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.
Tony Qiu and Brian A. Forbes
The RCC design review and construction supervision of the 60m high Tannur Dam in Jordan was carried out by GHD, Australia.
The 220,000m3 of RCC was placed during February-December 2000; change to the sloped layer method was made once the dam reached 15m height. It produced a 50% increase in placing rate and a considerable saving in costs.
The use of the method is the first known use outside of China, where it was developed during the construction of the 130m high Jiangya Dam in 1997-8. The sloping of the 300mm thick layers of RCC across the dam from bank to bank at grades between 5-8% ensures subsequent layers of RCC can be placed within the initial set time of the lower layer and hence the RCC is monolithic across the lift joint.
This paper briefly describes the project in Jordan and then gives specific details of the use of the sloped layer method. Typical results from the quality control testing during placement and subsequent coring and testing of the lift joints are also provided. The benefits of its use in adverse climatic conditions, such as extreme heat or rainfall and the ways it can be integrated with forming the upstream-downstream slope are also discussed.
The sloped layer method is a significant advancement, particularly for large structures, where lift joint cohesion, tensile resistance and RCC placing rates are vitally important.
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.
Steven Fox and Mark Tansley
Yarrawonga Weir was constructed in the 1930’s and is located on the Victoria / New South Wales border, between the towns of Yarrawonga and Mulwala. Dam safety investigations revealed that the main embankment was founded on a very loose layer of sand that would be vulnerable to liquefaction even under the operating basis earthquake.
This paper details the statutory approvals and community consultation processes that were employed and the benefits that they provided to the $13 million remedial works project.
Local communities can assist, be neutral or obstruct a project. By engaging the community in a positive manner it is possible to deliver excellent results without increasing costs.
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.
Gregg Barker B.E. (Hons.) GradIEAust
Dam safety emergency plans (DSEPs) are typically produced for individual dams. For owners of a large portfolio of dams, this approach creates document control difficulties, requires excessive time and effort and can lead to confusion when a single emergency affects multiple dams having individual DSEPs. Hydro Tasmania has developed a single DSEP which is applicable to its portfolio of 54 referable dams. The DSEP contains generic emergency response procedures, is applicable to a whole range of generic dam safety incidents, uses a simple colour-coded flowchart-action list format, has a two-stage emergency response, retains all necessary dam-specific information and can be easily adapted to any organisational structure. This approach was found to have benefits in document control, flexibility in the management of the emergency response and short lead time in terms of having DSEPs which cover an entire portfolio of dams.