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Line 1: − + − + − [[File:Sizing Bioretention.jpg|thumb|The vertical storage zones in a bioretention cell include: ponding, mulch, filter media, choker course, pipe diameter reservoir and the storage reservoir.]] − Many of the dimensions in a bioretention system can be predetermined according to the function of the component. There is greatest flexibility in the ponding depth and the depth of the storage reservoir beneath the optional underdrain pipe. The order of operations in calculating these dimensions depends on whether an underdrain is desired. + Line 10:
Line 9: − ! Recommended depth (no underdrain pipe) − + − | See below − | colspan="2" |75 ± 25 mm+ Line 25:
Line 22: − | colspan="2" |+ Line 31:
Line 28: − | [[choker layer|Choker course]]+ − | colspan="2" |100 mm − | 0.4 typical − |- − | Not applicable − + − + − | See below
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[[File:Sizing flow-through planter.jpg|thumb|A flow-through planter comprises a ponding zone, mulch layer, filter media for planting, and a supporting gravel drainage layer]]
[[File:Sizing flow-through planter.jpg|thumb|A flow-through planter comprises a ponding zone, mulch layer, filter media for planting, and a supporting gravel drainage layer]]
This article is specific to [[bioretention]], vegetated systems that infiltrate water to the native soil. <br>
This article is specific to [[Flow-through stormwater planters]], vegetated systems that do not infiltrate water to the native soil. <br>
If you are designing a planted system which does not infiltrate water, see advice on [[Planters: Sizing]].
If you are designing a planted system which does infiltrate water, see advice on [[Bioretention: Sizing]].
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The dimensions of a stormwater planter are largely predetermined according to the function of the component. As they do not contain a storage reservoir the planters rely more upon careful selection of materials. Both the filter media and the perforations of the pipe play critical roles for flow control.
{| class="wikitable"
{| class="wikitable"
! Component
! Component
! Recommended depth (with underdrain pipe)
! Recommended depth (with underdrain pipe)
! Typical void ratio (''V<sub>R</sub>'')
! Typical void ratio (''V<sub>R</sub>'')
|-
|-
| Ponding (''d<sub>p</sub>'')
| Ponding (''d<sub>p</sub>'')
| 300 mm
| ≥ 300 mm
| 1
| 1
|-
|-
| [[Mulch]]
| [[Mulch]]
| 75 ± 25 mm
|
|
* 0.7 for wood based
* 0.7 for wood based
|-
|-
| [[Bioretention: Filter media|filter media]] (''d<sub>m</sub>'')
| [[Bioretention: Filter media|filter media]] (''d<sub>m</sub>'')
|
* 300 mm to support turf grass (and accept only rainwater/roof runoff)
* 300 mm to support turf grass (and accept only rainwater/roof runoff)
* 600 mm to support flowering [[perennials]] and decorative [[grasses]]
* 600 mm to support flowering [[perennials]] and decorative [[grasses]]
| 0.3
| 0.3
|-
|-
| Pipe diameter reservoir
| Pipe diameter reservoir
| Is equal to underdrain pipe diameter
| Is equal to underdrain pipe diameter
| 0.4
| 0.4
|-
|-
| Storage reservoir (''d<sub>s</sub>'')
| Pipe bedding (''d<sub>b</sub>'')
| See below
| 50 mm (although commonly omitted altogether).
| 0.4
| 0.4
|}
|}