Why Dublin’s River Tolka’s defences may offer hope for flood-ravaged towns
Significant tracts of the country were engulfed by recent flooding and the threat continues to hang over many counties.
But the story of the River Tolka, which runs from Meath, through Drumcondra and enters Dublin Bay at East Wall, shows that a marriage of political will and engineering prowess can truly help.
Driven by two flooding incidents along the waterway in 2000 and 2002, and turbocharged by a cameo from a wellington-clad taoiseach Bertie Ahern, the Tolka’s flood defences rapidly materialised.
Despite the challenges of working on a large-scale infrastructure project across three local authorities, Dublin City, Fingal and Meath, works began within a year of Mr Ahern’s visit and were finished in 2009.
Gerard O’Connell, a senior engineer with Dublin City Council (DCC) who worked on the Tolka scheme, was there when Mr Ahern was wading through a waterlogged Drumcondra.
“I was standing not too far from him and we had an inspector within six foot in case he fell in,” he said.
“The water was nearly up to the top of his borrowed wellingtons.”
Mr O’Connell said that after the 2002 floods, the scheme advanced rapidly.
“It was, I suppose, so near Bertie’s office as well, at the time,” he said.
“The pub across the road, Fagan’s, the basement of that was flooded and I think he frequented there from time to time.”
A lot of the modelling of the river had been done already, so that’s why it could be done so quickly
Mr O’Connell said the unusually quick pace of delivery was down to more than just politics.
“Originally, the river was being looked at as part of the greater Dublin strategic drainage scheme and we had consultants on board for that and then when this flooding occurred, the Office of Public Works (OPW) came in big time,” he said.
“But a lot of the modelling of the river had been done already, so that’s why it could be done so quickly. We also got planning permission incredibly quickly on it.”
In terms of the interventions made for the scheme, Mr O’Connell said it was a mix of flood walls, raised embankments along the greener sections of the river, heightened bridges and widening the river for a short section.
Another contributor to its success is its relative simplicity, with other schemes often requiring the erection of temporary flood barriers. “There’s only one flood gate on the whole scheme and it’s rarely used. So that’s kind of the beauty of it that it needs very little human intervention,” he said.
The scheme has been tested many times since 2009, including over the last week, but has held up on each occasion.
Now, Mr O’Connell is focused on DCC’s next phase of the River Dodder flood relief scheme, stretching from Clonskeagh to Orwell Bridge.