4 The record articles

Cleaner Air Oregon Regulation: Call to Action and Lessons Learned So Far

Posted: August 28th, 2019

Authors: Dan D. 

By now I’m sure you’ve heard of or already been involved in some aspect of Oregon Department of Environmental Quality’s (DEQs) new Cleaner Air Oregon (CAO) risk-based toxic air contaminant permitting program.  You may also be asking yourself, when am I going to get “called-in” and should I do anything before I get “called-in?”  DEQ recently (March 2019) completed their call-in prioritization analysis utilizing 2016 air toxics emissions inventories, their Level 1 Risk Assessment Tool, demographic statistics, and “other” criteria for prioritization to place all facilities in Oregon into 4 Prioritization Groups.  Group 1 sources should expect to be called-in this year and Group 2 sources should expect to be called in next year.

Read CAO Permitting Process

Once a facility is called-in, a regulatory clock starts ticking on a number of CAO requirements depending on the type of analysis (Level 1, 2, 3, or 4) that you opt to evaluate your facility under.  The post call-in deadlines make it critical to get started on your CAO analysis before you’re called-in.  Getting started before you’re called-in will allow time to determine what level of analysis to utilize, identify and prioritize refinements to your air toxics emissions estimates, identify if public participation is likely, identify if emissions controls or a toxic best available control technology (TBACT) analysis is necessary, or if ambient monitoring is necessary all before the clock starts ticking.  Having time to make these decisions and evaluate the impacts will help to minimize impacts on operational flexibility and potential capital costs down the road.

ALL4 offers the following insights most likely to impact your evaluation based on our CAO experience so far:

  1. The Level 1 Risk Assessment Tool can be highly conservative especially for the following scenarios:
    • Short distances (i.e., less than 100 meters) from emissions sources to residential receptors,
    • Short stacks, and
    • Fugitive emissions sources and especially large fugitive emissions sources (i.e., waste water treatment systems).
  2. A few uncontrolled emissions sources and/or emissions sources not subject to a National Emissions Standard for Hazardous Air Pollutants (NESHAP) Maximum Available Control Technology (MACT) standard can drive facility-wide risk levels.
  3. 24-Hour acute metal air toxic emissions can drive risk assessments for low emitters because of conservative Risk Based Concentration (RBC) thresholds.
  4. Risk Action Levels (RALs) are based on combining the impacts from all air toxics at each receptor and therefore are additive.
  5. The CAO permitting program includes requirements for community engagement with required public meetings if certain RAL are exceeded.


Based on experience to-date I’d expect most facilities in the Group 1 and Group 2 prioritization to need to conduct a Level 3 CAO analysis which involves the use of U.S. EPA’s recommended air dispersion model AERMOD.  If you have never completed an AERMOD analysis for your facility this is another reason to get started ahead of your call-in to allow time to develop the modeling inputs necessary to run AERMOD.  If you’re interested in getting started on a preliminary CAO analysis before you’re called-in or have any questions about the process please feel free to give me a call at 610.422.1118 or email me at ddix@all4inc.com.  Don’t be surprised if you hear from us directly as we seek to communicate what we have learned so far, identify where facilities may need assistance, and to potentially “compare notes” with other facilities that have started the CAO process.
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