FACTS
Investor: PSE SA
Location: northern part of the West Pomeranian Voivodship
Investment cost: PLN 65.7 million
Completion: design 2017, construction 2018
LINE DETAILS
- new single-circuit power line Glinki - Recław 220 kV
- line length 33.6 km, including 8.1 km on forest areas
- new tower types: GRL52 M3 and GRL52 P
- customized technical solutions for towers and foundations of 220 kV line
CHALLENGE
In order to increase the security of power supply to the northern part of the West Pomeranian Voivodship and the Szczecin agglomeration, PSE SA proceeded with the construction of the Glinki - Recław 220 kV power line, which required the construction of a new single-circuit 220 kV line with a length of 33.6 km and the modernisation of the existing 220 kV line at a length of 15.2 km.
The 220 kV power line runs partly through State Forest areas belonging to the Goleniów and Rokita Forest Districts. Due to the conditions imposed by local spatial development plans as well as the provisions of the decision on environmental conditions, only a 15 m wide strip of trees could be felled in forest areas. In addition, the height of the towers was limited to 50 m, which in combination with the target tree height of approx. 30 m meant that it was not possible to use over-forest poles.
The general contractor for the works - Aldesa Nowa Energia Sp. z o.o. - asked Eltel Networks Engineering to present a concept for running a 220 kV power line through forest areas while meeting all environmental and technical requirements for this project. In addition to the restrictions already mentioned, such as the maximum width of the felling strip of 15 m and the maximum tower height of 50 m, it was necessary to ensure a tree-free area of 4 m around the towers and to meet the required electrical distances from falling trees.
As part of the concept, completely new 220 kV GRL52 series towers were proposed by Eltel Networks Engineering, which met the requirements of the environmental conditions. The towers were designed for use with AFL-8 525 mm2 phase conductor and AFL-1.7 95 mm2 lightning conductors and OPGW.
Another challenge faced by the designers was the difficult ground conditions which necessitated the use of pile foundations. Driven pile technology was used for the construction of the foundation, which significantly shortened the execution time compared to drilled pile technology. In addition, the top of the cap slab was elevated above ground level due to the high water table - this elevation of the foundation necessitated a reduction in the size of the foundation so that 4 m of free space remained between the cap slab wall and the cutting edge.
EFFECT
The construction of the single-circuit 220 kV Glinki - Recław overhead line in sections located in forest areas was a challenge both in terms of design and execution.
The small amount of available land on which it was possible to locate the power line, as well as stringent environmental requirements and difficult terrain conditions in the case of the forest sections of the 220kV Glinki - Recław overhead line, forced the use of customized solutions and "tailor-made" design in the projects.
