Operating a Terratec 3.85m-diameter rock slurry TBM, tunnelling crews have broken through on Priority Sewer Tunnel 1 (PST-1). The TBM has been advancing steadily on the PST-1 alignment since achieving its first breakthrough in Malad West. Approximately 4.5km of tunnelling has been completed and the tunnelling machine is now being prepared for its final 1.2km drive to finish the remaining section of the tunnel.
The project, overseen by the Brihanmumbai Municipal Corporation, involves the construction of a 3,200mm finished internal diameter sewer tunnel with a total length of approximately 5.8km beneath densely developed areas of Mumbai. The alignment runs below busy road networks and existing residential and commercial developments, requiring careful control of excavation and ground behaviour to ensure safe construction with minimal surface impact.
Terratec says tunnelling is being carried out under challenging urban conditions, including close proximity to existing structures, buried utilities and environmentally sensitive areas. Comprehensive monitoring of tunnel alignment and ground movement has been implemented throughout excavation to minimise surface settlements and protect surrounding infrastructure.
Once completed, the sewer tunnel will form a critical part of Mumbai’s wastewater management system, conveying sewage to downstream treatment facilities and marine outfalls. The project will significantly reduce the discharge of untreated wastewater into local waterways and the Arabian Sea.
