## South Carolina 8-Hour Ozone Attainment Demonstration

For the Portion of York County, South Carolina With in the Rock Hill-Fort Mill Area Transportation Study (RFAT S) Metropolitan Planning Organization (MPO)

Part of the Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Nonattainment Area

Prepared by the South Carolina Department of Health and Environment al Control

Bureau of Air Quality

August 30, 2007TABLE OF CONTENTS

**RFATS MPO 8-HOUR OZONE ATTAINMENT DEMONSTRATION EXE CUTIVE SUMMARY.......1** 

**I. 8-hour Ozone National Ambient Air Quality Stand ards...............................................**  **............................1**

**II. Modeling Protocol.............................**

**................................................... ...................................................**  **1**

**III. Conceptual Description of Ozone Formation ....**

**................................................... .................................1** 

**IV. Attainment Demonstration Methods and Inputs...**

**................................................... ..............................2** 

**V. Model Performance Evaluation...................**

**................................................... .........................................3** 

**VI. Attainment Demonstration......................**

**................................................... ............................................3** 

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

**................................................... ...........................3** 

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

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

**................................................... ..................................5** 

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

**................................................... ...............................5** 

**2. Health Concerns...............................**

**................................................... .............................................5** 

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

**................................................... ....................6** 

**4. 8-Hour Ozone NAAQS............................**

**................................................... .....................................6** 

**B. Nonattainment Area Designations and Classificat ions ...............................................**  **............................6**

**1. Area Designations.............................**

**................................................... ............................................6** 

**2. Nonattainment Area Boundaries.................**

**................................................... ..................................7** 

**3. Nonattainment Area Classifications............**

**................................................... ..................................7** 

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

**................................................... ................................8** 

**D. Charlotte-Gastonia-Rock Hill, NC-SC Metropolita n Statistical Area .................................**  **...................9**

**1. Charlotte-Gastonia-Rock Hill, NC-SC Metropolit an Statistical Area ................................**  **.............9**

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

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

**................................................... ...............................11** 

**1. Metrolina Area................................**

**................................................... ............................................11** 

**2. Metrolina Nonattainment Area Boundaries .......**

**................................................... .........................11** 

**3. Metrolina Nonattainment Area Classification ...**

**................................................... .........................11** 

**F. Conceptual Description of Ozone Formation in th e Metrolina Area...................................**  **..................11**

**G. Clean Air Act Requirements .....................**

**................................................... .........................................15** 

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

**................................................... ........................15** 

**2. Section 182(a) - Plan Submissions and Requirem ents for Marginal Areas ............................**  **.......15**

**3. Section 182(b) - Additional Plan Submissions a nd Requirements for Moderate Areas ................1**  **5**

**SECTION II. ATTAINMENT DEMONSTRATION METHODS AND I NPUTS...................................16** 

**A. Analysis Method ................................**

**................................................... ................................................16** 

**B. Model Selection................................**

**................................................... ..................................................1**  **7**

**1. Selection of Photochemical Grid Model.........**

**................................................... ............................17** 

**a. Criteria .....................................**

**................................................... ...............................................17** 

**b. Overview of CMAQ .............................**

**................................................... ..................................17** 

**2. Selection of Meteorological Model.............**

**................................................... ................................18** 

**a. Criteria .....................................**

**................................................... ...............................................18** 

**b. Overview of MM5..............................**

**................................................... ....................................18** 

**3. Selection of Emissions Processing System......**

**................................................... ...........................19** 

**a. Criteria .....................................**

**................................................... ...............................................19** 

**b. Overview of SMOKE ............................**

**................................................... .................................19** 

**C. Episode Selection ..............................**

**................................................... .................................................20** 

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

**................................................... .......................20** 

**2. Episode Selection.............................**

**................................................... ...........................................20** 

**D. Modeling Domains...............................**

**................................................... ..............................................21** **1. Horizontal Modeling Domain ....................**

**................................................... .................................21** 

**2. Vertical Modeling Domain ......................**

**................................................... ...................................23** 

**E. Emission Inventory.............................**

**................................................... ................................................24** 

**1. Stationary Point Sources ......................**

**................................................... .......................................25** 

**a. Electric Generating Units....................**

**................................................... ....................................25** 

**b. Other Point Sources..........................**

**................................................... ......................................26** 

**2. Stationary Area Sources.......................**

**................................................... .......................................26** 

**3. Nonroad Mobile Sources ........................**

**................................................... ....................................27** 

**4. Highway Mobile Sources........................**

**................................................... ....................................27** 

**5. Biogenic Emission Sources.....................**

**................................................... ....................................28** 

**SECTION III. MODEL PERFORMANCE EVALUATION .........**

**................................................... ........29** 

**A. Domain-Wide Performance ........................**

**................................................... .......................................30** 

**1. Spatial Plots .................................**

**................................................... ...............................................31** 

**2. Scatter Plots .................................**

**................................................... ...............................................39** 

**a. North Carolina Scatter Plots .................**

**................................................... ..................................39** 

**b. South Carolina Scatter Plots.................**

**................................................... ..................................41** 

**3. Time Series Plots .............................**

**................................................... ...........................................43** 

**4. Domain-Wide Summary ...........................**

**................................................... ..................................44** 

**B. Area and Monitor Statistics....................**

**................................................... ............................................45** 

**SECTION IV. CONTROLS APPLIED ......................**

**................................................... ............................47** 

**A. Federal Control Measures .......................**

**................................................... ...........................................47** 

**1. Tier 2 Vehicle Standards......................**

**................................................... .......................................47** 

**2. Heavy-Duty Gasoline and Diesel Highway Vehicle s Standards ........................................**  **...........47**

**3. Large Nonroad Diesel Engines Rule.............**

**................................................... ..............................47** **4. Nonroad Spark-Ignition Engines and Recreationa l Engines Standard.................................**  **..........47**

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

**................................................... ...............................48** 

**6. Clean Air Interstate Rule.....................**

**................................................... ........................................48** 

**B. State Control Measures .........................**

**................................................... .............................................48** 

**1. New Source Review Regulations.................**

**................................................... ...............................48** 

**a. South Carolina Air Pollution Control Regulati on R. 61-62,**  Definitions and General .................

Requirements **, Section II - Permit Requirements .................**

**................................................... .49** 

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

Significant Deterioration

**................................................... ...................................................**  **....49**

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

Source Review

**................................................... ...................................................**  **....................49**

**2. NO x** 

**Regulations .......................................**

**................................................... ..................................49** 

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

Quality Standards

**................................................... ...................................................**  **...............49**

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

Oxides of Nitrogen (NO
x )

**................................................... ...................................................**  **...49**

**c. South Carolina Air Pollution Control Regulati on R. 61-62.96 -**  Nitrogen Oxides (NO
x ) Budget .

Trading Program

**................................................... ...................................................**  **................50**

**d. South Carolina Air Pollution Control Regulati on R. 61-62.99 -**  Nitrogen Oxides Budget ...........

Program Requirements for Stationary Sources Not i n the Trading Program **..........................50**

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

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

Volatile Organic Compounds

**................................................... ...................................................**  **...50**

**4. Other State Control Measures..................**

**................................................... ...................................50** 

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

**................................................... ..............................50** 

**b. Permitting Requirements Involving Emission Of fsets - Conditions for Approval....................**  **51 5. Emissions Inventory: South Carolina Regulatio**  **n R. 61-62.1,** Definitions and General

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

**................................................... .....53** 

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

**................................................... ...................53** 

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

**b. Early Action Compacts........................**

**................................................... ...................................53** 

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

**................................................... ...............................54** 

**d. Overall RACM Conclusions.....................**

**................................................... ..............................55** 

**SECTION V. ATTAINMENT DEMONSTRATION ...............**

**................................................... .............56** 

**A. Attainment Test Introduction ...................**

**................................................... ..........................................56** 

**B. Attainment Test Results ........................**

**................................................... .............................................57** 

**C. Supporting Weight of Evidence ..................**

**................................................... .......................................57** 

**1. Alternative DVF Calculation ...................**

**................................................... ...................................58** 

**2. Additional Air Quality Modeling Metrics.......**

**................................................... ............................59** 

**3. Air Quality Modeling Results From Other Studie s..................................................**  **......................59**

**4. Positive Trends in Observed Air Quality and Ad ditional Emissions Reductions......................**  **....60**

**5. Local Measures Not Modeled....................**

**................................................... .................................63** 

**D. Unmonitored Area Attainment Analysis...........**

**................................................... .................................63** 

**E. Data Access ....................................**

**................................................... ...................................................**  **.64**

**SECTION VI. MODERATE NONATTAINMENT AREA REQUIREMEN TS......................................65** 

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

**,** et seq **.)................................................. ..............65** 

**1. CAA Section 172(c) - Nonattainment Plan Provis ions...............................................**  **...................65**

**2. CAA Section 182 - Plan Submissions and Require ments..............................................**  **................66**

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

**................................................... .........................66** 

**b. CAA Section 182(b) - Moderate Areas ..........**

**................................................... ........................66** **c. CAA Section 182(f) - NO**
**x Requirements......................................**  **............................................67**

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

**1. RACM/RACT Requirements........................**

**................................................... ..............................67** 

**a. RACM.........................................**

**................................................... ............................................67** 

**b. RACT .........................................**

**................................................... ............................................69** 

**2. Reasonable Further Progress...................**

**................................................... ....................................70** 

**3. Actual Emissions Inventory....................**

**................................................... ....................................73** 

**4. Emissions Inventory Statement.................**

**................................................... ..................................73** 

**5. Periodic Emissions Inventory ..................**

**................................................... ...................................73** 

**6. Permit Program Requirements...................**

**................................................... .................................73** 

**7. Gasoline Vapor Recovery .......................**

**................................................... ....................................74** 

**8. Inspection and Maintenance Program............**

**................................................... .............................74** 

**9. Other Measures ................................**

**................................................... ...........................................75** 

**a. NO x** 

**SIP Call..........................................**

**................................................... .................................75** 

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

**................................................... .................76** 

**c. Clean Air Interstate Rule ....................**

**................................................... ....................................77** 

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

**................................................... .............77** 

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

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

**................................................... ..............................78** 

**11. Equivalent Techniques........................**

**................................................... ......................................78** 

**12. Contingency Measures.........................**

**................................................... .....................................78** 

**SECTION VII. MOTOR VEHICLE EMISSION BUDGET........**

**................................................... ..........80** 

**A. Transportation Conformity......................**

**................................................... ...........................................80** 

**1. Memorandum of Agreement.......................**

**................................................... ................................80** 

**2. Conformity Interagency Consultation - York Cou nty/RFATS MPO ......................................**  **......81 3. RFATS - CMAQ Projects.........................** 

**................................................... ..................................81** 

**B. Highway Mobile Source VOC Insignificance.......**

**................................................... .............................82** 

**C. Motor Vehicle Emission Budgets.................**

**................................................... ......................................83** LIST OF FIGURES

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

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

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

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

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

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

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

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

**................................................... .....................................32** 

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

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

**................................................... .......................................33** 

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

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

**................................................... ......................................34** 

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

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

**................................................... .......................................35** 

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

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

**................................................... ......................................36** 

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

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

**................................................... .....................................37** 

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

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

**................................................... ....................................38** 

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

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

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

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

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

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

**monitors for June 2002. ............................**

**................................................... ...............................................43** 

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

**monitors for July 2002.............................**

**................................................... ................................................44** 

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

**monitors for August 2002 ...........................**

**................................................... .............................................44** 

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

**nonattainment area.................................**

**................................................... ..................................................6**  **2**LIST OF TABLES

**Executive Summary Table 1: Attainment Test Results**

**................................................... ............................3** 

**Table I-1: Subpart 2 Classifications and Attainmen t Dates............................................**  **.............................8**

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

**................................................... ......................................10** 

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

**Table III-1: 12-km Domain Model Statistics for 8-H our Ozone ..........................................**  **.....................31**

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

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

**................................................... ........................................57** 

**Table V-2: 5-Year Average Alternative Attainment T est Results for 2009 ...............................**  **...............58**

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

**................................................... ........................60** 

**Table V-4: Metrolina DVFs Based on USEPA’s CAIR Mo deling.............................................**  **...............60**

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

**Table V-6: Utility NO**
**x**

**Emission Reductions since 2006 Ozone Season....... ...........................................62** 

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

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

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

**Table VII-1: 2009 Highway Mobile Source NO**
**x Emissions York County Nonattainment Area.........**  **....83**

**Table VII-2: York County South Carolina NO**
**x MVEB for 2009 .....................................**  **.......................83 1**  LIST OF APPENDICES

**Appendix A:** Correspondence and Guidance Documents

**Appendix B:** Inspection and Maintenance Program

**Appendix C:** Historic Air Quality Data

**Appendix D:** Modeling Protocol

**Appendix E:** Emissions Inventory Summary

**Appendix F1:** Point Source Emissions Inventory Documentation

**Appendix F2:** Area and Nonroad Emissions Inventory Documentation

**Appendix F3:** On-road Mobile Source Emissions Inventory

**Appendix G:** Quality Assurance of the Emissions Inventories

**Appendix H:** Emissions Modeling Deviation from Defaults

**Appendix I:** Meteorological Model Performance

**Appendix J:** Model Performance Evaluation

**Appendix K:** Modeling Results

**Appendix L:** Attainment Test

**Appendix M:** Adopted State Measures

**Appendix N:** Grid Resolution Journal Article

**Appendix O:** Reasonable Further Progress

**Appendix P:** Contingency Measures Documentation

**Appendix Q:** Supporting Documentation from VISTAS

**Appendix R:** Reasonably Available Control Technology

**Appendix S:** RFATS Transportation Conformity**1** SOUTH CAROLINA AIR QUALITY IMPLEMENTATION PLAN

RFATS MPO 8-HOUR OZONE ATTAINMENT DEMONSTRATION EXE CUTIVE SUMMARY

I. 8-hour Ozone National Ambient Air Quality Stand ards

**On April 30, 2004, the United States Environmental Protection Agency (EPA) designated and**  **classified that portion of York County, South Carol ina within the Rock Hill Fort Mill Area Transportat**  **ion Study (RFATS) Metropolitan Planning Organization (M**  **PO) as a moderate nonattainment area for the 8- hour ozone National Ambient Air Quality Standards (**  **NAAQS) as part of the Charlotte-Gastonia-Rock Hill, NC-SC nonattainment area. As a result of this desi**  **gnation, the South Carolina Department of Health an d**  **Environmental Control (SCDHEC or Department) is req uired to amend the**  South Carolina Air Quality Implementation Plan **, also known as the State Implementation Plan, or S IP, in accordance with the**  **requirements of the** Clean Air Act **(CAA), as amended (42 U.S.C. 7401,** et seq **.). States involved in a multi-State ozone nonattainment area must work toge**  **ther to perform the appropriate modeling analyses t o**  **identify control measures that will enable the area to achieve attainment as expeditiously as practica**  **ble. Each State is responsible for its portion of the co**  **ntrol program and will be held accountable for cont rols**  **identified for implementation within its State boun daries.** 

II. Modeling Protocol

**The modeling protocol contains an overview of the models and model configurations that were**  **chosen for use in future year attainment demonstrat ions. Because the Charlotte-Gastonia-Rock Hill are**  **a has been classified moderate nonattainment with a r**  **equired attainment date set for June 15, 2010, the future year emission inventory for 2009 is used for**  **attainment demonstrations. Using USEPA’s guidance on ozone episode selection, 2002 is meteorologicall**  **y well-suited for demonstrating future year attainm ent**  **because 2002 exhibited the most number of days (38) exceeding the 0.08 ppm ozone standard and**  **because 2002 had numerous (13) and a wide variety ( several different types of scenarios) of high ozone**  **episodes.**

**The models that were chosen include the Mesoscale Meteorological Model (MM5), the Sparse**  **Matrix Operator Kernel Emissions (SMOKE) modeling s ystem, and the Community Multiscale Air**  **Quality (CMAQ) model. MM5 and SMOKE outputs will p rovide the meteorological and emissions data**  **that will be input into the CMAQ model. After comp letion of all CMAQ model runs, the final output**  **undergoes operational and diagnostic evaluations to determine model performance. While there are**  **limitations in each of the three chosen models, eac h model is considered the best available for its in**  **tended**

**use.**

**The modeling protocol also provides in-depth discu ssion on inventories of point source, area source,**  **on-road, non-road and biogenic source emission rate s. The development and implementation of quality**  **assurance (QA) and quality control (QC) strategies is the most important step in developing these**  **inventories. QA and QC strategies are described in addition to the process of developing emission con**  **trol strategies that may be applied to demonstrate compl**  **iance.**

III. Conceptual Description of Ozone Formation

**To fully understand the complexity of the ozone fo rmation across North and South Carolina, one**  **must first examine the interactions between the bio genic and anthropogenic emissions sources within**  **North and South Carolina and throughout the surroun ding region, as well as the geographical orientatio**  **n, 2** 

**topography, and the meteorological patterns that de velop over each of the Carolinas on a typical**  **summertime day. All of these interacting component s play a pivotal role in the day-to-day air quality**  **response across the state. On a few select days ea ch summer and often occurring together in episodes,**  **these components work together to produce 8-hour oz one concentrations in excess of the NAAQS. The**  **frequency and duration of these high ozone episodes in an individual summer season are significantly**  **impacted by global scale meteorological patterns an d climate deviations (see Appendix D for details).** 

IV. Attainment Demonstration Methods and Inputs

**The attainment modeling for the Charlotte-Gastonia -Rock Hill, NC-SC nonattainment area was**  **performed in conjunction with the regional haze mod eling being done by the Southeast Regional Planning**  **Organization, Visibility Improvement State and Trib al Association of the Southeast (VISTAS) and the**  **fine particulate matter (PM 2.5**  **) and ozone modeling being done by the Association of Southeastern**  **Integrated Planning (ASIP).**

**Attainment for the Charlotte-Gastonia-Rock Hill, N C-SC nonattainment area was demonstrated**  **through the use of a modeling system consisting of the USEPA’s Models-3/Community Multiscale Air**  **Quality (CMAQ) modeling system, the Pennsylvania St ate University/National Center for Atmospheric**  **Research (PSU/NCAR) Mesoscale Meteorological Model (MM5), and the Sparse Matrix Operator Kernel**  **Emissions (SMOKE) modeling system. The CMAQ modeli ng system is a "one-atmosphere"**  **photochemical air quality modeling system capable o f addressing ozone, fine particulate matter, visibi**  **lity, and acid deposition. The MM5 modeling system is a**  **three-dimensional, limited-area, primitive equation**

**, prognostic meteorological model that accurately rep**  **licates important meteorological phenomena that are used as inputs for the CMAQ air quality model. The**  **SMOKE model is principally an emission processing system that converts emissions inventory**  **data into formatted emission files that are used a s**  **inputs for the CMAQ air quality model.**

**Base year 2002 was chosen to process the typical e missions through the SMOKE emissions model,**  **which corresponds to the same year as the historic meteorology used in the air quality model. Since t**  **he mandatory attainment date for the Charlotte-Gastoni**  **a-Rock Hill, NC-SC area is June 15, 2010, a future year of 2009 was chosen as the modeled attainment y**  **ear. A comparison of the air quality modeling results between these two years is used to determin**  **e a relative reduction in future ozone, which is us ed in**  **the attainment demonstration. A key step in attain ment demonstration modeling is the selection of**  **episodes to model. For this attainment demonstrati on, criteria set out in the USEPA’s**  Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM 2.5 , and Regional Haze **("Attainment Guidance") were used to select the ep isodes that were used in the**  **attainment modeling for the Charlotte-Gastonia-Rock Hill, NC-SC area. The 2002 peak ozone season was**  **chosen to model as this episode covers several crit eria listed in the USEPA Attainment Guidance,**  **including the modeling of weekends and a sufficient number of days to ensure a robust modeled**  **attainment test. Modeling the 2002 peak ozone seas on will also accomplish the goal of encompassing a**  **myriad of meteorological conditions that influence tropospheric ozone formation. A detailed discussio**  **n of the configuration and description of CMAQ, MM5,**  **and SMOKE, as well as a discussion of the episode selection process can be found in the Modeling Prot**  **ocol (Appendix D).**

**Another consideration for the attainment modeling was an appropriate domain for which to model.**  **The CMAQ model was run in one-way nested grid mode, which allowed the larger outer domains to feed**  **concentration data to the inner nested domain. A h igh resolution 12-km grid covering the entire VISTA**  **S region was chosen as the horizontal domain modeling**  **domain for this attainment modeling. The vertical structure of the modeling is primarily defined by t**  **he MM5 34 layer terrain following coordinate system that extends from the surface to the 100 mb layer.**  **The vertical domain in the CMAQ air quality modeli ng**  **was reduced to 19 layers using a layer-averaging sc heme, reducing the computational cost of the** **3**

**simulations with only a minor effect on model perfo rmance.** 

V. Model Performance Evaluation

**Overall, the SCDHEC believes that the model perfor mance is well within the limits of acceptable**  **performance established in the USEPA’s. Attainment Guidance For the most part, mean normalized bias**  **and mean normalized gross error fall within the rec ommended limits for good model performance. The**  **model appears to do a good job of capturing ozone c oncentrations through various episode ramp-up and**  **clean-out cycles. There are some instances of unde r and over predictions. However, in most instances,**  **the model does well in simulating the afternoon ozo ne peak throughout the Carolinas and produces resul**  **ts reliable enough for use as meteorological inputs in**  **the Metrolina Area attainment demonstration CMAQ modeling.** 

VI. Attainment Demonstration

**The attainment demonstration is based on relative reductions of ozone rather than absolute modeling**  **results and is only applied at grid cells near the monitors. Reviewing the modeling results of how th**  **e predicted ozone decreases in the future years and h**  **ow widespread the reductions are play an important role for the State in determining if additional con**  **trols should be considered.**

**The air quality modeling is used in a relative sen se by determining what relative reduction in ozone**  **occurred between the baseline year (2002) and the a ttainment year (2009). Table 1 lists the attainmen**  **t test results for the Charlotte-Gastonia-Rock Hill,**  **NC-SC area. The first two columns are the monitori ng**  **site and the county in which the site is located. The next three columns are the modeling base year d**  **esign value (DVB), the relative response factor (RRF) and**  **the future design value (DVF). According to the USEPA’s Attainment Guidance, areas with future desi**  **gn values between 0.082 and 0.087 ppm need to provide additional weight of evidence that the area**  **will attain the 8-hour ozone NAAQS. Weight of evidence to demonstrate attainment is not required**  **for the monitor in York County.**

Executive Summary Table 1: Attainment Test Results

**2009 Monitoring Site County**  **DVB (ppm) 5-year weighted**  **2000-2004 RRF**  **DVF (ppm)**  **Arrowood Mecklenburg 0.0847**  **0.892 0.075**  **County Line Mecklenburg 0.0973**  **0.874** 0.085 **Crouse Lincoln 0.0907**  **0.868 0.078**  **Enochville Rowan 0.0970**  **0.870** 0.084 **Garinger (Plaza) Mecklenburg 0.0953**  **0.883** 0.084 **Monroe Union 0.0870**  **0.884 0.076**  **Rockwell Rowan 0.0973**  **0.862** 0.083 **York York, SC*** **0.0830 0.861**  **0.071** ***Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area**

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

**The SCDHEC believes that the modeling attainment d emonstration, in conjunction with the weight**  **of evidence analyses, provides the necessary eviden ce that the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area will attain the NAAQS by the pre scribed attainment date.** **4**

**The North Carolina Division of Air Quality (NCDAQ) and South Carolina Department of Health and**  **Environmental Control (SCDHEC) provided strong weig ht of evidence that the Charlotte-Gastonia-Rock**  **Hill, NC-SC nonattainment area will attain the 8-ho ur ozone NAAQS by 2009. This weight of evidence**  **included looking at alternative methods to calculat e the future design values, additional metrics of a**  **ir quality modeling results, air quality modeling resu**  **lts from other studies, positive trends in observed air**  **quality and additional emissions reductions, and ad ditional measures that were not included in the air**  **quality modeling. 5** 

SECTION I. SOUTH CAROLINA AIR QUALITY IMPLEMENTATION PLAN

**On April 30, 2004, the United States Environmental Protection Agency (EPA) designated and**  **classified that portion of York County, South Carol ina within the Rock Hill Fort Mill Area Transportat**  **ion Study (RFATS) Metropolitan Planning Organization (M**  **PO) as a moderate nonattainment area for the 8- hour ozone National Ambient Air Quality Standards (**  **NAAQS) as part of the Charlotte-Gastonia-Rock Hill nonattainment area. As a result of this designatio**  **n, the South Carolina Department of Health and Environmental Control (SCDHEC or Department) is req**  **uired to amend the** South Carolina Air Quality Implementation Plan **, also known as the State Implementation Plan, or S IP, in accordance with the**  **requirements of Title I, Part D - Plan Requirements for Nonattainment Areas, Subpart 1, Section 172, a**  **nd Subpart 2, Section 182 of the**  Clean Air Act **(CAA), as amended (42 U.S.C. 7401,** et seq **.). States involved in a multi-State ozone nonattainment area must work**  **together to perform the appropriate modeling analyses to identify control measures that will ena**  **ble the area to achieve attainment as expeditiously as**  **practicable. Each State is responsible for its por tion of the control program and will be held accoun**  **table for controls identified for implementation within i**  **ts State boundaries.**

A. Introduction to 8-Hour Ozone NAAQS

1. Ground-Level (Tropospheric) Ozone

**Ozone is a colorless gas that occurs naturally in the atmosphere and can be found in the air we**  **breathe. Ozone is composed of three atoms of oxyge n (O**  **3 ), one more than the common oxygen molecule**  **(O 2**  **) we need to breathe to sustain life. The addition al oxygen atom makes ozone extremely reactive.**  **Ozone in the Earth's upper atmosphere, known as str atospheric ozone, shields the Earth from the harmfu**  **l effects of the sun's ultraviolet rays. Ozone found**  **in the atmosphere closer to the Earth's surface (tropospheric ozone) is considered a harmful air po**  **llutant due to its adverse impacts on human health and**  **welfare.**

