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Mannheim, Quartier Hoch 4

Facts and Figures
Company Stump-Franki Spezialtiefbau GmbH
Principal Diringer & Scheidel, construction firm, Mannheim
Location Mannheim - Germany
Type Specialist civil engineering
Runtime 01.2018 - 12.2019

Soft gel floor slab.

In the centre of Mannheim, we implemented the sealing of a 6,000m² horizontal construction pit using soft gel injection procedures. The project incorporated several significant challenges.

Difficult conditions

The dimensions of the low-lying injection floor slab required for the horizontal construction pit to be closed against vertically climbing groundwater were formidable. Within just three months, we had to manufacture a 6,000m², 1m-high soft gel floor slab right next to the Mannheim central railway station.
This required maximum commitment: 24-hour operations during the first three months of the year, continuing through rain, frost, snow and sunshine.

Successful implementation

During the construction period, two drilling rigs worked in tandem to bore a total of 2,636 holes to depths of approx 7.5m, while 16 pumps operated simultaneously to make 7,908 injections.

Finally we were able to deploy 55,356m of injection lances to inject 1,882,104L of soft gel into the soil. Towards the end of the construction project, the thermometer was showing negative figures in the double digits, which made our work extremely difficult. Nevertheless, a pumping test finally confirmed that the contractual and technical sealing requirements of the floor slab had been met.

Technical data / quantities

Site area


Floor slab thickness


Drilling depth