Tsuen Wan Drainage Tunnel breakthrough1 March 2012
Hong Kong’s USD 142M Tsuen Wan Drainage Tunnel broke through on 27 February. A spokesman for TBM manufacturer and JV partner Seli said the TBM and other facilities were already being dismantled as T&TI went to press.
Excavation of the 5.1km-long, 6.5m id tunnel began in March 2010 by a contracting JV of Maeda, CRGL and Seli. Geology was extremely strong and abrasive fresh rocks that included crystal ash tuffs of the volcanic group, Tai Po Granodiorite and a variety of crosscutting dykes that included basalt, rhyolite, fine-grained granite and quartz.
Sections of the excavation were 200m below the surface.
The 7.72m-diameter Seli double shield, hard rock TBM was equipped with probe drills to investigate rock and water ahead of the tunnel face. The cutterhead was equipped with 47 cutters with a 19-inch diameter and powered by eight 315kW motors. Breakout torque was 6,600kNm.
The project was commissioned by the Hong Kong Drainage Services Department following a severe flood in June 1997. It began in December 2007 and will be fully completed in 2013.
The tunnel was designed to cope with a one in 200 years rainstorm, a capacity of 210 cubic metres of water per second. An outfall will discharge the water into the sea at Yau Kom Tau on the north coast of Tsing Yi Island.
The 7.72m double shield breaks through Workers celebrate the end of the 5.1km drive