Changes

#a layer of [[filter media]] to support plant growth (minimum depth, ''d_m'' = 0.6 m) , and  

#a layer of [[filter media]] to support plant growth (minimum depth, ''d_m'' = 0.6 m) , and  

#a reservoir of [[stone]] to store and facilitate [[infiltration]] of additional water (depth, ''d_R'', includes 0.1 m choking layer).  

#a reservoir of [[stone]] to store and facilitate [[infiltration]] of additional water (depth, ''d_R'', includes 0.1 m choking layer).  

Firstly, all three zones will be sized together within the limited depth to estimate the footprint area of the whole [[bioretention]] facility. To do this the mean void ratio (''V_R'') will estimated as ~ 0.35.

Firstly, all three zones will be sized together within the limited depth to estimate the footprint area of the whole [[bioretention]] facility. To do this the mean void ratio (''V_R'') will estimated as ~ 0.4.

To calculate the required practice area (''A_p'') or footprint where the depth is constrained:

To calculate the required practice area (''A_p'') or footprint where the depth is constrained:

{{Plainlist|1=Where:

{{Plainlist|1=Where:

*''V'' = Required volume of storage in m³

*''V'' = Required volume of storage in m³

*''V_R'' = Void ratio (porosity), as measured (or default to 0.35)   

*''V_R'' = Void ratio (porosity), as measured (or default to 0.4)   

*''A_p'' = Area of the infiltration practice in m²

*''A_p'' = Area of the infiltration practice in m²

*''d_T'' = Total depth of infiltration practice in m (= ''d_b'' + ''d_m'' + ''d_R'')}}

*''d_T'' = Total depth of infiltration practice in m (= ''d_b'' + ''d_m'' + ''d_R'')}}