Waterways

Water sensitive urban design (WSUD) is a new way of sustainably managing stormwater from urban areas to protect against environmental harm to our creeks, rivers and the receiving environment of Moreton Bay.

Basic aim

Stormwater runoff from urban areas has a significant impact on Logan's creeks, rivers and Moreton Bay. The runoff from an urban catchment contains a variety of pollutants and is a larger volume compared to runoff from similar non-urban catchments. WSUD aims to seamlessly integrate mitigation measures into the urban landscape to remove pollutants and reduce the amount of runoff generated. In Logan, all new development is required to apply the principles of WSUD to mitigate the impacts of its runoff.

Pollutants of concern

While urban stormwater can contain a wide range of pollutants, the four of primary concern to our waterways are:

  • Gross pollutants (e.g. litter, tree branches and other large matter)
  • Sediment (e.g. fine particles such as clay and sand)
  • Nitrogen (often from excess fertilizer use)
  • Phosphorous (often found in lawn fertilizers and manure).

Protecting our waterways

A variety of technologies are available to achieve the goals of WSUD including:

  • Bioretention systems
  • Constructed stormwater wetlands
  • Rainwater tanks
  • Swales
  • Buffer strips
  • Sediment basins
  • Gross pollutant traps

Rainwater tanks are the most common example of WSUD in practice. Collecting roof water in rainwater tanks and re-using it for watering gardens and other outdoor use minimises the amount of stormwater that enters our waterways reducing erosion, while helping to recharge groundwater and baseflow stores that keep our waterways flowing in dry times. In addition, using rainwater for outdoor use and for washing machines instead of drinking water, reduces the demand placed on potable water supplies and helps 'drought proof' our cities.

Bioretention systems are a type of a stormwater treatment system commonly constructed in new developments to capture and treat stormwater to remove pollutants. For the majority of the time they look like landscaped garden beds planted with native grasses and sedges such as Lomandra. When it rains, stormwater is directed into the bioretrention system where it temporarily ponds before filtering through a sandy soil called the filter media. Sediment, nitrogen and phosphorous are removed during this filtration. Most of the water is taken up by the plants and the remaining treated water is collected by pipes under the filter media and discharged to the stormwater system.

Constructed stormwater wetlands are another type of stormwater treatment system commonly constructed in new developments. They look like densely planted water bodies with little open water. When it rains, stormwater is directed into the wetland where sediment is able to settle out. The nutrients, nitrogen and phosphorous are used by the plants, and are also removed by beneficial micro-organisms which grow on the plant stems in what is known as a biofilm. A recent trend in constructed stormwater use has been to treat the water entering urban lakes to prevent algal blooms and improve the health of the lake.

What can I do at home?

The most simple and effective way to implement WSUD at home is to install a rainwater tank for outdoor use such as watering the garden. Even better, connecting it to non-potable uses such as the washing machine or the toilet will allow you to use more stormwater, further reducing your use of drinking water.

You can also build a type of small bioretention system known as a rain-garden to collect and treat water from roof space which isn't connected to a rainwater tank, the overflow from your rainwater tank or even from paved surfaces such as your driveway.

The South East Queensland Healthy Waterways Partnership has a guide to building your own rain-garden (PDF), while ABC's Gardening Australia has a segment on how to build a rain-garden.

Just remember, only a licensed plumber can make alterations to stormwater pipes.