Council's measures for improving stormwater quality and quantity for public safety and local flood protection.
Rainwater run-off contains pollutants such as nitrogen, phosphorous, suspended solids and gross pollutants (litter). In its natural state, the environment deals with these pollutants through bio-filtration through microbe-containing soil and root systems. However in a conventional urban context, rainfall runoff lands on roofs, paving and other hard surfaces and is discharged directly to local waterways via an impermeable stormwater system. When these pollutants hit the waterways they can create conditions that cause an ecological imbalance, which can harm flora and fauna and cause toxic algal blooms.
The stormwater system is designed to take rainwater from our streets and guttering into the closest waterway. Unlike sewage, stormwater is not treated before it enters our waterways. In some cases it is filtered by traps or wetlands, usually located at the end of the pipe system, but in most cases it flows directly from our streets and gutters into our creeks, rivers, bays and the ocean.
Maintaining our water quality is a challenge we all play a role in. Please do not empty any contaminants into the system, such as paints, oils, poisons or fertilizers. This has a devastating impact on aquatic flora and fauna.
Mansfield Shire Council is working with the community to improve the quality of our stormwater through wetlands, frog technology to eliminate toxic algaes, biofilms and water quality testing in our lakes and rivers.
Water sensitive urban design
Council has measures designed to improve stormwater quality and quantity can complement objectives of public safety and local flood protection.
Water Sensitive Urban Design is applied to protect and enhance our natural waterways in urban catchments by reducing pollution in stormwater runoff. Additionally, recycling the water within our properties is seen as ecologically responsible and hopefully a cost-effective use of a scarce resource.
Water-Sensitive Urban Design re-defines water management and conservation in a practical way. Designing new housing and other developments to incorporate WSUD is about ensuring that water, as a resource, is used as efficiently as possible. So instead of simply removing water from a site without treatment, and creating water quality and quantity problems downstream, water should be stored, reused and treated at every possible opportunity. This helps to create more sustainable developments.
Landscape elements of WSUD, which feature in many new developments include:
- Grass swales (drains)
- Bio-retention drains
- Treatment wetlands (artificially constructed)
- On-site storage systems (above and below ground storage tanks)
- Porous or permeable paving in car parks
The different elements of water-sensitive urban design are usually integrated throughout the development area (often more than one allotment or a new suburb) in a combination known as a 'treatment train'. This involves constructing stormwater treatment devices at locations where the stormwater is collected, channelled and discharged. The selection of treatment options should be based on the removal of pollutants from the surrounding land. Pollutants may include sediment, hydrocarbons, organic materials, heavy metals, pesticides or nutrients (from fertilisers).
Calculation for stormwater design
Council uses a STORM calculator and Model of Urban Stormwater Improvement Conceptualisation (MUSIC) measurement models in the planning application processes in order to determine which design and size is necessary for a specific site.
More information on stormwater and the environment is available at the Your Home website, the Goulburn Broken Catchment Management Authority website and the Environment Protection Authority website.