Geotechnical investigation of the condition under the ground

Amsterdam's quay walls are a feast for the eyes. They house a piece of history, bring atmosphere and provide wonderful spots along the water. But if we want to preserve these quay walls, they must be repaired or replaced now. 

The repair of Amsterdam's quay walls has been an issue for many years. Many quay walls require major maintenance. Over a stretch of about 10 kilometers, the situation is even worrisome. For a structured approach, the City of Amsterdam has now established a project office, which inspects the bridges and quay walls in outline and then concludes (framework) agreements with engineering firms and contractors for surveys and renovation. One of the agreements is with Geonius, which is conducting the geotechnical investigations for the quay walls at 27 locations.

A sizeable challenge

The study is comprehensive and requires intensive preparation. "The picture we have of the quays is sketchy," says Mark Rurup, director of Geonius Group. "They are partly made of wood and partly of masonry; we don't really have a good picture of the part below ground. In addition, the quays are narrow and filled with cables and pipes. An additional challenge: during the surveys, city life must continue to flow without much disruption."

The role of Geonius

"We determine for each site what the best approach is," adds Jos Verbeek, manager of Geotechnical Engineering. "What equipment can we deploy and what safety measures are needed? Through probing, drilling and laboratory tests, we gain insight into the soil structure under the existing quay walls. We do this in the downtown and New West districts. We carry out the probing and drilling partly on the quay, partly from a pontoon on the water. Of course, we do everything possible to spare shipping in the process."

Ready for the job

For Geonius, the major order comes at a sophisticated time. "With the acquisition of Hoogveld Geo last summer, we now have more than ten CPT units and our own pontoon," Verbeek says. "The newest acquisition is the boxed crawler, a probing unit with minimal dimensions. It comes in handy in Amsterdam's narrow streets. The unit has plastic tracks so it does not cause any damage and can do its work at a width of two meters."

Geonius began preparatory work in mid-July; since October it has been conducting the surveys. It's maneuvering, that's already clear. "Some places are already difficult to reach by car, let alone with a sounding unit," says Geonius.