Case Study
Coolatee Integrated Constructed Wetlands
OVERVIEW
By delivering a Constructed Wetland (CW) for the agglomeration of Coolatee, we successfully realised the primary project goal of removing an untreated discharge from the EPA’s list. Furthermore, we achieved the cessation of this untreated wastewater discharge to the Foyle estuary, without the need for an energy supply or any treated water connection, all whilst increasing the biodiversity of the area.
BENEFITS
Other benefits include the achievement of key sustainability objectives, including a minimal carbon footprint. The CW installation comprises a primary treatment stage followed by 4 no. wetland ponds, providing secondary and tertiary treatment. Ryan Hanley’s (RH) commission from Uisce Éireann, spanned all stages, from Feasibility Study to construction and commissioning.
The project achieved a significant milestone by removing the Coolatee agglomeration from the EPA’s untreated discharges list. We achieved this by designing a wastewater treatment to provide high quality effluent with no power supply requirement, no fixed water supply, no surface water runoff and significant increases in biodiversity. The project represents major operational savings and is one of the first of its kind commissioned by Uisce Éireann. It is envisaged that this project will pave the way for the implementation of nature‐based solutions for the treatment of municipal wastewater in numerous other agglomerations in Ireland.
Environmental
The constructed wetland system at Coolatee employs native aquatic plants, such as reeds and sedges, to consume the nutrients in the wastewater, thereby treating the wastewater in the most environmentally sustainable way possible. More than thirty aquatic plant species may be utilised in the ponds, creating a micro-habitat for native aquatic invertebrates which play a major role in extracting the organic matter via the food-web, leaving the discharge clean following natural filtration. The only energy requirement is sunlight to sustain the plants.
Services delivered by Ryan Hanley on the Coolatee Integrated Constructed Wetland (ICW) included environmental consultancy services to undertake the environmental assessments necessary to inform the design, planning consent and construction mitigation for the project.
The environmental assessments (Appropriate Assessment (AA) Screening, Natura Impact Statement (NIS) and Ecological Impact Assessment (EcIA)) included surveys for otter, whooper swan, riparian habitat and invasive plants to ensure that all measures were applied to successfully avoid adverse effects on the adjacent River Foyle (two SACs in a transboundary zone) and its qualifying interests, salmon and otter. The ICW location was carefully sited a distance from the riparian habitat, and of adequate elevation to avoid the 1-in-100 year flood extent. The project supports the WFD objective to achieve ‘good’ water quality in the waterbody by 2027.
