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* Step 11: Calculate the required total storage (S<sub>T</sub>, m<sup>3</sup>):* 10 is the units correction between m<sup>3</sup> and mm.Ha.}} ==Additional calculations==
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* Step 9: Adjust component depths to maintain a separation of 1.0 metre between base of the practice and seasonally high water table or top of bedrock elevation, or a lesser or greater value based on groundwater mounding analysis. See below and [[Groundwater]] for more information.
* Step 9: Adjust component depths to maintain a separation of 1.0 metre between base of the practice and seasonally high water table or top of bedrock elevation, or a lesser or greater value based on groundwater mounding analysis. See below and [[Groundwater]] for more information.
==Calculate the remaining dimensions==
==Determine the required surface area of the practice==
* Step 10: Multiply the depth of each separate water-retaining component layer in the profile of the practice by its corresponding porosity and then sum the total to find the 1 dimensional storage (in mm).
* Step 10: Calculate the surface (i.e footprint) area of the practice (A<sub>p</sub>) needed to capture the runoff volume produced from the catchment during the design storm event<br>
For practices where flow is delivered to the filter media bed:
<math>S_{T}=RVC_T\times A_i\times 10</math>
<math>A_{p}=i\times D\times A_{i}/[d_{p}' + (f_{m, min} \times D)]</math>
{{Plainlist|1=Where:
{{Plainlist|1=Where:
*''RVC<sub>T</sub>'' is the runoff volume control target (mm),
*i = Design storm intensity (m/h)
*''A<sub>i</sub>'' is the impervious area within the catchment (Ha), and
*D = Design storm duration (h)
*A<sub>i</sub> = Catchment impervious area (m<sup>2</sup>)
* Step 12. Divide required storage (m<sup>3</sup>) by the active storage depth of the practice, d<sub>a</sub> (in m) to find the required storage reservoir footprint area (''A<sub>p</sub>'') for the bioretention in m<sup>2</sup>.
*d<sub>p</sub>' = Design surface ponding depth (m)
*f<sub>m, min</sub> = minimum infiltration rate (i.e. saturated hydraulic conductivity) of the filter media (m/h), see [[Bioretention: Filter media|Filter media]] for guidance}}<br>
For practices where flow is delivered to the storage reservoir:
<math>A_{p}=i\times D\times A_{i}/[(d_{a}\times n) + (f' \times D)]</math>
{{Plainlist|1=Where:
*d<sub>a</sub> = Active storage depth (m)
*n = porosity of storage reservoir aggregate or effective porosity of void-producing structure system
*f' = design infiltration rate of the underlying native soil (m/h)
*D = Design storm duration (h)}}<br>
==Calculate peak flow rates==
* Step 13. Calculate the peak [[flow through perforated pipe|flow rate through the perforated pipe]],
* Step 13. Calculate the peak [[flow through perforated pipe|flow rate through the perforated pipe]],
* Step 14. Calculate the peak [[flow through media|flow rate through the filter media]],
* Step 14. Calculate the peak [[flow through media|flow rate through the filter media]],
* Step 15. Determine if downstream [[flow control]] is required to achieve hydrologic objectives.
* Step 15. Determine if downstream [[flow control]] is required to achieve hydrologic objectives.
===Calculating infiltration practice drainage in 1 dimension===
===Calculating infiltration practice drainage in 1 dimension===