Mark Wenclawiak of environmental consulting firm All4 Inc. presented on understanding the role of air quality modeling in environmental compliance. All4 performs complex air permitting and dispersion modeling. Dispersion models are mathematical tools that simulate how air pollutants disperse in the atmosphere. Modeling is used to support permit applications, conduct risk assessments, and evaluate compliance with upcoming regulations. Key inputs to models include emissions data, meteorological data, building dimensions, topography, and receptor grids. Guidance on modeling is available from All4, state environmental agencies, and the EPA.

1. www.all4inc.com
Philadelphia | 610.933.5246
Atlanta | 678.460.0324
Houston | 281.937.7553
Understanding the Role of
Air Quality Modeling in
Environmental Compliance
Mark Wenclawiak, CCM| mwenclawiak@all4inc.com | 678-460-0324
February 10, 2015
Presented to The American Society of Safety Engineers
Augusta/Aiken Chapter
by All4 Inc.

2. 2 Your environmental compliance is clearly our business.
Agenda
 What are air quality models?
 Why do we perform air quality modeling?
 What goes into an air quality model?
 Questions and answers

3. 3 Your environmental compliance is clearly our business.
ALL4
 Environmental consulting firm
 Founded 2002 – currently 40+ employees
 Offices in Philadelphia, Atlanta, Houston
 Specialize in air quality consulting
• Complex air permitting and strategy development
• Air dispersion modeling
• Ambient air quality monitoring
 Dispersion modeling as a company-wide initiative
 www.all4inc.com

4. 4 Your environmental compliance is clearly our business.
The Old Days of Modeling

5. What Are Air Quality
Models?

6. 6 Your environmental compliance is clearly our business.
Air Quality Models
 Models are predictive tools
• Past performance is not a predictor of future results
 Mathematical and numerical techniques to
simulate the physical and chemical processes that
affect air pollutants as they disperse and react in
the atmosphere
• Conservative assumptions

7. 7 Your environmental compliance is clearly our business.
Dispersion is Complex

8. 8 Your environmental compliance is clearly our business.
Models and the Real World…
 Speaking of complex…how do you model this?

9. 9 Your environmental compliance is clearly our business.
Types of Air Quality Models
 Screening
 Refined
 Photochemical
 Long-range transport
 Mobile sources
 U.S. EPA’s preferred/recommended models
• 40 CFR Part 51, Appendix W

10. Why Do We Model?

11. 11 Your environmental compliance is clearly our business.
 Support air permit applications
• Construction projects
• GEPD and SCDHEC air toxics analyses
 Conduct risk assessments
• Human health and environmental impacts
 Play detective (forensics evaluations)
• Nuisance dusts and odor complaints
 Proactively evaluate compliance
• Facility expansions
• Preparing for upcoming regulations
Modeling is Performed to…

12. What Goes Into an Air
Quality Model?

13. 13 Your environmental compliance is clearly our business.
 Emissions information
 Meteorological data
 Building dimensions
 Topography
 Agency-approved protocol
Data Input

14. 14 Your environmental compliance is clearly our business.
Data Input
Hourly Data
Wind Speed
Wind Direction
Ambient Temperature
Land Use Patterns
Topography
Building Dimensions
Stack Dimensions
Exhaust Velocity
Exhaust Temperature
Emission Rates
Predicted Ground Level
Ambient
Concentrations
Beware – Garbage In, Garbage Out!

15. 15 Your environmental compliance is clearly our business.
 Short-term emission rates
 Exhaust (stack) characteristics
 May or may not be readily available
Emissions Information

16. 16 Your environmental compliance is clearly our business.
 Surface data and upper air data
 National Weather Service or on-site data
• Not your Sky Mall weather station
Meteorological Data

17. 17 Your environmental compliance is clearly our business.
Meteorological Data

18. 18 Your environmental compliance is clearly our business.
Meteorological Data

19. 19 Your environmental compliance is clearly our business.
Meteorological Data
AERMOD
Interface
Vertical profiles of wind speed
Lateral and vertical turbulent fluctuations
Potential temperature gradient
Potential temperature
AERMET
Albedo
Surface Roughness
Bowen Ratio
Surface
Characteristics
Calculates
Gaussian
Equation for
Estimating
Dispersion
Wind Speed
Wind Direction
Temperature
Cloud Cover
Meteorological
Observations
Friction Velocity
Monin-Obukhov Length
Convective Velocity Scale
Temperature Scale
Mixing Height
Surface Heat Flux
Planetary Boundary
Layer Parameters

20. 20 Your environmental compliance is clearly our business.
 Horizontal dimensions
 Building height
• Tiers
Building Dimensions

21. 21 Your environmental compliance is clearly our business.
Building Downwash

22. 22 Your environmental compliance is clearly our business.
Building Downwash

23. 23 Your environmental compliance is clearly our business.
 Terrain elevation
 Land use
 From these, develop a receptor grid
• Exclude onsite receptors
Topography

24. 24 Your environmental compliance is clearly our business.
 Typical receptor grid spacing:
• 100 meters out to 2 kilometers
• 200 meters out to 5 kilometers
• 500 meters out to 10 kilometers
• 25 meter spacing along fenceline, assuming that only
offsite receptors are being modeled
 Public access must be restricted in some way
(e.g., fence, armed guards, attack dogs, moat) in
order for onsite receptors to be disregarded in
the modeling analysis
Receptor Grid

25. 25 Your environmental compliance is clearly our business.
Receptor Grid

26. 26 Your environmental compliance is clearly our business.
Don’t Forget Background Data!
188
NO21-hourConcentration(µg/m3)
80
NAAQS
Level
Monitored
Background Value
108 µg/m3 available
for modeling

27. 27 Your environmental compliance is clearly our business.
 All4 Inc.
 GEPD
• http://www.georgiaair.org/airpermit/html/sspp/mode
ling.htm
 SCDHEC
• http://www.scdhec.gov/Environment/AirQuality/Com
plianceandReporting/AirDispersionModeling/
 U.S
• http://www.epa.gov/scram001/
Resources and Guidance

28. www.all4inc.com
Philadelphia | 610.933.5246
Atlanta | 678.460.0324
Houston | 281.937.7553
Questions & Open Discussions