J Walker, M Gillon and L Mejia
The Aviemore Dam was built in the late 1960’s and is located on the Waitaki River in the South Island of New Zealand. It is comprised of a 56m high earth dam and a concrete dam housing the power plant and spillway. The dam is located across the Waitangi Fault. This fault was considered to be an ‘inactive’, normal fault at the time the dam was built. The dam is owned and operated by Meridian Energy Ltd.
This paper is in two parts. The first is to introduce the owners Dam Safety management processes. The second discusses the application of these processes to a State of the Art investigation of the faults near the dam, the derivation of seismic loads and the assessment of the dam for seismic loads including potential movement on the Waitangi Fault affecting both the earth dam and the reservoir.
Notable features of the work will be described including:
B Dyer, A Evans, J Titterton
Hume Dam is managed by State Water Corporation, NSW while Dartmouth Dam and Yarrawonga Weir are managed by Goulburn-Murray Water (G-MW),Victoria, all under direction from River Murray Water (RMW).
A series of dam safety emergency exercises commenced with an exercise involving the above agencies and has built up to a multi-agency exercise. The exercises have been designed to test the Dam Safety Emergency Plans, Emergency Action Plans and Flood Operations Plans for these dams under a variety of emergency situations.
These exercises have consisted of a tabletop exercise in 2002 involving the water agencies RMW, G-MW and State Water which presented terrorism and earthquake scenarios; a flood exercise in 2003 for Dartmouth Dam, Hume Dam and Yarrawonga Weir with six control rooms set up at dam sites and water agencies; and a multi agency tabletop flood exercise in 2004 for Hume Dam, involving RMW, G-MW, State Water, Police, SES and local government authorities from both NSW and Victoria.
The third exercise focused on communication and flow of information between agencies, not detailed tactical response.
Outcomes aimed for in these exercises have been improvement in the water agency emergency response plans and inter-agency communications, clarification of roles, responsibilities and capabilities, and to determine opportunities for improved cooperation between agencies.
The exercises highlighted areas which require improvement in the area of emergency response. Implementation of recommendations arising from each exercise is in progress.
Resource consents for Christchurch’s existing solid waste disposal facility at Burwood expire in May 2005 and the landfill must close. A new, state-of-the-art regional landfill is under construction at Kate Valley, which will accept solid waste from Christchurch and surrounding districts. Investigations and studies for the landfill have attracted considerable public attention, engaging public groups in discussions through resource consent hearings in 2002 and 2003.
The proposed landfill includes two embankment dams in a cascade arrangement below the landfill. The first is a 19m high sedimentation dam designed to retain silt runoff from the earthworks associated with landfill construction and operation, protecting the health of the stream and environment below the dam. The second is a 9m high dam performing dual roles of storing and supplying water for the landfill earthworks activities, and providing an additional safety buffer for silt control and containment of any accidental release of leachate at the landfill.
While the dams are relatively modest in size, they are being built to very high standards with strict peer review as a result of their association with the landfill project, and to minimise any community and environmental impacts. The design and construction of the landfill and dams is being completed using an innovative modified alliancing arrangement which provides the close working relationship that alliances are renowned for, while minimising up-front financial risk to the owner.
This paper deals with key aspects related to the landfill dams, such as community consultation and expectations, environmental impacts as well as the technical features. Construction is underway for the dams and the landfill at the time of writing of this paper.
Roy Fenderson & Wayne Peck
Although most people realise that earthquakes cannot be predicted, the Community expects that Dam Owners will utilise leading edge technology and the latest scientific understanding of earthquakes to mitigate the impacts of significant earthquakes once they occur.
The rapid analysis of large earthquake events with respect to critical dams can greatly enhance an emergency response. In order to achieve this enhancement, three sequential, interdependent processes must be in place. These processes are data collection, processing of the data into intelligent warnings and responding to the warnings appropriately. The absence of any one of these three processes or three “legs of the stool” destabilises the other two – greatly reducing the effectiveness of the whole.
This paper will discuss how Hydro Tasmania and the Seismology Research Centre designed, operate and manage an innovative system that encompasses the first two processes, and how their results integrate into Hydro Tasmania’s Dam Safety Emergency Plan (DSEP).
The Wai-iti Valley is located in the northern region of New Zealand’s South Island. Water demand during summer in the Wai-iti Valley is greater than the available supply, resulting in water allocation restrictions and pressure on in-stream habitat and uses. Further, the summer water resource in the Wai-iti Catchment is currently over-allocated. Thus, since the mid 1980s, Tasman District Council (TDC) has been unable to grant new water permits to take water from either rivers or
groundwater in the Wai-iti Catchment. Existing water permit quotas have been reduced where they were not being used, but despite this agricultural, horticultural and domestic use is frequently restricted during dry years.
Recently, the need for a community solution was identified for the Wai-iti Valley area. The Wai-iti Water Augmentation Committee (comprising representatives from the local community and TDC) was set up in 1995 to find the best option for the northernmost extent of the Wai-iti valley. A feasibility study for a community dam was completed in 2001 identifying small off-river storage dams as options. The proposed scheme is located in a tributary of the Wai-iti River and is essentially a water harvesting project where winter flows in the stream would be impounded and stored, and gradually released on a regular basis back into the stream and Wai-iti River system during dry summer periods.
The paper will cover the project’s economic objectives as well as community and environmental impacts and the consenting process under the Resource Management Act. Dam construction is planned to start in October 2004.
Wivenhoe Dam is being upgraded to safely manage any conceivable flood in response to a revision of rainfall predictions by the Bureau of Meteorology. These revisions have led to a substantial increase in estimates of the Probable Maximum Flood that the storage must be able to manage under the ANCOLD guidelines. Wivenhoe Dam, completed in 1985, is located about 80 km north west of Brisbane and is the major domestic water supply for South East Queensland.
The dam is owned and operated by SEQWater who are responsible also for North Pine and Somerset Dams. The upgrade is being undertaken as an Alliance contract with the member companies being SEQWater, Leighton Contractors, MWH, Department of Commerce NSW, and Coffey Geosciences. The upgrade involves construction of a second spillway, 165 m wide on the right abutment. This will be a fuse plug spillway requiring excavation of approximately 600,000 m3 of material.
Construction impacts on the community include noise and dust, blasting, and temporary road diversions/lane closures of the main Brisbane Valley Highway over about two years of construction.
This paper deals with a wide range of stakeholder, community consultation and environmental initiatives that have involved local residents, stakeholders and recreational users in the planning and implementation phases of this project. Several long-term environmental legacies are also discussed.