Rain gardens
During the past few years we have been active in installing rain gardens in various urban streets. Rain gardens offer many benefits, including cleaning storm water before it gets out to the sea.
How rain gardens work
Storm water diverted off the road is collected in a shallow pond on the surface of the rain garden.
Water then passes vertically through various soil mediums that filter the water to remove harmful chemical pollutants.
This is achieved through physical filtration and biological processes that naturally occur in plants, roots, microbes and soil.
Clean water reaching the bottom of the rain garden is collected in a slotted pipe and directed to the conventional underground drainage system.
Much of the storm water entering these rain gardens doesn’t reach the underground drainage systems.
This is because of the saturation of the soil layers and the water-well underneath the rain garden.
Why we install rain gardens
Rain gardens are a form of Water Sensitive Urban Design (WSUD) that can be adopted at the household, street or district scale to reduce the amount of storm water or rainwater runoff reaching storm water systems.
Rain gardens also improve the quality of storm water entering our drains, creeks, waterways and ultimately Gulf St. Vincent.
Rain gardens use a process known as bio-filtration to remove high percentages of chemical pollutants such as hydrocarbons, nitrogen and phosphorous which are then absorbed over time by natural processes occurring in the soil and plants.
Keeping your trees and plants alive
Rain gardens help street trees and vegetation to survive through long, hot and dry spells by giving them plenty of harvested storm water.
The design we use has been proven to provide water supply for vegetation for several weeks during long periods of dry weather.
Plants used in rain gardens are carefully chosen so that they are best suited to the conditions.
Plants need to be tolerant of extreme saturated conditions during winter months and dry conditions during the summer.
Choosing the right street trees
The street trees selected for these rain gardens are Yellow Bloodwood (Corymbia Eximia).
This Australian native tree has similar characteristics to eucalyptus trees.
Planted on the floor of the rain garden are a variety of native reeds, sedges and grasses, some of which are indigenous to the West Torrens area.
The plants used in the rain gardens need a lot less manual watering and have better growth rates and health when compared to typical road verge plants.
They also provide more visual appeal and have increased biodiversity and wildlife.
Rain garden interpretive trail
The City of West Torrens is concerned about the environment and how we can use and reuse resources better.
One of those resources which all suburbs have is storm water (water run off) that comes from the rooftops of houses, roads and footpaths, which normally ends up in drains and flows out to the ocean. The problem with storm water is that is gets polluted with things such as leaves, dust, animal waste, garbage, automotive fluids and cigarette butts, which can all end up in our ocean and harm our aquatic life.
Rain gardens, also known as 'green infrastructure', help filter out those pollutants so that the water that ends up in our creeks, rivers and ocean is much cleaner and safer for our environment. West Torrens has a number of rain gardens in its suburbs. In order to help our community gain a better understanding of how they work, the City of West Torrens has created a Rain Garden Interpretive Trail. This trail, which can be walked, cycled or driven around, covers a number of suburbs which are home to numerous rain gardens.
Check out the online trail.