 1.35 1.46 1.54 

Gaston 1.28 1.19 1.35 1.47 1.54 

Iredell* 0.86 0.94 1.03 1.09 1.16 

Lincoln 0.93 1.03 1.12 1.24 1.32 

Mecklenburg 3.24 3.52 3.82 4.05 4.31 

Rowan 3.72 4.08 4.48 4.87 5.25 

Union 1.36 1.49 1.61 1.72 1.85 

Total 12.53 13.50 14.76 15.90 16.97 

*Iredell County emissions for nonattainment area only 

Area sources are those stationary sources whose emissions are relatively small but due to the 

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

service stations, etc.). For area sources, emissions are estimated by multiplying an emission 

factor by some known indicator of collective activity such as production, number of employees, 

or population. These types of emissions are estimated on the county level. For the projected 

year's inventory, area source emissions are changed by population growth, projected production 

growth, or estimated employment growth. For detailed discussion on how the area source 

emission inventory was developed, see Appendix B.2. A summary of the area source emissions 

are presented in Table 3-5 and Table 3-6. The emissions are presented in a ton per summer day 

basis. 

Table 3-5. Area Source NOx Emissions (tons per day) 

County 2010 2013 2016 2019 2022 

Cabarrus 0.59 0.60 0.61 0.62 0.63 

Gaston 0.73 0.75 0.77 0.79 0.80 

Iredell* 0.20 0.20 0.20 0.20 0.20 

Lincoln 0.23 0.23 0.22 0.22 0.22 

Mecklenburg 5.25 5.31 5.37 5.44 5.50 

Rowan 0.50 0.50 0.50 0.51 0.51 

Union 0.66 0.65 0.64 0.65 0.64 

Total 8.16 8.24 8.31 8.43 8.50 

*Iredell County emissions for nonattainment area only 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 27 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 3-6. Area Source VOC Emissions (tons per day) 

County 2010 2013 2016 2019 2022 

Cabarrus 5.12 5.10 5.14 5.31 5.49 

Gaston 6.33 6.32 6.38 6.56 6.73 

Iredell* 2.06 2.14 2.19 2.27 2.35 

Lincoln 2.78 2.91 2.97 3.08 3.19 

Mecklenburg 25.76 26.26 25.82 26.47 27.18 

Rowan 4.87 5.16 5.27 5.45 5.63 

Union 8.80 9.27 9.58 10.13 10.67 

Total 55.72 57.16 57.35 59.27 61.24 

*Iredell County emissions for nonattainment area only 

For highway mobile sources, the USEPA’s Motor Vehicle Emission Simulator (MOVES) mobile 

model is run to generate emissions. The MOVES model includes the road class vehicle miles 

traveled (VMT) as an input file and can directly output the estimated emissions. For the 

projected years’ inventories, the highway mobile sources emissions are calculated by running the 

MOVES mobile model for the future year with the projected VMT to generate emissions that 

take into consideration expected Federal tailpipe standards, fleet turnover and new fuels. For 

detailed discussion on how the on-road mobile emission inventory was developed, see 

Appendix B.3. A summary of the on-road mobile source emissions are presented in Table 3-7 

and Table 3-8. The emissions are presented in a ton per summer day basis. 

Table 3-7. On-road Mobile Source NOx Emissions (tons per day)

County 2010 2013 2016 2019 2022 

Cabarrus 14.48 11.81 9.79 7.90 6.95 

Gaston 13.64 10.18 8.10 6.61 5.76 

Iredell* 8.91 7.09 5.75 4.69 4.00 

Lincoln 5.80 4.73 3.85 3.16 2.69 

Mecklenburg 69.21 52.08 41.47 33.82 32.00 

Rowan 12.96 10.06 8.03 6.41 5.46 

Union 13.26 10.97 9.44 7.90 6.81 

Total 138.26 106.92 86.43 70.49 63.67 

*Iredell County emissions for nonattainment area only 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 28 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 3-8. On-road Mobile Source VOC Emissions (tons per day)

County 2010 2013 2016 2019 2022 

Cabarrus 7.54 6.05 5.04 4.18 3.63 

Gaston 6.24 4.67 3.72 3.08 2.69 

Iredell* 5.51 4.32 3.55 2.95 2.53 

Lincoln 3.21 2.52 2.05 1.69 1.44 

Mecklenburg 30.42 22.91 18.32 15.20 13.65 

Rowan 6.32 4.82 3.84 3.10 2.60 

Union 7.46 6.03 5.06 4.27 3.67 

Total 66.70 51.32 41.58 34.47 30.21 

*Iredell County emissions for nonattainment area only 

Nonroad mobile sources, also referred to as off-road mobile sources, are equipment that can 

move but do not use the roadways, i.e., lawn mowers, construction equipment, railroad 

locomotives, aircraft, etc. The emissions from this category are calculated using the USEPA’s 

NONROAD2008a model, with the exception of the railroad locomotives and aircraft engine. 

