Attainment Demonstration for the San Antonio Early Action Compact Region Proposed Local Revision to the State Implementation Plan SIP Revision Attainment Demonstration for the San Antonio EAC Region 2 List of Appendices Appendix A Conceptual Model and Episode Selection for the San Antonio EAC Region Appendix B Development of the Meteorological Model Appendix C On Road Mobile Emissions Inventory Development ( TTI Report)

Appendix D 1999 Base Case Modeling Emissions Inventory Development Appendix E 1999 Base Case Development and Performance Analyses Appendix F 2007 Future Base Modeling Emissions Inventory Development Appendix G 2007 Base Case and Sensitivity Analyses Appendix H Modeled Attainment Test Appendix I Clean Air Strategy Development Appendix J Modeling Protocol Appendix K Additional Evidence Appendix L Maintenance for Growth Appendix M Impact of Transport Appendix N Resolutions from Early Action Compact Signatory Local Governments in Support of the Proposed Local Revisions to the State Implementation Plan and the Local Clean Air Strategies SIP Revision Attainment Demonstration for the San Antonio EAC Region 3 LIST OF ACRONYMS AACOG Alamo Area Council of Governments AFV Alternative Fuel Vehicle AIR Air Improvement Resources Committee AQTF Air Quality Task Force ARPDB Acid Rain Program Data Base CAPCO Capital Area Planning Council CAMS Continuous Air Monitoring Stations CAMx Comprehensive Air Quality Model with Extensions CO Carbon Monoxide COSA City of San Antonio CPS City Public Service DFW Dallas/ Fort Worth EAC Early Action Compact EGU Electric Generating Unit EI Emissions Inventory EPA U. S. Environmental Protection Agency FAR Flexible Attainment Region FCAA Federal Clean Air Act HC Hydrocarbon HDDV Heavy Duty Diesel Vehicles HGA Houston/ Galveston Area HPMS Highway Performance Monitoring System ITS Intelligent Transportation System LED Low Emission Diesel NAAQS National Ambient Air Quality Standards NEGU Non electric Generating Unit NOx Nitrogen Oxides NNA Near Non attainment Areas PPB Parts per Billion PPM Parts per Million RRF Relative Reduction Factor RVP Reid Vapor Pressure SA BC MPO San Antonio Bexar County Metropolitan Planning Organization SAER San Antonio Early Action Compact Region SB Senate Bill SIP State Implementation Plan SOS Southern Oxidants Study TCEQ Texas Commission on Environmental Quality TDM Travel Demand Management TERM Transportation Emission Reduction Measures TIP Transportation Improvement Plan TPY Tons per Year TTI Texas Transportation Institute VMT Vehicle Miles Traveled VOC Volatile Organic Compounds SIP Revision Attainment Demonstration for the San Antonio EAC Region 4 Table of Contents Page List of Tables                             6 List of Figures                             8 Chapter 1: General                          . 10 1.1 Introduction                        .. 10 1.2 Background                        .. 10 1.2.1 History of Air Quality Planning in the San Antonio Region  11 1.2.2 The Clean Air Plan                  .. 12 1.3 Public Involvement Program                  12 Chapter 2: Emissions Inventory                      18 2.1 Overview                           18 2.2 Point Sources                       . 18 2.3 Area Sources                         19 2.4 On Road Mobile Sources                    19 2.5 Non Road Mobile Sources                  . 19 2.6 Biogenic Sources                      . 20 2.7 Emissions Summary                     . 20 Chapter 3: Photochemical Modeling                   . 23 3.1 Introduction                          23 3.2 Episode Selection                       23 3.3 Modeling/ Analysis Protocol                  . 26 3.4 1999 Meteorological Model                  . 28 3.5 1999 Modeling Emissions Inventory              . 29 3.5.1 Local Emissions Inventory                . 30 3.5.2 Texas and Regional Emissions Inventories          31 3.5.3 QA/ QC Methodology and Preparation of EI Data for Photochemical Modeling                  32 3.6 1999 Photochemical Model Base Case and Performance Evaluation                          33 3.6.1 Evaluation Methodology                  33 3.6.2 Ozone Metrics                     . 35 3.6.3 Predictions of Precursor Concentrations         . 40 3.6.4 Precursor Sensitivity Studies                41 3.7 2007 Future Case Modeling Emissions Inventory        .. 43 3.8 2007 Photochemical Model Base Case and Sensitivity Analyses   45 3.9 Attainment Demonstration Process              .. 50 3.9.1 Design Values and Relative Reduction Factors      . 50 3.9.2 Modeled Attainment Test                .. 51 3.9.3 Screening Test                      52 3.10 Summary and Recommendations               . 53 SIP Revision Attainment Demonstration for the San Antonio EAC Region 5 Table of Contents ( continued) Page Chapter 4: Data Analysis                         55 4.1 Introduction                          55 4.2 Levels and Trends in Ozone Concentrations           55 4.3 Analysis of Meteorological Data                . 59 4.4 Transport and Local Contributions to Ozone Concentrations     62 4.5 Conclusion                         . 62 Chapter 5: Clean Air Strategies                     . 64 5.1 Introduction                          64 5.1.1 Challenges to Local Clean Air Strategies         . 66 5.1.2 Challenges: Degreasing Equipment Controls       .. 68 5.1.3 Conclusion                      . 70 5.2 Federal and State Reduction Strategies            .. 71 5.3 Local Clean Air Strategies                  .. 72 5.4 Strategy Testing                        73 5.5 Additional Evidence                     . 74 5.5.1 Evidence Supporting Attainment Demonstration       74 5.5.2 Degreasing Emissions                  74 5.5.3 Pollution Transport                  .. 75 5.5.4 Alternative Fuel Vehicles                 75 5.5.5 Energy Efficiency / Renewable Energy Projects     . 75 5.5.6 Lawnmower Recycling Program            .. 76 5.5.7 Lower Reid Vapor Pressure               76 5.5.8 Windshield Wiper Fluid                  77 5.5.9 Gas fired Water Heaters, Small Boilers, and Process Heaters                       .. 77 5.5.10 Transportation Demand Management          .. 78 5.5.11 Transportation Emission Reduction Measures      .. 78 5.5.12 TransGuide                       79 5.5.13 Public Education                   .. 79 5.6 Summary and Recommendations               . 79 Chapter 6: Maintenance for Growth                   .. 82 6.1 Background                          82 6.2 Maintenance Analysis                     82 6.3 Updating the Planning Process                . 88 6.3.1 Modeling Updates and Modeling Assumption Verification  . 88 6.3.2 Transportation Patterns                  89 6.4 New Strategy Requirements                 .. 89 SIP Revision Attainment Demonstration for the San Antonio EAC Region 6 List of Tables Page Table 1 1 Public Reporting of EAC Milestones              . 13 Table 3 1 Comparisons of Mean Daily Statistics with Performance Benchmarks for Selected Urban Regions            . 29 Table 3 2 Average Weekday ( Wednesday) Anthropogenic VOC Emissions in the Four county SAER Calculated for the September 1999 Episode                          .. 30 Table 3 3 Average Weekday ( Wednesday) Anthropogenic NOx Emissions in the Four county SAER Calculated for the September 1999 Episode                          .. 30 Table 3 4 Statistical Metrics (%), Based on the Predicted Daily Maximum Ozone Concentration within a 7x7 Array of Grid Cells Near Each Monitor, used to Assess 8 hour Performance of the September 13 20, 1999 Photochemical Model in Central Texas       .. 37 Table 3 5 Statistical Metrics (%), Based on the Predicted Daily Maximum Ozone Concentration within a 7x7 Array of Grid Cells Near Each Monitor that is Closest in Magnitude to the Observed Daily Maximum, used to Assess 8 hour Performance of the September 13 20, 1999 Photochemical Model in Central Texas       .. 37 Table 3 6 Statistical Metrics (%), Based on a Bilinear Interpolation of Predicted Daily Maximum Ozone Concentration, used to Assess 8 hour Performance of the September 13 20, 1999 Photochemical Model in Central Texas                     37 Table 3 7 Estimated 2007 Average Weekday ( Wednesday) VOC Emissions from Anthropogenic Sources in the Four county SAER      . 44 Table 3 8 Estimated 2007 Average Weekday ( Wednesday) NOx Emissions from Anthropogenic Sources in the Four county SAER      . 44 Table 3 9 Percent Difference between Estimated Weekday VOC Emissions for 1999 and 2007 in the Four county SAER           44 Table 3 10 Percent Difference between Estimated Weekday NOx Emissions for 1999 and 2007 in the Four county SAER           45 Table 3 11 Comparison of 1999 and 2007 Predicted Ozone Concentrations by Monitor                         .. 45 Table 3 12 Results of Sensitivity Runs Conducted at CAMS 23 ( San Antonio Northwest   Marshall High School)                48 Table 3 13 Results of Sensitivity Runs Conducted at CAMS 58 ( Camp Bullis) .. 49 Table 3 14 Results of Sensitivity Runs Conducted at CAMS 59 ( Calaveras Lake)                           .. 49 Table 3 15 Results of Sensitivity Runs Conducted at CAMS 678 ( CPS Pecan Valley)                           . 50 Table 3 16 Selection of Current Monitored Design Values based on Comparison of 1998   2000 Values with 2001   2003 Values   . 51 Table 3 17 Modeled Attainment Test Results at SAER Monitors       . 51 Table 3 18 Modeled Attainment Test Results that Account for Implementation of Stage I Vapor Recovery                  .. 52 Table 3 19 Screening Cell Design Value Scaling Results          . 53 SIP Revision Attainment Demonstration for the San Antonio EAC Region 7 List of Tables ( continued) Page Table 5 1 SAER VOC Emission Reduction Estimates for an Average Weekday ( Wednesday)                     64 Table 5 2 SAER NOx Emission Reduction Estimates for an Average Weekday ( Wednesday)                     64 Table 5 3 State and Federal Issued Rules                . 71 Table 5 4 Locally Issued Rules                      73 Table 5 5 Comparison of 1999 and 2007 Base Cases & Adopted Control Strategies                         .. 73 Table 5 6 Projected Ozone Reductions by Local Reduction Strategies     74 Table 5 7 Reduced Emissions from " Mow Down Smog" Recycling Program  76 Table 5 8 Reductions for SAER Counties with RVP 7.2 Gasoline, Compared with RVP 7.8                        .. 77 Table 6 1 Point Source VOC & NOx Emissions of New Point Source Projects                          .. 84 Table 6 2 Airport/ Military Emissions for the San Antonio EAC Region    .. 85 Table 6 3 Biogenic Emissions for the San Antonio EAC Region        85 Table 6 4 Anthropogenic Emissions within the San Antonio Early Action Compact Region                      .. 86 Table 6 5 Anthropogenic Emissions within the SAER, 2007 2012       87 SIP Revision Attainment Demonstration for the San Antonio EAC Region 8 List of Figures Page Figure 2 1 September 15, 1999 ( Wednesday) VOC Emissions Inventory for the San Antonio EAC Counties                21 Figure 2 2 September 15, 1999 ( Wednesday) NOx Emissions Inventory for the San Antonio EAC Counties                21 Figure 2 3 Estimated Wednesday, September 2007 VOC Emissions Inventory for the San Antonio EAC Counties               . 22 Figure 2 4 Estimated Wednesday, September 2007 NOx Emissions Inventory for the San Antonio EAC Counties                22 Figure 3 1 Eight hour Average Daily Maxima during the Ramp up Period and Modeling Episode, September 13  20, 1999, Recorded by Monitors in the San Antonio Region              . 25 Figure 3 2 Modeling Domain used to Simulate the September 13   20, 1999 High Ozone Episode                     . 27 Figure 3 3 Locations of Central Texas Air Quality Monitors in the Model's 4 km Grid System                      . 35 Figure 3 4 Observed and Predicted ( within 7x7 array of grid cells near each monitor) Daily Maximum 8 hour Ozone Concentrations at Central Texas Monitors                       . 38 Figure 3 5 Observed and Predicted ( within 7x7 array of grid cells near each monitor that is closest in magnitude to the observed daily maximum) Daily Maximum 8 hour Ozone Concentrations at Central Texas Monitors                     39 Figure 3 6 Observed and Predicted ( based on a bilinear interpolation of daily maximum ozone concentrations around each monitor) Daily Maximum 8 hour Ozone Concentrations at Central Texas Monitors                       . 39 Figure 3 7 Comparison of Observed and Predicted ( Run 18) NOx Concentrations at CAMS 27 during the September 13 20, 1999 Episode                          .. 40 Figure 3 8 Comparison of Observed and Predicted ( Run 18) NOx Concentrations at CAMS 59 during the September 13 20, 1999 Episode                          .. 41 Figure 3 9 Comparison of Observed and Predicted ( Run 18) NOx Concentrations at CAMS 62 during the September 13 20, 1999 Episode                          .. 41 Figure 3 10 Predicted Ozone Concentrations at CAMS 23 after Removing Local ( 4 county SAER) NOx and VOC Emissions, average from September 15   20, 1999                    42 Figure 3 11 Predicted Ozone Concentrations at CAMS 58 after Removing Local ( 4 county SAER) NOx and VOC Emissions, average from September 15   20, 1999                    43 Figure 3 12 Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for a Typical Weekday ( Wednesday, September 15th)            . 46 Figure 4 1 Annual Peak 1 hour and 8 hour Ozone Measurements within SAER                           . 55 SIP Revision Attainment Demonstration for the San Antonio EAC Region 9 List of Figures ( continued) Page Figure 4 2 San Antonio Eight hour Ozone Design Value Trends by Site   .. 57 Figure 4 3 Annual Number of Days in which Measured 8 hour Averages Met or Exceeded 85 ppb at SAER Monitors            58 Figure 4 4 High Ozone Readings by Two week Period for San Antonio Region                           . 58 Figure 4 5 High Ozone Readings by Two week Period for Major Texas Urban Areas                           .. 59 Figure 4 6 Daily 8 hour Ozone Maxima Measured at CAMS 23 v. Peak Temperature, 1998   2002                   61 Figure 4 7 Daily 8 hour Ozone Maxima v. Average Wind Speeds, 1997   2002                             61 Figure 4 8 Comparison of Daily 8 hr Maxima & Daily Solar Radiation Maxima, 1999 2002                     . 61 Figure 6 1 Trend of VOC and NOx Emissions in the SAER, 1996, 1999, 2007, 2012                         . 87 SIP Revision Attainment Demonstration for the San Antonio EAC Region 10 CHAPTER 1: GENERAL 1.1 INTRODUCTION The Clean Air Act is the comprehensive federal law that regulates airborne emissions from area, mobile, and stationary sources across the United States. This law authorizes the U. S. Environmental Protection Agency ( EPA) to establish National Ambient Air Quality Standards ( NAAQS) to protect public health and the environment.

