On this page, we answer technical questions and share reports and scientific publications. You will also find links to websites where you can find the information, such as government agencies.
At the storage locations, we use three-layer co-extrusion foil. This is resistant to frost, sun and chemicals, among other things. It is often used in construction and to cover contaminated soil. At the storage locations we use the 0.20mm variant.
After a lot of research, we decided on the soil remediation process by DEME. The soil treatment facility works using a cleaning process especially for soil containing PFAS. The good solubility of PFAS is made use of in this process. The most important parts in this process are the separation of the fine fraction (sludge) and the coarse fraction (sand) in combination with the cleaning of the soil.
This soil cleaning technique is already being used at several DEME soil recycling centres, under the supervision of the appropriate authorities. After cleaning the Schiphol soil, 80% reusable sand is left. The rest (20%) is contaminated sludge. That residual sludge still contains some PFAS, but a large part of the PFAS ends up in the water used to clean it.
After cleaning the soil, there is PFAS in the water. The cleaning water is not a waste fraction and is not discharged. It is always reused in a closed system and purified in the process itself.
The water passes through activated carbon filters to remove the PFAS.
The activated carbon filters are cleaned by way of a heating process. DEME does this through a partner who has the relevant expertise.
To make sure that the cleaning process works for our own soil, we have done extensive testing under the supervision of independent experts. The soil at Schiphol that needs to be cleaned contains an average of 20% clay and loam (fraction <63 μm, also known as 'sludge' or 'lutum'). The proportion of sludge is important for soil remediation. The treatment facility can even work with soils of up to 40% sludge. Laboratory tests were carried out that mimic the cleaning process. The results were positive. After that, a full-scale test cleaning was carried out with soil that we brought to Belgium by ship. This test cleaning also gave good results. At DEME's soil remediation plant in Kallo (Port of Antwerp), 1013 tonnes of our Schiphol soil was cleaned. The cleaning efficiency of PFOS was over 99%.
Every week, an inspector from Grondbalans on behalf of Schiphol checks whether all storage locations are in good condition. We share these reports with the Environment Agency.
Foil damage repaired During our inspections in late August, we noted that there was (minor) damage in several places to the foil that covers PFAS-containing soil. We made a thorough inventory and then carried out repairs at all storage sites. We discovered that the damage was caused by animals, such as birds and rodents. We repaired the damage with tape and applied new material and soil cover where needed. The tape is a temporary solution. We are exploring a number of options for a permanent solution.
You can read the latest reports here (in Dutch)
The Environment Agency itself also regularly checks the storage sites.