**Tropospheric ozone is commonly referred to as grou nd-level ozone and sometimes called smog.**  **Ozone is not emitted directly by the combustion of fuels. Ozone is formed in the atmosphere by the**  **reaction of volatile organic compounds (VOC) and ox ides of nitrogen (NO** 
**x ) in the presence of sunlight.**  **These air pollutants, often referred to as ozone pr ecursors, are emitted by many types of pollution so**  **urces, including on-road and off-road motor vehicles and e**  **ngines, power plants and industrial facilities, and smaller sources, collectively referred to as area s**  **ources. Ozone is predominately a summertime air pollutant. Changing weather patterns contribute to**  **yearly differences in ozone concentrations from re gion**  **to region. Ozone and the pollutants that form ozon e also can be transported into an area from polluti**  **on sources found hundreds of miles upwind.** 

2. Health Concerns

**During the hot summer months, ground-level ozone r eaches unhealthy levels in several parts of the**  **country. Ozone has been associated with increased hospitalizations and emergency room visits, school**  **absences, and reduced activity and productivity. Ev en at relatively low levels, breathing ozone can tr**  **igger a variety of health problems. Ozone can irritate t**  **he respiratory system, causing coughing, throat irritation, an uncomfortable sensation in the chest**  **, and/or pain when breathing deeply. Ozone can wor sen**  **asthma and possibly other respiratory diseases, suc h as bronchitis and emphysema. When ozone levels ar**  **e high, more people with asthma have attacks that req**  **uire a doctor's attention or the use of additional medication. Ozone can reduce lung function and mak**  **e it more difficult to breathe deeply, and breathin g**  **may become more rapid and shallow than normal, ther eby limiting a person's normal activity. In**  **addition, breathing ozone can inflame and damage th e lining of the lungs, which may lead to permanent**  **changes in lung tissue, irreversible reductions in lung function, and a lower quality of life if the** **6**

**inflammation occurs repeatedly over a long time per iod (months, years, a lifetime). People who are**  **particularly susceptible to the effects of ozone in clude children and adults who are active outdoors,**  **people with respiratory disease, such as asthma, and peopl**  **e with unusual sensitivity to ozone.**

3. National Ambient Air Quality Standards (NAAQS)

**The CAA requires the USEPA to set NAAQS for pollut ants considered harmful to public health and**  **the environment. National primary and secondary am bient air quality standards under Section 109 of th**  **e CAA are set forth in Title 40 of the Code of Federa**  **l Regulations, part 50. NAAQS are subject to revisi on,**  **and additional primary and secondary standards may be promulgated as the USEPA deems necessary to**  **protect the public health and welfare. The USEPA h as promulgated primary and secondary NAAQS for**  **carbon monoxide, lead, nitrogen dioxide, particulat e matter, sulfur oxides, and ground level ozone. T**  **he USEPA calls these pollutants "criteria" air polluta**  **nts because it regulates them by developing human health-based and/or environmentally-based criteria**  **(science-based guidelines) for setting permissible levels. For each pollutant, a health-based or "pri**  **mary" standard has been set to protect public healt h in**  **general, and a welfare-based or "secondary" standar d has been set to protect quality of life and the**  **environment. Primary standards set limits to prote ct public health, including the health of "sensitiv**  **e" populations such as asthmatics, children, and the e**  **lderly. Secondary standards set limits to protect public**  **welfare, including protection against decreased vis ibility, damage to animals, crops, vegetation, and**  **buildings.**

4. 8-Hour Ozone NAAQS

**In 1997, the USEPA revised the NAAQS for ground-le vel ozone, setting the standard at 0.08 parts**  **per million (ppm) averaged over an 8-hour period. At each ozone monitoring site, hourly average**  **concentrations are recorded in parts per million (p pm). Running 8-hour averages are computed from the**  **hourly ozone concentration data for each hour of th e year. The daily maximum 8-hour concentration for**  **a given calendar day is the highest of the 24 possibl**  **e 8-hour average concentrations computed for that d ay.**  **The standard-related summary statistic is the three -year average of the annual fourth-highest daily**  **maximum 8-hour average ozone concentrations. The t hree-year average is computed using the three most**  **recent, consecutive calendar years of monitoring da ta. This three-year average annual fourth-highest**  **daily maximum 8-hour average ozone concentration is also the air quality design value for the monitori**  **ng site. A violation of the 8-hour ozone NAAQS occurs**  **when the computed design value is greater than or equal to 0.085 ppm.** 

B. Nonattainment Area Designations and Classificat ions

1. Area Designations

**On February 8, 1979, the USEPA promulgated the 0.1 2 parts per million (ppm) 1-hour ozone**  **standards, (44** Federal Register **8202). On July 18, 1997, the USEPA promulgated a revised ozone**  **standard of 0.08 ppm, measured over an 8-hour perio d [i.e., the 8-hour standard (62 FR 38856)]. Upon**  **promulgation of a new or revised NAAQS, the CAA req uires the USEPA to designate areas as attaining**  **or not attaining that NAAQS. On April 30, 2004, th e USEPA announced and promulgated designations,**  **classifications, and boundaries for every area in t he United States with respect to the 8-hour ozone**  **NAAQS (69 FR 23857).**

**The 8-hour ground-level ozone NAAQS design values were calculated for each ozone monitor in the**  **United States. The USEPA area designations were ge nerally based on air quality monitoring data**  **collected from 2001 to 2003. The highest monitor d esign value in an area was used to determine its**  **designation. The CAA then specifies requirements f or areas based on whether such areas are or are not** **7**

**attaining the NAAQS.**

2. Nonattainment Area Boundaries

**The CAA defines a nonattainment area as an area th at is violating an ambient standard or is**  **contributing to a nearby area that is violating the standard. Once it is determined that a monitor is**  **recording a violation, the next step is to determin e if there are any nearby areas that are contributi**  **ng to the violation and include them in the designated nonatt**  **ainment area. When evaluating the air quality fact ors**  **for individual areas, the USEPA took into account i ts view that, in most cases, data recorded by an oz**  **one air quality monitor represents air quality througho**  **ut the area in which the monitor is located. The U SEPA**  **used the county as the basic jurisdictional unit in determining the extent of the area reflected by th**  **e ozone monitor data. As a result, if an ozone monitor was**  **violating the standard based on the 2001–2003 data**

**, the USEPA designated the entire county as nonattain**  **ment. The actual size of the nonattainment area ma y**  **be larger or smaller, depending on air quality-rela ted technical factors contained in the USEPA guidan**  **ce on determining nonattainment area boundaries for th**  **e 8-hour ozone standard.**

**Section 107(d)(4) of the CAA established the Conso lidated Metropolitan Statistical Area (CMSA) or**  **Metropolitan Statistical Area (MSA) as the presumpt ive boundary for areas designated nonattainment in**  **1991 for violating the ozone NAAQS. Once a CMSA, M SA, or single county area was determined to**  **contain a monitor that was violating the standard, the USEPA and the State considered several factors,**  **including emissions, population density, traffic co ngestion, commercial development, industrial**  **development, meteorological conditions, and polluti on transport in establishing the nonattainment area**  **boundaries. It is necessary to evaluate all counti es in and around an area containing a monitor that**  **is violating the standard to justify including countie**  **s outside the CMSA or MSA or excluding counties in the CMSA or MSA. In some cases, in considering the**  **se factors as well as information and recommendations provided by the State, the USEPA de**  **termined that only part of a county was contributing to the nearby nonattainment area.** 

3. Nonattainment Area Classifications

**Title I, part D of the CAA contains two sets of pr ovisions that address planning and control**  **requirements for nonattainment areas. Subpart 1 (wh ich is referred to as "basic" nonattainment) contai**  **ns general, less prescriptive, requirements for nonatt**  **ainment areas for any pollutant governed by a NAAQS**

**, including ozone. Subpart 2 (which is referred to a**  **s "classified" nonattainment) provides more specifi c**  **requirements for ozone nonattainment areas.**

**An area designated nonattainment for the 8-hour oz one NAAQS with a 1-hour design value less than**  **0.121 ppm at the time of designation is subject to the requirements of Subpart 1 and is covered under**  **Section 172(a)(1) of the CAA. These "basic" nonatt ainment areas have five years from designation to**  **attain the standard. The USEPA has provided flexib ility for areas that have entered into a compact an**  **d take early action to achieve emissions reductions n**  **ecessary to attain the 8-hour ozone standard. This action defers the effective date of the nonattainme**  **nt designation for these areas and establishes regulations governing future actions with respect t**  **o these areas. The USEPA has also promulgated deferral of the effective date of the nonattainment**  **designation for Early Action Compact areas.**

**8-hour ozone nonattainment areas with 1-hour desig n values of 0.121 ppm or greater at the time of**  **designation are subject to the provisions of Subpar t 2 and are classified in accordance with Section 1**  **81 of the CAA as marginal, moderate, serious, severe, or**  **extreme depending on the area's 8-hour design value**

**. Nonattainment areas with more serious ozone polluti**  **on, as differentiated by these area classifications , are**  **subject to more control requirements as prescribed in Section 182 of the CAA. These prescribed**  **requirements are designed to bring areas into attai nment by their specified attainment dates, which ar**  **e 8** 

**also based upon the area's classification. (See Tab le I-1: "Subpart 2 Classifications and Attainment**  **Dates.")**

Table I-1: Subpart 2 Classifications and Attainmen t Dates

**Classification Design Value Range (ppm) Attainment Date**  **Marginal 0.085 up to 0.092 June 15, 2007 Moderate 0.092 up to 0.107 June 15, 2010**  **Serious 0.107 up to 0.120 June 15, 2013 Severe 15 0.120 up to 0.127 June 15, 2019**  **Severe 17 0.127 up to 0.187 June 15, 2021 Extreme 0.187 and above June 15, 2024** 

C. 8-hour Ozone Designations for South Carolina

**On April 15, 2004, the USEPA promulgated 8-hour oz one designations and classifications for all of**  **the counties in South Carolina based on the design values calculated from air quality monitoring data**  **collected during the 2001, 2002, and 2003 ozone sea sons. Almost all of South Carolina was designated**  **unclassifiable/attainment for the 8-hour ozone stan dard; however, the following three areas of South**  **Carolina were designated nonattainment:**

**1. Greenville-Spartanburg-Anderson Area: This no nattainment area includes the entirety of**  **Greenville, Spartanburg, and Anderson Counties. Th e Greenville-Spartanburg-Anderson Area was**  **designated a Subpart 1 nonattainment area. The Gre enville-Spartanburg-Anderson Area has opted to**  **enter into an Early Action Compact and take early a ction to achieve emissions reductions necessary to**  **attain the 8-hour ozone standard. The USEPA has pr omulgated deferral of the effective date of the**  **nonattainment designation for the Greenville-Sparta nburg-Anderson Area.** 

**2. Columbia Area: This nonattainment area includ es the portions of Richland and Lexington**  **counties within the borders of the Columbia Area Tr ansportation Study (COATS) Metropolitan Planning**  **Organization (MPO). The Columbia Area was designat ed a Subpart 1 nonattainment area. The Columbia**  **Area has opted to enter into an Early Action Compac t and take early action to achieve emissions**  **reductions necessary to attain the 8-hour ozone sta ndard. The USEPA has promulgated deferral of the**  **effective date of the nonattainment designation for the Columbia Area.** 

**3. Charlotte-Gastonia-Rock Hill, NC-SC Area: The Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area includes that portion of York Co unty, South Carolina within the Rock Hill Fort Mill**  **Area Transportation Study (RFATS) Metropolitan Plan ning Organization (MPO). The Charlotte**  **Gastonia-Rock Hill, NC-SC Area (also referred to as the Metrolina area) is classified as a Subpart 2**  **moderate nonattainment area.**

**Figure I-1,** 8-hour ozone nonattainment boundaries for South Car olina **, outlines the majority of the State that was designated attainment/unclassifiable**  **and highlights the corresponding boundaries of the three areas designated nonattainment.** **9** Figure I-1: 8-hour ozone nonattainment boundaries for South Carolina

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

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

**The Charlotte-Gastonia-Rock Hill, NC-SC Metropolit an Statistical Area (MSA), as defined by the**  **Federal Office of Management and Budget (OMB) on Ju ne 30, 1999, consists of Cabarrus, Gaston,**  **Lincoln, Mecklenburg, Rowan, and Union Counties in NC; and York County in SC. MSA boundaries are**  **based on city and county populations in urbanized a reas, with "outlying counties" being included in th**  **e MSA contingent upon their commuting patterns into t**  **he central counties. Under OMB standards, the county (or counties) that contains the largest city**  **becomes the "central county" (counties), along wit h any**  **adjacent counties that have at least 50 percent of their populations in the urbanized area surrounding**  **the largest city. The MSA are named according to the p**  **opulations of the largest central cities. As noted previously, the CMSA or MSA is the USEPA presumptiv**  **e boundary for areas designated nonattainment for violating the ozone NAAQS.** 

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

**Figure I-2: "Monitors in the Charlotte-Gastonia-R ock Hill, NC-SC MSA" displays where monitors**  **are located in the Charlotte-Gastonia-Rock Hill, NC -SC MSA. There are no ozone monitors located in**  **either Cabarrus County or Gaston County in NC. The historic air quality data for the monitors in the**  **Charlotte-Gastonia-Rock Hill, NC-SC MSA is listed i n Appendix C.** **10** Figure I-2: Monitors in the Charlotte-Gastonia-Roc k Hill, NC-SC MSA

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

**Table I-2: "2001-2003 Design Values" lists the an nual fourth-highest daily maximum 8-hour**  **average ozone concentration and calculated design v alues for all of the monitors within the Charlotte**  **Gastonia-Rock Hill, NC-SC MSA.**

Table I-2: 2001-2003 Design Values

**4 th**  **Highest 8-hour Ozone Value Monitor County**  **2001 2002 2003 2001-2003**  **Design Value**

**Crouse Lincoln 0.094 0.095 0.089** 0.092 **County Line Mecklenburg 0.099 0.107 0.088** 0.098 **Garinger (Plaza) Mecklenburg 0.099 0.103 0.086** 0.096 **Arrowood Mecklenburg 0.086 0.094 0.073 0.084 Enochville Rowan 0.103 0.108 0.087**  0.099 **Rockwell Rowan 0.097 0.106 0.098** 0.100 **Monroe Union 0.081 0.100 0.083** 0.088 **York York, SC* 0.080 0.096 0.076 0.084**

**Values shown in bold represent violations of the 8- hour ozone NAAQS**  ***Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area 11** 

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

1. Metrolina Area

**The USEPA designated and classified ozone nonattai nment areas according to the calculated 2001-**  **2003 design values listed in Table I-2: "2001-2003 Design Values." An area referred to as the Charlo**  **tte Gastonia-Rock Hill, North Carolina-South Carolina (**  **Metrolina) Area was designated a nonattainment area for the 8-hour ozone standard.** 

2. Metrolina Nonattainment Area Boundaries

**The USEPA considered several factors, including em issions, population density, traffic congestion,**  **commercial development, industrial development, met eorological conditions, and pollution transport, in**  **evaluating all counties in and around the MSA to es tablish the nonattainment area boundaries. The ent**  **ire North Carolina portion of the MSA, which includes C**  **abarrus, Gaston, Lincoln, Mecklenburg, Rowan and Union Counties, was designated to be part of the Me**  **trolina nonattainment area. Two North Carolina area s**  **outside of the MSA, Coddle Creek Township and David son Township in Iredell County, were determined**  **to be contributing to violating monitors and are in cluded in the Metrolina nonattainment area. Althou**  **gh the monitor in York County, South Carolina during t**  **hat time was below the 8-hour ozone standard of 0.085 parts per million (ppm), the USEPA determined**  **that a portion of York County contributed to violating monitors in nearby North Carolina. That**  **portion of York County, South Carolina, which is situated within the Rock Hill Fort Mill Area Transp**  **ortation Study (RFATS) Metropolitan Planning Organization (MPO) was designated as a partial coun**  **ty nonattainment area and included in the Metrolina nonattainment area. (It should be noted that the Y**  **ork County ozone monitor is located outside of the designated nonattainment area boundary.)** 

3. Metrolina Nonattainment Area Classification

**The USEPA resolved that the Metrolina nonattainmen t area classification should be based on the**  **highest 8-hour ozone design value calculated for an y of the monitors located within the boundaries of**  **the designated nonattainment area. In reviewing the da**  **ta analysis reflected in Table I-2: "2001-2003 Des ign**  **Values," the highest regional design value was 0.10 0 ppm.** 

**In accordance with the classification criteria sum marized in Table I-1: "Subpart 2 Classifications an**  **d Attainment Dates," the USEPA classified the Metroli**  **na area as a Subpart 2, moderate nonattainment area**

**.**

**The Metrolina nonattainment area must demonstrate attainment of the 8-hour ozone NAAQS by no**  **later than June 15, 2010.**

F. Conceptual Description of Ozone Formation in th e Metrolina Area

**The full conceptual description of ozone formation in North Carolina and the Metrolina**  **nonattainment area is discussed in Appendix D. Thi s section will focus on the conceptual description**  **of ozone formation in the Metrolina area.** 

**As stated earlier, ozone forms through the reactio n of NO** 
**x and VOC emissions. Due to generally**  **warm and moist climate of the Carolinas, vegetation abounds in many forms. The emissions from natural**  **sources, such as vegetation, are referred to as bio genic emissions and account for approximately 90% o**  **f the total VOC emissions in the Carolinas. This res**  **ults in the Carolinas being a NO**
**x -limited environment,**  **which means that reductions in NO**
**x emissions will have the greatest impact on reducing**  **ozone formation 12** 

**in the Carolinas, including the Metrolina area.**

**North Carolina’s most populous metropolitan region s are located in the central portions or the**  **Piedmont of the state. The three largest cities (C harlotte, Greensboro, and Raleigh) form a partial**  **crescent extending from the southwest to the northe ast. This combination of metropolitan regions is o**  **ften referred to as the Piedmont Crescent. A network of**  **interstate and intrastate highways interconnects t hese**  **three largest cities and further extends into adjoi ning states (such as South Carolina) in a general**  **southwest to northeast pattern. The mobile-based N O**  **x emissions follow these highway networks with the**  **highest emissions occurring in or near the city cen ters. The industrial point sources with both**  **anthropogenic NO**
**x**

**and VOC emissions are also generally located in cl ose proximity to the cities and the**  **major road networks. Finally, North Carolina’s lar gest NO**  **x point sources are electric generating**  **facilities, which are spatially scattered around st ate but are most heavily concentrated near the Pied**  **mont Crescent. Figure I-3 displays the location of the**  **electric generating facilities in and near the Metr olina**  **nonattainment area. 13** 



### Figure I-3: Location of electric generating facili ties in and near the Metrolina nonattainment area

**By combining each of the major emission source cat egories (biogenic source VOC emissions and**  **mobile sources (highway and non-road) and electric generating facilities NO** 
**x emissions), the highest**  **concentrations of precursor pollutants for ozone fo rmation are focused throughout the Piedmont Crescen**  **t, which includes the Metrolina area. Therefore, the**  **greatest potential for ozone formation, with the ri ght**  **weather conditions, is also in this central portion of North Carolina.** 

**Figure I-4 displays the breakdown of man-made NO**
**x emissions in and near the Metrolina**  **nonattainment area. This figure shows that in the Metrolina area, including the counties that neighbo**  **r the nonattainment area, point source and highway mobile**  **source NO x**  **emissions account for over three quarters on the NOx emissions. The majority of the**  **point source NO**
**x emissions come from the electric**  **generating facilities. Therefore, these sources th at most impact ozone formation in the Metrolina reg**  **ion are highway mobile sources and electric generating**  **facilities. 14** 

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

**In addition to the emissions, meteorology plays an important role in ozone formation as well.**  **Almost all high ozone episodes occurring in the Sou theastern United States will have some common**  **meteorological characteristics, including warm temp eratures, lower relative humidity, little or no**  **precipitation, and relatively light winds. These c onditions are nearly universally indicative of regi**  **onal high-pressure patterns causing large-scale sinking**  **(subsiding) air at various levels of the atmosphere . The**  **differences in the position, strength, and movement of these high pressure areas, along with differenc**  **es in various mid-to-upper level wind patterns, allow sta**  **ff to discern five meteorological scenarios, or “regimes”, in which high ozone episodes are likely**  **to occur in the Carolinas. These meteorological regimes are discussed in detail in Appendix D.** 

**The regional transport of ozone into the Metrolina area also contributes to the high ozone values**  **observed in the Metrolina area. Just outside the b orders of the Carolinas is a collection of large**  **metropolitan regions. These metropolitan regions h ave similar emissions profiles and frequencies of h**  **igh ozone concentrations leading to exceedances of the**  **8-hour ozone NAAQS. It is reasonable to conclude that precursor pollutants, as well as formed ozone,**  **can be transported from any of these larger metropolitan regions into the Carolinas with an app**  **ropriate wind flow orientation from one or more of these regions. In recognition of the effects of re**  **gional transport of ozone, the USEPA has promulgate d**  **two rules to help reduce the effects of transported pollutants; the NO** 
**x SIP Call Rule and the Clean Air**  **Interstate Rule.**

**In additional to regional transport, recirculated pollution around the Metrolina area affects high**  **ozone events. Winds in the lower and middle atmosp here can shift around in a variety of directions.**  **In the most frequent scenarios, winds transition from**  **one direction to another in a clockwise fashion dur ing**  **the extent of the complete synoptic cycle or scenar io. This clockwise shifting of the winds is a key**  **characteristic of eastward-moving high pressure sys tems in the Northern Hemisphere. In a large**  **recirculation pattern, plume(s) of precursor pollut ants and formed ozone may leave the Metrolina area**  **one day, travel across multiple regions, then return to**  **the very air shed from where it started within a m atter of**  **days. Throughout the journey of air parcels in thi s type pattern, precursor pollutants and ozone are**  **constantly being exchanged and added to the air par cels from each source sector and metropolitan regio**  **n along the way, irrespective of any geo-political bo**  **undaries. In such smaller scale recirculation patt erns,**  **precursor pollutants and ozone from two neighboring metropolitan regions can exchange back and forth**  **over a series of days, especially as a strong area of high-pressure moves from west to east across the**  **region.**

**To summarize the conceptual description of ozone f ormation in the Metrolina area, various**  **Point 25%**  **Area 4%**  **Nonroad M obile 17%** 

**Highway M obile 54%** **15**

**meteorological regimes in conjunction with biogenic VOC emissions and man-made NO** 
**x emissions can**  **result in high ozone values in the Metrolina area. Reductions in highway mobile source and electric**  **generating facility NO**
**x**

**emissions in and near the Metrolina area will have the greatest impact on reducing**  **ozone formation.**

G. Clean Air Act Requirements

**Sections 172(c), 182(a), and 182(b) of the** Clean Air Act **(CAA), as amended (42 U.S.C. 7401,** et
seq. **), prescribe the requirements for ozone nonattainme nt areas. All designated nonattainment areas must**  **comply with the general requirements mandated by Se ction 172(c) of the CAA. As a Subpart 2, moderate**  **ozone nonattainment area, the Metrolina area must a lso meet the additional requirements prescribed by**  **Section 182 of the CAA. Each State in which all or part of a moderate nonattainment area is located s**  **hall make the submissions described under Section 182(a)**  **(relating to marginal nonattainment areas) and sha ll**  **also submit the revisions to the applicable impleme ntation plan described under Section 182(b) with**  **respect to moderate nonattainment areas. These req uirements are listed below and are discussed in mor**  **e details in Section VI of this attainment SIP.** 

1. Section 172(c) - Nonattainment Plan Provisions

**a. Reasonably available control measures (RACM) b. Reasonable further progress (RFP)**  **c. Actual emissions inventory and periodic emiss ions inventory**  **d. New source review (NSR) / Attainment Demonstr ation**  **e. Permit requirements for new and modified sour ces**  **f. Other measures as may be necessary to provide attainment by specified attainment date**  **g. Compliance with Section 110(a)(2) h. Equivalent techniques**  **i. Contingency measures**

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

**a. Actual emissions inventory in accordance with 172(c)(3)**  **b. Corrections to SIP i. Reasonably available control technology (RAC**  **T) ii. Motor vehicle inspection and maintenance (I**  **/M) iii. Permit programs**  **c. Periodic emissions inventory i. General emission inventory every three years**  **until area is redesignated to attainment ii. Annual emissions statement for sources emit**  **ting 25 tons per year or greater of VOC or NO**  **x**
3. Section 182(b) - Additional Plan Submissions a nd Requirements for Moderate Areas

**a. Reasonable further progress b. Reasonable available control technology**  **c. Gasoline vapor recovery d. Motor vehicle I/M**  **e. Offset requirements of at least 1.15 to 1. 16** 

SECTION II. ATTAINMENT DEMONSTRATION METHODS AND I NPUTS

**The attainment modeling for the Metrolina nonattai nment area was performed in conjunction with**  **the regional haze modeling being done by the Southe ast Regional Planning Organization, Visibility**  **Improvement State and Tribal Association of the Sou theast (VISTAS) and the fine particulate matter**  **(PM 2.5**  **) and ozone modeling being done by the Association of Southeastern Integrated Planning (ASIP).**  **VISTAS and ASIP are run by the ten Southeast states (Alabama, Florida, Georgia, Kentucky, Mississippi,**  **North Carolina, South Carolina, Tennessee, Virginia and West Virginia). Since the regional haze**  **modeling uses annual simulations and includes an in termediate year that is the attainment year require**  **d for the Metrolina nonattainment area, the NCDAQ and**  **the SCDHEC decided to use the this modeling for our ozone attainment demonstration. The sections b**  **elow outline the methods and inputs used by VISTAS/ASIP for this regional modeling.** 

A. Analysis Method

**The modeling analysis is a complex technical evalu ation that begins by selection of the modeling**  **system. VISTAS decided to use the following modeli ng system:** 

