Lake Ferry Wastewater Treatment Plant
At Lake Ferry, the wastewater treatment system consists of on-lot septic tanks with effluent filters and a community wastewater treatment plant. At the treatment plant, septic tank effluent flows through a packed bed reactor, a recirculation tank and ultraviolet treatment. Discharge of the treated effluent is managed to either an adjacent block of land by irrigation or to a constructed wetland, depending on the conditions of the resource consents.
It has been identified that peak loads are impacting on the plant’s hydraulic capacity, which needs to be addressed for wastewater treatment plant performance and compliance. Peak loads for wastewater treatment plants refer to the maximum flow and pollutant concentrations the plant must handle, which are higher than average daily flows.
About the project
Inflow and infiltration investigations will get under way in November/December 2025 to further understand the source of rainwater getting into wastewater pipes serving Lake Ferry Wastewater Treatment Plant.
This work is part of operative requirements for the plant and the data gathered will inform resource consent renewal applications. To pinpoint where water is getting into the wastewater network, our contractor needs a few days of consecutive rain.
Background
The plant was granted new consents on 17 June 2005. A change of conditions was granted on 10 January 2011. SWDC submitted a consent renewal application in August 2025.
In general, the consents allow SWDC:
- to discharge treated wastewater to land via an irrigation system at up to a maximum daily flow rate of 200 cubic meters per day and a maximum weekly flow rate of 700 cubic meters per week.
- to discharge treated wastewater to land at a maximum application rate of 3.0mm/day or up to the field capacity.
- to discharge treated wastewater to water (wetland) when the field capacity of the irrigation field has been exceeded or when a discharge is required for emergency or maintenance purposes.
- to discharge contaminants and odours from the collection, treatment and discharge facilities within the site boundary.