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 our plan:
The wastewater treatment plant
Ongoing upgrades have been made over the last seven years, enhancing the capacity of the wastewater treatment plant and significantly improving the quality of discharge at the Rukutane Point outfall.
Further upgrades and improvements are now planned as part of our application to renew the treatment plant’s resource consents which expire in 2020.
These upgrades will increase the capacity of the plant from treating 1,000 litres of wastewater per second to treating 1,500 litres of per second.
This alongside other technical improvements will ensure the treatment plant can fully treat all the flows that reach it and prevent any bypassing events.
We have considered also extending the outfall pipeline at Rukutane Point, however the benefit of doing so has proven very marginal compared to the cost. As such there is no intention to extend the outfall pipeline.
For more information on what we're planning to do, look at these information slides.
The wastewater network
The next focus will be the wastewater network, which is reaching the limit of its capacity and is contributing to the degraded water quality in Porirua Harbour in both wet and dry weather.
We have made some improvements to pumping stations and the network in recent years but have more work to do. Here are some of the things we are considering as part of a longer-term programme of improvements to the network:
- 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.