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Shane McGrath and Michelle Cowan

Goulburn-Murray Water (G-MW) is a Victorian rural water authority with responsibility for management of the major water systems within a 68,000 square kilometre region. Following a detailed business risk assessment undertaken in 1996, Goulburn-Murray Water developed a ten-year program to commence design reviews and address identified deficiencies at thirteen dams for which G-MW has responsibility.

In October 1997, the Victorian Government announced a $450 million regional water reform package, of which $35 million was provided for rural water authorities dam improvements. $18.5 million was allocated to G-MW on a ‘dollar for dollar’ basis. With contributions from G-MW customers, the current total funding amounts to $37 million.

This paper focuses on processes that G-MW has adopted to manage an accelerated program of dam design review and remedial work.

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1999 Papers

1999 – A Dam Improvement Program – An Owners Perspective
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Shane McGrath and Michelle Cowan

Goulburn-Murray Water (G-MW) is a Victorian rural water authority with responsibility for management of the major water systems within a 68,000 square kilometre region. Following a detailed business risk assessment undertaken in 1996, Goulburn-Murray Water developed a ten-year program to commence design reviews and address identified deficiencies at thirteen dams for which G-MW has responsibility.

In October 1997, the Victorian Government announced a $450 million regional water reform package, of which $35 million was provided for rural water authorities dam improvements. $18.5 million was allocated to G-MW on a ‘dollar for dollar’ basis. With contributions from G-MW customers, the current total funding amounts to $37 million.

This paper focuses on processes that G-MW has adopted to manage an accelerated program of dam design review and remedial work.
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1999 Papers

1999 – Alamo Dam Demonstration Risk Assessment
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David S. Bowles, Loren R. Anderson, Joseph B. Evelyn, Terry F. Glover and David M. Van Dorpe

A demonstration risk assessment was conducted on the 283-foot high rolled-earthfill Alamo Dam as part of a U.S. Army Corps of Engineers (USACE) Research and Development program. The existing dam and 19 structural risk reduction alternatives were evaluated for flood, earthquake and normal operating conditions. The paper summarizes the risk assessment process, results, findings and recommendations. It also provides an evaluation of the risk assessment process and recommendations for better positioning the USACE to use risk assessment for dam safety evaluation and decision support.
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1999 Papers

1999 – Construction of the Balambano Dam, Indonesia
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Andrew Day, Rod Bridges and Corrado Fabbri

A joint venture between Astaldi SpA of Italy and Thiess Contractors Pty Ltd of Australia (ATJO) has just completed a 95m high roller compacted concrete (RCC) dam on the island of Sulawesi in Indonesia. The dam which includes 528,000m’ of RCC was completed in September 1999 and will provide hydro-electric power for a nearby nickel smelting operation.

One of the largest RCC dams built in the region in recent times, the construction presented a number of unique challenges in particular placing techniques to cope with the heavy rainfall in the area as well the logistics to this remote location. Other aspects which are addressed in the paper include production rates, RCC placing systems (Rotec), dam formwork systems, aggregate sources, RCC mixes and waterproofing (membrane).

After early problems with the river diversion, the works were accelerated and completed to a very tight program. To enable dam construction to commence prior to river diversion the wall was advanced as a series of separate monoliths which led to a number of RCC placing innovations.
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1999 Papers

1999 – Dam Safety in a Corporate Environment
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Garry Meinck, Chris Elliott and Tony Moulds

This paper describes the experiences of a former state statutory authority in the almost four years since it became corporatised to form a water utility with a fully commercial orientation and with a new board of management with a clear awareness of the responsibilities of corporate governance.

