Latest Updates to Ontario’s Air Dispersion Models

Presentation to the External Working Group

April 4, 2019

Outline• Phasing out of Reg 346 Models and Schedule 2

Standards

• Suburban Regional Meteorological Data

• Potential Updates to AERSURFACE

• Modelling Portable Equipment

• Terrain Files (Digital Elevation Models (DEM) data)

LJ(8

Slide 2

LJ(8 I added this slide so that audience will know what's coming.Liu, Jinliang (MECP), 2019-04-01

Phasing out of Reg 346 Models and Schedule 2 Standards

• Schedule 2 standards1 in O.Reg. 419/05 are in effect until Feb 1st 2020– Until then, Reg 346 models or AERMOD (with conversion factor)

may be used to demonstrate compliance.• As of Feb 1st, 2019, facilities required to make application for

an ECA for which Schedule 2 standards still apply must prepare their ESDM reports as if Schedule 3 standards apply– SCREEN3 or AERMOD2 must be used to demonstrate

compliance with Schedule 3• Applications submitted with Reg 346 models or AERMOD/SCREEN3

(with conversion factors) to demonstrate compliance with Schedule 2 standards will be returned

• As of Feb 1st, 2020, Schedule 3 standards apply to all facilities– Reg 346 models can no longer be used

1 Note that facilities NOT listed in Schedules 4 and 5 of the Regulation are subject to section 19 of the Regulation (Schedule 2 air standards) unless they have been issued a notice to have section 20 of the Regulation (Schedule 3 air standards) apply in advance or they have included in their EASR ESDM report supplement a statement by a licensed engineering practitioner confirming that the EASR ESDM report has been prepared as if section 20 of that Regulation applies to the contaminant(s).2Facitities can request s7(1) ministry approval to use other non-regulatory models (not including Reg. 346 model)

Suburban Regional Meteorological Data

To assist in the transition to the more advanced models, the ministry will be posting additional regional meteorological datasets on “Ontario.ca”.o Currently, regional meteorological datasets are available for 5

regions in Ontario for three different types of land use (crop, rural, and urban).

o In many instances the land use in the vicinity of facilities is more suburban-like than urban or rural.o Many applicants are using the “urban” category inappropriately

o An additional land use category called “suburban” has been added for all 5 regionso Intended to be used by facilities located in areas with suburban land

use characteristics (e.g. much of Greater Toronto Area’s “905” region).o The intent of this new LU profile is to fill in the gap between the "urban"

and rural land use profiles.

Suburban Regional Meteorological Data

• What do we mean by suburban?

Suburban Regional Meteorological Data

• There is no specific definition of "suburban".• The suburban category provides more representative surface characteristics

in areas that have a mix of commercial and low intensity (low rise, single family) residential uses.

• In particular, somewhat higher surface roughness than rural “crops” data sets

• Can still use “urban” sources with this meteorology for heat island effects on the nighttime boundary layer, as per guidance in the Air Dispersion Modelling Guideline for Ontario (ADMGO)

Use of the Regional Meteorological Data Sets

• All regional datasets including “suburban” Land Use type are not intended for use at shoreline locations or near water bodies (lakes, rivers) (e.g. within 3 km radius).

Potential Updates to AERSURFACE

• We use AERSURFACE to process our land use/surface characteristics. – EPA may be changing some of the calculation

methodologies (e.g. estimation Z0)

– MECP is in process of reviewing and evaluating the potential changes to AERSURFACE

• US EPA revisions are still in “proposed DRAFT” stage

Modelling Portable Equipment

• Due to phase out of O.Reg.346 model, all ECA applications (new or amended) for portable units must be completed using either SCREEN3 or AERMOD.– If using SCREEN3, must be used as intended-

“screening” approach (e.g. add maxima for multiple sources)

– A composite “pseudo” met set was developed to reduce amount of run time and processing time for portable equipment (e.g. that can be used anywhere in Ontario).

Modelling Portable EquipmentTo minimize the modelling efforts for portable units, EMRB proposes the following approach which Practitioners can use: • To address potential impacts from terrain, proponents should use a modelling setup that

utilizes multiple vertical levels of polar receptors with flag-pole heights, spacing, source setup.

– General methodology originally presented to Air Practitioners by RWDI in 2016

• To capture as many meteorological conditions as possible, EMRB has developed a screening meteorological dataset by combining all regional datasets into a single set. Since all data included in this screening dataset is regional data, no s13(1) approval is needed.

– A composite “pseudo” data set that represents 120 years of data– Runs typically completed in ~12 hrs (+/-) using multi-processor (MPI) options*– Removal of met anomalies is difficult but can be done– A draft data set and guidance will be shared (shortly) with a small group of Practitioners for

testing• contact EMRB if you have experience with modelling portable units and want to be included in this

testing

• EMRB intends to eventually release the above meteorological data set along with more detailed instructions on the above modelling approaches once comments are received on the draft data set and guidance

With this approach, proponents would only need to carry out a single model run for each contaminant.

* With 7 volume sources and ~40,000 receptors

Terrain Data – DEM Files

• EMRB is in the process of updating the terrain files on Ontario.ca to DEM version 3– Terrain files are currently based on DEM

version 1– We have noted various issues with DEM

version 1 files• Particularly near shorelines of Great Lakes

• MECP is working towards replacing the files in the coming months

Questions?