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Line 46: − − <h4>Check dams</h4> − <p>Check dams are a feature of enhanced swales. They promote infiltration and evaporation by promoting limited ponding. − To design check dams into a swale: − #The height of each dam is determined by the depth of ponded water that will infiltrate in 24 hours. The infiltration may be into the native soils, into biomedia, or some other soil amendment may be proposed in the design. − #Dams are usually installed between 10-20 m along the swale. They are distributed such that the crest of each dam is at approximately the same elevation as the toe of the upstream dam. If the slope along the swale varies, so should the distance between the dams. − The objective of these design recommendations are to maximize the distribution of ponded water along the whole BMP. Detailed design may require iteration of the dam heights and distances along each section of a long swale. − *Dams may be constructed of any resilient and waterproof material, including: rock gabions, earth berms, coarse aggregate or rip-rap, concrete, metal or wood. − *Energy dissipation and erosion control measures should be installed in the 1 - 2 m downstream of each dam. Examples include large aggregate or [[Turf reinforcement|turf reinforcement]] − <h4>Other components</h4> − *[[Underdrain]] − *[[Bioretention: Filter media]]
→Design
<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 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.
==Performance==
==Performance==