Singapore is building the Deep Tunnel Sewerage System (DTSS) to meet its long-term need for sustainable wastewater collection, treatment, reclamation and disposal. Once Phase 2 is complete by 2025, the DTSS will serve the whole of Singapore and result in a 50% reduction in land uptake by used water infrastructure (the equivalent of about 214 football fields).
The scheme uses deep tunnel sewers to convey used water by gravity to water reclamation plants, where it is purified into ultra-clean, high-grade reclaimed water, or discharged to the sea through outfalls.
Singapore’s densely populated urban environment makes DTSS a highly complex project with major design challenges – the work site is highly constrained, with deep shafts required in challenging geology adjacent to major civil infrastructure. Together with CPG Corporation, COWI is working closely with the contractor to develop unique solutions to minimise the social and environmental impacts of the project. This includes investigating options to combine temporary work shafts to minimise land take and designing ground improvement measures to reduce any impact on adjacent structures.