Papers
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If there is a paper you require prior to 2007 that has not been uploaded please contact the secretariat [email protected]
Use the search below using keywords, year or author.
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2005 Papers
2005 – Pykes Creek Reservoir; Upgrading the Outlet Works for a 95 year old Dam
Learn moreMike Taylor, Jonathan Jensen and Greg Branson
Pykes Creek Dam is a 33 m high, 22,120 ML embankment dam, 72 km west of Melbourne owned and operated by Southern Rural Water.
The outlet works include a 30 m high “wet” outlet tower near the upstream toe of the dam on the right
abutment with its lower half comprising a concrete lined shaft excavated in rock. A 1.5 m diameter
concrete lined tunnel extends 30 m upstream from the base of the tower to a reinforced concrete inlet structure.The only controls upstream of the downstream toe of the dam comprised 2 guard gates located on the downstream side of the tower, operated manually by means of handwheels from the top of the tower.
Major deficiencies with the outlet works included:
- No facility to de-water the tower to maintain the gates located at the base of the tower. The
gates had become partially inoperable as a result. - The gates in any case were extremely laborious and time consuming to operate.
- No facility to inspect and maintain the upstream tunnel and inlet structure.
- No facility to select variable drawoff levels to control water quality and temperature for river
releases. - The access footbridge to the tower was structurally inadequate to safely accommodate loads for remedial works on the tower.
A major constraint in addressing these deficiencies was that any remedial works needed to be
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undertaken without draining the reservoir or interfering with the releases required for downstream
consumers, including irrigators in Werribee and Bacchus Marsh.The paper describes how all of the deficiencies have been addressed with no interruption to supply, by means of a collaborative effort between the dam owner, the consulting engineer, and 5 separate contractors, with the dam owner playing a leading role. - No facility to de-water the tower to maintain the gates located at the base of the tower. The
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2005 Papers
2005 – Bellfield Outlet Tower – How to do interesting things in tight spaces
Learn moreJL Tottenham
This paper outlines how Grampians Wimmera Mallee Water (trading as GWMWater) and its consultants managed the upgrading of Bellfield dam’s 43m high, reinforced concrete dry outlet tower and discharge facilities. The upgrading included improvements to operations, the provision of safe person and materials access into the tower and its 1200 mm diameter steel penstock, anchoring the tower with post tensioned cable anchors to resist seismic loads, refurbishing a 1200 mm butterfly valve and penstock corrosion assessments and repair.
Prior to the upgrading, access to all areas was difficult and unsafe to some areas. In particular no provision had been made during the original construction for butterfly valve removal or safe access into vertical sections of the penstock. Overcoming these deficiencies required considerable survey, detailed movement planning and attention to detail.
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2005 Papers
2005 – RCC Construction & Quality Control for Burnett Dam
Learn moreJosé López1, Tim Griggs, Robert J. Montalvo, Richard Herweynen and Ernest Schrader
The Burnett Dam is a 50m high Roller Compacted Concrete (RCC) Dam with a total RCC volume of
400,000 m3. It is located on the Burnett River, approximately 50km inland from the town of Childers
in Queensland, Australia. The design of the dam commenced in 2003, construction started in
November 2003 and the dam will be completed by the end of 2005.This paper discusses the construction processes, the extensive quality control program and the
innovations developed for the RCC dam construction.Key features of the project discussed in this paper are:
- The low cement RCC mix design and its optimisation during the construction stage.
- Thermal issues and elimination of the need for cooling.
- Performance of the ‘all-in-one’ aggregate stockpile.
- Dual pugmills for RCC production.
- RCC delivery in different areas of the dam undertaken by conveyor, Creter crane and trucks.
- Extensive laboratory and field testing used to evaluate and improve production and quality
control procedures including an analysis of the Lift Joint Quality Index.
During construction, special emphasis was given to the inspection of the processes of production,
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transportation, delivering, placement, compaction and curing of the RCC. -
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2005 Papers
2005 – The Environmental Sustainability of Large Sams Compare with Other Sources of Water Supply
Learn moreRobert Humphries, Caroline Minton, Andrew Baker and Mark Leathersich
There is a constant stream of criticism levelled at the perceived or actual adverse environmental
effects of large dams. These criticisms include prevention of fish migration, thermal and chemical and biological disturbance of downstream riverine habitats, silt trapping and drowning of terrestrial
habitats by flooding behind the dam wall. The beneficial effects of dams are rarely discussed, but
include aquatic habitat creation, catchment protection, flood mitigation, carbon sequestration and
protection of endangered species, amongst others.Critics of large dams rarely present an analysis of the environmental costs and benefits of other water supply options, which include abstraction of shallow or deep groundwater, desalination of seawater, and reclamation of human or other wastewater.
In this paper we compare the environmental costs and benefits of water supply from large dams with
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the common alternative options, and assess the relative sustainability of them all. -
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2005 Papers
2005 – Revised Extreme Floods in Tropical Regions
Learn moreR.A. Ayre and T. L. McGrath
SunWater as an owner of 25 major dams in Queensland has completed a programme to update the design flood hydrology of all of its referable structures in accordance with the latest methodology for estimating extreme design floods. This programme ensures the adequacy of existing spillways is included in an overall dam safety portfolio risk assessment in a consistent fashion.
