A contract to upgrade Mangaung Metro Municipality’s Maselspoort low and high lift pump station has been awarded to Veolia Water Solutions and Technologies South Africa (Pty) Ltd.
The 12-month contract, which began in September 2013 and aims to ensure the plant continues supplying 34%of Bloemfontein’s treated water, comprises mechanical and electrical upgrades. The improvements comprise replacing four low lift vertical turbine pumps with two low lift centrifugal self-priming pumps, the motor sets and associated pipe work; and two high lift split casing centrifugal pumps take the place of five horizontal centrifugal pumps. Each low lift pump has the equivalent capacity of two of the dated pumps; effectively providing a combined capacity equivalent to the four replaced pumps. The duty pump will be controlled remotely by DOL (direct online) and the other by variable speed drive (VSD,) allowing the operator to regulate pump speed while monitoring delivery flow.
Sump and pipework
The low lift pump sump will be changed from a dry to a wet well sump requiring additional suction pipework. “In order to tie the new piping in to the existing pipe work infrastructure, installation will take place in conjunction with a section of the discharge pipework,” says Michael Haig, Lead Engineer, Veolia Water Solutions and Technologies South Africa (Pty) Ltd. The high lift split casing centrifugal pumps, which join an existing refurbished pump, will run on VSDs to regulate them according to water demand. As part of the contract, there furbished pump will have its impeller replaced and motor size increased to bring its capacity in line with the two new ones. “The pumps and motor operation will be installed with features that enhance maintenance efficiency and overall system reliability,” says Haig, “while pump and motor operations will be remotely monitored.”
“The high lift pump suction pipework remains primarily the same,” comments Thabo Mogadima, Business Development Manager, Veolia Water Solutions and Technologies South Africa (Pty) Ltd. “The only exceptions are that the weir needs to be extended and suction pipe replaced.” The contract also calls for new pump legs to tie in to the existing header pipe and, according to Mogadima, an unconfirmed possibility of replacing the existing header pipework. “We feel that the maximum design pressure, which is just under 30 bar, may create overburden on the current header pipework,” he explains. The upgrade, due for completion in August this year, includes soft starter and variable speed drive installation, power supply and switchgear modernisation, as well as replacing appurtenant valves. Veolia has been retained for a five-year monitoring and maintenance contract to meet specific MTBF and MTTR requirements.