Complying with the NAAQS – PM2.5 Air Quality Modeling Considerations by ALL4

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Complying with the NAAQS – PM2.5
Air Quality Modeling
Considerations
Dan Dix | ddix@all4inc.com | 610.933.5246 x118
May 12, 2015
Presented to NCASI Northern Regional Meeting
by All4 Inc.

2 Your environmental compliance is clearly our business.
Agenda
 PM2.5 NAAQS (Where are we now)
 Fugitive PM2.5 Impacts vs. Point Source in the forest products
industry
 Ambient Air Boundary (Important for PM2.5 fenceline impacts)
 Source Information (Roadway and Storage Pile Silt Content)
 PM2.5 Background Concentrations for NAAQS Analyses
 Beta Options (LOWWIND1 and ADJ_U*)
 Meteorological Data (Onsite vs. NWS)
 Additional Considerations

PM2.5 NAAQS
 2006 24-Hour PM2.5 NAAQS (35mg/m3) – Primary and Secondary
 1997 Annual PM2.5 NAAQS (15 mg/m3) – Secondary (Primary
revoked when 2012 established in 2012)
 2012 Annual PM2.5 NAAQS (12 mg/m3) – Primary
 Final 2012 Annual PM2.5 NAAQS Designated on January 15, 2015
 Updates to some areas initially designated non-attainment to
attainment made on April 7, 2015 based on 2012-2014 monitoring
data.
 U.S. EPA’s “Guidance for PM2.5 Permit Modeling”

PM2.5 NAAQS

Fugitive PM2.5 Modeling
 Large concentration gradient associated with forest products
industry fugitive sources make compliance with 24-hour and
Annual PM2.5 NAAQS difficult.
 Modeled (predicted) concentrations exhibit high sensitivity to
fugitive source emission rates and outsized impacts when
compared to point sources
• 8 lb/hr fugitive emission rate resulted in a predicted 24-hour
modeled concentration of 74mg/m3 while a 522 lb/hr point
source emission rate resulted in a predicted 24-hour modeled
concentration of 63mg/m3 24-hour

Fugitive PM2.5 Modeling
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Scenario 1 Scenario 2 Scenario 3 Scenario 4
ModeledEmissionRate(lb/hr)
ModeledConcentration(µg/m3)
Peak 98th Percentile of 24-Hour Modeled PM2.5
Fugitive Concentrations
Pile Concentration (ug/m3)
Roadway Concentration
(ug/m3)
Roadway Emissions (lb/hr)
Pile Emissions (lb/hr)
NAAQS Level (ug/m3)
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Scenario 1 Scenario 2 Scenario 3 Scenario 4
Peak Annual Modeled PM2.5 Fugitive
Concentrations
Pile Concentration (ug/m3)
Roadway Concentration
(ug/m3)
Roadway Emissions (lb/hr)
Pile Emissions (lb/hr)
NAAQS Level (ug/m3)

Ambient Air Boundary
 Current ambient air boundary established with State Agency
 Own property on both sides of the river
 Own the up-river dam
 Paradigm shift for EPA and State Agencies

Source Distance to Ambient Air Boundary
Lime Kiln 110 Meters
Power Boiler 15 Meters
Recovery Boiler 150 Meters
Roadway 6 Meters
Chip Piles 20 Meters
Paper Machine Dryers 70 Meters

 Mill could easily use security surveillance system to control access
to the river
 Therefore ambient air boundary could be updated to adjacent
property boundary on the other side of the river
Source Distance to Updated Ambient Air
Boundary
Lime Kiln 300 Meters (+190)
Power Boiler 175 Meters (+160)
Recovery Boiler 310 Meters (+160)
Roadway 160 Meters (+154)
Chip Piles 245 Meters (+225)
Paper Machine Dryers 210 Meters (+140)

 Understand your ambient air boundary
 Work with State Agency to develop appropriate ambient air
boundary
 Understand where your fugitive (i.e., roadway/pile) and low
release point (i.e., process silos/starch silos) sources are relative to
your ambient air boundary

 Background PM2.5 ambient monitoring data required for NAAQS
analyses along with other local sources.
 Two methods for combining PM2.5 monitoring data and modeling
data summarized in U.S. EPA’s “Guidance for PM2.5 Permit
Modeling” finalized in May 2014.
• Tier 1 – Combine design value (i.e., 3-year average annual or 3-
year average of 98th percentile of 24-hour)
• Tier 2 – Incorporates seasonal variation for 24-hour NAAQS.
Background PM2.5

 Background Concentration Example
• Tier 1: 11.6 mg/m3 – Annual, 28.3 mg/m3 -24-Hour
• Tier 2: 24-Hour –Remove top 8 concentrations from
each year, then select max from each meteorological
season
Background PM2.5
PM2.5 Concentration (µg/m3
)
Year Annual
24-Hour
Winter Spring Summer Autumn
2012 11.6 26.4 25.4 24.1 25.0
2013 11.9 28.4 19.3 23.3 23.2
2014 11.4 26.4 23.5 23.2 21.8
Average 11.6 27.1 22.7 23.5 23.3

Background PM2.5
 AERMOD option to vary background concentration by wind sector
to avoid double counting of modeled and monitoring
concentrations (BGSECTOR).
 Monitoring sites inside a 90 sector downwind of the source may be
used to determine the area of impact.
 With multiple sources the downwind sector can have a greater arc

