The following address was made to Hertfordshire County Council’s Development Control committee on Wednesday 22nd March 2017 by Dr.Bryan Lovell, OBE, CGeol.
I’m a geologist based at the University of Cambridge. I’m also adviser to the mining company BHP Billiton. Previously I was with BP Exploration. I was recently President of the Geological Society, the learned and professional body responsible for awarding chartered status to geologists.
Chartered geologists apply their science to getting from rocks the resources we need, by mining, pumping and quarrying. Those resources include gravel, sand – and water. As a chartered geologist myself, I rather like quarries – but not this one. I’ll explain why – please brace yourselves for a brief lecture.
In the field it’s proposed to quarry, sand and gravel lie on top of chalk. The chalk is the aquifer that supplies Hertford with water. Six million litres of water a day come to Hertford from the Wadesmill Road boreholes that lie at the edge of the very field it is proposed to quarry.
All parties involved in this application recognise the risk of pollution reaching these boreholes as a result of the proposed quarrying. The specific geological nature of this risk is identified in the report from the applicants’ own consultants, Hafren Water.
The report from the Environment Agency does not consider this risk. Nor does it refer to the detailed hydrogeological report on the area commissioned from Ove Arup by McMullen and Sons Ltd in 1992. The author of the 1992 report is Chartered Geologist K J Edworthy, an expert on the chalk aquifer. His document provides independent confirmation of the risk to the Wadesmill Road boreholes. Yet the officers of the Council are under a statutory obligation to follow even incomplete advice of the Environment Agency. I suggest that to fill the gap left by the Agency, and release those officers from obligation, we now consider the rocks themselves, so we can understand the specific geological risk.
The problem with the chalk aquifer is this: very quick pollution, very slow decontamination. Fractures in the chalk aquifer mean that any pollution can reach the Wadesmill Road boreholes rapidly. But clearing pollution from the small pores within the body of chalk rock is a lengthy and costly business.
Let’s picture Bengeo quarry on a wet morning. When a digger disturbs sediment in the vicinity of a large fracture, muddy water may reach the boreholes before the driver breaks off for his lunch. By the time any pollution is detected, lasting damage may well have been done to Hertford’s aquifer.
Monitoring of pollution as it takes place is not the main issue: pollution must be prevented from the word go. Assessment of risk of pollution requires a detailed map of the buried chalk surface, and a survey of the size and orientation of fractures within the chalk aquifer. We do not have this information, which can only be acquired by spending time and money. Without this information it is not possible to decide whether quarrying in this field is even a feasible project, let alone give authority to begin operations.
Why are we even considering digging up this field, thereby threatening our water supply both in the short and long term? There is no need for this particular sand and gravel. During the proposed ten years of production, only one thousandth part of UK onshore supply of aggregate would come from Bengeo.
You wouldn’t drill boreholes in the chalk at the edge of a working quarry to supply a town with water. So don’t put a quarry by Hertford’s boreholes. Given the boreholes are there, it is hard for a geologist to imagine a worse site for a quarry. That field should be taken off the list of preferred sites, now and forever.
Those boreholes on the Wadesmill Road were drilled in 1936, at the edge of a field.
For 81 years the leaders of our community have had the good sense to leave that field undisturbed. We should continue to leave that field to the skylarks.