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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, using the table above.
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*Step 2: Select an underdrain pipe diameter (typically 100 - 200 mm), assign this as an 'embedding' depth. 
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*Step 3: Calculate the maximum possible storage reservoir depth beneath the pipe (''d<sub>s</sub>''):
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<math>d_{s}=f'\times38.4</math>
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{{Plainlist|1=Where:
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*''f''' = Design infiltration rate in mm/hr, and
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*38.4 comes from multiplying desired drainage time of 96 hours by void ratio of 0.4}}
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===Additional step for system without underdrain===
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*Step 4: Determine maximum permissible ponding depth (''d<sub>p</sub>''):
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<math>d_{p}=f'\times19.2</math>
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{{Plainlist|1=Where:
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*''f''' = Design infiltration rate in mm/hr, and
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*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.}}
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* 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==
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* Step 6: Multiply the depth of each separate component by the void ratio and then sum the total to find the 1 dimensional storage (in mm).
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* Step 7: Calculate the required total storage (m<sup>3</sup>):
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<math>Storage=RVC_T\times A_c\times C\times 0.1</math>
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{{Plainlist|1=Where:
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*''RVC<sub>T</sub>'' is the Runoff volume control target (mm),
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*''A<sub>c</sub>'' is the catchment area (Ha),
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*''C'' is the runoff coefficient of the catchment area, and
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* 0.1 is the units correction between m<sup>3</sup> and mm.Ha.}}
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* Step 8. Divide required storage (m<sup>3</sup>) by the 1 dimensional storage (in m) to find the required footprint area (''A<sub>p</sub>'') for the bioretention in m<sup>2</sup>.
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* Step 9. Calculate the peak flow rate (''Q<sub>p</sub>'', in L/s) through the filter media:
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