OAR 340-245-0050
Risk Assessment Procedures

(1) Existing source.
(a) When notified in writing by DEQ, at DEQ’s discretion, the owner or operator of an existing source with an operating permit must either demonstrate that it is an exempt source or:
(A) Assess risk from the source using any of the Level 1 through Level 4 Risk Assessment procedures in sections (8) through (11);
(B) Assess risk from the source using the emissions inventory submitted under OAR 340-245-0040 (Emissions Inventory)(1); and
(C) Follow the applicable calculation procedures under OAR 340-245-0200 (Risk Estimates).
(b) If the owner or operator of an existing source proposes to modify the source in a way that would require compliance under OAR chapter 340, division 224, “New Source Review,” excluding actions described in OAR 340-224-0010 (Applicability, General Prohibitions, General Requirements and Jurisdiction)(2)(b) and (d)(B) that require compliance only as Type B State New Source Review, then the owner or operator must perform a risk assessment and demonstrate compliance under this division and must include its compliance demonstration under this division with its application submitted under OAR chapter 340, division 224.
(c) The owner or operator must demonstrate compliance with paragraph (A), (B), (C) or (D), and also comply with paragraph (E), if applicable.
(A) The owner or operator must demonstrate that the source is a de minimis source by following the procedure in section (7), or demonstrate that the risk from the source is less than or equal to the TBACT Level. The owner or operator of a source whose risk is less than or equal to the TBACT Level must apply for a Toxic Air Contaminant Permit Addendum under OAR 340-245-0100 (Toxic Air Contaminant Permit Addenda) with Source Risk Limits or an application that modifies the existing permit in a manner that ensures that the risk from the source will be less than or equal to the TBACT Level.
(B) Toxic air contaminant monitoring.
(i) Before the owner or operator of a source may begin air monitoring, the owner or operator must complete and submit to DEQ a Level 3 or Level 4 Risk Assessment and comply with the applicable requirements of OAR 340-245-0230 (Toxic Air Contaminant Monitoring Requirements).
(ii) An owner or operator may not delay submission of an application for an Air Contaminant Permit Addendum and subsequent implementation of the approved Risk Reduction Plan prepared under OAR 340-245-0130 (Risk Reduction Plan Requirements) if a Level 3 or 4 Risk Assessment shows that:
(I) Calculated cancer risk exceeds 200 in 1 million;
(II) Calculated noncancer risk exceeds a Hazard Index of 12 if all toxic air contaminants emitted have been assigned a noncancer TBACT Risk Action Level of a Hazard Index of 3;
(III) Calculated noncancer risk exceeds a Hazard Index of 20 if all toxic air contaminants emitted have been assigned a noncancer TBACT Risk Action Level of a Hazard Index of 5; or
(IV) Calculated noncancer Risk Determination Ratio exceeds 4 if air toxic contaminants emitted include a mixture of toxic air contaminants assigned noncancer TBACT Risk Action Levels of both a Hazard Index of 3 and a Hazard Index of 5.
