Peter Hill, Rory Nathan, Phillip Jordan, Mark Pearse
This paper outlines the development and application of the Risk Analysis Prioritisation Tool (RAPT) which has been developed as an interactive tool to aid dam safety risk management. RAPT allows the risk profile and prioritisation of upgrades to be incrementally updated as inputs are refined. The paper outlines some of the requirements of a risk management tool and the resulting functionality of RAPT and the lessons learnt from its application to more than 75 dams.
Issues covered include:
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John D Smart
The paper presents the recent trends in the use of instrumentation and survey measurements at Bureau of Reclamation (Reclamation) dams. The underlying philosophy that has influenced those trends is presented and discussed. Based on experience at Reclamation, several factors that are considered key to the effective use of instrumentation and surveys are discussed. Several conclusions are offered.,
Dr. J. M. Rüeger
After a brief review of the origin and early days of the technique, the present role of geodetic deformation measurements is discussed. The design of geodetic measurement schemes is then considered, followed by a review of geodetic measurement, analysis and reporting techniques. An overview of the important discussions, that need to take place between engineers and surveyors in the design phase, follows. This covers the definition of the engineering needs and the resolution of surveying issues.
C Lake and J Walker
Meridian Energy is the owner and operator of a chain of hydro dams on the Waitaki River in the
South Island of NZ. It operates a Dam Safety Assurance Programme which reflects current best
practice; consequently it has focused primarily on managing civil dam assets. Advances in plant control technology have allowed de-manning of our power stations, dams and canals through centralised control. The safety of our hydraulic structures is increasingly reliant on the performance of Dam Safety Critical Plant (DSCP) – those items of plant (eg water level monitoring, gates, their power and control systems, and sump pumps) which are required to operate automatically, or under operator control, to assure safety of the hydraulic structures in all reasonably foreseeable circumstances.
Recent dam safety reviews have highlighted that the specification and testing of our DSCP is based on the application of ‘rules of thumb’ which have been established through engineering practice (eg. “monthly tests”, “third level of protection”, “backup power sources”, “triple voted floats”). The
adequacy of these engineering practices is difficult to defend as they are not based on published
criteria. The realisation that such rules may not be relevant to the increased demand on, and complexity of, DSCP led us to ask “Which belts and braces do we really need?” The current NZSOLD (2000) and ANCOLD (2003) Dam Safety guidelines give little guidance regarding specific criteria for the design and operation of DSCP.
Meridian has identified the use of Functional Safety standards (from the Process industry, defined in IEC 61511) as a tool which can be applied to the dams industry to review the risks to the hydraulic structures, the demands on the DSCP, and utilise corporate “tolerable risk” definitions to establish the reliability requirements (Safety Integrity Levels) of each protection, and determine lifecycle criteria for the design, operation, testing, maintenance, and review of those protections.
This paper outlines the background to identifying Functional Safety as a suitable tool for this purpose, and the practical application of Functional Safety Analysis to Meridian’s DSCP.
Michael Somerford, Alex Gower
The Water Corporation is the principal dam owner in Western Australian with a portfolio of 95 dams. In the absence of dam safety legislation in Western Australia the Corporation has adopted a policy of self regulation. This paper presents how the Corporation’s dam safety policy has been implemented with respect to dam instrumentation and monitoring. It includes a summary of the type of instruments used and experiences with automated data collection systems. The paper concludes that the Corporation does not see a need for a dam instrumentation guideline, however a document summarising current Australian practices and experiences would be of value.
For many years most emergency management agencies in Australia have used a framework called Prevention, Preparedness, Response and Recovery (PPRR). This approach has worked very well in the past and has been incorporated into the more recent framework of Emergency Risk Management.
While Emergency Management Agencies use practice sessions in the form of Desktop/Tabletop Exercises and Field Exercises as part of Preparedness (the 2nd P in PPRR) these activities can suffer from a lack of engagement with the community.
State Water Corporation, a dam owner in NSW, has installed warning systems to trigger plans written by the SES to warn affected residents of possible dam failure. Although the systems are maintained and tested regularly in a technical sense, the next logical step is to encourage the affected communities to understand their role in the event of evacuation.
A joint exercise involving the NSW State Emergency Service (SES), State Water Corporation and the community, was conducted in a town in the Namoi valley in 2005 and has provided an opportunity to explore this concept. State Water Corporation is now confident that not only will the technical side of the warning system work but that residents should be more aware of their role and that of the SES and State Water Corporation.
Other benefits from the exercise are: the opportunity for improving general flood awareness in the community; the SES identifying community representatives; fine tuning procedures between and within the SES and State Water Corporation; allaying fears within the community about what is required of them in a dam failure; and demonstrating the dam owner’s duty of care to affected residents.