## Supplement to the North Carolina

8-Hour Ozone Attainment Demonstration

for the Charlotte-Gastonia-Rock Hill, NC-SC

8-Hour Ozone Nonattainment Area (Cabarrus, Gaston, Lincoln, Mecklenburg, Rowan, Union Counties and Coddle Creek and Davidson Townships in Iredell County)

Prepared by:

North Carolina Department of Environment and Natural Resources Division of Air Quality

April 5, 2010(This page intentionally left blank)Supplement to the Attainment Demonstration for the i Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 

### PREFACE This document contains a supplement to the No rth Carolina attainment demonstration for the Charlotte-Gastonia-Rock Hill, North Carolina-S outh Carolina 8-hour ozone nonattainment area that was submitted to the United States Environmental Protection Agency on June 15, 2007. This supplement in combination with the June 15, 2007, submittal demonstrates that this area will meet the National Ambient Ai r Quality Standard for 8-hour ozone by June 15, 2011. This area includes the entire c ounties of Cabarrus, Gaston, Lincoln, Mecklenburg, Rowan and Union; Coddle Creek and Davidson Townships in Iredel l County; and the Rock Hill Metropolitan Planning Organization boundary in York County, South Carolina.Supplement to the Attainment Demonstration for the ii Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 TABLE OF CONTENTS

PREFACE i

1.0 INTRODUCTION 1
2.0 AMBIENT AIR QUALITY DATA 3

3.0 WEIGHT OF EVIDENCE MODELING 8 3.1 Emission Inventory a nd Controls Applied ........................................................................... 8 3.1.1 Stationary Point Sources ............................................................................................... 9 3.1.2 Stationary Area Sources .............................................................................................. 1 0 3.1.3 Off-Road Mobile Sources ........................................................................................... 10 3.1.4 Highway Mobile Sources ............................................................................................ 11 3.1.5 Biogenic Emission Sources ......................................................................................... 11 3.1.6 Controls Applied in 2011 Modeling ........................................................................... 11 3.2 Modeling Results ......................................................................................................... ...... 13 3.2.1 Attainment Test Introduction ...................................................................................... 13 3.2.2 2011 Modeling Results .................................................................................................. . 14

4.0 MOTOR VEHICLE EMISSION BUDGETS 15
5.0 Summary 17

LIST OF TABLES Table 2-1 Design Values (ppm) for the North Carolina Monitors in the Metrolina Area ............. 3 Table 2-2 Predicted 2009 Design Values Compared to Actual 2009 Design Values .................... 4 Table 2-3 Fourth Highest 8-hour Ozone Values ............................................................................ 4 Table 2-4 Utility NOx Emission Reductions since 2006 Ozone Season ....................................... 7
Table 5.2-2 Attainment Test Results for 2011 ............................................................................. 15 Table 4-1 2009 Highway Mobile Source Emi ssions Metrolina Nonattainment Area ................. 16 Table 4-2 County Level MVEB for 2009 .................................................................................... 17

LIST OF FIGURES

Figure 1-1 Monitor locations in the Metrolina area ....................................................................... 1 Figure 2-1 Number of Stagnation Days versus Exceedance Days ................................................. 5 Figure 2-2 Average High Temperatur es versus Exceedance Days ................................................. 6 Figure 2-3 Location and size of the Duke Ener gy facilities located in the vicinity of the Metrolina nonattainment area .................................................................................................. ....... 7Supplement to the Attainment Demonstration for the iii Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 LIST OF APPENDICES

Appendix A: Memorandums

Appendix B: Emissions Inventory Summary

Appendix C: Emissions Inventory Documentation

Appendix D: Attainment Test Results

Appendix E: VISTAS Supporting Documentation

Appendix F Public Notice Report, Comments Received and ResponsesSupplement to the Attainment Demonstration for the iv Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 (This page intentionally left blank)Supplement to the Attainment Demonstration for the 1 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 

### 1.0 INTRODUCTION On April 15, 2004, the United States Environmen tal Protection Agency (USEPA) designated areas as nonattainment for the 1997 8-hour oz one National Ambient Air Quality Standard (NAAQS) based upon air quality monitoring data measured during the 2001, 2002 and 2003 ozone seasons. These designations became effective on June 15, 2004.

The Charlotte-Gastonia-Rock Hill, North Carolina- South Carolina (referred to as the Metrolina area) 8-hour ozone nonattainment area was designat ed as a Moderate area, with a regional 2001- 2003 8-hour ozone design value of 0.100 ppm. This nonattainment area includes the entire counties of Cabarrus, Gaston, Lincoln, Meckle nburg, Rowan and Union; Coddle Creek and Davidson Townships in Iredell County; and the Rock Hill Metropolitan Planning Organization boundary in York County, South Carolina.

Figure 1-1 displays where the monitors are loca ted in the counties affected by the Metrolina nonattainment designation.

Figure 1-1 Monitor locations in the Metrolina area

The attainment date for a Moderate area is June 15, 2010, with an attainme nt demonstration State Implementation Plan (SIP) submittal date of J une 15, 2007. The North Carolina Division of Air Quality (NCDAQ) submitted an attainment demonstration SIP on June 15, 2007, which demonstrated that the Metrolina nonattainment area would attain the st andard by the end of 2009.Supplement to the Attainment Demonstration for the 2 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 The USEPA notified North Carolin a in a letter dated November 17, 2008, that they planned to disapprove the Metrolina attainment demonstr ation SIP unless North Carolina requested a voluntary reclassification to Serious. In that le tter, the USEPA stated “Because we are now so close to the attainment date, we now believe that attainment will not be achieved by the required moderate area deadline based on the air quality measurements from th e summers of 2007 and 2008 that exceed the standard by a sizable amount. Furthermore, we belie ve that the area will not meet the requirements for a one-year extensio n of the attainment date.” A copy of this correspondence can be found in Appendix A.