The railroad locomotive and aircraft engine emissions are estimated by taking activity data, such 

as landings and takeoffs, and multiply by an emission factor. These emissions are also estimated 

at the county level. For the projected years’ inventories, the emissions are estimated using the 

USEPA’s NONROAD2008a model, projected landing and takeoff data for aircraft and national 

fuel use from the Energy Information Administration for locomotives. For detailed discussion 

on how the nonroad mobile emission inventory was developed, see Appendix B.4. A summary 

of the nonroad mobile source emissions are presented in Table 3-9 and Table 3-10. The 

emissions are presented in a ton per summer day basis. 

Table 3-9. Nonroad Mobile Source NOx Emissions (tons per day)

County 2010 2013 2016 2019 2022 

Cabarrus 2.87 2.39 1.93 1.59 1.38 

Gaston 2.83 2.31 1.85 1.55 1.36 

Iredell* 0.90 0.74 0.58 0.47 0.40 

Lincoln 1.20 1.00 0.82 0.68 0.60 

Mecklenburg 25.38 22.93 20.33 18.69 17.88 

Rowan 2.52 2.15 1.80 1.55 1.38 

Union 5.35 4.52 3.68 3.05 2.61 

Total 41.05 36.04 30.99 27.58 25.61 

*Iredell County emissions for nonattainment area only 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 29 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 3-10. Nonroad Mobile Source VOC Emissions (tons per day)

County 2010 2013 2016 2019 2022 

Cabarrus 1.73 1.41 1.25 1.23 1.25 

Gaston 1.92 1.54 1.31 1.23 1.22 

Iredell* 0.62 0.50 0.42 0.38 0.36 

Lincoln 0.94 0.77 0.66 0.59 0.57 

Mecklenburg 16.20 13.63 12.33 12.14 12.37 

Rowan 1.89 1.58 1.33 1.18 1.12 

Union 3.11 2.60 2.33 2.27 2.29 

Total 26.41 22.03 19.63 19.02 19.18 

*Iredell County emissions for nonattainment area only 

3.3.3 Summary of Emissions 

The sum totals of the man-made emissions for the Metrolina nonattainment area are tabulated in 

Tables 3-11 though 3-14. The emission summaries for York County, South Carolina came from 

the SCDHEC redesignation demonstration and maintenance plan. 

Table 3-11 Total Man-Made NOx Emissions for the North Carolina Portion of the 

Metrolina Nonattainment Area (tons/day) 

County 2010 2013 2016 2019 2022 

Cabarrus 18.84 15.75 13.34 11.22 10.12 

Gaston 40.68 21.82 18.47 16.87 13.94 

Iredell* 13.29 11.57 10.32 9.40 8.88 

Lincoln 7.82 6.61 5.57 4.80 4.32 

Mecklenburg 101.19 81.71 68.65 59.53 57.06 

Rowan 23.02 16.09 13.20 11.54 10.67 

Union 19.60 16.49 14.14 12.00 10.50 

Total 224.44 170.04 143.69 125.36 115.49 

* Iredell County emissions for nonattainment area only. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 30 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 3-12 Total Man-Made VOC Emissions for the North Carolina Portion of the 

Metrolina Nonattainment Area (tons/day) 

County 2010 2013 2016 2019 2022 

Cabarrus 15.53 13.81 12.78 12.18 11.91 

Gaston 15.77 13.72 12.76 12.34 12.18 

Iredell* 9.05 7.90 7.19 6.69 6.40 

Lincoln 7.86 7.23 6.80 6.60 6.52 

Mecklenburg 75.62 66.32 60.29 57.86 57.51 

Rowan 16.80 15.64 14.92 14.60 14.60 

Union 20.73 19.39 18.58 18.39 18.48 

Total 161.36 144.01 133.32 128.66 127.60 

* Iredell County emissions for nonattainment area only. 

