South Dakota Administrative Rules
Title 74 - Department of Environment And Natural Resources
Article 74:36 - Air pollution control program
Chapter 74:36:10 - New source review
Section 74:36:10:07 - Determining credit for emission offsets

(1) All offsets must be for the same regulated NSR pollutant, result in a net positive air quality benefit in the affected area, and be approved by the department before issuance of the permit, even though they need not be in effect until the source commences operation. The offset ratio of total actual emissions reductions to the emissions increase shall be at least 1 to 1 unless an alternative ratio is provided in accordance with the offset requirements in 40 C.F.R. § 51.165(a)(9)(ii) through 51.165(a)(9)(iv) (July 1, 2018);

(2) External offsets or those emission limitations from sources not owned, operated, or controlled by an applicant for a permit shall be made through a revision of the permit conditions of the participating source or sources. At no time may the baseline be exceeded;

(3) The permissible location of offsetting emissions shall be conducted in accordance with 40 C.F.R., Part 51, Appendix S, section IV.D (July 1, 2018);

(4) For an existing fuel combustion unit, credit shall be based on the emission limit for the type of fuel being burned at the time the application to construct is filed. If the existing source agrees to switch to a cleaner fuel at some future date, emission offset credits based on the allowable or actual emissions for the fuels involved may be allowed only if permit conditions specify an alternative control measure that would achieve the same degree of emission reduction if the source switched back to the dirtier fuel at some later date;

(5) Emission reductions achieved by shutting down an existing unit or curtailing production or operating hours below baseline levels may be credited if the reductions are permanent, quantifiable, federally enforceable, and the area has a federally-approved attainment plan. In addition, the shutdown or curtailed production must occur after August 7, 1977, or less than one year before the date of submitting the permit application, whichever is earlier. Emission reductions may be credited in the absence of a federally-approved attainment plan if the shutdown or curtailment occurred on or after the date the application is filed for a new unit or if the applicant can establish that the proposed new unit is a replacement for the shutdown or curtailed unit, and the shutdown or curtailment occurred after August 7, 1977, or less than one year before the date of submitting the permit application, whichever is earlier;

(6) Except as set forth in 40 C.F.R. § 51.165(a)(3)(ii)(D) (July 1, 2018), emission offset credit may not be allowed for replacing one hydrocarbon compound with another of lesser reactivity;

(7) Credit for emissions reduction may be claimed to the extent that the department has not relied on it in issuing a permit or in its demonstration of attainment or reasonable further progress;

(8) If the emissions limit allows greater emissions than the potential to emit of the unit, the emission offset credit is allowed only for the control below the potential to emit of the unit; and

(9) All emission reductions claimed as offset credit must be federally enforceable.