| Year Published |
ANCOLD Papers |
$AUD |
Add To Cart |
| 1999 |
Dams and the Enviroment - Issues & Guidelines
Author: T. Macoun |
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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. "
Wliy 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. TJiis 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
KEYWORDS: Environmental issues — dams and their storages; environmental assessment and management; water resource management; sustainable performance and management.
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| 1999 |
Introducing and Environmental Management System to a Headworks Business. The Goulburn-Murray Water Experience
Author: G.O'Brien |
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The paper outlines the integration of Environmental Risk Management in Goulburn-Mnrray 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. Tiiis led to a decision to develop and implement an EMS based on the International Standard ISO 14001.
Examination of Goulbuni-Muiray Water activities, associated environmental aspects and impacts, (and the consequences arising), led to the establishment of an environmental risk register. Analysis and assessment of the risks to produce a ranking from low to vety high is described. Refinement to a significant risk register O'igh 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 |
Wingecarribee Reservoir Swamp Failure
Author: K.Arachchi, K.J Lambkin |
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Wetlands by their very nature act as storages of pollutants and nutrients in systems subject to environmental stresses. Wingecairibee Swamp acted in this manner and enhanced the quality of catchment runoff flowing into the Wingecairibee Reservoir until the structural failure of early August 1998 in which 6000 megalitres of peat and sedimentary material were moved into the Reservoir. Protection of the Swamp's functions and values is directly related to Sydney Catchment Authority's core objectives of protecting the environment and protecting public health by supplying drinking water of acceptable quality. Due to the catastrophic failure, water quality in the reservoir and the ecological integrity of the Swamp have been compromised. Tlie incident has also resulted in significant dam safety issues.
This paper describes the dam safety, catchment management and water quality response to the failure of a major peatland which covered 8% of the catchment of Wingecarribee Reservoir in the Southern Highlands of New South Wales.
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| 1999 |
Walla Weir Impact Assessment and Approval
Author: I.C McFarland, I.S Pullar, J.K Roberts, K.Watson |
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The Bui id ah erg Irrigation Area (BIA) is served by a reticulation system of channels, pipelines, pump stations and balancing storages drawing water from a major dam (Fred Haigh on the Kolan River), augmented by a number of weirs and tidal barrages. The scheme as originally proposed in the late 1960's included a major dam on the Burnett River that has never been built. Accordingly, the reliability of the system was lower than desired, a situation exacerbated by prolonged drought during the!990's.
In the 1980s, alternative (cheaper) sources of water supply were investigated and a weir site on the Burnett River (Walla) was selected as the most promising. In 1993, the Commonwealth and Queensland Governments agreed to the Sugar Industry Infrastructure Package (SUP). Walla Weir was included in the Package, subject to environmental and economic assessment.
Detailed impact assessment studies were carried out and submitted to both State and Commonwealth Environment departments. In the light of strong opposition from environmental groups (whose major concern was the Queensland Lungfish), the Federal Minister for the Environment commissioned an independent review of the IAS before granting approval.
Approval was conditional on the implementation of an Environmental Management Plan and a River Operation Plan as well as a commitment to undertake extensive baseline studies before any new development is proposed in the area
This paper will discuss the investigation and approval process and describe the additional monitoring/studies being carried out.
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| 1999 |
Report from the World Commission On Dams
Author: Dr judy Henderson |
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Against a background of several decades of increasingly polarised and acrimonious debate, the World Commission on Dams (WCD) was established in 1998 with a two year mandate to review the development effectiveness of dams, assess alternatives for water resources and energy development and develop internationally acceptable criteria and guidelines forfitture decisionmaking, litis report discusses the role of large dams in development and the challenges of water resource management in the future. T the work program of the WCD is outlined and progress to date on fitlfilling its mandate.
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| 1999 |
Life-Loss Estimation: What Can We Learn From Case Histories
Author: Duane M.McClelland and David.S Bowles |
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There is a growing concern about the limitations of the approaches to life-loss estimation that are currently used in dam safety risk assessment. Tltis 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. Tlie 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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| 1999 |
Small Dam, Big Issues
Author: R.E Saunders |
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The vast majority of dams in Australia are relatively small affairs. For example, approximately 90% of Queensland's referable dams are less than 15 m in height. Most of these dams are owned by small communities, mining companies or farmers, many of which have smaller operations than those of Australia's larger dam owners. In many cases the dam represents the owner's sole source of water supply.
