Largest Ever Stoplogs Installed in Hong Kong

As part of the new HK$1.7 billion (£128M) Lai Chi Kok Drainage Tunnel, Ham Baker Adams (part of F J Holdings Ltd) has completed the supply of the largest Stoplogs ever to be installed in Hong Kong.

Working with partners Biwater Man Lee, with whom it has established an unparalleled track record in Hong Kong for over three decades, Ham Baker Adams supplied Coplastix stoplogs and weir penstocks to Hong Kong’s Drainage Services Department (DSD) whose four-year high profile tunnel project now provides vital flood protection for northwest Kowloon.

The stoplogs provided by Ham Baker Adams were 13m at their deepest and 6m at their widest – the largest ever manufactured by the company. During rigorous site testing, the stoplogs had to withstand 13m head of water – for 24 hours.

The Ham Baker Adams’ penstocks, 2700 (W) x 2700 (D), one at the overflow weir wall and one (1886 W x 1180 D) at the inlet of low flow culvert, which are both provided with stainless steel covers, form an integral part of the project that included the design and construction of two storm water drainage tunnels (the main tunnel and the branch tunnel) with a total length of 3.7 kilometres, each with an internal diameter of 4.9 metres.

Gary Lau, Senior Manager (Sales) for Biwater Man Lee, commented: “Not for the first time in Hong Kong, the partnership between Ham Baker Adams once again proves that together we have the right people and the right tools to handle any special penstock installation. The Lai Chi Kok Drainage Tunnel has been particularly challenging, but as usual, Ham Baker Adams’ work with us, within an extremely tight program from preliminary design to installation, has been truly first class”.

Continuous urbanisation and development had meant that the capacity of the existing drainage system was no longer able to cope with increasing flows during heavy rainstorms.

Not only will the Lai Chi Kok Drainage Tunnel protect the low-lying urban areas of Sham Shui Po, Cheung Sha Wan and Lai Chi Kok itself, but it sets out the Hong Kong Development Bureau’s vision to make its city more ‘blue and green’. 

Stormwater collected in the stilling basin will be treated and used for gardening, toilet flushing and street cleansing for the Butterfly Valley Road Pet Garden. Fully utilising land resources, as the stilling basin of the tunnel was constructed under the viaduct of the Tsing Sha Highway, while the pet garden was built above the basin, it enables this piece of land to meet the needs of flood prevention, transportation and recreation – all at the same time. River works are also being carried out to include ecological features such as rainwater harvesting systems, green roofs and porous pavements to allow water infiltration.  Studies are also being carried out for storage lakes to reduce peak flow on the ground at source, so as to provide a more enhanced and natural drainage system.