CHAPTER 11: MASS MOVEMENT PROCESSES, PATTERNS AND LANDFORMS
3. The Derrybrien bog flow/bog burst, County Galway
In October 2003 a bog flow (bog burst) occurred near the village of Derrybrien, County Galway. A combination of human activity and heavy rainfall triggered the burst.
This bog flow began within the site of a large wind farm development. The development area covers most of the summit of one of the main peaks in the Slieve Aughty Mountains. The area is covered by blanket bog to a depth of between 2.5 to 5.5 m.
Fig. 22 The Derrybrien bog flow in County Galway
While digging the foundations for the wind turbines, waste peat was piled up in unstable areas of the site. Bog drainage ditches were also blocked by these waste piles, allowing water to build up and adding to the weight of the bog on the hillside.
At first a large mass of bog moved downhill for a distance of 2.5 km. Two weeks later during heavy rain, the bog then travelled more than 20 km along the Derrywee River and entered a major fishing lough, killing more than 100,000 fish. Drinking water was polluted for weeks and had to be supplied by tanker to residents in the area. Roads were severely blocked restricting travel.
Many people used the event to protest against wind farms in general, but in fact poor site management and not wind farms themselves were to blame for the bog flow.