Papers
Papers are made available through the website 12 months after they are presented at the annual conference. Please add to your shopping cart to purchase and you will receive a link to download.
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A CD can be purchased containing ANCOLD Bulletins from 1961 to 2001 on the OTHER PUBLICATIONS page.
If there is a paper you require prior to 2007 that has not been uploaded please contact the secretariat [email protected]
Use the search below using keywords, year or author.
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2016 Papers
2016 – Upcoming New National Seismic Hazard Assessment of Australia – Improvements & Novel ideas
Learn moreVicki-Ann Dimas
The National Seismic Hazard Assessment 2018 (NSHA 18) project intends to revise the existing seismic hazard map (AS1170.4 2007) for Australia. Geoscience Australia (GA) are leading the project along with a consortium of seismologists, geologists and earthquake engineers.
The NSHA 18, due to be released in 2018 is of great importance to dam owners and operators. The project intends to incorporate a comprehensive approach to seismic hazard, particularly in modelling uncertainty and variability.The Global Earthquake Model (GEM) is an international consortium of scientists, engineers and policy makers. One of the primary aims of GEM is to provide a uniform set of tools for analysis in seismic hazard and risk. GEM was established to provide a framework for global standards in comparing risk analysis, awareness and actions in an effort to increase resilience to vulnerable communities.
The NSHA 18 will use the GEM framework in order to meet its own objectives for the new upcoming hazard map. The Seismology Research Centre will contribute to the NSHA 18 in three areas. Firstly, to produce a unified earthquake catalogue where GA will homogenise magnitudes to a uniform scale. Secondly, to produce a number of applicable alternate seismotectonic models, and thirdly, through the contribution of ground motion data collected over the last forty years within Australia.
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2016 Papers
2016 – An Earthquake Alarm and Situation Awareness Tool Developed For Areas of Low to Moderate Seismic Hazard: Recent Developments and Past Results
Learn moreWayne Peck
The SRC operated seismic network is one of the largest privately owned and operated seismic networks in the world. Importantly it bridges the situation awareness gap between the information often provided by national seismic networks, of earthquake magnitude and location, and the emergency response managers questions of “What effects will this event have on my assets?” together with “What should we now be doing to mitigate the event?”
Software development of the Quick Quake app and improved automation of PDF report generation means that detailed, bespoke client specific earthquake response reports that incorporate asset earthquake resistance and failure consequence aspects can be produced by duty seismologists within reduced timeframes.
Preliminary earthquake locations computed by the SRC operated network for the two ML 4.7 Korumburra events in March 2009 and the ML 5.6 Moe earthquake of June 2012 were significantly closer to the final computed locations than those published by any other authority. The network additionally provides bonus outcomes of highly accurate detailed seismic activity maps that reduce uncertainties for Probabilistic Seismic Hazard Assessments (PSHAs) and attenuation data that will be used to develop regional specific ground motion models.
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2016 Papers
2016 – Comparing CRCFORGE Estimates and the New Rare Design Rainfalls
Learn moreJ.H.Green, C.Beesley, C.The, S.Podgerand, A.Frost
The ability to estimate design rainfalls for probabilities rarer than 100 years or 1% Annual Exceedance Probability (AEP) is an essential part of dam hydrology. The earliest means of estimating rare events consisted of a pragmatic curve fitting procedure between the 50 and 100 year design rainfalls and the Probable Maximum Precipitation. In the 1990s a more rigorous method of estimating design rainfalls as rare as 2000 years was developed – the Cooperative Research Centre – FOcussed Rainfall Growth Estimation (CRC-FORGE) method. CRC-FORGE estimates were derived for Victoria in 1997 followed progressively by each of the other states. Over the subsequent two decades CRC-FORGE estimates were an integral part of the risk assessment of large dams – being used to determine the AEP of the Dam Crest Flood.
The Bureau of Meteorology will soon release new rare design rainfall estimates for probabilities to 2000 years. The new rare design rainfalls are a significant improvement on the CRC-FORGE estimates as they have been derived using up to date data; contemporary analytical techniques and a method that is consistent across Australia.
However, there are differences between the CRC-FORGE estimates and the new rare design rainfalls. These differences do not constitute a systematic change to the CRC-FORGE estimates but rather vary with location; duration and probability. The results of a detailed comparison between the CRC-FORGE estimates and the new rare design rainfalls are presented together will an assessment of the possible impacts on previous estimates of the AEP of the Dam Crest Flood.
