2. Project description

In order to launch the TBM and commence construction of the CRL tie-ins to the NAL, a range of ‘enabling’ works are proposed, which are the subject of this ESCP. These enabling works are described in detail in the CEMP.

In summary, the Mt Eden Enabling Works involve:

Continuation of the demolition and clearance of the Mt Eden CSA (commenced under the Mt Eden Demolitions Outline Plan) Set up of a temporary site office, which is anticipated to be a 2-3 storey modular building (likely made up of containers) located in the western extent of the CSA. Piling and excavation associated with the preparation of the portal. This will involve the demolition of the redundant stormwater shaft located in the portal area; the installation of bored piles and associated works (ground anchors and shotcrete) to support the excavation face; and removal of spoil. Bulk excavation to form what will become the rail trenches/cut and cover tunnels, which will also provide a ramp for the TBM to be manoeuvred into position. The excavation will encounter basalt, which is to be blasted in order to expedite the works and minimise the amount of rock-breaking required. In places, softer ground conditions are anticipated to be encountered, which may require the use of sheet piles. Local mined tunnelling to facilitate the TBM launch. Construction of the additional Mt Eden Road bridge (north of the existing bridge), including temporary diversion of shallow utilities in this location. Construction of the Ruru Street bridge, including diversion of the Huia 2 watermain in this location. Temporary and permanent utility diversions (such as water, wastewater, stormwater, Vector overhead cables and ducting, gas and communications) along Fenton Street, Porters Avenue, Haultain Street and Wynyard Street to provide adequate clearance between the Huia 2 watermain and NAL, associated retaining walls, and the proposed Fenton Street pedestrian bridge.

2.1 Construction methodology

The Project will be divided into stages as described in the CEMP.