Many smaller dam owners are unaware of the key factors affecting the safety and best management of their facilities. Added to this is a general lack of understanding of dam related issues by the community at large. Tliis often leads to significant owner and community concerns (and conflicts) that have the potential to jeopardise the viability, or worse, the safety of a project. The relative importance of the dam to the smaller dam owner often exacerbates these issues.
This paper serves to illustrate, by way of example, a consultant's viewpoint of some of the issues encountered on small dam projects and suggests actions that the dams industry as whole could take to improve the situation.
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| 1999 |
Finding the Balance: A Community-Led Review Of the Operations Of Hume And Dartmouth Dams
Author: B.Haisman, C.Ballard, N.Garland |
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In early 1997 the Murray-Darling Basin Ministerial Council instigated a review of the operations of its primary resen'oirs, 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. Tlie review, completed in May 1999, achieved a consensus between parties advocating what are on the swface Ureconcilable 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 subsidiaiy 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 offlow parameters which could be viewed as swrogates for environmental outcomes. Conclusions and recommendations are drawn for future reviews of similar dams.
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| 1999 |
Improved Estaimates of Hydrologic Risks for Dams - Impacts of the Flood Guildelines
Author: P.I Hill, RJ Nathan, E Weinmann, JH Green |
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Tlie assessment of flood risk is important to the safe design, maintenance and operation of dams. Traditionally, a standards-based approach has been adopted, in which the adequacy of a spillway was assessed by its ability to pass the whole, or a specified fraction, of the Probable Maximum Flood (PMF). More recently, however, the ANCOLD Position Paper on Guidelines for Selection of Acceptable Flood Capacity for Dams has moved towards a risk-based approach, in which attention is focused on establishing the exceedance probability of the maximum flood that can be safely passed by the spillway.
The move to a risk-based approach has led to an increasing focus on the derivation of floods with very low probabilities of exceedance. Tlie chapter in Australian Rainfall and Runoff that gives guidance on the estimation of extreme floods has recently been revised and issued as Book VI. The new guidelines reflect the move from a standards, to a risk based approach and also include recent developments in extreme flood estimation. T/iese recent developments result in an improved estimate of floods in the large to extreme range and hence a more reliable estimate of hydro! ogic risk.
Tliis paper illustrates the impacts of the new flood guidelines by summarising the results for 7 dams in Southeastern Australia. For the examples presented in this paper the impact of the new guidelines is to reduce the estimated hydrologic risk. The new guidelines have an important effect on the estimation of hydrologic risk and therefore the assessment and management of dams in Australia.
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| 1999 |
Real Time Flood management of the Brisbane river and Pine River Dams during the February 1999 Flood
Author: Peter Allan, Don Cook, garry Grant, John Ruffini |
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The paper examines the performance of the Brisbane River and Pine River real time flood management system for the operation of Somerset Dam, Wivenhoe Dam and North Pine Dam during the 1999 flood event.
The February flood event, which was about 80% of the magnitude of the disastrous 1974 flood event upstream of Wivenhoe Dam, was the first major flood event to be managed by the system and it performed very creditably. The overall flood management system comprises:-
• A network of 125 ALERT type rainfall and river height stations throughout the catchment;
• A data management system to facilitate data collection and data validation;
• Hydrologic models to provide inflows into the dams and major downstream tributaries;
• Gate operation models to route the inflows through the reservoirs; and
• Hydraulic models of the main river channels downstream of the dams.
The paper describes the system and gives details of the performance of the system during the Febntaiy event. It details the performance of the dams during the event and how this was optimised to maximise the safety of the dams and minimise impacts on those dow?istream.