Of the many air pollutants commonly found throughout the country, the EPA has recognized six " criteria" pollutants that can injure health, harm the environment, and cause property damage. EPA refers to these pollutants as " criteria" air pollutants because the agency has regulated them by first developing health based criteria ( science based guidelines) as the basis for setting permissible levels. The NAAQS are a listing of the threshold levels, the concentration values above which human health is put at risk, for these criteria pollutants.

During the past several years, air quality planning in the San Antonio region has intensified since ozone concentrations have exceeded the values permitted in the 8 hour ozone NAAQS. Due to legal challenges to the NAAQS and ensuing litigation, the EPA has not formally designated any areas of the United States in violation of the 8 hour ozone NAAQS. However, that designation process is expected to begin as early as 2004. Areas formally designated in violation of the NAAQS and contributing to a violation are called " non attainment areas," a term frequently used in this and many other air quality documents.

Local elected officials, concerned leaders in business and industry, and other citizens committed to air quality planning have worked together for years to create an air quality plan for the citizens of the San Antonio region. This group, meeting as the Air Improvement Resources ( AIR) Committee of the Alamo Area Council of Governments ( AACOG), has proactively created an air quality plan that is comprehensive, flexible, and relies on EPA approved technical analysis for its control strategy recommendations.

1.2 BACKGROUND During the ozone seasons of 1997 through 2000, local air quality monitors recorded ozone levels above the concentrations allowed under the 8 hour ozone NAAQS. Moreover, in June of 2002, area monitors recorded some of the highest 8 hour and 1 hour ozone values on record since 19981. In December 2003, the EPA indicated its intent, barring review of compelling evidence from the State to the contrary, to designate the counties of Bexar, Comal, Guadalupe, and Wilson as non attainment of the 8 hour ozone NAAQS. These counties constituted the San Antonio Metropolitan Statistical Area at the time an Early Action Compact, a major component of the area's Clean Air Plan, was developed and submitted to the EPA. Since EPA guidance suggests that Metropolitan Statistical Areas be considered for establishing the boundaries of new 8

1 On June 24, 2002, the CAMS 23 monitor, located near Marshall High School in San Antonio, recorded a 1 hour average ozone value of 126 parts per billion, an exceedance of the 1 hour ozone NAAQS. The most recent exceedance of the 1 hour standard prior to this date was 141 ppb recorded September 4, 1998 at CAMS 58 in Camp Bullis. Also on June 24, 2002, the CAMS 23 monitor recorded an 8 hour average ozone reading of 110 ppb, an exceedance of the 8 hour average ozone NAAQS. The most recent 8 hour reading prior to this date above 100 ppb was a reading of 110 ppb recorded September 4, 1998 at CAMS 58 in Camp Bullis. SIP Revision Attainment Demonstration for the San Antonio EAC Region 11 hour ozone non attainment areas, air quality planning focused on Bexar, Comal, Guadalupe and Wilson Counties.

1.2.1 History of Air Quality Planning in the San Antonio Region As early as 1995, the Air Quality Committee of the Alamo Area Council of Governments, chaired by Senator Jeff Wentworth, first met to address air quality issues in the San Antonio region. This committee requested the first emissions inventory, for inventory year 1994.

In January 1996, the San Antonio Mayor's Blue Ribbon Committee on Air Quality merged with the Air Quality Committee of the Alamo Area Council of Governments ( AACOG) to form the Air Quality Task Force ( AQTF). The charge of the AQTF was to develop public education and provide advice to elected officials on air quality issues. The major accomplishment of the early AQTF was the establishment of the Ozone Action Day program. During FY 1996  1997, the AQTF provided input on the first Near Non Attainment grant, authorized by the 1997 Texas Legislature.

However, when, in the summer of 1996, the EPA proposed the new eight hour ozone NAAQS, the focus of the AQTF began to shift, first by providing comments and guidance on the impact of the new eight hour ozone NAAQS. In the summer of 1998 a local contingency met with EPA's Region 6 to begin discussion on the development of a Flexible Attainment Region ( FAR) agreement.

The AACOG developed its first photochemical model in 1997 along with sponsoring air quality monitoring efforts at St. Hedwig ( southeast Bexar County) during the 1997 ozone season. Monitoring results indicated that on high ozone level days, background levels coming into Bexar County were at or near ozone NAAQS threshold levels. Later that year when EPA finalized the eight hour NAAQS it became apparent that, based on historical data, the SAER could well be designated non attainment when the EPA made the first eight hour non attainment designations initially scheduled for July 2000.

During July 1998, the City of San Antonio ( COSA), San Antonio Bexar County Metropolitan Planning Organization ( MPO), Bexar County, and AACOG staff recommended to elected officials that the AQTF be revised to fit the structure advised by the Texas Commission on Environmental Quality ( TCEQ), then known as the Texas Natural Resource Conservation Commission ( TNRCC). During January  February 1999, the Boards of Directors and other responsible parties representing COSA, Bexar County, MPO, and AACOG approved the formation of the Air Improvement Resources ( AIR) Committee consortium including the Executive/ Advisory, Technical, and Public Education Committees and member appointments. The AIR Committee conducted its first official meeting during April 1999 with the goal to establish an organized, comprehensive, and aggressive plan of action to keep the SAER from slipping into nonattainment of the ozone standard.

Working with partners in the near non attainment areas across Texas, the AACOG has developed a second photochemical model for September 1999. This episode models ozone formation for four of the five near non attainment areas of the state, Corpus Christi, Austin, Victoria and San Antonio. AACOG is now expanding the network of ozone and meteorological monitoring stations in the San Antonio region. The TCEQ is responsible for maintaining monitors upon which official air quality data depends. Better monitoring allows for refined technical analysis of human exposure to ozone, a greater SIP Revision Attainment Demonstration for the San Antonio EAC Region 12 understanding of the formation and movement of ozone in the region, and provides a database for verification of the performance of future photochemical models.

1.2.2 The Clean Air Plan On December 9, 2002 the Clean Air Plan for the San Antonio Region was signed by elected officials representing the SAER. The Clean Air Plan was designed to enable a local approach to ozone attainment and to encourage early emission reductions that will help keep the SAER in attainment of the 1 hour ozone NAAQS and ensure attainment of the 8 hour ozone NAAQS, and so protect human health.

This Clean Air Plan also incorporates the Early Action Compact for the San Antonio area. The Early Action Compact protocol was endorsed by EPA Region 6 on June 19, 2002, and is designed to develop and implement control strategies, account for growth, and achieve and maintain the 8 hour ozone standard. As such, it represents a key component to finalizing this area's Clean Air Plan.

Since its first meeting, the AIR Committee has worked to transform the results of its planning effort into a protocol able to address air quality planning requirements originating with the Clean Air Act. The AIR Committee recognizes that the Clean Air Plan provides the means to sustain the region's air quality by proactively seeking local solutions within a suitable state and federally approved protocol.

The Clean Air Plan is designed to be a working document providing comprehensive planning for the ozone challenge faced by the citizens of the entire SAER. Adoption of this Clean Air Plan requires development of control strategies, or methodologies for lowering ozone concentrations to acceptable levels, which are designed to meet the region's clean air challenge. The technical analysis of the photochemical modeling, used to demonstrate the effectiveness of the control strategies, is performed by the staff of AACOG and is reviewed and approved by the AIR Committee, the staff of AACOG, the TCEQ, and the EPA.

1.3 PUBLIC INVOLVEMENT PROGRAM The EAC for the San Antonio region requires that the AIR Committee be responsible for the assessment and reporting of the region's progress against milestones with deliverables sent to TCEQ and the EPA and reported in a regular, public process at least every six months. Public reporting of assessment and progress against milestones occurs at least once every six months during the regularly scheduled, public meetings ( scheduled on a monthly basis), of the joined AIR Executive/ Advisory Committees of the AACOG. Every regularly scheduled meeting of the AIR Executive and Advisory Committees is a public meeting, with notification of the meeting time and location published by AACOG according to the Texas Open Meetings Act.

EAC milestones were discussed during the AIR Executive/ Advisory Committee meetings conducted at the Alamo Area Council of Governments, 8700 Tesoro Drive, Suite 100, San Antonio, Texas on the dates provided in table 1 1.

In addition to the meetings listed in table 1 1, AACOG conducted public workshops in all four SAER counties to discuss elements of the Clean Air Plan and obtain citizen feedback. Meeting topics and meeting dates for these public workshops are provided in appendix J, " Modeling/ Analysis Protocol." SIP Revision Attainment Demonstration for the San Antonio EAC Region 13 Table 1 1. Public Reporting of EAC Milestones.

Milestone Date of Air Improvement Resources ( AIR) Public Meeting in which Progress was Assessed/ Reported Emissions Inventory Milestones Development of a 1999 or later episode emissions inventory 4 23 03 Agenda Item: Clean Air Plan Update   MOBILE6 On

Road Update Incorporation of MOBILE6 data with link based Travel Demand Model data 4 23 03 Agenda Item: Clean Air Plan Update   MOBILE6 On

Road Update 10 1 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   Attainment Demonstration Model Status Development of additional emission inventory episode data based on local Conceptual Model update. Development of other episode inventories, if required, made in concert with EPA, TCEQ, and local entities 4 23 03 Agenda Item: Clean Air Plan Update   Conceptual Model Development of NONROAD model data adjusted for local equipment populations and usage rates and development of area source data based, when possible, on local survey data 8 27 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   2007 Projection in the Photochemical Model Completion of an Emissions Trend Analysis Report utilizing the National Emissions Trends Emissions Inventories 8 27 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   Trend Analysis 10 1 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   Final Approval of the Trend Analysis Modeling Milestones Development of SIP quality modeling episodes that perform within the EPA's accepted margin of accuracy by completion of the following modeling related tasks:

Develop base case on or before December 31, 2007

Develop future case on or before December 31, 2007

Provide documentation to TCEQ and EPA

Evaluate quantifiable emission reduction measures in the future case to produce one or more control cases

Evaluate control strategies against control case model. 4 23 03 Agenda Item: Clean Air Plan Update   Photochemical Model Update 7 23 03 Agenda Item: Clean Air Plan Update   Photochemical Modeling Update 8 27 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   2007 Projection in the Photochemical Model SIP Revision Attainment Demonstration for the San Antonio EAC Region 14 Milestone Date of Air Improvement Resources ( AIR) Public Meeting in which Progress was Assessed/ Reported Modeling Milestones ( continued) 10 1 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   Attainment Demonstration Model Status 10 1 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   Final Approval of the 2007 Photochemical Model Projection 10 29 03 Agenda Item: AIR Technical Committee Reports   Attainment Demonstration Model Status Development of other episodes, as necessary, to fully represent the variety of situations that typically contribute to local ozone production 4 23 03 Agenda Item: Clean Air Plan Update   Conceptual Model Note: Based on current Conceptual Model analyses, no other photochemical model episodes are planned at this time Control Strategy Development Milestones Identify additional local controls, as necessary, to demonstrate 2007 attainment of the 8 hour standard.

Implement controls by December 31, 2005, with full local stakeholder participation. 2 26 03 Agenda Item: Clean Air Plan Update   Review of Control Strategy Matrix 3 26 03 Agenda Item: Clean Air Plan Update   Review of Control Strategy Matrix 4 23 03 Agenda Item: Clean Air Plan Update   Submission of Draft Clean Air Strategies 5 28 03 Agenda Item: Clean Air Plan Update   Submission of Draft Clean Air Strategies 8 27 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   Update to the Clean Air Strategies SIP Revision Attainment Demonstration for the San Antonio EAC Region 15 Milestone Date of Air Improvement Resources ( AIR) Public Meeting in which Progress was Assessed/ Reported Control Strategy Development Milestones ( continued) 10 1 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   Update to the Clean Air Strategies 10 29 03 Agenda Item: AIR Technical Committee Reports   Update to the Clean Air Strategies 12 22 03 Agenda Item: Technical Updates  Further Modeling of Clean Air Strategies for the EAC Provide control measures to TCEQ for incorporation into the State Implementation Plan 1 28 04 Agenda Item: Clean Air Plan   Action Item: Approve Clean Air Strategies List Recommended by the AIR Technical Committee for the State Implementation Plan 3 3 04 Agenda Item: Clean Air Plan   Clean Air Strategies Update 3 24 04 Agenda Item: Clean Air Plan   Clean Air Strategies Update and Action Item: Approval of finalized Clean Air Plan and Signed Letter of Submission addressed to TCEQ/ EPA Maintenance for Growth Milestones Address emissions growth at least 5 years beyond December 31, 2007 to ensure the area will remain in attainment of the 8 hour standard during that period 8 27 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   Trend Line Analysis Continue the planning process by including updates to modeling and verification of modeling assumptions ( particularly growth assumptions) 4 23 03 Agenda Item: Clean Air Plan Update   Photochemical Model Update 7 23 03 Agenda Item: AIR Technical Committee Reports   Photochemical Modeling Update 8 27 03 Agenda Item: Milestones and Timelines in the Clean air Plan   2007 Projection in the Photochemical Model SIP Revision Attainment Demonstration for the San Antonio EAC Region 16 Milestone Date of Air Improvement Resources ( AIR) Public Meeting in which Progress was Assessed/ Reported Incorporate additional measures to the plan if the review of growth demonstrates that adopted control measures are inadequate to address increases in emissions 10 1 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   Final Approval of September 30 EAC Milestones Action Item: Final Approval: Trend Analysis Public Involvement Milestones Encourage public involvement in all stages of the planning and implementation process. Involve stakeholders in the planning process as early as possible.

Conduct public education programs to raise awareness regarding issues, opportunities for involvement in the planning process, and implementation of control strategies.

Make draft plans publicly available and allow sufficient opportunities for comment from all interested stakeholders.

