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Line 39: − *Step 1: Determine what the planting needs are and assign appropriate depth of media, using the table above. − *Step 2: Select an underdrain pipe diameter (typically 100 - 200 mm), assign this as an 'embedding' depth. − *Step 3: Calculate the maximum possible storage reservoir depth beneath the pipe (''d<sub>s</sub>''): − <math>d_{s}=f'\times38.4</math> − {{Plainlist|1=Where: − *''f''' = Design infiltration rate in mm/hr, and − *38.4 comes from multiplying desired drainage time of 96 hours by void ratio of 0.4}} − − ===Additional step for system without underdrain=== − *Step 4: Determine maximum permissible ponding depth (''d<sub>p</sub>''): − <math>d_{p}=f'\times19.2</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.}} − * Step 5: Sum total depth of bioretention, and compare to available space above water table and bedrock. Adjust if necessary. − − ==Calculate the remaining dimensions== − * 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). − * Step 7: Calculate the required total storage (m<sup>3</sup>): − <math>Storage=RVC_T\times A_c\times C\times 0.1</math> − {{Plainlist|1=Where: − *''RVC<sub>T</sub>'' is the Runoff volume control target (mm), − *''A<sub>c</sub>'' is the catchment area (Ha), − *''C'' is the runoff coefficient of the catchment area, and − * 0.1 is the units correction between m<sup>3</sup> and mm.Ha.}} − * 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>. − * Step 9. Calculate the peak flow rate (''Q<sub>p</sub>'', in L/s) through the filter media: − ----
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==Calculate the maximum overall depth==
==Calculate the maximum overall depth==