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→Design
==Planning considerations==
==Planning considerations==
==Design==
==Design==
{| class="wikitable"
!Element
!Design Objective
!Criteria
|-
|Drainage Area
|Sustaining vegetation, volumetric turnover
|5 Ha (≥10 Ha preferred)
|-
|Treatment Volume
|Provision of appropriate level of protection (Table 3.2)
|See Table 3.2
|-
|Active Storage
|Detention
|Suspended solids settling 24 hrs (12 hrs if in conflict with min. orifice size)
|-
|Forebay
|Pre-treatment
|Minimum depth: 1 m; ii) Sized to ensure non-erosive velocities leaving forebay; iii) Maximum area: 20 % of total permanent pool
|-
|Length-to-Width Ratio
|Maximize flow path and minimize short-circuiting potential
|i) Overall: minimum 3:1; ii) Forebay: minimum 2:1
|-
|Permanent Pool Depth
|Vegetation requirements, rapid settling
|The average permanent pool depth should range from 150 mm to 300 mm
|-
|Active Storage Depth
|Storage/flow control, sustaining vegetation
|Maximum 1.0m for storms < 10 year event
|-
|Side Slopes
|Safety
|i) 5:1 For 3 m above and below permanent pool (ii) Maximum 3:1 elsewhere
|-
|Inlet
|Avoid clogging/freezing
|i) Minimum 450 mm; ii) Preferred pipe slope: >1%; iii) If submerged, obvert 150 mm below expected maximum ice depth
|-
|Outlet
|Avoid clogging/freezing
|i) Minimum: 450mm outlet pipe; ii) Preferred pipe slope: >1%; iii) If orifice control used, 75mm diameter minimum; (iv) Minimum 100mm orifice preferable
|-
|Maintenance Access
|Access for backhoes or dredging equipment
|(i) Provided to approval of Municipality; (ii) Provision of maintenance drawdown pipe preferred
|-
|Buffer
|Safety
|Minimum 7.5 m above maximum water quality/erosion control water level
|}
==Performance==
==Performance==
STEP (under previous name SWAMP) conducted their own research into the performance of stormwater wetlands, the project page and report can be viewed [https://sustainabletechnologies.ca/home/urban-runoff-green-infrastructure/conventional-stormwater-management/constructed-wetlands/performance-assessment-of-an-open-and-covered-stormwater-wetland-system-aurora-ontario/ here].
STEP (under previous name SWAMP) conducted their own research into the performance of stormwater wetlands, the project page and report can be viewed [https://sustainabletechnologies.ca/home/urban-runoff-green-infrastructure/conventional-stormwater-management/constructed-wetlands/performance-assessment-of-an-open-and-covered-stormwater-wetland-system-aurora-ontario/ here].