- What is stormwater?
- How are stormwater systems designed?
- Stormwater Pollution
- Stormwater Quality Improvement Devices (SQUIDS)
- Water Sensitive Urban Design (WSUD)
- Stormwater Maintenance Programs
- The Drain Is Just for Rain Project
What is Stormwater?
Stormwater is water generated by rainfall, which does not soak into the ground.
This water generally runs off hard surfaces (roofs, roads, paved areas, yards) and flows into a network of drains and pipes eventually entering nearby waterways. Unlike sewage, stormwater is not treated and any substances entering the drainage system that is not pure rainwater affects the health of our local waterways and beaches.
How are stormwater systems designed?
Stormwater systems are designed to convey run-off generated from rainfall to a safe discharge point and to minimise flooding of surrounding areas. The current practice is to design a minor/major drainage system which is capable of handling small 'nuisance' flows that occur frequently as well as safely conveying large less frequent flows.
The minor system design is the traditional kerb, pit and piped network that are under most of our roads.
For larger flows, it is the intention to contain the excess stormwater within road reserves or within designated drainage channels before discharging to receiving waters.
Due to topographic features, it is common for portions of land within a subdivision or urban area to be set aside to solely convey stormwater. This land is called a 'drainage easement' or 'drainage reserve' and within it will either be an underground pipe or an open drain connected to the downstream drainage system.
Stormwater pollution has been identified as the leading pollutant affecting the health of our local waterways.
The major source of urban stormwater pollution comes from the following sources:
- Litter and dumping of household waste including organic materials
- Household chemicals such as pesticides and herbicides
- Nutrients from garden fertilisers
- Pet waste
- Detergents from washing cars on driveways
- Oils and grease from roads, and
- Construction pollutants such as sediment, cleaning chemicals, paint and concrete washings.
The impact on our waterways ranges from the build-up of poisonous toxins, depletion of oxygen and reduction in light infiltration which all have a detrimental effect on aquatic organisms.
Conversely, increasing nutrient loads in waterways can also lead to the outbreak of blue-green algae and invasive aquatic weeds.
Stormwater Quality Improvement Devices (SQUIDS)
Pollutants such as litter, organic matter, detergents, sediment etc, decrease the amenity and quality of our waterways and beaches.
To reduce these impacts, Council has installed a number of Stormwater Quality Improvement Devices including litter baskets, trash-racks, end-of-pipe nets, gross pollutant traps (GPT), sand filters and constructed wetlands.
There are currently 47 trash racks, nets and cages, 46 GPTs and 10 constructed wetlands in operation within the local government area.
These devices, while effective, are not an ideal solution. They do not stop the source of pollution and are regarded as an 'end of pipe' treatment. The best protection against stormwater pollution is preventing it at the source before it enters the stormwater system.
Here are some helpful things you can do to prevent stormwater pollution:
- Check your car for leaks and keep it well maintained
- Wash cars on grassed areas
- Correctly dispose of litter in appropriate bins
- Reduce the use of pesticides and fertilisers in your garden
- Sweep paths and gutters to remove leaves and lawn clippings
- Always clean up after your pets, and
- Ensure that sediment does not escape from construction sites by using appropriate controls
Please contact Council's drainage engineer on (02) 6581 8111 for further information on the location and function of Council's SQUIDS.
Water Sensitive Urban Design
WSUD is a design technique that recognises all water sources in the urban water system.
It can assist to reduce water consumption, wastewater and the environmental impacts of stormwater on our waterways, while also maximising water re-use.
The key principles of WSUD are to:
- Protect natural water systems within urban developments
- Protect and improve quality of water draining to our natural waterways
- Integrate stormwater treatment into the landscape
- Reduce the amount of run-off and peak flows
- Minimise cost of drainage infrastructure in development
- Reduce potable water demand
WSUD features include SQUIDS (see Stormwater Improvement Structures), grassed or vegetated swale drains, filtration trenches, bio-retention systems, wetlands, rainwater tanks, greywater re-use and rain gardens.
These features are now being incorporated in stormwater design throughout the local government area.
Stormwater Maintenance Programs
Council has now established a stormwater maintenance team dedicated to proactive maintenance of stormwater infrastructure. These resources enable Council to implement important preventative maintenance and to respond quickly to customer requests for routine maintenance.
This expanded service has been made possible by the introduction of the Stormwater Levy in 2006 that is being used to implement improved stormwater drainage services to the community.
In the first year of operation of the stormwater maintenance team, Council has been able to reduce response times for routine stormwater drainage maintenance work from over 60 days to around 12 days.
The Drain Is Just For Rain Project
This project was designed to raise awareness and knowledge levels of business owners, their employees and contractors (such as cleaners) through simple education tools such as brochures, drain stencilling and workplace stickers.
The materials have been selected for their general message and are being used in large and small shopping districts.