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Abu Dhabi to issue tender on $1.5bn STEP project

Tender is for odour control facililties at massive wastewater project.

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A view of AUH's STEP project.
A view of AUH's STEP project.

CH2M Hill is to issue tender documents in the next month or so for two large regional odour control facililties at the $1.5bn Strategic Tunnel Enhancement Program (STEP) in Abu Dhabi, set to be one of the world's largest wastewater systems when it's commissioned in late 2015.

The program will feature three key components, a 41km-long deep sewer tunnel, 43km of smaller diameter link sewers, and a 30m³ per second capacity pumping station located at the end of the deep tunnel sewer.

Link sewers will be used to intercept the flows from existing gravity sewers upstream of the existing pumping stations. The flows will be channelled by gravity via the deep tunnel sewer to the main pumping station, then lifted to central wastewater treatment facilities.

Back in 2011, CH2M Hill was engaged by pumping station contractor Odebrecht Construction to provide design and constructing supervision, and permitting and authority approvals.

Richard Bryant, business development lead facilities & urban environments, MENAI region, for CH2M Hill, said it had closed out Contracts T-02 and T-03 – the two Impregilo deep tunnel contracts – and T-01 will be completed by the end of this year.

All 41km of deep tunnels have been excavated without a single incident – the last breakthrough was last October. T-01 is now approximately 50% through the secondary lining.

He said: “Over 50% of the 43km of link sewer has been pipejacked – the two Zublin contracts should be complete by mid 2015 – although there is now an additional 3.1m internal diameter section of link sewer connecting Al Reem Island into the system, which will extend the completion of contract LS-01 to the end of 2015.

“We have nine TBMs (tunnel boring machines) of varying sizes on the link sewers, so with the eight TBMs on the deep tunnel contracts, we have used a total of 17 TBMs on the programme.”

By Yamurai Zendera, Construction Week.

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