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.
— OR —
Now showing 1-12 of 37 3483:
Lindsay Millard, David T Roberts, Steven Cox, Andrew Berghuis, Anna Hams
Addressing historical impacts of waterway barriers on regional fisheries values is a major focus for fisheries regulators when assessing proposed water infrastructure projects such as dam safety improvements. To inform prudent investment decisions, it is essential to quantitatively determine the feasibility and benefits of various fish passage options to mitigate barrier effects. In Queensland, the regulatory frameworks require consideration of multiple options to achieve mitigation with the overarching goal to support and restore regional fish productivity. Addressing multiple objectives on large water infrastructure projects can be challenging, particularly for existing assets requiring retrofit solutions. There is a need to balance the requirements for dam safety, water supply reliability, while also mitigating the loss of fish habitat access upstream of barriers. Finding optimal fish passage solutions requires consideration of multiple options and using objective approaches that can weigh up the many aspects. The best solution may not always be the most obvious. Here we describe an approach that addresses multiple objectives through a novel off-site solution that provides increased benefit to the impacted fish community. Seqwater, Queensland,
The approach involved weighing up various fish passage options, informed by stochastic hydrologic
modelling to produce a range of probabilistic scenarios. 120 years of modelled water levels and discharges from the study site and the broader catchment, enabled an evaluation of the benefits and dis-benefits of different options in relation to dam safety, water supply reliability and fish migration opportunities. Inputs to the assessment process included fish habitat availability and migratory needs, capital and operational feasibility considerations. Numerous modelling scenarios were produced to assess a range of possible solutions, both on and off-site, to provide an objective weighting of the relative strengths of each scenario.
In this instance, while an onsite option could be feasibly engineered, it would be costly and given the
hydrology of the system, would operate so infrequently as to provide limited opportunities for fish passage and minimal regional fisheries productivity benefits. The optimal solution found was to provide fish passage on a higher order stream within the same catchment area that has impacted fish migration and access to upstream habitats for the same fish community. This option improves fish habitat access to a larger proportion of the catchment and over a wide range of flow conditions, thus providing greater regional fisheries productivity outcomes.
Our method demonstrated an objective approach to balancing multiple project objectives for dam
improvements. The use of hydrologic modelling combined with fish migration and habitat information, found an optimal solution for regional fisheries productivity goals, while also balancing the dam safety and water supply reliability goals.
David Reid, Andy Fourie, Riccardo Fanni, Cristina Vulpe, Alexandra Halliday
Recent failures of a number of tailings storage facilities (TSFs) has highlighted the need for better
governance and operational management of these structures. One means to improve their safety is clearly better and more focussed monitoring. Significant efforts are underway in this area, with a number of technologies being deployed. In particular, the monitoring of deformations through a variety of means (direct, satellite inferred) is increasingly being applied. While deformation monitoring to warn against failure has a long history in geotechnical engineering, some aspects of the rapid triggering and resulting flow of some TSFs may not be amenable to deformation monitoring, in the sense that actionable warning of an impending failure is not assured.
To examine this issue, a series of numerical models of an idealised TSF are carried out. This idealised TSF is brought to failure by means of a rising phreatic surface – often referred to as the constant shear drained (CSD) stress path. Deformations of the outer slope and crest of the numerical model – i.e. those that could be monitored for a real TSF – are tracked and analyses for the models carried out. It is seen that under CSD loading distinct deformation patterns indicative of impending failure are not always clear. Rather, minimal deformations and indeed swelling of the crest is seen leading to failure. The importance of recognising the minimal pre-failure deformation patterns that may manifest with a rising phreatic surface is noted.
T. I. Mote, N. Vitharana, L. Johnstone, and K. Illangakoon
In Australia, the consideration of faults in seismic design has been captured in recent ANCOLD Guidelines for Design of Dams and Appurtenant Structures for Earthquake. The Guidelines recommend proper characterisation of geologic setting, foundation conditions, seismotectonic setting, and identification of both active and neotectonic faults as input to the seismic design basis for dams in Australia.
A case-study is presented at the proposed Cultana Pumped Hydro Energy Storage Project in South
Australia, summarising a fault assessment in concert with reference design. The progressive assessment of a lineament to a possible active fault to ultimately a non-seismogenic fault, allowed insights in understanding active fault rupture risk and active fault implications as it pertains to siting a dam in Australia. It highlighted the need for proper characterisation of geologic setting and faults based on targeted geotechnical investigations and the challenges in phasing these with an aggressive design program. These insights are relevant to many other projects in Australia either in existence or being planned for construction.
Richard Mannix, Michael Cawood, Joseph Matthews, Siraj Perera
Guidance material available to dam owners both domestically and internationally on testing dam safety emergency plans (DSEP) and running exercises is relatively general in nature. Guidance specific to dams that assists owners to design risk informed exercise scenarios tailored to their dam(s) total risk profile and the broader context in which the consequences of dam and operational safety failures would materialise, is limited.
This paper presents a framework that guides dam owners through a progressive scenario development process that enables the systematic identification of both dam and operational safety matters that require exploration as part of DSEP exercising. This level of rigour in guidance material has, until now, been missing and is particularly relevant in the context of dam owners demonstrating due diligence and SFAIRP imperatives while also bringing dam safety management closer to achieving the safety case.
David Stephens, Phillip Jordan, Peter Hill, Tim Craig, James Woolley and Bill Hakin
As part of the design of a proposed new hydropower dam (the Alimit HPP), on the island of Luzon in the Philippines, design flood estimates have been prepared using a RORB Monte Carlo approach for events up to and including the Probable Maximum Flood. Compared with Australia, the Philippines is a relatively data sparse environment, with limited rainfall gauge records and even fewer streamflow gauging stations. As such, considerable effort was required to derive design rainfall inputs for Monte Carlo simulation, including rainfall depths as well as temporal and spatial patterns.
This project made use of a number of remotely sensed data sets, including 20 years of global half hourly gridded rainfall data from NASA and global gridded estimates of rainfall intensity-frequency-duration. As part of the project, these data sets were benchmarked against local records from Luzon as well as selected Australian data sets.
This paper sets out the process used to determine design flood estimates in the Philippines, as well as summarising the usefulness of these new data sets for potential application in data sparse regions of Australia.