APPENDIX G 2007 BASE CASE AND SENSITIVITY ANALYSES SAN ANTONIO EAC REGION ATTAINMENT DEMONSTRATION MARCH 2004 G 2 Appendix G Table of Contents Page Introduction                               . G 6 2007 Base Case                             . G 14 2007 Base Case Performance Evaluation                  .. G 14 Tile Plots                             . G 14 Comparisons Between Model Refinements              .. G 21 Sensitivity Tests                          . G 23 Zero out Runs: Urban Areas                 .. G 23 Zero out Runs: Point Sources                  G 25 Incremental Removal of VOC and NOx Precursor Emissions   .. G 35 Summary of Modifications to the 1999 Base and 2007 Future Cases and Resulting Design Values                      .. G 38 References                               .. G 47 G 3 Appendix G List of Tables Page Table G 1 Comparison of 1999 and 2007 Anthropogenic VOC Emissions in the Four county SAER for a Typical Weekday ( Wednesday)  .. G 6 Table G 2 Comparison of 1999 and 2007 Anthropogenic NOx Emissions in the Four county SAER for a Typical Weekday ( Wednesday)   G 7 Table G 3 Comparison of 1999 and 2007 Predicted Maximum 8 hour Average Ozone Concentrations by Monitor, September 15th  20th                            . G 14 Table G 4 Comparison of Predicted Peak 8 hour Concentrations for Final UT and AACOG Base and Future Case Runs          . G 22 Table G 5 Modifications to the1999 Base Case and 2007 Future Case as Part of the QA/ QC Process and Resulting Peak 8 hour Predictions at CAMS 23 Associated with Each Run              G 39 Table G 6 Modifications to the1999 Base Case and 2007 Future Case as Part of the QA/ QC Process and Resulting Peak 8 hour Predictions at CAMS 58 Associated with Each Run              G 41 Table G 7 Modifications to the1999 Base Case and 2007 Future Case as Part of the QA/ QC Process and Resulting Peak 8 hour Predictions at CAMS 59 Associated with Each Run              G 43 Table G 8 Modifications to the1999 Base Case and 2007 Future Case as Part of the QA/ QC Process and Resulting Peak 8 hour Predictions at CAMS 678 Associated with Each Run             G 45 G 4 Appendix G List of Figures Page Figure G 1 Comparison of 1999 and 2007 Anthropogenic NOx Precursor Emissions from On road Sources within the 4 km Subdomain on Wednesday, September 15th                 G 8 Figure G 2 Comparison of 1999 and 2007 Anthropogenic NOx Precursor Emissions from Area/ non road Sources within the 4 km Subdomain on Wednesday, September 15th               .. G 9 Figure G 3 Comparison of 1999 and 2007 Anthropogenic NOx Precursor Emissions from Low level Point Sources within the 4 km Subdomain on Wednesday, September 15th            G 10 Figure G 4 Comparison of 1999 and 2007 Anthropogenic VOC Precursor Emissions from On road Sources within the 4 km Subdomain on Wednesday, September 15th                . G 11 Figure G 5 Comparison of 1999 and 2007 Anthropogenic VOC Precursor Emissions from Area/ non road Sources within the 4 km Subdomain on Wednesday, September 15th            G 12 Figure G 6 Comparison of 1999 and 2007 Anthropogenic VOC Precursor Emissions from Low level Point Sources within the 4 km Subdomain on Wednesday, September 15th            G 13 Figure G 7 Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Wednesday, September 15th                       .. G 15 Figure G 8 Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Thursday, September 16th                       .. G 16 Figure G 9 Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Friday, September 17th                       .. G 17 Figure G 10 Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Saturday, September 18th                        G 18 Figure G 11 Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Sunday, September 19th                       . G 19 Figure G 12 Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Monday, September 20th                        G 20 Figure G 13 Predicted Reductions in Ozone Concentrations at CAMS 23 after Zeroing Out Anthropogenic Precursor Emissions for the 11 county Houston Area, 2 county Corpus Christi Area, and 5 county Austin Area from the 1999 Base Case and 2007 Future Case      . G 24 Figure G 14 Predicted Reductions in Ozone Concentrations at CAMS 58 after Zeroing Out Anthropogenic Precursor Emissions for the 11 county Houston Area, 2 county Corpus Christi Area, and 5 county Austin Area from the 1999 Base Case and 2007 Future Case      . G 25 Figure G 15 Predicted Reductions in Ozone Concentrations at CAMS 23 after Removing Various Point Source Emissions within the SAER   Comparison between 1999 and 2007               G 26 G 5 Appendix G List of Figures ( continued) Page Figure G 16 Predicted Reductions in Ozone Concentrations at CAMS 58 after Removing Various Point Source Emissions within the SAER   Comparison between 1999 and 2007          . G 27 Figure G 17 Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Wednesday, September 15th           .. G 29 Figure G 18 Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Thursday, September 16th             G 30 Figure G 19 Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Friday, September 17th             . G 31 Figure G 20 Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Saturday, September 18th               . G 32 Figure G 21 Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Sunday, September 19th                .. G 33 Figure G 22 Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Monday, September 20th                 G 34 Figure G 23 Predicted Ozone Concentrations at CAMS 23 after Removing Local NOx and VOC Emissions from CAMx Run 18, Averages for September 15  20, 1999 and 2007              . G 36 Figure G 24 Predicted Ozone Concentrations at CAMS 58 after Removing Local NOx and VOC Emissions from CAMx Run 18, Average for September 15  20, 1999 and 2007              . G 37 G 6 INTRODUCTION To create a 2007 future case on which to model attainment, certain adjustments were made to the 1999 base case. Meteorological fields, boundary/ initial conditions, dry deposition algorithms, chemical mechanisms and other model configurations remained identical between the September 1999 and 2007 simulations. However, VOC, NOx, and CO emission estimations from anthropogenic sources were adjusted to account for such factors as anticipated growth/ decline in population and employment and the impact of federal, state and regional emission reduction measures. The biogenic emissions inventory ( EI) for the 2007 base was the same as that used for the 1999 base case, in accordance with EPA guidelines.

