Watercare detected Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) above the Drinking Water Standards Maximum Acceptable Value (MAV) on several occasions in 2019 and 2022, resulting in the Onehunga Water Treatment Plant shutting down. Watercare are in the process of implementing a treatment barrier and also commissioned PDP to undertake a comprehensive catchment-wide desktop assessment to better understand potential PFAS sources within the Onehunga Aquifer, helping to enhance their Source Water Risk Management Plan.
The project was a great example of collaboration across several specialist disciplines at PDP, including the Contaminated Land, Water Resources and Geospatial teams. The project included a hydrogeological assessment and sourcing large volumes of information from various public information sources, all of which was imported into a GIS Web-Map developed to spatially view the relevant information and build a comprehensive conceptual site model. The GIS Web-Map was a fundamental tool for assessing large volumes of data over a large spatial extent, facilitating the assessment of potential PFAS sources and supported the communication of potential risks to a diverse range of audiences.
Overall, the project demonstrated that GIS based tools could be used across a broad range of applications including conceptualising and assessing risk, source water risk management plans and the assessment of other potential contaminants/hazards to enhance drinking water supply resilience.
Key Contacts
Nerena Rhodes
