Committee on Cost Savings in Dams
1.1 Since 1950, the annual worldwide investments in dams have been in the range of USD 30 or 40 billion (2008 value) and presently total about USD 2 000 billion.
According to the ICOLD analysis of the Role of Dams in the 21st Century and also present trends, it is likely that this annual rate of investment will continue into the next decades and possibly even increase. Much of this will be in developing countries, possibly reaching over USD 500 billion within the next twenty years.
For reasons analysed below, it is usually difficult to select and optimize designs that correspond to the lowest cost for each dam. The margin of potential cost saving has been estimated as being up to 20% on average (ICOLD Bulletin 73); which would mean a potential saving margin of USD 100 billion in the next twenty years.
This margin is high for dams for the following reasons:
– Local conditions are quite never the same and each dam, built from local materials, requires a tailored design in order to achieve maximum economy.
– There are many variants such as: precise location, general layout, dam type, relevant data, foundation treatment, flood management, specifications, construction programme, care of siltation etc. Furthermore technical progress and economic changes may often warrant new and innovative solutions which are not always considered. In addition, cost comparisons between various solutions may not be easy. Not only will unit prices (for instance for earthfill, rockfill and even concrete) vary for each site, but for a same site they will vary with the factors already listed above. The designer may not be able to easily evaluate the relative impact of all these aspects.
– In most industries manufacturers cooperate with the designer for optimising costs whereas dam contractors are usually not involved in the design phase.
– There is often a keen competition for choosing the Consultant, based on minimizing the cost of his services. This may tend to reduce the cost for the design itself, but there is no competition for choosing and optimising the best design of the dam. This procedure does not favour the cost optimisation of each dam in the same way as competition may be used to minimize the costs for other construction activities such as for buildings, bridges, offshore, tunnels. Furthermore some efficient new solutions are used only when traditional solutions may hardly be used. For example the presently favoured solutions of Roller Compacted Concrete (RCC) or Concrete Faced Rockfill Dams (CFRDs) were technically possible and economically justified in 1960 but were only developed fully some 20 or 30 years later.
– Many designs are based on old design criteria or regulations poorly adapted to present knowledge and to conditions prevailing in those countries where most future dams will be constructed.
In order to help mitigate these drawbacks, ICOLD has focused on Cost Savings through two Technical Committees and these have produced:
– Two general bulletins:
73: Savings in Dam Construction (1989)
83: Cost impact on future dams designs (1992)
– And six specific bulletins:
85: Owners, Consultants and Contractors (1992)
108: Cost of flood control in dams (1997)
109: Dams lower than 30 m high (1997)
110: Cost impact of rules, criteria and specifications (1997)
117: The gravity dam, a dam for the future (2000)
E02: Non structural risk reduction measures (2001)
This represents some 20% of the ICOLD bulletins published in the encompassing 12 years.
In 2005 the ICOLD Chairman appointed an “Ad Hoc Committee on Cost Savings in Dam Design” for “Review of Bulletins 73 and 83 taking in account lessons from Question 84 of Barcelona Congress”. In June 2006, this appointment was approved by the ICOLD Executive Meeting and in the Barcelona Congress, Question 84 (Technical solutions to reduce time and cost in dams design and construction) raised considerable interest, receiving 50% more reports than average Congress questions.
The present Bulletin therefore reviews Bulletins 73 and 83, using lessons from Question 84 and also takes into account the six other specific bulletins on Cost Savings mentioned above. It applies to various dams apart from tailing dams where the problems and solutions are very different.
It is based upon a preliminary analysis of:
– Existing dams.
– Present trends in dam construction.
– Likely future dams and their most usual economical and physical conditions.
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