Case Study: An Expansion of a Water Treatment Plant
A municipal utility asked ECS Solutions to design and construct an expansion to one of their Water Treatment Plants. It was proposed to expand an existing facility from ten million gallons per day (MGD) to a total treatment capacity of 30 MGD and upon completion of the expansion, an existing 18 MGD plant was to be shut down.
Earlier, ECS had provided the configuration and start-up support for the SCADA system used to operate the plant and had installed the existing SCADA and control system at both the plant to be expanded, and the one ultimately to be shut down. The proposal provided by ECS Solutions for the expansion covered the control and/or monitoring of:
- Four existing and four new aerators.
- Existing and new primary and secondary settling basins.
- Existing sludge and reclaim equipment.
- All existing and eight new filters.
- Existing and new high service pumps.
- New chemical feed equipment for lime, sodium hypochlorite, fluoride, and polyphosphate.
The utility was using a Wonderware application, which ECS converted to an Ignition SCADA. This required drawing out old screens, connecting tags to the PLCs, and adding equipment to the existing plant that will be expanded. New equipment was heavily involved in the modifications, and this was added to the PLC program so that it was operating on a control logic system. The screens were converted to an Ignition system and the server was designed to run that system. In effect, it was a redundant system with both the PLC and HMI being redundant, which allowed all the software testing to be carried out on that system. The change to Ignition was cost-effective since the service portion for Ignition is cheaper than that of Wonderware. This change to Ignition also simplified the reporting software, giving the utility one platform rather than two. The historian function of Ignition was superior to that being used prior to the changes, although ECS had written the historian program during the earlier installation, and it was an “off the shelf” Ignition product. However, this allowed changes to be made without modification of the earlier system.
A challenge faced by ECS was the extensive scopes of work required by the municipality. This requirement demanded extensive understanding of the work proposed by ECS, together with helping the customer to comprehend exactly what was in the ECS scope of work. Many subcontractors were involved in the project, so that the various relationships could have difficulties, particularly in establishing that everyone knew who was doing what. The security portion of the system was designed in 2016. The techniques used today are very different and interaction between ECS and the utility was critical to ensure that the security was “up to snuff” and that ECS was working with today’s methodology rather than that used in 2016. ECS engineers necessarily had to comply with directions given by the internal IT personnel in the utility.
After the modifications, the utility has more capacity and is able to filter and treat more water. The collection and retrieval of data for the historian is a simpler process. Previously a number of steps were involved to obtain reports from the data. Now reporting has been simplified and streamlined in Ignition. Intentionally, the SCADA system itself was not improved, avoiding a large learning curve for the employees of the utility. ECS essentially copied the existing system, i.e., using the same pushbuttons, the same colors, and the same graphics so that the operators are not aware of any changes.
It seems unlikely that future improvements or modifications can be recommended. The system has been operating for a long time and water treatment plants have not changed much. From SCADA standpoint future improvements seem unlikely. Water treatment is not cutting-edge technology. In fact, there is little difference between one plant from another, so that it is difficult to find areas to improve.