Operating since 1897, Werribee Farm — now known as the Western Treatment Plant — has played a crucial role in the development of our city.
Melbourne's first sewage treatment farm
In 1888, a Royal Commission was carried out to find a solution to Melbourne’s waste problems. Methods for disposing of human waste were very basic at the time: sewage ran through open channels into the Yarra River and Hobsons Bay, and diseases like cholera and typhoid were rife.
The Commission’s findings led to an ambitious plan to build an underground sewerage system — a network of pipes, sewers and drains to carry sewage from homes and factories to a sewage treatment farm.
In 1892, the newly-established Melbourne and Metropolitan Board of Works began buying land at Werribee, chosen for its low rainfall and suitable soils. The Werribee Farm began operating in 1897.
Historical treatment methods
The plant's sewage treatment methods have changed over time, and previously included:
- land filtration
- grass filtration
- lagoon treatment
The land filtration method dates back to 1897, and was the main way of treating sewage during summer. The process normally took about three weeks and happened in cycles:
- An open paddock was flooded with sewage up to 10 centimetres deep, taking one to two days.
- The land filtered out rubbish and other solids — grass used nutrients from organic waste, and bacteria in the soil broke down pollutants.
- As the paddocks dried out, filtered sewage seeped through the soil, taking another five days.
- Treated effluent flowed out the lower end of the paddock into an earthen drain, which carried it to Port Phillip Bay.
- Sheep and cattle grazed on the paddocks for about two weeks, before the land was flooded with sewage again.
The grass filtration method was adopted in the 1930s as the main winter treatment method. It involved two stages:
- Pre-treatment: sewage entered large concrete tanks, which used a process of sedimentation to remove rubbish. Lighter rubbish floated to the top while heavier rubbish sank to the bottom, leaving a middle layer of primary treated sewage.
- Filtration in grass paddocks: the primary treated sewage trickled over sloping bays covered with a type of grass that tolerated continuous flooding. This filtered out all other solids, and a film of bacteria on the grass and in the soil removed pollutants. At the end of the bay, the filtered sewage flowed into earthen drains which took it to Port Phillip Bay.
The first treatment lagoon was constructed in 1936. Lagoon treatment facilities have been continuously upgraded to meet the needs of Melbourne’s growing population, with the first large, modern lagoon installed in 1986.
Today, all sewage at the Western Treatment Plant is treated in modern lagoons, which replace the old lagoons and traditional filtration methods. The new methods remove large amounts of nitrogen that would otherwise enter the bay, and produce high-quality recycled water — a valuable resource used both on and off site.
Moving to a modern era
The Western Treatment Plant contains a network of lagoons, wetlands, inter-tidal and shoreline areas that provide a haven for thousands of birds, including thousands of migratory waders that fly 12,000 kilometres from Siberia to avoid the harsh northern winter. The plant and areas of the surrounding bay and peninsula were declared a sanctuary for native animals in 1921, and in 1983 the plant became a Ramsar-litsted wetland, internationally recognised for supporting waterfowl.
In 2004, Melbourne Water completed a $160 million upgrade of the plant. This work stemmed from a CSIRO study which found that Port Phillip Bay could be damaged if nitrogen loads entering its waters continued to increase.
|1888||Royal Commission into public health following cholera and typhoid outbreaks in Melbourne.|
|1890||Melbourne and Metropolitan Board of Works established.|
|1897||Western Treatment Plant (then known as Werribee Farm) began operations. First homes connected to Melbourne’s sewerage system.|
|1921||Parts of Port Phillip Bay and Bellarine Peninsula including the Western Treatment Plant declared a sanctuary for native animals.|
|1982||Western Treatment Plant declared a Ramsar site, internationally recognised for its wetland habitat especially for waterfowl.|
|1996||Port Phillip Bay Environmental Study by CSIRO recommended reduction in nitrogen loads to the bay.|
|2004||Plant upgraded to reduce nitrogen loads to the bay. Recycled water irrigation replaced sewage irrigation across the site. Land and grass filtration methods stop being used.|