Integrated Wastewater Masterplanning for Wanganui City

Overflows and spilling during rain events, coupled with pressure from developers, have caused the Wanganui District Council (WDC) to evaluate the existing wastewater network and develop an integrated masterplan for their wastewater reticulation. The purpose of the masterplan is to act as a decision making tool in relation to Capex and Opex spending for these assets within the wider framework of its 30-year Infrastructure Strategy. 

At the commencement of this project, a “Roadmap” for the integrated masterplanning and hydraulic analysis of WDC’s wastewater system was created that showed how different asset information could be linked together in a coordinated way. The roadmap informed WDC of the required sequence of tasks, likely outcomes, required resources, timeframes and costs associated with the implementation of such an integrated masterplanning project prior to their commitment of resources and funds. 

As part of the masterplanning process, a hydraulic model of WDC’s entire wastewater network was built and calibrated using InfoWorks CS software. This model was used to identify the constraints within the networks and to create a programme of associated remedial works. 

This paper focuses on the development of the masterplan, the results of the wastewater model and development of the Programme of Works and outcomes. It serves as a case study on the benefits of the adopted roadmap and future implications.