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Lower North Island WWTP Upgrade

  • Completion date: Aug 2013

  • Track record: Effective project management ensured that this project was successfully completed on time and within the client’s budget.


In the years since its installation, the drying plant has been extensively modified to ensure the plant operation remains reliable. This resulted in the control system requiring continuous modifications and band-aids to keep the plant running. Over two thirds of the PLC code and SCADA screens were either redundant or did not function correctly, and the VSD communications were unreliable. The client had unsuccessfully attempted to upgrade the control system in the past.

AFI was contracted to review the installation, fully document the existing control system, develop a detailed project plan to minimise risks, upgrade to the new software version, remove any redundant code, and commission.

A window of 24 hours was made available for the upgrade – including the installation and commissioning of a new PLC and associated software. The commissioning / plant shutdown went exactly as planned and the plant was fully operational again with 4 hours to spare.

Services provided
  • Generate functional descriptions based on operator knowledge and existing PLC code and SCADA screens.
  • Risk mitigation strategies, detailed planning and comprehensive client communications.
  • Convert PLC software from Concept to Unity.
  • Develop new SCADA system in-line with client standards.
  • Understand associated resource consents and develop and generate automated reports to ensure compliance.
  • Diagnose the faulty VSD communications network and provide a reliable solution.
  • Shut the plant down and allow system to cool, install and commission the new control system, and get the plant fully operational again within 24 hours.
Product description
  • Schneider Quantum PLC with 250+ I/O points.
  • GE Fanuc boiler PLC.
  • Wonderware Intouch SCADA system.
  • Beijer decanter control system.
  • PDL drives.