A good soil survey lets you look under the hood of your future construction project. Of course, you want to be sure that the soil you want to reuse is also safe for people and the environment. Terrascan investigates and supervises the remediation of (PFAS-containing) soil at Schiphol. We spoke to senior project leader Michel van der Riet about his passion for thorough research.
In the news we are reading more and more about PFAS in the soil in several places in the Netherlands. Where does that PFAS come from? It could be anything. Take atmospheric deposition for example. This is when rain, snow, fog or gases move from the atmosphere to the Earth's surface, contaminating the ground. Another example is leakage of contaminated water. Sometimes a change in the law means that less PFAS is allowed in the ground than before. And then you have to examine the soil again and again. Ten years ago, research into PFAS was rare, but in the last five years it has become standard.
Terrascan is 100% focused on Schiphol projects. What explains that dedication? Interest. I started as a junior project leader at Terrascan in 2004. As a rookie you go on a voyage of discovery. Over the years, you notice what you find interesting. Which people you like working with and which projects you enjoy. I’ve already carried out enough soil quality tests for private individuals wanting to build a new extension. Been there, done that. Now I prefer to be a point of contact, budget manager and supervisor for Schiphol projects. What appeals to me about it is the complexity. Whether a taxiway is being moved or runway maintenance is being done, there is always a lot of research and data analysis involved. Wonderful.
If Terrascan is asked to test the soil quality, how do you proceed? With PFAS you want to identify the risks for people and the environment. Good preliminary research enables you to obtain the most representative ground and groundwater samples possible with as little drilling as possible. You can then send those samples to the lab for testing. When you think of a lab like this, you really have to picture people in long white coats, in spotless rooms. This lab sends the results to us, which we then interpret and present in a report to Schiphol.
And what does a preliminary investigation involve? We delve into the archives. We look at old environmental permits, business activities, soil surveys —whether remediations have been carried out before. Aerial photographs reveal a lot about whether there were old buildings or whether ditches were filled in. Some historical knowledge also helps. For example, during the Second World War, a ditch was dug around Schiphol to stop tanks. Farmers later filled that ditch with old waste. We have found German coffee cups and helmets in such places. This is interesting from a historical perspective, but also tells us how soil is composed. And how we can now effectively drill at strategic locations to obtain representative research results.
How does Terrascan ensure that your advice is followed? We also supervise the soil remediation. We conduct research, provide advice and once the soil has been remediated, we take control samples during and immediately afterwards to see if it’s all going well and if it has been sufficiently remediated. Over the past five years, we have also been conducting more and more research into PFAS outside Schiphol.
How do you determine whether a sample is representative? We adhere to the national NEN standards that apply to soil research. This states the minimum amount of drillings you must do per m2 when it concerns a 'suspicious' location. When Schiphol asks us to conduct soil research, we usually do more drilling and laboratory analyses of soil than is necessary according to national standards. This is due to the high standards we impose on ourselves and in order to obtain the most representative possible picture of soil quality. After all, measuring more means knowing more. This way we can work even more accurately and effectively.
Terrascan has been working for Schiphol for 25 years, can you still call it an independent research agency? With us, every assignment starts from scratch. It does not matter whether we are dealing with a private individual or a larger party such as Schiphol. Once, a farmer said to me: 'I would rather you didn’t measure in that area, because something happened there once.' In such a case we terminate the assignment. This is no different at Schiphol. Our degree of independence is also monitored. We comply with all kinds of certifications such as ISO 9001, VCA and SIKB. We also receive the corresponding audits. And that's a good thing. If you cannot comply, your entire right to exist will also disappear.
How do you deal with feedback on the research results? We are always open to feedback. However, you obviously cannot change research results, we can only dispute certain wording. Schiphol sometimes asks us to provide additional arguments as to why we drill here and not there. This saves extra explanation at a later date. We think it is especially important that we can always stand behind our advice.
Are you concerned about PFAS in the Netherlands and Europe? I'm not worried. I do hope that there will be more clarity in the short term about how harmful it really is. I think that will ensure peace and lead to clear regulations. You notice in the news that PFAS is almost becoming a hype. As if it's suddenly everywhere now. It's been there for decades. I don't want to downplay it, absolutely not, but we have to remain realistic. Does it pose a danger? If so, how big? The regulations are still in their infancy. It is of course strange that the limit values and rules differ per municipality. That must be national. This requires more research and better solutions. I do know for the near future: we have plenty to do.