The Environmental Protection Agency is investigating the leakage of up to one million litres of insulating oil from underground electricity cables in Dublin over the last 20 years.
The Electricity Supply Board notified the agency about the issue at the end of May, following a series of disclosures last year relating to safety by whistleblower Seamus O’Loughlin to the company and to the Department of the Environment.
Central to Mr O’Loughlin’s claim is that insulating fluid from about 160kms of underground, low pressure, fluid-filled cables, almost all of which are between the canals in Dublin, has been leaking into the ground at a rate of about 40,000 litres per year over the past two decades.
The fluid in the cables is a mixture of mineral oil - which was used until the late 1980s - and linear alkylbenzene, a lighter, biodegradable fluid.
The majority of the leaks are caused by the age of the cables, most of which were laid between the 1950s and 1980s and are starting to degrade. Subsidence and building works can also puncture the cables.
In some cables, the outer casing is made of lead and deteriorates over time, causing leaks. The fluid leaking out is potentially entering the ground water system under Dublin and also into watercourses, including rivers and canals, Mr O’Loughlin said.
Also among more than a dozen concerns raised by Mr O’Loughlin in a series of disclosures are concerns about the management of building works near the underground power cables. He cites one recent example of the cable on Harcourt Street being pierced during building works.
This could have led to a significant incident, he warned. As it happened, on that day, the cable was punctured, the cable was not live.
A spokesman for the ESB said "a review of our records indicates that between 1998 and 2014 the average annual [leakage] rate was in the order of 40,000 litres."
It said the leakage rate has been on a downward trend in recent years - with exception of 2018 - and it is on course to reduce the leakage this year to 8,000 litres. The company said this is in line with “international peers in other countries (measured on a litres per kilometre basis).
“It is important to note that the cable insulating fluid is readily biodegradable. Notwithstanding this, ESB Networks acknowledges that it is preferable to minimise and eliminate leaks.”
The company said it is engaged in a long-term cable replacement programme.
In a statement to The Irish Times, the EPA said it was concerned by the reports of leaks from the power cables and particularly the scale and duration.
It said it was notified on May 27th by the ESB in relation to the leaks. It is understood the notification from the ESB followed a series of questions to the utility from RTÉ Prime Time Investigates, which will broadcast a programme on the issue on Wednesday evening.
“The report of the alleged leakage of large volumes of oil to the environment over an extended period is of concern to the EPA.
“On May 27th, 2019 the EPA received correspondence from ESB Networks regarding their reporting obligations in relation to leaks from underground fluid filled electricity cables,” the EPA said in a statement.
“Given the alleged scale and duration of these incidents, and the correspondence received this week from ESB Networks, the EPA will investigate this matter and liaise with the relevant local authorities to determine what, if any action is required.”
According to RTÉ, ESB internal documents state the material leaks from these cables could present a “very high environmental impact, given the proximity to the Grand Canal”.
The documents also state the underground cable oil is “not considered compatible with watercourses and the associated eco systems, rivers and canals”.
Mr O’Loughlin, who worked with the ESB for more than 20 years, says when he saw the scale of the leakage, he found it difficult to comprehend. “It was so far ahead of what the UK and other international utilities were experiencing. I was astounded that a company like ESB would allow that situation to pertain,” he told RTÉ.
In a statement, the ESB said it has started a number of investigations into the claims made by a whistleblower and they should be complete by the end of June.
The company said it has introduced new management processes for building works near the cables and has also set reduction targets for leakages from its cables based on benchmarking against other, international utilities.
The ESB also said that it has, since 2006, been required to report to the Commission for Energy Regulation (CRU) "on environmental performance under its Distribution System Operator licence. This requirement has included reporting on cable insulating fluid leakage and we have complied with this requirement."
In a statement, the Department of the Environment said it “can confirm that a protected disclosure was made to the Minister for Communications, Climate Action and Environment in May 2018 and the matter has been and continues to be dealt with in accordance with the Protected Disclosures Act 2014.
“The Department has engaged and continues to engage appropriately with the individual concerned and the company.”