EPA questions Achill water plant ability to deal with seasonal demand

CONCERNS Corrymore Water Treatment Facility on Achill Island. Pic Conor McKeown

Audit also finds Irish Water and Mayo County Council ‘acted decisively’ after incident

Anton McNulty

THE Environmental Protection Agency (EPA) has expressed concern that the Achill water supply will not have the resilience required to deal with seasonal increases in water demand.
An audit of the Achill public water supply was carried out by the EPA on September 3, a day before the month-long ‘Do Not Consume’ notice was lifted. The notice was put in place on August after a combination of the high demand and rising water temperatures resulted in exceedances of aluminium in the public water supply.
The operational capacity of the water treatment plant at the time of the audit was 90 cubic metres per hour. Actions proposed by Irish Water and Mayo County Council in the short-term, include laying a new raw-water pipeline, which would increase plant capacity to approximately 120 cubic metres per hour.
However, the EPA inspectors highlighted areas of persistent concern. “Despite these upgrades, the EPA remains concerned over whether the plant could respond to high water demands in the summer months, particularly if the island sees a large influx of tourists as it did in August this year,” the agency stated in the audit.
In one of its recommendations, the EPA stated that Irish Water ‘should take action to improve the resilience of the Achill public water supply, by ensuring the water treatment plant has sufficient capacity to meet seasonal increases in water demand’.

Response assessed
The scope of the audit was to assess the full public water supply from source to tap, but there was an emphasis on assessing Irish Water’s remedial response to the recent ‘Do not Consume’ notice.
The audit found that Mayo County Council and Irish Water ‘acted decisively’ after the incident began and that they ‘worked tirelessly’ throughout the incident to ensure water was available for sanitation, while vulnerable customers received deliveries of bottled water’ and finding a solution was prioritised.
Concern was raised in the afternoon of Friday, August 7, when the caretaker of the Achill plant noticed the sludge blanket in the clarifiers was starting to rise and a series of tests were carried out to check aluminium levels.
The results remained below the drinking water limit of 200 microgrammes of aluminium per litre but ‘there was an obvious trend of rising aluminium values’. Another sample was taken that evening which showed a concentration of 1,010mg per litre and a decision was made following a conference call to issue a ‘Do Not Consume’ notice.
The audit found that due to the high demand for water, the caretakers were not in a position to reduce water flow through the treatment plant during the incident and the coronavirus threat meant water availability for hand-washing was prioritised.
The treatment plant could not recover until water demand on the supply decreased, and this did not occur until Tuesday, August 18, when the treatment plant returned to compliance.
“Irish Water then completed the commissioning of additional monitoring equipment at the plant and a new plant shut-down facility, to prevent inadequately treated water being supplied to consumers. Irish Water also cleaned all 18 reservoirs to remove any build-up of residual aluminium sediment before the ‘Do Not Consume’ notice was lifted,” the audit stated.

Action demanded
Five further recommendations were made by the EPA following the audit including a review of the network chlorine residual monitoring programme.
Irish Water representatives were advised of the audit findings by the EPA and told that action to address the issues raised must be taken as a priority.
Irish Water now has until October 17, 2020, to submit a report to the EPA detailing how it has dealt with the issues of concern identified during the audit and a time frame for commencement and completion of any planned work.