Sydney-based ground improvement Specialist Menard Oceania is working with CPB Contractors, Dragados and Samsung Joint Venture for the WestConnex New M5 project to provide support for this major road development in Sydney, NSW.
WestConnex is a key infrastructure project for the NSW Government. The New M5 component duplicates the existing M5 tunnel, which is heavily congested on a daily basis and, once complete, will separate city bound and airport bound traffic. The project consists of 9km of twin road tunnels (mined roadheader construction) from King Georges Road Interchange to a new four level St Peters Interchange.
Image courtesy of Sydney Motorway Corporation, August 2017
Opening to traffic in early 2020, the New M5 will provide new twin tunnels which will run roughly parallel to the existing M5 East and double the existing motorway corridor from two to four lanes in each direction. I
Such a big project requires solid soil to build on, and Menard was contracted by the CPB Contractors, Dragados and Samsung Joint Venture for ground improvement works at the St Peters Interchange, involving a barrier wall, ground compaction and installation of rigid inclusions.
With up to 12 people on site at the peak activity, the Menard team commenced the works last September with the installation of a Vertical Barrier Wall. This 10,540m2 in-ground wall restricts the flow of ground water through the area. This wall is over 1km long, has an average depth of 10.5m and was constructed using a specifically designed mix of in situ and imported materials. The re-use of in situ materials provided the environmental benefit of significantly reducing the amount of spoil to be relocated.
The team then completed over 20,000m2 of Rapid Impact Compaction works. This technique utilises a 7-ton hammer which repeatedly impacts the ground from a 1 metre drop height. The energy waves from this action induce localised densification of the ground, which significantly improves its capacity to support the new roadway above. This innovative technique is relatively new to the Australian market and provides the benefits of being both quick and cost effective. The hardworking Menard compaction hammer impacted the ground over half a million times in the period spanning December to May.
Rapid Impact Compaction (RIC) works
Menard then progressed to the careful installation of 94 CFA piles which support a protection slab spanning the Sydney Water Desalination Pipeline which passes through the site. These piles were installed 2m into the Class III shale to eliminate the risk of any settlement.
Most recently, Menard has been installing Controlled Modulus Columns (CMCs) in order to provide support for the embankments at the new bridge abutments. The installation of these columns is progressing ahead of schedule and by November over 2,000 columns will be installed, totalling 21,000 lm.
When asked what his favourite part of the project is, Kevin Doyle (Project Manager at Menard Oceania) answered “Being able to utilise a number of difference techniques on the same project and watching the landscape of the site transform over the last number of months.”
This is an exciting project for Menard and a strong endorsement of the business’ market-leading expertise in ground improvement for road infrastructure developments, and we are pleased to be able to contribute to the economic growth of Sydney with a project that eases congestion, creates jobs and connects communities.
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