Burrinjuck Dam
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Burrinjuck Dam is a 92 metres (300') high, concrete gravity dam on the Murrumbidgee River near Yass, New South Wales, Australia.
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[edit] Construction commences
The dam is the headwater storage for the Murrumbidgee Irrigation Area (M.I.A.). The dam has a long history, construction having commenced in 1907. Due to World War I, the dam was not completed until 1928. A major flood in May, 1925 far exceeded all previously recorded floods and resulted in the dam wall being overtopped to a depth of 1m (3' 3").
[edit] Enlargement
A strengthening and enlargement works program was undertaken between 1938 and 1957 (this time delayed by World War II) which raised the dam to a height of 80m (260') and provided a maximum spillway discharge capacity about twice the peak discharge of the 1925 flood.
A major flood in 1974 eroded unweathered granite from an unlined spillway discharge channel which then resulted in the destruction of a penstock to a downstream hydroelectric power station. The outlet valves of the dam were also destroyed during the same flood. These events prompted a review of the safety of the dam which recommended a new remedial works program.
[edit] Upgrade
This project involved raising the existing dam wall by 12 metres (40') to its present height of 92 metres and installing post-tensioned ground anchor cables to improve the security of the dam during major floods. At the time, the Burrinjuck Dam Flood Security Upgrading project was unprecedented in two respects;
(1) the post-tensioning force required per metre length of dam crest and,
(2) the intensity of the flood discharge over the unlined sections of the side channel spillways during the Probable Maximum Flood (PMF).
The upgrading works were completed in 1999 at a cost of $79.5 million (AUD).