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2016 Papers
2016 – Dam Safety Management for Upgrade of an Extreme Consequence Storage
Learn moreMark Arnold, Gavan Hunter and Mark Foster
Following the dam safety risk assessment for Greenvale Dam in 2008, Melbourne Water implemented a 3.0 m reservoir level restriction on the operation of the storage as an interim risk reduction measure. The 3.0 m restriction coincided with the ‘as constructed’ top of the chimney filter in the main embankment. This interim action reduced the dam safety risk to below the ANCOLD limit of tolerability.
Dam safety upgrade works were undertaken in 2014/15 to bring the dam in-line with current risk based guidelines and to enable the removal of the interim reservoir restriction, bringing the storage back to full operating capacity. Greenvale Dam was required to remain operational throughout the works and this required careful consideration of the dam safety risk during construction.
Deep excavations were required within the crest and downstream shoulder of the embankments, that,, without adequate management, had the potential to increase risk to the downstream population. Excavations up to 18 m depth were required into the wing embankments for construction of full height filters from foundation to crest, excavations up to 7 m deep were required in the main embankment to expose and connect into the existing filters and secant filter piles up to 13 m deep were used to connect the new chimney filter of the wing embankments with the original chimney filter of the main embankment.
A key element of the design and construction of the upgrade works was managing dam safety during construction. Dam safety considerations included (i) design based decisions to manage the level of exposure; (ii) implementation of further restrictions on reservoir level by the owner Melbourne Water; (iii) construction methods to manage exposure; (iv) an elevated surveillance regime during the works and (v) emergency preparation measures including emergency stockpiles and 24 hour emergency standby crew. The construction based dam safety requirements were focused on early detection and early intervention, and were managed via the project specific Dam Safety Management Plan.
This paper focuses on dam safety management including the decisions made, actions taken and construction requirements and touches on how these relate to the key project features.
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2016 Papers
2016 – Design Considerations for the Stortemelk Hydropower, South Africa
Learn moreBJ Rochecouste Collet, PC Blersch, AL Olivier
The paper shows how multidisciplinary engineering can create future-proofed solutions for dam management and how innovation is bringing those advancements to life. It includes the retrofitting of a small hydropower station to an existing dam structure, enhancing the use of the dam. The paper also reveals design, technical and project finance considerations underpinning the multi-disciplinary services.
Water supply in South Africa’s economic hub of Gauteng journeys from the Lesotho Highlands Water Project (LHWP) through three river systems that converge in to the Vaal Dam from which the water is treated and pumped for domestic usage. One of those systems delivers water originating in Lesotho to discharge into the Ash River. The Ash River was, by origin, a small river with an environmental reserve flow of 50 l/s. However, with the LHWP significantly adding flow, the annual average increased to 24,500 l/s (24.5 m3/s) and is set to increase further with future phases of the scheme. To mitigate significant erosion caused by the greatly increased flow, several structures were erected along the river, including the Botterkloof Dam. Whilst the energy was dissipated in the dam’s spillway, a private developer studied if the water could be used for energy generation. The river also offered some rapids some 1.6 km downstream, which also showed potential for hydropower generation. An option to combine the two sites was also considered.
Aurecon conducted the feasibility study in 2010 for both sites, including the combined option, which concluded that there would be significant benefits in the implementation the projects in two separate schemes. This boasted many advantages including reduced capital investment, reduced social impact (canoeist), reduced geotechnical risks, and lesser land acquisition leading to a better return on investment. Aurecon are currently providing engineering, procurement and construction management (EPCM) services for the entire project. Construction of the 4.4 MW hydropower station commenced construction in September 2014 and was commissioned ahead of time and under budget.
The founding conditions under the proposed hydropower station location, comprising interbedded sandstone and mudstone was fairly poor with the mudstone effectively decomposing in less than two days. The Botterkloof dam was build on a thick layer of sandstone which dips quite steeply towards the right bank. The right bank on the other hand comprises an old paleo channel. The Boston A dam, located on the left bank immediately adjacent to the Botterkloof Dam, is founded on the weather mudstone and the spillway is grass lined. The power station construction was constructed in the narrow space in between the two existing dams – the Botterkloof Dam (owned by the Department of Water and Sanitation (DWS), Government of South Africa) and the adjacent privately-owned Boston A Dam. Permission had to be obtained from the respective owners and all regulatory permits approved before the project could be submitted to the South African Renewable Energy Independent Power Producer Programme (REIPPP) implemented by the Department of Energy (DoE) of the South African Government.
Another significant challenge in the construction itself included the need for deep excavations through the left embankment of the Botterkloof Dam and adjacent to the spillway stilling basin whilst such construction needed to be done without affecting operations and stability of either of the two dams.
