Section 203.303  Baseline and Emission Offsets Determination

a)         An emission offset must be obtained from a source in operation prior to the permit application for the new or modified source.  Emission offsets must be effective prior to start-up of the new or modified source.

b)         The emission offsets provided:

1)         Must be of the same pollutant and further be of a type with approximately the same qualitative significance for public health and welfare as that attributed to the increase from a particular change;

2)         Must, in the case of a fuel combustion source, be based on the type of fuel being burned at the time the permit application is filed, and, if offset is to be produced by a future switch to a cleaner fuel, be accompanied by evidence that long-term supplies of the clean fuel are available and a commitment to a specified alternative control measure which would achieve the same degree of emission reduction of the dirtier fuel is proposed;

3)         Must, in the case of a past shutdown of a source or permanent curtailment of production or operating hours, have occurred since April 24, 1979, or the date the area is designated a nonattainment area for the pollutant, whichever is more recent, and, until the United States Environmental Protection Agency (USEPA) has approved the attainment demonstration and state trading or marketing rules for the relevant pollutant, the proposed new or modified source must be a replacement for the shutdown or curtailment;

4)         Must be federally enforceable by permit; and

5)         Must not have been previously relied on, as demonstrated by the Agency, in issuing any permit pursuant to 35 Ill. Adm. Code 201.142 or 201.143 or this Part, or for demonstrating attainment or reasonable further progress.

c)         The baseline for determining the extent to which emission reductions are creditable as offsets shall be the actual emissions of the source from which the offset is to be obtained, to the extent they are within any applicable emissions limitations of this Chapter or the Act or any applicable standards adopted by USEPA pursuant to Section 111 and 112 of the Clean Air Act, and made applicable in Illinois pursuant to Section 9.1 of the Environmental Protection Act (Ill. Rev. Stat. 1991, ch. 111½, par. 1009.1) [415 ILCS 5/9.1].

d)         The location of sources providing the emission  reductions to fulfill the offset requirements of this Section:

1)         Must be achieved in the same nonattainment area as the increase being offset, except as provided as follows:

A)        An owner or operator may obtain the necessary emission reductions from another nonattainment area where such other area has an equal or higher nonattainment classification than the area in which the source is located, and

B)        The emission reductions from such other area contribute to a violation of the national ambient air quality standard in the nonattainment area in which the new or modified source is located.

2)         Must, for particulate matter, sulfur dioxide and carbon monoxide, be such that, relative to the site of the proposed new or modified source, the location of the offset, together with its effective stack height, ensures a positive net air quality benefit.  This shall be demonstrated by atmospheric simulation modeling, unless the sources providing the offset are on the same premises or in the immediate vicinity of the new or modified source and the pollutants disperse from substantially the same effective stack height. In determining effective stack height, credit shall not be given for dispersion enhancement techniques.  The owner or operator of a proposed new or modified source shall perform the analysis to demonstrate the acceptability of the location of an offset, if the Agency declines to make such analysis.  Effective stack height means actual stack height plus plume rise.  Where actual stack height exceeds good engineering practices, as determined pursuant to 40 CFR 51.100 (1987) (no future amendments or editions are included), the creditable stack height shall be used.

e)         Replacement of one volatile organic material with another of lesser reactivity does not constitute an emission reduction.

f)         Emission reductions otherwise required by the Clean Air Act (42 U.S.C. 7401 et seq.) shall not be creditable for purposes of any such offset requirement.  Incidental emission reductions which are not otherwise required by the Clean Air Act shall be creditable as emission reductions for such purposes if such emissions reductions meet the requirements of this Subpart.

(Source:  Amended at 17 Ill. Reg. 6973, effective April 30, 1993)