To achieve the dramatic expansion, 19 of the three-storey buildings are currently being supplemented by two further floors in modular timber construction and the existing building foundations are been renovated to accommodate the extra weight.

Bauer Spezialtiefbau was commissioned in a joint venture with Implenia AG to re-compact the subsoil of the settlement. The specialist foundation engineering work includes the underpinning of 13 of the 19 building complexes by Bauer, including rear anchorages and securing the underground parking garages.

In order to stabilise the foundations, a total of about 4,250m³ underpinning is being produced using the high-pressure injection process (HDI). In this case, a drill string is introduced into the soil, after reaching the required final depth a binder suspension, which rinses a portion of the soil, exits from a nozzle at the lower end of the linkage.

"As the work has to be carried out partly in the cellars of the existing buildings, a compact Klemm KR 500 unit is used, which allows work in a small room height. In addition, there are two HDI pump containers and one mixing plant of the Bauer MAT Slurry Handling Systems of the type SCW 14/25 on site," explained Karsten Brahmann, project manager at Bauer Spezialtiefbau.

"In addition, a Klemm KR 806 will be used for the 500m of temporary anchors, and a Bauer BG 15 H will be used to build a 3,000m² pile wall with shotcrete infilling," added Michael Moser and Wolfgang Debus, both also project managers at Bauer.