All about soil –a fragile resource

The condition of the soil at Zurich Airport is relatively well known thanks to repeated studies and inspections. The reference values for pollutants in the soil are met to a large extent. However, it has long been known that the edges of the runways show increased copper and zinc values from flight operations (brake and rubber abrasion from aircraft in the past). At a few places, elevated levels of polycyclic aromatic hydrocarbons (PAH) have been found, e.g. where cleared snow is stored in winter. The pollution is moderate and comparable with busy roads or core areas of settlements in terms of magnitude.

Old landfills, industrial activities or historical accidents are reasons why various locations around the airport site are listed in the register of contaminated sites. The register is managed by FOCA (see link). Most sites have now been thoroughly inspected and cleaned up where necessary. The major project includes the cleaning up of a former contaminated tank farm in three stages from 2000 to 2005, at a cost of around CHF 7.8 million.

In contrast to contaminated sites, contaminated soils are identified as such only during the planning or implementation of a construction project. The pollutant entered the soil in the past and remained undetected to date. If Flughafen Zürich AG comes across contaminated soil during construction work, it immediately calls in external soil specialists who determine the type and extent of contamination on site using laboratory tests. In accordance with the Ordinance on the Avoidance and the Disposal of Waste (ADWO), the contaminated soil is then sent for appropriate recycling or treatment.

If unpolluted, fertile soil is removed during a construction project, there is a legal obligation to use it appropriately. As such, Flughafen Zürich AG conducts regular soil improvement projects. This means that the fertile soil from the airport is spread onto agricultural land in the vicinity to improve its suitability for farming. In this way, crop rotation areas can often be created at the same time, i.e. arable land that is protected in its function as a foundation for food and feed production.