Kranji Deep Tunnel Sewerage System (DTSS)
12.6 km tunnel from Kranji Sewerage Treatment Plant to approximately 1.3 km east of the Seletar Expressway flyover to Lentor Avenue. Along the proposed tunnel, there are 10 permanent access shafts, and the Odour Control Facility at the Kranji Sewerage Treatment Plant.
The primary lining consists of concrete segmental lining 250 mm thick with internal diameter 4100mm. Final cast-in-place concrete lining with HDPE corrosion protection membrane will be placed within the concrete segmental lining with a finished internal diameter 3600mm.
Two 4.93m diameter Herrenknecht EPB Tunnel Boring Machines (TBM) started excavation from base camp at Mandai Road, next to the Nee Soon flyover.
North TBM excavates towards Kranji Treatment Plant while South TBM excavates southwards to Lentor Avenue.