Herne Bay collector tunnel

Project overview

In parallel with the Central Interceptor extension to Point Erin, the Herne Bay collector tunnel will collect combined wastewater and stormwater overflows for safe treatment at Māngere Wastewater Treatment Plant. This new infrastructure will significantly reduce overflows into the environment and improve the quality of inland waterways and swimmable beaches.

Early works are continuing as we progress towards signing the final contract. These large projects have many checks and balances, so it can take time for a Construction Programme to be fully confirmed.

We will install a 2.1m-diameter tunnel for approximately 1.5km using a micro Tunnel Boring Machine (mTBM). The pipeline will pass beneath the road at depths ranging from 9-22 metres.

We will also:

• Install eight tunnel shafts, along with intercepting shafts connections to existing engineered overflow points (EOPs)

• Install small diameter pipelines along Marine Parade (600mm in diameter) and local connections to the existing engineering overflow points (between 200mm to 450mm in diameter). These will be constructed via open trenching.

• Establish two temporary Construction Support Areas (CSAs) one at Salisbury Reserve and the other in the area beside the Curran Street motorway on-ramp.

Main tunnelling and shaft site works

Early works contractor, Ghella, has completed service investigations across the project area. Over the next few months, we will carry out service relocations in preparation for the main Herne Bay Collector construction.

There will be three construction sites in the Sarsfield/Wallace/Argyle Street area, all located in the roadway at intersections. Service relocations are currently scheduled to from early January until April. All sites are fenced to keep everyone safe while we establish the area and put in a raised working platform. The sites will then be set up for a longer period of main construction works (shaft excavation and tunnelling) with altered traffic controls.

Traffic management will have an impact on both close neighbours and those travelling through the suburb. There are several different stages of work and each stage will have the appropriate traffic controls in place


The map below shows the location of the proposed works.

Areas affected by traffic management plans

Point Erin Park: South-west corner works

We are making good progress planning for the Point Erin Park south-west corner works (control chamber and plant room), which will integrate with the main Herne Bay tunnel (HBT) project. The image below shows amended design of the control chamber as well as the location of the first HBC shaft which has been moved into the park. We have our refined thinking around the connections to the EOP (engineered overflow point).

Now that the early works, service investigations in the main, have been completed, we carry out service relocations over the next few months. This is in preparation for site establishment for the main Herne Bay Collector works. Power cables and some streetlights will be relocated on Curran and Sarsfield Street. In the southwest corner of the park, we will relocate fibre and communication lines as well as wastewater and water pipes.