Finland – Engineering works and construction works – SR-VP 400kV kalliotunnelin louhinta- ja rakennusurakka, Helen Sähköverkko Oy

The subject of the procurement is the rock tunnel cable route for Helen Sähköverkko Oy (the Contracting Authority) from Sörnäinen to Vanhakaupunki. The rock tunnel is intended to accommodate a 400 kV cable connection. The 400 kV cable connection will be constructed as a separate contract after the excavation and construction contract for this rock tunnel. The planned length of the rock tunnel is approximately 4.2 km. The cross-sectional area of the rock tunnel is approximately 25 m2 and it mainly runs at a depth of 20…-53 meters below sea level. There are other underground spaces in the vicinity of the rock tunnel, including tunnels belonging to HSY (Helsingin seudun ympäristöpalvelut -kuntayhtymä). Vertical shafts will be constructed at the northern and southern ends of the rock tunnel, through which the cable connection will rise to the surface. In Vanhakaupunki, the vertical shaft will be located in an area with exposed rock. At the Sörnäinen end, the vertical shaft will be located in the Hanasaaren energy district. The overburden in this area consists of approximately 20 meters of fill from the 50s, according to preliminary information. There are also contaminated soils (PIMA) in the Hanasaaren energy district. The excavation of the rock tunnel will take place through two existing access tunnels. The rock tunnel is provisionally planned to have 5 pump houses, some of which may be implemented using borehole technology that can be serviced from the surface. The aim is to make the rock tunnel as maintenance-free as possible, and in the final situation, only essential building services will be installed. This procurement includes, among other things: - Construction of the Sörnäinen vertical shaft to the surface according to the plans, including excavation, temporary and final lining structures in the overburden section, as well as final shaft structures - Construction of the Vanhakaupunki vertical shaft according to the plans, including excavation, temporary and final lining structures in the overburden section, as well as final shaft structures and surface shaft building without building services - Modifications to the existing access tunnels and their associated shaft structures to the extent required by the plans, as well as any modifications required by the contractor - Excavation, reinforcement, and injection work, as well as shotcreting in the rock tunnel - Structures and equipment for the rock tunnel pump houses, as well as boreholes required for borehole technology with their surface structures - Other structures and equipment for the rock tunnel to the extent specified in the plans - Final structure backfill system - Drainage systems and base structures for the rock tunnel - Essential building services installations for the rock tunnel to the extent specified in the plans - 400 kV cable fixing system to the extent specified in the plans, including anchorages and rock anchors - Temporary electrical systems, lighting, ventilation, and pumping systems (these will remain with the Contracting Authority for later phases) The acquisition, planning, and equipping of the required work areas are the responsibility of the contractor. The selected contractor will act as the main designer and main contractor for the rock tunnel excavation and construction contract. The preliminary schedule for the implementation of the contract is 2027-2029. The documents related to the procurement and their content will be supplemented during the procurement process, and the final procurement target and requirements will be presented in the final tender invitation.