Green Infrastructure is a sustainable approach to solving urban stormwater problems while providing community benefits such as enhanced aesthetics and recreational opportunities. Stormwater is managed through designed systems that mimic natural watershed functions, such as infiltration and evapotranspiration. Green infrastructure includes vegetated curb extensions, rain gardens, planter boxes, porous asphalt, porous concrete, vegetated infiltration beds, rainwater harvesting, tree trenches, and many other methods.
Rain Gardens are vegetated collection areas with absorbent soils for managing excess stormwater runoff. The purpose of a rain garden is aesthetic as well as functional. Rain gardens are often landscaped with native plants in order to provide rain collection areas that will naturally thrive in their environment. They can be placed in lawn areas, in islands of paved areas, along roadways, and in other small open spaces adjacent to impervious surfaces. Since a rain garden can be sized and shaped to fit landscape restraints, multiple bioretention areas can be placed throughout a site to capture runoff from various surfaces.
Planter boxes are planted stormwater structures that filter and temporarily store runoff before draining. Planter boxes are ideal for sites with space constraints, as is often the case in highly urban environments. They can be placed against buildings, along walkways and roadways, and any other area with a small narrow open space available. Planter boxes can be on top of the existing surface or can be at surface grade, and they can be various shapes and sizes.
To see a movie of a urban planter box in action at the Waterview Recreation Center click here.
Porous asphalt, unlike standard asphalt, is constructed with limited fine aggregates allowing water to pass through the pavement. Porous asphalt must be designed with a subsurface storage/infiltration bed that captures the runoff. It is a technique that allows stormwater management to occur within the built environment which helps to reduce overall site disturbance. It is ideal for parking lots, paths, playgrounds, and other similar uses.
Porous concrete, similar to porous asphalt, is a pervious version of concrete. Porous concrete has a slightly different look than other concretes, but provides an effective tool for reducing impervious areas especially in urban environments.
To see a movie of porous concrete in action at the Waterview Recreation center click here.
A tree trench is a linear stormwater management feature consisting of trees planted in several feet of amended planting soils designed to capture runoff from adjacent impervious areas. Tree trenches are applicable in linear areas with limited space to manage stormwater, such as along streets. In addition to managing stormwater, tree trenches enhance aesthetics by providing greening, improve air quality, and reduce the urban heat island effect.
A street bump-out, or curb extension, is an extension of typical curb that creates an open space that is used to temporarily store and filter runoff. Street bump-outs reduce stormwater flow velocity and volume, as well as improve water quality, with vegetation and possibly infiltration. A street bump-out can be implemented in any street of adequate width. In addition to enhancing street aesthetics and providing stormwater management, street bump-outs provide traffic calming, which improves pedestrian safety.
Cisterns or Rain Barrels are large underground or surface containers that capture small frequent rainfall from roof leaders and store the water for other uses onsite. Water needs for irrigation and fire protection uses can be reduced through the use of rainwater harvesting systems while at the same time reducing stormwater runoff. Also, potable water needs can be reduced by using greywater stored in cisterns for toilet flushing.