The need to commit to major remedial work at one of the principal dams focussed the Board’s attention on the safety status of all of the Corporation’s 56 referable dams.
In the absence of external dam safety regulation the Corporation has moved to satisfy its corporate governance responsibilities by adopting current best practice in dam safety. Key elements in this process were:
- Setting up a high level steering committee, comprising key stakeholders, to manage a dam safety program.
- Clarifying accountabilities for dam custodianship and technical support.
- Fully implementing the recommendations of the ANCOLD dam safety management guidelines, with its implications for documentation of procedures, frequency of dam inspections, formal safety reviews and contingency planning.
- Communicating the dam safety risk issues to the Board, which has become fully aware and actively interested in the dam safety program.
- Adopting a policy of early risk reduction aimed at clearing up all known significant dam deficiencies within seven to ten years. The Board has approved in principle a program of capital expenditure potentially amounting to some $150 million over the next seven years,
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1999 Papers

1999 – Dam Safety Management using the Asset Safety Evaluation Tool in the Hydro Electric Corporation Tasmania
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Peter Quinlan and Sergio Giudici

The Hydro Electric Corporation (HEC) owns and manages 54 large and referable dams across Tasmania. Monitoring, data storage and data utilisation techniques have evolved significantly over the years as the dams have aged and as instrumentation, communication and data management technologies have advanced. This paper describes the development of the HEC’s ‘Asset Safety Evaluation Tool’ (ASET) for acquisition, management and interpretation of data relating to dam safety management. The paper also provides examples of how ASET has been applied within the HEC to demonstrate how the primary functional development goals of robustness and practicality have been achieved.
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1999 Papers

1999 – Dams and the Environment – Issues and Guidelines
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T.W. Macoun

ANCOLD Environmental Guidelines have been under preparation for a considerable time. A brief for their preparation followed a resolution by the ANCOLD executive in 1991] that:
“ANCOLD should be seen by the profession and the community as a credible and informed source of information on the risks and benefits associated with dam projects.”

Why the guidelines were initiated, why they have taken the time they have to prepare and what they cover are described in this paper.

To the author’s knowledge, they are the only guidelines of their type, addressing the environmental effects of dams and associated works. It is hoped that they generate substantive debate. This paper initiates the public comments phase.

The paper has two purposes:
° = To introduce the guidelines ° To use the guidelines to introduce this environmental issues session of this conference
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1999 Papers

1999 – Empirical and Mathematical Methods of Designing Dam Filters
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Buddhima Indraratna, Mark Locke and Gamini Adikari

The main objectives of the filter are to prevent erosion of the dam core, permit controlled passage of seepage flow through the dam and facilitate dissipation of excess pore pressures in the core. In most designs of dam filters, empirical methods based on particle size ratios have been used. These empirical rules are developed through extensive laboratory tests. Although the empirical rules benefit from directly or indirectly incorporating most factors affecting filtration, they cannot be extrapolated for distinctly different soils and do not describe the time dependent changes that occur within the filter medium.

Mathematical models can be formulated to explain the fundamental physics of particle interaction and migration, within a framework of well defined geohydraulic constraints. Considering the mass flow and momentum conservation principles; time dependent changes in particle size distributions, mass flow rates, retention capacity and base soil erosion rates can be simulated.

This paper reviews various empirical and mathematical models, based on the authors experience. A novel approach to large scale filtration is highlighted based on testing actual soil and filter materials from an Australian dam, in a new 500mm diameter apparatus.
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1999 Papers

1999 – Estimating Rare Storms in the Tropics and Sub-Tropics
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Gary Hargraves, Russ McConnell and John Ruffini

The acceptance of the use of generalised methods for estimating extreme rainfall has resulted in a growth of the Probable Maximum Flood (PMF) estimates that spillways of dams are required to pass. In many cases spillways were not designed with spare capacity and are incapable of safely passing the new PMF estimates. Dealing effectively with the potential for dams to cause damage and loss requires a risk management approach. Such an approach requires more reliable tools for estimation of rainfall. This paper examines the issues, the progress made, and outlines further work and options for clarifying risk.
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1999 Papers

1999 – Finding The Balance – A Community-led Review of the Operation of Hume and Dartmouth Dams
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Brian Haisman, Clarke Ballard and Neville Garland

