Where: Trysil and Åmot municipalities

Challenge

Raskiftet Wind Farm is located in a landscape with extensive peatland areas, and in a development of this kind, roads inevitably have to cross peatlands. Where they cross and how they are built determine how much of the peatland continues to function as such afterwards. A road routed incorrectly through the terrain will cut across the deepest sections and cause more disturbance than necessary. An impermeable roadbed or open roadside ditches may affect the groundwater level and alter the composition of the peatland vegetation.

Peatlands are a natural store of organic matter. As long as the groundwater level in the peatland remains high, the organic matter is preserved and greenhouse gases remain locked away. If the groundwater level drops, the organic matter in the peat soil will decompose, releasing greenhouse gases.

The peatland is also a habitat: deep wheel ruts and steep ditch edges become barriers for woodland grouse chicks foraging in early summer. The challenge, therefore, was not simply to cross the peatland with a construction road, but to do so without altering its function as a habitat for animals and plants, while also preserving its function as a carbon store.

Measures

To preserve the peatland’s function, the measures were planned before construction began and monitored throughout the construction process.

These are the measures we have taken:

• Route selection: The road routes have been planned to minimize the impact on the woodland edge between the bog and the forest.
  
• Field survey: The crossing points were identified through on-foot surveys and probing with an iron rod, point by point, until the shallowest areas had been mapped.
  
• Perpendicular crossing: The roads cross the bog at its shallowest points, as perpendicular to the direction of the slope as possible.
  
• Coarse stone in the foundation: The road foundation is constructed using very coarse stone. Water flows freely through the foundation, maintaining the natural water balance and ensuring that the vegetation remains the same on both sides of the road.
  
• Low road embankment: The road embankment is no higher than necessary. The roadway sits low above the marsh and is as unobtrusive as possible in the landscape.
  
• No open drainage ditches: Ditches with steep sides have been avoided, both to ensure proper drainage and to protect the birds.

Results of the measures

The bog at Raskiftet continues to function as a bog. Water flows through the coarse road foundation as before, the groundwater level is maintained on both sides, and the vegetation is the same on either side of the road. The terrain is free of deep wheel ruts and steep ditch edges, allowing woodland grouse chicks to forage just as freely as they did before construction. The road surface is low, the transition zone between the bog and firm ground is barely affected, and the development is therefore barely visible in the landscape.

The high groundwater level also has implications for the climate. Peatlands are natural stores of organic matter. As long as the peatland remains waterlogged, the material does not decompose, and the carbon remains stored in the peat soil. If the groundwater level drops, decomposition begins, resulting in greenhouse gas emissions. By maintaining the natural water balance, the peatland’s function as a carbon store is also preserved.

Tore Sollibråten, Head of Environment and Licensing at Hafslund, explains why the work is worth the time:

– Peatlands are about more than just greenhouse gases!

In this video, Sollibråten talks more about the project: