OAR 340-224-0510: Net Air Quality Benefit Emission Offsets: Common Offset Requirements

The purpose of these rules is to demonstrate reasonable further progress toward achieving or maintaining the ambient air quality standards for sources locating within or impacting designated areas. A source may make such demonstration by providing emission offsets to balance the level of projected emissions by the source at the applicable ratios described in this division. (1) Unless otherwise specified in the rules, offsets required under this rule must meet the requirements of OAR 340 division 268, Emission Reduction Credits. (2) Except as provided in section (3), the emission reductions used as offsets must be of the same type of regulated pollutant as the emissions from the new source or modification. Sources of PM10 must be offset with particulate in the same size range. (3) Offsets for direct PM2.5 may be obtained from NO2 and SO2 emissions as precursors to secondary PM2.5. The interpollutant trading ratios for these emissions will be approved by DEQ on a case by case basis. Offsets for SO2 and NO2 emissions from direct PM2.5 emissions will be determined in the same manner. (4) Offset ratios specified in these rules are the minimum requirement. All offsets obtained by a source, including any that exceed the minimum requirement, may be used for the purpose of OAR 340-224-0530(4). (5) Emission reductions used as offsets must meet at least one of the following criteria: (a) They must be equivalent to the emissions being offset in terms of short term, seasonal, and yearly time periods to mitigate the effects of the proposed emissions; or (b) They must address the air quality problem in the area, such as but not limited to woodstove replacements to address winter-time exceedances of short term PM2.5 standards. (6) If the complete permit application or permit that is issued based on that application is amended due to changes to the proposed project, the owner or operator may continue to use the original offsets and any additional offsets that may become necessary for the project provided that the changes to the project do not result in a change to the two digit Standard Industrial Classification (SIC) code associated with the source and that the offsets will continue to satisfy the offset criteria. NOTE: This rule, except section (3), is included in the State of Oregon Clean Air Act Implementation Plan that EQC adopted under OAR 340-020-0040.