by Aimee Peters
The City of Sydney Council has developed Australia’s first city-wide recycled water network as part of theSustainable Sydney 2030 program. The Decentralised Water Master Plan will improve water efficiency in Sydney through harvesting and recycling stormwater for non- drinking purposes and therefore reduce stormwater pollution.
The plan will apply to the City of Sydney Local Government Area which currently imports 32 gigalitres of drinking-quality water each year from Warragamba Dam.
Every day treated, drinkable water is pumped 68 kilometres from the dam to the city, supplying Sydney with 80 per cent of its water. However, only two per cent is actually drunk and the rest is used for non-drinking purposes that do not require the water to be treated.
The Lord Mayor Sydney Clover Moore says more than half of Sydney’s future water demand could be met with non-drinking water.
The plan predicts that a combination of stormwater, seawater and waste water will produce up to 12 billion litres of recycled water each year to cater for Sydney’s growing population.
This has become an increasingly important issue as it has been predicted that Sydney’s population will grow 30 per cent by the year 2030.
Chris Derksema City of Sydney Sustainability Director, says because of drought in the past, Sydney has not had enough water to maintain parks and gardens so it is important to have a sustainable water supply for the future. He says the Master Plan has a target to save 10 per cent on the 2006 demand for water by 2030.
The Council will be working in co-operation with the State and Federal Governments to implement the plan. International engineer consultants Gutteridge Haskins & Davey, The Sydney Public Private Partnership Consultants and the Institute of Sustainable Futures at the University of Technology will also be involved.
The recycling of stormwater will also reduce Sydney’s pollution. Every year, 3,500 tonnes of sediment, pollution and nutrients are dumped into Sydney waterways through stormwater run-off. Stormwater is made up street litter, animal droppings, cigarette butts, leaf litter, oil and silt.
Whenever Sydney has rain, all this is washed into the harbour and unlike sewage, stormwater is not treated before being released into waterways. This is what makes Sydney beaches dangerous for swimming after rain because of the increased risk of infection and disease.
Kirribilli resident, Jenny McDougall says, “Seeing the harbour so murky, brown and riddled with litter after rain will be a sight I don’t miss.”
In the last 20 years, Sydney Water has implemented 64 Stormwater Quality Improvement Devices that help to clean stormwater. These include trash racks, litter booms and sediment traps. So far 35,000 cubic metres of litter and 39,000 tonnes of sediment from stormwater have been removed before it has reached waterways.
Sydney Water has also worked with local councils to install stormwater harvesting systems. There are already four parks in Sydney being irrigating through these systems and the City of Sydney says they want more introduced.
Completed in 2010, the North Sydney Stormwater Re-use Project harvests, filters and treats stormwater from a 94 hectare catchment to irrigate North Sydney Oval, Cammeray Golf Course and North Sydney’s largest sporting and recreational area, St Leonards Park. The project is expected to save 90 million litres of drinking water each year.
It had also led to theimprovement in water quality in the area through the removal of 50 to 60 tonnes a year of pollutants as well as the reductionin total volumes of stormwater runoff into Sydney Harbour.
Projects such as this are among the first of a suite of initiatives being formulated under the Decentralised Water Master Plan.
In September, Sydney City Council ran a public exhibition of the first draft of the Plan. The Plan’s key aims:
Improved water efficiency in buildings across the City of Sydney to save 10 per cent on the 2006 demand by 2030; replacement 54 per cent of drinking water used for non-drinking purposes with recycled water; a reduction by a quarter of water use in City buildings, parks and open spaces by 2030; water-sensitive urban design, including rain gardens, swales, infiltration trenches within street scapes and permeable pavers on footpaths to filter or retain stormwater and reduce pollution discharged into waterways; and diversified water sources to include recycled and treated waste water, stormwater, groundwater, roof water and sea water to reduce dependence on the drinking water supply.