Prevention of hydrogeological instability

Wind farms are generally located in sparsely populated areas, on the tops of mountain slopes which are always difficult to access and where the limited frequency of road maintenance and containment works can cause poor soil stability.

The inevitable consequence is, unfortunately, hydrogeological instability, meaning events such as landslides, erosion, floods that generally occur very quickly but very intensely and that therefore are highly destructive for the affected area's morphology.

These phenomena are the main cause of deterioration of the infrastructures of wind farms (access roads to turbines, assembly pitches), as well as one of the possible causes of faults of the electrical infrastructure (failures of underground cables, breakage of electrical joints, etc.). Every year, ERG Renew produces an ordinary and extraordinary maintenance plan of civil engineering works in accordance with the safety policy on the management of the sites. This involves constantly seeking an overall environmental balance between the area's features – closely dependent on the geology and geomorphology of the soils and slopes – and the plant's supporting infrastructure (975 wind turbines and related clearings, 800 km of roads and underground cables in Italy).

The ordinary and extraordinary maintenance plan is divided into the following phases:

specific inspections on-site every six months to check for any abnormal deterioration of the wind farm infrastructure particularly of the structure (foundations), of the technical networks (collectors, pipes, fittings, water collection sumps, stone perforated drain pipes, drains), of other infrastructure (gutters, ditches, paving of roads and pitches), of existing containment works (reinforced soil, gabions, wooden piling) and of those related to electrical civil engineering (underground cables and fibre optic conduits);
• and preparation of inspection and photographic reports;
• detailed design of maintenance required;
• setup of the construction site;
• implementation of the measures;
• conclusion of the works.

In designing important structural consolidation works, ERG Renew supports the adoption of environmental recovery techniques using the methods typically taken by the bioengineering. They are low environmental impact techniques where the use of cement is limited to a minimum, while the main consolidating components are live plants or parts thereof (seeds, roots, etc.), the wood, the stones and the soil itself affected by landslides and subsidence, sometimes combined with artifi cial biodegradable materials such as bio matting, galvanized netting, geogrids, geonets, and geotextiles.

There are two main advantages: the natural environment is not affected and naturalization and integration with the different infrastructures is simultaneously promoted.

In 2015, to prevent the instability generated by the exceptional weather and to ensure the structural consolidation of assets as a result of landslides and subsidence, we designed and executed five major unplanned maintenance interventions. In addition there were over 30 different routine maintenance interventions of the civil works, which restored, when necessary, the functionality of the road infrastructures of the wind farms and of the related works by consolidating and restoring the road structure.