2016 – Roads Can Drive Your Risk! A Look at the Importance of Itinerants on Roads in your Consequence Assessments
Peter Woodman, Andrew Northfield, Tim Kallady
Currently there is little guidance available on how itinerants on roads should be included in a consequence assessment. The methods available are often subjective which can lead to itinerants on roads either being ignored or insufficiently considered. A fact that can in turn lead to consequence categories being inappropriately assigned to the asset being assessed or risks being under or over estimated. Consideration of these itinerants is especially important for smaller dams or retarding basins in urban areas where often the Potential Loss of Life (PLL) in buildings is small but there are major roads carrying a large Population At Risk (PAR) through the inundation extent, which experience flooding of sufficient severity to pose a threat to life.
This paper looks at how the method used to assess itinerants on roads can affect the consequence category assigned to an asset and/or the risk of the dam or retarding basin. It will draw on a number of recent assessments undertaken for retarding basins within Melbourne and make comment on a possible approach to consider itinerants on roads in the future.
$15.00
Now showing 1-12 of 46 2980:
Related products
-
$15.00
2016 Papers
2016 – Comparing CRCFORGE Estimates and the New Rare Design Rainfalls
Learn moreJ.H.Green, C.Beesley, C.The, S.Podgerand, A.Frost
The ability to estimate design rainfalls for probabilities rarer than 100 years or 1% Annual Exceedance Probability (AEP) is an essential part of dam hydrology. The earliest means of estimating rare events consisted of a pragmatic curve fitting procedure between the 50 and 100 year design rainfalls and the Probable Maximum Precipitation. In the 1990s a more rigorous method of estimating design rainfalls as rare as 2000 years was developed – the Cooperative Research Centre – FOcussed Rainfall Growth Estimation (CRC-FORGE) method. CRC-FORGE estimates were derived for Victoria in 1997 followed progressively by each of the other states. Over the subsequent two decades CRC-FORGE estimates were an integral part of the risk assessment of large dams – being used to determine the AEP of the Dam Crest Flood.
The Bureau of Meteorology will soon release new rare design rainfall estimates for probabilities to 2000 years. The new rare design rainfalls are a significant improvement on the CRC-FORGE estimates as they have been derived using up to date data; contemporary analytical techniques and a method that is consistent across Australia.
However, there are differences between the CRC-FORGE estimates and the new rare design rainfalls. These differences do not constitute a systematic change to the CRC-FORGE estimates but rather vary with location; duration and probability. The results of a detailed comparison between the CRC-FORGE estimates and the new rare design rainfalls are presented together will an assessment of the possible impacts on previous estimates of the AEP of the Dam Crest Flood.
Learn more -
$15.00
2016 Papers
2016 – Assessing Blasting Impacts on Embankment Dams: Limitations with Adopting an Equivalent Earthquake Approach
Learn moreRobert Harrington
There is a significant body of knowledge in relation to assessing the impacts of earthquakes on earth and rock fill dams which has led to a number of widely recognised and accepted methodologies for the calculation of potential deformations from an earthquake event. However, limited research has been conducted into the assessment of blasting impacts on earth structures. This has led to an adoption of earthquake analysis methods in the assessment of blasting impacts on earth structures without adequate consideration to the difference between the stresses and displacements imposed on an embankment as a result of a blast as opposed to an earthquake. Adopting earthquake analysis techniques may result in conservative vibration limits being imposed when undertaking blasting near embankment dams which may have negative financial impacts.
This paper explores the risks associated with blasting adjacent to earth fill dams and details the difference between stresses and displacements imposed on an embankment by a blast versus an earthquake.
This paper also discusses previously adopted approaches to assessing potential impacts associated with blasting and the limitations associated with adopting a pseudo-static and simplified permanent deformation analysis for blasts modelled as equivalent earthquakes. Finally, the paper proposes an alternate risk based analysis approach.
