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Papers 2005
2005 – THE SMART GUIDE TO OPERATIONS AND MAINTENANCE MANUALS
Learn moreChanges to the Regulatory and legal environment have resulted in an increased focus on the
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importance of proficient management of dams. Operation and maintenance manuals are now a
Regulatory requirement in Tasmania for all but very low hazard dams and are also required to ensure that dams are managed efficiently and safely. To meet these requirements Hydro Tasmania has developed the ‘Smart’ operations and maintenance manual.
Hydro Tasmania has a large portfolio of dams and as a result requires a large number of operations and maintenance manuals. This would result in an overwhelming array of information that is subject to evolving change if the traditional approach to the manual was adopted. To overcome this burden, a controlled electronic manual was developed to enable:
• Critical operation and maintenance information to be collated with minimal effort;
• Electronic hyperlinks to key existing operation and maintenance documents, reference
materials, and portals into operational data bases; and
• A means of updating and controlling information that is subject to change.
This paper will discuss how Hydro Tasmania developed its user-friendly operation and maintenance manuals in an innovative, unique and controlled manner to ensure prudent management of dams and to comply with Regulatory change. -
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Papers 2005
2005 – The Smart Guide to Operations and Maintenance Manuals
Learn moreNicola Woolford, Paul Southcott, Roy Fenderson, Emma Birch
Changes to the Regulatory and legal environment have resulted in an increased focus on the importance of proficient management of dams. Operation and maintenance manuals are now a Regulatory requirement in Tasmania for all but very low hazard dams and are also required to ensure that dams are managed efficiently and safely. To meet these requirements Hydro Tasmania has developed the ‘Smart’ operations and maintenance manual.
Hydro Tasmania has a large portfolio of dams andas a result requires a large number of operations and maintenance manuals. This would result in an overwhelming array of information that is subject to evolving change if the traditional approach to the manual was adopted.
To overcome this burden, a controlled electronic manual was developed to enable:
- Critical operation and maintenance information to be collated with minimal effort;
- Electronic hyperlinks to key existing operation and maintenance documents, reference materials, and portals into operational data bases; and
- A means of updating and controlling information that is subject to change.
This paper will discuss how Hydro Tasmania developed its user-friendly operation and maintenance manuals in an innovative, unique and controlled manner to ensure prudent management of dams and to comply with Regulatory change.
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Papers 2014
2014 – Blowing in the Wind: Reassessment of the Existing Rowallan Dam Spillway Walls – Performance and Design Approach
Learn morePaul Southcott, Tony Harman
This paper addresses structural behaviour of the Rowallan spillway walls and the learning that can be derived from this in the design of critical retaining walls in dams and how this can be applied both to remedial works and new work. The authors propose design criteria suitable for retaining walls in high hazard dams.
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Papers 2017
2017 – Decommissioning of Roaring Meg Dam and Cutten Street Dam No 3 – Creating a New Legacy
Learn morePaul Southcott,Suraj Neupane and David Krushka
TasWater owns and operates the water supply in Queenstown on the west coast of Tasmania. Anew water treatment plant was constructed downstream from one of the seven small dams that made up the original supply system, making the remaining six dams redundant.Two of these dams hada very high annual probability of failure and unacceptable societal life and financial risk due to their poor condition.Both dams required urgent attention (upgrade) to retain them as a lasting asset and legacy for the community or decommissioning to create a new ecological legacy.Roaring Meg Dam (6m high with a 9ML capacity) was constructed on Roaring Meg Creek around 1963. The Cutten Street Dam No 3 (10m high with a 2.4ML capacity) was constructed on Reservoir Creek around 1902to supply water to a growing mining community and had been in use since then. From a heritage perspective, the dam had some value as a timber crib and rockfill dam and its historical context as a key factor in the development of the town.There is limited guidance in the ANCOLD (2003) Dam Safety Management Guidelines on decommissioning and a process had to be developed in cooperation with the Regulator in this relatively new area of dam engineering. Detailed design of the decommissioning including diversion work during decommissioning, channel design to align with the original creek to help restore its ecological function and rehabilitation work on the exposed reservoir soils to stabilise them were undertaken. Aboriginal and historic heritage studies, flora & fauna studies and fluvio-geomorphological study at the dam sites were also undertaken to ensure that the decommissioning work did not interfere with the heritage, threatened species and riparian processes. The community were consulted to ensure acceptance of the changes to their town. Dam safety emergency management plans for the decommissioning of these dams was were also prepared. A significant issue in the decommissioning work was frequent and high rainfall due to the location of these dams on the west coast of Tasmania. The entire dam removal work had to be planned within the window of dry weather or very little rainfall. This paper presents the process, activities and lessons learned in successfully decommissioning these dams,to eliminate the unacceptably high risks posed by these dams and to restore the normal riparian processes.The general approach adopted for this project has applicability for other damsandis proposed as a starting point for an ANCOLD practice note in this area
