A New Era of Underground Construction in Hong Kong – From Ground Investigation to Construction

In order to support the sustainable development in Hong Kong, the Drainage Services Department (DSD) commenced the project ‘Relocation of Sha Tin Sewage Treatment Works to Caverns’. The first stage of construction for Main Access Tunnel was commenced in February 2019 and completed in April 2022 under Contract No. DC/2018/05. The excavation of main caverns to accommodate the sewage treatment facilities is on-going under Contract No. DC/2020/05. The paper first highlights the comprehensive ground investigation in planning stage. Advanced ground investigation techniques, including horizontal directional coring, surface geophysics tests, downhole geophysical logging, over-coring and hydraulic fracturing tests were carried out. The paper also briefly mentions the rock support design of MAT using rock reinforcement approach. The construction phase involves the installation of permanent rock bolts and shotcrete lining, implementation and utilisation of innovative and advanced technologies in drill-and-blast excavation with advanced sensors, surveying data with 3D laser scanner, and real-time monitoring via 5G network. These have allowed the team to conduct study on ground parameters, review of blasting design, continuous monitoring on excavation progress and quality control on site. The MAT construction under Contract No. DC/2018/05 represents a significant milestone in tunnel construction in Hong Kong. It showcases the integration of geotechnical expertise, innovative engineering, and meticulous construction practices. This paper provides an overview and valuable insights in shaping the future and usher in a new era of underground construction in Hong Kong.