Management of dams requires the use of experienced dam engineers and other competent personnel familiar with all relevant basic principles, technical guidelines, articles and manuals. This requires appropriate qualifications, registrations and adequate knowledge and experience relevant to the type of dam and the task required.
Engineering services in Queensland must comply with the Professional Engineers Act 2002 which requires a registered professional engineer of Queensland (RPEQ) to undertake or directly supervise an engineering service. Attributes in addition to RPEQ are recommended for personnel responsible for dam safety management. Inputs are often required from non -engineering technical specialists, such as geologists. Supervising these inputs in the context of meeting the Professional Engineers Act 2002 should be considered.
A matrix of skills for dam safety management personnel has been prepared as part of the Queensland dam safety management guideline and subject to extensive stakeholder feedback in its preparation. The matrix consists of a list of roles typically required for dam safety management and, for each role, a corresponding set of recommended core attributes.
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Now showing 1-12 of 37 3483:
Sonel Reynolds, Alex Gower, Bob Wark
During the outlet works upgrade in 2017 it was found that the valve pit and stilling basin at Mundaring Weir were not founded on rock. Based on these observations and the arrangement of the spillway and outlet works, it was considered that during significant spillway overflow events, a high velocity jet could displace the stilling basin slabs, erode the underlying material, and progress to failure of the outlet pipe and valve pit. A comprehensive risk assessment was conducted to estimate the likelihood of stilling basin slab uplift, erosion of the underlying material, and failure of the outlet works. A geotechnical investigation was undertaken comprising drilling nine boreholes and a program of geophysical downhole logging. Computational Fluid Dynamic (CFD) modelling was used to determine the pressure fluctuations and turbulence intensity over the spillway slab which could lead to uplift. The erodibility of the rock mass material below the stilling basin slabs was assessed using the outcomes of the geotechnical investigations and CFD output, with analyses based on the Kirsten Index and eGSI. A net benefit analysis was conducted to assess whether preventative remedial works were justified. Through this process it was demonstrated that the business risk was low and risk reduction measures were not justified.
Reena Ram, Siraj Perera, Mark Pearse, John Pisaniello, Shane McGrath, Joanne Tingey-Holyoak, Peter Hill
Dam construction in Victoria commenced in the 1850s and there are over 8,000 dams currently regulated by the Department of Environment, Land, Water and Planning (DELWP). Dam ownership spans across state owned water utilities and local government authorities to privately owned hydro-electricity generators and farmers.
Victoria was one of the first states in Australia to adopt risk-informed principles in the management and regulation of dam safety. A recent review of the State’s dam safety regulatory framework included a comparative analysis of Victoria’s dam safety arrangements with other regulatory regimes within Australia and overseas, including a total of 16 jurisdictions. A similar review was conducted in 2010.
The objective of the 2019 review was to examine the effectiveness of dam safety regulation in managing dam safety risks in Victoria and to assess the extent that dam safety regulation was consistent with good practice so that improvement opportunities could be identified.
This paper discusses the processes adopted in comparing various regulatory models, identification of good international practices and opportunities to achieve improved public safety outcomes for dam owners and regulators. In particular, it outlines how the State’s journey in progressively reducing dam safety risks over the years can be further strengthened.
Claudia Smith, Shannon Dooland, Adam Broit, Rachel Jensen, Samantha Watt
The estimation of real consequences from dam failure that directly link to the overall likelihood of the failure is a challenging task, particularly in data sparse locations. Previous regional methods have often relied on simplistic assumptions without consideration of the true joint probability of the volume of flow in the downstream tributaries of concurrent catchments. As a result, concurrent downstream flooding directly impacting the consequence in dam break assessment scenarios may be misrepresented. More recently, the adoption of streamflow-based joint probability has become the standard, particularly where consequence estimation is used within the context of risk assessment. This paper progresses the work completed by others to establish a practical treatment method based on rainfall analysis where suitable streamflow information is unavailable. A case study is also presented where this method has improved the understanding of the risk profile associated with a coastal storage based on a better estimate of the likely flood concurrence within the storage and downstream catchments.
Zara Bostock, Helena Sutherland
Ewen Maddock Dam is located approximately 12.0 km west of Caloundra, in the Sunshine Coast area of Southern Queensland. The dam is a homogeneous earthfill embankment dam 10.5 m high and 724 m long. The dam was originally built between 1973 and 1976 and later upgraded in 1982 to raise the ogee spillway crest by 2.44 m to the current Full Supply Level (FSL) of 25.38 m AHD.
Seqwater is undertaking a staged upgrade of Ewen Maddock Dam to address deficiencies identified during the Acceptable Flood Capacity (AFC) Review (GHD, 2010). The consequence category assigned to Ewen Maddock Dam is ‘Extreme’ with a downstream Population at Risk greater than 1000.
Stage 1 construction was completed in 2012 to manage the seepage underneath the dam to reduce the risk of piping and improve embankment stability. Stage 2A involved retrofitting a filter in the existing embankment and raising the dam 1.61 m to 30.11 m AHD using a reinforced concrete parapet wall. Stage 2B involves spillway upgrade works and was split from 2A due to approval constraints.
Stage 2A construction was completed in April 2021, navigating various project and dam safety challenges. This paper presents some practical ways dam safety and risk was managed on the ground from the perspective of both the designer and owner.
Chris Nielsen, Ron Guppy, Gary Hargraves, Robert Fowden
Dam safety upgrade projects of major dams typically involve a large capital investment. It is important that expenditure decisions are based on sound criteria, both technical and non-technical. Independent peer review of technical matters plays a key role in meeting design, construction and safety objectives within practical financial constraints and assuring robust, resilient and reliable project outcomes.
An independent technical review is recommended for all dam projects.
The Queensland dam safety regulator has developed guidelines associated with technical review for dam safety projects that considers scope and limitations, expertise and governance. The guidelines are informed by literature, recent projects, a commission of inquiry, internal and external review and industry feedback. The guidelines are being implemented across major dam safety upgrade business cases through preparation of terms of reference by the Queensland Government’s business planning and implementation entities, who maintain the responsibility of providing assurance to state government projects, as well as the state’s major dam owners.
The terms of reference, supported by the underlying principles in the guidelines, provide a platform for consistent and appropriate application of technical assurance to dam projects in Queensland. Among other matters, governance is highlighted as a critical factor for success as well as clarity of the roles, responsibilities and reporting lines of all parties. The application of both guidelines and terms of reference to recent projects is discussed.