R. Herweynen, T. Griggs, E. Schrader and D, Starr
The Burnett Dam is a 50m high Roller Compacted Concrete Dam on the Burnett River, located approximately 50km inland from the town of Childers in Queensland. The design and construction of the Burnett Dam is being undertaken by the Burnett Dam Alliance (BDA) consisting of Walter, Macmahon, Hydro Tasmania, SMEC and Burnett Water. The design of the dam commenced in 2003, construction started in November 2003 and the planned completion date is mid 2005.
The Alliance Contract was awarded through a competitive process and therefore innovation was a key aspect of the design and construction methodologies. This paper will look at a number of specific aspects of the design where innovation delivered true value, namely:
The Burnett Dam design has clearly demonstrated that the unique site conditions have had a significant impact on the final design and construction methods.
Simon A. Treadwell, Michael Shirley, Rory Nathan, Kylie Swingler
The Murray Darling Basin Commission through its native fish strategy has embarked on a comprehensive program for improving fish health in the basin. The strategy is aimed at managing and mitigating a range of threats including loss of habitat, altered flow regimes and thermal pollution downstream of large dams.
To help identify the relative benefits of different management options SKM developed a numerical ecological model. The model produces an index score that provides a measure of condition for native fish under various habitat, flow and temperature scenarios. The model uses a series of preference curves that define habitat requirements, critical spawning periods, spawning temperature thresholds and upper and lower temperature limits for egg, larval and adult survival. An index score of 1 is applied if conditions are ideal and an index score of 0 is applied if conditions are intolerable. Different temperature time series and habitat extent can be modelled to generate condition scores related to each fish life-history stage. Comparisons between the natural condition and those related to various reservoir release regimes can be made, for example to examine the likely effects of cold water releases or the benefits that could be achieved through the use of multi-level outlets. This can be compared with the relative benefits of restoring habitat or changing flow regime.
The results from a case study examining the relative benefits to native fish from managing flow, temperature and habitat downstream of Dartmouth Dam will be presented.
Dam safety planning is a team game. There are many players involved and there is a need for information to be shared and actions to be properly coordinated. The State Emergency Service is the legislated combat agency for flooding in New South Wales and is responsible for planning for and conducting the warning and evacuation of communities at risk from floods, including floods affected by dams. The successful execution of these responsibilities is dependent upon the continuing development of a strong, cooperative relationship between the dam owners and managers, dam regulators and emergency managers and the effective incorporation of community expectations in dam safety planning.
This paper explores some of the ways that this relationship can help to meet well accepted community expectations in respect of risk to life and property and outlines progress made in dam safety planning to date. The emergency response aspect of dam failure planning is still a relatively immature field in Australia, and it follows that there are lessons to be learned as we proceed. In that context, the paper also describes some of the difficulties the State Emergency Service has encountered in its role as the response planning agency and suggests some guiding principles to enhance future interactions between the key stakeholders.
The decision-making landscape has shifted markedly over the last 10 years with the implementation of COAG micro-economic reforms. These reforms have seen the separation of regulatory functions from commercial / service provision functions – yielding benefits to all stakeholders. However, the fragmented regulatory framework for dam owners (in Queensland at least) has resulted in potential conflict between price regulation and major dam safety decisions such as spillway upgrades.
This paper examines the scope for conflict in the two regulatory frameworks (pricing and dam safety) and the implications for dam owners, water users and potential new investors in the water infrastructure.
SEQWater is the major supplier of bulk water to Local Governments and industry in South East Queensland. SEQWater owns 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 dam SEQWater formed an alliance with Leighton, Coffey, MWH and the NSW Department of Commerce Dam & Civil Section.
A preferred upgrade option for Wivenhoe Dam has been selected, designed and construction started by the Wivenhoe Alliance. This paper presents details of the selected upgrade option.
P J Cummins, G S N Adikari, C Hill and A K Parkin
Yan Yean Dam has been a key component of water supply to the City of Melbourne since its completion in 1857. Of typical puddle core construction over deep alluvium, it has performed well over the years since, with the exception of the discovery of a piping tunnel in 1949, duly repaired with minimal risk. However, in the absence of an engineered filter, some potential for recurrence has remained, and this, coupled with a continuing outward creep of the downstream batter and the need to ensure compliance with current design practice, has driven the recent remedial program.
The original embankment was 9.6m high and almost a kilometer long, with 3:1 and 2:1 batters and a wide core, now modified by the placement of a 3-component full-height chimney filter and stabilising fill. Critical issues in the design of these remedial works are described herein, including foundation preparation, the evolution of the design slope, the cellular filter and its specification, and measures required for the preservation of historic structures. Because of the potential impact on public parkland and nearby housing, community consultation was a vital input that enabled good relationships to be maintained throughout the project.