Pressure Tunnel and Shafts facts for kids
Quick facts for kids Pressure Tunnel and Shafts |
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| Location | Potts Hill, City of Canterbury-Bankstown, New South Wales, Australia |
| Built | 1921–1935 |
| Architect | Water Board |
| Owner | Sydney Water |
| Official name: Pressure Tunnel and Shafts | |
| Type | state heritage (built) |
| Designated | 15 November 2002 |
| Reference no. | 1630 |
| Type | Water Tunnel |
| Category | Utilities - Water |
| Builders | Water Board |
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The Pressure Tunnel and Shafts is a special water supply system located at Potts Hill, in New South Wales, Australia. It was designed by the Water Board and built between 1921 and 1935. This tunnel is super important because it's the third largest pressure tunnel in the whole world! Sydney Water, a government group, owns and looks after this amazing piece of engineering. It was added to the New South Wales State Heritage Register on 15 November 2002, meaning it's a protected historical site.
Contents
History of the Pressure Tunnel
Early Days of Bankstown
The area where the tunnel is located, near Bankstown, was chosen for settlement by Governor Hunter. He named it Banks Town to honor a famous plant expert, Sir Joseph Banks. In 1795, explorers George Bass and Matthew Flinders explored the Georges River. They sailed along what would later become the southern edge of the town.
They shared what they found and were given land grants in the Georges Hall area. George Bass got the first grant in 1798. Matthew Flinders also received land and bought more, owning 300 acres. Other early settlers included Lieutenant John Shortland and Surveyor James Meehan. By 1799, about 1200 acres along the river had been given to former soldiers and convicts.
The area grew slowly at first because it was far from both Sydney and Parramatta. But after Liverpool Road was built in 1814, things started to develop much faster. Settlements began to pop up along the new road. In 1831, Michael Ryan was given 100 acres in Bankstown, which included the tunnel's site. For many years, this area was known as Ryan's Paddock.
Building the Water Supply Tunnel
In 1914, people started looking into building a large pressure tunnel. This tunnel was needed to help move more water through the main pipes between Potts Hill and Crown Street. The plan was for the tunnel to go from the Potts Hill Reservoir all the way to the Waterloo pumping station, which is about 16 kilometers away.
To make sure the tunnel could be cleaned and fixed, it was designed with two round tubes, each 1.8 meters wide. The plan for the tunnel was officially approved in 1919.
Work began with trial drilling in 1921 and 1922. The first tests were done on a 4-kilometer section. However, the tunnel's inner lining broke in many places. More cracks appeared during tests on another section. Even with these problems, a part of the tunnel was put into use in 1929 because water was urgently needed.
In 1930, the Water Board decided to line the entire tunnel with steel tubes. These tubes were 8 feet 3 inches (about 2.5 meters) wide inside. The space between the steel tube and the tunnel wall was filled with concrete. Due to a lack of money, the lining work stopped until 1933 when more funds became available.
In 1933, the government ordered a special investigation into why the tunnel's lining had failed. Even though the lining work was already happening, the investigation helped figure out what went wrong. The report from this investigation shared a lot of information about pressure tunnels and their problems around the world. This led to many skilled engineers joining the Water Board.
The tunnel's lining was finally finished by 1935. The inside of the pipes was coated with bitumen during manufacturing. In 1961, this tunnel was still the third largest in the world! The bitumen lining was later replaced with cement lining between 1961 and 1963, once a nearby tunnel called the City Tunnel was completed.
What the Pressure Tunnel Looks Like
The Pressure Tunnel starts at Potts Hill and goes under many suburbs. These include Chullora, Bankstown, Enfield, Canterbury, Ashfield, Petersham, Marrickville, Erskineville, and Waterloo. It runs deep underground, from 15 meters to 67 meters below the surface. The tunnel is about 16 kilometers long in total.
The pipes inside the tunnel are lined with a special sand-cement mix. The space between these liners and the tunnel walls is filled with concrete. This concrete helps support the liner against the water pressure and protects it from rust. If more water is needed, special pumps at Potts Hill can increase the tunnel's delivery power.
There are seventeen shafts built along the Pressure Tunnel. These shafts are like vertical tunnels that connect the main tunnel to the surface. Shaft 1 is near the Potts Hill Pumping Station. Shaft 17 is located at Waterloo. Some shafts, like 2, 3, 7, 8, 13, and 16, have been filled in. Shaft 5 and Shaft 11 are "dewatering shafts." This means they can release water from the tunnel, with Shaft 5 discharging into the Cooks River and Shaft 11 into Hawthorne Canal.
Other shafts are located in different areas, like Shaft 4 on Roberts Road, Shaft 12 on Chester St, and Shaft 14 on Station St. Shaft 6 and Shaft 9 are special because the tunnel changes levels at these points. Buildings were built at each shaft to allow access to the tunnel and its parts.
These shaft buildings are made of metal. There are eleven of these buildings in total, from Potts Hill to the Central Workshops. Other buildings are found along the railway line at Newtown, in Lewisham, Ashfield, and Strathfield South. The inside of the tunnels is mostly the same as when they were built. However, the shafts have been changed quite a bit over time.
Why the Pressure Tunnel is Important
The Pressure Tunnel is very important for history and engineering. It shows how engineers successfully solved the problem of getting more water from the Potts Hill Reservoir to the Waterloo Pumping Station. This was a super important link in Sydney's water supply system. It's also the third largest pressure tunnel in the world, which was a huge achievement for the government and the Water Board during the years between the two World Wars.
The Pressure Tunnel and Shafts were added to the New South Wales State Heritage Register on 15 November 2002 because it meets several important requirements:
- It shows how cultural or natural history developed in New South Wales.
The Pressure Tunnel is a key part of Sydney's water system. It has been doing the same job since it was built, showing a continuous part of history.
- It shows great creative or technical achievement in New South Wales.
The tunnel is underground, so you can only see it from the inside when it's empty of water. Its design and construction were a big engineering challenge.
- It has a strong connection with a community or group in New South Wales.
The Pressure Tunnel and shafts are important to society because they provided huge amounts of water to Sydney's growing population. It helped people get water during dry periods, so many people likely value it highly for its vital role.
- It can provide information that helps us understand the history of New South Wales.
Building the tunnel was tough. Two tunneling machines from England couldn't dig through the hard sandstone rock, so workers had to dig by hand. The cracks that appeared under full water pressure helped engineers learn more about the ground and its properties. This information was very valuable.
- It is rare or unusual in New South Wales.
This tunnel is rare in New South Wales. It is the third largest pressure tunnel in the world, making it a very special and uncommon structure.
- It shows the main features of similar historical places or environments in New South Wales.
It's a great example of how engineers successfully solved the problem of increasing water flow from Potts Hill to Waterloo. It represents how a reliable water supply was provided during the period between the World Wars.
