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National Ambient Air Quality Standards for NO 2 and SO 2 – New Modeling Challenges. August 4, 2011 Air & Waste Management Association – Southern Section Meeting & Technical Conference Justin Fickas , P.E. Managing Consultant. Introductions Justin Fickas , P.E.– Managing Consultant. - PowerPoint PPT Presentation
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National Ambient Air Quality Standards for NO2 and SO2 –
New Modeling ChallengesAugust 4, 2011
Air & Waste Management Association – Southern Section Meeting &
Technical Conference
Justin Fickas, P.E.Managing Consultant
IntroductionsJustin Fickas, P.E.– Managing Consultant
Managing Consultant based in Atlanta Extensive experience serving wood products, pulp
& paper, power, and general manufacturing industries
B.S. Civil Engineering with an emphasis in Environmental Engineering from Purdue University
Professional Engineer registered in Georgia Joined Trinity in July 2010 – 13 yrs of consulting
experience
Presentation Outline Modeling 101 Overview of the New 1-hr NAAQS Case Studies - “Real World” project examples Going forward – Options to consider in assessment
of the new NAAQS Conclusions
Modeling 101
When are Models Needed?
Regulatory - to determine air quality impacts due to sources of air emissions to determine compliance with existing NAAQS
Engineering – to discern viable control and mitigation options in terms of the net change in air quality
Health – to estimate risk and acute effects
Ecological – to calculate effects on soils & vegetation
The General New Source Review (NSR) Permit Modeling Process - NAAQS
Model facility impacts for comparison to Significant Impact Levels (SILs) established for pollutants of interest
If facility impacts do not exceed the SIL, no further action is needed
If facility impacts exceed the SIL Off-site source impacts (inventory) needs to be
evaluated and developed Both your facility and off-site sources are modeled If exceedances of NAAQS are shown, can be
acceptable so long as it is demonstrated that your facility is not significantly contributing to the exceedance
Guideline on Air Quality Models 40 CFR Part 51, Appendix W
Preferred models are AERMOD and CALPUFF
Provides methodologies for regulatory dispersion modeling
Does not directly include procedures to address the new 1-hour NAAQS (NO2 and SO2)
How Do We Choose a Modeling Methodology?
EPA Clearinghouse Memos “Applicability of Appendix W Modeling
Guidance for the 1-hour NO2 National Ambient Air Quality Standard”, June 28, 2010
“Applicability of Appendix W Modeling Guidance for the 1-hour SO2 National Ambient Air Quality Standard”, August 23, 2010
“Additional Clarification Regarding Application of Appendix W Modeling Guidance for the 1-hour NO2 National Ambient Air Quality Standard”, March 1, 2011
State Issued Guidance
Overview of the New 1-hr NAAQS
New NO2 NAAQS for 1-hour NO2 Standard
Published in FR on February 9, 2010 Added a 1-hour form of the standard to the
existing annual standard effective on April 12, 2010
NO2 standard is 3-year average of 98th percentile of annual distribution of daily maximum 1-hour concentrations
Interim 1-hr NO2 Significant Impact Level (SIL) issued in EPA Guidance June 2010 – 4 ppb (7.5 µg/m3)
Revised NO2 NAAQS - Implications
New NO2 monitors, likely near major roadways in urban areas To be operational by January 2013
New 1-hour standard problematic for sources required to model compliance with NAAQS Petition filed on April 12, 2010 by UARG and
API for reconsideration and stay of the NAAQS
“Industrial Sprawl”
New SO2 NAAQS for 1-hour SO2 Standard
Published in FR on June 22, 2010 Added a 1-hour form of the standard effective
on August 23, 2010 Revoked both annual and 24-hour standards SO2 standard is 3-year average of 99th
percentile of annual distribution of daily maximum 1-hour concentrations
Interim 1-hr SO2 Significant Impact Level (SIL) issued in EPA Guidance August 2010 – 3 ppb (7.8 µg/m3)
Revised SO2 NAAQS - Implications Nonattainment areas will be defined
based on BOTH monitoring and modeling New near source monitoring required by
January 2013 New 1-hour standard problematic for
sources required to model compliance with NAAQS
Modeling assessments for facilities found to be potentially contributing to monitoring exceedances
“Industrial Sprawl”
Case Study #1 – Site Location Assistance for a
New Greenfield Site
Case Study #1 – Background (1 of 2)
Client interested in siting a new greenfield manufacturing site
Facility will be a large source of NO2 and SO2 emissions Client education needed regarding new 1-hr
NAAQS Assessments recommended to evaluate
source impacts related to new 1-hr NAAQS
Original assessment indicated site impacts well below the new 1-hr NAAQS
Case Study #1 – Background (2 of 2)
Client provided new facility site layout Updated models incorporating new facility
layout indicated 1-hr NO2 and SO2 values had nearly doubled from initial estimates
Close review of model input files could find no errors – same meteorological data, receptor grid, emission units, buildings, etc.