Tables G 1 and G 2 provide comparisons between the 1999 anthropogenic modeling EI developed for the four county San Antonio Early Action Compact Region ( SAER) and the 2007 anthropogenic modeling EI. Despite projections in population growth in all four SAER counties between 1999 and 2007, most emissions categories are expected to decrease between the base year and attainment year. Overall, anthropogenic VOC emissions for the SAER were projected to decrease by 20.88% between 1999 and 2007; likewise, anthropogenic NOx emissions were projected to decrease by 30.11% during the same timeframe.

Table G 1. Comparison of 1999 and 2007 Anthropogenic VOC Emissions in the Fourcounty SAER for a Typical Weekday ( Wednesday).

County On Road ( tpd) Area / Non road ( tpd) Point ( tpd) Total ( tpd) 1999 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 2007 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 % Difference between 1999 and 2007 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  42.95%  11.85% 88.44%  20.88% G 7 Table G 2. Comparison of 1999 and 2007 Anthropogenic NOx Emissions in the Fourcounty SAER for a Typical Weekday ( Wednesday).

County On Road ( tpd) Area / Non road ( tpd) Point ( tpd) Total ( tpd) 1999 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 2007 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 % Difference between 1999 and 2007 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  42.65%  1.67%  25.85%  30.11%

Figures G 1 through G 3 provide graphical comparisons of the anthropogenic NOx EIs for 1999 and 2007 by source category, both in terms of magnitude of concentrations and spatial allocation of plumes. Similarly, figures G 4 through G 6 provide graphical comparisons between estimated 1999 and 2007 anthropogenic VOC emissions inventories. As indicated by these pictures, on road precursor emissions are concentrated in urban areas. By comparison, area/ non road and point source emissions are more dispersed. It is also evident that, overall, most anthropogenic emission categories are expected to decrease between 1999 and 2007. G 8 Figure G 1. Comparison of 1999 and 2007 Anthropogenic NOx Precursor Emissions from On road Sources within the 4 km Subdomain on Wednesday, September 15th.

1999 2007 San Antonio Austin Victoria Corpus Christi G 9 Figure G 2. Comparison of 1999 and 2007 Anthropogenic NOx Precursor Emissions from Area/ non road Sources within the 4 km Subdomain on Wednesday, September 15th.

1999 2007 G 10 Figure G 3. Comparison of 1999 and 2007 Anthropogenic NOx Precursor Emissions from Low level Point Sources within the 4 km Subdomain on Wednesday, September 15th.

1999 2007 G 11 Figure G 4. Comparison of 1999 and 2007 Anthropogenic VOC Precursor Emissions from On road Sources within the 4 km Subdomain on Wednesday, September 15th.

1999 2007 G 12 Figure G 5. Comparison of 1999 and 2007 Anthropogenic VOC Precursor Emissions from Area/ non road Sources within the 4 km Subdomain on Wednesday, September 15th.

1999 2007 G 13 Figure G 6. Comparison of 1999 and 2007 Anthropogenic VOC Precursor Emissions from Low level Point Sources within the 4 km Subdomain on Wednesday, September 15th.

1999 2007 G 14 2007 BASE CASE Once the 1999 base case was modified by replacing the photochemical model's emissions inputs ( i. e., replacing the 1999 local, state, and regional anthropogenic EI with a 2007 local, state, and regional EI), the model was rerun. The resulting episode projection represents the 2007 future case for the SAER.

The impact of modifying the anthropogenic local and regional emissions inventories between the 1999 base and 2007 future cases is demonstrated in table G 3. As shown, the 2007 projection predicts a decrease in ozone concentration at each San Antonio monitoring station ( 7x7 array of cells near monitor) compared to the 1999 base case predictions.

Table G 3. Comparison of 1999 and 2007 Predicted Maximum 8 hour Average Ozone Concentrations by Monitor, September 15th  20th.

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%

2007 BASE CASE PERFORMANCE EVALUATION Appendix E describes a variety of tests that were conducted on the 1999 base case in order to evaluate model performance. For a future case, such as the 2007 projection, methods of analyzing model performance are more limited. Ozone metrics and several other types of analyses that compare the model's predictions with actual measurements cannot be performed prior to compilation of those actual future measurements. As a consequence, performance analyses conducted on the 2007 future case were restricted to tile plots, comparisons between model refinements, and sensitivity runs.

