PFAS Contamination in Swiss Railway Infrastructure: Identifying Sources, Materials, and Analysing Potential Environmental Impact

In Switzerland, PFAS leakage from a deposit of tunnel construction material into groundwater was observed. Elevated concentrations were detected in sprayed concrete on the deposit and within the tunnel. To identify possible PFAS leakage from other Swiss railway infrastructures, a geodata analysis is performed. Tunnels, bridges and retaining structures are preselected and prioritized for further investigations. Nine objects or high priority, and 179 objects of medium priority are identified. 51 protected groundwater bodies are crossed by these objects. To minimize future PFAS introduction on SBB railway infrastructure, materials that could possibly contain PFAS are identified in the literature and during workshops with experts. Materials used on construction sites or for railway maintenance are gathered. Thirteen railway specific types of assets or products were identified. These require further investigation on actual PFAs contents. From exchanges with experts, pathways for PFAS contamination of sprayed concrete are outlined and discussed. Measured PFAS amounts in solid and aqueous matrices are compared with relevant regulatory limit values. Minimum required mixing ratios are calculated. PFAS patterns at different sites are detected and possible sources discussed. On single sites, PFAS precursors attributed to fire fighting activities were detected. At most sites, solid and liquid matrices of the same site do not show the same overall compound composition, while single PFAs can be found in both matrices.