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Shane McGrath, Mark Arnold, Josh Rankin, Gavan Hunter
Greenvale Dam is a critical storage for the supply of potable water to Melbourne. The dam had been upgraded through current risk management techniques, and an ALARP assessment completed at that time. However, it was decided that a more comprehensive demonstration of ALARP was warranted to satisfy the dam owner’s duty of care. Since there is no comprehensive guidance in the dams industry for owners and their advisors to reference, the safety case approach used extensively in other hazardous industries was adopted. Considering the approaches used by Victoria’s Worksafe, the Institution of Engineers Australia and the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA), the key components of the safety case for Greenvale dam were identified then developed to provide a logical, structured and comprehensive argument for the safety of Greenvale Dam. This paper provides an overview of components of the safety case developed for Greenvale Dam, the use of safety cases for dams and where process improvements could be made.
Now showing 37–48 of 84 search results:
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2020 Papers
2020 – The Safety Case
Learn moreShane McGrath, Mark Arnold, Josh Rankin, Gavan Hunter
Greenvale Dam is a critical storage for the supply of potable water to Melbourne. The dam had been upgraded through current risk management techniques, and an ALARP assessment completed at that time. However, it was decided that a more comprehensive demonstration of ALARP was warranted to satisfy the dam owner’s duty of care. Since there is no comprehensive guidance in the dams industry for owners and their advisors to reference, the safety case approach used extensively in other hazardous industries was adopted. Considering the approaches used by Victoria’s Worksafe, the Institution of Engineers Australia and the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA), the key components of the safety case for Greenvale dam were identified then developed to provide a logical, structured and comprehensive argument for the safety of Greenvale Dam. This paper provides an overview of components of the safety case developed for Greenvale Dam, the use of safety cases for dams and where process improvements could be made.
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2021 Papers
2021 – Development of a practical SFAIRP framework for dams
Learn moreMark Pearse, Mark Foster, Peter Hill, Sam Banzi, Muhammad Hameed, Benson Liu
Determining which risk control measures are required is one of the top issues for dam owners as they contend with limited resources generally and capex in particular. The key issue addressed in this paper is how a dam owner can both identify the control measures that they should implement and demonstrate that they are acting reasonably and responsibly. The Framework developed in this paper provides a practical and transparent way to address the relevant matters that are required to be considered under common law, work, health and safety (WHS) legislation and the NSW Dams Safety legislation for determining whether a risk control measure is reasonably practicable. It provides dam owners with a transparent and defensible way of both identifying the controls and demonstrating that they are acting in a reasonable and responsible manner.
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2021 Papers
2021 – Recommended skills for dam safety management personnel
Learn moreChris Nielsen
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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2021 Papers
2021 – WaterNSW Dam Safety Alert Trigger Framework
Learn moreDamien Bryan, John Sukkar, Erin Hughes, Michael Cawood
Alert triggers are a critical component of Dam Safety Emergency Management, aligning clearly defined adverse conditions with alert levels to initiate an appropriate emergency response. Early detection of these conditions allows for potential mitigation measures to be undertaken, early engagement of key stakeholders such as emergency agencies, and where necessary, the warning or evacuation of affected downstream communities. The Dam Safety Alert Trigger Framework provides WaterNSW with a consistent, repeatable, and defensible methodology for the determination of appropriate dam safety alert triggers. The framework was developed through the engagement of consultants, emergency and regulatory agencies (NSW SES & DSNSW), and several Australian large dam owners.
The determination of appropriate Dam Safety Alert Triggers is a challenge faced by all dam owners. Through the development and implementation of the Alert Trigger Framework, WaterNSW has achieved the ability to define defensible alert triggers through a consistent and repeatable methodology. This has resulted in an improved dam safety emergency response posture for WaterNSW, key emergency services partner the NSW SES, and greater protection for affected downstream communities. Concepts, processes and methodology covered in this paper could be used by other dam owners in addressing their own dam safety alert trigger challenges.
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2014 Papers
2014 – Risks Event Trees in the Assessment of Dam Safety
Learn morePrzemyslaw A. Zielinski
Three aspects of the current engineering practice in using event trees in dam safety risk analyses are discussed in the paper. These aspects include assignment of probabilities for initiating events, treat-ment of dependencies in the event tree, and dynamic aspects of dam system behaviour and accounting for time. The paper discusses limitations of the methodology and common mistakes in engineering applications of event tree methods when assessing dam safety risks and making safety decisions for specific dams. Of particular importance is the discussion of incorrect interpretation of dependency structure when addressing common cause failure modes.
