Research by the Human Environment and Transport Inspectorate (ILT) shows that the risks of preventing environmental damage from the large-scale application of LD steel slag are insufficiently controlled. At 9 out of 10 investigated locations where these steel slags have been applied, environmental damage has occurred despite the applications meeting the applicable laws and regulations. The inspectorate concludes that the regulations for the application of LD steel slag fall short and provide insufficient protection for people and the environment.
This is the second time that the ILT has raised the alarm. In 2023, the inspectorate already signaled this. This conclusion was based on research by the RIVM commissioned by the ILT.
Steel Slag
Steel slag is a byproduct that occurs during steel production. The ILT specifically focused its research on Linz-Donawitz slag, also known as LD steel slag. This is a type of steel slag often used in the Netherlands as a replacement for sand in land-based infrastructure projects. These steel slags can be marketed as certified building materials and can be beneficially applied in infrastructure projects on land. The use of steel slag in water has not been investigated by the ILT.
10 Locations Inspected
The ILT has investigated 10 locations to get a clearer picture of how LD steel slag is used and traded in practice. It turns out that the large-scale application of LD steel slag in land-based infrastructure projects has led to environmental damage.
At 9 out of 10 locations, environmental damage occurred due to water with an elevated pH level being released. When steel slag comes into contact with soil or rainwater, the water acquires a low acidity with an elevated pH level, similar to a drain cleaner. As a result of this acidity, heavy metals are released from the LD steel slag, which can be harmful to the environment. At 1 location, no problem was identified. During the work, the steel slag there was covered due to rainfall. It is likely that no rainwater reached the steel slag thanks to the covering. Current legislation does not include any standards for acidity. There are also no legal obligations to apply LD steel slag in an isolated and controlled manner.
Needle in a Haystack
The ILT is conducting additional research into other locations where LD steel slag has been applied. There are suspicions that this steel slag has been applied on an even larger scale at more locations in the Netherlands and may have caused or will cause harmful effects.
Identifying locations is much like searching for a needle in a haystack. There is little information available because companies are not required to notify the government of the use of LD steel slag prior to application. This makes it difficult to conduct preventive checks and enforcement. In the best case, supervisors can only retroactively determine that something has gone wrong.