Controversial plans to build a quarry on the site of the former Hatfield Aerodrome have been dismissed at appeal.

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

Their application included new access onto the A1057, an aggregate processing plant, a concrete batching plant and other ‘supporting facilities’. They appealed to the Planning Inspectorate after their proposals were refused by Herts county council.

Following a nine-day planning inquiry in November, inspector John Woolcock has now dismissed the appeal.

In his 29-page decision notice Mr Woolcock highlights the ‘important contribution’ the quarry would make to meeting the county’s need for aggregates.

But he says the harm to the Green Belt, the character, appearance and amenity of the area and to pedestrian safety all outweigh the benefits of the minerals that would be extracted. He says it has not been demonstrated that the development could be made acceptable through the use of conditions or planning obligations.

Addressing the Green Belt, Mr Woolcock highlights the inclusion of the ‘concrete batching plant’ in the application, which it is said "plays no direct role in the winning and working of minerals". He suggests this would be ‘inappropriate development’ and harmful to the Green Belt.

He said there is no convincing evidence that dust, emissions of crystalline silica or other effects would impact air quality, but he does suggest that at times noise could have ‘a significant adverse effect’ on those living at nearby Popefield Farm.

Mr Woolcock also points to the long-term impact on the character and appearance of the site. Even with progressive restoration, he says the development would have an adverse long-term effect on the character and appearance of the area.

While he accepts it may eventually provide an enhanced landscape, he suggested this would be "so far into the future that it would not compensate for the cumulative harm over the long operational period of the appeal scheme".

He also recognises the value of local access to the country park, and said the area currently provides circular walks through relatively isolated and quiet areas with informal paths that are well used.

He suggests some of the rights of way identified on the application would not be attractive – and users seeking a circular walk would have to cross the busy A1057.

“Given the speed of traffic and poor sightlines for pedestrians along this northern side of the road, such crossings, especially with groups of people that might include children or dogs, would be hazardous,” he said.

He acknowledges local concerns that additional HGVs from the site may impair the safety of other road users. But he points to evidence that suggests HGVs associated with the quarry would not have an unacceptable impact on highway safety.

He added: "The long-term ecological benefits of the progressive restoration would be sufficient to compensate for the harm to biodiversity during extraction/infill over the operational period."

Pointing to the benefit of the scheme, he highlighted the need for minerals and the provision for inert landfill.

Local authorities are required to have a steady and adequate supply of aggregate by maintaining a ‘landbank’ of at least seven years for sand and gravel.

According to the decision notice, HCC is reported to have a “significant shortfall” with a ‘landbank’ of 5.9 years.

Mr Woolcock says the provision of minerals to the local economy is a matter of ‘substantial significance’ that should be given ‘great weight’.

But he concludes that the benefits of aggregate extraction and co-location of the concrete batching plant did not outweigh the negative factors.

During the inquiry, there was a great deal of discussion relating to the hydrogeology of the site, particularly the presence of the ‘bromate plume’.

Mr Woolcock suggested the ‘dynamic interaction of several hydrogeological factors’ resulted in ‘considerable complexity’.

He said that given the risk posed by the bromate plume, it was problematic to predetermine the likely impact of de-watering the lower mineral horizon and it was clear it would be necessary for a planning condition to prevent pumping from the lower mineral aquifer.

He also said that to reduce the risk of exacerbating bromate pollution, it would be necessary to impose monitoring levels that would trigger intervention.

And he suggested the locations for these monitoring boreholes would require further consideration.

However, he suggests that issues relating to exacerbation of bromate pollution could be addressed through planning conditions – "and would not weigh significantly in the planning balance".

In September, Brett Aggregates submitted a further application to quarry the former Hatfield Aerodrome site, which includes a number of changes. This newer proposal does not include the erection and operation of a concrete batching plant.

It stipulates that there would be no pumping from the ‘lower mineral horizon’ and that the distance between extraction in that horizon and the bromate plume is increased, from 50m to 100m.

And the access road from the quarry entrance would be moved by five metres to the east, in order to allow for additional acoustic screening.

At the inquiry, Brett asked whether the inspector could consider the changes contained in the amended scheme.

But in his decision notice, Mr Woolcock ruled that it should be the plans as initially determined by HCC that should be the subject of the appeal decision.

“With the requested substitution of plans, I consider that the proposed development would be so changed that to grant it would be to deprive those who should have been consulted on the changed development of the opportunity of consultation,” says Mr Woolcock.

“In the circumstances, I consider that a significant likelihood of prejudice would arise if the appeal was dealt with on the basis of the amended scheme and substituted drawings suggested to the Inquiry.”

The plans – as determined by HCC in November 2020 – include the concrete batching plant and the proposed pumping of the lower mineral horizon.