This paper outlines lessons learned from 8 years of regular operations and testing of 111 gates at 22 sites. It points out that the implementation challenges involved are not only technological in nature, but also encompass human factor and organizational issues. This is perhaps understandable since the initiative is part of the cultural shift to sustain gate reliability long-term.
An increase in gate testing frequency has led to the identification of more performance anomalies, ranging from deficiencies to operational failures. This finding may not be unique to a single dam owner. It leads to the following question to the general dam owner community: Are we testing our gates enough?
Now showing 1-12 of 39 2978:
A C Mostert, D J Hagen, P C Blersch
The changes in flood operations since the 2006 flood, covering weather monitoring, hydrological flood station monitoring, and downstream monitoring, are discussed in detail in the paper.
Stephen Newman, Rod Jacobs, and Dr John Yeates
Independence Group (IGO) is assessing the feasibility of re-commissioning a closed copper-zinc mine in Victoria. Due to the acid producing potential of the mine tailings if exposed to oxygen they are to be contained in a saturated condition not only during the life of the mine but well beyond closure and effectively in perpetuity. The tailings are to be stored in a saturated condition underground in the mining void however due to the limited volume available approximately half of the tailings produced over the mine life will require containment in a purpose built surface Tailings Storage Facility that would need to perform as a water retaining structure.
This paper describes key challenges with tailings management including demonstrating the viability of maintaining permanent saturation of the tailings and the long term integrity of the structure. Excessive poor quality seepage, piping and other failure modes have also been considered in the long term design of the closed Tailings Storage Facility. A surveillance program to provide early identification of potential issues has also been developed.
The design is consistent with ANCOLD guidelines and used a risk based approach to assess key issues associated with the extended design life.
William Ziegler and Heather Middleton
This paper presents the collation of over 20 years of data on vertical and horizontal movements around Cataract Dam in the Southern Coalfield of New South Wales, reporting subsidence that continues 25 years after extraction in the area ceased. The occurrence of increased vertical movement over old goaf areas as the result of extraction in the same seam at greater than 1km distance has been observed. Together with a change in the behaviour of measured head of water 6 years after extraction ceased in the area. These points raise the question, how long should subsidence monitoring continue after extraction has ceased in areas of important infrastructure?
Michael Ashley and Robert Wark
The construction of service reservoirs has been an integral part of the development of water supply systems throughout Western Australia, and many such developments have occurred in coastal regions. The porous and highly soluble limestone foundations that are found in coastal regions pose specific challenges and risks for the long term management of these structures. Minimising leakage rates has been traditionally driven by economic losses. However, it has become apparent that the leakage has caused long term structural damage to the foundations of the structures.
Based on four case studies from south west Western Australia, this paper describes the extent of the problem, investigation and testing methods, design challenges and construction issues to be considered when constructing water storages on porous foundations.
Przemyslaw A. Zielinski
Three aspects of the current engineering practice in using event trees in dam safety risk analyses are discussed in the paper. These aspects include assignment of probabilities for initiating events, treat-ment of dependencies in the event tree, and dynamic aspects of dam system behaviour and accounting for time. The paper discusses limitations of the methodology and common mistakes in engineering applications of event tree methods when assessing dam safety risks and making safety decisions for specific dams. Of particular importance is the discussion of incorrect interpretation of dependency structure when addressing common cause failure modes.