1. N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION Short Term Ambient Air Quality Standards and The Effect on Permitting Margaret Valis NESCAUM, Stationary Sources & Permits Committee April 4, 2013

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3. “New” 1-hour Standards 1-hr NO2 added Feb 2010, 1-hr SO2 added Jun 2010 Form of the standards: – for NO2 – 98 th percentile daily max averaged over 3 years (8 th Highest) – For SO2 – 99 th percentile daily max averaged over 3 years (4 th Highest) N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION

4. How do these new standards effect permitting? Air Quality Modeling Required to Ensure Acceptable Air Quality Major New Source Review: Prevention of Significant Deterioration (PSD) & Nonattainment review --per Part 231. On federal side: 40CFR, Part 52.21 and 51.165,plus Appendix S (emission offset interpretive ruling), respectively. Modeling used to demonstrate: 1) NAAQS compliance, PSD increment consumption, protection of visibility and other Air Quality Related Values in Class I areas, and support request for monitoring waivers in attainment areas. 2) Insignificant impacts and net air quality benefits for nonattainment areas (cause or contribute test per Section 51.165(b)(2)). 3) Minor source consumption of PSD increment: Section 2.166(b)(13)(ii)(b). State Implementation Plan: Section 172(c) of the Act requires modeling of NAAQS compliance demonstration for nonattainment areas. Some specific regulations require modeling support (e.g. regional haze). Subpart 200.6: acceptable ambient air quality for sources alone or cumulatively. N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION

5. Regulatory Recommended Approaches Modeling Requirements per Section 320 of CAA. Calls for national conferences every three years to develop “standardized” models and procedures. Since 1977, modeling has evolved into a primary analytical tool in air quality assessments for permitting and rulemaking. 10 th Conference held in February 2012. Discussed challenges of modeling for the new 1-hr standards. N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION

6. Modeling Guidance Appendix W of 40 CFR part 51: EPA Guideline on Air Quality Models, Revised, November 9, 2005. http://www.epa.gov/scram001/guidance_permit.htm http://www.epa.gov/scram001/guidance_permit.htm DEC Program Policy DAR-10: NYSDEC Guidelines on Dispersion Modeling Procedures for Air Quality Impact Analysis, May 9, 2006. http://www.dec.ny.gov/chemical/8923.html http://www.dec.ny.gov/chemical/8923.html N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION

7. Recent NO2/SO2 PSD Modeling Guidance Applicability of Appendix W Modeling Guidance for the 1-hour NO2 National Ambient Air Quality Standard, June 28, 2010 – http://www.epa.gov/ttn/scram/ClarificationMemo_AppendixW_Ho urly-NO2-NAAQS_FINAL_06-28-2010.pdf http://www.epa.gov/ttn/scram/ClarificationMemo_AppendixW_Ho urly-NO2-NAAQS_FINAL_06-28-2010.pdf Applicability of Appendix W Modeling Guidance for the 1-hour SO2 National Ambient Air Quality Standard, August 23, 2010 – http://www.epa.gov/ttn/scram/ClarificationMemo_AppendixW_Ho urly-SO2-NAAQS_FINAL_08-23-2010.pdf http://www.epa.gov/ttn/scram/ClarificationMemo_AppendixW_Ho urly-SO2-NAAQS_FINAL_08-23-2010.pdf Additional Clarification Regarding Application of Appendix W Modeling Guidance for the 1-hour NO2 National Ambient Air Quality Standard, March 1, 2011– http://www.epa.gov/ttn/scram/Additional_Clarifications_Appendix W_Hourly-NO2-NAAQS_FINAL_03-01-2011.pdf http://www.epa.gov/ttn/scram/Additional_Clarifications_Appendix W_Hourly-NO2-NAAQS_FINAL_03-01-2011.pdf N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION

8. Modeling Guidance for 1-hr NO2 Standard is 100 ppb (188 ug/m3) based on 3-year average of the 98th percentile of daily maximum 1- hour concentrations Monitored design values (see Appendix S to 40 CFR Part 50) are based on 3-year averages Monitoring guidance does not preempt or alter Appendix W requirement for use of 5 years of National Weather Service (NWS) meteorological data or at least 1 year of site-specific data N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION

9. Modeling Guidance for NO2 Clarification memo on applicability of Appendix W guidance for new 1- hour NAAQS issued in June 2010 – AERMOD is the preferred model for estimating NO2 impacts in near-field applications (out to 50 km) – Interim SIL of 4 ppb (7.5 ug/m3) – Three-tiered screening approach in Section 5.2.4 is generally applicable for 1-hour NO2 modeling, with additional/different considerations: Tier 1 assumes full conversion of NO to NO2; Tier 2 applies ambient ratio to Tier 1 result (newest guidance assumes a short-term default ratio = 0.80); Tier 3 “detailed screening methods” on a case-by-case basis, including OLM (ozone limiting method) and PVMRM (plume volume molar ratio method) options implemented in AERMOD N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION

10. Modeling Guidance for SO2 Standard is 75 ppb (196 ug/m3)based on 3-year average of the 99th percentile of daily maximum 1-hour concentrations Clarification memo on applicability of Appendix W guidance for new 1-hour NAAQS issued in August 2010 – The current guidance in Appendix W regarding SO2 modeling in the context of the previous 24-hour and annual primary SO2 NAAQS and the 3-hour secondary SO2 NAAQS is generally applicable to the new 1-hour SO2 standard. – AERMOD is the preferred model for estimating SO2 impacts in near-field applications (out to 50 km) – Interim SIL of 3 ppb (7.8 ug/m3) N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION

11. Modeling Guidance for NO2 & SO2 Additional guidance issued March 1, 2011 – Clarifies procedures for analyzing results given form of NAAQS – For NO2, recommends default 1-hour Tier 2 ambient ratio of 0.80, and default in-stack NO2/NOx ratio for OLM and PVMRM Tier 3 options of 0.50, in the absence of more appropriate information – Addresses treatment of intermittent emissions (e.g., emergency generators) in PSD modeling demonstrations, a key issue with implementation of the new 1-hour NAAQS – Discussion/recommendations regarding nearby background sources to include in modeling and combining modeled+monitored contributions for cumulative analysis N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION

12. Notes N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION Background concentrations may be refined. Seasonal and diurnally varying values can be pulled from the hourly monitored data following the procedures outlined in EPA’s 3/1/2011 Clarification memo. Permit conditions may be required to restrict operation of emergency/ancillary equipment

13. Other Modeling Issues N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION Draft EPA guidance on permit modeling for PM2.5 was released March 4, 2013. Comments to EPA by May 31. – Secondary formation, emissions inventory, background concentrations… 1-hr SO2 Modeling for Attainment Designations and the SIP – EPA will not rely only on monitored data to assess whether areas are in attainment of the 1-hr SO2 NAAQS. Modeling of existing sources will be required by the states – awaiting guidance from EPA.

14. Thank You! Contact Information: Margaret Valis Chief, Impact Assessment and Meteorology Division of Air Resources 625 Broadway Albany, NY 12233-3254 mxvalis@gw.dec.state.ny.us (518)402-8403 N EW Y ORK S TATE D EPARTMENT OF E NVIRONMENTAL C ONSERVATION