Improving health, the integrity of the environment, and water quality for fishing, water sports, and marine life

Killala Wastewater Treatment Plant

Uisce Éireann is targeting the elimination of raw sewage discharges from municipalities across Ireland. Prior to this project, Killala Town discharged their wastewater untreated into Killala Bay. In addition to the bay—designated as Special Area of Conservation (SAC), Special Protection Area (SPA), and shellfish waters—there are two designated bathing areas at Ross Strand and Enniscrone in the vicinity.

Mayo County Council initially commissioned our team to undertake works on preliminary design, site selection, site investigation, and receiving water assessments for a wastewater treatment plant (WWTP), pump station, and pipework. Uisce Éireann then appointed us to advance the project through design, planning, procurement and construction.

This project brought significant challenges in terms of managing the statutory processes, selecting a suitable outfall location, and determining an appropriate level of treatment. To support this, we conducted detailed environmental assessments on the receiving waters as well as marine modelling and assessments.

The site chosen for the plant was located at the old Asahi industrial complex. This facilitated the use of the disused Asahi outfall pipeline to discharge effluent outside of the shellfish waters and SAC, allowing for less stringent treatment standards. Reuse of this outfall eliminated the requirement to install a new outfall in an environmentally sensitive location at considerable cost. Prior to selecting this option, specialist surveys on the existing pipeline were carried out to assess its condition and suitability for reuse.

Today, the new WWTP and related infrastructure help treat wastewater to appropriate standards before safely discharging it into the marine environment.