Tahuna township - The challenges of treating and discharging wastewater to the local environment

The problem of how to deal with the towns wastewater has been a problem in Tahuna since the mid 1980’s when the first plans were drawn up for a Community wastewater reticulation and treatment plant. Unfortunately the cost of a suitable system made the project prohibitive and the plans were shelved. Since then, the town has had to put up with failing septic tanks and raw effluent ponding and running off into surrounding properties.

Finally in 2004, the New Zealand Government introduced subsidies to assist small townships with their water and wastewater collection and treatment and this project was able to be completed. The original plans were revisited and updated to include the most up to date technologies for treating wastewater. The plant has to be capable of treating the 51 houses in Tahuna plus a variety of shops, businesses, and the local school.

A Membrane Bioreactor System (MBR) from Hynds Environmental was chosen as the most appropriate treatment technology owing to its small footprint and ability to produce an extremely high level of treatment for the wastewater. The treated water from this plant will be discharged directly into a local stream via a rock filter.

This paper discusses the challenges of gaining approval from all stakeholders for, and designing, a wastewater treatment plant with the ability to discharge directly into the local waterways. The performance of the system to date will also be presented.