1999 – Dams and the Environment – Issues and Guidelines
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 – Dam Safety in a Corporate Environment
Learn moreGarry 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 – Sustainable Development in Large Hydro Power Generation
Learn moreA. Stephen
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, Jocuses on Social Impact Assessment’ and its mitigatory 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
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1999 Papers
1999 – Warragamba Dam Auxiliary Spillway Design
Learn moreS. Knight, B. Cooper and P. van Breda
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 modern standards. Considering the dam’s High Incremental Flood Hazard category, the current risk of dambreak 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 1998 for 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 18,000m*/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.
The 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 Papers
1999 – Kinta RCC Dam – Are Over-Simplified Thermal – Structural Analyses Valid?
Learn moreAllan 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 – Small Dams, Big Issues
Learn moreRobert E Saunders
The vast majority of dams in Australia are relatively small affairs. For example, approximately 90% of Queensland’ 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. This 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.
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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.