We can all learn by our mistakes and the experience of others. This paper seeks to look at three
incidents/accidents which recently occurred in the UK so that others can learn from them. The
paper then seeks to answer the question as to whether we are improving in looking after our dams
in the UK in respect of reservoir safety.
We can all learn by our mistakes and the experience of others. This paper seeks to look at three incidents/accidents which recently occurred in the UK so that others can learn from them. The paper then seeks to answer the question as to whether we are improving in looking after our dams in the UK in respect of reservoir safety.
This paper reviews the general principles of duty of care which assist in the understanding of responsibilities that may exist for surveillance of dam safety, including the inter-play of the common law and statutory law. Only when there is a foundation in the general principles can obligations upon dam owners/operators with respect to surveillance and instrumentation be interpreted. Some legal issues around the development and use of industry guidelines are also explored.
Janice H. Green and Jeanette Meighen
The Probable Maximum Precipitation (PMP) is defined as ‘the theoretical greatest depth of
precipitation that is physically possible over a particular catchment’. The PMP depths provided by
the Bureau of Meteorology are described as ‘operational estimates of the PMP’ as they represent the best estimate of the PMP depth that can be made, based on the relatively small number of large events that have been observed and our limited knowledge of the causative mechanisms of extreme rainfalls.
Nevertheless, the magnitudes of the PMP depths provided by the Bureau are often met with scepticism concerning their accuracy when compared to large rainfall events which have been observed within catchments and which are, typically, only 20% to 25% of the PMP estimates. The recent increases in the PMP depths, resulting from the revision of the Generalised Tropical Storm Method (GTSMR), have served only to entrench this cynicism.
However, analyses of the magnitudes of the storms in the databases adopted for deriving PMP depths show that these observed storms constituted up to 76% of the corresponding GTSMR PMP depths and up to 80% of the Generalised Southeast Australia Method PMPs for the storm location. Further, comparisons of the PMP depths to large storms observed in similar climatic regions around the world indicate that the PMPs are not outliers.
The results of these analyses are presented for a range of catchment locations and sizes and storm durations and demonstrate that the PMP estimates provided by the Bureau of Meteorology are reasonable and are not unduly large.
Roger Vreugdenhil, Joanna Campbell
The dams industry is immersed in a changing environment. It is one of many industry sectors in Australia becoming acutely aware of the impacts of ageing practitioners and a competitive labour market. Shortages of skills and labour are impacting on all participants. The constraints around recruitment and retention are further amplified for dam owners in some States by increasing expenditure regulation and accountability.
People choosing to leave or retire from the dams profession per se does not necessarily pose a problem. Instead, problems arise if insufficient transfer of valuable knowledge has occurred prior to their departure, if the rate of replenishment is inadequate to cope with current and future industry workload, and if there is no innovation around what workforce is involved. Future work will likely be characterised by remedial works for existing dams rather than new dam construction, with an increased focus on environmental restoration, and optimisation of operations and maintenance to minimise losses and maximise productivity. These tasks require a great level of skills in leadership and innovation, equal to any level previously applied to this industry.
Organisational goals and decisions have to be realised through people and it appears that many people are taking up their roles differently than in the past. The authors, both Generation X, contend that the core issue is as much a challenge of imagination as it is a crisis of human resourcing. Greater imagination is required around: the image presented by the profession; retention and replenishment of personnel; appropriately connecting people of different generations to their individual roles; developing leaders comfortable with the sentient aspects of organisation life and capable of collaboration; and sustainable management of knowledge.
Joseph Matthews, Dr Mark Foster, Michael Phillips
Pykes Creek Dam is a 39m high earthfill dam with a central clay puddle core, first completed in 1911 and raised in 1930. A detailed risk assessment of the dam indicated that the risk did not satisfy ANCOLD societal risk criteria and that remedial works were necessary to address piping deficiencies and inadequate flood capacity. The risk assessment identified that piping at the embankment/spillway interface accounted for over 80% of the total risk. Therefore, interim risk reduction works were implemented in 2005 to address this risk issue while investigations and design studies were progressed for the second stage of works. Following the Stage 1 works, Pykes Creek Dam remains the highest risk in Southern Rural Water’s portfolio of dams and Stage 2 works are planned to commence in 2007 to reduce piping risks and increase flood capacity. The aim of the Stage 2 works is to reduce the risk below the Limit of Tolerability for Existing Dams (ANCOLD 2003) and to increase the flood capacity to a level more appropriate for an Extreme consequence category dam based on ALARP principles. The upgrade will stop short of meeting the PMF as there are other dams in Southern Rural Water’s portfolio requiring attention before an upgrade to this standard would be considered. The design of the works was complicated by the fact that the dam is bisected by a major freeway and has a complex spillway layout. This paper discusses the decision-making process and the methods used to analyse the dam from the initial risk assessment studies through to the design of the remedial works.