Sydney Gateway Project – Mass Soil Mixing (Stages 1 & 3)
Location: Mascot, New South Wales, Australia
Client: Transport for NSW
Engineer: Menard Oceania
Main Contractor: John Holland Seymour Whyte Joint Venture (JHSWJV)
Sectors: Transport Infrastructure, Road Construction
Project Duration: December 2021-May 2022
Project Overview
The Sydney Gateway Project is a major infrastructure initiative designed to improve connectivity between Sydney Airport, Port Botany, and the broader road network. Menard Oceania was engaged to deliver ground improvement works across two critical stages of the project using Mass Soil Mixing (MSM) technology.
Challenges
Both stages of the project presented complex geotechnical and environmental challenges:
- Contaminated and variable ground conditions including soft estuarine silts, Botany Sands, and residual soils.
- High groundwater table and tidal fluctuations.
- Hydrocarbon contamination and compressible fill layers.
- Safety and environmental risks associated with conventional excavation and dewatering methods.
Our Solution: Mass Soil Mixing (MSM)
Menard implemented MSM to stabilise trench alignments for the installation of drainage pipes and water quality devices. This technique involved in-situ mixing of soil with a binder to create stable blocks that:
- Minimise trench wall movement.
- Reduce groundwater ingress.
- Eliminate the need for sheet piling and extensive dewatering.
- Improve safety and reduce environmental impact.
Sustainability & Innovation
Menard’s approach prioritised sustainability by:
- Reducing excavation and offsite soil disposal.
- Minimising energy use through reduced dewatering.
- Lowering noise and vibration impacts near sensitive infrastructure.
- Conducting laboratory trials to optimise binder content and reduce material use.
Results
The use of MSM provided a safe, efficient, and environmentally responsible solution for trench stabilisation in challenging ground conditions. Menard’s innovative design and execution ensured minimal disruption to surrounding infrastructure and delivered long-term value to the Sydney Gateway Project.