**1. Air Quality Model: the USEPA’s Models-3/Comm unity Multiscale Air Quality (CMAQ)**  **modeling system is a ‘One-Atmosphere’ photochemical grid model capable of addressing ozone,**  **particulate matter (PM), visibility and acid deposi tion at regional scale for periods up to one year.** 

**2. Meteorological Model: The Pennsylvania State University/National Center for Atmospheric**  **Research (PSU/NCAR) Mesoscale Meteorological Model (MM5) is a nonhydrostatic, prognostic**  **meteorological model routinely used for urban- and regional-scale photochemical, fine particulate matt**  **er, and regional haze regulatory modeling studies.** 

**3. Emissions Model: The Sparse Matrix Operator K ernel Emissions (SMOKE) modeling**  **system is an emissions modeling system that generat es hourly gridded speciated emission inputs of**  **mobile, nonroad mobile, area, point, fire and bioge nic emission sources for photochemical grid models.** 

**Additionally, a historical year is selected to mod el that represent typical meteorological conditions**  **in the Southeast when high ozone, PM**  **2.5 and poor visibility are observed throughout the Re**  **gion. Once the historical year is selected, meteorological inputs**  **are developed using the meteorological model. Emis sion**  **inventories are also developed for the historical y ear and processed through the emissions model. The**  **se inputs are used in the air quality model to predict**  **ozone, PM 2.5**  **and visibility, with the results compared to the historic data. The model performance is evalua**  **ted by comparing the modeled predicted data to the historic air quality data.** 

**Once model performance is deemed adequate, typical baseline and future year emissions are**  **processed through the emissions model. For this de monstration, the baseline year was 2002, which**  **corresponds with the same year as the historic mete orology used in the modeling. The attainment futur**  **e year the NCDAQ and the SCDHEC are using for this de**  **monstration is 2009, since the mandatory attainment date for the Metrolina area is June 15,**  **2010. Since this attainment date is set prior to t he**  **completion of the 2010 ozone season, the attainment of the NAAQS would have to be met by the end of**  **the 2009 ozone season. These 2002 baseline and 200 9 future typical emissions are processed through th**  **e air quality model with the meteorological inputs.**  **The air quality modeling results are used to determ ine a**  **relative reduction in future ozone, which is used i n the attainment demonstration.** 

**The complete modeling protocol used for this analy sis can be found in Appendix D.** **17**

B. Model Selection

**To ensure that a modeling study is defensible, car e must be taken in the selection of the models to b**  **e used. The models selected must be scientifically a**  **ppropriate for the intended application and be free ly**  **accessible to all stakeholders. Scientifically app ropriate means that the models address important**  **physical and chemical phenomena in sufficient detai l using peer-reviewed methods. Freely accessible**  **means that model formulations and coding are freely available for review and that the models are**  **available to stakeholders and their consultants for execution and verification at no or low cost.** 

**The following sections outline the criteria for se lecting a modeling system that is both defensible a**  **nd capable of meeting the study's goals. These criter**  **ia were used in selecting the modeling system used for**  **this modeling attainment demonstration.**

1. Selection of Photochemical Grid Model

a. Criteria

**For a photochemical grid model to qualify as a can didate for use in an attainment demonstration of**  **the 8-hour ozone NAAQS, a State needs to show that it meets several general criteria:** 

**• The model has received a scientific peer review ;**  **• The model can be demonstrated applicable to the problem on a theoretical basis;**  **• Databases needed to perform the analysis are av ailable and adequate;**  **• Appropriate performance evaluations have shown the model is not biased toward**  **underestimates or overestimates; • A protocol on methods and procedures to be foll**  **owed has been established; and • The developer of the model must be willing to m**  **ake the source code available to users for free or for a reasonable cost, and the model ca**  **nnot otherwise be proprietary.**

b. Overview of CMAQ

**The photochemical model selected for this study wa s CMAQ version 4.4. For more than a decade,**  **the USEPA has been developing the Models-3 CMAQ mod eling system with the overarching aim of**  **producing a ‘One-Atmosphere’ air quality modeling s ystem capable of addressing ozone, fine particulate**  **matter, visibility, and acid deposition within a co mmon platform. The original justification for the**  **Models-3 development emerged from the challenges po sed by the 1990 CAAA and the USEPA’s desire**  **to develop an advanced modeling framework for ‘holi stic’ environmental modeling utilizing state-of**  **science representations of atmospheric processes in a high performance computing environment. The**  **USEPA completed the initial stage of development wi th Models-3 and released the CMAQ model in mid**  **1999 as the initial operating science model under t he Models-3 framework. The most recent rendition i**  **s CMAQ version 4.4, which was released in October 200**  **4.**

**Another reason for choosing CMAQ as the atmospheri c model is the ability to do one-atmospheric**  **modeling. Since the SCDHEC will be using the same modeling exercise for the ozone attainment**  **demonstration SIP as well as the regional haze SIP, having a model that can handle both ozone and**  **particulate matter is essential. A number of featu res in CMAQ’s theoretical formulation and technical**  **implementation make the model well suited for annua l particulate matter modeling.** 

**The configuration used for this modeling demonstra tion, as well as a more detailed description of the**  **CMAQ model, can be found in the Modeling Protocol ( Appendix D).** **18**

2. Selection of Meteorological Model

a. Criteria

**Meteorological models, either through objective, d iagnostic, or prognostic analysis, extend available**  **information about the state of the atmosphere to th e grid upon which photochemical grid modeling is to**  **be carried out. The criteria for selecting a meteo rological model are based on the model’s ability to**  **both accurately replicate important meteorological pheno**  **mena in the region of study and interface with the rest**  **of the modeling systems--particularly the photochem ical grid model. With these issues in mind, the**  **following criteria were established for the meteoro logical model to be used in this study:** 

**• Non-Hydrostatic Formulation • Reasonably current, peer reviewed formulation**  **• Simulates Cloud Physics • Public availability at no or low cost**  **• Output available in I/O API format • Supports Four Dimensional Data Assimilation (F**  **DDA) • Enhanced treatment of Planetary Boundary Layer**  **heights for air quality modeling**

b. Overview of MM5

**The non-hydrostatic MM5 model is a three-dimension al, limited-area, primitive equation, prognostic**  **model that has been used widely in regional air qua lity modeling applications. The basic model has be**  **en under continuous development, improvement, testing**  **and open peer-review for more than 20 years and has been used worldwide by hundreds of scientists f**  **or a variety of mesoscale studies.**

**MM5 uses a terrain-following non-dimensionalized p ressure, or "sigma," vertical coordinate similar**  **to that used in many operational and research model s. In the non-hydrostatic MM5, the sigma levels ar**  **e defined according to the initial hydrostatically-ba**  **lanced reference state so that the sigma levels are also**  **time-invariant. The gridded meteorological fields produced by MM5 are directly compatible with the**  **input requirements of ‘one atmosphere’ air quality models using the same coordinate system. MM5 field**  **s can be easily used in other regional air quality mo**  **dels with different coordinate systems by performin g a**  **vertical interpolation, followed by a mass-conserva tion adjustment.** 

**Distinct planetary boundary layer (PBL) parameteri zations are available for air quality applications,**  **both of which represent sub-grid-scale turbulent fl uxes of heat, moisture, and momentum. One scheme**  **uses a first-order eddy diffusivity formulation for stable and neutral environments and a modified fir**  **st order scheme for unstable regimes. The other schem**  **e uses a prognostic equation for the second-order turbulent kinetic energy, while diagnosing the othe**  **r key boundary layer terms.**

**Initial and lateral boundary conditions are specif ied for real-data cases from mesoscale three**  **dimensional analyses performed at 12-hour intervals on the outermost grid mesh selected by the user.**  **Surface fields are analyzed at three-hour intervals . A Cressman-based technique is used to analyze**  **standard surface and radiosonde observations using the National Meteorological Center's spectral analy**  **sis as a first guess. The lateral boundary data are in**  **troduced using a relaxation technique applied in th e**  **outermost five rows and columns of the coarsest gri d domain.** 

**Results of detailed performance evaluations of the MM5 modeling system in regulatory air quality**  **application studies have been widely reported in th e literature (e.g., Emery et al., 1999; Tesche et a**  **l., 2000, 2003), and many have involved comparisons wit**  **h other prognostic models such as the Regional Atmospheric Modeling System (RAMS) and the Systems**  **Application International Mesoscale Model. 19** 

**The MM5 enjoys a far richer application history in regulatory modeling studies compared with RAMS or**  **other models. Furthermore, in evaluations of these models in over 60 recent regional scale air qualit**  **y application studies since 1995, it has generally be**  **en found that the MM5 model tends to produce somewhat better photochemical model inputs than alt**  **ernative models.**

**The configuration used for this modeling demonstra tion, as well as a more detailed description of the**  **MM5 model, can be found in the Modeling Protocol (A ppendix D).** 

3. Selection of Emissions Processing System

a. Criteria

**The principal criterion for an emissions processin g system is that it accurately prepares emissions**  **files in a format suitable for the photochemical gr id model being used. The following list includes**  **clarification of this criterion and additional desi rable criteria for effective use of the system.** 

**• File System Compatibility with the I/O API • File Portability**  **• Ability to grid emissions on a Lambert Conform al projection**  **• Report Capability • Graphical Analysis Capability**  **• MOBILE6 Mobile Source Emissions • Biogenic Emissions Inventory System version 2**  **(BEIS-3) • Ability to process emissions for the proposed**  **domain in a reasonable amount of time • Ability to process control strategies**  **• No or low cost for acquisition and maintenance • Expandable to support other species and mechan**  **isms**

b. Overview of SMOKE

**The SMOKE Emissions Processing System Prototype wa s originally developed at the Micro**  **computing Center of North Carolina. As with most ‘ emissions models,’ SMOKE is principally an**  **emission processing system and not a true emissions modeling system in which emissions estimates are**  **simulated from ‘first principles’. This means that , with the exception of mobile and biogenic sources**  **, its purpose is to provide an efficient, modern tool for**  **converting emissions inventory data into the forma tted**  **emission files required by an air quality simulatio n model. For mobile sources, SMOKE actually**  **simulates emissions rates based on input mobile-sou rce activity data, emission factors and outputs fro**  **m transportation travel-demand models.** 

**SMOKE was originally designed to allow emissions d ata processing methods to utilize emergent**  **high-performance-computing as applied to sparse-mat rix algorithms. Indeed, SMOKE is the fastest**  **emissions processing tool currently available to th e air quality modeling community. The sparse matri**  **x approach utilized throughout SMOKE permits both rap**  **id and flexible processing of emissions data. The processing is rapid because SMOKE utilizes a series**  **of matrix calculations instead of less efficient algorithms used in previous systems. The processin**  **g is flexible because the processing steps of tempo ral**  **projection, controls, chemical speciation, temporal allocation, and spatial allocation have been separ**  **ated into independent operations wherever possible. The**  **results from these steps are merged together at a final**  **stage of processing.**

**SMOKE contains a number of major features that mak e it an attractive component of the modeling**  **system. The model supports a variety of input form ats from other emissions processing systems and** **20**

**models. It supports both gridded and county total land use schemes for biogenic emissions modeling.**  **SMOKE can accommodate emissions files from up to 10 countries and any pollutant can be processed by**  **the system.**

**For additional information about the SMOKE model p lease refer to the Modeling Protocol**  **(Appendix D).**

C. Episode Selection

**A crucial step to SIP modeling is the selection of episodes to model. Several considerations need to**  **be weighed before settling on not only which days t o model, but how many days are modeled for each**  **episode. This section details the guidance and pro cess by which episodes were selected for the 8-hour**  **Ozone SIP modeling package.**

1. Overview of USEPA Guidance on Ozone

**The USEPA’s Attainment Guidance on 8-hour ozone mo deling sets out specific criteria for the**  **selection of episodes to model for attainment of th e 8-hour ozone NAAQS. First, episodes should inclu**  **de days encompassing a variety of meteorological condi**  **tions, including varying wind directions, for days exceeding 0.084 ppm. Additionally, episodes should**  **be selected that contain days close to (within ± 0.010 ppm) the current design value (DVC). Episode**  **s should also be chosen around days for which there are extensive air quality and meteorology measureme**  **nts, including measurements aloft, measurements of indicator species and/or precursor measurements. F**  **inally, a sufficient number of days should be selec ted**  **to ensure robust attainment tests at violating moni toring sites.** 

**The USEPA also suggests a set of secondary criteri a, in addition to the primary criteria, that may be**  **used in the selection of episodes. This set of cri teria allows states to give preference to previousl**  **y modeled episodes. This is a very valuable consider**  **ation, as the USEPA points out, since it can save modeling resources and effort. Additional consider**  **ations include selecting episodes maximizing the number of days and sites observing a violation, sel**  **ecting episodes that include weekends, and, when considering regional scale modeling, selecting epis**  **odes that meet primary and secondary criteria in ot her**  **nonattainment areas. Using these criteria laid out by the USEPA, the data available was systematicall**  **y examined to determine the best episodes for modelin**  **g.**

2. Episode Selection

**With the advances in computing and storage technol ogies, and with the aid provided by regional**  **modeling efforts, the NCDAQ and the SCDHEC intend t o move toward the modeling of the peak ozone**  **season for the 8-hour ozone attainment demonstratio n SIP. By modeling the peak season, several criter**  **ia are covered, including the modeling of weekends and**  **a sufficient number of days to ensure a robust modeled attainment test. Modeling the peak ozone s**  **eason will also accomplish the goal of encompassing a myriad of meteorological conditions that influenc**  **e tropospheric ozone formation.**

**Efforts were made to determine an appropriate peri od to model. The selection process started with**  **an examination of the 8-hour ozone maxima for the 1 997 through 2004 seasons to determine which**  **season may yield the most days to be included for s tudy. Following the second primary criteria, the**  **number of days each monitoring site observed a valu e within 0.010 ppm of the design value was tabulate**  **d using the recently suggested 5-year weighted averag**  **e (the average of the three 3-year design values in the**  **five year period centered on the base year).**

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

**generally had the most exceedance days for the indi vidual monitoring sites. When 2002 was not the**  **highest year, it was generally either the second or third highest for either design value convention.**  **Since 2002 was the base year for the VISTAS modeling as w**  **ell, choosing the 2002 ozone season for the episode allowed the use of the VISTAS ASIP modeling**  **for the attainment demonstration for ozone.**

**The months of May through September 2002 were typi cal of the meteorology one would expect for**  **an active ozone season, namely warmer and drier tha n average. Temperatures were 1 to 2 oF warmer than**  **average across the state and throughout the Mid-Atl antic States, and the precipitation values were 4-6**  **inches below normal for most of the Carolinas. The dry conditions were also present for much of the**  **coastal Mid-Atlantic States. The warmer and drier conditions led to lower soil moisture throughout mu**  **ch of the East coast, which reduced the evaporation of**  **moisture into the air and decreased dew point temperatures. With less available moisture in the**  **atmosphere, cloud cover was decreased, which led to more sunlight, increased photochemistry, and higher**  **levels of ozone across the region.**

**Additionally, the episode classification further v erifies that the 2002 ozone season is a representat**  **ive year for use in attainment demonstration modeling.**  **The 2002 ozone season encompasses six of the region’s typical meteorological scenarios: eastern**  **stacked highs, frontal approaches, Canadian highs, modified Canadian highs, progressive continental hi**  **ghs and the subcategory of tropical influence. Thu s,**  **the 2002 season provides an excellent case to evalu ate various control strategies for maintaining the**  **NAAQS for ozone.**

**For these reasons, the 2002 ozone season was selec ted as the episode to model for the attainment**  **demonstration. Further details of the episode sele ction process, episode classification procedures, a**  **nd episode classifications for the 2002 ozone season c**  **an be found in the Modeling Protocol (Appendix D).**

D. Modeling Domains

1. Horizontal Modeling Domain

**The CMAQ model was run in one-way nested grid mode . This allowed the larger outer domains to**  **feed concentration data to the inner nested domain. One-way nesting is believed to be appropriate for**  **the generally stagnant conditions experienced during Me**  **trolina ozone episodes. Two-way nesting was not considered due to numerical and computational uncer**  **tainty associated with the technique.**

**The horizontal coarse grid modeling domain boundar ies were determined through a national effort to**  **develop a common grid projection and boundary. Sin ce this national modeling domain was used in the**  **VISTAS regional haze modeling, it was used for the attainment demonstration as well. A smaller 12-km**  **grid modeling domain was selected in an attempt to balance location of areas of interest, such as ozon**  **e and fine particulate matter nonattainment areas, as**  **well as Class 1 and wilderness areas for regional haze.**  **Processing time was also a factor in choosing a sma ller 12-km grid modeling domain.** 

**The coarse 36-km horizontal grid domain covers the continental United States. This domain was**  **used as the outer grid domain for MM5 modeling with the CMAQ domain nested within the MM5**  **domain. Figure II-1 shows the MM5 horizontal domai n as the outer most, blue grid with the CMAQ 36-**  **km domain nested in the MM5 domain. 22** 

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

**To achieve finer spatial resolution in the VISTAS states, a one-way nested high resolution (12 km**  **grid resolution) was used. Figure II-2 shows the 1 2-km grid modeling domain for the VISTAS region.**  **This is the modeling domain on which the attainment test results are based. A study was performed to**  **determine if using a finer grid resolution provided different modeling results. Since the USEPA’s**  **attainment test uses the modeling results to determ ine the relative reductions in ozone between the ba**  **se year and the future year, it was determined that es**  **sentially the same attainment test results are obta ined**  **from either 12-km grid modeling or 4-km grid modeli ng. Since 4-km grid modeling takes significantly**  **more time and resources to run, it was decided that the VISTAS 12-km grid modeling results for this**  **attainment demonstration would be used. A copy of a journal article describing the results of the gri**  **d resolution study can be found in Appendix N.** **23** Figure II-2: A more detailed view of the 12-km grid over the VISTAS region.

2. Vertical Modeling Domain

**The CMAQ vertical structure is primarily defined b y the vertical grid used in the MM5 modeling.**  **The MM5 model employed a terrain following coordina te system defined by pressure, using 34 layers**  **that extend from the surface to the 100 mb layer. Table II-1 lists the layer definitions for both MM5**  **and for CMAQ. A layer-averaging scheme is adopted for**  **CMAQ to reduce the computational cost of the CMAQ simulations. The effect of layer averaging wa**  **s evaluated in conjunction with the VISTAS modeling effort. It was found that layer averaging**  **had a relatively minor effect on the model perform ance**  **metrics when both the 34 layer and a 19 layer CMAQ models were compared to ambient monitoring data.**  **A discussion of the modeling sensitivity for this l ayer averaging can be found in Section 9.1 of the**  **VISTAS Model Performance Evaluation and Model Sensi tivity Tests for Three Phase I Episodes report**  **dated September 7, 2004. 24**  Table II-1: Vertical Layer Definition for MM5 and CMAQ

MM5 Simulation CMAQ 19 Layers **Layer Sigma Pressure** 

**(mb) Height** 

**(m) Depth** 

**(m) Layer Sigma**  **Pressure (mb)**  **Height**

**(m) Depth** 

**(m)**
34 0.000 100 14662 1841 19 0.000 100 14662 6536 **33 0.050 145 12822 1466 0.050 145 32 0.100 190 11356 1228 0.100 190**  **31 0.150 235 10127 1062 0.150 235 30 0.200 280 9066 939 0.200 280**  29 0.250 325 8127 843 18 0.250 325 8127 2966 **28 0.300 370 7284 767 0.300 370 27 0.350 415 6517 704 0.350 415**  **26 0.400 460 5812 652 0.400 460** 25 0.450 505 5160 607 17 0.450 505 5160 1712 **24 0.500 550 4553 569 0.500 550 23 0.550 595 3984 536 0.550 595**  22 0.600 640 3448 506 16 0.600 640 3448 986 **21 0.650 685 2942 480 0.650 685** 20 0.700 730 2462 367 15 0.700 730 2462 633 **19 0.740 766 2095 266 0.740 766** 18 0.770 793 1828 259 14 0.770 793 1828 428 **17 0.800 820 1569 169 0.800 820** 16 0.820 838 1400 166 13 0.820 838 1400 329 **15 0.840 856 1235 163 0.840 856** 14 0.860 874 1071 160 12 0.860 874 1071 160 **13 0.880 892 911 158 11 0.880 892 911 158** 12 0.900 910 753 78 10 0.900 910 753 155 **11 0.910 919 675 77 0.910 919** 10 0.920 928 598 77 9 0.920 928 598 153 **9 0.930 937 521 76 0.930 937** 8 0.940 946 445 76 8 0.940 946 445 76 7 0.950 955 369 75 7 0.950 955 369 75 6 0.960 964 294 74 6 0.960 964 294 74 5 0.970 973 220 74 5 0.970 973 220 74 4 0.980 982 146 37 4 0.980 982 146 37 3 0.985 986.5 109 37 3 0.985 986.5 109 37 2 0.990 991 73 36 2 0.990 991 73 36 1 0.995 995.5 36 36 1 0.995 995.5 36 36 0 1.000 1000 0 0 0 1.000 1000 0 0

E. Emission Inventory

**There are five different emission inventory source classifications: stationary point and area source**  **s, off-road and on-road mobile sources, and biogenic s**  **ources. Stationary point sources are those sources that emit greater than a specified tonnage per year**  **and the data is provided at the facility level. S tationary** **25**

**area sources are those sources whose emissions are relatively small but due to the large number of the**  **se sources, the collective emissions could be signific**  **ant (e.g., dry cleaners, service stations, etc.). These**  **types of emissions are estimated on the county leve l. Off-road mobile sources include equipment (e.g.** 

**, lawn mowers, construction equipment, railroad locom**  **otives, aircraft, etc.) that can move, but do not u se**  **the roadways. The emissions from these sources, li ke stationary area sources, are estimated on the co**  **unty level. On-road mobile sources are automobiles, tru**  **cks, and motorcycles that use the roadway system. The emissions from these sources are estimated by v**  **ehicle type and road type and are summed to the county level. Biogenic sources are the natural sou**  **rces like trees, crops, grasses, and natural decay of**  **plants. The emissions from these sources are estim ated on a county level.** 

**In addition to the various source classifications, there are also various types of emission inventori**  **es. The first is the actual base year inventory. This**  **inventory is the base year emissions that correspon d to**  **the meteorological data. For this modeling effort, the base year is 2002. These emissions are used f**  **or evaluating the air quality model performance.** 

**The second type of inventory is the typical base y ear inventory. This inventory is similar to the**  **actual base year. However, for sources that may ha ve significant changes from year-to-year, a more**  **typical emission value is used. In this modeling e ffort, typical emissions were developed for electri**  **c generating units (EGUs) and wildland fire emissions**  **. The air quality modeling results using these emissions are used in calculating the relative resp**  **onse factors used in the attainment demonstration t est.**  **The future year base inventory is an inventory deve loped for some future year for which attainment of**  **the ozone standard is needed. For this modeling projec**  **t, the future year inventory will be 2009, the last complete year for which the standard must be attain**  **ed. It is the future base year inventory to which control strategies and sensitivities are applied to**  **determine what controls beyond those measures alre ady**  **included in the future year base inventory, to whic h source classifications must be made in order to a**  **ttain and maintain the ozone standard.** 

**In the sections that follow, a synopsis of the inv entories used for each source classifications are**  **discussed. Detailed discussions of the emissions i nventory development can be found in Appendix F, an**  **d emission summaries by county for the Metrolina nona**  **ttainment area and for the State are in Appendix E.**

1. Stationary Point Sources

**Point source emissions are those emissions from la rger individual sources having a fixed location.**  **Generally, these sources must have permits to opera te, and their emissions are inventoried on a regula**  **r schedule. Large sources having emissions of 100 to**  **ns per year (tpy) of a criteria pollutant, 10 tpy o f a**  **single hazardous air pollutant (HAP), or 25 tpy tot al HAP are inventoried regularly. Smaller sources**  **have not been inventoried and are included in the area s**  **ource inventory. The point source emissions data c an**  **be grouped into the EGU sources and the other point sources (e.g., non-EGUs).** 

a. Electric Generating Units

**The actual base year inventory for the EGU sources used 2002 continuous emissions monitoring**  **(CEM) data reported to the USEPA’s Acid Rain progra m or 2002 hourly emissions data provided by**  **stakeholders. This data provides hourly emissions profiles that can be used in the modeling of these**  **large sources of NO** 
**x**

**and helps to provide more accurate modeling of the se sources.** 

**Since the NO**
**x**

**emissions from EGU sources are a significant part of the emissions inventory, a**  **typical base year emissions inventory was developed for these sources to avoid anomalies in emissions**  **due to variability in meteorology and economic and outage factors in 2002. This approach is consisten**  **t with the USEPA’s modeling guidance. To develop a t**  **ypical year 2002 emissions inventory for EGU 26** 

**sources, the average CEM heat input for 2000 throug h 2004 was divided by the 2002 actual heat input fo**  **r each unit to generate a unit specific normalizing f**  **actor. This normalizing factor was then multiplied by**  **the 2002 actual emissions. The heat inputs for the period 2000 through 2004 were used since the**  **modeling current design values use monitoring data from this same five-year period. If a unit was**  **shutdown for an entire year during the 2000 through 2004 period, the average of the years the unit was**  **operational was used. If a unit was shutdown tempo rarily in 2002, the emissions and heat inputs for 2**  **001 (or 2000) were used in the normalizing calculations** 

**. As part of the VISTAS modeling, VISTAS and the Mid**  **west Regional Planning Organization contracted with ICF Resources, L.L.C., to generate**  **the future year emission inventory for the electric generating sector of the contiguous United States u**  **sing the Integrated Planning Model (IPM). IPM is a dynamic linear optimization model that can be used**  **to examine air pollution control policies for vario us**  **pollutants throughout the contiguous United States for the entire electric power system. The dynamic**  **nature of IPM enables the projection of the behavio r of the power system over a specified future perio**  **d. The optimization logic determines the least-cost me**  **ans of meeting electric generation and capacity requirements while complying with specified constra**  **ints including air pollution regulations, transmiss ion**  **bottlenecks, and plant-specific operational constra ints. The versatility of IPM allows users to speci**  **fy which constraints to exercise and populate IPM with**  **their own datasets.**

