Trenchless technology in traffic corridor reduces impact to commuters
Black & Veatch has completed the rehabilitation of the first of five water mains that lie beneath the heavily trafficked Lion Rock Tunnel in Hong Kong Special Administrative Region (SAR). The company is using innovative trenchless technology for the Lion Rock water mains to reduce impacts to commuters.
“One of the major constraints on this project was getting access to the mains,” said Alan Man, Black & Veatch vice president and leader of the company’s water business in Hong Kong SAR. “Access to the pipe gallery via the shafts within the tunnel is permitted for only 14 days a month and then only between 1:30 and 6:00 a.m.”
The Lion Rock Tunnel is a vital component of Route 1 that connects Sha Tin in the New Territories and Kowloon. The five water mains that lie beneath the carriageway of the Lion Rock tunnel transfer treated water from the Shatin Water Treatment Works, the largest water treatment facility in Hong Kong, to the heavily populated areas of Kowloon and Hong Kong Island. The mains, which were built in the 1960s and ‘70s, are approximately 1.4 kilometers in length and range from 1.2 to 1.5 meters in diameter.
“Major excavation of the carriageway was not allowed and replacement was not possible,” Man said. “As conventional rehabilitation techniques such as slip lining were also not feasible, we had to use innovative in-situ methods within the pipe to get the job done.”
Black & Veatch adopted the use of hand-applied fiber-reinforced plastic (FRP) for the rehabilitation of the mains. Various trials and demonstrations on the FRP system were carried out on site. Relining of the first main was completed by mid-December 2008 at an average rate of approximately 25 to 40 meters per day. Final inspections and pressure tests were completed and the first water main was recommissioned in March 2009.
Work has now commenced on two other mains with all five mains targeted to be completed in early 2011.
“The Lion Rock Tunnel water mains are an essential component of Hong Kong’s water supply network,” Man said. “By using innovative technology, we are able to successfully rehabilitate these mains with minimal disruption to commuters who rely on the use of the tunnel every day.”
Hong Kong’s Water Supplies Department launched the Replacement and Rehabilitation Programme of Water Mains, one of the largest pipeline rehabilitation programs in the world, in 2000. The program aims to rehabilitate or replace a total of 3,000 km of water mains by 2015, at an estimated cost of $ 2.5 billion, improving the condition and reliability of Hong Kong’s water supply network.
Black & Veatch is responsible for replacing or rehabilitating approximately one-third of the pipelines in the overall program, and is involved in Stages 1, 2 and 4.