Bioretention: Streetscapes

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This is an image map of a curb extension, clicking on components will load the appropriate article.

Hydraulically separated or connected with an underdrain, these are often quite small units of 5 - 50 m2 each. In urban settings the bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. may be bounded entirely with hardscape, restricting options for pretreatment and sheet flow. Amenity and safety can be enhanced on sidewalks with a short (~ 45 cm wall) for seating, although the finished grade is usually only slightly lower than surroundings. Where underground space permits, shade trees are common feature of these facilities, enhancing the streetscape experience and optimizing transpiration. This type of bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. is often designed offlineRefers to a system that when full, stormwater will bypass the practice. Offline systems use flow splitters or bypass channels that only allow the water quality volume to enter the facility. This may be achieved with a pipe, weir, or curb opening sized for the target flow, but in conjunction, create a bypass channel so that higher flows do not pass over the surface of the filter bed., with bypass overflow.

An excellent opportunity for integrating more bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. into the street is through careful design of curb extensions for traffic control. See Roadside safety for design advice specific to this application.

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