Pumps For a Green London

Four 52-tonne waste water pumps for the construction of the Lee Tunnel in London will be supplied by KSB Aktiengesellschaft (Germany). Each of these pumps will feature an impeller measuring 2.2 metres in diameter.

A total of six pump sets including two smaller drainage pumps will be installed in a shaft structure 85 metres below the Beckton Sewage Treatment Works in London – Britain's largest waste water and sewage treatment plant – and used to transport combined stormwater and sewage.

These wear-resistant white cast iron pumps will each be driven by a 6,600 volt motor with a drive rating of 3.4 MW, controlled by a frequency inverter. To keep these motors cool, the pump manufacturer will deploy heat exchangers specially engineered for this underground application. Compared with equivalent air-cooled systems, these heat exchangers will sharply reduce the amount of energy required to dissipate the thermal load.

The shaft structure will be located at the end of the nearly seven kilometre long Lee Tunnel, which itself represents the first stage of a huge construction project. The project goal is to prevent an untreated mix of stormwater and sewage from entering the Thames during periods of heavy rainfall. With a diameter of seven metres, the Lee Tunnel will be able to capture and temporarily store some 382,000 cubic metres of stormwater. Its price tag of £675 million makes it the most expensive water project ever undertaken in the United Kingdom. It is scheduled for completion in 2015. Once in operation, the pumps will be maintained and serviced by the service specialists from British-based KSB Limited.

By the final stage of construction, the tunnel will have a total length of 39 kilometres and around 40 shafts. It will follow the course of the Thames at a depth of 25 to 80 metres, making it the deepest tunnel in London and one of the deepest waste water tunnels in Europe. One major reason for selecting the KSB Group for this project was the company's successful experience in supplying equipment to similar-scale projects in Mexico, Russia and the United States.