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 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 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 Your environmental compliance is clearly our business.

The Old Days of Modeling

What Are Air Quality Models?

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 Your environmental compliance is clearly our business.

Dispersion is Complex

8 Your environmental compliance is clearly our business.

Models and the Real World… Speaking of complex…how do you model this?

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

Why Do We Model?

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…

What Goes Into an Air Quality Model?

13 Your environmental compliance is clearly our business.

Emissions information Meteorological data Building dimensions Topography Agency-approved protocol

Data Input

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 Your environmental compliance is clearly our business.

Short-term emission rates Exhaust (stack) characteristics May or may not be readily available

Emissions Information

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 Your environmental compliance is clearly our business.

Meteorological Data

18 Your environmental compliance is clearly our business.

Meteorological Data

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 Your environmental compliance is clearly our business.

Horizontal dimensions Building height

• Tiers

Building Dimensions

21 Your environmental compliance is clearly our business.

Building Downwash

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Building Downwash

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Terrain elevation Land use From these, develop a receptor grid

• Exclude onsite receptors

Topography

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 Your environmental compliance is clearly our business.

Receptor Grid

26 Your environmental compliance is clearly our business.

Don’t Forget Background Data!

188

NO

2 1-h

our C

once

ntra

tion

(µg/

m3 )

80

NAAQS Level

Monitored Background Value

108 µg/m3 available for modeling

27 Your environmental compliance is clearly our business.

All4 Inc. GEPD

• http://www.georgiaair.org/airpermit/html/sspp/modeling.htm

SCDHEC • http://www.scdhec.gov/Environment/AirQuality/Com

plianceandReporting/AirDispersionModeling/

U.S • http://www.epa.gov/scram001/

Resources and Guidance

www.all4inc.com Philadelphia | 610.933.5246

Atlanta | 678.460.0324 Houston | 281.937.7553

Questions & Open Discussions