STORMWAT E R
The importance OF STORMWATER MANAGEMENT Stormwater is rainwater that runs off impervious or saturated surfaces in the urban environment, such as roofs, roads and pavements, and green spaces. In an undeveloped environment, natural vegetation allows for rainwater to infiltrate soils, allowing for transpiration by vegetation and evaporation into the atmosphere. The concrete jungles of Australia's cities generate enormous volumes of stormwater, which has significant environmental consequences for the waterways that receive it. Stormwater harvesting can also help save hundreds of millions of litres of drinking water each year by providing an alternative water supply and play an essential role in the development of thriving green spaces for community use.
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tormwater can carry pollutants including litter, soil, organic matter, grease, oil and metals collected from roads and properties, and fertilisers from gardens, with stormwater run-off cited as the primary cause of urban waterway degradation. In addition to negatively impacting stream ecosystem health, altered flow regimes and poor water quality as a result of stormwater run-off can render urban waterway restoration efforts largely ineffective. It’s also important to note that when excess water falls on impervious surfaces, it runs rapidly rather than soaking gradually into the earth. This can cause flooding, erosion and infrastructure damage if not managed properly. While stormwater clearly harms the environment, it is also a resource that is not being utilised to its full potential.
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UTILITY • AUGUST 2021
Stormwater has a range of non-potable applications in urban environments, including toilet flushing, garden watering, car washing, industrial uses, open space irrigation, ornamental water features, fire fighting, environmental flow provision and groundwater recharge. With appropriate treatment, stormwater can also provide a supplementary potable water supply; however, there are a number of barriers that significantly limit the potable use of stormwater in Australia and overseas, the most important being: • Limited understanding of the hazards of utilising urban stormwater as an alternate water source. In particular, there are very few datasets that have quantified the levels of pathogens and chemicals of concern to human health in stormwater • Minimal knowledge on pathogen and chemical removal in low-energy and affordable stormwater treatment systems that are based on the principles of water sensitive urban design • Non-existent validation procedures for these types of stormwater treatment systems The traditional model of stormwater management aims to drain urban run-off as quickly as possible with the help of channels and pipes, which only increases peak flows and the costs of stormwater management. New technologies for stormwater management have been in existence since the 1970s and include detention and retention basins, permeable surfaces, infiltration trenches, surface and subsurface groundwater recharge, and other control measures. A number of utilities and councils are trialling innovative technologies and adopting local stormwater management projects, which offer the opportunity to improve the health of the surrounding waterways while providing secondary benefits to communities, such as increasing water security and reducing peak summer temperatures.
RESTORING URBAN WATERWAYS TO FULL HEALTH Melbourne Water is one utility working with stakeholders and the community to minimise the negative impacts of stormwater and improve the habitat, ecology and amenity of local waterways. WWW.UTILITYMAGAZINE.COM.AU
