Mumbai Awards Afcons $200M Deep Water Tunnel

Water Infrastructure Mumbai Awards Afcons $200M Deep Water Tunnel Twin-TBM conveyance project in tidal creek will connect to planned major desalination plant Mumbai’s municipal government has awarded locally-based Afcons Infrastructure Ltd. a roughly $200-million contract to build a 4.5-mile tunnel connecting a planned seawater desalination plant on the city’s northwest coast with its water network. Afcons said Aug. 6 it received a letter of acceptance from Brihanmumbai Municipal Corp., or BMC, for design and construction of the conveyance tunnel serving the planned Manori desalination plant. From the coastal plant site, the tunnel will be built east beneath a tidal creek separating Manori from the mainland before continuing through Mumbai’s western suburbs to the existing water system. The alignment will descend as deep as about 420 ft, with two tunnel boring machines working simultaneously from opposite ends, according to municipal firm officials. The city has set a 45-month design-build period but has not publicly confirmed when it will issue an order to commence work. Deep Below a Tidal Creek Inland from Manori, the alignment passes an intermediate shaft in Mumbai’s western suburbs before reaching Mahavir Nagar and the existing distribution system. Procurement requirements call for at least six boreholes extending about 425 ft along the alignment and a separate investigation beneath the creek reaching about 394 ft. One engineering detail remains unresolved. BMC procurement information describes an approximately 8.2-ft finished tunnel diameter, while later local reports citing municipal officials state it at about 10.5 ft. Neither BMC nor Afcons has publicly explained the difference. Additional shafts are planned at Manori and Charkop, although municipal officials have said no water will be withdrawn at the Charkop location. Looking for quick answers on construction and engineering topics? Try Ask ENR, our new smart AI search tool. Ask ENR → Beyond the tunnel itself, Afcons’ scope includes a pumping station, transmission mains, treated-water storage, valve chambers and supervisory control and data acquisition, or SCADA, systems. Initial mechanical and electrical equipment at the pumping station will handle about 53 million gallons per day, while the facility is being designed for eventual capacity of about 106 million gallons per day. A map of Mumbai’s northwest coast shows Manori on the seaward side of the tidal creek and Charkop on the mainland, along the route of the planned deep conveyance tunnel. Map courtesy of ResearchGate That capacity mirrors the separately procured desalination plant, part of a broader $426-million desalination program now in preconstruction. BMC selected GVPR Engineers to build the reverse-osmosis facility, which is planned to begin at about 53 million gallons per day and eventually double output. At the coast, the plant complex will include seawater intake and brine-discharge infrastructure, treatment systems, pumping and associated electrical and mechanical works. Separate intake and outfall tunnels are planned to extend offshore into the Arabian Sea. The added supply would be meaningful for a system that currently delivers about 1.04 billion gallons per day, about 15% below estimated demand. Manori’s first phase would equal 5% of current supply and roughly one-quarter of the existing shortfall; full buildout would raise those shares to about 10% and more than half, respectively. “Climate change is another major concern, and it is very important that Mumbai has diverse water source portfolios,” P. Velarasu, then BMC additional commissioner for projects, told the Hindustan Times as the project moved through development. The Manori supply could also change how the municipal company moves water across the city. Officials estimate it could replace about 50 million gallons per day now routed from the Bhandup treatment system to the western suburbs, freeing that capacity for other parts of Mumbai and its 12.5 million residents.