(iii) If the Level 3 or Level 4 Risk Assessment calculates risk from the source that does not cause any exceedances of the criteria in subparagraph (ii), then DEQ shall issue a Toxics Air Contaminant Permit Addendum addressing only toxic air contaminant monitoring requirements, including a reporting and compliance schedule for implementing the Toxic Air Contaminant Monitoring Plan required under OAR 340-245-0230 (Toxic Air Contaminant Monitoring Requirements);
(iv) Upon completion and DEQ approval of toxic air contaminant monitoring in compliance with OAR 340-245-0230 (Toxic Air Contaminant Monitoring Requirements), the owner or operator must use the toxic air contaminant monitoring results, in association with other applicable, relevant data to determine compliance requirements under paragraph (c)(A), (C), or (D) and apply for a Toxic Air Contaminant Permit Addendum modification under OAR 340-245-0100 (Toxic Air Contaminant Permit Addenda);
(C) TBACT compliance. If the risk from the source is greater than the TBACT Level and less than or equal to the Risk Reduction Level, and all significant TEUs meet TBACT under OAR 340-245-0220 (TBACT and TLAER Procedures), then the owner or operator must apply for a Toxic Air Contaminant Permit Addendum under OAR 340-245-0100 (Toxic Air Contaminant Permit Addenda) that includes Source Risk Limits that ensure the risk from the source will be less than or equal to the Risk Reduction Level; or
(D) Risk Reduction Plan. The owner or operator may demonstrate compliance with this paragraph under either subparagraph (i), (ii), or (iii), whichever is applicable:
(i) If the risk from the source is greater than the TBACT Level and the owner or operator can make physical, operational or process changes to reduce the risk to less than or equal to the TBACT Level, then the owner or operator must apply for a Toxic Air Contaminant Permit Addendum under OAR 340-245-0100 (Toxic Air Contaminant Permit Addenda) that includes a Risk Reduction Plan under OAR 340-245-0130 (Risk Reduction Plan Requirements) and Source Risk Limits that ensure that the risk from the source will be less than or equal to the TBACT Level;
(ii) If the risk from the source is greater than the TBACT Level and less than or equal to the Risk Reduction Level, but not all significant TEUs meet TBACT under OAR 340-245-0220 (TBACT and TLAER Procedures), then the owner or operator must either reduce risk below the TBACT Level under subparagraph (i) or apply for a Toxic Air Contaminant Permit Addendum under OAR 340-245-0100 (Toxic Air Contaminant Permit Addenda) that includes a Risk Reduction Plan under OAR 340-245-0130 (Risk Reduction Plan Requirements) to meet TBACT on all significant TEUs and Source Risk Limits that ensure that the risk from the source will be less than or equal to the Risk Reduction Level; or
(iii) If the risk from the source is greater than the Risk Reduction Level, then the owner or operator must apply for a Toxic Air Contaminant Permit Addendum under OAR 340-245-0100 (Toxic Air Contaminant Permit Addenda) that includes a Risk Reduction Plan under OAR 340-245-0130 (Risk Reduction Plan Requirements) with additional risk reduction measures and Source Risk Limits that ensure that the risk from the source will be less than or equal to the Risk Reduction Level;
(E) If the risk from the source is greater than the Immediate Curtailment Level, then the owner or operator must take immediate action to reduce risk to below the Immediate Curtailment Level.
(2) New or reconstructed source.
(a)(A) The owner or operator of a proposed new or reconstructed source that is required to obtain a Simple or Standard Air Contaminant Discharge Permit, and that is not an exempt source, must also perform a risk assessment, and if applicable, apply for a Toxic Air Contaminant Permit Addendum concurrently with an application for a permit under OAR chapter 340, division 216, before a permit is issued. If DEQ approves the applications, then DEQ will incorporate the toxic air contaminant permit conditions directly into the new Simple or Standard Air Contaminant Discharge Permit and will not issue a separate Toxic Air Contaminant Permit Addendum.
(B) DEQ may require the owner or operator of a proposed new or reconstructed source that is required to obtain a Basic or a General Air Contaminant Discharge Permit to perform a risk assessment and demonstrate compliance with this division, and if applicable, apply for a Toxic Air Contaminant Permit Addendum concurrently with an application for a permit under OAR chapter 340, division 216.
(i) If DEQ approves the applications for a source that will have a Basic Air Contaminant Discharge Permit, then DEQ will incorporate the toxic air contaminant permit conditions directly into the new operating permit.
(ii) If DEQ approves the applications for a source that will be assigned to a General Air Contaminant Discharge Permit, then DEQ will issue a Toxic Air Contaminant Permit Addendum as a source-specific addendum to the new operating permit that will not be incorporated into the operating permit.
(C) Any owner or operator of a proposed new or reconstructed source that is required to perform a risk assessment must:
(i) Assess risk from the source using any of the Level 1 through Level 4 Risk Assessment procedures in sections (8) through (11);
(ii) Assess risk from the source using the emissions inventory submitted under OAR 340-245-0040 (Emissions Inventory)(1); and
(iii) Follow the applicable calculation procedures under OAR 340-245-0200 (Risk Estimates).
(b) The owner or operator of a new or reconstructed source must demonstrate compliance with either paragraph (A) or (B).
