Ahead of the scheduled opening of the Port Tunnel in Dublin later this year, city council engineers have drawn attention to what they say are leaks appearing in sections of the tunnel.
Documents and film seen by RTÉ News show leaking in a section between the two tunnels.
In June, engineers wrote to the contractors about the issue, saying the leakage was excessive. It was claimed that proposed arrangements to pump out the water were inadequate.
According to the city council, two leaks have been fixed, while there has been work to address a third fault over the past fortnight.
The council has said the concrete in a section of the ceiling is thinner than the 300mm specified under the original design.
The city council has stressed its good safety record on the project; it said the faults are being resolved and that leaks are common problems in tunnels.
Support for port link to Sandyford found
A new survey suggests almost 75% of residents in the south Dublin Bay area are in favour of constructing a tunnel or road connecting Dublin Port to the M50 at Sandyford.
The business group IBEC claims there would be big industry interest in a public-private partnership deal and has called on the National Roads Authority to take this into consideration in its upcoming review.
Dublin Port deals with 60% of Ireland's total trade and most trucks entering and exiting are obliged to go through the Dublin Port Tunnel.
But there are fears this could lead to major congestion, because even if a truck leaving the port wants to go to Waterford, it will have to exit the tunnel in north Dublin and then travel all the way around the M50.
An MRBI survey of 500 people in Sandymount, Booterstown and Blackrock found 74% are in favour of a southern link between the port and the M50 at Sandyford.
The poll found a tunnel would be the preferred option, with a motorway or causeway coming second if boring was too expensive.