Inspire : Public Works Sept Oct 2012
43 $88K [COMMUNITIES OF PRACTICE ASSET MANAGEMENT ] In 2009, KevIn HArrIS, A TeCHnICIAn WITH Bundaberg regional Council, was faced with a maintenance nightmare. The old sewage pump at the Council’s Woodgate vacuum Sewer Station was barely plodding along and prone to regular breakdowns. According to Harris, the system had been designed with some basic faws. As time went on, changes were made without consideration of the impact they would have on other parts of the system. At the time, a positive displacement lobe-style pump was being used. “One major failing was extending the length of the system without having extra pump stations along the way,” Harris explains. “This meant, to operate effectively, the system had to operate at a much higher vacuum: negative 80 kilopascals (the plant was designed to operate at approximately 65 kilopascals). “This had a major impact on the system as a whole, especially in the vacuum tank, which was not designed to operate at such vacuum. This resulted in the tank imploding.” every six to eight weeks, various parts would wear out and need to be replaced, but major overhauls would then need to be conducted every three to four months, recalls Harris. Silt was building up in the system because the pumps were not generating enough fow to move the sewage. Some months, it would cost the Council $2000 to $3000 to maintain the sewage pump, but every so often, bills would skyrocket up to $15,000. “If you take into account breakdowns, the effciency was troublesome,” Harris says. “[effciency levels were] dropping off fairly dramatically as the pump was wearing out. “When a pump is brand new, it pumps 20 litres a second. But after awhile, it might only pump fve litres a second, so it takes four times longer to pump out the same amount. The running costs are expensive.” At the end of 2009, it was decided that something had to be done and Harris began looking at alternate solutions to improve matters. However, this proved to be quite diffcult, due to some of the sewer station’s unique features. Bundaberg’s vacuum sewerage system incorporates a network of sewerage lines that come from houses and businesses, which all lead back to a collection point. A vacuum tank is located here and the sewage fows towards the tank with the aid of vacuum pumps. The vacuum system works the opposite to a gravity system. Whereas a gravity system fows @ PUMPING UP THE SAVINGS replacing a poorly designed sewage pump has rid Bundaberg regional Council of thousands of dollars in maintenance costs. BY JO-ANNE HUI IN 2011, BUNDABERG REGIONAL COUNCIL HAD AN ESTIMATED POPULATION OF 91,858 PEOPLE. THIS IS EXPEXTED TO GROW TO BETWEEN 112,647 AND 122,820 PEOPLE BY 2021.
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Public Works Nov Dec 2012