The new pipelines will convey untreated wastewater to the Christchurch Treatment Plant in Bromley for treatment and discharge out to sea through the Christchurch Ocean Outfall, which was constructed by McConnell Dowell eight years ago.
McConnell Dowell brings considerable experience to the project, including the construction of several marine outfall pipelines and expertise developed on the SCIRT earthquake rebuild programme.
Installation of the two (5km and 1.8km long) weighted HDPE marine pipelines will involve prefabrication of pipe strings onshore before joining and bottom-pulling the pipelines out to the required location. A backhoe dredger and divers will then be employed to excavate the trench, lower the pipeline and backfill.
Work on site will commence in February 2018 and the project is scheduled for completion by Christmas 2018.