Before responding to the Novemb er 17, 2008, letter, North Caroli na thoroughly considered the two most apparent options: the proposed disapproval of the a ttainment demonstration SIP and the voluntary reclassification to Serious. Both options presented rather negative consequences for the State. While the USEPA believed that it was unlikely that the Metrolina area would attain the 1997 ozone standard by its attainment date, North Caro lina believed that the region could meet the requirement for requesting a one-y ear extension if the attainment date was not met and believed that disapproval of the atta inment demonstration SIP was premature.

Many of the control requirements in the Cl ean Air Act Amendments (CAAA) for a Serious nonattainment area focus on reducing Volatile Organic Compound (VOC) emissions. For example, stationary sources with potential annual VOC emissions greater than 50 tons per year must implement reasonably available control technology or RACT. Th e Metrolina region is nitrogen oxide (NOx) limited, so reductions in VOC emissions will not result in the reductions in ozone needed to meet the standard. Therefore, the NCDAQ did not wish to request a voluntary reclassification of the Metrolina area to Serious when there was still a chance that the area would be eligible to request a one-year extension of the attainment date . North Carolina believed that in these difficult economic times, it was unreason able for the State to require business and industry to go through a resource intensive and burdensome process and implement costly VOC controls when lower ozone levels would not be achieved as a result of that exercise.

Therefore, on December 19, 2008, North Caro lina responded to the USEPA letter (see Appendix A) by withdrawing the attainment demonstration SIP submitted in 2007 and by committing to submit a revised SIP by November 30, 2009. In August 2009, the NCDAQ shared an internal draft of the revised attainment demonstration with the USEPA and the transportation partners for comment. The NCDA Q learned at the end of the comment period that the USEPA had issues with the attainment year as proposed in the revised SIP being 2011.

By the time the NCDAQ learned of the USEPA’s c oncerns, the majority of the ozone season was over. Although the Metrolina area did not have a design value below the 1997 8-hour ozone standard for the three-year pe riod including the 2009 data, the ar ea did have clean data for 2009; i.e., the fourth highest values at all of the monitors were below the 1997 ozone standard. The CAAA allows the USEPA to extend the attainment date for one year even if the area has a 3-year design value above the standard for the attainment year, provided certain ot her conditions exist. The conditions for the extension are that an area has clean data in the designated attainment year and that the State has complied with all requi rements and commitments in its implementation plan. With clean data for 2009, the area qualifies fo r a one-year extension of the attainment date once the attainment dem onstration is deemed co mplete by the USEPA.Supplement to the Attainment Demonstration for the 3 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 The USEPA discussed internally various options of what the NCDAQ could submit that would address their concerns with the 2011 attainment date. On November 4, 2009, the NCDAQ was given two options to consider:

• Option 1 - The State could re-submit the orig inal attainment demonstration and then submit supplemental information. The supplem ental information would include the 2009 ambient air quality data showing the area qua lifies for a one-year ex tension and the 2011 modeling as weight of evidence that the Metr olina region would atta in the standard by June 15, 2011.

• Option 2 - The State could use the origin al 2009 modeling and the revised 2011 modeling to develop a plan to demonstrate the area would attain the standard by June 15, 2011.

The NCDAQ chose Option 1, and on November 12, 2009, the agency re-submitted the attainment demonstration SIP for the Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area to the USEPA. This doc ument is a supplement to the June 15, 2007 submittal which addresses the additional weight of evidence. This supplement in combination with the June 2007 attainment demonstration SI P submission are what is necessary for the USEPA to deem the attainment demonstration complete.



### 2.0 AMBIENT AIR QUALITY DATA Since the 8-hour ozone designation for the Metro lina area, the 8-hour ozone design values have improved significantly. The 2001-2003 design value pe riod had values as high as 0.100 parts per million (ppm) and six out of the seven North Carolina monitors in the area were violating the NAAQS. Since the 2001-2003 period, the design valu es and the number of violating monitors in the region has decreased. With the latest de sign value period, 2007-2009, th e highest monitor in the area has a value of 0.086 ppm and only that monitor exceeds the NAAQS (See Table 2-1). A design value of 0.084 ppm would be considered to be in attainment with the 1997 8-hour ozone standard.