(A) The owner or operator must demonstrate that the source is a de minimis source by following the procedure in section (7), or demonstrate that the risk from the source is less than or equal to the TLAER Level. The owner or operator of a source whose risk is less than or equal to the TLAER Level must apply for a Toxic Air Contaminant Permit Addendum under OAR 340-245-0100 (Toxic Air Contaminant Permit Addenda) or an operating permit with Source Risk Limits that ensure that the risk from the source will be less than or equal to the TLAER Level; or
(B) TLAER compliance. If the risk from the new or reconstructed source is greater than the TLAER Level and less than or equal to the Permit Denial Level, and all significant TEUs meet TLAER under OAR 340-245-0220 (TBACT and TLAER Procedures), then the owner or operator must apply for a Toxic Air Contaminant Permit Addendum under OAR 340-245-0100 (Toxic Air Contaminant Permit Addenda) or an operating permit that includes Source Risk Limits that ensure the risk from the source will be less than or equal to the Permit Denial Level.
(3) Other sources. When notified in writing by DEQ, the owner or operator of a source that is not subject to sections (1) or (2) must perform a risk assessment using any of the Level 1 through Level 4 Risk Assessment procedures in sections (8) through (11). DEQ may notify such a source after determining through an investigation or file review that the source may emit toxic air contaminants in quantities that may cause the source’s risk to exceed the Source Permit Level.
(4) A risk assessment for a source must include all TEUs at the source, as of the date that the owner or operator submits an application under OAR 340-245-0100 (Toxic Air Contaminant Permit Addenda) for a Toxic Air Contaminant Permit Addendum, except for the following:
(a) Exempt TEUs;
(b) Gas combustion TEUs, as provided under section (5); and
(c) Aggregated TEUs, except when the owner or operator is requesting approval as a de minimis source under section (7).
(5) Gas combustion exemption. This exemption applies to TEUs that solely combust natural gas, propane, liquefied petroleum gas, and, when approved by DEQ in response to a written request by an owner or operator, pretreated landfill gas and pretreated digester gas or biogas. Risk from toxic air contaminants emitted from such combustion must be calculated and reported in the risk assessment, but the risk from such toxic air contaminants may be treated as follows:
(a) At each exposure location, risk must be reported as two values:
(A) The risk from toxic air contaminants emitted from such combustion of natural gas, propane, liquefied petroleum gas, pretreated landfill gas and pretreated digester gas or biogas ; and
(B) The risk from all other toxic air contaminant emissions;
(b) At each exposure location, the risk from toxic air contaminants emitted solely from the combustion of natural gas, propane, liquefied petroleum gas, pretreated landfill gas and pretreated digester gas or biogas may be excluded from the total risk for the purpose of determining compliance with Risk Action Levels and may be omitted from any requirements determined under a Risk Reduction Plan under OAR 340-245-0130 (Risk Reduction Plan Requirements) if good air pollution control practices are followed; and
(c) Notwithstanding subsections (a) and (b), an owner or operator must include in its risk assessment any toxic air contaminants that are emitted from materials that are contacted by the flame or combustion gases from the combustion of natural gas, propane, liquefied petroleum gas, pretreated landfill gas or pretreated digester gas or biogas. Materials that may emit toxic air contaminants include but are not limited to VOCs combusted in thermal oxidizers and materials dried in direct-contact dryers.
(6) Exempt Source Determination.
(a) To be approved as an exempt source, no later than 30 days after the date that DEQ sends a notice under subsection (1)(a) or with submittal of an application for a new or reconstructed source under subsection (2)(a), the owner or operator must submit information to DEQ that demonstrates that all TEUs at the source are exempt TEUs; and
(b) Upon receipt of a submittal from an owner or operator under subsection (a), DEQ will:
(A) Review the submissions and, if approved, write a memo to the DEQ file for the source summarizing the assessment that will be:
(i) Incorporated into the review report of a permitted source upon permit issuance or renewal; or
(ii) Maintained in the file and tracked in a DEQ database.
(B) Follow the Category I public notice procedure in OAR chapter 340, division 209, prior to approving or denying the request to be considered an exempt source; and
(C) Keep records of exempt sources in a database for the emissions inventory and future communication if RBCs change or other information about risk is received such that toxic air contaminant emissions must be reevaluated.
