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SO2 1 -Hour NAAQS. Modeling VS Modeling. Rule Chronology. Proposed December 9, 2009 Adopted June 22, 2010 States Designation Recommendation due: June 3, 2011 EPA Final Designation set for June 3, 2012. Proposed Rule Preamble.

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Presentation Transcript
So2 1 hour naaqs

SO2 1-Hour NAAQS

Modeling VS Modeling


Rule chronology
Rule Chronology

  • Proposed December 9, 2009

  • Adopted June 22, 2010

  • States Designation Recommendation due: June 3, 2011

  • EPA Final Designation set for June 3, 2012


Proposed rule preamble
Proposed Rule Preamble

  • Devoted 9 pages in Section III of Preamble to Monitoring Requirements

  • Section III specifically states: “Ambient SO2 monitoring data are used to determine whether an area is in violation of the SO2 NAAQS”

  • Preamble does not mention Modeling


Preamble solicited comments
Preamble Solicited Comments

  • Preamble in proposed rule has many areas where EPA specifically solicited comments, e.g.

    • Requirement for state and local agencies to report both hourly and 5-minute averages

    • Levels as high as 150 ppb

  • EPA did not seek comment on Modeling trumping Monitoring

  • No hint, EPA was considering a Policy that Modeling would be preferential to Monitoring


Final rule
Final Rule

  • 50.17 a) sets standard at 75 ppb

  • 50.17 b) the 1-hour standard is met at an ambient air quality monitoring sitewhen the 3-year average of the annual (99th percentile) of the daily maximum 1-hour average concentrations is less than or equal to 75 ppb, as determined in accordance with Appendix T

  • Appendix T identifies data handling for monitoring data

  • No mention of Modeling


State s concerns
State’s Concerns

  • Guidance stipulating that modeling trumps monitoring is unprecedented and sets a new direction

  • Guidance has not been vetted through public review

  • Guidance selects AERMOD as model of choice

    • Concerns that AERMOD is overly conservative

    • Other Models e.g. Calpuff may be better suited

  • Guidance Requires Maximum Emission Rates

    • Most Sources operate well below maximum rates

    • Ignores CEM data that is available

  • Guidance Ignores Ambient Monitoring unless it shows violation


Designation schedule
Designation Schedule

  • State’s must submit Designation Recommendations NLT June 3, 2011

  • EPA Notifies States by February 3, 2012 concerning any intended modifications to State’s Recommendation

  • Comment Period ends March 20, 2012

  • State’s Respond by April 3, 2012

    • Insufficient time to conduct modeling

  • EPA Promulgates Designation NLT June 3, 2012


Chronology
Chronology

  • June 22, 2010 Rule Promulgated

  • August 2010 ND and others Petitioned EPA to Reconsider

  • January 18, 2011 EPA denies Petition

  • March 30, 2011 Court issued order consolidating Petitions for Review

  • April 28, 2011 Filing Deadline – Statement of Issues

  • May 12, 2011 Briefing Schedule Deadline


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