Renewed quarrying at Rickney’s presents a significant threat to the water-supply boreholes at Wadesmill Road.
A new Minerals Local Plan is being prepared for Hertfordshire. An area north of Hertford was designated as Preferred Area No.2 in the previous plan. It is proposed to remove this area from the new plan.
An application to quarry sand and gravel from the southern part of Preferred Area No.2, in Bengeo Field, was rejected by Hertfordshire County Council on 22 March, 2017, on a number of grounds. An appeal has been made by the applicants, on which a decision is now awaited from the Inspector and the Secretary of State.
During the final session of the hearing of the appeal at County Hall in October 2018, the possibility emerged of a future application to quarry north of Hertford, using the access road previously used during operations at Rickneys. It is not yet clear whether any such future application would include both operations at the Rickneys site, and operations in Bengeo Field using a northern access via Rickneys.
We can separate two issues here, one over which we have control, and the other over which we have no control. The issue over which we have control is access to operations, such as use of the existing road at Rickneys. The issue over which we have no control is the geology of the area it is proposed to quarry. This geology precludes safe operations, whatever access route might be used.
There are two geological resources of value to the community in the area north of Hertford. One is the non-renewable resource of sand and gravel, the deposits of the early River Thames. The other is the renewable resource of the water in the chalk aquifer that directly underlies the sand and gravel.
In principle, water could be brought into the area by pipeline from distant sources, just as the sand and gravel could be brought in, again from a distance. There is a choice, but not a choice that it is difficult to make.
The more vital resource is water, renewable supplies of which have been provided by the Wadesmill Road boreholes for some 80 years now, with the prospect of continuing supply for at least that long into the future. If removal of sand and gravel from above the chalk aquifer risks pollution of that aquifer, then it is clear that protection of the aquifer has priority.
Would removal of sand and gravel jeopardise the aquifer? Our elected representatives on Hertfordshire County Council believe
that is the case.
An informative note accompanying the 22 March 2017 rejection of an application to quarry in Bengeo Field stated: “Hertfordshire County Council’s Development Control Committee has raised serious concerns regarding the potential for Hertford’s water supply to become contaminated as a result of this development due to the proximity of boreholes to the site.”
A five-minute presentation made by Dr.Bryan Lovell to the Committee in March 2017 was followed by questions from members of the Committee, and by a separate later discussion within the Committee itself. Should the serious concerns of the Committee about the threat to southern areas of Preferred Area No.2 also apply to northern areas?
The short answer to that question is yes. The threat to the boreholes I described on 22 March 2017 also applies to areas to the north. Indeed the threat from quarrying to the north may well be greater. Further quarrying of the northern area would involve two additional risks. One of these risks is specifically local, the other additional risk is related to an aspect of regional geology.
The local risk is the result of previous quarrying. Operations at Rickneys have largely removed the protection of the chalk aquifer provided by the original covering of soil, sand and gravel. Access to any new quarry would be through these unprotected areas. The nature of this risk is described by K.J. Edworthy in his 1992 report on the hydrogeology of the area, commissioned from Ove Arup by McMullen and Sons Limited.
The risks identified by Edworthy have been reviewed and endorsed by the leading hydrogeologist Professor Frederick Brassington, in a 2017 report commissioned by Stop Bengeo Quarry group. Professor Brassington was expert witness for Stop Bengeo Quarry at the appeal hearing in County Hall in May 2018.
The second, regional, risk arises from geological forces affecting England as a whole. Let me give a little technical background here.
Analysis of UK earthquakes published in 2010 by B. Baptie of the British Geological Survey shows that there is “…northwest-southeast compression and northeast-southwest tension…” The result of this NE-SW tension is to widen fractures trending NW-SE in rocks lying below the surface of England, rocks that include aquifers such as the chalk.
On the strength of this broad regional picture, we might expect preferential movement of water through NW-SE trending fractures in the chalk extending from the northern part of Preferred Area No.2 towards the Wadesmill Road boreholes. A
detailed local survey of fractures in the chalk aquifer would be required to quantify this regional effect on enhancing flow from the northwest towards the boreholes.
The overall risk to water-supply presented by further quarrying in this area is established on the basis of sound geological evidence. I summarised this evidence in my presentation to Hertfordshire County Council on 22 March, 2017. The evidence is set out in detail in the independent hydrogeological reports of Brassington and Edworthy. Then there is the additional evidence I present here. On geological grounds alone we may conclude that north of Hertford is a poor place to locate a quarry.
Those in favour of quarrying might argue that operations at Rickneys were carried out previously without obvious contamination of the Wadesmill Road boreholes. As Professor Brassington said at the May 2018 hearing of the appeal at County Hall: “I would say the operator has been most
fortunate.” We can add that no significant spill was reported during those earlier operations. There is a significant risk of pollution of the aquifer from quarrying the overlying sand and gravel. You would not site new water- supply boreholes in a fractured chalk aquifer in the
vicinity of an existing quarry. Nor should we quarry near existing boreholes that draw water from a fractured chalk aquifer.
The proposal by Hertfordshire County Council to remove preferred status from the area north of Hertford is correct. Indeed, Council should go further.
The area of chalk aquifer between Bengeo and Chapmore End should now be designated by Council as needing special long-term protection from any further disturbance by quarrying.
Within that framework, it is obvious that any future application to quarry in the vicinity of Rickneys can be readily rejected. We can argue about access, but we cannot argue with the rocks.