Hong Kong’s water supplies are provided through a network of 7,800 kilometres (km) (4,847 miles) of water mains. Most of these water mains are underground, and a substantial portion were laid more than 30 years ago. They are progressively approaching the end of their service life and have become increasingly difficult and costly to maintain.
In view of this, Hong Kong’s Water Supplies Department developed a comprehensive and cost-effective management plan for the water supply network. The plan recommended the replacement and rehabilitation of some 3,000 km (1,864 miles) of aged water mains in stages, to prevent further deterioration of the water supply network. The water mains transfer treated water from the largest water treatment facility in Hong Kong to the heavily populated areas of Kowloon and Hong Kong Island.
Black & Veatch faced several complex problems on this project. One of the major constraints was getting access to the mains. Access to the pipe gallery via the shafts within the road tunnel was permitted for only 14 days a month and then only between 1:30 a.m. and 6:00 a.m. Major excavation of the carriageway was not allowed, and replacement was not possible. Because conventional rehabilitation techniques such as sliplining were also not feasible, Black & Veatch experts used innovative “in situ” trenchless technology methods within the pipe to get the job done.
Black & Veatch adopted the use of hand-applied, fibre-reinforced plastic for the rehabilitation of the mains. Relining was completed at an average rate of approximately 32 metres (104 feet) per day. Black & Veatch used innovative technology to improve the water mains’ condition and reliability, while also understanding the community, economic and environmental aspects of such a project.