Table 3-13 Total Man-Made NOx Emissions for South Carolina Portion of the 

Metrolina Nonattainment Area – York County, South Carolina (tons/day) 

County 2010 2013 2016 2019 2022 

Point 4.54 4.64 4.91 5.19 5.48 

Area 1.17 1.22 1.27 1.32 1.36 

On-Road Mobile 12.05 8.73 6.52 5.16 4.42 

Nonroad Mobile 3.21 2.69 2.17 1.82 1.60 

Total 20.97 17.28 14.87 13.49 12.86 

* York County emissions for nonattainment area only. 

Table 3-13 Total Man-Made VOC Emissions for South Carolina Portion of the 

Metrolina Nonattainment Area – York County, South Carolina (tons/day) 

County 2010 2013 2016 2019 2022 

Point 2.07 2.06 2.20 2.34 2.49 

Area 7.16 7.39 7.57 7.70 7.83 

On-Road Mobile 3.92 3.14 2.61 2.29 2.14 

Nonroad Mobile 2.15 1.78 1.54 1.44 1.41 

Total 15.30 14.37 13.92 13.77 13.87 

* York County emissions for nonattainment area only. 

3.3.4 Maintenance Demonstration 

As discussed above, maintenance is demonstrated when the future years total man-made 

emissions are less than the 2010 baseline emissions. The following tables summarize the VOC 

and NOx emissions for the entire Metrolina nonattainment area and the North Carolina portion, 

respectively. The difference between the base year and the final year for both scenarios 

illustrates that the continued maintenance of the 1997 8-hour ozone NAAQS is expected. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 31 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 3-14 Maintenance Demonstration for Metrolina Nonattainment Area 

Year NOx (tons/day) VOC (tons/day) 

2010 245.41 176.66 

2013 187.32 158.38 

2016 158.56 147.24 

2019 138.85 142.43 

2022 128.35 141.47 

Difference from 

2010 to 2022 -117.06 -35.19 

Table 3-14 Maintenance Demonstration for North Carolina Portion of the 

Metrolina Nonattainment Area 

Year NOx (tons/day) VOC (tons/day) 

2010 224.44 161.36 

2013 170.04 144.01 

2016 143.69 133.32 

2019 125.36 128.66 

2022 115.49 127.60 

Difference from 

2010 to 2022 -108.95 -33.76 

The difference between the attainment level of emissions (2010) from all man-made sources and 

the projected level of emissions from all man-made sources in the nonattainment area is 

considered the “safety margin”. The safety margin for each projected year is listed below in 

Table 3-15. The safety margin for the North Carolina portion of the nonattainment area is 

summarized in Table 3-16. 

Table 3-15 Safety Margin for Metrolina Nonattainment Area 

Year NOx TPD VOC TPD 

2010 N/A N/A 

2013 -58.09 -18.28 

2016 -86.85 -29.42 

2019 -106.56 -34.23 

2022 -117.06 -35.19 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 32 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 3-16 Safety Margin for North Carolina Portion of the 

Metrolina Nonattainment Area 

Year NOx TPD VOC TPD 

2010 N/A N/A 

2013 -54.40 -17.35 

2016 -80.75 -28.04 

2019 -99.08 -32.70 

2022 -108.95 -33.76 

3.4 CONTINGENCY PLAN 

3.4.1 Overview 

The two main elements of the North Carolina contingency plan are tracking and triggering 

mechanisms to determine when contingency measures are needed and a process of developing 

and adopting appropriate control measures. There will be three potential triggers for the 

contingency plan. The primary trigger of the contingency plan will be a violation of the 1997 8-

hour ozone NAAQS at any of the Metrolina area monitors. The secondary trigger will be a 

monitored air quality pattern that suggests an actual 1997 8-hour ozone NAAQS violation may 

be imminent. The tertiary trigger will be a monitored fourth high exceedance of the NAAQS. 

Upon either the primary or secondary triggers being activated, the NCDAQ, working in 

consultation with the SCDHEC and the Mecklenburg County Air Quality (MCAQ) local 

program, will commence analyses to determine what additional measures, if any, will be 

necessary to attain or maintain the 1997 8-hour ozone standard. If activation of either the 

primary or secondary triggers occurs, this plan provides a regulatory adoption process for 

revising emission control strategies. Activation of the tertiary trigger will result in an analysis to 

understand the cause of the exceedance and to identify voluntary measures if needed. 

