TERRATEC Rock Slurry TBM Completes Mumbai’s Priority Sewer Tunnel 1. TERRATEC announced that its Ø3.85m Rock Slurry Tunnel Boring Machine (TBM) achieved final breakthrough on Oct. 9, 2026, at Don Bosco Junction, near Borivali West, completing excavation of the 5.85-km Priority Sewer Tunnel 1 (PST-1) for the Mumbai Sewage Disposal Project (MSDP) Stage II. The tunnel was constructed by J. Kumar–MEPL JV for the Brihanmumbai Municipal Corporation (BMC).