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| 1999 |
Estimating Rare Storms in the Tropics and Sub Tropics
Author: G Hargreaves, R McConnell, J Ruffina |
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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 |
The Application Of Risk Management Principles To Municipal Emergency Management Practice
Author: M Cawood, R Jones, K Durham |
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A methodology for local disaster management planning based on Australian/New Zealand Standard AS/NZS 4360:1995 - Risk Management has been developed as an oat-working of a Flood Risk Study for Murweh Shire. The methodology) has relevance to all local governments, particularly in view of National Disaster Relief Arrangements (NDRA) that now link the extent of NDRA funding available for a re-occurring natural disaster event to the existence of disaster mitigation actions or plans. This places a premium on actions being taken by local governments to mitigate public safety risk at community level.
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| 1999 |
Working with safe Dams
Author: Norm Robins |
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A strategy designed to ensure that an existing dam continues to perform effectively will include:
• a set of operating instructions.
• maintenance of the reservoir components.
• an ongoing review of structural performance.
• a system to indicate the appropriate application of resources.
• the ability to respond to an incident.
This paper will explore each of these issues and how they may be applied to dams in a variety of situations. These situations include water supply reservoirs, flood retarding basins, levees and wastewater lagoons. While each situation is different, the underlying principles will remain consistent. The range of situations encountered by Victorian Water Authorities provides the inspiration for the development of an efficient approach to the management of the safety of dams.
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| 1999 |
A Dam Improvement Program - An Owners Perspective
Author: S McGrath, M Cowan |
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GouIburn-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-hWhas 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 cuirent 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 |
Judged Values and Value Judgements in Dam Risk Assessment
Author: D Hartford |
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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 ofjudgement in risk evaluation, the process ofjudging 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 |
Dam Safety in a Corporate Environment
Author: A Moulds, G Meinck, C Elliot |
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This paper describes the experiences of a fanner 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 darn safety. Key elements in this process were:
• Setting up a high le\>el steering committee, comprising key stakeholders, to manage a darn safety program.
• Clarifying accountabilities for darn custodianship and technical support.
• Fully implementing the recommendations of the ANCOLD darn safety management guidelines, with its implications for documentation of procedures, frequency of darn 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 darn 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 |
Remedial Work on Cotter Dam and the Risk to these from Floods
Author: J Tabatabaei, C Zoppou |
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Cotter Dam was constructed in 1912 to 19m and was raised to 31m in 1949. Due to its close proximity to a popular recreational resort, it is considered as a high hazard dam. It forms a storage with a capacity of only 4500ML and receives flows from a catchment area of 482km2. Concern about the ageing and structural integrity of Cotter Dam was expressed as early as 1967. There has also been a major revision of the Probable Maximum Flood (PMF) and new earthquake requirements for the dam. All these factors have contributed to the decision to undertake remedial works on the dam. The remedial work could be interrupted by flows over the spillway. This would increase the cost of the works because the construction equipment must be removed and reinstated (de/remobilisation) when there are flows over the spillway. Additional costs are also incurred for each day the construction equipment remains idle (standby). The total tender price therefore includes the cost associated with the remedial work as well as any standby and de/remobolisations. Risk analysis was used to establish the frequency the reservoir water level exceeds the spillway level. The risk analysis was used to select the successful remedial works tender.
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| 1999 |
Almo Dam Demonstration Risk Assessment
Author: DS Bowles, LR Anderson, JB Evelyn, TF Glover, DM Van Dorpe |
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A demonstration risk assessment was conducted on the 283-foot high rolled-earthfill Alamo Dam as part of a U.S. Anny 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 |
Warragamba Dam Auxiliary Spillway Design
Author: SR Knight, B Cooper, R Van Breda |
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Warragamba Dam was completed in 1960 and impounds Sydney's main water supply storage. Hydrological studies in the 1980's showed the existing spillway to be significantly undersized by modem standards. Considering the dam's High Incremental Flood Hazard category, the current risk of dam break is unacceptably high. This has resulted in a two-stage program to upgrade the dam to full Probable Maximum Flood (PMF) capability.
The interim (first stage) measures were completed in 1990 and involved a 5.1 metre raising of the dam crest and significant post-tensioning of the dam wall. Following many feasibility/option studies and detailed technical and environmental studies, a contract was let by Sydney Water Corporation (SWC) in late 1998for the construction of an auxiliary spillway as the major (second stage) component of the flood security upgrading. The spillway will be a large capacity (about 18,000m3/s) concrete lined chute 700 metres long around the dam's right abutment. In the upper curved section will be the largest fuse plug embankments in Australia (up to 14.5 metres high). The lower straight section will terminate with a flip bucket structure.