Tile Plots Tile plots provide an indication of where the model is or isn't performing correctly given known changes to modeling input in the future case. These plots are visual representations of the model's predictions and provide such information as when and where the model predicts urban plumes. The following tile plots ( figures G 7 through G 12) represent comparisons between the 1999 and 2007 8 hour daily maximum ozone concentrations within the modeling domain for each day of the primary episode. G 15 Figure G 7. Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Wednesday, September 15th. 1999 2007 G 16 Figure G 8. Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Thursday, September 16th. 1999 2007 G 17 Figure G 9. Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Friday, September 17th. 1999 2007 G 18 Figure G 10. Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Saturday, September 18th. 1999 2007 G 19 Figure G 11. Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Sunday, September 19th. 1999 2007 G 20 Figure G 12. Comparison of 1999 and 2007 Predicted Daily Maximum 8 hour Ozone Concentrations in the 4 km Subdomain on Monday, September 20th. 1999 2007 G 21 As demonstrated by these plots, urban plumes are replicated predictably, both in terms of intensity and spatial allocation. Peak ozone concentrations are predicted downwind of city centers and major point sources in these tile plots. In addition, the overall reduction in NOx, VOC, and CO emissions ( local and regional) between 1999 and 2007 reduced the magnitude of the ozone plumes in each of the daily 1999 2007 comparisons.

Comparisons Between Model Refinements As described in appendix E, the original September 1999 model was developed by ENVIRON and refined through a collaboration between ENVIRON, UT Austin1, and AACOG ( meteorological model and air quality input refinements). Subsequently, the model was provided to the Texas Near Nonattainment ( NNA) partners2, 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 become dissimilar and provide different predictions for the base case, future case, and control strategy runs.

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 EI data for local and regional areas. Discrepancies in emissions inputs were corrected prior to the final AACOG and UT runs.

An analysis was conducted by AACOG staff to determine any differences between the final 1999 base case refined by UT Austin and the final base case refined by AACOG, based on predicted concentrations at two Austin monitors. The 2007 future cases developed by UT and AACOG were similarly analyzed. The results of these analyses are provided in table G 4. The table provides daily peak 8 hour predictions within the 7x7 array of cells near the Murchison and Audubon monitors for the 1999 and 2007 base cases.

As shown, the differences between predictions by AACOG's final run ( labeled 1999_ sos. f) and UT's final run ( labeled 1999_ v3) are insignificant. With regards to the Murchison monitor, the average difference ( six episode days) in ozone concentrations between the two 1999 base cases was 0.00 ppb, while the average difference at the Audubon monitor was 0.05 ppb. For the 2007 future cases, the average differences in peak ozone concentrations for the six day episode was  0.06 ppb ( Murchison) and   0.04 ppb ( Audubon). These results provide additional, independent verification of the performance of the 1999 base case and 2007 future case.

1 UT Austin acted on behalf of Austin modeling. 2 Development of the September 1999 photochemical model simulation was a collaboration between TCEQ and four Texas NNAs: Austin, Corpus Christi, San Antonio, and Victoria. G 22 Table G 4. Comparison of Predicted Peak 8 hour Concentrations for Final UT and AACOG Base and Future Case Runs.

Monitor UT 1999_ v3 AACOG 1999_ sos. f Average Difference UT 2007_ v3 AACOG 2007. f Average Difference UT RRF AACOG RRF Average Difference Days Date MURC 84.6 84.6 0.00 80.2 80.3  0.06 0.948 0.949  0.001 6 9/ 15   9/ 20 AUDU 81 80.9 0.05 76.7 76.7  0.04 0.948 0.948 0.000 6 9/ 15   9/ 20 Monitor UT 1999_ v3 AACOG 1999_ sos. f Daily Difference UT 2007_ v3 AACOG 2007. f Daily Difference UT RRF AACOG RRF Daily Difference Days Date MURC 77.8 77.8 0.0 75.1 75.1 0.0 0.964 0.965  0.001 1 9/ 15 MURC 75.5 75.4 0.1 72.8 72.8 0.0 0.964 0.966  0.002 1 9/ 16 MURC 86.8 86.7 0.1 82.2 82.2 0.0 0.947 0.948  0.001 1 9/ 17 MURC 84.5 84.4 0.1 79.8 79.8 0.0 0.945 0.946  0.001 1 9/ 18 MURC 89.6 89.7  0.1 83.4 83.4 0.0 0.932 0.930 0.002 1 9/ 19 MURC 93.6 93.6 0.0 88.2 88.3  0.1 0.942 0.942 0.000 1 9/ 20 AUDU 76.2 76.1 0.1 73.7 73.7 0.0 0.968 0.969  0.001 1 9/ 15 AUDU 78.2 78.2 0.0 74.6 74.7  0.1 0.954 0.955  0.001 1 9/ 16 AUDU 87.4 87.4 0.0 82.2 82.2 0.0 0.94 0.941  0.001 1 9/ 17 AUDU 84.5 84.4 0.1 78.8 78.8 0.0 0.933 0.934  0.001 1 9/ 18 AUDU 89.4 89.5  0.1 82.9 82.9 0.0 0.928 0.927 0.001 1 9/ 19 AUDU 70.1 70.2  0.1 68.1 68.2  0.1 0.972 0.971 0.001 1 9/ 20 G 23 Sensitivity Tests Sensitivity tests are used throughout model development as diagnostic tools. These tests are conducted by perturbing model input. Results of sensitivity tests are analyzed in terms of whether the model responded to changes in input and, further, whether the model responded in a manner judged to be appropriate to input modifications.

In addition to providing an indication of model performance, sensitivity tests are useful for providing key information. For example, when applied to a projection year base case, sensitivity runs may be used to analyze the impact of emissions sources in the future. Furthermore, these evaluations may be used to predict the impact of control strategies and assist with determining what types of precursor reductions are likely to be the most effective for reducing ozone concentrations.

The 2007 future case sensitivity tests were conducted by modifying model input in one of two ways: 1) removing the precursor emissions for specific point sources/ urban areas, or 2) reducing the local anthropogenic NOx and VOC emissions inventories in incremental amounts. The results of modifying model input to the 2007 future case are provided in the following sections.

Zero Out Runs: Urban Areas Appendix E describes sensitivity tests conducted on the 1999 base case in which the anthropogenic NOx and VOC EIs for Austin, Corpus Christi, and Houston were removed from, or " zeroed out" of, the model. These tests were also conducted on the 2007 future case, i. e., the 2007 NOx and VOC EIs for Austin, Corpus Christi, and Houston were removed from the future case in three separate tests. Figures G 13 and G 14 provide the predicted changes in ozone concentrations at CAMS 23 and CAMS 58, respectively, after removing the anthropogenic EIs for each of the three urban areas and compares those values to the 1999 sensitivity runs.

As shown by the graphs in figures G 13 and G 14, removing the anthropogenic EI for the 11 county Houston area had the greatest predicted impact on 2007 ozone concentrations in the San Antonio area, followed by the 2 county Corpus Christi area and 5 county Austin area. Moreover, this trend is the same whether referring to the 1999 base or 2007 future case sensitivity runs. During the 1999 episode, the predominate wind direction was such that Houston emissions were more likely to impact San Antonio than Austin or Corpus Christi. Since the meteorological inputs remain identical between base and future cases, it stands to reason that Houston emissions would continue to demonstrate the greatest influence on San Antonio ozone concentrations during the September episode. G 24 Figure G 13. Predicted Reductions in Ozone Concentrations at CAMS 23 after Zeroing Out Anthropogenic Precursor Emissions for the 11 county Houston Area, 2 county Corpus Christi Area, and 5 county Austin Area from the 1999 Base Case ( orange) and 2007 Future Case ( blue).

2.25 parts per billion 0.55 parts per billion 0.24 parts per billion 2.72 parts per billion 0.64 parts per billion 0.27 parts per billion 0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0% 3.5% Austin Removed Corpus Removed Houston Removed Percent Reduction in Ozone ( ppb) 1999 2007 G 25 Figure G 14. Predicted Reductions in Ozone Concentrations at CAMS 58 after Zeroing Out Anthropogenic Precursor Emissions for the 11 county Houston Area, 2 county Corpus Christi Area, and 5 county Austin Area from the 1999 Base Case ( orange) and 2007 Future Case ( blue).

Zero Out Runs: Point Sources Analyses were also conducted in which specific point source emissions were removed from the model in separate sensitivity runs. These tests were run at the request of local elected officials and the TCEQ to identify likely strategies ( VOC versus NOx) for ambient ozone reductions in the SAER.

Figures G 15 and G 16 provide the predicted changes in ozone concentrations at CAMS 23 and 58, as the result of conducting these zero out runs for 1999 and 2007. One run, labeled " CPS Spruce 1 Coal Plant Removed," simulates the impact of removing a currently existing 750 megawatt power plant from the 2007 future case in the San Antonio area. A second run, " Remove All CPS Power Plants," simulates the impact of removing the nine power plants in the San Antonio region in 1999 from the 1999 base case and removing seven power plants ( due to anticipated closures of two plants) from the 2007 future case. A third run " Remove Cement Plants" represents the removal of emissions from all cement kilns in the 4 county SAER. The last run, " Toyota Removed," simulates the impact of removing the EI for a major manufacturing plant from the 2007 2.19 parts per billion 0.45 parts per billion 0.35 parts per billion 2.61 parts per billion 0.57 parts per billion 0.40 parts per billion 0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0% 3.5% Austin Removed Corpus Removed Houston Removed Percent Reduction in Ozone ( ppb) 1999 2007 G 26 Figure G15. Predicted Reductions in Ozone Concentrations at CAMS 23 after Removing Various Point Source Emissions within the SAER   Comparison between 1999 ( orange) and 2007 ( blue).

0.10 parts per billion 0.01 parts per billion 0.16 parts per billion 1.20 parts per billion 0.0 parts per billion  0.17 parts per billion 0.69 parts per billion  0.2% 0.0% 0.2% 0.4% 0.6% 0.8% 1.0% 1.2% 1.4% 1.6% Toyota Removed Remove Cement Plants Remove All CPS Power Plants CPS Spruce 1 Coal Plant Removed*

Percent Reduction in Ozone ( ppb) 1999 2007 * based on 5.93 tons/ day of NOx in 2007 only G 27 Figure G 16. Predicted Reductions in Ozone Concentrations at CAMS 58 after Removing Various Point Source Emissions within the SAER   Comparison between 1999 ( orange) and 2007( blue).

future case. Since the plant is not scheduled to be in operation until 2006, removing these emissions have no impact on the 1999 base case.

As shown in these graphs, removing all power plant emissions had the greatest impact on both the 1999 and 2007 simulations. Since the combined power plants were the largest source of precursors ( NOx) of all sources tested, this type of result is expected. Conversely, the Toyota plant, which has the lowest emission rates ( primarily VOC), impacts San Antonio ozone concentrations the least.

With the exception of the results of removing the cement kiln emissions from the 1999 base case at CAMS 23, each sensitivity run demonstrates a decrease in predicted 1999 or 2007 ozone concentrations. The predicted increase in ozone concentration at CAMS 23 is most likely a reversal of the model's ozone scavenging process. During much of the 1999 episode, the model predicts conditions in which decreases in NOx cause ozone concentrations to increase ( NOx reduction disbenefit). Thus, removing the NOx emissions from kilns near the monitor causes the model to predict increased ozone concentrations at that location in the 1999 base case. 0.08 parts per billion 0.01 parts per billion 0.26 parts per billion 0.97 parts per billion 0.0 parts per billion 0.08 parts per billion 0.74 parts per billion 0.0% 0.2% 0.4% 0.6% 0.8% 1.0% 1.2% 1.4% 1.6% 1.8% Toyota Removed Remove Cement Plants Remove All CPS Power Plants CPS Spruce 1 Coal Plant Removed*

Percent Reduction in Ozone ( ppb) 1999 2007 * based on 5.93 tons/ day of NOx in 2007 only G 28 This NOx reduction disbenfit is much less evident in the 2007 future case. Consequently, removing the NOx emissions associated with the San Antonio area power plants causes larger ozone reductions in the 2007 future case than in the 1999 base case. Since there are no power plants in the vicinity of CAMS 23, removing the 1999 power plant emissions from the model did not cause an increase in predicted ozone levels in the 1999 base case, as was demonstrated by the cement kiln sensitivity run.

At the request of EPA Region 6, the output from each point source " zero out" simulation was run through a graphics program, PAVE, to obtain a visual depiction of the impact of removing these sources in the SAER. The plots for zeroing out point sources were created for all primary episode weekdays, when applicable, 3 as shown in figures G 17 through G 22. An advantage these plots have compared to the graphs for CAMS 23 and 58, shown previously, is that they provide an indication of the impact of modifying emissions in terms of spatial distribution.

As shown by these graphs, the impact of removing point source emissions was, to a large extent, influenced by the model's meteorological processes, particularly wind direction. The September 15th   17th plots, for example, indicate that these emissions primarily affect counties to the west and northwest of Bexar County. In addition, the cement kiln zero out runs tended to show the widest area of influence. This is an expected outcome since the cement kiln emission sources are spread throughout the San Antonio area, whereas all seven CPS power plants are located in southeast Bexar County. Similarly, the Toyota manufacturing plant is represented by a single point in south Bexar County on the plots.

3 Weekends were not included for the Toyota set of sensitivity runs because the plant is not scheduled to be operational on Saturday and Sunday. G 29 Figure G 17. Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Wednesday, September 15th.

Removal of CPS Power Plant Emissions Removal of San Antonio area Cement Kiln Emissions Removal of Toyota Manufacturing Plant Emissions G 30 Figure G 18. Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Thursday, September 16th.

Removal of CPS Power Plant Emissions Removal of San Antonio Area Cement Kiln Emissions Removal of Toyota Manufacturing Plant Emissions G 31 Figure G 19. Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Friday, September 17th. Problems with the graphics software prevented the completion of a tile plot for the September 17th cement kiln sensitivity run Removal of CPS Power Plant Emissions Removal of Toyota Manufacturing Plant Emissions G 32 Figure G 20. Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Saturday, September 18th. Not Applicable Toyota Manufacturing Plant is not scheduled to be operational on Saturdays Removal of CPS Power Plant Emissions Removal of San Antonio Area Cement Kiln Emissions G 33 Figure G 21. Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Sunday, September 19th. Not Applicable Toyota Manufacturing Plant is not Scheduled to be Operational on Sundays Removal of CPS Power Plant Emissions Removal of San Antonio Area Cement Kiln Emissions G 34 Figure G 22. Comparison of Zero Out Runs Conducted for CPS Power Plants, Cement Kilns, and Toyota Manufacturing Plant on the 2007 Future Case, Monday, September 20th.

Removal of CPS Power Plant Emissions Removal of San Antonio Area Cement Kiln Emissions Removal of Toyota Manufacturing Plant Emissions G 35 For the most part, removing point source emissions caused the model to predict decreases in ozone concentrations along the area of impact. However, the model also predicts some areas of increased ozone concentrations, the most prominent of which is the Thursday, September 16th plot depicting the impact of zeroing out cement kiln emissions. Likewise some of the Toyota sensitivity runs exhibit small increases in ozone concentrations near the plant, despite the very low NOx emissions the plant represents ( 0.34 tons/ day). This NOx reduction disbenefit is less pronounced in the power plant sensitivity runs. However, these tile plots depict ozone concentrations in the lowest atmospheric grid layer, whereas power plants pollutants are emitted, by computer simulation, into higher grid layers.

I ncremental Removal of VOC and NOx Precursor Emissions 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 2007 future case. Figures G 23 and G 24 provide the results of the across the board reduction runs for CAMS 23 and CAMS 58 ( San Antonio downwind monitors), averaged over the six day modeling period conducted on the 1999 base and 2007 future cases.

