This project marks the largest international initiative Herbosch-Kiere has undertaken to date. In collaboration with our joint venture partner, Enshore Subsea, we joined forces under the Dakar Marine Link initiative to install two subsea power cables.
Project
The project involved the installation of two subsea power cables with a voltage of 225 kV and an approximate length of 16 km, as well as six onshore power cables with a length of 1.9 km. The subsea cables ran between the western (Rive Bel Air) and eastern (Cape Des Biches) sides of the Bay of Dakar. The main responsibility of Herbosch-Kiere was the excavation of trenches in which the cables were installed. Herbosch-Kiere was also closely involved in the connection between the onshore and subsea cables, using horizontal directional drilling techniques. In addition, Herbosch-Kiere was responsible for the construction and installation of two HDPE strings, each 600 meters in length. After installation, Herbosch-Kiere was responsible for backfilling the offshore trenches by replacing seabed material and installing concrete mattresses for protection.
Project Background
The need for an improved high-voltage network in Dakar and surrounding areas was the driving force behind this project. The Senegalese and American governments joined forces through the Millennium Challenge Account (MCA) to implement various projects. With a funding of $550 million from the Millennium Challenge Corporation (MCC) in the United States, the aim of this initiative was to support the global fight against poverty. Our project, with MCA-Sénégal II as the client, fitted perfectly within this objective.
Equipment
For the execution of this project, three of Herbosch-Kiere’s largest vessels were deployed: the self-propelled multipurpose vessel Atlantis, the largest pontoon of Herbosch-Kiere named Gaverland, and the newest cable-laying vessel CMOS Installer. Atlantis was used for offshore excavation works, focusing on areas with harder soil layers. In addition, the vessel supported Enshore Subsea in trenching operations and backfilling of the trenches.
Gaverland operated closer to the shore and was used for trenching at the cable landing points near the beach. The pontoon also handled the installation of HDPE pipes in these trenches and the backfilling after cable installation.
Finally, the cable was laid at sea from the CMOS Installer.