John Egan of ALL4 Inc. explains the National Ambient Air Quality Standards (NAAQS) 1-Hour Standard for SO2. This presentation also includes implementation updates, experiences, impacts of permitting, and what we at ALL4 think is next!
3. NAAQS Background
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“Backdrop” of the Clean Air Act
States design their SIPs and implement enforce
their regulations to meet the NAAQS
Air quality construction permit programs are
designed around NAAQS compliance
• PSD: Maintaining NAAQS attainment
• NNSR: Getting into NAAQS attainment
NAAQS reevaluated every 5 years
5. SO2 NAAQS Implementation
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NAAQS Implementation Schedule:
• June 2011: Initial state nonattainment
recommendations to U.S. EPA (most counties were
“unclassifiable”)
• June 2012: EPA to finalize attainment status (most
states will still be “unclassifiable” or attainment)
• June 2013: Maintenance SIP submittals including
individual facility modeling to achieve compliance
with the NAAQS
• August 2017: Full NAAQS compliance in all areas
6. Implementation Update
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Draft guidance for states to evaluate
designations using AERMOD air dispersion
model was released on September 22, 2011
Numerous comments received on draft guidance
On April 12, 2012, U.S. EPA issued a letter to all
states stating that modeling demonstrations
showing attainment of the standard for areas
initially designated “unclassifiable” will no longer
be required for the June 2013 SIP submittals
7. Implementation Update
U.S. EPA now proposing “Stakeholder
Outreach” in order to discuss a workable
approach for implementation of the new
standard including:
• How best to assess compliance with standard
• How to implement new approach
U.S. EPA recommending that states focus 2013
SIP submittals on traditional CAA infrastructure
elements
http://www.epa.gov/airquality/sulfurdioxide/implement.html
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8. Implementation Experiences
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Air dispersion modeling scramble:
• States requested data and/or modeling
• States conducting modeling
• Facilities reevaluating data and resources
• Facilities conducting exploratory modeling
Troubling results…
9. Air Quality Modeling Steps
1. Emission Inventory
2. Meteorological Data
(AERMET/AERSURFACE)
3. Terrain Data (AERMAP)
4. Building Downwash (BPIPPRM)
5. Run model (AERMOD)
6. Assess results
7. Strategic planning
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10. Full NAAQS Evaluation
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Includes facility and other local facilities
Modeled emission rates need to be considered
as possible 1-hour permit limits
Considerations for accounting for emissions
during startup and shutdown
Emergency unit considerations
Includes background
12. Troubling Results
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Use of PTE emissions and AERMOD can over
estimate concentrations
Known issues with certain terrain and
meteorological conditions
Sensitivity of the model to very site-specific
parameters (angle of buildings, distance to
property lines, etc.)
Consideration of ambient SO2 monitoring to
compare to AERMOD results
13. Ambient SO2 Monitoring
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Pros:
• Monitoring data could be used to discount air
quality modeling results
• Potentially avoid need for permit limits,
pollution controls, fuel restrictions, or worse…
Cons:
• Collection of monitoring data above the SO2
NAAQS
• Time and cost
14. NAAQS Impacts on Permitting
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Major projects that trigger PSD require
demonstration of compliance with PSD
increments and NAAQS:
• Initial evaluation of project impacts vs.
significant impact level (SIL)
• Full NAAQS evaluation if SIL exceeded
• Like short-term NAAQS, SILs are extremely
low
15. NAAQS Impacts on Permitting
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Full NAAQS evaluation under PSD no different
than under SO2 implementation
Supports value of exploratory modeling for
strategic planning
16. What Next
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Primary NAAQS are health-based and not
likely to increase
Stakeholder Outreach to still consider
modeling – get involved in process
Projects triggering major NSR air permitting
can still require modeling
17. What Next
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Strategic planning for future growth and
compliance should consider:
• Exploratory dispersion modeling
• Emissions reduction options
• Ambient SO2 and meteorological
monitoring
• Alternative permitting approaches - PALs
Originally the Council reached out to me to talk about the short term NAAQS implementation, modeling and monitoring. However, given EPA’s recent shift in how they see, or don’t see the 1-hr SO2 implementation process happening, we agreed that it was more important to focus on how the process has played out so far and what to expect next.
2006 EPA revised primary PM2.5 standard.February 9, 2010 EPA revised primary NO2 standard.June 2, 2010 EPA revised primary SO2 standard.March 20, 2012 EPA took final action to retain Secondary NO2 and SO2 standards.
When new 1-hr standard was published and the air quality modeling was included as part of the attainment designation and demonstration process EPA acknowledged that additional guidance beyond what was included in Appendix W was needed. Draft guidance September 2011.As late as Annual EPA modeling conference in mid-March this year EPA indicated final guidance not available before end of year.Surprise came mid-April when EPA changed its mind…
Three stakeholder meetings are now scheduled for late May/early June. Industry group session will be June 1 in RTP. Ink to website gives contact name and phone number if interested.
Lets talk about what’s been happening over the past year:Some states moving forward requesting info, some actually doing modeling with data in hand.Facilities trying to compile appropriate info and considering and/or conducting “exploratory” modeling.Issues cropping up everywhere thanks to the stringency and form of the standard.
Look at what goes into and comes out of the modeling exercise and consider all the areas where issues can and have occurred:
Then there are confounding additional considerations that can add to the difficulty in modeling attainment:
So what happens when the results come back and the initial numbers are problematic: Emission rates – new limits, change fuels/raw materials, add controlsReconfigure exhaustsLimit access, move fence to property lines, acquire property?Work with model or consider alternative to AERMOD
What have we seen:
May not be out of the question if backed into a corner.
If EPA no longer requiring AQM for state 2013 SIP submittals why are we even bothering to talk about the 1-hr SO2 issues?