Stuart Richardson,Tusitha Karunaratne
Goulburn-Murray Water (G-MW) manages 16 large dams across Northern Victoria. Since January 2010 after 10 years of continuous drought a number of significant and historic maximum floods were passed through some of these dams. Although these floods are not considered extreme in a dam safety context, for downstream communities they presented very real emergency situations. There has been significant community concern regarding the impact of the floods resulting in several inquiries.
G-MW has maintained and annually reviewed comprehensive Dam Safety Emergency Management Plans (DSEP) since 1997. During 2009 G-MW began developing and documenting a systemised approach to dam’s management, operation and emergency response by developing and integrating its Operations and Maintenance Manuals, Flood Incident Management Plans and Dam Safety Emergency Management Plans. The plans have been developed to align with the Australian Inter Service Incident Management System (AIIMS) which G-MW uses as its corporate incident response framework.
This paper provides an overview of the benefits of having structured and integrated manuals and response plans for managing assets, flood and extreme events. The paper also shares G-MW’s experiences in developing this integrated management approach.
Workshop paper – Karunaratne 2011 – Management of Floods in 2010 and 2011 through Goulburn-Murray Water Dams
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Mark R. Sinclair & Richard J. Rodd
Over the last six years there have been ongoing significant developments in the design, fabrication and particularly of the corrosion protection details for high capacity ( >13,500kN MBL ) re-stressable ground anchors used to improve stability of gravity dams. These Australian based developments and the resultant specifications and details have now become the de-facto standards adopted.
The ANCOLD Register dams to have had this generation of cables installed have included; Ross River Dam, Lake Manchester Dam, Catagunya Dam, Tinaroo Falls Dam and Wellington Dam. These projects include the highest capacity permanent ground anchors installed to date worldwide. Some smaller capacity anchors installed into dams have also benefited from this technology.
The Recent Developments and Application of Large Ground Anchors for
Amanda Ament, Jon Williams, Malcolm Barker
Aplins Weir is located on the Ross River in Townsville, downstream from the Ross River Dam. Previous work had identified Aplins Weir as exhibiting factors of safety below 1.0 under normal operating conditions, with over 1000 persons at risk today in the event of failure. Originally constructed in the early 1920s, Aplins Weir has been upgraded and repaired following various failures on a number of occasions. The end result is a complex reinforced concrete and steel sheet pile composite structure reliant for stability on a number of unreliable components. This paper presents the historical data describing the current configuration of the weir, and the analyses required to evaluate the extisting structure, leading to the design of the proposed upgrade works. The final design involves a retrofit of large diameter cast-in-place lined piles and a heavily reinforced base overlay slab designed to completely bypass all existing vulnerable substructure elements.
2011 – Where is our Weir going – an Unusual Upgrade!
The large flood inundating areas of Brisbane and Ipswich along the lower Brisbane River below Wivenhoe Dam in January 2011 was extensively reported by the media. An independent Commission of Inquiry was formed soon after the flood with broad terms of reference including matters related to dam operations. Prior to the Inquiry hearings and findings, reporting in the media continued and made strong allegations of blame of the flood on dam operations. The media relied on limited expertise but the articles were portrayed and subsequently re-produced by other media outlets as ‘expert’ analyses. The author’s interpretation is that media claims were misleading and damaging to the public confidence in the role of dams for flood mitigation, and this damage occurred before official Inquiry findings were available.
A brief summary is presented of now publicly available credible reports on the flood event, and a summary is also presented of the key matters and allegations reported in the media related to the dam operations. An analysis and commentary of media reporting on the flood operations of the Wivenhoe Dam is presented in the context of time and people with reference to information and expertise available to the media, and media conduct in relation to fair public interest and professional practice.
Matters of importance for objective and informed knowledge of key technical matters in relation to operation of dams, dam safety, and the inevitable extremes of nature and floods are discussed. The paper then examines the roles and possible limitations of dams engineering professionals in relation to media reporting of such matters.
This paper solely focuses on matters of media examination of the floods and dam operations, and generally does not comment on technical matters that are in the terms of reference of the Commission of Inquiry.
2011 – January 2011 Brisbane River Floods and Examination by Media of the Dam Operations
Mojtaba E. Kan and Hossein A. Taiebat
Abstract: The simplified procedures for evaluation of earthquake induced displacement in earth and rockfill dams are widely used in practice. These methods are simple, inexpensive, and substantially less time consuming as compared to complicated numerical approaches. They are especially recommended to be used as a screening tool, to identify embankments with marginal factor of safety, assuming that these methods always give conservative estimates of deformation. However recent studies show that application of these methods may not be conservative in some cases, especially when the tuning ratio of a dam is within a certain range. In this paper the fundamental theory behind the simplified methods is critically reviewed and practical guidelines are presented that can be used to identify cases where the simplified procedures may not be conservative.
2011 – Reliability of simplified methods for evaluation of earthquake-induced displacement in earth and rockfill dams
Conrad Ginther, Colleen Stratford
The Wyaralong Dam Alliance (WDA), a consortium of seven engineering and contracting companies, was contracted to design and construct the Wyaralong Dam, which impounds the Teviot Brook 14 km from Beaudesert in Queensland, Australia. The dam is an approximately 500 metre long, 48 metre high Roller Compacted Concrete (RCC) structure built on a foundation generally consisting of massive sandstone with intermittent conglomerate zones consisting of cemented gravels, mudclasts and sands. Geologic features of note with regard to dam stability and long term seepage at the site are dominated by downstream sloping bedding features and conglomerate zones. In addition to the bedding-related features, two predominant vertical to subvertical fracture sets exist. The condition of the vertical fractures ranges from tight and fresh at depth to highly weathered and filled with dispersive clay and gravels near the foundation surface. To provide a durable and effective long term seepage barrier for the dam, an extensive foundation cleaning and treatment operation was undertaken. This comprised drilling, blasting, and excavation of the majority of the highly weathered rock and dispersive materials supplemented by localized installation of small cut-offs and dental concrete and the construction of a double-line grout curtain installed using real time computer monitoring, the GIN methodology, and balanced, stable grout mixes.
Foundation Preparation and Seepage Barrier Installation at Wyaralong Dam Construction Project