1-hour so2 national ambient air quality standards (naaqs) implementation – what’s next?

1-Hour SO2 NAAQS Implementation – What’s

Next?John P. Egan

NCASI 2012 Northern Regional MeetingPortland, ME

May 10, 2012

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Agenda Quick NAAQS Review NAAQS Implementation Updates NAAQS Implementation

Experiences NAAQS Impacts on Permitting What’s Next?

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NAAQS Background “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

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NAAQS SummaryPollutant

Averaging Period

Primary/Secondary

Historic NAAQS (µg/m3)

Revised NAAQS (µg/m3)

CO1-Hour Primary 40,000 40,0008-Hour Primary 10,000 10,000

Ozone 8-HourPrimary/

Secondary75 ppb Withdrawn

Pb3-Month Rolling

Primary/Secondary

1.5 0.15

PM10 24-HourPrimary/

Secondary150 150

PM2.5

24-HourPrimary/

Secondary65 35

AnnualPrimary/

Secondary15 15

NO2

1-Hour Primary N/A 188

AnnualPrimary/

Secondary100 100

SO2

1-Hour Primary N/A 1963-Hour Secondary 1,300 1,300

24-hour Primary 365 Revoked

AnnualPrimary/

Secondary80 Revoked

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SO2 NAAQS Implementation 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

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Implementation Update Draft guidance for states to evaluate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Numerous comments received on draft guidance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

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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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Implementation Experiences

Air dispersion modeling scramble:• States requested data and/or modeling• States conducting modeling• Facilities reevaluating data and

resources• Facilities conducting exploratory

modeling Troubling results…

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Air Quality Modeling Steps

1. Emission Inventory2. Meteorological Data

(AERMET/AERSURFACE)3. Terrain Data (AERMAP)4. Building Downwash (BPIPPRM)5. Run model (AERMOD)6. Assess results7. Strategic planning

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Full NAAQS Evaluation 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

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Assessing Modeled Results Emission Rate Strategies Stack/Exhaust Strategies Facility Fence Line Strategies Modeling Strategies

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Troubling Results 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

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Ambient SO2 Monitoring 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

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NAAQS Impacts on Permitting

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

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NAAQS Impacts on Permitting

Full NAAQS evaluation under PSD no different than under SO2 implementation

Supports value of exploratory modeling for strategic planning

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What Next 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

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What Next Strategic planning for future growth and

compliance should consider:• Exploratory dispersion modeling• Emissions reduction options• Ambient SO2 and meteorological

monitoring• Alternative permitting approaches -

PALs

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Questions?

John Eganjegan@all4inc.com(610) 933-5246 x14

2393 Kimberton RoadPO Box 299

Kimberton, PA 19442

All4 Inc.www.all4inc.com

www.enviroreview.com