A €2 billion tidal barrier for the city, a modified Salmon Weir Barrage, an offshore breakwater opposite Salthill, and massive landscaping of the Corrib and coastline are all options rejected before the next stage of Galway’s massive flood relief plan begins.
Instead, a briefing last week from the Office of Public Works (OPW ) on the immense Coirib go Cósta project highlighted a range of hyper-local flood defence options for 13 areas of Galway city to be progressed.
The OPW’s expected cost projection - of at least €50m, depending on options chosen and level of finish – did raise eyebrows amongst participants at the media briefing, where there was an expectation of a price tag in the hundreds of millions. The cost has increased since initial estimates of just over €9m were made three years ago.
With the economic cost to Galway of ‘doing nothing’ calculated to be €50m over ten years, OPW officials said they were “confident of a cost beneficial scheme for Galway, protecting more than 1,000 properties from once in a century river flooding, or once in 200-year coastal events.”
Officials explained how detailed hydrological and hydraulic studies of Galway’s coastline from Salthill to Ballyloughane, commenced in 2020, are now complete. These include analysis of the River Corrib, Terryland catchment, city waterways, Menlo and Lough Atalia.
A selection of preferred flood defence options have been identified, and project designers from Arup and Brady Shipman Martin architects are now seeking public input before detailed plans are drawn up. Planning applications are expected by 2027.
A virtual engagement room has been set up online (see www.coiribgocosta.ie ) where members of the public can assess detailed proposals, view artists’ impressions, read technical reports, and make submissions until July 18.
Most coastal areas from Salthill to South Park and into the city centre have – broadly speaking - three options, although each of the 13 elements is unique. The area around the Harbour Enterprise Park has been omitted until planning decisions are made on harbour housing and deep water dock extensions.
Option A is a c1.4m wall along seafronts and quaysides. Option B is a wall a few yards in from the coast with demountable barriers across pedestrian entrances, and Option C is allowing coastal areas to occasionally flood, with walls on the landward side of coastal roads to prevent surging water to flow inland.
Options A and B may involve the raising ground level in several areas with massive amounts of fill necessary. Options B and C may involve temporarily blocking some roads during flood events, and making certain coastal routes permanently one-way for vehicle traffic.
Expense and efficiency
Some flood engineering proposals, such as a breakwater opposite Grattan Road, channel widening and dredging were rejected as inefficient. Others, including a tidal barrier and Natural Flood Management (NFM ) proposals, were rejected as too expensive.
A barrier extending from Mutton Island to Hare Island and then to near Ballyloughane, including valves for releasing river water and allowing shipping through, was estimated to cost €2bn, based on similar proposals for Cork harbour.
The NFM plan of small dams, tree planting on flood plains, and erecting large earthen embankments, was deemed too slow to implement with climate change concerns pressing, and legally complex with land ownership issues.
Senior city officials were present at the OPW briefing. They anticipate substantial public engagement on certain areas of the flood defences, especially around Spanish Parade and Salthill’s Prom.
Submergible paths, terracing, disguised flood walls, raised roads, embankments, and integrating existing buildings into flood defences, are all proposed solutions for various parts of the city.
Toughened glass coastal walls are understood to be out of favour within the OPW at present, while complex micro projects to raise historic structures, such as the Spanish Arch, are unpopular amongst local authority officials.
A three-year construction of vital flood defences is expected to begin by 2030.
