Frankfurt Airport has been steadily growing alongside the Rhine-Main region for more than 75 years. 2005 saw the military use of the Rhein-Main Air Base in the southern part of the airport decommissioned before responsibility was transferred to the airport operator, Fraport AG. The old installations needed to yield to the new Terminal 3 and extensions to the airport infrastructure in this area. As part of the demolition process, CDM Smith was commissioned with contamination studies on a total of 175 buildings as well as various sealed surfaces and underground pipes. We carried out environmental, waste and geotechnical studies on soil and groundwater, which included 33 core holes drilled down to a depth of 40 m.
For the new Terminal 3, a shallow foundation will be implemented according to our recommendations. For the longitudinal approach table, a pile foundation will be implemented according to the results of horizontal pile test loads and extensive 3-dimensional deformation calculations. The excavation pit for the terminal will be constructed in two phases. First, the excavators worked their way down to the groundwater zone at a depth of 5.5 m in dry excavation over an area of 65,000 m². The final excavation depth in the groundwater zone will be reached under the protection of sheet pile shoring.
During the extensive sampling of the excavated soil, residues of the substance group of per- and polyfluorinated chemicals (PFC) or per- and polyfluorinated alkyl compounds - PFAS for short - were detected. Fraport commissioned CDM Smith to develop a soil management concept for Terminal 3, the aim of which is to recycle a large part of the contaminated soil material in accordance with the requirements of the remediation notice issued by the Regional Council or to dispose of excess excavated soil: CDM Smith controls and monitors this soil management. CDM Smith has planned an appropriate soil storage facility for the temporary storage of the excavated soil.
Our soil management strategy takes into account environmental and economic constraints by optimising recycling and disposal routes.
Following the site investigation, the soil material was analysed and residues of Per- and Polyfluoroalkyl Substances (PFAS) were detected. Fraport then commissioned CDM Smith to develop a soil management strategy for Terminal 3. The objective of this was to ensure that as much as possible of the contaminated soil material would be recycled, in accordance with regional guidelines. Furthermore, any material to be taken off site would be dealt with in an environmentally safe manner. As an interim measure, the excavated soil is being temporarily stored safely at a storage facility on site. CDM Smith is providing planning and monitoring services associated with this work. We are also responsible for construction supervision to ensures that the soil separation is undertaken in an environmentally safe manner, in addition to developing occupational safety instructions for handling the contaminated soil material.
At present, there are no national regulations for the handling of soil contaminated with PFAs and there are relatively few precedents for soil recycling. Our experts are also supporting Fraport in negotiations regarding this complex issue with the relevant authorities.