Rehabilitation of Large Diameter Pressure Water Mains in Hong Kong – a Case Study

Abstract

Repair of large diameter pressure water mains is always a big challenge. In Hong Kong, a large diameter pressure water main is usually a trunk main serving a big area with a large group of people in a large region and is usually laid under busy roads. Such conditions impose many constraints to the related pipe repair project, such as limited pipe shut down period and limited space for access pits. The cost of repair is usually very high. This paper presents a project of Water Supplies Department of Hong Kong in which about 30km of Dongjiang mains and 11km of mains along Fan Kam Road are rehabilitated. It discusses the project constraints encountered along different parts of the pipeline, followed by how suitable on-line rehabilitation methods are selected. This paper then describes the method of Hand Applied Fibre Reinforced Plastic (FRP) Lining, which is one of the major on-line rehabilitation methods adopted in this project. This lining is formed by building up FRP sheets in layers and allows the optimization of using semi-structural lining and fully structural lining at different locations along the pipeline and hence saving is achieved.