(1) The division may convene, at any appropriate time, an informal voluntary negotiation process, with appropriate public participation, to seek voluntary enforceable commitments from sources and source categories to achieve emissions reductions sufficient to make reasonable further progress in reducing any portion of the impairment.

(2) A voluntary enforceable commitment becomes enforceable through a commission rule, local ordinance or resolution, judicially enforceable consent decree, or division permit condition, as appropriate to the circumstances.

(3) If subsequent to January 15, 1996, a source or source category agrees to an enforceable commitment to adopt a control strategy that the division determines is as effective or is more effective than best available retrofit technology for stationary sources or reasonably available control measures for nonstationary sources, the division shall exempt that source or source category from the imposition of further controls pursuant to this part 10 for a period of ten years from the date established for achieving the emission reductions as specified in the voluntary enforceable agreement.

(4) If subsequent to January 15, 1996, and prior to January 15, 1998, a source or source category agrees to an enforceable commitment contained in a judicially enforceable consent decree to adopt a control strategy that the division determines provides both for reasonable progress toward the national visibility goal under 40 CFR Part 51, Subpart P and 5 CCR 1001-4 and for reasonable progress in reducing any present or future impairment of an air quality related value, the division shall exempt that source or source category from the imposition of further controls pursuant to this part 10 for a period of ten years from the date established for achieving the emission reductions as specified in the judicially enforceable consent decree. The provisions of section 25-7-133 shall not apply to that portion of an amendment to the visibility component of the state implementation plan that implements and enforces the control strategy covered by this subsection (4).

(5) If a source or source category agrees to an enforceable commitment to adopt a control strategy that the division determines is not as effective as best available retrofit technology for stationary sources or reasonably available control measures for nonstationary sources but that the division determines will assist in making reasonable further progress in reducing impairment of an air quality related value, the commission may, after public hearing, exempt that source or source category from the imposition of further controls pursuant to this part 10 with respect to those pollutants that the source or source category has agreed to control for a period of up to ten years from the date established for achieving the emission reductions as specified in the voluntary enforceable agreement.

(6) A source that, prior to June 1, 1996, has received a permit under the federal prevention of significant deterioration program, 42 U.S.C. secs. 7470 to 7479 or sections 25-7-201 to 25-7-210, and installed pollution control measures comparable to the best available control technology pursuant to that program shall not be required to install additional control measures pursuant to this part 10 for a period of ten years from June 1, 1996, but may be required to operate pollution control equipment to its maximum efficiency. This section shall not apply to any source that is not subject to compliance with the requirements of 42 U.S.C. sec. 7651 (f), which establishes schedules and emission limitations for the control of nitrogen oxide emissions from certain stationary sources. Nothing in this subsection (6) shall be construed to modify the terms of any permit applicable to such source or excuse compliance with respect to any other requirement under this article or the federal act. Except for the exemption for a period of ten years providedin this subsection (6), nothing in this subsection (6) shall excuse such sources from responding to reasonable requests by the division for information required to complete inventories and attribution and apportionment studies.