Changes

If R is greater than 20, consider decreasing catchment impervious area (A_i) by draining less area to the practice.

If R is greater than 20, consider decreasing catchment impervious area (A_i) by draining less area to the practice.

==Size a bioretention cell with no underdrain for constrained ground area==

==Size a bioretention cell where drainage area and practice area are fixed==

If the land area is limited, determine the I/P ratio, which is the ratio of catchment impervious area (A_i) to practice pervious footprint area (A_p):

If the land area is limited, determine the I/P ratio, which is the ratio of catchment impervious area (A_i) to practice pervious footprint area (A_p):

:<math>R=\frac{A_{i}}{A_{p}}</math>

:<math>R=\frac{A_{i}}{A_{p}}</math>

*''A_i'' = Catchment impervious area in m²}}

*''A_i'' = Catchment impervious area in m²}}

Then calculate the required depth (''d_T''), as:

Then calculate the required storage reservoir depth (''d_r''), as:

<math>d_{T}=\frac{D \left[ (R\times i)-f'\right]}{n'}</math>

<math>d_{r}=\frac{D \left[ (R\times i)-f'\right]}{n'}</math>

{{Plainlist|1=Where:

{{Plainlist|1=Where:

*''i'' = Intensity of design storm (m/h)

*''i'' = Intensity of design storm (m/h)

*''f''' = Design infiltration rate (m/h)  

*''f''' = Design infiltration rate (m/h)  

*''n''' = Effective porosity of the fill materials within the practice, depth weighted mean

*''n''' = Effective porosity of the storage reservoir fill material}}

*''d_T'' = Total depth of infiltration practice (m).}}

These equations assume that infiltration occurs primarily through the base of the facility.  

These equations assume that infiltration occurs primarily through the base of the facility.  

 

This spreadsheet tool has been set up to perform all of the infiltration practice sizing calculations shown above.<br>

This spreadsheet tool has been set up to perform all of the infiltration BMP sizing calculations shown above<br>

{{Clickable button|[[Media:Infiltration Sizing 20200525 locked.xlsx|Download the infiltration practice sizing tool]]}}

{{Clickable button|[[Media:Infiltration Sizing 20200525 locked.xlsx|Download the infiltration practice sizing tool]]}}