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.
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Now showing 1-12 of 37 3483:
Dan Clark, Joanne Stephenson, Trevor Allen
We present earthquake ground motions based upon a paleoseismically-validated characteristic earthquake scenario for the ~ 48 km-long Avonmore scarp, which overlies the Meadow Valley Fault, east of Bendigo, Victoria. The results from the moment magnitude MW 7.1 scenario earthquake indicate that ground motions are sufficient to be of concern to nearby mining and water infrastructure. Specifically, the estimated median peak ground acceleration (PGA) exceeds 0.5 g to more than ~ 10 km from the source fault, and a 0.09 g PGA liquefaction threshold is exceeded out to approximately 50-70 kilometres. Liquefaction of susceptible materials, such as mine tailings, may occur to much greater distances. Our study underscores the importance of identifying and characterising potentially active faults in proximity to high failure-consequence dams, including mine tailings dams, particularly in light of the requirement to manage tailing dams for a prolonged period after mine closure.
Rachel Jensen, Adam Broit, Chriselyn Kavanagh
Downstream emergency response is a critical driver in the consequences and potential life loss associated with dam flooding and failure. This response is highly varied between stakeholders, communities and the nature of the flooding or dam threat. As assessments on dam failure consequence and potential loss of life become increasingly important in understanding holistic dam risk, they are also becoming increasingly complex.
As part of a portfolio wide Comprehensive Risk Assessments, Sunwater have undertaken workshops with a wide range of stakeholders to better understand downstream emergency response and the warning timeline. The workshops have been aimed at facilitating better downstream stakeholder engagement, obtaining key data for consequence assessments and developing consistency in assumptions for potential life loss.
This paper presents the standardised methodology undertaken for warning time workshops, the outcomes for a range of downstream stakeholders and correlations between stakeholder groups which influence warning time response. These outcomes may be used by practitioners in the absence of catchment specific warning time data and provide a counterpoint to international standard warning time assumptions.
Richard Mannix, Michael Cawood, Joseph Matthews, Siraj Perera
Guidance material available to dam owners both domestically and internationally on testing dam safety emergency plans (DSEP) and running exercises is relatively general in nature. Guidance specific to dams that assists owners to design risk informed exercise scenarios tailored to their dam(s) total risk profile and the broader context in which the consequences of dam and operational safety failures would materialise, is limited.
This paper presents a framework that guides dam owners through a progressive scenario development process that enables the systematic identification of both dam and operational safety matters that require exploration as part of DSEP exercising. This level of rigour in guidance material has, until now, been missing and is particularly relevant in the context of dam owners demonstrating due diligence and SFAIRP imperatives while also bringing dam safety management closer to achieving the safety case.
Yuqi Tan, Behrooz Ghahreman-Nejad, Keith Seddon
Inadequate geotechnical investigation and hence undetected issues within the dam foundation have been responsible for many dam failures in the past. Fissured clay in the foundation poses a significant risk to the stability of the dam if it is not adequately detected and characterised. This paper presents a framework to evaluate the strength characteristics of fissured clay and its effect on the stability and performance of an embankment dam. The strength of fissured clay can be characterised from conventional triaxial test result based on the dip angle of the fissure plane. A design chart for the strength of the fissure has been developed based on the dip angle. The stability assessment for a tailings dam indicated that the dip angle of the fissure has significant impact on the overall stability of the embankment when the angle of the fissure aligns with the angle of the critical failure plane. Both fissure strength and fissure angle should be carefully evaluated for a site where fissured clay is observed.
Chris Nielsen, Ron Guppy, Donna Dunn, David Murray
Following several years of investigations and analysis a serious safety issue with the stability of the primary spillway during major flood events was identified at Paradise Dam that required urgent risk reduction works. The response to this safety issue was significant.
The Inspector General Emergency Management conducted a review into the effectiveness of emergency response if a dam safety event were to occur, taking into consideration process and communications to manage around 40,000 population at risk, comprised mostly of residents within the city of Bundaberg.
An essential works program to reduce the risk was urgently prepared then executed effectively within a calendar year. This short timeframe required significant and novel amendments to Queensland’s laws to bypass normal legislated process for such a major project.
The Paradise Dam Commission of Inquiry was established to identify the root cause of the issues, the facts and circumstances that contributed to them and recommendations to consider for future dam projects. All recommendations from the commission were accepted by the Queensland government and, following an extensive stakeholder engagement exercise, have been implemented through changes in policy and methodology and described in published guideline revisions.
For future dam projects the lessons learnt highlighted the need for early and ongoing engagement of
independent technical review, project governance that is cognisant of risk and the ownership and capacity to bear of that risk, the need to consider testing to confirm critical design parameters and the need for an effective regulator. The essential works program has established a precedent for the timely and appropriate application of risk reduction measures.