In 1998 North Shore City Council (NSCC) initiated ‘Project CARE’, their Council Action in Respect of the Environment Study to plan improvements to the city’s wastewater system to protect streams and beaches. In 2002 this included the creation of their first trunk wastewater computer model, which has been progressively updated and was used as the basis for two asset planning review cycles under NSCC. Since the Council merger in 2010 Watercare has taken on the responsibility and maintenance of the Project CARE model. It is now known as the ‘Rosedale Strategic Management Area (SMA) Model’ - a third generation computer model which has the trunk network and key detailed models of the local network sewer areas included.
The Rosedale SMA is a highly pumped network conveying wastewater flows up to the Rosedale Wastewater Treatment Plant located at elevation RL 45 metres. The model has become a very powerful planning and operations decision making tool. Working closely with Watercare Operations, Energy and Controls Systems Teams, the Planning Team has been able to develop and fine tune pump station interstation control routines in the model and optimize the best possible use of available storage and opportunities for preferential wet weather spill locations.
Over the past 15 years a rolling programme of flow gauging, model updates and recalibration has taken place. Currently, the Rosedale SMA Model is being used to assist Watercare in the development of its Wastewater Network Strategy (a requirement of Watercare’s Network Discharge Permit). As this model has been kept up-to-date i.e. ‘live’, it provides high confidence model outputs and history to assess completed improvement works, which will be further enhanced with proposed future flow gauging and recalibration phases. Quality of information and confidence in performance data is one of the key criteria required in Watercare’s Network Discharge Permit for prioritizing improvement works.