JKIL – MEPL’s Terratec TBM Records 2nd Breakthrough for Mumbai Sewage Project

J Kumar Infraprojects – Michigan Engineers JV this week celebrated their second tunnel breakthrough in Borivali West for Mumbai city’s 5.8 km Priority Sewer Tunnel (PST-1) project.

Mumbai’s PST-1 tunnel project by Brihanmumbai Municipal Corporation (BMC) connects Don Bosco Junction in Borivali West and Malad Waste Water Treatment Facility (WWTF). Along with PST-2 tunnel (Oshiwara Bus Depot to Malad Pumping Station), it aims to improve the quality and reliability of wastewater collection, treatment, and disposal processes, while minimizing the environmental impact caused by wastewater.

This week’s major milestone was recorded by Terratec tunnel boring machine (TBM) S112 nicknamed Manu 1. This 3.85m diameter machine is India’s smallest diameter rock slurry TBM.

S112 was originally launched in January 2024 from Malad WWTF (Shaft S07) and arrived at Malad Pumping Station (Shaft S06) in August 2024 to complete a 1630 meter long tunnel. It was then relaunched towards northwards towards Borivali’s Don Bosco Junction to build another roughly 2870m tunnel where it arrived this week.

Per Terratec’s old press release from June 2023, S112 is designed to handle various geological conditions along the tunnel alignments consisting of weathered/fresh breccia and basalt. The TBM has 23 rings of 15” replaceable disc cutters and a high-speed main drive which is capable of turning the cutter head at up to 8 revolutions per minute. The TBM is equipped with an active articulation system to accommodate a minimum curve radius of 250mR. The TBM’s main drive is hydraulic due to size constraints and the installation of a shield integrated man lock.

With this development roughly 4.5 km out of 5.8 km of tunnels have been built, and the machine is now being readied for its final roughly 1.2 km drive.

Terratec is the sole supplier for Mumbai’s sewage segmental tunnels and has provided 2 TBMs – S112 for 5.8 km PST-1 (Don Bosco to Malad WWTF) and S116 for 4.7 km PST-2 (Oshiwara Bus Depot to Malad Pumping Station).

S116 (Manu 2) is a 3.14 diameter EPB machine and started tunneling in August 2024 from Malad Pumping Station towards Oshiwara Bus Depot in Goregaon. Back in May 2025, it completed building a sharp 87m radius curve under the Mumbai Metro’s elevated Line-2A (Yellow Line)’s piers 393 and 394.

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– TMRG