Client
NEWest Alliance
Location
Perth, Western Australia
Sector
Infrastructure & Transport
Services Delivered
Groundwater and Hydrogeological SupportPermanent Works Design and OptimisationPIle Supervision and CertificationPile TestingTemporary Works Design
The challenge.
The Thornlie–Cockburn Link and Yanchep Rail Extension form part of the WA Government’s METRONET program, delivering significant new and upgraded rail infrastructure to support Perth’s population growth. The projects involved complex rail alignments, new stations, bridges, retaining walls and interfaces with existing passenger and freight rail networks. Key geotechnical challenges included high groundwater levels along sections of the TCL alignment, variable and compressible soils such as Canning River Alluvium, weak Guildford Formation soils, and the presence of landfill near critical structures. These conditions required careful consideration to manage settlement, stability, groundwater impacts and constructability while maintaining alignment and clearance requirements.
The approach.
FSG was engaged by NEWest Alliance to provide geotechnical and groundwater design and construction phase support across both projects. Services included geotechnical design review and optimisation, temporary and permanent works design, detailed foundation assessments for retaining walls and rail infrastructure, pile integrity testing and review of monitoring data. Engineering judgement was initially applied to assess preliminary pile types and layouts, slope stability, working platforms and ground improvement requirements, with detailed designs informed by targeted investigation data and advanced geotechnical analysis. Groundwater assessments supported dewatering management, subsoil drainage design and hydrogeological inputs to drainage and construction water supply solutions, enabling coordinated and practical design outcomes.
The outcome.
FSG’s involvement supported the delivery of geotechnical and groundwater solutions suited to the challenging ground conditions encountered along the TCL and YRE alignments. The adopted approaches addressed high groundwater, soft and variable soils and constrained interfaces with existing infrastructure, contributing to constructible and economical foundation and earthworks designs. FSG’s experience on major METRONET rail projects provided relevant technical input to support the successful progression of design and construction activities across both rail projects.