Carrigans in Co. Donegal is located a short distance from the River Foyle on the R236, approximately 1.5km west of the border between the Republic of Ireland and Northern Ireland. The Carrigans Wastewater Treatment Plant (WwTP) is located to the south of Carrigans village and adjacent to the Carrigans River. The 2016 Census recorded the population for Carrigans as approximately 330.
The Carrigans WwTP currently provides primary treatment only. The plant is a twin-cell horizontal flow septic tank, with a design capacity of 280 Population Equivalent (PE). It is estimated that the current wastewater load being received at Carrigans WwTP is around 330 PE.
Carrigans Wastewater Treatment Plant currently discharges via an outfall pipeline directly to the lower reaches of the Carrigans River, which is part of the River Finn Special Area of Conservation.
There are currently no storm water holding facilities at Carrigans WwTP and excess flows overflow to the outlet chamber and discharge via the discharge pipe to the Carrigans River.
The wastewater treatment plant in Carrigans is overloaded and needs to be upgraded to meet the needs of the village and to protect the environment.
We need to improve the wastewater treatment so that the receiving waters are not impacted. We therefore need to upgrade the size of the wastewater treatment plant as well as the level of treatment.
The current discharge from Carrigans WwTP is to the Carrigans River, rather than the main channel of the River Foyle, where significantly greater dilutions are available.
In order to overcome these deficiencies it is proposed to pump the untreated wastewater to St. Johnston WwTP. The upgrade at Carrigans Wastewater Treatment Plant will involve:
We are currently at the design phase of the project. It is expected that construction will start in Q3 2020 with works complete by the end of 2021.