Completion of the Southern Pipeline project is a race against time to prevent wastewater overflows into the harbour.
Tauranga has two wastewater treatment plants, one at Chapel Street and the other at Te Maunga. Chapel Street was built in the 1960s to service a population of 32,000. Until the 1990s, the treated wastewater from the Chapel Street plant was discharged into the Otumoetai Channel.
The newly amalgamated Tauranga District Council adopted a set of wastewater principles in the early 1990s:
- No sewage discharges into Tauranga Harbour.
- Transfer the treated wastewater from the Chapel Street plant to the Te Maunga site.
- All treated wastewater goes through wetlands before disposal to the ocean.
- Use the Te Maunga ocean outfall for disposal of all treated wastewater.
- No further reclamation of Rangataua Bay for wastewater purposes.
- Re-use treated wastewater as a resource, if possible.
Actions that resulted from those principles:
- A new pipeline was built to transfer treated wastewater from Chapel Street to Te Maunga instead of being discharged into the harbour.
- The Te Maunga site was extended and a new treatment plant was built there.
- Wetlands were built at Te Maunga to complete the treatment process.
- Ultraviolet disinfection facilities were built at both plants to improve the quality of the final treated discharge.
The Chapel Street treatment plant has been upgraded through the years but has reached the limit of its ability to expand. Meanwhile the city continues to grow and regularly produces more wastewater than the Chapel Street plant can cope with. This problem is being managed, but the long term solution is to divert more waste away from Chapel Street as soon as possible.
As a last resort measure during situations where the Chapel Street treatment plant is overloading, Tauranga City Council has resource consent to discharge treated wastewater into the Tauranga Harbour. This is more likely to occur during heavy rain, because that is when extra stormwater enters the wastewater system through manholes and gully traps, overloading the network.
The Southern Pipeline will relieve the burden on the Chapel Street treatment plant, improve its performance and reduce the risk of sewer overflows.
Last Reviewed: 29/11/2017