Herne Bay Collector
DATE: 2026-2028
CLIENT: Watercare Services Limited
LOCATION: Central Auckland
CONTRACTOR: Ghella
CONSTRUCTION TECHNIQUE: TBM
ESTIMATED COST: $260m
STATUS: Under construction
Watercare’s Herne Bay Collector will intercept combined wastewater and stormwater flows and convey them into the Central Interceptor at Point Erin Park, for treatment at the Māngere Wastewater Treatment Plant. The scheme will significantly reduce wet-weather overflows into the Waitematā Harbour, improving water quality along Auckland’s waterfront.
The works comprise approximately 1.5 km of 2.1 m internal-diameter main collector tunnel, together with a 190 m DN1000 branch tunnel, shafts, interception chambers and connections to the existing network. A new control chamber and plant room at Point Erin Park will integrate the collector with the Central Interceptor.
The main tunnel will be installed by pipe jacking using an Earth Pressure Balance micro-Tunnel Boring Machine. Shaft construction uses secant bored piles, with excavations approximately 9–22 m deep.
Delivery through an established residential suburb requires careful management of groundwater, ground movements, existing utilities and constrained construction sites. Completion is scheduled for the end of 2028.