In addition, there will be a tracking mechanism that requires a comparison of the actual 

emissions inventory submitted under the Consolidated Emissions Reporting Rule (CERR) and 

Air Emission Reporting Rule (AERR) to the projected inventory, and to the attainment year 

inventory contained in this maintenance plan. The CERR and AERR reporting years are within a 

year of the baseline, interim and final years of the emission inventory in this maintenance 

demonstration. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 33 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

3.4.2 Primary and Secondary Triggers 

The primary trigger of the contingency plan will be a violation of the 1997 8-hour ozone 

standard, or when the three-year average of the 4th highest values is equal to or greater than 0.085 

ppm at a monitor in the Metrolina nonattainment area. The trigger date will be 60 days from the 

date that the State observes a 4th highest value that, when averaged with the two previous ozone 

seasons’ fourth highest values, would result in a three-year average equal to or greater than 0.085 

ppm. 

The secondary trigger will apply where no actual violation of the 1997 8-hour ozone standard 

has occurred, but where the State finds monitored ozone levels indicating that an actual ozone 

NAAQS violation may be imminent. A pattern will be deemed to exist when there are two 

consecutive ozone seasons in which the 4th highest values are 0.085 ppm or greater at a single 

monitor within the Metrolina nonattainment area. The trigger date will be 60 days from the date 

that the State observes a 4th highest value of 0.085 ppm or greater at a monitor for which the 

previous season had a 4th highest value of 0.085 ppm or greater. 

Similarly, the tertiary trigger will not be an actual violation of the 1997 8-hour ozone standard. 

This trigger will be a first alert as to a potential air quality problem on the horizon. The trigger 

will be activated when a monitor in the Metrolina nonattainment area has a 4th highest value of 

0.085 ppm or greater, starting the first year after the maintenance plan has been approved. The 

trigger date will be 60 days from the date that the State observes a 4th highest value of 0.085 ppm 

or greater at any monitor. 

3.4.3 Action Resulting From Trigger Activation 

Once the primary or secondary trigger is activated, the Planning Section of the NCDAQ, in 

consultation with the SCDHEC and MCAQ, shall commence analyses including trajectory 

analyses of high ozone days, and emissions inventory assessment to determine those emission 

control measures that will be required for attaining or maintaining the 1997 8-hour ozone 

standard. By May 1 of the year following the ozone season in which the primary or secondary 

trigger has been activated, North Carolina will complete sufficient analyses to begin adoption of 

necessary rules for ensuring attainment and maintenance of the 1997 8-hour ozone NAAQS. 

The rules would become State effective by the following January 1, unless legislative review is 

required. 

The measures that will be considered for adoption upon a trigger of the contingency plan 

include: NOx Reasonably Available Control Technology on stationary sources with a potential 

to emit less than 100 tons per year in the North Carolina portion of the Metrolina nonattainment 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 34 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

area, diesel inspection and maintenance program, implementation of diesel retrofit programs, 

including incentives for performing retrofits, and additional controls in upwind areas. 

The NCDAQ commits to implement within 24 months of a primary or secondary trigger, or as 

expeditiously as practicable, at least one of the control measures listed above or other 

contingency measures that may be determined to be more appropriate based on the analyses 

performed. 

Once the tertiary trigger is activated, the Planning Section of the NCDAQ, in consultation with 

the SCDHEC and MCAQ, shall commence analyses including meteorological evaluation, 

trajectory analyses of high ozone days, and emissions inventory assessment to understand why a 

4th highest exceedance of the standard has occurred. Once the analyses are completed, the 

NCDAQ will work with SCDHEC, MCAQ and the local air awareness program to develop an 

outreach plan identifying any additional voluntary measures that can be implemented. If the 4th

highest exceedance occurs early in the season, the NCDAQ will work with entities identified in 

the outreach plan to determine if the measures can be implemented during the current season, 

otherwise, NCDAQ will work with SCDHEC, MCAQ and the local air awareness coordinator to 

implement the plan for the following ozone season. 

3.4.4 Tracking Program for Ongoing Maintenance 

In addition to the measures listed above, emissions inventory comparisons will be carried out. 

The large stationary sources are required to submit an emissions inventory annually to the 

NCDAQ or MCAQ. The NCDAQ will commit to review these emissions inventories to 

determine if an unexpected growth in NOx emissions in the Metrolina area may endanger the 

maintenance of the 1997 8-hour ozone standard. Additionally, as new VMT data is provided by 

the North Carolina Department of Transportation (NCDOT), the NCDAQ commits to review this 

data and determine if any unexpected growth in VMT may endanger the maintenance of the 

1997 8-hour ozone standard. 

