Singapore’s national water agency PUB has appointed three contractors – Ed Zublin AG (Singapore Branch), Penta-Ocean Construction Co Ltd and Koh Brothers Building & Civil Engineering Contractor (Pte) Ltd Joint Venture, and Leighton Contractors (Asia) Limited (Singapore Branch) – to design and build the first batch of 30 km of deep tunnels and link sewers for the Deep Tunnel Sewerage System (DTSS) Phase 2. These are part of a network of 40 km of deep tunnels and 60 km of link sewers for DTSS Phase 2, which will be built using the tunneling method.

According to PUB, the subsequent contracts to build the rest of the deep tunnels and link sewers will be awarded from 2018.

The contractors were appointed following a pre-qualification and tender exercise in mid-2016, with the three contracts valued at a total of S$1.51 billion. Over the next seven years, they are expected to develop the detailed design and construct some 30 km of deep tunnels and link sewers as well as the associated ancillary structures.

This network of 100 km of deep tunnels and link sewers will connect to the Tuas Water Reclamation Plant (WRP), which is scheduled for completion in 2025. By then, the whole of Singapore is planned to be served by the DTSS. Used water will be conveyed from the DTSS via gravity to three centralised WRPs for treatment, before it undergoes further purification to produce NEWater, or discharged into the sea.

The DTSS is a core water infrastructure that provides a cost-effective and sustainable solution to support Singapore’s continued growth and meet its long-term needs for used water collection, treatment, reclamation and disposal.

Under DTSS Phase 2, a NEWater factory to be integrated with the Tuas WRP will be built to facilitate water recycling, contributing to the goal of increasing NEWater supply from 40 percent to up to 55 percent of total water demand in the long term. Tuas WRP will also be co-located with NEA’s Integrated Waste Management Facility (IWMF), to harness potential synergies.