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Papers 2017
2017 – Nagmati Dam – A Project of Environmental and Cultural Significance
Learn moreRichard Herweynen, Suraj Neupane, Paul Southcott and Ashish B. Khanal
Kathmandu, the capital city of Nepal, is home to more than five million people. Three major rivers including the Bagmati run through the city of Kathmandu, providing the environmental and cultural lifelines for the civilisation and local people. High population growth in Kathmandu over the past 30years has put a serious environmental strain on the Bagmati River. Water is drawn from the Bagmati River for drinking, farming, industries and construction. Due to the lack of capacity in the current sewerage systems, untreated sewage is entering the river system, along with high quantities of rubbish. Although a holy river, the Bagmati River is highly degraded, with reduced flows, high pollution, and a fresh water ecosystem that is now destroyed.To revive the Bagmati River, the Government of Nepal with funding from the Asian Development Bank (ADB), is undertaking the Bagmati River Basin Improvement Project (BRBIP). One of the sub-projects is the construction of a dam on the Nagmati River to store water during the monsoon period for environmental release during dry season.Since November 2015, Entura have been involved in the investigation and detailed design of the Nagmati Dam. Through a simple storage model, it was determined that 8.2Mm 3 of live storage was required to meet the environmental flow objectives. To achieve this storage a 95m high dam was required at the Nagmati site, with a concrete faced rockfill dam (CFRD) determined to be the best option.This paper will present the development of this unique project, highlighting how a number of the challenges were addressed, leading to a sustainable project.
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Papers 2014
2014 – Crack Repair on Outlet Conduits – The Hunt for the Appropriate Method
Learn moreSuraj Neupane, Paul Southcott, and Tung Hoang
Conglomerate Dam has multiple cracks along the asbestos cement outlet conduits running through the embankment. The reservoir level has been maintained at 2m below the full supply level to reduce the amount of seepage, emerging on the downstream face, until the conduits are repaired and protect the embankment from slope instability and piping. Several methods were investigated under an options study to determine the most suitable internal lining method. Slip lining with polyethylene pipe was found to be the most suitable method in terms of technology as well as cost.
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Papers 2013
2013 – Flooded cars: estimating the consequences to itinerants exposed to dam break floods on roads
Learn moreJamie Campbell, Gregg Barker, Paul Southcott and Michael Wallis
The assessment of consequences of dambreak is used as input to the design parameters of dams, dam safety requirements and dam risk assessments. For many low consequence category dams, the consequences of failure can be dominated by itinerants, in particular vehicles on roads within the dambreak inundation area. Estimating the population at risk (PAR) and potential loss of life (PLL) rigorously is mathematically complex, requires significant user judgment and can be very sensitive to input assumptions. This paper presents a simple, practical tool that has been developed to assist engineers and analysts in assessing the PLL of itinerant road users within a dambreak inundation zone. The tool allows for a logical and defensible analysis based on an event tree approach and provides guidance on appropriate factors to be used in calculating the overall fatality rate of people exposed to the dambreak hazard. This paper details the tool and how to apply it to typical dambreak problems, providing the reader with the information required to estimate the consequences on itinerant road users; the paper also details how the concepts discussed can be applied to other itinerants.
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Papers 2008
2008 – Construction of a full height filter buttress against a full reservoir at Dee Dam
Learn moreChris Topham, Paul Southcott, Tim Cubit
Abstract: Dee Dam is a 15 m high and 270 m long central core earth and rockfill dam on the upper reaches of Hydro Tasmania’s Tungatinah Power Scheme. The dam is assessed to have a High A hazard category. Hydro Tasmania’s portfolio risk assessment found that a risk based upgrade was warranted to protect against both piping and flood overtopping failure modes.
A $4.2M modernisation project was implemented in 2008 comprising the installation of a full height downstream filter with rockfill buttress, repairs to cracking in the diversion conduit and raising of the core for improved flood capacity. Lowering of the Dee Lagoon to facilitate full height excavation of the downstream shoulder of the dam was impractical to Hydro Tasmania for production, environment, cost and stakeholder reasons. Hence, careful analysis and risk management was required to ensure the safety of the dam during the construction of the above works against a full storage.
This paper presents the risk objective for the upgrade work, modelling and analysis undertaken to assess dam safety during the works. A wide range of construction risk mitigation measures were employed prior to and during the upgrade works. The response to latent conditions and potential dam safety incidents that occurred during construction are described. The continuous adaptation of the construction methodology to suit site conditions encountered during the project is also presented. The project was successfully completed in June 2008. The approach of detailed investigations and design coupled with a strong risk based approach during the construction proved to be effective in managing the dam safety risks of construction work with a full reservoir.
Keywords: earth and rockfill dam, filters, construction risk mitigation, dam safety, dam safety incidents.
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