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MARCH was engaged by a national utilities company client to undertake a control change over at their Sewage Pumping Station; the aim was to simplify the legacy control system.
History
The pumping station was originally constructed in the late 1990s to support the redevelopment of the Royal Docks, handling flows from newly installed trunk foul sewers. Control of the site was achieved using a Duty/Standby configuration of GE Fanuc PLCs, both maintaining identical datasets and managing over 670 digital I/O points and 56 analogue I/O signals.
Over time, the legacy PLC system became increasingly unreliable and difficult to maintain due to limited support and obsolescence of hardware. In addition, the operational requirement for a Duty/Standby configuration no longer existed, presenting an opportunity to simplify the control system and improve long-term maintainability.
Solution
MARCH delivered a full control system upgrade, replacing the legacy PLC infrastructure and all ten I/O racks with a modern ControlLogix platform.
A comprehensive site survey of the existing ICA panels was undertaken to inform the detailed electrical design. This included verification of existing cabling and terminal arrangements to ensure accuracy and minimise installation risk. The existing control philosophy was reverse engineered and developed in collaboration with the client to create a more efficient, future-proof solution.
A new HMI system was implemented to enhance operator visibility and control of the site. In addition, a fibre optic ring network was designed and installed to connect distributed I/O racks across the site, providing a robust and resilient communications architecture.
To facilitate a risk-free changeover, the pumping station was temporarily operated in a hardwired backup mode, utilising level controllers with critical alarms monitored via regional telemetry. This approach enabled the complete removal and replacement of PLC equipment and internal wiring without impacting the live process.
Results
The project was successfully delivered with no disruption to operations, providing significant improvements in reliability, maintainability, and operational efficiency.
The upgraded ControlLogix system and new HMI have enabled the client team to easily maintain and modify the control system moving forward. Improved control strategies have reduced operational stress on key assets, enhancing overall site resilience.
Enhanced visibility through the HMI now allows operators to monitor key parameters such as levels and power consumption, supporting proactive maintenance and improved efficiency. The installation of new hardware, along with rationalised and clearly labelled panel wiring, has significantly simplified fault finding and reduced downtime.
Updated electrical drawings and improved panel layouts further support ongoing maintenance activities, ensuring the site is well-positioned for future operational needs.