Germany – Construction work for communication lines – Horizontal Directional Drilling (HDD-Verfahren) - LanWin3

The transmission system operators 50Hertz Transmission GmbH and TenneT TSO GmbH concluded a cooperation agreement in December 2023 with the intention of implementing their construction projects, which are located in close proximity to each other, within a partnership. This framework also includes the civil engineering services for the "LanWin3" project. Both partners aim to jointly plan, realise and commission future-oriented and innovative DC multiterminal (hub) systems in Germany. As part of the cooperation agreement, it was decided that TenneT will carry out the civil engineering work for LanWin3 on behalf of 50Hertz and hand over the key-ready empty conduit or cable protection conduit system to 50Hertz, enabling it to pull the cable into the empty conduit or cable protection conduit system. 50Hertz and TenneT share the common goal of implementing all necessary measures within the given legal, financial and qualitative framework conditions as well as in accordance with recognised rules of planning, permitting, procurement and construction. Subject of the tender The LanWin3 project comprises the construction of a cable route of approximately 16 km in length between the landfall point in Büsum and the land station Heide in Schleswig-Holstein. The route runs parallel to the offshore connection project LanWin2. As part of the implementation of the LanWin3 grid connection system in Schleswig-Holstein, the flood protection system and particularly protected areas (seagrass meadows) at Büsum Stinteck (Schleswig-Holstein) must be crossed. The present specification applies to the creation of the LanWin3 cable protection conduit structures and the associated works and services required. A single contract will be concluded between TenneT Offshore GmbH and the bidder. The LanWin3 system will be realised as a direct current cable with a voltage level of 525 kV. In addition to the two conductors, the additional laying of a so-called metallic return conductor is necessary. For the 3 cables, 3 independent horizontal directional drills must be carried out. The occupation of the cable protection conduits pulled into the drill channels made of PE-RT will be carried out in each case with one conductor. In one of the three cable protection conduits, an optical fibre cable will additionally be pulled in. Since, among other things, the open construction method is not an option with regard to the stability of the dikes, the crossing is planned on the planning side by means of horizontal directional drilling (short: HDD method). To enable the feasibility of the parallel planned projects LanWin2 and LanWin3 (a total of six HDD drillings) in 2027, parts of the execution, especially the preparatory measures for the access and BE area creation, must be temporally advanced. These works are to be carried out as early as spring 2027 (February/March) to gain sufficient time for the cable protection conduit laying. Immediately afterwards, the site is to be set up and the horizontal directional drilling works are to be prepared. A construction time window is available from 15.04.2027. The latest completion date for the works is 16.07.2027[PD1]. It must be taken into account that the preparatory measures for the laying of the LanWin2 system must also take place within this time window. More details can be found in the specification.