South Australian Water has made a bid to overcome Occupational Health & Safety issues by installing its first self-priming sewage pumping station.
Supplied by Engineered Products Group, the Gorman-Rupp packaged pumping station replaces SA water's 'conventional' pump station at its Osborne site.
SA Water and United Water International, which manage the operations, investigated several options in trying to overcome health and safety issues.
The site had two dry pit submersibles in a small pump chamber, requiring access via two step ladders.
The self-priming centrifugal option looked the most attractive as the system could be mounted above the ground (adjacent to an existing building used for below ground access), and use the existing wet well (a rectangular wet well with a trough sump).
The use of submersible pumps was considered, but they required the construction of a brand new wet well which would have caused a cost 'blow-out'.
Putting submersible pumps into the existing wet well was considered, but the shape of the well would have made an expensive and awkward retrofit.
Another benefit of selecting self-priming centrifugal sewage pumps was that there is no need to lift lids to gain access to pumping equipment and expose a confined space.
With the self-priming option, all mechanical and electrical equipment is above ground, allowing easy access for maintenance, blockage removal or repairs.
SA Water and United Water decided that self-priming centrifugal was the best alternative and chose the Gorman-Rupp brand of 'Super T' pump.
The company has been manufacturing self-priming pumps since 1933 and has been manufacturing the T series since 1963.
EPG representative Garry Grant explains "The repriming capability of a self-priming centrifugal pump is of the utmost importance when pumping sewage. If a pump doesn't have the capability to re-prime in a completely open system, then maintenance crews will spend a lot of time re-priming pumps."
Mr Grant says the recirculation port needs to pass the same size solid as the impeller to ensure that this 'path' through the pump remains blockage free to enable recirculation during this vital process.
He says that years of research in this area means there is a fine balance between circulation at the right rate to create the greatest vacuum while allowing a large enough solid to pass through without blocking.
Other features of the pump include its capability to have internal tolerances adjusted externally within minutes, keeping the machine at peak efficiency through its life, and also a feature that allows 6 mm of impeller/wear plate wear before wearing components need to be changed.
After commissioning, United Water project manager, Robert Fleet and operations supervisor, Dennis Hall gave the new design their 'thumbs up', especially after the station achieved a 68 dB(A) sound reading at one metre, getting well inside the specified allowance of 85 dB(A).For more  information,please visit http://www.bossgoo.com