Air Quality Modeling Guidance for Permits

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Current air quality permit modeling guidance for estimating impacts from stationary sources of air pollution.

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    General Permitting Questions

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    Colorado Modeling Guidance for Air Quality Permits

    • Colorado Modeling Guideline for Air Quality Permits (May 2022)
    • Meteorological Determinations and Application of Dispersion Models 
    • Modeling Determinations.
      • If an applicant is unsure if modeling will be required to conduct a required NAAQS analysis, the APCD-114 Form should be filled out to obtain a decision prior to submitting a permit application or a modeling demonstration to the Air Pollution Control Division (APCD). Form Instructions are provided here.
      • Once a determination is made, the applicant will be provided documentation of the Modeling Determination by APCD. The APCD-114 Form and Determination will be part of the source or modification's permit application record. If a determination of "Modeling Required" is made, the applicant must submit a modeling analysis demonstrating compliance with the NAAQS with the permit application. If a determination of “Modeling Not Required” is made, the completed APCD-114 Form and Determination will be included as part of the source or modification’s permit application record and no further analysis will be required.
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    Supplemental Modeling Guidance, Forms, and Information

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    Meteorological & Geophysical Data for Air Quality Permit Modeling

    • The Technical Services Program of the Air Pollution Control Division has data from current and historic meteorological towers in Colorado that are suitable for use in regulatory models. Contact the Division at cdphe_apcd_modeling_files@state.co.us for data. Division approval should be obtained on a case-by-case basis before meteorological datasets are used for regulatory (e.g., air permit) modeling.
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    Federal Modeling Support