Inspire : Public Works Sept Oct 2012
44 Public Works Professional September-October 2012 [COMMUNITIES OF PRACTICE ASSET MANAGEMENT ] downhill, some systems cannot be designed to do this, so vacuum systems allow the sewage to ‘travel up- hill’ to the collection point. The sewage then needs to be drawn out of the tanks and sent to the sewage treatment plant. Because this tank is under vacuum, it’s hard for pumps to pull against it, so the pump needed to pull against that and create 73 metres of head. Unfortunately, there are not many pumps available to cater to these needs. After several months of searching, Harris met Garry Grant, General Manager of Hydro Innovations. Together, they discussed the problem and spent several months exchanging information and designs. The fnal design was not only cost effective, it was also customised to suit Woodgate Station. “When assessed on a whole of life cost, including installation, maintenance and annual running cost of the units, their pricing was very competitive, which is also something that local government must consider,” adds Harris. It was eventually decided that Hydro Innovations would install the Gormann-rupp Ultra vS3A60-B, a two-stage self-priming sewage pump, which creates extra pressure. each of the stages of the pump develops 45 metres of head. The new pump was a purpose-built sewage pump and can also handle all manner of solids, which was a problem for the old pumps. According to Grant, scraps of clothing are a big problem, as people tend to dump all sorts of debris in their toilets. “Things like matted hair cause problems for the mechanical system, including the pump,” he adds. “The selected pump handles tin cans and stringy materials like underwear and shirts.” Since the installation of the Gorman-rupp pumps, maintenance costs have been dramatically reduced. In fact, Harris and his team have barely even needed to go back to the pumps and work on them. “They’ve been in for about 18 months and we haven’t had to do anything apart from general maintenance,” he says. “There’s been no work done on them at all. We just check the belt tensions to make sure they haven’t frayed and check the bearings are greased and there are no leaks. “Basically, we were previously spending between $30,000 and $40,000 a year on maintenance costs. now, we’re spending about $2000. The total installation of the pumps was somewhere in the vicinity of $88,000, so now we can pay the two pumps off in two years.” ••• CONTINUE THE CONVERSATION Have your say on this story. Go to http://goo.gl/oXRDy to comment on this article. Basically, we were previously spending between $30,000 and $40,000 a year on maintenance costs. Now, we're spending about $2000. The pump was designed especially to meet the needs of Woodgate.
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