Last week, it was reported that a High Court judge had rejected a judicial review of Shropshire Council's decision to grant permission for a quarry near Bridgnorth. We posted about this site back in 2018.
The claimant argued the council had downplayed the proposal's potential impact on local groundwater, that "there was inadequate evidence upon which to conclude that significant effects were not likely." However, the judge ruled that the council was within its rights to conclude "the proposals are not considered likely to lead to any significant impacts in relation to groundwater" – notwithstanding "major ambiguity in the [Environment] Agency's response." How could the council be so sure? Here’s the clue:
The applicant is willing to accept a condition ensuring that a minimum freeboard is retained above the aquifer. A freeboard of 2m is suggested, using results of the proposed groundwater monitoring scheme. In practice however, the applicant’s hydrological data indicates that any freeboard is unlikely to be less than 8m.
Aggregate Industries, on the other hand, would be on far shakier ground at Straitgate – where the impact on local groundwater from its plans to quarry the site is also a significant bone of contention. Here, the freeboard proposed by Aggregate Industries – the amount of material planned to be retained unquarried above the water table, to protect surrounding drinking water supplies for 100 people, to act as a margin of safety, to act as a margin of error – is precisely nothing, zero metres. Professor Brassington warns:
any proposals to quarry at Straitgate Farm will impact on the fragile groundwater system and cause the flows of springs to decrease and the quality of the water also to deteriorate
Prof Brassington also says, instead of a 0m freeboard, or even a 2m freeboard, at Straitgate – which as Dr Rutter recognised has "a very steep hydraulic gradient":
...if quarrying were to be permitted, I maintain that a 3 m unquarried buffer should be left above the maximum water table to minimize the negative impacts.
If there were ever a challenge to the Straitgate decision and the potential impact of the development on local groundwater – claimants could point not just to the 2m or more left at Bridgnorth, but a range of other quarries where the proposed freeboard was greater than Aggregate Industries' zero:
To protect groundwater quality ... Across the whole of the site 1 metre of sand will be left above the maximum recorded groundwater level.
A minimum stand-off of 1 metre will be maintained between the base of extraction and the underlying watertable (based upon peak groundwater levels)…. The peak groundwater level contours are derived from piezometer data collected over a monitoring period of up to 20 years.
Conditions were imposed to restrict the extraction of sand to within 1.2m of the highest recorded water levels to ensure there was no effect on the local ground water system.
Although the sand deposit continues at depth there are no proposals to extract any deeper material to ensure a suitable stand-off of at least 2m above the water table as is the case with the current extraction.
the limitation of all workings to at least 1m above the highest water table… Historically quarrying has always left 1 metre of undisturbed sand and gravel between the bottom of the quarry and the surface of the groundwater.
The maximum depth of excavation shall be no deeper than 2m above the maximum groundwater levels
The quarry floor will be maintained approximately 2 m above the maximum recorded groundwater level in common with other sections of the quarry.
Even in Devon:
The scheme proposes extraction within the Pebble Beds to 1m above the highest recorded water table level.
And last but not least, in Shropshire.
The Glaciofluvial Deposits are classified by the Environment Agency as a Secondary A aquifer, however there are no known groundwater abstractions in the vicinity of the Site…. In modelling the resources, a base of deposit at 45mAOD was assumed; this is approximately the level of the floor in the Buildwas Quarry and is some 2-3m above the water table.
Why have we saved this one for last? Well, not only is the freeboard one of the largest, but the person responsible for calculating the 1.9 million tonnes of sand and gravel available at Buildwas – 2-3m above the water table – once worked for Aggregate Industries. Not just that. He was, in fact, the author of the controversial 0m freeboard proposal at Straitgate. Small world. One rule for some...
Further afield we find that in Switzerland – the home of Aggregate Industries’ parent LafargeHolcim – the government has banned the extraction of sand and gravel from areas where drinking water is sourced, except "in a limited number of exceptions" in which case:
a protective layer of material must be left that is at least 2 m above the highest maximum ten-year groundwater level;
If a zero metre freeboard were such a good idea, why hasn't it been adopted elsewhere? Think how much more sand and gravel could be recovered.
At Straitgate, as Prof Brassington points out:
The method of working that is proposed is untried anywhere else in the country and is designed to maximize the sand and gravel dug with no regard to the changes it will inevitably bring to both the quantity and the quality of the groundwater and the springs it discharges through.
How exciting it would be for locals dependent on their wells and springs for drinking water from the Straitgate aquifer to be part of one huge experiment!
