Whakatāne District Council’s Projects and Services Committee has approved the use of $700,000 in unspent funds from the recent wastewater rising main replacement in Ōhope to fund the desludging of the Ōhope oxidation ponds.
The Bay of Plenty Regional Council issued a resource consent for the Ōhope wastewater treatment scheme earlier this year, requiring the Council to install ultraviolet (UV) light treatment to sterilise effluent before it is pumped to the sea outfall. The UV equipment requires a certain level of effluent clarity to ensure efficient light penetration. The installation of ‘floating wetlands’ has also been recommended as a pre-treatment method to achieve better clarity and has led to the need to desludge the maturation ponds ahead of the installation.
Following an investigation into the methods and costs of desludging the ponds, the best course of action was offered by ECL Group Site Care, based in Taupō. The methodology involves the use a suction head and two mobile dewatering units to extract the sludge, before returning up to 95 percent of the fluid back into the pond. The dewatered sludge would be then transferred to a sealed, vacuum tanker truck via a closed system and transported to the vermicasting facility in Kawerau.