==To calculate the required depth, where the area of the facility is constrained (1D drainage)==
==To calculate the required depth, where the area of the facility is constrained (1D drainage)==
In some very constrained sites, the surface area of the BMP may be limited, in this case the required depth of cell or trench can be calculated.
In some very constrained sites, the surface area of the BMP may be limited, in this case the required active storage reservoir depth of the bioretention cell or infiltration trench can be calculated.
Note that in most cases the results of this calculation will be very similar to those of the above equation using 3D infiltration.
Note that in most cases the results of this calculation will be very similar to those from the equation below assuming 3 dimensional drainage.