On Monday 15 November, Leona Cully took a stroll along the stretch of River Tolka that passes through Griffith Park in Glasnevin on her lunch break and noticed a thick smell of diesel.
“When I looked into the water, it was brown and slick with that kind of shininess that you get when there’s an oil spill,” she said, last week.
A small crowd huddled around the water and some took photographs, Cully said. “And someone actually reported it straight away.”
Emma Finlay, a senior executive engineer at Dublin City Council’s environmental protection department, says the incident was an oil spill.
“Contamination was found to be entering the River via a tributary which outfalls downstream of St Mobhi Road Bridge,” said Finlay in an email.
It’s a big catchment area and hard to tell what had caused the spill, she said, especially now that it’s cleared. But “from experience the source is believed to be from an accidental spillage/leak from a private home heating oil tank that has since been resolved locally”, said Finlay.
Finlay said they don’t know how often such tanks leak and contaminate Tolka or Dublin’s other rivers. “Spillages from home heating tanks are a private matter and are rarely reported to Dublin City Council,” she said.
On a cold and crisp morning on Saturday 27 November, over ten days after the spill, Brian Gray, a Glasnevin local, kept finding traces of oil on the site of the pollution as he pulled out rubbish from the river.
“You can definitely smell it here,” shouted Gray, almost knee-deep in the river and stirring a patch of water that looked cloudy with a litter picking stick. A stench of diesel spread in the air.
One-off oil pollution episode isn’t that harmful if the river is well looked after, says Pádraic Fogarty, campaign officer at the Irish Wildlife Trust.
The Tolka, though, isn’t, he said.
Agricultural run-offs often find their way into Tolka, he says, and urban waste too. “Including ‘misconnections’ whereby wastewater from houses is going into the pipe going to the river instead of the treatment plant in Ringsend.”
Oil pollution is harmful even fatal, he says, as “it doesn’t easily break down and any animal coming into contact with it, especially birds or mammals like otters will be badly affected”.
Tolka’s wildlife has proved resilient though, Fogarty said. “And near where I live has one of the most amazing rewilding areas that is full of life, even with the pollution.”
Dublin City Council samples the Tolka in Griffith Park every month, says Finlay, the senior engineer at its environmental protection department. They took a sample on 15 November, too.
Its results show that the river was polluted on 15 November, says Alejandro Criado, a wastewater scientist in Dublin.
The sample showed a high level of chemical oxygen demand (COD), said Criado. COD measures the water’s chemical compounds by checking how much oxygen they use.
High COD levels “suggest that there was an emission of high organics into the river”, said Criado.
It means, he says, that biodegrading bacteria are dirtying Tolka, and it can come from high-carbon pollutants like domestic sewage, or hydrocarbons like diesel and petrol.
“On-site investigations have noted strong smell of diesel, which indicate that pollutant may be hydrocarbons which commonly leak from household heating systems or filling stations,” said Criado.
Finlay, the council engineer, said that: “Water Pollution Control continue to liaise with Inland Fisheries Ireland on the matter.”
In Dublin city, more than 12,000 houses relied on oil for heating in 2016, according to Central Statistics Office (CSO)figures.
Finlay says oil spills from heating tanks are rarely reported to Dublin City Council.
Investigating oil leaks from private tanks is up to local authorities, a spokesperson for the Environmental Protection Agency (EPA) said. “The EPA has no role in investigating these. As such we do not have any data on the number of such incidents.”
Gray, the Glasnevin local, who volunteers with others to litter pick at the river every two weeks, says he went for a run along the Tolka in Griffith Park after hearing on Wednesday 16 November about the oil spill.
He saw a boom on the river then, he says, a floating barrier that can suck the oil out of polluted waters.
“It was black dark, so I saw the boom, but I couldn’t see a whole lot else, and I wasn’t gonna get into investigating it then,” said Gray, last Saturday.
He was pulling on his waterproof waders that help him keep warm and dry in the water, prepping to jump into the river to clean it. As he cleaned, he kept spotting the oil residue in the water.
Maybe the council should have kept the boom in longer, he says. “When there’s going to be heavy rain, the rain moves the oil along the river.”
Finlay, the senior engineer at the council’s environmental protection department, said the river was monitored daily.
“Following satisfactory visual inspections, the boom was removed from the river this morning,” said Finlay in an email on 23 November.
The End of Oil Tanks?
Gray says he had made sure his house’s heating was not reliant on oil, but that not everyone can afford to do that.
Reporting tank leaks isn’t something that crosses everyone’s minds either, he said. If an oil boiler starts leaking, owners will fix or replace it.
But “ I don’t think they say we need to tell somebody that all this oil has gone into the ground, I won’t say that’s the last thing on their mind, but it definitely won’t be the first,” he said, standing outside Griffith Park, with a stash of rubbish pulled out of Tolka including an old-fashioned street lamp in its entirety.
Gray says he hopes that, in future, oil tanks would have to come with apparatus to absorb leaks and protect the environment.
That’s if they’re not totally extinct. “Hopefully, oil tanks are on their way out in Ireland,” he said.
The government plans to ban the installation of oil boilers from next year and gas boilers by 2025 in all new buildings, says itsclimate action plan 2019.
Gray pulls his pile of collected rubbish behind him on a small carrier as he strides toward the park’s exit.
An older woman, her dog was hustling after a small ball, stops to thank him.
Gray tells her about the oil spill.
She’d heard about one from years ago, but not a new one, she says, looking concerned. “Ah our lovely Tolka, we’re so proud of it,” she said.