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.
— OR —
Now showing 1-12 of 33 2963:
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.
Dr Judy Henderson
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 for future decision- making. This 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 fulfilling its mandate.
P. J. N. Pells and M. Hunter
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.
Ungated spillways 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 but 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 jeopardy. 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 Africa. Out of experience gained from 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.
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