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Rock slurry TBM starts on Mumbai sewer drive
Contract awarded for DC Water project US – DC Water has awarded the Potomac River Tunnel design-build contract to a joint venture of CBNA and Halmar. The US$819m contract covers
construction of an 5.5 miles-long (8.9km) tunnel to control combined sewer overflows (CSOs) to the Potomac River in the US capital. It is part of the larger Clean Rivers Project, a programme to improve the water quality of the Anacostia and Potomac rivers and Rock Creek by increasing the capacity of the sewer system. The Anacostia River and Potomac River
tunnel systems include more than 29km of tunnels. The 18ft-diameter (5.5m) Potomac
Above: Terratec rock slurry TBM launched on sewer tunnel drive in Mumbai PHOTO CREDIT: TERRATEC
INDIA – Terratec’s 12.6ft-diameter (3.85m) rock slurry TBM on the Mumbai Sewer Disposal Project (MSDP) Stage II (PST1) has been launched. Contractor is a JV of J Kumar
and Michigan Engineers Private Ltd (MEPL) which will use the TBM and also a rock EBPM, also from Terratec, to build the 3.6 miles-long (5.8km) Mumbai Priority Sewer Tunnel (PST-1) and the 2.9 miles- long (4.7km) Priority Sewer Tunnel (PST-2), respectively. The rock slurry TBM was recently
launched from the Malad Shaft S07 Pumping Station. Geology along the alignment comprizes weathered/fresh breccia and basalt. The JV contractor anticipates daily progress rates of up to 14 rings when encountering fresh rock. The TBM employs a 5+1 universal
type segment design, featuring reinforced concrete segments 200mm thick and 1200mm wide. A slurry system controls
excavation face pressure and the cutterhead is equipped with 23 x 38cm replaceable disc cutters. The machine has a high-speed main drive capable of 8rpm, and an active articulation system accommodating a minimum curve radius of 250m. Its hydraulic main drive includes a shield integrated manlock. The Terratec Slurry
Transportation System and Slurry
Treatment Plant are used for slurry removal and treatment, which Terratec says is combination for an efficient and cost-effective excavation over long distances. The MSDP – Stage II Priority
Works Project includes 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 10.3ft- diameter (3.14m) EPBM is building the Mithi River Water Quality Improvement Tunnel. It was previously used on the Mumbai Sewer Disposal Project (MSDP) Stage-II Priority Works.
River Tunnel will connect by gravity to the existing Anacostia River Tunnel. Construction will require two TBMs, one to be launched from West Potomac Park to bore south through mostly soft ground, the other machine to head north to drive through rock. Work is expected to start in 2024 for
completion in 2030. The Clean Rivers Project is a
gamechanger for the District,” said DC Water CEO and general manager David L Gadis. “We have already seen the impact the completed Anacostia River tunnel system is having on the health of that river, and we expect similar results for the Potomac as a result of this project.”
STM issues final call for tunnel tender CANADA – Société de Transport de Montréal (STM) recently issued a final call for tenders for tunnel construction on the Blue Line metro extension. Given the complexity of the contract, a two-stage call for tenders was used. The contract includes: ● detailed design, supply and operation of the TBM
● construction of the tunnel between Pie- IX and Anjou West using a TBM
● construction of the tunnel between Pie-IX and the tail tracks of the current Blue line using conventional tunneling methods
● excavation of Pie-IX (main entrance building only), Viau and Lacordaire stations and some auxiliary structures
Following the discussion process with bidders, the timetable was extended so the Blue Line extension will not be finished before 2030.
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