This Palmerston North City Council wastewater management project is one of the largest projects the Council have ever undertaken. Its aim is to review how the city best manages, treats and discharges wastewater.
Earlier this year, a longlist of 26 options for management, treatment and discharge of wastewater was developed by technical experts with input from stakeholders. These options were grouped into seven categories, based on the type of environment treated wastewater would be discharged into – land application, discharge to river, combined land and river discharge, discharge to groundwater, ocean discharge, discharge to a water supply network, and discharge to air. A robust assessment and testing process considered a number of environmental, cultural, economic and social factors, and options from each group have been selected to make up a shortlist of six options.
The six shortlisted options involve discharging treated wastewater to a range of environments – the Manawatū River, land, groundwater, and the ocean. Five options involve applying most of the treated wastewater to land, with the remainder being discharged to either the Manawatū River, groundwater or the ocean. These options will involve shifting where part or all of the city’s treated wastewater is discharged. One option will discharge all treated wastewater to the Manawatū River, with the wastewater being treated to a higher standard than it is currently. To recognise Māori cultural values, all discharge to the Manawatū River will first pass through a wetland or land passage system. This reinforces the importance of the earth in cleansing the treated wastewater before it enters the river.
During the next 12 months, Council will investigate the shortlisted options in more detail, to understand the type of treatment required for each. A consultation process will occur in early 2020, and Council will confirm the best practicable option in late 2020.