Shane Papworth, Stuart Richardson, David Dreverman, Mel Jackson
A prominent element of the operational environment of a dam is its interaction with the community.The management of public recreational use of irrigation storages is an increasing challenge for Goulburn-Murray Water and the Murray Darling Basin Authority. The upper Murray storages have been significantly affected by the unprecedented low water resource availability which has caused an increasing conflict between the primary use of the dam to supply irrigation water and the secondary benefit of recreation and tourism use by the local communities. Many difficult management issues (media, community relations, political interest) arise from the local community, rather than just from operation of the dam itself.
An increasing awareness of the dire water resource position in recent years has coincided with an ever increasing appreciation of the environmental and social impacts of recreational use. For the storages along the Murray system, effective management is further complicated by complex agency and authority responsibilities, communities and interest groups effectively ‘in competition’ for the water resource.
To better manage these issues, ‘Land and On-Water Management Plans’ have been developed for Lake Mulwala and Lake Hume. Developing the Plans has not been without controversy, but ultimately the Plans have proved to be a simple and successful means of planning for and achieving agreed land and water management outcomes. This in turn is fostering a positive spirit of cooperation and communication with communities currently under considerable stress as a result of prolonged drought.
This paper describes the process, pitfalls and learnings to come out of the development of the Land and On-Water Management Plans.
Key words: Environment, community, irrigation dams, recreational use, planning
Michael Bassett-Foss , David Bouma , Dewi Knappstein
The Wairarapa Water Use Project (WWUP) in the southern North Island, New Zealand, is investigating new water storage schemes involving large dams that will allow the community to make use of the water resources that are currently available, but not necessarily available at the time they are needed. It is estimated that the 12,000 hectares currently irrigated in the Wairarapa could be increased to about 42,000 hectares depending on actual demand. The WWUP provides for a range of possible needs, such as supply of new areas of irrigation, increased reliability for existing irrigation and frost fighting, environmental augmentation of low summer river flows, environmental flushing flows, stock drinking water, power generation, municipal water supply, and recreational use.
WWUP objectives include early engagement of stakeholders, early integration of financial, social, cultural and environmental factors in decision-making, management of uncertainty associated with the preliminary level of investigation and evolving regulatory framework, development of an equitable framework for efficiently comparing options, and balancing long and short-term considerations.
A large number of dam options were identified, storing 3 to 80 million m3 of water, and progressively narrowed to a shortlist of 2 sites through a complex process of concept development, desktop studies, site visits, hydrological analyses, cost estimates and multi-criteria analyses.
The WWUP demonstrates how sustainable new major water storage schemes can be promoted in a highly regulated environment of a developed nation.
Keywords: Dams, water storage, stakeholder engagement, environment, water allocation, multi-criteria analysis
Robert Kingsland, Glen Burton
The management and closure of tailings dams can present mines with a trailing liability potentially extending well beyond the life of the mine. The dilemma faced by mine operators is that a tailings storage facility (TSF) is usually required to be in service up until the last product is mined and processed, but the stored tailings may be too weak to support the capping of those facilities for some years after the last tailings deposition. This paper presents the authors’ experience in the geotechnical characterisation of tailings and failure mode analysis required for tailings dams cover design, with particular reference to coal mines in the Hunter Valley. Techniques for field and laboratory determination of strength and consolidation parameters are presented. Failure modes for capping cover and displacement cover alternatives are discussed. Alternative cover techniques including strategies for improving and/or accelerating tailings strength gain are also discussed. Finally, areas needing further study are noted.
Keywords: tailings storage facilities, tailings dams, closure, capping, cover design.
Giovanni De Cataldo
The ANCOLD Guidelines on Dam Safety Management August 2003 were formulated to ensure that dam owners adopt a responsible approach towards the safe operation and maintenance of their dams.
Is it possible to safely, responsibly and acceptably work outside the regulatory Guidelines/Requirements?
The challenge for dam owners now and into the future in meeting stringent standards, is to cost effectively manage their assets within available financial constraints whilst minimising risks and maintaining acceptable levels of safety.
With the continuing drought and suppressed storage levels in most dams, the risk to downstream communities and to the environment from dam failure is significantly reduced.
Based on various studies, investigations, internal workshops and external “Expert Panel” reviews, this paper puts forward a case for a sound and responsible risk-based approach to routine visual and surveillance monitoring frequencies at varying storage levels for “Sunny Day” conditions and compares it against traditional ANCOLD standards which are based solely on consequences.
Keywords: State Water Corporation, ANCOLD guidelines, risk-based approach, dam safety, regulator.
David Brett, Bruce Brown, Imran Gillani, David Williams
This paper reports the direction of a current review of the 1999 ANCOLD Guidelines on Design, Construction and Operation of Tailings Dams. A sub-committee has been formed and has determined that the majority of the current guidelines need only minor editing but that additional attention is required to the concepts of risk and design for closure.
Major mining companies recognise that effective operation and closure of their tailings facilities are fundamental to their continued business from financial and political aspects. Risk needs to be managed throughout the life cycle of a TSF through planning, design, operation, closure and post-closure. Various methods are used to assess the “consequence category” of a TSF. This then determines design and operational criteria. Risks are identified and controls developed to limit these to acceptable levels.
The involvement in the sub-committee of representatives of the mining industry gives an industry perspective to this issue. This includes determination of acceptable risk levels and how to manage operations to achieve them.
The current ANCOLD Guidelines are very limited in terms of guidance for closure and possible abandonment of TSFs. However this area is perhaps the most critical from an economic and environmental perspective. The issues to be faced at closure and post-closure should be considered at the planning and design phases. The paper outlines some of the post closure cases that might need to be considered in design.
Keywords: guidelines, tailings dams, ANCOLD