(1) The department will not issue a Montana air quality permit required under ARM 17.8.1004 unless the requirements of subchapters 7 and 8 and the following additional conditions are met:

(a) the new source is required to meet an emission limitation, as more fully described in (2) and (3) , which specifies the lowest achievable emission rate for such source;

(b) the applicant certifies that all existing major stationary sources owned or operated by the applicant (or any entity controlling, controlled by, or under common control with the applicant) in the state of Montana are in compliance with all applicable emission limitations and standards under the FCAA or are in compliance with an expeditious schedule of compliance which is federally enforceable or contained in a court decree;

(c) the new source must obtain from existing sources emission reductions (offsets) , expressed in tons per year, which provide both a positive net air quality benefit in the affected area as determined in accordance with (3) , ARM 17.8.1006 and 17.8.1007, and a ratio of required emission offsets to the proposed source's emissions of 1:1 or greater; and

(d) the Montana air quality permit contains a condition requiring the source to submit documentation, prior to commencement of operation that the offsets required in the Montana air quality permit have occurred.

(2) If the department determines that technological or economic limitations on the application of measurement methodology to a particular class of sources would make the imposition of an enforceable numerical emission standard infeasible, the department may, instead, prescribe a design, operational or equipment standard. In such cases, the department shall make its best estimate as to the emission rate that will be achieved, and must take such steps as are necessary to ensure that this rate is federally enforceable. Any Montana air quality permit issued without an enforceable numerical emission standard must contain enforceable conditions which assure that the design characteristics or equipment will be properly maintained (or that the operational conditions will be properly performed) so as to continuously achieve the assumed degree of control. As used in this subchapter, the term "emission limitation" shall also include such design, operational, or equipment standards.

(3) The requirements of (1) (a) and (c) , shall only apply to those pollutants for which the major stationary source or major modification is major and for which the source is causing or contributing to a violation of a national ambient air quality standard.

(4) If the emissions from the proposed source would cause a new violation of a national ambient air quality standard but would not contribute to an existing violation, the new source must meet a more stringent and federally enforceable emission limitation, as more fully described in (2) , and/or control existing sources below allowable levels through federally enforceable methods so that the source will not cause a violation of any national ambient air quality standard. The new emission limitation must be accomplished prior to the new source's startup date.

(5) The issuance of a Montana air quality permit does not relieve any owner or operator of the responsibility to comply fully with applicable provisions of the Montana State Implementation Plan and any other requirements of local, state or federal law.

(6) Emission reductions (air quality offsets) under (1) (c) must also comply with the additional requirements for determining the baseline and magnitude of emission reductions (air quality offsets) contained in ARM 17.8.905(1) (c) and 17.8.906, except that 17.8.906(7) through (9) shall not be applicable to offsets required under this subchapter.