Hihi Wastewater Treatment Plant
The Hihi wastewater treatment plant is located on Marchant Road, Hihi and a constructed wetland off Hihi Road. This plant treats wastewater from the Hihi township. A popular retirement and holiday spot, Hihi’s residential population numbers 200 during the winter months, growing to 400 during summer and peaking during the Christmas holiday period at around 600.
Treating the wastewater
Unlike most of the treatment plants in the district which are pond-based systems, the Hihi treatment plant is an above ground activated sludge plant. Wastewater is treated in an activated sludge reactor before flowing to a clarifier. Clarified effluent is pumped through sand filters and UV. The treatment process takes about eight days.
The treated wastewater is then pumped to a constructed wetland. The final discharge from the wetland flows into the Hihi stream, which ultimately discharges on to Hihi Beach.
Monitoring
Discharges from the wastewater treatment plant are authorised by a resource consent. The resource consent sets out certain conditions, such as the requirement to regularly monitor the treated wastewater.
