Macroom wastewater treatment plant exceeded ammonia limit many times throughout 2024

Uisce Éireann said in a statement at the time that the issues were caused by “heavy rainfall which led to an overflow from the existing pipe, of which the EPA and Inland Fisheries Ireland were notified through our compliance team.” 

However, a Freedom of Information request to the EPA (Environmental Protection Agency) has revealed that testing of effluent from the plant showed levels of ammonia, suspended solids, and other substances far above what is permissible by the plant’s licence for months.

The effluent from the treatment plant is permitted to contain 2mg of ammonia per litre under its EPA licence

However, between April and the end of June, all ammonia samples were substantially higher than this limit. On April 26, the effluent had 33mg/l of ammonia, reaching a peak of 52mg/l on May 9.

Suspended solids in the effluent are permitted at 25mg/l. However, on April 28, a sample contained 430mg/l.

Raw sewage discharge

The documents also reveal the plant, which is currently undergoing a €21m upgrade to make it fit for purpose, was dogged by incidents throughout 2024. This is despite locals having been told that raw sewage discharge they saw in late June was a one-off incident caused by heavy rainfall.

A chamber at the plant became blocked in April, leading to sewage from the plant being taken by tanker to the wastewater treatment plant until mid-May.

In May, Uisce Éireann notified the EPA that it would need to switch to temporary clarifying equipment on June 4. This was due to an “emergency clear-out of Macroom WWTP clarifier”, and they acknowledged that the temporary replacement “will not give the same treatment as the existing clarifier gives.” On July 4, there was another equipment malfunction at the plant.

The EPA visited the plant three times in 2024, and reports note that the EPA inspector instructed Glanua and Uisce Éireann to meet with Cork County Council to find out how the plant could have no reported incidents in 2023 when under local authority maintenance.

Members of a local angling club, who lodged complaints with the EPA that raw sewage was flowing into the River Sullane in late June, have criticised levels of communication from both Glanua and Uisce Éireann.

“Staff told me there was a burst pipe and it would all be cleared up in a couple of days, and that was on the June 22,” Denis Cronin, of Macroom Trout Fly Anglers Association, told the Irish Examiner. 

"But now we can see that the problems are there longer than that."

Mr Cronin called on Uisce Éireann to include the local community as an important stakeholder and to achieve better communication of accurate information.

“They have treated us like mushrooms,” he said.

“We have been left in the dark until now, apart from some statements which have been made to the media. It’s all secrets. 

The plant is like Area 51 in Macroom

"They put up big barriers so that nobody can even see into it, so it’s like a secret site that nobody can look into.” 

The EPA told the Irish Examiner that a compliance investigation had been opened into the wastewater treatment plant, but could not confirm whether or not they will be seeking a prosecution of Uisce Éireann over the licence exceedances.

“The agency can make no further comment at this point in time as it is an open investigation,” a spokesperson said.

Macroom Wastewater Treatment Plant has suffered discharge issues and has been over capacity for the town for many years. Works to upgrade the plant began in November 2023 and are scheduled for completion by the end of 2025.

“Prior to the ongoing WWTP upgrade works, there were sustained ammonia ELV [emission limit value] exceedances and regular biochemical oxygen demand and suspended solids exceedances as reported to the EPA,” a press spokesperson for Uisce Éireann said.

“This is one of the reasons why the plant upgrade is being progressed.”