Christchurch City Council, Ocean Outfall

Christchurch

The Ocean Outfall is the biggest construction project Christchurch City Council has undertaken to date. 

The $87.2 million project will take the city’s treated wastewater from the oxidation ponds at the Bromley Wastewater Treatment Plant and transport it 3km out into Pegasus Bay instead of discharging it into the Avon-Heathcote Estuary.

The Ocean Outfall consists of:

• A new pump station being built on the edge of one of the oxidation ponds at the Bromley Wastewater Treatment Plant
• A 5km underground pipeline that will take treated wastewater from the pump station under the Estuary, South New Brighton Spit and sand dunes, and then 3km out to sea
• The pipeline from the oxidation ponds to a point approximately 250m offshore beyond the surf zone was constructed from PE lined concrete pipe using a tunnel boring machine.  The offshore section, beyond that point out to the diffuser, was built using a “float and sink” technique of HDPE pipe with concrete weight collars.

Octa have supplied a senior project manager to the Christchurch City Council to provide a dedicated resource to complete this project.