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.
— OR —
Now showing 1-12 of 37 3483:
Alberto Scuero, Gabriella Vaschetti, John Cowland
Efficiency in water supply reservoirs, even more so in pumped storage reservoirs, requires good water management and minimisation of water losses. With climate change affecting the quantity of water available for supply and power generation, minimising water losses is becoming more and more crucial, and the most efficient way to achieve this critical objective is to line the reservoir with a watertight geomembrane system. With more than 60 years of use, flexible geomembrane systems have proven to be a dependable technology for new construction as well as for rehabilitation. Efficiency can also be increased by covering the reservoir with a floating geomembrane cover to minimise evaporation losses, and by adding value to the reservoir with the installation of floating photovoltaic panel farms on the surface of the reservoir, to provide or increase electrical power generation. This paper addresses these two aspects of efficiency: water loss minimisation, by presenting concepts and advantages of geomembrane liners, and concepts and application
of floating photovoltaic farms with a case history in a water supply reservoir. The concept of a floating
photovoltaic farm on a pumped storage reservoir, and information on available guidelines for geomembrane systems and floating photovoltaic panels, are also presented.
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.
Dr Mark Leonard
The quantification of the 85% and 95% hazard fractiles, as required by the ANCOLD 2019 Guidelines for design of dams, is investigated. It is found that there are four independent sources of uncertainty in the PSHA input models that have a significant effect on the hazard. So all four need to be quantified, particularly for Extreme and High A consequent dams. It is also found that the uncertainty of many of the other parameters, which are routinely included in probabilistic seismic hazard assessments, have minimal effect on either the mean or the higher fractiles so do not necessarily need to be routinely included. The complexity of the input models required to satisfy the new standards are substantially higher than those routinely used in prior decades.
T. I. Mote, N. Vitharana, L. Johnstone, and K. Illangakoon
In Australia, the consideration of faults in seismic design has been captured in recent ANCOLD Guidelines for Design of Dams and Appurtenant Structures for Earthquake. The Guidelines recommend proper characterisation of geologic setting, foundation conditions, seismotectonic setting, and identification of both active and neotectonic faults as input to the seismic design basis for dams in Australia.
A case-study is presented at the proposed Cultana Pumped Hydro Energy Storage Project in South
Australia, summarising a fault assessment in concert with reference design. The progressive assessment of a lineament to a possible active fault to ultimately a non-seismogenic fault, allowed insights in understanding active fault rupture risk and active fault implications as it pertains to siting a dam in Australia. It highlighted the need for proper characterisation of geologic setting and faults based on targeted geotechnical investigations and the challenges in phasing these with an aggressive design program. These insights are relevant to many other projects in Australia either in existence or being planned for construction.
Ryan Cantrill, Petros Armenis & Angus Cannon
Large Australian dams span a range of ages and were designed and constructed to the prevailing
standards and practices of the day. Since that time, there has been a veritable explosion in monitoring and surveillance technologies available to dam owners to assist with risk management of their portfolio. Coupled with this has been the formalization and ongoing development of regulatory frameworks across the industry.
This paper endeavours to share Sunwater’s recent experience on this topic. Specifically, the following question is considered – how best to apply modern monitoring and surveillance technologies to manage dam safety risks associated with decades old structures, all while still meeting regulatory requirements? In answering this question, the authors necessarily had to consider several inputs including – physical condition of the existing assets; analysis of existing controls and mitigation measures; risk assessment and risk profile of the assets; and operational constraints. As always, outputs invariably required the prioritization of recommendations.
While dam owners must strive to comply with a standard and accepted way of managing their portfolio, it is vital they recognize and address the unique risks that each structure presents. It therefore follows that owners must be prepared to allow the time and provide the necessary resources when formulating a monitoring and surveillance program commensurate with the dam safety risk that their respective portfolio presents