Speech By Mr Masagos Zulkifli, Minister for the Environment and Water Resources, at Launch of Tunnel Boring Machine (TBM) for Deep Tunnel Sewerage System Phase 2, on 4 April 2019

Distinguished guests,

Ladies and gentlemen,

1. I am pleased to join you today to mark the commencement of tunnelling works for Phase 2 of the Deep Tunnel Sewerage System, or DTSS. This is another key milestone in one of Singapore’s most significant water infrastructure projects. 

2. A total of 19 tunnel boring machines will be deployed for this phase of the project. The machines will dig deep underground to create a network of tunnels and link sewers to serve the western and downtown parts of Singapore. Some $2.3 billion will be devoted to this endeavour. That’s nearly a third of the $6.5 billion price tag for the entire DTSS Phase 2. This is a significant and necessary investment to meet our population’s long-term water needs and enhance the sustainability of our water supply.


3. For a highly urbanised and densely populated city state like Singapore, a proper wastewater management system is important to protect our environment, public health and water sources. The DTSS allows us to transform our used water system to support Singapore’s growing water needs and ensure an effective and efficient sewerage system for Singaporeans. This is why PUB undertook the project.

4. Borne out of a bold vision conceived some 25 years ago, the DTSS is a powerful example of how, by planning decades ahead, and investing in innovative solutions, we can overcome challenges and turn them into opportunities. The DTSS is also an example of how we have applied circular economy strategies successfully in our water system. By conveying used water entirely via gravity to centralised water reclamation plants for treatment and recycling into NEWater, every drop of used water will be continually reused, closing our water loop. The risk of cross-contamination between Singapore’s water catchments and used water system will also be minimised.   

5. DTSS Phase 1 was completed in 2008 to serve the eastern part of Singapore.  Under Phase 2, the DTSS will serve the western and downtown areas, including upcoming developments such as the Jurong Lake District, Tengah Town and the Greater Southern Waterfront. A 100km network – comprising 40km of deep tunnels and 60km of link sewers – will be built. All five deep tunnel contracts have been awarded, and six out of 13 contracts for the link sewers have been awarded.

6. When construction of Phase 2 concludes by 2025, the whole of Singapore will be served by the DTSS, and it will be one of the largest integrated underground sewerage system in the world. It took hard work by many engineers to realise this vision. I am happy that some of the pioneers of the DTSS project are here with us today. Please join me in thanking them for their contributions.

7. The DTSS will bring tremendous economic benefits for Singapore. Existing water reclamation plants and pumping stations, as well as buffer land around the reclamation plants, will be phased out when they reach the end of their economic lifespans, freeing up space for higher value developments. Some 150 hectares of land – about the size of 214 football fields – will be made available.


8. The deep tunnels and link sewers will convey used water to the future Tuas Nexus. As an integrated used water treatment and waste management facility, Tuas Nexus will harness synergies from the water-energy-waste nexus by co-locating PUB’s Tuas Water Reclamation Plant and NEA’s Integrated Waste Management Facility. When completed, the Tuas Nexus facility will achieve high energy self-sufficiency, by co-digesting used water sludge and food waste to improve biogas yield and energy efficiency in used water treatment.


9. Besides being part of a sustainable water system, DTSS Phase 2 will also be a smart and safe sewerage system. 

10. During construction, the DTSS team will be using a smart monitoring system to monitor and gather real-time information on the construction progress, and location of the tunnel boring machines and pipe jacking machines during the tunnelling works.

11. Once the tunnels are completed, the use of Remotely Operated Vehicles and embedded fibre optic cables will allow for remote monitoring. This minimises the need for officers and contractors to enter the shafts, improving overall work safety. If maintenance is needed, individual segments of the tunnel can be isolated to prevent any disruption to water flow. This is also the first project to use a combination of air jumpers and odour control facilities to prevent odorous air from escaping into the surroundings.

12. These deep tunnels will have enhanced resilience thanks to a special concrete mix that will offer better protection against corrosion from sewage gases. Underwater sections of the deep tunnel at Tuas Bay and Sentosa will have an additional waterproof membrane to ensure the tunnel is water-tight.


13. The construction of DTSS Phase 2 is a challenging project. We will have to navigate the different ground conditions in the Jurong Formation and dig deep to tunnel beneath existing underground infrastructure. But I am confident that our team of skilled engineers are up to the task. PUB’s senior engineer Loh Siew Hui, who oversees the planning and construction of one of the deep tunnel segments, is one of them. Siew Hui is an experienced hand when it comes to tunnelling work, having also been involved in PUB's sewer and NEWater pipeline projects. She is an excellent example of how our engineers have acquired the knowledge and skills to take on larger, more complex and world-class projects.


14. Tunnelling works for DTSS Phase 2 will commence shortly after today’s event. I wish the DTSS team every success, as we work together to enhance the sustainability of our water resource, and write the next chapter of our Singapore Water Story.

Thank you.

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