The NCA is undertaking a major strengthening project at Scrivener Dam. The project will involve strengthening work on the downstream structure of the dam – the Dissipator.
On 20 September 1963, fifty years after the founding of the National Capital, Minister for the Interior Gordon Freeth, closed the valves on the newly completed Scrivener Dam (the Dam) thus allowing the waters of the Molonglo River to form Lake Burley Griffin (the Lake) - one of Canberra’s main recreational and tourist attractions.
Image: Completion of Scrivener Dam in 1963. (Credit: nla.obj-143774761)
The Dam is named after Charles Robert Scrivener (1855-1923) who recommended the site for the national capital in 1909.
Learn more about the Dam on the Scrivener Dam Attractions page.
Scrivener Dam is a concrete gravity dam. The design and mass of the dam retains the water which forms Lake Burley Griffin. The Dam is equipped with five flood gates and three sluice gates, all of which are used to control the water level in Lake Burley Griffin.
The spillway located immediately downstream of the dam includes a dissipator structure. The dissipator is a concrete structure comprising of a horizontal concrete slab, concrete chute blocks and vertical concrete baffle blocks. The dissipator absorbs the energy of the water flowing over the flood gates and prevents potentially damaging erosion in the river channel downstream of the dam.
The dam plays a critical role in controlling the flow of water and managing the risk of floods by controlling water levels at a consistent level, that in turn protects the residents of Canberra from flooding and downstream areas from sudden fluctuations in water flows. These work s will be the most significant strengthening works completed on the dam since it was first built in 1963.
Recent studies commissioned by NCA have identified the need to strengthen the Scrivener Dam Dissipator. NCA worked with the University of New South Wales Water Research Laboratory (UNSW WRL), and the Dam Safety Engineers (SMEC) to design, construct and test a scale model of Scrivener Dam. The model and other investigative methods were used to ascertain how the dam and its environs function under a range of operational scenarios.
The modelling and subsequent assessments identified structural risk with the dissipator under flood conditions. There is the potential for the dissipator to be significantly damaged during a major flood event, which in turn, could lead to the failure and subsequent collapse of Scrivener Dam. The project will involve:
The strengthening work will ensure the ongoing safety of the dam during flood events.
NCA are working with a detailed design consultant to complete the detailed design for the project. The detailed design is expected to be complete by October 2023
During the detailed design, the NCA has undertaken several supporting investigations and studies. These include:
Public Works Committee approval and other approvals
NCA has recent provided a submission for the project to the Joint Standing Committee on Public Works. It is anticipated that the NCA will attend a hearing for the project in October 2023.
Pending PWC approval, the NCA will also seek the relevant Works Approvals and Environmental Approvals for the project prior to construction activities.