Western Treatment Plant facts for kids
The Western Treatment Plant is a huge facility that cleans up Melbourne's wastewater. It's located in Cocoroc, Victoria, Australia, about 30 kilometres west of Melbourne's city centre. This plant covers a massive area of 110 square kilometres.
It was built way back in 1897 and is now run by Melbourne Water. The plant is next to the Werribee River and Avalon Airport. It's also a very important wetland, recognized internationally as part of the Port Phillip Bay (Western Shoreline) and Bellarine Peninsula Ramsar Site.
The Western Treatment Plant handles about half of Melbourne's wastewater, which is around 485 million litres every day! It also creates almost 40,000 million litres of recycled water each year.
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How Melbourne Solved Its Waste Problem
A Smelly City Needs a Solution
In the 1850s, gold was discovered in Victoria. This made Melbourne a very rich and fast-growing city. By the 1880s, about 500,000 people lived there.
But Melbourne had a big problem: pollution. People even called it "Marvellous 'Smellbourne'" because of how bad the city's waste disposal was. Most household waste, like dirty water from kitchens and bathrooms, went into open drains. These drains flowed into streets, then into local rivers and creeks. Waste from farms and factories also ended up there. This turned Melbourne's waterways into open sewers, leading to diseases like cholera and typhoid.
Planning a New System
In 1888, a special group called a Royal Commission was formed. Their job was to find a solution for Melbourne's waste. They came up with a big plan to build a sewerage system. This was a network of underground pipes and drains. It would carry wastewater from homes and factories to a special farm for cleaning.
In 1892, a new group called the Melbourne and Metropolitan Board of Works (MMBW) started buying land. They chose Werribee because it didn't get much rain and had good soil. The Western Treatment Plant, then called Werribee Farm, began working in 1897.
A famous British engineer, James Mansergh, helped design the system. Local engineer William Thwaites was in charge of building it. At that time, most cities just dumped their waste into rivers or the sea. But Mansergh suggested cleaning Melbourne's wastewater by spreading it over land. This was a very advanced idea for the time.
The Main Outfall Sewer
The Main Outfall Sewer was built between 1892 and 1894. It was a key part of Melbourne's new sewerage system. Building it was the biggest engineering project in Victoria at that time. About 1300 workers helped build it.
This sewer was a long channel, sometimes a tunnel, made of brick or concrete. It also had three brick bridges called aqueducts. It stretched for about 27 kilometres (16 miles). It ran from the old pumping station in Spotswood (now part of Scienceworks Museum) all the way to the Western Treatment Plant.
Today, the Main Outfall Sewer is no longer used for wastewater. A newer system, the Western Trunk Sewer, does its job. But the old sewer is now listed on the Victorian Heritage Register. This means it's important for Victoria's history and engineering.
Making the Plant Better
In 1996, a study found that too much nitrogen going into Port Phillip Bay could harm it. So, they suggested reducing the nitrogen. In 2004, Melbourne Water finished a big upgrade to the plant. This cost $160 million and helped reduce nitrogen levels.
Instead of using raw wastewater to water the land, they started using recycled water for irrigation. Older methods of cleaning water using land and grass were stopped.
Fun Facts About the Area
A popular walking and bicycle path called the Federation Trail follows the old Main Outfall Sewer. This path is 23 kilometres long.
There's also a project called "Greening the Pipeline." It aims to turn part of the old pipeline area into a 40-metre wide park. This will connect communities in Melbourne's western suburbs.
How Wastewater Is Cleaned
The Lagoon System
The Western Treatment Plant uses modern lagoon systems to clean wastewater. A lagoon system has about 10 large ponds. Each pond can hold around 600 million litres of water. Wastewater flows slowly through these ponds. Tiny living things called bacteria break down the dirty stuff, called organic material.
The water gets cleaner as it moves from one pond to the next. There are two main types of ponds:
- Anaerobic ponds: These ponds have no oxygen. They have special bacteria that work without air.
- Aerobic ponds: These ponds have oxygen. They have different bacteria that need air to break down waste.
Making Electricity and Stopping Smells
The plant uses huge covers over some ponds. These covers capture methane gas. This gas is a by-product of cleaning wastewater and is called biogas. The biogas is then turned into renewable energy.
The Western Treatment Plant makes about 95% of the electricity it needs each year. Capturing and using biogas also helps the environment. It greatly reduces greenhouse gases and bad odours. Since 1992, the plant has cut about 90% of its bad smells.
Recycling Water for Many Uses
In 2004, a water recycling plant was built at the Western Treatment Plant. This plant cleans recycled water to a very high standard. This means the water can be used for many more things.
In one year, the plant supplied almost 30,000 million litres of recycled water. Most of this water was used to water 85 square kilometres of pasture. This pasture feeds 15,000 cattle and 40,000 sheep! It also helps manage salty soil and keep the wetlands healthy.
About 1,921 million litres of the cleanest recycled water was sent to other users. This included farmers in the Werribee market garden area to grow vegetables. Local councils also used it to water sports grounds, parks, and gardens.
Any treated water that isn't recycled is safely released into Port Phillip Bay. This is done under a special licence from the EPA Victoria.
A Home for Wildlife
In 1921, parts of Port Phillip Bay and the Bellarine Peninsula, including the Western Treatment Plant, became a sanctuary for native animals. Then, in 1983, the plant was named a Ramsar site. This means it's an internationally important wetland, especially for waterbirds.
The Western Treatment Plant is one of Australia's best places for birding. About 270 different kinds of birds have been seen there! On the plant's edge is the Murtcaim Wildlife Area. It has one of the last natural saltmarshes on Port Phillip.
The cleaning ponds, Lake Borrie, creeks, saltmarsh, and coast are home to many birds. These include birds that live there all year and those that migrate from far away. It's also one of the few places where the critically endangered orange-bellied parrot spends the winter. If you want to go birdwatching there, you need a permit from Melbourne Water. The site is part of the Werribee and Avalon Important Bird Area. This area is important for waterbirds and the orange-bellied parrots.
