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===Sizing and Modelling=== Bioretention facilities should be sized to accommodate runoff from approximately 5 to 20 times the footprint area of the facility. i.e. I/P ratio of 5 to 20. *'''[[Bioretention: Sizing| Sizing]]'''*'''[[Bioretention: TTT| Modelling]]'''
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Naturalized landscaping and soft edges can make a bioretention facility 'disappear' into green space surroundings. In some scenarios, a larger bioretention (50 - 800 m<sup>2</sup>) cell may be used as an end-of-pipe facility treating both sheet flow and concentrated flow before it enters an adjacent water course. In these larger installations care must be made in the design to distribute the inflow, preventing erosion and maximizing infiltration.
Naturalized landscaping and soft edges can make a bioretention facility 'disappear' into green space surroundings. In some scenarios, a larger bioretention (50 - 800 m<sup>2</sup>) cell may be used as an end-of-pipe facility treating both sheet flow and concentrated flow before it enters an adjacent water course. In these larger installations care must be made in the design to distribute the inflow, preventing erosion and maximizing infiltration.
==Infiltration==
==Design==
{|class="wikitable"
|+ Optimizing bioretention for water quality
|-
!style="background: darkcyan; color: white"|Poor design choice: <br> Limits outflow water quality
!style="background: darkcyan; color: white"|Better design choice: <br> Improves outflow water quality
|-
|Single large cell design||Several smaller distributed cells
|-
|Single concentrated inflow||Forebays or distributed flow
|-
|No pretreatment||Pretreatment provided as part of treatment train design
|-
|Over-sized underdrain||Moderately sized underdrain (or no underdrain)
|-
|Filter bed < 0.5 m||Filter bed > 0.75 m
|-
|Filter media Phosphorus > 30 ppm||Filter media Phosphorus < 30 ppm
|-
|Filter media predominantly sand||Filter media contains fractions of fines and organic material in sand
|-
|Surface covered with stone (or uncovered)||Surface covered with mulch and dense vegetation
|}
===Sizing and Modelling===
Bioretention facilities should be sized to accommodate runoff from approximately 5 to 20 times the footprint area of the facility. i.e. I/P ratio of 5 to 20.
*'''[[Bioretention: Sizing| Sizing]]'''
*'''[[Bioretention: TTT| Modelling]]'''
===Infiltration===
Some form of stormwater landscaping (bioretention) can be fitted into most spaces. Although there are some [[Infiltration#Constraints|constraints]] to infiltrating water, it is preferable to do so where possible. [[Bioretention:_Partial_infiltration|Partial infiltration]] facilities are a popular choice over 'tight' soils where infiltration rates are ≤ 15 mm/hr.
Some form of stormwater landscaping (bioretention) can be fitted into most spaces. Although there are some [[Infiltration#Constraints|constraints]] to infiltrating water, it is preferable to do so where possible. [[Bioretention:_Partial_infiltration|Partial infiltration]] facilities are a popular choice over 'tight' soils where infiltration rates are ≤ 15 mm/hr.
{{:Bioretention: Variations}}
{{:Bioretention: Variations}}
==Design==
==Design==
===Plant Selection===
===Plant Selection===