Tunnelling begins on underground sewage superhighway

A PUB site at Jalan Bahar, where a tunnel boring machine was launched as part of the second phase of the Deep Tunnel Sewerage System project on April 4.
A PUB site at Jalan Bahar, where a tunnel boring machine was launched as part of the second phase of the Deep Tunnel Sewerage System project on April 4.ST PHOTO: GIN TAY
The 16m-wide and 35m-deep shaft at Jalan Bahar, the site of the Tunnel Boring Machine's launch on April 4.
The 16m-wide and 35m-deep shaft at Jalan Bahar, the site of the Tunnel Boring Machine's launch on April 4.ST PHOTO: GIN TAY
(From left) German Ambassador Dr Ulrich, founder and chairman of Board Herrenknecht Martin Herrenknecht, Minister for the Environment and Water Resources Masagos Zulkifli and PUB chief executive Ng Joo Hee touring the site of Tunnel Boring Machine at
(From left) German Ambassador Dr Ulrich, founder and chairman of Board Herrenknecht Martin Herrenknecht, Minister for the Environment and Water Resources Masagos Zulkifli and PUB chief executive Ng Joo Hee touring the site of Tunnel Boring Machine at Jalan Bahar on April 4.ST PHOTO: GIN TAY
The tunnel boring machine, which will burrow through the ground to create tunnels 3.5m in diameter below the surface.
The tunnel boring machine, which will burrow through the ground to create tunnels 3.5m in diameter below the surface. ST PHOTO: GIN TAY
(From left) PUB Chief Executive Ng Joo Hee, founder and chairman of Board Herrenknecht Martin Herrenknecht and Minister for the Environment and Water Resources Masagos Zulkifli looking at the deep tunnel sewerage system model.
(From left) PUB Chief Executive Ng Joo Hee, founder and chairman of Board Herrenknecht Martin Herrenknecht and Minister for the Environment and Water Resources Masagos Zulkifli looking at the deep tunnel sewerage system model. ST PHOTO: GIN TAY

SINGAPORE - Tunnelling work has begun on a massive underground sewage superhighway in western Singapore – the most ambitious project of its kind here to date. 

On track to be completed in 2025, the underground labyrinth of pipes will comprise 40km of deep tunnels and 60km of link sewers, traversing 100km across the western half of Singapore, including the downtown area and some new developments in the Jurong Lake District, Tengah Town and the Greater Southern Waterfront.

Waste water will be conveyed via gravity to centralised water reclamation plants for treatment and recycling into Newater.

Highlighting the economic benefits of DTSS phase 2, the PUB said it will allow allow 150 hectares of land, about the size of 214 football pitches, to be made available, as older existing water reclamation plants and pumping stations around the island are phased out.

These include the conventional water reclamation plants at Ulu Pandan and Jurong and the intermediate pumping stations. 

Work officially began on Thursday (April 4) at a PUB site in Jalan Bahar with the launch of the first tunnel boring machine, which will burrow through the ground to create tunnels 3.5m in diameter below the ground.

It is the second phase of the DTSS (Deep Tunnel Sewerage System) project, where the PUB, Singapore's national water agency, will break new ground in a bid to make Singapore's water systems more sustainable.

The first DTSS was completed in 2008, to serve eastern Singapore.

Tunnelling work on phase two of the DTSS is targeted to be completed by 2024, after which used water from homes, offices, and industries will be conveyed via two tunnels – the 30-km long South Tunnel, which is for domestic use, and the 10km Industrial Tunnel, for industrial use.

This waste water will go the Tuas Nexus, for treatment and recycling into NEWater. 

Phase two of the DTSS project will cost $6.5 billion in total, with $2.3 billion devoted to a total of 19 tunnel boring machines that will be deployed to dig deep underground to create a complex network of tunnels and link sewers.

 
 
 
 

Minister for the Environment and Water Resources Masagos Zulkifli officiated the launch of the DTSS Phase 2 tunnel boring machine. 

"This is another key milestone in one of Singapore's most significant water infrastructure projects. It is a significant and necessary investment to meet our population's long-term water needs," Mr Masagos said.

Mr Masagos mentioned that the DTSS would allow for every drop of used water to be continually re-used.

He added that these deep tunnels and link sewers will convey used water to an integrated used water and waste management plant: the future Tuas Nexus.

He said the DTSS will also have some economic benefits. The project will allow for some 150 hectares of land, about the size of 214 football pitches, to be made available, as older existing water reclamation plants and pumping stations around the island are phased out.

He added: "The DTSS will transform our used water system, to support our growing water needs, and ensure an effective and efficient sewerage system for Singaporeans."

This phase of the DTSS will also be the first time that smart tunnel monitoring systems and fibre optic sensors will be used to detect problems before they pose risks. 

For instance, a smart tunnel monitoring system known as the Shaft and Tunnel Excavation System (STEMS) will act as a nerve centre, providing real-time updates on the location of the tunnel boring machines, making sure that operations throughout the construction period remain safe and go smoothly, with minimal disruption to urban structures above. 

There will also be a fibre optic system in place to monitor the structural integrity of tunnel linings. Additionally, isolation gates will be put in place to allow parts of the tunnel to be sectioned off for repair work. 

The DTSS phase two will also be the first project in Singapore to use  ventilation equipment called air jumpers, which manage air flow in the tunnel, by push odorous air further downstream to be treated at an odour control facility.