AGRU concrete protection for giant wastewater tunnel

The Auckland Central Interceptor is the largest wastewater project in New Zealand's history. This super-sized wastewater tunnel will transport sewage from the west of the city to the Māngere Wastewater Treatment Plant in the east. Commissioned by Watercare Services Ltd, the new wastewater tunnel will cost around NZD 1.2 billion and is scheduled for completion by 2026. AGRU Kunststofftechnik supplies concrete protective liners made from polyethylene that will protect the wastewater tunnel against concrete corrosion in the long term.

This project is not only intended to accommodate the population growth in this major city of 1.7 million inhabitants and the resulting increased demand for wastewater. In older parts of downtown Auckland, wastewater and storm water flow into a combined pipe network. During heavy rains, storm water can flood these pipes. Currently, during heavy rains, storm water contaminated by fecal matter is discharged into Waitematā Harbour. The new wastewater tunnel is expected to significantly reduce these overflows.

The construction contract was signed with the Ghella Abergeldie Joint Venture in March 2019. A 200 m long Herrenknecht tunnel-boring machine is in use. The finished wastewater tunnel will have a gradient of 1:1000 to allow wastewater to drain to Māngere. A total of sixteen access shafts with a depth of up to 65 meters will be built for maintenance and operation. In the course of this, control and overflow structures as well as air treatment facilities will also be built for future operation.

Prior to construction of the project, AGRU Kunststofftechnik GmbH and Agru New Zealand Ltd provided technical support for the installation of the lining for the shafts and tunnel. Agru New Zealand Ltd provided on-site extrusion welding support and training to the site crew. AGRU Kunststofftechnik GmbH and Agru New Zealand Ltd. have coordinated and continue to coordinate the supply of approximately 210,000 m² of lining for the project.