An EarthCache provides an earth science lesson through a visit to a unique geological feature.
At the corner of Wright Street and Compton Street/Russell Street, there is a Rain Garden, named "Wright Street Rain Garden".
This rain garden is designed to clean polluted stormwater run-off from the road. The stormwater contains oil and petrol from cars, sediment, heavy metals and organic pollutants. The especially selected soils and plants in the rain garden help to trap and treat the contaminants, then the treated stormwater collected by the rain garden underdrains and any subsequent overflow discharges to the existing downstream drainage system. The rain garden also has a saturated zone, which acts as a well at the base of the system to provide water to the plants during dry periods.
In an ordinary rain garden design, rain that falls on our roads and streets, is directed into the rain garden so it can be taken up by thirsty plants. This helps them to grow healthy so they can provide shade for us and habitat for local wildlife. Any excess water not needed by the plants trickles through various layers of soil, pebbles and rocks. This natural process removes pollutants out of the water so it’s cleaner when it enters the stormwater system. Rain gardens also help to reduce local flooding, plus they can lower local temperatures during hot weather.
Rain gardens are also called "bio-filtration". ‘Bio’, meaning plants and vegetation, slow the flow of water and use it to grow. ‘Filtration’, the water filters through into the layers below (filter media, transition layer, drainage layer). There are three types of filtration: physical, biological and chemical. The process of physical filtration is the mechanical and physical removal of solids or fluids from a fluid through forcing the flow of the filtered liquid through a medium. Biodegradation is the disintegration of materials through bacteria, fungi or other biological means. Chemical media filtration is considered the most effective when desired to remove dissolved or attached pollutants, and the pollutants that are usually targeted in chemical filtration processes are heavy metals, nutrients, organic material and fine sedimentation.
This project is jointly funded by Adelaide City Council and the Australian Government's National Landcare Programme, partnering with the Environment Protection Authority to implement "Catchment to Coast", a project focussed on improving water quality across urban Adelaide.
To log this EarthCache, please answer the following questions, and send answers to owner via Message Center. You may log your found, and send answers within 7 days. Unqualified log entry will be deleted. If visited in a group, please mention all group members while submitting the answers. No spoiler photos. No step in the rain garden.
1. Observe the rain garden. Flooding may harm the plants. What's been done to prevent it?
2. Rain garden can trap and treat the contaminants in stormwater. In your opinion, which material can pollute stormwater? List 1 or 2.
3. In your opinion, what are the benefits can be provided by this rain garden, to the community? List 2 or 3.
4. (optional) Take a photo of yourself or a personal article in front of the rain garden and add it to your log.
Reference: www.watersensitivesa.com/ www.resilienteast.com/water