Water Sensitive
Urban Design

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Cramer Street Raingardens

Cramer street, Preston. Near Preston Market.

The Cramer Street raingardens are some of the many raingardens across Darebin working to improve the quality of water flowing into the Merri and Darebin creeks.

Cramer Street is a busy main road located in the heart of Preston, close to bustling High Street. Three raingardens have been installed along Cramer Street between Preston Market and Preston City Oval. The project was designed as a part of Preston Connect, a project aiming to revitalise Cramer Street, and the Preston City Oval Gateway Improvement project. The Preston Market and the Northern Bullants Football Club have strongly supported the project because it helps makes Preston a safer place to walk and cycle, and adds amenity to the area through greening the street.

Raingardens are designed to capture and filter stormwater. Stormwater is rainwater that flows over hard surfaces in urban areas, such as roofs, roads, carparks and gutters. Raingardens mimic processes found in natural wetlands. The soil and plants in the raingarden absorb some of the water, and the rest of the water slowly moves down through the different layers of the rain garden. The soil and plants act as a filter by removing pollution found in the stormwater before it flows into the stormwater drain. This stormwater is then carried directly to our creeks. Water sensitive urban design (WSUD) features such as raingardens help to filter out these pollutants, making the water cleaner and our waterways healthier.

Outcomes:

Improves water quality in our waterways.
Prevents erosion of creek banks by slowing the flow of water.
Reduced levels of nitrogen, gross pollutants (litter) and phosphorous entering our waterways.
An attractive and green streetscape for residents, with the added advantage of slowing traffic and creating a safer walkway for pedestrians.
An engaged community that is educated on the benefits of water sensitive urban design.

Project description:
The Cramer Street raingardens help to capture and clean stormwater before it enters the Merri creek

Purpose:
Designed to improve the quality of water entering our waterways

Catchment:
Merri Creek

Completion date:
March 2013

Project details

How the System Works

A raingarden is a special type of garden bed that is designed specifically to receive and filter rain run-off from hard surfaces such as streets, driveways, paving and gutters.

Stormwater flowing down the gutters of Cramer Street enter the raingardens via an inlet grate that leads to the raingarden. The raingarden comprises of a series of layers, allowing water to collect and settle on the garden surface before soaking through to the plants and filter media.

The top layer is planted with native plants and grasses that are able to tolerate long periods without rain, and large inundations at other times. These plants have deep, fibrous and spreading root systems, taking up water and nutrients as the water moves through the system. A layer of large pebbles on the surface of the raingarden helps to trap litter and sediment.

Below the surface, layers of soil, sand and organic material (known as bioretention media) work to filter the stormwater of toxins. Layers of sand and gravel also help drain water to the lower levels. You can see images here that show what the bioretention media looks like, when it was installed.

As water filters through the raingarden, it percolates through the layers, where contaminants from the street are slowly trapped. Larger particles are generally trapped in the top layers, with smaller particles trapped within the lower levels. At the lowest level is a slotted pipe, where the cleaned, filtered water can exit the raingarden and is drained to the Merri Creek.

System Components

Gravity System
The raingardens use gravity to capture stormwater in the garden beds. The rainwater is collected via runoff from the steep roads and gutters in the area. The location of the raingardens was an important design consideration in this project.

Top layer
Deep rooted plants such as kangaroo paw, sedges, club rush, hollow rush, mat rush and cushion bush.

Middle layers
Boulders, gravel mulch, bioretention media.

Bottom layer
Crushed rock laying over a slotted drain connected to stormwater system.

Project Timeline

This project was completed in March 2013.

Maintenance and Monitoring

Council will remove weeds and litter, and replace plants in the raingarden as required. Every few years, Council will also replace the top layer of gravel, and remove fine particles of pollutants with a suction hose.

Photos and Images

PROJECT BENEFITS

Benefits to Community

The rain garden provides an attractive and greener streetscape for residents. The raingardens improve the streetscape and increase biodiversity (the range of plants and animals) in the area as well as reducing the risk of flooding, by re-routing some of the stormwater that would normally flow into the stormwater system. The raingardens provide a smart and sustainable environment to be enjoyed by residents and visitors.

Environmental Benefits

Many animals and insects call our local creeks and waterways home, such as the platypus, rakali (our native water rat), water bugs, frogs, fish and birds (such as the Sacred Kingfisher). Our waterways provide food and habitat for these and other animals and plants, so it is important we keep them safe and clean.

When it rains, contaminants washed from our streets end up in the waterways. These contaminants include those we can see, such as plastics and cigarette butts, but also include those we can’t see, such as oils, detergents, bacteria and pesticides. Contaminants pollute our waterways, resulting in a direct negative health impact on our local aquatic wildlife and plants.

Raingardens clean, filter and separate water from contaminants, before the water enters our creeks, rivers and ultimately the ocean. Raingardens slow down the speed that stormwater enters our waterways, reducing problems of erosion (loosening of soil) on creek banks. Slowing the speed at which water enters our waterways helps to improve our overall stream water quality.

ACKNOWLEDGEMENTS

Darebin City Council ackowledges the Wurundjeri people as the traditional owners and custodians of this land and pays respect to their Elders past and present.