Neeta Arora, Prashant Agrawal, Yogendra Deva, Ravi Kumar
The tectono-lithologic complexities and the accompanying extreme mass wasting processes make the Himalaya a difficult terrain for river valley development projects envisaging dams and other diversion structures. Besides exceptionally thick riverbed deposits leading to management of deep foundations, abutting the dams often poses challenges in view of difficult ground conditions. The paper looks at three scenarios where the presence of highly decomposed strata, slumped mass and unconsolidated riverbed material led to serious problems in abutting the dams and invariably delayed the project completion. The design approach to special abutment issues is discussed in the light of investigations, explorations, laboratory and field tests, etc. In conclusion, while dependable engineering geological mapping and assessment is considered the backbone, innovative investigations and engineering play crucial role in successful implementation of projects.
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Now showing 1-12 of 14 3380:
Shane McGrath, Mark Arnold, Josh Rankin, Gavan Hunter
Greenvale Dam is a critical storage for the supply of potable water to Melbourne. The dam had been upgraded through current risk management techniques, and an ALARP assessment completed at that time. However, it was decided that a more comprehensive demonstration of ALARP was warranted to satisfy the dam owner’s duty of care. Since there is no comprehensive guidance in the dams industry for owners and their advisors to reference, the safety case approach used extensively in other hazardous industries was adopted. Considering the approaches used by Victoria’s Worksafe, the Institution of Engineers Australia and the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA), the key components of the safety case for Greenvale dam were identified then developed to provide a logical, structured and comprehensive argument for the safety of Greenvale Dam. This paper provides an overview of components of the safety case developed for Greenvale Dam, the use of safety cases for dams and where process improvements could be made.
James Thorp, Ryan Singh, Jiri Herza
Responsible management and operation of tailings and water storage facilities comprises a series of activities and projects that must be delivered within the commercial realities of the organisation and operation context of the facility owner. All projects are constrained by several variables, which are commonly represented by the Project Management Triangle of Scope, Time, and Cost. These variables are often finite and mutually exclusive, and delivery of the required outcome is accomplished by successfully managing each variable. The activities (variables) associated with the long-term dam safety are sometimes omitted to meet the immediate project requirements. In addition, the commercial realities, such as a selected project delivery model, can have a significant impact on dam safety risks through the allocation of risk, ability of the key decision makers, and the undue commercial pressures applied by each project delivery model. This paper presents several case studies where the project and commercial realities have led to decision making that impacted dam safety and increased the risk presented by the storage facility. While the immediate impact of these decisions may appear to be minimal, all stages of a tailings or water storage facility’s life span are impacted. This paper presents learnt lessons with the aim to prompt both owners and consultants to reconsider their commercial processes and project delivery strategies and limit unforeseen risks to the safety of tailings or water dams.
Hench Wang, Peter Hill, Sam Banzi, Muhammad Hameed
Dam owners can often struggle to demonstrate the dam safety risk benefits that can be achieved through non-structural risk reduction measures, such as adoption of smart technological solutions that improve the timeliness and quality of decision making. WaterNSW collaborated with HARC to develop a novel way of demonstrating benefits from improved data management. This paper discusses the use of HEC-LifeSim to demonstrate the reduction in life safety risk from improved monitoring through DamGuard for a case study dam in Sydney. DamGuard is a real-time dam safety monitoring system implemented by WaterNSW. This case study was the first time in Australia where a simulation model such as HEC-LifeSim was applied to quantify the life safety risk benefits pre and post the implementation of DamGuard. The implementation of DamGuard to the sample dam was estimated to reduce the life safety risk by 15%.
Andrew Northfield, Peter Hill, Muhammad Hameed, Hench Wang, Sam Banzi
In 2018 WaterNSW undertook a Portfolio Risk Assessment (PRA) for 20 dams across the greater Sydney area.
This paper describes the estimation of consequences for this large and diverse portfolio of dams. For some dams the population at risk were greater than 100,000 people whereas for others there were no permanent PAR which required the careful consideration of itinerants. This diversity of the dams required that the approach for estimating the consequences be tailored to the specific characteristics. For example, the approaches for estimating the potential loss of life (PLL) varied from a detailed simulation model (HECLifeSim) to a simpler empirical approach (Reclamation Consequence Estimation Methodology (USBR, 2014) to bespoke consideration of itinerant campers and users of walking tracks. For some dams the economic costs were driven by direct infrastructure costs whereas for other the indirect costs dominated the total economic cost for failure.
Richard M Robinson, Siraj Perera, Gaye Francis
Due diligence has become endemic in Australian legislation and in case law, to the point that it has become, in the philosopher Immanuel Kant’s terms, a categorical imperative. That is, our lawmakers seem to have decided that due diligence is universal in its application and creates a moral justification for action. This also means the converse, that failure to act demands sanction against the failed decision maker.
This applies to dam safety management which represents the archetypical high consequence – low likelihood event. It is now essential to have positively demonstrated safety due diligence in a way that can withstand post-event judicial scrutiny. Presently the only way this can be done is by using the notion of criticality and precaution, not hazard and risk. The test is not that of risk acceptability (as low as reasonably practicable or ALARP), rather it is that no further reasonably practicable precautions (so far as is reasonably practicable or SFAIRP) are available, and that what results is not prohibitively dangerous.
This paper will document the difference between the two approaches and how to positively demonstrate safety due diligence. It also discusses the definition of ALARP as stated in ANCOLD’s Guidelines on Risk Assessment 2003 and the relevance of the safety case principle for dam safety management.