Brian Haisman, Clarke Ballard and Neville Garland
In early 1997 the Murray-Darling Basin Ministerial Council instigated a review of the operations of its primary reservoirs, the Hume and Dartmouth Dams, in response to concerns of floodplain communities below the dams, coupled with changing community values in relation to the in-stream environmental effects of dams. The review, completed in May 1999, achieved a consensus between parties advocating what are on the surface irreconcilable objectives for the management of the water resource. Foremost competing objectives were flood mitigation, consumptive water use, and environmental health of the river system, plus subsidiary objectives related to recreation, hydro-electric generation, salinity management, tourism and the like. The keys to success were firstly, creation of a community-based Reference Panel which took on a steering role coupled with extensive consultation, and secondly a determination to describe situations wherever possible by means of factual information. The paper describes the identification and evaluation of issues, the consensus building process, the intensive hydrology and economic modelling undertaken, and the development of a comprehensive set of flow parameters which could be viewed as surrogates for environmental outcomes. Conclusions and recommendations are drawn for future reviews of similar dams.
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Peter Quinlan and Sergio Giudici
The Hydro Electric Corporation (HEC) owns and manages 54 large and referable dams across Tasmania. Monitoring, data storage and data utilisation techniques have evolved significantly over the years as the dams have aged and as instrumentation, communication and data management technologies have advanced. This paper describes the development of the HEC’s ‘Asset Safety Evaluation Tool’ (ASET) for acquisition, management and interpretation of data relating to dam safety management. The paper also provides examples of how ASET has been applied within the HEC to demonstrate how the primary functional development goals of robustness and practicality have been achieved.
The paper outlines the integration of Environmental Risk Management in Goulburn- Murray Water with previous work on Dam Safety, Business and Occupational Health and Safety risks. This has now been followed by the development of an Environmental Management System (EMS) to provide an environmental risk management framework for the whole Authority.
An Environmental Audit in 1997 identified deficiencies in some areas of environmental management and questioned the Authority’s ability to demonstrate due diligence. This led to a decision to develop and implement an EMS based on the International Standard ISO 14001.
Examination of Goulburn-Murray Water activities, associated environmental aspects and impacts, (and the consequences arising), led to the establishment ofan environmental risk register. Analysis and assessment of the risks to produce a ranking Jrom low to very high is described. Refinement to a significant risk register (high and very high risks), and consolidation into a list of generic risks based on major activities, functions and asset categories is described.
Based on this risk profile for the Authority, the Environmental Policy and Objectives were revised, and a methodology for identifying Environmental Targets was developed. Environmental Risk reduction is then delivered through the implementation of target driven Environmental Management Programs (EMPs).
Major system elements described include an emergency response plan, a legal register, an authority / responsibility matrix, a document control system, procedures, forms, training, auditing, and reporting.
The paper describes some of the practical issues encountered and the lessons learned with a focus on the activities of the Headworks Business. A prospective view of implementation and culture change issues is given.
Shane McGrath and Michelle Cowan
Goulburn-Murray Water (G-MW) is a Victorian rural water authority with responsibility for management of the major water systems within a 68,000 square kilometre region. Following a detailed business risk assessment undertaken in 1996, Goulburn-Murray Water developed a ten-year program to commence design reviews and address identified deficiencies at thirteen dams for which G-MW has responsibility.
In October 1997, the Victorian Government announced a $450 million regional water reform package, of which $35 million was provided for rural water authorities dam improvements. $18.5 million was allocated to G-MW on a ‘dollar for dollar’ basis. With contributions from G-MW customers, the current total funding amounts to $37 million.
This paper focuses on processes that G-MW has adopted to manage an accelerated program of dam design review and remedial work.
Robert J. Parker
This paper examines the current trends in the construction of Roller Compacted Concrete Dams in Australia and Internationally. Certain recent trends to processes such as grout enriched vibratable RCC will assist both the cost effectiveness and simplicity of this type of dam construction. Key issues considered are: I. The trend is to use less conventional concrete in the structure and grout enriched RCC against contact surfaces are the means of achieving this. 2. Proportionally greater use is being made of high paste mixes 3. In order to maximise placing rates, keep it simple 4. Aggregates should be manufactured in not less than three sizes and preferably four if segregation is to be controlled
Javad Tabatabaei! and Christopher Zoppou
Cotter Dam was constructed in 1912 to 19m and was raised to 31m in 1949. Due to its close proximity to a popular recreational resort, it is considered as a high hazard dam. It forms a storage with a capacity of only 4500ML and receives flows from a catchment area of 482km?. Concern about the ageing and structural integrity of Cotter Dam was expressed as early as 1967. There has also been a major revision of the Probable Maximum Flood (PMF) and new earthquake requirements for the dam. All these factors have contributed to the decision to undertake remedial works on the dam. The remedial work could be interrupted by flows over the spillway. This would increase the cost of the works because the construction equipment must be removed and reinstated (de/remobilisation) when there are flows over the spillway. Additional costs are also incurred for each day the construction equipment remains idle (standby). The total tender price therefore includes the cost associated with the remedial work as well as any standby and de/remobolisations. Risk analysis was used to establish the frequency the reservoir water level exceeds the spillway level. The risk analysis was used to select the successful remedial works tender.