Air Permitting and Advanced Dispersion

Modeling Services

Ron Petersen, PhD, CCM Sergio Guerra, Ph.D.

Cell: 970 690 1344 Cell: 612 584 9595

rpetersen@cppwind.com sguerra@cppwind.com

CPP, Inc.

2400 Midpoint Drive, Suite 190

Fort Collins, CO 80525

www.cppwind.com @CPPWindExperts

Who We Are

• An air quality and wind engineering consulting firm based in Fort

Collins, CO

• Founded in 1981 as a spin off from Colorado State University

• Offices in Australia, San Francisco, Boston, New York City, Dubai,

Singapore and Malaysia

What We Do

• Air permitting and advanced dispersion modeling

• Industrial wind tunnel modeling

• Particle and snow deposition

• Fume reentry

• Cooling tower impacts

• Expert testimony/forensics

• Wind energy assessments

• Pedestrian comfort

• Structural and cladding wind loads

• Natural ventilation/internal flows

• Fire and smoke management

Why CPP for Permitting?

We have the best solutions to your permitting problem using AERMOD and advanced analysis methods such as: Equivalent Building Dimensions, wind tunnel determined GEP stack heights, EMVAP, emission rate analysis, site specific background analysis, in-stack NO2/NOx ratio optimization.

Using all the advanced analysis methods and tools available, CPP can help optimize emission control equipment and stack heights and in some cases make a no-go project work.

• NAAQS are more stringent

• Initial modeling may show your project exceeds the

Significant Impact Levels (SILs) >> will trigger

requirement for a detailed Air Quality Impact

Assessment

• AERMOD modeling is likely to show non-compliance

with NAAQS in many situations

• AERMOD tends to overpredict in many cases

Problem

Air Permitting

• Completion of air permit applications to satisfy for Federal NSR, Title V and

Local/state programs

• Standard dispersion modeling (SIL, NAAQS, PSD Increment, Air Toxics,

Odor, etc.)

• Advanced Dispersion Modeling Solutions

• Equivalent Building Dimension (EBD) Studies

• Emission Variability Processor (EMVAP)

• GEP stack height evaluations

• Evaluation of background concentrations

• Haul road characterization based on site specific dispersion coefficients

• Fugitive dust emissions based on site-specific friction velocity

• Adjusted friction velocity (u*) in AERMET

Standard AERMOD Modeling Process

Advanced Model Input Analysis Solutions

• Emission Variability

Processor (EMVAP)

• Evaluation of

background

concentrations

• Adjusted friction

velocity (u*) in

AERMET

EM Magazine, December 2014

Guerra, S.A. “Innovative Dispersion Modeling

Practices to Achieve a Reasonable Level

of Conservatism in AERMOD Modeling

Demonstrations.” EM Magazine, December 2014.

Advanced Wind Tunnel Modeling Solutions

• Equivalent Building Dimension (EBD) studies

• GEP stack height evaluations

• Haul road characterization based on site specific

dispersion coefficients

• Fugitive dust emissions based on site-specific

friction velocity

Basic Wind Tunnel Modeling Methodology

• Specify model operating conditions

• Construct scale model

• Install model in wind tunnel and

measure desired quantity

Measure Ground-level Concentrations

Tracer

from stack

Max ground-level concentrations measured versus x

GEP Stack Height

• 40 CFR 51.110 (ii) Defines GEP stack height to

be the greater of:

• 65 meters; the formula height; or

• The height determined by a wind tunnel modeling

study – Can be taller than the formula!!

