Great North Road Sewer Separation

This project was enabled to mitigate combined overflows into the receiving environment, namely Coxs Bay and the Hauraki Gulf. The works also included extending the nearby stormwater network to allow for future growth of the area.

The design involved two separate sections of new stormwater pipe comprising of an approximately 78m of 225mm diameter pipe along Potatau Street and Great North Road and approximately 260m of 225-300mm diameter pipe along Great North Road and Northland Street along with the reuse of out- of-service bulk watermains to reduce the disruption of traffic along one of the city’s larger arterial roads.

By incorporating out-of-service watermains to connect stormwater reticulation on either sides of the road, the project was able to not only reduce disruption of traffic but also drilling or trenching requirements, providing a more economic and sustainable solution.

The preliminary design was completed in May 2020 – five months from award of contract.

Innovation

Reuse of serviceable out-of-service water main. Use of trenchless methods of construction across and along Great North Road to reduce disruption to traffic.

Challenges

Completion during COVID-19 times. Heavy traffic use in the area.