Table 2-1 Design Values (ppm) for the Nort h Carolina Monitors in the Metrolina Area
Monitoring Site County 2001- 2003 2002- 2004 2003- 2005 2004- 2006 2005- 2007 2006- 2008 2007- 2009 Arrowood Mecklenburg 0.084 0.081 0.078 0.080 0.083 0.079 0.076 County Line Mecklenburg 0.098 0.092 0.087 0.088 0.093 0.094 0.086 Crouse Lincoln 0.092 0.086 0.081 0.079 0.083 0.082 0.076 Enochville Rowan 0.099 0.091 0.085 0.085 0.090 0.088 0.083 Garinger (Plaza) Mecklenburg 0.096 0.091 0.086 0.088 0.090 0.089 0.082 Monroe Union 0.088 0.085 0.079 0.078 0.081 0.080 0.076 Rockwell Rowan 0.100 0.094 0.088 0.083 0.089 0.088 0.083 York York, SC 0.084 0.081 0.075 0.076 0.079 0.077 0.072

*Bolded values exceeding the NAAQS

The current ozone design values are very close to the predic ted design values for 2009 included in the June 2007 attainment demonstration SIP submittal (See Table 2-2 below). The MetrolinaSupplement to the Attainment Demonstration for the 4 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 area is a NOx limited area and the major sources of NOx emissions in the region are from mobile sources (highway and non-road) and electric generating facilities. The reduction in design values since the area was designated nonattainment is attributable to significant reductions in NOx emissions. The emission reductions from the NOx SIP call occurred between 2004 and 2007, the North Carolina Clean Smokestacks Act requir ed NOx emission caps be met in 2007 and 2009, the initial Phase I year for th e Clean Air Interstate Rule (C AIR) is 2009, and every year the mobile source fleet becomes cleaner and the NOx emissions from the highway and off-road mobile source sectors are reduced. All of thes e emission reductions ha ve contributed to the improvement of the design values. In fact, th e air quality measurements for 2009 exhibit clean data; i.e., the fourth highest value at each mon itor is well below the 1997 8-hour ozone standard (See Table 2-3).

Table 2-2 Predicted 2009 Design Values Compared to Actual 2009 Design Values

Monitoring Site County Model Predicted 2009 Design Values (ppm) Actual 2007-2009 Design Values (ppm) Arrowood Mecklenburg 0.075 0.076 County Line Mecklenburg 0.085 0.086 Crouse Lincoln 0.078 0.076 Enochville Rowan 0.084 0.083 Garinger (Plaza) Mecklenburg 0.084 0.082 Monroe Union 0.076 0.076 Rockwell Rowan 0.083 0.083 York York, SC 0.071 0.072

Table 2-3 Fourth Highest 8-hour Ozone Values
Monitoring Site County 2006 2007 2008 2009
Arrowood Mecklenburg 0.080 0.087 0.073 0.068 County Line Mecklenburg 0.093 0.096 0.093 0.071 Crouse Lincoln 0.082 0.085 0.079 0.065 Enochville Rowan 0.089 0.095 0.082 0.073 Garinger (Plaza) Mecklenburg 0.091 0.093 0.085 0.069 Monroe Union 0.080 0.082 0.080 0.067 Rockwell Rowan 0.085 0.096 0.084 0.071 York York, SC 0.078 0.080 0.075 0.062 *Bolded values above the NAAQS

As is demonstrated in the table above, the f ourth highest 8-hour oz one values have been improving. In 2007, there was an observed incr ease of the fourth highest values which corresponded to a significant drought and higher than normal te mperatures. The NCDAQ has reviewed the meteorology for 2009 and has determined that the decrease in ozone levels cannot be explained away due to impr oved meteorological c onditions. In North Carolina, the most serious air quality episodes occur during periods of stagnation, typically over three or moreSupplement to the Attainment Demonstration for the 5 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 consecutive days. Stagnation oc curs when winds are light for an extended period of time. Stagnation can be enhanced by temperature inve rsions, where the temperature increases with height and vertical mixing is reduced. Pollution load ing is kept even higher if there is little or no precipitation. Figure 2-1 shows the number of air stagnation days that occurred between April through September each year for the period 1998 through 2009. For this analysis, a day was defined as stagnant if the current day and the two previous days had upper level winds below 25 miles per hour (mph), lower level winds below 15 mph, and no precipitation. If an inversion was present, the low level wind threshold was incr eased by ten percent. The average number of stagnation days for this period was approximately 25 with a variability of +/- 8 days. In 2009, there were 23 stagnation days which is ve ry close to the 11-year average.

Figure 2-1 Number of Stagnation Days versus Exceedance Days

Another important indicator of ozone exceedances is the average high temperature. In general, the higher the June through August average high temperature, the greater the number of ozone exceedances. Figure 2-2 shows good correlation be tween higher temperatures and a greater number of exceedance days. Average high temp eratures in 2009 were very near the 11-year average of 87.6 oF; however the corresponding number of exceedance days for 2009 does not show the same correlati on as previous years. 0 5 10 15 20 25 30 35 40 45 50

0 10 20 30 40 50 60#ofStagnationDays#ofExceedanceDays

# of Exceedances (85ppb) Stagnation DaysSupplement to the Attainment Demonstration for the 6 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 Figure 2-2 Average High Tempera tures versus Exceedance Days

In addition to comparing the meteorology for 2009 to the 11-year average, the NCDAQ reviewed years that had similar meteorological parameters as 2009. The number of stagnant days and average high temperatures in 2009 was comparable to 2005 and 2006. Despite similar meteorological conditions in 2009 with 2005 and 2006, the number of exceedance days was well below the long term average and the numbers for 2005 and 2006. Therefore, the NCDAQ believes that the decline in ozone levels in 2009 was likely due to emission reductions.

Continued reductions of emissions from the mobi le source sector and the utility sector will influence the ozone formation in this regi on. Based on the 2009 and 2011 modeling emissions inventories, the NCDAQ has estimated that ther e will be reductions of approximately 14.6 tons per day of NOx emissions each year in this region from the highway and non-road mobile sectors. These reductions are the result of Fede ral motor vehicle and equipment engine standards for highway vehicles and off-road equipment, respectively.