Tlie NSW Department of Public Works and Services (DPWS) designed the earlier Interim Works, undertook the subsequent engineering option studies for the Major Works and carried out the concept design and technical specification for the new auxiliary spillway and associated dam modification works. This paper summarises the project, describes the main features of the concept design of the spillway and outlines the associated dam modifications
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| 1999 |
Full Scale Testing of a 2400 Tonne Capacity Rock Anchor
Author: BA Cavill |
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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 modem 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 |
Karipiro Dam - Stability Investigations and Enhancement Works
Author: J Walker, M Gillon, J Grimston |
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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 cany 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 |
Empirical and Mathematical Methods of Designing Granular Dams Filters
Author: B Indraratna, M Locke, G Adikari |
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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 pariicle size ratios have been used. These empirical rales 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 |
Investigations on Canning Dam Concrete Gravity Structure and its Rehabilitation
Author: A Shayan, RE Wark, J Waters |
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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 |
Recent Practices in the Construction of Roller Compacted Concrete Dams
Author: R Parker |
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This paper examines the current trends in the construction of Roller Compacted Concrete Dams in Australia and Internationally. Certain recent trends to processes such as grout enriched vibratable RCC will assist both the cost effectiveness and simplicity of this type of dam constmction. Key issues considered are:
1. The trend is to use less conventional concrete in the structure and grout enriched RCC against contact swfaces are the means of achieving this.
2. Proportionally greater use is being made of high paste mixes
3. In order to maximise placing rates, keep it simple
4. Aggregates should be manufactured in not less than three sizes and preferably four if segregation is to be controlled
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| 1999 |
Construction of the Balambano Dam, Indonesia
Author: A Day, R Bridges, C Fabbri |
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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 528,000m3 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, aggi-egate sources, RCC mixes and waterproofing (membrane).
After early problems with the river diversion, the works were accelerated and completed to a veiy 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 |
Towards Acceptance of totally Automatic Spillway Gates
Author: P Townshend |
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Ungated spillway's offer the safest form of spillway but they are more costly than gated spillways for the volume of water stored. Gated spillways offer a more cost-effective use of water by maximizing the storage capabilities of the dam. Gated spillways also lead to more cost effective new dams as well as increasing storage of existing dams. They can therefore offer considerable advantages bat must not jeopardize dam safety. Most commonly used spillway gates are mechanically driven by electric or hydraulic systems reliant on external power supply and instrumentation, and usually require operators to control the systems. Unfortunately there is already a substantial record of these types of gates not operating when required, thereby placing the dam's safety in jeopard}'. The ideal is to have automatic gates which do not suffer the problems associated with mechanically-driven gates.
A number of automatic gates exist, some with differing degrees of success but most are not truly automatic in operation and suffer some limitations. A range of fully automatic water control equipment has been developed and has operated for more than 20 years in South Afiica. Out of experience gainedfrom this equipment, a new generation of spillway gates has been developed which meets nearly all the requirements of an ideal spillway gate.
This paper introduces the gates and examines their features and safety devices. Other benefits are also mentioned.
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| 1999 |
Remedial works to the Upstream Face Protection of Megget Dam, Scotland
Author: D Gallacher, RM Doake, D Hay-Smith |
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Damage to the rip-rap protection on the upstream face of Megget Dam has occurred since first filling in 1983 and independent wind-wave investigations have demonstrated that waves exceeded anticipated wa\>e heights. Value Planning Studies for alternative schemes to upgrade the rip-rap protection indicated that bituminous grouting was the preferred option and its satisfactory performance was proved by site trials during May 1997. Tlie bituminous grouting works were carried out in two stages with a break over the winter season. Tfte upper pari of the face was completed over a 12 week period (September to early November 1997) and the grouting works for the remaining area was completed over a 24 week period (mid April to early October 1998).
