Dublin’s stinking summers and pricey sewerage upgrades

Twenty years ago, following years of stinking summers and damning European water pollution reports, Dublin Corporation announced plans to end the practice of dumping raw sewage into the Irish Sea.

At the time up to 40 million gallons of sewage shot out of a pipe at Howth Head every day. In addition three boatloads of sludge – effluent treated to a very basic standard at the outdated treatment plant in Ringsend – were dumped each week 12 miles offshore.

In June 2003 the new Ringsend waste water treatment works began to operate. The following November Dublin City Council reached agreement with the then government to extend the plant, which had cost €300 million, because it could not cope with the amount of sewage it was receiving.

The plant did substantially improve water quality in Dublin Bay. Beaches that used to have severely polluted bathing waters, such as Dollymount, were able to meet “blue flag” standards.

However, even on its first day of operation, the plant did not meet the EU waste water treatment directive standard and a noxious smell persistently affected the surrounding communities for years.

Inability to cope

The smell was largely due to the plant’s inability to cope with the volume of waste pumped in from the city’s sewerage system. It had capacity to deal with the sewage of about 1.64 million people but was receiving sewage equivalent to a population of 1.9 million when the loads from industry were taken into account.

About €40 million was spent on odour alleviation measures and by the end of 2008 the problem was substantially fixed, but the capacity problem and the failure to comply with EU standards still needed to be addressed. However, it was not until 2011 that the council sought permission to extend the capacity of the plant to a 2.4 million population equivalent, including the construction of a 9km (5.6 mile) pipeline to take the treated waste water outside Dublin Bay for disposal.

Stumbling block

The council secured permission for the scheme from

An Bord Pleanála

in November 2012. But in 2013 the project hit a stumbling block when the

Sandymount

and Merrion Residents’ Association took a High Court action against the construction of the pipe.

The association lost the case but as a result of the delay no contracts had been signed for the scheme before the handover to Irish Water in January 2014.

Irish Water’s engineers said new technologies have emerged in recent years that are suitable for upgrading the plant at a far lower cost than the pipeline option. The Aerobic Granular Sludge (AGS) system has been in operation in the Netherlands for several years and since last year has been in use in plants in Clonakilty and Carrigtwohill, Co Cork.

This system is cheaper than the council's project, Irish Water says, but the utility's figures are difficult to grasp.

When first proposed, almost two years ago, it said that the new system would cost €170 million and it said the council’s pipe project would have cost €340 million.

Irish Water now says that the AGS plan will cost €300 million but that the council’s scheme would have cost about €500-€600 million.

Ringsend by the numbers

2003

€300 million Ringsend Sewage Plant opens.

2011 Dublin City Council applies for permission to extend the plant and build 9km outfall pipe at cost of €250 million.

2013 Cost is revised to €270 million.

2014 Irish Water says council pipe project would cost €340 million. It proposes Aerobic Granular Sludge system costing an estimated €170 million.

2016 Irish Water revises its project costs to €300 million and says pipeline would have cost €500-€600 million