This paper describes the methodology adopted in the re-assessment of the design flood hydrology of the storages. Principally this has meant the use of a design hydrograph approach utilising runoff-routing methods as described in Australian Rainfall and Runoff (1999). Design rainfall inputs have been based on generalised techniques derived by the Bureau of Meteorology such as the Revised Generalised Tropical Storm Method and the Generalised Short Duration Method for the estimation of Probable Maximum Precipitation. These estimates, coupled with the use of a regional design rainfall estimation technique known as CRC-Forge that is used for determining large to rare design rainfall estimates, have been used to derive a complete estimate of the inflow/outflow flood frequency curve for each dam.
The paper also provides an insight into the significant factors and relationships that are involved in the changes resulting from this process. Overall, there has been an increase in design rainfall depth estimates for the extreme events, and a general reduction to neutral change in the large to rare rainfall range. These changes plus the influence of temporal effects and the assignment of Annual Exceedance Probability (AEP) has led to substantial changes from previous estimates of design floods. The implication of these changes is profound for
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an organisation such as SunWater. -
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2005 Papers
2005 – Importance of Streamflow Monitoring for Sam Safety and Water Supply Security
Learn moreIan Cordery, Peter S. Cloke
Scientists advocate more hydrological monitoring but in most regions publicly funded monitoring is in
steady decline. The lack of measured data at dam sites means there are many designs for new dams and remedial work that are insufficiently supported by factual information. Unfortunately data –free modelling exercises will usually produce favourable results – favourable to the modeller’s purposes, but not necessarily favourable to the determination of physical reality or truth. In these days of the popularity of modelling it is common to find decisions being made based on model studies for which little or no local data were available for model calibration or verification. How can the ‘large dam’ fraternity encourage (ensure) more data use? Causes of lack of data are many. For example governments fund data collection but others need the data, and data collection is a long-term activity that produces few benefits in the short term. Some years ago it was shown that hydrological data collection and archiving provided benefits to the community of at least nine times the costs of the data.The real costs of comprehensive data collection are not large but examples will be given of the huge
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costs, mainly due to the need to allow for uncertainty, that result from unavailability of data. Those
who understand this problem need to explain it to their communities, politicians and CEOs in a clear,
unmistakably persuasive manner, and to demand an increase in data collection. If we do not, no one
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2005 Papers
2005 – Ground-Motion Attenuation Modelling in Australia; Implications for Earthquake Hazard and Risk
Learn moreTrevor Allen, Phil R. Cummins, Trevor Dhu, John Schneider
Ground-motion attenuation models have been derived for the Australian crust. These models
employ both empirical and stochastic methods and are the first spectral ground-motion models to be
based entirely on Australian ground-motion data. In the past, these studies have been hampered by a lack of quality ground-motion data given Australia’s relatively low levels of seismicity.Two key datasets have been employed to derive empirical ground-motion attenuation models for
Australia; one from data recorded in the Palaeozoic crust of southeastern Australia (SEA) and the
other from the Archean shield region of southwestern Western Australia (WA). Empirical ground motion models are derived for each of these datasets. In general, long-period (e.g. 1 sec) ground motion energy appears to attenuate less in WA than in SEA. These empirical models suggest that SEA has similar near-source attenuation with eastern North America. Because of the limited and spatially clustered nature of the WA dataset, however, we could not constrain attenuation models as well as in SEA.Stochastic methods are employed to simulate ground-motions for larger earthquakes in regions
where recordings from real events are not available. These models are largely based upon source and attenuation parameters derived from empirical studies. Stochastic models are derived for SEA only.Spectral ground-motion predicted by these models are generally lower than ground-motion predicted
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by both eastern and western North American models, particularly at short-periods (T < 0.5 sec).
Results from this study have significant implications for earthquake hazard and risk in Australia. They
suggest that we are currently overestimating earthquake hazard in SEA. Furthermore, they suggest
that we cannot simply rely on North American ground-motion models to predict earthquake ground
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2005 Papers
2005 – A Contribution to Public Safety Studies – Failure Modes and Likelihood Analysis for a Tephra Dam on an Active Volcano
Learn moreMurray Gillon, Robin Fell, Harry Keys, M Foster
Volcanic eruptions at Mt Ruapehu in 1995-96 resulted in the deposition of about 7m of tephra over the rock rim overflow of Crater Lake. There is a long history of lahars (debris flows) associated with releases of water from Crater Lake. The 1995-96 eruptions emptied the lake and it has slowly been refilling from rainfall runoff and snow melt. When the lake level rises above the rock rim the tephra layer will act as a “barrier” or dam. Breaching of the barrier will release water and generate a lahar. The magnitude of the lahar flow will be a function of the lake level at the time of breaching
Extensive studies of the effects of the lahar that would be generated by the failure of the tephra barrier have been undertaken. The studies included a failure modes and likelihood analysis to provide information on the relative likelihood of failure as the lake level rises for the different failure modes applicable to this situation. The paper describes the failure modes considered and the results of the analysis.
