Is enough being done to keep Dublin Bay safe for swimmers this summer?

Malfunction at upgraded part of Ringsend plant, increased construction in the city and a leaky legacy are muddying the waters.

By Cónal Thomas

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WHETHER IT’S LEAPING off the Forty Foot in Sandycove or taking a leisurely dip at Seapoint, Dublin’s coast features some cracking swimming spots. Dublin Bay, a UNESCO-designated biosphere, is home to 300,000 Dubliners and plays host to a variety of plant and animal life.

Yet recent overflows at Ringsend Wastewater Treatment Plant forced eight of the city’s most popular bathing spots to close earlier this month. On Monday, Dollymount Beach was again closed to bathers after another overflow at Ringsend – an occurrence Irish Water has said happens 15 times annually. Later that evening, Dún Laoghaire-Rathdown County Council announced a swimming ban at Seapoint, Sandycove and the Forty Foot pending water testing.

And in February, 100 cubic metres of sludge entered the River Liffey’s estuary near Dublin Bay after 300 tonnes of waste entered the plant and a tank at the plant failed. 

How did these incidents occur? And what is being done to protect the bay and people living near it from any future sewage discharge?

With Dubliners left wondering when their beaches will reopen, several factors are converging that mean more strand closures could be in the offing.

As part of this investigation, Noteworthy discovered several moving parts increasing this risk, including:

  • Legacy issues with Dublin’s sewerage system;
  • Growing opposition to a new proposed wastewater facility on the northside;
  • A mechanism at a recently-upgraded reactor at the Ringsend plant broke;
  • And construction in the city which contributed to February’s sewage spill. 

Source: Shutterstock/Semmick Photo

The February Spill

On Saturday 23 February, a large discharge occurred at Ringsend, entering the water at Poolbeg, about 1km from the plant.  The discharge – which lasted for 20 minutes – caused 100 cubic metres of activated sludge to enter the bay.

The leak only came to light after one Dubliner used a drone to capture images of the effluent on Saturday evening, bringing the matter to public attention. Locals were alarmed at the brown mass of sewage seeping into their waters, the colour of which was caused by low tidal levels, sunlight, wind direction and water temperature on the day.

At the end of Ringsend pier on the Great South Wall near the plant sits the popular Half Moon Swimming Club established in 1898. Around the headland from the pier is Sandymount Strand, one of eight beaches closed to bathers three weeks ago after a storm water overflow occurred at the Ringsend plant.

Built between 2003 and 2005, the Ringsend Wastewater Treatment plant currently treats 40% of the country’s sewage.  Before Irish Water was set up, Dublin City Council planned to upgrade the plant and install a discharge tunnel into the sea.

However, due to advances in technology, Irish Water – responsible for water management since January 2014 – instead opted to invest over €400 million in the staged upgrading of Ringsend. Operated by Celtic Anglian Water, under contract to Irish Water, the utility found itself answering questions following February’s discharge of sludge. 

Bay. February's overflow resulted in 100 metres cubic metres leaking into the LIffey estuary.
Source: Eoin O'Shaughnessy

What went wrong?

At the time of the leak, Green Party councillor Claire Byrne called for Irish Water to “come clean” on any long-term issues with the plant, saying another similar incident took place in October 2017 during Storm Brian.

“The company is constantly reassuring local representatives that the plant is working well when the reality is clearly different,” Byrne said.

One major criticism of Irish Water at the time was the way in which it communicated the incident. Only after drone footage became public did the utility act to communicate what occurred to the public.

Irish Water has subsequently said that the way in which the spillage was managed and communicated “did not meet the standard” it considers acceptable.

“It is accepted and acknowledged that more could have been done to identify the potential for plume formation and to notify stakeholders and the public of same.”

Due to the plant operating beyond its capacity, “it is impossible” to penalise Celtic Anglian Water, a report into the incident later noted.

