Bioretention: Streetscapes

This is an image map of an extended tree pit, clicking on components will load the appropriate article.

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 bioretention 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 bioretention is often designed offline, with bypass overflow.

An excellent opportunity for integrating more bioretention into the street is through careful design of curb extensions for traffic control. See Roadside safety for design advice specific to this application.

Gallery

• 

  Curb extension in Victoria. Image credit Dylan Passmore

• 

  'Offline' streetscape bioretention with trees, King Street, Kitchener

• 

  Bioretention on residential street, with covered drain inlet (grate in the gutter) and iron grate covered overflow in the centre of the cell, Hinsdale, IL Photo credit: CNT

• 

  Curb extension in downtown Indianapolis, IN

• 

  Curb extension on Queen Lane, in Philidelphia
  Photo credit: PWD

• 

  Rainwater harvesting cistern, which discharges to tree pits during dry conditions. Image credit Mississippi WMO

• 

  Extended tree pit planting in USA
  Photo credit: USEPA

• 

  A right of way bioswale installed by the New York City Department of Environmental Protection on Dean Street, Brooklyn

See Also

• Bioretention cells
• Stormwater planters

---

• Perennials
• Grasses
• Curb cuts
• Forebays
• Overflow
• Mulch
• Filter media
• Choker layer
• Reservoir
• Trees
• Soil cells

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

Refers 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.

Refers 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.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

Tank used to store rainwater (typically roof runoff) for later use.

Linear bioretention cell designed to convey, treat and attenuate stormwater runoff. The engineered filter media soil mixture and vegetation slows the runoff water to allow sedimentation, filtration through the root zone, evapotranspiration, and infiltration into the underlying native soil.