*48 = Maximum permissible drainage time for ponded water (h)}}<br>
*48 = Maximum permissible drainage time for ponded water (h)}}<br>
−
*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 surface ponding depth 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>