For ALDI-Suisse's Distribution Center for Central Switzerland, soil improvement measures on a surface area of 160,000 m2 were required. First, vertical drains were sunk in the deep marine clay. A total of 225 km of drains were created. In a second step, the overburden, comprising silt, sand and gravel, was improved via vibro-displacement compaction. In order to establish the depths of vibro-displacement compaction required, all individual foundations were pre-probed using the heavy dynamic penetrometer. After vibro-displacement compaction, the foundations had to be re-probed for quality assurance. Due to the very tight deadline, over 10 large drilling rigs were deployed on the construction site.