9VAC5-80-1725: Air quality models

A. All applications of air quality modeling involved in this article shall be based on the applicable air quality models, data bases, and other requirements specified in Appendix W to 40 CFR Part 51.

B. Where an air quality impact model specified in Appendix W to 40 CFR Part 51 is inappropriate, the model may be modified or another model substituted. Such a modification or substitution of a model may be made on a case-by-case basis, or, where appropriate, on a generic basis for a specific state program. Written approval of the administrator shall be obtained for any modification or substitution. In addition, use of a modified or substituted model shall be subject to notice and opportunity for public comment under procedures developed in accordance with 9VAC5-80-1775.