(7) De minimis Source Determination.
(a) To be approved as a de minimis source, the owner or operator must assess risk at the capacity of each TEU, including aggregated TEUs, using any of the Level 1 through Level 4 Risk Assessment procedures in sections (8) through (11). The owner or operator must submit to DEQ the following:
(A) Information that demonstrates that the source does not exceed the Source Permit Level if the owner or operator is not required to operate and maintain control devices to remain a de minimis source;
(B) Information that demonstrates that the existing source does not exceed the Source Permit Level if the owner or operator is required to operate and maintain control devices to remain a de minimis source, and the existing operating permit includes necessary conditions to operate and maintain the control devices; or
(C) An application for a Toxic Air Contaminant Permit Addendum that demonstrates that the source does not exceed the Source Permit Level if the owner or operator is required to operate and maintain control devices to remain a de minimis source, and the source is a new source or the existing operating permit does not include necessary conditions to operate and maintain the control devices;
(b) Upon receipt of a submittal from an owner or operator under subsection (a), DEQ will:
(A) Review the submissions and, if approved, either:
(i) Write a memo to the DEQ file for the source summarizing the assessment that will be:
(I) Incorporated into the review report of a permitted source upon permit issuance or renewal; or
(II) Maintained in the file and tracked in a DEQ database for sources that meet the criteria in paragraph (a)(A) or (B); or
(ii) Issue a Toxic Air Contaminant Permit Addendum or operating permit, for sources that meet the criteria in paragraph (a)(C);
(B) Follow the Category I public notice procedure in OAR chapter 340, division 209, prior to approving or denying the request to be considered a de minimis source; and
(C) Keep records of de minimis sources in a database for the emissions inventory and future communication if RBCs change or other information about risk is received such that toxic air contaminant emissions must be reevaluated.
(8) Level 1 Risk Assessment. To complete a Level 1 Risk Assessment, the owner or operator must comply with OAR 340-245-0210 (Modeling and Risk Assessment Work Plan Requirements)(1) and then assess risk by using the Level 1 Risk Assessment Tool in OAR 340-245-8050 (Table 5 - Level 1 Risk Assessment Tool Dispersion Factors) Table 5 to determine toxic air contaminant concentrations at approved exposure locations.
(a) The owner or operator must follow the directions for using the Level 1 Risk Assessment Tool described in OAR 340-245-0200 (Risk Estimates)(2);
(b) For sources with multiple stacks, stacks must either be considered individually using OAR 340-245-8050 (Table 5 - Level 1 Risk Assessment Tool Dispersion Factors) Tables 5A and 5B with risk calculated as the summation of individual stack risk, or the stacks combined into a single stack in a manner approved by DEQ and risk calculated for that single stack;
(c) A Level 1 Risk Assessment will not be approved if the source is located near elevated terrain that DEQ determines could invalidate the assumptions used to develop the Level 1 Risk Assessment Tool; and
(d) If DEQ concludes that the source complies with this division based on a Level 1 Risk Assessment, then DEQ will follow the Category II public notice procedure in OAR chapter 340, division 209 for issuance of the Toxic Air Contaminant Permit Addendum.
(9) Level 2 Risk Assessment. To complete a Level 2 Risk Assessment, the owner or operator must comply with OAR 340-245-0210 (Modeling and Risk Assessment Work Plan Requirements)(1) and then assess risk by submitting a modeling protocol, conducting modeling, and performing a risk assessment. The owner or operator must use AERSCREEN or comparable screening model approved by DEQ to determine air concentrations at approved exposure locations. If DEQ concludes that the source complies with this division based on a Level 2 Risk Assessment, then DEQ will follow the Category II public notice procedure in OAR chapter 340, division 209 for issuance of the Toxic Air Contaminant Permit Addendum.
