Four alarms warning about the increased cloudiness of water at a Co Kildare water treatment plant that led to a boil water notice affecting 600,000 people in October went unheeded.
Detailed records released by Irish Water show that high-level alarms sounded over a period of 51 minutes on the evening of October 21st last at the Leixlip water treatment plant warning about higher levels of "turbidity" or cloudy water due to suspended particles in the source water.
Risks posed by potential contamination as a result of the breakdown of the disinfection process at the plant led to the largest-ever boil notice being issued in the country – affecting 615,539 people in Dublin, Kildare and Meath.
Irish Water records, released to The Irish Times under the Freedom of Information Act, show that problems with the disinfection process at the plant began at 3pm and that no action was taken until 9.20pm when the first attempt to solve the problem was made by switching pumps.
This was despite four alarms specifically warning about higher levels of turbidity in the source water being triggered at 6.16pm, 6.17pm, 6.22pm and 7.07pm, according to a presentation document prepared by Irish Water for an audit by the Environmental Protection Agency (EPA).
The operator was only alerted after an off-duty manager happened to spot the high levels of cloudiness in the water when he logged on to the plant’s system for an unrelated issue.
Irish Water listed seven “red flags” where preventative measures were missed, including graphs that should have alerted the operator to rising turbidity and text messages to his phone.
“Multiple alarms not responded to by operator,” said Irish Water in the document presented to the EPA during its October 24th audit of the plant.
Other indirect “red flags” that should have been spotted were the visual and physical evidence of a leaking pump and the visual condition of the water filters, said the company.
The presentation says there was “no operator intervention” as the cloudiness of filter water continued to rise above elevated levels from 7.50pm on.
At 9.15pm, the assistant plant manager logged on remotely to the plant’s system “on an entirely unrelated matter” and “happens to notice” that the turbidity levels across all filters was “extremely high”.
Fifteen minutes later, the assistant plant manager phoned the operator “who advises that he has just noticed the high turbidity”, states the presentation document.
At 10.15pm the rostered on-call manager decided to manually shut down the old plant.
At 10.40pm there was a shift change and a new plant operator took over and 10 minutes later identified cause of the problem “as being the blockage in the alum [aluminium] dosing line” – which treats the water – “and the pressure release valve having been ‘blown off.’ ”
Within an hour, a contractor was called to the plant and cleared the blockage, managing to complete a “temporary repair”.
By 5am the following morning turbidity levels had returned to normal.
Irish Water’s investigation found that the initial cause of the “alum dosing” failure was a blockage in the dosing line causing the pump “to ramp up to maximum capacity”.
The company found that an operator might have reduced the low-flow set-point on the “alum flow” reaching the raw water below 50 per cent of that required “to facilitate a restart of the plant on a previous occasion and forgot to reset it to its operational value”.
Simple water conservation actions such as turning off the tap while brushing teeth or shaving can save up to six litres of water per minute
Fingal County Council, which operates the plant under a service-level agreement with Irish Water, declined to say whether the operator on duty on the evening of October 21st was the same one working on the night of March 13th who failed to respond to an alarm warning of elevated aluminium and turbidity levels in final treated water in a separate incident.
A spokesman for the council said it has “no further comment in relation to ongoing investigations at this time.”
Utility appeal to conserve water
Irish Water said that it noticed a reduction in demand immediately after appealing to people in the greater Dublin area to conserve water over Christmas almost two weeks ago.
The company reminded customers to use only what they needed over the festival period as the risk to supply still exists while it upgrades treatment plants in the area, including the one in Leixlip.
Simple water conservation actions such as turning off the tap while brushing teeth or shaving can save up to six litres of water per minute, said the company. The utility also added that keeping a jug of water in the fridge instead of running the cold tap can save 10 litres of a day.
Water production capacity has been reduced as work continues on the old Leixlip water treatment plant that supplies hundreds of thousands of homes in Dublin, Kildare and Meath.
Irish Water said at the launch of its appeal on December 11th that the increase in demand was higher than in any previous year. And at 10 million litres higher a day it was the same amount of water needed to fill Liberty Hall in Dublin.