Present and make publicly available semi annual reports detailing, at a minimum, progress toward milestones 1 29 03 Agenda Item: Citizen Comments at First Public Meeting on the Clean Air Plan Conducted January 22, 2003 2 26 03 Agenda Item: Citizen Comments at Second Public Meeting on the Clean Air Plan Conducted February 22, 2003 3 26 03 Agenda Item: Citizen Comments at Third Public Meeting on the Clean Air Plan Conducted March 19, 2003 3 26 03 Agenda Item: Clean Air Plan Update   Business and Industry Outreach 4 23 03 Agenda Item: Citizen Comments at the Fourth Public Meeting on the Clean Air Plan Conducted April 12, 2003 4 23 03 Agenda Item: Discussion of Issues of Public Participation and the Early Action Compact 4 23 03 Agenda Item: Clean Air Plan Update   Biannual Progress Report 5 28 03 Agenda Item: Citizen Comments at the Fifth Public Meeting on the Clean Air Plan Conducted May 20, 2003 5 28 03 Agenda Item: Clean Air Plan Update   Review of First Biannual Progress Report SIP Revision Attainment Demonstration for the San Antonio EAC Region 17 Milestone Date of Air Improvement Resources ( AIR) Public Meeting in which Progress was Assessed/ Reported Public Involvement Milestones ( continued) 6 18 03 Agenda Item: Citizen Comments at the Sixth Clean Air Plan Workshop of 2003 Conducted on June 14, 2003 6 18 03 Agenda Item: Clean Air Plan Update   Approval of First Biannual Progress Report 7 23 03 Agenda Item: Citizen Comments at the Seventh Clean Air Plan Workshop of 2003 Conducted July 16, 2003 8 27 03 Agenda Item: Milestones and Timelines in the Clean Air Plan   Ongoing Local Efforts 10 1 03 Agenda Item: Other Issues For Discussion   Public Presentation of Clean Air Strategies 10 29 03 Agenda Item: Other Issues   Clean Air for Central Texas Public Presentation/ Workshop for Clean Air Strategies Scheduled for November 5, 2003 12 22 03 Agenda Item: Clean Air Plan   Action Item EAC Milestone Approval: 2nd Biannual Progress Report SIP Revision Attainment Demonstration for the San Antonio EAC Region 18 CHAPTER 2: EMISSIONS INVENTORY 2.1 OVERVIEW The 1990 Amendments to the federal Clean Air Act ( FCAA) and 40 CFR, § 51.322 require that emissions inventories ( EI) be prepared statewide, particularly for ozone nonattainment areas. The chemical species that form ozone include volatile organic compounds ( VOC), nitrogen oxides ( NOx), and to a more limited degree, carbon monoxide ( CO). Because ground level ozone forms photochemically ( i. e., in the presence of sunlight) as the result of VOC, NOx and CO chemical reactions, it is critical that planners identify and quantify these precursor pollutants. The EI describes sources of precursors within a region as well as the amount of each pollutant emitted and any processes and control devices in use.

EI data are used in support of a variety of air quality planning tasks, including establishing baseline emission levels, calculating reduction targets, developing control strategies, developing emission inputs for air quality simulation models, and tracking actual emission reductions against the established emissions growth and control budgets. This chapter focuses on the development of EI data used in the development of a photochemical model that simulates an elevated ozone episode that occurred in September 1999. This San Antonio area base case EI includes VOC, NOx, and CO emissions for the September 1999 episode for five general categories of emissions sources, as described below.

2.2 POINT SOURCES Major point sources include industrial, commercial, or institutional sources that emit criteria pollutants at or above thresholds established by the FCAA. For nonattainment areas, this threshold varies from 10 tons per year ( tpy) to 100 tpy depending on the pollutant in question and the seriousness of the nonattainment problem. For the attainment areas of the state, any source that emits a minimum of 100 tpy of a regulated pollutant must complete an inventory. Additionally, any source that generates or has the potential to generate at least 10 tpy of any single hazardous air pollutant ( HAP) or 25 tpy of aggregate HAPs is also required to report emissions to the Texas Commission on Environmental Quality ( TCEQ).

To collect emissions and industrial process operating data for these plants, the TCEQ mails Emissions Inventory questionnaires ( EIQ) to all sources identified as having emissions that trigger the reporting requirements. Companies must report the type of emissions from all emission generating units and emission points, as well as the amount of materials used in the processes that result in emissions. The EIQ also requests information on process equipment, operation schedules, emissions control devices, abatement device control efficiency, and stack parameters such as location, height, and exhaust gas flow rate. All data submitted via the EIQ are subjected to rigorous quality assurance procedures by the technical staff of the Industrial Emissions Assessment Section, and are then entered into the Point Source Data Base ( PSDB) by the Data Services Section. SIP Revision Attainment Demonstration for the San Antonio EAC Region 19 2.3 AREA SOURCES Area sources are defined as emission sources that fall below the point source reporting levels, and are too numerous or too small to identify individually. Area sources include commercial, small scale industrial, and residential sources that use materials or operate processes generating VOC, NOx, or CO emissions. Area sources can be divided into two groups   hydrocarbon evaporative emissions or fuel combustion emissions   depending on the emission mechanism. Examples of activities that generate evaporative losses include printing, application of industrial coatings, use of degreasing solvents, house painting, leaking underground storage tanks, gasoline service station underground tank filling, and vehicle refueling operations. Fuel combustion sources include stationary source fossil fuel combustion at residences and businesses, as well as outdoor burning, structural fires, and wildfires. These emissions, with some exceptions, may be calculated by multiplication of an established emission factor ( emissions per unit of activity) times the appropriate activity. If the activity level is difficult to obtain or measure, surrogate data may be used to develop emissions estimates. Population is the most commonly used surrogate for many area source categories, while other activity data include amount of gasoline sold in an area, employment by industry type, and acres of cropland.

2.4 ON ROAD MOBILE SOURCES On road mobile sources consist of automobiles, trucks, motorcycles, and other motor vehicles traveling a region's roadways. Combustion related emissions are estimated for vehicle engine exhaust, and evaporative hydrocarbon emissions are estimated for the fuel tank and other sources of leaks from vehicles. Emission factors were developed using the EPA's mobile emission factor model, MOBILE6. Model inputs were developed specifically for the San Antonio area. These inputs include such parameters as vehicle speeds by roadway type, vehicle registration by vehicle type and age, percentage of miles traveled by vehicle type, and gasoline vapor pressure. All of these inputs have an impact on the emission factor calculated by the MOBILE model, and every effort is made to use parameters reflecting local conditions. To complete the emissions estimate, the emission factors calculated by the MOBILE model must be multiplied by a measure of vehicle activity: vehicle miles traveled ( VMT). The level of vehicle travel activity is developed from the federal Highway Performance Monitoring System ( HPMS) data compiled by the Texas Department of Transportation for each county. Finally, roadway speeds, which are required for the MOBILE model's input, are obtained from an analysis for several roadway types performed by the Texas Transportation Institute ( TTI).

2.5 NON ROAD MOBILE SOURCES Non road mobile sources include aircraft operations, recreational boats, residential and commercial lawn maintenance equipment, railroad locomotives, and a wide range of offhighway equipment. Methods for calculating emissions from non road engine sources are based on information about equipment populations, engine horsepower, load factor, emission factor, and annual usage. With the exception of aircraft and locomotives, nonroad emissions were estimated using EPA's NONROAD model. Aircraft emissions were estimated using the Emissions and Dispersion Modeling System ( EDMS) aircraft emissions model. Model inputs were obtained from airport documents containing landing and takeoff data. Locomotive emissions were developed from fuel usage and track mileage data obtained from individual railroads. SIP Revision Attainment Demonstration for the San Antonio EAC Region 20 2.6 BIOGENIC SOURCES Biogenics refers to natural sources of emissions, primarily vegetation ( e. g., crops, lawn, and forests). Vegetation emits VOCs such as isoprenes, monoterpenes, and alphapinenes Natural processes in soil also contribute to ozone by emitting a small amount of NOx. The biogenic emission inventory for the San Antonio region was developed by ENVIRON International Corporation, under contract with the TCEQ, using version 2.2 of the GloBEIS biogenic emissions model. Emissions were calculated at the county level for an ozone season day in 1999 by using weather conditions typical of the September 1999 timeframe as model input. The model was further enhanced through the use of the TCEQ's landuse/ landcover ( LULC) database.

Emissions from biogenic sources are natural; therefore controls on biogenic sources are not appropriate. Nevertheless, biogenic emissions are part of the ozone chemistry and must be included in both the base and future case photochemical modeling to ensure that the overall chemical profile is correct. Only anthropogenic emissions are included in control strategy testing, however.

2.7 EMISSIONS SUMMARY The base case EI for the four SAER counties are summarized in figures 2 1 ( VOC) and 2 2 ( NOx). These numbers represent emission estimations for September 15, 1999 ( Wednesday), chosen to represent an average weekday.

The percent contributions from VOC sources in the September 15, 1999 base case inventory include the following: 53.8% from biogenic, 26.6% from area/ non road, 18.2% from on road, and 1.5% from point sources. The percent contributions from NOx sources for the September 15, 1999 EI include: 45.7% from on road, 32.3% from point sources, 15.3% from area/ non road, and 6.7% from biogenic.

Natural sources ( biogenics) are included in the summary. However, control strategies are limited to the reduction of anthropogenic emissions.

In addition to creating a 1999 base case EI, a 2007 future base EI was developed to facilitate attainment demonstration modeling. The 2007 EI was projected from 1999 emissions using growth factors and control factors. Figures 2 3 ( VOC) and 2 4 ( NOx) summarize the 2007 future base EI for the four San Antonio EAC counties. The percent contributions from VOC sources in the September 2007 ( Wednesday) future case inventory include the following: 59.5% from biogenic, 26.0% from area/ non road, 11.5% from on road, and 3.1% from point sources. The percent contributions from NOx sources for the September 2007 EI include: 36.5% from on road category, 33.3% from point sources, 21.0% from area/ non road, and 9.3% from biogenic. SIP Revision Attainment Demonstration for the San Antonio EAC Region 21 Figure 2 1. September 15, 1999 ( Wednesday) VOC Emissions Inventory for the San Antonio EAC Counties.

Figure 2 2. September 15, 1999 ( Wednesday) NOx Emissions Inventory for the San Antonio EAC Counties. On road 18.2%

Area/ Non road 26.6% Point 1.5% Biogenic 53.8% Tons/ Day Percent On road 88.8 18.2% Area/ Non road 130.2 26.6% Point 7.2 1.5% Biogenic 263.0 53.8%

Total 489.2 100.0%

On road 45.7%

Area/ Non road 15.3% Point 32.3% Biogenic 6.7% Tons/ Day Percent On road 143.6 45.7%

Area/ Non road 48.1 15.3% Point 101.3 32.3% Biogenic 21.0 6.7%

Total 314.0 100.0% SIP Revision Attainment Demonstration for the San Antonio EAC Region 22 Figure 2 3. Estimated Wednesday, September 2007 VOC Emissions Inventory for the San Antonio EAC Counties.

Figure 2 4. Estimated Wednesday, September 2007 NOx Emissions Inventory for the San Antonio EAC Counties. On road 11.5%

Area/ Non road 26.0%

Point 3.1% Biogenic 59.5% Tons/ Day Percent On road 50.7 11.5% Area/ Non road 114.8 26.0% Point 13.5 3.1% Biogenic 263.0 59.5%

Total 441.9 100.0%

On road 36.5%

Area/ Non road 21.0% Point 33.3% Biogenic 9.3% Tons/ Day Percent On road 82.3 36.5% Area/ Non road 47.3 21.0% Point 75.1 33.3% Biogenic 21.0 9.3%

Total 225.7 100.0% SIP Revision Attainment Demonstration for the San Antonio EAC Region 23 CHAPTER 3: PHOTOCHEMICAL MODELING 3.1 INTRODUCTION The Natural Resources staff of the Alamo Area Council of Governments has supported the development of and made refinements to two discrete photochemical models suitable for attainment demonstrations in the San Antonio EAC region. The first was a 1995 episode simulation developed to establish a base case for an attainment demonstration in the region's Early Implementation Plan and O3 Flex Plan. These plans were forerunners to the current Clean Air Plan developed under the TCEQ's and EPA's Early Action Compact protocol. The 1995 model simulation was presented to EPA Region 6 and TCEQ representatives in 2002 and was found adequate for attainment work.

AACOG staff also refined, with the assistance of other agencies2, a 1999 episode that is used to demonstrate attainment in the SAER's Early Action Compact SIP. Development of the September 15th through 20th, 1999 episode model was sponsored by four Southcentral Texas near nonattainment areas3 ( NNA) and TCEQ. During this time span, monitors in the San Antonio region recorded 8 hour ambient ozone levels as high as 96 parts per billion ( ppb) 4 as shown in figure 3 1. This exceeds the 85 ppb threshold established by the " eight hour average ozone standard" in the 1997 amendments to the Clean Air Act. Similarly, other urban areas of South and Central Texas also experienced elevated ozone concentrations.

The intent of developing the 1999 simulation was to provide a base case as the first step in projecting air quality conditions to the year 2007 so that clean air measures could be modeled and analyzed for their effectiveness in that future time period. The year 2007 was chosen because it coincides with the attainment dates for the largest metropolitan areas of Texas including Dallas Fort Worth and Houston. By that date, three of the four Texas nonattainment areas should have control strategies in place. Since ambient ozone levels in San Antonio can be affected by transport of pollution from Houston and other areas, selecting a date in which control strategies are in place for other large urban areas is an important modeling consideration. Furthermore, the Early Action Compacts for two Texas regions ( Austin and San Antonio) require attainment by 2007. As a result, the Texas non attainment and EAC areas benefit from the use of coordinated timelines and coordinated planning of control strategy programs.

3.2 EPISODE SELECTION An initial step in the attainment demonstration model process entailed developing a conceptual description of the SA area's ozone problem. The conceptual model of ozone formation provided a basis for determining subsequent steps in the model development process including those related to episode selection. One of the intents of the conceptual model was to summarize both the local meteorological conditions and associated synoptic weather patterns typically experienced during periods of elevated ozone concentrations. This process was facilitated by assembling and reviewing all available ambient air quality data, meteorological data, and previous photochemical 2 Other entities involved in refining the 1999 base case included the TCEQ, The University of Texas at Austin, and ENVIRON International Corporation. 3 The regions of Austin, Corpus Christi, San Antonio and Victoria. 4 Measured at the Camp Bullis monitor on September 18, 1999. SIP Revision Attainment Demonstration for the San Antonio EAC Region 24 modeling efforts. Appendix A provides a description of the conceptual model developed for the San Antonio region.

