Tunnel drilling under Heathcote River early in new year

A tunnel is set to be drilled under the Heathcote River next month as part of the Lyttelton Harbour wastewater project.

A 535-metre pipeline will be pulled through the tunnel under the river and the Ferry Road roundabout by a method called directional drilling.

It will then connect the Alport Place pump station to the Heathcote Valley pipeline, the final step of a project to connect Lyttelton Harbour’s wastewater system to the main Christchurch system.

Part of Ferry Road from St Johns Street to the Ferry Road roundabout will be closed to install the pipeline from 8pm Saturday 25 January to 10am Sunday 26 January.

This work is a key part of the fourth and final stage of the project, that once complete, will put an end to the routine discharge of treated wastewater into Lyttelton Harbour.

Up until now wastewater from Lyttelton, Governors Bay and Diamond Harbour has been treated at wastewater treatment plants in each of the townships before being discharged through outfall pipelines into Lyttelton Harbour.

“This project, when completed, will end the routine discharge of treated wastewater into Lyttelton Harbour, a fantastic environmental milestone for our city,” says Christchurch City Council Head of Three Waters and Waste Helen Beaumont.

The multimillion-dollar project is being constructed in four stages, with stages one and two now complete and stage four set for completion in early 2020.

In stage three, the existing wastewater treatment plants at Cashin Quay, Governors Bay and Diamond Harbour are being converted into pump stations to pipe all of Lyttelton Harbour’s wastewater through the Lyttelton Tunnel.

The Cashin Quay treatment plant has been converted and the pump station is being tested before commissioning. The new Diamond Harbour pump station is on track for commissioning this month.

Work on the new pump station on Lyttelton’s Simeon Quay is now expected to be complete by next October, due to a redesign of the pump station, with the entire wastewater network commissioned in late 2020.

This pump station will be the powerhouse that pumps all of the harbour’s wastewater through Lyttelton Tunnel and the Heathcote Valley pipeline to the main Christchurch system.

“Due to the intricate nature of the pump station, we need to take a bit more time to get the design right,” Ms Beaumont says. “It’s important to note this is still being delivered well ahead time and will meet Council’s target of ending the discharge of treated wastewater into Lyttelton Harbour by 2021.”

The Council is working with Environment Canterbury, Te Hapū o Ngāti Wheke, Te Rūnanga o Ngāi Tahu and Lyttelton Port Company and harbour communities to improve water quality in Lyttelton Harbour as part of the Whaka-Ora Healthy Harbour Plan.