Levels of silt in river ‘being addressed’

Heightened levels of silt in the River Shannon in Athlone, which have arisen from construction work on the town's new cycleway bridge, could be harmful to fish if not addressed, Westmeath County Council has acknowledged.

The local authority said steps were being taken to manage the issue after clouds of tea-coloured silt dramatically discoloured the river near Athlone's town bridge during the last fortnight.

The council said the project team on the new bridge had been "in consultation with the statutory bodies" about the recent silt disturbances.

The matter affected progress on the construction of the bridge's central pier last week, though the council said it did not expect it to delay the overall timescale for the project.

After being contacted by the Westmeath Independent, a spokesperson for Westmeath County Council issued a statement saying it was aware of the recent "discolouration event" and knew what had caused it.

A cofferdam is an enclosure built in a body of water to allow the enclosed area to be pumped out. The council said the issue arose when water was being pumped from a cofferdam in the Shannon "to facilitate the excavation for the central pier foundations" of the cycleway bridge.

It said that "additional filtration systems and sedimentation tanks" had been put in place in the river to "reduce the intensity of naturally occurring silts entering the watercourse."

The response added that "elevated levels of this naturally occurring fine silt" may be harmful to fish if not addressed.

It said the project team working on the cycleway bridge was "in consultation with the statutory bodies" on the matter, and it was agreed "to cease any further discharges" of pumped water from the cofferdam until "an improved engineered solution" was put in place.

“Daily monitoring of water turbidity on the river has been ongoing and will continue when this element of works recommence,” the council spokesperson added.

When asked if the need for a new engineering solution to be found would delay the construction of the bridge itself, the council replied: “Although progress on the central pier has been impacted in the last week, it is not currently envisaged that this will have a negative impact on the overall programme.”

Photos of the river’s discolouration prompted plenty of comment on social media recently, with some voicing concern about possible ecological impacts, while others played down the issue as being relatively harmless.

Jons Civil Engineering Ltd, the Meath-based firm which is the contractor for the bridge, started its in-river construction work last month. Previously, its work had concentrated on the east and west banks of the river, adjacent to the Radisson Blu Hotel, beside the Luan Gallery.

In August of last year the company was awarded a contract worth approximately €13 million for the construction of the bridge and cantilevered boardwalks that will connect with it on both sides of the river.

It’s anticipated that the bridge will open for use by cyclists and pedestrians next Easter.