Abu Dhabi prepares more tenders for super sewer scheme

06 April 2014

Contract covers installation of odour control systems

The project team on Abu Dhabi’s new 41-kilometre deep sewer tunnel is preparing to tender the construction of two new facilities to control odour in the new system.

“They are likely to be a design, build, operate type of system where whoever takes the contract will operate it for a few years,” says Alan Thomson, managing director at client body Abu Dhabi Sewerage Services Company (ADSSC).

“We have put a lot of emphasis on odour control for STEP [Strategic Tunnel Enhancement Programme] because of the sensitivities. It should be odour-free,” says Thomson, who explains that the scheme was modelled at Iowa University in the US to calculate how the sewage and the gases would flow through the new tunnel. “It was pushing modelling boundaries to the limit,” he says.

US-based CH2M Hill is programme manager for the scheme and says the new facilities will be let “in a month or so” and must be completed by the end of 2015.

The $1.6bn sewer tunnels are Abu Dhabi’s first mechanised tunnelling project using earth pressure balance machines of the type that will now be used on Doha’s metro. The 41km bore runs from the island, where it is 24 metres below ground, south to the mainland, where it descends to 80 metres.

The main tunnelling work was completed in October 2013 and was let through three major contracts. Two of these, led by Italy’s Impregilo, have now been concluded and the last package, led by South Korea’s Samsung C&T, will be completed by the end of 2014. Lining works are ongoing in this section.

Two further deals for 43km of linking pipework are now more than 50 per cent complete and are due to conclude in mid-2015. The contractor is Germany’s Ed Zueblin.

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