Regulatory Requirements For Modeling

Air Quality Model Estimates Developing Air Pollution Control Plans Assessment of Environmental Impacts Projecting Future Air Quality Trends

Regulatory Requirements for Modeling FIP/SIP/TIP NSR Control Strategy PSD EA/EIS

Air Quality Modeling Set of Mathematical Equations Logically connect Emission Rate (Q) to Ambient Air Quality Concentration (  ) Monitoring Site – Representative location chosen for sampling Receptor Site – Model prediction of pollutant concentration

Need for Air Quality Model Limitations in Spatial and Temporal Coverage Insufficient Monitoring Data to set Emission Limits Analyze the impacts of new sources that do not yet exist Diversity dictate against modeling “Cookbook”

Suitability of Models Meteorological & Topography Level of Detail & Accuracy Technical Competence Resource Availability Accurate Data

7 Source : EPA DREP

Levels of Models Screening Model- Simple estimation provides conservative estimates Refined Model- More refined least theoretical results Screening Technique followed by Refined Model Identify “appropriate reviewing authority”

Prevention of Significant Deterioration PSD- 40 CFR § New Major Stationary Source and Major Modification to Existing Source – Ensure compliance with NAAQS and PSD air increments Preconstruction Permit Application – Best Available Control Technology (“BACT”) – Ambient Air Quality Impact Analysis: Modeling – Impacts on Soils, Vegetation, and Visibility – Class 1 Area Impacts – Public Comments/Participation

Air Quality Monitoring Requirements 40 CFR § 52.21(i)(5) PSD De Minimis Monitoring Concentration PollutantAvg.PeriodThreshold Concentration (ug/m3) CO8-hour575 NO2Annual14 PM1024-hour13 SO224-hour13 O3NA Lead3-month0.1 Fluorides24-hour0.25 Total Reduced Sulfur 1-hour10 H2S1-hour0.2 Reduced Sulfur1-hour10

Air Quality Impact Analysis (AQIA) 40 CFR § 52.21(m) AQIA shall be based on Guidelines on Air Quality Models – 40 CFR § 51 Appendix W PSD Increments (ug/m3) PollutantClass IClass IIClass III Particulate Matter PM10, annual PM10, 24-hour Sulfur Dioxide SO2, Annual SO2, 24-hour SO2, 3-hour Nitrogen Dioxide NO2, Annual

Additional Impact & PSD Class 1 Analysis Growth – industrial, residential, commercial Soil and Vegetation Impacts – harmful effects to resident species Visibility Impairment – local visibility impairment PSD Class I Areas Notice to Federal Land Managers (FLM) Air Quality Related Values (“AQRV”)-FLAG Contribution to regional haze, acid deposition

New Source Review (NSR) Tribal Minor NSR 40 CFR § Reviewing Authority Trigger AQIA – local air quality condition – minor source or modification would cause or contribute to a NAAQS or PSD increment violation – conduct the AQIA using the dispersion models and procedures of part 51, Appendix W – AQIA cause or contribute to a NAAQS or PSD Reduce or mitigate impact Non-Attainment NSR (“NANSR”)

Federal/State/Tribal Implementation Plan Designation NAAQS Implementation Schedules Emission Inventories Attainment Demonstrations Strategies and Technology to Reduce Emissions NSR and PSD Regional Haze

Modeling Guidance Resources permit.htm permit.htm 40 CFR Part 51 Appendix W Air Quality Analysis Checklist Guideline for Determination of Good Engineering Practice Stack Height Regional/State/Local Modelers Workshop