Proposed Revisions to the Guideline on Air Quality Models Dan Jamieson Air Permits Division Texas Commission on Environmental Quality Advanced Air Permitting Seminar 2015

Guideline What is the Guideline? Why have it? EPA-preferred models Recommended techniques Why have it? Common basis and consistency EPA – Environmental Protection Agency

Guideline Where is the Guideline? Timeline: Published as Appendix W to 40 CFR Part 51 As a result, changes follow rulemaking process Timeline: Comment period Final rule package CFR – Title 40 Code of Federal Regulations Appendix W can be found at http://www.ecfr.gov/cgi-bin/text-idx?SID=4eeba4c5c08aad04511382328c77c8f1&mc=true&node=ap40.2.51_11205.w&rgn=div9.

Proposed Revisions Two basic types: Substantive changes to address various topics Editorial changes to update and reorganize information

Proposed Revisions NO2 and tiered approach: Tiered approach is not new Current Guideline addresses annual standard Clarification memos and 1-hour standard Proposed Guideline addresses both standards NO2 – nitrogen dioxide

Proposed Revisions Tier 1: 100 percent conversion Tier 2: replace existing ARM with ARM2 - Based on hourly data of NO2 to NOx ratios Empirically derived equation in AERMOD Default minimum ratio of 0.5 and maximum ratio of 0.9 ARM – Ambient Ratio Method NOX – oxides of nitrogen AERMOD – American Meteorological Society/EPA Regulatory Model

Proposed Revisions Tier 2 (cont.) - Sept. 2014 clarification memo includes minimum ratio of 0.2 Guideline provides flexibility on minimum ratio Impact?? Use of existing ARM Equation coded in AERMOD The September 2014 clarification memo can be found at http://www3.epa.gov/ttn/scram/guidance/clarification/NO2_Clarification_Memo-20140930.pdf.

Proposed Revisions Tier 3: OLM and PVMRM included in regulatory default version of AERMOD - No longer alternative models Still need to coordinate with us on model inputs Revised PVMRM – PVMRM2 OLM – Ozone Limiting Method PVMRM – Plume Volume Molar Ratio Method

Proposed Revisions Ozone and secondary PM2.5: Difficult to do Currently, no preferred model for single- source assessment Still no preferred model proposed, but EPA is recommending two-tier approach PM2.5 – particulate matter with a diameter of 2.5 microns or less O3 – ozone Photo located at https://www.flickr.com/photos/vogoa/2416829478/in/photolist-pAKcLD-w5qyb9-abxGTr-9xJoRa-9xJxxn-o8r8T9-nR3SKZ-5z2831-5DCYrh-4NsdvJ-gZWzSU-4FyTcL-9KCBSV-aRvDuR-j2hcXD-5Cf44u-B5t8H-9xJ8ED-b7ysB2-o8p4bQ-b7ysQR-aECUph-m1xPD9-9xMvR3-abxHAz-abxGCP-oaiAmz-o8r81h-o8p5oj-nR2Q4G-9xMvY9-9XhTu-abxHo6-abxH8K-nR2Pdo-nR2MYQ-oaiyXn-nR3RTZ-nR3bfm-oaizyx-nR32rF-nR3Pd8-nR2MvA-o8wnhr-nR3QuM-nR3QPp-o6tZ9W-o8e3fP-w2riJU-5G8nnq Photo by Ulrich Thumult. License can be found at https://creativecommons.org/licenses/by-nc-sa/2.0/legalcode. Bottom of photo cropped to show portion of skyline and focus on smog.

