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→Determine maximum overall depth
==Determine 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. Determine what the pipe diameter needs to be and assign appropriate depth of reservoir.
*Step 2. Decide on the underdrain pipe diameter.
*Step 3. Determine maximum possible storage reservoir depth (''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:
*''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.
==Calculate the 1 dimensional water storage capacity==
* Step 6. Multiply the depth of each separate component by the void ratio and then sum the total.
==Calculate the required total storage capacity==
<math>Storage=RVC_T\times Catchment area\times0.95</math>
{{Plainlist|1=Where:
*''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.}}
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