AIR DISPERSION MODEL
The dispersion models that may be used are those in the latest edition of the US-EPA Guideline on Air Quality Models (Appendix W to Part 51).
Using the model, the operator must calculate the concentration in the atmosphere of each contaminant emitted for which a limit is prescribed by sections 75 and 153 and in Schedules G and K.
All the values of the parameters required for the model must be listed.
The concentration of a contaminant in the atmosphere for a single source must be calculated by modeling with one of the following methods:
(a) a simple model, called a level 1 model, for a single source; or
(b) a multi-source complex model, called a level 2 model, simulating a single source.
For the sum of the concentration of contaminants calculated with a level 1 model and of the initial concentration exceeds 80% of the limit, modeling with a level 2 model is required.
If the establishment has several emission sources, the concentrations of contaminants in the atmosphere must be calculated using a level 2 model.
By using the concentration obtained for the calculation with a level 1 model, the daily and annual concentrations are obtained in the following manner:
Cdaily = CMAX-H x 0.24
CAN = CMAX-H x 0.04
where Cdaily is the daily concentration, CAN is the annual concentration and CMAX-H is the highest hourly concentration calculated.
For a level 2 model, the operator must use
(a) 5 years of complete meteorological data representative of the location of the establishment;
(b) the overall regional meteorological data supplied by the Ministère du Développement durable, de l’Environnement et des Parcs for the region where the establishment is located; or
(c) the overall general meteorological data supplied by the Ministère du Développement durable, de l’Environnement et des Parcs if the data described in paragraph a or b above does not exist.
The operator must describe all the calculations made using the meteorological data to obtain the specific parameters that the use of the model requires.
The annual and daily concentrations for each calculation point are obtained in the following manner, according to the meteorological data used and described above:
Meteorological Annual Daily
data concentration concentration
Complete and Average of the Average of the 24 hourly
representative of the 8,760 concentrations concentrations calculated
location of the calculated, for for every day of
establishment for each year every year
Overall regional Average of the Average of the 24 hourly
meteorological data 8,760 concentrations concentrations calculated
supplied by the calculated for every day
et des Parcs
Overall general From the highest hourly From the highest hourly
meteorological data concentration calculated: concentration calculated:
supplied by the CAN = CMAX-H x 0.04, Cdaily = CMAX-H x 0.24
Ministère du where CAN is the annual where Cdaily is the daily
Développement durable, concentration and CMAX-H concentration and CMAX-H
de l’Environnement is the highest hourly is the highest hourly
et des Parcs if the concentration calculated concentration calculated
data described above
does not exist
In the case of a contaminant for which column 1 of Schedule K provides that the limit is established over a period of less than 1 hour, the concentration is calculated using the following formula:
C(T) = CMAX-H x 0.97 T - 0.25
where T is the time in hours and CMAX-H is the maximum concentration for 1 hour.
The operator must take into account the topography if the difference in altitude between the highest and the lowest points of the region for which the calculations are made is equal to or greater than 10 m.
The initial concentrations of contaminants into the atmosphere, without the contribution of the source or sources considered for the modeling, must be added to the concentrations calculated. The resulting concentrations must be presented to enable comparison with the limit values prescribed by Schedules G and K.
The operator must retain the following information for a minimum of 5 years:
(a) one or more maps showing the region for which the calculations have been made, indicating the calculation points and their altitude, the establishment and its property limits, and the pertinent geographical, physical and human elements. Each map must include a scale and the direction of geographical North;
(b) a top view and a sectional view of the establishment’s buildings and the location of the sources;
(c) the physical features of each source and the operating characteristics;
(d) for each contaminant, maps showing the modeling calculation results in the form of isopleth curves for each year of calculation;
(e) for each contaminant, a table showing the location of each calculation point and the concentrations modelized, for each year of calculation;
(f) for each contaminant, a table showing the maximum annual concentrations calculated for all the calculation points and years and their locations; the initial concentrations and the sum of the maximum concentrations calculated and the initial concentrations; and
(g) the input data required for the operation of the model in a form compatible with its use (model input file) for the modeling carried out.