• Up to 3.25 times the building height

versus 2.5 for the formula

• Typically 2 times the nearby terrain

height

Real World Example – Rhinelander Mill

SO2 Monitor Exceeds 1-hr SO2 NAAQS

Stack

AERMOD predicts 1-hr SO2 NAAQS met

AERMOD predictions 50% of monitored value

Corner Vortex Problem

Formula GEP Height 75 m, Taller Stack Needed

Wind Tunnel Modeling Conducted

1:240 Scale Model of Rhinelander Installed in Wind Tunnel

Advanced AERMOD Modeling Process

• Equivalent Building Dimensions” (EBDs) are the dimensions (height, width, length and location) that are input into AERMOD in place of BPIP dimensions to more accurately predict building wake effects

• Guidance originally developed when ISC was the preferred model –

• EPA, 1994. Wind Tunnel Modeling Demonstration to Determine Equivalent Building Dimensions for the Cape Industries Facility, Wilmington, North Carolina. Joseph A. Tikvart Memorandum, dated July 25, 1994. U.S. Environmental Protection Agency, Research Triangle Park, NC

• Determined using wind tunnel modeling

• How does EBD Improve Accuracy? Watch video

What is EBD?

Advanced AERMOD Modeling

Case Study: Refinery A

3D Printed

Scale Model

Stack height: 45 m

Structure height: 61 m

Emission rate: 1 g/s

Five years of met data

Stack

Building

Input 1-hour 24-hour annual

BPIP 23.21 5.51 0.37

Wind Tunnel EBD 7.72 2.36 0.11

Reduction Factor 3.01 2.33 3.51

Maximum Concentration Results

AERMOD Results – Lattice Structure

Refinery Structures Upwind

Solid BPIP Structure Upwind

No Structures

WHY EBD Helped

AECOM (David Shea) Conducted Field Study

That Validated use of EBD – see AWMA 2007 papers

• Short, wide and long buildings

• Wide and narrow buildings

• Lattice structures

• Streamlined structures

Other Examples Where AERMOD Overpredicts

Stack S_288 From ALCOA EBD Study

Stack height = 27 m

Q = 1 g/s

Building height = 17 m

Building width/length > 200 m

5 years of meteorological data

(Moline/Quad-City Airport 2000-2004

Building Input 1-hr 3-hr 24-hr annual

BPIP 129.1 101.7 38.2 4.0

Wind Tunnel EBD 27.3 17.8 7.9 0.5

Decrease Factor 4.7 5.7 4.8 7.9

Maximum concentration (ug/m3)

Stack height: 47 m

Building height: 31 m

Property line in Red

Emission rate: 1 g/s

AERMOD RESULTS

Five years of met data AERMOD Building Dimension

Inputs 1-hour 24-hour annual

BPIP 15.19 8.20 0.89

Screening EBD Values 9.68 5.05 0.19

EBD values from wind tunnel

study3.99 1.88 0.18

AERMOD Maximum predicted

concentration (μg/m3)

Wide/narrow building

Typical AERMOD Predictions for Refinery

Structures with BPIP and EBD Inputs

0.00

0.25

0.50

0.75

1.00

BPIP EBD

Predicted Concentrations

FACTOR of 2 to 3.5 reduction when EBD used

Lattice Structures

0.00

0.25

0.50

0.75

1.00

BPIP EBD

Predicted Concentrations

FACTOR of 4 to 8 reduction when EBD used

Short building with a large foot print

Typical AERMOD Predictions for Buildings

with Large Footprint BPIP and EBD Inputs

0.00

0.25

0.50

0.75

1.00

BPIP EBD

Predicted Concentrations

FACTOR of 2 to 5

reduction when EBD used

Very Wide/Narrow Buildings

Typical AERMOD Predictions for Very

Wide/Narrow Buildings with BPIP and EBD

Summary

We can bring best solution to for you permitting problem using AERMOD and advanced analysis methods such as Equivalent Building Dimensions, wind tunnel determined GEP stack heights, EMVAP, emission rate analysis, site specific background analysis, in-stack NO2/NOx ratio optimization.

Using all the advanced analysis methods and tools available CPP can help optimize emission control, equipment, and stack heights and in some cases make a no-go project work.

Ron Petersen, PhD, CCM, FASHRAE Sergio Guerra, PhD rpetersen@cppwind.com sguerra@cppwind.com

Mobile: + 970 690 1344 Mobile: + 612 584 9595

CPP, Inc.

2400 Midpoint Drive, Suite 190

Fort Collins, CO 80525

+ 970 221 3371

www.cppwind.com @CPPWindExperts

Questions?