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Line 77: + − For practices with underdrain perforated pipe elevated off the bottom of the storage reservoir:+ − d<sub>p, max</sub>= depth of storage reservoir below the invert of the underdrain perforated pipe.<br> − For practices with underdrain on base of the storage reservoir and connected to a riser (e.g., standpipe and 90 degree coupling): − d<sub>p, max</sub>= Difference between elevation of reservoir bottom and invert of the riser (i.e 90 degree coupling).<br> − + + + + + + + + + +
→Select a surface ponding depth to begin sizing with:
*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.
* Step 3: Select a design surface ponding depth, d<sub>p</sub>' (m) to begin sizing with<br>
* Step 3: Determine the 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 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>)
* Step 4: Determine the active storage depth, d<sub>a</sub> of the practice<br>
For practices without an underdrain, the active storage depth equals the total depth of the practice, including surface ponding depth; <br>
<math>d_{a}=d_{T}</math>
For practices with the underdrain perforated pipe elevated off the bottom of the storage reservoir:
d<sub>p, max</sub>= depth of storage reservoir below the invert of the underdrain perforated pipe.<br>
For practices with the underdrain perforated pipe installed on the bottom of the storage reservoir and connected to a riser (e.g., standpipe and 90 degree coupling):
d<sub>p, max</sub>= Difference between invert elevation of reservoir bottom and invert of the riser (i.e 90 degree coupling).<br>
==Calculate the total depth of the practice, d<sub>T</sub>==
==Calculate the total depth of the practice, d<sub>T</sub>==