Two Deputies are asking the States to look at how land at Guernsey Airport will be used after contaminated soil is removed.

Perfluorooctane Sulphonate (PFOS) is a ‘forever chemical’, which will cost more than £16.5m to remove, according to the States Trading Supervisory Board (STSB), which oversees the airport’s operator.

PFOS – a remnant of old firefighting foam – had been temporarily stored in geotextile-lined bunds during previous runway works, however that protective membrane has reached the end of its life and is failing.

Now Deputy Adrian Gabriel has put in an amendment (seconded by Deputy Andy Cameron) to look at how the land could be used once the PFOS-contaminated soil is removed, with options including a bus terminus, bike lockers and integrated parking.

Pictured: Deputies Adrian Gabriel (L), and Andy Cameron (R), are looking to lock down improved infrastructure as part of any PFOS plans.

Deputies will be asked to decide whether or not to approve plans to ship contaminated soil to the UK, which is the preferred plan from STSB, at the States Meeting next week (24 June). 

The amendment attached to those plans does not seek to significantly alter them, instead using it as a vehicle for potentially improving infrastructure. 

It asks STSB and Policy and Resources (P&R) to explore using any freed-up bund land for a “multimodal transport hub”.

This would see the creation of “a central location where multiple forms of transit converge” at Guernsey Airport, where commercial aircraft, public buses, bicycles, rideshares, and pedestrian pathways integrate.

Table 1 - Summary of established soil remediation options with cost estimate below £20m and their feasibility Remediation Approach Status On-island options Engineered Containment: with Stabilisation/ Solidification Established Engineered Containment: at Guernsey Airport without Stabilisation/Solidification Established Soil Washing Established Estimated Cost* Feasibility 100 yrs: £10.6m- £15.4m 20 yrs: £6.8m- £16.4m £11.8- £18.4m This option would create a landfill site on-island requiring licencing and leachate monitoring. Costs for this are not included. Technically feasible but unlikely to gain regulatory approval. The option does not remove risk to the environment and public health, and does not meet CSF2. Discounted. Theoretically technically feasible, however this is the existing system; it has not lasted the design life and is failing, it is unlikely to gain regulatory approval. Costs do not include ongoing monitoring, leachate management (GWIS), licensing and the costs of another solution after 20 years. The option does not remove risk to the environment and public health, and does not meet CSF1, CSF2. Discounted. Theoretically this option is technically feasible, however the challenges to ( building and operating a facility on-island are enormous including specialist plant and expertise to design, build and run; furthermore, disposal of resulting fines could be challenging to agree acceptance at on-island landfill and decommissioning of the plant would be a specialist and costly undertaking. Costs for this are not included. Licensing would only be granted once built. The option removes environmental and public health risk but does not meet CSF4. Discounted. Off-island options Soil Washing Established {12.3m** The option is technically suitable, and the approach is accepted by the Regulator. This solution has been tendered so costs are known. It is a permanent solution with no maintenance costs. The option removes environmental and public health risk and meets all the CSF. Preferred Option. *Costs are 2025 estimates provided by the technical advisor plus optimism bias contingency allowance. Range does not allow for inflation, or maintenance costs for non-permanent options ** Option tendered 2025; cost and design are known plus calculated risk cost contingency Note: Issue costs would apply to all options and have not been included
Pictured: A table of the different options compared by STSB, as part of the proposition letter laid before the States, Page 10.

Recent testing shows the chemical levels are rising, which presents a significant potential pollution risk to groundwater streams near the site, and points to the problem of the dissolving bund. 

STSB and the environmental regulator have chosen to export the soil to the UK for specialist “soil washing” as their preferred option, which would see around 8,500m³ of soil excavated, shipped to the UK, and then washed. 

On-island containment options were rejected because they do not eliminate the chemical, require indefinite monitoring, and there were doubts over granting regulatory approval. 

Crucially, STSB says local containment also did “not remove risk to the environment and public health,” nor did the options meet the “satisfaction of the local waste regulator”, Guernsey Water. 

Building an on-island “soil washing” treatment facility was also deemed technically unfeasible and lacks disposal routes for toxic remnants, ultimately it was decided against as “the solution must utilise a fully licensed treatment plant” and licensing for anything built locally “would only be granted once built”.

More to follow…