Oregon Administrative Rules › Chapter 340 - DEPARTMENT OF ENVIRONMENTAL QUALITY › Division 245 - CLEANER AIR OREGON › Section 340-245-0210 - Modeling and Risk Assessment Work Plan Requirements

Current through Register Vol. 63, No. 7, July 1, 2024
The owner or operator of a source must follow the applicable
				procedures in this rule when required to perform a risk assessment under OAR
				340-245-0050  or 340-245-0060.
(1)
			 Modeling Requirements. All modeled estimates of ambient concentrations required
			 under this division must be based on the applicable air quality models and
			 other requirements as specified in  40 CFR part 51, Appendix W, "Guidelines on
			 Air Quality Models (Revised)," or a substantially equivalent model or
			 requirement approved by DEQ. Any change or substitution from models and
			 procedures specified in  40 CFR part 51, Appendix W must be approved by DEQ in
			 advance and incorporated in the modeling protocol. AERSCREEN and AERMOD are
			 examples of approved air quality models.
(a)
			 When choosing to perform a Level 1 Risk Assessment or modeling for a Level 2,
			 Level 3 or Level 4 Risk Assessment, the owner or operator of a source must
			 first submit a modeling protocol that must be approved by DEQ as required in
			 OAR 340-245-0030. The necessary information to perform any modeling will depend
			 on the risk assessment level and the model being used, if any, and may include
			 but is not limited to:
(A) Toxic air
			 contaminant emission rates based on the emissions inventory submitted under OAR
			 340-245-0040(1);
(B) Stack
			 parameter and building data, including stack height above ground, stack
			 orientation and configuration, exit diameter, exit velocity, and exit
			 temperature, for all existing and proposed emission points from the source, and
			 dimension data of buildings;
(C)
			 Meteorological and topographical data;
(D) Information about the dispersion models
			 and modeling parameters used;
(E)
			 Exposure locations where ambient concentrations will be modeled;
(F) For determining exposure locations where
			 ambient concentrations will be modeled, an owner or operator may provide
			 documentation to demonstrate an area is not being used in the manner allowed by
			 the land use zoning at the time the modeling is to be performed, and may
			 request that the land use zoning classification of these areas be excluded in
			 determining chronic exposure locations. If DEQ approves an exclusion under this
			 paragraph, then:
(i) The owner or operator
			 must model the approved locations based on their actual use;
(ii) The owner or operator must annually
			 submit to DEQ documentation showing the areas subject to the excluded land use
			 zoning classification continue to not be used in the manner allowed by the land
			 use zoning applicable to the area; and
(iii) If the annual documentation provided
			 under subparagraph (ii) shows the area is being used in the manner allowed by
			 the land use zoning and results in potential exposure to toxic air contaminants
			 from the source, the owner or operator must update the risk assessment based on
			 the change in use and apply for a Toxic Air Contaminant Permit Addendum
			 modification under OAR 340-245-0100(8)  or for an operating permit modification
			 under OAR 340 division 216 or 218 using the procedures in this division, if
			 applicable;
(G) Use of
			 other exposure locations where DEQ determines, based on documented evidence,
			 that an area is not being used in the manner allowed by the land use zoning at
			 the time the modeling is to be performed, such area should be considered an
			 exposure location based on its actual use; and
(H) Other information that may be necessary
			 to estimate air quality concentrations and risk at exposure
			 locations;