Overhead transmission line, 420 kv Balsfjord-Skaidi
OHTS, Transmission line, NOrway project, Troms county
Statnett is building a 300 km 420 kV overhead transmission line (OHTS) from Balsfjord to Skaidi in Troms county. EFLA worked with Statnett from the preparation stage, by assisting with the choice of the line route and making geotechnical estimates for foundation design. Designing the towers and foundations, to assisting with project and site management.
About this Project
Client
Statnett
Timespan
2011-ongoing
Location
North Norway, Troms county
Contact
Steinþór Gíslason Director | Energy Phone: +354 412 6200 / +354 665 6200 E-mail: steinthor.gislason@efla.is Reykjavík
The project's objective
The line has the objective to improve the security of supply in northern Norway, promote industrial growth and increase value creation.
In an addition to be a premise for future production of renewable energy.
Cost estimate for the project is 4-4,5 billions NOK.
This line is an extension of the 420 kV Ofoten-Balsfjord line to further eliminate a bottleneck in the main grid in the North of Norway. It is necessary in connection with an expected increase in consumption and for greater industrial activity in northern Norway.
In the 300 km 420 kV OHTL from Balsfjord to Skaidi Statnett decided to use standard Statnett steel portal towers, foundations along with prefabricated steel foundation.
Due to the size of the project it was divided into 3 separate contracts with 3 different contractors
- Balsfjord-Reisadalen 2017-2019/2020
- Reisadalen-Skillemoen 2017-2020
- Skillemoen-Skaidi: in tender stage, estimated start Sept. 2019
Rerouting existing 132 kV lines due to the main project, both steel and wood pole lines. For the design of the towers and the foundations, EFLA used specialized excel macros along with PLS-Cadd/Tower.
Environmental issues
Statnett was responsible for choice of the line route, environmental consequences, building permits and the Environmental, Transport and Construction plan (MTA). Where facilities for employees and storage are listed, along with location for preassembly sites, storage for drums and stringing equipment.
Construction and access roads, access for helicopter for material and workers are also stated in the ETC. Permanent environmental impact due to construction of the line was minimalized as much as possible. Reindeer farming on the line route was respected, by having restriction periods during parts of the year.
Service Components
Challenges
One of the challenges in the project where the long transport and difficult access to the line route, where transport of people and material was mostly done by helicopters. Due to short days and limited daylight during the winter months, the need for good planning and effective construction management from the contractor was essential.
Because of this Statnett decided to design and use prefabricated steel foundation, giving the contractors the possibility to continue foundation work during heavy winter months and decrease helicopter transport by using winter roads. Read about project on Statnett's website.