2003 – Coping with Probable Maximum Flood – An Alliance Project Delivery for Wivenhoe Dam
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.
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Papers 2003
2003 – Dykes to Access Canadian Diamonds – The Diavik Experience
Learn moreRichard Olive John Wonnacott, Stefan Schwank
The Diavik Dyke was constructed in 2001/2 in a major sub-Arctic lake in Canada’s Northwest Territories, to permit an open-pit diamond mining operation. The dyke, 3.9km long, was built in water up to 20 metres deep in a period of 17 months. For ten months of this period the lake was frozen. The project was notable for the extreme climate, discontinuous permafrost in the dyke foundations, very difficult logistics and the exceptional environmental constraints.
Project economics dictated a short construction period to permit the early generation of revenue from the mine. To confidently deliver a secure dyke within the time frame, the world’s most technologically advanced cut-off wall equipment was designed and fabricated in Germany.
This paper provides an overview of the dyke and focuses in more detail on the specialty equipment used for the cut-off wall and foundation treatment.
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Papers 2003
2003 – Can Cold Water Pollution Be Mitigated Below Hume Dam?
Learn moreB.S. Sherman
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.”
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Papers 2003
2003 – Remedial Works Design At Churchman Brook in Western Australia
Learn moreN. Vitharana, A. Gower, G. Bell and N. Petrovic
Churchman Brook Dam is a 26m high earthfill dam with a puddle clay core and impounds a reservoir of 2.2GL. Various remedial works have been undertaken since completion of construction in 1928. In September 2000, a sinkhole in the right abutment was observed during a routine dam inspection. Following this incident, detailed site investigations were carried out. These investigations revealed that there are soft zones and possibly voids formed in the upper part of the clay core.
A comprehensive dam safety study and a risk workshop undertaken in 2002/2003 showed the dam to be deficient in aspects associated with piping, spillway adequacy and outlet works condition. A rational geotechnical model was developed for the foundation utilising triaxial test data from 1980s and recent investigations. The existing spillway chute will be upgraded with a concrete liner attached to the existing chute incorporating no-fine concrete as a free-draining medium. This paper presents the various aspects of the remedial works currently being designed.
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Papers 2003
2003 – Bellfield Flood Security Upgrade – How We Did it Our Way With Minimal Resources
Learn moreJL Tottenham
Bellfield dam is a 78,500 ML drought reserve storage for the Wimmera-Mallee Stock and Domestic System. The 800m long by 57m high zoned earth and rockfill dam is located on Fyans Creek upstream of the Grampians tourist town of Halls Gap in north western Victoria. The dam was built in the period 1963-67. Later in 2002-03 as part of a flood security upgrading (FSU) program, had its rock chute spillway deepened by 3.4m and its embankment crest raised by 1.9m to withstand a PMF.
To manage the FSU’s likely construction constraints and risks, Wimmera Mallee Water’s Headworks Group successfully undertook the upgrading by a mix of schedule of rates contracts and direct management.This paper complements a companion paper by WMW’s design consultants, URS and describes why and how direct management was used, plus unconventional aspects of spillway deepening and the raising of a narrow dam crest with earthworks and a pre-cast parapet wall.
Keywords: Drill and blast, pre-cast parapet wall, narrow embankment crest, direct management, construction.
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Papers 2003
2003 – Keepit Dam Upgrade – The Community Consultation Way
Learn moreSuzie Gaynor, Jocelyn Potts, David Watson
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.