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| + | [[File:20161024 100338 550x550.jpg|thumb|Bioswale, County Court Boulevard, Brampton]] |
| This article is about installations designed to capture and convey surface runoff along a vegetated channel, whilst also promoting infiltration. <br> | | This article is about installations designed to capture and convey surface runoff along a vegetated channel, whilst also promoting infiltration. <br> |
| For underground conveyance which promotes infiltration, see [[Exfiltration trenches]]. | | For underground conveyance which promotes infiltration, see [[Exfiltration trenches]]. |
− | [[File:20161024 100338 550x550.jpg|thumb|Bioswale, County Court Boulevard, Brampton]]
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| {{TOClimit|2}} | | {{TOClimit|2}} |
| ==Overview== | | ==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 design of both may increase the benefits:<br> | | 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 design of both may increase the benefits:<br> |
− | <strong>[[Bioswales]]</strong> are sometimes referred to as 'dry swales', 'vegetated swales', or 'water quality swales'. This type of structure is similar to a [[Bioretention cells|bioretention cell]] but with a long linear shape (surface area typically >2:1 length:width),<br>
| + | '''[[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> |
− | <strong>[[Enhanced grass swales]]</strong> 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.
| + | '''[[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 make a relatively little contribution to water volume and quality control than many other BMPs, but they may feature as part of a site-wide treatment train approach. |
| + | {{float right|{{#widget:YouTube|id=8b3-a_Na1dE}}}} |
| {{textbox|Swales are an ideal technology for: | | {{textbox|Swales are an ideal technology for: |
| *Sites with long linear landscaped areas, such as parking lots | | *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}} |
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| {|class="wikitable" | | {|class="wikitable" |
| |+ Types of Swale | | |+ Types of Swale |
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| A linear design (surface area typically >2:1 length:width) is a common feature of a swales: | | A linear design (surface area typically >2:1 length:width) is a common feature of a swales: |
| *An absolute minimum width is 0.6 m is required for bioswales to have healthy plant growth, and to facilitate construction, | | *An absolute minimum width is 0.6 m is required for bioswales to have 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 trapzoidal 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]] | + | *Grassed swales are usually mown as part of routine maintenance, so the cross section will be triangular or trapzoidal 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]] |
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| Swales may be graded along longitudinal slopes between 0.5 - 6 %: | | Swales may be graded along longitudinal slopes between 0.5 - 6 %: |
− | *Check dams are required on slopes > 3 %. | + | *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 weir. | + | *Slopes > 6% can accommodate a series of stepped [[bioretention cells]], each overflowing into the next with a spillway. |
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| ==Design== | | ==Design== |
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| ==Performance== | | ==Performance== |
− | <h3>Bioswales</h3>
| + | 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}} | | {{:Bioswales: Performance}} |
− | <h3>Enhanced grass swales</h3>
| + | ===Enhanced grass swales=== |
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| ==Construction== | | ==Construction== |
− | {{:Infiltration:_Construction}}
| + | [[Construction]] |
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− | ==Incentives and Credits== | + | ==Galleries== |
− | <h3>In Ontario</h3>
| + | ===Simple grass swales=== |
− | <strong>City of Mississauga</strong><br>
| + | {{:Swales: Gallery}} |
− | 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].
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− | <br>
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− | <h3>LEED BD + C v. 4</h3>
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− | <h3>SITES v.2 </h3>
| + | ===Bioswales=== |
| + | {{:Bioswales: Gallery}} |
| + | ===Check dams=== |
| + | {{:Check dams: Gallery}} |
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| ==See Also== | | ==See Also== |
| *[[Bioretention cells]] | | *[[Bioretention cells]] |
| *[[Check dams]] | | *[[Check dams]] |
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| [[Category:Infiltration]] | | [[Category:Infiltration]] |
| [[Category:Green infrastructure]] | | [[Category:Green infrastructure]] |