How about a new island for Dublin Bay?

First Published: Sunday Times in Ireland, May 2013

 

Now there’s a thought.

This might just be the answer to the challenge that Dublin City is facing over what to do with almost a million tonnes of spoil from the bottom of Dublin Bay. A new island might just be  what’s needed.

It’s part of the final phase of what is known as the Dublin Bay Project. This is an ambitious plan to improve the water quality of Dublin Bay by improved waste water treatment, and building a pipe to send some of the waste water further out to sea.

The Liffey Estuary was designated as a nutrient sensitive water body by the Department of the Environment in 2001, and so the city has to reduce the amount of nitrogen and phosphorus that discharge into these waters close to the shore. The plan is to invest in further sewage treatment at the Ringsend Waste Water Treatment plant, and to construct an underwater tunnel four and a half metres in diameter that will discharge the treated sewage nine kilometres out into Dublin Bay. This is not cheap. It will cost around €222 million to build, and around €3 million per year to operate.  Dublin City Council made an application to the Environmental Protection Agency (EPA) to construct the works and dump the spoil at sea. The Environmental Impact Statement (EIS)  estimates that the rock spoil from the  excavations will be in the order of 847,500 tonnes, or around half a million cubic metres in volume. In April 2013 Dublin City withdrew their Application because some of the documentation regarding assessments and environmental impacts was not received in time to allow members of the public to make observations.

An other proposal put forward in the Environmental Impact Statement is to truck the waste through Dublin City for re-use or disposal in landfill. This would involve thousands of truck movements and wouldn’t be that popular an option from those who live close to the proposed route.

Maybe now is the time to consider an alternative approach?

I’m wondering could we carefully place the the rock spoil out at the edge of Dublin Bay on top of the Burford Bank and create a new island.  the Burford Bank is the vertical bar that can be seen on the right hand side of the chart above. The water is fairly shallow there: only about three fathoms or five and a half metres deep at the lowest tide. Arranging the spoil in a ten metre high mound resting on the sea-bed could produce a new island ten kilometres to the east of Ringsend. Such an island could be an amenity that Dubliners could sail, motor or row out to on a summers evening, you could even plant a few pine trees, put in a pier and and a few picnic tables. The island itself might be roughly one hundred metres in diameter, with a rock reef to protect it from erosion. The area around the island could be designated as a marine park, and might protect vulnerable marine species from over-fishing in the water s nearby. Needless to say there’d need to be an architectural competition held to come up with the best design for the project. It could be a great way of celebrating the improvement in water quality in Dublin Bay that would result from  the new outfall pipe. Of course the underwater hydrology would have to be carefully considered, but it might have a secondary function of helping to protect vulnerable coastal areas such as Clontarf from Easterly gales. Any proposal would have to respect the OSPAR Convention that protects the north-east Atlantic from pollution, as well as the various European Union Directives that protect our coast.

What would such an island look like? Well, here’s a link to a similar island  located a few kilometres away from Copenhagen in Denmark. There’s also a useful article by Wheeler, Walshe and Sutton from University College Cork on the seabed of Ireland’s east coast near Dublin here, and some seabed mapping from the Celtic Voyager seabed surveys here. Currently the City of Amsterdam is building new islands by using rock and sand from dredging shipping channels. It’s just an idea, and something that perhaps the Dublin City Council and the EPA could consider in their deliberations in advance of a new application for Dumping at Sea.

In 1801 Captain William Bligh, of Bounty fame surveyed the Liffey Channel and proposed extending the harbour walls so that ships could travel safely into Dublin Port. As a bonus Bull Island was created. Perhaps today’s plans to upgrade Dublin’s sewage treatment could give the city an amenity that would improve Dublin for the next two hundred years.  If we’re going to spend €220 million on Dublin’s sewage treatment upgrade, then let’s do something interesting with the waste rock and mud. In my mind a new island sounds like a good idea.

Currently the options for dealing with the waste from digging the 9km tunnel are to make it disappear, just like Steve McQueen did in “The Great Escape” where the earth from digging an escape tunnel was spread all over the prison yard.  The alternative is to truck it out through Ringsend and the Dublin Port Tunnel to a landfill site. I’m suggesting a third option, and it might be cheaper, the building of a new island in Dublin Bay.