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.
