Floating Wetlands - Nature Improved - An End User's Experience
Annual Conference
❄
In 1988, Whangarei District Council (WDC) constructed an eight hectare, surface flow wetland system to act as a final wastewater effluent polishing system and was a culturally sensitive option. Wastewater from Whangarei is treated at the treatment plant in Kioreroa Road before discharging to the wetland system, prior to Limeburners Creek and subsequently the Whangarei Harbour.
In 2011, public pressure and WDC’s inability to consistently meet Resource Consent conditions around effluent quality discharge, gave impetus to plans to upgrade the treatment plant and wetland. Options for the wetland upgrade were investigated and consideration was given to: consent requirements, minimization of wetland downtime during construction, long term water quality objectives, aesthetics & operational costs.
WDC has completed two further conversions of surface flow to floating wetlands at Hikurangi & Waipu. Unlike Kioreroa Rd, where the wetland is the final process before discharge, the installation of the floating wetlands at these locations was to aid downstream processes. At Hikurangi the intention was to improve the effluent being presented to a membrane plant, and at Waipu to aid the performance of the rapid sand infiltration basins.
This paper discusses the drivers for the installation of the floating wetland system and the actual performance achieved to date.