Difference between revisions of "Wetlands"

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|Drainage Area  
|Drainage Area  
|Sustaining vegetation, volumetric turnover
|Sustaining vegetation, volumetric turnover
|5 Ha (≥10 Ha preferred)
|style="text-align: left|5 Ha (≥10 Ha preferred)
|-
|-
|Treatment Volume  
|Treatment Volume  
|Provision of appropriate level of protection (Table 3.2)
|Provision of appropriate level of protection (Table 3.2)
|See Table 3.2
|style="text-align: left|See Table 3.2
|-
|-
|Active Storage
|Active Storage
|Detention
|Detention
|Suspended solids settling 24 hrs (12 hrs if in conflict with min. orifice size)
|style="text-align: left|Suspended solids settling 24 hrs (12 hrs if in conflict with min. orifice size)
|-
|-
|Forebay  
|Forebay  
|Pre-treatment  
|Pre-treatment  
|
|style="text-align: left|
#Minimum depth: 1 m;
#Minimum depth: 1 m;
#Sized to ensure non-erosive velocities leaving forebay;  
#Sized to ensure non-erosive velocities leaving forebay;  
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|Permanent Pool Depth
|Permanent Pool Depth
|Vegetation requirements, rapid settling
|Vegetation requirements, rapid settling
|The average permanent pool depth should range from 150 mm to 300 mm
|style="text-align: left|The average permanent pool depth should range from 150 mm to 300 mm
|-
|-
|Active Storage Depth
|Active Storage Depth
|Storage/flow control, sustaining vegetation
|Storage/flow control, sustaining vegetation
|Maximum 1.0m for storms < 10 year event
|style="text-align: left|Maximum 1.0m for storms < 10 year event
|-
|-
|Side Slopes  
|Side Slopes  
|Safety  
|Safety  
|
|style="text-align: left|
#5:1 For 3 m above and below permanent pool;  
#5:1 For 3 m above and below permanent pool;  
#Maximum 3:1 elsewhere
#Maximum 3:1 elsewhere
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|Inlet  
|Inlet  
|Avoid clogging/freezing  
|Avoid clogging/freezing  
|
|style="text-align: left|
#Minimum 450 mm;  
#Minimum 450 mm;  
#Preferred pipe slope: >1%;  
#Preferred pipe slope: >1%;  
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|Outlet  
|Outlet  
|Avoid clogging/freezing  
|Avoid clogging/freezing  
|
|style="text-align: left|
#Minimum: 450mm outlet pipe;  
#Minimum: 450mm outlet pipe;  
#Preferred pipe slope: >1%;  
#Preferred pipe slope: >1%;  
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|Maintenance Access  
|Maintenance Access  
|Access for backhoes or dredging equipment
|Access for backhoes or dredging equipment
|
|style="text-align: left|
#Provided to approval of Municipality;  
#Provided to approval of Municipality;  
#Provision of maintenance drawdown pipe preferred
#Provision of maintenance drawdown pipe preferred
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|Buffer  
|Buffer  
|Safety  
|Safety  
|Minimum 7.5 m above maximum water quality/erosion control water level
|style="text-align: left|Minimum 7.5 m above maximum water quality/erosion control water level
|}
|}



Revision as of 01:13, 29 September 2018

Wetlands fed by stormwater at Kortright Farm, Vaughan ON

Overview[edit]

Wetlands are an ideal technology for:

  • Text A
  • Text B
Types of Constructed Wetland
Type A Type B Type C
Surface water Minimal
Any surface flow can be slowed with check dams
Ponding is encouraged with check dams
Soil Filter media required Amendment preferable when possible
Underdrain Common Uncommon
Maintenance Medium to high Low
Stormwater benefit High Moderate
Biodiversity benefit Increased with native planting Typically lower

Planning considerations[edit]

Design[edit]

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
  1. Minimum depth: 1 m;
  2. Sized to ensure non-erosive velocities leaving forebay;
  3. Maximum area: 20 % of total permanent pool
Length-to-Width Ratio Maximize flow path and minimize short-circuiting potential
  1. Overall: minimum 3:1;
  2. 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
  1. 5:1 For 3 m above and below permanent pool;
  2. Maximum 3:1 elsewhere
Inlet Avoid clogging/freezing
  1. Minimum 450 mm;
  2. Preferred pipe slope: >1%;
  3. If submerged, obvert 150 mm below expected maximum ice depth
Outlet Avoid clogging/freezing
  1. Minimum: 450mm outlet pipe;
  2. Preferred pipe slope: >1%;
  3. If orifice control used, 75mm diameter minimum;
  4. Minimum 100mm orifice preferable
Maintenance Access Access for backhoes or dredging equipment
  1. Provided to approval of Municipality;
  2. Provision of maintenance drawdown pipe preferred
Buffer Safety Minimum 7.5 m above maximum water quality/erosion control water level

Performance[edit]

STEP (under previous name SWAMP) conducted their own research into the performance of stormwater wetlands, the project page and report can be viewed here.

Gallery[edit]

Construction[edit]

See also[edit]

External links[edit]