Media Release


18 March 2019

Diving specialists have carried out routine tank cleaning works at three water treatment plants in the Coliban Water region.

Manager Community Operations Mick Dunne said divers are employed once a year to clean the tanks at the Bendigo, Kyneton and Castlemaine plants to maintain water quality.

“Over the course of the year there is a build-up of lime sediment at the bottom of the tanks which has to be removed to prevent it from getting into our water network.

“Lime is a mineral that is used in the water treatment process to adjust the pH of the water and control acidity.

“The divers use specialist equipment, which looks a bit like a giant vacuum cleaner, to suck the sediment off the base of the tank and pump it into one of our holding lagoons.

“The divers also carry out a detailed visual assessment of the condition of the tank liner and record video footage to show the cleaning works and the tank condition.

“The clear water storage tank at our Bendigo plant can hold 40 megalitres, which is the equivalent volume of 20 Olympic-sized swimming pools. It takes around five days to clean the tank and carry out the condition assessment.

“The tank at Castlemaine holds six megalitres and the one at Kyneton holds four and a half megalitres, and can be cleaned in a few days.

“When the lime is pumped into the lagoon it is mixed with the solids that are removed in the water treatment process. Once it has dried out the remaining sludge is removed and reused in soil products,” said Mr Dunne.

The tank cleaning works started in February and were completed in less than three weeks.

The works are part of the AQUA Build Own Operate Transfer (BOOT) contract between Coliban Water and Bendigo Water Services (BWS), which is part of Veolia.

Veolia owns and operates water treatment plants for Bendigo, Castlemaine and Kyneton under a 25-year contract that started in June 2002.

For further information on water quality see our see our Drinking Water and Water Quality page on our website.





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