A planning inquiry that will scrutinise an application for a quarry on the site of the former Hatfield Aerodrome has been opened.

The controversial application – which seeks permission to extract up to eight million tonnes of sand and gravel from the site over a 32 year period – was turned down by the county council earlier this year.

But – following an appeal against that refusal by applicants Brett Aggregates – the decision is being reconsidered by the inquiry.

Although the county council had been expected to defend the decision, in the run-up to the inquiry they withdrew their “reasons for refusal”.

On the opening day of the inquiry yesterday, the hearing was told that the council now agreed that – “subject to the imposition of suitable conditions” – the appeal should be allowed.

The newly-formed ‘Colney Heath Group’, however, urged that the quarry proposal should be rejected.

Speaking for the group Sue Meehan told the hearing that the proposal was “a significant threat to the character, safety and environmental integrity” of the local area.

As well as the county council and the Colney Heath Group, on the first day of the inquiry Inspector Melvyn Middleton also heard statements from Brett Aggregates and other interested parties.

But the bulk of the hearing – which could last up to 10 days – will be based around a series of round table discussions.

These will focus on a range of topics that include the need for sand and gravel extraction, the Green Belt, the water environment and highway safety.

At the end of the inquiry the Planning Inspector will make recommendations to the Secretary of State, who will then make the final decision.

The application for the quarry includes a new access onto the A1057, an aggregate processing plant and other facilities.

The county council had initially refused the application on eight grounds, focussed around the Green Belt, heritage, residential amenity, landscape character, biodiversity, public access, the highway and groundwater.