Thursday, 10 December 2015

AI’s idea of a 1m standoff

From the start, Aggregate Industries has been persistently evasive about how much sand and gravel it intended to leave as an unquarried buffer above the maximum water table to safeguard private water supplies. Yesterday, at a meeting with a company representative, the truth became crystal clear - and the answer was none. AI wants to take it all. AI’s proposed base of quarry working is simply Amec's maximum groundwater level contours; put 0 metres of "Maintained depth over maximum groundwater" into the resource calculation below and out drops AI’s magical 1.2 million tonnes resource figure:



AI says "pretty much all of the extraction area would require the buffer backfilling as per AMEC modelling" with 1m of top soil and subsoils. How this could ever be restored to best and most versatile agricultural land again is anybody’s guess. How this fits in with the methodology of working half of the resource north to south, and the remainder going back from south to north, if extraction down to the maximum groundwater level is only during the drier summer months, is also anybody’s guess. Why AI didn’t want to come clean in its original application is perhaps clearer.

The truth has taken months to come out. Back in June we wrote that AI wants to quarry down to the water table - of the aquifer that supplies 106 people. We wrote to the Environment Agency, and on 9 July posted Clarification from the EA that said:
Aggregate Industries have proposed to stop quarrying a metre above the water-table. We expect DCC to make this a condition of any permission that is granted.
We said: "In which case, AI should now tell us the size of resource left at Straitgate - the size of the 'benefit' that should be weighed against the proposal's considerable harm. According to AI, the site contained "in the order of 1.2Mt of saleable sand and gravel" 3.8 with mineral extraction to the high groundwater level; a 1m depth of sand and gravel across a 25.6ha extraction area equates to about 0.5 million tonnes."

The same day, however, in email correspondence with DCC, AI mysteriously claimed:
a 1metre depth of unsaturated zone will be retained above the winter water table as per AMEC's technical note.
the calculation of the 1.2Mt reserve was modeled to a surface 1metre above the highest winter water table.
Calculations confirmed, however, that AI was overstating the saleable resource by at least 500,000 tonnes if 1m of unsaturated resource were to be retained. In its Regulation 22 request, DCC asked:
The applicant should demonstrate the methodology which will be used on site to ensure no working within the 1m standoff for the highest measured point of the groundwater in the Budleigh Salterton Pebblebeds - given the acknowledged variations across the site and the concern that there has been no piezometer installed at the centre of the site to monitor ground water levels at that location.
To which, all AI would say was:
The highest groundwater level across the site has been defined from historical data which includes two periods of exceptionally high rainfall which has resulted in particularly high water level conditions. Using this elevation surface to define the depth of the excavation, taking into account any standoff requirement, would therefore be conservative. 3.8
At the end of October, DCC warned AI that:
Given the importance of this point, to you as the proposed operator, and evidently to the MPA and the EA who were both of the understanding that you had agreed to this restriction. I am now asking you to clarify in writing whether you are intending to work to the proposed levels set out in the Amec technical Note to the Policy Team and the EA (and on which their recommendation was clearly based) or whether you wish for the MPA to consider your proposal as working to the highest measured level of the winter water table without the 1m standoff.
You will understand the importance of this point and the need for absolute clarity in your response as it has serious implications for the further progress of this application.
Hence the seven suits that subsequently turned up at the EA. Minutes from this meeting have yet to be published. Our understanding from the EA, however, is that they were not left with the impression that "pretty much all of the extraction area would require the buffer backfilling as per AMEC modelling". Next week*, infiltration tests will be performed at Straitgate at the EA’s request; a technical note will be produced, and another round of consultation will follow in due course. AI's next set of documents will obviously attract even more scrutiny from all concerned.

We’ve addressed the importance of leaving 1m of unquarried material above the maximum groundwater level. We’ve addressed the fact that in some places, operators are forced to leave 2m. We’ve addressed why at Town Farm, a quarry with the same geology but far fewer groundwater users, Hanson said:
The scheme proposes extraction within the Pebble Beds to 1m above the highest recorded water table level. C3.1
AI obviously thinks none of this applies to them. It looks as though its application for Straitgate will be decided on working "without the 1m standoff" - against the previous advice of the EA, against DCC’s draft Minerals Plan, against the advice of Amec, AI's own hydrogeologists. AI will have to convince the EA, planning officers, and members of the Development Management Committee of the merits of leaving nothing but a wing and a prayer to protect the water supplies of 106 people, 3 farms and their livestock, Grade I Cadhay’s mediaeval fishponds and tearooms that serve 2000 people a year.

*Edit: Delayed until 2016