Nanda Nandakumar, Janice Green, Rory Nathan, Kristen Sih& Robert Wilson
A detailed assessment of hydrologic risk was undertaken for Hume Dam. Data available and relevant to the hydrologic risk assessment were collated and assessed. The catchment was divided into 35 different sub-catchments, each with its own set of parameters that characterised the local hydrologic response. Recorded streamflow was used to calibrate the flood response of selected gauged sub-catchments, and a combination of historic and synthetically-derived data was used to validate the model and loss parameters. The 35 models were combined into a single catchment-wide model. A Monte Carlo approach was adopted for the validation of the models and the derivation of Hume Dam inflow and outflow frequency curves. A range of PMFs which satisfy ANCOLD’s definition of the PMF were also estimated. The PMPDF outflow was estimated to be 7,600 m3/s which can be passed by the dam. Depending upon the assumptions made, the peak PMF outflow was estimated to be in the range from 10,300 m3/s to 14,900 m3/s
2011 – Assessment of Hydrologic Risk for Hume Dam
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Alex Gower, Graeme Mannand Peter Hulcup
The Water Corporation is the principal dam owner in Western Australian with a portfolio of 70 dams. Many of these dams are more than 30 years old and were designed and constructed prior to the writing of most occupational health and safety legislation and associated regulations and standards. Achieving compliance with these regulations and standards on the older assets has led to increasingly complex procedures and increased costs to undertake what were previously routine inspection, operation and maintenance tasks. In some cases achieving compliance has become impractical and modification to the assets is required.
This paper discusses a range of different safety issues, hazards and challenges faced at dams in Western Australia. These include prevention of falls from height, rescue of injured personnel within intake towers and drainage galleries and public access on the dams. Solutions adopted to improve safety and security for operators and the public are presented.
2011 – Safer Access at Water Corporation Dams
Mark R. Sinclair & Richard J. Rodd
Over the last six years there have been ongoing significant developments in the design, fabrication and particularly of the corrosion protection details for high capacity ( >13,500kN MBL ) re-stressable ground anchors used to improve stability of gravity dams. These Australian based developments and the resultant specifications and details have now become the de-facto standards adopted.
The ANCOLD Register dams to have had this generation of cables installed have included; Ross River Dam, Lake Manchester Dam, Catagunya Dam, Tinaroo Falls Dam and Wellington Dam. These projects include the highest capacity permanent ground anchors installed to date worldwide. Some smaller capacity anchors installed into dams have also benefited from this technology.
The Recent Developments and Application of Large Ground Anchors for
The application of maintenance to mechanical assets is a mature and well understood discipline. Although techniques and methods differ from industry to industry, the experiences and knowledge of practitioners should be transferable, but are they?
A challenge faced by all engineers is finding the appropriate balance between obtaining detailed physical evidence of asset condition through invasive disassembly and inspection against assessing condition based on monitoring and past performance.
This paper describes the experiences of the author in applying mechanical maintenance skills in the dams environment and shares some important lessons learned along the way.
2011 – If it ain’t broke don’t fix it – or should you? Lessons learned from relying on past performance of mechanical assets.
Kirsty Carroll, Kelly Maslin, Richard Rodd
Melbourne Water manages over 210 retarding basins across Greater Melbourne ranging in size from 4ML to 4700 ML with embankment heights from 0.3m to 10m. Over the years the basins have been designed and constructed by a range of different owners and authorities. Varying design and construction standards with the majority of retarding basins generally being located in highly urbanised areas, has resulted in Melbourne Water having a large portfolio of assets that have potential to pose a significant risk to the downstream communities they are designed to protect.
High level hazard category assessments completed over the last10 years identified that approximately 90 structures were either High or Extreme hazard categories based on the ANCOLD Guidelines on Assessment of the Consequences of Dam Failure.
In an attempt to identify retarding basins requiring priority consideration for remedial works Melbourne Water embarked on a process of completing a dam safety risk assessment for five of the retarding basins in accordance with the ANCOLD Guidelines on Risk Assessment. The objective of the risk assessment was to develop an understanding of the key risk issues that might affect retarding basins as distinct from water supply storages, identify potential remedial works and develop a prioritised risk management strategy for the five basins considered. In completing the risk assessment there was also significant discussion about ways to streamline the process to allow assessment of the remaining basins.
This paper details the results obtained from the risk assessment, investigates the application of the base safety condition and implementation of a risk management strategy. It also looks at similarities between sites to enable common upgrades to be implemented across the range of retarding basins. This paper also discusses the need for guidelines specific to retarding basins to be developed.
How do you solve a problem like retarding basins? An asset owner’s perspective
Michael Somerford and Steven Fox
The Water Corporation of Western Australia has been implementing the risk assessment process promulgated by ANCOLD for 12 years. This approach has been central to a $310 million dam safety remedial works program that has reduced life safety risk across the Water Corporation’s portfolio of dams by an order of magnitude. However, whilst this process has provided a rational basis to prioritise dam safety upgrades, there are still questions that have not been fully answered and further development of the application of risk assessment to dams is desirable.
This paper revisits some of the key concerns that remain evident with the process and argues that unless further guidance is provided it may be that dam safety upgrades have effectively “hit the wall”; and upgrade programs commenced may never be completed as envisaged by ANCOLD.
2011 – Western Australian Dam Safety Challenges for ANCOLD Part 2