The Deep Tunnel Sewerage System (DTSS) is an efficient and cost-efficient solution to meet Singapore’s long-term needs for used water collection, treatment, reclamation and disposal. Conceptualised and managed by PUB, it was conceived as a cost-effective and sustainable solution to meet Singapore’s long-term used water needs.
The overall concept of the DTSS is to use deep tunnels to intercept the flows in existing gravity sewers, upstream of the pumping installations, and channel the flows by gravity to centralised treatment facilities strategically located at coastal areas. The used water is then treated and further purified into ultra-clean, high-grade reclaimed water called NEWater, or discharged to the sea through the outfalls.
The DTSS is a more cost-effective solution than renewing and expanding the existing used water infrastructure, and would free up land for other developments in Singapore. In the long term, it is envisaged that the integrated used water system will consist of three centralised WRPs: Changi WRP in the east, Kranji WRP in the north and Tuas WRP in the west to serve Singapore’s used water needs.
Crowned ‘Water Project of the Year’ at the Global Water Awards 2009 in Zurich, Switzerland on 28 April 2009, the DTSS was selected as the water project with the most significant contribution to water technology and environmental protection. The annual Global Water Awards is widely recognised as one of the most prestigious symbols of achievement in the global water industry.
PUB's Chief Executive, Mr Khoo Teng Chye (third from left) together with (from left) Mr Joaquín Fernández de Piérola Marín, Business Development and Investments Division International Director, Befesa Agua, Dr Glen T. Daigger, Senior Vice President and Chief Technology Officer, CH2M HILL at the 2009 Global Water Awards where PUB's Deep Tunnel Sewerage System was recognised as the Water Project of the Year.
Benefits of DTSS
Compact Design and Efficient Land Use
The DTSS optimizes land use by used water infrastructures. The phasing out of existing intermediate used water pumping stations and the conventional plants makes the previously occupied lands available for other higher value developments. Under DTSS Phase 1, the compact design of the Changi Water Reclamation Plant (Changi WRP) requires only one-third the land area of a conventional plant. There is also no need for a buffer zone, as the plant modules are fully covered. Additional land savings are also achieved by integrating Changi NEWater Factory on the rooftop of Changi WRP’s Liquid Modules.
The implementation of the entire DTSS will result in a 50% reduction in land taken up by used water infrastructure once it is fully completed. Land used to site the WRPs and the accompanying pumping stations has shrunk from 300 ha in the 1990s to 190 ha with the completion of DTSS Phase 1. With Phase 2 in place, the land needed for the WRP and pumping stations will eventually be reduced to about 150 ha.
2) Environmental Protection
With DTSS, the phasing out of intermediate pumping stations not only free up land for higher value development, it also enhances the reliability of the used water system by minimizing the risk of environmental contamination as many such existing stations lie within the clean water catchment areas, especially since 2/3 of Singapore is water catchment today.
3) Ensuring NEWater Sustainability
DTSS is an important component of Singapore’s water management strategy as it allows every drop of used water to be collected, treated and further purified into NEWater, Singapores own brand of reclaimed water. NEWater is the pillar of Singapores water sustainability. Together with three other sources water from local catchments, imported water and desalinated water they form the Four National Taps, PUBs long-term water supply strategy to ensure a robust and sustainable supply of water for Singapore.
Singapore’s largest NEWater plant to date is built on the rooftop of the Changi Water Reclamation Plant, the first of its kind in the world. Integrating the NEWater plant with the DTSS allows for efficient, large-scale water recycling, thus ensuring the sustainability of NEWater.
Opened in May 2010, this NEWater plant at Changi has a capacity of 50mgd. With this addition, coupled with the expansion of the existing three NEWater plants, NEWater now meets 30% of Singapore’s total water demand.
4) Growing Singapore’s Industry Capabilities
Over 300 local and international contractors, subcontractors and suppliers have worked on the construction of the DTSS Phase 1. The experience enabled them to build their track record and pitch for bigger projects in Singapore and overseas.