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Air Quality Modeling Guidance for Permits

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

    General Permitting Questions

    Colorado Modeling Guidance for Air Quality Permits

    • NEW: Colorado Minor NSR Source Modeling Guideline for Air Quality Permits (May 2023)
    • Call to Action for Outstanding Applications
    • Permit Modeling Unit (PMU) Determinations.
      • Traditional Construction Permits
        • If an applicant is unsure if modeling will be required to conduct a required NAAQS analysis, the APCD-114 Form (updated July 15, 2023) should be filled out to obtain a decision prior to submitting a permit application or a Modeling Analysis to the Air Pollution Control Division (Division). Form Instructions are provided here. Additional clarification can be found here
        • Once a determination is made, the applicant will be provided documentation of the PMU Determination by Division. The APCD-114 Form and PMU Determination must be included in the permit application and 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 PMU Determination, which demonstrates NAAQS compliance, will be included as part of the source or modification’s permit application record and no further analysis will be required. 
      • New General Permit Registrations: GP01, GP02, GP05, GP06, GP07, GP08, GP09, GP10 and GP11
        • In order to evaluate if modeling will be required to conduct a required NAAQS analysis pursuant to the Colorado Minor NSR Source Modeling Guideline for Air Quality Permits (May 2023), the APCD-114 Form (updated July 15, 2023) should be filled out to obtain a decision prior to submitting a general permit registration  or a Modeling Analysis to the Air Pollution Control Division (Division). Form Instructions are provided hereAdditional clarification can be found here
        • Once a determination is made, the applicant will be provided documentation of the PMU Determination by the Division. The APCD-114 Form and PMU Determination must be included in the general permit registration and will be part of the source’s permit application record. If a determination of “Modeling Not Required” is made, the completed APCD-114 Form and PMU Determination will be included as part of the source or modification’s permit application record and no further analysis will be required. If a determination of "Modeling Required" is made, the applicant must submit a Modeling Analysis demonstrating compliance with the NAAQS to the Division and obtain a Modeling Review Report, which is written approval of the Modeling Analysis, prior to submitting a general permit registration. The Modeling Review Report or determination of “Modeling Not Required” must be submitted with the General Permit registration for the registration to be complete.

    Supplemental Modeling Guidance, Maps, Forms, and Information

    Meteorological & Geophysical Data for Air Quality Permit Modeling

    Federal Modeling Support