Warragamba Supply Scheme
Warragamba Supply Scheme
Warragamba was the last and by far the biggest of the concrete dams built during the twentieth century to supply Sydney's ever-growing water needs. When completed in 1960, it was the world's tallest and largest domestic water supply dam built on stone foundations.
It was also the end of an era. In the future, rock fill would become the preferred building method, allowing dam walls to reach greater heights and hold back more water.
Looking back, we can now see that Warragamba was the pinnacle in engineering achievement for this type of mass concrete dam building.
Today, it stands as monument to the workers who designed and built it on such a massive scale, without the aid of computers or modern construction techniques.
The fact that Warragamba continues to be the centrepiece of Sydney's water supply system 50 years later is the best indication of just how great an engineering achievement it was for its time.
The narrow gorge at the exit to the Burragorang Valley was first suggested as an ideal dam site in the mid-1800s, but a century passed before construction techniques advanced enough for Warragamba Dam to be built.
During this time the capacity of Sydney's water supply system grew with four dams in the Upper Nepean Scheme built between 1908 and 1935 and a fifth dam, at Woronora, in 1941 - but still the water shortages continued.
The Warragamba Emergency Scheme was built between 1937 and 1940, in the middle of a record eight-year drought. A weir on the Warragamba River and a 52 kilometre pipeline to Prospect Reservoir temporarily saved Sydney.
Around this time, the Engineer in Chief of the Metropolitan Water, Sewerage & Drainage Board, Samuel T Farnsworth, proposed developing the full water supply potential of the Warragamba River.
He oversaw preparations, which began in 1942 with drilling rock core samples to find the best site. Final approval for his dam design was given in 1946 and was followed by tree clearing in the Burragorang Valley and the diversion of the Warragamba River around the construction site.
Farnsworth did not live to see his creation completed. He died in 1948. The dam would take 12 years and 1,800 workers to complete.
When it was finished in 1960, Warragamba was the highest concrete gravity dam in the world on stone foundations.
Its construction involved several innovative techniques used for the first time in Australia, such as the use of ice and chilled water to cool and strengthen the concrete using ice from a purpose built ice making plant.
The dam wall is an excellent example of gravity dam construction with inspection galleries, contraction joints, and a drainage system. The amount of concrete used in the dam wall is unique in NSW.
The design of the spillway and crest gates, incorporated in the dam wall rather than alongside, was a notable technological advancement from earlier dams.
The post-war architecture of the crest, lift towers and valve house, together with the engineering of the foundations and wall drainage systems, make it an outstanding example of a high, straight concrete gravity wall.
When completed in 1960, the 137 metre high dam wall created a lake 52 kilometres long, drawing water from a catchment of 9,051 square kilometres, quadrupling the previous total storage capacity of all of Sydney's existing dams.
See Visit Warragamba Dam for more history.
See the Warragamba Supply Scheme listing on the heritage register.