Ozone formation in the San Antonio region is influenced by many of the same factors as in other areas of Texas. These factors include sunny skies, high pressure, and low wind speeds. Ozone formation peaks during the warm weather that predominates in the San Antonio region from April through October.

In their draft guidance ( 1999), EPA recommends using four criteria, at a minimum, to select episodes appropriate for modeling. The minimum criteria include: 1) reviewing a mix of episodes that represent a variety of meteorological conditions associated with observed 8 hour daily maxima in excess of 84 ppb; 2) selecting periods in which observed 8 hour daily maxima approximate the average fourth highest 8 hour ozone concentrations; 3) reviewing periods for which extensive air quality/ meteorological data exist; and 4) modeling a sufficient number of days to represent a complete ozone cycle. SIP Revision Attainment Demonstration for the San Antonio EAC Region 25 Figure 3 1. Eight hour Average Daily Maxima during the Ramp up Period and Modeling Episode, September 13  20, 1999, Recorded by Monitors in the San Antonio Region.

Monitoring Site 13 14 15 16 17 18 19 20 San Antonio Northwest C23 57 66 82 85 75 92 89 84 Camp Bullis C58 57 63 79 78 74 96 91 81 CPS Pecan Valley C678 56 57 74 74 64 76 84 86 Calaveras Lake C59 64 64 81 81 76 80 89 84 Numbers in red represent exceedances of the 8 hour average threshold.

Work conducted during the summer of 2000 on the Conceptual Model helped staff identify five candidate episodes for modeling purposes: June 21 23, 1995, August 28   September 3, 1998, August 16   21, 1999, August 30   September 1, 1999, and September 16   20, 1999. However, the June 21 23, 1995, August 16 21, 1999, and August 30   September 1, 1999 episodes were eliminated from consideration because of a lack of meteorological data ( 8/ 30   9/ 1/ 99 episode), an insufficient number of exceedance days ( 8/ 16   8/ 21/ 99 episode), or because the episode occurred prior to the design value period ( 6/ 21   6/ 23/ 95 episode)   a secondary criterion.

Ultimately, the September 13   20, 1999 high ozone episode was chosen for the most recent modeling effort. Both the August September 1998 and September 1999 episodes met the primary selection criteria recommended by the EPA. In addition, both episodes SIP Revision Attainment Demonstration for the San Antonio EAC Region 26 met some secondary criteria, such as inclusion of weekend days and correspondence with the current ( as of Conceptual Model development in September 2000) design value. However, the decision to model the September 1999 episode was based on another secondary selection criterion; i. e., the 1999 time period represented an elevated ozone episode for multiple regions of Texas. The benefits of developing a regional model covering four near non attainment areas included cost sharing and a consistent, Central Texas base case on which to model clean air strategies.

The September episode consists of two model initialization days, September 13th and 14th, and five primary episode days, September 15   20, 1999. Although these days ( 15th 20th) were chosen because they represent a period in which elevated ozone levels occurred in South central Texas, the modeling domain covers a much larger geographical area than South central Texas alone. The larger domain is necessary to simulate the effects of meteorological and atmospheric processes including transport of precursors and background concentrations of ozone to the San Antonio region. The 32 hour back trajectories for the 1999 episode originated in southeastern Missouri. Consequently, the 36 km coarse grid used in the model simulation extends throughout much of the South and Central U. S. including the Ohio River Valley to the north and Atlanta to the east, as shown in Figure 3 2. Furthermore, this matches the TCEQ standard modeling domain. The grid formulation includes two nested grids: a 12 km grid domain that incorporates eastern Texas including the nonattainment areas of Dallas/ Fort Worth, Houston/ Galveston, and Beaumont/ Port Arthur, and an urban scale 4 km grid that covers the four NNAs in South central Texas.

The EAC requires development of other episodes, as necessary, to fully represent the variety of situations that typically contribute to local ozone production. The San Antonio region agreed in the Early Action Compact signed December 2002, to investigate further episode development based on Conceptual Model updates. Updates are scheduled for completion by AACOG by April 30, 2003 and April 30, 2005. Based on the April 2003 update of the Conceptual Model, in an analysis agreed upon by TCEQ, no candidate episodes were revealed.

The 2003 Conceptual Model update was comprehensive of all potential episodes from 1995 through 2002. Although there was one candidate episode in 2002, the meteorological conditions resemble the meteorological patterns in the September 1999 episode. Also, this 2002 episode was potentially useful to Austin and San Antonio; whereas the 1999 episode was useful to Austin, Corpus Christi, San Antonio, and Victoria. As a consequence, the 2002 episode is not a particularly strong candidate. However, if the region is required to perform 2002 modeling, as is currently the case for traditional 8 hour non attainment areas, then this episode may be revisited and developed. Ongoing research will attempt to identify new, viable episodes.

3.3 MODELING/ ANALYSIS PROTOCOL Many stakeholders were involved in the modeling/ analysis protocol process. Decisions as to which modeling episode, air quality simulation model, and modeling consultant( s) to use were made by staff of the TCEQ and representatives of four Texas NNAs: Austin ( Capital Area Planning Council and Central Texas Clean Air Force), Corpus Christi ( City of Corpus Christi), San Antonio ( Alamo Area Council of Governments), and Victoria ( City of Victoria). Modeling decisions were reviewed within the SAER by the Air Improvement Resources Technical Committee which is composed of technical staff representing local SIP Revision Attainment Demonstration for the San Antonio EAC Region 27 governments. Recommendations from the Technical Committee were forwarded to the Air Improvement Resources ( AIR) Executive/ Advisory Committee during regularlyscheduled public meetings for final approval at the local level. For example, the decision to use the September 13   20, 1999 episode for modeling purposes was approved during the August 23, 2000 AIR Executive/ Advisory Committee meeting by voting members of the AIR Committee.

Voting members ( Executive members) of the AIR Committee include one representative each from Bexar County, Comal County, City of Floresville, Guadalupe County, City of New Braunfels, City of San Antonio, City of Seguin, Wilson County, The Alamo Area Council of Governments Board of Directors, Greater Bexar County Council of Cities ( GBCCC) and the San Antonio Bexar County Metropolitan Planning Organization ( MPO).

The Advisory committee, although not consisting of voting members, includes representatives of other governmental entities, numerous industries, and private citizens. Appendix J provides additional information regarding the modeling/ analysis protocol for the SAER.

Figure 3 2. Modeling Domain used to Simulate the September 13   20, 1999 High Ozone Episode. Source: ENVIRON International Corporation. SIP Revision Attainment Demonstration for the San Antonio EAC Region 28 3.4 1999 METEOROLOGICAL MODEL The September 1999 ozone model was developed using the Mesoscale Model ( MM5), the standard meteorological model used by TCEQ and recommended by EPA. The original September 13   20, 1999 meteorological model was developed using version 3.4 of the MM5 model. However, statistical summaries of modeling results indicated certain performance problems. These included consistent over prediction of wind speed at night and under predictions during the daytime; over prediction of early morning temperatures; and marginal performance for both humidity and the overall pressure pattern covering the south central U. S.

It was assumed that the deficiencies in performance were the result of a combination of errors associated with model inputs and the choice of internal model algorithms. Based on results of sensitivity tests, numerous additional iterations of the model were conducted to incorporate new information and improve known deficiencies. These subsequent runs were conducted on the newly released version 3.5 of MM5; and so, took advantage of the additional modeling capabilities of the refined meteorological model. The new runs also incorporated improvements to the boundary layer scheme, radiation scheme, soil moisture scheme, and observational analyses and FDDA techniques.

The final MM5 configuration, referred to as " Met Run 5g," exhibited improved simulation capabilities of surface temperature and pressure gradients over Texas, and improved temperature and humidity performance at the surface. In addition, the EDAS analysis field utilized for large scale grid nudging on Met Run 5g more closely resembled observations than the EDAS initialization package used for other meteorological runs. As a result, the Met Run 5g configuration is the basis for the meteorological fields used in development of the September 13   20, 1999 photochemical model for the San Antonio, area, as well as three other NNA regions. Met Run 5g incorporates the following model physics and options ( CAPCO 2004):

28 sigma levels

Two way interactive 108/ 36/ 12/ 4 km grids

Three dimensional analysis nudging   MM5 was lightly nudged toward 3 hourly gridded EDAS analysis of winds ( in the boundary layer and aloft) and temperature and humidity ( only above the boundary layer), which were improved by the blending of routine surface and upper air observational data

Two dimensional surface analysis nudging   MM5 was lightly nudged toward 3 hourly gridded surface analyses of winds, temperature and humidity

Observation nudging on the 12/ 4 km grids   MM5 was strongly nudged toward discrete hourly wind observations from routine and special measurement networks operating in Texas during the episode

Medium Range Forecast ( MRF) planetary boundary layer scheme

Simple ice cloud microphysics

Kain Fritsch cumulus parameterization, except on 4 km grid

Five layer soil model

RRTM radiation scheme

Reduced soil moisture and thermal inertia to account for drier conditions SIP Revision Attainment Demonstration for the San Antonio EAC Region 29 Table 3 1 provides Met Run 5g performance statistics for several regions within the 4 km domain. These 4 km grid subdomains include Austin / San Antonio, Corpus Christi / Victoria, and Houston / Galveston / Beaumont / Port Arthur. A fourth column lists performance benchmarks for comparison purposes. The benchmarks represent performance goals that were established as the result of comparing statistical summaries of nearly thirty regional meteorological models developed for various areas of the country. The goals reflect the results of meteorological models that were accepted and used in support of regulatory air quality photochemical modeling efforts ( CAPCO, 2004).

The subdomain performance statistics listed in table 3 1are based on comparisons between observations obtained from ground level monitoring stations and Met Run 5g predictions. As indicated by the results, Met Run 5g demonstrated excellent performance for wind speed and direction and good performance for temperature and humidity within the 4 km domain. Since the most important variables passed to the ozone model are wind speed and direction, MM5 performance on other variables is secondary.

Table 3 1. Comparisons of Mean Daily Statistics with Performance Benchmarks for Selected Urban Regions. Values in red denote statistics outside the performance goals ( CAPCO, January 2004). Episode Mean Parameter Benchmark Austin/ San Antonio Corpus Christi/ Victoria Houston/ Galveston/ Beaumont/ Port Arthur Wind Speed RMSE* < 2.0 m/ s 1.2 1.3 1.3 Wind Speed Bias ± 0.5 m/ s 0.0 0.5 0.4 Wind Speed IOA** > 0.60 0.68 0.81 0.63 Wind Direction Gross Error < 30 deg 36 23 30 Wind Direction Bias ± 10 deg  6  5 2 Temperature Gross Error < 2.0 K 2.1 1.3 1.5 Temperature Bias ± 0.5 K  1.3 0.4  0.6 Temperature IOA** > 0.80 0.92 0.92 0.95 Humidity Gross Error < 2.0 g/ kg 1.4 2.4 1.1 Humidity Bias ± 1.0 g/ kg  0.3  1.6  0.3 Humidity IOA** > 0.60 0.47 0.53 0.61 * RMSE: root mean square error ** IOA: index of agreement Development, analysis, and subsequent refinement of the September 13 20, 1999 meteorological model are explained in more detail in appendix B. Appendix B also provides descriptions of the statistical measurements used to evaluate the meteorological model's performance.

3.5 1999 MODELING EMISSIONS INVENTORY In addition to meteorological inputs, photochemical models require emissions inputs that are day and hour specific to the modeled time period. For the September 1999 ozone SIP Revision Attainment Demonstration for the San Antonio EAC Region 30 episode, this required identifying and quantifying sources of VOC, NOx and CO emissions, as ozone forms as the result of chemical reactions between these chemical precursors. In order to prepare emissions for use in an air quality model, the emissions were temporally allocated to account for seasonal differences in emission rates or activity and to apportion emissions to a particular day or hour, in accordance with EPA policy ( EPA April 1999). Furthermore, the emissions were spatially allocated among each grid cell in the modeling domain, both horizontally and vertically.

As described previously, the original September 1999 photochemical simulation failed to meet certain EPA established acceptance criteria for photochemical simulations. Efforts to improve model performance focused on refining the meteorological inputs ( see section 3.3) and the emissions inputs. As a result, the emission inventory for the September 13 20, 1999 episode underwent extensive scrutiny and refinement since development of the original 1999 model simulation. The final mobile on road, area/ nonroad and point source ( anthropogenic) VOC and NOx emission inventories developed for the four county SAER are summarized in tables 3 2 and 3 3, respectively.

Table 3 2. Average Weekday ( Wednesday) Anthropogenic VOC Emissions in the Fourcounty SAER Calculated for the September 1999 Episode.

County On Road ( tpd) Area / Non road ( tpd) Point ( tpd) Total ( tpd) Bexar 75.52 111.98 6.30 193.80 Comal 6.15 6.70 0.34 13.20 Guadalupe 5.57 7.77 0.45 13.78 Wilson 1.57 3.73 0.07 5.37 Total ( tpd) 88.81 130.18 7.17 226.15 Table 3 3. Average Weekday ( Wednesday) Anthropogenic NOx Emissions in the Fourcounty SAER Calculated for the September 1999 Episode.

County On Road ( tpd) Area / Non road ( tpd) Point ( tpd) Total ( tpd) Bexar 119.57 39.39 88.59 247.55 Comal 11.64 3.57 12.16 27.38 Guadalupe 10.47 4.24 0.51 15.21 Wilson 1.89 0.93 0.00 2.82 Total ( tpd) 143.58 48.12 101.26 292.96 3.5.1 Local Emissions Inventory TCEQ provided staff with local biogenic and point source emissions inventories for the 12 county AACOG region. Area and non road inventories were developed by staff using guidance from such documents as EPA's Air Chief and AP 42. Whenever possible, emission calculation methodologies were supplemented with data obtained from surveys. Specific sources that were surveyed in development of the local 1999 EI included quarry operations; power plants; operators of construction, commercial, industrial, railroad, and agricultural equipment; bakeries; wineries; breweries; wastewater treatment plants; and asphalt paving operations.

