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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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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 • 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 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 • 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 • 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 • 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 • 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