The Owenteskna WSS is a Design, Build and Operate contract comprised of a 2ML/day water treatment plant, intake improvement works and road improvement works.
The plant was constructed on a greenfield site with an Operation Service period for the completed plant of one year (with an option to extend for a further three years). Raw water for the plant will be drawn from the existing source at Lough Na Lughraman.
The scope of the works is as follows:
- Design and build of Owenteskna water treatment plant with a treated water output capacity of 2,000m3/day (100m³/hour over 20 hours)
- Construction of pipeline works and public road improvement outside the water treatment plant site.
- Miscellaneous works at Lough Na Lughraman including the upgrade of the access road, fencing around the lake, new intake screen and solar powered lake level monitoring with GSM telemetry
- Surveys, investigations, detailed design, preparation of construction documentation, submission of materials and plant for approval by the Employer’s Representative
- Project Supervisor Design Stage and Project Supervisor Construction Stage duties.
The Owenteskna Water Supply Scheme comprises the following unit operations:
- Lough Na Lughraman Intake Works furnished with a screen,
- WTP Inlet Works furnished with flow monitoring and sampling instrumentation,
- Raw water Flocculation with pH adjustment, coagulant dosing,
- Dissolved Air Flotation (DAF) Clarification,
- Rapid Gravity Filtration (RGF) and associated washing equipment,
- Disinfection by:
- Ultraviolet (UV) reactors controlled by UVT and UVI sensors; and
- Chlorination using sodium hypochlorite with dosing governed by residual chlorine monitors,
- Fluoridation by Hydrofluorosilicic Acid dosing,
- Treated water pH correction by Sodium Carbonate (soda ash) solution,
- Treated Water Storage reservoir,
- Treated Water Quality Monitoring,
- RGF wash water treatment and sludge settlement, thickening & storage,
- Sludge settlement thickening & storage.
The ICA component of the Owenteskna WSS project involved providing a fully automatic water treatment plant capable of operation for extended periods with minimal operator intervention. CWL produced the Functional Design Specification to detail the control requirements for the WTP in compliance with the Irish Water specifications. To achieve the control requirements, CWL provided a broad suite of instrumentation and control equipment including:
- MCC Panel with integrated PLC and HMI with a separate local control station,
- Field wiring and cabling for all instruments and equipment,
- Flow monitoring instrumentation,
- Water quality instrumentation to measure the following parameters:
- Total Organic Carbon,
- Ultraviolet Transmittance, Temperature,
- Chlorine residual, and Fluoride
- Streaming current monitoring to enable enhanced coagulation control,
- Level monitoring instruments, and
- Pressure monitoring instruments.