TCEQ Air Permits Division
Justin Cherry, P.E.Reece Parker
Stephen F. Austin State UniversityFebruary 26, 2015
Outline TCEQ Air Permits Division Air Dispersion Modeling Team Modeling Overview AERMOD Examples Questions?
What is the TCEQ?
The Texas Commission on EnvironmentalQuality strives to protect our state's humanand natural resources consistent withsustainable economic development. Our goalis clean air, clean water, and the safe
management of waste.
Air Permits Division
Any 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.
Air Permits Division
New Source Review (NSR) program
Two main goals:○ Clean up dirty areas○ Keep clean areas clean
What do we permit?
Air Permits Division
Technical Review...Identify emission sourcesConfirm emissions calculationsDetermine Best Available Control TechnologyDetermine applicability of state/federal rules
and regulationsAnalyze off-property health impacts
Air Dispersion Modeling Team
Provide guidanceTCEQ Permit ReviewersAir Permit ApplicantsConsulting Firms
Review modeling demonstrations Conduct modeling for small
businesses/permit resolution
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
Modeling Overview
Modeling for regulatory purposesFederal Review/PSD
○ NAAQSCO, Pb, NO2, O3, PM10, PM2.5, and SO2
○ IncrementSO2, NO2, PM10, and PM2.5
Modeling Overview Modeling for regulatory purposes
(continued)State Review
○ NAAQSCO, Pb, NO2, O3, PM10, PM2.5, and SO2
○ Property Line StandardsSO2, H2S, and H2SO4
○ Effects ReviewNon-criteria pollutantsExamples: formaldehyde, ammonia, and benzene
Modeling Overview
Emission Event ModelingAccidental 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.
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
Modeling Overview
Two levelsScreening (SCREEN3 or AERSCREEN)
○ One source○ Worst-case meteorology
Refined (ISC3 and AERMOD)○ Many sources○ Specific meteorology○ Many locations of interest
AERMOD
American Meteorological Society/Environmental Protection Agency Regulatory Model
AERMOD: Input Information
Source input dataSource location, parameters, emission ratesDifferent types of sources:
○ Point○ Area○ Volume
Building (downwash) information○ Mechanical turbulence due to structure○ Enhanced turbulence = greater dispersion○ Can reduce plume rise
AERMOD: Input Information Downwash Simulation
AERMOD: Input Information
AERMAPCalculates elevations for:
○ Terrain DataSource base elevationsBuilding base elevationsReceptor base elevations
○ Receptor locationsWhere concentrations are predicted
AERMOD: Input Information
AERMETProcesses meteorological data into format used by
model○ Meteorological data
Surface dataUpper air data
AERMOD: Input Information
AERMET (continued)Incorporates surface characteristics
○ AERSURFACELand use/land cover dataAlbedoBowen ratioSurface roughness
Types of Plume Rise
5 Types
Fanning Fumigating Looping Coning Lofting
AERMOD: Model Options
Source GroupsGroup 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.
AERMOD: Model Options Hour of Day Scalar
When hours of operation need to be limited.
Wind ScalarApplied to particulate sources (i.e. storage
pile) for more accurate emission representations.
Example: AERMOD OutputAveraging Time
Overall Concentration/Impact
Source Group
Example: Property Line
Example: Receptor Grid
Receptor
Example: Buildings & Sources
The Mickey Leland Environmental Internship Program
http://www.tceq.texas.gov/adminservices/employ/mickeyleland/
The Transitions Hiring Program
http://www.tceq.texas.gov/adminservices/employ/transitions/
Questions?Thank you!