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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, using the table above. |
− | *Step 2: Decide on the underdrain pipe diameter. | + | *Step 2: Select an underdrain pipe diameter (typically 100 - 200 mm), assign this as an 'embedding' depth. |
− | *Step 3: Determine maximum possible storage reservoir depth beneath the pipe (''d<sub>s</sub>''): | + | *Step 3: Calculate the 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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| *''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 necessary. | + | * Step 5: Sum total depth of bioretention, and compare to available space above water table and bedrock. Adjust if necessary. |
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| ==Calculate the remaining dimensions== | | ==Calculate the remaining dimensions== |