W&F’s Emscher sewers

30 January 2012

Wayss & Freytag (W&F) of the Royal Bam Group has won a EUR 424M (USD 556.9M) contract for sewer construction work for the Emschergenossenschaft water services organisation.

Work includes deep shaft construction, slurry shield mechanised pipe jacking and open cut sewer laying in three lots (BA31-33) for sewers in Emscher, Bottrop and the Castrop-Rauxal industrial region, Germany. It is part of sewer section 30 in the huge AbwasserkanalEmscher project for improving management of drainage in the River Emscher basin and the clean up the river and it tributaries running into the Rhine.

The contract was awarded on the basis of 90 per cent weighting to economy of construction and 10 per cent to shortness of execution time to W&F’s Central Division in Dusseldorf.

The Emscher Sewage Canal project, which commenced in Spring 2010, comprises mainly 73km of new closed sewers (some a twin bores) and associated pumping stations. Depths range from 10 to 40m. The sewer diameters range from 1800/2000mm at the upper end of the project to 2.8m at the lower end. They are being made of steel-reinforced concrete, or using steel casing in tunnel.

In operation the sewers will be permanently filled to the bottom of the shafts, necessitating the use of robot cameras for inspections. To ensure free drainage, the inclination is 15:10 000, but with intermediate pumping stations to prevent depths that would be too great. The pumping stations are being constructed in 40m-deep circular shafts within concrete piles or diaphragm walling.

The Emscher conversion project, the largest environmental project in the European Union, requires a total investment of EUR 4.4bn (USD 5.78bn) over 30 years, of which around EUR 2bn (USD 2.6bn) has been spent so far on four treatment plants and 200km of sewers to purify 50km of waterways.

Cities that will be affected range from Holzwickde and Dortmund down to Essen, Oberhausen and Dinslaken. Bochum and Duisberg will also benefit although they are on tributaries rather than the River Emscher itself.