Project Summary
Coffey delivered the design and construction of a new foul sewer collection system serving Achill town and surrounding areas in County Mayo. The project included pumping stations, a wastewater treatment plant, and a marine outfall, providing modern infrastructure for a population equivalent (PE) of 1,200. The contract was completed in 2010, with Coffey also responsible for a six-month maintenance period.
Project Description
The works comprised the installation of approximately 6km of sewers, the majority being rising mains, laid along narrow roads within the town and surrounding areas. Five pumping stations, a wastewater treatment plant and a marine outfall were constructed.
The sea outfall consisted of a 300mm HDPE pipe extending 190m offshore, terminating in a branched diffuser protected with rock armour. The diffuser system incorporated a tidal clock as part of the SCADA controls, ensuring treated effluent was discharged only when the tide was above diffuser level.
Design and installation of process and MEICA elements were carried out by Coffey’s subsidiary, Coffey Water, while civil engineering design was undertaken by HGL O’Connor.
Scope of Works
The works included:
- Installation of approximately 6km of foul sewers, including rising mains and gravity mains.
- Five pumping stations at Sraheens, St. Finions, Achill Sound Bridge, and Old Railway.
- Construction of a wastewater treatment plant designed for PE 1,200.
- Marine outfall pipeline and diffuser chamber with rock armour protection.
- Interconnecting pipework and associated site services.
Landscaping, screening mounds, paved areas, access roads, turning bays, and skip areas. - Boundary walls, fencing, cattle grid and entrance gates.
Technical Highlights
- 6km of pipelines installed, including gravity sewers, rising mains, and water mains.
- Excavations up to 6m deep through rock, using gas blasting where required.
- Marine outfall constructed 190m offshore with diffuser chamber protected by rock armour.
- Wastewater Treatment Plant designed for 1,200 PE, incorporating SBR unit, UV sterilisation and sludge treatment facilities.
- Five pumping stations constructed at key locations to service the network.
Added Value
- Design-and-build contract allowed Coffey to coordinate civil, process and MEICA design, ensuring efficient delivery.
- Use of Coffey Water for process and MEICA works streamlined design responsibility.
- Trial trenching, daily reinstatement and fencing minimised disruption to the local community.
Environmental, Safety or Community Measures
- Marine outfall designed with tidal clock control to safeguard the marine environment.
- Landscaping and screening mounds integrated into the works to reduce visual impact.
- Public safety maintained by fencing and daily reinstatement of trenches through the town centre.
To learn more about Coffey’s work in water and wastewater management, or to discuss future opportunities, please contact us at 091 844356 or info@coffeygroup.com.
