Changes

==Calculate the maximum overall depth==

==Calculate the maximum overall depth==

*Step 1. Determine what the planting needs are and assign appropriate depth of media.  

*Step 1: Determine what the planting needs are and assign appropriate depth of media.  

*Step 2. Decide on the underdrain pipe diameter.  

*Step 2: Decide on the underdrain pipe diameter.  

*Step 3. Determine maximum possible storage reservoir depth beneath the pipe (''d_S''):

*Step 3: Determine maximum possible storage reservoir depth beneath the pipe (''d_S''):

<math>d_{S}=f'\times38.4</math>

<math>d_{S}=f'\times38.4</math>

{{Plainlist|1=Where:

{{Plainlist|1=Where:

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

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

*Step 4. Determine maximum permissible ponding depth (''d_P''):

*Step 4: Determine maximum permissible ponding depth (''d_P''):

<math>d_{P}=f'\times19.2</math>

<math>d_{P}=f'\times19.2</math>

{{Plainlist|1=Where:

{{Plainlist|1=Where:

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

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

*19.2 comes from multiplying desired drainage time of 48 hours by void ratio of 0.4. Note that conceptually the drainage of the ponded area is limited by ex-filtration at the base of the practice.}}

*19.2 comes from multiplying desired drainage time of 48 hours by void ratio of 0.4. 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 necesary.  

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

==Calculate the remaining dimensions==

==Calculate the remaining dimensions==

* Step 6. Multiply the depth of each separate component by the void ratio and then sum the total.

* Step 6: Multiply the depth of each separate component by the void ratio and then sum the total.

<math>Storage=RVC_T\times Catchment area\times0.095</math>

 

<math>Storage=RVC_T\times Catchment area\times0.95</math>

{{Plainlist|1=Where:

{{Plainlist|1=Where:

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

*''RVC_T''' = Runoff volume control target (mm), and

*19.2 comes from multiplying desired drainage time of 48 hours by void ratio of 0.4. Note that conceptually the drainage of the ponded area is limited by ex-filtration at the base of the practice.}}

* Area (Ha)

* 0.095 is the product of a typical runoff coefficient for impermeable surfaces (0.95) and the units correction between m³ and mm.Ha.}}