Blanchardstown Regional Drainage Scheme: The rapid urban expansion in Dublin is exerting significant strain on outdated infrastructure, notably affecting the Tolka Valley’s wastewater network. Built in the 1970s to serve several commuter towns including several in County Meath, Blanchardstown, Mulhuddart, and Castleknock, the system has struggled to meet the increased demand. This has resulted in frequent overflows of untreated wastewater into the River Tolka, posing serious environmental and public health threats. The scheme was located alongside the Tolka River Valley in Blanchardstown between Parslickstown and Mill Road and the route of the sewer line is adjacent to the existing 9C wastewater network.
Appointed by the national water utility, Uisce Eireann (Irish Water), Ayesa was tasked with the Blanchardstown Regional Drainage Scheme, serving as the consulting engineer, lead designer, and Employer’s Representative. This €88 million project aimed to revitalize and expand the aging sewer system in Tolka Valley Park near the M50 motorway, emphasizing sensitivity due to environmental and public concerns.
The project scope included installing over 3 kilometers of new wastewater lines, and extending the network to serve local areas and towns such as Dunboyne, Clonee, Ashbourne, and Ratoath. The work involved 3.2 kilometers of micro-tunneling (1.8 m and 1.5 m diameter) to minimise surface disruption and included the establishment of 30,000 m³ of offline storage beneath Waterville Park to manage stormwater.
The upgrade also featured enhancements to the existing 9C sewer by adding a duplicate line from Parslickstown Bridge to Tolka Valley Park, coupled with a new pumping station. Advanced trenchless techniques were utilised throughout the construction, not only for the sewer installation but also for the development of underground infrastructures like wet-well/dry-well pumping stations and extensive pipeline networks.
Further construction included an above-ground building housing mechanical, electrical, instrumentation, control, and automation (MEICA) equipment, an ESB substation, and a sedum roof. The project incorporated environmental safeguards such as septicity dosing to counteract hydrogen sulfide buildup and comprehensive odor control systems featuring granular activated carbon, forced and natural ventilation, and vent stacks with integral carbon canisters.
Ayesa engineered and implemented cutting-edge technologies and sustainable practices throughout the project. This included managing the rerouting of local utilities to avoid service interruptions and restoring the landscape upon completion, thereby ensuring minimal ecological impact and setting the stage for future development and environmental protection.
The design featured advanced flow control technologies that bolstered system resilience and efficiency. The underground wastewater pumps, controlled from an above-ground central room, allowed for remote monitoring and rapid troubleshooting.
The comprehensive design during the procurement phase encompassed all necessary hydraulic, civil, structural, and MEICA specifications, cutting overall project costs significantly.
Ayesa’s environmental team played a crucial role in preparing the Environmental Impact Statement, ensuring the project preserved the surrounding natural habitats and park areas. Following planning permission secured in 2017, construction started in mid-2019 and the system became fully operational, enhancing wastewater handling capacity and adhering to the EU Urban Wastewater Treatment Directive.
WINNER: Highly Commended award | Infrastructure Category | The Irish Concrete Society 49th Annual Awards 2023.
FINALIST: Civil Construction Project of the Year 2023.
FINALIST: Irish Construction Excellence Awards 2024.
30000m3/day
storage
3km
using trenchless technology
