Highly variable ground conditions required pile foundations

enercity Erneuerbar GmbH is one of the leading players in the German onshore wind market. The Leer-based company is consistently expanding its wind energy business, particularly in the windy north. A current example is the Bosau wind farm planned in the district of Hutzfeld. There, enercity Erneuerbare GmbH is constructing two modern GE 158 wind turbines, each with a capacity of 5.5 megawatts.

Due to the highly variable building ground, the building ground survey recommended deep foundations on piles. enercity Erneuerbare opted for the flexible and resource-saving Franki in-situ concrete rammed piles. This allows the production of the Franki piles to be adapted to the respective soil conditions by specifically limiting the pile setting depth through pre-compaction of gravel.

Resource-efficient and stable: the Franki pile NG®

In total, the Oldenburg special civil engineering team installed 68 Franki piles NG® with a diameter of 510 millimeters and a pile length of 17.50 meters. These piles are part of PORR Spezialtiefbau's Greenpile® system and offer significant environmental benefits. First and foremost is the improved CO₂ balance: full soil displacement means that no drill cuttings are produced, completely eliminating the need for additional transport for their disposal. Together with the lower concrete consumption due to the slim pile diameters, this significantly reduces the ecological footprint of the entire construction project. The ramming also compacts the surrounding soil, which further increases the load-bearing capacity of the piles.

Sustainability confirmed by DGNB

Another milestone in terms of environmental responsibility: the PORR Spezialtiefbau construction site at the Bosau wind farm has been awarded the DGNB “Sustainable Construction Site” certification. This officially confirms the commitment of all those involved to resource-saving, low-emission, and socially responsible construction. The certification underscores the high standards of sustainability that were pursued in both the planning and implementation of the project.