One of the most significant refinements made to the modeling EI was the use of traffic demand modeling and EPA's MOBILE6 model to develop link based on road inventories SIP Revision Attainment Demonstration for the San Antonio EAC Region 31 for some urban areas of Texas including the 4 county SAER. The original 1999 SAER on road EI was created using a previous version of the model, MOBILE5a_ h. Texas Transportation Institute, under contract with the TCEQ, developed MOBILE6 on road emission estimates for 18 Texas NNA counties. This MOBILE6 EI file, labeled version 1, continued to undergo review during the QA/ QC process.

As a product of their review, an enhanced MOBILE6 on road file, version 2, was developed by TTI to account for an improved methodology for allocating vehicle miles traveled ( VMT) for heavy duty diesel vehicles ( HDDV). The Bexar County MOBILE6 version 2 on road file was provided to AACOG by TCEQ modeling staff on August 29, 2003 and incorporated into the September 1999 photochemical model labeled " CAMx Run 18." Although AACOG eventually received MOBILE6 on road inventories for surrounding SAER counties ( Comal, Guadalupe, and Wilson), the file was not received in time to incorporate into the photochemical model.

To account for the anticipated difference between MOBILE5a_ h and MOBILE6 emission estimations in Comal, Guadalupe, and Wilson counties, an emissions factor was applied to the counties' on road emission data using a software adjustment. This " cntlem" software program was provided to staff by UT Austin.

The on road inventories were developed by TTI for a September 17   20, 1999 timeframe. TTI's documentation on development of NNA on road emission inventories is included as appendix C of this SIP. The process of converting TTI's emissions inventory from an abbreviated episode, September 17 20, 1999, to the complete episode including ramp up period ( September 13   20, 1999), is presented in appendix D.

3.5.2 Texas and Regional Emissions Inventories September 1999 area and non road modeling EIs were developed for three other urban areas within the 4 km subdomain ( the NNA partners participating in the joint modeling project  Austin, Corpus Christi, and Victoria) for inclusion in the photochemical model. Area/ non road files for the remainder of Texas were obtained from the TCEQ and based on the TEXAQS 2000 data set. In order to use this data set for modeling a September 1999 ozone episode, the data were backcast to 1999 using the ratio of 1999/ 2000 emissions as determined by the Economic Growth Analysis System ( EGAS) 4.0 and NONROAD 2000 models.

Non electric generating unit ( NEGU) point source emissions were obtained from the TCEQ's point source database ( PSDB). Electric generating unit ( EGU) point source emissions were provided by the TCEQ from a September 1999 TCEQ emissions package that was updated with data from the 1999 Acid Rain Program Data Base ( ARPDB). This data set applied to all of Texas with the exception of Houston. The 11 county Houston point source file was based on a 2000 NEGU and EGU emissions inventory.

On road mobile EI data for Texas were developed by TTI and provided to staff by TCEQ. MOBILE6, version 1 was used to develop on road emissions for the Houston area, Gregg County and Smith County. On road EI files for the remainder of the state were developed using MOBILE5a_ h.

In some cases the Texas area, non road, and mobile EI data provided by the TCEQ required additional refinement. The modeling EI for the Houston area, for example, was SIP Revision Attainment Demonstration for the San Antonio EAC Region 32 developed for an August 2000 ozone episode. Therefore, the emissions data were backcast from August 2000 to September 1999 using appropriate modeling software such as the EGAS, MOBILE6 and NONROAD models.

Regional EI data for states outside of Texas were provided by the TCEQ. Other than point sources for the State of Louisiana, the TCEQ based the emission rates on EPA's 1999 National Emission Inventory ( NEI v. 2). The point source EI for Louisiana was obtained from the Louisiana Department of Environmental Quality, quality assured by the TCEQ, and updated with September data from the ARPDB.

3.5.3 QA/ QC Methodology and Preparation of EI Data for Photochemical Modeling Several quality assurance/ quality control methodologies were used to assess the reliability of the EI calculations. These included " reality checks" in which calculations were evaluated for reasonableness, peer review of the EI by TCEQ, replication of calculations for some emissions sources, statistical checks, and computerized checks. To conduct computerized checks, staff evaluated computer generated graphics using PAVE software to identify possible problems and make comparisons ( 1999 EI versus 2007 EI for example). This type of check provided an additional benefit; i. e., it allowed analysts to evaluate the spatial allocation of emissions. Examples of these types of comparisons can be found in figures G 1 through G 6 of appendix G.

In addition to checking data for accuracy in terms of calculation methodologies and geographical allocation, data were also evaluated in terms of temporal allocation. This step involved reviewing data distribution by hour of the day, day of the week, and season.

Although the original September 1999 model was developed by ENVIRON and further refined by collaboration between ENVIRON and UT Austin ( meteorological model and air quality input refinements), the model was eventually provided to the NNA partners ( or their contractors) for further modifications. These modifications included refinement of the emissions inventory inputs, development of the future case, and clean air strategy analyses. Because the model was modified by more than one agency during this process, there was a concern that the various agencies' models would be dissimilar and provide different predictions for the base case, future case, and control strategy runs.

As part of the QA/ QC process, a great amount of effort was spent ensuring that the Austin and San Antonio base and future cases contained identical input. Often this involved discussions between the two agencies, as well as TCEQ, regarding the most appropriate model procedures and EI data for local and regional areas. Discrepancies in emissions inputs were corrected prior to the final AACOG and UT Austin runs.

As a result of this effort, the base and future cases refined/ developed by AACOG and UT are nearly identical. An analysis of predictions made by the two models reveals that there is an insignificant difference in the models' predictions at the two Austin monitors. The average differences, during the six day episode, between peak predictions at the Murchison and Audubon monitors when comparing the AACOG and UT base cases were 0.00 ppb and 0.05 ppb, respectively. For the 2007 future cases, the average differences in peak concentrations were   0.06 ppb ( Murchison) and   0.04 ppb ( Audubon). Daily differences in peak predictions by the two models are provided in the Summary of appendix E. SIP Revision Attainment Demonstration for the San Antonio EAC Region 33 Upon completion of the QA/ QC process, the emissions were formatted for the CAMx photochemical model using EPA's Emissions Preprocessor System 2.0 ( EPS2). The EPS2 computer program performs the data manipulations required to incorporate spatial, temporal, and chemical resolution into the emissions inventory used by photochemical models. At the end of the spatial and temporal allocation process, data totals were checked to ensure no emissions were lost during the allocation process.

3.6 1999 PHOTOCHEMICAL MODEL BASE CASE AND PERFORMANCE EVALUATION In addition to extensive refinement of the meteorological and emissions inputs, other model configurations were reviewed for suitability during an on going test and evaluation process. This step entailed performing sensitivity analyses on various model parameters including dry deposition algorithms, chemistry data, and boundary/ initial conditions. As a result of these studies, changes were made to some model settings including dry deposition algorithms ( to account for mild drought conditions occurring in eastern Texas during September 1999) and boundary condition data. Sources of refined boundary/ initial condition data included U. S. EPA's guidance on UAM modeling, measurements of rural oxidants collected during the Southern Oxidants Study ( SOS), and data collected during the Gulf of Mexico Air Quality Study sponsored by the Minerals Management Service. Appendix E provides a more extensive description of 1999 photochemical model development including the modifications made to the dry deposition algorithms, chemistry data, and boundary/ initial conditions.

3.6.1 Evaluation Methodology In accordance with EPA's draft 8 hour guidance ( May 1999), the September 1999 photochemical simulation was subjected to a variety of 1 hour and 8 hour performance analyses. Many of the tests conducted, including scatter plots, Q Q plots, and ozone metrics, were used to measure the differences between predictions and their paired observations. Due to some uncertainty as to the most appropriate method of implementing the EPA's 8 hour statistics, and in recognition that model performance for 8 hour averaged ozone attainment demonstrations is currently being applied for the first time, statistical metrics were calculated using three different methodologies. These included: 1) The predicted daily maximum ozone concentration within grid cells near a monitor; 2) The predicted daily maximum ozone concentration within grid cells near a monitor that is closest in magnitude to the observed daily maximum at the monitor; and 3) A bilinear interpolation of predicted daily maximum ozone concentration around the monitor location.

EPA's draft guidance provides default recommendations for delineating the area " near a monitor." The defaults are based on the size of the grid cells used in the photochemical model. Since the 1999 episode was modeled using a 4 km grid, " near a monitor" was determined to be the 7 x 7 array of cells surrounding each monitor. The 7 x 7 arrays surrounding the Central Texas monitors are represented by dashed red lines in figure 3 3. The Central Texas monitors include four CAMS sites located in the 10 county Capital Area Planning Council ( CAPCO) region and four monitors located in the 12 county AACOG region. SIP Revision Attainment Demonstration for the San Antonio EAC Region 34 The 1999 base case was also evaluated using a second type of performance analysis: sensitivity tests. These tests were used to determine how accurately the model responds to changes in emissions. Diagnostic, or sensitivity, tests were conducted throughout the model development process. The type of sensitivity test applied to the model depended on the stage of model development. During the performance evaluation stage, sensitivity analysis efforts focused on testing the impacts of precursor species on ozone concentrations. These tests and test results are provided in Section 3.5.2. SIP Revision Attainment Demonstration for the San Antonio EAC Region 35 Figure 3 3. Locations of Central Texas Air Quality Monitors in the Model's 4 km Grid System. Dashed red lines represent the 7 x 7 array of cells surrounding each monitor.

3.6.2 Ozone Metrics EPA recommends calculating ozone metrics to produce numerical comparisons between observed ( measured) ozone concentrations and the model's predicted concentrations. The recommended metrics include calculations of bias, error, and correlation coefficients.

In addition to conducting the metrics calculations for individual monitors, the EPA recommends " pooling" data by monitor location, i. e., developing average statistics for downwind, city center, and upwind groups of monitors. Both the San Antonio and Austin areas have relatively sparse monitoring networks. Although, bias, error, and other metrics were calculated for monitoring groups when possible, the two EAC regions, based on recommendations from the TCEQ and U. S. EPA Region 6, evaluated performance based on the averaged statistics for all stations in Central Texas. The ozone metrics calculated for the pooled eight Central Texas monitors are provided in this section. Metrics for individual monitors and monitor groups are provided in appendix E.

In their draft guidance ( EPA, May 1999), the EPA recommends specific goals for each of the ozone metrics tests. These goals include the following: SIP Revision Attainment Demonstration for the San Antonio EAC Region 36 Test Goal Bias between predicted/ observed mean 8 hour ( and 1 hour) daily maxima near each monitor 20% most monitors ( 8 hr comparisons only)

Fractional bias between predicted/ Observed mean 8 hour ( and 1 hour) daily maxima near each monitor 20% most monitors ( 8 hr comparisons only)

Correlation coefficients, all data, temporally paired means, spatially paired means Moderate to large positive correlation Bias ( 8 hour daily maxima and 1 hour observed/ predicted), all monitors 5   15%

Gross error ( 8 hour daily maxima and 1 hour observed/ predicted), all monitors 30   35%

Statistical metrics averaged for the eight Central Texas monitors, using each of the three methodologies described in Section 3.5.1, are presented in tables 3 4 through 3 6. Likewise, scatter plots with correlation coefficients and Q Q results, using each of the three methodologies, are provided in figures 3 4 through 3 6. These statistical and graphical metrics were performed on the final photochemical model run, CAMx Run 18, which incorporated the refined meteorological model ( Met Run 5g), refined emissions inventories, modified dry deposition algorithms to account for vegetation moisture stress, and the modified boundary/ initial conditions described in appendix E.

Although EPA does not require calculating performance statistics for the model initialization period, these metrics are included in tables 3 4 through 3 6 for comparison purposes. Metrics for the initialization days are highlighted in yellow.

As demonstrated, all bias and error metrics averaged for the eight Central Texas monitors fall within the goals established for the EPA. Furthermore, the goals are not only met on primary episode days ( September 15   20, 1999), but also on the initialization days. SIP Revision Attainment Demonstration for the San Antonio EAC Region 37 Table 3 4. Statistical Metrics (%), Based on the Predicted Daily Maximum Ozone Concentration within a 7x7 Array of Grid Cells Near Each Monitor, used to Assess 8 hour Performance of the September 13 20, 1999 Photochemical Model in Central Texas.

Date Maximum Observed 8 Hour Ozone Concentration ( ppb) Maximum Predicted 8 Hour Ozone Concentration ( ppb) Average Normalized Bias ( ± 15%) Average Fractional Bias ( ± 15%) Average Normalized Error ( 35%) Average Fractional Error ( 35%)

9/ 13/ 99 55.74 52.87  4.54  5.01 8.63 8.94 9/ 14/ 99 60.03 59.56  0.13  0.70 7.51 7.39 9/ 15/ 99 75.41 74.09  1.28  1.67 6.80 6.92 9/ 16/ 99 76.19 75.04  0.80  1.13 7.46 7.50 9/ 17/ 99 82.12 80.75  0.79  1.16 7.66 7.74 9/ 18/ 99 85.53 83.59  2.13  2.40 5.96 6.15 9/ 19/ 99 88.76 89.58 1.16 0.82 7.07 7.01 9/ 20/ 99 82.24 86.20 4.68 4.43 6.40 6.21 Table 3 5. Statistical Metrics (%), Based on the Predicted Daily Maximum Ozone Concentration within a 7x7 Array of Grid Cells Near Each Monitor that is Closest in Magnitude to the Observed Daily Maximum, used to Assess 8 hour Performance of the September 13 20, 1999 Photochemical Model in Central Texas.

Date Maximum Observed 8 hour Ozone Concentration ( ppb) Maximum Predicted 8 hour Ozone Concentration ( ppb) Average Normalized Bias ( ± 15%) Average Fractional Bias ( ± 15%) Average Normalized Error ( 35%) Average Fractional Error ( 35%)

9/ 13/ 99 55.74 51.92  6.45  6.84 6.74 7.13 9/ 14/ 99 60.03 57.59  3.84  4.07 3.84 4.07 9/ 15/ 99 75.41 72.15  4.09  4.34 4.11 4.36 9/ 1699 76.19 72.77  4.13  4.32 4.13 4.32 9/ 17/ 99 82.12 78.25  4.24  4.47 4.32 4.55 9/ 18/ 99 85.53 81.83  4.20  4.43 4.26 4.49 9/ 19/ 99 88.76 86.02  2.88  3.02 3.15 3.30 9/ 20/ 99 82.24 81.61  0.85  0.88 1.01 1.04 Table 3 6. Statistical Metrics (%), Based on a Bilinear Interpolation of Predicted Daily Maximum Ozone Concentration, used to Assess 8 hour Performance of the September 13 20, 1999 Photochemical Model in Central Texas.

