In May, a Professor of Hydrogeology produced a damning report concluding that 'ANY quarrying at Straitgate would cause problems'.
The Environment Agency, through the Area Director of Devon, Cornwall and Isles of Scilly, has now responded to Professor Brassington’s report – essentially dismissing large chunks of it, essentially saying that the person at the EA responding to Aggregate Industries' planning application to quarry Straitgate Farm knows better than a Professor of Hydrogeology who has authored textbooks on the subject, essentially saying the EA found more comfort in the story being spun by an aggregates giant desperate to eke out the maximum amount of material, who, for a long time, couldn’t even come clean on how deep it intended to dig.
The EA – which has a statutory duty to protect the water environment – does however concede:
We agree that it would be challenging for machine operators to excavate precisely down to the planned quarry base (MWWT in summer and MWWT plus 1m in winter). We will therefore recommend to Devon County Council that they obtain a detailed method statement from Aggregate Industries (AI), describing how they plan to achieve this.
The EA has conceded another point too.
Cadhay Spring derives its water from Straitgate, and supplies Grade I listed Cadhay House, surrounding properties and a busy tea room; 60 people are reliant on this source, 2000 people visit the tea room each year. It's an important source. The EA has designated a SPZ across Straitgate in an effort to protect it.
Previously, however, Cadhay was not to be included in any Section 106 covering the provision of alternative drinking water supplies should private springs or wells surrounding Straitgate become diminished or polluted due to quarry operations. We posted about this as far back as 2015 in For those worried about losing their water supply... Now the EA says:
Although we have concluded that it is unlikely that quarrying at Straitgate Farm will affect Cadhay House’s private water supply, we will recommend to Devon County Council that Cadhay House should be included in the Section 106 Agreement. The Agreement includes a groundwater contamination provision. We will recommend to Devon County Council that this is updated to explicitly include pH.
Unfortunately, the EA’s concession does not include the listed mediaeval fishponds – the reason why the Devon Gardens Trust objects. Unfortunately, as a leading planning solicitor has already pointed out, AI’s legal assurances for alternative water supplies are “unfit for purpose”. However, this obviously increases the potential financial exposure for AI. The cost of restoring water supplies to Cadhay would not be insignificant, the reason no doubt why AI had previously argued against the need for Cadhay to be part of any Section 106.
On the subject of the 'Maximum Winter Water Table' – the base of any quarry – not accurately reflecting maximum groundwater levels, the EA continues to rely on a disparate assortment of boreholes to corroborate AI’s estimate of the MWWT, a modelled surface based on the argument that groundwater levels in winter 2013/14 were the highest on record. The EA is choosing to ignore historical evidence from the site – as posted here and here – in particular, the base flow in one of the streams emanating from the site, and groundwater levels from a borehole drilled on the site, both of which contradict that assumption.
The EA’s response can be found here. Whilst disappointing, the EA's letter did leave the door open, saying: "We would be very interested to see any comments from Professor Brassington on the points in this letter." Prof Brassington has now responded to the EA – disputing many of the Agency's conclusions.
Prof Brassington clearly thinks the EA has got it all wrong, in particular the accuracy of the maximum water table and the impact of removing the unsaturated zone.
With respect to the former, he dismisses the comparison with EA observation boreholes:
...the records of observation boreholes across a wide area (Woodbury ED is more than 10 km away) are affected by many factors: different rainfall amounts, geology, depths, neighbouring abstractions, dipping frequency (in the past, most were only dipped monthly), so a competition between observation boreholes has little meaning.
He again points to the Salston stream base flows:
The only conclusion that can be drawn from this hydrograph is that the groundwater levels on the Straitgate Farm site would have been at a higher elevation than those in 2013/14 during the winters of 1976/77 and 2000/01.
He rebukes the EA for ignoring 1990 water levels:
If this value is to be ignored, then, by the same reasoning, all the groundwater data in the table can be regarded as “spot readings” and dismissed in the same way. If this is the way that the data are to be used to review the MWWT, then there can be no confidence in the results and no confidence in the EA either.
With respect to the effect of removing the unsaturated zone, the EA has previously said:
Our main concern previously was the loss of unsaturated zone storage and the potential effect of this on stream flow and private water supplies. The information provided [by Aggregate Industries] gives us sufficient confidence that the rapidity of groundwater flow through the unsaturated zone is such that a reduction in thickness will not result in significant adverse impacts.
Prof Brassington's view, on the other hand, is that such confidence is utterly misplaced:
I do not accept the proposition by Aggregate Industries that the water percolates quickly, so the difference caused by removing almost all the unsaturated zone will make no difference. It will make a great deal of difference.
Again, Prof Brassington's stresses that:
...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
However, he is even stronger in his condemnation of the whole sorry proposal:
I would point out that I remain totally opposed to the idea of this quarrying being allowed to go ahead... In my opinion the proposal that removes most of the unsaturated zone in an aquifer that is fragile is too risky and presents too much of a hazard to the water supplies of a large number of people in addition to those supplies for Cadhay House and its mediaeval fishponds and ancient woodlands.
A copy of Prof Brassington’s letter has now been sent to the EA and DCC.
