OAR 340-225-0045: Requirements for Analysis in Maintenance Areas

Modeling: For determining compliance with the maintenance area impact levels established in OAR 340-202-0225, the following methods must be used: (1) For each maintenance pollutant, a single source impact analysis is sufficient to show compliance with the maintenance area maximum impact levels if: (a) The modeled impacts from emission increases equal to or greater than a SER above the netting basis due to the proposed source or modification being evaluated are less than the Class II Significant Impact Levels specified in OAR 340-200-0020; and (b) The owner or operator provides an assessment of factors that may impact the air quality conditions in the area showing that the SIL by itself is protective of the maintenance area impact levels. The assessment must take into consideration but is not limited to the emission increases and decreases since the baseline concentration year from other sources that are expected to cause a significant concentration gradient in the vicinity of the source. Determination of significant concentration gradient may take into account factors including but not limited to ROI formula, spatial distribution of existing emission sources, topography, and meteorology. (2) If the requirement in section (1) is not satisfied, the owner or operator of a proposed source or modification must complete a competing source analysis to demonstrate that modeled impacts from the proposed increased emissions plus competing source impacts, plus the predicted maintenance area concentration are less than the maintenance area impact levels in OAR 340-202-0225 for all averaging times. (3) Any analyses performed under this section must be done in compliance with OAR 340-225-0030 and 340-225-0040, as applicable. [NOTE: This rule is included in the State of Oregon Clean Air Act Implementation Plan that EQC adopted under OAR 340-020-0040.]