06-096 C.M.R. ch. 113, § 3 - Use of Offset Credits

A. Sources that meet the applicability requirements pursuant to Section 1 of this Chapter must obtain offset credits for that nonattainment pollutant, or its precursors, as directed in Subsection 3(E) below.

B. The new source or modification may not commence operation until the Department has determined that emission reductions of the nonattainment pollutant have occurred and that all requirements of Section 4 of this Chapter are met.

C. Offset credit reductions must be federally enforceable by the time the air emission license for the user is issued.

D. At a minimum, the total offset credits required shall be greater than the potential emission increase from a new major source or new major modification pursuant to this section.

E. Offset Credit Requirements

(1) Volatile Organic Compounds (VOC) and NO_xOffset Credits

(a) VOC and NO_xOffset Ratios. For a new major source or major modification subject to this Chapter, the offset ratio for VOC and NO_xis based on the current ozone nonattainment area classification or other designation for the area in which the new major source or major modification will locate, and on the distance between the new major source or major modification and the source from which offset credits are obtained, as specified below. If the location of a new major source or major modification is subject to more than one classification, the more restrictive offset ratio shall apply.

(b) NO_xoffset credits may be used to offset increased VOC emissions, and VOC offset credits may be used to offset increased NO_xemissions, if approved by the EPA and the Department. In areas subject to a NO_xwaiver under section 182(f) of the Clean Air Act, NO_xcredits may be used to offset VOC emissions to the extent allowed under the Clean Air Act and upon written notification of approval from the EPA. The same number of offset credits must be obtained whether NO_xor VOC credits are used. Approval by the Department will be based on whether the Department finds that the same estimated ozone reduction will be achieved whether VOC offset credits or NO_xoffset credits are used.

(c) Location of Offset Credits for VOC and NO_xOffset credits for VOC and NO_xshall be obtained from sources in the same ozone designation area, except that such offset credits may be obtained from a source in another ozone designation area if the conditions of either (i) or (ii), whichever is relevant, are met:

(i) Locating in an Ozone Nonattainment Area: For a new major source or major modification subject to this Chapter locating in an ozone nonattainment area:

(a) The ozone nonattainment area from which offset credits are obtained has an equal or higher (i.e., more serious) nonattainment classification than the ozone nonattainment area in which the new major source or major modification subject to this Chapter is locating; and

(b) Emissions from the ozone nonattainment area from which offset credits are obtained contribute to a violation of a National Ambient Air Quality Standard in the ozone nonattainment area in which the new major source or major modification subject to this Chapter is locating;

(c) Offset credits are obtained based on the classification of the area in which the new major source or major modification is locating, per the minimum offset ratios listed below:

Ozone Classification for Area in Which New Major Source or Major Modification is Locating	Minimum Offset Ratio
Serious nonattainment area	1.2 to 1
Moderate nonattainment area	1.15 to 1
Marginal nonattainment area (not included in the OTR)	1.1 to 1
Areas within the OTR	1.15 to 1

(ii) Locating In an Ozone Attainment Area in the OTR: For a new major source or major modification subject to this Chapter locating in an ozone attainment area in the OTR, the source from which the offset credits are being obtained must be located in the OTR and may be located within another ozone attainment area or within an ozone nonattainment area if approved by the Department and EPA. Sources locating in an ozone attainment area within the OTR must obtain VOC offset credits at a ratio of 1.15 to 1.

A new major source or major modification subject to this Chapter locating in an ozone attainment area that does not have a NO_x waiver under section 182(f) of the Clean Air Act must obtain NO_xoffset credits at a ratio of 1.15 to 1.

(2) Offset Credits for SO₂, PM₁₀, PM_2.5, NO₂, CO, or Lead

(a) Offset credits for sulfur dioxide (SO₂), particulate matter smaller than 10 microns in diameter (PM₁₀), particulate matter smaller than 2.5 microns in diameter (PM_2.5), nitrogen dioxide (NO₂), carbon monoxide (CO), or lead (Pb) must be obtained in a ratio that is greater than 1 to 1.

(b) Demonstration of a Net Air Quality Benefit

When the new major source or major modification subject to this Chapter is locating in or has a significant impact on an SO₂, NO₂, PM₁₀, PM_2.5, CO, or Lead nonattainment area, and the offset credits are not obtained from an existing stationary source on the same premises or in the vicinity (within 250 meters), and the pollutants are not emitted from substantially the same effective stack height of the new source or modification, a demonstration of a net air quality benefit shall be made on the basis of atmospheric dispersion modeling.

(c) Location of Offset Credits

Offset credits for SO₂, PM₁₀, PM_2.5, NO₂, CO, and Lead shall be obtained from the same source or other sources located in the same nonattainment area or in another nonattainment area if

(i) The other area has an equal or higher (worse) nonattainment classification than the area in which the source is located; and

(ii) Emissions from such other area contribute to a violation of the national ambient air quality standard in the nonattainment area in which the source is located.

(d) NO_x offsets generated in Maine cannot be used by a source located outside of Maine, unless that source is located on the outer continental shelf and Maine has been determined to be the corresponding onshore area for the source pursuant to 40 C.F.R. Part 55.

Notes

06-096 C.M.R. ch. 113, § 3