*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>
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* Step 11: Compare required surface area of the practice to available space.<br>
+
To decrease A<sub>p</sub>, consider increasing ponding depth if feasible and would not create a safety hazard, or decreasing catchment impervious area.
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* Step 12: Calculate catchment impervious area to practice permeable (footprint) area ratio, R and compare to recommended range in the table above