Terratec is the sole supplier for the project’s segmental tunnels, providing two TBMs. J Kumar and Michigan Engineers Private Ltd (MEPL) Joint Venture will use the rock slurry TBM and a rock EBPM to build the 5.8km Mumbai Priority Sewer Tunnel (PST-1) and the 4.7km Priority Sewer Tunnel (PST-2) respectively.
The 3.85m diameter rock slurry TBM was launched from the Malad Shaft S07 Pumping Station. It will bore through a range of geology, including weather/fresh breccia and basalt, and achieve a daily excavation rate of up to 14 rings when encountering fresh rock.
It features a slurry system controlling excavation face pressure, 23 38cm replaceable disc cutters, a high-speed main drive capable of 8rpm, and an active articulation system accommodating a minimum curve radius of 250mR. The TBM’s hydraulic main drive includes a shield integrated man lock.
The TBM employs a 5+1 universal type segment design, featuring reinforced concrete segments 200mm thick and 1200mm wide. The Terratec Slurry Transportation System and Slurry Treatment Plant are used for slurry removal and treatment.
The system uses a centrifugal slurry pump for effective slurry removal, while the Slurry Treatment Plant incorporates mud treatment technology and a remote-control maintenance system. Terratec says this combination provides efficient excavation over long distances and is also cost-effective throughout the process.
The MSDP – Stage II Priority Works project include a sewer tunnel to the existing Malad Pumping Station. Another branch sewer tunnel connects from the Gorai Pumping Station, and a tunnel runs from the existing Malad Pumping Station to the proposed Malad IPS at Malad WwTF. This project involves constructing shafts and upstream connections to reduce wastewater flow into existing collector sewers and decommissioned pumping stations.
The project will expand sewage collection networks, provide new pumping stations, wastewater treatment facilities and treated effluent disposal systems. These treatment plants are projected to recycle 2.464 million litres of sewage per day, reducing water pollution levels and improving water quality in Mumbai’s Mithi and Oshiwara rivers.
In a related development, a refurbished Terratec 3.14m diameter EPBM is building the Mithi River Water Quality Improvement Tunnel. Previously used for the completion of the Mumbai Sewer Disposal Project (MSDP) Stage-II Priority Works, it is expected to make its second breakthrough next week. Operated by a J Kumar Infraprojects and MEPL joint venture, the EPBM has achieved a monthly advance of 370m.
