Changes

*Step 2: Select an underdrain pipe diameter (typically 100 - 200 mm), assign this as an 'embedding' depth. *Note that this component does not apply if a downstream riser is being used to control an extended saturation zone.   

*Step 2: Select an underdrain pipe diameter (typically 100 - 200 mm), assign this as an 'embedding' depth. *Note that this component does not apply if a downstream riser is being used to control an extended saturation zone.   

*Step 3: Calculate the maximum possible storage reservoir depth beneath the pipe (''d_{s, max}'', mm):

*Step 3: Calculate the maximum possible storage reservoir depth beneath the pipe (''d_{s, max}'', mm):

<math>d_{s, max}=\frac{f'\times t}{0.4}</math>

<math>d_{s, max}=f'\times t</math>

{{Plainlist|1=Where:

{{Plainlist|1=Where:

*''f''' = Design infiltration rate (mm/hr), and

*''f''' = Design infiltration rate (mm/hr), and

*''t'' = [[Drainage time]] (hrs). Check local regulations for drainage time requirements.

*''t'' = [[Drainage time]] (hrs). Check local regulations for drainage time requirements.}}

*''0.4'' = Void ratio of [[reservoir gravel|clear stone]]}}

===Additional step for system without underdrain===

===Additional step for system without underdrain===

* Step 4: Determine maximum permissible ponding depth (''d_{p, max}''):

* Step 4: Determine maximum permissible ponding depth (''d_{p, max}''):

<math>d_{p, max}=\frac{f'\times48}{0.4}</math>

<math>d_{p, max}=f'\times48</math>

{{Plainlist|1=Where:

{{Plainlist|1=Where:

*''f''' = Design infiltration rate (mm/hr), and

*''f''' = Design infiltration rate (mm/hr), and

*48 = Drainage time of the ponding (hrs)

*48 = Drainage time of the ponding (hrs)

*0.4 = Void ratio of [[reservoir gravel|clear stone]] *Note that conceptually the drainage of the ponded area is limited by ex-filtration at the base of the practice.}}

*Note that conceptually the drainage of the ponded area is limited by ex-filtration at the base of the practice.}}

* Step 5: Sum total depth of bioretention, and compare to available space above water table and bedrock. Adjust if necessary.

* Step 5: Sum total depth of bioretention, and compare to available space above water table and bedrock. Adjust if necessary.