Additionally, the overall background leve ls of ozone are expected to decrease as the utilities in the eastern United States put on additional controls to meet CAIR as well as the reductions in emissions of highway and non-road mobile sources throughout the country. For North Carolina, 2009 was the final compliance year for the NOx emission caps for the Clean Smokestacks Act. Figure 2-3 displays the location a nd size of the Duke Energy facilitie s located in the vicinity of the Metrolina nonattainment area. Table 2-4 lists the units that are in and around the Metrolina area, the type of technology installed and the ye ar controls came on line, and the estimated amount of NOx emissions reduc tions for the ozone season. 81 82 83 84 85 86 87 88 89 90 91

0 10 20 30 40 50 60AverageHighTemperature(F)#ofExceedanceDays

# of Exceedances (85ppb) Average JJA Max Temp (F)Supplement to the Attainment Demonstration for the 7 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 Figure 2-3 Location and size of the Duke En ergy facilities located in the vicinity of the Metrolina nonattainment area

Table 2-4 Utility NOx Emission Reductions since 2006 Ozone Season

Facility County Technology Optimized Operational Date Ozone Season Reductions (tons/season) Allen Steam Station Unit 2 Unit 5 Gaston SNCR SNCR 2007 2008 ~175

Buck Steam Station Units 3 & 4 Units 5 & 6 Rowan Low NOx Burners SNCR 2007 Fall 2006 ~225

Riverbend Unit 4 Unit 5 Unit 6 Unit 7 Gaston SNCR SNCR & Burners SNCR & Burners SNCR 2007 2008 Fall 2006 Fall 2006 ~170

Marshall Steam Station Unit 2 Unit 3 Unit 4 Catawba SNCR SCR SNCR 2007 2008 2007 ~1800

Total expected reduction = ~2,370 tons/ozone season SNCR = Selective Non-Catalytic Reduction SCR = Selective Catalytic ReductionSupplement to the Attainment Demonstration for the 8 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 The combination of the highway and non-road mobile sources and utility NOx emission reductions that occurred in the Metrolina ar ea between the end of the 2006 ozone season and before the beginning of the attainment year 2009 was significant. The additional NOx emission reductions in the area resulted in the Metrolin a area having clean data for 2009, which will allow the State to request a one-year ex tension of the attainment date.



### 3.0 WEIGHT OF EVIDENCE MODELING The modeling for the 2009 attainment year for the Metrolina nonattainment area was performed in conjunction with the regiona l haze modeling being done by the Southeast Regional Planning Organization, Visibility Improveme nt State and Tribal Associati on of the Southeast (VISTAS) and the fine particulate matter (PM2.5) and oz one modeling being done by the Association of Southeastern Integrated Planni ng (ASIP). VISTAS and ASIP are managed by the ten Southeast states (Alabama, Florida, Georgia, Kentucky, Mississippi, North Caro lina, South Carolina, Tennessee, Virginia and West Virginia). Sin ce the regional haze and PM2.5 modeling utilizes annual simulations and includes an intermediate year that is the attainment year required for the Metrolina nonattainment area, the NCDAQ decide d to use this modeling for the 2009 attainment year demonstration that was submitted June 2007 to the USEPA.

The supplemental modeling for 2011 was perfor med by the NCDAQ. The methods and inputs used by the NCDAQ were the same as those used by VISTAS/ASIP, with the only exception being a minor alteration in the spatial distri bution of the highway mobile source emissions inventory and the use of a 2011 emissions i nventory. The models used included the Pennsylvania State University /National Center for Atmospheric Research Mesoscale Meteorological Model (MM5), the Sparse Ma trix Operator Kernel Emissions (SMOKE) modeling system and the USEP A’s Models-3/Community Multi scale Air Quality (CMAQ) modeling system.

The analysis method, model sel ection, episode selection a nd modeling domains were all discussed in detail in the June 2007 attainment demonstration SIP and will not be discussed in this supplement. The sections that follow w ill briefly discuss: 1) the 2011 emissions inventory and the controls applied; and 2) the 2011 modeling results and how this additional modeling supports the June 2007 attainment dem onstration as weight of evidence.

3.1 Emission Inventory and Controls Applied

There are five different emission inventory source classifications : stationary point sources, area sources, off-road and on-road mobile sources, and biogenic sources. Stati onary point sources are those sources that emit greater th an a specified tonnage per year and the data is provided at the facility level. Stationary area sources are thos e sources whose emissions are relatively small but due to the large number of thes e sources, the collective emissions could be significant (e.g., dry cleaners, service stations, etc.). These types of emissions are estimated at the county level. Offroad mobile sources include equipment that can move but does not use the roadways (e.g., lawn mowers, construction equipment, railroad locomotiv es, aircraft, etc). The emissions from these sources, like stationary area sources, are estimated at the county level. On-road mobile sources are automobiles, trucks, and motorcycles that us e the roadway system. The emissions from theseSupplement to the Attainment Demonstration for the 9 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 sources are estimated by vehicle type and road type and are summed to the county level. Biogenic sources are the natural sources like tree s, crops, grasses and natural decay of plants. The emissions from biogenic sources are estimat ed at the grid cell level and summed to the county level.

A synopsis of the inventories used for each source classification and a summary of the controls applied are discussed below. The emi ssion summaries by county for the Metrolina nonattainment area, as well as for the State, are in Appendix B, and the detailed discussions of the 2011 emissions inventor y development can be found in Appendix C.

3.1.1 Stationary Point Sources

Point source emissions are from individual source s having a fixed location. In general, these sources have a potential to emit more than five tons per year of carbon monoxide (CO), NOx, particulate matter (PM), sulfur di oxide or VOC from a single facili ty. These sources must have permits to operate and their emissions are inve ntoried on a regular sche dule. Large sources having emissions of 100 tons per year (tpy) of a criteria pollutant, 10 tpy of a single hazardous air pollutant (HAP), or 25 tpy total HAP are inve ntoried annually. Smaller sources have been inventoried less frequently. The point source em issions data can be grouped into the electric generating units (EGU) sources and the other po int sources, or non-EGUs. Appendix B provides the average daily peak ozone season emissions in the Metrolina nonattainment area. Appendix C documents the 2011 point source modeling inve ntory development in more detail.

As part of the regional haze modeling, VI STAS and the Midwest Regional Planning Organization contracted with ICF Resources, L.L.C., to generate a future year emission inventory for the electric generating sector of the contiguous United States using the Integrated Planning Model (IPM). IPM is a dynamic linear optimization model that can be used to examine air pollution control policies fo r various pollutants throughout the contiguous United States for the entire electric power system. The dynamic nature of IPM enables the projection of the behavior of the power system over a specified fu ture period. The optimization logic determines the least-cost means of meeting electric gene ration and capacity requirements while complying with specified constraints includi ng air pollution regulations, tran smission bottlenecks, and plantspecific operational constraints. The versatility of IPM allows users to specify which constraints to exercise and to populate IP M with their own datasets.

The IPM modeling runs took into consideration th e USEPA’s Clean Air Inte rstate Rule (CAIR) implementation and North Carolina’s Clean Smokestacks Act compliance plans for Duke Energy and Progress Energy. The VISTAS States then modified the IPM results to account for known controls expected to be installed, sources th at were known to be shutting down that IPM had operating, and sources that IPM shutdown that a State knew would c ontinue to operate.

The VISTAS 2012 EGU inventory was used as the starting point for the 2011 modeling inventory. This inve ntory was adjusted for 2011 base d upon VISTAS States’ feedback.

The general approach for assembling the 2012 VI STAS non-EGU point source inventory was to use recently updated growth and control data cons istent with the USEPA’s CAIR analyses. ThisSupplement to the Attainment Demonstration for the 10 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 data was supplemented with state specific gr owth factors and stakeholder input on growth assumptions. Based on state feedback, it was determined there would be very minimal differences between a 2012 and 2011 non-EGU emi ssions inventory. Ther efore, the VISTAS 2012 non-EGU inventory was used for the 2011 modeling.

3.1.2 Stationary Area Sources
Stationary area sources include sources whose emi ssions are relatively small but due to the large number of these sources, the collective emissi ons could be significant (e.g., combustion of fuels for heating, structure fires, service stations, et c.). Emissions are estimated by multiplying an emission factor by some known indicator of collec tive activity, such as fuel usage, number of households or population. Stationa ry area source emissions are estimated on the county level.

For categories other than wildland fires, the VI STAS/ASIP contractor generated the 2012 future year emissions inventory. Growth factors s upplied from the states or the USEPA’s CAIR emission projections were applie d to project the controlled em issions. In some cases, the USEPA’s Economic Growth and Analysis System Version 5 growth factors were used if no factor was available from either th e states or the CAIR files. Fo r wildland fires, the 2002 typical base year emissions were used. This is a comm on practice since it is difficult to predict where wildland fires will occur in the future.

The 2012 VISTAS area source emissions inventor y was used for the 2011 modeling since it was determined be a conservative estimate of emi ssions. Appendix B provides emission summaries for average peak ozone season day. Appendix C provides a detailed discussion of the area source inventory development.

3.1.3 Off-Road Mobile Sources

Off-road mobile sources, also referred to as non-ro ad mobile sources, include equipment that can move but do not use the roadways, such as construction equipment, aircraft, railroad locomotives, lawn and garden equipment, etc. Fo r the majority of the non-road mobile sources, the emissions were estimated using the USEPA’ s NONROAD2005c model. For the three source categories not included in the NONROAD model, i.e., aircraft engines, railroad locomotives and commercial marine, more traditional methods of estimating the emissions were used.

The NONROAD model takes into consideration rules that are in effect th at could impact the emissions from these source categories. For the four largest airports in North Carolina, the FAA’s Terminal Area Forecast was used to project growth in aircraft emissions to 2011. For the commercial marine, railroad locomotives and th e remaining airport emissions, the VISTAS/ASIP contractor calculated the 2012 em issions using detailed inventor y data (both before and after controls) for 1996 and 2010 obtained from the USEP A’s Clean Air Interstate Rule Technical Support Document. When available, state specific growth factors were used.