Additionally, under the CERR and AERR the NCDAQ is required to develop a comprehensive, 

annual, statewide emissions inventory every three years and is due twelve to eighteen months 

after the completion of the inventory year. The CERR and AERR inventory years are within a 

year of the baseline, interim and final years of the maintenance plan. Therefore, the NCDAQ 

commits to compare the CERR and AERR inventories as they are developed with the 

maintenance plan to determine if additional steps are necessary for continued maintenance of the 

1997 8-hour ozone standard in this area. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 35 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

4.0 MOTOR VEHICLE EMISSIONS BUDGET FOR CONFORMITY 

4.1 TRANSPORTATION CONFORMITY 

The purpose of transportation conformity is to ensure that Federal transportation actions 

occurring in nonattainment and maintenance areas do not hinder the area from attaining and 

maintaining the 1997 8-hour ozone standard. This means that the level of emissions estimated 

by the NCDOT or the metropolitan planning organizations for the Transportation 

Implementation Plan (TIP) and Long Range Transportation Plan must not exceed the motor 

vehicle emission budgets (MVEBs) as defined in this maintenance plan. 

Through the interagency consultation process, there was discussion on the years to set MVEBs 

for the Metrolina maintenance plan. According to Section 93.118 of the transportation 

conformity rule, a maintenance plan must establish MVEBs for the last year of the maintenance 

plan (in this case, 2022). The consensus during the interagency consultation process was that 

another MVEB should be set for the year 2013 in the Metrolina maintenance plan. 

4.2 SAFETY MARGIN 

As stated in Section 3.3.4, a safety margin is the difference between the attainment level of 

emissions from all source categories (i.e., point, area, on-road and nonroad mobile) and the 

projected level of emissions from all source categories. The safety margins for the North 

Carolina portion of the Metrolina nonattainment area are listed in Table 3-16 above. The State 

may choose to allocate some of the safety margin to the MVEB, for transportation conformity 

purposes, so long as the total level of emissions from all source categories remains below the 

attainment level of emissions. 

The NCDAQ has decided to allocate a portion of the safety margin to the MVEB to allow for 

unanticipated growth in VMT, changes and uncertainty in vehicle mix assumptions, etc. that will 

influence the emission estimations. The NCDAQ has developed and implemented a four-step 

approach for determining a factor to use to calculate the amount of safety margin to apply to the 

MVEB and it is outlined in Appendix B.3. The percent increase to the MVEBs for the North 

Carolina counties in the Metrolina nonattainment area are listed in the table below. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 36 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 4-1 Percent Increase To Mobile Vehicle Emissions Budget 

County 2013 2022 

Cabarrus 10% 20% 

Gaston 10% 20% 

Iredell 12% 22% 

Lincoln 12% 22% 

Mecklenburg 7% 17% 

Rowan 10% 20% 

Union 10% 20% 

4.3 MOTOR VEHICLE EMISSION BUDGETS 

Although the emissions up to this point have been 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 so that the 

MVEBs will be defined in a smaller unit of measurement. Additionally, in past conformity 

determinations there have been concerns with how the tons per day MVEBs were rounded to the 

hundredth place. Setting the MVEBs in kilograms per day will avoid these concerns in future 

conformity determinations. The MOVES model reports emissions out several decimal places 

and for this plan the emissions have been rounded to the second decimal place. The conversion 

to kilograms used the actual emissions reported in the MOVES model. The conversion was done 

utilizing the “CONVERT” function in an EXCEL spreadsheet. 

The tables below shows the counties with their highway mobile NOx and VOC emissions 

expressed in tons per day and the corresponding kilograms per day values for 2013 and 2022. 

Table 4-2 Highway Mobile Source NOx Emissions North Carolina Portion of the 

Metrolina Nonattainment Area 

County 2013 2022 

Tons/day Kg/day Tons/day Kg/day 

Cabarrus 11.81 10,711 6.95 6,303 

Gaston 10.18 9,235 5.76 5,229 

Iredell* 7.09 6,433 4.00 3,626 

Lincoln 4.73 4,289 2.69 2,439 

Mecklenburg 52.08 47,243 32.00 29,033 

Rowan 10.06 9,127 5.46 4,955 

Union 10.97 9,955 6.81 6,174 

Total 106.92 96,993 63.67 57,759 

*Iredell County emissions for nonattainment area only. 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 37 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

Table 4-3 Highway Mobile Source VOC Emissions North Carolina Portion of the 

Metrolina Nonattainment Area 

County 2013 2022 

Tons/day Kg/day Tons/day Kg/day 

Cabarrus 6.05 5,491 3.63 3,297 

Gaston 4.67 4,240 2.69 2,437 

Iredell* 4.32 3,920 2.53 2,298 

Lincoln 2.52 2,282 1.44 1,306 

Mecklenburg 22.91 20,783 13.66 12,387 

Rowan 4.82 4,372 2.60 2,363 

Union 6.03 5,467 3.67 3,326 

Total 51.32 46,555 30.22 27,414 

*Iredell County emissions for nonattainment area only. 