Proposed Revisions First tier: relationship between precursor emissions and source impact - Peer-reviewed literature Previous modeling results Reduced-form model

Proposed Revisions Second tier: conduct photochemical grid modeling - New draft guidance Consult with us early

Proposed Revisions EPA to pursue rulemaking to establish SILs for PM2.5 and ozone Also to introduce new tool – MERP: If emissions < MERP – not expected to contribute significantly SILs – Significant Impact Levels MERP – Modeled Emissions Rates for Precursors

Proposed Revisions CALPUFF and Class I Increment: CALPUFF preferred for long-range transport Proposal to no longer have preferred model: More flexibility Available tools Management of code CALPUFF – California Puff model

Proposed Revisions Proposed screening approach Near-field application of preferred model at 50 kilometers: If results < SILs – done If results > SILs – further analysis

Proposed Revisions For further analysis, no preferred model For single-source or cumulative modeling – consult with us and EPA early

Proposed Revisions EPA’s Model Clearinghouse: Coordination between EPA/Regional Offices Helps resolve issues not in Guideline Helps with considerations of alternative models

Proposed Revisions Proposing that Regional Offices consult with Model Clearinghouse on use of alternative models: Formal concurrence memo Impact?? Permit review time

Proposed Revisions Procedures – cumulative analysis: Proposed changes for model inputs and background concentrations Based on clarification memos issued since 2010 (new standards) Photo located at https://www.flickr.com/photos/21550937@N03/5518927574/in/photolist-9pFWTG-9pFVRh-ahYjMS-ahYcSC-ahVf8t-ahVAka-ahY6aU-ahYbSy-ahVrTK-ahVqBc-faVnGJ-faF7mr-faVnA9-faF6Pi-faF7bi-faVnrE-faF6tX-faF6x2-5bSYyi-4tkmTD-4tkjCD-buFRXG-4tppbN-4tpoAb-4tkj2X-nmDzUu-7n86tJ-daiZ24-3xtd9M-o6a9Mv-o7WdX6-BP4ZD-48k1qL-bkbwoV-bkbwLR-bX49ZN-aefeiy-c6divm-aecq4e-aecqSx-2uYy9-485Qzk-aK5fTg-ahYdUu-ahYciW-ahVgQD-ahVBKv-ahVhPH-ahVsdi-ahVuR6-ahVibX Photo by Roy Luck. License can be found at https://creativecommons.org/licenses/by/2.0/legalcode. Bottom and top of photo cropped slightly.

Proposed Revisions Emissions input data (Table 8-2): New/modified source – allowable emissions Nearby source – can use actual emissions data Other source – represented by monitoring data

Proposed Revisions Nearby source: in vicinity of source under consideration - Explicitly model Other source: all other sources - Accounted for by monitoring data

Proposed Revisions Identifying sources – isolated single-source vs. multi-source area: Isolated: focus on other sources and use of background monitoring data Multi-source: focus on determining nearby sources and background monitoring data for other sources

Proposed Revisions Proposing definition of modeling domain: Geographic area for analysis Includes all location of significant impacts Area extending to most distant significant impact or 50 kilometers

Proposed Revisions Meteorological input data: Recommending use of AERMINUTE: Processor for 1-minute ASOS wind data Reduces calm and missing hours We use it in our processing AERMINUTE – a meteorological pre-processor used to process 1-minute wind data for use with AERMET, the meteorological pre-processor for the AERMOD modeling system ASOS – Automated Surface Observing Stations

Proposed Revisions Proposing option to use prognostic meteorological data: No NWS station or collecting on-site data is prohibitive/infeasible MMIF – tool to convert data for use in AERMET Coordinate with us early in the process NWS – National Weather Service MMIF – Mesoscale Model Interface program AERMET – the meteorological pre-processor for the AERMOD modeling system

Proposed Revisions AERMOD modeling system: New version (15181) as part of proposal Updates subject to public review and comment Current non-default/beta options proposed to be part of regulatory default option

Proposed Revisions Proposed updates: U-star in AERMET LOWWIND3 in AERMOD Horizontal/capped stacks Buoyant line source option Code for proposed NO2 Other enhancements/bug fixes U-star – represents the surface friction velocity LOWWIND3 – represents a proposed model keyword for use with AERMOD

Summary EPA proposing a number of revisions to the Guideline We are looking at how they could affect us: Revisions to our modeling guidance? Pre-processed meteorological data sets?

Contact Information Dan Jamieson - Air Dispersion Modeling Team (512) 239-4342 daniel.jamieson@tceq.texas.gov

Questions?