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2006 Papers
2006 – Which Belts And Braces Do We Really Need? – Application of a Functional Safety Methodology to a Dam Safety Assurance Programme
Learn moreC Lake and J Walker
Meridian Energy is the owner and operator of a chain of hydro dams on the Waitaki River in the
South Island of NZ. It operates a Dam Safety Assurance Programme which reflects current best
practice; consequently it has focused primarily on managing civil dam assets. Advances in plant control technology have allowed de-manning of our power stations, dams and canals through centralised control. The safety of our hydraulic structures is increasingly reliant on the performance of Dam Safety Critical Plant (DSCP) – those items of plant (eg water level monitoring, gates, their power and control systems, and sump pumps) which are required to operate automatically, or under operator control, to assure safety of the hydraulic structures in all reasonably foreseeable circumstances.Recent dam safety reviews have highlighted that the specification and testing of our DSCP is based on the application of ‘rules of thumb’ which have been established through engineering practice (eg. “monthly tests”, “third level of protection”, “backup power sources”, “triple voted floats”). The
adequacy of these engineering practices is difficult to defend as they are not based on published
criteria. The realisation that such rules may not be relevant to the increased demand on, and complexity of, DSCP led us to ask “Which belts and braces do we really need?” The current NZSOLD (2000) and ANCOLD (2003) Dam Safety guidelines give little guidance regarding specific criteria for the design and operation of DSCP.Meridian has identified the use of Functional Safety standards (from the Process industry, defined in IEC 61511) as a tool which can be applied to the dams industry to review the risks to the hydraulic structures, the demands on the DSCP, and utilise corporate “tolerable risk” definitions to establish the reliability requirements (Safety Integrity Levels) of each protection, and determine lifecycle criteria for the design, operation, testing, maintenance, and review of those protections.
This paper outlines the background to identifying Functional Safety as a suitable tool for this purpose, and the practical application of Functional Safety Analysis to Meridian’s DSCP.
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2006 Papers
2006 – CORPORATE GOVERNANCE FOR DAM SAFETY
Learn moreS. Frazer
Ensuring compliance with the Regulator’s requirements is a cornerstone consideration for any water corporation in planning its risk minimisation strategies against dam failure. With the increased focus on due diligence and corporate governance however, there are emerging themes that are of equal importance for a water corporation in planning protections against its core risks to dam safety.
These considerations include:
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• documenting and implementing plans and strategies to ensure corporate compliance with the
Regulator’s requirements and updating these in line with legislative and policy changes;
• Documenting and implementing the corporation’s defences to the common law duty of care for
public liability, including keeping up to date with the latest case law development locally and
internationally in interpreting implications in respect of damage to property and injury and loss of
life in relation to dam failure.
• Adopting behaviours and practices that bear out a compliance culture – is the current dam safety
assessment and training “best practice” and is this enough to defend a claim? What is reasonable
in economic and practical terms to ensure defensibility?
• ensuring the Board, Executive and other Officers are informed of operational decisions and
incidents and their advice is implemented;
• arranging and maintaining appropriate insurances if available for public liability and property
damage, as well as protections for directors and officers, both past and current.
• Developing and implementing a policy for disclosure, document management and retention that will support investigation for legal proceedings purposes; including providing privilege for relevant
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2013 Papers
2013 – Case study of risk assessment for dam safety management decision-making in Korea
Learn moreJeong Yeul, Lim
For various historical reasons and some technical reasons, the safety of dams has been evaluated using an engineering standards-based approach, which was developed over many years. It was used initially for the design of new dams, but increasingly has been applied over the past few decades to assess the safety of existing dams. Some countries have carried out risk assessments of existing dams that included both the structural and hydraulic safety of the dam and social risk. These methods developed by other countries could be adapted to assist in decision-making for dam safety management. Unfortunately, methods for risk assessment of dams were not established in Korea. This study outlines a beginning risk analysis for structural safety management. The first stage consisted of research on the present domestic dam safety guidelines and reviewing operations for management systems of dam safety abroad. Also, dam risk analysis requires reliable data on dam failure, past construction history and management records of existing dams. A suitable risk analysis method of dams for structural safety management in Korea is use of event tree, fault tree and conditioning indexes methods. A pilot risk assessment was carried out for two dams. The dam risk assessment process was thus established, and we learned the importance of risk assessment. The future includes additional research and risk analysis to develop the system.
