Handover of Carrigrennan WwTP

Coffey has completed the engineering works on the Carrigrennan Wastewater Treatment Plant (WwTP) in Co. Cork and the commissioning, staff training and formal handover of the plant to Northumbrian Water Projects Limited (NWPL) is due to be completed in the second week of May 2021.

Coffey has been working with Northumbrian Water Projects Limited (NWPL) on upgrading the Carrigrennan WwTP at Little Island, Co. Cork to meet growing waste water treatment demands from Cork City and surrounding areas.

Ferric Chloride Bulk Storage tanks - 2 no. bulk chemical storage tanks of  25 m3 capacity providing total storage volume of 50m3 - equivalent to 15 days storage.

The project commenced in January 2020 following an Irish Water (IW) design and build tender award to Coffey. The engineering works on the Carrigrennan WwTP were completed by Coffey in April 2021 and included the design and build of a phosphate removal plant and the installation of a sludge dewatering system supplied by Huber SE. Handover of the plant to Northumbrian Water Projects Limited is due in the second week of May 2021.

Northumbrian Water Projects Limited operate and maintain the Carrigrennan WwTP on behalf of Irish Water. The plant provides primary and secondary treatment for wastewater from Cork City and surrounding areas. The original WwTP was commissioned in 2004 with a design organic load capacity of 413,000 population equivalent (p.e.). Treated wastewater from the plant is discharged through a 500m long outfall pipe to Cork Harbour at Lough Mahon. The initial design of Carrigrennan WwTP was driven by the requirements of the Urban Wastewater Directive. This legislation sets standards for the collection, treatment, and monitoring for wastewater discharges from urban areas.

Since the plant was commissioned, the upper harbour at Lough Mahon has been designated a sensitive area under the Urban Wastewater Treatment (Amendment) Regulations 2004 (SI 440/2004). The original WwTP design did not include for nutrient removal or disinfection of the effluent water. The Carrigrennan works are required to upgrade the plant to ensure appropriate phosphorus removal and that all water discharges from the WwTP meet the requirements of the wastewater regulations.

New Ferric Chloride Dosing Kiosk houses a day tank, dosing system control panel and two dosing pump cabinets
Ferric Chloride Dosing Kiosk
Day Tank - Chemical is transferred from each Bulk Storage tank via transfer pumps to a 2.5 m3 day tank located within the chemical dosing kiosk.
Day Tank within Chemical Dosing Kiosk

The Carrigrennan upgrades will ensure compliance with the phosphorus reduction requirements of the Wastewater Discharge Licence for the Cork City Agglomeration (D0033-01).   Coffey has designed and installed a new ferric chloride storage and dosing system to reduce total phosphorous along with an Hach OrthoPhosphate analyser to monitor levels in the treated waters. The sludge dewatering facility is also being upgraded to include, sludge treatment, thickening, digestion, dewatering and drying prior to the re-use or disposal of the sludge. Coffey has installed the dewatering upgrade as the final stage of the works on behalf of Northumbrian Water Projects Limited.

The commissioning, staff training and formal handover of the Carrigrennan WwTP plant is proceeding this week (w/c 10-May-2021) and the plant will be fully operational from mid-May 2021.

Call us on 091 844 356, email at info@coffeygroup.com or click here for details on this project or to discuss the other recent projects completed by Coffey.

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