Southern Pipeline route selection
Planning for the Southern Pipeline began in 2005. The primary goal was to divert wastewater from the new southern catchments across to the Te Maunga treatment plant, because the Chapel Street plant would not be able to cope.
Several different routes were considered. The option that offered the best result for the whole city was to bring the Southern Pipeline from Greerton to Memorial Park, then across the harbour to Matapihi. This option solved several wastewater network problems at once. It achieved the primary goal of diverting sewage from the southern catchments to the Te Maunga treatment plant, and it also offered more ability to relieve the overall wastewater burden that the wider city was placing on the Chapel Street treatment plant.
In 2008 an independent review investigated the option of building a third wastewater treatment plant in the Tauriko/Lakes area instead of constructing the Southern Pipeline. The review confirmed that even with a third treatment plant at Tauriko, the Southern Pipeline still needed to be built to avoid wastewater overflows into the harbour.
Southern Pipeline Project Independent Review (1.5mb pdf)
The third treatment plant was more expensive than the Southern Pipeline option, with the overall cost being $47M higher than the status quo option (building the Southern Pipeline and expanding Te Maunga). It also created more problems than it solved. The biggest issue was how to dispose of the treated effluent. Options included:
- pumping treated effluent into the Kopurererua Stream
- building a new pipeline to carry it to the Chapel Street wastewater plant
- treating it to an extremely high quality level then feeding it back into the city’s water supply network for non-drinking use only.
None of these were considered to be satisfactory options at the time. The review confirmed that even with a third treatment plant at Tauriko, the Southern Pipeline still needed to be built to avoid 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. 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.
Chapel Street has reached the limit of its ability to expand.
Last Reviewed: 28/11/2016