Melbourne Water (MW) has historically seen dam safety management as a civil discipline and has focussed on understanding and managing the civil assets at its dam sites. The recent addition of a mechanical engineering resource to the team responsible for the dam safety management has refocused attention on the mechanical and electrical (M&E) assets and provided a more holistic asset management approach to MWs large dams.
This paper discusses the process MW has developed over the past two years to improve their understanding and management of M&E assets. It centres on key process points for how MW has prioritised the development of M&E asset management programs on the basis of an autogenous ‘asset criticality’ rating system and has utilised ANCOLD comprehensive inspections to plan and implement new inspections and tests on dam M&E assets. The two case studies of Sugarloaf and Upper Yarra Reservoirs’ outlet works demonstrate the the benefits of the process to gain operational and technical knowledge of M&E assets, strategic importance to the water supply network, identifying risks therein and reallocate significant funding to address these risks as prioritised by asset criticality.
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Ulu Jelai project is a recently completed 372MW hydroelectric peak – power project located in the Cameron Highlands of Malaysia. A combination of power generating and reservoir operating conditions together with the site topography, existing road infrastructure, geology and hydrogeological conditions pose a significant risk to the viability of the project during operation. As a result, significant reservoir rim stability treatments were designed and constructed along a 3.5km section of the right abutment of t he Susu Reservoir to reduce the risk of instability to acceptable levels. This paper describes the methods of investigations, stability assessment and design aspects of the reservoir rim stability treatments that were constructed.
HEC-LifeSim modelling has been emerging in the industry over the last few years and is increasingly becoming the preferred method for detailed consequence and failure impact assessments. The increased adoption rate of HEC-LifeSim modelling is a result of advancements to computation power and hydraulic modelling techniques and allows dam owners to obtain more robust and consistent estimates of the potential loss of life (PLL) compared to the traditional Graham (1999) and RCEM (USBR, 2014) approaches.
This paper will demonstrate, through the use of three examples, how the inputs and outputs from HEC- LifeSim have been used to identify potential ways to better understand the consequences as a result of dambreak.
Junction and Clover Dams are central spillway slab-and-buttress dams located in Victoria. Previous safety reviews and assessments of the dams concluded that neither dam met modern dam design standards and remedial works were recommended, including infilling the slab-and-buttress dams with mass concrete to sustain seismic loadings. These conclusions were based largely on the assessed seismic hazard at the site, the results of response spectrum analyses and observed conditions of the dams including alkali-aggregate reaction of the concrete. AECOM used current seismic hazard assessment techniques, conducted concrete investigations and testing, assessed long term surveillance monitoring results and used modern finite element techniques to demonstrate that no upgrade works were required at either dam resulting in a significant saving for AGL.
In 2015, a study was undertaken where recommendations were made to provide protection to the exposed rock in the unlined channel of the spillway at Burdekin Falls Dam. The protection included a matrix of anchor bars which extended the full 504 m width of the spillway and 25 m in the downstream direction. Over 1,200 anchors were proposed comprising 36 mm diameter bar extending up to 15 m into the foundation.
A value engineering study was undertaken in 2017 where a review of the rock scour potential was undertaken. The study was based on a methodology developed by Pells (2016) as part of a research grant funded under an Australian Research Council (ARC) Linkage Project which was jointly financed by the Federal Government of Australia, various state government bodies and engineering consultancies involved in dam design, operations and management.
This paper describes the approach taken as part of the value engineering study, the methods used in the assessment and the benefits of both innovative thinking and challenging the more traditional approach of rock scour assessment, the outcome of which resulted in a $11 m plus saving to the owner of the asset.
Yarrawonga and Torrumbarry Weirs; located on the Murray River bordering Victoria and New South
Wales, are operated by Goulburn Murray Water on behalf of the Murray Darling Basin Authority.
The electrical and control systems that operate both structures were nearing 20 years of age, resulting in risk associated with equipment nearing the end of its useful working life and hardware obsolescence, driving this upgrade program. These control systems are critical in the monitoring and management of river levels and flows that extensively affect Victorian and New South Wales irrigation supplies and recreational users on the Murray River and Lake Mulwala.
Considerable effort was required to update and develop the control philosophy before proceeding to the design phase of the projects. The requirement to work on these brownfield sites, while maintaining operational ability and minimising dam safety and water delivery risks, resulted in a significant implementation and commissioning process. During the course of these works, the opportunity was also taken to enhance and update remote monitoring capability.
The lessons learnt on these projects are being incorporated into current Electrical and Control System Upgrade projects at Cairn Curran Reservoir and Dartmouth Dam.