The contamination was caused by the chemical Pfos (Perfluorooctane Sulfonate) which used to be contained in fire-fighting foam.
About 14,000 tonnes of contaminated soil was removed from the airfield in 2012 and this was sealed in a specially-created cell within the raised grass bund alongside the main entrance to the airport.
A smaller cell was created at the western end of the bund in January 2015 to contain about 2,500 tonnes of soil that had been contaminated following a plane crash in a Forest field in 1999.
Guernsey Ports managing director Colin Le Ray said options were still being considered for the disposal of the soil and several treatments were being developed by the commercial waste industry.
‘Guernsey Ports has (with our professional advisor) evaluated a number of these treatments and is undertaking trials to test local soil samples to establish which methods of treatment and/or safe disposal can be recommended for approval by the Office of Environmental Health and Pollution Regulation (OEPHR),’ he said.
Samples were taken from the airport late last year and are being analysed by a UK laboratory to see which solution might be best for the material.
‘Among the viable options under consideration include off-island incineration in a specialist facility overseas, soil washing, soil stabilisation or upgrading the current storage arrangements in front of the airport terminal building,’ he said.
There is currently no timetable for when the work might be done and this will be based on which options for dealing with the contaminated soil are viable and affordable.
‘In the meantime, Guernsey Ports works with the OEPHR to ensure the continued licensing of the storage site in front of the airport terminal building,’ said Mr Le Ray.
The States of Guernsey filed an unsuccessful lawsuit against 3M, the manufacturer of the foam, in a bid to recover £20m., in 2016.
An offer from the company of £3.25m. was rejected and, while the parties agreed to mediation, it was unsuccessful.
3M contested the States’ claim and argued that the legal time limit within which such claims must be brought had expired and this was accepted by the High Court.