Ground Improvement of the Tank Terminal in Amsterdam, the Netherlands

In the western part of the Port of Amsterdam, a new storage terminal for oil products is being built. The site investigation revealed that underneath a single tank, the thickness of the compressible layers could differ in up to 3 meters. It was concluded by the client that ground improvement was required to avoid excessive differential settlements of the storage tanks and associated maintenance costs. The initial ground improvement design proposed by the client consisted of the application of dynamic replacement (DR). A trial showed that the traditional DR method as well as the CDC technique (Cofra Dynamic Compaction®) did not achieve sufficient improvement. Therefore, a full ground improvement was made, with large excavations of up to a depth of 8 meters below the surface, removing more than 1,000,000 m3 of material. The excavations were backfilled with sand. This very loose sand was compacted in one phase using the CDC technique. This paper presents an overview of the initial trial results and the final work method with a focus on the method of compaction and the compaction results