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| ==Size a bioretention cell for constrained depth== | | ==Size a bioretention cell for constrained depth== |
− | Determine if there is a constraint to the depth (''d<sub>T</sub>'') of the bioretention practice:
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| {{:Depth to GW}} | | {{:Depth to GW}} |
− | |'''or''' if the land area is limited, determine the I/P ratio::<math>R=\frac{A_{c}}{A_{p}}</math> | + | If there is a constraint to the depth (''d<sub>T</sub>'') of the bioretention practice calculate the require facility area or footprint where the depth is constrained, as: |
| + | <math>A_{p}=\frac{IiD}{V_{R}d+f'D}</math> |
| + | {{Plainlist|1=Where: |
| + | *''D'' = Duration of design storm in hrs |
| + | *''i'' = Intensity of design storm in mm/hr |
| + | *''f''' = [[design infiltration rate]] in mm/hr |
| + | *''V<sub>R</sub>'' = Void ratio (porosity), as measured (or default to 0.35 for all aggregates) |
| + | *''R'' = Ratio of catchment area (''A<sub>c</sub>'') to BMP footprint area (A<sub>p</sub>). |
| + | *''A<sub>p</sub>'' = Area of the infiltration practice in m<sup>2</sup> |
| + | *''A<sub>c</sub>'' = Catchment area in m<sup>2</sup> |
| + | *''d<sub>T</sub>'' = Total depth of the infiltration practice in m.}} |
| + | |
| + | ==Size a bioretention cell for constrained ground area== |
| + | If the land area is limited, determine the ratio: |
| + | :<math>R=\frac{A_{c}}{A_{p}}</math> |
| + | |
| {{Plainlist|1= Where: | | {{Plainlist|1= Where: |
| *''R'' = Ratio of catchment area (''A<sub>c</sub>'') to BMP footprint area (A<sub>p</sub>) syn. I/P ratio. | | *''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> | | *''A<sub>p</sub>'' = Area of the infiltration practice in m<sup>2</sup> |
| *''A<sub>c</sub>'' = Catchment area in m<sup>2</sup>}} | | *''A<sub>c</sub>'' = Catchment area in m<sup>2</sup>}} |
− | |-
| + | |
− | !colspan="2" style="text-align: center;"|Then
| + | Calculate the required depth (d<sub>T</sub>), as: |
− | |-
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− | |To calculate the require facility area or footprint where the depth is constrained:
| |
− | <math>A_{p}=\frac{IiD}{V_{R}d+q'D}</math> | |
− | |To calculate the required depth, where the area of the facility is constrained:
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| <math>d=\frac{D\left[Ri-q'\right]}{V_{R}}</math> | | <math>d=\frac{D\left[Ri-q'\right]}{V_{R}}</math> |
| {{#widget:WolframAlpha|id=88d135fd5507a36a9770deaa8106c975}} | | {{#widget:WolframAlpha|id=88d135fd5507a36a9770deaa8106c975}} |
− | |}
| + | |
| {{Plainlist|1=Where: | | {{Plainlist|1=Where: |
| *''D'' = Duration of design storm in hrs | | *''D'' = Duration of design storm in hrs |