The scope of works included:

• Installation of 516m of 2m Ø stormwater pipeline install using a Tunnell Boring Machine (TBM) and traditional pipe jack techniques between Wellesley and Swanson Streets to replace the existing Albert Street stormwater line. These works included the construction of an 18m-deep pipe jacking shaft at Victoria Street, constructed using traditional soldier piles and walers, and reception shafts at both Swanson and Wellesley Streets to enable the removal of the TBM and tying-in of the new stormwater line to the existing networks.
• Strengthening 40m of the Orakei Main Sewer beneath Victoria Street.
• Construction of 350m of twin cut and cover tunnels along Albert Street, between Custom and Wyndham Streets.
• Relocation of existing utility services.
• Extensive traffic management, due to CBD location of worksites.
• Excavation of a tunnel box to maintain two-way traffic at all times through the Customs/Albert Street intersection as the main tunnels were built.
• Construction of four integrated 2.2m deep concrete decks to allow traffic to flow overhead while the rail tunnels were safely excavated underneath.

The City Rail Link C2 Enabling Works Contract was a highly complex, high-profile project for Auckland's CBD which required diversions of both live stormwater and sewer lines 18m underground. The tunnelling scope required 3D modelling and planning to ensure the works were carried out successfully.

Automated real time survey monitoring was implemented, providing detailed records of all project impacts, helping to mitigate concerns from stakeholders.

Ground water within the vicinity of the project was also closely monitored automatically in real time, with project bore holes with trigger level set.

All components of the C2 works involved significant excavations within a densely populated urban area. This created a complex interface of construction sites with urban streets and local stakeholders. Innovative techniques were developed to remove, treat, and dispose of groundwater. Complex arrangements of settlement tanks, silt busters, and flocking systems were implemented in order to successfully manage the environmental risks. This was then strictly monitored by a highly motivated environmental team.

To mitigate risks with odors during works on the OMS, a deoderising system was developed and implemented within the Victoria Street Shafts. Real time live dust monitoring was also implemented to track dust and monitor the construction techniques.

Works were also carried out in accordance with Mining and Tunnelling Regulations and those set by Worksafe.

The works carried out under the City Rail Link C2 Early Works Package will help to facilitate the new railway line which better connects Auckland's rail network and double rail capacity.