The solution was a shallow intake, followed by a cut and cover concrete penstock leading to a compact hydropower station housing a single 4.4 MW vertical “Compact Axial Turbine” Kaplan turbine ending in the tailrace, which was rotated at 90 degrees.
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2016 Papers
2016 – Seismic Assessment and Life Extension for the Mahinerangi Dam
Learn moreRobert Shelton, Jako Abrie, Matt Wansbone
The Mahinerangi dam – arguably the most valuable in Trustpower’s portfolio of 47 large dams – is over 80 years old and needs a plan of work to confirm it meets current design standards.
The dam was completed in 1931, subsequently raised in 1944-1946, and strengthened with steel tendon anchors in 1961.
A comprehensive safety review (CSR) in 2007 noted a potential deficiency in the fully grouted anchors and a program of work commenced to re-evaluate the overall stability of the dam.A potential failure mode assessment revealed that the dam may need upgrading to meet the criteria for maximum design earthquake (MDE). Areas of uncertainty were identified and a significant programme of survey, geological mapping, concrete testing and site specific seismic assessments have been carried out to reduce risk and uncertainty in design.
The paper discusses the dam’s history, current condition, and describes the ongoing programme of work planned to extend the life of the dam for another 80+ years.
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2016 Papers
2016 – Kangaroo Creek Dam Embankment Raising and Stabilisation – Balancing Competing Objectives
Learn morePeter Buchanan, Malcolm Barker, Paul Maisano, Marius Jonker
Kangaroo Creek Dam located on the Torrens River, approximately 22 km north east of Adelaide, is currently undergoing a major upgrade to address a number of deficiencies, including increasing flood capacity and reducing its vulnerability to major seismic loading.
Originally constructed in the 1960s and raised in 1983, recent reviews have indicated that the dam does not meet modern standards for an extreme consequence category dam.
The original dam was generally constructed from the rock won from the spillway excavation. This rock was quite variable in quality and strength and contained significant portions of low strength schist, which broke down when compacted by the rollers. The nature of this material in places is very fine with characteristics more akin to soil than rock. Review of this material suggests that large seepage flows (say following a major seismic event and rupture of the upstream face slab) could lead to extensive migration of the finer material and possible failure of the embankment. However, it is also envisaged that the zones of coarser material could behave as a rockfill and therefore transmit large seepage flows, which may result in unravelling of the downstream face leading to instability.
This paper addresses the design of the embankment raising and stabilising providing suitable protection against both these possible failure scenarios, which tend to lead to competing solutions. The final solution required the embankment to be considered both as a CFRD and a zoned earth and rockfill embankment.
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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:
- 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 legal advices
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2006 Papers
2006 – Meeting the Challenges of Tomorrow, Today – Human Resources – A Changing World
Learn moreKaren Soo Kee
Strategic resource management has never been more important than it is today with the aging of the “baby boomers” and their ongoing exodus from the workforce. The vacancies they leave in professions such as engineering are just beginning to be felt and will exponentially escalate over the next few years. Specialised professions such as dam engineering and related professions will be hit the hardest as the knowledge and skills learnt over decades are depleted.
The lack of skilled staff and in fact the lack of interest of young engineers in entering the dam industry is one of the critical challenges for today. How do we attract professional staff into the field of dam safety before the exodus creates a “black hole” that can never be filled? And how can we ensure the knowledge transfer from existing skilled staff to newer staff to retain expertise within the industry?
Another issue for resource management is that tomorrow’s workers, the “X &Y generations”, will be unlike the current and previous generations of workers. These workers will be less likely to have a mortgage, will have fewer children and be more interested in lifestyle, not career. They will be extremely confident, well-educated and very mobile. The future will be a sellers market. The challenge here will not only be to attract and recruit talented workers but also to retain them.
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2016 Papers
2016 – Paradise Dam – An Analysis of Severe Damage to a Modern Dam
Learn moreDavid Scriven, Lawrence Fahey
Paradise Dam is located approximately 20 km north-west of Biggenden and 80 km south-west of Bundaberg on the Burnett River in Queensland. The dam was designed and constructed under an alliance agreement with construction completed in mid 2005. It is a concrete gravity structure up to 52 m high, the primary construction material being roller compacted concrete (RCC).
