Development of Viermyr and Austøla power plants are tentatively calculated to be able to provide a maximum annual production of approx. 36 GWh, at a construction cost of approx. NOK 3.6/kWh.
Construction period is approximately two years.
The project has several positive effects on the environment such as a greater and more even winter water transfer, something which will also be an important contribution to maintaining vital stocks of salmon and sea trout in Austdøla.
The development plans proposed in the notification border the Lang-Sima development and are based on using the residual water flow further down to Austdalen for new power production. It has been proposed that a reservoir be established in Austdølvatnet (contour line 907). The head from here down to contour line 180 in Austdøla is intended to be used in two steps by constructing the Viermyr and Austdøla power plants. Three alternative station locations have been established for Austdøla power plant.
Assuming a reservoir is established in Austdølvatnet of approx. 1.6 Mm³, this will ensure a larger and even winter water flow in Austdøla downstream of the power supply emissions. The increase may be more than double the current low water transfer on the driest winter days, and for roe and spawn of anadromous fish in Austdøla, this is thought to be an important contribution to maintaining vital stocks of salmon and sea trout in Austdøla.
Viermyr power plant
The waterway for the power plant will be created using a drilled shaft from Austdølvatnet with a transition to GUP pipes in an approx. 200 m long horizontal tunnel up to the power station. The actual power station is located in the open by the tunnel door. A new permanent road approx. 150 m long and a new underground cable or overhead line of about the same length must be built up to the station.
Austdøla power plant
The intake to Austdøla power plant will be downstream of Viermyr power plant, below the confluence with the river from Grasbotn. Specifically about contour line 740 just below the old rigging area from the Eidfjord development. The top 100 metres of the waterway is planned as a drilled shaft through the first mountain ridge and down to the water. From here there will be a transition to a buried pipe that closely follows the current road. Except for a shorter section with particularly steep terrain between contour line 520 and contour line 430 where the pipe is laid in the open, the pipe will then travel downwards towards the two lower alternatives laid in the trench. All three power station alternatives will be relatively similar in execution but will result in varying performance of 5.0, 8.5 or 9.2 MW respectively.
A new permanent road as well as underground cable or overhead line of between 100 and 400 metres must be built for all alternatives.