At the 25% reduction level ( CAMS 23), VOC reductions were slightly more effective than NOx reductions at lowering ozone concentrations. At CAMS 58, 25% NOx and 25% VOC reductions are equally effective. These results are somewhat different than those predicted for the 1999 base case in that, at the 25% level, VOC reductions were more effective than NOx for reducing ozone concentrations in the SAER. These results tend to support the evaluation of both VOC and NOx control strategies as possible means of reducing ambient ozone concentrations in the San Antonio region. G 36 Figure G 23. Predicted Ozone Concentrations at CAMS 23 after Removing Local NOx and VOC Emissions from CAMx Run 18, Averages for September 15  20, 1999 and 2007.

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 1999 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 2007 G 37 Figure G 24. Predicted Ozone Concentrations at CAMS 58 after Removing Local NOx and VOC Emissions from CAMx Run 18, Average for September 15  20, 1999 and 2007.

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 1999 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 2007 G 38 SUMMARY OF MODIFICATIONS TO THE 1999 BASE AND 2007 FUTURE CASES AND RESULTING DESIGN VALUES As described previously, a great amount of time and effort were spent ensuring the 2007 future cases developed by UT Austin and AACOG were consistent. As part of that effort, UT and AACOG staff, in consultation with the TCEQ, evaluated local and regional 2007 EI files used as input to the two future cases. Whenever inconsistencies in emissions or procedures were identified, staff from UT, AACOG, and the TCEQ determined the most appropriate data to incorporate into the models. Both the UT and AACOG future cases were modified to reflect these decisions.

Tables G 5 through G 8 summarize the impact of making these modifications to AACOG's 2007 future case. The future case runs, labeled A through G, represent the first future case ( A) developed by AACOG, projected from the 1999 base case labeled CAMx Run 18 ( see appendix E for more information), through the final 2007 future case run ( G). The far right column lists changes that were made to the model for each run.

Results of making the modifications to the future case model simulation are provided for each monitor in the San Antonio region ( CAMS 23, 58, 59, and 678). Based on analyses between the AACOG and UT final future cases ( see section on " Comparisons Between Model Refinements"), it is evident that the extra effort required to analyze all model inputs resulted in consistent, well performing future case simulations on which to model control strategy effectiveness and base attainment demonstrations. G 39 Table G 5. Modifications to the1999 Base Case and 2007 Future Case as Part of the QA/ QC Process and Resulting Peak 8 hour Predictions at CAMS 23 Associated with Each Run.

CAMS 23 Peak Predicted 8 hour Ozone Concentrations Run Label Year 15th 16th 17th 18th 19th 20th Average Design Value Modifications to Model Base Case. A 1999 81.63 78.25 81.39 98.68 102.54 93.73 89.37 89.00 Base Case. B 1999 81.62 78.25 81.36 98.67 102.46 93.68 89.34 89.00

Updated quarry and construction equipment emissions Base Case. D 1999 81.62 78.25 81.36 98.67 102.46 93.67 89.34 89.00

Incorporated new wastewater estimates from San Antonio Water System Base Case. E 1999 81.73 78.16 81.36 98.72 101.59 93.49 89.18 89.00

Updated 1999 area and non road source temporal profiles for regional Texas to match 2007 temporal profiles

Updated point source cut off point from 20m to 50m for the 4km grid Base Case F 1999 81.35 78.22 81.52 98.67 101.49 93.42 89.11 89.00

Updated Victoria's mobile EI with latest data from UT

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

Updated Victoria's point sources

Updated Texas NEGU and EGU sources outside of Houston

Updated Louisiana point source emissions

Updated Austin's area & non road sources Base Case G 1999 81.14 78.08 81.36 98.57 101.40 93.20 88.96 89.00

Updated San Antonio asphalt emissions

Updated tanker truck unloading emissions

Updated tanker trucks in transit emissions

Updated emissions for other gasoline distribution activities Base Case. A 2007 84.56 Base Case. B 2007 80.00 76.21 80.05 89.45 93.92 92.67 85.38 85.06

Updated regional EI HDD non road EI ( provided by TCEQ)

Updated Austin Point Source Control EI ( Alcoa)

Updated San Antonio construction and quarry equipment emissions G 40 CAMS 23 ( continued)

Base Case. D 2007 80.09 76.19 80.01 89.45 93.93 92.67 85.39 85.07

Incorporated new wastewater estimates

Revised Austin Point Source Control EI ( Alcoa)

Base Case. E 2007 79.70 75.20 79.57 88.73 92.48 91.45 84.52 84.35

Revised Austin Point Source Control EI

Incorporated new regional temporal profile for point sources

Added CO for Austin on road EI ( 3 County)

Included stage1 ( 125k) for the 4 county San Antonio MSA

Removed tank truck unloading on Sunday to match EPA guidance

Updated other area source temporal profiles to match EPA guidance

Updated Texas regional area and non road emissions

Updated Texas point sources ( besides CPS)

Updated Lehigh cement Kiln controls

Updated point source cut off point from 20m to 50m on the 4 km grid to match the 12 km grid cut off

Updated Victoria's EI Base Case F 2007 79.70 75.20 79.57 88.73 92.49 91.46 84.53 84.42

Updated Victoria's mobile EI

Updated chemical and temporal profiles for Texas area and non road emissions Base Case G 2007 79.57 75.07 79.50 88.69 92.50 91.57 84.48 84.52

Updated San Antonio asphalt emissions

Updated tanker truck unloading emissions

Updated tanker trucks in transit emissions

Updated emissions from other gasoline distribution activities

Updated emissions for ROP controls G 41 Table G 6. Modifications to the1999 Base Case and 2007 Future Case as Part of the QA/ QC Process and Resulting Peak 8 hour Predictions at CAMS 58 Associated with Each Run.

