The sand and gravel that Aggregate Industries wants at Straitgate Farm starts on average 2.3m below ground level.
The company’s permission only permits quarrying above the maximum water table.
Clearly, therefore, in areas where the maximum groundwater level is closer than 2.3m below the ground surface, there is likely to be no sand and gravel available for the company to recover.
In practice, to make it at all worthwhile – bearing in mind the costs, ecologically or otherwise, involved in stripping, storing, restoring more than 2.3m of 'best and most versatile' topsoil, subsoils and overburden – the maximum groundwater would need to be no nearer than 3.3m below ground level to be able to extract even 1 metre’s worth of sand and gravel.
Earlier this month we posted how the water level at borehole PZ2017/03 has risen to ground level, and how Aggregate Industries has been pulling the wool over everybody’s eyes – planning inspectors included.
Obviously, there is no resource available to the company for an indeterminate area around this borehole on the eastern boundary of the extraction area.
It's now the same for the area around another borehole.
Last week, the groundwater level at borehole PZ2017/02 was just 1.19m below ground level. This is again on the eastern boundary - as shown below:
This groundwater level is higher, by our estimation, than the borehole’s previously recorded maximum on 18/02/2020. It is notable that levels in this location have only been monitored between 2017 and 2022, and not, like a number of the other locations, during the wet winter of 2013-2014.
It’s not altogether surprising that the previous maximum has been exceeded, given the recent rainfall:
Last February was one of the driest on record for England & Wales with many locations seeing less than 10% of normal rain.
— Dave Throup (@DaveThroup) February 18, 2024
This February will be one of the wettest, many places will record more than 200%.
Extremes driven by climate change and things will get more extreme. pic.twitter.com/3xPTqh8soj
This all ties in with what we said in 2021, when we posted Depth of available resource at Straitgate is in places ZERO.
Borehole PZ2017/02 is where Aggregate Industries plans to locate infiltration trenches to stop downslope flooding. Clearly, with water levels this high, those trenches can't work as intended. Again, as we posted in 2021, Infiltration areas to stop flooding couldn't be 3m deep – without breaching MWWT and in 2018, AI’s infiltration plans can’t work either – with groundwater this close to the surface.
Ordinarily, if Aggregate Industries were monitoring the site, another calculation of the extrapolated maximum winter water table, the MWWT, would now be triggered, the company’s permitted base of extraction would have to be moved upwards and the available tonnage moved downwards.
For reasons we can all guess, the company is not currently monitoring groundwater levels across the site.
