(1) The ratio of total actual emissions reductions to the emissions increase shall be 1.1:1 unless an alternative ratio is provided for the applicable nonattainment area in subsection (2) through (4) of this section.

(2) In meeting the emissions offset requirements of WAC 173-400-830 for ozone nonattainment areas that are subject to sections 181-185B of the Federal Clean Air Act, the ratio of total actual emissions reductions of VOC to the emissions increase of VOC shall be as follows:

(a) In any marginal nonattainment area for ozone - 1.1:1;

(b) In any moderate nonattainment area for ozone - 1.15:1;

(c) In any serious nonattainment area for ozone - 1.2:1;

(d) In any severe nonattainment area for ozone - 1.3:1; and

(e) In any extreme nonattainment area for ozone - 1.5:1.

(3) Notwithstanding the requirements of subsection (2) of this section for meeting the requirements of WAC 173-400-830, the ratio of total actual emissions reductions of VOC to the emissions increase of VOC shall be 1.15:1 for all areas within an ozone transport region that is subject to sections 181-185B of the Federal Clean Air Act, except for serious, severe, and extreme ozone nonattainment areas that are subject to sections 181-185B of the Federal Clean Air Act.

(4) In meeting the emissions offset requirements of this section for ozone nonattainment areas that are subject to sections 171-179b of the Federal Clean Air Act (but are not subject to sections 181-185B of the Federal Clean Air Act, including eight-hour ozone nonattainment areas subject to 40 C.F.R. 51.902(b)), the ratio of total actual emissions reductions of VOC to the emissions increase of VOC shall be 1.1:1.

(5) Emission offsets used to meet the requirements of WAC 173-400-830 (1)(e), must be for the same regulated NSR pollutant.

(6) If the offsets are provided by another source, the reductions in emissions from that source must be federally enforceable by the time the order of approval for the new or modified source is effective. An emission reduction credit issued under WAC 173-400-131 may be used to satisfy some or all of the offset requirements of this subsection.

(7) Emission offsets are required for the incremental increase in allowable emissions occurring during startup and shutdown operations at the new or modified emission units subject to nonattainment area major new source review. The incremental increase is the difference between the allowable emissions during normal operation and the allowable emissions for startup and shutdown contained in the nonattainment new source review approval.

(8) Emission offsets including those described in an emission reduction credit issued under WAC 173-400-131, must meet the following criteria:

(a) The baseline for determining credit for emissions reductions is the emissions limit under the applicable state implementation plan in effect at the time the notice of construction application is determined to be complete, except that the offset baseline shall be the actual emissions of the source from which offset credit is obtained where:

(i) The demonstration of reasonable further progress and attainment of ambient air quality standards is based upon the actual emissions of sources located within the designated nonattainment area; or

(ii) The applicable state implementation plan does not contain an emissions limitation for that source or source category.

(b) Other limitations on emission offsets.

(i) Where the emissions limit under the applicable state implementation plan allows greater emissions than the potential to emit of the source, emissions offset credit will be allowed only for control below the potential to emit;

(ii) For an existing fuel combustion source, credit shall be based on the allowable emissions under the applicable state implementation plan for the type of fuel being burned at the time the notice of construction application is determined to be complete. If the existing source commits to switch to a cleaner fuel at some future date, an emissions offset credit based on the allowable (or actual) emissions reduction resulting from the fuels change is not acceptable, unless the permit or other enforceable order is conditioned to require the use of a specified alternative control measure which would achieve the same degree of emissions reduction should the source switch back to the higher emitting (dirtier) fuel at some later date. The permitting authority must ensure that adequate long-term supplies of the new fuel are available before granting emissions offset credit for fuel switches;

(iii) Emission reductions.

(A) Emissions reductions achieved by shutting down an existing emission unit or curtailing production or operating hours may be generally credited for offsets if:

(I) Such reductions are surplus, permanent, quantifiable, and federally enforceable; and

(II) The shutdown or curtailment occurred after the last day of the base year for the SIP planning process. For purposes of this subsection, the permitting authority may choose to consider a prior shutdown or curtailment to have occurred after the last day of the base year if the projected emissions inventory used to develop the attainment demonstration explicitly includes the preshutdown or precurtailment emissions from the previously shutdown or curtailed emission units. However, in no event may credit be given for shutdowns that occurred before August 7, 1977.

(B) Emissions reductions achieved by shutting down an existing emissions unit or curtailing production or operating hours and that do not meet the requirements in subsection (8)(b)(iii)(A) of this section may be generally credited only if:

(I) The shutdown or curtailment occurred on or after the date the construction permit application is filed; or

(II) The applicant can establish that the proposed new emissions unit is a replacement for the shutdown or curtailed emissions unit, and the emissions reductions achieved by the shutdown or curtailment met the requirements of (7)(b)(iii)(A)(I) of this section.

(iv) All emission reductions claimed as offset credit shall be federally enforceable;

(v) Emission reductions used for offsets may only be from any location within the designated nonattainment area. Except the permitting authority may allow use of emission reductions from another area that is nonattainment for the same pollutant, provided the following conditions are met:

(A) The other area is designated as an equal or higher nonattainment status than the nonattainment area where the source proposing to use the reduction is located; and

(B) Emissions from the other nonattainment area contribute to violations of the standard in the nonattainment area where the source proposing to use the reduction is located.

(vi) Credit for an emissions reduction can be claimed to the extent that the reduction has not been relied on in issuing any permit under 40 C.F.R. 52.21 or regulations approved pursuant to 40 C.F.R. Part 51, subpart I or the state has not relied on it in demonstration of attainment or reasonable further progress.

(vii) The total tonnage of increased emissions, in tons per year, resulting from a major modification that must be offset in accordance with Section 173 of the Federal Clean Air Act shall be determined by summing the difference between the allowable emissions after the modification and the actual emissions before the modification for each emissions unit.

(9) No emissions credit may be allowed for replacing one hydrocarbon compound with another of lesser reactivity, except for those compounds listed in Table 1 of EPA's "Recommended Policy on Control of Volatile Organic Compounds" (42 FR 35314, July 8, 1977). This document is also available from Office of Air Quality Planning and Standards, (MD-15) Research Triangle Park, NC 27711.