Richard M Robinson, Siraj Perera, Gaye Francis
SFAIRP (so far as is reasonably practicable) is the ‘modern’ definition of ‘safe’. Shrouded in the legal
concept of the ‘safety case’, it is actually the judicial form of the principle of reciprocity – the golden rule – do unto others, incorporated into the common law by the Brisbane born English law lord, Lord Atkin in 1932.
In dam safety terms, it asks the question; “If you lived downstream of a dam, how would you expect the dam to be designed, operated and maintained in order for it to be considered safe?”
The answer is that it now requires a public demonstration that all reasonably practicable precautions are in place in a way that satisfies the will of our parliaments and our sovereign’s courts, otherwise known as a SFAIRP safety case.
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Reza Asadi, Mahdi M. Disfani, Behrooz Ghahreman-Nejad
Rockfill, a granular material with particle sizes usually in the range of 2 cm to 1 m, is commonly used as the main construction material in a range of civil engineering applications such as water and tailings retaining embankment dams. Rockfill’s complex behaviour mainly stems from its inherently large particle size grading on one hand and its discrete and heterogeneous nature on the other hand. The investigation of mechanical behaviour of rockfill requires expensive and time-consuming laboratory testing in large apparatuses, which are scarce. This highlights the importance of numerical investigation techniques such as Discrete Element Method (DEM) in better understanding of rockfill properties. In this paper initially a concise and comprehensive overview of effective parameters on Rockfill behaviour are presented followed by the discussion on analytical and numerical methods for investigation of the mechanical behaviour of Rockfill.
Finally, a combination of Replacement and Bonded-Particles (clusters) methods is proposed so the effects of particle shape and breakage, which are among the most effective parameters, can be adequately investigated. The preliminary results of DEM modelling are also presented which show a good agreement with the expected micro-mechanical behaviour of rockfill.
Management of dams requires the use of experienced dam engineers and other competent personnel familiar with all relevant basic principles, technical guidelines, articles and manuals. This requires appropriate qualifications, registrations and adequate knowledge and experience relevant to the type of dam and the task required.
Engineering services in Queensland must comply with the Professional Engineers Act 2002 which requires a registered professional engineer of Queensland (RPEQ) to undertake or directly supervise an engineering service. Attributes in addition to RPEQ are recommended for personnel responsible for dam safety management. Inputs are often required from non -engineering technical specialists, such as geologists. Supervising these inputs in the context of meeting the Professional Engineers Act 2002 should be considered.
A matrix of skills for dam safety management personnel has been prepared as part of the Queensland dam safety management guideline and subject to extensive stakeholder feedback in its preparation. The matrix consists of a list of roles typically required for dam safety management and, for each role, a corresponding set of recommended core attributes.
Alberto Scuero, Gabriella Vaschetti, John Cowland
Efficiency in water supply reservoirs, even more so in pumped storage reservoirs, requires good water management and minimisation of water losses. With climate change affecting the quantity of water available for supply and power generation, minimising water losses is becoming more and more crucial, and the most efficient way to achieve this critical objective is to line the reservoir with a watertight geomembrane system. With more than 60 years of use, flexible geomembrane systems have proven to be a dependable technology for new construction as well as for rehabilitation. Efficiency can also be increased by covering the reservoir with a floating geomembrane cover to minimise evaporation losses, and by adding value to the reservoir with the installation of floating photovoltaic panel farms on the surface of the reservoir, to provide or increase electrical power generation. This paper addresses these two aspects of efficiency: water loss minimisation, by presenting concepts and advantages of geomembrane liners, and concepts and application
of floating photovoltaic farms with a case history in a water supply reservoir. The concept of a floating
photovoltaic farm on a pumped storage reservoir, and information on available guidelines for geomembrane systems and floating photovoltaic panels, are also presented.
Christopher Dann, Chad Martin, Garry Fyfe, Nigel Rutherford
This paper presents a case study on remedial works that were undertaken at Lock and Weir One
along the River Murray, that to our knowledge are the first of their kind in Australia.
The weir structure’s left abutment is comprised of a stepped concrete structure founded on timber
piles, with timber sheet piles extending beneath the structure to cut off seepage through underlying
alluvium. A piping incident occurred at the left abutment in late 2014 and a filter blanket was
installed as an emergency response measure. A detailed review of historic construction documents
showed that there was a “missing” timber sheet pile upstream of the piping boil. Geotechnical
investigations, including piezometer installation confirmed the missing timber sheet pile was the
likely cause of the piping incident. A piping risk assessment showed the residual risk of further piping
was reasonably high.
A range of remedial works was considered as permanent risk reduction works. However, these
solutions required extensive temporary works to expose the missing timber sheet pile including a
cofferdam to access the defect and partial demolition of a recently constructed fishway structure.
An alternate Secant ‘Grout Column’ solution was developed that comprised targeted drilling and
backfill grouting to close the gap where the sheet pile was not installed and to grout an inferred void
under the abutment structure. This solution was successful at reducing seepage through the
abutment structure, as indicated by monitoring piezometers.
Mark Pearse, Mark Foster, Peter Hill, Sam Banzi, Muhammad Hameed, Benson Liu
Determining which risk control measures are required is one of the top issues for dam owners as they contend with limited resources generally and capex in particular. The key issue addressed in this paper is how a dam owner can both identify the control measures that they should implement and demonstrate that they are acting reasonably and responsibly. The Framework developed in this paper provides a practical and transparent way to address the relevant matters that are required to be considered under common law, work, health and safety (WHS) legislation and the NSW Dams Safety legislation for determining whether a risk control measure is reasonably practicable. It provides dam owners with a transparent and defensible way of both identifying the controls and demonstrating that they are acting in a reasonable and responsible manner.