Filtered Streets for Healthy Creeks

In order to restore the health of the creek treating and retaining stormwater runoff from streets, as well as houses is important This will provide for a reduced quantity and increased quality of water entering the creek which will allow for a return back to near natural (pre-development) levels (click here for more information).

1. The Problem with streets

2. Addressing the problem

3. Proposed works for Mt Evelyn

There are a number of ways in which streets can be treated to reduce the runoff and pollutants entering creeks. The most effective and efficient way is by building swales or raingardens along the edge of streets, both of which have locations where water is able to soak into the ground.

A typical table drain/swale gutter in Mt Evelyn (Bailey Road, Mt Evelyn). This type of road allows for  water to soak into the ground, and also provides some filtration of rainwater.

Some swales already exist in the catchment (about 40% or roads), for example along Bailey Rd and Clancy Rd (see photo below). During small rainfall events, these swales (or table drains) filter and clean the water running off the street, removing pollutants and allowing some of the water to soak back into the ground. This means the street has less of an impact on the Little Stringybark Creek.

To improve the health of the Little Stringybark Creek it will be beneficial to modify the streets that have concrete curbs and gutters with measures like swales or raingardens that will allow water to soak into the ground or be filtered before it reaches the creek.

Building raingardens in nature strips can be a very attractive addition to a streetscape. Similar raingardens to the ones being constructed in the streets around the Little Stringybark Creek catchment are now being built in many areas across Melbourne as well as overseas. These raingardens help improve the quality of stormwater and reduce the quantity of stormwater entering our rivers and creeks.

Raingardens filter pollutants such as oil and dirt that is washed off our streets and into our creeks when it rains. They also allow the water to filter into the soil and be used by the plants and ‘good’ bugs in the soil. The process of rain-gardens filtering and soaking rainfall is a way to mimic nature and helps to restore more natural flow regimes in downstream rivers and creeks.

Sadly, the Little Stringybark Creek is being damaged by polluted stormwater in high quantities when it rains. Fortunately, the streets  of Mt Evelyn have been chosen as a pilot to install many raingardens over the next few years to filter and reduce the stormwater over the next few years. Monitoring of the creek over time will determine how successful we have been at improving its condition. 

A Filtered Streets for Healthy Creeks Program has just begun and will support the  installation of raingardens in the Little Stringybark Creek catchment area. This is a complementary project to the existing Stormwater Tender project. Working together on this project is the Shire of Yarra Ranges and Melbourne Water. This project is anticipated to run over the next 5 years from 2008 to 2012.

The map below shows the first few sites that are currently being investigated for their potential to install raingardens or swales.

click on map for a larger view

Fortunately, raingardens require little on-going maintenance as they’re similar to a normal garden bed. This may consist of some occasional weeding and removal of any litter that may build up over time (similar to any open space area). Raingardens typically include hardy native ground cover species – although trees and shrubs can also be suitably grown.

While the project team would encourage residents to look after the raingardens by weeding them– it would be council’s responsibility to address issues like blocked inlets and outlets.