China Road and Bridge, in turn, engaged L&M to be the specialist contractor to construct about 97.8 m long drain pipes from Man Cheong Street to Saigon Street, crossing Ferry Street and Wai Ching Street.

Construction Works
Started the works in December 2003, L&M adopts the pipe jacking with hand shield method to install the drain pipes under the busy streets with congested underground utilities and heavy pedestrian traffic. According to Mr. Tai Hok Hoi, Manager of L&M㏒s Geotechnical Division, using the hand shield pipe jacking method, instead of slurry boring shield machine, is to avoid any damage to the congested underground utilities which include cable fibre, the sewer and box culvert, the sheetpiles and so on.

The sequence of the works is as follows:
1. Construction of jacking pit
2. Ground treatment (to ensure the jacking pit being reasonable dry)
3. Fabrication of entrance ring and cut opening of sheet pile wall
4. Horizontal grout to stabilize soil ahead pipe jacking
5. Pipe jacking
6. Construction of receiving pit

Challenges & Difficulties
Unforeseen underground condition poses a great challenge on L&M. Initially, L&M expected that the works could be completed within four months. However, the existing underground utilities and old structures, especially the sheetpiles running 25 m long under Wai Ching Street, extend the work time to more than six months. Underground investigation had to be conducted before commencing the project. Hand digging and horizontal grouting are also required to take extreme care about the existing underground utilities during the course of pipe jacking. Especially the cable fibre was protected and supported by underpinning.

L&M completed the 97.8m long pipelines in late June 2004. The construction peak of the project was from December 2003 to June 2004 with around 12 workers involved in the works.