Dam infrastructure news - August 2006.
Here is an updated summary of the sketchy information that we have been able to glean from DNRM&W staff during the public forum process and later consultations concerning scientific, legal, engineering and construction aspects of the dam and it's impact Some of this advice has only been given verbally.
Legal and political constructions
The construction of the dam is now in the hands of Queensland Water Infrastructure Pty Ltd. Scott Smith, who was the State Government officer in charge of the project is now employed by QWIPL. QWIPL's CEO is Graham Newton, who was the CEO of Burnett Water Pty Ltd (now defunct), the company that built the infamous Paradise Dam on the Burnett. Burnett Water (including Paradise Dam) was subsequently taken over by Sun Water. QWIPL will be acting in a commercial capacity to conduct the engineering, economic and scientific studies required to licence the dam and proceed with its construction and will be contracting State Government departments to conduct some of these investigations (eq. hydrological studies) as required. Officially, NRM&W is now simply the regulating body overseeing the licencing of QWIPL's activities. Premier Peter Beattie has now appointed himself the chief executive ultimately responsible for water licencing decisions in Queensland. Although not announced in the media, on 28/07/06 the Water Resource Plan (Mary Basin) became law (SL192). This legislation provides no effective protection of the environmental flow regime in the Mary River downstream of the dam site and gives the chief executive discretion to grant an Interim Resource Operations Licence to applicants such as QWIPL before a legal Resource Operations Plan for the Mary Basin is in place.
Which properties will be affected
NRM&W staff can still give no indication of where the effective boundary line between stage one and stage three of the project lies, and still cannot provide information about whether there will be a buffer zone around either of the stages announced, or the likely size of this buffer zone. The public still do not have access to a map which accurately shows which properties will be affected by the proposed stages of the project. NRM&W staff state that studies showing the effect of flooding upstream of the dam have not been released yet. QWIPL have advised that this information will be available 'by the end of the year'.
In addition to the main dam, a number of other smaller saddle dams are on the plans to stop water escaping from the impoundment in flood conditions. Although the water level at full supply is proposed to be at 79.5 m above sea level, the top of the main dam wall and the saddle dams are at approximately 94m above sea level. If this much freeboard is required on the dam to allow the spillway to cope with flood flows, this has worrying implications for residents in the catchment far upstream and has worrying implications for the towns of Kandanga and Imbil. Although this may not be connected, Cooloola Shire Council and the State Government have been in negotiation with developers around the township of Kandanga Creek (upstream on Kandanga Creek) regarding large new subdivision projects in this higer location.
Currently, NRM&W are responsible for property negotiations with people affected by hardship associated with the full supply levels on either of the two maps published to date and the buffer zone shown on the first map. QWIPL will be responsible for the property aquisition planning for the project once the 'new' map with the flooding information and full impact on roads and access is released
Water grid and water trading
The state government has released a lot of new information concerning commercial trading of water allocations. At present, water licences are linked to property titles. As soon as a Resource Operations Plan is in place for the Mary, these will be converted to water allocations, listed on a seperate title, and free to be traded independently of the land. Any one considering selling land with an existing water entitlement should look into the financial and legal implications of this when it comes to the fair valuation of their property under these circumstances.
http://www.nrm.qld.gov.au/water/trading
Dam Construction
QWIPL have not announced the location of pumping and power stations or the pipelines to transfer water however, pipelines will follow existing government easements where possible. It is most likely that the water will be transferred from dam to dam down the Eastern side of the Mary Valley, involving the construction of pipelines from Traveston to Cooloolabine to Baroon Pocket to Ewan Maddock to North Pine etc. There is a power line planned for this route in the SEQ infrastructure plan.
Designers are having trouble with the spillway design and are running a series of simulations to work out how the dam will cope with major flooding events. The top of the dam wall is proposed to be at 94 m above sea level, and this is the approximate elevation of a number of smaller saddle dams that will need to be constructed. There have been no announcement as yet as to how the river flow will be diverted during dam construction. Some details of dam construction, including plans, were released to the State Parliamentary estimates comittee. (Click here to view plan and statistics)
The deep fractured rock under the dam wall will need to be sealed with a grout curtain - a network of deep holes is drilled in the rock and it is pumped full of cement slurry to seal the footings. The dam will uses a variety of construction methods, being principally a gravity dam that relies on it’s shape and mass and the mass of the water behind it to hold it in place. The principal method of construction will be roller compacted concrete, a procedure where a fairly dry mix of concrete is delivered directly to the dam wall from an on-site concrete plant via a conveyer belt where it is spread into layers and roller compacted. The dam is built up as a set of horizontal layers. There will also have to be some other methods of construction used in some places, such as concrete skin rock fill and earth wall.
The construction method requires a huge amount of crushed rock aggregate to be delivered to the site. There are a number of sources of this in and near the valley but the closest is the Meadvale quarry, site of the State Government’s Mega Dump proposal just north of Traveston. It is large enough to provide the amount required, is on the rail line, and is the only State Government protected resource nearby. The other obvious source of suitable aggregate is at Moy Pocket, but this is privately owned and a lot further from the dam wall. Approval for the significant expansion of Moy Pocket quarry has recently been given and power supplies in the valley have been re-configured to allow the installation of new crushing machinery. There are other possible rock sources in the area, but these were the only two specifically discussed. DNR&M staff have done everything they can to not say the words “Meadvale”, “Traveston” or “Tandur” in discussions with them about the rock source, although they can point to the general location of the quarry on a map and refer to a “protected resource” in that area. There are three similar rock deposits in that area, but the Meadvale Quarry is the only one that has been developed, (as a source of ballast for the North Coast rail line).
There has been no comment on the impact that moving this volume of rock to the dam site will have on local residents or the Bruce Highway.
Steve Burgess August 2006 |
