1. TCEQ Air Permits Division Justin Cherry, P.E. Ahmed Omar Stephen F. Austin State University February 28, 2013

2. Outline  TCEQ  Air Permits Division  Air Dispersion Modeling Team  Modeling Overview  AERMOD  Examples  Questions?

3. What is the TCEQ? The Texas Commission on Environmental Quality strives to protect our state's human and natural resources consistent with sustainable economic development. Our goal is clean air, clean water, and the safe management of waste.

4. Air Permits Division A ny person who plans to construct any new facility or engage in the modification of any existing facility which emits air contaminants into the atmosphere shall obtain a permit pursuant to Title 30 Texas Administrative Code (30 TAC) § 116.111.

5. Air Permits Division  New Source Review (NSR) program Two main goals: ○ Clean up dirty areas ○ Keep clean areas clean

6. What do we permit?

7. Air Permits Division  Technical Review... Identify emission sources Confirm emissions calculations Determine Best Available Control Technology Determine applicability of state/federal rules and regulations Analyze off-property health impacts

8. Air Dispersion Modeling Team  Provide guidance TCEQ Permit Reviewers Air Permit Applicants Consulting Firms  Review modeling demonstrations  Conduct modeling for small businesses/permit resolution

9. Modeling Overview  Why model? To assess impacts from new or modified sources Requirement to conduct modeling is contained in: ○ 30 TAC Chapter 116 ○ 40 CFR Parts 51, 52, 266 Cost-effective tool to estimate impacts ○ Ambient monitoring is expensive

10. Modeling Overview  Modeling for regulatory purposes Federal Review/PSD ○ NAAQS CO, Pb, NO 2, O 3, PM 10, PM 2.5, and SO 2 ○ Increment SO 2, NO 2, PM 10, and PM 2.5

11. Modeling Overview  Modeling for regulatory purposes (continued) State Review ○ Property Line Standards SO 2, H 2 S, and H 2 SO 4 ○ NAAQS CO, Pb, NO 2, O 3, PM 10, PM 2.5, and SO 2 ○ Effects Review Non-criteria pollutants Examples: formaldehyde, ammonia, and benzene

12. Modeling Overview  Emission Event Modeling Accidental releases ○ Unplanned events ○ Upsets  State Implemention Plan (SIP) Modeling ○ An enforceable plan developed at the state level that explains how the state will comply with air quality standards according to the Federal Clean Air Act.

13. Modeling Overview  What is a model ? A tool used to predict impacts from new and existing sources of emissions. Mathematical equations used to simulate atmospheric processes ○ Transport ○ Dispersion ○ Transformation ○ Removal

14. Modeling Overview  Two levels Screening (SCREEN3 or AERSCREEN) ○ One source ○ Worst-case meteorology Refined (ISC3 and AERMOD) ○ Many sources ○ Specific meteorology ○ Many locations of interest

15. AERMOD  American Meteorological Society/Environmental Protection Agency Regulatory Model

16. AERMOD: Input Information  Source input data Source location, parameters, emission rates Different types of sources: ○ Point ○ Area ○ Volume  Building (downwash) information ○ Mechanical turbulence due to structure ○ Enhanced turbulence = greater dispersion ○ Can reduce plume rise

17. AERMOD: Input Information  Downwash Simulation

18. AERMOD: Input Information  AERMAP Calculates elevations for: ○ Terrain Data Source base elevations Building base elevations Receptor base elevations ○ Receptor locations Where concentrations are predicted

19. AERMOD: Input Information  AERMET Processes meteorological data into format used by model ○ Meteorological data Surface data Upper air data

20. AERMOD: Input Information  AERMET (continued) Incorporates surface characteristics ○ AERSURFACE Land use/land cover data Albedo Bowen ratio Surface roughness

21. AERMOD: Model Options  Source Groups Group sources together to get an impact for that group. Several source groups may be setup in a single run  Averaging Times 1-hr, 3-hr, 8-hr, 24-hr, or annual ○ Dependent on the pollutant being evaluated.

22. AERMOD: Model Options  Hour of Day Scalar When hours of operation need to be limited.  Wind Scalar Applied to particulate sources (i.e. storage pile) for more accurate wind speeds.

23. Example: AERMOD Output Averaging Time Overall Concentration/Impact Source Group

24. Example: Property Line

25. Example: Receptor Grid Receptor

26. Example: Buildings & Sources

27. Questions ?