Plans for the Operation Stack alternative, Stanford West truck park near the M20, are in the balance after local protesters were granted a judicial review of the scheme.
The review, to be heard in June, will consider whether the scheme has failed to carry out an environmental assessment as required by EU law.
If the protesters' legal challenge is successful, the scheme could be delayed for at least two years.
The 3,600 space truck park, which was given the green light by former Transport Secretary Patrick McLoughlin last summer, is aimed at preventing major congestion on the M20 whenever cross channel services are disrupted.
G Forge, the owner of local landmark Westenhanger Castle in Hythe, has brought the legal challenge, supported by Stanford Parish Council.
It argues that Highways England's environmental impact assessment was inadequate and the scheme should be reclassified as a nationally significant infrastructure project, requiring a Development Consent Order.
Stanford Parish Council chairman Matthew Webb said: “The agency has failed to undertake a full and proper assessment of the likely significant environmental effects of the project, which would normally take the form of an Environmental Impact Assessment report.
“Neither of these challenges provides a silver bullet to stop the truck park. However, if successful, they could result in a delay of up to two years. In that time the political and economic landscape can alter significantly, and support and funding for the truck park may disappear, particularly if we continue to see a low frequency of Operation Stack.”
The scheme has already been criticised by MPs. Last year the Transport Committee raised concerns that it had been rushed through in reaction to major congestion created on the M20 in the summer of 2015 when the migrant crisis and industrial action by French ferry workers in Calais disrupted cross channel services.
Asked about the judicial review, a DfT spokesman said: “We do not comment on possible or ongoing legal proceedings.”
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