Changes

|''i''||mm/hr||Intensity of design storm (for MOECC volume based calculations use whole storm depth (link to map))

|''i''||mm/hr||Intensity of design storm (for MOECC volume based calculations use whole storm depth (link to map))

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|''q''||mm/hr||Infiltration coefficient of the underlying native soil, calculated from measured [[Infiltration: Testing| infiltration rate]] and applied [[Infiltration|safety factor]]

|''f'''||mm/hr||Design infiltration rate of the underlying native soil, calculated from measured [[Infiltration: Testing| infiltration rate]] and applied [[Infiltration|safety factor]]

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|''n''||-||Porosity, as measured (or default to 0.35 for all aggregates).<br> *Note: For systems that have significant storage in clear open chambers, an effective porosity value (''n<nowiki>'</nowiki>'') may be estimated for the whole installation and used in the calculations below. Effective porosity will vary according to the geometry of the storage chambers, so advice should be sought from product manufacturers. Permit applications should include the basis for ''n<nowiki>'</nowiki>'' estimates.

|''n''||-||Porosity, depth-weighted mean of all fill materials.<br> *Note: For systems that have significant storage in clear open chambers, an effective porosity value (''n<nowiki>'</nowiki>'') may be estimated for the whole installation and used in the calculations below. Effective porosity will vary according to the geometry of the storage chambers, so advice should be sought from product manufacturers. Permit applications should include the basis for ''n<nowiki>'</nowiki>'' estimates.

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|''I''||m²||Impermeable area i.e. catchment

|''I''||m²||Impermeable area within the catchment

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|''d''||m||depth of infiltration facility or BMP

|''d''||m||Depth of the infiltration BMP, total of all components

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|''P''||m²||Permeable area i.e. footprint area of the facility or BMP

|''P''||m²||Permeable area i.e. footprint area of the infiltration BMP

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|''K''||mm/hr||Infiltration coefficient of the filter media or fill used in the infiltration facility  

|''K''||mm/hr||Saturated hydraulic conductivity of the filter media or fill used in the infiltration BMP  

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:<math>d=a[e^{\left ( -bD \right )} -1]</math>

:<math>d=a[e^{\left ( -bD \right )} -1]</math>

Where

Where

<math>a=\frac{P}{x}-\frac{i I}{P q}</math>

<math>a=\frac{P}{x}-\frac{i I}{P f'}</math>

and  

and  

<math>b=\frac{xq}{nP}</math>

<math>b=\frac{xf'}{nP}</math>

(The rearrangement to calculate the required footprint area of the facility for a given depth using three dimensions of underground infiltration is not available at this time. Elegant submissions are invited.)

(The rearrangement to calculate the required footprint area of the facility for a given depth using three dimensions of underground infiltration is not available at this time. Elegant submissions are invited.)

In some very constrained sites, the surface area of the BMP may be limited, in this case the required depth of cell or trench can be calculated.

In some very constrained sites, the surface area of the BMP may be limited, in this case the required depth of cell or trench can be calculated.

Note that in most cases the results of this calculation will be very similar to those of the above equation using 3D infiltration.  

Note that in most cases the results of this calculation will be very similar to those of the above equation using 3D infiltration.  

:<math>d=\frac{D\left[\left( \frac{I}{P} \right )i-q \right]}{n}</math>

:<math>d=\frac{D\left[\left( \frac{I}{P} \right )i-f' \right]}{n}</math>

==To calculate the require facility area or footprint where the depth is constrained (1D)==

==To calculate the require facility area or footprint where the depth is constrained (1D)==

In many locations throughout Ontario, there may be limited depth of soil available into which stormwater may be infiltrated. In this case the required storage needs to be distributed more widely across the landscape. The overall are of BMP required can be calculated:

In many locations throughout Ontario, there may be limited depth of soil available into which stormwater may be infiltrated. In this case the required storage needs to be distributed more widely across the landscape. The overall are of BMP required can be calculated:

<math>P=\frac{IiD}{nd+qD}</math>

<math>P=\frac{IiD}{nd+f'D}</math>

==Time for infiltration of surface ponded water==

==Time for infiltration of surface ponded water==