The failure of one tank at the plant was a contributing factor to February’s incident, Irish Water has said. This breakage occurred when a diffuser head in one of the plant’s 12 batch reactors came loose from the pipeline system, the Environmental Protection Agency (EPA) has confirmed.

Irish Water has said this breakage was responsible for only 3% of the suspended solids from February’s spillage.

Now, for the technical part.

A batch reactor converts effluent from being pathogen-bearing to non-pathogen bearing. (A pathogen is anything that can cause disease). In an on-site report from 7 February, the EPA notes that the 12 batch reactors at the Ringsend plant “will be converted to the Nereda process”. (The Nereda process is a specific method of purifying wastewater.)

“One tank has been converted and it is currently achieving Licence compliance,” the EPA report notes. 

This batch reactor  is the only one to have been upgraded to the new [Nereda] process to date, an EPA spokesperson confirmed. 

“This situation is rather serious,” Joe McCarthy of national trust An Taisce remarked at a February meeting of Dublin City Council’s environment committee, when he raised concerns about the breakage in the only upgraded tank at Ringsend. 

“It would seem to be failing at its first test.”

Questions were asked and in March, Irish Water published a report of its findings. Irish Water has said that this breakage is a relatively innocuous occurrence in wastewater treatment and can happen quite easily given the current pressures on the system, regardless of treatment process. 

The primary cause of the plume visible in the estuary instead, it noted, was “persistent solids” that entered the treatment plant in the weeks leading up to the spillage.

The report, obtained by Noteworthy under the Freedom of Information Act, notes that “the inability of the already overloaded plant to deal” with these solids was a major factor in the spillage. Yet the report also notes that after the effluent that leaked into the Liffey estuary was analysed it became clear that it was also full of solids not from wastewater but from an increase in construction activity across the city.

Local Labour councillor Dermot Lacey told Noteworthy that “probably no part of Dublin has been more developed in the last few years than Dublin 4″. He said: “It has seen a huge increase in population.”

Closed beaches

Dubliners were again inconvenienced earlier this month when swimming at eight Dublin beaches was prohibited after heavy rainfall caused what’s known as “stormwater overflow” at the Ringsend plant. It’s important to note that February’s spillage into the Liffey estuary and this month’s beach closures are different and had distinct causes.

Due to heavy rainfall during a yellow weather warning event in early June, there was a storm water overflow from the Ringsend plant – not an overload of untreated solid sewage. A spokesperson has said that the plant “operated as it should” in this instance and was in compliance with regulations” following the heavy rainfall.

Sandycove. An algal bloom present along Dublin's coast over the past number of weeks at Sandycove beach on Tuesday morning.
Source: Flossieandthebeachcleaners/

Capacity issues at Ringsend are one issue. But Victorian design – common in many cities in Europe – has resulted in overflows into Dublin’s waters becoming a common occurrence. In 1851, Dublin City Engineer Parke Neville was tasked with redeveloping Dublin’s inadequate drainage system. During this period, there was growing public awareness about the link between contaminated water and poor hygiene.

Dublin required ‘interceptor sewers’ to deal with foul water from the River Liffey, Neville realised. The city built one on the northside and one on the southside. ‘Storm water’ pipes (carrying rain from gutters and drains) enters the sewerage system and runs separately but alongside foul water pipes (carrying sewage). Originally designed for a population of 325,000, Dublin’s wastewater treatment facility was first built at Pigeon House Harbour, Ringsend. Over time, this facility grew as Dublin’s population boomed. 

So what happens?

The current Ringsend plant can manage a water flow of 11,000 litres per second. If that volume is breached, the water flows into a storm water holding tank which is then fed back into the normal tank, treated and discharged.

However, in periods of heavy rain the plant settles the contents of the tank, screens it for debris and release it into the environment.

“This is standard practice in wastewater treatment plants around the world,” a spokesperson for Irish Water said.

Essentially, the plant releases the overflow into Dublin Bay. This happens on average 15 times per year, a spokesperson for Irish Water said, particularly in winter.

