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*The applicable infiltration coefficient (''q'') is calculated by applying a [[Infiltration: Testing|safety factor to the measured infiltration rate]].*Determine the impervious catchment area (''I''), and outline the location of the bioretention facility. To begin with, budget for at least 10% of the total catchment area to be required for the BMP. The area of the facility on the ground will be 'P' (pervious).*Unless the biomedia fill material has been tested and certified otherwise, a porosity value (''n'') of 0.35 may be assumed (i.e. void ratio 35%).*Bioretention facilities are usually between 0.5 m and 1.25 m deep, owing to construction considerations. Determine the maximum available depth of the facility (''d<sub>f max</sub>'') from the site constraints. The [[Infiltration]] page lists these. Identify the duration (''D'') and intensity (''i'') of design storm(s).Calculate the required facility area (''P'').<math>d_{f}=\frac{D\left (\left [ I/P \right ]i-q \right )}{n}</math><math>\left [ I/P \right ]= \frac{Cn+qD}{in}</math><strong>[[Media:Infiltration Sizing.xlsx|Download .xlsx calculation tool]]</strong>
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<math>d=\frac{D\left (\left [ I/P \right ]i-q \right )}{n}</math>
<math>d=\frac{D\left (\left [ I/P \right ]i-q \right )}{n}</math>
To calculate the require facility area or footprint where the depth is constrained:
<math>P=\frac{IiD}{nd+qD}</math>
<strong>[[Media:Infiltration Sizing.xlsx|Download .xlsx calculation tool]]</strong>
[[category: modeling]]
[[category: modeling]]
[[category: infiltration]]
[[category: infiltration]]