An inquiry to determine if a quarry should be approved for the site of the former Hatfield Aerodrome has opened.

Brett Aggregates want to extract up to eight million tonnes of sand and gravel from the site – between Smallford and Ellenbrook – over a 32 year period.

But last September its planning application – which includes new access onto the A1057, an aggregate processing plant, a concrete batching plant and other "supporting facilities" – was refused by Hertfordshire County Council.

In refusing the application, county councillors had pointed to a range of factors – including the impact on the Green Belt, air quality and traffic, the cumulative effect of quarrying in the area and the risk to the bromate plume.

And on Tuesday (November 16) – as a result of an appeal against that decision by Brett – the Planning Inspectorate opened an inquiry that will determine whether or not to overturn the county council’s decision.

At the hearing, Richard Kimblin QC, acting for Brett, highlighted the position of the aerodrome site as being within one of the council’s ‘preferred’ sites for sand and gravel extraction.

He stressed that when it was identified as such it was known that "there was a bromate plume issue to address". This "preferred’ area was identified on the "express understanding" that it sat within the Green Belt.

With regard to the "bromate plume", he suggested the county council, the Environment Agency and Affinity Water had now "agreed that the bromate issue does not give rise to a reason for the refusal of planning permission" – subject to the imposition of appropriate planning conditions.

And considering Green Belt concerns, he suggested that the proposal was "not inappropriate" development.

He also suggested there were no alternatives for sand and gravel extraction in the county that were not in the Green Belt.

Acting for HCC, David Forsdick QC said the council accepted that "if it can be done safely" the minerals can, and need to, be extracted.

He said the council now accepted that there was no practical way of extracting the mineral without the HGVs and highway impacts – so had withdrawn this reason for refusal.

He said that as a result of evidence provided by an independent expert the council was satisfied the mineral could be safely extracted without an adverse impact on groundwater or public water supply, subject to suitable conditions.

And he suggested this would require a condition that pumping would not be permitted across most of the site because of the risk pumping creates to the bromate plume.

But he said elements of the application such as the concrete batching plant were not appropriate for the Green Belt and that the processing area is excessively large.

Opening statements were also made by representatives of Colney Heath Parish Council, Ellenbrook and Smallford Residents’ Associations and the Environment Agency.

Cllr Peter Cook, of Colney Heath Parish Council, focused on four areas of objection: the Green Belt, the cumulative impact, highways and hydro-geology, including the bromate plume.

And Sue Meehan, speaking for Ellenbrook and Smallford Residents’ Associations, pointed to the cumulative impact of having so much quarrying in one small area of Hertfordshire.

“There is a strong sense of opposition to the quarry from the whole area and hundreds of residents have objected to the proposal to quarry and over 1,000 have signed petitions against it,” she said.

She pointed to the 32-year time scale as well as concerns about noise, dust, additional HGV traffic and increased flood risk.

Sue highlighted fears relating to the bromate plume, which sits beneath the site, suggesting that the "magnitude" of the contamination had not been taken into account when the council drew up its local minerals plan.

“We strongly believe that quarrying on Ellenbrook Fields is too high a risk to take because of the bromate proximity,” Sue said.

“The probability of something untoward occurring may be low, but the impact is too high to ignore.

“This combination of low probability and high impact is too high for residents to be expected to accept.”

The hybrid planning inquiry is being held at the Fielder Centre, Hatfield Avenue and can also be accessed online.

Members of the public can attend the inquiry subject to the discretion of the Planning Inspector.