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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:
===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.
==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>):
<math>Storage=RVC_T\times Catchment area\times0.095</math>
<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.}}