Russell Paton, Peter MacTaggart, Lee Benson
The Nathan Dam project has been identified by the State Government of Queensland as a potential water supply option to facilitate future growth in central Queensland. The proposed storage is located approximately 69 km downstream of the township of Taroom and would have a storage capacity of 1,080,000 ML which would make it Queensland’s fourth largest storage.
The proposed dam arrangement includes a central concrete gated spillway section across the river in order to maximise the storage volume and limit the flood rise upstream such that flood levels at Taroom are not increased during major flood events. A high level fixed crest spillway, to assist in the passage of rare flood events, forms the right abutment portion of the dam wall. It is proposed that the bulk of the concrete sections of the dam be constructed using roller compacted concrete (RCC).
The investigations to progress Nathan Dam are complicated by the existence of the Boggomoss Snail (Adclarkia dawsonensis) within the proposed inundation area. The snail is listed as a critically endangered species under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), and a proportion of the snail’s known population is located on a Boggomoss (the colloquial name for an artesian spring) that will be inundated should the project proceed.
SunWater has engaged Australia’s foremost expert on land snails to design a translocation process aimed at relocating the species to alternative habitat outside the inundation area. The process will seek to not only protect the snail from the dam development, but to increase both its numbers and distribution thereby reducing risks to the currently isolated population from threats such as fire and predation. It is the first time in Australia that such a trial has been attempted, and SunWater is working closely with the Federal Department of Environment, Water, Heritage and the Arts (DEWHA) to ensure that the process is consistent with their policies and guidelines.
The paper will discuss the engineering and environmental challenges of the dam and how the Environmental Impact Study process can influence the delivery of a project.
Keywords: Nathan Dam, Environment, Engineering
Now showing 1-12 of 38 2973:
Amanda Barrett, Mike Marley, Tariq Rahiman
The site of the Wyaralong Dam, west of Beaudesert, Queensland, has been investigated in progressive stages since 1991. The first stage of the investigation was a siting study and the second in 2006 was designed to gather sufficient geotechnical information to develop a preliminary design and provide input into the environmental approval process. The third stage of the investigation was designed to gather further information to allow the detailed design of the dam to commence. This iterative investigation approach has ensured confidence in the site geology and geotechnical model.
The site investigations have included diamond drilling, piezo-cone penetration testing, geophysics techniques, hydraulic conductivity testing, groundwater pumping tests, costean excavation, geological mapping and accompanying laboratory test programs. Investigations have been targeted to assess the foundation conditions for the proposed engineering structure and have been refined to the needs of the dam design as it has developed.
With sufficient data, a 3-dimensional geotechnical model has been developed using the computer modelling program Vulcan, to assess the position and influence of a number of key geological features observed in the site investigation. Assessment of engineering properties based on in situ and laboratory testing were then extrapolated across the site through application of the geotechnical model.
Keywords: Wyaralong Dam, geotechnical investigation, geology, 3-D Vulcan model, foundation.
Tommie Conway, Katherine Miller, Peter Hill
The ‘Black Saturday’ fires of the 7th of February 2009 and the continuation of fires over the following weeks had devastating human, environmental and financial costs for Victoria. Many of Melbourne’s water supply catchments and assets were burnt and the major harvesting catchments were seriously threatened. This paper highlights the need for owners and managers of catchments, dams and associated infrastructure to better understand and plan for the potential impacts of fire, given its predicted increased likelihood and severity due to climate change.
The paper will share Melbourne Water’s recent experiences of the fire, the scale of the impact to the business in terms of assets damaged and catchments affected, the extent of the burn and the threat that was faced. It will describe Melbourne Water’s experience with the United States Burnt Area Emergency Response (BAER) team to expediently map the severity of the fires, to identify areas of concern and prioritise fire recovery works. Of interest to those involved in risk management will be the discussion of the construction flood risk analysis at Tarago Reservoir which was revisited due to severe fire damage to the catchment.
Keywords: fire impact, Melbourne’s water catchments, BAER team, hydrology, Tarago, construction flood risk analysis
Robert Fowden, Peter Allen, John McKenna
The Large Referable Farm Dam Assessment Program commenced in early 2006 after inspections identified a significant number of Queensland dams that were unknown to the Department of Environment and Resource Management (DERM) and could potentially threaten life if they were to fail. The program is unique given the number of structures under consideration and is understood to be the first widespread, systematic search for dams with a population at risk in the world. The Dam Safety (Farm Dams) team has developed many original solutions to allow the majority of investigations to be undertaken in-house, thus minimising the potentially higher cost and timeframe issues associated with obtaining external engineering and surveying support.
Keywords: Queensland, dam safety, dam failure, regulation, farm dams, surveying, modelling
Angus Swindon, Tony Ang
Managing risk lies at the heart of the asset management processes. All utilities and large asset owners strive to ensure their asset management practices meet the needs of the business. To be able to demonstrate this to internal and external stakeholders including Boards, Regulators and Insurers, some form of bench marking or comparison with industry practice is often undertaken. This inevitably leads to a discussion about what good or indeed best practice might look like and a somewhat philosophical discussion about what aspects of these might be appropriate. If an organisation chooses to define “World Class Asset Management” as “the level of practice that no one else could exceed given the same internal requirements and constraints and external operating environment” then that organisation must develop a framework such that a pathway to achieve this can be defined and an assessment made. This paper will present such a framework and describe a pathway to demonstrate progress towards asset management maturity. Actively managing surveillance practices to monitor dam condition and performance is presented as an example within such a framework.
Keywords: World Class Asset Management, Dam Safety, Surveillance, ANCOLD Guideline.
Peter Cordi, Paul Fuller
Tallowa Dam was completed in 1977 at the junction of the Shoalhaven and Kangaroo Rivers in the southern highlands of NSW to provide a pumping pool for water supply transfers to Sydney. These transfers were made only during drought periods, at which time limited and fixed environmental flow releases from a low level outlet were made to the downstream Shoalhaven River. After extensive consultation with the local community the Government decided in 2006 to commence transfers earlier in the drought cycle, and release variable amounts of surface water to improve river health during transfer periods. In addition, Tallowa Dam was identified as having a significant impact on fish passage, as many species migrate to the estuary during their life cycle, and approximately 75% of the viable fish habitat was upstream of the dam. This project involved the design and construction of works to be retrofitted to the dam to address both issues. A surface water release slide gate in the spillway, a low friction coating on the spillway, and a downstream weir were constructed to release environmental flows and allow safe downstream fish passage. A new fish attraction flow outlet was drilled through the dam wall, and a fish attraction chamber and a travelling bucket fish lift was installed for upstream fish passage.
Keywords: environmental flows, fish passage, Shoalhaven River, construction.