CAMS 58 Peak Predicted 8 hour Ozone Concentrations Run Label Year 15th 16th 17th 18th 19th 20th Average Base Case Design Value Modifications to Model Base Case. A 1999 75.95 77.44 81.93 98.68 102.75 91.66 88.07 87.00 Base Case. B 1999 75.95 77.44 81.93 98.67 102.68 91.64 88.05 87.00

Updated quarry and construction equipment emissions Base Case. D 1999 75.95 77.44 81.92 98.67 102.68 91.63 88.05 87.00

Incorporated new wastewater estimates from San Antonio Water System Base Case. E 1999 76.00 77.41 81.87 98.72 101.92 91.50 87.90 87.00

Updated 1999 area and non road source temporal profiles for regional Texas to match 2007 temporal profiles

Updated point source cut off point from 20m to 50m for the 4km grid Base Case F 1999 75.74 77.44 82.16 98.67 101.90 91.51 87.90 87.00

Updated Victoria's mobile EI with latest data from UT

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

Updated Victoria's point sources

Updated Texas NEGU and EGU sources outside of Houston

Updated Louisiana point source emissions

Updated Austin's area & non road sources Base Case G 1999 75.59 77.26 82.01 98.57 101.83 91.30 87.76 87.00

Updated San Antonio asphalt emissions

Updated tanker truck unloading emissions

Updated tanker trucks in transit emissions

Updated emissions for other gasoline distribution activities Base Case. A 2007 82.19 Base Case. B 2007 74.11 75.41 79.07 89.45 93.92 90.17 83.69 82.69

Updated regional EI HDD non road EI ( provided by TCEQ)

Updated Austin Point Source Control EI ( Alcoa)

Updated San Antonio construction and quarry equipment emissions G 42 CAMS 58 ( continued)

Base Case. D 2007 74.28 75.40 79.02 89.45 93.93 90.18 83.71 82.71

Incorporated new wastewater estimates

Revised Austin Point Source Control EI ( Alcoa)

Base Case. E 2007 73.91 74.46 78.57 88.73 92.48 89.17 82.89 82.03

Revised Austin Point Source Control EI

Incorporated new regional temporal profile for point sources

Added CO for Austin on road EI ( 3 County)

Included stage1 ( 125k) for the 4 county San Antonio MSA

Removed tank truck unloading on Sunday to match EPA guidance

Updated other area source temporal profiles to match EPA guidance

Updated Texas regional area and non road emissions

Updated Texas point sources ( besides CPS)

Updated Lehigh cement Kiln controls

Updated point source cut off point from 20m to 50m on the 4 km grid to match the 12 km grid cut off

Updated Victoria EI Base Case F 2007 73.90 74.46 78.57 88.73 92.49 89.18 82.89 82.04

Updated Victoria's mobile EI

Updated chemical and temporal profiles for Texas area and non road emissions Base Case G 2007 73.80 74.28 78.50 88.69 92.50 89.25 82.84 82.12

Updated San Antonio asphalt emissions

Updated tanker truck unloading emissions

Updated tanker trucks in transit emissions

Updated emissions from other gasoline distribution activities

Updated emissions for ROP controls G 43 Table G 7. Modifications to the1999 Base Case and 2007 Future Case as Part of the QA/ QC Process and Resulting Peak 8 hour Predictions at CAMS 59 Associated with Each Run.

Gray strike through numbers are values that fall below the EPA requirement ( EPA 1999, p. 41) of 70 ppb to be included in the RRF CAMS 59 Peak Predicted 8 hour Ozone Concentrations Run Label Year 15th 16th 17th 18th 19th 20th Average Base Case Design Value Modifications to Model Base Case. A 1999 66.95 72.04 69.83 72.53 83.04 86.65 76.82 79.00 Base Case. B 1999 66.95 72.04 69.83 72.53 82.90 86.61 76.78 79.00

Updated quarry and construction equipment emissions Base Case. D 1999 66.95 72.04 69.83 72.53 82.90 86.60 76.78 79.00

Incorporated new wastewater estimates from San Antonio Water System Base Case. E 1999 67.33 72.30 69.86 72.58 82.24 86.25 76.65 79.00

Updated 1999 area and non road source temporal profiles for regional Texas to match 2007 temporal profiles

Updated point source cut off point from 20m to 50m for the 4km grid Base Case F 1999 67.12 72.33 70.09 72.38 81.90 86.46 76.63 79.00

Updated Victoria's mobile EI with latest data from UT

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

Updated Victoria's point sources

Updated Texas NEGU and EGU sources outside of Houston

Updated Louisiana point source emissions

Updated Austin's area & non road sources Base Case G 1999 66.89 72.38 69.90 72.12 81.75 86.26 78.13 79.00

Updated San Antonio asphalt emissions

Updated tanker truck unloading emissions

Updated tanker trucks in transit emissions

Updated emissions for other gasoline distribution activities Base Case. A 2007 74.96 Base Case. B 2007 64.65 67.40 67.68 68.97 78.73 84.15 73.38 75.51