For the 2011 modeling, an interpolated emissi ons inventory between the VISTAS 2009 and 2012 inventories was used. Average daily emissi on summaries can be found in Appendix B. Appendix C provides a detailed discussion of the non-road mobile source inventory.Supplement to the Attainment Demonstration for the 11 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 3.1.4 Highway Mobile Sources
In order to accurately model the mobile sour ce emissions in the Metrolina nonattainment area, the latest version of the MOBI LE model available at the time of the modeling, MOBILE6.2, was used. Key inputs for the MOBILE model include information on the age of vehicles on the roads, the average speed on the roads, the mix of vehicles on the roads, any control technologies in place in an area to reduce emissions for moto r vehicles (e.g., emissions inspection programs), and temperature. The MOBILE model inputs we re developed through in teragency consultation with the transportation partners for this area.

The MOBILE model takes into consideration rules that are in effect that impact the emissions from this source sector. The 2011 emissions inventory was devel oped running the MOBILE model using input data reflective of 2011. Th e 2011 vehicle miles traveled (VMT), speeds, vehicle age and vehicle mix da ta was obtained from the North Carolina Department of Transportation (NCDOT).

Emission summaries by county for the highway mobile source sector can be found in Appendix B. For a detailed discussion about the highway mobile source inventory development used in the 2011 modeling, pleas e refer to Appendix C.

3.1.5 Biogenic Emission Sources
Biogenic emissions were prepared with th e SMOKE-BEIS3 (Biogenic Emission Inventory System 3 version 0.9) preprocessor. SMOKE-B EIS3 is basically the Urban Airshed Model (UAM)-BEIS3 model, but also includes modifica tions to use MM5 data, gridded land use data, and science updates. The emissi on factors that are used in SMOKE-BEIS3 are the same as the emission factors in UAM-BEIS3.

The basis for the gridded land use data used by BE IS3 is the county land use data in the Biogenic Emissions Landcover Database version 3 (BELD3) provided by the USEPA. A separate land classification scheme, based upon satellite ( AVHRR, 1 km spatial resolution) and census information, aided in defining the forest, agri culture and urban portions of each county.

The 2002 base year biogenic emissions were us ed for 2011 modeling. This is a common practice in air quality modeling si nce the same meteorology is used for both base and future year model runs and the biogenic emissions are very dependent on the meteorology. Variation in these emissions could impact the control strategies need ed to demonstrate attainment. Therefore, these emissions are kept constant.

3.1.6 Controls Applied in 2011 Modeling

There are several State and Federa l measures that have been en acted in recent years that are resulting in emissions reductions from stationary point source s, highway mobile sources and nonroad mobile sources. The Federal and State control measures modeled for 2011 are briefly discussed below. A more detaile d description of these measures is in the June 2007 attainment demonstration SIP.Supplement to the Attainment Demonstration for the 12 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 The federal measures that were modeled include:

• Tier 2 vehicle standards: In addition to NOx controls, 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.

• Heavy-duty gasoline and diesel highway vehicle standards: Second phase of standards and testing procedures, which began in 2007, will reduce particulate matter from heavyduty highway engines, and will also reduce high way diesel fuel sulfur content to 15 ppm since the sulfur damages emission control devi ces. The total program is expected to achieve a 90% reduction in pa rticulate matter (PM) emissions and a 95% reduction in NOx emissions.

• Nonroad spark-ignition engines and recreati onal engines standards: Tier 1 of this standard was implemented in 2004 and Tier 2 started in 2007, and will reduce NOx, Carbon Monoxide (CO), hydrocar bons and PM emissions.

• Large nonroad diesel engine standards: Prom ulgated in 2004, this ru le is being phased in between 2008 and 2014. This rule will also reduce sulfur content in nonroad diesel fuel. When fully implemented, this rule will reduce NOx and direct PM2.5 emissions by over 90%.

• NOx SIP Call in surrounding states: In October 1998, the USEPA made a finding of significant contribution of NOx emissions from certain stat es and promulgated a rule that set ozone season NOx budgets for the purpose of reducing regional transport of ozone. This rule, referred to as the NOx SIP Call, required ozone season controls to be put on utility and industrial boilers, as well as inte rnal combustion engines, in 22 states in the Eastern United States. 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 starting in 2004.

• Clean Air Interstate Rule: On May 12, 2005, the USEPA promulgated the “Rule To Reduce Interstate Trans port of Fine Particulate Matter and Ozone (Clean Air Interstate Rule); Revisions to Acid Rain Program; Re visions to the NOX SIP Call”, referred to as CAIR. This rule established the requirement for States to adopt rules limiting the emissions of NOx and sulfur dioxide (SO2). The purpose of CAIR is to reduce interstate transport of precursors of fine particulate a nd ozone. Due to Court challenges of CAIR in 2008, the USEPA will be making changes to this program by 2011. However, the existing CAIR rules will remain in place until the USEPA promulgates changes to the
program.

The state measures that were modeled include:

• Clean Air Bill: This State legislation expanded the inspection and maintenance (I/M) program from 9 counties to 48. Vehicles ar e tested using the onboard diagnostic systemSupplement to the Attainment Demonstration for the 13 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 (OBDII), an improved method of testing, which ensures proper emission system operation for vehicles and li ght trucks during their lifet ime by monitoring emissionrelated components and systems for malfuncti on or deterioration. This program is designed to reduce NOx and Volatile Orga nic Compound (VOCs), and Carbon Monoxide (CO).

• North Carolina NOx SIP Call rule: This rule was predicted to reduce summertime NOx emissions from power plants and other industries by 68%.

