Bespoke solution

20 litres 

of water treated per second

15,000 tons

of contaminated soil removed

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The challenge

Two seemingly unrelated things happened in the 1930s: Guernsey Airport celebrated its grand unveiling, and PFAS were invented. And while both were deemed a positive progression, PFAS have since proven otherwise. Poly and perfluoroalkyl substances (PFAS) - a group of chemicals first developed for use in textile coatings, non-stick cookware, electronics and firefighting foams - are now responsible for large-scale environmental contamination. When PFAS were identified in the surface waters which supply the island's drinking water reservoir, Guernsey Airport needed help to investigate the issue. Its grounds could potentially have been impacted from using firefighting foams during training and incident response, and immediate action was needed to protect Guernsey's drinking water supply.

The solution

It was important to establish whether the specific PFAS identified in Guernsey’s surface waters were indeed due to the airport using firefighting foams that contained the chemical. Arcadis was commissioned to investigate and assess soil, groundwater and surface waters and, fortunately, we have specific expertise in dealing with PFAS. It meant that we could implement interim emergency response measures, while designing and developing a bespoke water treatment system that would help to clean up supply.


    We set to work immediately and, as part of our initial investigation, identified seven main areas of the airport that had been impacted by PFAS. We prioritised four of these as needing immediate attention and started remediation works straight away. This included removing 15,000 tonnes of impacted soil, which was continuing to act as a PFAS source by leeching into the local water environment.


    We simultaneously designed a water treatment system that would remove any remaining PFAS that posed a risk to Guernsey’s wider water supply. The system we developed uses granulated activated carbon, which works by capturing and treating groundwater and surface water before it reaches the island's drinking water reservoir.


    Despite the difficulties that come with working on an active airport and dealing with a highly complex contaminant, this treatment system was fully installed at the airport in as little as nine months. The treatment system, known locally as the GWIS (Groundwater Improvement System) is capable of treating up to 20 litres of water per second and has ensured that concentrations of PFAS in the island's drinking waters are now well below current UK drinking water criteria.

The impact

Protecting the people of Guernsey

Devising a pragmatic, successful and cost-effective way to manage and mitigate the impacts of this contamination was imperative. Understanding that PFAS are highly mobile in water, they do not biodegrade and some are bio-accumulative – which means they accumulate in living organisms, including humans – acted as a core motivator on the project.

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