“The overflows operate in this way to ensure that raw sewage does not back up in the network and end up bubbling up into people’s front gardens,” the spokesperson added.

As a result – and as a precaution – Dublin’s beaches are closed and bathers are advised not to swim as bacteria might be present. If future city planners wanted to prevent storm water overflowing and mixing with sewage, separate collection systems would be built, a spokesperson for the EPA has said.

Irish Water plans to increase capacity at the Ringsend Wastewater Treatment plant from 1.6 million PE [population equivalent] to 2.4 million PE in 2025. John O’Donoghue, Regional Operations Manager with Irish Water told Newstalk Breakfast yesterday that the upgrade “won’t completely eliminate the overflow but it will help”.

In the meantime, Irish Water is awaiting a decision from An Bord Pleanála in relation to its proposed facility at Clonshaugh in north Dublin which, the utility says, will reduce pressure on the Ringsend Wastewater Treatment System.

But for locals, the prospect of another large treatment plant – which Irish Water says will “protect public health and safeguard the environment” – is a step too far. 

Plant. Ringsend Wastewater Treatment Plant
Source: Sam Boal/

Local opposition

Locals last week expressed fears that Portmarnock beach – a popular swimming spot – will be affected by Irish Water’s ambitious Clonshaugh proposal. The facility – which Irish Water submitted for planning permission in June 2018 – will essentially form a new regional wastewater treatment facility.

According to a spokesperson for Irish Water, it’s a “vital project” which “will help to ensure that the wastewater generated every day in our homes, schools and workplaces will continue to be treated safely in compliance with the EU and national wastewater treatment regulations”.

“As part of this planning application, extensive research was undertaken to assess all potential impacts of the project on the environment,” they added.

“This confirmed that the proposed project will not have a perceptible impact on the water quality of the coastal waters off Dublin, will not negatively impact any local bathing waters or Blue Flag beaches and is the most environmentally, technically and economically advantageous solution to meeting Dublin’s long-term wastewater treatment needs.”

Local campaigner and filmmaker Declan Cassidy has said, however, that this systematic “standard practice” of discharging excess effluent into Dublin bay treats sewage “as a problem”. Cassidy argues that, while treatment facilities are necessary, alternatives exist.

The Solution, Not Pollution campaign aims to prevent the Clonsaugh plant’s construction but also to highlight that sewage needn’t be disposed off into Dublin’s waters. It can instead, Cassidy has said, be harnessed to tackle climate change.

An Bord Pleanála is due to make a planning decision on the Clonsaugh plant on Friday. 

An overloaded plant

Are spillages into Dublin’s waters likely to continue? Most likely.

The European Court of Justice has already ruled that Ireland failed to uphold EU regulations for almost 30 of its wastewater treatment plants across the country -  a fact well-known to those working at Irish Water.

The Ringsend plant is currently operating over capacity, has been for several years and does not comply with the Urban Waste Water Treatment Directive. This Ringsend plant upgrade – due to be completed by 2020 – will allow for wastewater treatment for an additional 400,000 people, Irish Water has said.

The plant can only process 101 tonnes of solids per day. But on that Friday in February -  before effluent leaked into the estuary – 300 tonnes of solids arrived at the plant for treatment.

Irish Water has since recommended that real-time photography be installed at the Ringsend discharge point, has said it is working to ensure better communication with stakeholders after discharge incidents as well implementing measures to increase sludge removal from the Ringsend plant.

The company’s report into February’s incident lays bare the reality facing both the wastewater treatment plant and Dubliners in the years ahead.

The report said: “The inability of the plant, in its current guise, to adequately treat the load arriving at the plant, is common knowledge and Irish Water, Celtic Anglian Water and Dublin City Council are consistently working daily to minimise the extent of the exceedances.

“It should be stressed that the plant is significantly overloaded and that once these elevated solid levels arrive at the plant through the network, it is impossible to guarantee that the plant will be able to reduce and eliminate the solids content”. 

- Additional reporting by Ken Foxe.

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