In early 1997 the Murray-Darling Basin Ministerial Council instigated a review of the operations of its primary reservoirs, the Hume and Dartmouth Dams, in response to concerns of floodplain communities below the dams, coupled with changing community values in relation to the in-stream environmental effects of dams. The review, completed in May 1999, achieved a consensus between parties advocating what are on the surface irreconcilable objectives for the management of the water resource. Foremost competing objectives were flood mitigation, consumptive water use, and environmental health of the river system, plus subsidiary objectives related to recreation, hydro-electric generation, salinity management, tourism and the like. The keys to success were firstly, creation of a community-based Reference Panel which took on a steering role coupled with extensive consultation, and secondly a determination to describe situations wherever possible by means of factual information. The paper describes the identification and evaluation of issues, the consensus building process, the intensive hydrology and economic modelling undertaken, and the development of a comprehensive set of flow parameters which could be viewed as surrogates for environmental outcomes. Conclusions and recommendations are drawn for future reviews of similar dams.
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1999 Papers

1999 – Full Scale Testing of the 2400 Tonne Capacity Rock Anchor
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Brian Cavill

Canning Dam is a mass concrete curved gravity structure 466m long and 70m high and is a primary peaking source for the Perth Metropolitan water supply system.

A safety review of Canning Dam concluded that the existing structure does not possess adequate margins of safety under static and dynamic loadings using contemporary dam engineering practices. Given the location and strategic importance of the Canning source, it is imperative that the dam be upgraded to comply with moder standards.

After investigation of alternative remedial measures to strengthen the dam, a permanent post- tensioned anchoring system was chosen.

Of the total of 165 permanent, monitorable and restressable ground anchors to be installed, 70 will consist of 91 x 15.2 mm strands. These are the highest capacity anchors to be installed anywhere in the world. A proving test for this size of anchor was carried out by VSL in September 1998. The results of the test confirmed that the use of 91 x 15.2 mm strand permanent anchors is feasible and that the corrosion protection is assured.
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1999 Papers

1999 – Introducing an Environment Management System to a Headworks Business – The Goulburn-Murray Water Experience
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Gordon O’Brien

The paper outlines the integration of Environmental Risk Management in Goulburn- Murray Water with previous work on Dam Safety, Business and Occupational Health and Safety risks. This has now been followed by the development of an Environmental Management System (EMS) to provide an environmental risk management framework for the whole Authority.

An Environmental Audit in 1997 identified deficiencies in some areas of environmental management and questioned the Authority’s ability to demonstrate due diligence. This led to a decision to develop and implement an EMS based on the International Standard ISO 14001.

Examination of Goulburn-Murray Water activities, associated environmental aspects and impacts, (and the consequences arising), led to the establishment ofan environmental risk register. Analysis and assessment of the risks to produce a ranking Jrom low to very high is described. Refinement to a significant risk register (high and very high risks), and consolidation into a list of generic risks based on major activities, functions and asset categories is described.
Based on this risk profile for the Authority, the Environmental Policy and Objectives were revised, and a methodology for identifying Environmental Targets was developed. Environmental Risk reduction is then delivered through the implementation of target driven Environmental Management Programs (EMPs).

Major system elements described include an emergency response plan, a legal register, an authority / responsibility matrix, a document control system, procedures, forms, training, auditing, and reporting.

The paper describes some of the practical issues encountered and the lessons learned with a focus on the activities of the Headworks Business. A prospective view of implementation and culture change issues is given.
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1999 Papers

1999 – Investigations on Canning Dam Concrete Gravity Structure and it’s Rehabilitation
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Ahmad Shayan, Robert J. Wark and John Waters

The Canning Dam concrete gravity structure located in Western Australia has shown an upward movement of 18.3 mm and lateral upstream movement of 14.2 mm over the past 15 years of monitoring. These movements have been associated with considerable cracking of the upper parts of the dam and the upper gallery. Investigations have shown that the cause of the cracking was a strong alkali-aggregate reaction (AAR) in the concrete, brought about by a deformed granitic rock. Extensive horizontal and vertical cracking in the upper part of the dam wall has necessitated the removal of the section above the floor of the upper gallery level, and construction of a new reinforced concrete section to act as head beam for post-tensioning of the rest of the dam wall.

