The As Low As Reasonably Practicable (ALARP) principle was established in the Australian Dams
community in the ANCOLD Guidelines on Risk Assessment in 1994. Since that time, dam owners have been focused on reducing their societal risk to below the ANCOLD Limit of Tolerability (LoT) through dam safety upgrades and are now considering how to justify an ALARP position. This paper presents a framework that provides a systematic approach to assembling the inputs, applying a process and documenting the outcomes of an ALARP assessment. It is a pragmatic approach that aligns with the safety case, which is a legislated requirement for Major Hazard Facilities in Victoria.
The framework has been applied to two dams in Melbourne Water’s portfolio with differing societal risk, size, uses and criticality to the water supply system. It has highlighted the importance of dam safety governance, documentation of procedures, defensible technical analysis and an ongoing engagement with leading industry practice, in demonstrating risks are ALARP.
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Recent advances in communication technologies have made available an array of new systems and functionalities that dam operators can use to improve automation and centralisation in the daily surveillance tasks of their portfolios. These functionalities include real-time monitoring, target-oriented video surveillance and the remote management of PLCs and data loggers.
The present paper aims to outline some integration possibilities using TCP/IP technologies for remote operations and video surveillance.
The case study features a comprehensive dam instrumentation upgrade, in which the acquisition systems were complemented with a series of IP cameras designed to be triggered by local and remote events.
This paper will explore the differences in pore pressures resulting from saturated and unsaturated seepage (pore pressure) analysis. It will also evaluate some conventional recommendations, such as the inclusion of essential components of the embankment dam and omission of inessential components. In addition, the identification of inessential components will be discussed.
Finally, pore pressures obtained from these analyses will be compared to monitoring data in order to identify the most appropriate seepage (pore pressure) model.
In conclusion, advantages and disadvantages of each method will be discussed and recommendations will be provided in order to gain the most appropriate results.
The results of this paper can be used for designing new embankment dams or safety reviews of existing dams, particularly when there is lack of reliable monitoring data.
The assessment of the geological foundations of arch dams is required as part of the asset owner’s safety obligations (ANCOLD 2003). The task is often made difficult due to steep topography where arch dams are commonly constructed. Between 2013 and 2017, GHD was engaged by South Australia Water (SA Water) to examine the geological and geotechnical conditions of the Sturt River Flood Attenuation Dam (South Australia) abutment foundations. The dam was constructed between 1964 and 1966 within the Proterozoic “Sturt Tillite”. The foundations of the dam are characterised by a folded and fractured rock mass which creates complex spatial relationships between discontinuities and outcrop expression, difficult to assess in two-dimensional space. In collaboration with Monash University’s School of Earth, Atmosphere and Environment, a high resolution ortho-photogrammetric survey of the downstream dam abutments was undertaken using an Unmanned Aerial Vehicle (UAV) in areas where traditional mapping could only be obtained by rope access methods. Monash also undertook digital geological mapping of inferred discontinuities based on the UAV imagery. The data was then used to construct a three-dimensional (3D) model of the shape and position of high-persistence discontinuities, potentially critical to abutment stability. In addition to digital data, a low cost, high value field investigation to “ground-truth” the digital data and reviewed existing geological information (including rope access scanline data, foundation mapping and rotary cored boreholes) to develop a holistic understanding of the persistent discontinuities in their geological context.
Across Australia, recreation usage around dams is growing rapidly. There is also increasing public expectation around the facilities provided and the activities that can be undertaken.
While dams create many benefits, they also have inherent risks associated with them. The risks associated with public access include public and staff safety, water quality, pollution, environmental degradation, bushfires, water availability, dam & power generation operations, and financial.
In 2016 the Victorian government released “Water for Victoria”, a strategy for managing increasingly valued water resources and a growing population. This strategy recognises the importance of recreational enjoyment of waterways and commits water corporations to continuing to maintain infrastructure and facilities to support recreational objectives at their water storages. Water for Victoria also commits water corporations to consider recreational user objectives in the way water storage and supply is managed. However, this must be within legislative requirements to meet the needs of water entitlement holders and with awareness of the realities of dry conditions and climate change.
For the last 10 years, Goulburn Murray Water has been progressively rolling out Land & on Water Management Plans and setting up Land & on Water Implementation Committees. These committees provide a forum for liaison with local government, other statutory authorities, as well as interested environmental, heritage, indigenous, commercial and recreation groups. The groups aim to understand the concerns and requirements of all parties, take appropriate action, which may involve educating communities where some of their desired actions are not achievable.
While this approach has been successful, the growth in social media and the emergence of groups outside of the Land & on Water process has meant that consultation has had to be extended to include self-identifying, special interest groups. This has involved the development of separate groups at Dartmouth and Lake Eppalock to educate and work through the issue at hand, developing appropriate actions, which are accepted and implemented by all parties.
This paper will review the Goulburn Murray Water Land & on Water process, and consider two cases studies, namely the “Save Lake Eppalock” community driven campaign and the provision of fishing access on Dartmouth regulating pondage.
The paper describes the development of UK guidance on reservoir drawdown capacity. The guidance provides for a consistent thought process to be used in determining the recommended capacity. A basic recommended standard is proposed for embankment dams which varies with the consequences of failure of a dam. The drawdown rate for the highest consequence dams is 5% dam height/day with an upper limit of 1m/day. Engineering judgement is used to vary this standard allowing for ‘other considerations’ including the vulnerability to rapid dam failure, surveillance and precedent practice. A different approach is proposed for concrete/masonry dam, which considers the prime purpose of drawdown being to lower the reservoir in a reasonable timeframe to permit repairs rather than rapid lowering to avert failure. The UK approach is compared with that used in Australia and suggestions made for where its use may be appropriate.