H. Morrison, J. Leckie, P. Richardson, R Paton
Awoonga Dam is a 40 metre high concrete faced rockfill dam on the Boyne River near Gladstone in Central Queensland. The dam supplies domestic and industrial water to the Gladstone region and the Callide Power Station. Stage 1 will increase FSL by 10 metres to EL 40, which increases storage capacity from 289,000 ML to 777,000 ML. To provide for future industrial growth in the region, the dam design facilitates future raising up to a nominated FSL of EL 62, in a number of stages.
The project consists of:
Significant savings were realised by adopting the alliances project delivery method, resulting in completion 5 months ahead of program and more than 10% under budget.
This paper details development of the project under the alliance and outlines some of the lessons learnt.
Brian Walford and Ross Killick
Increasing salinity in Australian river systems is a major issue that is attracting attention from politicians, environmentalists and the wider community. The successful coexistence of mining and agriculture in the Hunter Valley has resulted in the need to tackle river salinity with a cooperative approach to not only contain salinity, but also reduce it. Mining companies have participated in the development of a tradeable emission scheme to manage the discharge of surplus saline water, resulting in the construction of mine water dams that are designed to release a large volume of saline water in 2– 3 days.
D. J. Dole, D. Dreverman and A. J. McLeod
The Murray-Darling Basin Commission is embarking on an ambitious project directed towards repairing the environmental damage to the River Murray, caused by a century of human intervention. Today the River Murray is one of the more highly regulated rivers in the world, with only a 27% natural annual median flow to the sea.
In April 2002 the Murray-Darling Basin Ministerial Council approved, in–principle, a program of structural works from Dartmouth Dam to the Murray Mouth, including the lower Darling downstream from the Menindee Lakes. The initial phase is estimated to cost $150 million over 7 years. At the same time the Council has authorised studies of the environmental, social and economic impacts of 3 scenarios involving recovery of 350 GL, 750 GL and 1500 GL per year from existing uses, for reallocation to the environment.
This paper describes some of the key projects in the portfolio of works under consideration, including:
The paper also outlines the extensive stakeholder consultation and community engagement processes which are fundamental to the success of the project, as well as the various means adopted to enhance the links between scientists and engineers involved in the project.
Chas Keys and Steve Opper
As the legislated ‘combat agency’ for dealing with floods, the NSW State Emergency Service has had considerable experience in planning for flooding on the state’s rivers and in developing arrangements to help keep people safe when floods occur. This experience has been put to use over the past decade in the particular context of managing floods caused or exacerbated by dam failure. Some of the complexities of the dam-failure planning problem are explored in this paper, specifically as they relate to warning and evacuation tasks and to the issue of preparing communities for the extreme flooding which dam failure can be expected to cause. The points are made that warning is not just about mechanical alerting devices, evacuation is not restricted to commanding people to move, and public education requires a sensitive comprehension of the problems of disseminating information about rare and difficult-to-believe events.
Paul W. Heinrichs & John Bosler
Spring Creek Dam is a 16m high zoned earthfill dam with a central vertical concrete core wall storing 4700 ML for Orange City Council’s water supply. It was a 14.5m high dam constructed in 1931 and in 1947 was raised by 1.0m. In 1966 after a week of heavy rain following a long dry spell, an 80m section of the downstream face slumped but the dam fortuitously survived. In 1969 the dam was re-constructed but no internal drain/filter was installed.
Following the 1994 dam surveillance report, piezometers were installed in the downstream fill. Drilling for these revealed that a substantial portion of the zone downstream of the core wall was saturated. The piezometers recorded piezometric elevations that closely and rapidly followed the reservoir level. Subsequent site investigations identified pockets of very low strength fill immediately downstream of the core wall. It was concluded that the core wall was seriously compromised and the storage level was subsequently, significantly lowered, as an interim dam safety measure.
Dambreak studies indicated the dam is a high hazard and hydrological studies found that the spillway capacity was inadequate.
This paper details the problems involved, their analyses, and the remedial measures proposed at the concept design stage. These include a chimney filter/drain, a stabilising fill combined with embankment crest raising and the construction of a 3-bay fuse plug auxiliary spillway.
Tim Waldron, K D Murray and Allan Crichton
The City of Hervey Bay is a growing tourist community that is located a comfortable 3½ hour drive north of Brisbane. To meet the growing water demands of the community, Wide Bay Water Corporation required the raising of its sole water supply – Lenthalls Dam.
At the time of the option study, Queensland dam owners were aware of their obligation to manage their dams to minimise adverse environmental impacts but detailed Environmental Flow Objectives were still being developed.
This required a solution for the raising of Lenthalls Dam that provided maximum flexibility while, at the same time, being cost effective.
A range of solutions and new technologies were investigated. Using a Risk Management methodology, the Crest Gate system developed in South Africa was adopted.
Subsequently, draft Environmental Flow Objectives have been set and the use of a gated system has been beneficial in meeting post-winter flow objectives.