What happened?
Building/Downwash Influences?
Two Different Site Orientations With Different Results (1 of 2)
Two Different Site Orientations With Different Results – No Buildings (2 of 2)
Plume Visualization (1 of 3)
Plume Visualization (2 of 3)
Plume Visualization (3 of 3)
What Does All This Mean? (1 of 2)
Greenfield Sites Site orientation could have a significant
impact on 1-hr modeling results Could site layout/orientation be revised to
improve modeling results Existing Sites
Review existing site layout – can have a significant impact on 1-hr modeling results
What Does All This Mean? (2 of 2) Items “commonly” considered when
looking for modeling result improvements Stack height Stack diameter Stack flow/velocity Stack temperature Distance of source to the facility fence
line New additional issues to focus on
Building setup/orientation Meteorological data
Case Study #2 – Existing Facility Considering a PSD
Project
Case Study #2 – Background Client interested in modifying several
facility combustion units Due to new regulatory applicability, etc.
looking at possibility of PSD avoidance through installation of emission controls
Assessments recommended to evaluate off-site source impacts related to new 1-hr NAAQS
The problem came with off-site sources of NO2
Off-Site Only Impacts Due to 1-hr NO2
Cause or Contribute AnalysesWind from Southwest Wind from Southeast
What Does All This Mean? Greenfield Sites
Review of the proximity of large off-site sources of 1-hr NO2 and SO2 a must as part of site selection process
Existing Sites Prior to consideration of a large project,
review existing site impacts and off-site impacts (if known) in comparison to the 1-hr NAAQS
Even with the inherent “difficulty” in pairing violations in time and space, can still cause issues given the proper source/wind alignment
Accuracy of modeling inventories more critical
Going Forward
Reduction in Receptor Grid
Discussed in EPA 3/1/11 memo Reduction in receptors to only those receptors
which exceed the 1-hr NAAQS interim SIL Solves one portion of the “temporal and
spatial” test for cause and contribute analyses
Can be helpful in assessment of source contributions to the new 1-hr NAAQS Reduction in number of receptors necessary
to evaluate culpability for modeled violations MAXDCONT processing requirements
Limitations in Hourly Emissions
“Emergency” Units discussed in EPA 3/1/11 memo
Hour of day function in AERMOD model Worst case modeling impacts, due to
meteorological conditions, can occur during non-daylight hours for fugitive or low dispersion point sources
Restricting emissions to daylight hours, or equipment “testing” to certain hours, can show modeled improvements
Including “Inventory Problem Source” Site Specific Information
Inclusion of facility fenceline? Inclusion of facility buildings and
downwash influences? Actual emission point locations? Review of problem source permit
documentation essential
Additional Possible Strategies Consideration of background?
Use of higher background in place of modeled sources?
Selection of background value sources? Additional guidance regarding the “need”
for modeling for the 1-hr NAAQS? Has there been an actual/potential hourly
emissions increase? Offsets – “net air quality benefit” Modeling actual vs. potential emissions
Conclusions When assessing the new 1-hr NAAQS for
NO2 and SO2, there are additional items to consider that may not have been considered before
The new 1-hr NAAQS can play an integral role in project planning
Cooperation and sharing of ideas/solutions will be beneficial to all
We need to consider thinking “outside the box” for solutions to our current modeling difficulties
Contact Information
Justin Fickas53 Perimeter Center EastSuite 230Atlanta, GA 30346Office: (678) 441-9977Cell: (678) 549-9755Fax: (678) 441-9978http://www.trinityconsultants.com/atlanta/jfickas@trinityconsultants.com
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