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Could a £24m airport extension put Alderney's water quality at risk?

Could a £24m airport extension put Alderney's water quality at risk?

Thursday 25 January 2024

Could a £24m airport extension put Alderney's water quality at risk?

Thursday 25 January 2024

Hopes to increase Alderney's connectivity with a better airport and lengthier runway have long been a topic of discussion – but now concerns have been raised that doing so would put the island's water quality at risk.

Express explores...

What's the plan?

After much debate, back in December 2022, the States of Guernsey agreed multi-million pound plans to redevelop the runway and airport.

However, at the time, it was also agreed that a full and thorough Environmental Impact Assessment would need to be carried out before any work can begin.


Pictured: The red outline shows the proposed expansion and extensions to the airport and runway in Alderney.

Spanning around 30.9 hectares, the proposed works include extending the runway to the west and to reconstruct or refurbish the terminal building and fire station so that larger aircrafts can use the runway. 

What's the point?

Allowing larger planes to land, it was suggested, would mean a boost for tourism with more passengers coming in on every flight. It was estimated this could be as many as 20,000 per year.


Pictured: Alderney wants to bring in bigger aircraft, with more passengers, to boost tourism. 

While some say the idea is a no-brainer, some Deputies have tried to derail the plan – although Alderney's political representative, Alex Snowdon, has maintained that it's important to get on with the work as the current site is continuing to deteriorate. More recently, he has also called for better links with Jersey – with which the island has no direct connection.

But now it seems there could be a new spanner in the works.

What's the problem?

The Environmental Impact Assessment found no significant effects were expected to arise during the actual construction phase of the planned development around the airport and runway.

However, it did raise a major concern for the island's water quality once the new airport and runway are in use.

The review found there could be problems caused as a result of the potential need for de-icing on the larger aircraft which will then be able to fly in to the island.

The work to de-ice ATRs could have what was described in the report as a "major adverse and significant effect" on the water quality of the Bonne Terre Stream, which is the destination for water run-off from the airport.

Detailing the nature of the issue, the assessment document explained that "the biodegradation of de-icers results in the consumption of very high amounts of dissolved oxygen".

"As the Bonne Terre Stream is relatively small there is likely to be insufficient flow to dilute the de-icer contaminated runoff from the airport, which is likely to constitute a significant proportion of the flow," it continued. "This would result in a seasonal but significant adverse impact on the Bonne Terre Stream, the online ponds downstream, and potentially the small wetland area close to Platte Saline."

This is not a risk at present because of the lesser need to de-ice the smaller planes which currently service Alderney, the report said.

Is there a fix?

Against the perceived risks from de-icing, mitigation is proposed in the form of a 'De-icing Management Plan' and a 'Drainage Strategy', which would minimise the effect caused by the larger aircraft.

The management plan would include a water quality risk assessment to estimate what chemicals could enter the water run-off systems through de-icing, and how it can be reduced.

The Bonne Terre Stream's water quality and flows would also need to be monitored along with aquatic ecological surveys "to better understand the sensitivity of the watercourse and associated water features, namely the online ponds and the wetland near Platte Saline".

Following the risk assessments, it may be decided that the water run-off should be discharged a different way, avoiding the Bonne Terre Stream.

But, if no alternative can be found, then de-icing of aircraft and the airfield might not be possible at Alderney Airport.

However, if a solution can be found, then a De-icing Management Plan would focus on the procedural use of de-icing chemicals and in particular how it is managed by Alderney Airport and the Alderney Water Board to ensure that no water is taken from the Bonne Terre for human use when de-icer has been used.


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