**The IPM modeling runs took into consideration the USEPA’s Clean Air Interstate Rule (CAIR)**  **implementation and North Carolina’s Clean Smokestac ks Act compliance plans for Duke Power and**  **Progress Energy.**

b. Other Point Sources

**For the non-EGU sources, the same inventory will b e used for both the actual and typical base year**  **emissions inventories. The non-EGU category will u se annual emissions as reported for the Consolidate**  **d Emissions Reporting Rule (CERR) for the year 2002.**  **These emissions were temporally allocated to month, day, and hour using source category code (SC**  **C) based allocation factors using the SMOKE emissions model.** 

**The general approach for assembling future year da ta was to use recently updated growth and control**  **data consistent with the USEPA’s analyses. This d ata was supplemented with state specific growth**  **factors and stakeholder input on growth assumptions**

**.**
2. Stationary Area Sources

**Stationary area sources include sources whose emis sions are relatively small but, due to their large**  **numbers, whose collective emissions could be signif icant (e.g., combustion of fuels for heating, struc**  **ture fires, service stations, etc.). Emissions are esti**  **mated by multiplying an emission factor by some kno wn**  **indicator of collective activity, such as fuel usag e, number of households, or population. Stationary**  **area source emissions are estimated on the county level.** 

**The area source 2002 base year inventory for South Carolina was developed by the VISTAS/ASIP**  **contractor. The VISTAS/ASIP contractor used the 20 02 CERR as the basis for the area source inventory.**  **The sources estimated by the contractor include emi ssions from animal husbandry, wildland fires, and**  **particulate matter from paved and unpaved roads. F or the other states within the modeling domain, the**  **state supplied data or the CERR data for 2002 was u sed.** 

**The actual base year inventory will serve as the t ypical base year inventory for all area source**  **categories except for wildland fires. For this sou rce category, development of a typical year fire** **27**

**inventory provided the capability of using a compar able data set for both the base year and future yea**  **rs. Thus, fire emissions would remain the same for air**  **quality modeling in both the base and any future years. The VISTAS Fire Special Interest Work Group**  **was consulted and decided that State-level ratios of acres over a longer term record (three or more y**  **ears) developed for each fire type relative to 2002 would be used. The 2002 acreage was then scaled up**  **or down based on these ratios to develop a typical year inventory.** 

**For categories other than wildland fires, the VIST AS/ASIP contractor generated the future base year**  **emissions inventory used in the attainment demonstr ation modeling. Growth factors supplied from the**  **states or the USEPA’s emission projections were app lied to project the controlled emissions to the**  **appropriate year. In some cases, USEPA’s Economic Growth and Analysis System Version 5 growth**  **factors were used if no growth factor was available from either the states or the growth factor files.** 

3. Nonroad Mobile Sources

**Nonroad mobile sources include equipment that can move but do not use the roadways, such as**  **construction equipment, aircraft, railroad locomoti ves, lawn and garden equipment, etc. For the major**  **ity of the nonroad mobile sources, the emissions were e**  **stimated using the USEPA’s NONROAD2005c model. For the three source categories not include**  **d in the NONROAD model (aircraft engines, railroad locomotives, and commercial marine engines), more t**  **raditional methods of estimating the emissions were used. The same inventory will be used for both the**  **actual and typical base year emissions inventories for**  **the nonroad mobile sources.**

**For the source categories estimated using the USEP A’s NONROAD model, the model was used to**  **create a future base year inventory. The NONROAD m odel takes into consideration rules that are in**  **effect that could impact the emissions from these s ource categories. For the commercial marine, railr**  **oad, and airport emissions, the VISTAS/ASIP contractor c**  **alculated the future base year emissions using detailed inventory data (both before and after cont**  **rols) for 1996 and 2010 obtained from the USEPA’s** Clean Air Interstate Rule Technical Support Documen t **. When available, state specific growth factors were used.** 

4. Highway Mobile Sources

**The attainment modeling for the Charlotte-Gastonia- Rock Hill, North Carolina-South Carolina**  **nonattainment area (referred to as the Metrolina ar ea) was performed in conjunction with the regional**  **haze modeling being done by the Southeast Regional Planning Organization, Visibility Improvement**  **State and Tribal Association of the Southeast (VIST AS) and the fine particulate matter (PM**  **2.5 ) and ozone**  **modeling being done by the Association of Southeast ern Integrated Planning (ASIP). VISTAS and ASIP**  **are run by the ten Southeast states (Alabama, Flori da, Georgia, Kentucky, Mississippi, North Carolina,**  **South Carolina, Tennessee, Virginia and West Virgin ia).** 

**The South Carolina transportation partners involved in attainment demonstration State**  **Implementation Plan (SIP) and motor vehicle emissio n budget development included: USEPA Region 4,**  **South Carolina Department of Transportation (SCDOT) , Federal Highway Administration (FHWA),**  **Federal Transit Administration (FTA), South Carolin a Department of Health and Environmental Control**  **(SCDHEC), and the Rock Hill-Fort Mill Area Transpor tation Study (RFATS) Metropolitan Planning**  **Organization (MPO). The Charlotte Department of Tra nsportation (CDOT) was consulted for speeds and**  **VMT data derived from the Metrolina travel demand m odel (TDM). Refer to Appendix F.3 for more**  **detailed information.**

**In order to accurately model the mobile source emi ssions in the Metrolina nonattainment area, the** **28**

**newest version of the MOBILE model, MOBILE6.2, was used. Key inputs for the MOBILE model**  **include information on the age of vehicles on the r oads, the average speed on the roads, the mix of**  **vehicles on the roads, any control technologies in place in an area to reduce emissions for motor vehi**  **cles (e.g., emissions inspection programs), and temperat**  **ure.**

**The MOBILE model takes into consideration rules th at are in effect that impact the emissions from**  **this source sector. For highway mobile sources, th e actual and typical year emissions were the same a**  **nd the MOBILE model was run using input data reflectiv**  **e of 2002. The same model then is run for the future year emissions inventory using input data re**  **flective of 2009. The 2002 and 2009 vehicle miles traveled (VMT) are based on data provided by the So**  **uth Carolina Department of Transportation (SCDOT).** 

5. Biogenic Emission Sources

**Biogenic emissions were prepared with the SMOKE-BE IS3 (Biogenic Emission Inventory System 3**  **version 0.9) preprocessor. SMOKE-BEIS3 is basicall y the Urban Airshed Model (UAM)-BEIS3 model,**  **but also includes modifications to use MM5 data, gr idded land use data, and science updates. The**  **emission factors that are used in SMOKE-BEIS3 are t he 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) prov ided by the USEPA. A separate land**  **classification scheme, based upon satellite (AVHRR, 1 km spatial resolution) and census information,**  **aided in defining the forest, agriculture, and urba n portions of each county.** **29**

SECTION III. MODEL PERFORMANCE EVALUATION

**There are many accepted methodologies for evaluati ng the performance of any air quality model.**  **This section, however, will focus primarily on the methods and techniques recommended by the USEPA**  **for evaluating the performance of air quality model s. Before the air quality model can be fully evalu**  **ated, a comprehensive understanding of the performance of**  **the meteorological model being used for its inputs is essential. This evaluation should be specifical**  **ly designed to identify potential biases and errors that**  **may be passed directly from the meteorological mode l into the air quality model. The meteorological**  **modeling evaluation is fully documented in Appendix I and is briefly summarized in the next few**  **paragraphs.**

**Generally speaking, the meteorological modeling pe rformance was quite good at both the 36-km and**  **12-km grid resolutions. Synoptic features were acc urately predicted and the meteorological model**  **showed considerable skill in replicating all import ant atmospheric variables (e.g., temperature, mixin**  **g ratio, relative humidity, wind speed and direction,**  **cloud cover, and precipitation) necessary to drive the**  **CMAQ air quality model. Performance statistics sho w that the meteorological modeling results fell**  **within expected and acceptable ranges of error duri ng the majority of the 2002 modeled year.** 

**The meteorological modeling performance for North and South Carolina was very similar to the**  **performance for the VISTAS/ASIP region for the 12-k m modeling domain. As before, large-scale**  **meteorological patterns were accurately predicted. The meteorological model demonstrated substantial**  **skill throughout the entire 2002 modeling year, and was especially skillful during the summertime (cor**  **e ozone) season from May through September.** 

**For the North Carolina portion of the 12km modelin g domain (which includes York County, SC), the**  **temperature bias was near zero in May, June, and Au gust. July had a slight negative temperature bias**  **near –0.25 Kelvin (K), and September had a negative temperature bias of –0.1 K. The mixing ratio bias**  **was near 0 gram/kilogram (g/kg) in May through July and then fell to –0.2 g/kg in August and to -0.6 i**  **n September. The relative humidity bias generally ho**  **vered around ± 3% throughout the summer. Cloud coverage bias peaked near 10% in July and was biase**  **d less than 5% during the other summertime months. Wind direction was the most erratic of the measurem**  **ents. The direction bias throughout North Carolina was more pronounced than for the full 12-km domain,**  **being more negative May through July, and more positive in August and September. When considering**  **all wind measurements, the wind speed was 0.8 to 1.0 meters per second (m/s) too strong. When omitt**  **ing calm observations, the bias falls to 0.2 to 0.5 m/s.**  **Additionally, the meteorological model noticeably o verestimated the amount of summertime precipitation**  **across both Carolinas. However, it was reasonably accurate in reproducing the spatial coverage of**  **measurable precipitation.**

**Overall, excess wind speeds, increased relative hu midity, more daytime cloud cover, and**  **precipitation overestimations will likely contribut e to slight under predictions of the daily maximum**  **peak ozone concentration in the CMAQ air quality model.**  **Based on the comprehensive VISTAS & NCDAQ evaluation of the 2002 VISTAS MM5 results, the SCDH**  **EC believes that the meteorological model performance is adequate for this modeling exercise**  **for the York County, SC portion of the Metrolina 8- hour Nonattainment Area, and should produce credibl**  **e inputs for CMAQ air quality modeling for the Metrolina Area attainment demonstration.** 

**Following the meteorological modeling performance evaluation, the next step in the modeling**  **process was to verify the actual air quality model’ s performance in terms of its ability to predict th**  **e ozone in the right locations and at the right levels. To**  **do this, the actual base year model predictions we re**  **compared to the ambient data observed in the histor ical season (2002). The methodology in this type o**  **f verification involved a combination of statistical**  **and graphical evaluations, with the goal of determi ning** **30**

**if the air quality model appears to be reproducing ozone trends in the right locations for the right r**  **easons. If this goal is met, then the model can reasonably**  **be used as a predictive tool in evaluating various control**  **strategies and their effects on ozone.**

**The key statistical measures used to evaluate CMAQ air quality model performance for the**  **Metrolina Area attainment demonstration are as foll ows:** 

**1. Comparison of modeled mean of ozone to the ob served mean of ozone. This metric is an**  **evaluation of how, on average across the modeling p eriod, the model compares to the observed values.** 

**2. Bias in the model, calculated by taking the d ifference between the modeled mean and the**  **observed mean.**

**3. Normalized bias, calculated by taking the bia s for each observation/prediction pair, and then**  **dividing by the number of pairs that are used in th e calculations. The USEPA recommends that**  **normalized bias fall between ± 5 – 15 percent.**

**4. Gross error. For the entire modeling domain, gross error for all pairs above 60 parts per**  **billion (ppb) of ozone was calculated. For the Met rolina nonattainment area, the gross error was**  **calculated on the daily 8-hour ozone maximums. The USEPA’s Attainment Guidance suggests that gross**  **error can be interpreted as precision of the model. This metric is typically used to compare various**  **modeling applications. USEPA recommends that the g ross error of all pairs >60 ppb be less than 30-35**  **percent.**

**These statistics will be presented in the sections that follow for the entire 12-km VISTAS/ASIP**  **modeling domain, then, specifically, for the Metrol ina nonattainment area.** 

**In addition to statistical methods, model performa nce was evaluated by reviewing spatial and time**  **series plots of the modeled versus observed data. These graphical plots aided in gaining a better**  **understanding of how the model performed across the entire modeling domain.** 

**Only the model performance evaluation for the 12-k m grid domain will be discussed in the**  **subsections to follow. For the full model performa nce evaluation for both the 36-km and 12-km grid**  **domains, please refer to Appendix J.**

A. Domain-Wide Performance

**As a first-line screening of overall CMAQ model pe rformance, 8-hour ozone statistical metrics were**  **calculated for the 12-km domain for the VISTAS/ASIP states, North Carolina, and South Carolina**  **(presented in Table III-1). The mean normalized bi as was well within the recommended ± 5 - 15 percent**  **for the entire "core ozone" season (May through Sep tember). The individual monthly statistics for**  **August and September in North and South Carolina, h owever, showed a mean normalized bias slightly**  **outside the suggested range. This suggests an unde r prediction of ozone by the model toward the end o**  **f the summer. However, the SCDHEC does not believe t**  **his slight under prediction for August and September impacts the overall modeling results. Th**  **e mean normalized gross error was significantly below the 30-35 percent range at the 60 ppb thresho**  **ld for all regions across the domain. 31**  Table III-1: 12-km Domain Model Statistics for 8-H our Ozone

Region/Month Modeled

Mean (ppb) Observed

Mean (ppb) Mean Bias

(ppb) Mean

Normalized Bias (%) Mean

Normalized Gross Error (%) **ASIP States combined May 61.26 67.69 -6.44 -8.96 12.47**  **June 62.62 70.99 -8.37 -11.37 14.02 July 62.73 70.85 -8.12 -10.90 14.74**  **August 61.33 72.57 -11.24 -14.92 16.98 September 60.81 71.98 -11.17 -14.98 17.07**  Mean (May-September) 61.75 70.82 -9.07 -12.23 15.06 **North Carolina May 64.06 69.05 -5 -6.86 10.76**  **June 62.21 71.82 -9.62 -13.03 14.47 July 62.94 72.10 -9.16 -12.09 14.63**  **August 60.60 73.92 -13.33 -17.40 18.34 September 57.90 69.37 -11.46 -16.11 17.68**  Mean (May-September) 61.54 71.25 -9.71 -13.10 15.18 **South Carolina May 63.87 67.71 -3.85 -5.31 9.66**  **June 61.95 70.92 -8.97 -12.10 13.52 July 60.89 70.24 -9.35 -12.73 14.75**  **August 59.77 71.39 -11.62 -16.03 16.64**

**September 61.18 72.62 -11.44 -15.22 16.32**

Mean (May-September) 61.53 70.58 -9.05 -12.28 14.18

1. Spatial Plots

**Overall, the model performed well with the spatial extent of higher ozone concentrations. There is,**  **however, a slight under-prediction of the ozone in the model, most notably in the 1-hour ozone plots.**  **As expected, higher ozone concentrations are seen in t**  **he urban areas. In general, the SCDHEC believes th e**  **model does an acceptable job capturing the spatial distribution and concentrations of ozone in the**  **Metrolina area. Appendix J shows all of the domain -wide spatial plots of modeled 1-hour and 8-hour**  **maximum ozone with the observations, overlaid for t he days used in the relative response factor (RRF)**  **calculations. Only representative days are display ed below in Figure III-1 through Figure III-7.** **32**

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

(bottom) ozone concentrations for May 25, 2002.**33**

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

(bottom) ozone concentrations for June 3, 2002.**34**

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

(bottom) ozone concentrations for June 12, 2002.**35**

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

(bottom) ozone concentrations for July 3, 2002.**36**

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

(bottom) ozone concentrations for July 17, 2002.**37**

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

(bottom) ozone concentrations for August 2, 2002.**38**

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

(bottom) ozone concentrations for August 10, 2002.**39**

2. Scatter Plots

**The SCDHEC and the NCDAQ are most concerned about how the model performed for North and**  **South Carolina, primary to the entire 12-km VISTAS/ ASIP domain. For this reason, the scatter plots**  **below are for the Carolinas only, with the domain-w ide scatter plots found in Appendix J. The model**  **performance scatter plots of "model-predicted" vers us "observed" for 1-hour and 8-hour ozone have been**  **compiled for each month used in the attainment test (May through September of 2002). Only the 8-hour**  **ozone scatter plots for the three months (June thro ugh August), in which the majority of the modeled d**  **ays used in the relative response factor, are shown. A**  **lthough there are some outliers, the overall model performance was good for the 2002 ozone season, wit**  **h the majority of the points falling within acceptable limits.** 

a. North Carolina Scatter Plots

**Since the majority of the Metrolina Area is in Nor th Carolina, scatter plots for the North Carolina**  **domain are shown first, in Figure III-8 through Fig ure III-10 below. These scatter plots show 8-hour**  **ozone for June, July, and August for all of the mon itoring sites in North Carolina only (York, SC**  **omitted). The 1-hour ozone scatter plots and the r emaining 8-hour ozone scatter plots for North Carol**  **ina can be found in Appendix J. Overall, for the North**  **Carolina monitoring sites the model performance is good. Although there are some days where over-pred**  **ictions and under-predictions are observed, in general most days fall within acceptable ranges of**  **the 1:1 line.**

Figure III-8: 8-hour ozone scatter plot for North Carolina 12-km grid for June 2002.**40**

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

Figure III-10: 8-hour ozone scatter plots for Nort h Carolina 12-km grid for August 2002.**41**

b. South Carolina Scatter Plots

**Figure III-11 through Figure III-13 display the sc atter plots for 8-hour ozone for June, July and**  **August for all of the monitoring sites in South Car olina (even though the York County, SC portion of t**  **he Metrolina Area is evaluated in most cases as a part**  **of North Carolina proper). The 1-hour ozone scatt er**  **plots and the remaining 8-hour ozone scatter plots can be found in Appendix J. Overall, the model**  **performance is good for the South Carolina monitori ng sites, including York. Again, although there ar**  **e some days where over-predictions and under-predicti**  **ons are observed, in general most days fall within acceptable ranges of the 1:1 line.** 

Figure III-11: 8-hour ozone scatter plots for Sout h Carolina 12-km grid for June 2002.**42**

Figure III-12: 8-hour ozone scatter plots for Sout h Carolina 12-km grid for July 2002.

Figure III-13: 8-hour ozone scatter plots for Sout h Carolina 12-km grid for August 2002.**43**

3. Time Series Plots

**Following are 8-hour time series plots from the 12 -km domain for the North Carolina monitors for**  **June through August. The time series presents the** **observed values [displayed as black asterisks (*)]** **and the predicted values (displayed as green lines) by**  **month. The 1-hour and 8-hour ozone time series plo ts**  **for the ASIP region, North Carolina, and South Caro lina (including York) can be found in Appendix J.** 

**The model predicts the overall diurnal pattern wel l; however, it tends to under-predict peak values**  **and over-predict minimum values. In particular the last few days of August shows the model not**  **handling the prediction of the absolute value of oz one well. Overall, the model is within acceptable**  **tolerances for model performance.**

Figure III-14: Time series plot of model predicted versus mean 8-hour observed for North Carolina monitors for June 2002.**44**

Figure III-15: Time series plot of model predicted versus mean 8-hour observed for North Carolina monitors for July 2002.

Figure III-16: Times series plot of model predicte d versus mean 8-hour observed for North Carolina monitors for August 2002

4. Domain-Wide Summary

**Overall, the SCDHEC believes that the VISTAS/ASIP CMAQ model performance across the** **45**

**domain and throughout the ozone season is good. Fo r the most part, mean normalized bias and mean**  **normalized gross error fall within the recommended limits for good model performance. The model**  **seems to do a good job capturing ozone concentratio ns through various episode ramp-up and clean-out**  **cycles. There are some instances of under- and ove r-predictions, but, as the scatter plots show, most**  **of the time, the model does well simulating the aftern**  **oon ozone peak throughout the Carolinas. The SCDHEC believes that the model performance is well**  **within the limits of acceptable performance established in the USEPA’s Attainment Guidance and**  **produces results reliable enough for use in the Metrolina Area attainment demonstration.** 

B. Area and Monitor Statistics

**Table III-2 displays the model performance statist ics comparing the modeled 8-hour ozone mean and**  **the observed 8-hour ozone mean at each monitor in t he Metrolina area, as well as the combined statisti**  **cs for all of the monitors in the Metrolina area. The**  **statistics represent the May through September ("c ore**  **ozone season") time period.**

Table III-2: Metrolina Nonattainment Area Monitor Statistics

**Monitor Modeled Mean** 

**(ppb) Observed** 

**Mean (ppb) Mean Bias** 

**(ppb) Mean** 

**Normalized Bias (%)**  **Mean**

**Normalized Gross Error**  **(%)**
Metrolina Area 65.25 73.00 -7.875 -10.152 13.289 **Crouse 69.0 73.0 -4.0 -5.330 9.868 County Line 67.0 74.0 -7.0 -8.807 11.885**  **Garinger (Plaza) 63.0 73.0 -11.0 -14.470 16.125 Arrowood 67.0 72.0 -5.0 -5.837 12.249**  **Enochville 65.0 75.0 -9.0 -11.790 13.710 Rockwell 65.0 73.0 -9.0 -10.989 13.322** 
**Monroe 62.0 72.0 -10.0 -13.097 14.958** **York County, SC* 64.0 72.0 -8.0 -10.898 14.197** ***Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area**

**The USEPA recommends that the combined mean normal ized bias fall within ± 5-15 percent and the**  **combined mean normalized gross error not exceed the 30-35 percent range. For a specific monitor, it i**  **s recommended that the mean normalized bias fall with**  **in ± 20 percent. The table above shows the VISTAS/ASIP CMAQ modeling demonstrated that the mea**  **n bias, mean normalized bias, and mean normalized gross error were all within recommended**  **and accepted ranges.**

**A slight under-prediction of 8-hour ozone was also observed at this more refined level of analysis**  **and was similar to what was seen at the larger stat e and VISTAS/ASIP region levels. Individual monthl**  **y statistics are not presented here due to the very l**  **imited number of modeled and observed data pairs at only**  **the eight Metrolina Area ozone monitoring sites. W hole season statistics are more representative of h**  **ow this air quality modeling will be applied in the mo**  **deled attainment test discussed in Appendix L. Acr oss**  **the whole season, the Metrolina Area as a whole, as well as the individual ozone monitoring sites, sho**  **wed a mean normalized bias within the suggested ± 5-15**  **percent range. Additionally, mean normalized gross 46** 

**error fell within the suggested 30-35 percent range given a 60 ppb threshold.** **47**

SECTION IV. CONTROLS APPLIED

**Several control measures already in place or being implemented over the next few years will reduce**  **stationary point, highway mobile, and nonroad mobil e sources emissions. The Federal and State control**  **measures were modeled for all of the future years a nd are discussed in the sections below.** 

A. Federal Control Measures

1. Tier 2 Vehicle Standards

**Federal Tier 2 vehicle standards will require all passenger vehicles in a manufacturer’s fleet,**  **including light-duty trucks and Sport Utility Vehic les (SUVs), to meet an average standard of 0.07 gra**  **ms of NO** 
**x per mile. Implementation began in 2004, and shoul**  **d be completely phased in by 2007. The Tier 2 standards will also cover passenger vehicles over**  **8,500 pounds gross vehicle weight rating (the larg er**  **pickup trucks and SUVs), which are not covered by t he current Tier 1 regulations. For these vehicles,**  **the standards will be phased in beginning in 2008, with**  **full compliance in 2009. The new standards requir e**  **vehicles to be 77% to 95% cleaner than those on the road today. The Tier 2 rule also reduced the sulf**  **ur content of gasoline to 30 ppm starting in January o**  **f 2006. Most gasoline sold in South Carolina prior to**  **January 2006 had a sulfur content of about 300 ppm. Sulfur occurs naturally in gasoline but interfere**  **s with the operation of catalytic converters on vehic**  **les, resulting in higher NO**
**x emissions. Lower-sulfur**  **gasoline is necessary to achieve the Tier 2 vehicle emission standards.** 

2. Heavy-Duty Gasoline and Diesel Highway Vehicle s Standards

**New USEPA standards designed to reduce NO**
**x and VOC emissions from heavy-duty gasoline and**  **diesel highway vehicles commenced implementation in 2004. A second phase of standards and testing**  **procedures, which begins in 2007, is reducing parti culate matter from heavy-duty highway engines and**  **has reduced highway diesel fuel sulfur content to 1 5 ppm. The total program for these new engines usi**  **ng low sulfur diesel is expected to achieve a 90% redu**  **ction in particulate matter (PM) emissions and a 95 %**  **reduction in NO**
**x**

**emissions (as compared to existing engines using h igher-content sulfur diesel).** 

3. Large Nonroad Diesel Engines Rule

**In May 2004, the USEPA promulgated new rules for l arge 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 sulf**  **ur in nonroad diesel fuel by over 99%. Nonroad die sel**  **fuel currently averages about 3,400 ppm sulfur. Th e rule limits nonroad diesel sulfur content to 500**  **ppm in 2006 and 15 ppm in 2010. The combined engine an**  **d fuel rules would reduce NO**
**x and PM emissions**  **from large nonroad diesel engines by over 90% (as c ompared to current nonroad engines using higher**  **content sulfur diesel).**

4. Nonroad Spark-Ignition Engines and Recreationa l Engines Standard

**The new standard, effective in July 2003, regulate s NO**  **x , HC, and CO for groups of previously**  **unregulated nonroad engines. The new standard will apply to all new engines imported into or sold**  **within the United States after these standards begi n and will apply to large spark-ignition engines**  **(forklifts and airport ground service equipment), r ecreational vehicles (off-highway motorcycles and a**  **ll terrain-vehicles), and recreational marine diesel e**  **ngines. The regulation varies based upon the type of**  **engine or vehicle.**

**The large spark-ignition engines contribute to ozo ne formation and ambient CO and PM levels in** **48**

**urban areas. Tier 1 of this standard was implement ed in 2004, and Tier 2 is scheduled to start in 200**  **7. Like the large spark-ignition, recreational vehicle**  **s contribute to ozone formation and ambient CO and PM**  **levels. For all model-year 2006 off-highway motorc ycles and all-terrain-vehicles, the new exhaust**  **emissions standard was phased-in at 50%; for model years 2007 and later, the standard will be phased-i**  **n at 100%. Recreational marine diesel engines over 3**  **7 kilowatts (used in yachts, cruisers, and other ty pes**  **of pleasure craft) contribute to ozone formation an d PM levels, especially in marinas. For certain**  **recreational marine diesel engine sizes, the standa rd began to be phased-in in 2006.** 

