On 8 March the South Drive on contract T-05 of the Singapore Deep Tunnel Sewerage System (DTSS) broke through to complete its 4.9km drive through variable ground conditions.
Contractor SembCorp used a 4.93m diameter Herrenknecht EPBM for the tunnel, which has a finished i.d. of 3.6m. Extreme variations along the alignment, from very hard to completely decomposed granite, posed many challenges for the contractors – the design constraints of a gravity flow sewerage system meant the alignment could not be altered.
