Analysis:Dublin City Council plans to dump up to 800,000 tonnes of material in Dublin Bay from its tunnelling operation to lay pipes there.
Alternatives to dumping the material on the seabed were given consideration by the local authority before it went for the dumping at sea option.
Dublin City Council could proceed to requesting a dumping licence only after it had exhausted several other, preferable options to dispose of the material.
The European Communities (Waste Directive) Regulations 2011, transposed into Irish law from EU regulations, are designed to encourage recycling, to promote waste prevention and to protect the environment.
It lists the options of "re-use, recycle and recovery", and says that a final possibility of disposal "is the least favoured option, and applies to land filling (or sea disposal) operations".
Alternatives ruled out
In a detailed licence application, council officials systematically outlined how each of several alternative options had been ruled out.
The material was unsuitable for infill in engineering projects as the State's construction sector had come to a halt, leaving "little or no demand".
Although it could be utilised in road builds, the National Roads Authority (NRA) said it had no suitable projects pending.
It is also unsuitable for the creation of wildlife habitats, and the Office of Public Works, when queried on the issue of coastal nourishment measures, said the "angular" nature of the bored rock would prove unsuitable in the place of rounded stones.
The tonnage could also be used for infill at ports - but again, this was not considered a viable option.
Plans for suitable works at Dublin Port are too undeveloped at this stage while Bremore Port near Balbriggan in north Co Dublin would not be applying for planning permission until 2015, rendering the timelines incompatible.
Rosslare Port would welcome the material but their plans are also at too early a stage.
"They have confirmed their interest in the spoil from the Ringsend project as infill material," the application states.
"However, their project has yet to be submitted for planning permission and therefore does not fit in with the timescale of this project."
Similarly, projects in the UK are not suitable in terms of timing.
Recycling
In some cases, material like this might be used for recycling into concrete products but investigations in this area also proved fruitless.
"From discussions with Roadstone it is considered that recycling for reuse as an aggregate [element of concrete] is highly unlikely due to the quality of the material and based on experience from the Dublin Port Tunnel and the high dust content of the spoil," it says.
There is also a small element of pyrite in the material.
Council officials had expressed their concerns at the notion of transporting the material by road through the local community, which would involve more than 70,000 truck loads.