Pipejacking breakthrough on Singapore link sewer

28 September 2021

Contractor Zublin Singapore has announced a breakthrough at Shaft N3 of the Deep Tunnel Sewerage System Phase 2 (DTSS2) which will serve the western part of the country.

Seen as an important project milestone, the Zublin Link Sewer–S2 C2 project team completed the connection between the DTSS link and the main sewer. The pipe-jacked drive has an inner diameter of 3m between Shaft 2A-MH08 to Shaft N3 (by DTSS2 T-09) and was achieved in the final week of September. As one of numerous link sewers totalling 60km in length, it will channel used water flows from the existing shallower sewerage network to the new deep tunnel.

The 100km DTSS Phase 2 conveyance network comprises the South Tunnel which conveys domestic used water, the Industrial Tunnel for non-domestic used water, and associated link sewers. The mammoth project involves a total of 19 TBMs (18 mix shield, 1 EPB) of diameters up to 7.56m, and one 10-12m diameter VSM for sinking shafts, all supplied by Herrenknecht. The project’s various alignments run through the mainly heterogeneous soils of the Jurong Formation comprising limestone, sandstone, clay stone, and groundwater.

Seen as a sewer ‘super highway’, the DTSS conveys used water entirely by gravity through deep tunnels to three coastal treatment plants. DTSS Phase 2 will serve the western part of Singapore and is targeted for completion and operation in 2025 when it will link with Phase 1 (eastern part) which was completed in 2008.