Officials in Hong Kong are planning three drainage tunnels worth a total of US$700M, which are likely to create a mini-tunnelling boom when construction begins next year.

Maunsell Consultants Asia has already invited contractors to prequalify by 22 June for the first job – the US$145M design and construction of the Lai Chi Kok transfer tunnel in Kowloon.

Budget approval is also expected for two other schemes, the US$390M Hong Kong Island drainage tunnel and the US$165M Tsuen Wan drainage tunnel.

The Lai Chi Kok transfer tunnel will be 3.7km long, 4.9m i.d. and transfer water between two reservoirs. Included are adits, drop shafts, intake structures, a stilling basin and an outfall structure. Work is to run from March 2008 to December 2011.

Arup is to seek expressions of interest for design and construction of the 11km long Hong Kong Island tunnel. The 6.25m-7.25m Ø tunnel will run from Tai Hang to Pokfulam, and about 8km of adits and 34 intakes are needed. Construction is to run from October to March 2012.

Construction is also due to start in October for the third, 5km long, tunnel. The 6.5m Ø bore is to run between Tsuen Wan and Kwai Chung in the New Territories, and needs 80m of adits and three intakes. Construction is to be completed by September 2011.