S.E. Macnish, B Maher2, D. Gill, N Bennett, N.Woods and K.F. Chandler
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.
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Community consultation is starting to become the ‘in thing’ to do for dam safety upgrades.
While ANCOLD has been promoting community consultation as an essential element in dam safety upgrades and is particularly highlighted in its most recent risk guidelines; there are many dam owners who have reservations about its value.
State Water is currently embarking on a series of upgrades and has included strategic ‘up-front’ community consultation in its approach.
This paper further builds on the paper given at the 2003 ANCOLD conference titled: “Keepit Dam Upgrade – The Community Consultation Way”, placing more emphasis on the value of involving the community, the added value that their involvement gives the project and how the community feels about being involved. This paper outlines the outcomes of two State Water projects embracing and practicing procedural justice.
The paper answers a range of questions including:
What is meant by community consultation, its key issues and their handling?
Are there various activities associated with consultation?
What is the value in early community consultation?
How important is it to have a champion and / or champion group?
When would you use a Community Reference Panel and what should its role be?
Who should be members and how critical is the Chair?
Are there other ways to establish a champion and effectively consult?
What is the cost – both time and money and issues handling?
Is it a win-win for the community, dam owner and government?
Involving the community is not just invaluable, it value adds.
Ian Hampton, Dr Mohand Amghar and James Willey
The Eildon Dam Improvement Project is being undertaken by Goulburn-Murray Water as part of its dam improvement program that includes an upgrade of the existing Lake Eildon spillway that passes through the left abutment of the dam. The main components of the spillway are a gated concrete gravity overflow section that is 33 m high and 60 m wide, a 435 m long low gradient spillway chute and a hydraulic jump stilling basin.
The spillway was originally designed, including a physical model, in the 1950s to pass a maximum discharge of 3,400 m3/s with a maximum reservoir head of 9.0 m above the spillway crest. This can be compared with the 2003 flood hydrology and flood routing studies that result in a PMF discharge of 6,900 m3/s and a maximum reservoir head of 14.1 m above the spillway crest.
A new physical hydraulic model study was carried out over 2003-2004 as part of the investigations by the Eildon Alliance for the Project. The model was tested with discharges up to and exceeding the upgraded PMF. Very turbulent conditions were observed at discharges exceeding the original design discharge including the formation, build-up and collapse of large diameter vortices in flow over the spillway crest and overflow section. The vortex phenomena resulted in the intermittent formation of high waves and very high transient pressure loadings at the downstream toe of the overflow section and extending to the upstream section of the spillway chute. The paper discusses some scaling issues, presents some of the salient results of the study and discusses their application to the 2003-2004 design of structural modifications for the spillway.
The paper includes a discussion and comparison of the 1950’s model study with the 2003-2004 study. The magnitude of the vortex phenomena could not be predicted from the previous studies, and it is recommended that investigations for upgrades of similar works that involve large increases in design discharges include detail examination of vortex phenomena.
The ANCOLD Guidelines for the Design of Dams for Earthquake (ANCOLD 1998) were developed by a working group convened by the author over the period 1993-1998.
Since the release of the guidelines there have been some important developments in the design of embankment dams for earthquakes, and it has become apparent some aspects of the guideline could be explained better.
This paper outlines some of these issues with a view to encouraging the Profession to use up-to-date methods.
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.
Ross River Dam is dam of extreme hazard located immediately upstream of a population in excess of 100,000. A comprehensive review undertaken by a team of international experts (ref 1) identified a number of unacceptable risks that required immediate attention.
The State Government designed and oversaw the construction of the dam that was completed in 1976. NQ Water is of the belief that the problems identified by the team of international experts were a result of poor design by the State and inadequate attention by them during the construction process.
NQ Water developed a comprehensive communications plan (ref 2) with the objective of keeping the community adequately informed, gaining positive media exposure, obtaining the support and confidence of the business community and key stakeholders, and securing State Government funding towards the upgrades.
The climate at the time was characterised by adverse media history in relation to the dam, reluctance by the State Government to take responsibility, and poor brand awareness of NQ Water and its activities.
This paper focuses on the process undertaken by NQ Water in engaging the community, various levels of Government, key stakeholders, and business community, which resulted in securing the necessary funding for the dam upgrades. It will discuss the key elements and components of the communications plan, their objectives, the results achieved, and lessons learnt.