ABSTRACT
Approximately a decade after the completion of Deep Tunnel Sewerage System Phase 1 (DTSS1), Public Utilities Board (PUB, Singapore’s National Water Agency) started DTSS Phase 2 (DTSS2), in 2017, to complete the master plan of superhighway for Singapore’s used water management. Arup was appointed by Penta-Ocean Koh Brothers (POKB) JV to provide the detailed design services for the construction of one of DTSS2 Contracts, namely Contract T-08. This contract includes the design and construction of main South Tunnel, which is 3 km long with 6 m internal diameter, running from Tuas Road to Tuas Water Reclamation Plant (TWRP) and Industrial Tunnel, which is 7.1 km long with 4 m & 3.3 m internal diameter, running from Jalan Buroh/Pioneer Road to TWRP. For the linings, both main and industrial tunnels have been designed consisting of primary lining made of precast concrete segmental lining and secondary lining made of cast-in-situ concrete. One particular requirement specified in the contract document is the application of microbiologically influenced corrosion (MIC) resistant concrete for the secondary concrete lining. In order to justify the thickness of sacrificial cover required to satisfy the design life of 100 years, accelerated biogenic sulphuric-acid corrosion test was carried out at the Advanced Wastewater Management Centre (AWMC), University of Queensland. This paper presents the process of mix design selection of the MIC resistant concrete applied in DTSS2 Contract T-08, complying with the requirements stipulated in the contract document.