In January 2013 the flood of record was experienced at the dam with a depth of overflow on the primary spillway reaching 8.65 m following heavy rainfall in the catchment from ex-tropical cyclone Oswald. The peak outflow was approximately 17,000 m3/s. This equated to a 1 in 170 AEP flood event. When the flood receded it was discovered that the dam and surrounds had suffered severe damage in a number of locations including: extensive rock scour downstream of the primary dissipator and the left abutment, damage to portions of the primary dissipator apron, and the loss of most of the primary dissipator end sill.
SunWater initiated a staged remediation program to manage the dam safety risks and by November 2013 had completed the initial Phase 1 Emergency and Phase 2 Interim repairs. Phase 3 of the program was to implement a comprehensive Dam Safety Review (DSR) and a Comprehensive Risk Assessment (CRA). The DSR became arguably the largest ever undertaken by SunWater and included: extensive geotechnical investigations, large scale physical modelling, numerical scour analysis, stability analysis, and an extensive design assessment. This paper describes some of the key aspects of the DSR undertaken related to the flood damage.
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2016 Papers
2016 – Hedges Dam – Upstream Face Slip from Rapid Drawdown and Subsequent Remedial Works
Learn moreDavid Laan, Kim Matsen
A slip on the upstream face of Hedges Dam was observed during an annual site inspection in late March 2016. At that stage the slip appeared to be largely contained within the right hand third of the embankment.
By early April, the slip area had developed into a head scarp across the entire central portion of the embankment. Multiple other head scarps were observed, indicating multiple or segmented slips. Several tension cracks were also visible on the face of the dam. The toe of the slips was indicated by a poorly defined bulge.
The most recent drawdown of the reservoir level was identified as a potential driver for the initiation of the slip failure. During the most recent drawdown the maximum drawdown rate was approximately 0.6 m/day whereas in the previous 17 years the maximum drawdown rate was approximately 0.2 m/day.
The remedial works proposed are to place a rockfill weighting zone on the upstream face to stabilise the embankment. The strength of the materials along the sheared surface was back calculated from the mechanics of the failure surface. This data was then used to calculate the shape of the weighting zone required to stabilise the slope.
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2017 Papers
2017 – Public Safety Around Dams: Best Practices for Barrier & Signage Placement at Water Control Dams & Hydroelectric Powerplants
Learn morePaul S. Meeks
In June 2008 a young girl kayaking at a hydroelectric control dam owned by Alcan in Quebec Canada, tragically drowned when she was swept through the open spillgates. The public safety boat barrier, installed the year before, failed to prevent this accident. In June 2015, Stephen Hembree took his daughter and 7 of her friends out for a pontoon boat ride on Lake Linganore to celebrate her 16th birthday. A short time later, Mr. Hembree was dead while his daughter and her friends were be rescued by helicopter as they clung to boulders in the spillway. Contrast these incidents to one in March 2017, when the public safety boat barrier installed by Alliant Energy at Kilbourn Dam was credited with preventing the loss of life after a woman fell into the river above the dam. What went wrong in the first 2 instances and what can we learn from the third incident? What steps can dam owners take to prevent accidents like these from happening?
The first two incidents represent preventable loss of life at a dam while the third incident proves how a proactive approach to public safety results in reduced liability for dam owners and lower loss of life. In the Alcan instance, the public safety barrier installed to prevent this very scenario was instead installed in a location that doomed the girl even before she set her kayak in the water. The second instance demonstrates how a dam owners lack of risk awareness coupled with a boat owners carelessness resulted in a fatality.
Using the incidents above, this presentation, modeled after the Canadian Dam Associations Guidelines for Public Safety Around Dams, will educate owners and operators how to identify “dangerous” zones above and below dams. We will consider the effects of surface water velocity of individual survivability and barrier effectiveness. Flow-3D models will be shown to illustrate the effect of barrier alignment and velocity to increase an individual’s ability to “self-rescue”. Lastly, we will integrate within the presentation practical guidelines for the use of signage, sign size, lettering height and message consistency. The presentation will conclude by examining lessons learned in the Alcan incident and presenting how a proper public safety barrier and signage plan would be implemented.
More people have died from accidents around dams than have died from dam failures. The Canadian Dam Association published its guidelines in 2011 and the result has seen a significant reduction in fatalities and injuries as a result of recreating around Canadian Dams. The United States Society on Dams (USSD), the Association of State Dam Safety Officials (ASDSO) and the Federal Energy Regulatory Commission (FERC) all have embarked on efforts, modeled in large part around the CDA Guidelines to bring Public Safety out of the dam safety toolbox so Public Safety is viewed as a separate managed system. This is being conducted in an effort to educate and alert dam owners, operators and recreational users to hazards and risks in and around dams.
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