• North Carolina Clean Smokestack Act: This le gislation required coal -fired power plants in North Carolina to reduce annual NOx emi ssions by 77% by 2009 and to reduce annual sulfur dioxide emissions by 49% by 2009 and 73% by 2013. This legislation set a cap on NOx and SO2 emissions, which the public u tilities cannot meet by purchasing emission credits. The Clean Smokestacks Act include d stipulations that NOx emission reductions go beyond the requirements of the NOx SIP Call rule since it required year-round NOx controls and did not allow the purchas e of credits to meet the NOx caps.

• Heavy duty diesel engine gap filling rule: This rule required e ngine manufacturers to perform the supplemental testing requirements for heavy duty diesel engines for model years 2005 and 2006 due to delays in the USEPA’ s rule and as a result reduced NOx and PM emissions.

3.2 Modeling Results

Since the Metrolina nonattainment area did not have a design value below the 1997 8-hour ozone standard but did have clean data for 2009, the US EPA has requested supplemental information to support the June 2007 attainment demonstrati on SIP. The NCDAQ utilized 2011 modeling to support the attainment demonstra tion SIP and to provide weight of evidence that the area will attain the standard with a one year extension of the attain ment date to June 15, 2011. The NCDAQ applied the attainment te st as outlined in the USEPA’s Guidance on the Use of Models and Other Analyses for Demonstrating Attainme nt of Air Quality Goals for Ozone, PM2.5 and Regional Haze , (referred to as Attainment Guidance) to the 2011 modeling results.

An explanation of the attainment test and the modeling results are pres ented in the following sections.

3.2.1 Attainment Test Introduction

The modeled attainment test is the practice of using air quality modeling results for baseline and future years to determine if an area is expected to attain th e NAAQS. For the 8-hour ozone NAAQS, the baseline and future model estimates are used in a “relative” rather than “absolute” sense. Specifically, the ratio of the air quality m odel’s future to current predictions is calculated at each ozone monitoring site. These monitoring site-specific ratios are called relative response factors (RRFs). Future ozone design values (DVFs) are then estimated at each monitor by multiplying the monitor-specific baseline ozone design value (DVB) by the modeled RRF for each monitor. If all of the pr edicted monitor-specific DVFs in a given area are less than or equalSupplement to the Attainment Demonstration for the 14 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 to the standard, in this case 0.084 ppm, the attainment test is pa ssed and the area is said to demonstrate attainment. Equation 3.2.1-1 presen ts the modeled attainment test, applied at monitoring site “x” as describe d in Section 4.0 of the USEPA’s Attainment Guidance

.
(DVF) = (RRF) x (DVB) Equation 3.2.1-1

Where (DVB) = the baseline design va lue monitored at site "x", ppm

(RRF) = the ratio of the future 8-hour dail y maximum concentration predicted "nearby" a monitor (averaged over each day of the episode) to the current 8-hour daily maximum concentration predicted "near by" the monitor (averaged over each day of the episode).

(DVF) = the estimated future design value, ppm.

It is important to consider an array of cells “nearby” a monitor rather than focusing on the individual cell containing the monitor. This allows for variations in the model performance where the peak ozone may not occur in the grid cell that contains the m onitor but rather nearby the monitor.

The RRF is calculated by taking the ratio of the future year modeling 8-hour ozone daily maximum to the current year modeling 8-hour ozone daily maximum “near” the monitor averaged over all of the ep isode days (Equations 3.2.1-2).

RRF = mean future year 8-hour daily max “near” monitor “x” Equation 3.2.1-2 mean current year 8-hour daily max “near” monitor “x”

The DVB, for purposes of the modeled attain ment test, is defined in the USEPA’s Attainment Guidance as the average of the three design value pe riods that straddle th e baseline inventory year (e.g., the average of the 2000-2002, 2001- 2003, and 2002-2004 design value periods for a 2002 baseline inventory year).

3.2.2 2011 Modeling Results

As stated above, the attainment test is not base d on absolute modeling resu lts but rather relative responses of ozone and is only applied at the mon itors. A careful review of the predicted ozone values in the future years along with an examin ation of the emission reduc tions are important in determining whether additional controls should be considered.

Table 3.2.2-1 provides the future design values for the Metrolina nonattainment area for 2011. The first column is the monitoring site, followed by the base year design value. The next two columns are the calculated RRF and the resulting DVF for 2011.Supplement to the Attainment Demonstration for the 15 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 Table 3.2.2-1 Attainment Test Results for 2011

Monitoring Site County DVB (ppm) 5-year weighted 2000-2004 2011

RRF DVF (ppm) Arrowood Mecklenburg 0.0847 0.854 0.072 County Line Mecklenburg 0.0973 0.846 0.082 Crouse Lincoln 0.0907 0.829 0.075 Enochville Rowan 0.0970 0.837 0.081 Garinger (Plaza) Mecklenburg 0.0953 0.862 0.082 Monroe Union 0.0870 0.858 0.074 Rockwell Rowan 0.0973 0.837 0.081 York York, SC 0.0830 0.841 0.069

As can be seen in the table above , all monitors in the Metrolina area have pr edicted design values below the standard. These results support NCDAQ’s assertion that the air quality is expected to continue to improve as the NOx emissions cont inue to decline from the point and mobile sources. These results provide additional weight of evidence that the ar ea will attain the 1997 8- hour ozone standard by June 15, 2011.



