(1) The modification procedures set forth in (3) , must be used for any application requesting a significant modification of an air quality operating permit. Significant modifications include the following:

(a) any permit modification that does not qualify as either a minor modification or as an administrative permit amendment;

(b) every significant change in existing permit monitoring terms or conditions;

(c) every relaxation of permit reporting or recordkeeping terms or conditions which limits the department's ability to determine compliance with any applicable rule, consistent with the requirements of the rule; or

(d) any other change determined by the department to be significant.

(2) Nothing herein may be construed to preclude the permittee from making changes consistent with this chapter that would render existing permit compliance terms and conditions irrelevant.

(3) Significant modifications shall meet all requirements of this chapter, including those for applications, public participation, and review by affected states and the administrator, as they apply to permit issuance and renewal, except that an application for a significant modification permit need only address in detail those portions of the permit application that require revision, updating, supplementation, or deletion. The department shall conduct this process to complete review of the majority of significant modifications within nine months after receipt of a complete application.

(4) The permit shield provided for in ARM 17.8.1214 shall extend to significant modifications.