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

A new resource consent has now been issued for the operation and discharge activities associated with the wastewater treatment plant. This consent sets out updated conditions that Council must comply with, including requirements for system performance, environmental safeguards, and ongoing monitoring obligations. A copy of the newly issued consent is available below.