Sydney to Build Desalination PlantAs part of the New South Wales government's initiatives for sustainable water supply, Sydney Water will build a major seawater reverse osmosis desalination plant. The Blue Water desalination plant has a secure and reliable supply of water that is not rainfall dependant. This project comes in the face of uncertainty over climate change and strong demographic growth in the region.The project consists of intake and outlet tunnels, seawater pump station, pre-treatment filters, a two pass reverse osmosis process, post-treatment and 40,000 cu m storage. The desalination plant will have an initial capacity of 250,000 cu m/day while the seawater intake and brine discharge tunnels have been designed for a total capacity of 500,000 cu m/day to allow for future expansion. Work began on the project in late July 2007 and water will be delivered to Sydney residents by the Australian summer (November to March) 2009/2010. Sydney Water has awarded two contracts for the desalination project. The Blue Water joint venture will design, build, operate and maintain the desalination plant at Kurnell and the ocean intake and outlet tunnels for 20 years. The joint venture consists of Veolia Water and John Holland. Their contract is worth AUD960 million. John Holland's interest in the project is valued at approximately AUD600 million. Veolia Water will operate the plant for 20 years. Click au/26. Visit www.johnholland.com.au and www.veoliawater.comThe Water Delivery Alliance will design and build the delivery pipelines from Kurnell to Erskineville. This alliance is made up of Bovis Lend Lease, McConnell Dowell, Kellogg Brown & Root, WorleyParsons and Environmental Resources Management.Construction methodsVarious construction methods will be used to lay the pipeline, including hard rock TBMs, microtunnelling and trenching. Microtunnelling will mainly be used in residential areas. The pipeline across Botany Bay will be constructed using methods to avoid long-term environmentalimpacts. The construction method is designed to minimise inconvenience to people who use the bay for recreation and fishing.Intake and outlet tunnels will connect the desalination plant site with the Tasman Sea. The seawater tunnels will not travel through residential areas. Both seawater tunnels travel approximately 300 m offshore, with a depth below the sea floor between 20 and 30 m. Geology will predominantly consist of Hawkesbury sandstone. The outlet tunnel is expected to intersect two dykes during excavation.The seawater intake tunnel length is 2,579 m, allowing for 14 m TBM burial chamber. The bored diameter of the seawater intake tunnel is 4,150 mm and the finished internal diameter is 3,400 mm. The seawater outlet tunnel length is 2,579 m allowing for 14 m TBM burial chamber. The bored diameter of outlet tunnel is 4,100 mm and the finished internal diameter is 3,400 mm.Two double shield hard rock type TBMs supplied by Herrenknecht will be used. Launch tunnels for the TBMs will be excavated using a S200 roadheader. The roadheader will undertake full face excavation. Visit www.herrenknecht.comThe launch tunnels will be supported using fully encapsulated resin grouted R27 Secura bolts. Steel fibre shotcrete will be applied where necessary. Visit www.stratacontrol.com.auThe TBM tunnels will be supported with precast concrete segments. Each ring consists of six segments and is 1.35 m wide. Segments are universally tapered trapezoidal. Concrete segments are cast by Georgiou Group and are steel fibre reinforced. Segment moulds are supplied by Korea Mould. Sealing gaskets are supplied by Phoenix and segment inserts and dowel bars are supplied by Sofrasar. Visit www.georgiou.com.au, www.kmceng.com, www.phoenix-dt.de and www.sofrasar.frSpoil removal will be undertaken by two 2,000 m continuous conveyors supplied by Marti Technik, with capacity for 240 tonnes/hour and powered by 90 kW each. The conveyors will feature a curve radius of 500 m. The belts are 500 mm wide. Visit www.martitechnik.ch Excavation activities at the pump station Work advanceA box cut has been excavated to provide room for the TBM build. The box cut will also house the pumping station and stilling basin. Concreting works has begun in the box cut for these structures. Excavation of launch tunnels will commence after Easter once the concrete structures have progressed to a stage where tunnel excavation can commence. TBM excavation will commence mid-year. Visit www.sydneywater.com.au/EnsuringTheFuture/Desalination/pdf/Desalinationfactsheet_Seawatertodrinkingwater.pdf#Page=1 12/08.