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The target [[drainage time]] for the internal storage of an infiltration facility is typically between 48 and 72 hours or based on the average inter-event period for the location. See [[Drainage time]] for more information about how inter-event periods vary across Ontario and to help select what is suitable for the site. <br>
The target [[drainage time]] for the internal storage of an infiltration facility is typically between 48 and 72 hours or based on the average inter-event period for the location. See [[Drainage time]] for more information about how inter-event periods vary across Ontario and to help select what is suitable for the site. <br>
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Try the Darcy Drainage calculator tool for estimating drainage time assuming either one or three-dimensional drainage from the practice: <br>
{{Clickable button|[[Media:Darcy drainage.xlsx|Download drainage time calculator(.xlsx)]]}}<br>
==To calculate the required depth, where the area of the facility is constrained (3D drainage)==
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:
:<math>d=a[e^{\left ( -bD \right )} -1]</math>
Where
<math>a=\frac{Ap}{x}-\frac{i Ai}{x f'}</math>
and
<math>b=\frac{xf'}{nAp}</math>
(The rearrangement to calculate the required footprint area of the facility for a given depth using three dimensional drainage is not available at this time. Elegant submissions are invited.)<br>
<br>
Try the Darcy drainage calculator tool for estimating drainage time assuming either one or three-dimensional drainage from the practice: <br>
{{Clickable button|[[Media:Darcy_drainage.xlsx|Download the Darcy drainage time calculator]]}}<br>
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For some geometries (e.g. particularly deep facilities or linear facilities), it preferable to account for lateral infiltration.
For some geometries (e.g. particularly deep facilities or linear facilities), it preferable to account for lateral infiltration.