A set of small diameter cores were taken from the various parts for diagnostic purposes, and a vertical core of 100 mm diameter was taken through the whole thickness of the wall for the determination of the strength properties, alkali content and residual expansion potential. Based on these, a post-tensioning stress of 1.5-2.0 MPa has been calculated for restraining the residual expansion of the concrete. The spillway bridge structure which is part of the dam wall has also shown mild signs of deterioration. The piers and abutment walls and the deck were surveyed for corrosion activity and extent of AAR. This work showed that the spillway bridge structure was sound and only needed maintenance. The performance of a triple blend concrete mix containing a high volume of fly ash (45%) and silica fume (5%) developed for the replacement of the old concrete is also discussed.
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1999 Papers

1999 – Judged Values and Value Judgements in Dam Risk Assessment – A Personal Perspective
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D.N.D. Hartford

The role of judgement in risk assessments as applied in dam safety management has been the source of considerable debate in recent years. With regard to risk analysis of dams, and while there is general agreement that judgement is an essential element of the process, essentially two schools of thought have emerged. One view holds that, in the assignment of probabilities, reliance can be based on collective engineering judgement that is anchored to a knowledge base. The second view holds that judgement should be based on the knowledge that is revealed by an appropriate amount of analysis. The paper, written from the perspective of the latter view, explores some of the underlying issues in this debate.

The role of judgement in risk evaluation, the process of judging the significance of risk, is considered to be equally important. However, the process of making value judgements and statements of principles is complex and often beyond the sphere of engineering. The third issue addressed in the paper concerns the search for answers to the question, “How good is the assessment?”
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1999 Papers

1999 – Karapiro Dam – Stability Investigations and Enhancement Works
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Jim Walker, Murray Gillon and John Grimston

Karapiro Dam is at the end of a cascade of hydropower dams on the Waikato River in New Zealand’s North Island. The 52m high, high hazard, arch dam retains the lake for a 96MW power station at its downstream toe. Safety reviews recommended a re-evaluation of the dam stability under seismic loading.

Dam owner, Electricity Corporation of New Zealand (ECNZ), commissioned consultants Tonkin & Taylor Ltd to carry out a series of studies and investigations which provided better understanding of the dam’s safety status. Investigations located a previously unrecorded continuous low strength thrust fault underlying the left abutment. This provided the potential for movement of the left abutment gravity blocks under earthquake loading, with adverse effects on arch dam and reservoir safety. Investigations showed the abutment cut off walls to be lower than the PMF lake level. High groundwater levels and erodible pumiceous soils were found at the left abutment. These findings prompted ECNZ to implement stability enhancement works.

This paper describes the studies and investigations, peer review process, and design and construction of enhancement works.
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1999 Papers

1999 – Kinta RCC Dam – Are Over-Simplified Thermal – Structural Analyses Valid?
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Allan J Crichton , Ikhlef Benzenati, Tony J Qiu and Jon T Williams

The Sg Kinta Dam is a 90 m high Roller Compacted Concrete (RCC) gravity dam and is expected to be the first RCC dam in Malaysia when construction commences in 2000. The dam is part of the development of the Ipoh Water supply on mainland Malaysia. A thermal – structural analysis has been completed as part of detailed design using ANSYS finite element analysis software to assess the effect of the heat of hydration of the RCC on resulting structural stresses. The effect of using simple linear elastic material properties on the calculated stresses has been compared to more complex time variant material modulus and creep analyses. From these comparisons it is shown that the simple models overestimate initial stresses and underestimate or cannot predict the long term tensile stresses.
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1999 Papers

1999 – Life-loss Estimation: What Can We Learn from Case Histories?
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Duane M. McClelland and David S. Bowles

There is a growing concern about the limitations of the approaches to life-loss estimation that are currently used in dam safety risk assessment. This paper summarises insights into factors that affect evacuation effectiveness, loss of life, and survival, based on a detailed review of historical dam breaks and other types of floods. The understanding and empirical characterisation of life loss dynamics being developed from these case histories are intended to provide the foundation for an improved practical life-loss estimation model.
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