For more in depth discussion on this issue
Please contact Herdis Heinemann
What are the main causes of the increasing foundation problems?
Climate change, policy decisions and land subsidence. Global warming is causing rising sea levels and precipitation extremes, so more frequent torrential showers, where huge amounts of rain fall in a short period of time, due to which rivers overflow their banks more frequently, as well as periods of prolonged drought.
The management of groundwater levels also plays an important role. Sometimes the government deliberately chooses to lower or raise the groundwater level in a certain area. And then there is the problem of subsidence in various parts of the Netherlands.
What are the consequences?
Many old buildings in the Netherlands are supported by wooden piles, as is much of our infrastructure. As groundwater levels increasingly start to fluctuate, those piles can start to rot. This means that we are on the eve of a period in which we will be confronted with serious foundation problems. But those wooden piles are only part of the problem.
Because up to the 1970s, in addition to building wooden pile foundations, construction companies built shallow foundations on sand layers just below ground level, which in Dutch are also known as ‘op staal’ foundations. And these shallow foundations, too, appear to be sensitive to subsidence and erratic groundwater levels.
And what problems does that create?
That varies enormously. Some buildings suffer such severe subsidence or damage to their foundations that they start to visibly lean to one side and truly dangerous structural issues develop. In other buildings, the problem is limited to small cracks in the walls, but these must nevertheless be inspected to determine whether they are the first signs of more serious foundation problems.
Where do foundation problems occur?
So far, the really serious foundation problems with wooden piles have largely been limited to several cities in the Randstad conurbation, such as Rotterdam, Dordrecht and Gouda. These cities already have a lot of expertise in mapping and repairing foundation damage.
Now that the rest of the Netherlands will also increasingly face foundation problems, it is important to share the knowledge that is already available. And that goes even more for sharing knowledge about problems with the shallow op staal foundations, because we currently have little experience in this area.
Why do we need to act on foundation problems now?
Processes in the subsurface are often complex, which makes it difficult to accurately predict in which locations foundation problems may develop. At the same time, it is a problem that many Dutch people will be confronted with eventually.
In addition, the foundation problems will cause a lot of damage financially. Experts estimate the total cost of the foundation damage will add up to 20 to 30 billion euros by 2050. This estimate assumes that the Netherlands will take extensive measures to prevent foundation damage as much as possible. If these measures are not taken, the total cost of the damage could run up to a much higher figure.
How can TNO help with this issue?
At TNO, we develop and share knowledge to get a clear picture of the foundation problems. For example, we recently wrote a report on this subject together with Deltares. The three main recommendations are:
- Take steps to gain a better understanding of the nature, size and distribution of the foundation problems, as well as a better understanding of how exactly the damage arises.
- Look for new techniques and guidelines with respect to collecting and extracting data and information on foundation problems.
- Develop new concepts that can prevent foundation problems or make it possible to repair damage to foundations in a fast and effective way.
What role does the Dutch government play?
The report was commissioned as part of the government programme aimed at tackling the foundation problems. This programme is managed by the Netherlands Enterprise Agency (Rijksdienst voor Ondernemend Nederland, RVO).
Together with its partners, the RVO works to improve knowledge about the foundation problems in the Netherlands and to find appropriate solutions. There is still a lot to do in this area and time is running short. For this reason, TNO is now devoting much more attention to this topic than before.
Want to know more?
Interested in learning more about the foundation problems in the Netherlands? Download the report by TNO and Deltares