Updated regional EI HDD non road EI ( provided by TCEQ)

Updated Austin Point Source Control EI ( Alcoa) G 44 CAMS 59 ( continued)

Base Case. D 2007 64.70 67.40 67.66 68.97 78.73 84.15 73.38 75.51

Updated San Antonio construction and quarry equipment emissions

Incorporated new wastewater estimates

Revised Austin Point Source Control EI ( Alcoa)

Base Case. E 2007 64.25 65.90 68.05 69.21 76.99 83.03 72.64 74.87

Revised Austin Point Source Control EI

Incorporated new regional temporal profile for point sources

Added CO for Austin on road EI ( 3 County)

Included stage1 ( 125k) for the 4 county San Antonio MSA

Removed tank truck unloading on Sunday to match EPA guidance

Updated other area source temporal profiles to match EPA guidance

Updated Texas regional area and non road emissions

Updated Texas point sources ( besides CPS)

Updated Lehigh cement Kiln controls

Updated point source cut off point from 20m to 50m on the 4 km grid to match the 12 km grid cut off

Updated Victoria EI Base Case F 2007 64.25 65.90 68.05 69.21 77.01 83.05 72.64 74.89

Updated Victoria's mobile EI

Updated chemical and temporal profiles for Texas area and non road emissions Base Case G 2007 63.98 65.93 67.82 68.92 76.84 82.96 73.66 74.48

Updated San Antonio asphalt emissions

Updated tanker truck unloading emissions

Updated tanker trucks in transit emissions

Updated emissions from other gasoline distribution activities

Updated emissions for ROP controls G 45 Table G 8. Modifications to the1999 Base Case and 2007 Future Case as Part of the QA/ QC Process and Resulting Peak 8 hour Predictions at CAMS 678 Associated with Each Run.

Gray strike through numbers are values that fall below the EPA requirement ( EPA 1999 , p. 41) of 70 ppb to be included in the RRF CAMS 678 Peak Predicted 8 hour Ozone Concentrations Run Label Year 15th 16th 17th 18th 19th 20th Average Base Case Design Value Modifications to Model Base Case A 1999 70.34 71.19 69.83 80.03 92.94 88.47 78.80 77.00 Base Case B 1999 70.33 71.19 69.83 80.01 92.81 88.33 78.75 77.00

Updated quarry and construction equipment emissions Base Case D 1999 70.33 71.19 69.83 80.01 92.80 88.32 78.75 77.00

Incorporated new wastewater estimates from San Antonio Water System Base Case E 1999 70.57 71.45 69.86 80.06 91.99 87.92 78.64 77.00

Updated 1999 area and non road source temporal profiles for regional Texas to match 2007 temporal profiles

Updated point source cut off point from 20m to 50m for the 4km grid Base Case F 1999 70.39 71.50 70.09 79.81 91.60 87.84 78.54 77.00

Updated Victoria's mobile EI with latest data from UT

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

Updated Victoria's point sources

Updated Texas NEGU and EGU sources outside of Houston

Updated Louisiana point source emissions

Updated Austin's area & non road sources Base Case G 1999 70.16 71.51 69.90 79.63 91.49 87.65 80.09 77.00

Updated San Antonio asphalt emissions

Updated tanker truck unloading emissions

Updated tanker trucks in transit emissions

Updated emissions for other gasoline distribution activities Base Case A 2007 74.71 Base Case B 2007 70.43 69.14 68.99 76.78 87.03 89.14 76.92 75.21

Updated regional EI HDD non road EI ( provided by TCEQ)

Updated Austin Point Source Control EI ( Alcoa) G 46 CAMS 678 ( continued)

Base Case D 2007 70.56 69.14 68.94 76.77 87.04 89.14 76.93 75.22

Updated San Antonio construction and quarry equipment emissions

Incorporated new wastewater estimates

Revised Austin Point Source Control EI ( Alcoa)

Base Case E 2007 70.08 68.00 68.89 76.26 85.53 87.83 76.10 74.51

Revised Austin Point Source Control EI

Incorporated new regional temporal profile for point sources

Added CO for Austin on road EI ( 3 County)

Included stage1 ( 125k) for the 4 county San Antonio MSA

Removed tank truck unloading on Sunday to match EPA guidance

Updated other area source temporal profiles to match EPA guidance

Updated Texas regional area and non road emissions

Updated Texas point sources ( besides CPS)

Updated Lehigh cement Kiln controls

Updated point source cut off point from 20m to 50m on the 4 km grid to match the 12 km grid cut off

Updated Victoria EI Base Case F 2007 70.08 68.00 68.89 76.26 85.55 87.84 76.10 74.61

Updated Victoria's mobile EI

Updated chemical and temporal profiles for Texas area and non road emissions Base Case G 2007 69.89 67.86 68.75 76.11 85.50 87.87 77.45 74.46

Updated San Antonio asphalt emissions

Updated tanker truck unloading emissions

Updated tanker trucks in transit emissions

Updated emissions from other gasoline distribution activities

Updated emissions for ROP controls G 47 REFERENCES U. S. Environmental Protection Agency ( May 1999). Draft Guidance on the Use of Models and Other Analyses in Attainment Demonstrations for the 8 hour Ozone NAAQS. Research Triangle Park, NC: Office of Air Quality Planning and Standards.