2,681
edits
Changes
Jump to navigation
Jump to search
Line 92:
Line 92: − + − + − + − + − *''d<sub>p</sub>''= design surface ponding depth}}<br>+ −
→Determine the active storage depth of the practice
{{Plainlist|1=Where:
{{Plainlist|1=Where:
*d<sub>T</sub> = Total depth of the practice, including surface ponding}}<br>
*d<sub>T</sub> = Total depth of the practice, including surface ponding}}<br>
For practices with the underdrain perforated pipe elevated off the bottom of the storage reservoir:
For practices with the underdrain perforated pipe elevated off the bottom of the storage reservoir:<br>
d<sub>a</sub>= Depth of storage reservoir below the invert elevation of the underdrain perforated pipe.<br>
d<sub>a</sub>= Depth of storage reservoir below the invert elevation 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):
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):<br>
d<sub>a</sub>= Difference between invert elevations of the reservoir bottom and riser outlet (i.e invert elevation of the 90 degree coupling).<br>
d<sub>a</sub>= Difference between invert elevations of the reservoir bottom and riser outlet (i.e invert elevation of the 90 degree coupling).<br>
* Step 5: Calculate the active storage depth of the storage reservoir (''d<sub>a'', mm):<br>
* Step 5: Calculate the active storage depth of the storage reservoir (''d<sub>a'', mm):<br>
For practices with no underdrain, this is limited to the surface ponding and storage reservoir depth that will reliably drain within the specified drainage time:
For practices with no underdrain, this includes the surface ponding and storage reservoir depth that will reliably drain within the specified drainage time:
<math>d_{a}=(f'\times t \times 1/n)</math>
<math>d_{a}=(f'\times t \times 1/n)</math>
{{Plainlist|1=Where:
{{Plainlist|1=Where:
*''f''' = Design infiltration rate (mm/hr),
*''f''' = Design infiltration rate (mm/hr),
*''t'' = [[Drainage time]] (hrs). Check local regulations for drainage time requirements; and
*''t'' = [[Drainage time]] (hrs). Check local regulations for drainage time requirements; and
*''n'' = Porosity of the reservoir aggregate
*''n'' = Porosity of the reservoir aggregate}}<br>
For practices with an underdrain, this includes only the storage reservoir depth that will reliably drain within the specified drainage time:
For practices with an underdrain:
<math>d_{a}=f'\times t \times 1/n</math>
<math>d_{a}=f'\times t \times 1/n</math>
{{Plainlist|1=Where:
{{Plainlist|1=Where: