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SO 2 Designation Guidance. Ian D. Cohen EPA Region 1 617-918-1655. Revision to SO 2 Standard – Adopted June 2, 2010. EPA replaced the existing annual and 24-hour primary SO 2 standards with a new 1-hour SO 2 standard set at 75 parts per billion (ppb).
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SO2 Designation Guidance Ian D. Cohen EPA Region 1 617-918-1655 U.S. Environmental Protection Agency
Revision to SO2 Standard –Adopted June 2, 2010 EPA replaced the existing annual and 24-hour primary SO2 standards with a new 1-hour SO2 standard set at 75 parts per billion (ppb). EPA also described our planned hybrid approach for implementing the new 1-hour SO2 standard. The approach would rely on air dispersion modeling of SO2 sources and ambient monitoring to determine compliance with the new standard.
Structure of the Memo • Body of Memo: What is a Nonattainment Area? • Attachment 1: Schedule • Attachment 2: Factors to be used in specifying a nonattainment area • Attachment 3: Modeling guidance U.S. Environmental Protection Agency
SO2 Implementation Schedule * See www.epa.gov/nsr/documents/20100823guidance.pdf ** See www.epa.gov/air/sulfurdioxide/pdfs/20110324so2designationsguidance.pdf
Designation Guidance for SO2 NAAQS • Modeling and boundary guidance to support initial designations released to states/tribes on March 24, 2011. • Designations driven by modeling rather than monitoring. • States given option to be initially designated as attainment if modeling results support an attainment designation. • No unclassifiable/attainment but rather: attainment, nonattainment, unclassifiable. U.S. Environmental Protection Agency
Identifying Nonattainment Areas • Identify through monitoring and modeling appropriate areas violating the NAAQS • Approx. 59 counties will be designated as “nonattainment.” • Determining Boundaries • Should contain areas violating NAAQS, as well as nearby areas which contain sources U.S. Environmental Protection Agency
Nonattainment Area Boundaries • First approximation: County • Adjusted by other factors, including • Air quality data • Emissions-related data • Meteorology • Geography/topography • Jurisdictional boundaries U.S. Environmental Protection Agency
Where SO2 differs from all other NAAQS designations • States are not required to model for initial designation purposes. • Thus, we expect most of country to be designated “unclassifiable.” • Unclassifiable areas have substantial sec. 110(a)(1) SIP requirements, unlike other NAAQS with same designation. • Must submit by June 3, 2013, a SIP demonstrating an adequate program to implement, maintain, and enforce the SO2 NAAQS
Modeling Guidance • Model Selection • Domain/Sources • Receptor Grid • Allowables/Actuals • Stack Height • Configuration • Urban/Rural • Source Groups • NWS Met Data • Site Specific Data • Background • Design Values U.S. Environmental Protection Agency
Link to SO2 Guidance: Guidance can also be accessed from TTN SCRAM Bulletin Board and from the Sulfur Dioxide Webpage http://www.epa.gov/air/sulfurdioxide/pdfs/20110324so2designationsguidance.pdf U.S. Environmental Protection Agency
Questions U.S. Environmental Protection Agency