Switzerland – Construction work – UW Riet - Baumeister (AIS)

The substation (UW) Riet was commissioned in the early 1970s. The outdoor switchgear is in need of renovation. Spare parts for the hydraulically driven disconnectors and switches are only a few available. The secondary equipment and auxiliary systems of UW Riet have been renewed in the meantime, but have already reached the end of their technical service life and must be renewed. There is also a high degree of interconnection with the systems of the former operator Axpo in this area. Axpo has terminated the 220/50-kV network connection "Transformer 21" as of 31.05.2022 and will dismantle the 50-kV outdoor switchgear as far as possible and necessary. Despite this termination, UW Riet remains a connection point of the Axpo distribution network in the Winterthur region. It also connects the Swissgrid network node Breite with UW Schlattingen. To maintain the safe operation of the plant, various systems must be renewed. The auxiliary systems should also be supplemented with an emergency diesel generator that ensures an autonomy time of 72 hours. This emergency diesel generator will be operated by Axpo. Swissgrid is therefore replacing the primary and secondary equipment and building its own substation building (UWG) to achieve the greatest possible decoupling from the Axpo systems. The following requirements must be strictly observed during the construction work: · Work within an operating substation (up to 220 kV), · Work near railway tracks. The present tender includes the work related to the dismantling and new construction of the outdoor switchgear and its cable duct blocks and shafts. The already executed substation building is not part of this tender. The following work is to be carried out in general: · Preparatory work (site establishment, provisional measures, dismantling, demolition, disposal, etc.) · Landscape design (earthworks, etc.) · Rough and finish work (civil engineering work (foundations, drainage, extension and adaptation of rail track), edge closures, surfacing, etc.) · Electrical systems (system lighting, earthing, etc.) · Access through lines (cable duct blocks and shafts, etc.) · Acceptance (FAT, SAT and IBN). The detailed scope of services is listed in document C100.