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2013 Papers
2013 – A case study: how to minimise risks associated with a portfolio of non-revenue generating dams
Learn moreMonique de Moel and Gamini Adikari
Parks Victoria manages over 4 million hectares of parkland and a portfolio of over $1.9 billion worth of infrastructure assets. Within this portfolio, Parks Victoria is responsible for a large number of dams and their associated structures. Consequence category of these dams varies from Extreme to Very Low. Parks Victoria recognised that these assets required a dam safety management and monitoring program. The development of a program commenced with a portfolio risk assessment in 1998 which progressed to detailed design reviews of a selected number of dams and the initiation of an ongoing dam safety and surveillance program. This initial work identified the need for dam safety upgrade works within this asset portfolio which Parks Victoria has been progressively addressing. In 2012 Parks Victoria identified that a review of the risk profile of the dams was warranted. The review included consideration of alternative options such as staging of works, reducing storage volume and decommissioning, as well as non-technical considerations such as increasing the recreational use and the environmental value of these assets. This paper outlines the approach adopted by Parks Victoria in developing and improving its dam safety program and how it has assisted in minimising dam safety risks. Specifically, Parks Victoria’s approach of adopting measures that recognize the purpose and benefits of the individual storages, whilst being sympathetic to the requirements of the other infrastructure within its diverse portfolio of assets is highlighted. Since this work commenced in 1998, Parks Victoria have been successful in the development of an effective dam safety and management program which has resulted in the reduction of risks associated with this portfolio of assets.
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2007 Papers
2007 – Cobb Dam sinkholes
Learn moreBruce Walpole and Craig Scott
Monitoring and surveillance is crucial to managing the ongoing performance of dam structures.
The true value of appropriate monitoring, surveillance and review processes is only realised when
potential dam safety issues arise. TrustPower’s civil safety monitoring and surveillance program
includes nineteen hydro schemes throughout New Zealand and incorporates structures with
Potential Impact Classifications (PIC) ranging from Low to High.TrustPower promotes a continual improvement policy on its management of safety issues and
conducts inspections on a regular basis. Routine and periodic independent inspections of the key
components within a scheme are paramount to the viability of the safety management system. The
importance and purpose of these inspections has recently been highlighted by the discovery of two
sinkholes on the face of the earth dam associated with the Cobb hydro electric power scheme.This paper provides an example of the need for continual monitoring and surveillance, vigilance
of observations, good archiving systems and documentation. It discusses the broader issues
surrounding the subsequent response processes to potential dam safety deficiencies, and the
success (or otherwise) of investigative methods. It also highlights that an adequate dam safety
compliance system has commercial value as there is a measurable reduction in dam performance
uncertainty and hence greater efficiency in the speed at which accurate resolutions can be drawn.Keywords: Dam safety, embankment, sinkholes, foundations, dam drainage, geophysical
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2007 Papers
2007 – Seismic hazard assessment of the Lake Edgar Fault
Learn moreA. Swindon, M. Gillon, D. Clark, P Somerville, R. Van Dissen and D. Rhoades
The 45 km long Lake Edgar Fault in south-west Tasmania passes through the right abutment of the Edgar Dam and into Lake Pedder, and within 30 km of three other large dams. In 2004 an independent seismotectonic study concluded that the fault had moved three times in the past 48–61,000 years, with the last movement around 18,000 years ago.
In order to better constrain the risk assessment for the nearby dams, the likelihood of a rupture recurrence along the fault was required. Two independent methods were investigated. The first was a comprehensive review of active faulting and deformation of stable continental region faults within Australia, and a comparison with similar faults worldwide with the well studied behaviour of the Lake Edgar Fault. The study results demonstrated the episodic nature of stable continental region fault activity, separated by much longer periods of quiescence, with a decreasing likelihood of rupture following each event within an active period. The time window of applicability of this paleoseismological study is thousands to tens of thousands of years.
The second study looked for evidence of precursory seismic activity in the vicinity of the fault which could indicate an increasing risk of rupture over the next decade or so. This method does not predict specific earthquakes, but does forecast whether the level of future earthquake activity in the short to intermediate term is relatively low, high or at an average level. Using a catalogue of seismic activity for south-eastern Australia, the study concluded that there is no evidence for precursory seismic activity in the area of the Lake Edgar Fault that would give rise to an elevated forecast rate of occurrence of moderate magnitude earthquakes either in the short to intermediate term. This precursory method has a window of applicability of a decade to perhaps several decades.
