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!