**When all of the nonroad spark-ignition engines and recreational engines standards are fully**  **implemented, overall reductions of 72% in HC, 80% i n NO**  **x , and 56% in CO emissions are expected by**  **2020. These controls will help reduce ambient conc entrations of ozone, CO, and fine PM.** 

5. NOx SIP Call in Surrounding States

**In October 1998, the USEPA made a finding of signi ficant contribution of NO** 
**x emissions from**  **certain states and published a rule that set ozone season NO**  **x budgets for the purpose of reducing regional**  **transport of ozone (63 FR 57356). This rule, refer red to as the NO** 
**x**

**SIP Call, called for ozone season controls to be put on utility and industrial boiler**  **s, as well as internal combustion engines in 22 sta tes in**  **the Eastern United States. A NO**
**x emissions budget was set for each state, and the s**  **tates were required to develop rules that would allow their respective sta**  **tes to meet their budgets. A NO**
**x trading program was**  **established, allowing sources to buy credits to mee t their NO** 
**x budgets as opposed to actually installing**  **controls. The emission budgets were to be met by t he beginning of 2004. Even with the trading progra**  **m, the amount of ozone season NO** 
**x emissions has decreased significantly in and aroun**  **d North and South Carolina.** 

6. Clean Air Interstate Rule

**On May 12, 2005, the USEPA promulgated the “Rule T o Reduce Interstate Transport of Fine**  **Particulate Matter and Ozone (Clean Air Interstate Rule); Revisions to Acid Rain Program; Revisions to**  **the NO**
**x SIP Call,” referred to as CAIR. This rule establi**  **shed the requirement for states to adopt rules limiting the emissions of NO** 
**x and sulfur dioxide (SO**  **2 ) and established a model rule for the states to us**  **e in developing their rules. The purpose of the CAIR**  **is to reduce interstate transport of precursors to fine**  **particulate and ozone. The CAIR applies to: (1) a ny stationary, fossil-fuel-fired boiler or stationa**  **ry, fossil-fuel-fired combustion turbine serving at any**  **time, since the start-up of a unit’s combustion chamber, a generator with nameplate capacity of mor**  **e than 25 MWe producing electricity for sale; and (2) for a unit that qualifies as a cogeneration uni**  **t during the 12-month period starting on the date t hat the**  **unit first produces electricity and continues to qu alify as a cogeneration unit, a cogeneration unit s**  **erving at any time a generator with nameplate capacity of**  **more than 25 MWe and supplying in any calendar year more than one-third of the unit’s potential electri**  **c output capacity or 219,000 MWh, whichever is grea ter,**  **to any utility power distribution system for sale. This rule provide annual state caps for NO** 
**x and SO**  **2 in**  **two phases, with the Phase I caps for NO**
**x and SO**  **2 starting in 2009 and 2010, respectively. Phase II**  **caps become effective in 2015. The USEPA is allowing th**  **e caps to be met through a cap and trade program if a state so chooses to participate in the program.** 

B. State Control Measures

1. New Source Review Regulations**49**

**On December 31, 2002, the USEPA finalized revision s governing the New Source Review (NSR)**  **program. The major NSR program is a preconstructio n review and permitting program applicable to new**  **or modified major stationary sources of air polluta nts. In areas not meeting health-based NAAWS, the**  **program is referred to as the Prevention of Signifi cant Deterioration (PSD) program. Collectively, th**  **ese programs are commonly referred to as the major NSR**  **program.**

**In accordance with USEPA’s final rule revisions, s tate agency programs must adopt and submit**  **revisions to their SIPs to include the minimum prog ram elements outline in the final rules. States ma**  **y choose to adopt provisions that differ from the fin**  **al rules; however, to be approvable under the SIP, the**  **state must show that the regulations is at least as stringent as USEPA’s amendments.** 

**After a lengthy stakeholder process, SCDHEC submit ted revisions to the Legislature in January 2005**  **to comply with the USEPA requirements. The revisio ns adopted by SCDHEC differ from the federal**  **revisions in several key respects and have the effe ct of being more stringent than the federal rules.**  **These revisions were approved by the General Assembly and**  **became state-effective upon publication in the** State Register

**on June 24, 2005. The final regulations promulgat ed amendments to regulations R. 61-**  **62.1,** Definitions and General Requirements **, and R. 61-62.5, Standard No. 7,** Prevention of Significant Deterioration **, and also promulgated a new regulation, R. 61-62.5 , Standard No. 7.1,**  Nonattainment New Source Review

**.**
a. South Carolina Air Pollution Control Regulation R. 61-62, Definitions and General Requirements , Section II - Permit Requirements

**This regulation implements a program for the minor new source review permitting program, which**  **enhances the State’s prevention of significant dete rioration of air quality initiatives.** 

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

**This regulation implements a program for the preve ntion of significant deterioration of air quality f**  **or sources located in or whose construction is propose**  **d in an unclassifiable/attainment area of the State**

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

**This regulation implements a program whereby sourc es located in or whose construction is proposed**  **in nonattainment areas are subject to the requireme nts of R. 61-62.5, Standard No. 7.1** 

2. NO x

Regulations

**These regulations specify the requirements for con trolling NO** 
**x and for demonstrating compliance**  **with NO**
**x limitations and the NO** 
**x SIP Call.** 

a. South Carolina Air Pollution Control Regulatio n R. 61-62.5, Standard No. 2 - Ambient Air Quality Standards

**This regulation contains the State of South Caroli na ambient air quality standards, which have**  **recently been amended to include the 8-hour ozone s tandards.** 

b. South Carolina Air Pollution Control Regulation R. 61-62.5, Standard No. 5.2 - Control of Oxides of Nitrogen (NO x )**50**

**This regulation contains the NO**
**x control standards applicable to affected stationary**  **sources that emit or have the potential to emit NO** 
**x generated from fuel combustion.** 

c. South Carolina Air Pollution Control Regulati on R. 61-62.96 - Nitrogen Oxides (NO x ) Budget Trading Program

**On October 27, 1998, the USEPA finalized a Nitroge n Oxides (NO** 
**x ) State Implementation Plan**  **(SIP) Call Rule. The NO**
**x SIP Call was designed to reduce the regional trans**  **port of ground-level ozone through reductions in NO** 
**x from electric-generating unit (EGU) rouces and fro**  **m some non-EGU sources. The rule requires that, beginning in 2004, NO** 
**x reductions must occur during ground-level ozone se**  **ason in states whose NO** 
**x**

**emissions have been identified as contributing to 1-hour ozone standard nonattainment**  **in “downwind” states. The rule also requires state s to identify pollution-reduction measures and deve**  **lop a plan to achieve these reductions.** 

**Each state subject to the NO**
**x SIP Call regulation has a NO** 
**x budet that the state allocates to**  **applicable sources. The budget is based on cost-ef fective reductions in emissions that can be achieve**  **d by the affected sources. South Carolina’s state tradi**  **ng program budget, as specified in R. 61-62.96, Nit rogen**  **Oxides (NO**
**x ) Budget Trading Program, is 19,678 tons. The NO** 
**x SIP Call regulation will be repealed**  **after 2009 upon implementation of the Clean Air Int erstate Rule.** 

d. South Carolina Air Pollution Control Regulati on R. 61-62.99 - Nitrogen Oxides Budget Program Requirements for Stationary Sources Not in the Trading Program

**This regulation details requirements for controlli ng NO**  **x emissions from cement manufacturing.** 

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

**The revision of R. 61-62.2,** Prohibition of Open Burning **, includes a ban of certain open burning during the ozone season for additional control of N**  **O x**  **emissions.**

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

**This regulation contains requirements for controll ing VOCs.** 

4. Other State Control Measures

a. Clean Air Interstate Rule (CAIR)

**On March 10, 2005, the USEPA finalized the Clean A ir Interstate Rule, also referred to as CAIR.**  **On May 12, 2005, CAIR was published in the** Federal Register **. CAIR affectes 28 states and the District of Columbia, whose emissions of sulfur dioxide (SO**  **2 ) and/or NO** 
**x produced by EGU sources and some**  **non-EGU sources contribute significantly to the non attainment of the National Ambient Air Quality**  **Standards (NAAQS) for fine particles (PM 2.5**  **) and/or 8-hour ozone in downwind states. (SO 2**  **and NO**
**x are**  **both precursors to ground-level ozone formation, an d NO** 
**x is also a precursor to PM**  **2.5 formation.) The**  **USEPA has determined that EGU sources in South Caro lina are affecting the nonattainment of ozone and**  **PM 2.5**  **standards in downwind states. CAIR is a cap-and-tr ade program for NO** 
**x and SO**  **2 emissions from**  **affected facilities and has two phases of implement ation. The caps for the phases are as follows:** **51**

**Phase I, which begins in 2009 for NO**
**x (annual and ozone season) and 2010 for SO**  **2 CAIR NO**  **x annual cap = 32,662 tons (T)**  **CAIR EGU SO 2**  **annual cap = 57,271 T CAIR NO**  **x ozone season cap = 15,249 T** 

**Phase II, which begins in 2015 for both pollutant s**  **CAIR NO x**  **annual cap = 27,219 T CAIR EGU SO**  **2 annual cap = 40,089 T**  **CAIR NO x**  **ozone season cap = 12,707 T**

**CAIR was due for submission to the USEPA for appro val on September 11, 2006. South Carolina is**  **one of many states that did not meet this deadline because of a lengthy regulatory process. SCDHEC is**  **working closely with USEPA Region IV toward impleme ntation of the state’s rule. SCDHEC has**  **adopted the federal CAIR with modifications in area s where the state has flexibility. A Notice of Dra**  **fting was published in the State Register on July 22, 200**  **5; a second Notice of Drafting was published in the** State Register

**on February 24, 2006. The initial approval to pro ceed with the proposed regulation was**  **given by the SCDHEC Board on September 14, 2006. T he Notice of Proposed Rule was first published**  **in the** State Register

**on October 27, 2006. A public hearing before the SCDHEC Board was held on**  **January 11, 2007. On January 22, 2007, the propose d regulation was submitted to the South Carolina**  **Legislature for approval. On March 8, 2007, SCDHEC submitted a request to USEPA Region 4 for**  **parallel processing. South Carolina’s CAIR was sta te-effective upon publication in the State Register**  **on June 22, 2007. A final state-version of CAIR was s**  **ubmitted to the USEPA on August 16, 2007.**

b. Permitting Requirements Involving Emission Of fsets - Conditions for Approval

**If SCDHEC finds that the major stationary source o r major modification would be constructed in an**  **area designated in 40 CFR 81.341 as nonattainment f or a pollutant for which the stationary source or**  **modification is major, approval may be granted only if the following conditions are met:** 

**(A) The major stationary source or major modificat ion is required to meet an emission limitation**  **which specifies the lowest achievable emission rate (LAER) for such source.** 

**(B) The applicant must certify that all existing m ajor sources owned or operated by the applicant (or**  **any entity controlling, controlled by, or under com mon control with the applicant) in the same State a**  **s the proposed source are in compliance with all applicab**  **le emission limitations and standards under the Cle an**  **Air Act (or are in compliance with an expeditious s chedule which is Federally-enforceable or contained**  **in a court decree).** 

**(C) The owner or operator of the proposed new majo r stationary source or major modification will**  **obtain sufficient emission reductions of the nonatt ainment pollutant from other sources. Emission**  **reductions shall be in effect and enforceable prior to the date the new source or modification commenc**  **es operation. The emission reductions shall be obtaine**  **d in accordance with the following provisions:**

**(1) Where the permitted emissions limit allows gr eater emissions than the potential to emit of**  **the source, emissions offset credit will be allowed only for control below this potential;** 

**(2) For an existing fuel combustion source, credi t shall be based on the allowable emissions for**  **the type of fuel being burned at the time the appli cation to construct is filed. If the existing sourc**  **e commits to switch to a cleaner fuel at some future**  **date, emissions offset credit based on the allowabl e (or**  **actual) emissions for the fuels involved is not acc eptable, unless the permit is conditioned to requir**  **e the 52** 

**use of a specified alternative control measure whic h would achieve the same degree of emissions**  **reduction should the source switch back to a dirtie r fuel at some later date.** 

**(3) (a) Emissions reductions achieved by shutting down an existing source or curtailing**  **production or operating hours below baseline levels may be generally credited if such reductions are**  **permanent, quantifiable, federally enforceable, occ urred on or after the date of the most recent emiss**  **ions inventory, and if the area has an EPA-approved atta**  **inment plan.**

**(b) Such reductions may be credited if the shutd own or curtailment occurred on or after the**  **date the new source permit application is filed, or , if the applicant can establish that the proposed**  **new source is a replacement for the shutdown or curtail**  **ed source, and the cutoff date provision of paragra ph**  **(d)(C)(iii)(a) of Standard 7.1 are observed.**

**(4) No emissions credit may be allowed for replac ing one hydrocarbon compound with another**  **of lesser reactivity, except for those compounds li sted in Table 1 of EPA's "Recommended Policy on**  **Control of Volatile Organic Compounds" (42 FR 35314 , July 8, 1977);** 

**(5) All emission reductions claimed as offset cre dit shall be federally enforceable;** 

**(6) Location of offsetting emissions. Emission of fsets shall be obtained from sources currently**  **operating within the same designated nonattainment area as the new or modified stationary source.**  **Emission offsets may be obtained from another nonat tainment area with the Department's approval only**  **if: (a) The other area has an equal or higher nonatt**  **ainment classification than the area in which the proposed source is located; and,** 

**(b) Emissions from the other area contribute to a violation of the NAAQS in the**  **nonattainment area in which the source is located.**

**(7) Emission offsetting ratios. Emission offsets shall be required in nonattainment areas in**  **accordance with the following provisions:**

**(a) Emissions for carbon monoxide (CO), nitrogen dioxide (NO**  **2 ), sulfur dioxide (SO**  **2 ),**  **lead (Pb), particulate matter (PM 10**  **and PM 2.5**  **) nonattainment areas shall be offset at a ratio gr eater than** 
**one to one.**

**(b) Emissions for ozone nonattainment areas shal l be offset for volatile organic compounds**  **(VOCs) and nitrogen oxides (NO**
**x ) in accordance with the following table:** 

**(8) Credit for an emissions reduction can be clai med to the extent that the Department has not**  **relied on it in issuing any permit under regulation s approved pursuant to 40 CFR part 51 subpart I or**  **the Department has not relied on it in demonstrating at**  **tainment or reasonable further progress. 53** 

**(9) Decreases in actual emissions resulting from the installation of add-on control technology or**  **application of pollution prevention measures that w ere relied upon in designating an emissions unit as**  **a Clean Unit or a project as a PCP cannot be used as**  **offsets.**

**(10) Decreases in actual emissions occurring at a Clean Unit cannot be used as offsets, except as**  **provided in paragraphs (f)(8) and (g)(10) of Regula tion 61-62.5, St. No. 7.1. Similarly, decreases in**  **actual emissions occurring at a PCP cannot be used as offs**  **ets, except as provided in paragraph (h)(6)(iv) of Regulation 61-62.5, St. No. 7.1.** 

**(11) The total tonnage of increased emissions, in tons per year, resulting from a major**  **modification that must be offset in accordance with section 173 of the Clean Air Act shall be determin**  **ed by summing the difference between the allowable emi**  **ssions after the modification (as defined by paragraph (b)(3) of Regulation 61-62.5, St. No. 7.1**  **) and the actual emissions before the modification (as**  **defined in paragraph (c)(1) of Regulation 61-62.5, St. No. 7.1) for each emissions unit.** 

**(D) The emission offsets must provide a positive n et air quality benefit in the affected area as**  **determined by 40 CFR 51, Appendix S, Emission Offse t Interpretative Ruling.** 

**(E) Alternative Sites Analysis. An analysis of alt ernative sites, sizes, production processes, and**  **environmental control techniques for such proposed source demonstrates that benefits of the proposed**  **source significantly outweigh the environmental and social costs imposed as a result of its location,**  **construction, or modification shall be required.**

5. Emissions Inventory: South Carolina Regulation R. 61-62.1, Definitions and General Requirements , Section III - Emissions Inventory

**This regulation requires the submittal of emission s inventory information by affected sources.** 

6. Reasonably Available Control Measures (RACM)

**Reasonably Available Control Measures is a broadly defined term referring to technologies and other**  **measures that can be used to control pollution; inc ludes Reasonably Available Control Technology (see**  **Appendix R - RACT SIP) and other measures.**

**EPA's final 8-hour ozone implementation rule in 40 CFR 51.912(d), pursuant to section 172(c)(1) of**  **the CAA, requires the attainment demonstration SIP submittal to include "a SIP revision demonstrating**  **that it has adopted all RACM necessary to demonstra te attainment as expeditiously as practicable and t**  **o meet any RFP requirements." In addition, EPA's RAC**  **M policy indicates that areas should consider all candidate measures that are potentially available,**  **including any that have been suggested for the particular nonattainment area. Although areas shoul**  **d consider all available measures, areas need only to**  **adopt measures if they are both economically and te chnologically feasible and will contribute to timel**  **y attainment or are necessary for RFP. Measures that**  **might be available but would not advance attainmen t**  **or contribute to RFP need not be considered RACM.**

a. Reasonably Available Control Technology (RACT)

**The case-by-case RACT analysis for existing source s located in the ozone nonattainment area with**  **the potential to emit greater than 100 tons per yea r of NO** 
**x and/or VOC is found in Appendix R - RACT**  **SIP. In the York County portion of the nonattainme nt area, there are no VOC sources subject to CTGs.** 

b. Early Action Compacts**54**

**On August 22, 2002, DHEC published a Notice of Dra fting in the**  State Register **announcing its intent to pursue Early Action Compacts (EAC) for th**  **e 8-hour ozone standard. Through the EAC process, local, state, and EPA officials commit to working t**  **ogether to develop and implement plans that will reduce ozone pollution so that areas are attaining**  **the 8-hour ozone standard earlier than would be req uired**  **by the Clean Air Act. Only areas that are attaining the 1-hour ozone standard are eligible to particip**  **ate in the EAC process. The compact requires these areas**  **to attain the 8-hour ozone standard by December 31, 2007, a date that is sooner than would otherwise be**  **required through the traditional nonattainment designation process.** 

**At the end of 2002, 45 of South Carolina's 46 coun ties, SCDHEC, and USEPA Region 4 had signed**  **compacts to implement ozone reduction strategies ea rlier than federally required. Statewide stakehold**  **er groups involving local and federal governments, ind**  **ustry, environmental groups, and other interested parties have worked together to plan and implement**  **strategies for ozone pollution prevention throughou t**  **the state. Plans involve mobile source pollution re duction, outreach actions, and point source prevent**  **ion, which provide flexibility and foster "homegrown" so**  **lutions.**

**The most important reasons for moving forward in t his proactive manner are the public health**  **benefits realized by meeting the new standard soone r than required and also the deferral of the effect**  **ive date of a nonattainment designation.** 

**As part of this process, the EAC stakeholders deve loped statewide regulations aimed at achieving**  **additional reductions in ozone precursors. One new regulation that was developed as part of this proc**  **ess was South Carolina Air Pollution Control Regulation**  **R. 61-62.5, Standard 5.2,** Control of Oxides of Nitrogen (NO

x ) **. This is a broad-based regulation that applies sta tewide to new and existing stationary**  **sources that emit NO**
**x**

**from fuel combustion and have not undergone a best available control technology**  **(BACT) analysis for NO**
**x . For new sources, the regulation requires the ins**  **tallation of control technology that is based on BACT standards found in the RACT/B**  **ACT/LAER clearinghouse. For existing sources, the regulation only applies when an applicable unit**  **replaces their burner. At this point, they will b e**  **required to replace their burner with a low NO**
**x burner or equivalent technology capable of achievin**  **g a 30 percent reduction from uncontrolled levels.** 

**Also, as part of the EAC process, South Carolina A ir Pollution Control Regulation R. 61-62.2,**  Prohibition of Open Burning **, was revised by deleting the exception for the bur ning of household trash,**  **revising the exception for the burning of construct ion waste, and revising the exception for fires set**  **for the purpose of firefighter training. The burning of**  **household trash presents health and environmental concerns for many communities. The smoke generated**  **from these activities is a nuisance to some and a health threat to others with asthma or other respir**  **atory problems. With respect to the exception for t he**  **burning of construction waste, the regulation was r evised to allow only residential construction waste**  **to be burned outside the ozone season, and this will o**  **nly be allowed if it meets the provisions of the regulation. Finally, the exception for the purpose**  **of firefighter training was revised to ensure that minimum health, environmental, and safety concerns**  **are addressed.**

**These regulations were approved by the SCDHEC Boar d in January 2004, and, in accordance with**  **South Carolina law, they were subsequently submitte d to the Legislature for approval. The South**  **Carolina General Assembly approved the regulations, and the rules were published and became effective**  **upon publication in the** State Register **on June 25, 2004. In accordance with the EAC proce ss, SCDHEC**  **incorporated the statewide regulations and the loca l early action plans into the agency's Early Action**  **SIP revision and submitted it to the USEPA in December**  **2004, for review and approval.**

c. Take a Break from the Exhaust**55**

**Take a break from the exhaust (TABFTE) is an alter native commute initiative that uses a competitive**  **model in which points are assigned/ awarded for eac h action that is done to minimize air pollution. A**  **computer program is used by participants to report their actions and to record their daily points. Th**  **e web based program is available to state and local gover**  **nment, industry, and the public. The program track s**  **and calculates vehicle miles, determines emission r eductions, is free and requires no additional**  **equipment.**

**TABFTE was started by the SCDHEC Bureau of Air Qua lity in 2001 and is still being used by the**  **bureau staff. In 2003, it was awarded the Governor 's Pollution Prevention Award and became Internet**  **accessible. The program was expanded to other stat e agencies in 2004. The primary benefits of TABFTE**  **are reduced emissions from mobile sources and incre ased awareness of the impact of mobile sources on**  **air quality; it also encourages participants to tak e voluntary actions to help improve air quality.** 

d. Overall RACM Conclusions

**A number of emissions controls programs have been implemented in South Carolina since the Clean**  **Air Act Amendments of 1990, and substantial further emissions reductions will occur in the State as we**  **ll as the Metrolina area in 2007. SCDHEC intends to c**  **ontinue to investigate and, where appropriate, adop t**  **additional measures that would reduce emissions of ozone precursors even further. Such measures may**  **help the State in the future as it moves towards at tainment of the eight-hour ozone NAAQS. The source**  **categories emitting the vast preponderance of ozone precursor emissions in the State are already subje**  **ct to control requirements. South Carolina has adopte**  **d all of the above RACM and have since determined that there are no additional technologically and ec**  **onomically feasible control measures that would res ult**  **in South Carolina attaining the one-hour ozone NAAQ S earlier than 2007.** **56**

SECTION V. ATTAINMENT DEMONSTRATION

A. Attainment Test Introduction

**The modeled attainment test is the practice of usi ng air quality modeling results for baseline and**  **future years to determine if an area is expected to attain the NAAQS. For the 8-hour ozone NAAQS, the**  **baseline and future model estimates are used in a " relative" rather than an "absolute" sense. Specifi**  **cally, the ratio of the air quality model’s future to curr**  **ent predictions is calculated at each ozone monitor ing**  **site. These monitoring site-specific ratios are ca lled relative response factors (RRFs). Future ozon**  **e design values (DVFs) are then estimated at each mon**  **itor by multiplying the monitor-specific baseline ozone design value (DVB) by the modeled RRF for eac**  **h monitor. If all of the predicted monitor-specifi c**  **DVFs in a given area are less than or equal to 0.08 4 ppm, the attainment test is passed and the area i**  **s said to demonstrate attainment. Equation V-1 presents t**  **he modeled attainment test, applied at monitoring s ite**  **"x" as described in Section 4.0 of the USEPA’s** Attainment Guidance

**.**

Equation V-1 (Future Design Values):

**(DVF) = (RRF) x (DVB)**

**Where:**

**(DVB) = the baseline design value monitored at site "x" in ppm**  **= the average of the three design value period s which include the baseline**  **inventory year (i.e., the average of the 2000-2002, 2001-2003, and 2002-2004 design value periods for**  **the 2002 baseline inventory year).** 

**(RRF) = the ratio of the future 8-hr daily maxim um concentration predicted "nearby" a**  **monitor (averaged over each day of the episode) to the current 8-hr daily maximum concentration**  **predicted "nearby" the monitor (averaged over each day of the episode).** 

**(DVF) = the estimated future design value in ppm**

**.**

**It is important to consider an array of cells "nea rby" a monitor rather than focusing on the individu**  **al cell containing the monitor. This allows for varia**  **tions in the model performance where the peak ozone concentration occurs in a nearby grid cell rather t**  **han in the grid cell that contains the monitor.**

**The RRF is calculated by taking the ratio of the m ean future year modeling 8-hour ozone daily**  **maximum (averaged over all of the episode days) to the mean current year modeling 8-hour ozone daily**  **maximum "near" the monitor (averaged over all of th e episode days) (Equation V-2).** 

Equation V-2 (Relative Response Factors):

**RRF = (mean future yr. 8-hr daily max "near" moni tor "x")**  **(mean current yr. 8-hr daily max "near" monitor "x")** 

**The DVB, for purposes of the modeled attainment te st, is defined in the USEPA’s**  Attainment Guidance **as the average of the three design value periods t hat straddle the baseline inventory year (i.e.,** **57**

**the average of the 2000-2002, 2001-2003, and 2002-2 004 design value periods for a 2002 baseline**  **inventory year).**

