Second contract awarded for Abu Dhabi tunnel

Italian contractor Impregilo has confirmed that it has been awarded a second contract by Abu Dhabi’s Sewerage Services Company (ADSSC) for the construction of a 10km section of a 40km sewer tunnel. The $200M award was confirmed on 30 November with the firm beating bidders such as fellow Italian firm Astaldi, Germany’s Ed Zeublin, UAE based Lindenberg and French firm Bouygues Batiment International.

The 10km section will have a 7m external diameter with a 5.5m internal diameter. “In addition to the tunnel, the project involves construction of four access shafts to depths of between 60 and 80 metres, as well as the links to the main tunnel,” says the Impregilo statement on the contract which is expected to take three years to build. Rates of up to 100m per week are expected. “The project presents significant technical and organisational complexities. It involves simultaneous use of two earth pressure balance tunnel boring machines for pressures up to 8 bars, to bore and simultaneously line the tunnel with prefabricated concrete elements,” says the statement.

The contract is the second awarded to Impregilo, which this month (December) starting boring a 15km central section of the sewer worth AED 891 million (USD 243M). The award was made in September 2009 and involves three 6.3m diameter EPBMs. A further four contracts are also still to be awarded for the remaining sewer section, connecting tunnels and a major pumping station.