(10) Level 3 Risk Assessment. To complete a Level 3 Risk Assessment, the owner or operator must comply with OAR 340-245-0210 (Modeling and Risk Assessment Work Plan Requirements) and then assess risk by submitting a modeling protocol and a risk assessment work plan, conducting modeling, and performing a risk assessment. The owner or operator must use AERMOD or comparable model approved by DEQ to determine air concentrations at approved exposure locations. If DEQ concludes that the source complies with this division based on a Level 3 Risk Assessment, then DEQ will follow the Category III public notice procedure in OAR chapter 340, division 209 for issuance of the Toxic Air Contaminant Permit Addendum.
(11) Level 4 Risk Assessment. To complete a Level 4 Risk Assessment, the owner or operator must comply with OAR 340-245-0210 (Modeling and Risk Assessment Work Plan Requirements) and then assess risk by submitting a modeling protocol and a risk assessment work plan, conducting modeling, and performing a risk assessment. The owner or operator must use AERMOD or comparable model approved by DEQ to determine air concentrations at approved exposure locations. The risk assessment must include toxicity and bioaccumulation assessments, and may include proposed modifications to default exposure assumptions as specified in OAR 340-245-0210 (Modeling and Risk Assessment Work Plan Requirements). If DEQ concludes that the source complies with this division based on a Level 4 Risk Assessment, then DEQ will follow the Category III public notice procedure in OAR chapter 340, division 209 for issuance of the Toxic Air Contaminant Permit Addendum.
(12) DEQ may require the owner or operator of a source to conduct and submit an additional multipathway risk evaluation for any level of risk assessment if DEQ determines that airborne deposition of chemicals could be important for scenarios not included in the default multipathway adjustment factor assumptions used in the original risk assessment for the source.

Source: Rule 340-245-0050 — Risk Assessment Procedures, https://secure.­sos.­state.­or.­us/oard/view.­action?ruleNumber=340-245-0050.

340‑245‑0005
Purpose and Overview 340‑245‑0010
Applicability and Jurisdiction 340‑245‑0020
Definitions 340‑245‑0022
Abbreviations and Acronyms 340‑245‑0030
Submittal and Payment Deadlines 340‑245‑0040
Emissions Inventory 340‑245‑0050
Risk Assessment Procedures 340‑245‑0060
Toxic Emissions Units 340‑245‑0100
Toxic Air Contaminant Permit Addenda 340‑245‑0110
Source Risk Limits 340‑245‑0120
Community Engagement 340‑245‑0130
Risk Reduction Plan Requirements 340‑245‑0140
Pollution Prevention 340‑245‑0150
Postponement of Risk Reduction 340‑245‑0200
Risk Estimates 340‑245‑0210
Modeling and Risk Assessment Work Plan Requirements 340‑245‑0220
TBACT and TLAER Procedures 340‑245‑0230
Toxic Air Contaminant Monitoring Requirements 340‑245‑0300
Toxicity Reference Values 340‑245‑0310
Process for Updating Lists of Regulated Toxic Air Contaminants and Their Risk-Based Concentrations 340‑245‑0320
Standards and Criteria for Noncancer Risk Action Levels for Existing Contamination Sources 340‑245‑0400
Cleaner Air Oregon Fees 340‑245‑8010
Table 1 - Risk Action Levels 340‑245‑8020
Table 2 - Toxic Air Contaminant Reporting List 340‑245‑8030
Table 3 - Toxicity Reference Values 340‑245‑8040
Table 4 - Risk-Based Concentrations 340‑245‑8050
Table 5 - Level 1 Risk Assessment Tool Dispersion Factors 340‑245‑9000
Colored Art Glass Manufacturing Facility Rules 340‑245‑9010
Colored Art Glass Manufacturing Facility Rules 340‑245‑9015
Colored Art Glass Manufacturing Facility Rules 340‑245‑9020
Colored Art Glass Manufacturing Facility Rules 340‑245‑9030
Colored Art Glass Manufacturing Facility Rules 340‑245‑9050
Colored Art Glass Manufacturing Facility Rules 340‑245‑9060
Colored Art Glass Manufacturing Facility Rules 340‑245‑9070
Colored Art Glass Manufacturing Facility Rules 340‑245‑9080
Colored Art Glass Manufacturing Facility Rules
Last Updated

Jun. 8, 2021

Rule 340-245-0050’s source at or​.us