The combination of these two studies has advanced the understanding of the Lake Edgar Fault activity by both setting it in the long-term stable continental region fault context and investigating the presence of short-term behavioural activity. This has allowed the seismic hazard to be re-assessed as nearer to ambient levels than earlier postulated. This work has applicability for other fault scarps in Australia, both with regards to better defining the long-term hazard (103-105 years) posed by a fault, and potentially also giving advance (short-term 101 years) notification of increasing risk of fault rupture. Better long- and short-term hazard information allows more complete and thorough engineering decisions to be made.
Keywords: Earthquake, seismic, fault rupture, dam safety, risk assessment, Hydro Tasmania, Lake Edgar Fault.
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2007 Papers
2007 – Improving safety and hydraulic efficiency of dams with physical model studies
Learn moreSteven L. Barfuss and Blake P. Tullis
An important aspect of improving the safety of dams is selecting designs that are both hydraulically efficient and cost-effective. A powerful tool that can be used as part of the hydraulic structure design process is a physical model study. To obtain maximum benefit from the model, it should be implemented as a part of the design process rather than as a post-design verification phase. A model study included early in the conceptual design phase can also provide increased flexibility to the designers.
Hydraulic model studies can often provide cost-effective answers to difficult problems. Some of the issues that can be efficiently resolved using model studies include optimizing spillway head-discharge relationships to increase reservoir storage while minimizing upstream flooding potential, controlling downstream scour, quantifying hydraulic uplift forces and/or overturning moments of dam structures, evaluating alternatives for structure retrofit or repair, and optimizing control gate sequencing during floods. Model studies also allow the engineer to simulate prototype performance (e.g., three-dimensional flow patterns, velocities, pressures, scour potential) over the full range of expected discharges. Quick and easy changes to the model can be made at minimal cost when evaluating the performance, safety and economic impact of various design alternatives.This hands-on model study approach to dam safety represents a tool that in some cases is underutilized.
Brief discussions of several physical model studies conducted at the Utah Water Research Laboratory, Utah State University in Logan, Utah, USA, are presented to illustrate key points of the paper. The primary objective of each of these model studies was to provide and/or improve the safety of the dam and the spillway while minimizing construction costs. This paper discusses the cost-effectiveness and hydraulic improvements that can be achieved through physical model studies.
Keywords: Physical models studies, design, hydraulic efficiency, dam safety, construction costs
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2012 Papers
2012 – Estimating potential loss of life from dam failure in the digital age
Learn moreSimon Lang, Peter Hill, Wayne Graham
The empirical method developed by Graham (1999) is the most widely used in Australia to estimate potential loss of life from dam failure. It is likely to remain that way while spatially based dynamic simulation models are not publicly available (e.g. LIFESim, HEC-FIA and LSM). When the Graham (1999) approach was first developed the prevalence of spatial data and the speed of computers was much less. In addition, most people did not have mobile phones, social media was in its infancy, and automatic emergency alert telephone systems were 10 years from being used in Australia. Graham (1999) was intended to be applied to populations at risk (PAR) lumped into a discrete number of reaches. The selection of fatality rates for the PAR in each reach was based on average flood severity and dam failure warning times. Today, there is typically much more spatially distributed data available to those doing dam failure consequence assessments. Often a property database is available that identifies the location of each individual building where PAR may be, along with estimates of flood depths and velocities at those buildings. News of severe flooding is likely to be circulated by Facebook, Twitter and e-mail, in conjunction with official warnings provided by emergency agencies through radio and television and emergency alert telephone systems.
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This raises the question of how Graham (1999) is best applied in today’s digital age. This paper explores some of the issues, including the estimation of dam failure warning time, using Graham (1999) to estimate loss of life in individual buildings and the suitability of Graham (1999) for estimating loss of life for very large PAR.
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2008 Papers
2008 – Design considerations for upgrading SunWater’s dams for acceptable flood capacity
Learn moreBrendan Trebilco
Abstract: A number of SunWater’s dams are in the process of being upgraded to the acceptable flood capacity (AFC) to ensure the highest level of safety. The Fred Haigh Dam upgrade was completed in September 2006 and the Bjelke Petersen Dam upgrade was completed in October 2007. Borumba Dam is the latest upgrade being undertaken with construction commencing in April 2008 and is expected to be completed by December 2008. Each dam underwent a comprehensive risk assessment to identify and evaluate all risks with respect to the ANCOLD tolerability limits to ensure risks satisfied ALARP. The assessment identified the most cost effective upgrade solutions for detailed design.
