The starting point: a plant with no real visibility
The installation was a wastewater treatment plant (WWTP) with capacity to treat tens of thousands of cubic metres per day. The existing control system had been running for over 15 years: older-generation PLCs with no modern connectivity, no centralised SCADA system, and supervision split across local HMI panels in each plant area.
The result was predictable: operators had no real-time global view of the process, alarms were missed or arrived too late, and every incident required physically travelling to the affected area for diagnosis. Historical data was virtually non-existent, making any trend analysis or process optimisation impossible.
The client came to us with a clear objective: modernise plant supervision without stopping operations and without replacing the existing PLCs — a full replacement would have meant unacceptable cost and operational risk.
Solution design
After analysing the installation, we identified three key challenges: heterogeneous equipment across different manufacturers and generations, operational continuity with no downtime allowed, and cybersecurity requirements for any remote access capability.
Our solution was built on three pillars. First, a unified OPC-UA communication layer using industrial gateways to translate proprietary protocols (Modbus RTU, Profibus DP) from the existing PLCs into OPC-UA — integrating all equipment into a common architecture without touching any PLC. Second, a centralised SCADA on Siemens WinCC with complete synoptic screens for each plant area, real-time indicators, variable historians and centralised alarm management. Third, secure remote access via VPN with two-factor authentication, enabling the on-call team to monitor the plant from anywhere.
Phased implementation
To ensure continuity of service, implementation was divided into four phases running in parallel with normal plant operation: network infrastructure (IT/OT segmentation with industrial firewall), protocol gateway installation and OPC-UA validation, parallel SCADA development using live data from the installed gateways, and finally commissioning and operator training.
Results
- 70% reduction in alarm response time through centralised management and remote notification.
- Complete data historian — for the first time, the plant had a continuous record of all process variables, enabling energy consumption optimisation.
- Reduced internal travel — operators could diagnose any area from the central control room.
- 24/7 remote visibility — on-call staff could monitor the plant from any device, improving night and weekend coverage without increasing headcount.
Key takeaway
This project confirmed something we see frequently in the utilities sector: modernisation does not always mean replacing existing hardware. With a well-designed communication layer and a modern SCADA, it is possible to dramatically expand the capabilities of an installation at a fraction of the cost of a full replacement. The key is thorough upfront analysis — understanding the existing installation, the protocols in use and the operational requirements before proposing any technical solution.
If you have a similar installation and want to modernise its supervision without stopping production, tell us about your project. We'll analyse it at no cost or obligation.