A decision on whether a quarry should be allowed on the site of a former aerodrome has been postponed amid fears of water pollution.

Brett Aggregates has drawn up plans to extract up to eight million tonnes of sand and gravel from the 87.1 hectares aerodrome site, which sits between Smallford and Ellenbrook.

But concerns have been raised about contamination of water below ground.

That’s because a ‘bromate plume’ – attributed to a leak from a former chemical works in Sandridge – flows close to the site.

And there are fears that any disturbance by the quarry could affect the flow of that ‘plume’ and lead to contamination of drinking water.

Brett Aggregates – which hopes to begin work on the site in 2021 – has insisted it will take action so there is no risk of contamination.

And the Environment Agency says the proposed operations – and the required planning requirements – would ‘reduce and effectively manage the risk’.

But the county council’s development control committee on Wednesday refused to take a decision without further information from the Environment Agency.

And members have asked that representatives from the Environment Agency attend the next hearing – so their concerns can be addressed.

Leading calls for the deferment, Cllr Seamus Quilty said the decision was a "balancing act” – and that it was “an absolute disgrace” that the Environment Agency was not present.

He said references to ‘reducing’and ‘managing’ the risk meant that there was a risk.

He said he wanted to ask the Environment Agency ‘face to face’, if they could give a professional guarantee that there would be no contamination of the water supply.

“Not having them here is ridiculous,” said Cllr Quilty, who also asked tha director of public health Jim McManus was on hand to answer their questions.

Cllr Michael Muir said it was the most difficult decision in his 16 years on the committee. And he said he couldn’t make the decision on “one-sided evidence”.

At the end of the meeting the decision to defer the decision to a later date was taken unanimously by the committee.

Earlier councillors had heard from and on behalf of Ellenbrook Area Residents’ Association, Welwyn Hatfield Borough Council, Smallford Residents Association and on behalf of the owners of Popefield Farm.

As well as the pollution from the bromate plume, their concerns included the implementation of a previous Section 106 agreement for a country park on the site, the cumulative effect of the quarry, such as traffic, and the direct impact on Popefield Farm.

Councillors were also addressed by Brett Aggregates’ planning director Simon Treacy  and Peter Rowland from SLR Consulting, who is project manager for the Hatfield site.

Mr Treacy, from Brett Aggregates, pointed to the importance of mineral extraction and he said the scheme had been designed to the highest standards.

He said the company had undertaken considerable research to understand the physical properties, extent and behaviour of the bromate plume.

And he said their plans had been independently scrutinised by the Environment Agency and Affinity Water.

When asked if he could guarantee that there would be no contamination of the water supply, he said: “Yes,we can”.

Mr Treacy also said he understood the importance of the provision of the country park.

And he said as much as possible would remain open to the public during the phased extraction of the sand and gravel.

Meanwhile project manager Mr Rowland said the bromate plume was “static” and in answer to a question he said the risk of it leaking into the water supply was “low”.

The meeting heard that work on the Green Belt site – which would be split into seven separate four-year phases – would continue (including restoration) for up to 32 years.

It was also reported to councillors that the Environment Agency had specified that no minerals should be extracted from within the existing plume and that activities close to the plume should neither change the water flow or interfere with the remediation of the bromide and bromate pollution.

And according to a letter submitted by the Environment Agency, the planned operations and the recommended planning condition will ‘reduce and effectively manage’ the risk to ground water.

Following the meeting on Wednesday (December 18) Simon Treacy, planning director for Brett Aggregates, said: “We are disappointed that the committee has decided to defer consideration of the application today.

“But we respect the decision that has been made and we look forward to hearing the committee’s decision when it takes places in the future.”