Richard 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.
Investigations of damaging blowback incidents at the headrace tunnel intake to Rangipo Power Station in the Central North Island of New Zealand are described. The blowback phenomenon is explained theoretically based on evaluation of the evidence available from the incidents and information obtained from the literature. A physical hydraulic model study is described in which this explanation of the blowback phenomenon was verified. The model was also used to devise a solution for the blowback problem.
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.
This paper provides an insight into the management of reservoirs under drought conditions within the new water management frameworks established under the Council of Australian Governments (COAG) Water Reforms. Traditional approaches to the sharing of available supplies during drought are no longer appropriate as the roles of the resource regulator, infrastructure operator, and Government have been separated in the interests of providing certainty for water users and the environment. Recent experiences during drought in the Upper Mary River system near Gympie in Queensland has demonstrated the need to ensure the robustness of water sharing rules for reservoirs under the new framework if certainty is to be delivered.
A. Swindon, T. Griggs, R. Herweyne and R. Fell
Cairn Curran Dam is a 44m high zoned earthfill embankment located near Bendigo in central
Victoria. The dam is owned and operated by Goulburn-Murray Water.
A risk assessment had identified that the junction between the embankment and spillway wall was a
weakness in regard to the potential for piping. Initial geotechnical investigations indicated a softened
zone adjacent to the foundation.
The conceptual upgrade design was to excavate the downstream slope and place filter material and a rockfill weighting berm. A 2-D slope stability analysis gave unacceptably low factors of safety for this excavation. The three dimensional nature of the embankment/spillway interface and excavation
geometry was identified as an important factor in the upgrade design.
A detailed geotechnical assessment was undertaken and a geotechnical model developed that
accounted for potential softened zones adjacent to the spillway wall, along the foundation, and within
A 3-D limit equilibrium slope stability program was utilised to analyse the 3-D factors of safety. The
program employed an extension of Bishop’s method of slices to a 3-D ‘method of columns’. A 3-D
finite element analysis was also undertaken to estimate likely deformations of the embankment and cut slope during construction.
The development of the geotechnical model and subsequent analysis allowed the upgrade works to be undertaken with confidence.
David Snape and Brian Simmons
Sydney Catchment Authority (SCA) has been progressively enhancing its asset management capability for dams and other headworks infrastructure since 1999. A key to the development of the integrated asset management system has been the application of asset condition assessment and Failure Modes, Effects and Criticality Analysis (FMECA) across the water supply mechanical and electrical assets. This has provided vital data necessary to:
Asset management features as a key result area within the SCA’s Corporate Business Plan. Integrated asset management is achieved by cascading corporate outcomes, strategies, objectives and responsibilities down through divisional and team work plans to individual staff members. This paper covers a range of issues that have a bearing on the day-to-day integrity of the infrastructure required to deliver bulk raw water to the SCA’s customers.
The management of maintenance at Warragamba Dam is used as an example to demonstrate the effectiveness and practicality of the application of the contemporary asset management system.