A superhighway for sewage treatment

Singapore is the world leader in sustainable water and sewage management. Around 30% of drinking water requirements are covered by seawater desalination plants, around 40% is obtained by means of state-of-the-art rainwater and sewage treatment. Only a small proportion still needs to be imported from neighboring Malaysia. And the Public Utilities Board (PUB) continues to invest in the efficiency of the infrastructure for the collection and treatment of sewage.

With the Deep Tunnel Sewerage System (DTSS) Phase II, deep underground beneath the city-state some 50 kilometers of new tunnel tubes are being built for this purpose. They serve to feed the sewage from the south and west into the new Tuas Water Reclamation Plant. No elaborate pumping stations are needed because thanks to an appropriately planned gradient, the sewage in the tunnels flows to the destination by itself.

20 x Herrenknecht

Herrenknecht is the only supplier of mechanized tunnelling technology for the DTSS II project. The contractors ordered 18 Mixshields and an EPB Shield with diameters between 4.50 and 7.56 meters to bore the sewage collectors at a depth of 35 to 55 meters and line them with concrete segments. A Vertical Shaft Sinking Machine (VSM) from Herrenknecht is used for the safe and fast construction of shafts with diameters of 10 to 12 meters and depths between 35 and 60 meters.

In close cooperation with the customers, Herrenknecht engineers adapted the design of the TBMs to the expected complex geological conditions. The planned tunnel runs mainly through the Jurong Formation with limestone, sandstone and argillite. In Lot T-08 the machines have to cross about 3.5 kilometers under an estuary to build the section leading to the Tuas Water Reclamation Plant.


  • Approx. 50 kilometers of sewage tunnels
  • Herrenknecht as the exclusive supplier of mechanized tunnelling technology
  • 18 x Mixshield, 1 x EPB Shield, 1 x VSM
  • Crossing under an estuary

20 years of Herrenknecht in Singapore

Since 1998, Herrenknecht machines have repeatedly been used in Singapore for the creation of tunnels for subways and electricity as well as for other sewage projects. From 2001 to 2005, five Herrenknecht EPB Shields excavated a good 28 kilometers in total of the tunnels for Phase 1 of the DTSS project in the eastern districts.

Singapore Deep Tunnel Sewerage System

Project data
Column 0 Column 1
Project Singapore Deep Tunnel Sewerage System Phase 2
Client Public Utilities Board
Contractor Ed. Züblin AG, Singapore Branch
Leighton Contractors (Asia) Limited (Singapore Branch)
Nishimatsu Construction Co., Ltd., Singapore Branch
Penta Ocean Construction - Koh Bros JV
Shanghai Tunnel Engineering Singapore
Geology Heterogeneous ground
Jurong Formation (Limestone, sand stone, mud stone, partly groundwater bearing)
Tunnelling length 47,968m
Machine data 18 x Mixshield:
Diameter: 4,500mm – 7,560mm
1 x EPB Shield:
Diameter: 4,789mm
1 x VSM
Diameter: 10,000mm – 12,000mm

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Jack Brockway President and CEO Herrenknecht Tunnelling Systems USA Inc.
Gerhard Goisser COO Herrenknecht Tunnelling Systems USA, Inc.

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Jack Brockway President and CEO Herrenknecht Tunnelling Systems USA Inc.
Gerhard Goisser COO Herrenknecht Tunnelling Systems USA, Inc.