Changes

[[File:Bioswale.png||thumb|Bioswale with check dams<br> (vertical scale exaggerated)]]

[[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)]]

[[File:Stepped cells.png||thumb|Stepped bioretention cells alternative for slopes >6 % <br> (vertical scale exaggerated)]]

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 swales:

*An absolute minimum width of 0.6 m is required for bioswales to have healthy plant growth, and to facilitate construction,

*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 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]]

*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]]

Swales may be graded along longitudinal slopes between 0.5 - 6 %:

Swales may be graded along longitudinal slopes between 0.5 - 6 %:

<h3>Pretreatment and inlets</h3>

<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 spreading 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.

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==

==Performance==