10.05.2012 – KSB Aktiengesellschaft based in Frankenthal, Germany, is set to supply four 52 t waste water pumps for the construction of the Lee Tunnel in London. Each of these pumps will feature an impeller measuring 2.8 m in diameter. A total of six pump sets including two smaller drainage pumps will be installed in a shaft structure 85 m 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 V 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 7 km 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 7 m, the Lee Tunnel will be able to capture and temporarily store some 382,000m3 of stormwater. Its price tag of 675 million British pounds makes it the most expensive water project ever undertaken in the United Kingdom. It is scheduled for completion in 2015.