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→Determine the required surface area of the practice
==Determine the required surface area of the practice==
==Determine the required surface area of the practice==
* 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>
* Step 10: Calculate the surface area of the practice (A<sub>p</sub>) needed to capture the volume of runoff produced from the catchment during the design storm event<br>
For practices where flow is delivered to a surface ponding area:
For practices where flow is delivered to a surface ponding area:
<math>A_{p}=i\times D\times A_{i}/[d_{p}' + (f_{f, min} \times D)]</math>
<math>A_{p}=i\times D\times A_{i}/[d_{p}' + (f_{f, min} \times D)]</math>
<math>A_{p}=i\times D\times A_{i}/[d_{a} + (f' \times D)]</math>
<math>A_{p}=i\times D\times A_{i}/[d_{a} + (f' \times D)]</math>
{{Plainlist|1=Where:
{{Plainlist|1=Where:
*d<sub>a</sub> = Active water storage depth (m), see above equations
*d<sub>a</sub> = Active water storage depth (m), see above for equations for with and without underdrain designs
*f' = design infiltration rate of the underlying native soil (m/h)
*f' = design infiltration rate of the underlying native soil (m/h)
*D = Design storm duration (h)}}<br>
*D = Design storm duration (h)}}<br>