Airport in Örnsköldsvik, Sweden

Description

Adjacent to the airport is an active fire-fighting training area where aqueous film-forming foam (AFFF)-impacted soils can be found due to historical use of PFAS, which has now ceased. Near surface groundwater flows with PFAS concentrations on the scale of up to 200 000 ng/l have been measured, and PFAS has been shown to impact groundwater, surface water and biota (fish and otters in downstream surface water).  The recipient of the outflowing AFFF-impacted groundwater is a Norrlandsmyr, a groundwater-dependent terrestrial ecosystem which shows characteristics of both a wetland and peat bog. This type of ecosystem is fairly distinctive to the northern Nordic countries, and both hosts a rich biodiversity and a plethora of socio-cultural activities such as hiking, foraging, and hunting. In addition to being a carbon sink, a peat bog may risk becoming a secondary source for PFAS due to higher sorption in the carbon-rich organic sediments, where temporarily sorbed PFAS are spread and subsequently re-released over time into surface water. 

The Swedish Geotechnical Institute, together with the Geological Survey of Sweden, has an ongoing pilot-scale test of an activated carbon barrier as a remediation technology to limit the spread of PFAS from the site as part of a governmental assignment relating to PFAS remediation. Very detailed hydrogeological and PFAS sampling datasets exist and are being expanded, in addition to investigations aimed at improving knowledge relating to the fate and transport of PFAS from AFFF-impacted sites. Currently, groundwater monitoring of PFAS concentrations (as well as PFAS-forming precursors) is being carried out to monitor the efficacy of the remediation method. As part of the site investigation phase, detailed geological data (single-hole interpretations, geophysics, depth soundings), and hydrogeological data (for example monthly depth sounding, selected pressure transducer time series, single- and multi-hole tracer tests, passive and active flow measurement, high-resolution vertical and single-hole permeability measurements) has been collected. Soil and water sampling of PFAS, as well as carbon and other ions, has been carried out in the saturated zone via monitoring wells and depth-specific sampling as well as in the vadose zone via soil coring and sampling with suction lysimeters. Ongoing collaboration with Uppsala University involving the development and testing of models capable of numerically describing the fate and transport of PFAS is being carried out.