Date Maximum Observed 8 hour Ozone Concentration ( ppb) Maximum Predicted 8 hour Ozone Concentration ( ppb) Average Normalized Bias ( ± 15%) Average Fractional Bias ( ± 15%) Average Normalized Error ( 35%) Average Fractional Error ( 35%)

9/ 13/ 99 55.74 50.49  8.82  9.61 9.87 10.65 9/ 14/ 99 60.03 55.17  7.55  8.17 9.23 9.81 9/ 15/ 99 75.41 68.04  9.37  10.07 9.73 10.43 9/ 16/ 99 76.19 70.04  7.43  8.07 9.37 9.96 9/ 17/ 99 82.12 73.97  9.22  9.92 10.22 10.90 9/ 18/ 99 85.53 76.44  10.52  11.34 10.52 11.34 9/ 19/ 99 88.76 82.97  6.30  6.82 8.41 8.85 9/ 20/ 99 82.24 78.36  4.69  5.20 6.68 7.16 SIP Revision Attainment Demonstration for the San Antonio EAC Region 38 Observed and predicted 8 hour maxima were compared graphically using scatter plots and Q Q plots. 5 Figures 3 4 through 3 6 provide combined scatter/ Q Q data pairs determined for the pooled Central Texas monitors using the three methodologies described previously. Only the third methodology ( figure 3 6) yields observed/ predicted data pairs ( indicated by blue "+" signs) outside the ± 20 indicator lines. Q Q points, designated by magenta circles, follow the 1: 1 reference line closely in each graph, particularly for methods 1 and 2. Furthermore, each methodology yields moderate to high correlation coefficients. Therefore the graphics tests indicate a high degree of correlation between peak 8 hour ozone concentrations measured during the September 1999 episode and the predicted 8 hour maximums predicted by the model for the same period.

Figure 3 4. Observed and Predicted ( within 7x7 array of grid cells near each monitor) Daily Maximum 8 hour Ozone Concentrations at Central Texas Monitors.

5 Q Q plots are used to determine whether two data sets, observed and predicted values in this case, come from populations with a common distribution. A quantile is the percentage of points below a given value; thus the 60% quantile is the point at which 60% of the data are below and 40% are above that value. The closer the Q Q points follow the 1: 1 reference line, the greater the evidence that the two data sets come from populations with similar distributions. Daily maximum 8 Hour ozone near monitor. All sites and all days. Subregion = Central Texas Monitors 0 20 40 60 80 100 120 0 20 40 60 80 100 120 Observed Ozone ( ppb) Predicted Ozone ( ppb) r2= 0.7741 O   O shows quantiles SIP Revision Attainment Demonstration for the San Antonio EAC Region 39 Figure 3 5. Observed and Predicted ( within 7x7 array of grid cells near each monitor that is closest in magnitude to the observed daily maximum) Daily Maximum 8 hour Ozone Concentrations at Central Texas Monitors.

Figure 3 6. Observed and Predicted ( based on a bilinear interpolation of daily maximum ozone concentrations around each monitor) Daily Maximum 8 hour Ozone Concentrations at Central Texas Monitors.

Daily maximum 8 Hour ozone at monitor. All sites and all days. Subregion = Central Texas Monitors 0 20 40 60 80 100 120 0 20 40 60 80 100 120 Observed Ozone ( ppb) Predicted Ozone ( ppb) r2= 0.773 O   O shows quantiles Nearest daily maximum 8 Hour ozone. All sites and all days. Subregion = Central Texas Monitors 0 20 40 60 80 100 120 0 20 40 60 80 100 120 Observed Ozone ( ppb) Predicted Ozone ( ppb) r2= 0.9042 O   O shows quantiles SIP Revision Attainment Demonstration for the San Antonio EAC Region 40 Regardless of the methodology used to determine the predicted maximum concentration within Central Texas, the results of applying metrics tests to Run 18 for each day of the September 13   20, 1999 episode fell well within EPA's guidelines. In addition, 1 hour metrics and 8 hour metrics conducted on individual monitors and groups of monitors yielded excellent results. These tests and test results are described in appendix E.

3.6.3 Predictions of Precursor Concentrations Models may also be assessed by how well the simulation replicates observed VOC, CO, NOy and NO2, whenever data permits. There are no criteria for evaluating precursor concentrations, but comparing the modeled results to monitored data where precursor data exists can assist in resolving performance issues. When the two data sets track closely, the comparison provides additional assurance that the model is performing well and " getting the right answer for the right reasons."

Currently, the sole ozone precursor monitored by San Antonio area CAMS stations is NOx. Figures 3 7 through 3 9 provide a comparison of observed and predicted NOx concentrations at three monitoring sites: CAMS 27 located in downtown San Antonio, CAMS 59 located at Calaveras Lake in southeastern Bexar County, and CAMS 62 located northeast of San Antonio in Caldwell County.

The predicted/ observed NOx comparisons were particularly important for evaluating earlier versions of the model, as the earlier base case runs tended to predict moderate to severe NOx reduction disbenefits on some episode days. Refinements to subsequent runs attenuated much of the NOx disbenefit problem. These graphs depicting CAMx Run 18 results indicate a high degree of correlation between paired predicted and observed data. A notable exception occurs on September 20th when predicted NOx concentrations are significantly higher than observed data at all three monitors.

Figure 3 7. Comparison of Observed and Predicted ( Run 18) NOx Concentrations at CAMS 27 ( San Antonio downtown) during the September 13 20, 1999 Episode. NOx values represent maximum concentrations within the 3x3 grid surrounding the monitor.

0 50 100 150 200 250 300 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM Predicted Observed SIP Revision Attainment Demonstration for the San Antonio EAC Region 41 Figure 3 8. Comparison of Observed and Predicted ( Run 18) NOx Concentrations at CAMS 59 ( Calaveras Lake) during the September 13 20, 1999 Episode. NOx values represent maximum concentrations within the 3x3 grid surrounding the monitor.

Figure 3 9. Comparison of Observed and Predicted ( Run 18) NOx Concentrations at CAMS 62 ( San Marcos) during the September 13 20, 1999 Episode. NOx values represent maximum concentrations within the 3x3 grid surrounding the monitor.

3.6.4 Precursor Sensitivity Studies During the base case performance evaluation process, two types of analyses were conducted on the model: ( 1) the metrics tests described above that measure how accurately the model predicts observed concentrations, and ( 2) sensitivity analyses that are useful for diagnostic or predictive purposes depending on how and when the tests are applied. Sensitivity tests were conducted throughout the model development process to identify sources of uncertainty and opportunities for model improvement. The sensitivity tests applied during the base case evaluation phase of model development involved reducing VOC, NOx, and combinations of VOC and NOx to determine the model's sensitivity to precursor emissions. Precursor sensitivity studies are useful for identifying the types of emissions and sources of emissions on which to focus strategy analyses. CAMS 59 NOx  run18 ( 3 x 3 Grid)

0 25 50 75 100 125 150 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 0 0 PM 12: 00 AM 4: 00 AM 8: 00 AM 1 2: 00 PM 4: 00 PM 8: 00 PM 12: 0 0 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 0 0 AM 8: 00 AM 12: 00 PM 4: 00 PM 8 : 00 PM 12: 00 AM 4: 00 A M 8: 0 0 AM 12: 00 PM 4: 00 PM 8: 00 PM 12 : 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM Predicted Observed 0 25 50 75 100 125 150 12: 00 AM 4 : 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 0 0 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 0 0 AM 4: 00 AM 8: 00 AM 12: 0 0 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM 12: 00 AM 4: 00 AM 8: 00 AM 12: 00 PM 4: 00 PM 8: 00 PM Predicted Observed SIP Revision Attainment Demonstration for the San Antonio EAC Region 42 Across the board sensitivity runs were conducted by removing 25%, 50%, 75%, and 100% of the local ( 4 county SAER) NOx emissions, VOC emissions, and combinations of the two, from the CAMx Run 17b model. Figures 3 10 and 3 11 provide the results of the across the board reduction runs for CAMS 23 and CAMS 58, averaged over the six day modeling period. In general, VOC reductions were more effective than NOx reductions over the range of controls required to demonstrate attainment.

Due to time constraints, VOC/ NOx reduction analyses were not conducted on CAMx Run 18. However, several precursor sensitivity runs were conducted on a prior version of the September 1999 model, CAMx Run 17b. The primary difference between CAMx Run 17b and CAMx Run 18, for the 1999 base cases, 6 was the use of a refined MOBILE6 on road EI in the latter model, as described in section 3.4. Rerunning all the sensitivity tests again on Run 18 would have added an enormous amount of work. Based upon experience, it was assumed that the general findings and directional guidance determined from previous runs would remain stable with relatively small emissions adjustments.

Figure 3 10. Predicted Ozone Concentrations at CAMS 23 after Removing Local ( 4 county SAER) NOx and VOC Emissions, average from September 15   20, 1999.

6 The 2007 projection developed from CAMx Run 18 incorporates a refined regional EI ( described in Section 3.6); however, the regional EIs for Runs 17b and 18 1999 base cases are identical. 60 65 70 75 80 85 90 0% 25% 50% 75% 100%

Anthropogenic Emission Reductions ( percentage) Ozone Concentration ( ppb)

NOx Reduction VOC Reduction NOx & VOC Reduction 8 hour standard  85 ppb SIP Revision Attainment Demonstration for the San Antonio EAC Region 43 Figure 3 11. Predicted Ozone Concentrations at CAMS 58 after Removing Local ( 4 county SAER) NOx and VOC Emissions, average from September 15   20, 1999.

3.7 2007 FUTURE CASE MODELING EMISSIONS INVENTORY Based on the positive outcome of performance evaluations conducted on the September 1999 episode simulation ( Run 18), the model was subjected to a subsequent step in the attainment demonstration process: development of an attainment year base case. In order to create a future base case for the SAER, emissions inventory inputs were developed for the attainment year of 2007. This step required adjusting the modeling EI calculated for the 1999 base case to the projection year using both control and growth factors. Growth factors accounted for anticipated increases or decreases in emissiongenerating activities as the result of growth / decline in employment, population, and transportation. Control factors were applied to emission projections to account for state and federal control regulations that are already mandated and expected to be in place by the attainment year. Such control factors are expected to impact local emissions through changes in technology, fuel formulations, fuel use, energy efficiency, and other emission reduction programs.

One exception to " growing" emissions to a projection year was the estimation of future biogenic emissions. In accordance with EPA recommendations, the biogenic inventory for 2007 was identical to that used in the 1999 base case. Biogenic sources were estimated to release 263 tons per day ( tpd) of VOC and 21 tpd of NOx in the SAER during the September 1999 episode. Therefore, the 2007 biogenic emission input file contains these same values. Likewise, the biogenic EI for the remainder for the modeling domain remains consistent between base and future cases.

Emission projection procedures are specific to the source category   on road mobile, area/ non road, and point   and are discussed in more detail in appendix F. As part of the on road emission estimation project referenced in section 3.4, TTI also developed 2007 attainment year mobile emissions for the NNA regions. The methodology TTI used to project on road emissions for the San Antonio area is described in their report, San Antonio Metropolitan Statistical Area On Road Mobile Source Modeling Emissions 60 65 70 75 80 85 90 0% 25% 50% 75% 100%

Anthropogenic Emission Reductions ( percentage) Ozone Concentration ( ppb)

NOx Reduction VOC Reduction NOx & VOC Reduction 8 hour standard  85 ppb SIP Revision Attainment Demonstration for the San Antonio EAC Region 44 Inventories: 1999, 2007, and 2012 ( TTI, 2003), included as appendix C. The results of projecting the VOC and NOx EI to 2007 for all anthropogenic sources in the four county SAER are summarized in tables 3 7 and 3 8, respectively.

Table 3 7. Estimated 2007 Average Weekday ( Wednesday) VOC Emissions from Anthropogenic Sources in the Four county SAER.

County On Road ( tpd) Area / Non road ( tpd) Point ( tpd) Total ( tpd) Bexar 42.42 98.55 11.82 152.79 Comal 3.85 5.53 0.52 9.90 Guadalupe 3.42 6.98 1.10 11.50 Wilson 0.98 3.68 0.07 4.74 Total ( tpd) 50.67 114.75 13.50 178.93 Table 3 8. Estimated 2007 Average Weekday ( Wednesday) NOx Emissions from Anthropogenic Sources in the Four county SAER.

County On Road ( tpd) Area / Non road ( tpd) Point ( tpd) Total ( tpd) Bexar 67.45 39.18 53.24 159.86 Comal 7.07 3.70 13.77 24.53 Guadalupe 6.47 3.40 8.07 17.95 Wilson 1.34 1.04 0.00 2.39 Total ( tpd) 82.34 47.32 75.08 204.74 For most anthropogenic source categories, the emission estimates decreased between 1999 and 2007, as shown in tables 3 9 and 3 10. Exceptions include an estimated increase in VOC emissions from point sources in Bexar, Comal, and Guadalupe counties. The increases in Bexar and Guadalupe counties are primarily attributed to a new Toyota manufacturing plant scheduled for completion by 2006 in Bexar County and two gas fired power plants ( online between 1999 and 2007) in Guadalupe County. The increase in NOx emissions in Guadalupe County for 2007 is based on projected effluent from the new power plants as well. In addition, area/ non road NOx emissions are estimated to increase in Comal and Wilson Counties by 2007. Overall, VOC emissions are expected to decrease by 20.88% between 1999 and 2007 in the four county SAER and NOx emissions are expected to decrease by 30.11% during the same timeframe.

Table 3 9. Percent Difference between Estimated Weekday VOC Emissions for 1999 and 2007 in the Four county SAER.

County On Road ( tpd) Area / Non road ( tpd) Point ( tpd) Total ( tpd) Bexar  43.83%  11.99% 87.47%  21.16% Comal  37.42%  17.45% 50.94%  24.98% Guadalupe  38.63%  10.08% 145.00%  16.58% Wilson  37.42%  1.31% 0.00%  11.82% Total ( tpd)  42.95%  11.85% 88.44%  20.88% SIP Revision Attainment Demonstration for the San Antonio EAC Region 45 Table 3 10. Percent Difference between Estimated Weekday NOx Emissions for 1999 and 2007 in the Four county SAER.

County On Road ( tpd) Area / Non road ( tpd) Point ( tpd) Total ( tpd) Bexar  43.59%  0.53%  39.90%  35.42% Comal  39.30% 3.46% 13.22%  10.39% Guadalupe  38.15%  19.65% 1492.19% 17.99% Wilson  29.00% 12.17% 0.00%  15.44% Total ( tpd)  42.65%  1.67%  25.85%  30.11%

3.8 2007 PHOTOCHEMICAL MODEL BASE CASE AND SENSITIVITY ANALYSES The effects of modifying emissions inputs to the model in order to develop a 2007 future base are provided in table 3 11. This table lists the average daily ( September 15   20) maximum 8 hour ozone concentrations within the 7x7 array of cells surrounding the SAER monitors, as predicted by the 2007 future case, and compares those values to those predicted for 1999. For each monitoring site, ozone concentrations are predicted to decrease between 1999 and 2007. The difference in the 1999 and 2007 predictions ranges from  3.3% at CAMS 678 to  5.7% at CAMS 59. Both CAMS 59 and CAMS 678 are upwind monitors located southeast of downtown San Antonio.

Table 3 11. Comparison of 1999 and 2007 Predicted Ozone Concentrations by Monitor.

CAMS Station 1999 Predicted 8 hr Max. Ozone 2007 Predicted 8 hr Max. Ozone 1999 2007 Percent Change CAMS 23 89.0 ppb 84.5 ppb  5.0% CAMS 58 87.8 ppb 82.8 ppb  5.6% CAMS 59 78.1 ppb 73.6 ppb  5.7% CAMS 678 80.1 ppb 77.4 ppb  3.3%

The 1999 2007 predicted ozone concentration results are compared graphically in figure 3 12. This comparison represents the maximum 8 hour concentrations within the entire 4 km subdomain for a typical episode weekday   Wednesday, September 15th. As shown, predicted ozone levels fell significantly between 1999 and 2007 throughout the 4 km subdomain and the area with exceedances was completely eliminated. Moreover, the peak predicted 8 hour maximum concentration for the domain decreased from 90 ppb to 81 ppb in the September 15th simulation. Comparisons of 1999 and 2007 peak ozone concentration predictions for each episode day are provided in appendix G, 2007 Base Case and Sensitivity Analyses. SIP Revision Attainment Demonstration for the San Antonio EAC Region 46 Figure 3 12. Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for a Typical Weekday ( Wednesday, September 15th).

1999 2007 SIP Revision Attainment Demonstration for the San Antonio EAC Region 47 Once the photochemical model was modified using the projected 2007 EI, several additional sensitivity runs were conducted on the simulation to assess the robustness of the 2007 base case simulation. The 2007 base case included an updated 2007 regional EI that was originally used by ENVIRON to model an ozone episode for northeast Texas. Much of the regional emission rate file was based on an EPA study which analyzed the impacts of implementing federal rules pertaining to heavy duty diesel engines and fuels in the on road and off road source categories. The study was documented in the federal agency's report Procedures for Developing Base Year and Future Year Mass and Modeling Inventories for the Heavy Duty Engine and Vehicle Standards and Highway Diesel Fuel ( HDD) Rulemaking. 7 After the sensitivity tests were completed on the CAMx Run 18 base case ( or 1999 base case A), AACOG received additional EI data and performed other modifications to incorporate into the 1999 base and 2007 future cases. Modifications incorporated into the 1999 base case included:

refined 1999 VOC emission rates from a San Antonio based water utility for wastewater treatment plants

EI data file from ENVIRON International Corporation ( via TCEQ) for states outside of Texas

updated area and non road source temporal profiles for regional Texas that matches 2007 temporal profiles

updated point source cut off point from 20m to 50m for the 4km grid

updated Victoria's mobile EI

updated chemical and temporal profiles for Texas area and non road emissions

updated Victoria's point sources

updated Texas NEGU and EGU point sources outside of Houston

updated Louisiana point source emissions

updated San Antonio asphalt emissions

updated tanker truck unloading emissions

updated tanker trucks in transit emissions

updated emissions for other gasoline distribution activities Additional modifications incorporated into the 2007 base case included:

updated regional EI non road HDD provided by TCEQ

updated Austin Point Source Control database ( several revisions)

new wastewater estimates

new regional temporal profile for point sources

updated Austin CO on road EI ( 3 County)

stage1 ( 125k) file

removed tank truck unloading on Sunday

updated area source temporal profiles

updated Texas regional area and non road emissions

updated Texas point sources ( besides CPS),

new Lehigh cement kiln controls

updated point source cut off point from 20m to 50m for the 4km grid

updated Victoria's emissions

updated chemical and temporal profiles for Texas area and non road emissions

updated San Antonio asphalt emissions 7 The report , dated October 2000, was prepared for EPA by E. H. Pechan & Associates, Inc. and is available on line at: http:// www. epa. gov/ otaq/ models/ hd2007/ r00020. pdf SIP Revision Attainment Demonstration for the San Antonio EAC Region 48

updated tanker truck unloading emissions

updated tanker trucks in transit emissions

updated emissions for other gasoline distribution activities

updated emissions for rate of progress controls As a consequence of receiving and incorporating revised local and regional EI data files for the base case and future case, additional sensitivity runs were conducted on the refined base runs. The final run, 1999 Base Case G ( CAMX Run 18. f) incorporates all refinements listed above. Tables 3 12 through 3 15 list the results ( by ppb) of sensitivity runs conducted for 2007 based on predictions of ozone concentrations within the 7 x 7 grids surrounding each of four CAMS stations in the San Antonio area. The tables also provide comparisons between 1999 and 2007 predicted average ozone concentrations and between 1999 and 2007 design values for both A and G versions of the CAMx Run 18 simulations.

As demonstrated in these tables, the future case " zero out" runs ( removal of power plants and other sources), show that SAER sources will contribute from ~ 12   21% of the ambient ozone, depending on the CAMS station being evaluated. These sensitivity runs also indicate that emissions added by the Toyota plant and the various power plants make small changes in total ozone concentrations in the SAER. Furthermore, the predicted 2007 design values ( see section 3.9 for methodology used to calculate design values) at each CAMS location in the San Antonio region are reduced below the 85 ppb threshold for both A and G versions of the future cases. This holds true even for CAMS 23, which has the highest current design value: 89 ppb.

Table 3 12. Results of Sensitivity Runs Conducted at CAMS 23 ( San Antonio Northwest   Marshall High School).

Sensitivity Run Year Design Value ( ppb) Change ( ppb) Base Case A 1999 89  Base Case G 1999 89

No City Public Service Plants 2007 83.32  1.21 No Spruce Power Plant ( 5.93 tons/ day NOx) 2007 84.42  0.10 No Toyota Manufacturing Plant 2007 84.51  0.01 No San Antonio ( 4 county area ) 2007 2007 63.09  21.43 Base Case A 2007 84.56  Base Case G 2007 84.52  SIP Revision Attainment Demonstration for the San Antonio EAC Region 49 Table 3 13. Results of Sensitivity Runs Conducted at CAMS 58 ( Camp Bullis)

Sensitivity Run Year Design Value ( ppb) Change ( ppb) Base Case A 1999 87  Base Case G 1999 87

No City Public Service Plants 2007 81.15  0.97 No Spruce Power Plant 2007 82.04  0.08 No Toyota Manufacturing Plant 2007 82.11  0.01 No San Antonio ( 4 county area ) 2007 2007 63.42  18.69 Base Case A 2007 82.19  Base Case G 2007 82.12

Table 3 14. Results of Sensitivity Runs Conducted at CAMS 59 ( Calaveras Lake)

Sensitivity Run Year Design Value ( ppb) Change ( ppb) Base Case A 1999 79  Base Case G 1999 79

No City Public Service Plants 2007 71.07  3.42 No Spruce Power Plant 2007 74.46 0.03 No Toyota Manufacturing Plant 2007 74.46  0.02 No San Antonio ( 4 county area ) 2007 2007 64.51  9.97 Base Case A 2007 74.96*  Base Case G 2007 74.48  * averaged over one more day ( Sept 17th) because the value was above 70 ppb requirement ( EPA 1999 , p. 41) to be included in the RRF SIP Revision Attainment Demonstration for the San Antonio EAC Region 50 Table 3 15. Results of Sensitivity Runs Conducted at CAMS 678 ( CPS Pecan Valley)

Sensitivity Run Year Design Value ( ppb) Change ( ppb)

Base Case A 1999 77  Base Case G ( includes refined wastewater VOCs) 1999 77

No City Public Service Plants 2007 72.17  2.29 No Spruce Power Plant 2007 74.35  0.11 No Toyota Manufacturing Plant 2007 74.48  0.02 No San Antonio ( 4 county area) 2007 2007 61.29  13.17 Base Case A* 2007 74.71  Base Case G 2007 74.46

* averaged over one more day ( Sept 17th) because the value was above the 70 ppb requirement ( EPA 1999 , p. 41) to be included in the RRF 3.9 ATTAINMENT DEMONSTRATION PROCESS An attainment demonstration compares predicted ozone concentrations with the thresholds established by the ozone NAAQS. The NAAQS are met if the fourth highest 8 hour daily maximum ozone concentration averaged over three consecutive years is less than or equal to 0.08 ppm. Therefore, the modeled attainment test is passed when the predicted future design values near all monitoring sites are less than or equal to 84 ppb. The EPA has specified a procedure for calculating the future design values. In order to determine the level of reductions needed to reach attainment by 2007, staff calculated the future design values for the San Antonio region in accordance with EPA guidance.

3.9.1 Design Values and Relative Reduction Factors As recommended by the EPA, attainment demonstrations for the 8 hour ozone NAAQS should be based on the results of modeled attainment tests, screening tests, and, when appropriate, weight of evidence determinations. Key components of these tests are the predicted and observed design values.

The " current" design value for the SAER was determined using EPA guidelines. This step entailed reviewing the three year period straddling the year represented by the most recently available emissions inventory ( 1998   2000) and the three year period that is anticipated to be used to designate the area nonattainment ( 2001   2003). The current monitored design values were selected based on the higher of the two estimates at each monitor, as shown in table3 16. Based on this procedure, the area wide " current" design value for the San Antonio area is 89 ppb at CAMS 23. SIP Revision Attainment Demonstration for the San Antonio EAC Region 51 Table 3 16. Selection of Current Monitored Design Values based on Comparison of 1998   2000 Values with 2001   2003 Values.

Monitor 1998 2000 Design Value 2001 2003 Design Value Current Monitored Design Value Used in the Modeled Attainment Test CAMS 23 85 ppb 89 ppb 89 ppb CAMS 58 84 ppb 87 ppb 87 ppb CAMS 59 79 ppb 78 ppb 79 ppb CAMS 678 77 ppb 76 ppb 77 ppb 3.9.2 Modeled Attainment Test The modeled attainment test predicts whether or not all observed future design values will be less than or equal to the 8 hour ozone NAAQS under the same meteorological conditions as those simulated for the base case ( EPA, May 1999). The future design value is calculated by multiplying the " current" design value by a " Relative Reduction Factor," which is the relative change in modeled values between the base and future case. The test was performed by solving the following equation for each monitoring site within the San Antonio region.

( DVF) I = ( RRF) I( DVC) I where ( DVC) I = the current design value at monitoring site I ( RRF) I = the relative reduction calculated near site I ( ratio of the future 8 hour daily maximum concentration predicted near a monitor ( within the 7 x 7 grid) to the current 8 hour daily maximum concentration predicted near a monitor ( DVF) I = the estimated future design value for the time attainment is required The modeled attainment test is passed if all resulting predicted future design values are   84 ppb. Table 3 17 provides the results of the modeled attainment test at each SAER monitor. As indicated, the test was passed at all the monitors used to determine attainment.

Table 3 17. Modeled Attainment Test Results at SAER Monitors.

Monitor Modeled Average Daily Maximum Ozone Concentration   1999 Modeled Average Daily Maximum Ozone Concentration  2007 RRF Current Design Value Future Design Value Pass / Fail Status CAMS 23 88 ppb 84 ppb 0.95 89 ppb 84 ppb Pass CAMS 58 87 ppb 82 ppb 0.94 87 ppb 82 ppb Pass CAMS 59 78 ppb 73 ppb 0.95 79 ppb 74 ppb Pass CAMS 678 80 ppb 77 ppb 0.97 77 ppb 74 ppb Pass While the future design values listed in table 3 17 indicate the region would be in compliance with the 8 hour ozone NAAQS by the attainment year without implementing local clean air controls, the results for CAMS 23 are very close to the 85 ppb threshold. Chapter 5 describes additional local controls that were evaluated as a means of further SIP Revision Attainment Demonstration for the San Antonio EAC Region 52 reducing ozone concentrations in the SAER by the attainment year. One strategy, Stage I vapor recovery, is creditable, enforceable, and permanent in terms required for credit taken in the SIP.

Table 3 18 provides the future design values, by monitor, calculated from a 2007 control strategy run that incorporated the impacts of Stage I vapor recovery technology in the SAER. The table provides a comparison between these values and the future design values calculated from the 2007 future case ( without local controls). Although EPA guidance ( May 1999) suggests truncating design value calculations, decimal places are provided in table 3 18 to allow for comparisons. These results indicate that implementation of Stage I vapor recovery systems in the SAER is expected to reduce ozone concentrations at all SAER monitors. More information on clean air strategies and calculation of design values is provided in chapter 5 of this attainment document and appendix H.

Table 3 18. Modeled Attainment Test Results that Account for Implementation of Stage I Vapor Recovery.

Monitor Future Design Value ( ppb) RRF Future Design Value with Stage I ( ppb) Pass/ Fail Status CAMS 23 84.52 0.950 84.40 Pass CAMS 58 82.12 0.944 82.03 Pass CAMS 59 74.48 0.943 74.44 Pass CAMS 678 74.46 0.967 74.39 Pass 3.9.3 Screening Test Since the modeled attainment test provides no indication of future ozone concentrations at locations without monitors, the EPA recommends a supplementary screening analysis to support an attainment demonstration. The screening test is particularly important in areas such as Central Texas where monitoring networks are relatively sparse. The screening test requires identifying areas in the domain where absolute predicted 8 hour daily maximum ozone concentrations are consistently greater than any predicted in the vicinity of a monitoring site. The final step in the screening test requires estimating the future design value for each identified area.