B. Attainment Test Results

**As stated above, the attainment test is not based on absolute modeling results but, rather, relative**  **reductions of ozone and is only applied at the moni tors. However, reviewing the modeling results of h**  **ow the predicted ozone decreases in the future years a**  **nd how widespread the reductions are plays an impor t**  **role for the State in determining if additional con trols should be considered. The modeling results f**  **or each day used in the RRF calculations are available**  **in Appendix K. Additionally, discussions about ho w**  **this modeling demonstration meets the screening tes t for areas away from the monitoring sites and**  **additional matrices performed to support the attain ment test results are in Appendix L.** 

**The USEPA states that future design values (DVFs) that fall below 0.082 ppm demonstrate**  **attainment whereby little weight of evidence is nee ded. For monitors with DVFs between 0.082 ppm and**  **0.087 ppm, weight of evidence must be submitted tha t supports a demonstration of attainment. DVFs**  **greater than 0.085 ppm fail the attainment test.**

**Table V-1 lists the attainment test results for th e Metrolina nonattainment area. The first column i**  **s the monitoring site, followed by the base year desi**  **gn value discussed in Section V.A. The next series of**  **columns are the calculated RRF and the resulting DV F for the 2009 attainment year. Monitors with**  **DVFs that fall in the additional weight of evidence requirement appear in bold.** 

Table V-1: Attainment Test Results

**2009 Monitoring Site County**  **DVB (ppm) 5-year weighted**  **2000-2004 RRF**  **DVF (ppm)**  **Arrowood Mecklenburg 0.0847**  **0.892 0.075**  **County Line Mecklenburg 0.0973**  **0.874 0.085**  **Crouse Lincoln 0.0907**  **0.868 0.078**  **Enochville Rowan 0.0970**  **0.870 0.084**  **Garinger (Plaza) Mecklenburg 0.0953**  **0.883 0.084**  **Monroe Union 0.0870**  **0.884 0.076**  **Rockwell Rowan 0.0973**  **0.862 0.083**  **York York, SC*** **0.0830 0.861**  **0.071** ***Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area.**

C. Supporting Weight of Evidence

**As part of the weight of evidence determination, t he following analyses will be evaluated:**  **alternative DVF calculations, additional metrics of air quality modeling results, air quality modeling**  **results from other studies, positive trends in obse rved air quality and additional emissions reduction**  **s, and local measures that were not modeled. The weight o**  **f evidence determination is a supplement to the modeled attainment test and further supports that t**  **he area will attain the NAAQS for 8-hour ozone by June 15, 2010.** 

**The SCDHEC believes that the weight of evidence pr ovided in the sections below is strong evidence** **58**

**that the Metrolina nonattainment area will attain t he 8-hour ozone NAAQS by 2009.** 

1. Alternative DVF Calculation

**The USEPA recommends calculating the DVB by averag ing the three design value periods that**  **straddle the baseline inventory year. This methodo logy results in a center weighting of annual 4th hi**  **ghest ozone concentrations around the baseline inventory**  **year because the three design value periods average d**  **contain overlapping data. A weighted DVB can be si gnificantly affected by an abnormally hot/dry or**  **cool/wet year, if the year happens to be the center weighted year.** 

**To minimize potential impacts of any abnormal mete orological conditions while still considering**  **ozone conditions across a 5-year span, the NCDAQ an d the SCDHEC prefer an alternative DVB**  **calculation that does not weigh any of the years mo re than another but is the straight average of annu**  **al 4th highest ozone concentrations for the 5-year spa**  **n centered on the baseline inventory year.**

**This preferred DVB calculation is applied to the r emainder of the modeled attainment test equations**  **and the resulting DVFs are shown in Table V-2 at ea ch monitoring site in the Metrolina region.** 

Table V-2: 5-Year Average Alternative Attainment T est Results for 2009

**Monitoring Site County DVB**  **5-Year Straight Average**  **2000-2004 (ppm)**  **RRF DVF**  **(ppm)**

**Arrowood Mecklenburg 0.0834 0.892 0.074 County Line Mecklenburg 0.0956 0.874 0.083** 
**Crouse Lincoln 0.0892 0.868 0.077**
**Enochville Rowan 0.0944 0.870 0.082 Garinger (Plaza) Mecklenburg 0.0938 0.883 0.082** 
**Monroe Union 0.0846 0.884 0.074**
**Rockwell Rowan 0.0946 0.862 0.081** **York York, SC* 0.0798 0.861 0.068** ***Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area.**

**The alternative DVFs are slightly lower at each mo nitoring site compared to the attainment test**  **DVFs. These differences were expected as 2002 was an abnormally hot and dry year throughout the**  **Southeast, resulting in ozone concentrations that w ere higher than normal and that were much higher th**  **an in the surrounding years of 2000, 2001, 2003, and 2**  **004. Thus, the USEPA recommended DVB calculation weighted these abnormally-high air qual**  **ity conditions several times more than in the strai ght**  **average alternative DVB calculations. The NCDAQ an d the SCDHEC firmly believe that the straight**  **five-year average approach to the DVB calculation i s more appropriate and minimizes dramatic**  **fluctuations in meteorological and air quality cond itions from year to year.** 

**While none of the monitoring sites in the Metrolin a region had DVF values at or above 0.085 ppm** **59**

**using the straight average alternative DVB calculat ion, there are still three monitors that have DVFs**  **that fall between 0.082 and 0.087 ppm. This continues t**  **o indicate that some additional weight of evidence should be included to demonstrate attainment.** 

2. Additional Air Quality Modeling Metrics

**A series of five additional air quality modeling o utputs or metrics is recommended to provide**  **assurance the modeled attainment demonstration indi cates attainment. These metrics look at the relati**  **ve change between the baseline and future years modeli**  **ng and help to demonstrate how widespread the improvement in air quality is expected in the futur**  **e. These metrics include:**

**• The relative change in surface grid-hours great er than 0.084ppm. This is the number of grid cells**  **in a Metrolina region with predicted hourly 8-hour ozone concentrations greater than 0.084 ppm. The**  **relative change is the percent reduction from the b aseline year to the future year.** 

**• The relative change in the number of grid cells with predicted 8-hour daily maximums greater than**  **0.084 ppm. This metric uses the modeled daily maxi mum 8-hour ozone concentrations greater than 0.084**  **ppm. The relative change is the percent reduction from the baseline year to the future year.** 

**• The relative change in the sum of hourly predic tions greater than 0.084 ppm. This metric is the**  **sum of all grid cells with predicted hourly 8-hour ozone concentrations greater than 0.084 ppm. The**  **relative change is the percent reduction from the b aseline year to the future year.** 

**• The relative change in the sum of the predicted 8-hour daily maximums greater than 0.084 ppm.**  **This metric uses the modeled daily maximum 8-hour o zone concentrations greater than 0.084 ppm. The**  **relative change is the percent reduction from the b aseline year to the future year.** 

**• The change in the Air Quality Index (AQI) count s. The AQI counts metric is a count of the**  **number of grid cells with predicted maximum 8-hour ozone concentrations sorted within each of the colo**  **r codes as defined by the USEPA’s AQI.** 

**The USEPA recommended that these metrics should in dicate a reduction in ozone of 80% or more in**  **order to provide weight of evidence that an area wo uld attain the ozone NAAQS. The additional air**  **quality modeling metric analyses demonstrated reduc tions of greater than 85% for all metrics in the 20**  **09 attainment year for modeled days above the NAAQS in**  **the Metrolina nonattainment area. A full discussion of the metrics and the results can be fo**  **und in Appendix L.**

3. Air Quality Modeling Results From Other Studie s

**Another recommended weight of evidence analysis is to review other air quality modeling results**  **that included the Metrolina nonattainment area to d etermine how other modeling results compare to the**  **attainment demonstration. There are two air qualit y modeling studies for which results are available**  **for the Metrolina area.** 

**The first is the Early Action Compact (EAC) modeli ng that the NCDAQ and the SCDHEC**  **performed for the EAC areas within North and South Carolina. Since the modeling domain for this**  **analysis covered the majority of North and South Ca rolina, including the Metrolina nonattainment area,**  **the modeling results can be easily compared to the attainment demonstration. Although there are some**  **differences between the two modeling exercises, the modeling results for 2012 show all of the monitors**  **well below the 8-hour ozone NAAQS, with the highest monitor having a DVF of 0.081 ppm.** **60** Table V-3: Metrolina DVFs Based on EAC Modeling

**2012 Monitoring Site County**  **DVB (ppm)**  **RRF DVF**  **(ppm) Arrowood Mecklenburg**  **0.092 0.848**  **0.078 County Line Mecklenburg**  **0.101 0.802**  **0.081 Crouse Lincoln**  **0.092 0.826**  **0.076 Enochville Rowan**  **0.099 0.818**  **0.081 Garinger (Plaza) Mecklenburg**  **0.098 0.816**  **0.080 Monroe Union**  **0.088 0.795**  **0.070 Rockwell Rowan**  **0.100 0.800**  **0.080 York York, SC** * **0.086 0.844**  **0.073** ***Represents only that portion of the county that is located in the**  **Charlotte-Gastonia-Rock Hill, NC-SC nonattainment a rea.** 

**Another air quality modeling exercise that contain ed results for the Metrolina nonattainment area is**  **the USEPA’s modeling for the Clean Air Interstate R ule (CAIR). The Technical Support Document for**  **the final , dated March 2005, provided modeling res ults with and without the implementation for the .**  **These modeling results are listed in the table belo w.** 

Table V-4: Metrolina DVFs Based on USEPA’s Modeli ng

**DVF (ppb) County**  **DVB**

**(ppb) 2010 Base 2010**  **Lincoln 92.3**  **76.1 74.5**  **Mecklenburg 100.3**  **82.5 81.4**  **Rowan 99.7**  **81.3 80.1**  **Union 87.7**  **71.9 71.1**  **York, SC*** **83.3 70.0**  **68.5** ***Represents only that portion of the county that is located in the**  **Charlotte-Gastonia-Rock Hill, NC-SC nonattainment a rea.** 

**The USEPA’s modeling results predicts that the Met rolina nonattainment area should be below the**  **8-hour ozone standard by 2010. Although this is on e year later than the attainment year for the Metro**  **lina area, the USEPA’s 2010 DVFs are 2 to 4 ppb lower t**  **han the DVFs predicted in the attainment demonstration and support weight of evidence that t**  **he Metrolina area will attain the 8-hour ozone standard by its attainment year of 2009.** 

4. Positive Trends in Observed Air Quality and Ad ditional Emissions Reductions

**Since the 8-hour ozone designation for the Metroli na area, the 8-hour ozone design values have**  **improved significantly. The 2001-2003 design value period had values as high as 0.100 ppm, and six ou**  **t of the seven North Carolina monitors in the area we**  **re violating the NAAQS. Each year since, the desig n**  **values have decreased and/or the number of violatin g monitors in the region has decreased. For the la**  **test design value period, 2004-2006, the highest violati**  **ng monitor has a value of 88 ppb, with only three monitors exceeding the NAAQS (See Table V-5).** **61**

Table V-5: Design Values (ppm) for the North Carol ina Monitors in the Metrolina Area **Monitoring Site County 2001-2003 2002-2004 2003-200 5**  **2004-2006 Arrowood Mecklenburg 0.084 0.081 0.078**  **0.080 County Line Mecklenburg**  0.098 0.092 0.087 0.088 **Crouse Lincoln** 0.092 0.086 **0.081 0.079**  **Enochville Rowan** 0.099 0.091 0.085 0.085 **Garinger (Plaza) Mecklenburg** 0.096 0.091 0.086 0.088 **Monroe Union** 0.088 0.085 **0.079 0.078**  **Rockwell Rowan** 0.100 0.094 0.088 **0.083** **York York, SC* 0.084 0.081 0.075** **0.076** ***Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area.**

**The current ozone design values are very close to the predicted attainment year design values,**  **however, there are still significant nitrogen oxide s (NO** 
**x ) emission reductions that are expected between**  **now and the attainment year. Although most of thes e expected NO** 
**x emission reductions have been**  **included in the attainment demonstration modeling, it does not appear the model is responsive enough t**  **o expected emission reductions.** 

**As mentioned in earlier in the narrative, the Metr olina area is a NO** 
**x -limited area, and the major**  **sources of NO**
**x emissions in the region comes from mobile sources a**  **nd electric generating facilities. Reduction of emissions from these two source sector**  **s can significantly influence the ozone formation i n**  **this region. The NCDAQ and the SCDHEC have estimat ed that there will be approximately 7.6 tons per**  **day of NO**
**x**

**emissions reduced each year from the mobile sector . These reductions are the result of**  **Federal motor vehicle and equipment standards for b oth highway vehicles and off-road equipment.**  **Another source of NO**
**x emission reductions that are expected to occur bet**  **ween now and the attainment year are from the electric generating fa**  **cilities located in and near the Metrolina nonattai nment**  **area. Several of the Duke Energy units are still e xpected to have controls installed over the next tw**  **o years. Figure V-1 displays the location and size o**  **f the Duke Energy facilities located in the vicinit y of the**  **Metrolina nonattainment area. Table 5.3.4-2 lists the units that are in and around the Metrolina area**  **and shows the year the controls are expected to come on**  **line and the estimated amount of NO**
**x emissions** **62**

**reductions for the ozone season.**



### Figure V-1: Location and size of the Duke Energy f acilities located in the vicinity of the Metrolina nonattainment area

Table V-6: Utility NO x

Emission Reductions since 2006 Ozone Season

**Facility County Technology Operational Date Ozone Season Reductions**  **(tons/season) Allen Steam Station**  **Unit 2 Unit 3**  **Gaston SNCR**  **SNCR Spring 2007** 

**Fall 2007 ~300** 

**Buck Steam Station Units 3 & 4**  **Units 5 & 6 Rowan**  **Low NO x**  **Burners SNCR**  **Spring 2007**

**Fall 2006 ~350** 

**Riverbend Unit 4**  **Unit 5 Unit 6**  **Unit 7 Gaston**  **SNCR SNCR & Burners**  **SNCR & Burners SNCR**  **Spring 2007**

**Spring 2007 Fall 2006**  **Fall 2006 ~325** **63**

**Marshall Steam Station Unit 2**  **Unit 3 Unit 4**  **Catawba SNCR**  **SCR SNCR**  **Spring 2007**

**Fall 2008 Fall 2006**  **~2,300**

Total expected reduction = 3,275 tons/ozone season **SNCR = Selective Non-Catalytic Reduction SCR = Selective Catalytic Reduction** 

**The combination of the mobile source and utility N O**  **x emission reductions that are expected in the**  **Metrolina area after the end of the 2006 ozone seas on and before the beginning of the attainment year**  **2009 is significant. Since the 2004-2006 design va lues are just above the standard, the additional NO** 
**x emission reductions in the area should ensure that**  **the Metrolina area will attain the NAAQS by the prescribed attainment year.** 

5. Local Measures Not Modeled

**A significant source of NO**
**x emission reductions that has not been included in**  **the modeling is the addition of a SCR unit at Marshall Unit 3. This SC**  **R unit should be installed the fall of 2008 and wil l be**  **operational before the beginning of 2009.**

**In addition to the Marshall NO**
**x emission reductions, the Metrolina area has a numb**  **er of groups that are working towards decreasing emissions. These ar**  **e voluntary measures that, although not accounting for large emission reductions, are reductions nonet**  **heless. A few of the known measures that are under way in the Metrolina area include: I-77 High Occup**  **ancy Vehicle (HOV) lanes in Mecklenburg County, truckstop electrification in Rowan County, express**  **bus routes, pedestrian walkway and bikeway projects**

**, idle reduction policies, and biodiesel use and dies**  **el retrofit projects. Discussions of these measure s can**  **be found in Appendix L.**

D. Unmonitored Area Attainment Analysis

**The modeled attainment test does not address futur e air quality at locations where there is not an**  **ozone monitor nearby. To guard against the possibi lity that air quality levels could exceed the stand**  **ard in areas with limited monitoring, Section 3.4 of the**  Attainment Guidance **suggest that additional review is “necessary, particularly in nonattainment areas whe**  **re the ozone or PM 2.5**  **monitoring network just meets or minimally exceeds the size of the network requir**  **ed to report data to Air Quality System (AQS).” Th is**  **review is intended to ensure that a control strateg y leads to reductions in ozone at other locations t**  **hat could have baseline (and future) design values exce**  **eding the NAAQS were a monitor deployed there. The test is called an “unmonitored area analysis”.**  **The purpose of the analysis is to use a combinatio n of**  **model output and ambient data to identify areas tha t might exceed the NAAQS if monitors were located**  **there.**

**NCDAQ and SCDHEC believe that the density of their monitoring network relieves the necessity of**  **applying this additional analysis. With an average of one monitor per 3,077 km**  **2 , this is one of the**  **densest statewide ozone monitoring networks in the nation. Additionally, the monitor density across t**  **he Metrolina nonattainment area is more than twice tha**  **t of the statewide monitor density (on average a monitor every 1,278 km**  **2 ).** 

**The Modeled Attainment Test Software (MATS) tool h as been developed by the USEPA to spatially**  **interpolate data, adjust the spatial fields based o n model output gradients, and multiply the fields b**  **y model calculated RRFs for analysis of unmonitored a**  **reas. However, this tool has just recently been released with documentation (June 2007), and neithe**  **r the NCDAQ nor the SCDHEC has had sufficient 64** 

**time to review documentation and fully understand t he output from this tool, nor has the tool been pee**  **r reviewed. The NCDAQ and the SCDHEC ares committed**  **to evaluate the MATS tool output and any peer review comments that are submitted to determin**  **e if additional monitoring or further NO**
**x controls**  **may be needed to ensure attainment of the NAAQS thr oughout the Metrolina region.** 

**Refer to Appendix L for a complete discussion of th is topic.** 

E. Data Access

**The modeling input and output files are very large and it would not be reasonable to submit all of**  **these files with the SIP attainment demonstration. These include all files used to process the emissi**  **ons, meteorology, and air quality models and any other f**  **iles used to develop the modeling. To request acce ss**  **to these files, please contact the Bureau of Air Qu ality at 803-898-4123.** **65**

SECTION VI. MODERATE NONATTAINMENT AREA REQUIREMEN TS

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

**Sections 172(c), 182(a), and 182(b) of the CAA pre scribe the requirements for ozone nonattainment**  **areas. Any State with a designated nonattainment a rea must promulgate amendments to their SIP to**  **address the requirements mandated by Section 172(c) of the CAA. As a Subpart 2, moderate ozone**  **nonattainment area, the Metrolina area must meet th e additional requirements prescribed by Section 182**  **of the CAA. Each State in which all or part of a M oderate Nonattainment Area is located shall make th**  **e submissions prescribed under Section 182(a) relatin**  **g to Marginal Nonattainment Areas and shall also submit the revisions to the applicable implementati**  **on plan described under Section 182(b) with respect to**  **Moderate Nonattainment Areas. The requirements are listed below, and the SCDHEC's activities in**  **promulgating amendments to the** South Carolina Air Quality Implementation Plan **(SIP) to comply with these mandates are discussed in more detail in the**  **various parts of this section.**

1. CAA Section 172(c) - Nonattainment Plan Provis ions

**Any State with a designated nonattainment area mus t promulgate amendments to its SIP to address**  **the requirements mandated by Section 172(c) of the CAA. The SIP provisions (including plan items)**  **required to be submitted under this part shall comp ly with each of the following:** 

**(1) RACM - Implementation of all reasonably avai lable control measures (RACM) as**  **expeditiously as practicable [including such reduct ions in emissions from existing sources in the area**  **as may be obtained through the adoption, at a minimum,**  **of reasonably available control technology (RACT)] and provide for attainment of the national**  **primary ambient air quality standards.**

**(2) RFP - Require reasonable further progress (R FP).** 

**(3) Inventory - Include a comprehensive, accurat e, current inventory of actual emissions from**  **all sources of the relevant pollutant or pollutants in the nonattainment area, including such periodic**  **revisions as the USEPA may determine necessary to a ssure that the requirements are met.** 

**(4) New Source Review (NSR): Identification and quantification - Identify and quantify the**  **emissions, if any, of any such pollutant or polluta nts that will be allowed from the construction and**  **operation of major new or modified stationary sourc es in the nonattainment area. Demonstrate to the**  **satisfaction of the USEPA that the emissions quanti fied for this purpose will be consistent with the**  **achievement of reasonable further progress and will not interfere with attainment of the applicable**  **NAAQS by the applicable attainment date.**

**(5) Permits for new and modified major stationar y sources - Require permits for the**  **construction and operation of new or modified major stationary sources anywhere in the nonattainment** 

**area.**

**(6) Other measures - Include enforceable emissio n limitations, and other such control**  **measures, means, techniques (including economic inc entives such as fees, marketable permits, and**  **auctions of emission rights), and schedules and tim etables for compliance determined necessary or**  **appropriate to provide for attainment of such stand ard in the nonattainment area by the applicable**  **attainment date.**

**(7) Compliance with Section 110(a)(2) of the CAA**

**. 66** 

**(8) Equivalent techniques - Upon application by any State, the USEPA may allow the use of**  **equivalent modeling, emission inventory, and planni ng procedures unless the USEPA determines that the**  **proposed techniques are, in the aggregate, less eff ective than the methods specified by the USEPA.** 

**(9) Contingency measures - Provide for the imple mentation of specific measures to be**  **undertaken if the area fails to make reasonable fur ther progress or to attain the NAAQS by the applica**  **ble attainment date. Such measures shall be included in**  **the plan revision as contingency measures to take effect in any such case without further action by t**  **he State or the USEPA.**

2. CAA Section 182 - Plan Submissions and Require ments

**Each State in which all or part of a Moderate Nona ttainment Area is located shall make the**  **submissions prescribed under Section 182(a) relatin g to Marginal Nonattainment Areas and shall also**  **submit the revisions to the SIP described under Sec tion 182(b) with respect to Moderate Nonattainment**  **Areas.**

a. CAA Section 182(a) - Marginal Areas

**Each State in which a nonattainment area is located shall submit to the USEPA the SIP revisions**  **(including the plan items) described under Section 182(a) of the CAA.** 

**(1) Inventory - Submit a comprehensive, accurat e, current inventory of actual emissions**  **from all sources.**

**(2) Corrections to the SIP - Submit a revision to the SIP that meets the following**  **requirements:**

**(A) Reasonably available control technology (R ACT) corrections - Submit, within 6**  **months of the date of classification, a revision th at includes such provisions to correct requirements**  **in (or add requirements to) the SIP concerning RACT.** 

**(B) Motor vehicle inspection and maintenance ( I/M) program.** 

**(C) Permit programs - Provisions to require pe rmits for the construction and**  **operation of each new or modified major stationary source (with respect to ozone) to be located in the** 

**area.**

**(3) Periodic inventory**

**(A) General requirement - Submit a revised inv entory every three years until the area**  **is redesignated to attainment.**

**(B) Emissions statements - Require that the ow ner or operator of each stationary**  **source of oxides of nitrogen or volatile organic co mpounds provide the State with an annual statement**  **showing the actual emissions of oxides of nitrogen and volatile organic compounds from that source. T**  **he statement shall contain a certification that the in**  **formation contained in the statement is accurate to the**  **best knowledge of the individual certifying the sta tement. The State may waive the annual emissions**  **inventory submittal requirement for any class or ca tegory of stationary sources that emit less than 25**  **tons per year of VOCs or NO** 
**x .** 
b. CAA Section 182(b) - Moderate Areas**67**

**As a Subpart 2, moderate ozone nonattainment area, the Metrolina area must also meet the additional**  **requirements prescribed by Section 182(b) of the CA A.** 

**(1) RFP - Provide for volatile organic compound emission reductions, within 6 years, of at**  **least 15 percent from baseline emissions, accountin g for any growth in emissions. Provide for such**  **specific annual reductions in emissions of VOCs and NO**  **x as necessary to attain the NAAQS for ozone.** 

**(2) RACT - Require the implementation of reason ably available control technology with**  **respect to all VOC sources in the area covered by a ny CTG issued by the USEPA and all other major**  **stationary sources of VOCs that are located in the area. There are no VOC sources subject to CTGs**  **located in York County portion of the nonattainment area.** 

**(3) Gasoline vapor recovery - Section 182(b)(3 ) of the CAA requires moderate and above**  **ozone nonattainment areas to implement Stage II vap or recovery programs. However, Section 202(a)(6)**  **of the CAA states that the Section 182(b)(3) Stage II requirement shall not apply in moderate areas af**  **ter onboard refueling vapor recovery (ORVR) rules are p**  **romulgated. The USEPA promulgated the ORVR regulations on April 16, 1994. Because of the USEP**  **A’s promulgation of ORVR and York County not already having Stage II vapor recovery in place, th**  **at portion of York County that is located in the Charlotte-Gastonia-Rock Hill, NC-SC nonattainment a**  **rea is not required to implement Stage II vapor recovery requirements.** 

**(4) Motor vehicle inspection and maintenance - Provide for a vehicle inspection and**  **maintenance program.**

**(5) General offset requirement - The ratio of t otal emission reductions of VOCs to total**  **increased emissions of such air pollutant shall be at least 1.15 to 1.** 

c. CAA Section 182(f) - NO x Requirements

**(1) The plan provisions required under this Sub part for major stationary sources of volatile**  **organic compounds shall also apply to major station ary sources [as defined in Section 302 and**  **Subsections (c), (d), and (e) of this Section] of o xides of nitrogen.** 