As part of the consultation process on setting MVEBs, the NCDAQ discussed several options for 

setting the geographic extent of the MVEBs with the transportation partners. The NCDAQ 

requested feedback on these options or other alternatives for consideration from the 

transportation partners. The NCDAQ received feedback from only two of the transportation 

partners. Therefore, as part of the public comment process, the NCDAQ provided several 

options for establishing the MVEBs. The options included: 

• Option A – county level MVEBs; 

• Option B – MVEBs set as grouped counties based on counties that contain a Metropolitan 

Planning Organization (MPO) and/or Rural Planning Organization (RPO) and a 

sub-MPO budget for Mecklenburg County; 

• Option C – MVEBs set as grouped counties based on counties that contain a Metropolitan 

Planning Organization (MPO) and/or Rural Planning Organization (RPO); 

• Option D – MVEBs set for Cabarrus Rowan MPO (CRMPO), one MVEB for the 

remaining MPOs and RPOs and a sub-MPO budget for Mecklenburg County. 

During the public comment period, comments regarding geographical extent for the MVEBs 

were received from the USEPA, CRMPO and the Mecklenburg Union MPO (MUMPO). The 

USEPA preferred Option A and CRMPO preferred Options B or C. MUMPO requested that 

Mecklenburg County not have separate sub-MPO budget, that county level MVEBs not be set 

and that NCDAQ consider an alternative option similar to Option D without the sub-MPO 

budget for Mecklenburg County. 

After considering the comments received, the NCDAQ has chosen to establish MVEBs based on 

Option C. This option is consistent with the CRMPO request and takes into consideration two of 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 38 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

the comments from MUMPO. The NCDAQ believes that this option is a good compromise 

between how MVEBs have been established in the past, addressing the NCDAQ’s concern with 

Mecklenburg County’s on-road mobile source emissions and the preferences of the 

transportation partners. Further, the NCDAQ believes this approach provides additional 

flexibility to the transportation partners while providing adequate assurance that the ozone 

standard will be maintained in the region. 

Therefore, MVEBs are set for the CRMPO (Cabarrus and Rowan Counties), for the Gaston 

Urban Area MPO and Lake Norman RPO (Gaston, Iredell, and Lincoln Counties), and for the 

MUMPO and Rocky River RPO (Mecklenburg and Union Counties). Tables 4-4 through 4-6 

below provide the NOx and VOC MVEBs in kilograms per day, for transportation conformity 

purposes, for 2013 and 2022. Upon the USEPA’s affirmative adequacy finding for these subarea MVEBs, they will become the applicable MVEBs for transportation conformity. 

Table 4-4 Cabarrus-Rowan MPO MVEB in kilograms per day 

2013 2022 

NOx VOC NOx VOC 

Base Emissions 19,838 9,863 11,258 5,660 

Safety Margin Allocated to 

MVEB 1,984 986 2,252 1,132 

Conformity MVEB 21,822 10,849 13,510 6,792 

 Includes all of Cabarrus and Rowan Counties 

Table 4-5 Gaston Urban Area MPO/Lake Norman RPO MVEB in kilograms per day 

2013 2022 

NOx VOC NOx VOC 

Base Emissions 19,957 10,442 11,294 6,041 

Safety Margin Allocated to 

MVEB 2,211 1,168 2,381 1,280 

Conformity MVEB 22,168 11,610 13,675 7,321 

 Includes all of Gaston and Lincoln Counties and the nonattainment area of Iredell Co 

Table 4-6 Mecklenburg-Union MPO/Rocky River RPO MVEB in kilograms per day 

2013 2022 

NOx VOC NOx VOC 

Base Emissions 57,198 26,250 35,207 15,713 

Safety Margin Allocated to 

MVEB 4,303 2,002 6,171 2,771 

Conformity MVEB 61,501 28,252 41,378 18,484 

 Includes all of Mecklenburg and Union Counties 
Charlotte-Gastonia-Rock Hill, NC-SC 1997 8-Hour Ozone Nonattainment Area 39 

Redesignation Demonstration and Maintenance Plan November 2, 2011 

New Safety Margins

A total of 8,498 kg/day (9.37 tons/day) and 10,804 kg/day (11.91 tons/day) of 2013 and 2022 

NOx safety margin, respectively, were added to the MVEB for the Metrolina area. A total of 

4,156 kg/day (4.58 tons/day) and 5,183 kg/day (5.71 tons/day) of the 2013 and 2022 VOC safety 

margin, respectively, were added to the MVEB for the Metrolina area. The revised safety 

margins, which take into consideration the portion of the safety margin applied to the MVEB, for 

each projected year is listed below in Table 4-23. 

