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| ==Calculate the maximum overall depth== | | ==Calculate the maximum overall depth== |
− | *Step 1. Determine what the planting needs are and assign appropriate depth of media. | + | *Step 1: Determine what the planting needs are and assign appropriate depth of media. |
− | *Step 2. Decide on the underdrain pipe diameter. | + | *Step 2: Decide on the underdrain pipe diameter. |
− | *Step 3. Determine maximum possible storage reservoir depth beneath the pipe (''d<sub>S</sub>''): | + | *Step 3: Determine maximum possible storage reservoir depth beneath the pipe (''d<sub>S</sub>''): |
| <math>d_{S}=f'\times38.4</math> | | <math>d_{S}=f'\times38.4</math> |
| {{Plainlist|1=Where: | | {{Plainlist|1=Where: |
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| ===Additional step for system without underdrain=== | | ===Additional step for system without underdrain=== |
− | *Step 4. Determine maximum permissible ponding depth (''d<sub>P</sub>''): | + | *Step 4: Determine maximum permissible ponding depth (''d<sub>P</sub>''): |
| <math>d_{P}=f'\times19.2</math> | | <math>d_{P}=f'\times19.2</math> |
| {{Plainlist|1=Where: | | {{Plainlist|1=Where: |
| *''f''' = Design infiltration rate in mm/hr, and | | *''f''' = Design infiltration rate in mm/hr, and |
| *19.2 comes from multiplying desired drainage time of 48 hours by void ratio of 0.4. Note that conceptually the drainage of the ponded area is limited by ex-filtration at the base of the practice.}} | | *19.2 comes from multiplying desired drainage time of 48 hours by void ratio of 0.4. Note that conceptually the drainage of the ponded area is limited by ex-filtration at the base of the practice.}} |
− | * Step 5. Sum total depth of bioretention and compare to available space above water table and bedrock. Adjust if necesary. | + | * Step 5: Sum total depth of bioretention and compare to available space above water table and bedrock. Adjust if necesary. |
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| ==Calculate the remaining dimensions== | | ==Calculate the remaining dimensions== |
− | * Step 6. Multiply the depth of each separate component by the void ratio and then sum the total. | + | * Step 6: Multiply the depth of each separate component by the void ratio and then sum the total. |
| + | * Step 7: Calculate the required total storage (in m<sup>3</sup>): |
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− | ==Calculate the required total storage capacity==
| + | <math>Storage=RVC_T\times Catchment area\times0.095</math> |
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− | <math>Storage=RVC_T\times Catchment area\times0.95</math> | |
| {{Plainlist|1=Where: | | {{Plainlist|1=Where: |
− | *''f''' = Design infiltration rate in mm/hr, and | + | *''RVC<sub>T</sub>''' = Runoff volume control target (mm), and |
− | *19.2 comes from multiplying desired drainage time of 48 hours by void ratio of 0.4. Note that conceptually the drainage of the ponded area is limited by ex-filtration at the base of the practice.}} | + | * Area (Ha) |
| + | * 0.095 is the product of a typical runoff coefficient for impermeable surfaces (0.95) and the units correction between m<sup>3</sup> and mm.Ha.}} |
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