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

1. RACM/RACT Requirements

**Section 172(c)(1) of the CAA requires an amendment to the SIP to provide for the implementation of**  **all reasonably available control measures (RACM) to demonstrate attainment as expeditiously as**  **practicable [including such reductions in emissions from existing sources in the area as may be obtain**  **ed through the adoption, at a minimum, of reasonably a**  **vailable control technology (RACT)] and provide for attainment of the national primary ambient air qual**  **ity standards. Sensitivity analysis has demonstrat ed**  **that VOC reductions have very little impact on ozon e in South Carolina. The SCDHEC has determined**  **that the entire state is NO**
**x -limited and that the control program for reducing**  **ozone should be focused on NO**  **x emission reductions. The overwhelming abundance o**  **f biogenic VOC emissions makes the majority of North and South Carolina, including the Metrolin**  **a area, a NO x**  **-limited environment for the formation of ozone.** 

a. RACM**68**

**In August of 2006, stakeholders involved in suppor ting South Carolina's "Cleaner Air Sooner" effort**  **convened in Columbia to share and exchange ideas an d information about their local strategies. It was**  **appropriate that this "first of its kind" meeting w as held in the state, since South Carolina, with fo**  **rty-five of its forty-six counties participating, leads the**  **nation in the number of local areas that are commit ted to**  **implementing emission reduction measures. The EAC Summit was coordinated by SCDHEC staff with**  **input from stakeholders for the purpose of offering the local leadership a stage to highlight their ac**  **tivities. This sharing of ideas and local strategies served a**  **s an opportunity to connect EAC contacts and develo p a**  **network of peers for sharing information on positiv e strategies. To re-emphasize the importance of th**  **is work in South Carolina, USEPA Assistant Administrat**  **or Bill Wehrum addressed the attendees as the keynote speaker. Items on the agenda for the EAC S**  **ummit included: Energy Conservation; Diesel Retrofits; Land Use Planning; Alternative Fuels; Co**  **mmuting Options; Innovative Education and Outreach; Health Impacts/Lifestyle; Finding the Fun**  **ding; and Commuting Options (to Multi-Modal Transportation).** 

**SEQL (Sustainable Environment for Quality of Life) is a special USEPA Region 4 bi-state project**  **involving the Charlotte-Mecklenburg area of North C arolina and the Catawba region of South Carolina,**  **which includes Chester, Union, Lancaster, and York counties. The Centralina and Catawba Regional**  **Councils of Government (COGs) have been instrumenta l in involving other local government**  **organizations, state agencies and the public in SEQ L. Due to these areas experiencing strong and**  **sustained population growth, they face many challen ges in maintaining good air quality and in contendi**  **ng with nonattainment for the eight-hour ozone NAAQS i**  **n some areas.**

**As part of the SCDHEC's involvement in SEQL, the B ureau of Air Quality partnered with the**  **Catawba Regional COG to develop model ordinances, e xamples of best management practices, and**  **program guidance documents to assist local governme nts in implementing programs such as tree planting,**  **bike trails, and parking with green spaces to addre ss environmental concerns. The Model Ordinances ar**  **e posted on the SCDHEC's Web site as well as a link t**  **o the SEQL Web site. The Centralina and Catawba Regional COGs continue to work together to address**  **air quality and other environmental concerns and ar e**  **now developing a regional vision that will represen t what residents, local jurisdictions, and private**  **sector leaders want the region to be.** 

**The following emission reduction measures impactin g mobile sources are planned or have been**  **implemented in York County:**

**• York County gas can exchange in 2004. Catawba Regional Council of Government**  **(COG), Rock Hill Clean and Green, York County Gover nment, City of Rock Hill, Palmetto State Clean**  **Fuels Coalition, and Sustainable Environment for Qu ality of Life (SEQL) collaborated with the SCDHEC**  **on the event. A total of 110 old cans were turned in.** 

**• South Carolina has two current school bus retro fit projects, a Santee Cooper Supplemental**  **Environmental Project (SEP) project that involves i nstallation of diesel particulate filters, and a Cl**  **ean School Bus USA grant involving installations of die**  **sel oxidation catalysts, crankcase ventilation syst ems,**  **and anti-idling hardware. The nonattainment portio n of York County is a priority area for both projec**  **ts.**

**• Breathe Better anti-idling program is being imp lemented at Rosewood Elementary School**  **in Rock Hill. Additionally, the Catawba Regional C ouncil of Governments, the South Carolina Energy**  **Office, and the Museum of York County have provided matching funds for a two-year implementation of**  **this Idle Reduction Program in York County Schools through Congestion Mitigation and Air Quality**  **(CMAQ) funding.**

**• Additional emission reducing projects to receiv e CMAQ funds include signal controller** **69**

**upgrades, intersection improvements, and bike/pedes trian projects.**  **• York Technical College has received a grant to retrofit nonroad equipment with diesel**  **oxidation catalysts. The catalysts will be install ed on 50 vehicles, including backhoes, bulldozers,**  **motor graders, and others from the fleets of the City of**  **Rock Hill, the South Carolina Department of Transportation, and Chester County.** 

**• Where no transit has been available, Dial-a-Rid e service will start in the City of Rock Hill**  **(expanded from York County.)**

**• RFATS is participating in the Charlotte Region HOV lane study for I-77.** 

**• A lawn mower exchange was held in York County i n April 2007.** 

**• RFATS is studying transit alternatives to conne ct downtown Rock Hill and Uptown**  **Charlotte (Rock Hill-York County-Charlotte Transit Study.)** 

**• Duke Energy launched a pilot program to subsidi ze public transportation costs for**  **Charlotte area employees as part of the company's c ommitment to the environment and its ongoing effort**  **s to help reduce ozone related emissions. Beginning**  **September 1 and running through December 31 of 2006, the pilot program provided subsidies and ince**  **ntives around bus transit, carpools and vanpools fo r**  **full time and part time employees who work at the f ollowing Duke Energy locations: Catawba Nuclear**  **Station (York, S.C.), Customer Contact Center (Univ ersity Research Park), McGuire Nuclear Station**  **(Huntersville, N.C.), and uptown Charlotte.**

**• EnviroFlash has been configured and activated f or South Carolina's Catawba region. The**  **Catawba region will include York, Chester, and Lanc aster counties. By including York County in the**  **Catawba region, the SCDHEC will take over duties fr om North Carolina with regard to ground-level**  **ozone forecasting for the county. The SCDHEC belie ves that the resources in South Carolina are**  **available to provide York County with an accurate a nd reliable forecast during the ground-level ozone** 

**season.**

**The SCDHEC has initiated a program to continue the statewide focus on air quality that began with**  **the Early Action Compact process. Staff are assign ed to all counties of the state to work with local**  **governments, businesses, and citizens to continue w orking to maintain and improve air quality. The**  **SCDHEC, with its York County partners, will continu e to seek opportunities that offer emission**  **reductions that may be needed to show maintenance o f the 8-hour ozone standard.** 

b. RACT

**In accordance with 40 CFR Part 51, Subpart X - §51 .912 pertaining to moderate nonattainment areas**  **under the 8-hour ozone NAAQS, the State is required to submit to the USEPA an amendment to the SIP**  **that includes the identification and implementation of reasonably available control technology (RACT).**  **The SIP amendment must meet the NO**
**x and VOC RACT requirements in Sections 172(c)(1), 1**  **82 (a)(2)(A), 182(b)(2), and 182(f) of the CAA. The S**  **tate must implement all reductions in emissions fro m**  **existing sources in the nonattainment area as may b e obtained through the adoption of RACT that will**  **provide for attainment of the NAAQS as expeditiousl y as practicable. The CAA requires that RACT be**  **applied to major stationary sources of NO**
**x and VOCs located in ozone nonattainment areas. A**  **major source is considered any source with the potential**  **to emit 100 tons per year or more of NO**
**x or VOCs.** 

**As defined by the USEPA in 40 CFR Section 51.100 - Definitions: Reasonably Available Control**  **Technology (RACT) means devices, systems, process m odifications, or other apparatus or techniques that** **70**

**are reasonably available taking into account (1) th e necessity of imposing such controls in order to a**  **ttain and maintain a national ambient air quality standar**  **d; (2) the social, environmental, and economic impa ct**  **of such controls; and (3) alternative means of prov iding for attainment and maintenance of such standa**  **rd.**

**RACT requirements are typically prescribed by Stat e and local rules and regulations but may also be**  **made on a case-by-case basis. In performing a RACT analysis, the State must look at available control**  **s to conclude whether they are reasonably available f**  **or a specific source or source category. RACT requires that sources adopt controls that are reaso**  **nably available, thus they may not be the most stri ngent**  **controls that have been adopted for other similar s ources. The fact that another similar source has s**  **uch controls in place does not mean that such a control**  **is reasonably available for all other similar sour ces.** 

**The SCDHEC has determined that there are no CTG (C ontrol Technology Guidance) sources located**  **within the nonattainment portion of York County. T he SCDHEC has identified three affected major non**  **CTG sources within the ozone nonattainment portion of York County subject to RACT requirements and**  **has approached these facilities to conduct a RACT a nalysis:** 

**(1) Bowater, Inc. (Title V permit # 2440-0005); (2) Cytec Carbon Fibers, LLC (Title V permit # 2**  **440-0097); and (3) Georgia Pacific Wood Products, LLC (Title V**  **permit # 2440-0026).**

**The above facilities determined their RACT applica bility based on "top down" procedures**  **established for prevention of significant deteriora tion (PSD) and nonattainment new source review**  **(NSR). A report of each facility's applicability d etermination that was prepared and submitted to the**  **SCDHEC for review is contained in Appendix Q. The SCDHEC concurred with the reports' conclusions**  **that installation of additional emission control de vices would not be economically feasible, thus only**  **work practice revisions will be utilized for RACT a t these facilities. Georgia Pacific Wood Products,**  **LLC, however, will comply with maximum achievable c ontrol technology (MACT) requirements in**  **accordance with 40 CFR 63, Subpart DDDD, whereby MA CT is at least as stringent as RACT.** 

**Any new sources with the potential to emit 100 ton s per year or more of NO** 
**x or VOCs will be**  **covered under the requirements of South Carolina Ai r Pollution Control Regulation R. 61-62.5, Standard**  **No. 7.1,** Nonattainment New Source Review **(NSR).**

**On June 8, 2007, the USEPA published a final notice of reconsideration (72 FR 31727),**  Phase 2 of the Final Rule To Implement the 8-Hour Ozone Nation al Ambient Air Quality Standard—Notice of Reconsideration **. In this notice, the USEPA states that it has det ermined that EGU sources complying**  **with rules implementing the Clean Air Interstate Ru le (CAIR) requirements meet ozone NO** 
**x RACT**  **requirements in states where all required emission s reductions are achieved from EGUs only. The**  **USEPA does not believe that requiring source-specif ic RACT controls on EGUs in nonattainment areas**  **will reduce total NO X**  **emissions from EGU sources covered by the below t he levels that would be**  **achieved under the alone.**

**The SCDHEC amended South Carolina Air Pollution Co ntrol Regulation 61-62.72,**  Acid Rain **; South Carolina Air Pollution Control Regulation 61-62.96,**  Nitrogen Oxides (NO
x ) Budget Trading Program General Provisions, **and the SIP to ensure compliance with the provisio ns of the , which was published in**  **the** Federal Register

**on May 12, 2005. On June 22, 2007, the** South Carolina State Register (State Register) **promulgated the full text of the noted revisions, which became effective upon the date of**  **publication. The South Carolina Legislature approv ed the amendments on May 27, 2007.** 

2. Reasonable Further Progress**71**

**Section 182(b)(1) of the CAA mandates a 15 percent VOC emission reduction, accounting for**  **growth, in the first 6 years after the baseline yea r (2002) for moderate and above ozone nonattainment**  **areas. Thus, for the York County nonattainment are a, a reasonable further progress (RFP) analysis**  **between 2002 and 2008 is required.**

**The methodology the SCDHEC used to calculate the R FP target levels of VOC emissions is based**  **on the method developed in the CAA while taking int o account the restrictions on creditable emissions**  **and the need to use the 2002 inventory as a baselin e. The CAA specifies four types of measures that a**  **re not creditable toward the 15 percent RFP requiremen**  **t:**

**1. Any measure relating to motor vehicle exhaust or evaporative emissions promulgated by the**  **USEPA by January 1, 1990.**

**2. Regulations concerning Reid Vapor Pressure (R VP) promulgated after 1990 or required**  **under Section 211(h) of the CAA.**

**3. Measures required under Section 182(a)(2)(A) of the CAA to correct deficiencies in the SIP**  **regarding VOC RACT regulations required prior to en actment of the CAA Amendments of 1990.** 

**4. State regulations submitted to correct defici encies in existing or required I/M programs.** 

**These four types of measures were all expected to result in a decrease in emissions between 1990**  **and 1996. Of these four types of measures, RACT an d I/M program corrections did not apply to South**  **Carolina because the State was in attainment for al l standards at that time, and the 1990 RVP**  **requirements were completely in place by 1996 and t herefore are already accounted for in the 2002**  **baseline. As a result, they would produce no addit ional reductions between 2002 and 2008 or later**  **milestone years.**

**However, the pre-1990 Federal Motor Vehicle Contro l Program (FMVCP) will continue to provide**  **additional benefits during the first two decades of the 21st century as remaining vehicles meeting pre** 

**** **1990 standards are removed from the vehicle fleet. Because these benefits are not creditable for RFP**  **purposes, in order to calculate the target level of emissions for future RFP milestone years, the SCDH**  **EC first calculated the reductions that would occur ov**  **er these future years as a result of the pre-1990 FMVCP. Consistent with the requirements of Section**  **s 182(b)(1)(C) and (D) and 182(c)(2)(B) of the CAA, the SCDHEC used the process described in Metho**  **d 1 below to account for non-creditable reductions in calculating RFP targets for the 2008**  **milestone year. The SCDHEC did not have VOC RACT regulations in the York County nonattainment a**  **rea prior to the enactment of the 1990 CAA, thus only the on-road mobile source sector required an e**  **stimation of non-creditable emissions.**

**Method 1: For areas that must meet a 15 percent VOC reduction requirement by 2008:** 

**(A) Estimate the actual anthropogenic base year VOC inventory in 2002 with all 2002**  **control programs in place for all sources.**

**(B) Using the same highway vehicle activity inp uts used to calculate the actual 2002**  **inventory, run the appropriate motor vehicle emissi ons model for 2002 and for 2008 with all post-1990**  **CAA measures turned off. Any other local inputs fo r vehicle I/M programs should be set according to t**  **he program that was required to be in place in 1990.**  **Fuel RVP should be set at 9.0 or 7.8 depending on t he**  **RVP required in the local area as a result of fuel RVP regulations promulgated in June, 1990.** 

**(C) Calculate the difference between the 2002 a nd 2008 VOC emission factors calculated** **72**

**in Step B and multiply by 2002 vehicle miles travel ed (VMT). The result is the VOC emissions**  **reductions that will occur between 2002 and 2008 wi thout the benefits of any post-1990 CAA measures.**  **These are the non-creditable reductions that occur over this period.** 

**(D) Subtract the non-creditable reductions calc ulated in Step C from the actual**  **anthropogenic 2002 inventory estimated in Step A. This adjusted VOC inventory is the basis for**  **calculating the target level of emissions in 2008.**

**(E) Reduce the adjusted VOC inventory calculate d in Step D by 15 percent. The result is**  **the target level of VOC emissions in 2008 in order to meet the 2008 RFP requirement. The actual**  **projected 2008 inventory for all sources with all c ontrol measures in place, including projected 2008**  **growth in activity, must be at or lower than this t arget level of emissions.** 

**The 2002 baseline VOC emissions for the York Count y nonattainment area are presented in Table**  **VI-1.**

Table VI-1: York County Nonattainment Area 2002 Ba seline VOC Emissions (tons/day)

Point Area Nonroad Highway Mobile Total

**York* 7.29 7.48 3.19 6.84 24.80** ***Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area.**

**The 2008 VOC emission estimates are included in Ta ble VI-2.** 

Table VI-2: York County Nonattainment Area 2008 Pr ojected VOC Emissions (tons/day)

Point Area Nonroad Highway Mobile Total

**York* 3.60 7.90 2.40 3.94 17.84** ***Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area.**

**Table VI-3 provides the summary 15% RFP analysis s howing the projected 2008 VOC emissions for**  **the area, 17.84 tons/day, are well below the target level of emissions, 20.23 tons/day, as calculated**  **using Method 1. See Appendix O for detailed modeling data** 

**.**

Table VI-3: York County* Nonattainment Area 15% RF P Analysis

**York County 15% RFP Analysis VOC**  **(tons/day) Step from Method 1** 
**Total 2002 Base year anthropogenic VOC emissions**  **24.80 Step A**
**Non-creditable VOC reductions 1.00 Step C 2002 base year minus the non-creditable emissions 2**  **3.80 Step D 73** 

**2008 target level of VOC emissions 20.23 Step E 2008 projected VOC emissions 17.84 Projection < Tar**  **get RFP goal met** ***Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area.**

**The SCDHEC must show continued progress from 2008 through the attainment date (June 15, 2010).**  **To do so, the SCDHEC calculated the expected benefi ts from the fleet turnover for the on-road and off**  **road mobile sectors. In 2009 and 2010, the SCDHEC expects approximately 0.73 tons per day of NO** 
**x emissions reductions from this fleet turnover. The**  **SCDHEC did not calculate future expected VOC emissions reductions in 2009 and 2010 since the are**  **a is NO**
**x -limited, but additional VOC emission**  **reductions are expected from the fleet turnover of the on-road mobile sector. The SCDHEC believes**  **these additional reductions demonstrate continued r easonable further progress toward attainment beyond**  **2008.**

3. Actual Emissions Inventory

**Section 182(a)(1) and Section 172(c)(3) of the CAA require the development of a comprehensive,**  **accurate current inventory of actual emissions from all sources of VOC and NO** 
**x in the nonattainment**  **area. Such inventory was due two years after desig nation of the 8-hour ozone nonattainment areas, or**  **by June 15, 2006. The SCDHEC met this requirement thr**  **ough the submission of the 2002 emission inventories under the Consolidated Emission Reporti**  **ng Rule (CERR) for that portion of York County within the nonattainment area. The SCDHEC submitte**  **d statewide emissions inventories for point, area, nonroad mobile, and highway mobile sources.** 

**The final 2002 emission inventories used in the at tainment demonstration (found in "Appendix E -**  **Emission Inventory Summary") will go through the pu blic hearing process as part of the full attainment**  **demonstration, which will include any updates or re visions that are necessary since the CERR submittal** 

**.**
4. Emissions Inventory Statement

**Section 182(a)(3)(B) requires the SIP to contain a requirement for all owners or operators of**  **stationary sources located in the nonattainment are a and emit either VOC or NO** 
**x to submit a statement of**  **actual emissions annually. The State may waive the requirement for sources that emit less than 25 ton**  **s per year of NO** 
**x**

**or VOC emissions.**

5. Periodic Emissions Inventory

**Section 172(c)(3) and 182(a)(3)(A) of the CAA requ ire periodic inventory submissions.**  **Specifically, Section 182(a)(3)(A) requires the inv entory be submitted every three years until the are**  **a is redesignated to attainment. The SCDHEC plans to me**  **et this requirement through the CERR submittal. As such, the SCDHEC will submit the 2005 emissions**  **inventory on or before June 1, 2007.**

6. Permit Program Requirements

**It is required per Sections 172(c)(5) and 182(a)(2 )(C) of the CAA that there be a permit program**  **consistent with the requirements of Section 173. I n addition, an offset requirement of 1.15 to 1 is**  **required per Section 182(b)(5). The SCDHEC submitt ed the regulations for the nonattainment new**  **source review (NSR) contained in Regulation R. 61-6 2.5, Standard No. 7.1,**  Nonattainment New Source Review **on July 1, 2005, to the USEPA for review and appro val. These regulations adopted the new offset** **74**

**requirement. Furthermore, the SCDHEC submitted ame ndments to Regulation R. 61-62.5, Standard No.**  **7,** Prevention of Significant Deterioration **(PSD) permitting regulations to the USEPA for appro val on**  **July 1, 2005. The SCDHEC believes that the "preven tion of significant deterioration" requirement of**  **Section 110(a)(2)(D)(i) is met by the adoption and submittal of the NSR and PSD regulations since PSD**  **and NSR are applicable to major sources in South Ca rolina. The SCDHEC believes it has satisfied the**  **permit program requirements for a moderate nonattai nment area.** 

7. Gasoline Vapor Recovery

**Section 182(b)(3) of the CAA requires moderate and above ozone nonattainment areas to implement**  **Stage II vapor recovery programs. However, Section 202(a)(6) of the CAA states that the Section**  **182(b)(3) Stage II requirement shall not apply in m oderate areas after onboard refueling vapor recover**  **y (ORVR) rules are promulgated. The USEPA promulgate**  **d the ORVR regulations on April 16, 1994. Therefore, 8-hour ozone moderate areas designated i**  **n 2004 are not subject to the Stage II vapor recove ry**  **program requirements. The attainment plan and cont ingency plan contained in this submittal addresses**  **the necessary controls to attain the 8-hour standar d in the Metrolina region.** 

8. Inspection and Maintenance (I/M) Program

**The USEPA initially recommended the development of an On-Board Diagnostics (OBD) program**  **for the Rock Hill-Fort Mill Area Transportation Stu dy (RFATS) Metropolitan Planning Organization**  **(MPO) portion of the Charlotte-Gastonia-Rock Hill, NC-SC moderate nonattainment area. The SCDHEC**  **examined the feasibility and impact of implementing an I/M program for the nonattainment portion of**  **York County that would have affected only 55,700 ve hicles. Emissions modeling indicated that an OBDII**  **program, if implemented in the nonattainment area, would only reduce NO** 
**x emissions by about 87 tons**  **annually and volatile organic compounds emissions b y about 63 tons annually, or approximately 49 tons**  **and 37 tons, respectively, during the ozone season. The SCDHEC approached several contractors to**  **develop and implement an OBDII I/M program in the a rea but was unable to find a contractor who would**  **undertake the expenses involved in running an I/M p rogram of this size. The SCDHEC found that it was**  **not economically feasible to proceed with implement ation of an I/M program in South Carolina, and**  **proceeded to petition the USEPA for a waiver of thi s moderate nonattainment area requirement.** 

**Based upon correspondence between the SCDHEC and t he USEPA Region 4 after their consultation**  **with the USEPA's Office of Transportation and Air Q uality and the Office of General Counsel, the**  **USEPA concurred that the I/M requirement for modera te areas is not applicable to York County, SC. On**  **November 23, 2005, the USEPA Region 4 notified the SCDHEC that the CAA requirement to implement**  **an Inspection and Maintenance (I/M) program was not applicable to the York County, South Carolina**  **RFATS MPO moderate nonattainment area. The corresp ondence from USEPA Region 4 stated:** 

"Even though a portion of York County was designat ed as part of the Charlotte moderate 8-hour ozone nonattainment area, applicability of the I/M regulations to areas outside the Ozone Transport Region is based on the population of the urbanized area as defined by the 1990 census. As defined by the 1990 census (see enclosed map), the Rock Hill and C harlotte urbanized areas are distinct and are not contiguous. Although the Charlotte urbanized porti on of the MSA is contiguous to the North Carolina/South Carolina border, it does not extend into South Carolina. The Rock Hill urbanized area is totally contained within South Carolina and does no t touch the State line. Therefore, the applicabili ty level of a 1990 census population of 200,000 or mor e in an urbanized area (40 CFR 51.350(a)(1)) applie s to each of the two urbanized areas separately. Sin ce the Rock Hill urbanized area has a population le ss than 200,000, the I/M requirement in Section 182(b) (4) of the CAA is not applicable to York County."

