In an apparent change of tack – and rather than just defending an unorthodox scheme put forward by Aggregate Industries to extract as much material as possible from a hydrologically sensitive area – the Environment Agency now thinks it would be "prudent" that DCC asks AI to address the concerns in Professor Brassington’s report and subsequent letter.
We have previously posted that Professor of Hydrogeology says 'ANY quarrying at Straitgate would cause problems' and Professor rebuts EA’s response to his report. Has the EA got it all wrong?
Prof Brassington’s most recent letter concluded:
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.
The EA has now responded to Prof Brassington’s letter, saying:
We consider that it would now be prudent for Devon County Council to engage with the applicant and their consultants to give them an opportunity to respond to the matters raised in Professor Brassington’s original report, our letter of 21 June 2019 and Professor Brassington’s subsequent letter. We will be happy to then review the consultants’ response.
We will recommend to Devon County Council that the following points in particular are considered:
- Implications of the 1976/77 and 2000/2001 Salston stream flow for maximum groundwater levels at the site.
- The rate of infiltration through the unsaturated zone (our interest in this relates to unsaturated zone storage and reduced baseflow in dry periods)
With respect to the first point, the base flow of the Salston stream is an indicator of groundwater levels at Straitgate. Prof Brassington is concerned that:
...the computer model derived MWWT surface [the ‘maximum winter water table’, the base of any quarry] is unlikely to provide an accurate representation of the real maximum groundwater levels.
AI’s consultants had previously argued:
The flow data for Salston are presented in Fig 3.6 which shows the total flow together with the baseflow component of flow calculated using the CEH prescribed 5 day minimum turning point method (Low Flow Studies Report, IoH 1980)… It is clear that very high baseflow occurred in the winter months of 2012/13 and 2013/14 – reflecting high BSPB spring flows (and therefore high groundwater levels). The only previous periods characterised by similarly high baseflow were the winter periods of 2000/01 and 1976/77. 3.3.17
Based on long-term trends, groundwater levels measured at the Site piezometers during the recent winter months of 2013 to 2014 are likely to reflect the highest groundwater levels that may occur at Straitgate. 4.2.10
However, Prof Brassington points to the higher base flows recorded in 2000/01 and 1976/77 and says:
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.
Plainly, this is another setback for AI.
Consider how long the company has been drilling and monitoring boreholes at Straitgate. Consider how very long its consultants have been churning out expensive water report after expensive water report – in an effort to square the hydrological circle at Straitgate.
We recently posted about one of those reports from 2013, where Consultants misled EA in key report to back Straitgate’s inclusion in Minerals Plan. In 2017, we posted about how Amec’s water report has been whitewashed.
If AI had originally proposed to leave at least one metre of unquarried material above the maximum water table to safeguard groundwater – like every other quarry operator where drinking water sources are at risk – it would not, in all probability, still be in this mess. But the company, greedy for the last 1m of resource, instead proposed a zero metre safeguard. Now, having analysed the data, Prof Brassington maintains that – if quarrying were to be permitted against his advice – "a 3 m unquarried buffer should be left above the maximum water table to minimize the negative impacts that I have outlined".
