Incoming Dispersion Modelling Updates – What it Means for You

Terry Lam, P. Eng.  – Specialist, Compliance & Permitting
October 1, 2015

The Ministry of the Environment and Climate Change (MOECC) will be updating the approved versions of the AERMOD and ASHRAE method dispersion models later this month through the publication of a notice on the Environmental Registry. A pre-notification of the incoming update was sent to stakeholders earlier this year. The approved versions will now be AERMOD version 14134 and the method described in the AHSRAE 2011 Handbook, chapter 44.  A change in model version has the potential to result in increased point-of-impingement concentration (POI) predictions. This means that on the extreme end of the impacts, a facility could move from compliance to non-compliance as a result of the change, potentially triggering notification and abatement requirements. Other considerations include:

  • Facilities required to update an Emissions Summary and Dispersion Modelling (ESDM) report annually (e.g. Schedule 4 or 5 facilities) will need to use the newly approved versions for their updated report due March 31. This might result in additional costs for facilities that do not undergo year-to-year changes and previously updated simply with an administrative note.

  • Facilities with Environmental Compliance Approvals (ECAs) with Limited Operational Flexibility are required to keep an up-to-date ESDM report that demonstrates compliance. This means that the ESDM report would need to be updated to use the new versions once they are in effect. Additionally, increases to POI predictions for contaminants without standards could trigger the requirement to submit a toxicological assessment request to the MOECC depending on interpretation.

  • The MOECC has indicated that existing ECA applications which have not yet been approved may be retroactively required to reassess using the new versions. This means that there is a potential for additional unanticipated costs if your facility currently has an ECA application using an older version in queue.  The MOECC has also indicated that they will phase in new versions on an on-going basis. This creates additional uncertainty in the ECA application process as the time in queue is often longer that the lifespan of a model version. There is now a real risk that the assessment you submit in support of your ECA application will be obsolete and require update by the time it gets reviewed.

Need assistance? ORTECH can help you:

  • Prepare or update an ESDM report
  • Use an approved dispersion model to assess your facility
  • Assess the impact of an incoming model update
  • Support an existing ECA application that requires updated modelling