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→Select a surface ponding depth to begin sizing with:
If the field estimated infiltration rate of the underlying native soil (f<sub>f</sub>) is less than 15 mm/h, include an underdrain.
If the field estimated infiltration rate of the underlying native soil (f<sub>f</sub>) is less than 15 mm/h, include an underdrain.
==Select a surface ponding depth to begin sizing with:==
==Select a surface ponding depth to begin sizing with==
* Step 2: Determine a maximum surface ponding depth (''d<sub>p, max</sub>'')
* Step 2: Determine a maximum surface ponding depth (''d<sub>p, max</sub>'')
For practices without underdrains:<br>
For practices without underdrains:<br>
*48 = Maximum permissible drainage time for ponded water (h)
*48 = Maximum permissible drainage time for ponded water (h)
*Note that in designs without underdrains, conceptually the drainage of ponded water is limited by infiltration through the base of the practice.}}<br>
*Note that in designs without underdrains, conceptually the drainage of ponded water is limited by infiltration through the base of the practice.}}<br>
For practices with underdrains see recommended maximum ponding depths for each filter media blend in the table above.<br>
For practices with underdrains see recommended maximum surface ponding depth for each filter media blend in the table above.<br>
* Step 3: Select a design surface ponding depth, d<sub>p</sub>' (m) to begin sizing with<br>
* Step 3: Select a design surface ponding depth, d<sub>p</sub>' (m) to begin sizing with<br>
For practices with soft (i.e. landscaped) edges and bowl-shaped ponding areas calculate the mean ponding depth:
For practices with soft (i.e. landscaped) edges and bowl-shaped ponding areas calculate the mean surface ponding depth:
<math>d_{p}'=d_{p, max}\times 1/2</math>
<math>d_{p}'=d_{p, max}\times 1/2</math>
For practices with hard edges and vertical-walled ponding areas (e.g., stormwater planter, soil cell) use the maximum ponding depth (d<sub>p, max</sub>)
For practices with hard edges and vertical-walled ponding areas (e.g., stormwater planter, soil cell) use the maximum ponding depth:
<math>(d_{p}'=d_{p, max}
* Step 4: Determine the active storage depth, d<sub>a</sub> of the practice<br>
* Step 4: Determine the active storage depth, d<sub>a</sub> of the practice<br>