Following the award earlier this year of a major contract for the Singapore Metro Circle Line PSD have been asked to supply a slurry treatment plant to Hochtief Construction AG and Concor JV for the Durban Harbour Tunnel in South Africa.
South Africa’s National Ports Authority is planning to widen and deepen the entrance of Durban Harbour. Currently the movement of vessels in and out of the harbour is limited to one direction at a time, leading to delays. A new 4.5m internal diameter tunnel will carry two large diameter sewers, a water main, power cables, telecommunication cables and cable ducts for the new Durban lighthouse. The 520m long tunnel is to be excavated through marine sediments by Hochtief / Concor in 3 months using a Herrenknecht 5.1 m diameter slurry shield TBM. This machine is the same one used by China Harbour Transfield JV on the Kai Tak Transfer Scheme in Hong Kong, where PSD also supplied the slurry treatment plant. An option exists for the client to extend the contract with the construction of a second tunnel for “people-moving” and a decision on this is expected in the New Year.
The slurry treatment plant (STP) being supplied by PSD will be delivered to site before Christmas 2005 and assembled in January ready for the start of tunnelling in February 2006. The STP has a capacity of up to 900m3/hr and includes a steeply declined deck primary shaker, 2 No. high performance desanders, flocculation plant with 2 No. S3 centrifuges, mud mixing equipment, mud storage tanks together with all associated pumps, pipework, access platforms and stairways.
PSD will supply specialist personnel to supervise the assembly and disassembly of the plant and train the Contractor’s locally recruited operators to carry out the day-to-day working of the STP.