Hatfield Aerodrome quarry has been taken off a Hertfordshire County Council agenda, after campaigners warned of carcinogenic leaks.
On Friday, the HCC said it had received further information from the developers of the site so it will delay the decision on quarry plans.
Members of the Hatfield-based Ellenbrook Area Residents' Association - who delivered a petition to the county council's development committee - said they believe the information they have on the carcinogenic bromate plume is now "out of date".
Presenting the more than 1,000-strong petition to the committee on June 27, EARA's John Jackson highlighted concerns about the impact a quarry on the site could have on the spread of the bromate plume.
He suggested the plume - believed to have been caused by the Sandridge chemical spillage in the past - could pose a real and serious threat to drinking water in Hatfield and across Hertfordshire.
He said the onus should be on the applicants to show that the site is not contaminated, with more information being available before a decision is taken.
It was acknowledged in a report by HCC, in August 2018, that the site of the quarry could have an high impact on the ecological status of water bodies, heritage assets, recreation and sensitive land uses.
Another report by the Environment Agency also showed high concentrations of bromate supply between 2011-17.
The application to develop the site - lodged in 2016 by Brett Aggregates Limited - was objected to by nearby residents, councils and other organisations consulted on the plans at the time.
"We believe that important council decisions - such as the application to quarry the old Hatfield Aerodrome on behalf of Brett Aggregates - should be supported with accurate, up to date and independently validated information," Mr Jackson said.
"When informed that this application for the quarry may be heard we checked the planning portal and could not find an updated traffic survey or flood risk document - and still no health impact assessment.
"The traffic flow has greatly increased since the 2014 survey and the flood risk assessment does not take into account new and proposed housing developments close by, which will remove a significant amount of the porous land in the surrounding area."
Development committee chairman, Cllr Ian Reay, said in a written response, he would welcome the opportunity speak again about the site at a future meeting.
No planning permission has been granted so far.
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