### 4.0 MOTOR VEHICLE EMISSION BUDGETS The purpose of transportation conformity is to ensure that Federal transportation actions occurring in nonattainment and maintenance ar eas do not hinder the area from attaining and maintaining the 8-hour ozone standard. This mean s that the level of emissions estimated by the NCDOT or the metropolitan planning organi zations for the Transportation Improvement Program and Long Range Transportation Plan mu st not exceed the motor vehicle emission budgets (MVEBs) as defined in th is attainment demonstration.

The NCDAQ has examined the sources of VOC emissions and their contribution to ozone formation in North Carolina. Although NCDAQ steadfastly believes on-road mobile VOCs are insignificant contributors to ozone formation in the Metrolina nonattain ment area, the USEPA has indicated that they will not approve the atta inment demonstration SIP if it does not establish MVEBs for VOCs. Therefore, a requirement for the supplemental analysis is that VOC MVEBs, for transportation conformity purposes, be set for the year 2009.

Motor vehicle emissions estimates for the attainme nt demonstration have been generated at the county level. Developing county level MVEB s maintains consistency with the modeling conducted for the attainment demonstration. The NCDAQ believes that since mobile source NOx emissions play a significan t role in the ozone formation in the Metrolina area, it is important that the large counties in the area meet the county level NOx MVEBs that closely represent the emissions that were modeled fo r the attainment demonstration.Supplement to the Attainment Demonstration for the 16 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 Although the emissions are usually expressed in te rms of tons per day, the MVEBs will be set in terms of kilograms (kg) per day. The reason for the change is because the MOBILE model generates the emissions factors in grams per mile. In past conform ity exercises, there have been some issues with conversion to tons per day, as well as concerns with how the MVEBs were rounded to the hundredth place. Setting MVEBs in kilograms per day will avoid these issues in future conformity determinations.

The mobile inputs used to establish the MVEBs were developed through interagency consultation with the transportati on partners for this area. Thes e inputs were consistent with what was used in the attainment demonstrat ion modeling, and do not re present a significant change to the emissions.

In the attainment demonstration modeling, the vehicle miles traveled (VMT) data used for Iredell County was the Highway Performance Monitori ng System (HPMS) VMT increased by 40%. Travel demand model VMT has been demonstrated to be approximately 30% higher than HPMS VMT, so part of the increase was to adjust Irede ll County’s VMT to be more in line with what would be expected from the travel demand mode l. The additional 10% increase was to account for high growth expected in southern Iredell Co unty which the transportation partners believed would be evident in later revisions to the trav el demand model. For the MVEBs, travel demand model VMT was provided for the nonattainment portion of Iredell County. This VMT was increased by 10% to be representative of what was modeled in the atta inment demonstration.

The table below shows the North Carolina coun ties with their highway mobile NOx and VOC emissions expressed in tons per day and th e corresponding kilograms per day values for 2009.

Table 4-1 2009 Highway Mobile Source Emissions Metrolina Nonattainment Area

County NOx VOC Tons/day Kg/day Tons/day Kg/day Cabarrus 8.57 7,788 8.70 7,893 Gaston 9.48 8,602 6.47 5,870 Iredell* 5.61 5,094 4.32 3,923 Lincoln 3.65 3,317 3.19 2,892 Mecklenburg 32.27 29,270 25.18 22,852 Rowan 8.45 7,675 6.80 6,153 Union 5.57 5,070 6.04 5,486 Total 73.09 66,353 60.70 55,069

* Iredell County emissions for nonattainment area only.

The NCDAQ will set MVEBs, for transportation c onformity purposes, as county budgets within the Metrolina nonattainment area for 2009. Tabl e 4-2 below lists the NOx and VOC MVEBs by county in kilograms per day for transportation conf ormity purposes. It should be noted that these NOx MVEBs are the same as in the original a ttainment demonstration submittal and are being displayed in this supplement for completeness. Upon the USEPA’s affirmative adequacy findingSupplement to the Attainment Demonstration for the 17 Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area April 5, 2010 for these county level sub-area MVEBs, they will become the app licable MVEBs for each county.

Table 4-2 County Level MVEB for 2009

County NOx MVEB (kilograms/day) VOC MVEB (kilogram/day) Cabarrus 7,788 7,893

Gaston 8,602 5,870

Iredell* 5,094 3,923

Lincoln 3,317 2,892

Mecklenburg 29,270 22,852

Rowan 7,675 6,153

Union 5,070 5,486 * Iredell County MVEB fo r nonattainment area only



### 5.0 Summary The air quality data for the Metrolina area has improved significantly since the area was designated nonattainment in 2004. The latest 3- year design value (2007-2 009) for the region is 0.086 ppm, which is just above the 1997 8-hour ozone standard, and the area had clean data for 2009. The fourth highest values for 2007 (Table 2-3) were well above the standard for most monitors. This data will drop off and be re placed with the data for 2010. With the NOx emission reductions that have occurred in the re gion and throughout the Stat e, the fourth highest values for 2010 are expected to be similar to what was seen in 2009. Therefore, the Metrolina area is expected to attain the standard by June 15, 2011.

The 2007 attainment demonstration SIP predicte d the future design values just above the standard and were very close to the actual design values (Table 2-2). The 2011 modeling demonstrates that the design valu es are expected to continue to improve (Table 3.2.2-1). This also supports the NCDAQ’s assertion that th e area will attain the standard by June 15, 2011.