Australasia’s largest giant fibre glass liners lifted into our Central Interceptor shaft


There were huge sighs of relief as five giant fibre glass liners, weighing a total of 80 tonnes, were successfully lifted inside a 70m deep shaft at our Central Interceptor May Road, Mt Roskill site today (5 May).
New Zealand’s largest lattice boom mobile crane (600 tonnes) was used to lift five Glass Reinforced Plastic (GRP) liners, each 3m high, with a 7.5m diameter into a 70m deep shaft. First the modules were lifted on top of each other to form a long cigar. Once they were bolted together, the structure was lifted carefully into the shaft, steel guide rails helping it to slide into place, with millimetres to spare.  
Central Interceptor delivery manager, Chris McCarthny says considerable planning went into preparing for the big lift: “We understand these are the first GRP liners of this size and depth in Australasia and the crane is one of the few in New Zealand with enough capacity to lower them down this very deep shaft. The weather was a bit gnarly, so there were cheers all round when the final piece slotted into place.
“I want to thank the liner manufacturers, RPC, and the Ghella Abergeldie JV team delivering the Central Interceptor project for their coordination and good communication with the crane crews which produced a great outcome, with five liners going into the shaft smoothly.”
The liners are made in Indonesia and were transferred from Ports of Auckland at night, due to their large size. Five of the modules contain ‘cascade shelves’, designed to dissipate the energy of the wastewater when it transfers from Link Sewer C tunnel into the deeper Central Interceptor tunnel lying below. The fibre glass also protects against the corrosive effects of wastewater, helping to ensure a 100-year life span of the shaft. A further 17 modules will be added in coming weeks.

Fibre glass liner being put into position by a crane

The base of the first module has a semi-circle cut out, ready for Hiwa-i-te-Rangi, a Tunnel Boring Machine digging the main Central Interceptor tunnel to pass through in August as she continues her 14.7km to central Auckland. The TBM has travelled more than five kilometres since leaving Māngere in 2021 and is tunnelling at around 18-20m per day as she approaches Mt Roskill. 
The Central Interceptor project has achieved a flurry of recent milestones, including successfully crossing under the Manukau Harbour in December and completing the first link sewer in March. Tunnelling work on the second link sewer begins in July. Sixteen sites are operating across Auckland, employing around 500 construction staff.
The Central Interceptor project is the largest wastewater infrastructure project in New Zealand and will see a significant reduction of wet-weather overflows into central Auckland waterways and beaches.”