Wind farm work caused bogslide, says report

The ESB subsidiary, Hibernian Wind Power, has said it accepts that construction work on its €60 million wind farm in the Slieve…

The ESB subsidiary, Hibernian Wind Power, has said it accepts that construction work on its €60 million wind farm in the Slieve Aughty mountains caused the major bogslide at Derrybrien in south Galway last October.

Mr Brian Ryan, managing director of Hibernian Wind Power, was commenting following the publication yesterday of a consultants' report on the bogslide.

He said the company would "fully implement" all 17 recommendations made in the report before there was any further construction activity.

Mr Ryan added that the company would not resume work on the site until given permission to do so by Galway County Council.

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The findings would have "implications for all wind farm developments in the State", he said.

However, residents of Derrybrien last night demanded that no further work resume until the location was assessed by the European Commission's environment directorate.

The directorate has confirmed it is investigating a complaint lodged by the Derrybrien community.

The report, by Applied Ground Engineering Consultants (AGEC), is the first of two studies on the landslide.

It identifies a combination of soft ground and work on the wind farm as the main cause of the landslide on October 16th, 2003.

No one was injured in the slide, which halted just in front of an unoccupied farmhouse. It caused substantial damage to Coillte forestry and land and to the Lough Cutra river system. Some 70 employees of contractors on site had to be evacuated.

The report confirms that a previous slide, or "failure", of peat had occurred on October 2nd during excavation for a wind turbine base.

Several other areas of "failure" and ground movement related to construction activity on three turbine bases are also identified by the consultants.

These occurred before the major slide, which took place in dry weather and which extended to 2,450 metres.

The consultants say that the major slide occurred in a shallow valley where there would have been a concentration of surface and sub-surface water flow - and where a zone of weaker peat would have been within the centre of the natural drainage line.

They make 17 recommendations for "safe completion" of construction, including one that no heavy loads, such as excavated soil from turbine foundations, be placed on marginally stable ground.

Concentrated water flow on to the pleat slopes, and unstable excavations, should also be avoided, the report says.

It also urges regular monitoring of work and the "full-time" presence on site of suitably qualified and experienced geotechnical personnel.

Hibernian Wind Energy says that it has no such full-time geotechnical expertise on site during the work, and this is one of the "lessons" it intends to take on board.

Mr Ryan said the report had been given to Galway County Council, which would also be issuing its own consultancy study.

He hoped that work would resume in four to six weeks' time, and that the project would be completed next year, rather than the end of this year as planned.

Mr Ryan said it was impossible to put a figure on the cost of implementing the recommendations, but it would add some "millions" to the original estimate of €60 million.

Some €20 million has already been committed by Hibernian Wind Power to the project, and it intends to reimburse Galway County Council for the cost of remedial works, estimated to be at least €1 million.

The company says it is in negotiations with Shannon Regional Fisheries Board on rehabilitation of the Lough Cutra system after the fish kill in the area, but claims that the extent of that kill after the landslide is not as great as had been originally estimated.

Lorna Siggins

Lorna Siggins

Lorna Siggins is the former western and marine correspondent of The Irish Times