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2005 Papers
2005 – Snowy River Environmental Releases
Learn moreBrett Jones, Brian Mayhew
In preparation for the Corporatisation of the former Snowy Mountains Hydro-electric Authority, an
enquiry was held into the health of the Snowy River below Jindabyne Dam. This enquiry has led to a
range of environmental release requirements being placed on the new entity Snowy Hydro, including
requirements for variable release patterns (daily base flows and periodic flushing flows) and water
quality control.Construction works are currently underway to modify the existing Jindabyne Dam structures so that
these releases can be provided. The works include a new intake channel and control structure, a new environmental release tunnel and modifications to the existing spillway, including a concrete lined chute and plunge pool. Provision is also being made for a future mini-hydro power station, which would generate using waters released to provide environmental flows.This paper discusses the history and background of Jindabyne Dam including the Snowy River
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inquiry, details of the environmental flow requirements; design to meet the required capabilities and
the current status of the project. -
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2005 Papers
2005 – Lake Mokoan Decommissioning Project: Working with the Community to Maintain Supply Reliability
Learn moreGraeme Hannan, David Jeffery
Lake Mokoan is a 365 GL capacity off-stream storage in the Broken River basin in northern
Victoria. Lake Mokoan will be decommissioned to provide 44 GL of water savings to benefit the
River Murray and the Snowy River. The Victorian Government has committed to maintain
reliability of supply in the Broken River supply system by implementing a package of offset projects.
The paper describes the community engagement process implemented by Goulburn-Murray Water
to steer the selection and implementation of the offset projects.A reference committee of Broken systems irrigators was established in late 2004 to provide advice
to Goulburn-Murray Water and the Department of Sustainability and Environment on the package
of offset measures to be implemented to maintain the supply reliability once the 365 GL capacity
Lake Mokoan was decommissioned, leaving the 40GL capacity Lake Nillahcootie as the sole
storage in the Broken River irrigation system.A REALM based system simulation model was refined to test the sensitivity of the parameters
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defining the system reliability and to assess proposed offsets measures. The paper describes the
modelling which was undertaken and the evaluation and ranking of offset projects priorities.
The community engagement process is described. The paper concludes with commentary of the
lessons learned from this process. -
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2005 Papers
2005 – The Significance of Factors Affecting Secure Yield
Learn moreMalcolm Nix
“Off-river” storage, Bootawa Dam, receives water pumped from the Manning River to supply a
regional water scheme on the mid-north coast of NSW.As part of drought planning, short term predictive modelling of future streamflow has been developed
from an analysis of the last 30 years of recorded flow data and “on-line” upstream river gauges.
In the longer view, a comparison was made of th e last 30 years of recorded flow with an analysis of
the previous 80 years of synthetic flow data. There is a downward trend in streamflow in the last 25
years. Is this likely to continue, or is it part of a cycle or some other factor?Long term fluctuations in the Southern Oscillation Index are compared to rainfall for this region.
Estimates of sustainable yield of the scheme are dependant on many factors, including environmental flows, dam size, turbidity constraints, river pump transfer capacity, river loss, catchment rural demand, accuracy of streamflow data and future climate change.The affect of each of these factors has been quantified and ranked according to their importance on
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sustainable yield. -
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2005 Papers
2005 – Water for the Waimea Basin, New Zealand
Learn moreJoseph Thomas, Peter Thomson, John Grimston, Sally Marx
The Waimea Basin is located in the South Island of New Zealand. The area has an acute water shortage with recent studies showing the water resources to be over-allocated by 22% for a 1 in 10 year drought security. The current area irrigated is about 3,700 ha and there is additional productive land that could potentially be irrigated if more water were available. Water users have suffered severe restrictions on their water use over recent years through drought management measures imposed to meet critical environmental flow requirements and coastal salinity buffering. This has caused significant production cutbacks for irrigated crops resulting in regional economic loss, affected major urban water supplies resulting in water supply cut-backs affecting domestic and industrial users and also affecting the important environmental values of the Wairoa/Waimea Rivers and the coastal springs that are highly valued by the community and local iwi (Maori).
The principal objective of this project is to carry out a study into the feasibility of water storage in the upper parts of the catchment for enhancing water availability for both consumptive and environmental/community/ aesthetic benefits downstream. The outcome from this feasibility study will provide the community with the necessary information to make an informed decision on proceeding with potential storage options. The Waimea Water Augmentation Committee is overseeing this feasibility study. The study will be completed byJune 2007.
The Waimea Plains area is also quite unique as to the interest and values relating to the water resource as it has multi stakeholder interest. Being close to urban centres, the water resource not only caters for irrigation use but also public water supplies as well as recreational, community interest and cultural values.
This paper sets out the project’s aim, general methodology being followed, and summarises the progress to June 2005.
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