Learn more -
$15.00
2016 Papers
2016 – Estimating the Maximum Credible Earthquake (MCE) and its Application in Australia and New Zealand
Learn morePaul Somerville
This paper reviews methods used to estimate the MCE in Australia and New Zealand. In the ICOLD (2016), NZSOLD (2015) and proposed ANCOLD (2016) guidelines, the deterministic approach is applicable only to fault sources, whereas the probabilistic approach is applicable to both fault sources and distributed earthquake sources. Although ICOLD (2016) states that the use of a deterministic approach to develop the SEE “may be more appropriate in locations with relatively frequent earthquakes that occur on well- identified sources, for example near plate boundaries,” the proposed ANCOLD (2016) guidelines retain the use of the deterministic approach for critical active faults which show evidence of movements in Holocene time (i.e. in the last 11,000 years), or large faults which show evidence of movements in Latest Pleistocene time (i.e. between 11,000 and 35,000 years ago). In Australia, active faults make a significant contribution to the probabilistic MCE only at near-fault sites, and even in those cases most of the hazard comes from distributed earthquake sources. However, some sites may be close enough to nearby or even more distant identified active faults that a Deterministic Seismic Hazard Analysis (DSHA) produces MCE ground motions that are far larger than those obtained probabilistically even for very long return periods. Conversely, the deterministically defined MCE may be lower than the probabilistically defined MCE for very long return periods at near fault sites in New Zealand, requiring the probabilistic approach.
Learn more -
$15.00
2016 Papers
2016 – Would Bowties and Critical Controls Contribute to the Prevention of High Consequence / Low Frequency Dam Failures?
Learn moreRussell Mills PhD,Rebecca Freeman, Malcolm Barker
The global mining industry lives with the risk of catastrophic events such as water storage or tailings dam failures as part of its daily operations, and has developed a number of approaches to enable mine management to understand the nature of the risks and the ways in which they are being managed. One such approach involves the use of bowties for the understanding of the hazards and risks. Building from bowties, the second approach involves the selection and management of controls critical to the prevention or mitigation of the catastrophic event. The Australian mining industry is a world leader in this regard and the purpose of this paper is to illustrate how bowties are constructed, how risks can be semi-quantitatively estimated, how critical controls are selected and managed, and how, if all this is done well, risks can be demonstrated to be as low as reasonably practicable (ALARP).
This paper sets out key themes and presents an example for a tailings dam failure to illustrate the role of bowties and critical controls in management of catastrophic events. It will also highlight the role of bowties in the anticipated introduction of a Safety Case approach to dam risk management. Bowties provide a useful tool for the transfer of risk management knowledge from the designer, to allow dam owner / operators to better understand their risks and to recognise the link between design and operational controls and how they are used to manage those risks to ALARP.
Learn more -
$15.00
2016 Papers
2016 – Investigation of the Foundation, Sub-surface Drainage and Slab Anchor Degradation of a Concrete-lined Spillway: Fairbairn Dam, Queensland
Learn morePeter Simson, Deryk Foster
Fairbairn Dam is an earth and rockfill embankment dam with an ungated, concrete-lined, spillway, located at AMTD 685.6 km on the Nogoa River, approximately 16 km south of Emerald in Central Queensland.
Following the flood of record in 2011 it was decided to repair a number of areas of spalling concrete which uncovered a collapsed transverse drain and a large void beneath the chute floor. The spillway chute is designed with subsurface drainage system of floor slabs consisting of alternate strips of concrete footing and gravel bed to aid in the control of uplift. The gravel was flushed from under the spillway floor into collapsed earthenware pipes of the drainage system resulting in an unsupported floor slab. Further investigation was carried out using Ground Penetrating Radar (GPR) which identified additional locations of possible voids. Concrete coring was carried out at selected locations to confirm the voids with some being over 250 mm in depth.
Investigation of the sub-surface drains was carried out using CCTV and showed many of the open jointed earthenware collector pipes had cracked and/or collapsed causing the drainage gravel and founding sedimentary rock to be scoured out by spillway flows entering the system through open contraction joints.
Following the discovery of the foundation scouring it was decided to expose a number of anchor bars in the chute floor to undertake a pull-out testing program. Of the ten anchor bars that were exposed, six were found to have corroded completely with the remaining four noted to be partially corroded and subsequently failed under loading.A geotechnical investigation of the foundation materials was planned to determine the condition and strength of the founding sedimentary rock. In addition, the investigation also included sampling of seepage and reservoir waters to characterise the hydro-geochemistry and its contribution to the deterioration of the anchors.
Artesian conditions also occur within the spillway area, driven by the reservoir, with water passing through an extensive network of pervasive defects in addition to permeable flat-lying strata.Coal seam gas is also known to occur, providing a further contribution to aggressive water geochemistry.
Learn more