Hydro Tasmania is using world-leading innovative technology on the $38 million upgrade of the Catagunya Dam in the Derwent Valley. The two-year project is injecting over $15 million into the Tasmanian economy through the use of local contractors and suppliers.
The upgrade will bring the 50-year-old dam on the Derwent River 30 km from Ouse up to contemporary international safety standards. The dam is 49m high and impounds water for the adjacent 50MW power station.
Hydro Tasmania’s project manager, Andrew Pattle, said the upgrade will incorporate innovative technology.
“We are installing 92 post-tensioned anchors in the dam to replace the original anchors that we believe may be corroding,” Mr Pattle said.
“The anchors are bundles of steel wires that are drilled through the dam and secured into the foundation. Once installed, they are stretched tight using jacks to keep the dam attached to its foundation.
“They are the largest in the world, with each anchor nearly 300 mm in diameter with a holding force of 1700 tonnes, or the weight of nearly 1000 cars.”
Work has begun on the spillway with holes being drilled up to 75 metres deep through the dam and into the rock below. An anchor is lowered into each hole, bonded to the rock and then stretched by a very large jack at the top of the dam.
The new cables are protected from corrosion by encasing them in grease-filled tubes within a larger plastic pipe.
Mr Pattle said four anchors have already been installed in the dam spillway and drilling is well underway for the rest of the anchors.
The project employs a workforce of between 25 and 30 people and is expected to be completed by mid 2010. Local contractors have been employed to build bridges, pour concrete, and provide site cranes. Tasmanian suppliers have been used for steel fabrication and other materials. Design and project management staff are based in Tasmania.
Under its dam safety program, Hydro Tasmania evaluates the condition and design of all its dams to ensure they meet current best practice.
Released by Helen Brain, 03 6230 5746
CATAGUNYA DAM – QUICK FACTS
• 50-year old dam being refurbished at a cost of $38 million
• Injecting over $15 million into the Tasmanian economy through the use of local contractors and suppliers
• 25-30 people employed on the project
• Local contractors employed to build bridges, pour concrete and supply site cranes
• Specialist contractors from Victoria and NSW employed for drilling and anchor installation
• Hydro Tasmania Consulting prepared the design work
• 92 anchors being inserted into the dam
• Anchors 350 mm in diameter with a holding force of 1700 tonnes, the weight of nearly 1000 cars, are the largest anchors in the world
• Each anchor is made from 91 strands of high tensile steel wire
• Holes drilled up to 75 metres deep through the dam in the rock below
• A cement and water grout is pumped into the holes and when set will hold each anchor in place
• Cables encased in grease filled sheaths within a larger plastic pipe to protect from corrosion
• Two large temporary bridges have been constructed to provide access to the face of the dam along with a bridge across the Derwent River
• Project completion mid 2010.