Changes

===Calculating infiltration practice drainage time assuming three dimensional (3D) drainage<ref>Woods Ballard, B., S. Wilson, H. Udale-Clarke, S. Illman, T. Scott, R. Ahsley, and R. Kellagher. 2016. The SuDS Manual. 5th ed. CIRIA, London.</ref>===

===Calculating infiltration practice drainage time assuming three dimensional (3D) drainage<ref>Woods Ballard, B., S. Wilson, H. Udale-Clarke, S. Illman, T. Scott, R. Ahsley, and R. Kellagher. 2016. The SuDS Manual. 5th ed. CIRIA, London.</ref>===

[[file:Hydraulic radius.png|thumb|Two practice areas of 9 m².<br> x = 12 m (left), x = 20 m (right)]]

[[file:Hydraulic radius.png|thumb|Two practice areas of 9 m².<br> x = 12 m (left), x = 20 m (right)]]

In some situations, it may be desirable to reduce the size of the bioretention required, by accounting for rapid drainage.  

In some situations, it may be desirable to optimize the size of the bioretention practice, by accounting for drainage in three dimensions rather than one.  

Typically, this is only worth exploring over sandy textured native subsoils with rapid infiltration.  

Typically, this is only worth exploring over sandy textured native subsoils with rapid infiltration.  

The drainage time calculator noted above can be used to calculate drainage time assuming three dimensional drainage as well.

The drainage time calculator noted above can be used to calculate drainage time assuming both one and three dimensional drainage and allows for comparison between the estimates.

*Begin the drainage time calculation by dividing the area of the practice (''A_p'') by the perimeter (''x'')

*Begin the drainage time calculation by dividing the area of the practice (''A_p'') by the perimeter (''x'')