Improvement Programme

We are already working on improving parts of the wastewater system, including enabling better flow at central Porirua City pump stations, as well as upgrading the capacity of the treatment plant.

The wastewater improvement programme will continue to build on this work. Here is how we plan to do that.

The consenting programme

The discharge of treated effluent from the wastewater treatment plant is currently consented. But these consents expire in October 2020 and need to be replaced. We are currently assessing nine different options for replacing the discharge consents.

A preferred option will be presented to PCC and WCC later in 2019 and if agreed, a consent application will be lodged with Greater Wellington Regional Council late March 2020.

We will also apply for resource consents for the wastewater network wet weather overflows, which is a necessary part of the programme to manage and reduce them.

The improvement programme

Our approach is an integrated programme of improvement for the wastewater system, prioritising long-term investment in the wastewater network ensuring we can manage flows to the treatment plant and reduce wastewater entering the harbour and waterways. This work will build on upgrades to the treatment plant to increase capacity and performance enabling it to treat all flows that reach it.

The focus of the proposed investment programme is on the network, rather than the treatment plant, because:

  • Numerous previous consultation exercises have highlighted the high priority that the community places on improving the Porirua harbour and its streams, and
  • The harbour and streams are more sensitive to the untreated discharges from the network.

Improving the network (options being considered)

  • Increase capacity of the wastewater pipe network
  • Build wastewater storage tanks in the network to hold back the flow of wastewater during heavy rainfall
  • Upgrade pump stations so they can pump more wastewater to the treatment plant during heavy rainfall
  • Reduce the amount of stormwater entering the wastewater network during heavy rainfall
  • Increase leak detection and repairs to reduce wastewater entering streams and the harbour during dry weather.

Improving the treatment plant

  • Plant and equipment upgrades
  • Increase capacity of the plant to treat up to 1,500 litres of wastewater per second following heavy rainfall
  • Investigate new locations for the discharge from the plant