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| 1999 |
Dam Safety Management Using The Asset Safety Evaluation Tool in the Hydro Electric Corporation Tasmania
Author: P Quinland, S Guidici |
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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 |
Kinta RCC Dam - Are over simplified thermal-structural analyses valid?
Author: AJ Crichton, I Benzenati, TJ Qui, JT Williams |
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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 - stnictural 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 stnictural 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 |
Lightning Protection For Dam Instrumentation - A case study of the new Victoria Dam
Author: A Moulds, AM Watson |
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The selection of lightning protection equipment will always remain within the cost versus benefit, or risk management area. As more and more monitoring equipment becomes electronic and microprocessor based, we need to have a better understanding of the ways to protect it, and maintain the data flow.
Recent experience has shown that utilising the Australian Standard (NZS/AS J768-J99J) Lightning Protection, in conjunction with a six-point plan, will go a long way to providing total integrated protection for both structures and contents. However, no matter how much protection is applied, damage due to lightning may still occur. For dam surveillance instrumentation the aim ultimately is to protect the transducer 'in the ground' or 'in the dam', because generally these instruments are inaccessible and non-replaceable without prohibitive drilling and retrofitting costs.
Tlie six-point plan was applied initially to designing lightning protection for a large, well-instrumented RCC dam, completed in 1991. The protection proved to be not as good as was hoped. The paper describes how the lightning protection at the dam was subsequently developed. This experience, which has pointed the way to achieving a good level of protection at a reasonable cost, has been applied to a number of other, instrumented dams.
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| 1999 |
Stresses & Deflections in Concrete Dams
Author: A Khan, A Patnaik |
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Concrete dams are thinner than embankment dams and impose more concentrated loads on the foundation and abutments. A narrow valley with sufficient rock foundation is a typical site for concrete dam, which require a solidfoundation that is relatively free of faults, shears, and major changes in foundation strength. Such discontinuities can overstress the concrete by causing some areas of dams to cany more loads than other areas. The measurement of deflections and use of finite element technique can predict the stresses in the concrete dams. A computer model is underdeveloped for prediction of deflections and stresses in Concrete Dam by using finite element. At the first stage of this study, measured deflections from Buirinjuch Dam are compared with the predicted deflections by using finite element. Tins paper outlines the deflections measured in the dam due to temperature variations and comparison of the measured thermal deflections with those predicted from a finite element analysis
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| 1999 |
Sustainable Development in Large Hydro Power Generation
Author: A Stephen |
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Among the major energy options, Large Hydro Power is considered to be the front ranking and renewable. But, in most of the developing countries including India, the large multipurpose dam projects are shrouded in controversies.
This paper, while dealing with positive and negative impacts of large multipurpose dam projects, focuses on 'Social Impact Assessment'and its mitigatoiy measures, for the success of the project. The Environment cost as well the Human cost of such projects should be judiciously integrated in the project cycle from its conception to its post implementation stage, for sustainable development of this power regime.
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| 1999 |
The Kelian Waste Storage Dam for the prevention of acid rock drainage
Author: PJN Pells, M Hunter |
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The potential for generating acid leachate from waste dumps is a major consideration in many metalliferous and coal mines. This paper describes the construction of the highest embankment dam in Indonesia for the sole purpose of storing potentially acid producing waste under water. The paper discusses the features of embankment dam design peculiar to an open pit mining environment which involves moving more than three times the total volume of earth and rock than in the whole of the Snowy Mountains Scheme.
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| 1999 |
Using Contracts for Life Cycle Risk Management of Dams and other Infrastructure Assets
Author: DC Green |
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Contracts are usually thought of as documents which set out the respective legal obligations of the contracting parties. If the focus is changed, however, away from closing legal loopholes to the use of contracts to achieving project management objectives, then, among other things, contracts may be drafted as an integral part of the risk management plan for particular infrastructure assets.
In this paper, where the emphasis is on dam projects, the principles of risk management Are applied to contracts for construction, maintenance and surveillance and outsourced technical advice, thereby covering issues over the whole life cycle of the asset. The principles are then broader issues ofproject procurement. Such as selection of contractor, contract packaging, .clauses within the contract and administration of the contract.
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