M. Barker, T. Burt, K. McCallum-Gaul, Dr M. Barry
The disused Stapylton quarry is located in the suburbs of the Queensland Gold Coast. Gold Coast City Council, as part of the Northern Wastewater Strategy, has included the use of the quarry for storage and re-distribution of reclaimed water from the Beenleigh Water Reclamation Facility (WRF) to the downstream cane farmlands. A comprehensive EIS has been produced, which has strict water quality requirements for the quarry environs as well as the reservoir and outflow. This paper presents the background to the Northern Wastewater Strategy, the requirements for the Stapylton reservoir and the analysis performed for the detailed design of the embankment dam and the inlet bubble plume destratification system. The modelling of the destratification system was undertaken using the programme DYnamic REservoir Simulation Model (DYRESM) coupled with Computational Aquatic Ecosystems DYnamics Model (CAEDYM). The outcomes and implications of the modelling for the design and system operation including environmental monitoring are discussed.
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Hydro Tasmania uses an electronic inclinometer to monitor the face deflections of nine of its CFRDs. The inclinometer is lowered down a steel pipe attached to the upstream face of each dam. The inclinometer was designed and constructed by the University of Tasmania and was first used on Cethana Dam when it was completed in 1972.
The success of its use on Cethana Dam lead to its use for the long term monitoring of eight subsequent CFRDs constructed by Hydro Tasmania.
After 25 years of successful operation some irregular readings of face deflection became apparent. This paper describes the investigation of the irregular readings that had been obtained, the assessment of other methods of observing concrete face deflection, and the refurbishment of the inclinometer using modern electronic components.
To allow greater flexibility in their generation and hence a better response to the peaks in electricity demand, Southern Hydro decided to increase the Full Supply Level of Dartmouth Regulatory Dam by 3.5m using labyrinth Fusegates.
The Regulating Dam is located on the Mitta Mitta River, approximately 8 km downstream of Dartmouth Dam. It is a 23 m high concrete gravity structure with a 60 m long central spillway section. The dam forms the storage required for regulating releases from the Dartmouth Power Station back to the Mitta Mitta River, so as to satisfy environmental requirements.
Although this is the second Fusegate project in Australia it is unique in that difficult access conditions determined that construction in mild steel would be the most appropriate. Initial civil works involved construction of a flat sill to replace the Ogee spillway crest so that it could support the Fusegates. The installation contractor devised an ingenious method for installing the huge structures over the top of the gate-house which blocks direct access to the spillway. Design was very much undertaken with the installation method in mind to ensure a high quality project with minimum contractual risk.
This paper discusses the construction stage of this very interesting spillway modification.
K. Chandler, D. Gill, B. Maher, S. Macnish and G. Roads
SEQWater is the major supplier of untreated water in bulk to Local Governments and industry in the South East Queensland region of Australia, through ownership of Wivenhoe, Somerset and North Pine Dams. Wivenhoe Dam (Lake Wivenhoe) is located on the Brisbane River in Esk Shire. The storage provides both flood mitigation and water supply storage to Brisbane and Ipswich. The water supply storage capacity at full supply level is 1,160 GL. An additional 1,450 GL of storage above full supply level is used for flood mitigation.
Changes to the estimation of extreme rainfall events has resulted in significant increases in the estimates of the PMF since the original design of Wivenhoe Dam. To upgrade the flood security of Wivenhoe Dam, SEQWater has formed an alliance with Leighton Contractors, Coffey Geosciences, MWH and the NSW Department of Commerce.
This paper details the alliance delivery method, the latest estimates of the PMF based on the GTSMR method and details of the two preferred options being finalised by the Alliance.
State Water # as manager of Keepit Dam has established a comprehensive upgrade project.
A portfolio risk assessment by State Water of its major dams placed Keepit Dam as the highest priority for an upgrade.
While extreme flood and earthquake dam safety are the main drivesr for this upgrade, the opportunity has been taken to integrate other key dam management considerations into the process including environmental improvements, flood mitigation and sustainable regional development.
The dam, which is located on the Namoi River some 45km upstream of Gunnedah, is, in tandem with Split Rock Dam upstream, a vital irrigation water supply for the Namoi Valley region in northern New South Wales.
In considering the most appropriate way of addressing the critical flood safety issue, it became very apparent that the solutions were many and they significantly impacted on the local community. Other important issues such as water quality and flood mitigation, and overall sustainable development in the valley, particularly system water reliability, could influence dam safety solutions and so also needed to be considered as part of the process. As such it was considered imperative that the local community be actively involved in determining both interim and long-term upgrade solutions.
To achieve the best outcome for the region, State Water since mid 2001, has used the community consultation approach to guide the project.
Currently interim works have been completed and long-term options are being evaluated.
An Environmental Impact Statement on the preferred proposal will be undertaken during the later part of 2004 and if approved, all works will be completed by end of 2007.
This paper will highlight our experiences to date including:
• the proposition of an integrated consultative process;
• the background to the project;
• the need for and extent of upgrade;
• an integrated consultation and communication approach including innovative processes and the creation of a high profile Community Reference Panel (CRP) to guide the upgrade project;
• some dos and don’ts from a consultation perspective, for use in other upgrade projects; and
• where to from now.
Cold water pollution occurs downstream of many Australian dams when water is released from well below the surface layer of a stratified reservoir during spring and summer. Water temperature can be depressed by 8 °C or more and this may impact negatively upon the survival and growth of native Australian fishes.
After many years in the ‘too hard basket’, mitigation of cold water pollution below dams is receiving increasing attention in Australia. Hume Dam is a case in point. Hume Reservoir, one of the largest irrigation reservoirs in Australia, has a high throughput of water (short residence time) and receives unseasonably cold water from Dartmouth Dam on the Mitta Mitta River and the Snowy Mountains Hydro Scheme on the Murray River.
The maximum possible discharge temperature below Hume Dam may be constrained by geomorphic and climatic features beyond human control. Specifically, the relatively short residence time of water may limit the extent to which it can heat up in the reservoir prior to discharge downstream. Here I present a heat budget for Lake Hume and address the question, “How much can we improve the thermal regime below Hume Dam.”