Airport in Örnsköldsvik, Sweden
Location
Örnsköldsvik Airport is located approximately 450 km north of Stockholm, Sweden and is characterized by thin glacial and postglacial sediments overlying hard rock. The airport itself is situated on thicker glaciofluvial sands and gravels, of the type typically used for municipal drinking water sources in Sweden.
Description
Adjacent to the airport is an active fire-fighting training area where 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). Preliminary results show that retention within the unsaturated zone is vital for understanding its role and longevity as a primary source of contamination.
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.
Specific features
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.
Relevant Users/Stakeholders
Municipal Water suppliers, Water-users, private forestry, outdoor enthusiasts such as foragers, hunters, fishers, bird-watchers, hikers, etc.
Used tools
MODLFOW, MT3D, Analytical methods, HYDRUS
Lead
Swedish Geotechnical Institute
Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them.