Hertfordshire county councillors were expected to make a decision on the site located between Hatfield and St Albans at a meeting on Wednesday.Construction and building materials group 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.
In November, county council officers said the planned quarry should be given a green light, despite the site being affected by bromate pollution from an old chemical works.
The recommendation has come in the face of strong objections from the local MP and Welwyn Hatfield Borough Council, which is calling for an independent investigation into the plume. There are fears that any disturbance by the quarry could impact on the flow of that 'plume' and could lead to contamination of drinking supply.
However, the EA has said it can go ahead, subject to conditions that it will not further contaminate the local groundwater.
Despite this, the county council's development control committee refused to take a decision without further information from the EA.
According to local press reports, Conservative county councillor Seamus Quilty lead the calls for deferment and said the decision was a "balancing act" - and that it was "an absolute disgrace" that the EA was not present.
He said the EA's references to reducing and managing the risk meant that there was a risk and asked the watchdog to give a professional guarantee that there would be no contamination to the public water supply.
Conservative councillor Michael Muir said it was the most difficult decision of his 16 years on the committee and added that he couldn't make the decision on "one-sided evidence".
Planning permission for the quarry was granted initially in January 2018, subject to agreeing on the establishment of a country park as part of a section 106 agreement. But an ongoing dispute over the terms of a lease has prevented this condition being fulfilled.
Following the meeting on Wednesday, 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 place in the future."
The EA has been contacted for comment.