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Trans-Tasman collaboration breeds success for trenchless JV

Rob Carr, March Construction

The partnership of two Soletanche Bachy Group companies, Rob Carr and March Construction, is providing unmatched experience and capability in civil and trenchless construction in New Zealand.

From upgrading stormwater networks in Auckland, to tunnelling under live rails in Christchurch, the joint venture (JV) proves the power of collaboration.

Through cooperation Rob Carr and March are able to offer unparalleled access to international resources, underpinned by 50 years of local expertise. The JV has tackled trenchless construction projects to install pipelines beneath major transport infrastructure, waterways and environmentally sensitive areas. 

Expertise across two key trenchless techniques – slurry pressure balanced microtunnelling and pilot auger soil displacement – and a fleet of over 70 tunnelling and microtunnelling machines, has allowed the JV to develop a proven track record for tackling difficult projects across New Zealand.

The partners behind the JV
Rob Carr has been developing its capabilities across Australia’s utilities sectors since 1989. The company has a reputation for excellence in the delivery of energy, water and wastewater infrastructure, working as either head contractor or subcontractor on diverse projects in varying conditions, valued up to $35 million.

The company’s team of Australian-based tunnelling experts provide support and knowledge to their counterpartsW in New Zealand. From operational support through to mechanical maintenance and knowledge of the differing tunnelling machines, Rob Carr management and off-site staff are heavily involved in all New Zealand trenchless projects, ensuring collaborations between March and Rob Carr are seamless.

March is one of New Zealand’s leading geotechnical and civil engineering contractors. Since it was founded in 1971, March has delivered projects with high quality workmanship and an exceptional level of commitment to helping clients achieve
their goals. The company thrives on technically challenging projects, many involving significant temporary works including sheet piling and dewatering.

Rob Carr and March have worked together across NZ.

Preparing for Auckland’s CRL
Auckland’s City Rail Link (CRL) is the largest transport infrastructure project in New Zealand’s history. The project comprises a railway tunnel crossing Mt Eden Road, close to the existing Mt Eden Station. 

The tunnel clashed with an existing stormwater drain, which had to be replaced before the main railway tunnel could be built. The contract for the CRL C6 Project was awarded to a JV between March and Bessac, which was tasked with installing 423 m of new 2.32 m OD stormwater pipe, diverting the existing asset. Bessac, like Rob Carr, are also a Soletanche Bachy group company further showcasing the wider group capability.

Using its expertise and experience, the JV proposed an alternate alignment and design  optimization to launch at the Water Street shaft and implementing an S-Curve to avoid the need for a third shaft to be constructed. By adopting an S-curved alignment the team were able to avoid the worst of the impeding basalt lava flow and still construct the tunnel in one single continuous drive. 

However, this S-curve required the tunnel be constructed with a radius of 150 m in one direction – something which had not previously been attempted in New Zealand. The alignment also turned back in the opposite direction on a radius of 450 m to avoid the lava flow. 

The original two drives were combined into one, which required the use of a hydraulic joint, designed by Jackcontrol, and ongoing surveying of the installation provided by VMT. The JV also installed the main drive shaft, a 15 m deep secant piled structure, through difficult ground conditions, including the construction of the permanent works inside the main drive shaft.

Dual MTBMs upgrading century old pipelines
Freemans Bay Stormwater Network Upgrade required the renovation of separate, century-old, combined stormwater and wastewater pipes in the Freemans Bay area of Auckland. The Rob Carr-March JV was engaged by the client to deliver the project, including the construction of 1,200 m of new stormwater pipeline which consisted of 895 m of DN600, DN900, DN1200 and DN1400 glass reinforced plastic (GRP) pipe.

To install the pipeline, the JV used four separate Iseki slurry pressure balanced microtunnel boring machine (MTBMs) with each suited to particular size and ground condition combinations. The pipelines were installed depths up to 9 m below ground level. To facilitate the launch of MTBMs, the project team constructed several launch shafts by various methods but predominantly steel shoring boxes and sheet-piled shafts. 

A further 485 m of DN300 and DN375 concrete pipe was also installed using traditional open cut pipelaying methods along with the associated connections, catch pits and manholes.

Tunnelling under live rail
Hayton Road Wastewater Mains Upgrade required 430 m of existing DN525 wastewater main to be upsized to DN900 and DN1000 from Hayton Road to Alloy Street in Christchurch. The Rob Carr-March JV successfully completed tunnelling under a live rail corridor to replace a section of wastewater main under Hayton Road. The project team successfully installed the 37 m crossing with only 1 mm of the 3 mm settlement tolerance experienced by the KiwiRail assets. The construction team were able to overcome some challenging ground conditions through complex geotechnical engineering.

A masterclass in collaborative success
The JV sees both companies’ strengths foregrounded, carving the way for success on technically complex projects. It brings with it the full force of Rob Carr’s hard-earned 30 years of experience in trenchless civil construction, combined with March’s trust and knowledge that comes from 50 years of local presence in the communities where the JV works. With further support from sister company Bessac, the combined offering is simply unmatched.

For more information visit Rob Carr and March Construction.

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This article appeared in the October edition of Trenchless Australasia. Access the digital copy of the magazine here.

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