The upgrade at Fred Haigh, Bjelke Petersen and Borumba Dams will enable them to pass an extreme flood equivalent to 50% of the Acceptable Flood Capacity (AFC). This is Stage 1 of a two stage upgrade to ultimately achieve 100% of the ANCOLD “Fallback” AFC which is the standard SunWater has adopted for its major dams. SunWater has prioritised spillway capacity upgrades to achieve a minimum dam portfolio standard of passing 50% Acceptable Flood Capacity inflow by 2015 and full Acceptable Flood Capacity inflow by 2025.
The most economic Stage 1 upgrade option for Fred Haigh, Bjelke Petersen and Borumba Dams was to maintain the existing spillway width and to raise the dam crest with a concrete parapet wall. For the Bjelke Petersen and Borumba Dams the spillway training wall heights were raised to allow for increased flow though the spillway. From the hydraulic model studies and flood routing a height of each different dam crest wall was obtained.
This paper will describe the different methods and considerations used for upgrading Fred Haigh, Bjelke Petersen and Borumba Dams to the 50% AFC.
Keywords: dam safety, spillway, Fred Haigh Dam, Bjelke Petersen Dam, Borumba Dam, SunWater, Queensland.
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2008 Papers
2008 – Construction of a full height filter buttress against a full reservoir at Dee Dam
Learn moreChris Topham, Paul Southcott, Tim Cubit
Abstract: Dee Dam is a 15 m high and 270 m long central core earth and rockfill dam on the upper reaches of Hydro Tasmania’s Tungatinah Power Scheme. The dam is assessed to have a High A hazard category. Hydro Tasmania’s portfolio risk assessment found that a risk based upgrade was warranted to protect against both piping and flood overtopping failure modes.
A $4.2M modernisation project was implemented in 2008 comprising the installation of a full height downstream filter with rockfill buttress, repairs to cracking in the diversion conduit and raising of the core for improved flood capacity. Lowering of the Dee Lagoon to facilitate full height excavation of the downstream shoulder of the dam was impractical to Hydro Tasmania for production, environment, cost and stakeholder reasons. Hence, careful analysis and risk management was required to ensure the safety of the dam during the construction of the above works against a full storage.
This paper presents the risk objective for the upgrade work, modelling and analysis undertaken to assess dam safety during the works. A wide range of construction risk mitigation measures were employed prior to and during the upgrade works. The response to latent conditions and potential dam safety incidents that occurred during construction are described. The continuous adaptation of the construction methodology to suit site conditions encountered during the project is also presented. The project was successfully completed in June 2008. The approach of detailed investigations and design coupled with a strong risk based approach during the construction proved to be effective in managing the dam safety risks of construction work with a full reservoir.
Keywords: earth and rockfill dam, filters, construction risk mitigation, dam safety, dam safety incidents.
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2008 Papers
2008 – Application of procedures for estimation of rock erosion for overflow of dams – illustrated by application to Julius Dam, Queensland
Learn moreEric Lesleighter, Erik Bollaert
Abstract: Many of the dams in Australia, and other countries, are potentially unprotected from the occurrence of extreme floods which would discharge either over the dam and/or the abutments due to inadequate spillway capacity.
The paper commences with the presentation of the evaluation procedure that has been applied by the first author for a number of dams in Queensland, initially with a detailed description of dams, the original hydraulics studies, the current hydrology, and the geological information. The procedure then comprises analysis of the extreme flood hydraulics and an erodibility assessment which leads to an estimate of the possible erosion of the rock for a range of flood magnitudes. A description of the components of the final evaluation and the typical conclusions is presented with reference to the Julius Dam in Queensland.
The paper includes a description of an alternative or complementary procedure that comes from the work of the second author. Comparison is made with the Comprehensive Scour Model (CSM) developed by Bollaert (2002, 2004). This model is physically based and allows estimating scour formation in rock or concrete as a function of time duration of discharge. The model compares the resistance against fracturing of concrete or rock layers with the hydrodynamic pressure fluctuations exerted by a turbulent aerated jet impacting in the plunge area. Once the fracture network is formed, dynamic uplift of single rock or concrete blocks in computed. Based on fracture mechanics and air-water hydrodynamics, a detailed time-evolution of scour formation is obtained. The model is generally used for projects involving plunge pool floors, ski-jump spillways, fractured rock and so on, where sufficient data are available on both rock quality and duration and intensity of spill from the dam. In the present paper, the CSM has been used to model scour of non-overflow abutment sections when there is overtopping flows.
Keywords: dams, spillways, extreme floods, rock scour, erosion, dam safety
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