ME Case Study Three

Refurbishment & Upgrade of Assets

Forth Sewage Treatment Works

WGM carried out the MEICA refurbishment and upgrade of assets at Forth STW, Lanarkshire. The project involved replacement of existing M&E assets, and development of a new ICA solution to integrate all equipment for control and automation from a single MCC.

Description of the works

Forth WwTW is an existing, operational wastewater treatment works built in 1950 that treats domestic sewage from the village of Forth with a designed PE of 3500.

The works incorporate the following processes:

  • Storm Treatment – Screened Flows Over 9DWF To Water Course

  • Inlet Works – Screenings Removal & Grit Removal

  • Primary Treatment – Sludge Settlement

  • Secondary Treatment – Biological Filters

  • Final Treatment – Humus Settlement

  • Sludge Treatment – Tankered Off-Site For Treatment

Development of ICA solution

The design requirements for the new ICA section included integrating existing operational plant, not for the replacement, new process equipment being installed and upgrading of existing failing assets with replacement equipment. It was also identified that due to existing plant being controlled locally at each point this was difficult to manage the treatment works due to lack of visibility of equipment condition and operation.

WGM selected a systems integration partner for design and manufacture of the new ICA control panel and remained involved throughout the design through to site delivery including drawing and documentation input and approvals, PLC & HMI selection and sizing, the location of componentry and factory testing of software. The sizing and locating of componentry were particularly important due to the different data transmission types of hardwired inputs and outputs, Profibus networks and Modbus communication. This involved a number of different cables entering the ICA compartment requiring a larger frame size to accommodate this. The selection for a Siemens S7 PLC & HMI allowed areas of the site to be intelligently viewed and controlled instead of the previous conventional wiring of all equipment. This included the flow to full treatment actuator replacement which now provides a stable incoming flow through to the primary settlement tanks, with excess flows spilling at the relevant upstream locations.

The final design resulted in an easily accessible and manageable system, assisting with a more suitable operating manner. Site operatives previously had to access different locations on site for information gathering and checking of equipment condition, and now this can all be viewed and monitored from a single HMI screen. The implementation of remote reset functionality to control panels on site also allowed for certain plant items to be reset from a single location, removing operator risk of accessing the plant directly to carry out the task, especially during harsh and difficult weather conditions.

WGM Engineering


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