Porirua Waste Water Treatment Plant RAS System Upgrade and Hydraulic Capacity Upgrade, 2015

The Porirua Wastewater Treatment Plant is operated by Wellington Water and treats wastewater from the Porirua City Council catchment and the northern suburbs of Wellington City Council’s catchment. The treatment plant which was commissioned in 1989 is located in a valley south of Titahi Bay. Since then, a number of upgrades have been implemented but some operational and performance issues remained.

The plant was not operating to its design capability due to problems with sludge in the clarifiers. To overcome this four new pump stations needed to be built with associated piping. The main inlet pipe also needed upgrading from 450mm to 600mm and a new flow meter needed to be installed on the 900mm diameter aeration inlet pipe.

We won the Civil Contractors NZ Wellington/Wairarapa John Carson Memorial Award for Health and Safety for 2016 for this project.