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Line 1: − + − + − <div class="col-md-8">+ − ===Overview===+ − + − + − + − + − + − + − + + − <p><strong>The fundamental components of a bioretention cell are:</strong>+ − *Biomedia - an engineered soil mix+ − *Planting - </p>+ − <p><strong>Additional components may include:</strong>+ − *Impermeable membrane to prevent infiltration to soils below+ − *Check dams+ − </p>+ − + − </div>+ − <div class="col-md-4">+ − + − <panelSuccess>+ − <gallery mode="packed" widths=300px heights=300px>+ − 20161024 100338 550x550.jpg| Bioswale? + − </gallery>+ − </panelSuccess>+ − + − + − <div class="col-md-12">+ − ---- − − ===Planning Considerations=== − </div> − <div class="col-md-8"> − Planning Content − − </div> − <div class="col-md-4"> − <panelSuccess>+ − <gallery mode="packed" widths=300px heights=300px>+ − IMG 2457 750X500.jpg| Placeholder.+ − + − </panelSuccess>+ + − + − <div class="col-md-12">+ − ----+ − ===Design===+ − </div>+ − − Design Content − + − <div class="col-md-4">+ − <panelSuccess>+ − <gallery mode="packed" widths=300px heights=300px>+ − IMG 2457 750X500.jpg| Bioretention cell capturing and treating runoff from adjacent parking lot at the Kortright Centre, Vaughan. − </gallery> − </panelSuccess> − </div>+ − <div class="col-md-12">+ − ----+ − − </div> − <div class="col-md-8"> − Performance Content − </div>+ − <div class="col-md-4">+ − <panelSuccess>+ − <gallery mode="packed" widths=300px heights=300px>+ − IMG 2457 750X500.jpg| Placeholder+ − </gallery> − </panelSuccess> − − </div> − <div class="col-md-12"> − ---- − − <h4>In Ontario</h4> − <strong>City of Mississauga</strong><br> − The City of Mississauga has a stormwater management credit program which includes RWH as one of their recommended site strategies[https://www.mississauga.ca/portal/services/credit-program]. − <br> − <h4>LEED BD + C v. 4</h4> − − <h4>SITES v.2 </h4> − − ---- − − ===See Also=== − <ul> − <li>[[Bioretention Cells]]</li> − <li>[[Check Dams]]</li> − <li>[[Trees]]</li> − </ul> − ---- − + + + + + + + − <table class="table table-hover table-condensed table-bordered"> − <td class="text-center"><i class="fa fa-envelope-open-o"></i> [[Special:SpecialContact|<strong>SEND US YOUR QUESTIONS & FEEDBACK ABOUT THIS PAGE</strong>]]</td> − </table> − +
→Planning Considerations
This article is about planted installations designed to capture <strong>and convey</strong> surface runoff through an engineered soil with subterranean infrastructure. <br>
[[File:20161024 100338 550x550.jpg|thumb|Bioswale, County Court Boulevard, Brampton]]
For node type systems, see [[Bioretention Cells]].
This article is about installations designed to capture and convey surface runoff along a vegetated channel, whilst also promoting infiltration. <br>
For underground conveyance systems which promote infiltration, see [[Exfiltration trenches]].
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==Overview==
Swales are linear landscape features consisting of a drainage channel with gently sloping sides. Underground they may be filled with engineered soil and/or contain a water storage layer of coarse gravel material. Two variations on a basic swale are recommended as low impact development strategies, although using a combination of both designs may increase the benefits:<br>
<p>Bioswales are the
'''[[Bioswales]]''' are sometimes referred to as 'dry swales', 'vegetated swales', or 'water quality swales'. This type of BMP is form of [[bioretention]] with a long, linear shape (surface area typically >2:1 length:width) and a slope which convey water,<br>
</p>
'''[[Enhanced grass swales]]''' are a lower maintenance alternative, but generally have lower stormwater management potential. The enhancement over a basic grass swale is in the addition of [[check dams]] to slow surface water flow and create small temporary pools of water which can infiltrate the underlying soil.<br>
'''Grass swales''' are a relatively common landscape feature already and a great opportunity for retrofit, to reduce flow and improve water quality by encouraging settling and infiltration behind a series of check dams. <br>
'''[[Retention swales]]''' can be imagined as linear, sloped [[dry ponds]]. They typically make relatively small contributions to water volume and quality control than many other BMPs, but they may feature as part of a site-wide treatment train approach.
{{TextBox|1=Bioswales are an ideal technology for:
{{float right|{{#widget:YouTube|id=8b3-a_Na1dE}}}}
*Sites with long linear landscaped areas, such as parking lots
{{textbox|Swales are an ideal technology for:
*Sites with long, linear landscaped areas, such as parking lots
*Connecting with one or more other types of LID}}
*Connecting with one or more other types of LID}}
{|class="wikitable"
|+ Types of Swale
|-
!Property
!Bioswale
!Enhanced grass swale
|-
|Surface water||Minimal<br>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
|-
</div>
|Biodiversity benefit||Increased with native planting||Typically lower
|}
==Planning Considerations==
[[File:Bioswale.png||thumb|Bioswale with check dams<br> (vertical scale exaggerated)]]
[[File:Stepped cells.png||thumb|Stepped bioretention cells alternative for slopes >6 % <br> (vertical scale exaggerated)]]
</gallery>
A linear design (surface area typically >2:1 length:width) is a common feature of swales:
*An absolute minimum width of 0.6 m is required for bioswales to promote healthy plant growth, and to facilitate construction,
*Grassed swales are usually mown as part of routine maintenance, so the cross section will be triangular or trapezoidal in shape with maximum side slopes of 1:3. The minimum width for this type would be 2 m. See [[Enhanced grass swales#Best cross sections| Best cross sections]]
</div>
Swales may be graded along longitudinal slopes between 0.5 - 6 %:
*Between 1 - 6 %, check dams are recommended to bring the compensation gradient <1 %.
*Slopes > 6% can accommodate a series of stepped [[bioretention cells]], each overflowing into the next with a spillway.
==Design==
[[File:Check dams.png|thumb| Distance between dams is determined by equalling the elevation of the crest of each dam, with the elevation of the toe of the upstream dam. <br>(vertical scale exaggerated)]]
<div class="col-md-8">
</div>
<h3>Pretreatment and inlets</h3>
To minimize erosion and maximize the functionality of the swale, sheet flow of surface water should be directed into the side of the BMP. [[Gravel diaphragms]], [[vegetated filter strips]] and shallow side slopes are ideal. Alternatively, a series of curb inlets can be employed, where each has some form of flow spreader incorporated. Single point inflow can cause increased erosion and sedimentation, which will damage vegetation and contribute to BMP failure. Again, flow spreading devices can mitigate these processes, where concentrated point inflow is required.
==Performance==
A review of swale-like practices was published by STEP in 1999. The project page and additional tools are available [https://sustainabletechnologies.ca/home/urban-runoff-green-infrastructure/low-impact-development/swales-and-roadside-ditches/ here].
===Bioswales===
{{:Bioswales: Performance}}
===Enhanced grass swales===
===Performance===
==Construction==
[[Construction]]
==Galleries==
===Simple grass swales===
{{:Swales: Gallery}}
===Incentives and Credits===
===External Links===
===Bioswales===
{{:Bioswales: Gallery}}
===Check dams===
{{:Check dams: Gallery}}
==See Also==
*[[Bioretention cells]]
*[[Check dams]]
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[[Category:Infiltration]]
[[Category:Infiltration]]
[[Category:Planted]]
[[Category:Green infrastructure]]