**See "Appendix R - I/M Supporting Documents" for co pies of the following correspondence between** **75**

**the SCDHEC and the USEPA Region 4 relating to the I /M requirement for the nonattainment portion of**  **York County.**

**October 26, 2004 (SCDHEC BAQ to USEPA Region 4)**

**December 27, 2004 (EPA Region 4 to SCDHEC BAQ)**

**August 26, 2005 (SCDHEC to USEPA Region 4)**

**October 3, 2005 (EPA Region 4 to SCDHEC)**

**November 23, 2005 (EPA Region 4 to SCDHEC)**

**"Appendix R - I/M Supporting Documents" also inclu des a copy of the SCDHEC comments on the**  **proposed rulemaking amendments to the vehicle I/M p rograms requirements to address the 8-hour**  **NAAQS for Ozone dated February 7, 2005.**

9. Other Measures

**The SCDHEC evaluated the expected emission reducti ons through the implementation of Federal**  **and State programs and regulations. Many of the NO**
**x stationary point sources have already been or will**  **be controlled upon implementation of the NO**
**x SIP call and SIP initiatives. In addition, the S**  **outh Carolina Air Pollution Control Regulations and Stan**  **dards has been amended with the addition of a new Regulation 61-62.5, Standard No. 5.2 - Control of O**  **xides of Nitrogen, and a revision of Regulation 61- 62.2 - Prohibition of Open Burning, for additional**  **control of NO**
**x emissions.** 

a. NO x

SIP Call

**On October 27, 1998, the USEPA finalized a Nitroge n Oxides (NO** 
**x ) State Implementation Plan**  **(SIP) Call Rule. The NO**
**x SIP Call was designed to reduce the regional trans**  **port of ground-level ozone through reductions in NO** 
**x from electric generating unit (EGU) sources and fr**  **om some non-EGU sources. The rule requires that, beginning in 2004, NO** 
**x reductions must occur during ground-level ozone se**  **ason in states whose NO** 
**x**

**emissions have been identified as contributing to 1-hour ozone standard nonattainment**  **in "downwind" states. The rule also requires state s to identify pollution-reduction measures and deve**  **lop a plan to achieve these reductions.** 

**A draft SIP revision was submitted to the USEPA on October 30, 2000. The SCDHEC Board**  **(Board) granted initial approval on December 14, 20 00. A public hearing was conducted before the**  **Board on April 12, 2001, at which time the Board in structed staff to provide an additional 30-day**  **comment period. A second notice of proposed regula tions was published in the**  State Register **on April 27, 2001. Final Board approval was granted on June**  **14, 2001. Legislative review was required and the final regulation was published in the**  State Register **on May 24, 2002, as document number 2593. The draft SIP revision was submitted to the USEPA on Ju**  **ly 30, 2001 for parallel processing. On April 10, 2002, the USEPA published the proposed approval of**  **the plan in the** Federal Register **(67 FR 17317). Final USEPA approval was published in the**  Federal Register **on June 28, 2002.**

**Each state subject to the NO**
**x SIP Call regulation has a NO** 
**x budget that the state allocates to**  **applicable sources. The budget is NO**
**x -based on cost-effective reductions in emissions th**  **at can be achieved by the affected sources. South Carolina's**  **state trading program budget, as specified in Regulation 61-62.92, Nitrogen Oxides (NO** 
**x ) Budget Trading Program, is 19,678 tons. The NO** 
**x SIP Call**  **regulation will be repealed after 2009 upon impleme ntation of the Clean Air Interstate Rule.** **76**

b. 8-hour Ozone Early Action Compact Regulations

**On August 22, 2002, the SCDHEC published a Notice of Drafting in the**  State Register **announcing its intent to pursue Early Action Compacts (EAC) fo**  **r the 8-hour ozone standard. Through the EAC process, local, state, and USEPA officials committe**  **d to work together to develop and implement plans that will reduce ozone pollution so that areas are**  **attaining the 8-hour ozone standard earlier than wo uld be**  **required by the Clean Air Act. Only areas that are attaining the 1-hour ozone standard are eligible t**  **o participate in the EAC process. The compact requir**  **es these areas to attain the 8-hour ozone standard by**  **December 31, 2007, a date that is sooner than would otherwise be required through the traditional**  **nonattainment designation process.**

**At the end of 2002, 45 of South Carolina's 46 coun ties, the SCDHEC, and the USEPA Region 4 had**  **signed compacts to implement ozone reduction strate gies earlier than federally required. Statewide**  **stakeholder groups involving local and federal gove rnments, industry, environmental groups, and other**  **interested parties have worked together to plan and implement strategies for ozone pollution preventio**  **n throughout the state. Plans involve mobile source**  **pollution reduction, outreach actions, and point so urce**  **prevention, which provide flexibility and foster lo cal solutions to local problems. In 2002, York Cou**  **nty elected to participate in the 8-hour Ozone EAC proc**  **ess. However, due to an area of York County (Rock Hill-Fort Mill Area Transportation Study Metropolit**  **an Planning Organization, also known as RFATS MPO) being included in the Charlotte-Gastonia-Rock**  **Hill, NC-SC nonattainment area, that portion of the county designated as nonattainment was no longer el**  **igible to participate even though York County was designated attainment for the 1-hour ozone standard**  **. York County officials have continued working wit h**  **stakeholders to implement emission reduction measur es and submit EAC progress reports every 6**  **months.**

**As part of this process, the EAC stakeholders deve loped statewide regulations aimed at achieving**  **additional reductions in ozone precursors. One new regulation that was developed as part of this proc**  **ess was Regulation 61-62.5, Standard 5.2, Control of Ox**  **ides of Nitrogen (NO**
**x ). This is a broad-based**  **regulation that applies statewide to new and existi ng stationary sources that emit NO** 
**x from fuel**  **combustion and have not undergone a best available control technology (BACT) analysis for NO** 
**x . For**  **new sources, the regulation requires the installati on of control technology that is based on BACT**  **standards found in the RACT/BACT/LAER clearinghouse . For existing sources, the regulation only**  **applies when an applicable unit replaces its burner . At this point, they will be required to replace**  **their burner with a low NO** 
**x**

**burner or equivalent technology capable of achievi ng a 30 percent reduction from**  **uncontrolled levels.**

**Also, as part of the EAC process, Regulation 61-62 .2, Prohibition of Open Burning, was revised by**  **deleting the exception for the burning of household trash, revising the exception for the burning of**  **construction waste, and revising the exception for fires set for the purpose of firefighter training.**  **The burning of household trash presents health and envi**  **ronmental concerns for many communities. The smoke generated from these activities is a nuisance**  **to some and a health threat to others with asthma or**  **other respiratory problems. With respect to the ex ception for the burning of construction waste, the**  **regulation was revised to allow only residential co nstruction waste to be burned outside the ozone sea**  **son, and this will only be allowed if it meets the provi**  **sions of the regulation. Finally, the exception fo r the**  **purpose of firefighter training was revised to ensu re that minimum health, environmental, and safety**  **concerns are addressed.**

**These regulations were approved by the Board in Ja nuary 2004, and, in accordance with South**  **Carolina law, they were subsequently submitted to t he Legislature for approval. The South Carolina**  **General Assembly approved the regulations, and the rules were published and became effective upon** **77**

**publication in the** State Register **on June 25, 2004. Statewide NO**
**x reductions from the Control of NO** 
**x regulation are estimated at 3,357 tons a year. Stat**  **ewide reductions resulting from the revisions to th e**  **Prohibition of Open Burning regulation are estimate d at 147 tons of NO** 
**x and 698 tons of VOC per ozone** 

**season.**

c. Clean Air Interstate Rule

**On March 10, 2005 the USEPA finalized the Clean Ai r Interstate Rule, also referred to as CAIR. On**  **May 12, 2005, CAIR was published in the** Federal Register

**.**

**CAIR affects 28 states and the District of Columbi a, whose emissions of sulfur dioxide (SO**  **2 ) and/or**  **NO x**  **produced by EGU sources and some non-EGU sources c ontribute significantly to the nonattainment**  **of the National Ambient Air Quality Standards (NAAQ S) for fine particles (PM**  **2.5 ) and/or 8-hour ozone in**  **downwind states. (SO 2**  **and NO**
**x are both precursors to ground-level ozone formatio**  **n, and NO**
**x is also a**  **precursor to PM 2.5**  **formation.) The USEPA has determined that EGU sour ces in South Carolina are**  **affecting the nonattainment of ozone and PM 2.5**  **standards in downwind states. CAIR is a cap-and-tr ade**  **program for NO**
**x**

**and SO 2**  **emissions from affected facilities and has two pha ses of implementation. The**  **caps for the phases are as follows:**

**Phase I, which begins in 2009 for NO**
**x (annual and ozone season) and 2010 for SO**  **2 CAIR NO**  **x annual cap = 32,662 tons (T)**  **CAIR EGU SO 2**  **annual cap = 57,271 T CAIR NO**  **x ozone season cap = 15,249 T** 

**Phase II, which begins in 2015 for both pollutant s**  **CAIR NO x**  **annual cap = 27,219 T CAIR EGU SO**  **2 annual cap = 40,089 T**  **CAIR NO x**  **ozone season cap = 12,707 T**

**was due for submission to the USEPA for approval on September 11, 2006. South Carolina is one**  **of many states that did not meet this deadline beca use of a lengthy regulatory process. The SCDHEC is**  **working closely with USEPA Region 4 toward implemen tation of the State's rule. The SCDHEC has**  **adopted the federal with modifications in areas wh ere the state has flexibility. A Notice of Draftin**  **g was published in the**  State Register **on July 22, 2005; a second Notice of Drafting was published in the**  State Register **on February 24, 2006. The initial approval to proc eed with the proposed regulation was given by**  **the SCDHEC Board on September 14, 2006. The Notice of Proposed Rule was first published in the**  State Register

**on October 27, 2006. A public hearing before the SCDHEC Board was held on January**  **11, 2007. On January 22, 2007, the proposed regula tion was submitted to the South Carolina Legislatur**  **e for approval. In March of 2007, the SCDHEC submitt**  **ed a request to the USEPA Region 4 for parallel processing. The SCDHEC anticipates the proposed re**  **gulation to become state-efffective upon publication in the**  State Register **in mid-Summer 2007. South Carolina is working wit h the USEPA to**  **complete the parallel processing at this time.**

d. Regulation R. 61.62.2, Prohibition of Open Burning

**On June 24, 2004, the Department revised its exist ing regulation regarding open burning activities to**  **reduce emissions of ozone precursor pollutants. Am ong the revisions were elimination of the exception**  **for burning household trash, modification of the ex ception of burning of construction waste, and**  **modification to the exception for fires set for fir efighter training. Based on the Department’s 1999**  **emissions inventory, residential burning of househo ld waste generates 2,379 tons of NO** 
**x and 11,896 tons**  **of VOCs in the state annually. As for the ban on t he burning of construction waste, the data indicate**  **s that 78** 

**the ban on residential construction waste alone wil l result in annual reductions of 147 tons of NO** 
**x and**  **625 tons of PM. Information on the amount of reduc tions to be expected from the ban on the burning of**  **commercial construction waste is not available, but it is clear that substantial reductions in NO** 
**x and**  **VOCs will occur statewide starting in 2004 as a dir ect result of the elimination of this activity as w**  **ell.**

**Regarding the burning of construction waste, the De partment revised this provision to allow only**  residential

**construction waste to be burned and only under the following conditions: the burning must**  **take place outside of ozone season (not during Apri l 1 through October 30 in South Carolina), the burn**  **ing must be conducted at least 500 feet from any occupi**  **ed structure, and the burning must be only of “clea n”**  **waste. Further, the exception for the purpose of f irefighter training has been revised to ensure that**  **minimum health, environmental and safety concerns a re addressed. The Department intends to do a**  **review of permanent firefighter training facilities and will evaluate nonpermanent sites and require**  **Department approval prior to a burn. Finally, in a ccordance with South Carolina Air Pollution Control**  **Regulation 61-62.2, Section II.C., the Department r eserves the right to restrict open burning on forec**  **asted code orange and higher air quality ozone action day**  **s for York County.**



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

**On June 24, 2004, South Carolina adopted Air Pollu tion Control Regulation R.61-62.5, Standard No.**  **5.2,** Control of Oxides of Nitrogen **to ensure areas attain and maintain the 8-hour ozo ne standard. This**  **regulation requires Best Available Control Technolo gy (BACT)-level controls on all stationary sources**  **that emits or have the potential to emit NO**
**x . Many of these sources would not otherwise be req**  **uired to control their NO** 
**x**

**emissions. For example, under the Clean Air Act r equirements, the preconstruction**  **review program referred to as New Source Review (NS R) only applies to larger sources (generally those**  **with potential emissions greater than 100 tons per year or more). For sources with emissions below th**  **ese levels, there are generally no controls for NO** 
**x required.** 

**This newly-developed regulation applies state-wide to new and existing stationary sources of NO** 
**x emissions. Larger sources that have undergone a BA**  **CT review for NO**
**x are exempt from the regulation;**  **however, larger sources that have taken limits to o pt out of a Prevention for Significant Deterioratio**  **n (PSD) review will still be required to comply with**  **this regulation which covers sources ranging from boilers and turbines to fluidized bed combustors an**  **d lime kilns. For existing sources, the regulation only**  **applies when an applicable unit replaces their burn er. At this point, they will be required to replac**  **e their burner with a low burner or equivalent technology c**  **apable of achieving a 30% reduction from uncontrolled levels.** 

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

**Section 172(c)(7) requires nonattainment SIPs to m eet the applicable provisions of Section**  **110(a)(2). The NCDAQ and the SCDHEC - BAQ have rev iewed the requirements of Section 110(a)(2)**  **and have concluded that the prior rule submittals, along with this attainment demonstration plan, addr**  **ess the relevant requirements.** 

11. Equivalent Techniques

**The SCDHEC believes that the procedures for modeli ng, emissions inventory and planning follow**  **USEPA guidance and is not requesting approval for e quivalent techniques, as allowed under Section**  **172(c)(8) of the CAA.**

12. Contingency Measures**79**

**Section 172(c)(9) requires that the nonattainment SIPs contain specific measures that would take**  **effect upon a State's failure to attain the ozone s tandard in a given area, without further action by**  **the State or the USEPA. Guidance from the USEPA indicates th**  **at the measures should be approximately three percent of the baseline emissions, so that reasonab**  **le progress level of reduction could be expected to occur in the year following the failure to attain.**  **The SCDHEC elected to adopt NO**
**x -only contingency**  **measures since the area is NO**
**x -limited. The contingency plan consists of Federal**  **and State measures. The Federal measures result from the fleet turnover**  **of the light and heavy-duty engine standards from the**  **on-road mobile sector and the nonroad engine standa rds. These measures are already adopted and the**  **fleet turnover will occur without further action by either the State or the USEPA. The fleet turnover**  **will result in approximately 0.11 tons/day NO** 
**x emission reductions, or about 2.2% of the base emi**  **ssions. The analysis of these emission reductions is included i**  **n Appendix P.**

**The State anticipates additional reductions from l ocal measures implemented by the Rock Hill-Fort**  **Mill Area Transportation Study (RFATS) Metropolitan Planning Organization (MPO). SC has been**  **determined to be NO**
**x**

**limited, the SCDHEC will encourage the RFATS Inter agency Partners to fund**  **future CMAQ projects that will result in the most r educed NO** 
**x emissions. There is no easy way to**  **estimate the amount of reductions that would be ach ieved through Congestion Mitigation and Air Quality**  **(CMAQ) projects. 80** 

SECTION VII. MOTOR VEHICLE EMISSION BUDGET

A. Transportation Conformity

**The purpose of transportation conformity is to ens ure that Federal transportation actions occurring i**  **n nonattainment and maintenance areas do not hinder t**  **he area from attaining and maintaining the 8-hour ozone standard. The level of emissions estimated b**  **y the Rock Hill-Fort Mill Area Transportation Study Metropolitan Planning Organization (also known as R**  **FATS) for the Transportation Implementation Plan (TIP) and Long Range Transportation Plan (LRTP) mus**  **t not exceed the motor vehicle emission budget (MVEB) as defined in this attainment demonstration.** 

1. Memorandum of Agreement

**On September 27, 1996, a Memorandum of Agreement ( MOA), negotiated between the South**  **Carolina Department of Health and Environmental Con trol (SCDHEC) and the South Carolina**  **Department of Transportation (SCDOT), was published in the**  South Carolina State Register **. The purpose of the MOA was to formally incorporate the**  **applicable provisions of the transportation conformity review process in accordance with the re**  **quirements of the CAA as promulgated by the USEPA on November 24, 1993 (58 FR 62188) in 40 CFR**  **Part 51 Subpart T, as amended August 7, 1995 (60 FR 40098), and November 14, 1995 (60 FR 57179).**  **Under those authorities, no department, agency, or instrumentality of the Federal government shall**  **engage in, support in any way or provide financial assistance for, license or permit, or approve any a**  **ctivity that does not conform to the** South Carolina Air Quality Implementation Plan **(SIP). The transportation conformity rule require s Federal agencies to**  **determine, prior to taking any action on transporta tion plans, programs, and projects, that such actio**  **n will conform to the SIP to maintain the National Ambient**  **Air Quality Standards (NAAQS). The transportation conformity regulation applies only t**  **o areas that are designated nonattainment or maintenance for any of the criteria pollutants (ozo**  **ne, carbon monoxide, fine particulate matter, sulfu r**  **dioxide, nitrogen dioxide, or lead).**

**On August 15, 1997 (62 FR 43780), April 10, 2000 ( 65 FR 18911), and August 6, 2002 (67 FR**  **50808), the USEPA promulgated amendments to the tra nsportation conformity rule to streamline and**  **clarify the criteria and procedures for determining the conformity of transportation plans, programs,**  **and projects. The State was required by 40 CFR Part 51**  **Subpart T Section 51.390 to amend the SIP by specifically removing any previously applicable imp**  **lementation plan transportation conformity requirements and submitting a revision to the SIP t**  **hat addresses all requirements of 40 CFR Part 93 Subpart A. A Notice of General Public Interest was**  **published on August 25, 2000. This SIP revision was delayed by the time-consuming task of gathering**  **the necessary signatures for a MOA. A staff conducted public hearing was held on the proposed r**  **evision on September 22, 2003. The SIP amendment was published as final in the**  State Register **on October 24, 2003, and subsequently submitted to the**  **USEPA for final approval on November 14, 2003. The USEPA published approval of the SIP revision in**  **the** Federal Register

**(69 FR 4245) on January 29, 2004.**

**In accordance with these requirements, the SCDHEC incorporated into the SIP a new MOA to**  **implement Section 176 of the Clean Air Act (CAA), a s amended (42 U.S.C. 7401,**  et seq **.), the related requirements of 23 U.S.C. 109(j), and regulations u**  **nder 40 Code of Federal Regulations (CFR) Part 93, Subpart A. The parties to this MOA are as follows:**  **each of the South Carolina Metropolitan Planning Organizations (MPOs), the SCDHEC, the SCDOT, the Fe**  **deral Highway Administration South Carolina Division Office (FHWA), the Federal Transit Adminis**  **tration (FTA), the USEPA Region 4 (USEPA), and local publicly-owned transit agencies not represent**  **ed by aforementioned MPOs in nonattainment and maintenance areas. The “South Carolina Criteria an**  **d Interagency Consultation Procedures for the Determination of the Conformity of Transportation P**  **lans, Programs, and Projects” provides for 81** 

**interagency consultation, resolution of conflicts, and public consultation procedures. The parties to**  **this MOA agreed to conduct transportation conformity det**  **erminations in accordance with the provisions of 40 CFR Part 93 Subpart A.** 

**The SIP amendment consisted of the following docum ents:** 

**1: South Carolina Transportation Conformity Memo randum of Agreement as endorsed by all**  **parties.**

**2: South Carolina** State Register **“Notice of Amendment to the South Carolina Air Qua lity**  **Implementation Plan” - Published on October 24, 2003.** 

**3: Notice of Public Hearing published in the** State Register **on August 22, 2003.**

**4: Copy of the verbatim transcript of the Septem ber 22, 2003, Public Hearing.** 

**5: South Carolina’s Legal Authority (Excerpt fro m the USEPA-approved SIP).** 

2. Conformity Interagency Consultation - York County/RFATS MPO

**On April 15, 2004, the USEPA issued designations a nd classifications based on the severity of the 8-**  **hour ozone NAAQS in each state with an effective da te of June 15, 2004. This included the RFATS**  **MPO boundary for the York County area along with co ntiguous portions of North Carolina. In making**  **the boundary and classification determinations, the USEPA utilized 8-hour ozone monitoring data from**  **the 2001-2003 calendar years. Although the monitor in York County during that time was below the 8-**  **hour ozone standard of 0.085 parts per million (ppm ), the USEPA determined that a portion of York**  **County contributed to violating monitors in nearby North Carolina. The nonattainment area was**  **classified under Subpart 2 of the Clean Air Act as being a “moderate” nonattainment area for ozone. T**  **his was decided based upon a monitored ozone value of 0**  **.100 ppm in Rowan County, North Carolina.**

**As a minimum requirement, no later than June 15, 2 005, the RFATS area was required to**  **demonstrate transportation conformity to ensure tha t all projects utilizing federal funds do not have**  **an adverse impact on the area’s air quality. Transpor**  **tation Conformity consultation procedures as outlin ed**  **in the South Carolina Transportation Conformity Mem orandum of Agreement and endorsed by all parties**  **enabled the nonattainment area to immediately begin the process. The York County Interagency**  **Consultation process, which included representative s from the RFATS, the SCDHEC, the SC Department**  **of Transportation, the USEPA Region 4, the SC Divis ion Office of Federal Highways, the Federal Transit**  **Authority, the City of Rock Hill, and York County, was initiated on May 14, 2004, and is ongoing.**  **Specific information regarding this process is incl uded in Appendix F3 Section 4.1.** 

3. RFATS - CMAQ Projects

**The Congestion Mitigation and Air Quality Improvem ent Program (CMAQ) was created by the**  **Intermodal Surface Transportation Equity Act (ISTEA ) in 1991, was reauthorized by the Transportation**  **Equity Act for the Twenty-First Century (TEA-21), a nd was subsequently reauthorized by the Safe**  **Accountable, Flexible Efficient Transportation Equi ty Act - a Legacy for Users (SAFETEA-LU). The**  **CMAQ program provides funding for projects designed to help achieve and maintain the NAAQS. South**  **Carolina receives an annual minimum apportionment, which in 2006 was a little over $10 million. A**  **mandatory portion of that, nearly $2 million, was r equired to be used in the Rock Hill nonattainment a**  **rea. To be eligible for the mandatory funding, projects**  **must advance air quality goals. New roads or lanes that would potentially increase traffic are not eli**  **gible for CMAQ funding. A variety of eligible proj ect** **82**

**types include traffic control signalization, traffi c flow improvements, alternative fuel programs, tra**  **nsit projects, carpooling programs, and bicycle and pede**  **strian projects.**

**The RFATS MPO announced its approved list of CMAQ projects for the funding years 2004 through**  **2006 at a press conference on January 26, 2007. Th e York County interagency consultation group, which**  **includes the RFATS MPO, the SCDHEC, the SCDOT, USEP A Region 4, the FHWA, and the FTA, has**  **been meeting for several years to address transport ation conformity and the attainment SIP. This grou**  **p approved the methodology used in determining air qu**  **ality benefits for the selected projects. All RFAT S**  **sponsored CMAQ projects are included in the RFATS 2 030 Long Range Transportation Plan. The**  **project list includes signalization improvements, t urn lanes, bicycle paths, a hybrid trolley, alterna**  **tive fuel vehicles, and an idle reduction and awareness progr**  **am for schools. Of the ten projects on the list, s even**  **are fully-funded. Project sponsors include the Cit y of Rock Hill, RFATS, RFATS Congestion**  **Management System, SCDOT District 4, York County, a nd the Catawba Regional Council of**  **Governments (COG). Local matches were provided by the City of York, the City of Rock Hill, York**  **County, the Catawba COG, the SC Energy Office, the Rock Hill School District, and the Museum of**  **York County. Emissions reductions over the lifetim es of the currently-funded projects are estimated a**  **t 1,999 tons of VOCs, 8,659 tons of CO, and 1,678 ton**  **s of NO**
**x . Matching funding for the three additional**  **projects will need to be identified before they can proceed. These projects, when funded, will produc**  **e additional reductions of 61 tons of VOCs, 266 tons**  **of CO, and 52 tons of NO**
**x .** 
B. Highway Mobile Source VOC Insignificance

**Section 93.109(k), in the Transportation Conformit y Rule Amendments for the new 8-hour ozone**  **and fine particulate matter NAAQS, addresses areas with insignificant motor vehicle emissions. The ru**  **le suggests that such a finding would be based on a nu**  **mber of factors, including the percentage of motor vehicle emissions in the context of the total SIP i**  **nventory, the current state of air quality as deter mined by**  **monitoring data for that NAAQS, the absence of SIP motor vehicle control measures, and historical**  **trends and future projections of the growth of moto r vehicle emissions. Although there is a vehicle**  **control measure (inspection and maintenance) progra m in place in the North Carolina counties of the**  **Metrolina area, it was established for additional r eductions in NO** 
**x emissions. There are incidental VOC**  **emissions reductions as a result of this program; h owever, it is not believed the reduction of VOC**  **emissions has resulted in decreased ozone levels.**

**The SCDHEC has examined the NCDAQ’s study to deter mine sources of VOC emissions and their**  **contribution to ozone formation in the Metrolina ar ea. Due to the generally warm and moist climate of**  **the Carolinas, vegetation abounds in many forms, an d forested lands naturally cover much of each state** 

**. The NCDAQ has found that, as a result, the biogenic**  **sector is the most abundant source of VOC emissions in the Carolinas, accounting for approxim**  **ately 90% of the total VOC emissions. The overwhelming abundance of biogenic VOC emissions ma**  **kes the majority of North and South Carolina, including the Metrolina area, a NO** 
**x -limited environment for the formation of ozone.** 

**Additionally, the SCDHEC has reviewed a number of modeling sensitivity runs performed by the**  **NCDAQ that were designed to determine the impact of highway mobile source VOCs on ozone formation**  **in the Metrolina area. The results of these sensit ivities indicate no change in future ozone concentr**  **ations in the Metrolina area when highway mobile VOC emiss**  **ions are significantly changed (e.g., 50% decrease). These sensitivities are discussed in mo**  **re detail in Appendix F.3.**

**The SCDHEC agrees with the NCDAQ findings that hig hway mobile VOCs are insignificant**  **contributors to ozone formation in the Metrolina no nattainment area. Emission estimates indicate**  **highway mobile VOC is a small percentage of the tot al VOC emissions inventory. Highway mobile VOC**  **emissions are projected to decrease in the future, notwithstanding VMT increases. Emission sensitivit**  **y 83** 

**modeling indicates no change in future ozone concen trations when VOC emissions are significantly**  **changed. For these reasons, neither the NCDAQ nor the SCDHEC will be setting MVEB for VOC for**  **the Metrolina nonattainment area. The SCDHEC consu lted with its interagency transportation partners**  **prior to reaching this conclusion. Both agencies w ill revisit the setting of MVEB for VOC if there is**  **any future indication that the Metrolina area has becom**  **e VOC-sensitive for ozone formation.**

**As a result of the finding of VOC insignificance, t he SCDHEC will not be establishing a VOC budget for**  **the 2008 Reasonable Further Progress determination nor the 2009 attainment demonstration.** 

C. Motor Vehicle Emission Budgets

**The MVEB will be set for the attainment year 2009. By the time the MVEB is found adequate or**  **approved by the USEPA, the next transportation conf ormity regional emissions analysis should be for**  **years 2009 and beyond. Therefore, an MVEB will not be set for the baseline year 2002.** 

**Although emissions are usually expressed in terms of tons per day, the MVEBs will be set in terms**  **of kilograms (kg) per day. The reason for the chan ge is because the MOBILE model generates emission**  **factors in grams per mile. In past conformity exer cises, there have been some issues with conversion**  **to tons per day, as well as concerns with how MVEBs we**  **re rounded to the hundredth place. Setting the MVEB in kilograms per day will avoid these issues i**  **n future conformity determinations. During the development of the MVEB, the interagency partners f**  **or the York County nonattainment area were consulted.** 

**Table VII-1 shows the York County on-road mobile NO**
**x emissions expressed in tons per day and the**  **corresponding kilograms per day values for 2009.**

Table VII-1: 2009 Highway Mobile Source NO x Emissions York County Nonattainment Area

**County 2009**  **Tons/day Kg/day** **York* 8.01 7,266** ***Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area.**

**Upon the USEPA’s affirmative adequacy finding for the partial county MVEB, as shown in Table**  **VII-2, it will become the applicable MVEB for the n onattainment portion of York County.** 

Table VII-2: York County South Carolina NO x MVEB for 2009

**County MVEB (Kilograms/day) York** * **7,266** ***Represents only that portion of the county that is located in the Charlotte-Gastonia-Rock Hill, NC-SC**  **nonattainment area.**