Background PM2.5

Analysis of Roadway Silt Sampling
 Mill specific silt sample conducted for 2 mills following AP-42
Appendix C.1 – “Procedures for Sampling Surface/Bulk Dust
Loading” (July 1993) and Appendix C.2 – “Procedures for
Laboratory Analysis of Surface/Bulk Dust Loading Samples” (July
1993).
 24 samples collected for 18 discrete segments.
 Average site specific sL 2.5 g/m2
 Average entrance (closest fenceline segment) 0.27 g/m2
 AP-42 Appendix C.2 defines sL as PM < 75 micrometers (200 mesh
screen)
 Mesh sizing available down to 632 (20 micrometers)

Summary of Site Specific Paved Roadways Silt Loadings
Mill Mill Process Area No. of Samples Total Weight (g) % sL Weight (g) Area (m2) sL (g/m2)
Mill A Main Entrance 3 N/A N/A 23.26 62.71 0.37
Mill A Pulping Area 2 N/A N/A 20.27 42.74 0.47
Mill A Paper Machine Area 1 N/A N/A 46.39 20.44 2.27
Mill A Landfill 2 N/A N/A 42.7 30.35 1.4
Mill A Chipping Area 1 N/A N/A 20.61 14.86 1.39
Mill A Lime Kiln 1 N/A N/A 43.21 13.94 3.10
Mill A WWTP 1 N/A N/A 3.87 14.63 0.26
Mill A Lime Kiln 1 N/A N/A 5.46 16.26 0.34
Mill B Main Entrance 1 0.58 1.2 0.01 1.11 0.01
Mill B Chipping Area 3 1689.00 4.3 72.63 3.34 21.72
Mill B Roundwood Area 1 12.69 0.73 0.09 1.11 0.08
Mill B Roundwood Area 1 348.00 4.2 14.62 1.11 13.11
Average
Main Entrance 10 0.27
Pulping Area 2 0.47
Paper Machine Area 1 2.27
Landfill 2 1.41
Chipping Area 4 11.55
Lime Kiln 2 1.72
WWTP 1 0.26
Roundwood Area 2 6.60
Mill A 12 1.20
Mill B 12 3.67
Mill A/B 24 2.57

Summary of AP-42 Table 132.1-3 Paved Roadway Silt Loadings
Industry No. Sites No. Of Samples sL (g/m2)
Copper Smelting 1 3 292
Iron and Steel Production 9 48 9.7
Asphalt Batching 1 3 120
Concrete Batching 1 3 12
Sand and Gravel Processing 1 3 70
Municipal Solid Waste Landfill 2 7 7.4
Quarry 1 6 8.2
Corn Wet Mills 3 15 1.1

0
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0
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Site Specific Silt AP-42 Silt
Peak Annual Modeled PM2.5 Fugitive Roadway Concentrations
Roadway Concentration (ug/m3) Roadway Emissions (lb/hr) NAAQS Level (ug/m3)

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35
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Site Specific Silt AP-42 Silt
Peak 98th Percentile of 24-Hour Modeled PM2.5 Fugitive
Roadway Concentrations
Roadway Concentration (ug/m3) Roadway Emissions (lb/hr) NAAQS Level (ug/m3)

 In the 12345 version release of AERMOD LOWWIND1 and ADJ_U*
beta options were incorporated that can be useful in low release
point and fugitive source modeling
• Friction velocity (U*) used to calculate mixing height, initial
horizontal, and vertical dispersion
• ADJ_U* option for low wind speed stable conditions based on
Quian and Venkatram
• LOWWIND1 option increase the minimum value of sigma-v and
turns off the meander component
AERMOD Beta Options

 Currently are considered non-default options and are therefore
subject to the alternative model provisions.
 ADJ_U* alternative model justification easier undertaking because
of peer-reviewed study (Qian and Venkatram, 2011)
 Beta Option Test Case
• Fugitive Roadway Emission from Pulp & Paper Mill with onsite
meteorological data and site specific silt loading.
• Base Case: Default AERMET and AERMOD Options
• Beta Case: 0.5 wind speed threshold ADJ_U* Beta Option
AERMOD Beta Options

AERMOD Beta Options
0
5000
10000
15000
20000
25000
0 0.2 0.4 0.6 1 1.2 1.4 1.8
NumberofHours
Friction Veleocity, U* (m./s)
Comparison of Base Case and U* Ajusted Data Set Friction Veloticies
U* Adjusted Data Set Base Case Data Set

AERMOD Beta Options
0
20
40
60
80
100
120
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160
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Concentrations(mg/m3)
Friction Velocity, U* (m/s)
Hourly Predicted Modeled Concentrations Vs. U* Value
Base Case Data Set U* Adjusted Data Set

 Use of offsite meteorological data (usually National Weather
Service Data) for PSD air quality modeling analyses requires 5-
years of onsite data which usually includes the following
measurements used by AERMET:
• Horizontal Wind Speed and Direction
• One Temperature Level
• Pressure
• Cloud Cover
Onsite Met vs. Offsite Met

 Use of onsite meteorological data for PSD air quality modeling
analyses requires 1-year of onsite data which can include the
following additional sensors which are also used by AERMET to
better predict atmospheric conditions:
• Vertical Wind Speed (i.e, standard deviation AKA sigma W)
• Multiple Levels of Temperature Data
• Solar Radiation and/or Net Radiation
• Multiple Levels of Horizontal Wind Speed and Directions
(collected from a tower or SODAR)

 Advantages of Collecting Onsite Meteorological Data
• Site Specific
• Measurements at stack top and plume rise elevations vs.
extrapolated measurements
• Especially (and in some cases required) beneficially in complex
terrain settings
• Meteorological data can be used for other Mill related activities

 Elephant in the Room
• Addressing cumulative PM2.5 impacts of PM2.5
precursors SO2 and NO2.
Additional PM2.5 Modeling Considerations

Complying with the NAAQS – PM2.5 Air Quality Modeling Considerations by ALL4

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