Table 4-23 New Safety Margins for the North Carolina Portion of the 

Metrolina Nonattainment Area 

Year NOx TPD VOC TPD 

2010 N/A N/A 

2013 -45.03 -12.77 

2016 -80.75 -28.04 

2019 -99.08 -32.70 

2022 -97.04 -28.05 
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5.0 STATE IMPLEMENTATION PLAN APPROVAL 

5.1 INTRODUCTION 

For an area to be redesignated and have an approved maintenance plan, the SIP must include 

evidence of compliance with the rules relied on to show maintenance of the standard. This 

section provides the evidence of compliance with such rules for the Charlotte-Gastonia-Rock 

Hill 1997 8-hour ozone nonattainment area.

5.2 EVIDENCE OF COMPLIANCE 

Two counties in the Metrolina area (Gaston and Mecklenburg Counties) were designated as 

moderate nonattainment for 1-hour ozone effective January 1992. Since a redesignation 

demonstration and maintenance plan was submitted for this area prior to November 15, 1992, the 

CAA requirements for moderate areas were not required with the exception of the inspection and 

maintenance program. An inspection and maintenance program was established in the Metrolina 

area as prescribed by the 1990 CAA. Therefore, North Carolina has a fully approved SIP for this 

area. 

For the 1997 8-hour ozone standard, the NCDAQ submitted to the USEPA for approval the 

Metrolina Attainment Demonstration SIP on June 15, 2007 and a Supplement to the Attainment 

Demonstration SIP on April 5, 2010. The Reasonable Further Progress (RFP) SIP was submitted 

to the USEPA for approval on June 15, 2007 and a Revised RFP SIP was submitted on 

November 30, 2009. 

Additionally, the following rules regulating emissions of VOCs and/or NOx in Metrolina 

nonattainment area counties have been approved, or have been submitted with a request to be 

approved, as part of the SIP: 

15A NCAC 2D .0958, Work Practices For Sources of Volatile Organic Compounds, 

15A NCAC 2D .0530, Prevention of Significant Deterioration, 

15A NCAC 2D .0925, Petroleum Liquid Storage in Fixed Roof Tanks, 

15A NCAC 2D .0926, Bulk Gasoline Plants, 

15A NCAC 2D .0927, Bulk Gasoline Terminals, 

15A NCAC 2D .0928, Gasoline Service Stations Stage I, 

15A NCAC 2D .0932, Gasoline Truck Tanks and Vapor Collection Systems, 

15A NCAC 2D .0933 Petroleum Liquid Storage in External Floating Roof Tanks 

15A NCAC 2D .1000, Motor Vehicle Emission Control Standards. 

15A NCAC 2D .1200, Control and Emissions from Incinerators 

15A NCAC 2D .1409(b), Stationary Internal Combustion Engines 

15A NCAC 2D .1416 - .1423, NOx SIP rules 
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15A NCAC 2D .1600, General Conformity 

15A NCAC 2D .1700, Municipal Solid Waste Landfills, and 

 15A NCAC 2D .1900, Open Burning 

 15A NCAC 2D .2000, Transportation Conformity 

15A NCAC 2D .2400 Clean Air Interstate Rules 

Rules 15A NCAC 2D .0925, .0926, .0927, .0928, .0932, .0933, .0948, .0949, and .0958 have 

been approved as part of the SIP and are applicable across the state regardless of the size of the 

source. 

Section 15A NCAC 2D .1000 also regulates emissions from motor vehicles in the North 

Carolina counties in and around the Metrolina nonattainment area and requires the use of the on 

board diagnostic system, which will indicate NOx emissions as well as other pollutants. 

Section 15A NCAC 2D .1200 regulates the controls and emissions from incinerators. Part of this 

rule has been submitted as part of the SIP, while .1205, .1206 and .1210 are part of the CAA 

Section 111(d) plans. 

