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| Then calculate the required depth (d<sub>T</sub>), as: | | Then calculate the required depth (d<sub>T</sub>), as: |
| <math>d=\frac{D \left[ (R\times i)-f'\right]}{V_{R}}</math> | | <math>d_{T}=\frac{D \left[ (R\times i)-f'\right]}{V_{R}}</math> |
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| {{Plainlist|1=Where: | | {{Plainlist|1=Where: |
| *''D'' = Duration of design storm in hrs | | *''D'' = Duration of design storm in hrs |
| *''i'' = Intensity of design storm in mm/hr | | *''i'' = Intensity of design storm in mm/hr |
| *''q''' = Infiltration coefficient in mm/hr (accounting for SCF) | | *''f''' = Design infiltration rate in mm/hr |
| *''SCF'' = Safety correction factor
| | *''V<sub>R</sub>'' = Void ratio |
| *''V<sub>R</sub>'' = Void ratio (porosity), as measured (or default to 0.35 for all aggregates) | | *''d<sub>T</sub>'' = Depth of infiltration practice in m.}} |
| *''R'' = Ratio of catchment area (''A<sub>c</sub>'') to BMP footprint area (A<sub>p</sub>) syn. I/P ratio. | |
| *''A<sub>p</sub>'' = Area of the infiltration practice in m<sup>2</sup>
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| *''A<sub>c</sub>'' = Catchment area in m<sup>2</sup>
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| *''d'' = Depth of infiltration practice in m.}}
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| The following equations assume that infiltration occurs primarily through the base of the facility. | | The following equations assume that infiltration occurs primarily through the base of the facility. |
| They may be easily applied for any shape and size of infiltration facility, in which the reservoir storage is mostly in an aggregate. | | They may be easily applied for any shape and size of infiltration facility, in which the reservoir storage is mostly in an aggregate. |