The default criterion recommended by EPA for defining areas with consistently high predictions of 8 hour daily maximum ozone concentrations requires identifying 8 hour concentration predictions that are > 5% higher than any near a monitored location on 50% or more of the modeled days. Table 3 19 provides a list of the daily maximum 8 hour concentrations predicted within the San Antonio region for the September episode model and compares the data to daily maximum 8 hour concentrations in the vicinity of a monitoring site. As shown, the predicted 8 hour daily maximum for the SA region exceeded the highest predicted 8 hour daily maximum near a monitor by more than 5% on only two day of the episode ( 16th and 17th). Since the 5% threshold was not exceeded on " 50% or more modeled days," a screening test is unnecessary for demonstration purposes. SIP Revision Attainment Demonstration for the San Antonio EAC Region 53 Table 3 19. Screening Cell Design Value Scaling Results*

8 hr Daily Maximum Date CAMS 23 CAMS 58 CAMS 59 CAMS 679 Maximum Screened Cell Value Percent difference compared to Peak CAMS Value 15th 81.14 75.59 66.89 70.16 83.22 2.56% 16th 78.08 77.26 72.38 71.51 84.67 8.43% 17th 81.36 82.01 69.90 69.90 86.13 5.03% 18th 98.57 98.57 72.12 79.63 98.57 0.00% 19th 101.40 101.83 81.75 91.49 101.83 0.00% 20th 93.20 91.30 86.26 87.65 93.20 0.00% * Bold type indicates > 5% of modeled daily maximum value 3.10 SUMMARY AND RECOMMENDATIONS The extensive QA/ QC process performed on and subsequent refinements made to the September 1999 photochemical simulation have produced a model that replicates observed trends very well. A variety of performance tests, including 1 hour and 8 hour metrics, precursor observations, and diagnostic tests, were conducted on the simulation with encouraging results. In particular, the final iteration labeled Run 18, replicated observations quite accurately and passed all performance tests. Extensive model analyses, testing, and performance evaluation provided all four South and Central Texas urban areas with the confidence to use the simulation for modeling purposes. Furthermore, model performance lent credence for basing attainment demonstrations for two cities on the September episode simulation: the SAER attainment demonstration described here and the Austin / Round Rock MSA Clean Air Plan.

Following EPA guidance, modeled attainment tests and screening tests were conducted on the model to determine the reductions necessary to meet NAAQS thresholds by the attainment year. Although these tests indicated the San Antonio region would reach attainment by 2007 with no additional local controls, it was recognized that the attainment tests were passed with very little margin for error. Therefore, it was deemed prudent to proceed with modeling the effects of controlling local sources of emissions.

Results of the precursor sensitivity analyses described in Section 3.5.3 indicate that, at the 25% reduction level, decreases in either VOC or NOx effectively reduce ozone levels in the San Antonio region. However, VOC reductions were generally more effective at lowering ozone concentrations at the 25% reduction level than comparable reductions of NOx. Based on these precursor tests, it was recommended that a variety of local controls be modeled that target reductions of NOx, VOC, or both NOx and VOC.

References Capital Area Planning Council ( January 2004). Development of the September 13 20, 1999 Base Case Photochemical Model for Austin's Early Action Compact, Report submitted to the U. S. EPA and TCEQ by CAPCO with contractors from The University of Texas at Austin and ENVIRON International Corporation. Austin, TX.

Environmental Protection Agency ( April 1999). Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards ( NAAQS) and Regional Haze Regulations ( EPA 454/ R 99 006). Research Triangle Park, NC: Office of Air Quality Planning and Standards. SIP Revision Attainment Demonstration for the San Antonio EAC Region 54 Environmental Protection Agency ( May 1999). Draft Guidance on the Use of Models and Other Analyses in Attainment Demonstrations for the 8 Hour Ozone NAAQS ( EPA 454/ R 99 004). Research Triangle Park, NC: Office of Air Quality Planning and Standards.

Texas Transportation Institute ( June 2003). San Antonio Metropolitan Statistical Area On Road Mobile Source Modeling Emissions Inventories: 1999, 2007, and 2012. College Station, TX: TTI   The Texas A& M University System SIP Revision Attainment Demonstration for the San Antonio EAC Region 55 CHAPTER 4: DATA ANALYSIS 4.1 INTRODUCTION A great amount of data must be accumulated and reviewed in preparation for photochemical modeling. This not only includes the data used to develop meteorological, precursor emissions, and air quality inputs to the model, but data used to understand and define the conditions that contribute to elevated ozone concentrations in a region. Data analysis entails assessing and characterizing these environmental conditions to develop an understanding of their impact on ozone formation, transport, and deposition. Further, these analyses enhance the decision making process for clean air strategy selection.

Ozone data analysis focuses on the underlying causes of ozone level exceedances. Such studies include a review of ozone trends to identify patterns of peak ozone formation; meteorological conditions that are conducive to exceedances; and the impacts of transport, as well as contribution of local sources, on ozone levels. The following sections summarize the results and conclusions of these analyses. Detailed information on these topics is provided in appendices A and M.

4.2 LEVELS AND TRENDS IN OZONE CONCENTRATIONS The SAER region continues to meet the 1 hour ozone NAAQS. However, since promulgation of the 8 hour ozone standard in 1997, the region has exceeded the 8 hour standard during several averaging periods.

Figure 4 1 identifies the annual peak 1 hour and 8 hour ozone concentrations measured by any SAER monitor between 1995 and 2002. Of note is the relative rarity of 1 hour ozone exceedances in the region. From 1995 2003, the region has recorded a total of five one hour ozone readings at or above 125 ppb. One of these, May 7, 1998, was associated with a Mexican smoke event and is not a regulatory reading. This graph also indicates the highest 8 hour average measured in the region varies from year to year. Due to the limited information this graph provides ( annual peak values), and the relatively short ( 8 years) study period, no conclusions are drawn regarding ozone concentration trends.

Figure 4 1. Annual Peak 1 hour and 8 hour Ozone Measurements within SAER.

0 20 40 60 80 100 120 140 160 1995 1996 1997 1998 1999 2000 2001 2002 ppb 1 hr 8 hr SIP Revision Attainment Demonstration for the San Antonio EAC Region 56 Figure 4 2 displays the eight hour ozone design value trends, by site, between the years 1980 and 2003. Although this graph provides a much wider data range than figure 4 1, there is little indication of ozone trends in this graph, as the values tend to vary from year to year. The lowest 8 hour design values generally occurred during the early 1990s. However, beginning in 1995, the design values began to rise and the 85 ppb design was exceeded multiple times. Only the design values for CAMS 59 ( Calaveras Lake) and CAMS 678 ( CPS Pecan Valley) consistently remained below 85 ppb. During the ozone season, these monitors are historically upwind. Since CAMS 59 and 678 typically measure background concentrations, these monitors are expected to have lower design values than San Antonio's downwind monitors, CAMS 23 and 58. SIP Revision Attainment Demonstration for the San Antonio EAC Region 57 Figure 4 2. San Antonio Eight hour Ozone Design Value Trends by Site.*

* Each plotted value covers a 3 year period ending with the year indicated.

70 75 80 85 90 95 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 Year Design Value (

ppb) Northwest C23 North C07 Camp Bullis C58 Calaveras C59 CPS/ Trinity C678 8 Hour O3 Exceedance C58 Level to Exceed the 8 Hour Ozone Standard C23 C23 C23 C07 C07 C07 C59 C678 SIP Revision Attainment Demonstration for the San Antonio EAC Region 58 Figure 4 3 provides an indication of the frequency of 8 hour threshold exceedances. This graph identifies, on an annual basis, the number of days the 85 ppb threshold was exceeded between 1995 and 2002. The annual values range from one exceedance day in 2001 to 17 exceedance days the following year, 2002. As with annual peak concentrations, this comparison shows a great deal of variability between 1995 and 2002, with no obvious conclusions regarding trends.

Figure 4 3. Annual Number of Days in which Measured 8 hour Averages Met or Exceeded 85 ppb at SAER Monitors.

Figure 4 4. High Ozone Readings by Two week Period for San Antonio Region. ( Source: TCEQ). 14 2 3 8 11 3 1 17 0 2 4 6 8 10 12 14 16 18 1995 1996 1997 1998 1999 2000 2001 2002 # of Days per Year SIP Revision Attainment Demonstration for the San Antonio EAC Region 59 While few conclusions can be drawn regarding annual trends in ozone data as demonstrated above, aggregated annual data may be more useful. The previous graph ( figure 4 4) shows ozone exceedance counts by two week bin for San Antonio. The following graph ( figure 4 5) provided by TCEQ compares high ozone measurements, by two week period, for the combined years of 2000 2002. The curve for the SAER is similar to several other Texas urban areas ( also displayed) in which peak measurements are typically recorded in June, August, and September. These peaks indicate the influence of seasonal weather patterns on regional ozone concentrations, given that exceedance frequency occurs in patterns when averaged.

Figure 4 5. High Ozone Readings by Two week Period for Major Texas Urban Areas. ( Source: TCEQ).

4.3 ANALYSIS OF METEOROLOGICAL DATA The TCEQ conducts periodic studies to determine air quality/ meteorological conditions, both at the surface and aloft, throughout Texas. Several of these studies have involved the use of aircraft for collecting air samples. For example, the Baylor University Aviation Sciences Department, under contract with the TCEQ, has been collecting airborne air quality data in Texas for several years. Sonoma Technology, Inc. analyzed air quality data collected by the Baylor Airborne sampling program during the years 1997 and 1998 and concluded that, in the San Antonio region, elevated ozone levels were associated 0 5 10 15 20 25 Early Jan.

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Coverage Years: 2000 2002 Total # of Days over 0.08/ 8 Hr. Dallas/ Fort Worth Tyler/ Longview El Paso Beaumont/ Port Arthur Austin Houston/ Galveston San Antonio Corpus Christi/ Victoria McAllen/ Rio Grande Valley SIP Revision Attainment Demonstration for the San Antonio EAC Region 60 with high pressure systems, clear skies, light flow aloft, and peak mixing heights at approximately 1500 meters ( MacDonald et al., 1999).

Additional meteorological analyses have been conducted by AACOG. Staff analyzed the relationship of regional ozone concentrations to several meteorological parameters: temperature, wind speed, and solar radiation. Results of these analyses are provided in figures 4 6 through 4 8.

The average daily peak temperature on ozone exceedance days ( 8 hour average   85 ppb) during the study period of 1998 2002 was 91.2o F. As shown in figure 4 6, 95% of the exceedances occurred on days when peak daily temperatures were greater than 84o F. Although 8 hour ozone exceedances in the SAER typically occur when peak temperatures are > 84o F., the figure also makes it clear that peak temperatures do not necessarily produce ozone exceedances. The majority of high temperature days are associated with ozone levels below the 85 ppb threshold. The temperature data indicate that other factors, or combinations of factors, are of greater influence on concentrations than temperature alone.

Analysis of 1997   2002 wind speed data indicate no exceedances occurred on days when wind speeds surpassed 6 mph. In addition, only 15% of the exceedance days occurred on days when wind speeds were between 5 6 mph. Therefore, stagnation is an important factor in ozone exceedances. Figure 4 7 also indicates that on the majority of days with little or no wind, there were no exceedances of the 85 ppb threshold.

Since ozone forms as the result of photochemical reactions between precursor emissions, the amount of solar radiation reaching the lower atmosphere is another meteorological condition that influences the chemical's formation. Figure 4 8 shows that below 1 langley/ minute, there were only two days between 1999 and 2002 in which 8 hour ozone levels exceeded 85 ppb. Below 0.9 langleys/ minute there were no exceedances. As with temperature and wind speed however, certain solar radiation levels may be conducive to, but by no means guarantee, ozone exceedances.

Local ozone exceedances are typically associated with certain meteorological conditions: high pressure systems and stagnation, high ambient temperatures, and low wind speeds. As demonstrated, these conditions do not always produce excessive ozone concentrations in SAER. Other factors also influence ozone buildup. Such conditions include background ozone concentrations and transport. These issues are discussed in more detail in the following section. SIP Revision Attainment Demonstration for the San Antonio EAC Region 61 Figure 4 6. Daily 8 hour Ozone Maxima Measured at CAMS 23 v.

Peak Temperature, 1998   2002 0 20 40 60 80 100 120 2 4 6 8 10 12 14 Average Daily Wind Speed ( mph)

Daily Ozone 8

Hour Maximum (

ppb) 8 hr Ozone Standard 15% of exceedance days had average wind speeds > 5mph & 0% > 6mph 0 20 40 60 80 100 120 40 60 80 100 Daily Peak Temperatures in Degrees F Daily Ozone 8

Hour Maximums 95% of exceedance days had temps > 84 F 8 hr Ozone Standard 0 20 40 60 80 100 120 0 0.25 0.5 0.75 1 1.25 1.5 Daily Solar Radiation Maximums ( langleys/ min.)

Daily Ozone 8

Hour Maximums (

ppb) 8 hr Ozone Standard 95% of exceedance days had Solar Radiation > 1.0 & 100% had > 0.9 Figure 4 7. Daily 8 hour Ozone Maxima v. Average Wind Speeds,

1997  2002 Figure 4 8. Comparison of Daily 8 hr Maxima & Daily Solar Radiation Maxima, 1999 2002 SIP Revision Attainment Demonstration for the San Antonio EAC Region 62 4.4 TRANSPORT AND LOCAL CONTRIBUTIONS TO OZONE CONCENTRATIONS It is generally recognized that transport is a more significant issue under the 8 hour ozone standard than under the 1 hour standard. Since transport is a primary contributor to the local ozone problem, the SAER has less control over local ambient air quality.

As is shown extensively in Appendix M, photochemical modeling runs in which the entire anthropogenic emissions inventory for the four county San Antonio region is removed lowers the peak ozone levels by less than 25% in the 1999 base case. This result intimates that transport and background ozone levels heavily influence the ozone levels recorded on area ozone monitors. Clearly, local governments in the San Antonio region have no jurisdiction over the background concentrations or the external sources giving rise to transport.

Based on the modeled results of implementing clean air measures locally, it is predicted that many strategies which significantly reduce ambient ozone concentrations in onehour nonattainment areas would be considerably less effective in the SA region. ( See Chapter 5 for results of modeled clean air strategies in the SAER). As a consequence, the San Antonio regional Early Action Compact signatories must rely on state and federal partners to ensure that the clean air strategies and controls they have proposed and promulgated are installed and effective.