Two rules are conformity related, 15A NCAC 2D .1600 and .2000. General conformity related 

projects are covered under Section .1600, while transportation conformity related projects are 

covered under Section .2000. Although neither of these rules require reduction in emissions, they 

do ensure that federal actions do not hinder attainment or maintenance of the NAAQS. 

North Carolina has adopted an open burning rule, 15A NCAC 2D .1900, that prohibits open 

burning of vegetative material during Air Quality Action Days of Code Orange or higher in 

forecasted areas of the State. Ozone forecasts are issued for the Raleigh-Durham-Chapel Hill 

area from May 1st through September 30th, therefore this area is covered by this rule. 

Section 15A NCAC 2D .2400 regulates nitrogen oxide emissions from electric generating units 

with a nameplate capacity of 25 megawatts or more producing electricity for sale. Section 15A 

NCAC 2D .2400 also covers industrial boilers that are covered under the NOx SIP rules. This 

Section replaces the NOx SIP rules beginning January 1, 2009. Although North Carolina did not 

rely on the emission reductions from CAIR for maintenance of the 1997 8-hour ozone standard, 

these regulations will result in additional reductions in NOx emissions regionally. 

Another important set of rules that control volatile organic compound emissions in these counties 

is Section 15A NCAC 2D .1100, Control of Toxic Air Pollutants. These rules, however, have 

not been submitted to the USEPA to be approved as part of the SIP. 
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There are two other rules that control emissions of volatile organic compounds in these areas. 

They are 15A NCAC 2D .0524, New Source Performance Standards, and 2D.1110, National 

Emission Standards for Hazardous Air Pollutants. Also, rule 2D.1111, Maximum Achievable 

Control Technology applies to control of emissions of volatile organic compounds. They are not 

part of the SIP, but the USEPA has delegated the State enforcement authority for standards that 

have been adopted by the State. (The standards adopted by the State are state-enforceable 

regardless of the USEPA delegation.) 
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6.0 STATE COMPLIANCE WITH CLEAN AIR ACT REQUIREMENTS 

Section 107(d)(3)(E)(v) of the CAA requires that the provisions of Section 110 and part D of the 

Act be met within the area to be redesignated. This means that North Carolina must meet all 

requirements, if any, that had come due as of the date of the redesignation request. 

The USEPA, in its latest guidance on redesignation requirements (as contained in a 

memorandum from John Calcagni, Director, Air Quality Management Division, Office of Air 

Quality Planning and Standards to the USEPA Regional Offices dated September 4, 1992, see 

Appendix A), states that "For the purposes of redesignation, a State must meet all requirements 

of Section 110 and Part D that were applicable prior to submittal of the complete redesignation 

request. When evaluating a redesignation request, Regions should not consider whether the State 

has met requirements that come due under the Act after submittal of a complete redesignation 

request." 

Monitoring is one of the requirements of Section 110. The NCDAQ commits to continue 

operating the current ozone monitors in the North Carolina portion of the Metrolina 1997 8-hour 

ozone nonattainment area, providing sufficient funding is available for continued operation. Any 

monitor shutdowns or relocations will only be made with the approval of USEPA. No plans are 

underway to discontinue operation, relocation or otherwise affect the integrity of the ambient 

monitoring network in place. The current monitors are operated consistent with 40 CFR Part 58 

and any changes will only be made if they are consistent with 40 CFR Part 58. 

The NCDAQ has submitted to the USEPA for adoption into the SIP: an attainment 

demonstration SIP; a reasonable further progress SIP; and a reasonable available control 

technology SIP. The NCDAQ believes that North Carolina has met all of the requirements of 

Section 110 and Part D. 
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7.0 CONCLUSION 

The most recent three years of ozone monitoring data for the Charlotte-Gastonia-Rock Hill 

nonattainment area demonstrate compliance with the NAAQS for 1997 8-hour ozone. Since the 

1990’s, there have been many major programs enacted in North Carolina that have led to 

significant actual, enforceable emissions reductions, which have led to improvements in the air 

quality in the Metrolina area. Additionally, the maintenance plan demonstrates that the projected 

emissions inventories for 2022, the final year of the maintenance plan and ten years beyond the 

expected redesignation year, as well as the interim years, are all less than the base year emissions 

inventory. Therefore, maintenance of the 1997 8-hour ozone NAAQS has also been 

demonstrated. 

This redesignation demonstration and maintenance plan has been prepared to meet the 

requirements of the 1990 Clean Air Act Amendments.