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Permit Modeling Guidance
| This section provides recommendations on modeling techniques and guidance for estimating pollutant concentrations in order to assess control strategies and determine emission limits. These recommendations were originally published in April 1978 as the "Guideline on Air Quality Models" and were incorporated by reference in the regulations for the Prevention of Significant Deterioration of Air Quality, Title 40, Code of Federal Regulations (CFR) sections 51.166 and 52.21 in June 1978 [Federal Register, 43 (118), 26 382-26 388]. The purpose of these guidelines is to promote consistency in the use of modeling within the air quality management process. These guidelines are periodically revised to ensure that new model developments or expanded regulatory requirements are incorporated. This section provides guidance associated with permit modeling and is divided into three components: Appendix W Guidance, Screening Guidance, and Other Permit Modeling Guidance. |
| Appendix W Guidance |
| Appendix W (803KB,pdf) - 40 CFR Part 51 Appendix W (November 2005) Preferred/Recommended Models listed in Appendix W - a list of preferred and recommended models as provided in Appendix W. Use of Alternative Models - A list of dispersion models for use on a case-by-case basis with approval by reviewing authority. Example Air Quality Analysis Checklist - An example checklist as it formerly appeared as Appendix C of the "Guideline on Air Quality Models" as explained in the Explanatory Note. Clarification Memos - Provides access to memoranda issued by EPA as clarifications of Appendix W and technical aspects of dispersion modeling in general. |
| Screening Guidance |
Screening Procedures for Estimating the Air Quality Impact of Stationary Sources (3.2MB, WP) Screening Models - SCRAM webpage providing information on screening models, including model code and documentation |